Chemical engineering education ( Journal Site )

Material Information

Chemical engineering education
Alternate Title:
Abbreviated Title:
Chem. eng. educ.
Physical Description:
v. : ill. ; 22-28 cm.
American Society for Engineering Education -- Chemical Engineering Division
Chemical Engineering Division, American Society for Engineering Education
Place of Publication:
Storrs, Conn
Publication Date:
annual[ former 1960-1961]


Subjects / Keywords:
Chemical engineering -- Study and teaching -- Periodicals   ( lcsh )
periodical   ( marcgt )
serial   ( sobekcm )


Chemical abstracts
Additional Physical Form:
Also issued online.
Dates or Sequential Designation:
1960-June 1964 ; v. 1, no. 1 (Oct. 1965)-
Numbering Peculiarities:
Publication suspended briefly: issue designated v. 1, no. 4 (June 1966) published Nov. 1967.
General Note:
Title from cover.
General Note:
Place of publication varies: Rochester, N.Y., 1965-1967; Gainesville, Fla., 1968-

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
oclc - 01151209
lccn - 70013732
issn - 0009-2479
lcc - TP165 .C18
ddc - 660/.2/071
System ID:

Full Text

t a c .

When you think of Milwaukee,

do you think of this?

There's more to Milwaukee than Laverne and Shirley!

Recently ranked #14 in Fortune Magazine's "Best Cities in Which To Live and Work", Milwaukee is
a city full of amenities with a small town feel. Milwaukee welcomes the 1997 ASEE Annual
Conference and Exposition with exciting festivals, enchanting Lake Michigan, genuine, midwestern
hospitality and an international flair.
At the conference, June 15-18, you'll have the chance to stroll along the Third Street Pier and jump
on the riverboat rides at the Society-Wide Picnic, complete with German cuisine and an authentic
Oompah band! Take a tour of Harley-Davidson or hob-nob with Tommy Thompson, Wisconsin's
governor, at the exposition's Focus on Exhibits reception.
In addition, you can tap your feet to the Mississippi Mudcats at the Awards Banquet, attend the
Plenary Session with internationally-renowned speaker Carol Bartz, CEO of Autodesk, Inc., and take
advantage of the restaurants and shops in Milwaukee's ethnically diverse neighborhoods in your free
These are just of few of the things the ASEE Conference promises! Milwaukee is affordable, scenic,
festive, safe and exciting--'"a greatplace on a great lake". Come alone or bring the whole family! Plan
now to attend June 15-18, 1997! More information will be mailed with the March issue of ASEE
PRISM or visit ASEE's website for info today!

1997 ASEE Annual Conference and Exposition, June 15-18,1997
Milwaukee, Wisconsin

Chemical Engineering Education
Department of Chemical Engineering
University of Florida Gainesville, FL 32611
PHONE and FAX: 352-392-0861

T. J. Anderson

Phillip C. Wankat

Carole Yocum

James 0. Wilkes and Mark A. Burns
University of Michigan
William J. Koros
University of Texas, Austin

E. Dendy Sloan, Jr.
Colorado School of Mines

Gary Poehlein
Georgia Institute of Technology
Klaus Timmerhaus
University of Colorado

Dianne Dorland
University of Minnesota, Duluth
Thomas F. Edgar
University of Texas at Austin
Richard M. Felder
North Carolina State University
Bruce A. Finlayson
University of Washington
H. Scott Fogler
University ofMichigan
David F. Ollis
North Carolina State University
Angelo J. Perna
New Jersey Institute of Technology
Ronald W. Rousseau
Georgia Institute of Technology
Stanley I Sandler
University of Delaware
Richard C. Seagrave
Iowa State University
M. Sami Selim
Colorado School of Mines
James E. Stice
University of Texas at Austin
Donald R. Woods
McMaster University

Spring 1997

Chemical Engineering Education

Volume 31

Number 2

Spring 1997

74 T.W. Fraser Russell, by his Colleagues

80 University of Maine, Douglas M. Ruthven, Andrew Chase

86 What to do if Relative Volatilities Cannot Be Assumed to Be Constant:
Differential-Algebraic Equations Systems in Undergraduate Education,
Neima Brauner, Mordechai Shacham
110 Using the Intranet in ChE Instruction, David W. M. Marr, J. Douglas
116 Development of Oral and Written Communication Skills Across an
Integrated Laboratory Sequence,
James A. Newell, Douglas K. Ludlow, Steven P.K. Sternberg
134 How to Make Questioning Work for You: Effective Questioning in the
ChE Classroom, Kenneth J. Kauffman

94 An Integrated Course and Design Project in Chemical Process Design,
David A. Rockstraw, James Eakman, Nick Nabours, Steven Bellner

100 A Quality-Driven Process Design Internship,
R.M. Counce, J.M. Holmes, S.V. Edwards, C.J. Perilloux, R.A. Reimer

106 Meet Your Students: 7. Dave, Martha, and Roberto, Richard M. Felder

120 Being Dynamic in the Unit Operations Laboratory: A Transient
Fluidized-Bed Heat Transfer Experiment, Brian Priore, Shawn
Whitacre, Keven Myers
124 Introduction to Bioseparations: Affinity Adsorption,
Armando Tejeda, Judn A. Noriega, Arturo Ruiz, Rosa Ma. Montesinos,
Hayded Yeomans, Roberto Gusmdn
130 Providing Industrial Experience in a Regular Laboratory Course,
Robin A. Chaplin

138 A Chemical Engineering Investigative Project for Secondary School
Students, David C. Shallcross

142 CSTR Optimization with By-Product Disposal Costs, Kevin J. Myers

> 108 ASEE Annual Meeting: ChE Division Program
> 137 New Books

CHEMICAL ENGINEERING EDUCATION (ISSN 0009-2479) is published quarterly by the Chemical Engineering
Division, American Society for Engineering Education, and is edited at the University of Florida. Correspondence
regarding editorial matter, circulation, and changes of address should be sent to CEE, Chemical Engineering Department,
University of Florida, Gainesville, FL 32611-6005. Copyright C 1997 by the Chemical Engineering Division, American
Society for Engineering Education. The statements and opinions expressed in this periodical are those of the writers and
not necessarily those of the ChE Division, ASEE, which body assumes no responsibility for them. Defective copies replaced
if notified within 120 days of publication. Write for information on subscription costs and for back copy costs and
availability. POSTMASTER: Send address changes to CEE, Chemical Engineering Department., University of Florida,
Gainesville, FL 32611-6005.

OE educator

T. W. Fraser Russell

An Appreciation by is Colleagues

.W. Fraser Russell is a friend, a guide to his younger .

colleagues at all levels, and a continuous source of
good humor and valuable perspective for all who
know him. He is the Allan P. Colburn Professor of Chemical
Engineering at the University of Delaware and Chief Engi-
neer of the Institute of Energy Conversion, a campus labora-
tory that is devoted to thin-film photovoltaic research. He is
an exceptional teacher who has also served the University as
Chair of the Department of Chemical Engineering, as Asso-
ciate and Acting Dean of the College of Engineering, and as
Director of the Institute of Energy Conversion for 16 of the
25 years it has been in existence.
Fraser was born in Moose Jaw, Saskatchewan, and lived in
various cities in Saskatchewan and Alberta before obtaining
a bachelor's degree in chemical engineering from the Uni-
versity of Alberta in 1956. He put himself through college
by working in an Edmonton oil refinery in the summers.
Although this was valuable practical experience in both labo-
ratory analysis and refinery operating, he had to turn down a
job as lifeguard at the Banff Springs Hotel to complete his
third summer at the refinery. This would not be worth
mentioning were that not the year The River of No
Return was filmed in Banff. Thus, while Fraser
completed the design of a waste treatment unit for
the refinery, his replacement in Banff was hired to
teach Marilyn Monroe how to swim. This dedica-
tion to the practice of engineering has held through-
out Fraser's career.
Upon graduation, Fraser worked for the Research My...My...My.
Council of Alberta on fluid mechanics problems asso-
ciated with the production of oil from the Alberta tar
sands. His first job was the collection of a (probably years gone?
metric) ton of tar sands from a site on the Clearwater
River north of Edmonton. He and two colleagues
brought the sand out by canoe. This early pragmatic
work in mass transport was short term and his princi-
pal research effort was directed toward an under-
standing of the pipeline flow of the very viscous tar
sand-crude oil-water mixtures. This research pro-
duced the first papers published on liquid-liquid Copyright ChE Division ofASEE 1997
74 Chemical Engineering Education


flow in pipes and was accepted by the Uni-
versity of Alberta as meeting the research
requirements for a master's degree, which
Fraser was awarded in 1956.
Fraser, his wife Shirley, and their two-year-
old son Bruce left Edmonton in the summer of
1958 and proceeded to Montreal (in a 1956
Volkswagen "Beetle") to a position as a design
engineer with Union Carbide Canada. This firm
had just moved into Canada and had assembled
a group of Canadian engineers to design and
build a petrochemical plant to make ethylene-
derived chemicals in Montreal East. Fraser was
assigned the task of designing a facility to make
ethanolamines and glycol ethers using informa-
tion from a batch processing unit at the Montreal
plant. The preliminary design and economic
justification was completed in Montreal, and
Fraser and his family were sent to Houston to
complete the process design and equipment
specification. This was done with the help of
Union Carbide International and Brown and
Root-the result was a multipurpose continu-
ous processing unit designed to make mono-,
di-, and triethanolamines and methyl, ethyl, and
butyl glycol ethers-the first multipurpose con-
tinuous processing unit built in Canada.
Union Carbide's policy to make as much use
of Canadian personnel as possible required that

Fraser's career is
characterized by a
close relationship
with industry,
and he has
always strongly
believed that one
cannot effectively
teach engineering
understanding the
art aspect of the
profession ....
He also feels that
the techniques
required to
organize research
results into a form
suitable for
teaching students
are the same as
those required to
information in a
form usefulfor

Fraser, Shirley, Bruce, and three-month old Brian move to
Calgary, Alberta. Fraser supervised the piping design and
drafting phase of the job in Brown and Root's office-
despite the fact that his undergraduate drawing courses con-
centrated on drawing bolts in India ink and never men-
tioned piping (this has always annoyed him). The project
was brought back to Montreal in the fall of 1960 and,
after a winter of Fraser's construction supervision, the
plant was started up in the spring, producing on-spec
product within 24 hours. It did so for over 35 years and
was just recently decommissioned.
Shirley and Fraser then executed a plan they had devel-
oped over several years and began investigating the possi-
bility of graduate education. The presence of Art Metzner
and Bob Pigford at the University of Delaware, coupled
with its location in a small university town with good schools
and a low cost of living, led them to apply to Delaware.
Fraser, together with his family (Shirley, Bruce, Brian,
and month-old Carey) came to Newark, Delaware, in the fall
of 1961. The adjustment to an academic environment pre-
sented many challenges, not the least of which was over-
coming failure of two of the three qualifying exams on his
first attempt. A supportive faculty, and many study sessions
Spring 1997

with his fellow graduate students, taught him
to effectively integrate his exceptional prac-
tical experience with the academic approach
to chemical engineering, and he passed the
exams laudably on his second try. He is par-
ticularly grateful to Jack Hopper, John
Gainer, and Don Kirwan, all of whom be-
came chemical engineering faculty.
Fraser was asked to teach the senior cap-
stone design course in his last year as a gradu-
ate student, and his success in so doing
prompted Bob Pigford to offer him a posi-
tion as an assistant professor (he is the only
person who received his PhD at Delaware
who has been invited to stay as a faculty
member-and, as Fraser says, "You can
analyze that one of two ways."). His ex-
perimental thesis on "The Flow Mecha-
nism of Two Phase Annular Flow" was
directed by David Lamb, and the degree
was awarded in 1964.
His early research efforts at Delaware were
driven by a desire to quantify a whole class
of reactor design problems in which ethyl-
ene oxide was reacted with water, ammonia,
and various alcohols. Fraser and one of his
early graduate students, David Buzzelli, stud-
ied this problem and published "Reactor
Analysis and Process Synthesis for a Class

of Complex Reactions." At that time, Fraser was also con-
sulting with Union Carbide Canada on the expansion of the
multipurpose facility in Montreal, and this gave him and
another early graduate student, Robert Anderson, the oppor-
tunity to use the Buzzelli paper to design new reactors for
this unit. The new reactors gave Union Carbide a distinct
competitive edge over its chief rival, Dow Canada. Years
later, David became CEO of Dow Canada, and thus had to
deal with a competitor that had been wise enough to follow
the design procedures he developed as a student. He must
have done so successfully because David is now VP and
Corporate Director for Environment, Health, and Safety
at Dow. In an even more curious turn of events, at the
same time that Dave was responsible for Dow Canada,
the same Robert Anderson was the Union Carbide man-
ager for the Montreal plant!
Fraser also combined industrial process design experience
with work on two-phase fluid mechanics to develop a re-
search program emphasizing experiments that produced es-
sential information for the design and operation of commer-
cial-scale process equipment. This experimental research
and modeling effort, resulting in an early series of papers
coauthored with Anderson, Schaftlein, Cichy, Ultman,

Rogers, Jensen, Arruda, Etchells, and Holmes, was well
received by a number of industrial organizations and the
findings were incorporated into many of their design proce-
dures. This group's organization of gas-liquid design prob-
lems into tank-type and tubular categories proved valuable
to both design engineers and stu-
dents. It also led to a long-term con-
sulting contact with the Engineering
Department of the DuPont Company
(now in its 26th year) and gave
Fraser's students an opportunity to
test the conclusions of their experi-
mental work and modeling efforts in
the design and operation of com-
mercial-scale equipment.
Fraser's career is characterized by
a close relationship with industry,
and he has always strongly believed
that one cannot effectively teach en-
gineering without understanding the
art aspect of the profession. He de-
fines this as an ability to make deci-
sions within severe time constraints
and with uncertainties in the avail-
able information. He also feels that
the techniques required to organize
research results into a form suitable
for teaching students are the same as
"Just for fun." Shir
those required to prepare informa- "Just for fun." Shir
tion in a form useful for practic- and Carey
ing engineers. This approach to
both teaching and engineering practice has earned him
several honors, including a University of Delaware Teach-
ing Award, the AIChE Award in Chemical Engineering
Practice, and the Thomas H. Chilton Award (from the
AIChE Wilmington Section).
A quote from J. R. Balder's presentation of the Chilton
Award to Fraser in May of 1988 captures the essence of
Fraser's contribution to industrial practice:
Dr. Russell has contributed through his research and
publications to the solution of a whole class of problems
related to multiphase fluid flow. I can speak from personal
knowledge about Dr. Russell's industrial contributions,
and I am not referring to people just reading his papers
and applying his results. For the past twenty years he has
spent between a half to a full day each week, as a member
of our internal consulting group in heat, mass, and
momentum transfer. He consults with our own consultants
on their technical problems, and he also has a series of
clients at DuPont's manufacturing sites for whom he is the
engineering department consultant in multiphase process-
ing. He is on the front line solving problems every week,
and in fact one of the strongest impressions that Dr.
Russell leaves with those who work with him is his
practical orientation to the science of engineering.


(It is interesting to note that J. R. Balder was a student in
the first class in design that Fraser taught.)
Fraser has also had multi-year consulting relationships
with the Ethyl Corporation, Pfizer, and over twenty other
firms or organizations for shorter periods.
Fraser was promoted to Associate
Professor in 1967 and to full Profes-
sor in 1970. During this time, he
devoted a great deal of effort to re-
design of the traditional first course
in chemical engineering. Fraser and
Mort Denn tackled the problem with
the considerable talent and experi-
ence they possessed between them
(see Mort's comments in the sidebar
opposite). For six years they taught
the course in two sections so they
could compare notes on the class-
room effectiveness of the material
being developed. This collaboration
produced the text Introduction to
Chemical Engineering Analysis,
which has been described in the
pages of this journal by two articles,
the first in the summer issue, 1973,
and more recently in an article about
Mort Denn (spring issue, 1996).
Fraser, Brian, Bruce, Fraser convinced his wife, who
uary 1980) was studying for a master's degree
in secondary math education at Dela-
ware, that she could not effectively teach math without un-
derstanding how it was used. So Shirley registered for the
course-attending Fraser's lectures, but with homework and
exams graded by Mort. She says she thought she could give
Fraser advice on how to be a more effective teacher, and
Fraser thought he could get good solutions of the homework
problems. In fact, both occurred. Shirley's enthusiasm for
the approach and her success in mastering the material (she
was one of the top three students) promoted the development
of a course in chemical engineering analysis for nonmajors.
This course attracted a wide variety of students and was
taught both as an on-campus offering of the Chemical Engi-
neering Department and as a Continuing Education course.
A very satisfying sabbatical year in 1972-73 at the Swiss
Federal Institute of Technology (ETH) in Zurich produced a
collaboration with Irving Dunn and Harvey Blanch. A re-
search effort developed that followed earlier work on sew-
age treatment in transfer lines and involved designing, build-
ing, and conducting experiments in a two-phase tubular loop
reactor in the ETH labs. Together they successfully pro-
duced C. topicalis and developed a reaction and reactor
analysis for the system. At Fraser's urging, the department at
Delaware hired Harvey, where he subsequently received
Chemical Engineering Education

Comments from Mort Denn

For my first teaching assignment, Bob Pigford asked me to develop a
new course on mathematical methods to follow immediately after the
introductory "mass and energy balances" course. (By a historical acci-
dent, a differential equations course was not a formal part of the Dela-
ware chemical engineering curriculum although all our students took
differential equations-so there was no campus political issue in remov-
ing our students from an existing math course.)
Fraser took an immediate interest, and after the first offering of the
new course we decided to work together to integrate the two courses into
a year-long sequence. We soon realized that the most serious problem
faced by our students was not poor ability in formal mathematics (which
certainly existed), but rather a lack of appreciation of how to quantify
physical problems. We cut back significantly on the mathematics and
began to develop a systematic approach to translation of physical prob-
lems into mathematical form. (I'd like to call it "mathematical model-
ing," which it is, but that term has a negative connotation to many of our
Fraser and I developed our program with a few key ideas in mind; the
material covered in basic science and math courses should be used and
reinforced in our chemical engineering course (Fraser kept copies of all
the textbooks used by our students and cited them frequently in class.)
The most easily understood physical processes are those in the liquid
phase, and keeping to the liquid phase enables the introduction of dynam-
ics at the start. Chemical reaction and mass transfer can be developed
effectively at the introductory level, creating avenues of understanding
about the full scope of chemical engineering and enabling students to
attack simple design problems in the first course. Fraser's design experi-
ence was very helpful in focusing on meaningful problems, which inevi-
tably meant that rate processes had to be included in the problem formu-
lation, since the rate processes play a central role in any real design. (This
was a major departure from traditional introductory courses in chemical
For a number of years we taught the course in two morning sections,
covering the same material in each section and getting together for tea
after class to evaluate and plan. In time, the year-long course evolved to
the material covered in our text Introduction to Chemical Engineering
Analysis. With the reintroduction of a formal course in differential equa-
tions, much of the later mathematical content became redundant and the
analysis course is again a one-semester course, but totally different from
the old mass and energy balances course. It is notable that most of the
essential concepts are taught with separable first-order differential equa-
tions, so calculus is used extensively, but only a first course in calculus is
It is not possible to overstate Fraser's contribution to this effort. He has
an uncanny understanding of the way in which students learn difficult
material, and he defined the pace at which ideas were introduced-very
slowly at first, to build confidence, then accelerating rapidly. (A typical
Russell comment: "Do you want to cover everything or do you want
them to learn something?") While his lecturing style is very low key, he
has a wonderful way of relating to each student, and they learn from him.
I still recall with chagrin the year in which my students were consistently
doing more poorly on exams than Fraser's. Since the material covered in
each section was identical, the obvious conclusion was that he had, on the
average, better students. But I note sadly, if one is to accept the predictive
ability of the freshman GPA, it was I who had the better students!

Spring 1997

part of the experience that made him so attractive
later on to the University of California at Berke-
ley. Since Mort also ended up at Berkeley, Fraser
often wonders why collaborations with him pro-
duce this urge to go west!
In the mid-1970s, Fraser was asked by Irv
Greenfield, a newly appointed Dean, to take on the
responsibilities of the Associate Dean of the College
of Engineering. Fraser claims he accepted so he could
have access to his own secretary, but his three years at
this task produced the beginnings of what is now a
very successful minority engineering program, the
introduction of computers into the education programs
of the college, a revision of the student advisement
process, support for teaching excellence in the Col-
lege, and an upgrading of the academic program in all
the departments. He was also responsible for initiat-
ing and supervising an intern program in chemical
engineering design, a master' s-level program for chem-
ists, a partnership program for chemical process de-
sign, and a bachelor's-master's program for excep-
tional undergraduates.
Fraser's belief that one could not ask students to
take the fundamentals exam for professional registra-
tion unless someone in the Dean's Office was a regis-
tered professional engineer led him to attempt to get
the Delaware Association of Professional Engineers
to recognize his Quebec registration. He was not suc-
cessful, and twenty years after he graduated he took
and passed both the eight-hour fundamental and eight-
hour professional exams in order to reinstate his pro-
fessional registration. After doing this, he concluded
that better exams would be written if all faculty had to
take an exam every so often.
It was during his time in the Dean's office that
Fraser and Jim Wei, assisted by M. Swartzlander,
developed both a research and teaching program in
the economics of the chemical process industries.
This produced a text, Structure of the Chemical Pro-
cess Industries, as well as a successful course (de-
scribed in the Fall 1979 issue of this journal). Three
papers applying microeconomics theory to process
design were also produced as a result of this collabo-
ration, as well as the thesis research of Ricardo Bogaert
and Dennis Brestovansky.
Fraser ended his tenure in the Dean's Office by
serving a year as Acting Dean. His effective leader-
ship of the College prompted the university adminis-
tration to ask him to take the directorship of a troubled
laboratory devoted to photovoltaic and other renew-
able energy research. Thus, in the fall of 1979, he
became the first Director of the Institute of Energy
Conversion (IEC).

Fraser directed the IEC during a critical period in the early
1980s, during which federal support for photovoltaic re-
search was reduced from over $150 million to around $40
million annually. Despite this drop in federal funding, he
developed a stable and effective research organization that
between 1979 and 1996 received over $20 million in federal
funds, over $3 million from industry, and over $600,000
from the State of Delaware. Money was also raised for a new
40,000 square-foot laboratory facility built in 1982.
During his tenure as Director, the IEC research program
was reorganized to concentrate on developing, implement-
ing, and analyzing the laboratory experiments required to
provide essential information for the manufacture of large-
area photovoltaic modules. This integrated approach encom-
passed materials synthesis, process equipment design and
operation, and device design and analysis. It allowed the
engineers and scientists at IEC to make many significant
contributions to thin film photovoltaic technology. These
contributions include
* Expansion of the number of thin-film photovoltaic materials
designed, fabricated, and analyzed at IEC to include
cadmium telluride, copper indium diselenide, and amorphous
Achieving efficiencies of laboratory-scale solar cells of
between 10 and 15%for all of the above materials;
Developing twenty-three patents in thin-film photovoltaic
technology, along with several hundred technical publica-
Development of a reaction and reactor analysis research
program carried out in conjunction with the Department of
Chemical Engineering that led to the design, fabrication, and
operation of the first pilot-scale reactor for continuous
deposition ofphotovoltaic-grade semiconductor material
onto a moving substrate.
Fraser dubbed the above research effort "photovoltaic unit
operations," and it was carried out in cooperation with Bill
Baron, a physical chemist at IEC, and a group of students
including Rick Rocheleau, Dennis Brestovansky, Ricardo
Bogeart, and Scott Jackson. This effort was recognized by
the Leo Friend Award for the best paper in CHEMTECH,
"Photovoltaic Unit Operations," and the ASEE Chemical
Engineering Division 3M Lectureship Award.
The editor of CHEMTECH, Ben Luberoff, also commented
on this in an editorial:
But the paper by the University of Delaware's T. W.
Fraser Russell-the 1982 Leo Friend Award winner-is a
lot more than just another energy paper. I see it as a vane
pointing the direction of at least American chemistry. In
his Colburn Chair lecture, on which the winning paper
is based, Russell opens the door to the kind of technol-
ogy that will be required as we turn our attention from
making "stuff" to making "things "-in this case
copper cadmium-sulfide solar cells. Russell's continu-
ous process involves not only classical chemical

His effective leadership of the College
[of Engineering] prompted the university
administration to ask him to take the directorship
of a troubled laboratory devoted to photovoltaic
and other renewable energy research. Thus, in
the fall of 1979, he became the first Director of
the Institute of Energy Conversion (IEC).

technology, but lots of surface science.
Fraser has recently expanded the reaction and reactor analy-
sis with colleagues N. Orbey and R. W. Birkmire, and stu-
dents R. Varrin and S. Verma, to include the first reaction
analysis of the growth of copper indium diselenide. This is a
study essential to a major consortium research and develop-
ment effort that has as its goal the construction of an inte-
grated pilot line to make copper indium diselenide modules
on flexible substrates.
As Director, Fraser strongly supported the educational
component of IEC's solar-cell research, and he actively en-
couraged undergraduate and graduate students to carry on
research with IEC's professional staff and faculty. This em-
phasis on education produced twenty PhD and over fifty MS
graduates who have research experience in photovoltaics. In
addition, over fifty professionals now active in the photovol-
taic industry received their training at IEC.
IEC's significant contributions were further recognized by
the United States Department of Energy in 1992 when it
designated the laboratory as a University Center of Excel-
lence for Photovoltaic Research and Education, an award
given to only two institutions in the United States. IEC is the
only University Center of Excellence supported by the Na-
tional Renewable Energy Laboratory.
Despite the administrative demands of leading a labora-
tory with between forty and fifty faculty, professional and
technical staff, and of his development of the photovoltaic
unit operations research, Fraser continued studies of gas-
liquid fluid mechanics. These studies were sponsored by the
Design Institute for Multi-Phase Processing, an AIChE co-
operative research effort funded by the industrial firms in the
chemical processing industry. This phase of Fraser's re-
search was carried out in close collaboration with A.W.
Etchells, a consultant in DuPont's Engineering Department
and Fraser's former student. Jim Tilton, Zenaida Otero, Robert
Hesketh, and Fraser produced a series of papers on bubble
break-up and design of commercial-scale tank-type mass
contractors that have been well received; the validity of the
design methods employed was verified using data from a
multi-acre sized commercial waste disposal facility.
In 1986, Fraser was asked to become Chair of Chemical
Engineering, a position he held for a five-year term while
continuing to direct the IEC. Fraser says he could not have
dealt with the administrative load if he had not had an
Chemical Engineering Education

A Shirley and
Fraser take a break
at the European
Photovoltaic Confer-
ence in 1989.

> Fraser accepts the I
University of
Delaware's Alison
Award (1990)

extremely competent staff in both organizations. It is typical of Fraser's
concern for his staff that he publicly acknowledged the exceptional efforts
of his first IEC secretary, Sheri Barwick, and the IEC Manager of Opera-
tions, Margaret Stallings, in his ASEE Award lecture publication in this
journal. He is particularly appreciative of the two executive secretaries,
Linda Huber in Chemical Engineering and Paula Newton at IEC, who
worked closely with him and each other to give him the needed freedom
from administrative detail to continue his teaching and research.
Fraser has turned down many opportunities to assume upper-level ad-
ministrative positions in universities. He has done so because he feels that
his most significant impact on chemical engineering has been in the class-
room, and over the past few years he has begun to put much more time into
these activities. In 1991, he and Nese Orbey supervised a DuPont Teaching
Fellow, Linda J. Broadbelt (now an Assistant Professor at Northwestern
University), in an undergraduate course in kinetics and reactor design. The
DuPont Teaching Fellows Program and the experiences of the six Fellows
were described in the Fall 1993 issue of this journal. An excerpt from
Linda's write-up regarding her interaction with Fraser reads:
Dr. Russell sat in on most of my lectures and gave me excellent feedback
about nmy style and the students' reactions. He was also an invaluable
resource during a lecture, providing knowledge and insight from his
years of experience. Having such an active and interested mentor was
the most crucial element in making my teaching experience so
Spring 1997

rewarding and successful.
His colleague, Nese Orbey, describes Fraser
as a born teacher who creates a classroom envi-
ronment (with a relaxed atmosphere) that culti-
vates participation and self-esteem while pro-
moting higher-level reasoning and creative think-
ing. His style is much appreciated by colleagues
and academic candidates he has mentored. She
also notes that perhaps the most difficult part of
working with Fraser is to be always reminded-
and sometimes forced-to walk at least five miles
daily and to "eat your veggies."
Fraser has served the chemical engineering
profession through his membership on the AIChE
Awards Committee and its Education and Ac-
creditation Committee, where he also serves as
an ABET visitor. He and Stan Sandler orga-
nized, co-chaired, and raised funds for the sup-
port of the 1982 Summer School for Chemical
Engineering held at the University of California
at Santa Barbara. He has published over ten
articles in Chemical Engineering Education and
other ASEE publications.
Raising three sons always kept the Russell
family engaged in various outdoor activities, and
time each year was spent hiking, sailing, snor-
keling, diving, skiing, and canoeing in locales
ranging from the Florida Keys to Baxter Park in
Maine, and from the Appalachian Trail to the
Colorado and Alberta Rockies. Highlights of
those trips include a two-week cruise of the Vir-
gin Islands (sailing their own boat), three months
in Western Europe in the 1970s traveling and
camping in a VW camper, a fourteen-day trek
along the Walkers High Route from Chamoix in
France to Zermat in Switzerland, and a one-day,
thirty-kilometer hike from the top of Haleakala
(Hawaii) through Kapo Gap to the ocean (3500
meters drop in elevation).
The National Academy of Engineering elected
Fraser a member in 1990, the same year the
University of Delaware designated him as Francis
Alison Scholar-an honor held by only 16 of
some 1000 faculty. His most recent honor was
designation as the ICI Distinguished Lecturer at
the University of Alberta. This not only gave
him an opportunity to speak on his theme of the
critical need for creative laboratory-scale ex-
periments for commercial-scale equipment de-
sign, but it also provided an opportunity to visit
with his two-year old grandson, Quinn, who was
just recently joined by a new granddaughter,
Skye. 0

j department


University of Maine Orono, ME 04469-5737

he University of Maine was
established in 1868 as a
Land Grant College (The
Maine State College of Agriculture
and Mechanic Arts), but in its early
years enrollments were very small.
The first graduating class (1872)
numbered only 6, although by 1876
it had reached 33 and by 1911 it
numbered 140 (including 15 stu-
dents who were awarded Master's
degrees). Today, with about 10,000
students, the University of Maine is
still not large by state-university
standards, but it is the only
multidisciplinary university in
Maine as well as the only one to
offer a full engineering program.
The College of Engineering has
about 1200 students in all, includ-
ing 138 graduate students and about
300 students enrolled in Engineer-
ing Technology. Somewhat unusu-
ally, chemical engineering (with 180
undergraduates and 30 graduate stu-
dents) is the largest of the engineer-
ing departments.

Some important milestones in the
history of chemical engineering at
U Maine are listed in Table 1. The
first program in chemical engineer-
ing appeared in the catalog in 1908,
the year in which AIChE was

Figure 1. Jenness Hall and the Soderberg Center (right).

founded, and the first ChE degrees were awarded in 1911. At that time, chemical
engineering was part of the Chemistry Department and, in common with most ChE
programs of that era, the course content was essentially what we would now call
"applied chemistry." In the early 1920s, an MS program was introduced, and (following
the lead of MIT) courses titled "Unit Operations" appeared in the undergraduate
The founder of the modern department, Lyle C. Jenness (in whose honor the chemical
engineering building is named), was appointed to the faculty in 1926 (see Table 2). He
served as a faculty member for forty years, the last twenty of them (1947-1966) as
Department Head.
Chemical engineering became a separate Department in 1946, but for the next twenty-
five years it continued to be housed, with the Chemistry Department, in Aubert Hall. A
separate ChE building, Jenness Hall, was completed in 1972, but some of the laborato-
ries remained in Aubert Hall until 1986 when, with a substantial extension to Jenness
Hall, the Department was finally accommodated at a single location. A second exten-

* Andrew Chase is Professor Emeritus of Chemical Engineering, having served on the U Maine faculty from 1949 to 1982.
@ Copyright ChE Division ofASEE 1997
80 Chemical Engineering Education

'.-.; '

S. through the shrewdness and foresight of its founders ... and with the generous help
and support of the Foundation, U Maine has become an important niche player,
providing a supply of well-trained and capable graduates with a special
focus on the needs of the pulp, paper, and associated industries
and acting as a center for fundamental research on problems
of practical concern to that industry.


sion to Jenness Hall, to provide a state-of-the-art lecture
room and conference room with distance education facili-
ties, as well as an extension to the Pilot Plant, is due to open
in April, 1997.
Throughout most of its history, the Department has been
closely linked with the paper industry and its present success
is due in no small measure to the generosity of donors from
that industry. The first course in pulp and paper technology
appeared in 1913, but it was Lyle Jenness who first fully
appreciated the importance of focusing on the needs of this
industry. He seems to have been among the first to recognize
that the paper industry involves a wide range of standard
chemical engineering operations, and that to meet its staff-
ing requirements, the industry needed broadly trained chemi-
cal engineers rather than narrowly trained paper technolo-
gists. The U Maine Pulp and Paper Foundation was estab-
lished in 1950 and incorporated in 1953 through the efforts
and generosity of twelve alumni, all of whom had risen to
important positions in the industry (see Table 3). Of particu-
lar note are J. Larcom Ober, whose generous bequest in 1990
financed the Ober Professorship, and Frederic Soderberg,
who bequeathed $4.3 million to the Foundation in 1993 (of
which about half has been used to finance the final phase of
the Jenness Hall expansion and the Soderberg Center).
Since 1970, the Foundation has been managed by Mr.
Stanley Marshall, Jr., as its Executive Director. The annual
income is now about $800,000, of which about half is de-
voted to merit-based student scholarships. Many, but by no
means all, of these scholarships go to chemical engineering
students-a significant number of students in other engi-
neering disciplines are also supported. The Department also
receives direct financial support of about $200,000/year from
Foundation sources.
In addition to financial support, the Department is the
beneficiary of a finely tuned recruiting program mounted by
the Foundation to attract top high school graduates to engi-
neering in general and to chemical engineering in particular.
In addition to an extensive series of high school visits, a
short residential course is organized during the summer for
Spring 1997

ChE Department Milestones
1908 First courses in ChE listed in UM catalog
1911 First ChE degrees awarded
1923 MS program introduced
1926 Lyle C. Jenness appointed to faculty
1946 ChE formally separates from chemistry; Roy Whitney appointed head of ChE
1947 Roy Whitney resigns; Lyle C. Jenness appointed Head (retired in 1966)
1948 AIChE Student Chapter formed; first female ChE graduate
1950 UM Pulp and Paper Foundation established by 12 UM alumni (incorporated
formally in 1953)
1951 ChE program accredited by AIChE
1958 Major extension to laboratory facilities at Aubert Hall
1960 Gottesman Computer Center established in ChE (first computer center on
1962 PhD program introduced
1972 Department moves to its own building-Jenness Hall
1973 Cooperative work experience program introduced
1986 Jenness Hall extension to accommodate ChE laboratories and Pilot Plant
1997 Soderberg Center and Pilot Plant extension to Jenness Hall

Profile of Lyle C. Jenness

Born November 1, 1900; South Danbury, NH
Education BS, Chemical Engineering; UNH, 1922
MS, Chemical Engineering; UM, 1925
D.Phil. (Honorary); UNH, 1966
Teaching Career Depts of Math and Chemistry; UM, 1923-26
Chemical Engineering; UM, 1926-66
Head of Chemical Engineering; UM, 1947-66
Deceased May 4, 1986, in Orono, ME

Founding Members of UM Pulp and Paper Foundation
Articles of Incorporation signed on 27th of July, 1953, at Orono, ME

Vice Presidents


J. Larcom Ober:
Frederic A. Soderberg
Walace B. Parsons
Henry W. Fales
Ralph A. Wilkins
George D. Bearce
Philip S. Bolton
John S. Calkin
Thomas G. Mangan
Harold Holden
M.C. McDonald
Raymond W. Davis

V. President, Scott Paper Co..
V. President, Huyck Felt Co.
Keyes Fibre Co.
St. Croix Paper Co.
Bird and Son, Inc.
St. Regis Paper Co.
Robert Gale Company
University of Maine
International Paper
Eastern Fine Paper
Great Northern Paper Co.
Robert Fibre Co.

top-ranked high school juniors. The students spend a week
on campus taking part in a series of activities, including
selected experiments, to introduce them to chemical engi-
neering (see Figure 2).
The State of Maine ranks 46/50 in per capital funding of
higher education and 50/50 in research funding. Without the
support of the Foundation, it would not have been possible
to develop and support a high-caliber, nationally competi-
tive chemical engineering program.

The BS program, which last re-
ceived full ABET and AIChE ac-
creditation in 1995, is summarized
in Table 4. One hundred and thirty
credit hours are required for gradua-
tion, and the course structure and
content, including general education
requirements, are similar to most US
university programs. Communica-
tion skills and teamwork are em-
A special feature of the program -
is the emphasis on cooperative work
experience that takes place in the
junior year. Between completion of
the sophomore year in May and the
start of the senior year the following
September, students spend two four-
month periods in industry, separated
by one regular term (either fall or
spring) on campus in Orono and
three months of summer school to
pick up key courses missed during
the internship period. The benefits Figure 2. Robert Bile
of this program are mutual since it left), a PhD student, as
provides employers access to a pool school juniors with a
of capable, trained manpower on ment.
what amounts to a trial basis, and it provides students with
valuable practical experience and an insight into the oppor-
tunities and challenges faced by a junior engineer. More than
85% of the students select the co-op option, even though it
involves significantly more work. The benefits are clearly
apparent from the hiring statistics, which show that the co-
op graduates almost invariably receive the earliest and usu-
ally the best offers of permanent employment.
In addition to the usual unit operations laboratory, the
Department has a fully equipped pulp and paper laboratory,
which is used as a teaching laboratory (for pulp and paper
courses), as a testing service in conjunction with the Pilot
Plant, and for research. The Department has always made it
clear that we offer a general chemical engineering program
rather than a program in pulp and paper. Nevertheless, the


curriculum does allow for a modest degree of specialization
through the choice of technical electives. Furthermore, most
of our industrial partners (who provide the places for co-op
students) are associated with this industry, defined in its
broadest sense to include the equipment and materials sup-
pliers as well as the companies actually involved in pulp and
paper production. The industrial base of the state is heavily
dependent on the pulp and paper industry, so it is hardly
surprising that the majority of U Maine chemical engineer-
ing graduates eventually find employ-
ment in this industry.
Student numbers have shown steady
growth over the years and, with a fresh-
man class of about 50 and graduating
classes of about 35, we are now approach-
ing full capacity. The first female to com-
plete the program graduated in 1948, but
until the late 1970s, the number of fe-
male graduates remained relatively small.
The proportion of female graduates has
increased rapidly in recent years and now
amounts to about 35%. Our program has
gained a reputation as one of the more
challenging on campus, and the appar-
ently high attrition rate is accounted for
mainly by transfers to less demanding

The MS degree in chemical engineer-
ing was introduced in 1923 and the PhD
in 1962, but a significant emphasis on
graduate studies and research developed
only in the 1970s. Today, the Depart-
u (second from ment has approximately 30 graduate stu-
a group of high dents divided almost equally between the
draulics experi- PhD and MS programs. The Foundation
provides financial support for up to five
first-year graduate students and this goes a long way toward
solving the problem of how to fund first-year students before
they select a research project. About two-thirds of the gradu-
ate students are citizens or permanent residents of the US.
This is a much higher proportion than in most chemical
engineering departments, in part as a result of a policy re-
stricting the use of Foundation funds to the support of Ameri-
can students.
Perhaps the defining feature of the research program is its
close collaborative relationship with industry. The Depart-
ment has well-equipped research laboratories that include
major items, such as an NMR spectrometer and an environ-
mental scanning electron microscope, that are not commonly
found in chemical engineering departments. In addition to
the usual small-scale laboratory equipment, there is a fully
Chemical Engineering Education

equipped paper-making Pilot Plant, valued at approximately
$5 million. The research program is funded at a level of
about $1.2 million/year, of which about two-thirds comes
directly from industry and the remaining one-third from
government sources. In addition, the Pilot Plant generates
about $600,000/year from industrial contracts.
Two of the major research groups (Paper Surface Science
and Recycle Fiber Technology) are structured as industrial
research partnerships in which the member companies (27
companies between the two consortia) pay an annual fee to
support research in the designated area. This provides a
steady base of financial support at about $400,000/year for
the two programs. Research results are distributed to the
members prior to publication and are reviewed at meetings
of the consortium, held two or three times a year. These

The BS Chemical Engineering Program at UM

First Semester
Analytic Geometry and Calculus
Chemical Principles I / Lab
Physics for Engineers and Physical Scientists I
Introduction to Chemical Engineering I
Humanities/Social Sciences Elective
Total Hours

First Semester
Analytic Geometry and Calculus
Organic Chemistry Lecture I
Organic Chemistry Laboratory I
Fundamentals of Chemical Engineering
Humanities/Social Sciences Elective

Total Hours

First Semester*
Physical Chemistry I
Elements of Chemical Engineering I
Process Control
Chemical Engineering Thermodynamics
Statics and Strength of Materials
Total Hours

First Semester
Computer-Aided Process Design
Elements of Chemical Process Design
Chemical Engineering Seminar
Chemical Engineering Laboratory II
Technical Elective II**
Humanities/Social Sciences Elective
Total Hours

Second Semester
Analytic Geometry and Calc
Chemical Principles II / Lab
Physics for Engineers and P
Introduction to Chemical En
Humanities/Social Sciences
Total Hours

Second Semester
4 Intro. to Diff. Equations and
3 Organic Chemistry Lecture
2 Electric Circuit Fundamenta
4 Chemical Engineering Ther
3 Statistics for Engineers
Humanities/Social Sciences
16 Total Hours

Second Semester*
4 Physical Chemistry II
4 Elements of Chemical Engi
3 Chemical Engineering Labo
3 Chemical Engineering Kine
3 Technical Elective I**
17 Total Hours

meetings provide a forum for comments and feedback from
the industrial partners as well as an opportunity to suggest
additional critical experiments and to propose future re-
search directions. They also provide a useful forum for gradu-
ate students to meet and talk with their industrial sponsors,
who frequently have a somewhat different perspective. In
several instances, the relationships established in this way
have led directly to offers of employment. Further details of
these, and other research activities follow.

Paper Surface Science Program
(Profs. LePoutre and Bousfield; ten students)

The emphasis of this program, supported by a consortium
of fifteen companies, is on developing a fundamental under-
standing of surface treatment processes such as paper sizing,
coating, printing, and gluing. This re-
quires detailed studies of both the phys-
ics and chemistry of the surface interac-
tions and the fluid mechanics of fluid-
paper contacting. Since the fluids in-
volved are generally non-Newtonian sus-
ulus 4 pensions, the theological and fluid me-
4 chanical problems are complex. Recent
physical Scientists II 4 studies have focused on several different
gineering II 2 issues. For example, print gloss is a criti-
Elective 3
17 cal indicator of the quality of the final
printed page. A laser-beam system has
been developed to monitor the ink-gloss
* Linear Algebra 4 dynamics starting at 0.1 sec after the print-
II 3 ing nip. Analysis of the surface-tension
ls 3 driven leveling of the ink filaments re-
modynamics 1 3 veals that the filament diameter has a
Elective 3 critical impact on the final gloss level.
19 The structure of a paper coating depends
on the pigment type, the proportion of
latex or water-soluble binders, and the
4 mode of application and drying. System-
neering I 4 atic studies of the effects of key vari-
iratoryI 2 ables have been carried out using light
tics 3
3 scattering techniques to monitor the po-
16 rosity and roughness of the surface.

Second Semester
3 Process Design Projects 4
3 Chemical Engineering Seminar 1
0 Technical Elective III** 3
2 Humanities/Social Sciences Elective 3
3 Humanities/Social Sciences Elective 3

Total Hours

*Co-op students are absentfor either the Fall or Spring semester of the junior year. The necessary
courses are picked up during two summer school sessions to allow graduation in four years.
** Technical electives include the polymer sciences sequence, the control sequence, the pulp and
paper sequence, or any of the 500-level graduate courses.

Spring 1997

Cooperative Recycled Fiber Studies
(Prof Thompson; five students)

The overall aim of this program, sup-
ported by a consortium of twelve compa-
nies, is to provide fundamental research
to support and supplement the paper
industry's own research and development
efforts in relation to the problems associ-
ated with the recycling of fiber. Research
has been focused mainly in three areas:
flotation, repulping; and high-consistency
dispersion. Experimental flotation stud-


717 T 1 n 1

Figure 4. Students share a laugh in the
paper laboratory.

Figure 3. General view of the U Maine Pilot Plant
showing the paper machine.

ies have addressed a wide range of important issues related
to drinking. Theoretical studies have focused on developing
a fundamental hydrodynamic model to calculate bubble and
particle trajectories and predict the conditions for particle
capture in a flotation cell. Repulping studies have been con-
cerned mainly with toner/fiber and stickies/fiber detachment
and the consequences of incomplete detachment on the per-
formance of subsequent operations. The breakdown of toner
particles and the fate of "hairy" particles in a modified 12-
inch disk refiner have also been investigated.
Pulp and Paper Pilot Plant
(Prof Genco; professional staff four students)
The Pilot plant is a fully equipped and instrumented facil-
ity that includes stock preparation and pulping, hydrocyclone
cleaners, and a small-scale (12-inch) continuous paper ma-
chine (see Figure 3) as well as blade and roll coaters. One
can thus start with wood, straw, recycled paper, or any other
fibrous material and study the full paper-making process
through to coating and final finishing of the sheet. The
facility is run partly for research and partly as a routine
testing facility for which the client company pays a service
fee. Recent research has been focused on the development of
new environmentally friendly bleaching and pulping pro-
cesses based on the use of oxygen rather than chlorine as the
primary oxidant as well as on advanced refining and drain-
age studies.
Supercritical Fluids
(Prof Kiran; two post-doctorals; four students)
Professor Kiran has established a well-equipped high-pres-
sure (up to 1000 bar) laboratory for studying the thermody-
namic, transport, and kinetic aspects of supercritical fluids
and polymer solutions. A series of integrated studies focus-
ing on both the fundamentals and applications of near and
supercritical fluids has been carried out over a period of
more than ten years. Among the fundamental topics recently
studied are the Kinetics of Pressure-Induced Phase Separa-

tion (PIPS) by Time-Resolved Light Scattering and Density
Modulated Supercritical Polymerization, in which the den-
sity/pressure/temperature of the solvent medium is adjusted
to achieve controlled phase separation and the precipitation
thresholds are adjusted to control the molecular weight and
morphology of the resulting polymers. More practically ori-
ented studies have focused on the formation of micro-struc-
tured polymeric materials, delignification, and pulping un-
der supercritical conditions, and on the possibility of using
supercritical impregnation of other polymeric species to
modify cellulose fibers and/or wood in order to improve the
physical properties.
Sensors and Neural Networks
(Prof Pendse; three students)
Hemant Pendse's main research focus has been on the
development of advanced sensors-notably the application
of ultrasound to the characterization of slurries. This has led
to the development of a commercial instrument, the
Acoustrophoretic Particle Analyzer, which can provide in-
formation, without dilution, on the particle size distribution
of quite concentrated slurries. Present research is focused on
generalizing these techniques to obtain information on par-
ticle shape and to study the characterization of suspensions,
polymer melts, and porous media. The possibility of apply-
ing virtual sensors using a neural network to improve the
control system at a local pulp mill is being investigated, in
collaboration with Prof. M.T. Musavi of the Electrical Engi-
neering Department.
Chemical Engineering Education

I I_ -- -

."". At C." ,


Douglas W. Bousfield (Associate Professor)
BS, Montana State, 1981 MS, Oregon State, 1983 PhD, California-Berkeley, 1986
Non-Newtonian fluid mechanics, fluid suspensions, particle hydrodynamics, and flow in
thin films; Director of Graduate Studies
Albert Co (Associate Professor)
BS, University of Philippines, 1972 PhD, Wisconsin, 1979
Polymer rheology, slip casting, transport phenomena; responsibility for computing
facilities and LAN
Joseph M. Genco (Colder Professor and Director of Pilot Plant)
BS, Case Institute, 1960 MS, Ohio State, 1962 PhD, Ohio State, 1965
Pulp and paper technology, delignification of wood, novel pulping methods
John C. Hassler (Professor)
BS, Kansas State, 1960 PhD, Kansas State. 1966
Process control, instrumentation and computer interfacing, mathematical modeling
John J. Hwalek (Associate Professor)
BS, Clarkson College, 1977* MS, Illinois, 1980 PhD, Illinois, 1982
Process analysis, neural networks
Erdogan Kiran (Gottesman Research Professor)
BS, MIT, 1969 MS, Cornell, 1971 PhD, Princeton, 1974
Supercritical fluids, physics and chemistry of polymers
Pierre LePoutre (J. Larcom Ober Professor)
BSc, Ecole des Hautes Etudes Industrielles, Lille, France, 1957 MS, N.C. State, 1960 *
PhD, N .C. State, 1969
Physics and chemistry of surfaces, adhesion, paper surface science
Kenneth I. Mumme (Professor)
BS, Lawrence College, 1954 MS, U. Maine, 1966 PhD. U. Maine, 1970
Process control; Director of undergraduate studies and co-op program
Hemant P. Pendse (Professor)
BTech, IIT, Bombay, 1975 MS, Syracuse, 1977 PhD, Syracuse, 1980
Development of sensors, colloid and surface chemistry, neural networks applied to
process control
Douglas M. Ruthven (Professor and Chair)
BA, Cambridge, 1960 MA, Cambridge, 1963 PhD, Cambridge, 1966 ScD, Cambridge,
Adsorption and adsorption separation processes
Edward V. Thompson (Pulp and Paper Foundation Research Professor)
BS, Cornell, 1956 PhD, Brooklyn Polytechnic, 1962
Recycle fiber technology, flotation and interfacial phenomena

Nick G. Triantafillopoulos
PhD, IPST, Atlanta, 1991
Principal Technologist, GenCorp Specialty Polymers, Inc.

Stanley N. Marshall, Jr.
BS, U. Maine, 1961 MS. U. Maine, 1964
Executive Director of UM Pulp and Paper Foundation

Barbara J.W. Cole
PhD, Washington, 1986 Associate Professor of Chemistry, U. Maine
Barry S. Goodell
PhD, Oregon State, 1983 Professor/Chair. Dept of Wood Science. U. Maine
Marquita K. Hill
PhD., California-Davis, 1966
Stephen M. Shaler
PhD, Penn State, 1986 Associate Professor of Wood Science
Charles E. Tarr
PhD, North Carolina, 1966 Associate Vice President for Academic Affairs, Dean of
Graduate Studies, Professor of Physics

With the appointment of Barry Goodell, a
biochemist by training, as a cooperating profes-
sor, the Department has made a cautious entry
into the field of biochemical engineering. Two
ChE graduate students are now working on
projects involving the application of enzymes
and chelating agents to pulping and bleaching.
Albert Co is a former student of Byron Bird,
and he has inherited his mentor's penchant for
complex fluid mechanical problems. He is cur-
rently studying the effects of polymer rheology
and operating conditions on draw resonance in
multilayer film casting, a problem that is closely
related to some of the problems encountered in
the production of polymer coated paper. Dou-
glas Ruthven joined the Department as Chair in
1995. When not fighting with the University
Administration to preserve the chemical engi-
neering budget, he continues his research on
adsorption and adsorption processes and his edi-
torial duties for Chemical Engineering Science.

There are many excellent chemical engineer-
ing departments in the U.S., and most are larger
and far better funded than U Maine. Through
the shrewdness and foresight of its founders
(notably Lyle Jenness), however, and with the
generous help and support of the Foundation, U
Maine has become an important niche player,
providing a supply of well-trained and capable
graduates with a special focus on the needs of
the pulp, paper, and associated industries and
acting as a center for fundamental research
on problems of practical concern to that in-
dustry. With increasingly stringent environ-
mental regulations and decreasing availabil-
ity of traditional sources of fiber, there is no
shortage of challenging problems to address.
Our first priority for the future must be to
maintain and strengthen our links with in-
dustry through the Foundation, the co-op pro-
gram, and the collaborative research programs
in order to ensure that our students, in both
undergraduate and graduate programs, receive
a first-class, practically oriented engineering
education. Half the faculty are within seven
years of the "normal" retirement age, so the
need to hire some younger members to con-
tinue the tradition is obvious. The current
hiring freeze at U Maine thus presents a sig-
nificant obstacle that will have to be over-
come. D

Spring 1997

, SO classroom




Differential-Algebraic Equations Systems

in Undergraduate Education

Tel-Aviv University Tel-Aviv 69978, Israel

Design and simulation of unit operations and many
other physical phenomena require development of
mathematical models and a solution of the models.
In the past, the analytical solution was the only option.
Nowadays, however, with the introduction of interactive,
user-friendly numerical software packages, the model is of-
ten solved numerically even if an analytical solution can be
obtained, since a numerical solution usually requires less
effort and allows solution of more realistic problems. Obvi-
ously, an analytical expression can provide more informa-
tion than a numerical solution. While a numerical solution
provides numerical information only inside the region where
simulation is carried out, an analytical expression allows
investigation of the model behavior over the entire region of
its validity. Furthermore, when the analytical model is pre-
sented in a dimensionless form, the effects of its various
dimensionlesss) parameters can often be predicted even with-
out solving the equations.
But arriving at an analytical solution often requires simpli-
fication of the rigorous model by making certain assump-
tions. Once an assumption is made, it is sometimes difficult
to appreciate the inaccuracy it introduces and to decide
whether the solution reached for the simplified model is also
a valid solution for the original problem. The information
provided by analytical and numerical solutions complement
each other, and therefore it is very important to obtain both
whenever it is possible. The recommended procedure would
start with solving the simplified model both analytically and

* Address: Ben-Gurion University of the Negev, Beer-Sheva
84105, Israel

numerically. This apparently superfluous step validates the
analytical solution of the simplified model and at the same
time substantiates the numerical scheme. Then one can pro-
ceed to solve the rigorous model numerically.
If the rigorous model consists of ordinary differential equa-
tions (ODE) or nonlinear algebraic equations (NLE), the
numerical solution is a feasible approach, even at an under-
graduate level, using readily available software tools such as
MAPLE,11 MATLAB,'21 and POLYMATH.'3' Often, rigor-
ous models of simple systems contain both ordinary differ-
ential equations and implicit nonlinear algebraic equations.
Such a system of equations is called a differential-algebraic
system (DAE). The software tools available for solving such

Neima Brauner received her BSc and MSc from
the Technion, Israel Institute of Technology, and
her PhD from the University of Tel-Aviv. She is
currently Associate Professor in the Fluid Me-
chanics and Heat Transfer Department. She
teaches courses in Mass and Heat Transfer and
Process Control. Her main research interests
include two-phase flows and transport phenom-
ena in thin films.

Mordechai Shacham is Professor and Head of
the Chemical Engineering Department at the Ben
Gurion University of the Negev, Beer-Sheva,
Israel. He received his BSc and DSc from the
Technion, Israel Institute of Technology. His re-
search interests include applied numerical meth-
ods, computer-aided instruction, chemical pro-
cess simulation, design, and optimization, and
expert systems.

Copyright ChE Division ofASEE 1997
Chemical Engineering Education

In this paper, we present two simple examples where some simplified models yield incorrect
results and there is a need to solve DAE systems. A simple technique for solving DAE
systems using the software tools familiar to engineering students is introduced.

systems are not yet appropriate for use by undergraduate
students, and instructors feel reluctant to present realistic
models containing DAEs.
In this paper, we present two simple examples where some
simplified models yield incorrect results and there is a need
to solve DAE systems. A simple technique for solving DAE
systems using the software tools familiar to engineering
students is introduced.

Calculation of the composition in a batch distillation still
as a function of the amount of the remaining liquid is a
classical problem, described in many textbooks."4 7] The sim-
plified model for batch distillation was provided by Lord
Rayleigh in 1902. 1
The batch distillation apparatus is shown schematically in
Figure 1. Liquid of the amount Lo moles is initially charged
into the still. Distillate is removed continuously at a rate of V
moles/hr. Total material and component balances on the still


L(t = 0)= Lo

d -V y (2)

where x, is the mole fraction of species i in the liquid phase,
and y, is the mole fraction of species i in the vapor phase.
Equations (1) and (2) are combined to yield
dL L
L x(t = 0) = Xi (3)
dxi y xi

The solution of Eq. (3) requires an equilibrium relation-
ship between y, and x,. Such a relationship can be expressed
using either the vapor liquid equilibrium ratio k, or the rela-
tive volatility ca,. During distillation, the liquid and vapor
compositions change. Consequently, the temperature changes,
following the bubble point curve of the liquid. If the value of
k, can be assumed to be constant, Eq. (3) can be integrated
from the initial mole fraction of species i, x,o to the final
mole fraction xi, to yield

Lo ki -1 (4)

For a binary system when aij is assumed to be constant,
integration of Eq. (3) yields

(nL aL (x,(1l-xi)J 1- xio (5)
L0) L- xlo(1-x 1 n -xi)

To verify that either ki or aij may be assumed to be
constant, the bubble point temperature at the initial and final
compositions and the respective k, and aj values must be
calculated. If there is only a small difference between the
initial and final values, an average value of ki or aij can be
used in Eqs. (4) or (5), respectively. But when a considerable
difference is encountered, the simplified model gives incor-
rect results and the rigorous model must be used.
In the rigorous model, the effect of changing compositions
and temperature during the distillation on the k, and aij
values must be taken into account. The temperature changes
in the batch still follow the bubble point curve. The bubble
point temperature is defined by the implicit algebraic equa-

Figure 1. Batch distillation apparatus.

f(T)=l- kixi =0

For near-atmospheric pressures, the vapor-liquid equilib-
rium ratio can be expressed by

k, = P (7)
where Pi,y, are the vapor pressure and the activity coeffi-
cients of the species, respectively, and P is the total pressure
(usually constant).
The vapor pressure of an individual component can be
correlated as a function of temperature using, for example,
the Antoine equation. The activity coefficient for a binary

Spring 1997

system can be expressed as a function of the liquid composi-
tion using Margules, Van-Laar, or similar equations.
The system of equations comprising Eqs. (3), (6), and (7)
is a DAE system. Thus, if neither k, nor aij can be assumed
to be constant, the solution of a binary batch distillation
problem requires a numerical solution of a DAE system.


The results of the simplified model and the rigorous model
are compared by solving both numerically. The initial tem-
perature and the associated k, and aij values are obtained by
solving the bubble point temperature, Eq. (6), at the initial
composition. From this initial point, the ODE equation, Eq.
(3), can be integrated while maintaining constant (say, the
initial) values for the temperature, ki and aij. The error
introduced by this assumption is estimated from Eq. (6),
which is rewritten in the form

e=l- kixi (6a)

The error calculated from Eq. (6a) provides a basis for
correcting the temperature along the bubble point curve. The
temperature can be changed in proportion to the error. Thus

S= Kc (8)

A proper choice of Kc will keep the error below a desired
error tolerance Ed throughout the whole integration interval.
Equations (6a) and (8) combined yield an ODE system that
represents the rigorous model.
This method for solving a DAE system by converting it to
an ODE system will be called the "controlled integration"
method. The name indicates that the variation of the alge-
braic variable is being controlled during the integration to
maintain the error of the implicit algebraic equation below a
desired level.
The value of Kc, appropriate for a certain error tolerance,
can be estimated from the rate of increase of the error while
the temperature is kept constant. A method for calculating
Kc is explained in Appendix A. The value of Kc can also be
determined by a simple trial-and-error technique. Students
often find this approach easier to understand and more con-
venient to implement. It will be demonstrated in the detailed
example that follows.
Another option to convert a DAE system into an ODE
system is differentiation of the implicit algebraic equation(s)
(such as Eq. 6) to obtain an expression for, say, dT/dxi. For
initialization (to get an initial value for T), the implicit
algebraic equation(s) must be solved. This approach has

several disadvantages in comparison to the controlled inte-
gration method. The differentiation of even moderately com-
plex equations is a very tedious and error-prone task. Fur-
thermore, it is often impossible to express the differential
(say, dT/dxi) explicitly, as is required by most numerical
software tools. The use of this method becomes especially
complicated for disjunctive system of equations, where there
is a need to use different sets of equations in different re-
gions (transition from laminar to turbulent flow, for ex-
ample). The transition from one region to another requires
re-initialization of the system, while for the controlled inte-
gration method, such a re-initialization is not necessary. The
use of differentiation for converting DAEs to ODEs, and the
potential difficulties, will also be demonstrated in the ex-
amples that follow.


Batch Distillation of an Ideal and a
Non-Ideal Binary System

la. Ideal System
King"41 presents an example of batch distillation of ben-
zene (component #1) and toluene (component #2) mixture.
Initially, there are 100 moles of liquid in the still, comprising
60% benzene and 40% toluene (mole fraction). The amount
of liquid remaining in the still when the concentration of
toluene reaches 80% should be calculated. The distillation is

Initial and Final Conditions in Batch Distillation of a
Benzene (1) Toluene (2) Mixture

x, x, ToC k, k2 o12
Initial 0.6 0.4 95.5851 1.31164 0.532535 2.46302
Final 0.2 0.8 108.572 1.85674 0.785817 2.36281

Ke = 0 _... --------
---- '~~ K'e= 103
Kc = 105
E 10-4 -
Kc= 3x106


10-8 I I
0.40 0.48 0.56 0.64 0.72 0.80
Concentration, X2
Figure 2. Variation of E while changing the value of K,
in Eq. (8).
Chemical Engineering Education

carried out at a pressure of 1.2 atm.
The mixture of toluene and benzene can be considered as
an ideal mixture (yi, ,2 = 1), thus the liquid vapor equilib-
rium ratio can be calculated from k, = P,/P. The vapor pres-
sure of the individual components can be calculated from the
Antoine equation
log(Pi)=A,+ (9)

where P, is the pressure in mmHg, and T is the temperature
in 'C. The Antoine equation constants for benzene are A, =
6.90565, B, = -1211.033, and C, = 220.79. For toluene they
are A, = 6.95464, B, = -1344.8, and CG = 219.482.191
Solving the algebraic Eq. (6) (when k, is calculated from
Eqs. 7 and 9) to find the bubble point temperature at the
initial and final composition of the liquid, yields the results
shown in Table 1.
It can be seen that the temperature increases during the

0.40 0.48 0.56 0.64 0.72 0.80
Concentration, x2
Figure 3. Variation of k,, k2, and a12 during distillation
of the ideal benzene-toluene system.

distillation by about 130C, which causes approximately a
40% increase in the value of k, but only about a 4% reduc-
tion in the value of c12. Thus, Eq. (5), with an average value
of a2 = 2.41, can be used to calculate the amount of liquid
remaining in the still. This calculation yields L = 14.031
mol, which is identical to the result obtained by King.'41
To check whether the results of the simplified model are
accurate enough, numerical integration of Eq. (3) is carried
out while the error is calculated using Eq. (6a). Since nu-
merical integration must proceed in the direction of increas-
ing x, value, Eq. (3) is integrated from x2 = 0.4 up to x2 = 0.8.
Figure 2 shows that various values of K, yield solutions of
different precision. For K, = 0, e increases from -3.6 x 10-7
at the initial point to 0.311 at the final point. With K, = 1000,
the maximal error is 3.7 x 10- and it reduces to 3.9 x 104 for
K, = 10'.
Finally, using K, = 3 x 106 yields a solution with a maxi-
mal error e = 1.3 x 105 at x, = 0.8, which matches the
desired error tolerance (ed = 10-5). The initial and final val-
ues for the other variables are exactly the same as shown in
Table 1. The remaining liquid, L = 14.0423 mol, differs only
in the fourth decimal digit from the simplified model results.
The reason for the excellent fit in this case is that the relative
volatility changes linearly over the entire range (see Figure
3). Thus, an average value of a12 provides a very good
In this example, the rigorous model is simple enough to
obtain an analytical expression for dT/dx,. For an ideal bi-
nary mixture, where y, = 1 and the vapor pressure is repre-
sented by the Antoine equation, differentiation of Eq. (6)

dT (k2 -k,)
dx2 ( BI B2 I
Sn (10)1x 1 I 2 -+ x k ^ --2-X2 1 |
(C, + T) (C2+ T)2

Simultaneous numerical integration of Eqs. (3) and (10)
yields the same results as were obtained using the controlled
integration method.

lb. Non-Ideal System

The batch distillation of the ideal-system example is re-
peated with the non-ideal mixture of water (component #1)
and ethanol (component #2). Initially, a liquid mixture of
60% ethanol and 40% water is charged to a still pot. The
distillation is carried out at a total pressure of 1 atm. The
amount of liquid remaining in the still, when the mole frac-
tion of water reaches 0.95, should be calculated.
Since water and ethanol form a non-ideal mixture, Eq. (7)
should be used to calculate the vapor-liquid equilibrium
ratio. The Margules equations can be used to calculate the
activity coefficients of the various components:

Spring 1997

Antoine Equation Constants191 for
the Water-Ethanol System

Water 7.96681 -1668.21 228.0
Ethanol 8.04499 -1554.3 222.65

Initial and Final Conditions in Batch Distillation of a
Water (1) and Ethanol (2) Mixture

x, x, TC k, k, a12
Initial 0.4 0.6 79.1685 0.757729 1.16151 0.652364
Final 0.95 0.05 90.9639 0.721619 6.28615 0.114795

log(y1)= x2[a + 2 x (b- a)]
log(2)= x [b + 2x2(a b)]


where a=0.3781 and b = 0.6848 for this particular system."01
The respective Antoine equation constants are shown in
Table 2.
Solving the algebraic equations for bubble point tempera-
ture at the initial and final compositions of the liquid yields
the results shown in Table 3.
It can be seen that in this case changes in the values of the
relative volatility and k2 are very significant. Using Eq. (5)
with an average value of a12 =0.384 to calculate the remain-
ing amount of liquid yields L = 5.236 moles.
The rigorous model is solved by the controlled integration
method. Using the procedure described in Appendix A with
an error tolerance of Ed = 105 yields K, = 2.56 x 105. The
amount of liquid remaining in the still using the rigorous
model is L = 8.329 moles, 60% greater than the value pre-
dicted by the simplified model. Figure 4 shows the variation
of kl, k2, and a12 during distillation. It can be seen that the
variation of a12 is nonlinear. This explains the large discrep-
ancy between the results of the simplified and rigorous mod-
For this non-ideal solution, Eq. (6) can be differentiated to


(71 71 Pl 2 J 2
(kI k) + a- a- X + Y2 -Y2 X P2
Dx, X2 P Ox1 ayx2 P
71 dP1 72 dP2
dT P+X dT
P dT P dT

To carry out all the differentiations required in Eq. (12)
can probably be a good exercise in mathematics, but it is
clearly not a practical way to solve the rigorous model. Even
when a symbolic manipulation package (such as Maple) is
used to carry out the differentiations, the effort and the
complexity involved are not reduced to such a level that
makes this approach a practical one to be used in under-
graduate education.


Draining a Cylindrical Tank

Figure 5 shows a cylindrical tank of diameter D with a
draining pipe arrangement. The initial height of the liquid
level above the draining pipe exit is H, and the final height is
Hf. The draining pipe diameter is d and its length is L. The
time required to drain the tank from the initial height of H0 to
the final height H, is to be calculated.
The equations representing the tank during the draining
are fairly simple and have been discussed widely in the

literature. "'"21 The pertinent equations follow.
The rate of change of the liquid level in the tank dH/dt is

dH d2
dt D2 V (13
where V2 is the exit velocity of the liquid from the draining

2g(H + L)
V =F2g(H+L (14
2 1+fDL/d

In the laminar region (Re < 2100), the friction factor, fD, is
given by
where Re is the Reynold's number, Re = V2d/u, and u is
the kinematic viscosity. In the turbulent region (Re > 4000),,
the Colebrook & White equation applies:

1 ( e 2.51
S-2 log 3.7d R (16:

where e is the pipe roughness.
Assuming that fD is constant during draining, the expres-

-0.8 L


0.60 0.72 0.84 0.96

Concentration, xi

Figure 4. Variation of k,, k2, and a12 during distillation
for the non-ideal water-ethanol system.

Figure 5. Tank with draining pipe.
Chemical Engineering Education


I II ,


sion for V, from Eq. (14) can be introduced into Eq. (13).
Integration from H0 to H, yields the expression for the total
time required for draining, t,,

t = D 2 I + ( -- L ) (17)

The solution of the simplified model (Eq. 17) is compared
with the rigorous solution for the case of turbulent draining
(Example 2a) and for the case where transition from turbu-
lent to laminar flow takes place during the draining.

2a. Tank Draining in the Turbulent Region

The following numerical data was used for the calcula-
tions in the turbulent region: D = 3 ft, H, = 3 ft, and H, = 1 in.
The draining pipe is a nominal 1/2" schedule 40 steel pipe
with roughness e = 0.00015 ft. The liquid in the tank is water
at 600F (kinematic viscosity t = 1.22 x 105 ft2/s).
The initial and final conditions obtained by solving the
system of algebraic equations (comprising Eqs. 14 and 16)
are shown in Table 4.
It can be seen that although the exit velocity and the
Reynolds number are significantly reduced (to about half of
their initial value), the friction factor changes only by about
6%. Using the average value of fD = 0.0291 in Eq. (17) yields
a draining time of t, = 1000.58 s.
To solve the rigorous model, Eq. (16) is rewritten as

Initial and Final Conditions in Turbulent Draining

Liquid Level (ft) Exit Velocity (ft/s) Re fo
Initial 3 12.9157 54873.9 0.02821
Final 0.08333 6.64831 28246.2 0.02998

Figure 6. Friction factor variation during tank draining.

= -2 log d Re.fD
[ 3.7 d Re fDj
with an additional differential equation

Applying the same procedure used in the batch distillation
example for calculating K, yields the value of K, = 1. Solv-
ing the rigorous model by numerical integration yields a
draining time of tf = 999.5 s. Thus, the difference between
the values calculated by the simplified and rigorous models
is insignificant (about 0.1%).

Figure 6 shows the change of the friction factor during
draining. The almost linear and very moderate change of fD
causes the simplified model to be very accurate in this ex-

2b. Tank Draining in the Transitional
and Laminar Regions

The system geometry is the same as in Example 2a, but the
liquid in the tank is now hydraulic fluid (MIL-M-5606) at
600F (kinematic viscosity u = 20.9 x 10-5 ft2/s).
The initial and final conditions obtained by solving a
system of algebraic equations (comprising Eqs. 14 and 15 or
16) are shown in Table 5. It can be seen that initially the flow
is in the transitional region (2100 < Re < 4000). There is no
definite rule for the friction factor correlation that applies in
this region.13'" The equation for laminar flow (Eq. 15) yields
a friction factor smaller by a factor of about 2.5 than the
Colebrook & White equation (Eq. 16) for turbulent flow.
Consequently, the draining velocity and the Reynolds num-
ber are also considerably different.
At the final stage of the draining, the flow is in the laminar
region. In order to model this system, we used the Colebrook
& White equation for fD as long as Re > 2100, and Eq. (15)
was used after the value of Re dropped for the first time
below the value of 2100.

Initial and Final Conditions During Tank Draining in the
Transitional and Laminar Regions

Liquid Level Exit Velocity
(ft) ft/s Re f,

Initial f, from Eq. 15 3 13.7525 3410.77 0.01876
f from Eq. 16 3 11.6509 2889.5 0.04653
Final 0.08333 6.2263 1544.18 0.0414459

Spring 1997

Using an average value of fD = 0.04399 in Eq. (17) yields a
draining time of tf 1088.76 s. Solving the rigorous model
using the controlled integration method yields t, = 1057.9 s.
Thus, there is only a 3% difference between the results
obtained by the simplified and rigorous models. It is to be
noted that the difference increases as the period of laminar
draining extends.
Figure 6 shows the change of the friction factor during
draining. It can be seen that it increases gradually during
draining until the Reynolds number reaches Re = 2100 for
the first time. At this point, the friction factor calculation
switches to the laminar flow equations. This causes the
friction factor to drop to about half of the turbulent flow
In Figure 7, a similar jump in the exit velocity is notice-
able at the point where the flow regime changes. From this
point on, the friction factor starts increasing gradually as the
flow stays in the laminar regime.
If we attempt to solve this problem by differentiating Eq.
(16) to obtain an expression for dfD/dt for converting the
original DAE system into an ODE system, the system must
be reinitialized at the point of transition from turbulent to
laminar flow. The controlled integration method automati-
cally adjusts to such a discontinuity caused by switching
between the two different correlations for the friction factor.

The controlled integration method, as presented in the
previous sections, enables students without any background
in numerical analysis or control theory to solve simple DAE
systems using interactive computational tools they are fa-
miliar with. For students who have been exposed to process
control principles, the method can be extended to include
more complex DAE systems using PID controllers.
A DAE system can be written in general as

=f(x, y, t)

x = x at t = to

g(x, y, t) = 0



For solving this system using the controlled integration
method, Eq. (20b) is rewritten as

and the following equations are added:

= q

q=Kc e+-- dt+ TD-
Ti dt
0o J




The set of algebraic equations (Eq. 20b) is solved at the
initial point; thus y = yo at t = to so that g(x, y0, o) = 0. For
rigorous solution of the DAE system, controllers) are used
to force y to follow the solution curve. The method for
selecting the controller type and the tuning parameter values
is discussed in detail by Shacham, et al.1141
Students who have access to large-scale dynamic simula-
tion programs (such as SPEEDUPE"V) can solve DAE sys-
tems directly, just like ODE systems. Unfortunately, these
large-scale packages are still too complex to be used in
undergraduate education.

We have shown that application of closure laws in realistic
modeling will often lead to the need to solve DAE systems.
Educators in the past were reluctant to discuss such prob-
lems because there were no software tools available to en-
able students to solve DAEs.
We have introduced the controlled integration method,
which enables students without prior knowledge of numeri-
cal analysis or process control, to solve simple DAE systems
using user-friendly popular software tools, such as MAPLE,
The examples presented clearly demonstrate that without
solving the rigorous model, the error introduced by certain
simplifying assumptions often cannot be appreciated. There
is no justification whatsoever to avoid classroom problems
(where, say, the relative volatility is not constant) just be-
cause an elegant analytical solution does not exist. Just as
user-friendly NLE solvers enable students to deal with real
gases represented by various equations of state (in addition
to the ideal gas), the method presented in this paper enables
them to deal with non-ideal solutions in addition to the
traditional treatment of ideal solutions.

1. Ellis, W., Jr., E. Johnson, E. Lodi, and D. Schwalbe, MAPLE
V Flight Manual, Brooks/Cole Pub. Co., Pacific Grove, CA

0 0.2 0.4 0.6 0.8 1.0
Time, tx0" [sec]

Figure 7. Velocity variation during draining.
Chemical Engineering Education

2. MATLAB for Unix Computer's Users' Guide, The MathWorks,
Inc., Natick, MA (1991)
3. Shacham, M., and M.B. Cutlip, POLYMATH 4.0 User's
Manual, CACHE Corporation, Austin, TX (1996)
4. King, C. J., Separation Processes, McGraw-Hill, New York,
NY (1971)
5. Henley, E.J., and J.D. Seader, Equilibrium-Stage Separa-
tion Operations in Chemical Engineering, John Wiley &
Sons, New York, NY (1981)
6. Holland, C.D., and A. I. Liapis, Computer Methods for Solv-
ing Dynamic Separation Problems, Prentice Hall Book Co.
7. Holland, C.D., Fundamentals of Multicomponent Distilla-
tion, McGraw-Hill Book Co., (1981)
8. Rayleigh, Lord, Phil. Mag. [vi], 4(23), 521 (1902)
9. Dean, J.A., ed., Lange's Handbook of Chemistry, McGraw-

Hill, New York, NY (1973)
10. Holmes, M.J., and M. Van Winkle, "Prediction of Ternary
Vapor-Liquid Equilibria from Binary Data," Ind. & Eng.
Chem., 62(1), 21 (1970)
11. Brauner, N., and M. Shacham, "Numerical Experiments in
Fluid Mechanics with a Tank and Draining Pipe," Comp.
Appl. in Eng. Ed., 2(3), 175 (1994)
12. Sommerfeld, J.T., "Draining of Conical Tanks with Piping,"
Chem. Eng. Ed., 24, 145 (1990)
13. Moody, L.F., "Friction Factors for Pipe Flow," Trans. of the
ASME, 66, 671 (1944)
14. Shacham, M., N. Brauner, and M. Pozin, "Applications of
Feedback Control Principles for Solving Differential Alge-
braic Systems of Equations in Process Control Education,"
Comp. & Chem. Eng., 20, Suppl. S1329-S1334 (1996)
15. Biegler, L.T., "Chemical Process Simulation," Chem. Eng.
Progr., 85(10), 50 (1989)


Calculation of the Controlled Integration K, for the Batch Distillation Problem

The change of temperature in the batch still can be
expressed by the differential equation

aT aE
aE ax,

(A 1)

Both derivatives on the right-hand side of this equation
can be easily estimated by integrating the simplified model,
observing the change of e vs. x, while keeping T con-
stant. The slope of the curve AE / Ax yields an estimation
for aE/ax Introducing a small change in the tempera-
ture, AT, and measuring the resultant change in the error,
AE provides an estimate for aT / De ~ AT / Ae. In order to
keep the error within a desired error tolerance, (|Ae| < Ed)
the integration step size, Ax, should be of the order of
Ed/(A / Axi).

Concentration, x2

Comparing Eq. (8) with Eq. (A-1) shows that

aT 1
aE Ax,

Thus, the value of Ax, and AT/AE can be used to obtain an
appropriate value for K,.
It should be emphasized that only a rough estimate for
K, is needed. Most recent integration routines include step
size control algorithms, which will change the value of
Axi to make Eq. (8) an accurate representation of dT/dx,.
The calculation of Kc is demonstrated with reference to
Figure A-1, which shows the variation of e vs. x2, for the
example of batch distillation of the benzene-toluene mix-
ture. The temperature is kept constant during the integra-
tion, except a step change of -1C, which is introduced at
x, = 0.41.
It can be seen that E increases linearly from an initial
value close to 0 to about 0.36 for x, = 0.8. The slope of the
straight line yields De / ax, = 0.76. Thus, in order to achieve
a solution with a tolerance Ed = 10-5, the controlled inte-
gration should use a step size

Ax, 10- 1.3x 10-5
The step change introduced in the temperature (-1C)
causes an increase in the error ( A = 0.028), hence

aT -l
= -35.7
le 0.028
An appropriate value for K, is thus K, = 35.7/1.3 x 105 =
2.7 x 106. 1

Figure A-1. Variation of the error in the bubble point
equation for the constant temperature batch
distillation model.

Spring 1997

u curriculum



In Chemical Process Design

New Mexico State University Las Cruces, NM 88003-8001

his description of a "Process Design, Analysis, and
Simulation" course curriculum is divided into three
sections. Since the concept of process design is em-
phasized throughout the curriculum, the sequencing of chemi-
cal engineering design classes at New Mexico State Univer-
sity (NMSU) is described in the first section, showing where
the course is sequenced in the degree program. In the
second section, the details of the course content are de-
scribed, and finally, the details of student evaluation
methods and the Texas Eastman involvement are de-
scribed in the third section.

Where "Process Design, Analysis, and Simulation"
Fits into the Curriculum
Process design at NMSU is a four-course, eleven-credit-
hour sequence beginning in the student's fourth semester.
The students begin performing detailed system designs and
cost estimations in the Process Instrumentation Laboratory.
This lab is followed by an engineering economics course
(Junior year), a design, analysis, and simulation course (se-
mester 7), and finally, a capstone design course (semester 8).
The progression of these courses in the NMSU curriculum is
shown in Figure 1. This figure also shows the associated
core understandings of the students at each level.
The "Process Design, Analysis, and Simulation" course
taken in semester 7 is the subject of this paper. The capstone
design experience requires the students to complete the AIChE
Design Contest problem. It is a two-credit-hour course that
requires students to solve the problem individually, follow-
ing AIChE contest rules. This capstone course affords the
students the opportunity to demonstrate that they have learned

I University of Nebraska, Lincoln, NE 68588-0126
2 Eastman Chemical Company, PO Box 7444, Longview, TX

and understood all of the technical aspects of process design.

Course Educational Goals
The course was created to accomplish a number of educa-
tional goals representing a greater-than-acceptable level of
process design competence for an entry-level engineer. Upon
completion of the course, we expect the student to
Understand the design method, design alternatives,
and cost estimation methods
Be capable of simulating a continuous flow process
with ASPEN+
Be adept at preparing progress reports, P&IDs, and
design project reports
Be efficient at preparing and performing formal and
informal oral presentations

David A. Rockstraw is Assistant Professor of Chemical Engineering at
New Mexico State University. He received his BS from Purdue University
in 1986, and his PhD from the University of Oklahoma in 1989, both in
chemical engineering. He is actively engaged in process research at
NMSU on projects involving micellar-enhanced electrodialysis, novel ad-
sorption materials, biofilm growth modeling, secondary-heterogeneous
crystallization, and solid acid catalysis.
James Eakman is Department Head of Chemical Engineering at the
University of Nebraska. He received his BS with distinction in chemical
engineering from the University of Minnesota in 1960 and his PhD from
Minnesota in 1966. Prior to becoming Department Head at Nebraska, he
was the Department Head at New Mexico State University (1992-1996).
Nick Nabours is supervisor of Professional Employment and College
Relations for Texas Eastman Division of Eastman Chemical Company.
He is the immediate past president of the National Association of Colleges
and Employers and has also served as president of the Southwest Asso-
ciation of Colleges and Employers. He remains active in all aspects of
college relations.
Steve Bellner is a Senior Chemical Engineer for the Texas Eastman
Division of Eastman Chemical Company in Longview, Texas. He has over
twelve years of experience in the areas of process synthesis and plant
design, specializing in all aspects of process simulation. He holds a BS
degree in chemical engineering from the University of Texas.
Copyright ChE Division ofASEE 1997
Chemical Engineering Education

[This] is a four-course, eleven-credit-hour sequence beginning
in the student's fourth semester. The students begin performing
detailed system designs and cost estimations in the Process
Instrumentation Laboratory. .... followed by an engineering
economics course, a design, analysis, and simulation
course, and finally, a capstone design course.

CTus semester 4 semester 5 or 6 semester 7 semester 8
Design Process Engineering Process Design
S instrumentation Eng"c ngo Analysis, and D gn
Sequence Laboratory Simulation
Prerequisite material & macro- transport &
Courses energy balances economics thermodynamics
Figure 1. Course sequencing in Chemical Engineering at NMSU.

Figure 2. Integration of lectures and simulation labs with the design project.
Spring 1997

Understand the application of 29
CFR 1910.119 regulations to the
design process
Distinguish between Process Hazards
Review techniques and understand
how to arrange and lead a review
Be able to identify appropriate
vendors for making inquiries and
obtaining price quotes

To achieve these goals in one semester,
the course was built around the design, cost-
ing, and evaluation techniques in the Peters
and Timmerhaus text,[' which is supple-
mented by a number of references made avail-
able to the students in the department's read-
ing room.12-'] In addition, up-to-date vendor
literature on commercially available equip-
ment options is made available as reference
material for design projects.
The applicable material from the above-
mentioned references is being assembled into
a single source. In total, the guide lists thirty
sources of reference material used for the
lecture portion of the course, divided into
forty-one lectures. Student response to
availability of the notes was enthusiastic,
with convenience outweighing concerns
of additional cost.
To create an increased sense of industrial
authenticity, Texas Eastman was recruited to
participate in the course by providing design
projects that represented projects under con-
sideration at the Longview site.

Description of
Integrated Course Components

Details of the nature and timing of the
lectures, the simulation lab topics, and the
design project milestones for the integrated
course, outlined in Figure 2, are detailed
in the following sections.
Lectures The course is designed for three
fifty-minute lectures each week. The lectures
are divided into three units (equipment de-
sign/cost; economic evaluation/hazards re-
view methods; process optimization), and
written exams are administered at the comple-
tion of each unit. A summary of the lecture
and examination schedule is given in Table 1.
In the first unit (lectures 1-17), students are
informed of available equipment options, siz-
ing techniques, cost estimation techniques,

SDesign Proiect Milestones
1 informal written project report
2 formal written progress report memo, oral presentations
3 process hazards reviews, formal written follow-up summary
4 Informal written design report, oral recommendation
t- I written exam

and procurement procedures. The second unit (lectures 18-
32) covers economic evaluation and safety regulations, in-
cluding plant costing techniques, profitability potential,
OSHA 29 CFR 1910 regulations, and process hazards re-
view techniques. In the final unit of the course (lectures 33-
41), students are given some of the finer details of plant
design (including optimization techniques), relief and scrub-
ber systems for hazardous gases, column control techniques,
and pinch technology. Each set of lectures is followed by
a written examination to evaluate student progress on an
individual level.

Simulation Laboratory As the course title indicates, the
course includes a computer simulation component. This seg-
ment of the course is covered in a weekly, two-and-a-half
hour simulation lab in which the students are taught to per-
form process simulations on ASPEN+ simulation software.
Students must use the software to prepare the material and
energy balances for their preliminary and final designs. The
final design report must include a section on the preparation
and results of their simulation.
Four of the laboratory time slots are used for student oral
presentations. They include 1) the design task presentation,
2) an informal student-team presentation of potential design
concepts, 3) a formal process hazards review, and 4) the
formal design recommendation. The schedule of simulation
lecture topics and oral presentations for the computer labora-
tory is given in Table 2.
Design Project The major student learning activity dur-
ing the course is the design project. Except for oral presenta-
tions, the design project is completed by the students outside
of the class. The students spend ten weeks developing a
solution to a chemical processing need. Working in groups
of 3-4, the students are led through a design process contain-
ing four "milestones," each one representing a point where
one phase of the project is brought to a conclusion and
student progress is evaluated in some manner. The mile-
stones include 1) the generation of alternative designs, 2) a
study of the feasibility of the options generated and the
preparation of a preliminary design on promising candidate
designs, 3) a formal process hazards review, and 4) an eco-
nomic evaluation and design recommendation.
Student evaluation methods vary, depending on the mile-
stone reached. The evaluation may include written progress
reports, informal presentations, formal and informal written
reports, or a final formal presentation where the team pro-
poses and defends its design recommendation. Additional
details of the evaluation methods are described in the sec-
tions that follow and in the Student Evaluation Section.

> Milestone 1: Generation of Alternatives
Students are placed into groups and told to prepare a
flow diagram representing what they believe is the best
option for the processing problem being considered, in-

Course Lecture/Examination Schedule

Session Too


Course Ground Rules and Introduction to Process Design
Design Reports; Specification Sheets
Block Diagrams, Process Flow Sheets, and P&IDs
Design & Cost: Vessels, Reactors, Reaction Systems
Design & Cost: Plate Mass Transfer Systems
Design & Cost: Continuous Contacting Mass Transfer Systems
Design & Cost: Drying, Filtering, Mixing/Agitation Systems
Design & Cost: Valves, Pipes, Fittings
Piping System Calculations 1
Piping System Calculations 2
Design & Cost: Pumps
Design & Cost: Fans, Blowers, Compressors
Design & Cost: Vacuum Equipment and Systems
Design & Cost: Mechanical Design of Heat Transfer Equipment
Design & Cost: Sizing/Specifying Heat Transfer Equipment
Design & Cost: Solids Handling, Size Reduction Equipment
Materials of Construction: Options and Selection
Open Review for Exam 1


20 Cash Flows, Cost Classifications 18
21 Cost Estimation Methods 1 19
22 Cost Estimation Methods 2 20
23 Safety, Health, and Environmental Regulations 21
24 29 CFR 1910.119; Process Safety Management Regulations 22
25 Exposure, Fire, Explosion, and Thermal Stability 23
26 Process Hazards Review Procedures; Checklist and HAZOP 24
27 Process Hazards Review Procedures; FMEA and Fault Tree 25
28 Interest and Investment Costs 26
29 Taxes and Insurance 27
30 Depreciation Cost Methods 1 28
31 Depreciation Cost Methods 2 29
32 Profitability 30
33 Alternative Investments 31
34 Replacements 32
35 Open Review for Exam 2


37 Optimal Design and Design Strategy 33
38 Hazardous Gases 34
39 Control of Liquefied Toxic Gas Releases and Scrubber Design 35
40 Sizing of Relief and Control Valves 36
41 Distillation Column Control 37
42 Heat-Exchanger Networks (Pinch Technology) 1 38
43 Heat-Exchanger Networks (Pinch Technology) 2 39
44 Heat-Exchanger Networks (Pinch Technology) 3 40
45 Design Heuristics and Open Review for Final Exam 41


Chemical Engineering Education

eluding estimates of the installed capital of the process.
Emphasis is placed on creativity, thereby promoting brain-
storming sessions.
Students are evaluated based on the technical consider-
ations of their design, their creativity, and on the prepa-
ration of a memo that describes and justifies the alter-
native selected, summarizes the cost estimate, lists
assumptions and unknowns, and includes the flow dia-
gram as an attachment.
> Milestone 2: Feasibility Survey and Preliminary Design
The students are regrouped in such a manner that no
two members of a Milestone 1 group 1 are in the same
group again for Milestone 2. Using the design options
each member brings to the new group, the Milestone 2
team must prepare a preliminary design from the al-
ternatives and then perform a feasibility survey as-
sessment on that design.
Evaluation is based on a formal report that includes a
computer process simulation, equipment specification
sheets, preliminary P&IDs, and an estimate of capital
and operating costs. These materials are used to prepare
for the process hazards review.
> Milestone 3: Process Hazards Review
A complete process hazards review (PHR) is performed
by assigning each group an independent segment of the
process on which to prepare documentation for the review
(e.g., feed system, reactor system, distillation system).
Each group acts as the chairman for that segment, presents
a process description of that segment, and then leads the
hazards review on that segment. The instructor acts as the
PHR resource, assuring that the review session follows
proper protocols. Due to the manner in which students

Laboratory Lecture Topics/Oral Presentations
(Student Presentations in Italics)
Week ASPEN+ Topics and Student Presentation Sessions
1 Introduction to ASPEN+ and Model Manager
2 Components and Physical Properties
3 Component and Physical Properties
4 Flowsheeting and Unit Operations
5 Design Problem Presentation
6 Flowsheeting and Unit Operations
7 Preliminary Design Reports Due; Informal Oral Progress Reports
8 Flowsheeting and Unit Operations
9 Sizing and Cost Estimation
10 Work on Project Design Simulation
11 Process Hazards Reviews (PHR Materials Due and Presentations Given)
12 Optimization
13 Work on Final Design Simulation, Consultations
14 Work on Final Design Simulation (Final Design Reports Due End of Wk)
15 Final Process Design Recommendation Orals

Spring 1997

were grouped for the first two stages of the project, the
designs of the different groups are similar at this point.
Each group has a vested interest in the results of the
PHRs of other groups and thus becomes an active par-
ticipant in the review process.
Evaluation of the PHR is based on the quality of the
process description, the extent of the review performed,
participation, and the quality of summary documentation.

> Milestone 4: Economic Evaluation and Final Design
In the final phase of the project, each group incorpo-
rates the findings of the PHR committee into its design,
makes appropriate modifications to the simulations and
cost estimations, determines project profitability, and
prepares a structured, informal report clearly present-
ing a design recommendation. Each group must also
prepare and present a formal oral recommendation of
its design project.
Student evaluation for the final phase of the project is
based on performance on the traditional written report
and oral presentation. Eastman representatives are present
for the students' final oral design recommendations and
take active roles in the evaluation, with a portion of the
team's grade based on evaluations prepared by the Eastman
representatives. Upon completion of the orals, the
Eastman representative discusses the approach Eastman
would have taken to complete the design, providing
instant critique and feedback to the student teams on
their design solutions.

Guidelines for Problem Screening and Selection Each
problem must contain a significant opportunity for the stu-
dents to demonstrate acquired design skills without overbur-
dening them with ancillary tasks. The real systems of the
selected problem will typically require non-ideal thermody-
namic relationships. Details of the physical property rela-
tionships are provided as a part of the problem statement.
This removes the burden of having to research physical
property data (such as interaction parameters), but still re-
quires the student to decide whether or not to make use of
the information. The students become aware of the impor-
tance of the thermodynamic relationships without using valu-
able time better spent in the process synthesis and design
stages of the program.
It is important to select a problem that does not require an
unreasonable amount of effort to solve with the simulation
software. Although it is certainly a major objective of this
program to incorporate simulation methods into the design
process, the student should not have to use advanced simula-
tion techniques to solve the problem. This is a double-edged
sword since most problems with any substance whatsoever
require some advanced techniques to solve. It becomes the
task of the educator and corporate sponsor to reach a reason-
able balance between the complexity of the problem chosen

and the degree of modeling effort required to solve it.


Total Point Distribution
In addition to the core activity of the course (the group
design project), the evaluation includes assignments from
the text and lab, impromptu writing assignments and quiz-
zes, and three written examinations. These activities reflect
"individual" evaluation of the subject matter. The total course
point system is arranged so that the students must perform
both the individual and group activities successfully to achieve
an acceptable grade. The point distribution for the course in
provided in Table 3.

Evaluation of Design Projects

The final design is evaluated based
on four categories: technical content
(55%), report format (15%), project
management (5%), and oral presenta-
tion (25%). These expectations are in-
cluded in the course syllabus. Final de-
sign project reports are scored accord-
ing to the itemized breakdown pro-
vided in Table 4. The "Wt" column
refers to the weight the item carries
with respect to the category of which
the item is a subset.

Texas Eastman partnered with chemi-
cal engineering at New Mexico State
University in 1994 to assist in the edu-
cation and professional development of
students enrolled in the chemical engi-
neering program. The relationship in-
volves Texas Eastman's active partici-
pation in the administration and evalu-
ation of the design curriculum, coop-
erative engineering programs, and
scholarships. The hiring of NMSU
chemical engineering graduates by
Texas Eastman has increased substan-
tially since the onset of this program.
This interaction addresses requests by
the NSF's Engineering Education Coa-
litions (EEC) program to reform under-
graduate engineering education.[9] The
relationship seeks to aid in meeting
goals established by the NSF/EECs, in-
cluding 1) development of alternative
curricula and delivery systems that im-

prove the quality of undergraduate education, and 2) cre-
ation of intellectual exchange and substantive resource link-
ages among institutions. The value of design faculty pos-
sessing industrial experience complements the relation-
ship. The virtues of faculty having industrial design ex-
perience have been discussed by others.110o

Benefits to the Student
Although this interaction provides benefits to all parties
involved, the students enrolled in the course receive the
greatest enrichment. First, they have an opportunity to dem-
onstrate their technical competence, design creativity, and
communication skills to a potential employer, making the
design project and oral presentation much more than an

activity performed

Point Distribution

Student Evaluation PointValue Activit Type
Homework/Lab Problems 150 individual
Three Exams (100 points each) 300 individual
Preliminary Design 50 group (Milestone 1)
Feasibility Survey 150 group (Milestone 2)
Process Hazards Review 150 group (Milestone 3)
Final Design 200 group (Milestone 4)

Itemization of Evaluation Scoring

Technical Content (55%)
P&I Diagrams 20
Material/Energy Balances (simulation) 25
Federal Regulations/Hazards Review 15
Equipment/Construction Materials List 5
Equipment Specification Sheets 5
Equipment Cost Estimate 15
Economic Analysis 15

Project Management (5%)
Teamwork 50
Time Management 25
Progress Reports 25

Report Format (15%)
Transmittal Letter 5
Executive Summary/Abstract 20
Discussion 20
Conclusions and Recommendations 20
Attachments 10
Remaining Report Sections 10
Grammar/Spelling 15

Oral Presentation (25%)
Communication Skills 65
Quality of Visual Aids 25
Professional Appearance 10

only for a grade. The students have an
opportunity to network with potential
-recruiters as peers outside of the stan-
dard university interview process. In
1995, Eastman hired 10% of the gradu-
ating seniors from this class. Finally,
students achieve a feeling of satis-
faction derived from having com-
pleted a plant design that may find
industrial application as opposed to
merely repeating a previously com-
pleted plant design.

Benefits to the Industrial Sponsor

Texas Eastman is also a benefactor
of the interaction. Technical person-
nel from Texas Eastman have an op-
portunity to preview student's com-
munication and technical skills applied
to a specific problem from the Texas
Eastman site. In today's highly com-
petitive chemical manufacturing mar-
ket, poor communication can result in
missed opportunities, or worse yet,
human tragedy. In the design curricu-
lum at NMSU, students must give ap-
proximately ten formal presentations
on lab experiments or design projects
prior to their final oral presentation to
the Eastman representatives. Eastman
recruiters who are present for the fi-
nal oral design presentations are privi-
leged to see the results of a program
that places heavy emphasis on strong,
clear communication abilities.
Results of the students' work can
also be used as a "screening tool" for
preliminary process design alterna-
tives. The design problem being solved
by the students this semester involves
Chemical Engineering Education

a process stream at the Longview site, where a number of
components have recently been identified as potentially high-
value materials. Because of existing design commitments,
Eastman has been unable to perform a preliminary design
and cost analysis on separation of the valuable components.
With minimal effort, Eastman engineers were able to devise
the design problem in a manner that removed potential "con-
fidentiality" issues and have provided the design task as this
year's major problem for the class. Upon completion of the
course, Eastman will receive a number of design alterna-
tives, including ASPEN+ simulations, capital cost estimates,
and complete economic evaluations for this design. The
computer simulations represent a starting point for the com-
mercial design and save the company a significant number
of man-hours in design time.
Finally, the relationship places the "Eastman" name di-
rectly in front of each student for an extended period of time.
For those students who ultimately will not be employed by
Eastman, this process helps foster an image of a sponsor
that is sincere in its effort to help both the student and
their chosen college. This promotes a sense of added
"goodwill" toward Eastman Chemical Company since
the company becomes a permanent part of the student's
educational experience.

Benefits to the Corporate Design Engineer
The Texas Eastman engineer responsible for assisting in
the preparation and presentation of the design problem ben-
efits from the interaction with NMSU faculty in that it al-
lows the engineer to follow graduate research programs that
are of interest to the company. In addition, the student-
generated designs represent alternatives independently pro-
duced that may uncover an approach not previously consid-
ered by the company. Also, for tasks for which the company
has been unable to assign manpower to conduct a feasibility
study, the student designs represent a timesaving mechanism
by providing basic design requirements and a computer simu-
lation from which the company may begin a commercial
design task. In addition, the literature search and many of the
tedious calculations that represent the design fundamentals
will have been completed, conveniently placing the Eastman
design engineer in a position to begin optimizing the pro-
cess economics. The process also provides independent
verification of existing designs for problems extracted
from historical project files.
Finally, for students who are hired or accepted into the
cooperative program, the design engineer become a defacto
mentor and familiar face, easing the transition from success-
ful student to productive employee.

Benefits to the
Chemical Engineering Department and the University
This direct interaction of NMSU faculty and representa-
tives from Texas Eastman's Process Engineering Depart-
Spring 1997

ment, as well as Texas Eastman's Personnel Department,
has resulted in the formation of personal friendships, further
strengthening ties between Texas Eastman and NMSU. These
strong relationships are the precursor of many of the benefits
already discussed. Such relationships are often the source of
many intangible benefits to the Department and the Univer-
sity that are difficult to quantify.
As already discussed, this relationship increases the likeli-
hood of student placement, provides feedback from the in-
dustrial sponsor concerning suggestions on strengthening
the Department's academic program, allows faculty to keep
abreast of changing design needs of industry, and provides
the potential to develop collaborative research relationships
on topics of common interest.

The chemical process design curriculum at New Mexico
State University demonstrates the value of recent industrial
experience within a department. Dedication to education is
displayed by the level of effort placed into preparation of the
course design and educational materials. The achievements
of the Department's graduates will ultimately demonstrate
the effectiveness of the course format.
NMSU's Chemical Engineering Department has devel-
oped a partnership with the Texas Eastman Division of
Eastman Chemical Company for development and adminis-
tration of the design curriculum. This union provides ben-
efits to the students, the industrial sponsor, and the univer-
sity. The program has received praise from the students as
well as from the management of Texas Eastman and the
NMSU College of Engineering.

1. Peters, M.S., and K.D. Timmerhaus, Plant Design and Eco-
nomics for Chemical Engineers, 4th ed., McGraw-Hill, New
York, NY (1991)
2. Douglas, J.M., Conceptual Design of Chemical Processes,
McGraw-Hill, New York, NY (1988)
3. Himmelblau, D.M., Basic Principles and Calculations in
Chemical Engineering, 4th ed., Prentice-Hall, Englewood
Cliffs, NJ (1995)
4. Ludwig, E.E., Applied Process Design for Chemical and
Petrochemical Plants, Vols. 1-3, Gulf Publishing Co., Hous-
ton, TX (1964)
5. Perry, Chilton, and Kirkpatrick, Perry's Chemical Engineer-
ing Handbook, 6th ed., McGraw-Hill, New York, NY (1985)
6. Reid, R.C., J.M. Prausnitz, and B.E. Poling, The Properties
of Gases and Liquids, 4th ed., McGraw-Hill, New York, NY
7. Sander and Luckiewwicz, Practical Process Engineering: A
Working Approach to Plant Design, Ximax, Inc. (1987)
8. Vasilis, M.F., Prevention and Control ofAccidental Releases
of Hazardous Gases, von Nostrand Reinhold, New York, NY
9. Coleman, Robert J., "The Engineering Education Coalitions,"
Prism, Sept (1996)
10. Fairweather, James, and Karen Paulson, "Industrial Expe-
rience: Its Role in Faculty Commitment to Teaching," J. of
Engr. Educ., 85(3), p. 209 (1996) O

, learning in industry

This column provides examples of cases in which students have gained knowledge, insight, and
experience in the practice of chemical engineering while in an industrial setting. Summer internships
and co-op assignments typify such experiences; however, reports of more unusual cases are also
welcome. Description of the analytical tools used and the skills developed during the project should
be emphasized. These examples should stimulate innovative approaches for bringing real world tools
and experiences back to campus for integration into the curriculum. Please submit manuscripts to
Professor W. J. Koros, Chemical Engineering Department, University of Texas, Austin, Texas 78712.



University of Tennessee Knoxville, TN

he course "Design Internship in Industrial Pollution
Prevention" at The University of Tennessee (UT) is
an honors capstone design course in which source
reduction is incorporated into the design of industrial pro-
cesses. It involves the participation and support of DuPont
and is consistent with DuPont's commitment to environ-
mental excellence, summarized by the following process

R.M. Counce is Professor of Chemical Engineering at The University of
Tennessee. He holds a PhD in chemical engineering from UT. Prior to
coming to UT in 1981, he was at the Oak Ridge National Laboratory. He
conducts research in separations, process design, and pollution pre-
J.J. Holmes is Emeritus Professor of Chemical Engineering at the
University of Tennessee. He holds a PhD in chemical engineering from
UT. Prior to coming to UT, he worked in the chemical and nuclear
S.V. Edwards is a Management Consultant with Quality Development
Incorporated of Knoxville, TN, where she has been since 1992. She
holds a BS in Psychology from the University of Tennessee, Martin.
She was with IBM before coming to Quality Development Incorporated..
C.J. Perilloux is involved in research and development and new pro-
cess commercialization for organic chemicals. He is currently at DuPont's
Sabine River Laboratory in Orange, TX. He has a BS from Louisiana
State University and a PhD from Rice, both in chemical engineering. He
has been with DuPont since 1970.
R.A. Reimer is an Engineering Associate in DuPont's Orange, TX,
nylon intermediates research organization. He holds a BSChE from the
University of California at Berkeley and an MS in chemical engineering
practice from M.I.T. He has been associated with DuPont since 1969.

Quality Development Corporation, Knoxville, TN
2Sabine River Laboratory, E.I. du Pont de Nemours and
Company, Orange, TX

design priorities: 1) The design of processes will emphasize
technology selection such that all process materials are con-
verted into useful products. For process materials that are
unsuccessfully converted, the remaining design priorities
will be 2) recovery and recycle of all materials, 3) any
material that must be put into the environment will be in a
form that is transparent to the environment, and 4) failing
all of the above, material will be put into a form that is
safe to handle, and it will be immobilized and securely
stored in a controlled manner. Using that philosophy,
internship projects in process design have completed stud-
ies on far-ranging topics.
The activity described here is honors experience in indus-
trial process design where pollution prevention through ba-
sic flowsheet development and equipment selection is em-
phasized rather than conventional treatment of the effluent
waste streams.1'1 It is a 3-semester-hour course and is an
alternative to the traditional senior capstone design course.
The advisors have typically been full-time and emeritus
chemical engineering faculty members, but faculty from
other departments have also been extremely valuable in help-
ing the students gain a suitable working knowledge of a
subject that is commensurate with their educational back-
ground. DuPont currently provides internship opportuni-
ties, technical direction, and financial support, with cost
sharing from UT. Concepts to promote effective team
building and teamwork are provided by Quality Develop-

Copyright ChE Division ofASEE 1997

Chemical Engineering Education

The type of activity described in this paper provides for involvement of university students and faculty in
significant and challenging projects involving pollution prevention. This project and similar activities
have been well received by the students; their enthusiasm, perseverance, and overall quality of
work have been outstanding .... Participants ... typically begin industrial careers soon
after project completion, with a smaller number going to graduate school.

ment Incorporated (QDI).
The design internship proceeds through some typical steps
of preliminary process synthesis and evaluation, summa-
rized in Table 1. Faculty and industrial advisors provide the
necessary conditions and support for a student-directed pro-
cess design team to function effectively. Over the course of
several projects, the students have demonstrated the ability
to handle increasingly more complicated design tasks; in-
sights on the elements necessary for successful student de-
sign teams are the focus of this paper.

In general, the projects are at the conceptual level and all
students sign secrecy agreements. A background study is
conducted to familiarize the students with the problem and
to reveal alternative solutions. Screening is usually neces-
sary to select alternatives for more in-depth study. Flowsheets
for the selected approaches are developed and capital and
operating costs are estimated. Recommendations are based
on a matrix of considerations including economics and ad-
herence to DuPont's waste-management criteria. A final
report summarizing the various activities and recom-
mendations is typically the primary deliverable. One
project described below preceded DuPont's concep-
tual design activities and had the development of AS-
PEN process models as a deliverable.
Fall, 1991 A team of six students reviewed DuPont's
hydrogen cyanide recovery process and proposed improve-
ments or alternative processes to minimize waste-treatment
requirements. The project was coordinated by Dr. Ed Moss
(DuPont Victoria Plant) and members of the HCN team,
who met with the students for periodic reviews. Three
alternatives to current production approaches were se-
lected for in-depth study.
Spring, 1993 A team of six students investigated various
technologies for the removal and recovery of Cu and V from
adipic acid process purges. The project advisor was Althea
Haylett (DuPont Sabine River Laboratory), and UT advisors
included Professor George K. Sweitzer (Chemistry Depart-
ment). Potential technological approaches were screened,
flowsheets were generated for three selected technologies,
and capital and operating costs were estimated.
Spring, 1994 A team of seven students focused on treat-
ment options for biosolids from biological wastewater treat-
ment. The project was sponsored by Dr. Charles Perilloux of
Spring 1997

the DuPont Sabine River Laboratory. The team examined
state-of-the-art options for treatment of biosolids, including
an innovative approach being studied by DuPont.
Spring, 1995 A team of five students focused on alterna-
tive processes for recovery and control of gaseous process
effluents from combined sources at the DuPont Chambers
Works. This project was sponsored by Tom Scarfe of Spe-
cialty Chemicals. The team examined state-of-the-art op-
tions for the recovery and control of gaseous effluents, in-
cluding NOx, benzene, CO, 0,, and N,.
Spring, 1995 A second design team of five students
focused on selection and evaluation of state-of-the-art op-
tions for the treatment of leachate from the Southeast Haz-
ardous Waste Landfill at the Victoria Plant. This project was
sponsored by E. B. Keough of the ESD-Gulf Regional Of-
fice. The team examined options for the treatment of haz-
ardous leachate constituents, which were grouped as free
HCN, completed cyanides, free metal ions, ammonium
ions, and organic. Three students from this team joined
DuPont after graduation.
Spring, 1996 Three teams of three students each focused
on different approaches to the production of a marketable
by-product from an aqueous/organic waste stream from adipic
acid production facilities. All three approaches involved con-
centration of the recyclable organic material, reaction, and
refining. The sponsor was Dr. Charles Perilloux of the Sabine
River Laboratory. This project was unusual in that it was not
at the conceptual design level and involved developing AS-

Typical Steps of Preliminary Process
Synthesis and Evaluation

1. Project selection
2. Team selection
3. Project initiation
4. Feasiblity study
5. Narrowing the field of alternatives
6. Preliminary design report and presentation
7. Flowsheet development
8. Estimation of capital and operating costs
9. Selection of most promising alternatives)
10. Final report and presentation

PEN flowsheets of the three routes and using the results as a
basis for estimating the required capital investments. The
deliverables consisted of a final report with details of the
ASPEN process models and the capital investment, and ex-
ecutable copies of the models. A member of one of the
design teams worked for DuPont at the Sabine River Labo-
ratory during the summer following the project, polishing
and optimizing each flowsheet for further evaluation.
Spring, 1996 A second team of three students focused on
alternative processes for recovery and control of gaseous
NO, from tank vent fumes at the Sabine River Works. The
project was sponsored by Victor Kamantauskas of the Sabine
River Works. The team examined state-of-the-art options for
the recovery and control of dilute concentrations of gaseous
NO,. Flowsheets were developed for several destruction and
recovery/recycle technologies using the FLOW program, a
conceptual design simulation developed by the Oak Ridge
National Laboratory.

This project is one of only a few academic experiences
involving a team rather than an individual effort. QDI is
working with the UT faculty advisors to improve the link
between the activities and resource utilization of individuals
and teams and the desired results stated in a team's mission,
vision, and values. The group's mission is spelled out in the
design objectives and is developed in the early stages of the
activity. The student's personal expectations and team ex-
pectations from Spring, 1996, were developed in the initial
meeting and are presented in Table 2. The expectations were
then translated into ground rules and project evaluations,
presented in Table 3.
Students typically alternate weekly as group leaders and
communicate frequently with their advisors. Three hours per
week of scheduled group meetings (with their faculty advi-
sors present is typical); these meetings begin with a warm-
up activity, along with a review of the agenda and a determi-
nation of the appropriate time for each agenda item. The
group leader acts as facilitator for the meeting, while other
key roles are the time keeper (who keeps the meeting on
schedule) and the recorder (who records the key discussion
points and distributes the meeting record).
The meeting concludes with setting an expected agenda
for the next meeting and confirming its date, time, and
location. A few supplemental faculty lectures are presented;
the typical role of the faculty advisor is one of consultant.
reviewer, and coach. The students contribute a great deal
of time to successful conclusion of these projects, similar
to the time required in a typical engineering capstone
design experience.
Team Building Effective team building begins with analy-
sis of the critical elements of the project; this analysis

then leads to clearly defined objectives, deliverables,
and quality measures that translate into task assign-
ments and priorities. The design internship evolves by
incorporation of a total quality approach to definition
and accomplishment of the team goals, summarized in
Table 4. The faculty advisor works on creating a win/
win relationship with the team members and on promot-
ing planning, organization, and record keeping for ef-
fective project performance.
Project Selection Discussions within DuPont begin several
weeks in advance of the project's initiation, with the
faculty advisors typically involved in the final selection
of the project. The selection criteria are based on their
educational benefits, their value to DuPont, and on the
possibility of being completed in one semester. One or
more DuPont personnel volunteer to function as indus-
trial advisors for the students.
Group Membership Selection The students are typically
selected based on their academic achievements and on
completion of an informal interview. Providing equal
opportunity for all chemical engineering students who
have appropriate prerequisite course work is an impor-
tant consideration.
Project Initiation Various formats for project initiation

Personal and Team Expections (1996 Teams)

Personal Expectations
Better knowledge of what industrial activity will involve
Working with a group on a long-term project
Gaining practical engineering experience
Gaining experience at working in groups
Exposure toformal project encountered in "real" world
Opportunity to bring personal learning to actual design
Seeing a design project from initial idea tofinal state
Overall design experience
Ownership; having control over a project
Seeing if this is a desirable graduate-school area of study

Team Expectations
Cooperation and commitment to a common goal
General interest in design task
Being able to take initiative and to complete tasks
Organization; communication
Getting along with others
Team members doing their jobs; not having to do other'sjobs
Having a leader, not a Mother Goose
Working with a diversity of people
Actually solving a problem (not guessing at its solution)

Chemical Engineering Education

Student-Developed Ground Rules and
Evaluation Criteria for 1996 Teams

Ground Rules
Attendance at group meetings by all team members
Participants must display professionalism
Individuals should advise group if there are problems
Equal participation of all members (cross checking)
Members should not let dominant personalities dictate
There should be scheduling offlexible long-term goals
Scheduling so that everyone can contribute
There should befreedomfor anyone to voice concerns
Members should be willing to have an open mind and to address
concerns without anger
Mistakes should be minimized by getting group input

Evaluation Criteria

* Achieving design objectives
* Usefulness of work (quality)
* Timeliness (meeting deadlines)
* Effective use of individual time
* Producing a valuable product
* Ongoing group evaluation

Sinput to project

have been used. In earlier projects, the initiation oc-
curred at a production site where the facility was toured;
later projects have been initiated on campus, some-
times with a visit from the corporate sponsor. In the
initiation discussion, expectations for individuals and
teams are established and project ground rules and
evaluation criteria are set. This activity is facilitated
by the faculty advisor, but input is provided only by
the team members.
Information generated by the students at the initiation
of the 1996 internship is presented in Tables 2 and 3.
The intent of the facilitator in this activity is to create a
win/win situation for all involved.
Information on the project design objectives is pro-
vided, as available, in the initiation meeting. Sometimes
alternative designs are suggested at these meetings and
supporting information is provided, as available; still
other alternative designs are developed by the students
later in the study.
The supporting information may include desired prod-
uct purity, relevant reaction rates and yields, reaction
and phase equilibria information, by-product formation
data, operating- and pilot-plant data, and safety and
toxicity information. Usually, more supporting infor-
mation is available for some alternatives than for others.
Design Objectives An important Project Initiation activity
is the development of design objectives. The purpose of
establishing such objectives is to clearly spell out the
level of effort, the expected resources, and the descrip-
tion and timing of expected deliverables. It is important
that the design team and its advisors have a common
vision as to the design objectives.
Due to limited travel budgets and minimal travel time
available to the students, the current project initiation
generally occurs on campus. When the students visit
their sponsor later in this activity, they are more knowl-
edgeable about the project and perhaps gain more from
their visit than they would otherwise.
It is typical for the students to visit and present a
briefing at the conclusion of their feasibility study or
later in this activity when flowsheeting is complete and
capital and operating costs are known. Attendance gen-
erally includes industrial and faculty advisors as well as
interested industrial personnel.
Feasibility Study The feasibility study provides informa-
tion on the appropriate design alternatives. It ensures
that students have the necessary information to make
their own decisions as to appropriate technology. A
computer search of the literature greatly expedites this
phase of the project.
There is often extensive communication between the

Spring 1997

A Total Quality Approach to
Definition and Accomplishment of Team Goals

1. Objective setting and deployment based on the needs and
expectations of stakeholders (typically customers, employees,
investors, suppliers, and communities.

2. Explicit connection between tasks (methods) and objectives

3. Results-oriented meeting planning and record keeping.

4. Win/win agreements between individuals and team advisors,
including role expectations and Specific, Measurable, Agreed,
Realistic, and Time-phased (SMART) goals.

5. Process and results measurement for feedback.

6. Acquiring, updating, and maintaining the knowledge acquired in
linking the activities and resource utilization of individuals and
teams with the desired results.

students and their industrial project advisors via e-mail,
fax messages, and telephone conferences; video confer-
ences are more expensive, but are still lower in cost than
personal visits. The combination of faxed documents,
speaker phones, and conference calling provides a low-
cost and effective means of communication between a
number of people at different sites.
At the conclusion of the feasibility study, the students

present and discuss their findings with the
corporate sponsor. These are important dis-
cussions for ensuring that the objectives of
the design study are being met and that all
feasible options are identified.
Narrowing the Field At the conclusion of the
feasibility study the alternatives are
screened to ensure that the most appropri-
ate options are considered further. The stu-
dents are encouraged to develop screening
criteria that properly emphasize DuPont's
hierarchy of waste management priorities.
At this phase in the project, material and
energy balance flowsheets have not yet been
developed and no capital and operating costs
have been determined. The results of this
screening step are typically presented to
the corporate sponsor simultaneously with
feasibility discussions.
Preliminary Design Report and Presentation *
The results of the feasibility study and the
alternative screening step are provided
through oral and written reports. The writ-
ten report spreads the report writing tasks
over a greater portion of the semester than
would be the case if only a final report
were required. Essentially all of the mate-
rial in the preliminary report will become

nature and the input-output structure of alternative
flowsheets[31 may be found from examining the reac-
tion step. Information on some waste streams re-
quires discussions with knowledgeable DuPont per-
sonnel in order to get a total view of the wastes
generated in an operating process.
Development of appropriate mass and energy balances
is a critical component of process synthesis and evalua-

The design
internship proceeds
through some
typical steps of
preliminary process
synthesis and
Faculty and
industrial advisors
provide the
necessary conditions
and supportfor a
process design team
to function
effectively. Over
the course of
several projects, the
students have
demonstrated an
ability to handle
increasingly more
design tasks.

part of the final report. The preliminary report and all
sensitive communications may be treated as confiden-
tial. For some projects, students and faculty sign a se-
crecy agreement with DuPont.
Flowsheet Development Identifying waste streams in the
early stages of process design is expedited by consider-
ing waste streams to be either intrinsic or extrinsic.
Intrinsic waste streams are those that are inherent to the
process configuration, while extrinsic waste streams are
associated with the operation of the process.121 Some
waste streams can be identified from macroscopic mate-
rial balances, but identification of other waste streams
may be difficult at an early stage of process develop-
ment. Identification of intrinsic wastes may, at times,
require experimental data; identification of extrinsic
wastes usually requires experience. A great deal of the

tion. Regardless of the computer tool employed,
approximate hand calculations are a critical first
step in the development of mass and energy
balances. Approximate balances, typically us-
ing spreadsheets, tend to be appropriate for the
more "preliminary" process synthesis activities,
although advanced process simulators, such as
ASPEN, may be timesaving devices for diffi-
cult problems such as coupled mass and energy
balances. The FLOW conceptual process de-
sign simulator, developed at the Oak Ridge Na-
tional Laboratory,r4] is very useful for incorpo-
rating the type of information typically avail-
able at the conceptual design level into simula-
tion of mass and energy balances and estima-
tion of capital and operating costs. For post-
conceptual process synthesis, the rigorous
material and energy balance capability of
flowsheet simulators, such as ASPEN, may
be required as a deliverable.
The window for creativity in these activi-
ties comes after the students understand the pro-
cess and its constraints and are formulating or
evaluating their flowsheets. The semi-structured
brainstorming activities of the flowsheet for-
mulation phase may take a considerable amount
of time, but are critical for the opportunity they
offer for creativity.

Estimation of Capital and Operating Costs For prelimi-
nary estimates of fixed-capital investment by anyone
other than an expert, the factored approach has gener-
ally proven reliable and is usually the method selected.
In this method of cost estimating, the purchased cost of
the major equipment items is estimated and the total
fixed-capital investment is estimated by applying a mul-
tiplier (Lang factor) to the purchased cost of the major
equipment items."5 When time for this activity has been
compressed, an approach based on a method by Zevnik
and Buchananr61 has been used; this method must be
carefully applied, however, and calibration of the proce-
dure using actual cost data is recommended. Specific
operating cost information, product cost, and raw mate-
rial costs are consistent with those used within DuPont.
Selection of Most Promising Alternative(s) Selection of

Chemical Engineering Education

the most promising alternatives occurs when capital and
operating estimates have been completed. Again, the
students are encouraged to develop criteria that properly
emphasize DuPont's hierarchy of waste management
options as well as cost and other considerations.
Final Report and Presentation The final design report
from this activity is a business confidential document.
As mentioned earlier, students typically sign a "limited
term" secrecy agreement with DuPont. The agreement
to hold findings of these projects and related informa-
tion secret is important if the students need access to
proprietary information in order to provide a useful
study. The final report is reviewed first by the university
advisors, and after their comments are addressed, it is
reviewed a second time by both university and DuPont
project advisors. A final oral report is also made by the
student design team at the conclusion of the project.

The essential elements of the design internship described
in this paper are functioning successfully. There is both an
opportunity and a need to improve the adherence to project
milestones and for improving the cycle of review-feedback-
revision in the various phases of the project. Responsibility
for planning and execution of the internship rests on the
students. An important expectation is that the concluding
design report be of professional quality; the internship
does not conclude without achieving this goal. Improv-
ing the operating procedures that refine the existing ac-
tivity without reducing it to an academic exercise is likely
to be a continuing goal.

The type of activity described in this paper provides for
involvement of university students and faculty in significant
and challenging projects involving pollution prevention.
Several important steps ensuring successful student de-
sign internships are:
1. The projects should involve worthwhile activities
directly related to the student's prior chemical
engineering courses.
2. The design objectives and ground rules should be
clear and mutually acceptable.
3. Faculty and industrial advisors should provide
effective review and suggestions on an ongoing
basis. Suggestions based on the advisor's prior
design experiences are of substantial value to the
4. Report writing and review should begin early in
the activity. Much of the report should be semi-
complete at the time of the preliminary review. All
work, including basic assumptions, process and

equipment selection, material balances, design
calculations, computer programs/results, and
economic evaluations should be included in the
final report.
5. Cost elements should be similar to those used by
the corporate sponsor and should reflect current
economic conditions. Ground rules for economic
estimations should be included in the Design
6. The design report should be of similar quality to
one expected of a commercial engineering design
7. Students are usually required to use computer
simulation systems during the projects. The
importance of sound judgment in accepting
simulation results cannot be overemphasized.
When credible solutions are achieved, the very
extensive advantages of these systems become
The successful completion of projects such as these supple-
ments corporate design activities, particularly when emerg-
ing technologies are involved. This project and similar ac-
tivities have been well received by the students; their enthu-
siasm, perseverance, and overall quality of work have been
outstanding and sincerely appreciated by their advisors and
sponsors. Participants in these activities typically begin in-
dustrial careers soon after project completion, with a smaller
number going to graduate school.

This activity was supported by a grant from E. I. du Pont
de Nemours and Company.

1. Counce, R.M., J.M. Holmes, E.R. Moss, R.A. Reimer, and
L.D. Pesce, "DuPont Design Internship in Pollution Preven-
tion," Chem. Eng. Ed., 28(2), 116 (1994): Counce, R.M., J.M.
Holmes, and R.A. Riemer, "An Honors Capstone Design
Experience in Chemical Engineering," 5th Pollution Pre-
vention Topical Conference (held in conjunction with the
AIChE 1994 Summer National Meeting) Denver, Colorado
(1994): Advances in Capstone Education (Fostering Indus-
trial Partnerships), Brigham Young University, Provo, Utah
2. Berglund, R.L., and C.T. Lawson, "Preventing Pollution in
the CPI," Chem. Eng., 120 (1991)
3. Douglas, J.M., "Process Synthesis for Waste Minimization,"
Ind. Eng. Chem. Res., 31, 238 (1992)
4. Ferrada, J.J., J.W. Nehls, Jr., T.D. Welch, and J.L. Giardina,
"Modeling a Novel Glass Immobilization Waste Treatment
Process Using Flow," 1996 AIChE Spring National Meeting,
New Orleans, Louisiana (1996)
5. Peters, M.S., and K.D. Timmerhaus, Plant Design and Eco-
nomic Analysis for Chemical Engineers, 4th ed., McGraw-
Hill, New York, NY (1991)
6. Zevnik, F.C., and R.L. Buchanan, "Generalized Correlation
of Process Investment," Chem. Eng. Prog., 70 (1963) 0

Spring 1997

Random Thoughts...


7. Dave, Martha, and Roberto*

North Carolina State University Raleigh, NC 27695

Three engineering classmates are heading for lunch after
a heat transfer test. Martha and Roberto are discussing the
test and Dave is listening silently and looking grim.

Martha: "OK, so Problems 1 and 2 were pretty much out
of the book, but Problem 3 was typical Brenner-he
gives us a heat exchanger design and asks us to
criticize it. I said the design might be too expensive,
but we could say anything and he couldn't tell us
we're wrong."
Roberto: "Sure he could-it was a lousy design. They
were putting a viscous solution through the tube
side so you'd have a big pressure drop to overcome,
the flow was laminar so you'd have a low heat
transfer rate, the salt would probably corrode those
carbon steel tubes, the ..."
M: "Maybe, but it's just a matter of opinion in ques-
tions like that-it's like my English teacher taking
off points because of awkward expression or some-
thing when anyone with half a brain would know
exactly what I was saying."
R: "Come on, Martha-most real problems don't have
just one solution, and he's trying to .. ."
M: "Yeah, yeah-he's trying to get us to think, and I'm
okay with that game as long as I don't lose points if
my opinion isn't the same as his. What do you think,
Dave: "I think that problem sucks! Which formula are you
supposed to use for it?"
M: "It's not that kind of question-not everything has a
formula you can ..."

SMany thanks to Dick Culver and Mike Pavelich for their
valuable comments on a draft of this column.

D: "OK, so when did he tell us the answer? I memo-
rized every lousy word he said after I bombed that
last test and not one had anything to do with .. ."
R: "It's a thinking question-you have to try to come
up with as many ..."
D: "That's bull, man! I already know how to think-
I'm here to learn how to be an engineer."
M: "Dave, not everything in the world is black and
white-some things are fuzzy."
D: "Yeah, in those airhead humanities courses and those
science courses where they spout all those theories,
but not in engineering-those questions have an-
swers, and Brenner's job is to teach them to me, not
to play guessing games or put us in those dumb
groups and ask us to ..."
M: "Yeah, I'm not too crazy about those groups either,
but.. ."
D: ". .. and that's not all-Monday Roberto asked him
that question about the best exchanger tube material
and he starts out by saying 'it depends' I'm
paying tuition for the answers, and if this bozo
doesn't know them he shouldn't be up there."
R: "Look, the teachers don't know everything ... you
have to get information wherever you can-like in
those groups you two were trashing-and then evalu-
ate it and decide for yourself, and then you can ..."

Richard M. Felder is Hoechst Celanese Pro-
fessor of Chemical Engineering at North Caro-
lina State University. He received his BChE from
City College of CUNY and his PhD from
Princeton. He has presented courses on chemi-
cal engineering principles, reactor design, pro-
cess optimization, and effective teaching to vari-
ous American and foreign industries and institu-
tions. He is coauthor of the text Elementary
Principles of Chemical Processes (Wiley, 1986).

Copyright ChE Division ofASEE 1997
Chemical Engineering Education

D: "That's a crock of..."
M: "Um, what did you guys get for Problem 2? I used
the Dittus-Boelter formula and got 4.3 square meters
for the heat transfer area. How does that sound?"
R: "I don't think it's right. I did the same thing at first,
but then I started to think about it some more and I
remembered that you have to be in turbulent flow to
use Dittus-Boelter and the Reynolds number was
only 550, so I redid it with the laminar flow correla-
tion and got..."
M: "Whoa-he never did anything like that in class."
D: "I say we go straight to the Dean!"

These three students illustrate three levels of the Perry
Model of Intellectual Development." 3' The model was
developed in the 1960s by William Perry, an educational
psychologist at Harvard, who observed that students varied
considerably in their attitudes toward courses and instructors
and their own roles in the learning process. The Perry model
is a hierarchy of nine levels grouped into four categories:

Dualism (Levels 1 and 2) Knowledge is black and
white, every problem has one and only one correct
solution, the authority (in school, the teacher) has all
the solutions, and the job of the student is to memo-
rize and repeat them. Dualists want facts and formu-
las and don't like theories or abstract models, open-
ended questions, or active or cooperative learning
("I'm paying tuition for him to teach me, not to teach
myself."). At Level 2, students begin to see that some
questions may seem to have multiple answers, but
they still believe that one answer must be right. Like
many entering college students, Dave is at Level 2.
Multiplicity (Levels 3 and 4) Some questions may not
have answers now, but the answers will eventually be
known (Level 3) or responses to some (or most) ques-
tions may always remain matters of opinion (Level
4). Open-ended questions and cooperative learning
are tolerated, but not if they have too much of an
effect on grades. Students start using supporting evi-
dence to resolve issues rather than relying completely
on what authorities say, but they count preconcep-
tions and prejudices as acceptable evidence and once
they have reached a solution they have little inclina-
tion to examine alternatives. Many entering college
students are at Level 3, and most college graduates
are at Level 3 or 4. Martha is at Level 4.

Relativism (Levels 5 and 6) Students in relativism see
that knowledge and values depend on context and
individual perspective rather than being externally
and objectively based, as Level 1-4 students believe
them to be. Using real evidence to reach and support
conclusions becomes habitual and not just something
professors want them to do. At Level 6, they begin to
see the need for commitment to a course of action
even in the absence of certainty, basing the commit-
ment on critical evaluation rather than on external
authority. A few college graduates like Roberto attain
Level 5.*

The key to helping students move up this development
ladder is to provide an appropriate balance of challenge and
support, occasionally posing problems one or two levels
above the students' current position."21 (They are unlikely to
comprehend wider gaps than that.) If teaching is confined to
single-answer problems, students will never be impelled to
move beyond dualist thinking; on the other hand, expecting
most freshmen to think critically when solving problems and
to appreciate multiple viewpoints is a sure recipe for frustra-
tion. Instructors should assign open-ended real-world prob-
lems throughout the curriculum but should not make course
grades heavily dependent on the outcomes, especially in the
freshman and sophomore years. They should have students
work in small groups (automatically exposing them to multi-
plicity), model the type of thinking being sought, and pro-
vide supportive feedback on the students' initial attempts to
achieve it. While doing those things won't guarantee that all
of our students will reach Level 5 or higher by the time they
graduate, the more we move them in that direction the better
we will be doing our job.

1. Culver, R.S., and J.T. Hackos, "Perry's Model of Intellectual
Development," Engr. Ed., 72, 221 (1982)
2. Pavelich, M.J., and W.S. Moore, "Measuring the Effect of
Experiential Education Using the Perry Model," J. Engr.
Ed., 85(4), 287 (1996)
3. Perry, W.G., Forms of Intellectual and Ethical Development
in the College Years, Holt, Rinehart, and Winston, Inc., New
York, NY (1970) I

At the highest category of the Perry model, commitment within
relativism, individuals start to make actual commitments in
personal direction and values (Level 7), evaluate the conse-
quences and implications of their commitments and attempt to
resolve conflicts (Level 8), and finally acknowledge that the
conflicts may never be fully resolved and come to terms with the
continuing struggle (Level 9). These levels are rarely reached by
college students.

Editor's Note: All of the Random Thoughts columns are now available on the World Wide Web at

Spring 1997

M% -classroom



Colorado School of Mines Golden, CO 80401-1887

Reflecting an overall information revolution, commu-
nication across the Internet has evolved rapidly in
the past few years, from primarily text-based (e-
mail) information to graphically oriented material. This has
been due to the amazing growth of the World Wide Web
(WWW) and the development of web browsers, beginning
with NCSA Mosaic but now including Microsoft's Internet
Explorer (based on Mosaic) and the current market-dominat-
ing Netscape.'" The academic community has, for a number
of years, been fervent in its use of the Internet (how long
could we survive without e-mail?) and has expanded its use
as the Internet has grown. The desire to remain at the fore-
front of information technology has led to significant aca-
demic discussion concerning the use of the WWW and the
Internet in undergraduate and graduate education.12- 4
Much of the discussion about using the Internet has con-
cerned incorporation of the vast amount of information avail-
able across the Web into the curriculum. Given a Universal
Resource Locator (URL-basically a web address), one can
immediately travel throughout the world and obtain infor-
mation (text, images, files, programs, etc.) that have been
posted on the Internet. The tools that have been developed
David W.M. Marr is Assistant Professor of chemi-
cal engineering and petroleum refining at the
Colorado School of Mines. He received his BS
from the University of California, Berkeley (1988)
and his PhD from Stanford (1993). His research
interests include interfacial phenomena, complex
fluids, semicrystalline polymer blends and com-
posites, and scattering techniques.

J. Douglas Way is Associate Professor of chemi-
cal engineering and petroleum refining at the Colo-
rado School of Mines. He received his BS, MS,
and PhD from the University of Colorado, Boulder.
His research interests include novel separation
processes, membranes, catalytic membrane re-
ri actors, n oo and biopolymeradsorbents for heavy metal
remediation of ground and surface water.

for browsing through the Internet are not only capable of
surfing the net but also of distributing information within a
corporation, a university, or even within the classroom in a
similarly convenient fashion. In the same manner that these
browsers and the Internet have made accessing information
across the world nearly instantaneous and interesting, the
intranet can be used to assist instruction and information
distribution within the classroom.
Wouldn't it be nice to

Improve your undergraduate courses with your exist-
ing campus network?
Improve communication with your students and col-
Save resources (such as paper) by publishing assign-
ments, solutions, course syllabi, exams, and quizzes on
the WWW?
Publish grades and scores on the intranet while pro-
tecting students' security?
Provide assistance to students outside of the classroom
or office hours?
Provide student access to course materials twenty-four
hours a day (and thereby eliminate a host of common
Obtain truly anonymous feedback from students?
Advertise your course to a broader audience both on
campus and outside your school?

The goal of this article is to describe our efforts to incorpo-
rate the intranet into the instruction of an undergraduate
chemical engineering course and to relay those aspects of
the incorporation that appeared to be most useful. We will
also give some tips for developing Web-based materials,
including a discussion of the current status of Web standard
development and the various tools available to aid in Web

Copyright ChE Division ofASEE 1997

Chemical Engineering Education

page construction. In our own experience, some of the things
we have attempted have worked quite well, while others
have been less successful. We hope that those who attempt
to duplicate our efforts in their own department at some time
in the future can benefit from this discussion.

At the Colorado School of Mines (CSM), develop
we are well poised for incorporating the through
Web into undergraduate chemical engineer- to h
ing instruction. This is due to a large dona- not only cc
tion and the construction of the Bernard the ne
Coady computer laboratory incorporating 22 distribute
IBM RS/6000 workstations in a classroom within a.
environment. These workstations are used a similar
throughout the undergraduate chemical en- fashion
gineering curriculum,'15 primarily as a tool
for using the ASPEN and Provision simula- manni
tors 67v1 in courses ranging from the initial browsers
mass/energy balances course all the way have m
through the senior design course. This work- inform
station classroom is also used in teaching wol
organic chemistry with Spartan molecular in
modeling and visualization software. 81
Because of the required and heavy use of
can be
networked workstations in their other
coursework, students have ready access to ins
the Internet. In addition, many students also informal
have access to the Web from their home or within i
dorm via dial-up access to the CSM net-
work or other external networks (such as
Compuserve and America On-Line) and are able to readily
obtain classroom information. In fact, a recent survey of heat
transfer undergraduates showed that every single student in
the class knew how to access the WWW and that fully two-
thirds of them could access the Web from their home/dorm.

Academicians are not noted for having a lot of free time,
so the first question one of them usually asks is, "What do I
get in return for the time investment required to incorporate
the Web into classroom instruction?" It is a difficult ques-
tion to answer because the Web is always evolving-prob-
ably at a rate proportional to the rise in the use of the
Internet itself. As the number of uses for the Internet
increases, so do the conceivable applications of having
such a resource available.
Our approach in this initial use of Web-based materials
has been focused on the ability to rapidly disseminate infor-
mation in a convenient manner. There are, however, a num-
ber of other possible advantages in using the Web to aid in
the instruction of an undergraduate course. They include the

Spring 1997

ability to incorporate supplemental course materials such as
pictures, diagrams, videos, and even links to other informa-
tion sources across the Internet. Having the course home
page also provides a ready means of communicating with

the class outside

of the lecture, thereby giving the instructor
some flexibility in the course outline. In
general, though, and especially in this
initial incorporation of the Web into our
course, we hoped that making class ma-
terials readily accessible to students out-
side of the classroom would aid in their
assimilation of the subject matter.

that have been
d for browsing
he Internet are
liable of surfing
t but also of
ng information
.. classroom in
rly convenient
. In the same
er that these
and the Internet
ade accessing
tion across the
Id nearly
taneous and
ng, the intranet
used to assist
action and
ion distribution
he classroom.

materials, can be quite easy. The HTML "language" is text-
based and can therefore be created and read with a large
number of applications and word processors. Various tools
for converting files such as those produced by Word,
Excel, and LaTeX to HTML are available on the Internet.
For those who are interested in preparing their own docu-
ments directly, or in optimizing files created using con-
verters, a number of excellent tutorials are available on
the Internet. They include:
* A Beginner's guide to HTML
A Bare Bones Guide to HTML
*The Web Designer (This site has a great list of the
converters currently available on the Internet for the various
computer programs and platforms.)
In addition to the above, Java is the latest development in
incorporating new capabilities into Internet browsing soft-
ware. Developed at Sun Microsystems, Java is a true pro-

In order to use standard Web brows-
ers in displaying classroom materials,
the documents and graphics must be for-
matted in the language of the Internet.
This requires converting documents pre-
pared by other means (LaTeX, Word,
Excel, etc.) into Hypertext Markup Lan-
guage (HTML). Once they have been
converted to HTML, any browser soft-
ware can be used to preview the docu-
ments before they are added to the course
Web site.
Hypertext Markup Language is a rela-
tively simple means of preparing docu-
ments in a manner that various browsers
can use to display information in a for-
matted manner. Preparing documents in
HTML, particularly simple text-based

gramming language for the Internet that, in its simplest
form, allows incorporation of animation into Web pages.191 If
your browser is Java-capable (most current browsers are-
Netscape has such versions available for UNIX worksta-
tions, PCs, and Macs), a great site for exploring its capabili-
ties is
Also, for a glimpse of the educational possibilities of Java,
We did not attempt to include Java into the class home
pages; in fact, Netscape browsers including Java were not
available until the middle of the spring semester in 1996.
Certainly though, Java has potential for aiding in instruction
and providing demos that would be more readily
assimilated by the 'Nintendo' generation.

The authors have each taught a section of a
semester-long junior-level heat transfer class
with a total enrollment of 75 students. In gen-
eral, most of the features we placed on the class
home page were well received by the students
in the course. To keep track of general usage,
we used a counter similar to an automobile
odometer (see
for a nice counter that runs externally and can
keep track of such things). The number of times
the class home page was accessed during the
semester was about fifty times (hits) per week,
totaling around 850. Specific usage statistics,
however, were not compiled, so the number of
times students were accessing homework solu-
tions versus course grades, for example, were
not kept. (Some usage information was ob-
tained directly from the students during class
evaluations, however, the results of which are
shown graphically in Figure 4, which will be
discussed in detail later.)

The class home page (see Figure 1) includes:
Urgent Messages These were placed at the
beginning of the course page and blinked if
they were particularly urgent. Example mes-
sages included reminders of upcoming ex-
ams or changes in scheduled class quizzes.
This feature also proved extremely useful
when sudden changes in office hours were
necessary-placing an announcement on the

page prevented many students from showing up at the
door and finding us unavailable.
Course Syllabus A description of our policies on
grading, homework, and exams so that students would
always have access to the information.
Course Outline A description of where we expected
to be throughout the course.
Course Objectives Outlines of what we intend for
the students to learn throughout the course.
Office Hours Office hours are given.
Schedules Our weekly schedules are displayed so
students will know when we are available. This also
makes it convenient for other professors or secretaries
who are trying to put together meetings (such as com-
mittee meetings). When we receive e-mail asking about

- Nelfape: (EPR 308 ..

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02i. s: 1. 3:60*4:00, TTm 12:60-2M00
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Sores: CR308AO C]R308B G
Gnderv.: Reia semt, uscan Rlke
Offic. Xe.r: 9T 9:15-10:00
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,# Cws E-SThiu Outine obijetives Var nous
Si C 1- 308 117"96 Materia
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ours, Links to
ages and Email

assignments and
ck Forms and

Class Reference

Figure 1. CEPR 308 home page.
Chemical Engineering Education

availability, we give out our URLs. This also turns
out to be useful information for other researchers that
we collaborate with across the country-by having
such a guide available, they know the best times to try
to contact us directly.
Practical Issues As discussed above, translators from
software we typically use to prepare course materials are
extremely useful. Examples include TextToHTML (freeware
for the Macintosh) that can convert Microsoft Word docu-
ments (or any word-processing software that can save files
in rich text, or RTF, format) to HTML. The major drawback
of these translators is that embedded graphics are not dealt
with in a simple manner. One typically needs to deal with
them separately (converting them from their original format
to gif or jpeg) and then either embedding them or including
links to them from the converted HTML file. Currently,

'-=_-- ... Nelreape: [Ham I _-

.Bad ... k orr,, pa Iy ODPn Pr-t Fw
' L | 'C d I I" I .. : i .. Y .. r ... I .. /

Ex_ #1
CF. ?- Spew;B 1996r

however, large strides are being made to address this prob-
lem. For example, Microsoft has made available tools that
work directly with Microsoft Office-for example, "Internet
Assistant," available at

Weekly homework assignments were distributed both in
class and on the Web. When students would ask if we had an
extra copy of the homework, we would tell them it could be
downloaded from the Web at their leisure-about half-way
through the semester they stopped asking. Solutions to the
homework problems were also available on the Web, as an
aid in solving the assigned problems. Having the solutions
available on the Web meant that students could access them
when they were most needed-the night before the home-


' pl iiok,; ino n owt"- nter ow iit OB s ire
| ytt. I Ai d nic;rl. Pi- ciiw I. '"oti o; -.h? 1 'rpzS
| ttW

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ra1-ii.!., a ;'mialh.,' t .ly the .jt.L ttli k .i mt lI
*:ilv ii tiyl, d e-r-,ma* th e rmprt; c pro'lr The
eitt :ra, lret, 1 t, erlSZ .u ,4 i t a .. try_
neilu a it ie llt. tih V p I l ii : Lter V'iSJ the
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. .,bi,-a w r-,, Ti. f

*-. C

-' ^ 4 4 U
2/>i '? > '

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2, i



Figure 2. Clicking on the solution link displays scanned
image of problem solution.
Spring 1997

work was due and after the li-
brary had closed.
Quizzes were typically given
biweekly, and if a quiz were de-
layed, an announcement to that
effect would be placed on the
class home page. Quiz solutions
were also posted on the Web, just
as the homework solutions were.
As far as midterm exams were
concerned, the exam and its solu-
tions were posted on the Web after
the test had been given (see Figure
2). From the usage statistics, how-
ever, it is clear that many students
still preferred to obtain solutions
by photocopying them from the
library, as opposed to getting them
off the Web. The motivation for
this is unclear-whether it is just a
habit that will change over time or
if it is simply easier to go to the
library and photocopy as opposed
to logging onto a computer.
Practical Issues There is pres-
ently no real standard for Internet
browsing software or the com-
puters that run them. Currently,
Netscape controls about 85% of
the market, so the pages we have
written are designed for it.l] For
text-based solutions there is no
problem since text typically
comes across clear and easy to
read on any browser capable of
accessing the class home pages.
Many of the solutions for the un-

dergraduate heat transfer course, however, are equations or
mathematical derivations, and there is currently no HTML
standard for marking up equations (although this should
change when HTML 3.0 becomes available). Subscripts and
superscripts are supported with the and com-
mands, respectively, but a comprehensive math environment
has yet to be incorporated. Current plans call for equation
commands in a flavor similar to LaTeX to be incorporated
into this environments (in fact, there is a converter available
called math2html that will convert equations typeset in LaTeX
to HTML 3.0). Until the full math environment is incorpo-
rated into the most popular browsers, however, writing equa-
tions in HTML 3.0 will make little sense. Currently, there-
fore, the process involves writing out the solutions and then
scanning them into the computer as an image file for display
on the Web (gif and jpeg are the most common formats).
These images can appear quite different on different com-
puters with different browsers and different monitors of
differing resolutions. This makes displaying solutions for all
users in a readable and printable fashion extremely difficult.
Our final solution was a compromise arrived at through an
iterative process involving feedback from students with
widely differing setups. For those who prepare their docu-
ments using LaTeX, another solution is available-the
LaTeX2HTML converter found at
This application will convert the entire document to HTML,
including equations, not through the markup expected to be
available in HTML 3.0, but by converting them into graphic
files that can be directly incorporated. Most of us, however,
do not prepare our homework assignments and solutions in
LaTeX, so we eagerly await the full incorporation of the new
standard into Netscape and the other popular browsers.

A side note about the full implemen-
tation of HTML 3.0 is that the only
browser that includes this is Arena, avail-
able at
This browser, however, is not intended
as commercial software and is cur-
rently used only for development of
future standards.

Grades, including homework, quiz, and
exam scores, are posted on the Web. This
allows students to check and keep track
of their grades throughout the semester so
there will be no surprises when the course
is over. Other incorporated amenities in-
clude test grade distributions and graphs.
Practical Issues Students may not
want their grades posted in a public place.

At CSM, student scores at the end of the semester are posted
outside professor's doors via their student numbers. It doesn't
seem prudent to use these to post their grades to the Internet, so
grade numbers were randomly generated instead. Also, to
further make grades inaccessible to those who have no particu-
lar need to peruse them, access to this part of the class home
page was limited to our local domain,
For httpd servers, the process can be a relatively simple one.
One need only create a particular file within the UNIX
directory in which access for Internet users at large is to be
prevented (see Figure 3). Preventing access in this manner,
however, has a disadvantage in that students accessing the
class home page from home using an outside vendor
(Compuserve, etc.) will be unable to see their grades.
In regards to grade preparation, spreadsheets are a conve-
nient way to keep track of scores, and there are tools avail-
able for translating such documents into Web-based files.
Specifically, translators from Microsoft Excel to HTML are
available-two examples include XTML (shareware) and
CSV-to-HTML (freeware), both available on the net at

One of the interesting things that can be done with the
latest browsers is the incorporation of forms into Web pages.
Properly designed, this capability can be used to solicit
anonymous feedback from the students (see Figure 4). The
opportunity to deliver anonymous feedback to an instructor
can be taken advantage of, however, particularly in an un-
dergraduate course. For the most part though, feedback was
quite positive and was typically directed at getting us to do
more demos in class. Having such feed-

Figure 3. Limiting access.

back during the course, as opposed to
the end of the course, allows incorpo-
rating suggestions in a timely fashion.
If an anonymous feedback form is used,
we suggest that a response section also
be included to allow for replies to the
concerns submitted as feedback.
Practical Issues Setting up a form
for the course home page is a little more
difficult than standard HTML markup.
It requires not only preparing an HTML
document that can handle the entering
of data, but also a script (which can be
written in perl, for example) that knows
what to do with the data once it is en-
tered (such as forwarding it as mail).
Details of this procedure are beyond
the scope of this article, but are covered
in many newly available references on
Web publishing.""0 Using a template
Chemical Engineering Education

To limit access to a specific unix
directory within domain
create a file named ".htaccess"
which contains:

AuthUserFile /dev/null
AuthGroupFile /dev/null
AuthName Example
AuthType Basic

order deny,allow
deny from all
allow from

available from these references, one can design a feedback
form that readily sends the anonymous information. One word
of warning, however, is that such scripts can be vulnerable to
attack and must be carefully written before being published on
the Web. Additionally, and as with the course grades, access to
the feedback form was limited to the local domain to prevent
anonymous feedback from non-CSM students.

Figure 5 shows the results of a survey given to the students

CR308 canments
Pofessors Way and Manz wouldvey much like to haveyou input on the cowse so that they can
make it better as the class goes along. Please help them out by completingthis form and
submitting it. This form is completelyanoymos; unless you include you name they ll have no
idea who submitted it (they can't even check handwriting so please keep profamtyto a
miilm r).

Your name (optional):
Your section? B
Howwould youate the lectures?
SI can stayawake the entire 50 minutes!
.; Ok,40mmutes
: We have lectwes?
Howwould you rate the quises (checkone)?
1. Q Ilovethem,pleasehavemoee.
2. They'leinteesting.
3. O Theye ok.
4. ] Theysuck.
Favorite Coordinate system? Uncoordinated
Any conent on hsowe can help you further?
This is yowu golden oppozrtmity..,


Figure 4. Feedback ft ofform.

Figure 4. Feedback form.

Figure 5. Student-use statistics.
Spring 1997

concerning how they actually used the class information
published on the Web. Of the students in the class, about
20% did not use any of the Web features; of the other 80%,
the three most popular features were access to homework
solutions, access to grades, and quiz/exam solutions. Other
features were clearly less frequently used by the students, e-
mail help being a notable example. It may just be too diffi-
cult to formulate a cogent question concerning a homework
problem via e-mail.


We have described both the methods necessary to use the
intranet and the available Web browsers to disseminate in-
formation to students in an undergraduate chemical engi-
neering course. Many freeware or shareware conversion utili-
ties are available on the Internet to convert course materials
prepared using standard word processing and spreadsheet
software to the necessary HTML format. These tools greatly
simplify construction of a course home page, making a highly
detailed knowledge of HTML unnecessary.
It appears that many students were eager to take advantage
of the course home page features, possibly due to the current
public interest in the Internet. Although students in the course
were not required to use the Web, many of them did so.
Exposing the students to the latest technology and intro-
ducing them to such a massive resource as the Web
should also prove useful to them in their future
coursework. Making students comfortable in understand-
ing and using the computer's capabilities is one of the
goals that we, as educators, have to better prepare our
students for future employment.
This article and the associated hypertext links are avail-
able on-line at
or via links from the CEPR department home page at

1. Levy, S., "The Browser War," Newsweek, 127(18), 47 (1996)
2. Fogler, S., and J.C. Piana, "Development of an Undergradu-
ate Course Web Site," Cache News, 42, 17 (1996)
3. Bungay, H., and W. Kuchinski, "The World Wide Web for
Teaching Chemical Engineering," Chem. Eng. Ed., 29(3),
162 (1995)
4. Terry, T.M., "Teaching Microbiology with the World Wide
Web," ASM News, 61, 401 (1995)
5. Dorgan, J.R., and J.T. McKinnon, "Mathematica in the ChE
Curriculum," Chem. Eng. Ed., 30(2), 136 (1996)
6. ASPEN Plus version 9.0, Aspen Tech, Cambridge, MA 02141
7. Provision, Simulation Sciences Inc., Brea, CA 92621 (http://
8. Spartan Version 4.0, Wavefunction Inc., Irvine, CA 92715
9. See, for example, van Hoff, A., S. Shaio, and 0. Starbuck,
Hooked on Java, Addison-Wesley (1996)
10. See, for example, Savola, T., "Special Edition Using HTML,"
Que Corp. (1995) C'




Milwaukee, Wisconsin
June 15-18, 1997

Chemical Engineering Division Program


#1213 Effective Teaching in Large Lectures
Students Plus!
Teaching and Reaching Large Classes
Integration of Critical Thinking and Technical Communication into Undergraduate Lab Course
A Secret to Large Classes-Showing You Care
Beating the Numbers Game

#1613 Homework Problem and Lecture Exchange
Estimation of Optimum Pipe Diameter and Econonomics for a Pump and Pipeline System
Reactor Design with MATLAB in a Manufacturing Environment
Simulation Graphics: Software for Visualizing Stagewise Design
Designing a Pumping System: Why Worry About Other Process Elements?

#2213 Curriculum Assessment
Linking Classroom Teaching to Assessment in an Ability-Based Curriculum
Preparing for Criteria 2000: A Chemical Engineering Perspective
Criteria 2000-The New Game-How Does it Play Out?
Experiences with ABET Criteria 2000 and Outcomes Assessment

#2313 Undergraduate Research Experiences in ChE
The Case for Uundergraduate Research: Experience in its Use at the University of Missouri-Rolla
Building an Active Environmental/Chemical Engineering Research Program with Undergraduate Students
Introducing Underrepresented Students to Research Through Funded Programs
Outcomes Assessment of a Multi-Task, Multi-Institutional Project
Undergraduates Research Experiences Developing Virtual-Reality Based Educational Modules

Check out the 1997 ASEE National Meeting Program at

Chemical Engineering Education

#2513 Laboratory and Lecture Demonstrations
Fluid-Phase Equilibria from a Process Simulator
Small Group In-Class Problem Solving Exercises
A New Multipurpose Fluid Flow Experimental Module
Experiments in Waste Processing for Undergraduates
The Use of Peer Review in the Undergraduate Laboratory
Demonstration of Chemical Engineering Principles to a Multidisciplinary
Engineering Audience

#2613 Developing New Courses in the Chemical Engineering Curriculum
The Start-Up Company Approach to Teaching Semiconductor Processing
An Interdisciplinary Program and Laboratory for Printed Circuit Board (PCD)
Design and Manufacturing
A Course in Chemical, Pharmaceutical, and Food Procesing
Revitalizing Statistics in the Chemical Engineering Curriculum
A New Senior-Level/Graduate Course in Cellular Bioengineering

#3213 Innovative Use of Computers in Chemical Engineering
Ten Steps to Developing Virtual Reality Applications for Engineering Education
Framework for a Computer-Based Corrosion Course
Experiments in Learning Chemical Engineering Modeling Skills
Applications of ASPEN in Senior Design Projects
The Use of Process Simulation Software in Suphomore and Junior Chemical
Engineering Courses.

#3513 Case Studies in Chemical Engineering
Choices and Foundations-An Introduction to Chemical Engineering for First-
Year Students
Allyl Chloride Production-A Case Study in Debottlenecking, Retrofitting, and
A Case Study in Stoichiometry Course Using Excel and Power Point Presenta-
The Story of Polyethylene Garbage Bags
Early Introduction of Design Fundamentals into the Chemical Engineering

#3613 Environmental Chemical Engineering
Chemical and Environmental Engineering: A Partnership in Pollution Preven-
Developing and Interdisciplinary Environmental Engineering Program
Educating Chemical and Environmental Engineers in Semiconductor Processing
Infusing Environmental Education into the Chemical Engineering Curriculum:
A Minor in Environmental Engineering Science


#1413 Chemical Engineering Division Chairperson Luncheon
#2412 Chemical Engineering Division Executive Committee Luncheon
#3413 Chemical Engineering DivisionBusiness Meeting and Luncheon

Spring 1997

MM] classroom




Across An Integrated Laboratory Sequence

University of North Dakota Grand Forks, ND 58202-7101

here can be little doubt that the development of effec-
tive oral and written communication skills is an es-
sential component of an engineer's undergraduate
education. Regrettably, strong communication skills remain
the exception rather than the rule for many engineering
graduates.'" Kranzber121 reported that, for engineers who had
been out of school for ten years, the most common answer to
the question "What courses do you wish you had taken?"
was English and/or writing courses.
The Canadian Accreditation Board has even included a

James A. Newell became an assistant profes-
sor at the University of North Dakota in 1995
after spending one year at Clemson University
as a visiting assistant professor. His research
focuses on high-performance polymers and com-
posite materials. He is a member of the Ameri-
can Carbon Society, AIChE, and serves as a
board member of the New Engineering Educa-
/ tors Division of ASEE.

Steven P. K. Sternberg received his PhD
from Purdue University in 1994. He was an
assistant professor at the University of De-
troit Mercy before going to the University of
North Dakota in 1995. His interests include
groundwater transport modeling, metal re-
moval from waste water, and environmental

Douglas K. Ludlow served as the chair of the
chemical engineering department at the Univer-
sity of North Dakota from 1994 to 1996. He
recently left UND to become the chair of the
chemical engineering department at the Univer-
sity of Missouri-Rolla. His research focuses on
surface characterization and fractal analysis of
chemical phenomena.

statement requiring that students' communication capabili-
ties be developed.13? Fortunately, many engineering pro-
grams now focus on the developing the entire engineer-
ing student by incorporating the concept of writing-to-
learn in their curricula.14 61
Despite this growing consensus, there remains little agree-
ment on how best to approach the cultivation of these skills.
Some argue that humanities electives are the appropriate
forum for addressing these concerns, but Stevenson[7] ob-
serves that as an engineering student's perception of a course's
connection to engineering decreases, the amount of time
spent on that course also tends to decrease. Thus, by failing
to connect the importance of written and oral presentations
to engineering careers, we are undermining the perceived
value of these skills, despite the fact that most engineers will
find themselves writing memos, reports, or articles through-
out their careers.18 Thus, it is essential that the importance of
writing and oral presentations be related to the core engi-
neering principles that the students value.
A movement to integrate writing across the curriculum has
been undertaken at many universities, including the Univer-
sity of North Dakota.141 Clearly, this is a departure from the
classical view of many engineering lecturers who would
claim that they are too busy teaching engineering to teach
writing. The ability to formulate a coherent written report,
however, requires that the student think clearly about the
engineering problem.19'0' Although these programs repre-
sent a distinct step forward, they do not address the problem
of how to incorporate the development of communication
skills into the curriculum. At the University of North
Dakota, we have developed an integrated laboratory se-
quence to systematically enhance the communication
skills of our students.

Copyright ChE Division ofASEE 1997

Chemical Engineering Education

... it is essential that the importance of writing and oral presentations be related to the core
engineering principles that the students value.... The University of North Dakota uses a four-semester, four-
course laboratory sequence [to develop these skills]. Each class is designed to build upon the technical and writing
concepts and skills developed in the previous class. Care is taken, however, to ensure that these skills enhance
rather than replace the important technical skills developed in the lab.

The University of North Dakota uses a four-semester,
four-course laboratory sequence. Each class is designed to
build upon the technical and writing concepts and skills
developed in the previous class. Care is taken, however, to
ensure that these skills enhance rather than replace the im-
portant technical skills developed in the lab. The lab instruc-
tors stay in regular communication and coordinate group
selection and writing assignments. Additionally, the depart-
ment has hired a quarter-time writing consultant to aid in
evaluating the reports. The consultant is an engineer with
industrial experience in evaluating technical reports. She
assists in Labs II through IV. The individual lab classes are
described in the following paragraphs.

Labl )

The first lab, taken during the second semester of the
second year, focuses on the fundamentals of laboratory mea-
surements and writing. Students work in three-person groups
and submit individual reports. The ten reports in Lab I con-
sist of one-page summary memos to the instructor. This
introductory lab class forces students to selectively reduce
an entire experiment's worth of information down to only
one page of relevant text. Writing assignments are frequent
and the feedback is rapid. There are no oral presentations
required in this lab.

Lab II

The second lab class focuses on the chemical and physical
properties of materials and is taken in the first semester of
the third year. Again, the students work in three-person
groups, but the nature of the reports changes dramatically.
The student groups write a single-group memo for each
experiment, similar to the individual reports in Lab I, but this
time the memo is returned to the students with detailed
feedback. The students then return to the lab and acquire
additional data, and each group member is required to sub-
mit a final report in one of the following formats: Technical
Journal, Operations Manual, Oral Presentation, or Peer Re-
view (all described in the following paragraphs). As a conse-
quence of the expanded format, each group runs fewer ex-
periments than it did in Lab I. Each group runs a total of four
experiments and spends four three-hour lab classes acquir-

Spring 1997

ing data for each experiment.
Technical Journal The technical journal article is the
standard for engineering research. Each student is expected
to produce a report that includes an abstract, an introduction,
an experimental-methods section, a theoretical development,
the results and discussion, the conclusions, the recommen-
dations, and references. The student must examine outside
sources to write a coherent introduction and must fully un-
derstand the experiment to write a reasonable results-and-
discussion section. The students is required to submit three
copies of the report; one is graded by the faculty instructor,
one by the writing consultant, and the third is given to
another student for peer review.
All three copies of the report and associated critiques are
returned to the student. The grade is determined by a weighted
average of the writing consultant and the faculty instructor's
grade (the student peer review does not impact grading). The
student is required to revise the report based on the three
reviews and to resubmit a final draft of the technical journal
at the end of the semester. The final draft is graded by the
writing consultant and the instructor and is worth twice the
number of points as the earlier draft.
Operations Manual One member of each group is re-
quired to develop a detailed operations manual. He or she is
told that the company sells experiments to high school chem-
istry classes. The student must develop an instructional packet
that will enable high school students to perform the experi-
ments with minimal supervision. The packet must also ad-
dress data analysis and include complete sample calcula-
tions. The students must also generate a cover letter, thank-
ing the high school instructor for purchasing the product and
explaining the proper use of the manual. This report forces
students to address a less sophisticated audience than did the
technical journal.
Oral Presentations One member of each group is re-
quired to give a twenty-minute oral presentation based on
his or her experiment. The student is provided a sample
"audience" to which the presentation should be targeted.
These audiences include scientists at a technical conference,
a group of marketing executives, or a room full of high
school students. The student is expected to present material
at a level commensurate with the target audience. The grade
for the oral presentation is weighted as equivalent to one
written report. Students are graded by the Lab II instructor,


the writing consultant, and the Lab III instructor, although
all students fill out an evaluation form (shown in Figure 1).
The different oral presentations are scheduled at different
times throughout the semester, and all students are required
to attend every presentation. Invariably, the students who
present later in the semester make fewer mechanical or lack-
of-preparation errors. They have learned from watching and
evaluating the previous speakers. Therefore, each report type is
graded independently to minimize the disadvantage to students
who presented early in the semester.

Peer Review During the course of the
semester, each student is given a copy of
another student's technical journal. The re-
viewing student is expected to perform a
detailed review of the paper, identifying both
strengths and weaknesses, making recom-
mendations for revision, and identifying ad-
ditional data requirements. Although the stu-
dent review does not affect the grade of the
student who wrote the journal article, the
review itself is graded as a lab report. By
requiring students to perform a formal re-
view of another student's work, the students
are forced to consider what elements lead to
an effective technical journal. Additionally,
the extra review provides more feedback to
the student author of the original paper, which
facilitates the revision process.


The students continue to measure chemi-
cal and physical properties and are exposed
to unit operations in the third lab, taken dur-
ing the second semester of the third year.
Students work in groups of three, but each of
them submits an individual report and each
is assigned a different type of report. Experi-
ments are performed in two distinct halves.
The first half follows a standard written pro-
cedure, while the second half requires the
group to design and implement changes to
the original experiment that either improve
the precision/accuracy or explore an inter-
esting sub-part of the original experiment.
The goal is to provide students with a taste
of how research can be conducted, as well as
to give students an opportunity for critical
thought. The three groups of reports include
1) poster presentation (which includes a writ-
ten abstract) and an oral presentation, 2) a
memo-to-file and a technical paper, and 3) a
memo-to-customer and an operation manual.

Because a report is due from each half of the experiment, the
students write a total of six reports on three experiments.
The report styles are very similar to those described in the
Lab II section, with the exception of the memo formats. For
these memos, the students create short (four-page) descrip-
tions of their work and its results. They also must discuss at
least one concrete improvement that can realistically be imple-
mented that will improve or expand on the results obtained.
This improvement is the basis for the second part of the
laboratory. All written reports must also include the follow-
ing appendices: information on chemical hazards, proper

Oral Presentation Evaluation Form


IUnacceptable: 1 Marginal: 2 Fair: 3 Good: 4 Excellent: 5

Organization (overview of presentation, summary, flow, use of time, etc.)

Poise and Appearance (appropriate dress, fidgeting, nervousness, etc.)

Delivery (eye contact, voice, rate of delivery, etc.)

Overheads and Aids (neatness, font size, titles and labels, use of space, etc.)

Content (level of information, adequate discussion and analysis, summary, etc.)

Questioning (poise, interaction with audience, overall answer)

Overall effectiveness (did the speaker achieve his or her objectives?)

Total Score (35)

Figure 1. Oral Presentation Evaluation Form.
Chemical Engineering Education

environmental precautions (especially waste disposal), and
human safety (e.g., proper operation of equipment).

Lab IV

The final lab in the sequence is taken during the first
semester of the fourth year. It focuses on unit operations,
process control, and optimization. Again, three-member
groups are used, but all submissions are group reports. The
technical journal and oral presentations exist as in Labs II
and III, but are written or presented by the entire group. In
addition to these report formats, the students are required to
submit a memo-to-file, a report to their supervisor, and a
letter home to their non-technically oriented parents. Again,
the goal is to provide students with the opportunity to
write about technical information in a variety of styles
for a variety of audiences.

In today's competitive world, solid communication skills
are increasingly essential for engineers. At the University of
North Dakota, an integrated laboratory sequence is used to
progressively develop these skills as well as the technical
skills required by undergraduate engineering students. By
systematically building on writing and speaking skills, the
labs provide students with a means for improving their com-

munication abilities.

1. Bakos, J.D., "A Departmental Policy for Developing Com-
munications Skills of Undergraduate Engineers," J. of Eng.
Ed., p. 101 (November 1986)
2. Kranzber, M., "Educating the Whole Engineer,"ASEE Prism,
P. 28 (Nov. 1993)
3. Canadian Accreditation Board, 1993 Annual Report, Cana-
dian Council of Professional Engineers (1993)
4. Ludlow, D.K., and K.H. Schulz, "Writing Across the Chemi-
cal Engineering Curriculum at the University of North Da-
kota," J. of Eng. Ed., 83(2), p. 161 (1994)
5. Aris, R. Chemical Engineering and The Liberal Arts Today,
The School of Chemical Engineering, Oklahoma State Uni-
versity, Stillwater, OK (1991)
6. Kreiger, J., "Push to Restructure Precollege Science Educa-
tion Gets More Emphasis," Chem. and Eng. News, 25(2), p.
7. Stevenson, S., "Integrating Complementary Studies in the
Engineering Curriculum: A Role for Communication Skills
Programs," 1994 ASEE Ann. Conf Proc., Edmonton, Alberta,
Canada, p. 2340 (1996)
8. Paradis, J., D. Dobrin, and R. Miller, "Writing at Exxon
ITD: Notes on the Writing Environment of an R&D Organi-
zation," in Writing in Nonacademic Settings, L. Odell and
D. Goswami, eds., Guilford Press, New York, NY, p. 281
9. Elbow, P., "Teaching Thinking by Teaching Writing," Phi
Delta Kappan, p. 37 (1983)
10. Van Orden, N., "Is Writing an Effective Way to Learn Chemi-
cal Concepts?" J. of Chem. Ed., 67(7), p. 583 (1990) C




Pablo G. Debenedetti

"This book is destined to take its place on
the shelf of every serious scientist or engineer
interested in the liquid state of matter. It will
undoubtedly become the defining 'bible' in its field,
for there is nothing comparable anywhere in the
world's literature."
-H. Eugene Stanley, Boston University

Metastable Liquids provides a comprehen-
sive treatment of the properties of liquids
under conditions where the stable state is a
vapor, a solid, or a liquid mixture of different
composition. It examines the fundamental
principles that govern the equilibrium proper-
ties, stability, relaxation mechanisms, and
relaxation rates of metastable liquids.
This is the definitive book on metastable
liquids. All mathematical symbols are defined
in the text and key equations are clearly
explained. More complex mathematical
explanations are available in the appendixes.
"[Pablo Debenedetti's] book is
remarkable because it offers the only
modern account of this vast field in a
manner so readable that one is hard
pressed to put it down. ... The reader
is treated to penetrating insights and
dramatically new information."
-Howard Reiss, University of California, Los Angeles
Physical Chemistry. Science and Engineering: John M. Prausntz and Leo Brewer, Editors
Cloth $69.50 ISBN 0-691-08595-1

~II1UhPrinceton Uivers'Uity Prs

Spring 1997

MR%^q laboratory



A Transient Fluidized-Bed Heat

Transfer Experiment

University of Dayton Dayton, OH 45469-0246

traditionally, steady-state performance of chemical
processing hardware is investigated in the unit opera-
tions laboratory, while transient behavior is reserved
for the process control laboratory. But given the importance
of dynamic behavior to the practice of chemical engineering,
more should be done to develop students' understanding of
transient process phenomena. The focus here is one of a
number of unit operations experiments that form a bridge
between the unit operations and process control laboratories.
These experiments give students the opportunity to develop
process-modeling skills and require the use of numerical
methods to solve the model equations.
Specifically, a transient fluidized-bed heat transfer experi-
ment is described that challenges students to demonstrate
their understanding of fluid flow, heat transfer, and process
dynamics as they apply to this particular unit operation.
Students performing this experiment have previously com-
pleted introductory fluid flow and heat transfer courses and
are concurrently taking courses in unit operations and pro-
cess control. Thus, they are well-prepared for the experi-
ment, and limited direct instruction is required. The students
are expected to search the literature for pertinent information
about fluidized beds and their operation, to formulate a math-
ematical model and experimental plan, and then to report their
results. This fluidized-bed experiment also has the additional
benefit of exposing students to particle technology, an area that
is often overlooked in chemical engineering curricula[1.21

The experiment is performed in a commercial fluidized-
bed experimental apparatus (P. A. Hilton Ltd. Fluidisation
and Fluid Bed Heat Transfer Unit H692; current price of
$14,136). The hardware is durable, having provided years of
reliable experimentation with limited maintenance require-
ments. Further, the small scale of the apparatus permits rapid
experimentation and simplification of the process heat trans-
fer model. Although it is not always desirable to eliminate

real-world complications in the unit operations laboratory,
in this instance it allows the students to focus on the primary
goal of developing their understanding of transient phenom-
ena in process operations.
A schematic of the experimental apparatus is shown in
Figure 1. The bed chamber is constructed of thick glass and
has an internal diameter of 0.105 m and a length of 0.220 m.
The bed solid is fused alumina particles with an average
particle size of 177 microns. The settled bed height is 0.067 m.
Air is used as the fluidizing medium, with the flow rate being
measured by either a rotameter or an orifice meter. The air is
introduced through a distributor that is designed to provide
both uniform air distribution over the column cross section and

Brian Priore received his MS in chemical engi-
neering from the University of Dayton, where he
conducted the first in-depth investigation of the
processing science of polymer composites via
Laminated Object Manufacturing (LOM). He is
currently enrolled in the doctoral chemical engi-
neering program at Carnegie Mellon University.

Shawn Whitacre received his MS in chemical
engineering from the University of Dayton, where
he conducted research on the effect of addi-
tives on the thermal degradation of jet fuels. He
is currently an engineer in the Chemistry, Fuels,
and Lubricants Group at Cummins Engine Com-
pany in Columbus, Indiana.

Kevin Myers is an associate professor in the
Department of Chemical and Materials Engineer-
ing at the University of Dayton. He received his
BChE degree from the University of Dayton and
his DSChE from Washington University in St.
Louis. His research interests are in multiphase
agitation and chemical reactors.
Copyright ChE Division ofASEE 1997
Chemical Engineering Education

support for the solid material in the non-fluidized state.
The bed can be heated with a resistance heater that is
cylindrical in shape, has a surface area of 0.0016 m2, and is
positioned horizontally in the bed. The rate of energy input
to the bed is controlled with a variable transformer and is
determined by measuring the voltage drop across and the
current flow through the heating element. Thermocouples
with digital indicators measure the heating element, air inlet,
and bed temperatures. An air-water manometer measures the
pressure drop across the bed. The experimental apparatus is
also equipped with safety devices to avoid dangerously high
pressures and temperatures.
The initial condition of the transient experiment is a fully
fluidized bed at room temperature. The transient experiment
is then initiated by turning on the heating element at the
desired power level (a step change stimulus). The bed tem-
perature is then recorded as a function of time until a new

Figure 1. Experimental apparatus schematic.

0.08 0.15

0.06 0
I Minimum
S0.04 Fluidization 0
m 0.05 V
0.02 .

0.00 0.00
0.00 0.05 0.10 0.15 0.20
Figure 2. Dependence of the bed height and pressure
drop on the superficial gas velocity at room temperature.
Spring 1997

steady state is approached as evidenced by a nearly constant
bed temperature. The goal of the experiment is to develop a
process model that can accurately predict the bed tempera-
ture as a function of time. Ricel31 has described a similar
transient heat transfer experiment in which steam is used to
heat a tank of water.


In addition to the transient experiment of interest here, a
number of steady-state experiments have been performed
with the apparatus. As described in detail by Fee,141 the
dependence of the bed height and pressure drop on superfi-
cial gas velocity can be used to determine the minimum
fluidization velocity. At superficial gas velocities below the
minimum fluidization velocity, the situation is that of gas
flow through a packed bed of solids. As illustrated by the
experimental data of Figure 2, the bed height is independent
of the superficial gas velocity in this regime, while the
pressure drop increases in an approximately linear manner
with increasing superficial gas velocity."5' At minimum flu-
idization conditions, the upward drag force exerted on the
solid particles by the flowing gas (as evidenced in the bed
pressure drop) is equal to the downward force of the weight
of the bed. Above the minimum fluidization velocity, the
bed height increases with increasing gas velocity, while the
bed pressure drop is relatively independent of gas velocity.
The data of Figure 2 indicates a minimum fluidization veloc-
ity of 0.115 m/s at room temperature. Since a hysteresis
effect has been observed,151 it should be noted that the data of
Figure 2 was taken as the superficial gas velocity was de-
creased from its maximum value (i.e., the bed went from the
fluidized to the packed state).
Figure 3 illustrates the dependence of the heat transfer
coefficient between the submerged heating element and the
bed on the superficial gas velocity (this data was obtained


2 300
I 200
I 100-



S :

0.00 0.05 0.10 0.15 0.20 0.25 0.30

0.35 0.40

Figure 3. Influence of superficial gas velocity on the heat
transfer coefficient between the submerged heating ele-
ment and the bed (based on steady-state experimentation).



using steady-state experimentation). The data indicates that
the heat transfer coefficient increases substantially upon flu-
idization and continually increases with increasing gas ve-
locity. The dramatic increase in the heat transfer coefficient
upon fluidization is due to the motion of the solid particles in
the fluidized state.151 Kunii and Levenspiel'61 note that a
maximum heat transfer coefficient in the fluidized state of-
ten occurs at an intermediate superficial gas velocity due
to large gas bubbles decreasing the particle-particle and
particle-heater interactions in the bed. But this behavior
is not seen in Figure 3, perhaps because the fluidizing
velocities are less than that which yields the maximum
heat transfer coefficient.


A mathematical model is often useful for understanding
process dynamics, and developing a process model is a
valuable learning experience for students. The following
assumptions are used in developing a model of transient heat
transfer from the submerged heating element to the fluidized
bed. The bed is treated as a pseudo-homogeneous phase that
has a single temperature at any point (as opposed to treating
the air and solid as distinct phases). This is a reasonable
assumption because the large exposed surface area of the
solids in a fluidized bed leads to rapid heat transfer between
the gas and solid."' Because of the rapid mixing that occurs
in the fluidized state, the bed is assumed to be well mixed, so
that the bed temperature is independent of position and is
described by a single value at any time.'7 Further, because of
the low thermal conductivity of the glass column, heat losses
to the surroundings are taken to be negligible.
A transient energy balance of the form

Rate of Energy

Rate of Energy

Rate of Energy

can be mathematically expressed for the bed as

mbCpb = Se rmCp(Tb Tai) (2)

The rate at which energy is added to the fluidized bed by the
submerged heater is S, while the second term on the right-
hand side of the equation represents the rate at which energy
leaves the bed by heating up the fluidizing air. Note that the
exiting air is assumed to have the same temperature as the
bed (an assumption of the process model). Separation and
integration of the model equation yields the following pre-
diction of the bed temperature response under the conditions
of the experiment (with the initial bed temperature and the
inlet air temperature being equal, Tbo = T,):

Tb = Tbo+ l
maCpa I

This exponential response is typical of a first-order system.

The predicted response of the model is compared to the
experimental response in Figure 4, and the conditions and
model parameters of the experiment are listed in Table 1.
Note that the model contains no adjustable parameters that
are used to fit its prediction to the experimental response.
The comparison indicates that the model does a reason-
able job of predicting the experimental response. The
model response at short times is more rapid than that of
the experiment, however, and the experimental response
is not that of a first-order system. Clearly, the process
model can be improved.

The difference between the model prediction and the ex-
perimental response indicates that energy does not enter the
fluidized bed as rapidly as expected. This can be explained
by the presence of a thermal capacity other than the bed that
absorbs some of the energy being added to the system. In
this instance, the second thermal capacity is the submerged
heating element itself (i.e., the original process model essen-
tially assumed that the heating element instantaneously

Model Parameters and Experimental Conditions

Bed mass (mb) 1.023 kg
Bed heat capacity (C p) 761 J/kg .C
Air mass flow rate ( ri) 0.00145 kg/s
Air heat capacity (Cp) 1050 J/kg .C
Initial bed temperature (Tb) 24C
Inlet air temperature (T,) 24C
Rate of electrical energy dissipation (S.) 36W




M 30 -
2 4


10- DATA

0 100 200 300 400 500 600 700 800

Figure 4. Comparison of the model prediction and the
experimental response to a step change in power input.
Chemical Engineering Education

I fmaCpa ^
* exp pa

reached its new steady-state temperature). The revised pro-
cess model consists of simultaneous energy balances for the
heating element as well as the fluidized bed.

meCpe = Se hA(Te -Tb) (4a)

mbpb dTb = hA(Te -Tb)- thaCpa(Tb Ta,) (4b)

The model now reflects that the electrical energy is dissi-
pated in, and accumulates in, the heating element and that
the rate of heat transfer between the element and the bed is
determined by a heat transfer coefficient. Note that the heat-
ing element has been treated in a lumped-parameter manner
(i.e., a single, uniform temperature is assumed). Again, the
revised model does not contain any adjustable parameters
because the heat transfer coefficient can be determined from
steady-state experiments (refer to the results of Figure 3).
The additional model parameters required by the revised
process model are listed in Table 2.
The coupled model equations can be solved simultaneously
to yield the heating element and bed temperatures as func-
tions of time. Solution of the model equations is readily
accomplished numerically, providing students with a good
opportunity to apply their mathematical and computational
skills. A fourth-order Runge-Kutta technique was used in

Additional Parameters of the Revised Model

Element mass (m,) 0.0412 kg
Element heat capacity (Cp,) 385 J/kg .C
Heat transfer coefficient (h) 173 W/m' .C
Heating element area (A) 0.0016 m2

60 --200

s -150 -
u 40 c

1 250
0 Te
0 '--,--,- 0
0 100 200 300 400 500 600 700 800

Figure 5. Comparison of the revised model prediction
and the experimental response to a step change in power
input (model predictions are shown as curves).
Spring 1997

this instance. The initial conditions for the experiment re-
ported here are that both the bed and heating element are
initially at the ambient temperature. The resulting predic-
tions are compared to the experimental responses in Figure 5
(note that the bed and heating element temperatures are
presented on separate axes). The model prediction now very
accurately describes the experimentally observed bed tem-
perature. The model prediction of the heating element tem-
perature is less accurate, but reasonable.

The transient fluidized-bed experiment outlined here has
been useful in providing students with an opportunity to
study transient process phenomena in the unit operations
laboratory. Because the transient experiment can be per-
formed rapidly, students can do it after they have completed
study of the steady-state behavior of the fluidized bed. The
modeling and associated numerical solution of the govern-
ing model equations are additional features associated with
performing transient experiments in the unit operations

A Area of the heating element
C Constant pressure heat capacity (J/kg .C)
h Heating element to bed heat-transfer coefficient
(W/m' "'C)
m Mass (kg)
rh Mass flow rate (kg/s)
S Rate of electrical energy dissipation (W)
T Temperature ('C)
t Time (s)
a refers to the fluidizing air
b refers to the bed
e refers to the heating element
i refers to inlet or feed conditions
o refers to initial conditions

1. Nelson, R.D., R. Davies, and K. Jacob, "Teach 'Em Particle
Technology," Chem. Eng. Ed. 29(1), 12 (1995)
2. Tardos, G.I., "Development of a Powder Technology Option
at CCNY," Chem. Eng. Ed., 29(3), 172 (1995)
3. Rice, P., "Unsteady-State Heat Transfer from a Steam-
Heated Coil to a Tank of Water," Chem. Eng. Ed., 29(2), 116
4. Fee, C.J., "A Simple but Effective Fluidized-Bed Experi-
ment," Chem. Eng. Ed., 28(3), 214 (1994)
5. McCabe, W.L., J.C. Smith, and P. Harriott, Unit Operations
of Chemical Engineering, 4th ed., McGraw-Hill, New York,
NY (1985)
6. Kunii, D., and 0. Levenspiel, Fluidization Engineering, 2nd
ed., Butterworth-Heinemann, Boston, MA (1991)
7. Botterill, J.S.M., Fluid-Bed Heat Transfer, Academic Press,
London, UK (1973) J

r1 laboratory


Affinity Adsorption

Universidad de Sonora Hermosillo, Sonora, Mexico

Bioseparation processes have long been regarded as
the critical factor in the commercial development of
biotechnology. Chemical engineering operations have
been widely used to obtain bioproducts, but there are some
new separation techniques that enhance these operations
that need to be included in chemical engineering courses.
Among these techniques, affinity adsorption is of par-
ticular interest. Highly valuable proteins such as enzymes,
hormones, antibodies, and interferons are obtained
through the use of this technique.

Armando Tejeda is a member of the research staff of the Centro de
Investigaciones Cientificas y Tecnologicas at the University of Sonora.
He has taught bioseparations in the University's biotechnology program
for more than six years. His research is concerned with design and
optimization of large-scale bioseparations.
Juan A. Noriega received his BS in chemical engineering in 1989 and his
Diploma in biotechnology in 1995 from the University of Sonora. He is a
faculty member of the Chemical Engineering and Metallurgy Department
at the University of Sonora. His major research interest is mass transfer
operations applied to bioprocesses.
Arturo Ruiz has been on the Chemical Engineering and Metallurgy
Department faculty at the University of Sonora since 1975, where he has
served as Department Head and holds responsibility for the biotechnol-
ogy program. His principal academic interests are in bioprocessing engi-
neering and environmental biotechnology.
Rosa M. Montesinos received her BS in physics from the National
University of Mexico. She is a faculty member of the Mathematics Depart-
ment at the University of Sonora. Her major research interest is in protein
purification methods.
Haydee Yeomans is a chemist with graduate studies in food technology
and has been on the Chemical Engineering Department faculty at the
University of Sonora since 1978. Her principal research interest is in
environmental biotechnology.
Roberto Guzmdn received his BS in chemical engineering from the
University of Guanajuato, his MS from Illinois University, and his PhD
from North Carolina State University. He is a faculty member of the
Chemical and Environmental Engineering Department at the University of
Arizona. His research is concerned with bioprocesses development and

SUniversity ofArizona, Tucson, AZ 85721

We have developed some basic experiments that permit
the demonstration of affinity adsorption techniques to chemi-
cal engineering undergraduate students. In our experience,
this material is suitable for inclusion in a required senior-
level unit operations course since most undergraduates have
little exposure to adsorption in general and probably no
exposure to protein separations methods in particular.
In the experiments, a dye-ligand affinity adsorbent is used
because it is didactic and has management advantages. Dye
affinity adsorption is widely recommended and used for
large-scale protein purification because dye-ligand adsorbents
are cheap, stable, and versatile. "21
Affinity adsorption processes can be used in the concen-
tration of a desired product from a diluted solution or to
separate a mixture of solutes using column chromatographic
techniques.' In some cases, it may be suitable to perform
affinity adsorption in a batch-stirred tank.
Much of the information needed to evaluate column per-
formance is contained in typical plots of effluent concentra-
tion versus time or breakthrough curve. This curve can be
used to determine 1) how much of the column capacity has
been used, 2) how much solute is lost in the effluent, and 3)
the processing time. This is precisely the performance infor-
mation needed to optimize processing.16' Concentration pro-
files for batch systems can be used in an analogous way.
In affinity adsorption systems after the adsorption step,
non-adsorbed material is washed off with equilibrium buffer,
and adsorbed compounds are then eluted.[41 Recovery is
usually effected by changing the pH, ion strength, or chemi-
cal composition of the buffer.151
To predict the performance of affinity adsorption systems,
theory and experiments must be combined. This article de-

Copyright ChE Division ofASEE 1997

Chemical Engineering Education

We have developed some basic experiments that permit the demonstration of affinity
adsorption techniques to chemical engineering undergraduate students. In our experience, this
material is suitable for inclusion in a required senior-level unit operations course.

scribes batch and fixed-bed experiments to demonstrate this
predictive approach to undergraduate students.


The interaction of proteins with immobilized dyes varies
and, for the most part, is not well understood. To describe
these complex interactions, a simplified model is often used."71
The model is the second-order reversible interaction where
the protein (P) is assumed to interact with the ligand (D) by a
monovalent interaction that has a characteristic binding en-
ergy, forming the dye-protein complex (PD) as
P+D < P- D (1)
The adsorption rate for this type of interaction is given by

dq = kc(q, -q)-k_ q (2)
c = protein concentration in the liquid. ML-3
q = protein concentration in the adsorbent, ML-
qm = maximum adsorption capacity of the adsorbent, ML-'
k, = forward kinetic constant. M-'L-3t-
k = reverse kinetic constant, t'
t = time, t

The kinetics constants k, and k., are lumped parameters
that reflect the contributions of mass transport and binding
kinetics as well. At equilibrium, Eq. (2) reduces to the famil-
iar Langmuir isotherm model

q* = qc* (3)
Kd +c*
where denotes equilibrium concentrations and Kd = k -/k,
is the dissociation constant.

We will use an expression for the protein uptake by affin-
ity adsorbent in a well-stirred tank initially filled with a
protein solution at an initial concentration co. The total vol-
ume of the system is V and the liquid volume is eV, where e
is the batch void fraction. Then the adsorbent volume is
(1- )v. Protein concentration in solution at time t is given
Spring 1997

c= c


a- [ Cb2 m ]q
(1 -F) M

1F Co KdE
and b = +I [ + qm+
2 (1-e) (1 (-e)

and qs is the maximum adsorbent capacity referred to the
settled volume of adsorbent.

The model used to describe fixed-bed affinity adsorption
is based on isothermal sorption of a single solute in plug
flow through a packed bed of uniform spherical particles
having a radius r,, which has a uniform cross-sectional area
A of length L and a void fraction e. Liquid flows through the
bed at a superficial velocity of u, and the column is initially
devoid of solute. At time zero the inlet concentration of
solute in the mobile phase to the column is changed to co.
It has been shownl6" that when axial dispersion is negli-
gible, column mass balance can be expressed as
E- =- c (1- E (5)
at az at
The analytic solution to Eqs. (2) and (5) was first obtained
by Thomas[91 and can be expressed asl0o]

( n I
X(t,L)= r r nF (6)
n nF I
J r ,n n, expKi1- 1j(n- nF)]


x(t.L) = c

r=l+ c
n = q k L-
Kd +cj ( Ft
Asm AL- )

and J is a two-parameter function of a and p given

J(,p)= 1 -e-P e- 10o(2,FP) di (11)
where Io refers to a zero-order modified Bessel function
of the first kind. According to Thomas, when the prod-
uct of a and p is greater than 36, J(a, P) can be calcu-
lated within 1% accuracy by

exp[- A )2
J(a, )= 1-erf( x -V)+ ---. (12)

Resolution is a measure of the attained separation of
two solutes. The resolution of two solute peaks Rs is
defined as the distance between the peaks divided by
the sum of their average width.

R 2(tB tA (13)
(WA +WB)
tA,tB = retention times of components A and B (min)
WA,WB = widths of peaks A and B (min)


To conduct the experimental procedures, the adsor-
bent used was DyeMatrex'" Blue-A (Cibacron Blue
F3GA covalently attached to cross-linked 6% agarose)
with a particle diameter between 50 to 150 um pur-
chased from Amicon. Bovine serum albumin (BSA)
and lysozyme were the proteins used for adsorption
and selectivity experiments, and for void volume deter-
minations, Blue Dextran was employed. These chemi-
cals are available from Sigma and Pharmacia.
All solutions were buffered with 20 mM of sodium
phosphate, pH 7. Known volumes of adsorbent were
previously prepared by a laboratory assistant by allow-
ing a suspension of adsorbent in 0.5 M of sodium
chloride in 20 mM sodium phosphate buffer to settle in
a measuring cylinder overnight. A 50:50 (v/v) suspen-
sion was then prepared by adjusting the liquid volume
to equal that of the settled adsorbent. Air bubbles were

removed from the slurry by applying vacuum for ten minutes. Before
use, the adsorbent was washed with 20 mM sodium phosphate ad-
sorption buffer.
Protein concentration was estimated by absorbance at 280 nm.
Extinction coefficient of 0.56 AU-ml/mg for albumin and 2.16 AU-
ml/mg for lysozyme, determined previously by a calibration curve,
were given to students. All the experiments were run at room
temperature (25 C).

The students conducted adsorption equilibrium experiments in the
stirred-batch system shown schematically in Figure 1. A typical

Figure 1. Apparatus for batch stirred tank experiments: (1) batch
adsorption vessel; (2) stirred magnetic plate; (3) UV monitor; (4)
chart recorder; (5) peristaltic pump; (6) speed control.

Figure 2. (A) Adsorbent preparation; (B) Column packing; (C)
Experimental arrangement for column experiments. (1) measure-
ment cylinder; (2) column (3) peristaltic pump; (4) vessel; (5)
starting buffer or feed vessel; (6) final buffer vessel; (7) sample
application; (8) UV monitor; (9) fractions collector; (10) chart
Chemical Engineering Education

5 6



B heo- I

experiment consisted of the addition of 2 ml of a 50:50 (v/v) suspen-
sion of the adsorbent to 25 ml of buffer in the adsorption vessel. The
experiment was conducted by step-wise addition of pulses of a 10 mg/
ml BSA solution to the adsorption vessel. At time zero, a 100 ul pulse
was added to the batch adsorber. Soluble phase protein concentration
was continuously monitored by recycling the liquid phase through a
20 pm porosity net filter adapted to the tubing and through a continu-
ous flow BioRad UV spectrophotometer, using a flow-rate of 1 ml/
min. The adsorption was carried out until no appreciable change was
observed in the chart recorder connected to the spectrophotometer;
this reading was taken as an equilibrium point. Successive pulses
were added to the same system to obtain higher equilibrium points
until adsorbent saturation was reached. The amount of protein adsorbed
at each point was then calculated by mass balances. These values
were used to obtain the adsorption isotherm for the system.

The students did batch experiments in the same experimental ar-
rangements (Figure 1). Initially, 25 ml of BSA solution at known
concentration (e.g., 0.5 mg/ml) was placed in the well-stirred reactor
(50 ml volume). At time zero, 2 ml of a 50:50 (v/v) adsorbent
suspension was added to the reactor. Protein concentration was con-
tinuously monitored with the spectrophotometer using a recycle flow
of 6 ml/min. The adsorption was carried out until no appreciable
change was observed.

Fixed-bed experiments were carried out in a BioRad Chromato-
graphic Econosystem, shown schematically in Figure 2. The adsor-
bent was measured (Figure 2A) as described above, and then students
packed the column (Figure 2B). The breakthrough curve for the
system was determined by continuously loading protein to the packed

q 10

bed until the protein outlet concentration was equal to
protein inlet concentration, co.
Fixed-bed experiments were performed with 2 ml
(settled volume) of adsorbent packed in a chro-
matographic column having a diameter of 10 mm.
Inlet protein solution with a concentration of 1 mg/ml
(co) was applied using a volumetric flow-rate of
0.3 ml/min. The optical density at 280 nm of the
outlet stream was continuously recorded (Figure 2C).
Data were plotted in the form of normalized con-
centration, c/co, of the outlet stream against the
time of operation. Time zero was taken as the
point at which the adsorbate solution first entered
the bed. The void volume of the bed was estimated
by a pulse of Blue Dextran.

The experimental arrangement shown in Figure 2
was also used by the students in the selectivity experi-
ment. To measure the column selectivity, a 100 gl
pulse of a 4.0 mg/ml albumin and a 1.5 mg/ml of
lysozyme solution was applied to the column and
then eluted using a linear gradient 0.0-2.0 M NaCI
(240 min) in 20mM sodium phosphate buffer. A flow
of 0.3 ml/min was maintained throughout. The ex-
periment was performed using an automatic gradient
formed program.

Computer programs were developed by students to
simulate batch concentration profiles and the break-
through curve. All computer programs were run using
MathCad version 4.0 in a personal computer.



Equilibrium points were derived from the protein
concentration attained at each adsorption step and the
corresponding mass balances. With the calculated val-
ues, the isotherm for the system shown in Figure 3 is
obtained. Equilibrium data were fitted to the
Langmuir model (Eq. 3) by nonlinear least-squares
regression analysis to obtain the maximum adsorp-
tion capacity qm = 15.6 mg of BSA/ml of adsorbent
settled volume and the dissociation constant Kd =
0.25 mg/ml. The solid lines in Figure 3 represent
the Langmuir isotherm, which best fits the data. In
general, the model fits the data well. These results
are well reproduced by students when they mea-
sure solution pulses in a proper form.

I c (mg/ml)
Figure 3. Adsorption isotherm for bovine serum albumin (BSA)
adsorption to Cibacron Blue adsorbent: D Experimental points;
- best-fit to Langmuir model.
Spring 1997

Batch kinetic experimental results obtained by instructors
are shown in Figure 4. The experimental data (small squares)
were fitted by the proposed model (Eq. 4) using Kd and q.
values from equilibrium experiments and a k, value of 0.0038
ml/mg-s that best fit the kinetic data. The solid line is the
best fit to the model. The same approach is used by students
for experimental data treatment. The experiment has a high
degree of reproducibility.

A breakthrough curve obtained by instructors for fixed-
bed adsorption of BSA is shown in Figure 5. The continuous
line in the figure was obtained by fitting the experimental
data to the kinetic model in Eq. (6). A value of 0.0009 ml/
mg-s for the lumped forward rate constant k, was estimated
by the best fit to the early part of the curve (that of most
interest) using a Kd value of 0.25 mg/ml and the q,,, of 15.6
mg/ml as determined in batch uptake experiments. A void
bed volume of 0.42 as determined with Blue Dextran was
used in these simulations. For student's data treatment, the
void bed value is provided by instructors. In order to get a
good reproducibility of these results by students, special
attention must be taken in column packing.
In general, good agreement was observed between theory
and experiments, particularly in the early part of the curve.
Systematic discrepancies were found in the latter stage of
the breakthrough curves, however, where experimental data
trail behind the model. These results indicate that the adsorp-
tion rate was slower at this latter stage than it was at the
beginning of the breakthrough. If a more detailed descrip-
tion of the phenomena is needed, a more sophisticated model
should be employed.
It has been pointed out that the kinetic model works better
for situations where mass transfer effects are small.[71 This
may explain why fit in batch is better than in fixed-bed
experiments. For this reason, no attempt was made to
predict the kinetic forward rate constant k, from the batch

Figure 6 shows selectivity experimental results obtained
by instructors. The retention time for BSA is about 70 min
and for lysozyme is 180 min. Under the experimental condi-
tions employed, lysozyme binding to the adsorbent is stron-
ger than BSA binding. Both peaks are well developed and
about the same size because the difference in the extinction
coefficients is well compensated by sample concentration.
The experimental resolution obtained in this separation is
about 1.87. Correct column packing and sample application
allow students to develop these same concentration profiles.


500 1000 1500 2000 2500

Figure 4. Bovine serum albumin (BSA) batch adsorption
kinetics on Cibacron Blue-ligand adsorbent: L Experimen-
tal points; Best-fit to batch model.


Figure 5. Fixed-bed breakthrough curve for bovine serum
albumin adsorption to Cibacron Blue-ligand adsorbent: D
Experimental points; -Best-fit to kinetic model.

Chemical Engineering Education


These experiments are of great educational interest be-
cause they allow the study of affinity adsorption, a novel
concept for chemical engineers. A major advantage of these
experiments is the simplicity of the laboratory procedures.
The continuous protein concentration monitoring in the ex-
perimental systems offers several advantages, permits stu-
dents to focus on the experiment rather than in taking samples,
and requires less supervision.
Small-scale experiments are easier to conduct. Less time
and fewer materials are used than in some of the pilot-scale
experiments commonly used in traditional chemical engi-
neering laboratories. Small-scale experiments also permit
the student to focus on fundamentals rather than on routine
The experiments can be integrated in three modules: (1)
equilibrium and batch experiments; (2) fixed-bed experi-
ments; (3) selectivity experiments. Initial preparation for
each module requires less than thirty minutes for the stu-
dents or laboratory assistant. The experimental measure-
ments for each of the first two modules can be made in
approximately three hours; the third module requires about
four hours. These experimental modules may be conducted
simultaneously if sufficient equipment is available.
The general nature of the experiments should also be
emphasized. The procedures here described can be employed
with other types of adsorbent-protein systems as well as to
work out various situations of interest under different condi-
tions: sample concentration, sample volume, gradient, col-
umn length, buffer flow rate, and type of elution buffer.
To evaluate experimental achievements, students are re-

60 2.0

280 n1.0 NaCI
280 nm A

0 I1 I 0
0 50 100 150 200 250
I (min)

Figure 6. Elution pattern for lysozyme and albumin
mixture on Cibacron-Blue adsorbent column using a
linear gradient 0.0 2.0 M NaCI (240 min). A flow rate of
0.3 ml/min was maintained throughout. (A) albumin, (L)
Spring 1997

quired to submit a report with their experimental results. The
report must include a parametric analysis, done with the
fixed-bed experimental model, on the influence flow rate
and inlet concentration have on column operation capacity.
We highly recommend using one of the simulated runs to
validate the experimental model.


The BSA-dye adsorbent experimental system allows one
to demonstrate affinity adsorption techniques. By combining
a simple kinetic model with experimental results, some of
the key factors that affect affinity adsorption systems are
better grasped by the students. Through this approach, the
interrelation between equilibrium and kinetic data-and how
to integrate theory and experimental results to predict sys-
tems performance-can be emphasized. Very complex phe-
nomena can be demonstrated using a simple and low-cost
system that permits the development of textbook-type graph-


This work has been supported by the Universidad de Sonora
and the Consejo Nacional de Ciencia y Technologia
(CONACyT: 2046-A9302).

1. Vijayalakshmi, M.A., "Pseudobiospecific Ligand Affinity
Chromatography," Trends Biotechnol., 7, 71 (1989)
2. Scopes, R.K., "Strategies for Enzyme Isolation Using Dye-
Ligand and Related Adsorbents," J. Chromatogr., 376, 131
3. Yarmush, M.L., and C.K. Colton,, "Affinity Chromatogra-
phy," in Comprehensive Biotechnology, M.Y. Murray, Ed.,
Pergamon Press, New York, NY, (1985)
4. Clonis, Y.D., "Large-Scale Affinity," Bio / Technology, 5, 1290
5. Gibbs, S.J., and E.N. Lightfoot, "Scaling Up Gradient Elu-
tion Chromatography," Ind. Chem. Fund., 25, 490 (1986)
6. Arnold, F.H., H.W. Blanch, and C.R. Wilke, "Analysis of
Affinity Separations. I: Predicting the Performance of Affin-
ity Adsorbers. II: The Characterization of Affinity Columns
by Pulse Techniques," The Chem. Eng. J., 30, B9 (1985)
7. Boyer, P.M., and J.T. Hsu, "Effects of Ligand Concentration
on Protein Adsorption in Dye-Ligand Adsorbent," Chem.
Eng. Sci., 47, 1, 241 (1992)
8. Skidmore, G.L., B.J. Horstmann, and H.A. Chase, "Model-
ing Single-Component Protein Adsorption to the Cation Ex-
changer Sepharose FF," J. Chromatogr., 498, 113 (1990)
9. Thomas, H.C., "Heterogeneous Ion-Exchange in a Flowing
System," J. Am. Chem. Soc., 66, 1664 (1944)
10. Arnold, F.H., and H.W. Blanch, "Analytical Affinity Chro-
matography. Part II: Rate Theory and the Measurement of
Biological Binding Kinetics," J. Chromatogr., 355, 13 (1986)
11. Hiester, N.K., and T. Vermeulen, "Saturation Performance
of Ion-Exchange and Adsorption Columns," Chem. Eng. Prog.,
48,505(1952) O

" laboratory




University of New Brunswick Fredericton, New Brunswick, Canada E3B 5A3

Industrial experience has always been considered an im-
portant part of the engineering curriculum at the Univer-
sity of New Brunswick. There are, however, limited
facilities for students to obtain industrial experience. As a
result, the university continually explores ways of providing
the necessary exposure. The Department of Chemical Engi-
neering has developed the following activities to achieve
this end:
First Year Factory Tours
Second Year Boiler Test
Third Year Practice School
Fourth Year Plant Design
All of these activities form a part or the whole of required
courses within the chemical engineering program, and aca-
demic credit is earned for the work. There is also a provision
for students to obtain academic credit for summer research
projects or work terms in industry, but since this is optional,
it is not considered in this paper.
The main emphasis in this paper is on the boiler test,
which I have directed on a number of occasions and have
modified from time to time. I believe that it now provides
good exposure to an industrial operation and that students
learn a great deal from it. Most of all, they seem to enjoy it.

An effort has been made to introduce chemical engineer-

Robin Chaplin, after some fifteen years of indus-
trial experience, returned to university, obtained a
PhD from Queen's University in 1986, and took
the position as Chair in Power Plant Engineering
at the University New Brunswick. He teaches
thermodynamics and fluid mechanics, as well as
specialized courses in nuclear and conventional
powerplants. At various times he has supervised
I the laboratory course referred to in this paper.

Copyright ChE Division ofASEE 1997

ing students to chemical engineering practice in their first
year in the engineering program. The concept of factory
tours was to stimulate interest in chemical engineering dur-
ing the students' first year of study. The visits are carried out
within the regular program and, as a follow-up exercise,
students write an essay on the particular industry they vis-
ited. The essay also serves to assess the students' compe-
tency in English writing early in the program.

Introduction There is a heating plant that supplies heat-
ing steam to both the University of New Brunswick campus
and the regional hospital. The heating plant, shown in Figure
1, has one wood-chip-burning boiler and two fuel-oil-fired
boilers capable of generating 40,000 lb/hr (5 kg/s) and
120,000 lb/hr (15 kg/s) of steam each, respectively. Satu-
rated steam for space heating is supplied at a pressure slightly
above 200 lbf/in2 (1.3 MPa), and the condensate is returned
for preheating and feeding back into the boiler.
When I first became involved with the second-year chemi-
cal engineering laboratory course, I found that the boiler was
treated as some kind of reactor on which a mass balance was
carried out. Since redundant data were obtained, there was
confusion as to how to close the mass balance. Due to errors
in measurement, the mass balance never closed, leaving the
students frustrated and confused since they did not yet have
the depth of knowledge to sort out the conflicting results.
Since then, I have made two changes: the first was to provide
better direction on what was to be achieved, and the second
was to ensure the students had adequate theoretical back-
ground to assess the results. The test is now done in accordance
with the ASME Power Test Code for Steam Generating Units,1'
and the objective is to determine the boiler efficiency.
Course Structure The second-year laboratory course
runs for twelve weeks and comprises the boiler test (40%),
fluid mechanics (40%), and industrial safety (20%). This
Chemical Engineering Education

breakdown is for assessment and grading purposes, but some-
what more laboratory time (about 50%) is actually spent on
the boiler test. The fluid mechanics portion of the course
encompasses execution of laboratory experiments and writ-
ing up laboratory reports. In this part of the course, students
spend more of their own time writing up laboratory re-
ports-hence the lesser amount of scheduled laboratory time.
The industrial safety portion of the course includes lectures
by industrial safety and fire protection officers from outside
the university. The final examination in the course is biased
towards safety aspects.
The boiler test itself occupies four lectures and seven
laboratory sessions:

Lecture 1
Lecture 2
Lecture 3
Lecture 4
Laboratory 1
Laboratory 2
Laboratory 3
Laboratory 4
Laboratory 5
Laboratory 6
Laboratory 7

Course structure and requirements
Boiler configuration and efficiency
Boiler test equipment and procedures
Boiler test report and presentation
Thermodynamics tutorial
Heating plant tour
Test equipment check (two experiments)
Test equipment check (two experiments)
Boiler test at heating plant
Presentation of results
Mid-term test

There is one lecture and one laboratory session each week.
The purpose of the lectures is to give direction to the whole
class and to explain general principles applicable to the
equipment to be used and procedures to be followed. The
whole process may be explained by following the activities
in the laboratory sessions and noting that the lectures simply
provide a support function. Normally there are between 30
and 36 students in the class. The class meets as a whole for
the lectures and divides into two teams of half that size for
the laboratory sessions on different days.
Boiler Efficiency The objective of the boiler test is to

Spring 1997

determine the efficiency of one of the fuel-oil-fired boilers,
using the appropriate ASME Power Test Code. The effi-
ciency is determined by the Input-Output Method and by the
Heat-Loss Method. This requires measurement of the fol-
lowing parameters:
Steam flow rate (direct reading)
Steam quality (throttling calorimeter)
Steam pressure (direct reading)
Feedwater pressure (direct reading)
Feedwater temperature (direct reading)
Fuel-oil flow rate (direct reading)
Fuel-oil calorific value (bomb calorimeter)
Ambient air pressure (mercury barometer)
Ambient air temperature (sling psychrometer)
Ambient air humidity (sling psychrometer)
Inlet air flow rate (Pitot tube traverse)
Exhaust gas analysis (Orsat apparatus)
Exhaust gas CO, (electronic probe)
Exhaust gas temperature (electronic probe)
Boiler wall temperature thermocouplee traverse)
Where direct readings are indicated, they are taken from
existing instrumentation. Other readings are obtained from
laboratory equipment or equipment temporarily installed for
the boiler test.
In addition, operating conditions are monitored in case
transients occur or there are losses from the system such as
blowdown of boiler water. Corrections also have to be made
to the direct readings to account for operation away from
design conditions, e.g., the effect of steam pressure on the
steam flow calibration.
The efficiency by the Input-Output Method is
S= MsteamAh / MfuelCVfuel
and the efficiency by the Heat-Loss Method is
S= (MfuelCVfuel Losses) / MfueCVfuel
Mstcam = mass flow rate of steam
M fuel = mass flow rate of fuel
CVfuel = calorific value of fuel
Ah = enthalpy difference between steam and feedwater
Losses = heat loss in exhaust gas plus heat loss from boiler walls
The various steps in executing the whole process are de-
scribed below.
Thermodynamics Tutorial Students coming into the
laboratory course have normally completed the first course
in engineering thermodynamics. This course covers power
cycles, steam systems, boiler efficiency, and combustion
calculations, along with the basic concepts of heat and en-
ergy. In the thermodynamics tutorial, this knowledge is rein-
forced by having the students find the answers to problems
such as:
SThe power required to drive a feedwater pump given inlet and

outlet conditions and flow
The quality of steam in a steam line given data from a
throttling calorimeter
The efficiency of a boiler by the Input-Output Method, given
steam and feedwater conditions and flow as well as fuel
calorific value and flow
The air-fuel ratio required for the combustion of a simple
hydrocarbon fuel with specified excess air
The air-fuel ratio for a simple hydrocarbon fuel given
volumetric analysis of flue gas from an Orsat apparatus
The efficiency of a boiler by the Heat-Loss Method given gas
conditions and flow as well as fuel calorific value and flow
The problems demonstrate the basic calculations required
to determine boiler efficiency and to give some meaning to
subsequent work.
Heating Plant Tour The next phase is a tour of the
heating plant, conducted by the plant supervisor. Data re-
lated to the boilers and their operation are presented and the
students subsequently have access to the plant and operators
to fill in missing information. Before leaving the plant, they
have to submit a layout diagram of the plant, a listing of
technical data, and a written description of the plant and its
operation. A minimum of direction is given to allow for
individuality and initiative.
Test Equipment Check This section occupies two labo-
ratory sessions and requires the execution of four simple
experiments (two each session) on the following pieces of
laboratory equipment: the airflow rig, the bomb calorimeter,
the heat-loss rig, and the Orsat apparatus.
The students are divided into four groups of about four
students each. The groups rotate so that all students work on
all pieces of equipment that will be used in carrying out the
actual boiler test. The experiments are relatively simple since
the main purpose is to allow the students to become familiar
with the apparatus and to get hands-on experience. The work
done of each piece of equipment is shown below.
Air-Flow Rig Measurement of air flow emerging from a
duct by doing a Pitot tube traverse Measurement of
humidity using a sling psychrometer Measurement of
atmospheric pressure on a mercury barometer
Bomb Calorimeter Standardization of the calorimeter using
benzoic acid pellets or the determination of the calorific
value of a fuel oil
Heat-Loss Rig Measurement of temperature at various points
on a non-uniformly heated steel plate using a thermo-
couple probe Determination of heat loss from the plate
OrsatApparatus. Determination of the oxygen content of
the air in the laboratory Determination of the composi-
tion of a simulated flue gas
At this stage in their program, the students generally have
not had exposure to the theory that supports these experi-
ments. Most are just starting fluid mechanics and none have
had heat transfer. The required background is therefore given

in the laboratory manual-this is a good demonstration that
useful work can be done by reference to appropriate material.
Boiler Test at Heating Plant For the real test, the
groups are slightly restructured from the original four groups
to create five groups of about three students each. This is
done by pulling out selected students who are judged to be
able to adapt to the transition-usually the most senior in the
class. Each of these new groups is then responsible for
heating-plant measurements of 1) steam and fuel flow (new
group), 2) combustion air flow, 3) fuel oil characteristics, 4)
boiler heat losses, and 5) stack gas analysis.
The additional group (#1) must take measurements from
the existing plant instrumentation as well as from a tempo-
rarily installed steam calorimeter. This is an area where the
theoretical background has been covered and if the group
has been well constituted, the students in that group come
together easily. Their measurements are critical to the suc-
cess of the whole exercise since the steam and fuel flows are
key parameters. The other groups are by this time familiar
with the equipment they are using and each group simply
repeats one of the previous experiments, only on a larger or
more rigorous scale.
The test is conducted over a period of two hours, with
steam and fuel flows being read every 15 minutes and other
measurements less frequently, depending on the constraints
of the equipment.
Presentation of Results A week later, the team as a
whole has to present its results, with each group giving its
analysis and each student giving his or her contribution. To
do this, there must be some interchange of information and
cooperative work between groups. Naturally, this does not
always happen (some groups or individuals work in isola-
tion), but it is a demonstration of the need to work as a team.
For the presentation, each student is required to prepare
some overhead projector slides and to explain part of the
proceedings. Each student is graded as follows:
Attendance 1
Overheads (visual impact) 3
Presentation (verbal logic) 3
Technical Content 3
The attendance mark is simply a bonus mark so that the
others can be marked on a simple scale: 1, satisfactory; 2,
good; 3, excellent.
Questions from the other groups and discussion between
the groups is encouraged after each group's presentation. It
also provides an opportunity for the laboratory supervisors
to clarify misconceptions or explain deficiencies.
The presentation of results is followed up by a joint report
from the team as a whole, with each group contributing one
section of the report. The objective is to produce a single
formal report in a consistent format where the efficiency of
Chemical Engineering Education

the boiler is calculated and presented. This is, in theory, an
excellent exercise since it demonstrates what is required in
industry. In practice, however, it falls short because not all
students make an equal contribution and it is difficult to
justify giving lower marks to those suspected of not do-
ing their fair share.
Mid-Term Test A mid-term test concludes this part of
the course. Since the various groups have worked on differ-
ent aspects of the boiler test, it is desirable to examine the
students on their overall knowledge of boiler plant testing.
As far as possible, the questions are directed toward the
knowledge and experience that should have been gained by
the exercises rather than factual information given in the
laboratory manuals. The test includes both simple calcula-
tions and descriptive answers. Generally, the results in the
most recent test appeared to be a fair reflection of the knowl-
edge and ability of the students.
One aspect worth noting is that all work (except the formal
report on the boiler test) has to have been done in laboratory
books. The mid-term test is also done in the laboratory
books-no supplementary references are permitted. It is,
therefore, advantageous for the students to have well-docu-
mented records to refer to during the mid-term test. Another
fact of interest is that, with separate teams on different days,
separate and different mid-term tests have to be set. This
challenges the instructor, who knows that even if the ques-
tion sheets are collected after the first exam, there will be
consultation between teams before the second exam.
Make-Up Assignments Should a student miss a labora-
tory session for some valid reason, various makeup assign-
ments are available. He or she is required to spend a period
in the heating plant tracing out the pipelines of a selected
system, such as the feedwater system or the oil system, and
to develop a flow diagram for that system. The flow diagram
must show all valves and fittings and instrumentation points
so that it is evident how the system works. This work is self-
paced, with no supervision-but the end result clearly shows
the effort put into the exercise.
Conclusion The boiler test provides students with expo-
sure to the industrial world. They have the opportunity of
working in an industrial setting, of talking to plant operators,
and of generally finding out what industrial engineering is
like. They are encouraged to spend as much time at the plant
as they can afford and to make follow-up visits to learn more
about the plant or to find missing data.
This part of the course demonstrates the need for funda-
mental theory and shows the practical application of the
basic sciences. One student commented, "Some concepts
were hard to grasp, but now that I have seen them ap-
plied, the material makes sense." It also shows the prob-
lems that can arise in practical engineering: "I felt that
the experiments where I learned the most were the ones
that went totally wrong."
Spring 1997

Generally, comments from the students regarding the boiler
test are good. The harder they have to work and the more
effort they put into it, the more satisfaction they derive from
it. Of course, the professor must ensure that the demands are
not excessive and that the grading is done fairly so they are
rewarded for their efforts.

Practice School projects are conducted in industry by small
groups of students. They take place over a two-week period
in the spring, immediately after the final examinations. Each
project is jointly supervised by a faculty member and an
industrial engineer, and the students subsequently have to
produce a report and give a formal presentation. It is part
of the regular program and students obtain academic
credit for it. Coordination is not easy, but each year the
instructor'12 manages to match most students with the
limited number of projects available.

Plant design projects are conducted during normal term
time. Following identification of a real industrial problem,
students work in groups to find alternative solutions. Regu-
lar meetings with the plant engineers and occasional visits to
the industrial site are made to keep the project on track. At
the conclusion, presentations are made, the solutions are
discussed, and a report is submitted. This venture has
proved to be very successful and of benefit both to the
students and to the company.

While it is difficult to provide industrial exposure to stu-
dents within a required university course, we have suc-
ceeded in doing it at the University of New Brunswick by
using an industrial facility on the campus. Through appro-
priate organization, it is possible to give all second-year
students some industrial experience early in their education
as part of the regular chemical engineering curriculum.

The author wishes to acknowledge the support and assis-
tance received from Brian Lowry and Frank Collins in mak-
ing the boiler test a meaningful exercise and in carrying the
balance of the laboratory course to a successful conclusion.
Nancy Mathis, of Mathis Instruments Ltd., initiated the origi-
nal concept of factory tours; Mladen Eic coordinates the
matching of students to practice-school projects each year;
and Guido Bendrich directs the plant design projects.

1. American Society of Mechanical Engineers, "ASME Power
Test Code, Steam Generating Units," PTC 4.1 (1964)
2. Eic, M., "Practice School in the Chemical Engineering Cur-
riculum at the university of New Brunswick," 42nd Cana-
dian Chemical Engineering Conference, Toronto (1992) 0

, Oclassroom



Effective Questioning in the ChE Classroom

University of Iowa Iowa City, IA 52242

he classroom atmosphere in many college lecture
halls is far from ideal. Many students are passively
involved in learning the material-if they are in-
volved at all. When called upon, a typical student often
responds with as few words as possible or simply waits for
the professor to answer for him or her. Wouldn't it be great if
students walked into class excited and ready to go? If they
discussed the material in class and were actively involved in
their own learning?
Actually, the two situations are not that far removed from
each other, and two small teaching behaviors could close the
gap considerably. Just two changes can result in increased
student participation, increased student interest, and increased
student learning. The first teaching change involves asking
better questions; the second change is waiting an appropriate
amount of time for the students' response.
One problem is that many questions frequently encoun-
tered in a college lecture hall are short-answer in nature, e.g.,
there is only one correct response and it doesn't require
much thought to come up with it. In my experience, profes-
sors rarely ask a question that requires the student to synthe-
size an answer. Even when a good question is posed, most
professors fail to provide an appropriate amount of time for
the student to synthesize an answer-and they end up telling
the students the solution to the problem.
There are five types of questions that are usually ap-
Attention-focusing questions These are typically short-
answer questions; they ask such things as "have you seen?"
"did you notice?" or "what happens if?" Measuring and
counting questions such as "how often?" and "how many?"
are also short-answer in nature.
Comparison questions These are extended-answer/open-

ended questions and are typically qualitative in nature. Ex-
amples include "how are...and...similar?" and "how do they
Action questions These are the "what happens if?" ques-
tions and are usually open-ended in nature.
Problem-posing questions Questions of this nature are
typically phrased in a manner similar to "can you find a way
How and why questions These questions are frequently
misused and should be avoided in most circumstances. Such
questions include "Why do you think?", which is highly
open-ended. The questions typically result in a teacher tell-
ing the students they are right or wrong, depending on what
they say, and can do more harm than good in terms of
student self-esteem.
Unfortunately, randomly asking the right type of question
alone does not solve the problem of passivism in the class-
room. A good questioning technique is also needed. The
questions must be of an appropriate level of difficulty so the
students will find them interesting, and they must follow a
progression that is logical to the students. Since students are
being exposed to the material for the first time, jumps that
may seem logical to the instructor could leave student com-
prehension behind. In order for students to learn, the order of

Copyright ChE Division ofASEE 1997

Chemical Engineering Education

Kenneth Kauffman is an undergraduate stu-
dent double majoring in chemical engineering
and science education at The University of Iowa.
He has served as a preteaching intern (under-
graduate teaching assistant) for two chemical
engineering courses and has also had experi-
ence teaching both elementary and junior high
school classes. In August of 1997 he will gradu-
ate with certification to teach grades 7-12 in
chemistry, physics, and physical science.

A good questioning technique is also needed. The questions must be of an appropriate
level of difficulty so the students will find them interesting, and they
must follow a progression that is logical to the students.

questions must make sense to them. Care should be taken to
ensure that jumps in logic are not too large.
One questioning model that has been proposed (by no
means the only appropriate model, however) is the HRASE
(read as "harass") model.121 Using this model, the first ques-
tion should relate the upcoming questions to the
History of the student, his or her past experience.
Appropriate questions include "What did you find?"
and "What happened when?" They should be rela-
tively easy to answer but should require more than a
yes/no answer. After a history has been developed
with the students, the next step is to have the students
Relationships and patterns with questions such as
"How does this compare to?" and "What is a common
theme in your results?" By drawing relationships,
students are logically prepared for the next step, which
is finding an
Application for the knowledge. These questions in-
clude "How could you use this?" and "If you wanted
to do that, how would this help?" After the students
have discussed some applications of the knowledge,
the next step is to make
Speculations about a different situation. Appropriate
questions include "What if we did this instead?" or "If
we wanted to prevent that from happening, what could
we do?" After the students have made some specula-
tions (and perhaps tested them), the next step is an
Explanation for the experience. Appropriate ques-
tions for this include "How does that work?"or "What
causes that to happen?" or "How would you change
your explanation if I changed...?"
To summarize, the HRASE model is a questioning strat-
egy that provides a logical order for asking questions. To
demonstrate an example of HRASE at work, consider a mass
transfer course where the students have just finished a labo-
ratory on batch flash distillation. To lead into a multistage
process, the following series of questions could be used.
- What happened when weflashed an ethanol-water mix-
A question such as this calls on the students' past expe-
rience and brings to mind an actual event to which they
can all relate.
Spring 1997

iRe How does this compare to the batch distillations you
have done in organic lab?
This question causes the students to relate the material
from the mass transfer course to other courses they have
taken. It also encourages them to compare and contrast
the two processes.
[A If you wanted to separate benzene and toluene, what
problems would you encounter. ?
This provides an opportunity for the professor to assess
student understanding. He is asking the students to ap-
ply knowledge they already have to a new situation. If
he is not satisfied with the responses, the professor can
send the students to the teaching laboratory and let them
encounter the problems.
S What would happen to the vapor phase if I added a
partial condenser at the top? How could we find evi-
dence to support that?
This requires the students to speculate-an unknown.
Care must be taken (if future participation of the stu-
dents is desired) to ensure that the students do not feel
embarrassed by "wrong" responses. To minimize such a
situation, one approach is to put all the student predic-
tions on the board, ask the students to choose the one
they like most, and then test it as a class exercise. In a
teaching laboratory, a small-scale model of a flash
drum can be used to test the student predictions. If a
teaching assistant has the equipment ready to go
when the students arrive, the demonstration would
only take a few minutes.
] What causes this to happen?
This type of question gives the professor an idea of
student misconceptions since their explanations will re-
flect their misconceptions. When one or two students
voice a major misconception, it is likely that others in
the class hold the same misconception. Rather than tell-
ing students they are wrong, ask them to make predic-
tions (another Speculation question) about what they
would expect to see if this were the case, and have them
do this as part of a laboratory exercise. Notice that such
an approach results in a learning-cycle approach to teach-
ing, which research has shown to be very effective.[3'41
If used appropriately and consistently, this model and
others like it have the potential of increasing desirable stu-

dent behavior. There are times, however, that even when
asking all of the "right" questions at the "right" time will still
result in no response from the students.
Instructors will frequently ask a question and then wait
less than one or two seconds for the students to respond,
regardless of the type of question. Increasing the wait-time
has a variety of effects:[]1
Length of student responses increases by up to 700%
Students demonstrate more logic andprovide support
for arguments
Students speculate more
Students ask more questions and propose more
Student-student exchanges increase
Student responses of "I don't know" (or no response)
Students stay attentive for longer periods of time
Students volunteer more
Student confidence increases
Achievement on written measures improves
These positive outcomes relate to many of the common
goals shared by chemical engineering faculty. Specifically,
students have more opportunities to demonstrate the depth
of their understanding of fundamental chemical engineering
concepts; they practice effective communication skills; they
are better able to apply chemical engineering concepts; and
they are better prepared to encounter new situations. Obvi-
ously, effective use of wait-time offers many benefits in the
chemical engineering curriculum.
There are two types of wait-time. Wait-time one refers to
the amount of time an instructor gives a student to respond to
a question before moving on to another question. Wait-time
two refers to the amount of time the instructor waits after a
student has responded to a question to allow other students
to respond. In order for the above benefits to be fully real-
ized, both types of wait-time should be used and the students
should be made aware of the instructor's expectations.
After asking an open-ended question, at least three sec-
onds of wait-time one should be provided for the students to
formulate their responses. Longer time can be used for more
complex questions. In fact, a wait-time of over a minute is
not unreasonable for engineering problems. It allows the
student to formulate a coherent response in which he or she
has considered some of the specific details and allows for
better discussions to ensue. Beware, however, of the percep-
tion of time. One minute of silence in a classroom can seem
like an eternity, especially to the instructor. If a problem
should take more than a minute to reason through, don't be
afraid to use a watch.

After the first student has responded, wait again. At least
three more seconds of wait-time are required for wait-time
two. For the first few times that wait-time two is used, the
instructor may need to prompt the students to respond to
each other. An appropriate question might be, "What al-
ternatives do you have to his (her) idea?" or "What are
the problems/benefits of that idea?" Research also shows
that giving a student a chance to respond without inter-
ruption and without immediate rejection/acceptance can
improve the student's self-esteem and the quality of his
or her learning.15-71
Once an instructor starts using wait-time, he or she should
talk to others about the experience and have outsiders evalu-
ate it by measuring the quality and length of responses both
before and after wait-time. This allows the instructor to get a
second opinion on the value of wait-time and also helps to
make the changes more lasting-if there is corroborative
evidence that the wait-time is effective, the instructor is
far less likely to revert to the original wait-times of less
than one second.151
In addition to the outside review, students should also be
asked to evaluate the experience. There are two reasons for
this: first, the instructor can get an idea of what is an appro-
priate length of time for wait-time two; and second, the
students will have an opportunity to inject some of their own
input into the class, which frequently has many other posi-
tive advantages.181
Even with adequate wait-time and appropriate questions,
there are still occasions when students will feel too threat-
ened to respond to questions. Typically, highly speculative
questions tend to increase student anxiety and result in less
participation, but such questions are very relevant to assess-
ing student understanding and student progression. One way
to overcome student anxiety is to ask a lot of speculative
questions. Let the students work on the problem by them-
selves for a brief period of time, and then ask them to discuss
their ideas with the person next to them; next, ask them to
share their ideas with the rest of the class. The result of this
procedure is that students are less likely to feel anxious
about the possibility of proposing a wrong idea. If the stu-
dent is still nervous about sharing in class, his or her partner
can present the idea instead.
If the professor accepts all ideas and writes all of them
down on the board (even the incorrect ones), the students
will begin to feel comfortable when expressing an opinion or
an idea in this class. That is not to say that a professor should
let just any comment be construed as correct. Rather, after
all of the ideas are on the board, he should go back and
evaluate them for the class. This distances rejection from the
student-that is, the student is less likely to feel rejection in
front of the class. Over time, such an approach can result in
students proposing speculative ideas without having to first

Chemical Engineering Education

consult with a peer, and it can lead to student realization that
there is a time for speculation-even incorrect speculation.
By asking more appropriate questions and asking them in
a logical sequence, it is possible to improve the quality of in-
class student interaction. Furthermore, such interaction comes
at a low cost, and it can improve both the self-esteem of the
students and their learning potential. In addition to asking
the right type of question, it is essential that wait-time be
used to allow students to formulate and work through their
responses. Wait-time one allows students enough time to
come up with an appropriate response, and wait-time two
allows students to prepare a response to other students re-
sponses; the result is a more student-centered classroom.
The instructor should use both student and peer evaluation
to help him realize the full potential of the results. By using
these simple techniques in the classroom, the quality of
instruction can increase dramatically.

I would like to thank Drs. Murhammer and Wiencek for
allowing me to practice these skills in their chemical engi-

neering classrooms. I would also like to thank Drs. Clough,
Penick, and Tillotson in science education for their guid-

1. Elstgeest, Jos., Primary Science: Taking the Plunge, Chap
4., The Right Question at the Right Time, Heinemann Edu-
cational Books, Great Britain (1985)
2. Penick, John E., Linda W. Crow, and Ronald J. Bonnstetter,
"Questions are the Answer: A Logical Questioning Strategy
for Any Topic," The Science Teacher, p. 27 (1996)
3. Abraham, M.R., "A Descriptive Instrument for Use in In-
vestigating Science Laboratories," J. of Res. in Sci. Teach-
ing, 19, 155 (1982)
4. Schneider, L.S., and J.W. Renner, "Concrete and Formal
Teaching," J. of Res. in Sci. Teaching, 17, 503 (1980)
5. Rowe, Mary Budd, "Wait-Time: Slowing Down May Be a
Way of Speeding Up," J. of Teacher Ed., Jan-Feb (1986)
6. Mehrabian, A., Tactics of Social Influence, Prentice Hall,
Englewood Cliffs, NJ (1970)
7. Treffinger, D., "Guidelines for Encouraging Independence
and Self-Direction Among Gifted Students," J. of Creative
Behavior, 12(1), 14 (1978)
8. Delbert, J., and W. Hoy, "Custodial High Schools and Self-
Actualization of Students," Educational Res. Quart., 2, 2:24
(1977) J

m -new books

Progress in Dairy Science, edited by C.J.C. Phillips; Oxford University
Press, 198 Madison Avenue, New York NY 10016; 417 pages. $110 (cloth)
FORTRAN Programs for Chemical Process Design, Analysis, and Simu-
lation, by A. Kayode Coker; Gulf Publishing Company, Houston, TX
77252-2608; 854 pages (1995)
The Nuclear Fuel Cycle From Ore to Waste, edited by P.D. Wilson;
Oxford University Press, 198 Madison Avenue. New York NY 10016; 323
pages, $55 (1996)
Fluid Mechanics, by David Pnueli and Chaim Gutfinger: Cambridge
University Press. 40 West 20th St., New York NY 10011-4211; 482 pages.
$49.95 (hardback), $34.95 (paperback) (1997)
Alternative Fuels, by Sunggyu Lee; Taylor & Francis, 1900 Frost Road,
Suite 101, Briston PA 19007-1598; 485 pages, $79.95 (1996)
Green Technology and Design for the Environment, by Samir Billatos
and Nadia Basaly; Taylor & Francis. 1900 Frost Road, Suite 101, Briston
PA 19007-1598; 296 pages, $39.95 (1996)
Antioxidative Stabilization of Polymers, by Shlyapnikov, Kiryushkin,
and Mar'in; Taylor & Francis, 1900 Frost Road. Suite 101. Briston PA
19007-1598; 243 pages, $49.95 (1996)
Handbook on Bioethanol: Production and Utilization, edited by Charles
E. Wyman; Taylor & Francis, 1900 Frost Road. Suite 101, Briston PA
19007-1598; 424 pages, $89.95 (1996)
Environmental Technology Handbook, by James G. Speight; Taylor &
Francis, 1900 Frost Road, Suite 101, Briston PA 19007-1598; 302 pages,
$69.95 (1996)
Dispelling Chemical Engineering Myths, 3rd ed., by Trevor Kletz: Tay-
lor & Francis, 1900 Frost Road, Suite 101, Briston PA 19007-1598; 202
pages, $89.95 (1996)
Stereochemistry of Coordination Compounds, by Alexander von Zelewsky:
John Wiley & Sons, 605 Third Avenue, New York NY 10158; 254 pages,
Spring 1997

$34.95 (paperback) (1996)
Polymeric Systems, by I. Prigogine and Stuart A. Rice; John Wiley &
Sons, 605 Third Avenue, New York NY 10158; 740 pages, $130 (1996)
Mathematical Methods for Scientists & Engineers: Linear & Nonlinear
Systems. by Peter B. Kahn; John Wiley & Sons, 605 Third Avenue, New
York NY 10158; 469 pages, $38 (paperback), $89.95 (cloth) (1996)
Corrosion of Stainless Steels. 2nd ed., by John Sedriks; John Wiley &
Sons, 605 Third Avenue. New York NY 10158: 437 pages, $69.95 (1996)
Surface Properties, edited by I. Prigogine and Stuart A. Rice; John Wiley
& Sons. 605 Third Avenue, New York NY 10158; 432 pages, $95.00
Inmobilization of Enzymes and Cells, edited by Gordon F. Bickerstaff;
Humana Press, 999 Riverview Drive, Suite 208, Totowa, NJ 07512; 367
pages, $79.50 (1997)
Advances in Chemical Physics, by I. Prigogine and Stuart A. Rice; John
Wiley & Sons, 605 Third Avenue, New York NY 10158; 330 pages, $125
Patent Strategy for Researchers and Research Managers, by J. Jackson
Knight; John Wiley & Sons, 605 Third Avenue, New York NY 10158; 166
pages. $49.95 (1996)
The Surface Science of Metal Oxides, by V.E. Henrich and P.A. Cox;
Cambridge University Press, 40 West 20th Street, New York, NY 10011-
4211; 464 pages. $99.95 (hardback) $39.95 (paperback) (1996)
Numerical Methods for Engineers, by Santosh K. Gupta; Franklin Book
Co. Inc.. 7804 Montgomery Ave.. Elkins Park, PA 19117; 407 pages
New Methods in Computational Quantum Mechanics, edited by I.
Prigogine and Stuart A. Rice: John Wiley & Sons, 605 Third Avenue, New
York NY 10158; 813 pages. $130 (1996)

S" outreach





The University of Melbourne e Parkville, Victoria 3052, Australia

Engineering faculties around the world must constantly
work to ensure that they attract high quality students
to their courses, but unfortunately, prospective stu-
dents often have a poor appreciation for engineering. They
are unaware of the diversity of challenges and opportunities
that await them in an engineering career.
A number of strategies exist to raise the profile of engi-
neering for students in secondary schools. One activity in-
volves engineering academics either visiting the schools or
playing host to the students on college campuses. Another
method is to furnish secondary-school mathematics teachers
with real engineering design problems that can be solved by
the application of relatively simple mathematical concepts.
This paper describes a challenge in chemical engineering
design that can be answered in the classroom by applying
logic and a knowledge of the volumes of cylinders and
rectangular prisms. The problem can be presented to differ-
ent grade levels by selecting individual parts and can either
be carried out by individuals or as a team exercise. It was
presented to groups of secondary-school mathematics
teachers in 1994 and 1995, and it has since been incorpo-

rated into the secondary school syllabus in a number of
schools in Victoria, Australia.[]1
The problem involves the design of a bulk liquid chemical
storage facility-a tank farm. Students are asked to design a
facility to store a given volume of liquid while considering
such design aspects as bund bermm) wall height and thick-
ness, tank spacing, maintenance access, and allowance for
fire-fighting water. A presentation to mathematics teachers
in as little time as forty-five minutes can provide sufficient
information for them to return to their schools and tailor the
material to their individual requirements.

The information session for the teachers begins with an
introduction to the use of tank farms. It is important to give
the teachers local examples of where tank farms can be
found. In the case of Melbourne, we refer to a bulk liquid
chemical storage facility located at Coode Island, less than 4
km from the downtown area. This facility is well known
locally due to a major fire at the site in August of 1991. We
show video footage of the facility and the fire and emphasize
the fact that because of proper facility design, all the spilled
liquid chemicals and fire-fighting water was contained
within the site. As the video is shown, we point out the
bunds, the position of the tanks within the bunded com-
pounds, and the pipe tracks.
While some may argue that it is unwise to highlight an
incident that brought bad publicity to the local chemical
industry, we feel it is important to emphasize that good
engineering design helped to contain a dangerous situation.
We describe and discuss the important safety aspects of

Copyright ChE Division of ASEE 1997

Chemical Engineering Education

David Shallcross is a Senior Lecturer in Chemi-
cal Engineering at The University of Melbourne.
He received his BE and PhD degrees at The
University of Melbourne. His research interests
include ion exchange processes in radial flow
and enhanced oil recovery techniques for light

This paper describes a challenge in chemical engineering design that can be answered in the
classroom by applying logic and a knowledge of the volumes of cylinders and rectangular
prisms. The problem can be presented to different grade levels by selecting
individual parts and can be either be carried out by
individuals or as a team exercise.

design and bring attention to the relevant standards and
government regulations as a way of showing how engineers
must work within the framework of government rules and
restrictions. In Victoria, reference is made to the appropriate
Australian Standard, AS 1940-1988 The Storage and Han-
dling of Flammable and Combustion Liquids, and the Dan-
gerous Goods (Storage and Handling) Regulations of 1989.
Local equivalents would be substituted as appropriate.
In order to limit the problem, only upright cylindrical
tanks are considered. We point out that these tanks must be
built within a bunded area that will contain any spill. The
government regulations and standards require that the spill
containment compound enclosed by the bund has a net
capacity equivalent to the largest tank in the compound,
plus ten percent of the capacity of the second largest
tank, plus a volume equal to the output of the fire-fight-
ing sprinkler system over a period of twenty minutes.
These figures vary depending on the particular standard
or government regulation.
We give the teachers the following information with re-
spect to the design requirements of the spill containment

1. The ground within the bund must slope gently
away from the tank to prevent accumulation of
liquid around the base of the tank. Any liquid spill
must drain to a sump within the bunded area.
2. The bund wall must be no higher than 1.5 in above
the compound floor to ensure adequate ventilation
around the tanks and to allow quick egress from
the compound in an emergency.
3. The bund wall must be impervious to, and compat-
ible with, the dangerous chemicals stored within
the compound.
4. The bund must be designed to withstand the
hydrostatic head when full.
5. The perimeter of the spill compound must be
located a sufficient distance from all tanks within
the compound to prevent a leak from the surface
of the tank spilling over the bund outside the
compound. The minimum distance between a tank
and the bund wall is one-half the height of the tank
above the top of the bund wall.

6. The bund wall must have aflat section at the top
not less than 600 nun wide.
7. Incompatible chemicals may not be stored within
the same bunded area.
8. The bounded area may contain no equipment, with
the exception of the tanks and the pipes that
service them. Pumps are not permitted within the
spill collection area.
9. The minimum distance between any two tanks in
the same collection area depends on the diameters
of the two tanks:
If neither tank exceeds 6 m in diameter, the
distance between them shall be not less than
either one-third of the diameter of the larger tank
or I m, whichever is the greater.
If one of the tanks is more than 6 m, but neither
is more than 20 m in diameter, the distance
between them shall be not less than one-half of the
diameter of the larger tank.
If one of the tanks is 20 m or more in diameter,
the distance between it and any other tank shall
not be less than 15 m.
10. Where the aggregate capacity of the tanks in any
compound exceeds 10,000 n', intermediate bunds
of at least half the height of the main bunds or 600
mm, whichever is the lesser, shall be provided so
that any subdivision so created contains tanks
having an aggregate capacity not exceeding
10,000 m or a single tank if such tank exceeds
that capacity.

Not all the design requirements listed above are used in the
calculations that follow. For example, the third and fourth
points relating to the physical design of the bund are
provided for the general information of the teacher and
student, but are not required in the actual calculations. It
is important, however, that this type of background in-
formation is included.

The teachers are given a worked example for the design of
a facility to store 26,000 bbl of oil. The oil is to be stored in

Spring 1997

four identical tanks located within a single containment area.
We begin by performing a unit conversion to obtain an oil
volume of 4134 m3. If a maximum height restriction of 9.1 m
is arbitrarily set for the four tanks, then the minimum diam-
eter for each of the tanks is found to be 12.1 m. Alterna-
tively, the tanks could be required to be half as high as
they are wide. A height of 6.9 m and a diameter of 13.8 m
would be calculated.
Next, we calculate the minimum volume of the spill con-
tainment area necessary to satisfy government regulations.
We recall that the minimum volume equals the volume of
the largest tank plus 10% of the next largest tank plus a 20-
minute supply of fire-fighting water. If we arbitrarily as-
sume a volumetric flow rate for the fire-fighting water of 30
m3/min, and we recall that the four tanks are identical, then

Minimum Volume = 1034 + 0.1 x 1034 + 600 = 1737 m3
Regulations demand a bund wall be no higher than 1.5m.
Assuming an average depth of 1.4 m within the spill com-
pound, we then calculate that 1241 m2 is the minimum
area of the spill containment compound available to con-
tain the liquid.
The spill compound is to be square, with the four tanks
equally spaced in a square pattern within it (see Figure 1). If
each tank has a diameter of 12.1 m, we then calculate the
minimum length of one side of the compound. Letting L be
the length of one side of the compound and assuming the
bund walls are vertical, we find

Area = L2 4
where the second term accounts for the area taken up by the
bases of the four tanks. Therefore

1241= L2 t(12.1)2

L2 =1701 or L= 41.2m
So the length of one side of the compound is 41.2 m.
We then ask whether this length is practical. Would a
compound with this length satisfy the spacing requirements
of the government regulations? Consider the spacing be-
tween the tanks and between the tanks and the bund walls.
The minimum distance, dr, between adjacent tanks is one-
half the diameter of the largest tank. The minimum distance,
dT1, between a tank and a bund wall is one-half the height of
the tank above the level of the top of the bund wall.
If tank diameter = 12.1 m
tank height = 9.1 m
bund wall height = 1.5 m

dT =-- 6.1m
dTB = = 3.8m

Considering Figure 2, we see that the minimum length of
one side, Lmin, is given by

Lmin = dTB + d + d- + d + dTB
= 2 x 3.8 + 2 x 12.1+6.1
= 37.9m

Since 41.2 m is greater than the minimum length required to
satisfy the minimum spacing requirements, this length is
The degree of difficulty of the above problem can be
increased by requiring the calculation of the optimum tank
height-to-diameter ratio so that the area occupied by the
spill- containment compound is a minimum. Letting a = h / d,
we find

_d2h _otad3
VTank d2h cd
4 4
and thus

d 3VTa and h 4VTank
V TIt \ T
Denoting the containment area by Acont to find

A 4ixd2
Lcont = LA
=> L = Acont + Td2



Figure 1. View of the spill-containment compound
showing the location of the four identical tanks.

Chemical Engineering Education


Lmin = 2d+ 2B +dTT
(h -1.5) d
= 2d+ 2 J
= 2.5d+h-1.5
The minimum area of the compound occurs when
L = Lmin

-FAcont + td2 d + h 1.5

S (4 AV 2/3
\ io

(5 4 V -ank1.5
_2 nA

We know that VTank = 1034 m3 and A,co = 1241 m2. Solving
the equation, we obtain a = 2.25. Therefore
d=8.36m, h= 18.8m, and L= 38.2m
In performing the above calculations, a number of simpli-
fying assumptions have been made to allow the problem to
be applied in the classroom without unnecessary complica-
tions. The problem, however, still retains a number of im-
portant engineering considerations.
This exercise has been developed so that it can be pitched
to different grade levels. Younger students may be asked to
perform the basic calculations, while more senior or capable
students may be required to perform optimization calcula-
tions. In performing the calculations, the junior students
might be told to assume that the ground within the spill-
collection compound is flat. More advanced students, how-
ever, might be told that to prevent any spilled liquids from
collecting around the base of the tank, the floor of the com-
pound slopes away from the tank. They would then have to
assume that the tank is located at the apex of a flat cone and
that they must account for this change of depth within the
spill-collection compound in their calculations.

The tank farm for a small refinery must be able to store the
unrefined oil as well as a range of products that can include
different grades of gasoline, diesel fuels, and lubricating
oils. These liquids would be stored in tanks of different sizes
in a number of different spill-containment compounds.
A class exercise that could be developed by the teacher

I< >-
K/// //////
Bund Ta / Bund

dFigure d2. dSide view of the spill-containment compound

Figure 2. Side view of the spill-containment compound.

would involve the preparation of a neat, scaled plan of such a
tank farm. Each student or group of students could be re-
sponsible for performing the design calculations for a single
containment compound. The plan would include the indi-
vidual tanks and containment compounds as well as showing
the location of roads and pipe reservations.
In designing the tank farm, the following points should be
The width of the pipe reservation will range between
2 and 4 m. The reservation is outside the bund and
runs between the tanks and the loading points.
The width of the roadways between the compounds
will be about 8 mfor side roads and 10 mfor main
Compounds with tanks storing different liquids
should not share a common bund.
The minimum number of tanks required for any one
product is three.
Several additional tanks should be included in the
plan to increase flexibility of refinery operation.
The largest tank on site should be no larger than 21
m high and 46 m in diameter. The next largest size
would be 17 m high and 41 m in diameter.
These figures have been arbitrarily set as a guide for the

Many of the calculations presented to the teachers can be
automated by the students using spreadsheet packages such
as Microsoft Excel. Students would then be able to see how
varying parameters such as the tank aspect ratio, bund wall
height, and number of tanks can affect factors such as the
required area for the spill compound.
Whether they are teaching simple algebra or more ad-
vanced calculus, mathematics teachers at any grade level are
often confronted by students with questions such as "Why
are we learning this?" and "What is this used for?" Examples
of real engineering problems such as the one described above,
albeit in simplified form, allow the teachers to answer some
of these questions. This sort of activity not only helps to
raise the profile of engineering in secondary schools, but it
also provides mathematics teachers with a valuable resource.
This exercise has been greeted enthusiastically whenever it
has been presented to teachers.

1. Shallcross, D.C., "Investigative Project in Engineering: De-
signing a New Coode Island," Proc. of the Mathematics
Association Victoria 32nd Ann. Conf., Mathematics Associa-
tion of Victoria, Melbourne, Australia (1995) O

Spring 1997

"5 class and home problems



University of Dayton Dayton, OH 45469-0246

Reactor optimization problems are commonly encoun-
tered in the study of chemical reaction engineering.
These problems become particularly interesting and
challenging when product distribution is a concern. The
simplest series reaction scheme
A-> R-S (1)
where the intermediate R is the desired product, is often
analyzed. While discussing this reaction with a group of
environmentally conscious chemical engineering students,
concern for the fate of the undesired by-product S arose.
What if species S is hazardous and presents disposal prob-
lems? How would this influence optimization of the reactor?
An example of this type of reaction scheme is the successive
chlorination of benzene to produce monochlorobenzene and
dichlorobenzene. The ortho and para isomers of dichloroben-
zene are health hazards'" that may entail immediate disposal

Kevin Myers is an associate professor in the
Department of Chemical and Materials Engi-
neering at the University of Dayton. He received
his BChE degree from the University of Dayton
and his DSChE from Washington University in
St. Louis. His research interests are in multi-
phase agitation and chemical reactors.

costs and/or future liability costs.121 Fogler[3] has suggested
that this reaction sequence can be carried out in a continu-
ous stirred tank reactor (CSTR), and if the liquid phase is
saturated with chlorine, then the reaction kinetics can be
taken as first-order in nature.

A diagram of the reactor is shown in Figure 1. Note that
the feed concentrations of the product species R and S will
be taken to be zero (CR, = Cso = 0). Before considering our
analysis of this problem, a quick review of the typical ap-
proach to optimizing the performance of a CSTR for this
reaction scheme will be given. When disposal of the by-
product S is not a concern, the effluent concentration of
species R is usually maximized to optimize reactor perfor-
mance.[41 For the case of first-order reaction kinetics
-rA = kiCA rR = kCA k2CR s = k2CR (2:
the CSTR design equation for constant-density conditions
V CAo -CAf CRf -CRo (3
Q -rA rR
can be solved for the effluent concentrations of species A
and R

CAo 1+kI,

Copyright ChE Division ofASEE 1997

Chemical Engineering Education

The object of this column is to enhance our readers' collections of interesting and novel
problems in chemical engineering. Problems of the type that can be used to motivate the student
by presenting a particular principle in class, or in a new light, or that can be assigned as a novel
home problem, are requested, as well as those that are more traditional in nature and which
elucidate difficult concepts. Please submit them to Professor James O. Wilkes (e-mail: or Mark A. Burns (e-mail:, Chemical
Engineering Department, University of Michigan, Ann Arbor, MI 48109-2136.

CRf k '(4b
CAo (1+kl,)(l +k,T)
The effluent concentration of species S can be determined
from the reaction stoichiometry

Csf = CA Rf (4c
Maximizing the effluent species R concentration with re-
spect to the reactor space time by setting dCRf / dt equal to
zero indicates that the optimal reactor space time is

tmax kk )15 (5a

The corresponding maximum effluent concentration of spe-
cies R is

CAo 1/

C<0 kHY'"

Now reconsider this reactor optimization problem when
there are disposal costs associated with the production of
species S. In this case, the problem becomes one of pollution
prevention.121 First, it is necessary to choose an objective
function that is to be optimized. We chose an economic
S objective function, the value of the effluent stream per unit
volume ($f), which can be expressed as the difference be-
tween the income that can be obtained from selling the
desired product (species R) and the cost required to dispose
of the undesired by-product (species S)

$f = PRCRf PSCSf (6)

Reactor Feed
CRo = Co= 0

Reactor Effluent

CAf, CRf, CSf

Figure 1. CSTR diagram.



o 0.2

Figure 2. Influence of the cost-to-price ratio on the optimal
reactor space time and corresponding effluent concentra-
tions when the value of the effluent stream is maximized and
k,=k2=i time-.
Spring 1997

PR represents the income per mole that can be obtained
from the sale of species R while Ps is the cost per mole
associated with the disposal of species S. To keep the
analysis straightforward, this objective function does
not include any costs associated with species A (per-
haps species A is inexpensive or can readily be sepa-
rated from the effluent and recycled to the reactor). But
this consideration could also be included in a more
detailed analysis.
The objective function of Eq. (6) can be maximized
with respect to the reactor space time using the effluent
concentrations of Eq. (4) (note that these expressions
are not influenced by the change in objective function).
Setting d$f /dT equal to zero yields the reactor space
time that maximizes the value of the effluent stream per
unit volume

+ 1/2
Topt = +a (7)

The parameter a is the ratio of the reaction rate con-
stants, while the parameter p characterizes the relation
between the selling price of species R and the disposal
cost of species S,
k Ps + PR PR (8)
k, PS Ps
The expression for the optimal reactor space time in
this instance is rather unwieldy, but can be combined
with Eq. (4) to yield the corresponding effluent con-
Figure 2 illustrates the variation of the optimal reac-
tor space time and effluent concentrations with respect
to the cost-to-price ratio Ps/PR for the specific case of

k, = k2 = 1 time '(any arbitrary time units can be used). In the
limit of the income from selling species R far exceeding the
cost of disposing species S (PR>>PS such that Ps/PR 0) the
present solution reduces to that found previously when the
effluent concentration of species R was maximized (Eq. 7
reduces to Eq. 5a as p approaches infinity).
As the cost of disposing species S increases, the amount
of S produced must be decreased to maximize the value of
the effluent stream. This is done by decreasing the reactor
space time, which in turn decreases the effluent concentra-
tion of the desired product (species R) such that the driving
force for the production of species S is decreased (refer to
Eq. 2). This also increases the effluent concentration of the
raw material (species A).
In the limit of very high disposal costs (Ps>>PR), the
process cannot be profitable and the optimal reactor space
time tends to zero so that no reaction occurs and the forma-
tion of species S is avoided.

This problem also leads to related exercises:
> Students can find examples of industrially relevant
reaction schemes that fit this scenario. This should
include finding selling prices and disposal costs to
quantify the optimum reactor space time.
Students can demonstrate that the results of the new
analysis reduce to the results of the traditional
analysis when the cost of disposing of species S is
negligible (that is, show that Eq.7 reduces to Eq. 5a
as p approaches infinity).
The technique of maximizing the value of the
product stream can be modified to account for
species S being a marketable product, but with a
lower selling price than the intermediate species R.
Fogler151 cites the successive hydrodealkylation of
mesitylene to produce m-xylene and toluene as an
example of this situation. Both species have selling
value, but m-xylene is preferred because of its
higher selling price. Westerterp, et al.t61 discussed
the successive chlorination of methane to form
methyl chloride, methylene chloride, chloroform,
and carbon tetrachloride. In this more complex
reaction scheme, methylene chloride and carbon
tetrachloride have the higher selling prices.
As shown in Figure 2, large amounts of species A
may remain in the effluent stream. This indicates
that the simplifying assumption that the costs
associated with species A are negligible may not be
valid. A more complex optimization problem would
include the cost of the species A raw material and/or
the cost of separating species A from the product


The author would like to acknowledge the encouragement
and suggestions provided by the editor of the "Class and
Home Problems" and the reviewer of this article.

C, Concentration of species i (mole/m3)



Effluent concentration of species i (mole/m3)
Feed concentration of species i (mole/m3)
Maximum effluent concentration of species R (mole/m3)
First-order reaction rate constants (s-')

PR Selling price of species R ($/mole)
Ps Disposal cost of species S ($/mole)
Q Volumetric flow rate (m3/s)
r, Rate of production of species i per unit volume (mole/
V Reactor volume (m3)

$, Value of the effluent stream per unit volume ($/m3)
a Kinetic parameter k1/k, (-)
3 Cost parameter (Ps+P)/P,(-)
T Reactor space time (s)

'max Reactor space time that maximizes the effluent concen-
tration of the desired product (s)
Topt Reactor space time that maximizes the value of the
effluent stream (s)

1. The Fisher Catalog 95/96, Fisher Scientific, Pittsburgh,
PA, p. 100C (1994)
2. Allen, D.T., N. Bakshani, and K.S. Rosselot, Pollution Pre-
vention: Homework & Design Problems for Engineering Cur-
ricula, AIChE Center for Waste Reduction Technologies,
Problem 17, "The Effect of Future Liability Costs on Return
on Investment," p. 125 (1992)
3. Fogler, H.S., Elements of Chemical Reaction Engineering,
1st ed., Prentice-Hall, Englewood Cliffs, NJ, Prob. P9-14, p.
4. Levenspiel, O. Chemical Reaction Engineering, 2nd ed.,
Wiley, NY, p. 178 (1972)
5. Fogler, H.S., Elements of Chemical Reaction Engineering,
2nd ed., Prentice-Hall, Englewood Cliffs, NJ; Ex. 9-6,
"Hydrodealkylation of Mesitylene in a PFR," p. 510 (1992)
6. Westerterp, K.R., W.P.M. van Swaaij, and A.A.C.M.
Beenackers, Chemical Reactor Design and Operation, Wiley,
NY; Ex. III.4.d., "A Chain of Consecutive Reactions, the
Chlorination of Methane," p. 120 (1984)
7. Allen D.T., N. Bakshani, and K.S. Rosselot, Pollution Pre-
vention: Homework & Design Problems for Engineering Cur-
ricula, AIChE Center for Waste Reduction Technologies,
Prob. 16, "Reaction Pathway Optimization for Waste Reduc-
tion," p. 121 (1992) 0

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