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

.r. -. .e d ca tion

We wish to
acknowledge and thank...



...for supporting

with a donation of funds.

Chemical Engineering Education
Department of Chemical Engineering
University of Florida
Gainesville, FL 32611

EDITOR: Ray W. Fahien (904) 392-0857
MANAGING EDITOR: Carole Yocum (904) 392-0861


Gary Poehlein
Georgia Institute of Technology

Klaus D. Timmerhaus
University of Colorado

Lee C. Eagleton
Pennsylvania State University

Richard M. Felder
North Carolina State University

Jack R. Hopper
Lamar University

Donald R. Paul
University of Texas

James Fair
University of Texas

J. S. Dranoff
Northwestern University

Frederick H. Shair
California Institute of Technology

Alexis T. Bell
University of California, Berkeley

Angelo J. Perna
New Jersey Institute of Technology

Stuart W. Churchill
University of Pennsylvania

Massachusetts Institute of Technology
Charles Sleicher
University of Washington
Leslie W. Shemilt
McMaster University
Library Representative
Thomas W. Weber
State University of New York

Chemical Engineering Education

58 Lehigh University, Hugo S. Caram, John C. Chen

64 Noel de Nevers of Utah, Vickie S. Jones

68 Meet Your Students: 1. Stan and Nathan,
Richard M. Felder

70 Incorporating Health, Safety, Environmental, and Ethical
Issues into the Curriculum, Alan M. Lane

106 General Education Requirements and Chemical
Engineering Curricula, Walden L. S. Laukhuf,
C. A. Plank, James C. Watters

116 Heterogeneous Catalysis, R. Miranda

120 Design Education in Chemical Engineering: Part 2 -
Using Design Tools, J. M. Douglas, R. L. Kirkwood

76 Multiple Reaction Equilibria-With Pencil and Paper: A
Class Problem on Coal Methanation,
Friedrich G. Helfferich

82 An Alternative Approach to the Process Design Course,
Mark J. McCready

10a The Heart of the Matter: The Engineer's Essential One-Page
Memo, Rob Adams McKean, Emil L. Hanzevack

86 A Laboratory Experiment on Combined Mass Transfer and
Kinetics, Stuart A. Sanders, Jude T. Sommerfeld

92 Do Student Chemical Engineers Understand Experimental
Error? R. R. Hudgins, P. M. Reilly

96 A Three-Stage Counter Current Leaching Rig for the Senior
Laboratory, Wayne A. Davies

100 The ChEGSA Symposium: A Continuing Tradition at
Carnegie Mellon University,
Ajay K. Modi, Paul T. Bowman

112 CSTR's in Biochemical Reactions: An Optimization
Problem, F. Xavier Malcata


Lettertothe Editor
Positions Available
Books Received

CHEMICAL ENGINEERING EDUCATION (ISSN 0009-2479) is published quarterly by 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. Advertising mate-
rial may be sent directly to E. O. Painter Printing Co., P. Box 877, DeLeon Springs, FL 32028. Copyright
S1989 by tCh 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 with
120 days of publication. Write for information on subscription costs and for back copy cost and availability.
POSTMASTER: Send address changes to CEE, Chemical Engineering Department, University of Florida,
Gainesville, FL 3s611.




Ff- m*.1 *iI

New home of Chemical Engineering Department at Mountaintop Campus.


Lehigh University
Bethlehem, PA 18015-4791

THE CHEMICAL engineering program at Lehigh
started in 1907 and followed the growth of Lehigh
University from a small undergraduate school to its
current research university status. The department
has been characterized by a creative and personalized
approach to undergraduate education, complemented
by steady growth of its graduate and research ac-
tivities. It is currently among the larger chemical en-
gineering departments in the U.S., with 22 faculty
members, approximately 150 undergraduate stu-
dents, 95 resident graduate students, and 30 part-time
graduate students. In the past three years the depart-
ment has graduated an average of forty BS, twenty-
five MS, and fourteen PhD students per year.
Founded in 1865, Lehigh University is an inde-
pendent, co-educational institution dedicated to the
advancement of knowledge in a wide range of disci-

plines. The University takes pride in its highly com-
petitive curricula in science and technology, the arts
and humanities, and business and economics. Current
enrollment is approximately 4,300 undergraduate and
2,000 graduate students. The Chemical Engineering
Department has the largest graduate program of any
single department at the University and accounts for
approximately one out of every five PhD degrees
granted by Lehigh.
Lehigh University's educational philosophy is
based on the premise that preparation for successful
living must combine the acquisition of knowledge and
skills necessary to the profession with the develop-
ment of humanistic values and ethics that enrich per-
sonal life. Thus, the University's emphasis for a liberal
education combines the professional with the cultural,
the practical with the ideal, and the functional with
the esthetic.
The University is located in the city of Bethlehem,
in the Lehigh Valley of eastern Pennsylvania. The

Copyright ChE Division ASEE 1989


CE sr

area, with a population of half a million, supports a
significant cultural life of its own as well as offering
easy access to the metropolitan environments of New
York and Philadelphia, and to the outdoor recreational
opportunities of the Pocono Mountains, the Delaware
River Basin, and the New Jersey Shore.
The University is situated on three adjoining cam-
puses covering 1,500 acres of South Mountain and the
neighboring valleys. The Chemical Engineering De-
partment is now based in the Tower Building of the
new Mountaintop Campus, a beautiful 700 acre site
along the summit of South Mountain.

Chemical engineering at Lehigh University
started as a program in the Department of Chemistry,
and the first chemical engineering degree was
awarded in 1907. By the early 1930's, some twenty to
thirty Bachelor degrees and three to four Masters de-
grees were being awarded each year in chemical en-
gineering. Distinguished faculty of the 1940's included
Darrell Mack, Vincent Uhl, and Harvey Neville. 1952
marked the beginning of the "new" program at
Lehigh. In that year chemical engineering was for-
mally recognized as an independent academic depart-
ment, and Leonard A. Wenzel and Alan S. Foust
joined the faculty, the latter to serve as its first chair-
man. In short order, Curtis W. Clump, Bryce Ander-
son, and Louis Maus also joined the department and
together with Foust and Wenzel began building the
modern department of today. That effort included
writing of the classic textbook Principles of Unit Op-
erations. In 1962, Leonard Wenzel became chairman
and oversaw the move of the department to the new
Whitaker Laboratory Building in 1965. By the time
Len left the chairmanship in 1983, the department had
won a place among the well-regarded chemical en-
gineering programs in the country, graduating some
sixty BS, twenty-eight MS, and two PhD's per year.
John C. Chen assumed the chairmanship in 1983 and,
with the current faculty, has continued to pursue en-
hanced quality in both the educational and research
programs of the department.

Along with the entire profession, our department
has undergone intense self-scrutiny and clarification
of objectives in the past six years. This was triggered
by a realization that today chemical engineering is
challenged by rapid technical developments, a great
variety of products and applications, emphasis on

higher value-added products, concerns with quality
and safety, and intense competitiveness in develop-
ment and production. Our response as an academic
department was to

* Affirm the importance of fundamentals in science,
mathematics, and engineering basics for both under-
graduate and graduate curricula
Nurture and develop students' "intellectual nimbleness,"
the ability to define problems, apply critical faculties, op-
timize solutions, integrate knowledge from multiple discip-
lines and work effectively in interpersonal relationships
Develop the very best research capabilities of international
stature in a few selected areas of chemical engineering.

In pursuit of the above goals, the following initia-
tives were taken.

Along with the entire profession, our department
has undergone intense self-scrutiny and clarification
of objectives in the past six years ... triggered
by ... [the challenge] of rapid technical developments,
the variety of products and applications .. emphasis on
higher value-added products, concerns with quality
and safety competitiveness in development .

Undergraduate curriculum A better-integ-
rated curriculum has been instituted which more effi-
ciently covers the fundamentals of chemistry, physics,
natural sciences, mathematics, and engineering sci-
ence, with room for a substantial amount of elective

Laboratory Instruction The old "unit operations
laboratory" had lost favor in the 60's and 70's for many
departments across the country. The importance of
hands-on laboratory experience in an engineering con-
text was reaffirmed, and we have just completed a
four-year development effort, at a cost of over $1 mil-
lion, to enhance both the physical facilities and the
instructional content of our undergraduate process en-
gineering laboratories. The fifteen new experiments
provide students with experience in both classical
technology (heat and mass transfer, thermodynamics,
distillation, etc.) as well as some of the advanced
technologies (membrane separation, digital process
control, bioengineering, etc.).

Undergraduate Research With sponsorship by
an educational foundation and a dozen companies, a
new program called Opportunity for Student Innova-
tion (OSI) was started in 1987. Teams of senior stu-
dents work with faculty advisors and industrial men-


tors on research projects that arise from real needs of
the industrial companies. This attempt to foster the
students' critical faculty for problem definition and
solution has generated enthusiastic interest and active
participation by students, faculty, and industrial

New Facilities Having outgrown its home of
twenty years in Whitaker Laboratory, the depart-
ment was moved to the newly acquired Mountaintop
Campus in the Summer of 1988. Offices, classrooms,
seminar rooms, and laboratories are all integrated ir
the 200,000 square feet Tower Building. An additional
10,000 square feet of engineering laboratory space is
also available to chemical engineering in a neighboring
pilot-plant building. For the first time in two decades,

Teams of senior students work with faculty
advisors and industrial mentors on research projects
that arise from real needs of the industrial companies...
This has generated enthusiastic interest and active
participation by students, faculty, and industry...

nearly all of the chemical engineering faculty and their
research programs are located together at a single
site. Campus-wide communications were also signifi-
cantly enhanced by a fiber-optic computer network.

Research is the heart of our department's graduate
activity. With the intention of concentrating in
selected areas, the faculty has developed focused
thrusts in bioprocessing, polymer science and en-
gineering, process modeling and control, and multi-
phase processing. Approximately a quarter of the fac-
ulty members are involved in each of these four areas.
The research in bioprocessing is focused on the op-
erations required for manufacture and isolation of
biological products. Faculty and students are cur-
rently investigating the fundamental kinetics of micro-
bial, enzyme, and mammalian cell systems, the design
and scale up of bioreactors, the development of on-line
instrumentation, and novel separation/purification
schemes for recovery of biologically active species.
These activities are coordinated through the BioPro-
-cessing Institute, directed by Janice A. Phillips, as a
part of Lehigh University's Center for Molecular Bio-
sciences and Biotechnology, directed by Arthur E.
The polymer program at Lehigh is an interdis-
ciplinary activity pursuing research in polymer col-
loids and polymer materials. The polymer colloids ac-

tivity is promoted by the Emulsion Polymers Insti-
tute, co-directed by John Vanderhoff and Mohamed
El-Aasser. Currently active projects pursue the prep-
aration of special monosize polymer particles, the mor-
phology of composite polymer particles, the kinetics,
transport phenomena, and modeling of emulsion
polymerization processes, the absorption of various
molecules on surface of latex particles, and the
phenomena of copolymerization and inverse emulsion
polymerization. The research activity in polymer col-
loids is strongly supported by an industrial consortium
of over fifty companies. Research on polymer mater-
ials has concentrated on multicomponent polymers.
Specific projects have studied interpenetrating net-
work composites, neutron scattering characterization
techniques, block copolymers, and the engineering
properties of polymeric materials.
Research in process modeling and control has the
objective of using advanced computer science to de-
velop novel approaches for dynamic modeling, simula-
tion, and control of industrial chemical processes. Ac-
tive projects include the modeling and control of batch
reactors, the design of nonlinear and multivariable
control structures, the design and control of energy-
conserving distillation systems, the development of
improved numerical integration methods, the use of
artificial intelligence in process control, and the appli-
cation of statistical control schemes. Activities in this
area are organized in a Center for Process Modeling
and Control, co-directed by Christos Georgakis and
William Luyben, and are supported by an industrial
consortium of a dozen companies.
While technical specializations are highly varied
within the multi-phase processing research activity,
the common theme is concern with interfacial
phenomena as found in multiphase systems. Faculty
interests reflect the wide range of industrial processes
dependent upon multiphase processing technology.
Active projects include the studies of plasma etching
of semiconductor materials, heterogeneous catalysts
for production of synthetic fuels, laser Raman spec-
troscopy to characterize surface oxides on substrates
for improved catalysts, phase equilibria of multicom-
ponent fluid mixtures, fluid mechanics of spouted beds
and the flow of granular materials, fluid mechanics
and heat transfer in both bubbling and circulating
fluidized beds, and multicomponent evaporation and
condensation. Much of the research is coordinated
through the Institute of Thermo-Fluid Engineering,
the Zettlemoyer Center for Surface Science, and the
Energy Research Center.
Due partly to the department's selective focus in


- Professor Fred Stein and
a graduate student measure
VLE of fluid mixtures.

Professor Christos Georgakis
confers with a group of grad-
uate students.

Professor John C. Chen
Department Chairman.

-> Professor Hugo S. Caram
inspects the research appa-
ratus of a graduate student.


the above four research areas, we are enjoying a
period of growth and effervescent enthusiasm. Since
1983, research funding has grown at an average an-
nual rate of over 30%, resulting in a research budget
of $3 million per year. The department's graduate edu-
cational program has seen a shift from the MS towards
the PhD program. In a five-year span, the fraction of
resident students studying for the doctoral degree has
increased from 30% to 70%, and the average number
of PhD degrees granted per year has increased from
4 to 14, ranking us, on this basis, among the top ten
departments in the U.S.
In the spring of 1989 the department faculty con-
sists of sixteen full-time faculty, three faculty with
joint appointments (with other departments), two ac-
tive emeritus professors, and one adjunct faculty.
What follows is a brief introduction to each of our
colleagues, in the chronological order of their joining
the Lehigh staff.
First on the scene were Leonard A. Wenzel and
Curtis W. Clump, who came from the University of
Michigan and Carnegie Institute of Technology in 1951
and 1954, respectively. Along with Alan Foust, Curt
and Len were instrumental in laying the foundation
for our department of today. In addition to their own
teaching and research efforts, each came to assume

major administrative responsibilities. In 1962 Len be-
came chairman of the department and held that posi-
tion for twenty-one years. Curt took on the respon-
sibilities of Associate Dean for Undergraduate Educa-
tion in the College of Engineering over the period of
1975 to 1988. Both retired as distinguished emeritus
professors but remain active in the department.
The sixties brought additional new blood, with two
former Lehigh undergraduates joining the depart-
ment. William E. Schiesser came in 1960, followed
by Fred P. Stein in 1963. Bill (now the R.L McCann
Professor) obtained his PhD at Princeton under the
late Leon Lapidus and brought with him an interest
in numerical analysis and computer methods that has
continued unabated to this day. Fred came from
graduate work at the University of Michigan and
brought an abiding interest in thermodynamics. In ad-
dition to the substantial responsibility of being the
associate chairman, Fred is now extending his work
on thermodynamics into state equations for electro-
lytes, reactive solution theory, and the effects of ther-
modynamic data uncertainty on process design.
Leslie H. Sperling and William L. Luyben came
from Duke and Delaware, respectively, via Buckeye
Cellulose Co. and Dupont, in 1967. The mechanical
properties of polymers and composites are Les's core
research interest. He applies his results to interpene-
trating polymer networks, sound and vibration damp-


ening, and to novel adhesives and binders. This is
explored at the molecular level with such techniques
as neutron scattering. Bill brought process control to
Lehigh. He has been extremely active in the analysis
of distillation processes and has added to the sophisti-
cated technology of what is currently the dominant
separation technique in the chemical industry. Bill has
written a well-recognized process control textbook
and more recently, in collaboration with Len Wenzel,
a sophomore text reflecting their personal philosophy
on undergraduate teaching. Les has also just pub-
lished a book on composites, reflecting the state of the
art in this exciting field.
Marvin Charles had completed his PhD research
in rheology at Brooklyn Polytechnic Institute when
he came in 1970. He joined forces with Bob Coughlin,
now at Connecticut, and developed what would be the
initial roots of the biotechnology effort at Lehigh.
While maintaining a New Yorker's attitude, Marvin
worries, in his words, about "identifying problems in-
hibiting development and scale up of bioprocesses and
solving them by understanding the basic biochemical
and engineering concepts."
John C. Chen, our current department chairman,
left a successful career at Brookhaven National Labs
to join the Mechanical Engineering Department in
1970. John came to this department in 1980 as the
Carl R. Anderson Professor of Chemical Engineering.
His original interests in heat transfer, started at
Michigan where he worked under S.W. Churchill,
have cut a wide swath in radiation and multiphase
processes. He has maintained a core activity in con-
vective boiling, but heat transfer in circulating and
bubbling fluidized beds and the cooling of electronic
circuits are also a significant part of his current in-
terests. John's research contributions have been rec-
ognized by both the AIChE and the ASME, with the
Melville Medal and the Kern Award, respectively.
Mohamed S. El-Aasser studied under Stan Mason
at McGill and came to Lehigh in 1970. Together with
John Vanderhoff and Gary Poehlein, now at Georgia
Tech, Mohamed was instrumental in the development
of the Emulsion Polymers Institute and is currently
its co-director. He is concerned with the formation,
stability, and polymerization of mini-emulsions and
the morphology of composite latex particles. With his
co-workers, Mohamed was involved in the preparation
of large monodisperse latex particles in the micrograv-
ity environment of the space shuttle. More recently
he has become interested in the surface modification
of latexes and their new intriguing applications in the

biotech-biomed areas.
The late seventies brought Hugo S. Caram (1977),
Cesar A. Silebi (1978), and Andrew Klein (1979).
Hugo was the first Minnesota PhD (studied under
Amundson) to join the department. With an initial in-
terest in reactor analysis, he has now moved to study
the flow of fluidized and granular media. Flow visuali-
zation and fiber optic probes are some of the tools in
these systems. Cesar is the only Lehigh PhD on our
faculty. He has expanded the work he started under
developed and expanded the work he started under
Anthony McHugh (now at the University of Illinois,
Urbana) on the separation of colloidal particles using
hydrodynamic chromatography and on the rheology
and coagulation of colloidal suspensions. Cesar's
basic research on separation and dispersion
mechanisms has generated new analytical methods
that are now used commercially. Andy, who did his
doctoral work at North Carolina State, left research
at GAF for Lehigh. Andy's research interests are in
the morphology of emulsion polymers and scale up of
mixing processes in colloidal systems. He is also in-
volved in the study of membranes with reduced gas
Rapid changes took place in the eighties. Arthur
E. Humphrey and Janice A. Phillips came in 1980
from the University of Pennsylvania. Art, a former
student of Elmer Gaden at Columbia and Dean of En-
gineering at Penn, became Lehigh's provost. A
member of the National Academy of Engineering, he
pioneered the field of biochemical engineering with
his well-known textbook, written with Aiba, being one
of the first to link traditional fermentation technology
with modern chemical engineering science. Having re-
turned full time to the department as the T.L. Dia-
mond Professor of Chemical Engineering, Art now
leads the Center of Molecular Biology and Biotechnol-
ogy. Art is interested in the "basics": fermenta-
tion modeling, monitoring and control, the new plas-
mid stability and plant cell culture; and in the
"applied": waste water treatment and waste utiliza-
tion. Students should be aware that graduate work
with Art includes strenuous hiking about his mountain
retreat in northern Pennsylvania. Janice, an avid run-
ner and a former student of Art Humphrey at Penn,
coordinates the graduate activities of the department
and directs the Bioprocessing Institute. Her three key
research areas are the use of Fourier Transform In-
frared Spectroscopy for continuous monitoring of fer-
mentations, the chemical engineering of mammalian
cell technology, and enzyme engineering. The FTIR


work requires the use of statistical methods to extract
information on concentration of the desired compo-
nents against the noisy backdrop provided by the
water spectrum. The mammalian cell work studies the
environmental factors controlling the productivity of
mammalian cell cultures. Janice is not only an active
research scientist (PYI awardee), but also an excel-
lent teacher, receiving the university's Robinson
Award in 1983.
While Matthew J. Reilly's main activities are in
the development of research programs at the univer-
sity level, he actively participates in the teaching of
undergraduate design courses and assists in the
supervision of graduate students in process modeling.
A student of Roger Schmitz at Illinois, and a former
faculty member at Carnegie-Mellon, Matt occupied
several positions with the National Academy of En-
gineering and the federal energy research program
before coming to Lehigh in 1982.
Christos Georgakis, another Minnesota student
(having studied with Aris-Amundson) joined the de-
partment in 1983. His research interests in process
control synergized with Bill Luyben's and blossomed
into an University-Industry NSF Research Center for
Process Modeling and Control. For all of the industrial
support, Christos' research remains thoroughly basic.
He is interested in nonlinear and multivariable control
and in the more exploratory tendency and expert con-
trol. Less traditional projects involve plant-wide con-
trol and statistical quality control in chemical proces-
Harvey G. Stenger studied under Charles Satter-
field at MIT and joined Lehigh in 1984. Harvey's in-
terests are in reaction engineering. He is working on
a variety of heterogeneous reacting systems, includ-
ing the processing of electronic materials, the use of
layered catalysts for NOx and sulfur removal in com-
bustion gases, and the modeling of food processes such
as the semibatch alkalinization of cacao products. Har-
vey was given Lehigh's Robinson Award as the out-
standing teacher in 1988 and currently chairs the de-
partment's Undergraduate Affairs Committee. Last,
but not least, he contributes a solid batting average
to the departmental softball team.
The last three years have seen the addition of
James T. Hsu and Israel E. Wachs. Jim had exten-
sive industrial experience in separations and catalysis
and after doctoral work with Joshua Dranoff at North-
western, came to Lehigh from Gulf Research and the
NSF in 1986. His current research on bioseparations
concentrates on the use of aqueous two-phase polymer
systems, and on selective precipitation and

The only certainty about the future is that it will be
challenging our emphasis on the fundamentals of
education, combined with opportunities to experience
applied engineering as well as innovative research,
will be of long-lasting benefit to our students.

chromatographic methods. More recently Jim has also
become involved in vaccine technology. Israel brings
into the department the tools of modern surface sci-
ence. After PhD work under Robert Maddix at Stan-
ford, he joined Exxon Research before coming to
Lehigh in 1987. He has used, among other techniques,
Raman spectra to elucidate the character of surface
oxides on substrates that are finding increasing appli-
cations for metal oxide catalysts, ceramic materials,
pigments, and electronic devices.
Important contributions to the depatmental oper-
ations are made also by Phillip A. Blythe and Eric
P. Salathe, who hold joint appointments in mechani-
cal engineering and mathematics, respectively. Phillip
works in diffusion and reaction and in the fluid
mechanics of melts used in the production of semicon-
ductor devices. Eric is interested in microcirculation
and in biomechanics. We could not close this descrip-
tion without mentioning William R. Hencke. Bill was
associate laboratory director at Texaco and his experi-
ence has been invaluable in the modernization of the
Unit Operations Laboratory, the teaching of the pro-
fessional development courses, and in the advising of
both graduate and undergraduate students.

The only certainty about the future is that it will
be challenging, both for our students and for our fac-
ulty. We feel that our emphasis on the fundamentals
of education, combined with opportunities to experi-
ence applied engineering as well as innovative re-
search, will be of long-lasting benefit to our students,
both graduate and undergraduate. We think that the
four areas of research selected for special attention by
the faculty (polymers, biotechnology, multi-phase pro-
cessing, and process modeling/control) are among the
most significant and fertile in the broad spectrum of
chemical engineering. Above all, we are convinced
that the attention paid to engineering science will per-
mit our department to respond to evolving technolog-
ical challenges. As a department our collective objec-
tive is to give our students the very best possible edu-
cation and to contribute significantly to the advance-
ment of chemical engineering science and practice. O


n educator




University of Utah
Salt Lake City, UT 48112

Laureate of Jell-O"? Indeed! Witness the follow-

The skinny young lady said "Hello!,
I'll fill my brassiere up with Jell-O!
The jiggle and shake
Will certainly make
A lure for some gullible fellow!"

Although most of Noel de Nevers' writing is seri-
ous and related mainly to chemical engineering, he
recently made an exception. His children dared him
to enter a contest for the title "Poet Laureate of Jell-
O" at the Last Annual Jell-O Salad Festival (Jell-O is
very big in Utah), sponsored by the Utah Holiday
Magazine; he went along with them and won with
three limericks and a quatrain. The above is the best
of the limericks. He also has three "de Nevers' laws"
in the most recent Murphy's Laws compilation, of
which the best is "de Nevers' law of debate" which
Copyright ChE Division ASEE 1989

states, "Two monologues do not make a dialogue."
Noel obtained his BS in chemical engineering in
1954 at Stanford University. Why chemical engineer-
ing? Two of his uncles were engineers-one a civil
engineer and one an electrical engineer. Noel was fas-
cinated by engineering but was also very interested
in chemistry. In looking through the general catalog
for Stanford, he discovered the field of chemical en-
gineering and figured it could be a good combination
of those two interests. Noel, although very serious
about his studies, was moderately active in student
affairs at Stanford, including one year as associate
editor of the humor magazine, The Chaparral.
Noel met Klara Nancy (Klancy) Clark there at
Stanford when they were both undergraduates work-
ing as "hashers" in the dormitories. Klancy changed
her name from Klara Nancy to Klancy when she ar-
rived on campus and discovered there were already
three other Nancy Clarks there, and she would have
been No. 4 (Klara was a family name which she never
used). They were married in 1955 and subsequently
produced three offspring: Their son Clark is a chemi-
cal engineer working for Hercules, Inc., making roc-
ket motors for intercontinental ballistic missiles; one
daughter, Renee, is finishing the PhD program at Col-



umbia University, seeking a career in arms control
and disarmament (those two cover both sides of the
street!); their other daughter, Nanette, is a senior
computer systems analyst for Burroughs/UNISYS.
Klancy has an MS degree in mathematics and works
for Project Technology Inc., teaching computer
software design.
Noel and Klancy like to travel, and if they were to
win a lottery that made them rich, the biggest change
in their lifestyle would be that they would take more,
longer, and more exotic vacation trips. Now that they
are through paying for their children' educations,
they do manage to take vacations to out-of-the-way
spots. They have trekked in the Himalayas, the
Andes, the Swiss and French Alps, and most recently
the Dolomites. In the past few years, Noel has
climbed Mt. Kilamanjaro and the Grand Teton. He
also enjoys hiking locally; he regularly leads hiking
trips for the Wasatch Mountain Club and the Salt
Lake Chapter of the Sierra Club. He has hiked exten-
sively in the nearby mountain areas-the Uintahs,
Wind Rivers, and Wasatch ranges-and in the deserts
of Southern Utah. One of the laws which Noel has
submitted for the next edition of Murphy's Laws is
"de Nevers' law of trail finding" which states, "When
you come to an unmarked trail fork, the most heavily
travelled fork is the dead end. Everyone who went
that way had to come back!"
Noel is also a regular tennis player and skier. He
feels he is mediocre in these sports, but that does not
prevent him from enjoying them. ("On a scale of 1 to
10, my tennis is about 3; 3s can have a lot of fun and
get a lot of exercise playing other 3s.") Each spring
Noel and Lamont Tyler, the department chairman,
challenge the senior class to a tennis match-not the
whole class, but two or four of the students who be-
lieve themselves good enough to beat the "old guys."
Over the last ten years, the fearsome duo of de Nevers
and Tyler has beaten the students nine times. The
students insist that in spite of their receiving the "Let-
the-Old-Men-Win-or-We'll-Never-Graduate" or "Old-
award at the senior luncheon in the spring, they do
give the tennis match their best shot.
Noel was born and raised in San Francisco and
lived in the Bay Area (except for his years at school)
until he was thirty. He was raised to believe that
civilization extended from the Golden Gate to the crest
of the Sierra Nevada Mountains; after that, all was
void and waste until one got to Paris. Noel does not
like to visit San Francisco these days because he re-
members how beautiful the Bay Area was when he
was growing up and the population was a third of what

it is now.
In 1954 and 1955, Noel had an opportunity to ob-
serve that civilization does exist beyond the Sierra; he
journeyed to Germany to study as a Fulbright ex-
change student at the Technical Institute in
Karlsruhe. Since he elected to hitchhike from San
Francisco to New York (after a brief stop in Aber-
deen, Washington, to bid a temporary farewell to the
girlfriend who later became his wife), Noel saw A
LOT of the United States. He further discovered that
there is civilization even in the Mid-West as a
graduate student at the University of Michigan from

Noel, entering into the spirit of things in Chincheros,

1955 to 1958 where he received the MS and PhD in
chemical engineering under the supervision of the late
Professor Joseph Martin.
In 1958, Noel returned to the Bay Area and
worked for the research subsidiary of what is now the
Chevron Oil Company (then Standard Oil Co. of
California) in process development, process design,
and secondary recovery of petroleum, at Richmond
and in La Habra, California, until 1963.
In 1963, Noel felt the time was ripe to make the
move to academia. The only academic opening in
chemical engineering in the Western US (where Noel
and Klancy preferred to remain) was at Utah, so he
applied, and in the fall of 1963, he became a faculty
member at the University of Utah in Salt Lake City.
Except for three summers and one year on leave, Noel
has been a full-time faculty member in the department
ever since, making the normal progression from Assis-
tant to Associate to Full Professor. For two years he
was the Associate Dean of the College of Engineering.
That stint as Associate Dean proved to be an effective
immunization against further academic administra-
tion; Noel finds the life of a non-administering profes-


One of the laws which Noel has submitted for the next edition of Murphy's Laws is "de Nevers' Law
of trail finding" which states, "When you come to an unmarked trail fork, the most heavily
travelled fork is the dead end. Everyone who went that way had to come back!,

sor more enjoyable and rewarding than that of an
academic administrator.
In the summer of 1964 he worked at the Atomic
Energy site (officially "National Reactor Testing Sta-
tion") west of Idaho Falls, Idaho, doing research on
technical problems concerned with reprocessing of
spent nuclear reactor fuels. And in the summer of 1968
he worked at a US Army research lab in Washington,
D.C., on a special weapons problem (apparently still
In the spring of 1971, for various reasons, Noel
thought it was a good time for him and his family to
get away for a year. He thought he had a Fulbright
lined up, but it fell through at the last minute. So he
wrote to all sorts of people looking for a one-year job.
One of his letters found its way to the Air Pollution
Technical Office of the EPA in Durham, NC. Noel
later found out that they had a long debate on the
topic, "Question: Can you get any useful work out of
a professor?" They concluded that the answer was
"No." But they were against their manpower ceiling
(although not their budget ceiling) so if they hired him
as a one-year temporary employee, it would help them
spend their budget so they could get more money next
year, which is absolutely necessary for federal bureau-
crats. The folks at EPA rationalized that even if Noel
just sat in a corner and twiddled his thumbs for the
year, they were better off than if he didn't come and
they had to turn back, unspent, the equivalent of his
When Noel arrived at EPA, they had little idea of
what to do with a professor, so they indeed sat him in
a corner with some reports to read. However, when
the boss asked him a simple technical question and
Noel replied with a two-page memo with the answer,
the boss was electrified: "Professors write memos!"
In the Federal Government, memos are important.
So for the rest of the year, when something came in
the door that no one had any idea what to do about,
they said, "Noel, write a position paper on this." It
was an exceedingly interesting and stimulating year
in which he delved into a wide variety of subtopics in
air pollution. Subsequently, he has written and con-
sulted on air pollution topics and has served for twelve
years on Utah's state air pollution control board (offi-
cially, the "Utah State Air Conservation Commit-
In addition to air pollution, Noel's research in-

terests are in fluid mechanics, thermodynamics, and
process safety and accident investigations. He has au-
thored two widely used textbooks, Fluid Mechanics
and Technology and Society, and has prepared widely
used teaching films entitled Phase Behavior. In addi-
tion to his academic work, he is regularly involved in
environmental regulation, and in 1988 he served on a
Utah Legislative Hazardous Waste Task Force.
In the summer of 1974, Noel was awarded a Ful-
bright faculty fellowship to teach air pollution at the
Universidad del Valle, in Cali, Colombia. He and his
family drove from Salt Lake City to Panama (which
one would have a hard time doing now) in a 1969
Dodge station wagon, which was then shipped to Co-
lombia where they travelled as widely as they could.
He developed his Spanish to a level at which he could
give suitable lectures in Spanish. The host diplomati-
cally said those lectures were "understandable, if not
grammatical." The de Nevers' family was able to
travel a great deal while Noel lectured, and Klancy
learned to act dumb (to lapse into garbled "Spanglish")
when asked for the appropriate papers on the car be-
cause they had been dated incorrectly upon their ar-
rival in Cali.

Noel feels that the permanent challenge in the profes-
sor business is to be broad without being shallow, and
to be deep without being narrow. The ideal professor
should be broad, but quite deep, in one or two areas.
Compared to the ideal, he feels he is broader than
most but maybe not deep enough in specific technical
areas, although his current consulting and research
work in propane fires and explosions is making him
quite deep in that area.
Noel is considered an unconventional teacher; if he
had his way, lectures would be banished outright from
universities. He never lectures if he can help it. "Lec-
turing is a sop to the ego of the faculty and the laziness
of the student. If I were dictator, I would forbid it
outright and fire any faculty member who regularly
did it." Putting five hundred freshmen in an au-
ditorium and having some professor tell them what it
says in the textbook is very inexpensive, but poor
education, according to Noel's philosophy. "The best
thing we can do for the students is to help them be-
come self-teachers and lifelong learners." The best


way to do that, he feels, is to tell them to read the
book and then to pose questions or problems based on
that reading and discuss them in class. This allows the
students to do their own intellectual work instead of
relying on the faculty to do it for them. It is easy to
teach that way in small engineering classes.
In Noel's courses, the class hour begins with sev-
eral students writing on the board their solutions to
the assigned homework problems, and the rest of the
class period consists of a discussion of those solutions.
When some of the students try unsuccessfully to work
the problems, there are lots of questions, and through
the discussion they find out why they had trouble. If
the students can all work the assigned problems, then
Noel changes the problems to more difficult ones and
sees if the students can figure them out on the spot.
It is harder to use this ("Socratic") procedure in
humanities and harder with big classes, but, in Noel's
opinion, it can be done. "It is like the ancient Chinese
proverb, 'If you give a man a fish, you have given him
a meal. If you teach him how to fish, you have given
him a way to get his meals for the rest of his life.'
Making students into self-teachers is like teaching
them to fish.
"I believe that learning is an active process. One
more ancient Chinese proverb (why are proverbs al-
ways ancient Chinese? Are we not making up any new
proverbs today?): 'Tell me, and I will forget. Show
me, and I will remember. Involve me, and I will un-
"Similarly, I think that learning goes on in the fol-
lowing way: 'From the known to the unknown, from
the simple to the complex, one step at a time.' I heard
that in a course for ski instructors, but I think it
applies equally well to learning engineering or any-
thing else."

"Noel is a big-city guy who fell in love with the
great outdoors," says one of his colleagues. Others
consider him the designated traveler for the depart-
ment. Shortly after returning from his excursions,
Noel prepares a slide presentation to share with in-
terested persons who can then experience his travels
vicariously. The slides are generally very good and
the narrative always lively. If he is interested in a
particular subject, in any of several fields, i.e., travel,
history, geography, religion, he endeavors to learn
enough about it to be conversant, if not an expert, on
the subject. Noel also keeps well informed on politics.
Utah is practically a small city-state so that anyone
interested in politics can easily get to know all the
elected and party officials. His politics are about "cen-

trist," which in Utah passes for liberal. He regularly
wins election bets because most of his colleagues and
friends are not as interested in politics as he is, and
they will bet on what they think ought to happen,
against what Noel thinks will happen. "When Noel
serves on the University Senate, we can rest assured
that the opinions of the College of Engineering will be
heard." He is not one to sit quietly and let things slide
Of himself, Noel says: "I have, alas, passed the
age at which I can be considered a child prodigy, or
even a promising young man. Two years ago, in the
middle of a University budget crisis, a special commit-
tee was elected to represent the interests of the entire
University faculty. By a coin toss following a tie vote,
I became its chairman. It seems clear that my col-
leagues consider me an elder statesman. I still don't
think of myself that way." D

book reviews

of the Art and Future Directions
Report on a AAAS Workshop and Symposium, (February 1988)
Mark S. Frankel, Editor
American Association for the Advancement of Science,
Washington, DC (1988)

Reviewed by
Mark E. Orazem
University of Florida

There is a growing awareness in our profession of
the need to expose students to the types of ethical or
moral decisions that they may face as professional engi-
neers. Our approach to introducing ethics at the Univer-
sity of Florida has been to make use of a series of case
studies published in Chemical Engineering.* We are al-
ways on the lookout for new material, and for this reason
I agreed to review this report on an AAAS workshop on
This book provides a report of a workshop, sup-
ported by the National Science Foundation, held on the
Continued on page 74.

**Philip M. Kohn and Roy V. Hughson, "Perplexing Prob-
lems in Engineering Ethics," Chemical Engineering, May 5,
1980; 97
*Roy V. Hughson and Philip M. Kohn, "Ethics," Chemical
Engineering, September 22, 1980; 132
*Jay Matley and Richard Greene, "Ethics of Health, Safety,
and Environment: What's 'Right'?" Chemical Engineering,
March 2, 1987; 40
-Jay Matley, Richard Greene, and Celeste McCauley, "Health,
Safety, and Environment: CE Readers Say What's 'Right',"
Chemical Engineering, September 28, 1987; 108


Random Thoughts...


7. Stan and Nathan

North Carolina State University
Raleigh, NC 27695

STAN AND NATHAN are juniors in chemical en-
gineering and roommates at a large midwestern
university. They are similar in many ways. Both enjoy
partying, midnight pizza runs, listening to rock, and
watching TV. Both did well in science and math in
high school, although Nathan's grades were consis-
tently higher. Both found their mass and energy bal-
ance course tough (although they agree the text was
superb), thermodynamics incomprehensible, English
boring, and other humanities courses useless. Both
have girl friends who occasionally accuse them of
being "too logical."
For all their similarities, however, they are funda-
mentally different. If single words were chosen to de-
scribe each of them, Stan's would be "practical" and
Nathan's would be "scholarly" (or spacyy," depending
on whom you ask). Stan is a mechanical wizard and is
constantly sought after by friends with ailing cars and
computers, while changing a light bulb is at the outer
limits of Nathan's mechanical ability. Stan notices his
surroundings, tends to know where he put things, and
remembers people he only met once; Nathan notices
very little around him, misplaces things constantly,
and may not recognize someone he has known for
years. Nathan subscribes to Scientific American and
reads science fiction and mystery novels voraciously;
Stan only reads when he has to. Stan has trouble fol-
lowing lectures; Nathan follows them easily, but when
instructors spend a lot of class time going through

If single words were chosen to describe them, Stan's
would be "practical" and Nathan's would be scholarly."
Stan is a mechanical wizard and is constantly
sought after by friends with ailing cars and computers,
while changing a light bulb is at the outer limits
of Nathan's mechanical ability.

Richard M. Felder is a professor of ChE at
N.C. State, where he has been since 1969. He
received his BChE at City College of C.U.N.Y.
and his PhD from Princeton. He has worked at
the A.E.R.E., Harwell, and Brookhaven Na-
tional Laboratory, and has presented courses
on chemical engineering principles, reactor
design, process optimization, and radioisotope
applications to various American and foreign
industries and institutions. He is coauthor of
the text Elementary Principles of Chemical
Processes (Wiley, 1986).

detailed derivations or homework assignments he al-
ready understands he gets bored and his attention
When Stan takes a test he reads the first problem,
reads it again, and if the test is open-book tries to find
an identical worked-out problem and copy the solu-
tion. If he can't find one, he searches for suitable for-
mulas to plug into. He frequently rereads the problem
while working on it and repeats each numerical calcu-
lation just to be on the safe side. When he has gone
as far as he can go he repeats the process on the sec-
ond problem. He usually runs out of time and gets
class average or lower on the test. Nathan reads test
problems only up to the point where he thinks he
knows how to proceed and then plunges in. He works
quickly and usually finishes early and gets high
grades. However, he sometimes blows tests because
he makes careless errors and lacks the patience to
check his calculations, or he fails to read a question
thoroughly enough and misses important data or an-
swers a different question than was asked.
The one place where Stan outshines Nathan
academically is the laboratory. Stan is sure-handed
and meticulous and seems to have an instinct for set-
ting up and running experiments, while Nathan rarely
gets anything to work right. Nathan almost had a
nervous breakdown in analytical chemistry: he would
repeat a quantitative analysis five times, get five com-
Copyright ChE Division ASEE 1989


pletely different results, and finally average the two
closest estimates and hope for the best. Stan, on the
other hand, would do the analysis twice, get almost
perfect agreement between the results, and head for
a victory soda while Nathan was still weighing out the
reagents for his second attempt.
Stan did well in only one non-laboratory engineer-
ing course. The instructor used a lot of visual demon-
strations-transparencies, pictures and diagrams, and
actual equipment; provided clear outlines of problem
solution procedures; and gave practical applications of
all theories and formulas the students were required
to learn. Stan claimed that it was the first course he
had taken that seemed to have anything to do with
the real world. Nathan thought the course was okay
but he could have done with a bit less plug-and-chug
on the homework.
Stan is a sensor; Nathan is an intuitor'. Sensors
favor information that comes in through their senses
and intuitors favor internally-generated information
(memory, conjecture, interpretation). Sensors are at-
tentive to details and don't like abstract concepts; in-
tuitors can handle abstraction and are bored by de-
tails. A student who complains about things having
nothing to do with the real world is almost certainly
a sensor. Sensors like well-defined problems that can
be solved by standard methods; intuitors prefer prob-
lems that call for innovation. Individuals of both types
may be excellent engineers: the observant and
methodical sensors tend to be good experimentalists
and plant engineers, and the insightful and innovative
intuitors tend to be good theoreticians, designers, and
The degree to which someone favors sensing or
intuition can be determined with the Myers-Briggs
Type Indicator, a personality inventory that has been
administered to hundreds of thousands of people in-

'See R. M. Felder and L. K. Silverman, "Learning and Teaching
Styles in Engineering Education," Engineering Education
78(7),674(1988), and G. Lawrence, People Types and Tiger Stripes,
Center for Applications of Psychological Type, 2nd Edition, Gaines-
ville, FL, 1982. Stan is a representative sensor and Nathan a repre-
sentative intuitor, but not all sensors are just like Stan and not all
intuitors are just like Nathan. Sensation and intuition are prefer-
ences, not clear-cut categories, and all human beings exhibit charac-
teristics of both types to different degrees.

eluding many engineering students and faculty mem-
bers. More than half of all undergraduate engineering
students tested have been found to be sensors while
most engineering professors are intuitors. A mis-
match thus exists between the teaching styles of most
professors, who emphasize basic principles,
mathematical models and thought problems, and the
learning styles of many undergraduates, who favor
observable phenomena, hard facts, and problems with
well-defined solution methods. Intuitive students
would consequently be expected to enjoy a clear ad-
vantage in school, and indeed intuitors have been
found to get consistently higher grades except in
courses that emphasize facts, experimentation, and
repetitive calculations.
For many sensing students, the disparity between
the way they learn best and the way they are gener-
ally taught is too great: they get poor grades no mat-
ter how hard they work, become disillusioned, and
drop out. Felder and Silverman' give several ways
instructors can accommodate the learning styles of
these students without compromising their own teach-
ing styles or their ability to get through the syllabus.
The accommodation is well worth attempting: sensors
are sorely needed in industry and may do exception-
ally well there if they manage to survive school.
Postscript: 15 years later. Nathan graduated
magna cum laude, went to graduate school and got a
PhD, worked for several years in the research and
development division of a major chemical company,
got several important patents, moved to manufactur-
ing, and ended up as a group leader supervising a
team of designers and systems analysts. Stan strug-
gled through the curriculum, graduated in the bottom
third of his class, and got a production engineering job
in the same company Nathan went to work for. His
mechanical talents soon became apparent and he was
put in charge of a trouble-shooting team that came to
be in great demand throughout the plant. His manage-
rial skills then led to a rapid series of promotions cul-
minating in his becoming the youngest corporate vice
president in company history. Among the thousands
of employees in the branch he heads is Nathan, with
whom he gets together occasionally to talk over old
times. Stan thoroughly enjoys these meetings; Nathan
also enjoys them but perhaps not as much. O


Each year Chemical Engineering Education publishes a special fall issue devoted to graduate education. It consists of 1)
articles on graduate courses and research, written by professors at various universities, and 2) ads placed by chemical
engineering departments describing their graduate programs. Anyone interested in contributing to the editorial content of the
1989 fall issue should write to the editor, indicating the subject of the contribution and the tentative date it can be submitted.
Deadline is June 1st.





University of Alabama
Tuscaloosa, AL 33487-0203

NCORPORATING HEALTH, safety, environmental,
and ethical issues (HSE&E) into the chemical en-
gineering curriculum has become an important topic
[1, 2], reflecting the chemical process industry's grow-
ing concern over these issues. This paper reports the
results of a survey of U.S. chemical engineering de-
partments on this matter and some details of what we
are doing at the University of Alabama.
Most educators probably agree that HSE&E needs
to be taught. But what is the best way to do it? Many
schools include some of this type of training in the
capstone senior design course (see ref. 3 for an exam-
ple), but is there enough time to adequately cover the
topic there? Some offer an elective HSE&E course,
but with our overcrowded curriculums many schools
cannot justify that approach. Also, when the course is
an elective, not all ChE students will be trained.
Other schools prefer to coordinate HSE&E training
through examples and homework problems in the core
ChE courses, but coordination of any topic throughout
a curriculum is very difficult and requires the diligent
effort of a designated coordinator and the full support
of the department. Another problem is that several
important HSE&E topics are unsuitable for inclusion
in existing courses.
What are U.S. chemical engineering programs ac-
tually doing, or planning to do, at this moment? ABET
recently polled all engineering programs concerning
their teaching of occupational, public, and product
safety and health [4]. The results were broken down
according to disciplines so that the status of chemical

The majority of schools lean toward
incorporating HSE&E into the existing core courses,
and the most popular courses seem to be the capstone
design course and the laboratory.

Alan M. Lane is an assistant professor
at the University of Alabama, where he
teaches the course "Health and Safety in
the CPI." He received two BS degrees, in
chemistry and chemical engineering, from
the University of Washington (1977) and a
PhD in chemical engineering from the Uni-
versity of Massachusetts (1984). His re-
search is in the area of kinetics and hetero-
geneous catalysis.

compared to the other engineering disciplines could
be seen. However, the information wasn't very specif-
ic, and it did not cover environmental and ethical con-
cerns. The present survey is an attempt to provide
information for gauging the chemical engineering dis-
cipline's success in this area and to provide concrete
help for incorporating HSE&E into the curriculum.

The survey was designed to find out what chemical
engineering programs are actually doing, or planning
to do, about teaching HSE&E issues. The questions
were intentionally broad so that respondents could be
free to define their own concept of HSE&E content.
As a result, my interpretation of the data must be
somewhat subjective, and I will try to point out the
subjective comments. An example is the question of
what constitutes a coordinated effort to incorporate
HSE&E into the curriculum. Simple agreement at a
faculty meeting does not guarantee any effort at all,
but how do we know if a formal coordination plan is
or is not in place? I had to interpret this based on the
individual response.
The survey was sent in the fall of 1987 to the 155
U.S. departments listed in the Chemical Engineering
Faculties Directory, and 54 (35%) of the schools re-
sponded. Since schools with an ongoing HSE&E con-
cern might be more likely to respond, and since my
interpretation is subjective, I will make no claim as to
Copyright ChE Division ASEE 1989


a margin of error for this survey. I hope that the re-
sults do accurately reflect the general trends in chem-
ical engineering HSE&E education and that they pro-
vide some useful ideas for incorporating HSE&E into
your curriculum.


The questions are presented below as they ap-
peared on the survey. Only the fourth question was
multiple choice.
1. Does your department offer a ChE course with the major
focus being health, safety, environmental, or ethical is-
sues? If yes, please list the courses with a brief description.

36 (67%) claimed no ChE course focused on these issues.
18 (33%) offered separate courses on one or some
HSE&E issues with pollution control being the most
common. 7 of the 18 offered a comprehensive HSE&E
course which appeared to cover at least three of the four

2. Does your department have a coordinated effort to in-
clude health, safety, environmental, or ethical issues in
your ChE core courses (for example, through homework
problems or design experiences)? If yes, please briefy de-
scribe the program.

31 (57%) have no coordinated effort, although 10 of
these 31 indicated an informal attempt to incorporate
HSE&E topics. 23 (43%) do claim a coordinated effort to
incorporate HSE&E into various courses, with the cap-
stone design course being the most common, followed
closely by the laboratory course. Other courses men-
tioned were seminar, reactor design, and separations. 5
of the 23 indicated a coordinated effort throughout most
of the core courses.

3. Does your department have specific plans to incorporate
these topics into the curriculum within the next five years?
If yes, please briefly describe the plans.

10 (19%) plan to modify their curriculum in some way
to include some or more HSE&E content. The plans
ranged from inclusion of HSE&E in the capstone design
course to creation of an elective HSE&E course. 44
(81%) have no plans to do anything different, but many
of these already are making significant efforts.

4. Is there a consensus within your department whether
such topics are best:
a. included as a separate course (required or elective)?
5 (9%)
b. coordinated as problems within the existing courses?
18 (33%)
c. left for industrial training?
2 (4%)
d. no real consensus.
29 (54%)

Some responses were split between two options
and were counted as half for each answer. Several
participants expressed personal opinions but indicated
that there was no departmental consensus.

[HSE&E] is far too important a topic ... [for] a "hit or miss"
incorporation in the core curriculum ... the student must
be introduced to the concept of making socially responsible
professional decisions in addition to being trained .
on how to design a properly-sized relief valve.

The majority of schools-whether by deed, plans,
or simply opinion-lean toward incorporating HSE&E
into the existing core courses, and the most popular
courses seem to be the capstone design course and the
laboratory. Not many actually incorporate it through-
out the curriculum. Only a handful offer or are plan-
ning to offer a comprehensive HSE&E course.
Perhaps the most surprising result is that most
departments do not plan to increase the HSE&E con-
tent of their curriculum. Of course, many already have
some HSE&E content, but in my opinion at least half
of those which do not intend to increase HSE&E con-
tent currently have insufficient coverage to meet the
spirit of ABET HSE&E criteria.


The most popular option for teaching HSE&E is
by incorporating it into the capstone design course.
Several schools (for example, the University of
Washington) dedicate several of the initial design lec-
tures to specific HSE&E topics, and at the University
of New Mexico weekly 15-minute mini-lectures on
HSE&E topics are interspersed in the design class
[3]. An HSE&E section is required in the design re-
ports of other schools.
The unit operations laboratory is also a popular
class in which to teach safety. At one university, the
school's health and safety office lectures the students
on safety and then provides a competency test before
the laboratory course can proceed.
Probably the hardest option (but maybe the best)
is to incorporate HSE&E throughout the curriculum.
At the Massachusetts Institute of Technology plans
are being considered to reorganize several core
courses around case studies that place emphasis on
HSE&E concerns. The University of Arkansas, under
contract with the Center for Chemical Process Safety,
has prepared a collection of HSE&E problems for a
variety of ChE core courses. Marvin Fleishman has
also recommended HSE&E topics that could be incor-
porated in several ChE core courses [2].
A number of schools offer dedicated courses on
HSE&E topics. Some of these are "single-topic"
courses like pollution control or engineering ethics.
Several others offer a course which covers some com-


bination of HSE&E topics. The most popular topics
seem to be those that cover occupational health, per-
sonal safety, and loss prevention. Ethics is sometimes
included explicitly and is most probably implicitly co-
vered. The course contents are not uniform, are
rapidly evolving, and several syllabi are being used.
An interesting technique used in the HSE&E course
at Rutgers University is the requirement of a term
paper analyzing a chemical process from raw materials
handling through the chemical process itself, to prod-
uct distribution and to ultimate disposal. This reflects
the current "cradle to grave" responsibility of chemi-
cal producers for their products.
Some schools have made use of guest lecturers
from industry or government agencies and have vid-
eotaped the lectures for future use. NIOSH and
OSHA lectures were videotaped at West Virginia
University [5], and five 2-hour lectures were telecast
to Wayne State University from BASF corporation
on a variety of HSE&E topics [6]. The latter are being
prepared as a study guide to be sold through the
AIChE. Many schools regularly include a speaker on
HSE&E issues in their graduate seminar.


In the spring semester of 1988 we offered, for the
first time, an elective course entitled "Health and
Safety in the CPI," a survey of safety (both personal
and loss prevention), health, environmental, and ethi-
cal issues. It is intended for chemical engineering and
chemistry students, although we also hope to attract
students from other technological fields. The course
description reads:

Historical, legislative, and technical aspects of safety,
health, environmental, and ethical issues. Develop skills to
assess, design to prevent, and mitigate health and safety
problems in the chemical process industry.

Why try to teach all this is one course? A student
should be introduced to all four subjects in order to
be prepared for responsible professional decisions, but
the subjects weren't being adequately covered, and
we only had room for one more elective course. The
subjects group together naturally, having a common
feature; they all have aspects which are reasonably
hard to quantify and involve some subjective thinking.
It is unrealistic to expect to develop expertise in
any specific topic and still cover such a broad array of
subjects. For instance, we discuss hazard and opera-
bility (HAZOP) analysis and go through a practice
problem, but leave detailed training in HAZOP
analysis for industrial employers. Student surveys in-

dicated that most students were confronted with these
issues for the first time in the course and that their
awareness was radically increased, indicating that the
course accomplished my primary goals.
The syllabus for the course is shown in Table 1. A
variety of teaching methods and materials are used,

Course Syllabus

1. Introduction
A Introductory lecture: The Engineer and Society 1
B "Technology and the Law," OSHA lecture taped at 1
West Virginia University: discussion
C Acceptable Risks, ABC movie; discussion 2

2. Safety
A Personal Safety
1. General discussion; HAZCOM and Kletz's "What 1
Went Wrong?" as guides
2. Lecture by Safety Director from Hunt Oil 1
3. Laboratory safety movies; discussion 2
4. Actual laboratory inspection of University Labs; 2
discussion of inspection reports
B Loss Prevention
1. Types of accidents; Kletz's "What Went Wrong?" 2
2. Prevention technology pressure relief devices, plant 1
layout, fail-safe systems, etc.
3. IChemE case study slide shows; discussion; students 2
try to figure out how accidents happened
C Hazard Analysis; Center for Chemical Process Safety 2
material; analyze chemical processes, predict potential
problems, suggest preventative measures

3. Health
A Government regulations; OSHA and NIOSH lectures 1
taped at West Virginia University
B Toxicology; Carcinogens, Anticarcinogens, and Risk 1
Assessment, video tape by Professor Ames (UC-Berkeley)
for the Council for Chemical Research
C Prevention technology; process, isolation, protection 1
D Case studies: asbestos, vinyl chloride, benzene, etc. 2
E Wrath of Grapes, United Farm Worker's video on 1
pesticide abuse; discussion; critical analysis of
information given

4. Environment
A Government regulations; EPA, Superfund, etc. 1
B Types of pollution; air, water, ground water, land 1
C Pollution technology; aerobic digestion, incineration, 2
scrubbers, etc.
D Case studies: Willamette river cleanup, Rhine River 1-2
spill, Monongehela River spill
E Silent Spring / Silent Spring Revisited: discussion 1-2

5. Ethics
A Engineering codes of conduct and introduction 1
B Selected readings from The Ethics Reader; discussion 1
C Chemical Engineering ethics surveys; discussion 2

6. Term Project Reports a
Note: As a second-time course this syllabus will certainly be modified
throughout the semester: Please give me input on the course content. I
welcome your comments!


Course Resources

Hearl, F. J., P. E., Technology and the Law, NIOSH seminar
videotaped at West Virginia University, loaned by Professor
Wallace B. Whiting
Acceptable Risks, ABC-TV movie originally broadcast on Sunday,
March 2, 1986

Kletz, T. A., What Went Wrong: Case Histories of Process Plant
Disasters, Gulf Pub. Co., Houston, 1985
Lees, F. P., Loss Prevention in the Process Industries,
Butterworths, Boston, 1986
"Guidelines for Hazard Evaluation Procedures," Center for
Chemical Process Safety by Batelle Columbus Division, AIChE,
New York, 1985
Wadden, R. A., and P. A. Scheff, Engineering Design for the
Control of Workplace Hazards, McGraw-Hill, New York, 1987
"Loss Prevention," Chemical Engineering Progress Technical
Manual, AIChE, New York, various issues
Whitmyre, G., and R. L. Long, "Guide to Safety in the Laboratory
for Chemical Engineers," New Mexico State University, 1987
Stull, D. R., "Fundamentals of Fire and Explosion," AIChE
Monograph Series, 10, (73), 1977
Hazard Workshop Modules: Fires and Explosions, training slide
show prepared by IChemE, 1987
"Loss Prevention Bulletin," IChemE, various issues

A variety of standard industrial hygiene texts
Fighting Workplace Cancer, United Auto Workers, slide tape
Silverstein, M., M.D., "The Case of the Workplace Killers: A
Manual for Cancer Detectives on the Job," United Auto Workers,
"Current Intelligence Bulletin," NIOSH, various issues
Ames, B., Carcinogens, Anticarcinogens, and Risk Assessment,
videotape for the Council for Chemical Research, 1987
Wrath of Grapes, videotape by the United Farm Workers

A variety of standard pollution control engineering texts
Hanna, S. R., and P. J. Drivas, Vapor Cloud Dispersion Models,
Center for Chemical Process Safety, AIChE, New York, 1987
Myhre, R., Double Alkali Flue Gas Desulfurization: The CIPS
Experience, Engineering Case Library, Washington Internships
for Students of Engineering Program, 1983
Carson, R., Silent Spring, Houghton Miffin, Boston, 1962
Marco, G. L., R. M. Hollingworth, and W. Durham, Eds., Silent
Spring Revisited, ACS, Washington, DC, 1987

* Flores, A., ed., Ethical Problems in Engineering, Vol. 1, The Center
for the Study of the Human Dimensions of Science and
Technology, Troy, NY, 1980
Baum, R. J., ed., Ethical Problems in Engineering, Vol. 2, The
Center for the Study of the Human Dimensions of Science and
Technology, Troy, NY, 1980
"Suggested Guidelines for UsE With the Fundamental Canons of
Ethics," Accreditation Board for Engineering and Technology,
New York, 1985
Vesilind, P. A., "Rules, Ethics and Morals in Engineering
Education," Eng. Ed., 289, February, 1988
Berube, B. G., "A Whistle-Blower's Perspective of Ethics in
Engineering," Eng. Ed., 294, February, 1988
Matley, J., and R. Greene, "Ethics of Health, Safety and
Environment: What's Right?" Chem. Eng., 40, March 2, 1987

including traditional lectures, discussion groups, video
tapes, slide shows, guest speakers, and field trips.
Resources are widely scattered but available. Some
resources that I use are listed in Table 2. Some of
them are traditional (from the AIChE, IChemE,
CCPS, etc.), and some are more non-traditional. The
latter include the ABC movie, Acceptable Risks, and
the United Farm Worker's documentary, Wrath of
Grapes. These films impose a dramatic and emotional
element to safety and health discussions, as Silent
Spring, by Rachel Carson, does to the environmental
issue. This is entirely appropriate and results in re-
markable classroom discussions.
We cannot expect every student to receive
HSE&E training with this effort alone since this is an
elective course. Therefore, we initiated a coordinated
effort to intersperse HSE&E training throughout the
entire chemical engineering core curriculum. The pri-
mary tool was the CCPS example problems compiled
at the University of Arkansas, but not many of the
problems were actually used the first time around.
One benefit of this survey was obtaining new and di-
verse ideas from my colleagues for accomplishing the
HSE&E incorporation.


I sensed a general agreement that the university
has a responsibility to provide some training in
HSE&E issues. It is far too important a topic to rele-
gate to a few lectures in the capstone design course
or a "hit or miss" incorporation in the core curriculum.
It is also more than a strictly technological topic; the
student must be introduced to the concept of making
socially responsible professional decisions in addition
to being trained, for example, on how to design a prop-
erly-sized relief valve.
I believe we will eventually see the need for a re-
quired HSE&E course. Most present HSE&E offer-
ings are elective and so by definition do not meet this
need for all students. The scope and content of the
HSE&E course will evolve but there are too many
important topics that cannot be adequately covered
within another course. How this HSE&E course will
fit into a crowded curriculum will be a hotly debated
Incorporating HSE&E topics within the core cur-
riculum should be a concurrent activity. This will
gradually come as more faculty are impressed with
the need to teach HSE&E and as more resources spe-
cific to the various core courses become available. To
facilitate the incorporation, each department should
identify a dedicated individual or committee to con-
tinuously coordinate the topics taught, collect and dis-


seminate resource material to the faculty, and to
monitor progress.


I thank my department chairman, Dr. Marvin
McKinley, for helping develop our HSE&E course and
providing enthusiastic support for this project. I also
thank my fifty-four colleagues who took the time to
complete the survey.

1. Talty, J. T., "Integrating Safety and Health Issues into
Engineering School Curricula," Chem. Eng. Prog., 82,
2. Fleischman, M., "Rationale for Incorporating Health
and Safety into the Curriculum," Chem. Eng. Ed., 22, 30
3. Kauffman, D., "Health, Safety, and Loss Control Topics
in the Senior Design Courses," Plant/Operations Prog.,
6, 73(1987)
4. Accreditation Board for Engineering and Technology
(ABET) Occupational Safety and Health Study, Sub-
Task 3 of NIOSH P.O. No. 84-2653, Sept. 11, 1986
5. Whiting, W. B., W. E. Wallace, J. F. Gamble, F. J.
Hearl, L. Piacitelli, E. Regad, and R. Ronk,
"Introducing Engineering Students to Health and Safety
Aspects of Their Profession," Proceedings of the 1986
Frontiers in Education Conference, Arlington, TX., p.
30, October 1986
6. Crowl, D.A., and J. F. Louvar, "Safety and Loss Pre-
vention in the Undergraduate Curriculum," Chem.
Eng. Ed., 22, 74 (1988) 0

Continued from page 67.
state of the art and future directions of ethics in engi-
neering and sciences. There is very little of substance in
this report that could be useful in teaching. One author
reports a brief personal code of ethics attributed to John
Last of the Canadian Journal of Public Health:
Be honest.
Be truthful
Be fair to collaborators.
Uphold the honor, dignity, and credibility of your field.
Act and write in the public interest.
Save trees

This quote might provide an interesting springboard
for classroom discussions of the meaning and utility of
engineering codes of ethics. Some vague suggestions
were made on changes needed in corporate or public
policy, but, in general, these comments were limited to
identification of the problems; specifics on what the
changes should be and how such changes could be im-
plemented were not addressed.
The majority of the material was written by partici-
pants in this field, for participants in this field, and in the
jargon of this field. The symposium papers submitted

deal primarily with problems of defining the structure of
this area, and therefore provide little of use to technical
personnel. It is interesting to note that the major chal-
lenges in this field were identified to be: 1) the introduc-
tion of EVS (Ethics and Values Studies) into technical ed-
ucation; 2) the need to have EVS evolve from a passive
role to an active role (i.e., transition from conducting im-
pact studies to influencing public policy); and 3) the need
to obtain more funding for research. One of the laudable
goals identified for education by one contributor is the
collection of educational materials that would emphasize
development of critical thinking and that could be used
easily in grades K-12 as well as in universities.
This is a profoundly disturbing collection of papers
and working group reports because it reveals an entire
field devoted to ethics in science and engineering, funded
by NSF, but dominated by a group of people who exhibit
no knowledge of engineering and science or of how tech-
nical people work within the corporate structure. I found
it disturbing that none of the participants addressed the
extent to which decisions on application of technology
are made by people who do not have technical training, a
critical omission when studying the ethics of technology
in a society so dominated by profit as "the bottom line."
The comments of some of the contributors reflect a sur-
prising bias against the technical fields they are studying.
The following excerpt from a section discussing the need
for new teaching methodology provides an example
(emphasis is mine):

There needs to be more creative approaches to the dis-
semination of EVS/STS (Ethics and Values Stud-
ies/studies in Science, Technology, and Society). One
of the most troublesome aspects of EVS/STS dissemina-
tion has to do with college teaching. In many cases,
philosophy departments send their youngest and least
experienced faculty to tell students in science and en-
gineering how to be good people. Often those faculty
have no idea what the real problems of the field are;
worse, they proceed to brand the particular scientific or
engineering field as a social evil. They are
unprepared to address the real ethical issues in the field
or to help students with ethical problem solving. It does
no good to tell people that their field is bad without
showing them practical ways to improve practice in
their field.
Of course, no field, including those in the sciences
and engineering, is inherently bad. Comments like these,
made by a professor in a psychology department, reflect
a profound lack of understanding of the nature of engi-
neering and science. Such comments also underscore the
need for a greater activity by our professional societies
(e.g., AIChE) in the area of public policy. The develop-
ment of the field of ethics and value studies in science and
engineering in departments of philosophy, psychology,
and/or social sciences is, in part, a response to the vac-
uum caused by the reluctance of technical people to get
involved in ethical issues. It is vital that leadership in this
area be provided by engineers and scientists who can be
knowledgeable in both the technical and the managerial
aspects of the problem. 0


n letters


To The Editor:

A while back (Summer 1988 issue), I wrote a letter to this
column which pointed out the wide difference in the cost of
two for-profit mainline chemical engineering journals,
CEC and CES. In your last issue (Winter 1989) Mr. Gordon,
chairman of Gordon and Breach, publishers of CEC, in a
long letter said that my analysis was "incorrect in just about
every respect imaginable." I am sorry to have to return to
this matter but I am impelled to do so because I do not think
that I am wrong and I believe that the facts support my con-
cerns. I have a few brief comments in response to Mr. Gor-
don's letter.
1. Of course Mr. Gordon's figures and mine are com-
pletely different. He quotes 1988 prices but my comparison
was not for 1988! In my letter I clearly stated that I was com-
paring December 1987 figures which were the only ones
available when I wrote the letter. The numbers given by Mr.
Gordon are not pertinent and are not correct for the period
referred to in my letter.
2. Only one of the numbers in my comparison of journals
may be in question, and that is the cost for the December 1987
issue of CES.Since journals are bought by the volume, and




Texts from


since $435.00 was the price of the 1987 volume, including the
December issue, this was the figure I used in my calcula-
tions. CES did raise its advertised price during the year to
$500/volume, but that would not affect the buyer of the 1987
volume. I think that $435 is the correct figure to use, however
even if one takes the higher figure this would mean the CEC
would cost about 10 times as much as CES, instead of 11
times. Whether 10 or 11, the point of my letter remains un-
changed in that the pricing of technical journals is
3. Mr. Gordon brings up a number of other matters...the
color plates in CEC, my alleged connection to CES, the vol-
umes of CEC which contain as many as 1000 pages, etc. Reg-
ular readers of CEC may be as puzzled as I am about the
above statements.
4. Finally, on a more general note: it is evident that the
forces of the marketplace do not apply when it comes to the
pricing of technical journals. In the long run this is harm-
ful to our profession and this concerns me. The first step in
redressing this situation is to know the facts. Therefore, I
would like to propose that CEE make and publish a survey
every now and then of the costs of the mainline chemical
engineering journals. I think that this would be worthwhile
since it would be most enlightening and helpful to us

Octave Levenspiel
Oregon State University

Stanley I. Sander, The University of Delaware
0-471-83050-X, 656pp., Cloth, AvailableJanuary 1989
A fully revised new edition of the well received sophomore/junior level thermo-
dynamics text, now incorporating microcomputer programs.

Dale E. Seborg, University of California, Santa Barbara,
Thomas R. Edgar, University of Texas, Austin,
and Duncan A. Mellichamp, University of California,
Santa Barbara
0-471-86389-0,840pp., Cloth, Available February 1989
A balanced, in-depth treatment of the central issues in process control, including
numerous worked examples and exercises.

Contact your local Wiley representative or write on your school's stationery to
Angelica DiDia, Dept 9-0264, John Wiley & Sons, Inc, 605 Third Avenue, New York,
NY 10158 Please include your name, the name of your course and its enrollment,
and the title of your current text. IN CANADA: write to John Wiley & Sons Canada
Ltd., 22 Worcester Road, Rexdale, Ontario, M9W ILl.

605 Third Avenue
New York, NY 10158







A Class Problem on Coal Methanation

The Pennsylvania State University
University Park, PA 16802

E QUILIBRIA OF MULTIPLE and heterogeneous
chemical reactions are accorded only a rather
cursory treatment in most textbooks on ther-
modynamics and reaction engineering. Yet problems
of this kind are frequent in practice. Moreover, the
textbook methods involve extensive calculations that
require a computer if three or more reactions are in-
The purpose of this article is to point out a differ-
ent and much simpler approach that can be taken in
many practical situations. The problem is especially
suited for the undergraduate classroom in that it ac-
quaints the student not only with the topic im-
mediately at hand, but also introduces him to a widely
applicable technique of problem solving in chemical
engineering practice which is largely unrealized in un-
dergraduate textbooks.
In my experience, the message is delivered most
effectively in a setting where the class plays the role
of a development group in a fictional major industrial
company. The description that follows is along such

The Vice President of Research and Development
explains that the company has acquired major coal

Friedrich G. Helfferich is professor
of chemical engineering at Penn State. He
is a native of Germany and received chem-
istry degrees from the Universities of Ham-
burg and Gottingen. He is author of books
on ion exchange and chromatography, and
is founder and editor-in-chief of the journal
Reactive Polymers. Current interests of his
are reaction kinetics, ion exchange, dy-
namics of multicomponent systems, and
windsurfing, but his true love is teaching.

Standard Free Energies and Enthalpies of
Formation of Gaseous Participants
from Elements at 298.15 K, in kcal/mol
(from Hill [1], Appendix A)


- 32.8077
- 94.2598
- 12.140


- 57.7979
- 26.4157
- 94.0518
- 17.889

leases as a hedge against the day when oil and gas
reserves will dwindle. However, to serve a technology
that has been nursed on fluid fuels, much of that coal
will have to be liquefied or gasified. In the context of
a preliminary feasibility study, our group receives an
assignment to evaluate the thermodynamics of coal
methanation. Specifically, the question of whether and
under what conditions 90% of the coal can be con-
verted to methane (as opposed to oxides of carbon)
should be answered.
For the classroom the problem is simplified and
dressed up as follows. Coal is regarded as elementary
carbon. Only the three main reactions are to be consid-

C+H2 0-CO+H2
CO + 3H2 -* CH4 + H,0
CO+H2 0 -CO2 +H2

The starting materials are carbon, water, and, if
needed, hydrogen. All potential catalysts catalyze all
three reactions, so they cannot be conducted in sepa-
rate reactors. All reactants except coal should be
gaseous. A minimum temperature of 550 K is required
for reasonable catalyst activity. High temperatures
and pressures, as well as the presence of liquid water,
are undesirable because of cost and corrosion prob-
E Division ASEE 1989



lems. For the purpose at hand, calculations which are
based on ideal gas behavior and temperature-inde-
pendent standard enthalpy changes are acceptable. A
strict and short deadline is set for the presentation of
conclusions to management.

The task at hand now is to find
what sets, if any, of operating variables ...
will produce the desired 90% equilibrium yield to
methane, basis carbon reacted (i.e., 0.9 moles of
methane produced per mole of carbon reacted).


To obtain an idea of the system, an obvious first
step is to calculate and plot the equilibrium constants
of the three reactions as a function of temperature.
This calls for the AG and AH values of the reactions,
readily calculated from tabulated thermochemical data
(see Table 1) by the standard procedure [1] (formation
values of products minus those of reactants). The re-
sulting values as well as the changes Ang in gas mole
number are shown in Table 2. The equilibrium con-

K1 PcoP!/PH20 (4)

K2 = pCIf Pi O/PCO PH3 (5)
4 2 2
K = Pco2 PH2 /PCO P1120 (6)

at any temperature T can now be obtained from the
Van't Hoff equation

In Ki(T)= -AG/R* 298 + (AHo/R)(1/298- 1/T) (7)

Plots of In Ki(T) versus reciprocal temperature are
shown in Figure 1. In the absence of solid carbon, the
inequality in Eq. (4) may apply.
The data reveal conflicting demands with respect
to temperature and pressure. Both reactions 1 and 2
are necessary for methane formation from coal, but
reaction 1 is seen to be favored by high temperature
(positive AH) and low pressure (increase in gas mole
number), while for reaction 2 the opposite holds. In-
tuitively, we may wish to seek conditions giving not
too low an equilibrium constant of either reaction, and
thus be led to a temperature "window" of, say, 600 to
1200 K. If this line of reasoning were correct, we

Changes in Standard Free Energy, Standard
Enthalpy, and Gas Mole Number
for Reactions 1, 2, and 3
(AG" and AH" in kcal/mol, calculated from data in Table 1)

AH" Ang

Reaction 1
Reaction 2
Reaction 3

+ 21.83
- 33.97
- 6.83

+ 31.38
- 49.27
- 9.84


I.10' 2.10& 3.10'

FIGURE 1. Van't Hoff plot for equilibrium constants of reactions
1 to 3.

would seek low pressure at low temperature and high
pressure at high temperature, in order to have pres-
sure favor the reaction discouraged by temperature.
Obviously, we prefer low to high temperature and
pressure, and so we might start our search for condi-
tions with temperatures in the vicinity of 600 to 700
K and pressures of perhaps a few atmospheres. This,
however, is no more than a working hypothesis, to be
carried on our fingertips so it can be blown away by
the slightest breeze of better insight (as indeed it
The task at hand now is to find what sets, if any,
of operating variables-temperature T, pressure P,
and H2:H20 mole ratio R in the reactor feed-will
produce the desired 90% equilibrium yield to methane,
basis carbon reacted (i.e., 0.9 moles of methane pro-
duced per mole of carbon reacted). The most common
procedure [1-5] is to establish the relations between
the mole fractions yi of the gaseous participants at
equilibrium and the extents x, y, and z of the three


reactions, as shown in Table 3, and then to rewrite
the equilibrium expressions (4) to (6) in terms of the
extents of reaction and mole fractions yi = Pi/P. With
the mole fraction in Table 3, Eqs. (4) to (6) in terms
of extents of reaction become

Ki Y 2co (R+ x- 3y + z)(x-y- z) (8)
S H2O (1- x+y- z)(1+R+x- 2y)

-2 CH4YH2O y(1-x+y-z)(1+R+x-2y)2
YcoYH2a3 (x- y-z)(R+x-3y+z)3

K Yco2 Y z(R+x-3y+z) (0)
3 YCOYH20 (X -y-z)(l-x+y -z)

Sets of operating variables-temperature, pressure,
and feed mole ratio-can then be chosen for screening
(temperature determining the equilibrium constants).
For each set, the simultaneous Eqs. (8) to (10) must
he solved for x, y, and z, and the gas mole fractions
must be calculated from the expressions for the yi in
Table 3. This task involves a lot of calculation since
ranges of three independent variables must be co-
vered, but it can be performed without trouble on
a mainframe computer with a packaged routine for
solving simultaneous algebraic equations. For the pur-
pose at hand, this is the method of choice.
Two other methods could be considered here. The
rirst is the relaxation method (also called the series-
reactor technique [3, 4, 6]; this is an iteration over a
n!,,rge number of reactors in series, in each of which
only one of the three reactions occurs. The other is
the method of minimization of Gibbs energy (also
called Lagrangian multiplier technique [3, 4]), which
operates with equilibrium equations (one for each
species) and material balances (one for each element),

Initial Mole Numbers ni', Equilibrium Mole Numbers
ni, and Equilibrium Gas Mole Fractions Yi of
Gaseous Participants in Dependence on Extents
x,y, and z of Reactions 1 to 3
(procedure as in Hill [1])

ni- ni

x -y-z
R + x 3v + z


y/(1 +R +x- 2y)
(x + y z)/(1 +R + x- 2y)
z/(1 + R + x 2y)
(1- x + y-z)/( +R+x-2y)
(R + x 3y + z)/(1 + R + x 2y)

ICYrAL 1 + R + x 2y

to establish the minimum of free energy. Both
methods involve extensive calculation and would re-
quire more computer programming, although the
Gibbs method has advantages if systems are more
complex and a packaged routine is available.

Unfortunately for our group, we are informed that
the mainframe must be shut down to repair water
damage from Hurricane Fidel and that all stand-by
computing facilities have been reserved for tasks of
higher priority. We are reduced to using our hand-
held, programmable calculators. To meet the deadline
we shall have to streamline the problem.
Indeed, our approach as originally envisaged is in-
efficient in that many chosen sets of variables will pro-
duce results that are useless because the methane
yield falls short of our goal. Instead, we can choose
that yield as one of our "design options," that is, as
one of the three variables we can specify. Desired is

Ycl I/ (co+Yc +YcC )=0.9

which amounts to

YC/ (YC + Y )= 9 (11)

With the expressions for the mole fractions in Table
3 this reduces to

y = 0.9 x

a result so simple as to be suspect. It makes sense,
however: Carbon appears only in reaction 1, as reac-
tant; and methane, only in reaction 2, as product.
Therefore, y/x = 0.9 translates into 0.9 moles of
methane formed per mole of carbon reacted. With Eq.
(12), y can be eliminated from Eqs. (8) to (10), greatly
reducing our calculation load. We still have three
simultaneous equations to solve, but we can solve for
x, z and R and have only ranges of two variables, P
and T, to screen instead of three. Moreover, every
successful calculation (i.e., giving a physically realiz-
able answer) will now produce a useful result as the
demanded methane yield is guaranteed. A possible ap-
proach is to fix temperature and pressure within our
window, select pairs of values of x and z, solve the
three equations for R, and adjust the choice of x and
z until all three equations give the same value of R.
This will take time and our time is short, but with,
say, ten or twelve good programmable calculators in
our groups we might just be able to come up with at
least a few sets of conditions giving the desired result.



... in our days of easy access to computers and the temptation to use [them] on every occasion, it will be
educational for a student to see that the human brain still has a place in our world: That, in fact, a problem properly
thought through might possibly be solved long-hand in a shorter time than it would take to be fed to a computer.

Now the time has come to let misfortune strike
again. Fate (personified by the instructor), decrees
that we are running out of batteries and have no re-
placements. Can our problem be solved in the few
hours left with just pencil and paper alone?
On closer inspection we might realize that we have
not derived full benefit from our idea to start the cal-
culation with the desired result. There is no longer
any need to translate the simple, partial-pressure
equilibrium Eqs. (4) to (6) into the more complex ex-
tent-of-reaction Eqs. (8) to (10). It is true that total
pressure does not appear explicitly in Eqs. (4) to (6)
and so can no longer be chosen as a design option.
However, we are not held to calculate results for
specified total pressures and so can let ourselves be
surprised by what that pressure will turn out to be.
Following up on this idea, we find that if we fix
temperature, and thus the three equilibrium con-
stants, we have five unknowns (the five partial pres-
sures), three equations (if for the time being we accept
the equality in condition (4)), and one constraint (the
selectivity requirement (11)). Accordingly, we can
choose one partial pressure and calculate all others.
For instance the four other partial pressures can be
expressed as functions of only pCH4 and the equilib-
rium constants and can be calculated once a value of
PCH4 (and of temperature) has been chosen.
Proceeding in this fashion we can obtain explicit
equations for our partial pressures, but at least one is
a quadratic equation. Because the deadline is so close,
we might want to streamline the problem even
further. Experience with other projects and the very
large decrease in AG from CO to CO2 (see Table 1)
tells us that at all reasonable temperatures and pres-
sures the amount of CO at equilibrium will be small
compared with that of CO2. We should thus be fairly
safe if we set

PCH/ Po = 10 (13)

instead of

PCH / (CO +PO )= 9
4 2

This still leaves some margin for CO and should bring
us quite close to the desired result.

By simple algebraic manipulation, Eqs. (4) to (6)
are easily solved for pH2 and pco in terms of PCH4 and

Pco =(K1 p / K )2 (14)
P11 =(PCH /K1K2 ) (15)
2 4

p"on is then obtained from Eq. (4)

Ho20 PH2PCO / K

Eq. (13) allows us to choose a partial pressure of
methane and one of CO2 one-tenth as large and calcu-
late the other three. In each case, we shall have to
check whether the stipulated methane yield is indeed
attained or exceeded; if not, the calculation must be
repeated with a slightly lower partial pressure of CO2.
Time permitting, if the yield turns out to be signifi-
cantly better than needed, the calculation should also
be repeated, with a slightly higher partial pressure of
CO2, for better comparison of conditions giving the
desired result.*
We still have to deal with the possible inequality
in the equilibrium condition (4) for reaction 1 and with
the possibility that water may condense at equilibri-
um. It becomes immediately apparent that an inequal-
ity in condition (4), as would be produced by continued
reaction after all coal is consumed, leads to a higher
water content of the product gas and thus is undesir-
able. As to water condensing, at temperatures below
647 K (critical temperature of water) the calculated
partial pressure of water must be checked against the
vapor pressure at that temperature. If it exceeds the
vapor pressure, the calculation is invalid and would
have to be repeated with pH20 set equal to the vapor

Note Added in Proof:
As pointed out to me by J.-M. Chern, the approximation (13)
and the recalculations it may necessitate can be avoided as
follows: select a value of Pco; then calculate
Pco2=K3Pco2/Kl[from Eqs. (6) and (4)], PCH4 = 9(Pco2 + PCO)
[from Eq. (9)], P12 = (PCH4/K1K2)1/2 [from Eqs. (4) and (5)],
and PH20 = PcoPH22/Kl [from Eq. (4)]. The only disadvantage
of this more direct procedure is that it is harder to anticipate
what the total pressure will turn out to be when starting with
CO, in most cases a very minor component, instead of CH4,
the main component.


pressure. Only one other partial pressure can now be
freely chosen, and the desired methane yield might
not be attained. However we were instructed to avoid
such conditions because they would invite corrosion
problems, and so should rather discard the case.
As to information on the three operating variables:
Temperature was fixed to calculate the equilibrium
constants; total pressure is immediately obtained as
the sum of the partial pressures; the H2:HO2 feed mole
ratio still remains to be determined. This requires ma-
terial balances. Since water is the only source of oxy-
gen, the oxygen balance is

moles H20 in= (moles H2O +CO + 2*CO2) out

and the hydrogen balance is

(moles H2 + H20)in=(moles H2 + H20+2* CH) out


moles H2 in PH20 + PHf2 2PCH,
R H in p 1
moles H2O in pH + pCO + 2pC
2 HO O 02

This completes the information needed.
With each member of the group calculating, say,
four or five cases in assigned ranges of temperature

and partial pressure of methane, a rather broad and
thorough coverage of conditions giving the desired
methane yield can be achieved, with just pencil and
paper, in time for presentation to an impressed man-
agement. (Slide rules would come in handy but are
hard to find short of raiding the local science
museum-and rare is now the student who has
learned to use one.)

Results of nine calculated cases in the range of 600
to 1000 K and 2 to 85 atm and with methane yield
(based on carbon converted) tuned to fall between
0.900 and 0.902 have been collected in Table 4. The
table also includes the ratio of H2 fed to CH4 formed,
a measure of the economically highly important hydro-
gen utilization.
It turns out that, contrary to our initial intuitive
idea, the desired methane yield is easily attained at
almost any temperature and pressure. Indeed, the
yield is relatively insensitive to these operating vari-
ables and can be tuned at will by changes in the
H2:H20 feed ratio; the required feed changes are
minor except at high temperature and low pressure,
where much hydrogen is needed to force methane for-
mation. This serves to demonstrate that, in multiple
reaction equilibria, one reaction can fairly effectively

Calculated Equilibrium Partial Pressures, Selectivities to Methane (Basis Carbon Reacted),
H2:H20 Mole Ratios in Feed, and Mole Ratios H2 Fed to CH4 Formed, in Range 600 to 1000 K and 2 to 85 atm
(Courtesy of L. C. Eagleton)

temperature. K 600 800 1000
total pressure, atm 1.97 9.68 95.7* 2.05 9.16 85.2 2.65 9.74 82.3
H2:H20 in, m/m 1.83 1.79 1.77 3.40 2.77 2.46 14.74 7.59 3.99

pCH4, atm 1.00 5.00 50.0 1.00 5.00 50.0 1.00 5.00 50.0
Pco2 0.109 0.546 5.47 0.0836 0.490 5.24 0.0068 0.116 3.27
PH20 0.793 3.971 39.73 0.473 2.56 26.50 0.107 0.991 16.62
Pm 0.071 0.159 0.504 0.465 1.04 3.29 1.43 3.20 10.13
Pco 0.0004 0.0009 0.0029 0.0272 0.0659 0.216 0.104 0.429 2.28
(CH4 out):(C in), m/m 0.9014 0.9014 0.9014 0.9002 0.9000 0.9016 0.9003 0.9017 0.9002
(H2 in):(CH4 out), m/m 1.85 1.81 1.79 2.27 2.00 1.85 3.31 2.51 2.02

* Invalid case: Calculated partial pressure of water exceeds vapor pressure.
* Invalid case: Calculated partial pressure of water exceeds vapor pressure.


drive another, even if the latter's equilibrium constant
is quite unfavorable. It scuttles the hypothesis we
started out with.
In the broader context of the project, we might
say that we have worked ourselves out of a job. Our
analysis has shown that thermodynamics does not im-
pose serious limitations and that optimum operating
conditions will be dictated mostly by other considera-
tions, such as catalyst chemistry, rates, corrosion and
materials of construction, solids handling, etc.

Had we been more clever, we might have antici-
pated these conclusions. We could have written an
overall stoichiometric equation approximately reflect-
ing our desired conversion:

C+ 0.2 H20 +1.6 H2 -- 0.9 CH4 + 0.1 CO2 (18)

The mere fact that we can write such an equation
should have made us realize that the methane yield
depends on the relative amounts of H2 and H20
reacted, while temperature and pressure play only an
indirect role by affecting the extent of CO formation
and the relative amounts of H2 and H20 leaving un-
reacted with the product gas.
For reaction (18) we find

AG= 943 kcal/mol
AH=- 13.95 kcal/mol
An, =- 0.8

We see that the reaction, constrained to roughly the
desired methane yield, is somewhat favored by low
temperature (small negative AH) and high pressure
(small negative Ang) and has a reasonable favorable
equilibrium (negative AG'298); Ki(T) by Eq. (7) turns
out to be larger than unity up to T = 920 K. The gist
of the conclusions from our calculations could thus
have been foreseen on the basis of an even simpler, if
crude, reasoning.

Apart from having been placed in the atmosphere
of an industrial development project and having
gained some insight (even if superficial), into coal
methanation equilibria, the student should have de-
rived other benefits from this exercise.
Regarding reaction equilibria, the student will
have learned a much simpler approach that can often
be used in practice. More importantly, he or she will

take home the message that many practical problems
in chemical engineering are more easily solved not by
stipulating conditions and calculating results, but by
starting from the desired result and finding conditions
that will produce it-just as, say, an equation such as
X3 + x In x = a requires a root finder to calculate x
(the result) for given a (conditions) but is solved di-
rectly in seconds for a if x is given. As our exercise
has shown, this approach is most effective if the relev-
ant equations are written in their simplest form and
the "design options" (that is, the variables that can be
chosen) are selected from the variables appearing in
these equations (in our case, the partial pressures).
This "cart-before-the-horse" approach is rarely
found in elementary texts. However, there is one
well-established precedent in chemical engineering
education: the McCabe-Thiele construction for binary
fractionation columns. Here, the desired purities of
the tops and bottoms are specified, and reflux ratios
and numbers of trays to attain them are determined.
I recommend to my students that they fill an hour of
boredom with an attempt to use the construction to
find the tops and bottoms purities for a given tray
number and reflux ratio, just to see how much more
complicated and difficult the procedure becomes.
Lastly, in our days of easy access to computers
and the great temptation to use these wonderful
machines on every occasion, it will be educational for
a student to see that the human brain still has a place
in our world, that in fact a problem properly thought
through might possibly be solved long-hand in a shor-
ter time than it would take to be fed to a computer.

I am indebted to R. L Kabel for his suggestion to
use coal methanation as a class problem.

1. See, for example, C. G. Hill, Jr., An Introduction to Chem-
ical Engineering Kinetics & Reactor Design, Wiley,
Chapter 2 and Appendix A (1977)
2. S. R. Brinkley, "Note on the Conditions of Equilibrium for
Systems of Many Constituents," J. Chem. Phys., 14, 563-
3. T. Daubert, Chemical Engineering Thermodynamics,
McGraw Hill, Section 9.5 (1985)
4. S. M. Walas, Phase Equilibria in Chemical Engineering,
Butterworth, Section 10.6 (1985)
5. E. B. Nauman, Chemical Reactor Design, Wiley, Exam-
ple 4.15 (1987)
6. H. P. Meissner, C. L. Kusik, and W. H. Dalzell,
"Equilibrium Composition with Multiple Reactions,"
I&EC Funds., 8, 659-665 (1969) 0





University of Notre Dame
Notre Dame, IN 46556

A COURSE WHICH many departments find trouble-
some to teach is the senior level process design
course. Problems may arise because there is no avail-
able faculty member with either significant design ex-
perience or who does research in the area of process
design or simulation, and the option of bringing in an
industrial practitioner may not be possible because of
geographical considerations. Even when an appropri-
ate faculty member is available, a question which must
be addressed is: What goals should the course have,
given the continual evolution of technology and the
shifting of traditional positions of employment for BS
chemical engineers? An additional consideration is:
How can these goals be realized when the course is
taken by second-semester seniors who can be ex-
pected to lose intensity after spring break?
In this article, the format of a senior design course
structured for the present economic and business con-
ditions and for a group of students with diverse in-
terests, is described. In addition, the content and for-
mat are such that an instructor who is not an expert
in design can still provide a useful and interesting
course for the students.
The primary goals of the course are to

1. Develop the students' ability to "create" good solutions to
engineering problems for which many alternatives exist.
2. Expand the above goal to include all types of problems for
which a student's knowledge or experience could be use-

Mark J. McCready joined the faculty
at Notre Dame as an assistant professor af-
ter receiving his BChE degree from the
University of Delaware and his MS and PhD
degrees from the University of Illinois. His
research interests lie in the areas of fluid
mechanics and transport properties of mui-
tiphase flows. Current topics include inter-
facial wave phenomena and turbulent
transport of solids.

3. Improve written and verbal communication skills.
4. Encourage students to form a viewpoint about science and
technology and to look beyond the current situation to see
the bigger picture.
5. Expose students to some of the issues which they will face
when they leave college for their chosen profession.

Goals 1 and 3 are traditionally present in any de-
sign course, but the other three, which are also impor-
tant in the education of students who will pursue a
broad range of career paths, are not. To meet these
goals, elements other than design projects and lec-
tures on topics related to design must be incorporated
into the course.
The process design sequence at Notre Dame con-
sists of two 3-credit courses which meet three times
a week for fifty minutes. In the fall course, basic de-
sign topics such as economic analysis, short-cut design
methods, process synthesis, and flowsheeting are co-
vered. In addition, students are given instruction and
practice (in the form of small projects) in the use of
the process simulator ProcessTM [1]. Because many of
the fundamentals of process design have been included
in the fall semester course, great flexibility is possible
in the content of the spring semester course. This al-
lows for the opportunity of extending the curriculum
of the design course to address goals 2, 4, and 5.
The components of the second semester course are:

A process design project
A project which involves the invention of an original prod-
Class discussions on pertinent moral/social/economic is-
"Problems of the week" (defined below)
Lectures on various topics

Each of these features of the class will be described
below in terms of the intended goal.
Copyright ChE Division ASEE 1989



It is worth noting our experience with the use of a process simulator which allows for the simulation of some rather
complex equipment configurations. The process for the separation of the light hydrocarbon stream required five
distillation columns, ten compressors, numerous heat exchangers, and various other equipment. While this could
all be simulated, the time involved in getting many separate pieces of equipment to work correctly was excessive.

Given the success of our "team teaching" approach
in the undergraduate labs where four or five faculty
members are involved (each having complete charge
of two experiments), we decided to try a similar ap-
proach to process design. For this semester, four fac-
ulty members (including the course coordinator) were
part of the course, with each directing two groups of
three students on a single design project. The course
coordinator had overall responsibility for the course,
including lectures. With only one project to direct,
each faculty member could become quite familiar with
the details of his design problem and its potential so-
lutions. He was therefore able to provide suggestions
to assist the group's progress as well as to evaluate
their performance. Two groups were assigned to the
same project. This allowed for competition as well as
for comparison of final solutions, but did not result in
the problem being overworked, with all its subtleties
"shared around," which often occurs when an entire
class does the same project. The projects used were:
separation system for a light hydrocarbon mixture
(adapted from a CACHE problem, suggested by D. S.
Maisel, which was implemented at Carnegie Mellon
University); design of a separation scheme to remove
dimethlyformamide from water (adapted from a prob-
lem in the Washington University AIChE Series, au-
thored by Frank Rush and implemented at the Uni-
versity of Delaware); design of a process to produce
ethanolamines (suggested and directed by J. T. Ban-
chero, Emeritus Professor at Notre Dame); and a pro-
cess which involved a novel use for waste whey
(suggested and directed by F. H. Verhoff, an adjunct
professor of our department).
The projects were chosen in consideration of a
nine-week time constraint for completion. While this
period is shorter than those usually allocated for large
projects, I have been a student recently enough to
know that the amount of time and effort spent work-
ing on a large project is not determined by the total
time interval (or the difficulty of the project), but by
the number of sub-parts (i.e., progress reports) neces-
sary for its completion.
The design project was introduced through a
memo from the instructor which specified that a go/no-
go decision on a particular project was to be made by
the parent company on a specific and not-too-distant

date (early April). The task before each group was to
get the best possible solution as to the project's feasi-
bility and its associated economics before that date.
Intricate details regarding equipment selection were
not to be addressed.
On the first day of class, and after being divided
into groups, students were given a short written de-
scription of four projects and were asked to list their
choices in the order of their preference. Not surpris-
ingly, reflective of the time (and with no knowledge
of which of the faculty was going to supervise which
project), six of the nine groups listed the whey utiliza-
tion project as their first choice.
Progress memos, specified as "on time or not at
all," were due every two weeks, which made it neces-
sary for the students to work on their projects virtu-
ally every day. This rate of progress allowed the
major technical and computer-intensive work to be
done before spring break. The progress memos were
the standard type, with the first one requiring that
the students examine the literature for answers to
such questions as: Is there any current need for the
process? What are the uses, the selling prices, and the
world demand for the products? How are these ex-
pected to change in the future?
The groups met with their project supervisors
each week for about a half hour. Depending on the
skill of the group, the involvement of the instructor
would range from making vague suggestions to ex-
amining specific details of the students' work. In gen-
eral, the faculty tried to provide as little guidance as
possible in hope that the groups would solve their
problems independently.
It is worth noting our experience with the use of
a process simulator which allows for the simulation of
some rather complex equipment configurations. The
process for the separation of the light hydrocarbon
stream required five distillation columns, ten com-
pressors, numerous heat exchangers, and various
other equipment. While this could all be simulated,
the time involved in getting many separate pieces of
equipment to work correctly was excessive. Greater
educational benefit would have resulted if the problem
were simpler (in this case, fewer chemical compo-
nents). This would have allowed more time for the
students to take full advantage of a process simulator,
i.e., to propose and check numerous alternative


schemes and to spend more effort on optimization of
the best scheme.
The memos provided an opportunity for the stu-
dents to practice their writing. We have found that
this is not an overwhelming necessity, however, since
students at Notre Dame must take advanced
humanities courses which require papers. In addition,
our seniors have by this time completed two semes-
ters of chemical engineering lab. Consequently, our
students can write well if they take sufficient care. I
was less certain about the ability of students to com-
municate verbally. To give them practice, groups had
to give twenty-minute oral presentations to the entire
class, describing the results of their projects. The
presentations were surprisingly good. All of the stu-
dents had given a similar report on at least one prior
occasion (in the fall chemical engineering laboratory),
and a lecture/discussion on the mechanics and goals of
such talks was held in the current semester.
Professor James Wei [2], expressing his concern
for the future health of the chemical engineering pro-
fession, has made the statement, "We have to put a
bigger share of our best brains into manufacturing;
bring in people who can make the economic pie bigger
rather than those whose job it is to divide up a pie
that is already baked." This general idea has been
expressed by many who worry that chemical en-
gineers may become less valuable in society if they
are limited to the design and operation of chemical
processes. Encouraging creativity in our graduates is
certainly one way to prevent the decay of the profes-
This part of the course, which occurred during the
last four weeks of the semester, began with a lecture/
discussion inspired by James Christensen [3] and
Richard Felder [4,5]. At the beginning of one class
period I mentioned to the students that they should
not be limited by normal thinking, but should try
novel methods for solving problems. They were then
left to work on some in-class exercises which I had
devised. Exercises which produced the most creative
solutions were: develop a homework problem in fluid
mechanics which involves a priest, a swimsuit model,
and a sea creature; describe as many uses as possible
(other than personal viewing) for a complete set of the
episodes from the TV show M.A.S.H. on VHS tapes;
and, devise an advertising strategy for a major Wall
Street investment banking firm which wants to enter
the consumer investment market.
With this introduction, groups were asked to in-
vent a product which they feel is needed by the world

but which does not already exist. The original inten-
tion that the product should be related to chemical
engineering was loosely enforced. This allowed the
students to consider any interesting ideas, and they
were not limited by a lack of technical knowledge. The
first memo, due within a few days, had to describe the
reasons for their product and, more important to the
goals of the course, had to include a list of (at least)
ten ideas which were rejected. A wide variety of good
and bad ideas filled the lists, some of which may have
patent possibilities. The second memo, due two weeks
later, was to describe the technical aspects of the
product, e.g., how it can be made, or what the exact
design or chemical formula is. A final memo had to
contain a rough economic forecast and describe the
perceived market sector and corresponding marketing
strategy. Again, oral presentations were given, de-
scribing the product to the class.
This time, however, a twist was included. As the
project was originally formulated, an advertising cam-
paign was required if the product was intended for
use by consumers. When I included this in the original
instructions, I did not anticipate that all the groups
would pick consumer products. The consequence was
that we were subjected to two and one-half hours of
presentations, interrupted by commercials. One group
made a video tape describing the technical aspects of
its product, but most of the commercials were "live."
While the strategy and style of the commercials were
not really novel, the content was.
Needless to say, the students found this aspect of
the course quite enjoyable; but how can we rate the
educational benefit? I believe that it provided an op-
portunity for all students to use their creativity,
which is not possible when solving difficult design
problems. While design problems may lend them-
selves to creative solutions, only the very best stu-
dents who understand all of the technical aspects are
in a position to develop imaginative solutions. Weaker
students are left to struggle along and to get any an-
swer they can.
When I mentioned (to anyone who would listen)
my plans to try such an exercise with a class of
seniors, the typical responses were that either it
would work great or it would be a total disaster. The
verdict: It did work well. The students put in the time
necessary to ensure the success of the project; if they
had not exerted this effort, the idea would have failed.
The product design project allows for obvious ex-
tensions if time permits. The ASEE summary of the
Quality of Engineering Education Project [6] men-
tions that, "Employers are generally satisfied with the
basic technical preparation of today's graduates, but


find them largely unaware of the steps needed to bring
new products from the idea stage to the marketplace
and of the vital roles that engineers play throughout."
Groups could be required to examine the manufactur-
ing steps necessary to actually make the product, with
the goal of identifying operations which could cause
problems with reliability. In addition, marketing fore-
casts could be done in greater detail.

In an effort to improve the general problem solving
skills of the students, problems drawn from everyday
life, but which required engineering solutions, were
posed and then solved using suggestions by the stu-
dents. This was done at the beginning of class every
Friday until time became too short to continue. The
premise behind this part of the course is that most
students need to think about solving problems when
no clear subject (e.g., fluid mechanics or ther-
modynamics) or method is implied. My favorite prob-
lem concerned keeping a Big Mac hot in a car on a
cold day. A simple heat transfer analysis demon-
strated that it is better to keep the bag on the seat
rather than under the heater. However, one particu-
larly inventive student suggested that the glove com-
partment might be the ultimate solution.
Initially, I found that very few students would
venture even a guess as to how to solve the problem.
However, after about the third time they warmed up
to the idea, and I subsequently got more than enough
suggestions to solve any problem. On the only test,
given at about mid-semester, responses to a question
regarding the inevitable uneven cooking of a frozen
pizza demonstrated that students were enjoying the
challenge of solving such problems. The course evalu-
ation questionnaires showed that students felt this
was a very beneficial part of the class and that it
should be expanded. A good suggestion which will be
implemented in the future was to provide students
with a summary of the solution after class so that no
note-taking would be necessary.

The biggest problem which arises in teaching a
process design course when the instructor does re-
search in a field far removed from design, is the selec-
tion of topics and the development of lectures. Profes-
sor J. C. Kantor had taught this course previously,
and during that time he had developed a set of course
notes and identified literature sources for important
topics, with the intention of enabling other faculty to
teach the course. Lectures for the present course

were adapted from his notes. Major topics included a
survey of the products and economics of the chemical
and petroleum process industries (particular emphasis
was placed on specialty products), prediction of phys-
ical and chemical properties, and optimization. Indi-
vidual lectures were devoted to batch processing, pro-
cess reliability and quality control, multiphase con-
tacting, interpersonal relations, and fluid pumping. In
addition, an engineer from UOP Corporation gave a
lecture on a specialized separation operation. One
topic which will be included in the future is the selec-
tion and evaluation of separation processes.

One of the course goals was to encourage students,
who are trained in science and engineering, to develop
opinions about technology and its use. To effect this,
some of the lectures had a definite point of view which
could have been (and sometimes was) disputed. An

One of the course goals was to encourage students, who
are trained in science and engineering, to develop opinions
about technology and it use An additional aspect
was to have class discussions on controversial topics ...

additional aspect of the course intended to achieve this
goal was to have class discussions on controversial
topics, such as use/misuse of chemical pesticides and
herbicides, or the productivity of the American work
force (which was based on a preliminary release of an
MIT productivity report [7]). The relatively small
class size (twenty-eight) made this possible, and the
format used was similar to a debate. Two teams of
students prepared arguments for opposing sides of the
issue. The rest of the class was free to join the discus-
sion after the opening statements were made. It was
not surprising that the students' ability to develop and
express opinions was not correlated in any way to
their grade averages.
From the evaluation questionnaires it was possible
to get an assessment of this feature of the course.
Some students mentioned that it encouraged them to
think of technology more broadly, but sometimes the
arguments moved on to tangential issues or became
totally unfocused. Nevertheless, two or three will
probably be held next year, with an effort made to
correct the flaws.

This course, which differs from traditional design
courses in several respects, was structured to meet
Continued on page 99.





Georgia Institute of Technology
Atlanta, GA 30332

THIS ARTICLE DESCRIBES a senior-level under-
graduate laboratory experiment on combined mass
transfer and kinetics. Specifically, the increase of pH
in an aqueous solution of acetic acid (such as vinegar)
is followed with a digital pH meter during neutraliza-
tion with commercial antacid tablets. This experiment
was successfully implemented into the chemical en-
gineering laboratory curriculum at Georgia Tech dur-
ing the winter quarter of 1988, at a total cost of $600.
The reagents can be purchased cheaply at a local

The development of meaningful yet inexpensive
engineering laboratory experiments on chemical kine-
tics is a difficult task. The incorporation of mass trans-
fer concepts into such experiments renders this task
even more formidable.
The pH values of the gastric contents of human
stomachs can typically vary from 1.0 to 3.0. Similarly,
the pH values for many foods, specifically fruits (ap-
ples, apricots, grapefruit, oranges, peaches, pears,
strawberries), are in the range of 3.0-4.0. Thus, dilute
acetic acid (such as vinegar) with a pH of around 3.0
is a reasonably effective and inexpensive representa-
tive of the weak organic acids present in a human
body. This acid may then be employed for'simple lab-
oratory simulation of the biochemical processes as-
sociated with neutralization by commercial over-the-
counter antacids to relieve gastric distress.

. dilute acetic acid (such as vinegar) with a pH of
around 3.0 is a reasonably effective and inexpensive
representative of the weak organic acids
present in the human body.

Stuart A. Sanders received his
bachelor's degree in chemical engineering
in June of 1988 from the Georgia Institute
of Technology. He developed the
laboratory experiment described in this arti-
cle during his senior year. He is currently
employed as a composites engineer with
Pratt-Whitney in West Palm Beach, Florida.

Jude T. Sommerfeld is a professor in
the School of Chemical Engineering at
Georgia Tech. He received his BChE from
the University of Detroit and his MSE and
PhD degrees, also in chemical engineer-
ing, from the University of Michigan. His 25
years of industrial and academic experience
have been primarily in the area of computer-
aided design, and he has published over
f:-htv articles in this and other areas.

The principal piece of equipment needed for this
laboratory experiment is a pH meter and electrode
with a reasonably rapid response time, e.g., 5-10 sec-
onds. For this purpose, an Accumet Model 910 pH
meter with digital readout was purchased from Fisher
Scientific for about $500. A glass-body combination
electrode (with automatic temperature compensation)
was also purchased from the same company (Catalog
No. 13-639-285), as well as two buffer solutions (pH
= 1.0 and 7.0) for 2-point standardization of the pH
meter. Total cost of these latter items was less than
Most of the remaining required equipment items
are standard laboratory supplies, such as beakers,
graduated cylinders, and reagent bottles. A magnetic
stirrer and stirring bar are required, as well as a
timer. A set of vernier calipers is also needed for the
students to measure the dimensions of the antacid tab-
lets studied. A photograph of the experimental setup
is shown as Figure 1.

Copyright ChE Division ASEE 1989


FIGURE 1. Experimental setup to study neutralization of
vinegar with antacid tablets.


Some initial tests were performed on the neutrali-
zation of distilled white vinegar with granulated or
powdered antacids. As one might expect, the neutrali-
zation was completed within less than a minute. This
time frame is, of course, unacceptable for two reasons:
1) response time considerations of the electrode and
2) duration of the experiment for data acquisition. It
was also found that very little vinegar was required
if one wished to avoid excessive consumption of the
Thus, in all further experiments the distilled white
vinegar was diluted with distilled water in the ratio
of 1:20. It was also decided to use antacid tablets as
the neutralization agents. Two such commercial prod-
ucts were chosen, and they are denoted as R and T
throughout this article. The various properties and
physical characteristics of these antacid tablets are
given in Table 1.


Following is a summary of the procedure for this
laboratory experiment, as distributed to the students.
The protective tip is removed from the pH elec-
trode, and the latter is rinsed well with distilled water
to remove any residue which may have formed on the

electrode tip. The 2-point standardization of the pH
meter is then performed with the two buffer solutions
in accordance with the procedure given in the man-
ufacturer's instruction manual. A copy of the latter is
provided (loaned) to the students at the beginning of
the experiment.
A fresh acid solution is prepared by mixing 25 ml
of distilled white vinegar and 500 ml of distilled water
in a 1-liter reagent bottle. From the latter, 250 ml of
this fresh acid solution are transferred to a 500-ml
beaker, which is placed on a magnetic stirrer. This
beaker is then positioned below the electrode assem-
bly, and the latter is lowered into the acid solution.
Care is taken to ensure that the stirring bar will not
hit the electrode tip during operation. The initial pH
of the acid solution is recorded (typically 3.09).
The thickness (H) and diameter (D) of a tablet of
the test antacid are measured with the vernier cali-
pers. At time = 0, the suggested number of tablets
(m = 5 for brand R, 3 for brand T) are dropped into
the acid solution and the timer is started. The stirring
speed is adjusted to achieve a fair degree of
homogeneity, and so that the tablets are just barely
lifted off of the bottom of the beaker. The pH values
for the solution are recorded at 30-second intervals
for the first five minutes, at 1-minute intervals for the
next 15 minutes, and at 2-minute intervals for the re-
mainder of the run-until the tablets are completely
dissolved and the solution pH has levelled off at a
constant value (typically 40-50 minutes total).
The above procedure is then repeated for the sec-
ond antacid (R or T) to be investigated. Typical ex-
perimental data from such an investigation of brand T
are presented in Table 2.

Characteristics of Antacid Tablets Studied


Active (alkaline) ingredient Dihyd
Typical mass of tablet, g
Mass of active ingredient, mg
Mass fraction active ingredient (xB)
Mol. wt. of active ingredient (MB)
Typical thickness of tablet (H), cm
Typical diameter of tablet (D), cm
Aspect ratio (a = H/R)
Density of tablet (p), g/cm3
No. of tablets used in an experiment (m)

Antacid Brai

ium carbonate





Very simply, the overall ionic reaction for this sys-
tem is:
2H 0++ CO3 -4 3H0 + CO2 (1)

It is assumed that the instantaneous rate of the overall
reaction, measured as the rate of disappearance of the
hydronium ion, is proportional to the product of the
instantaneous remaining surface area of the tablets
and the hydronium ion concentration, with the order
for the latter as yet unspecified. Thus

1 dNA
kaCA (2)
V dt A

Now, the area of a given tablet (disc) is the sum of its
two faces plus its edge, or 21rr2 + 2'nrh. Assuming
that the aspect ratio (a = height/radius) of a given
tablet remains constant throughout the dissolution
process, the instantaneous surface area of a tablet is
2rr2 (1 + a). Eq. (2) then becomes, after assuming
constant reaction volume (V)

dCA 2 =-2nkmr2(1+a)CA (3)
dt A

It is necessary to relate CA and r in the above
llation. From the stoichiometry of Eq. (1)

Experimental Data on the
Neutralization of Vinegar with Antacid Brand T

t, min pH

t,min pH

t, min pH


terms of the single dependent variable r, is then ob-
tained after substitution of Eq. (8) into Eq. (7).

In the case of n = 1 (process is first-order with
respect to the acid concentration), the substitution of
Eq. (8) into Eq. (7) yields

dr k(3 )

dNA dN,
dt dt

Eq. (3) then becomes

1 dNB
1 d B kmr2( a)C
V dt A


(1+a)M, CA V 2nm(l+a)R3
3apxB 3

(5) and

We further assume that the composition of an antacid
tablet remains constant throughout the process. Thus

N tmr2 hpxB armpxB r
NB M MB (6)

Eq. (5) then becomes

dr -k(l+a)MBV
dt 3apxB A A(

From an overall material balance

C 2ampxB (R r3) (8)
The final differentiA equation to be integrated, inV

The final differential equation to be integrated, in

P3 27m(1+ a)

Eq. (9) can then be integrated between the limits of r
= R at t = O and r at t to yield

3 2 (+R(12- r +r2)

+ 3 TAN- 2r TAN- 12R 1 = kt (12)
L l V3- wh J



Thus, a plot of the left-hand side of Eq. (12), de-
noted as f(r), versus time (t) would yield a straight
line if n were equal to unity. The slope of this straight
line would be the combined mass transfer and kinetic
rate constant, k. The function f(r) is computed at each
experimental data point by calculating r from rear-
rangement of Eq. (8)

r= /R 2B V C C) (14)
2anmpxB x A A)

and invoking the definition of pH

pH =-log(CA) (15)

When the data of Table 2 were converted and plotted
in the indicated fashion, however, the results were
disappointing. Instead of a straight line, a smooth
curve with a monotonically decreasing slope was ob-
tained, indicating that n $ 1.
A differential analysis of the experimental data of
Table 2 was next performed. For this purpose, the pH
data of Table 2 were converted to CA, numerically
differentiated with respect to time, and the resulting
rate normalized with respect to the instantaneous
total surface area of the tablets. The latter is com-
puted as

a = 2mr2 (1+ a) (16)




-22 -20 -18 -16 14

LN [H*]

FIGURE 2. Plot of reaction rate, normalized to the instan-
taneous surface area of the tablets, versus the hydro-
nium ion concentration, in log-log coordinates.

where r is again computed from Eq. (14), averaged
over the time increment selected.
The logarithm of the normalized rate

i[1 dC A

was then plotted versus the logarithm of the hydron-
ium ion concentration. The result of this procedure is
shown in Figure 2. As Eq. (2) indicates, the slope of
this straight line in log-log coordinates should be equal
to the reaction order (n) with respect to the hydro-
nium ion concentration. Least-squares regression
analysis of these data for the T tablets yielded a slope
of n = 1.5007, with a correlation coefficient of 0.980.
Similar results, i.e., n ~ 3/2, were obtained from ex-
perimental data on neutralization with brand R tab-


Thus, in the laboratory instructions to the stu-
dents, they are given the value of n = 3/2 in Eq. (2),
and then asked to experimentally determine the value
of the combined mass transfer and kinetic rate con-
stant, k. This is accomplished by again numerically
differentiating the data to obtain dCA/dt, and plotting
this result versus the product of 27rmr2 (1 + )CA32




-2.000e-7 -

y = 3 2837e-9 79 469x R'2 = 0 984


2.000e-9 4.000e-9 6.00e-9 8.00D-9


FIGURE 3. Plot of reaction rate to obtain rate constant
from Eq. (3).


[see Eq. (3)]; r is again calculated from Eq. (14). The
result of this procedure is shown in Figure 3 for the
data of Table 2 on brand T tablets. Least-squares re-
gression analysis of the data in this case yielded a
value of the slope for this straight line (equal to k) of
79.5 (liter/gmole)12/(cm2 min).

No reasons for the apparent process order with
respect to the hydronium ion concentration of n = 3/2
are provided to the students. They are not expected
to come up with an explanation, either. The develop-
ment of a more complete and accurate mechanism for
this process would certainly be an interesting exer-
cise, but is beyond the scope of a single undergraduate
laboratory experiment (one of four during a 10-week
Thus, in addition to the single heterogeneous term
of Eq. (2), incorporation of the homogeneous aqueous
dissociation of acetic acid
CH COOH+H2 0 (-- H3 0+CH3COO- (17)

would be a more complete representation for the rate
of hydronium ion disappearance. In this case, Eq. (2)
would become

1 dNA (18)
V dt kaCA CHAc + kA Ac-

The reverse reaction rate constant (k2) in Eq. (18) can
be eliminated by introduction of the dissociation con-
stant for acetic acid (KA), but the forward rate con-
stant (ki) would have to be estimated or determined.
In writing Eq. (2), it was implicitly assumed that reac-
tion (17) is always at equilibrium, and thus its net rate
is equal to zero. In principle, this reaction can be in-
corporated into the model through usage of appropri-
ate material balance equations, but processing of the
experimental data then becomes practically intract-
Another consideration pertains to consumption of
the acetic acid. In writing Eqs. (1) and (4), it was also
implicitly assumed that the only mechanism for con-
sumption of the acetic acid was the following overall
2CH COOH+CO3 H20+CO2 +2CH COO- (19)

where COs= is the common anion in the two brands of
antacid tablets studied. However, since CO2 is formed
as a product of reaction (19), the following additional
CH COOH+HCO H -> H20+CO +CH CO- (20)
3 3 2 2 3

may also be postulated for consumption of the acetic
acid. The bicarbonate ion, of course, is formed from
the ionic dissociation of CO2

H20 +CO2 H2CO3

H2CO +H2 O-H O +HCO-

There are two implicit assumptions underlying
reaction (19) as the sole consumption sink for the ace-
tic acid: 1) most or all of the CO2 is evolved as gas
from the reaction solution; 2) the amount of HCO3
formed from any residual CO2 present in solution is
negligible. Indeed, some gas evolution is observed
during the experiment. The ionization constant for
carbonic acid (K, equal to 4.3 10-7 at room tempera-
ture) may be used to estimate the amount of bicarbo-
nate ion present, i.e.

fH O HCO-]
[H 2 3 ][CO -cK (23)
Thus, at the beginning of the reaction (when very
little CO2 should be present in the first place) when
the pH is 3.09, from Eq. (23) the ratio of the concen-
trations of bicarbonate ion to carbonic acid is about
4 10-, and hence the former is truly negligible. At
the final pH of 5.90, however, this ratio is equal to
0.34. Reaction (20) may thus have an impact on the
overall process under these conditions. The fact that
this latter reaction is unimolecular in acetic acid,
whereas the assumed sole consumption reaction (19)
is bimolecular with respect to the same species, may
conceivably be related to the apparent intermediate
reaction order of 3/2 observed.

a = instantaneous total surface area of the antacid
tablets, cm2
C = concentration, gmole/liter
D = initial diameter of an antacid tablet, cm
f(r) = function of r, defined by Eq. (12)
H = initial thickness of an antacid tablet, cm
h = instantaneous thickness of an antacid tablet,
KA = ionization constant for the aqueous dissocia-
tion of acetic acid
Kc = ionization constant for the aqueous dissocia-
tion of carbonic acid
k = combined mass transfer and kinetic rate con-
stant, (liter/gm mole)'2/(cm2 min)
ki = forward reaction rate constant for the aqueous
dissociation of acetic acid


k2 = reverse reaction rate constant for the aqueous
dissociation of acetic acid
I = constant (= y/p), cm
M = molecular weight, g/gmole
m = number of antacid tablets present
N = moles of a substance, gmoles
n = order of process with respect to hydronium ion
pH = -log(CA)
R = initial radius of an antacid tablet, cm
r = instantaneous radius of an antacid tablet, cm
t = time, min
V = volume of reaction solution, liters
x = mass fraction
a = aspect ratio of an antacid tablet (= H/R)
P = constant defined by Eq. (11)
y = constant defined by Eq. (10), cm
p = density of a tablet, g/cm3
[ ] = concentration of, gmole/liter

A = acid (H3O+)
B = base (CO3=)

O = initial condition (t = o) D

book reviews

COAL LIQUID MIXTURES: Proceedings of the
Third European Conference
edited by T. J. Pierce, et al
Hemisphere Publishing Corp., 79 Madison Ave.,
New York, NY; 409 pages, $82.50 (1988)

Reviewed by Alex E. S. Green
University of Florida

Published by the European Federation of Chemical
Engineers (EFCE Publication Series No. 64, EFCE Event
No. 372), this book is a report on a two day symposium
held in Malmo, Sweden, 14-15 Oct 1987 (ISB No. 85295
2139). CLM-2 the 2nd European conference on this topic
held in London (1985) reflected optimism on the future of
CLM as well as a consolidation of works on the stability,
atomization, and combustion characteristic of slurry
technology. On the other hand, CLM-3 recognizes that
the 1986 fall of world oil prices has generally delayed the
commercial realization of CLM. The papers presented
provide mostly an update of technological developments
on coal water mixtures (CWM). They cover slurry
preparation at pilot and commercial scales, slurry atom-

ization including an analysis of droplet mechanisms and
influence of dispersants, and slurry combustion including
an assessment of mineral matter transformation and re-
action kinetics. Most of the CWM combustion programs
in Europe are carried out on converted utility and indus-
trial boiler plants. Whereas most USA CLM programs
have emphasized the use of premium grades of coal, the
European program gives considerable emphasis to the
use of low-grade fuels of high ash content where local
economic factors are favorable including coal washery
fines. Commercial application of slurry to steam genera-
tion, to aggregate cement kiln firing and to open hearth
furnaces are discussed in considerable detail reflecting
the technological maturity of the use of CWM.
Economic and marketing aspects of coal liquid mix-
tures are nicely summarized in Chapter 27 by N. Lood on
"Coal Water Fuel (CWF) in a Changing Market." He
points to the increases of oil prices in 1973 and in 1979
which focused attention on the need to develop alterna-
tives to oil and to the recent emergence of CWF as the
leading candidate. He discusses CWM fuels advantages
in terms of high coal reserves, market stability, the
preservation of the fluid infrastructure, the safety and
environmental cleanliness, and the fact that existing oil
boilers could be utilized with minimal changes and low
retrofit costs.
The oil price collapse of 1986 from the $30 per barrel
range to the $10 per barrel range had a major impact on
CWF. The reaction in the USA where market forces are
predominant was almost immediate, and most develop-
ment projects were shelved or drastically scaled down.
This conference proceedings suggests that Europeans
have taken a longer range perspective and are giving
somewhat greater attention to the security of energy
supply upon the stability of European economies vis-a-
vis actions of the OPEC cartel. Of the member states in
the European Economic Community, Italy is making the
greatest progress in the use of CWF. From the continued
advancement of CWM technology in Europe it would
appear that the technological lead which the US had in
1985 might have been transferred abroad. The recent
Clean Coal Technology program might, however, restore
the US position.
This reviewer finds it difficult to understand why co-
combustion of coal water fuel with natural gas has re-
ceived practically no attention in Europe. Natural gas is
available from the USSR, Northern Africa, and the North
Sea, and its price tends to track the price of oil. Co-com-
bustion of coal water fuel with natural gas (CWG fuel)
provides advantages in the form of emission reduction,
energy enhancement, flame stabilization, and other tech-
nological benefits (see An Alternative to Oil: Burning Coal
with Gas, University Presses of Florida, 1981, and Co-
Combustion ASME FACT, Vol 4, 1988, HOO443). In this
reviewer's opinion, when oil prices climb above $20 per
barrel again, CWG fuel will be the most competitive al-
ternative to oil from environmental, energy, and eco-
nomic standpoints. O


1( 1




University of Waterloo
Waterloo, Ontario, Canada N2L 3G1

D PROFESSORS PAY lip service to teaching mathe-
matical statistics but leave the philosophy of the
"scientific method" unlearned? We provide our stu-
dents with example after example of "sanitized" mod-
els in the form of mathematical correlations obtained
from "dirty" data after a liberal application of scien-
tific hygienics. Such filtering of information requires
a mature understanding of error analysis, even though
we treat the variability of our data as if it should be
Most chemical engineers have used empirical equa-
tions like the Sieder-Tate relationship and, after
checking that the variables are in the permissible
range, they tend to ignore the accuracy of the pre-
dicted values. If pressed, most would admit that some
level of uncertainty is present that is hopefully toler-
able. However, if asked about E = mC2, many would
say, "That's not an empirical equation: it represents
physical reality," and they might be reluctant to agree
that there is any uncertainty in it.
Engineers, however, must work in the real world

Bob Hudgins is a professor of
chemical engineering at the University of
Waterloo and holds degrees from the Uni-
versity of Toronto and Princeton University. ;4, *6-
He teaches reaction engineering, staged
operations, and laboratories that go with
them. His research interests lie in periodic
operation of catalytic reactors and in the im-
provement of gravity clarifiers. /
Park Reilly holds an appointment as
professor (retired) of chemical engineering
at the University of Waterloo. He graduated
from the University of Toronto in 1943 and
worked in industry until 1967 when he
joined the faculty at the University of Wa-
terloo. He studied statistics at the University
of London and received a PhD in Statistics
in 1962. His research and publications are
in the area of applied statistics.

Copyrllht ChE Division ASEE 1989


FIGURE 1. Measurement-the Precarious Bridge
with measured quantities. We, as engineers, are also
forced to recognize that no communication exists be-
tween the real and the mathematical worlds except
through some sort of measurement (see Figure 1). Al-
though we can make all sorts of flights of fancy about
E = mC2, they have no meaning in the world of things
that we touch and manipulate except through the
single bridge provided by measurements. Further-
more, measurements (except in trivial cases) are al-
ways contaminated by error. For example, if we set
out to check how closely E = mC2 corresponds to
reality, we find insurmountable difficulties in defining
the symbols so they can be perfectly verified in the
real world. One of these concerns the concept of mass.
How can it be determined except by comparison and
how can that comparison be made on an indefinitely
fine scale?
To step from this into the real world of chemical


experiments is to meet error head-on. Students in an
undergraduate laboratory have spent most of their
scientific lives on the abstract side of the measure-
ment bridge. They tend to think that there are only
two options if the results do not agree nicely with the
theory: 1) there is something wrong with the equip-
ment or its value in elucidating the theory, or 2) the
real and the mathematical worlds cannot be bridged,
so theory is of little value in the real world.
A critical examination of undergraduate labora-
tories reveals that most of the experiments are cont-
rived to illustrate one or more points of physical or
chemical theory. Statistical design and analysis are
usually considered nuisances at best. "Error
analysis," when it is carried out, consists most often
of an examination of what the maximum error might
be, without regard to any evaluation of what typical
errors could have occurred.
In this vein, the most powerful method of assess-
ing what errors are likely to occur is that of replication
of experimental trials. In the atmosphere of the labo-
ratory, students regard this as a waste of time.
We believe that it is possible to design under-
graduate experiments in such a way that the true re-
lationship between theory and practice can be re-
spected, the presence of error can be accounted for in
a rational manner, and at the same time the physical
or chemical point can be made. Above all, we believe
that each experiment can be a learning experience in
experimentation as such, so that the students gain
some skill and knowledge which will help them in any
future experiments.

As an example of an experiment with considerable
scatter in the measurements, let us examine a gas
absorption experiment, specifically the one used in the
undergraduate curriculum in the Department of
Chemical Engineering, University of Waterloo. In
this experiment, air picks up a predetermined quan-
tity of acetone vapour and enters the bottom of a
packed tower of Raschig rings where it meets fresh
water entering from above. The water leaving the gas
absorber is sampled and analyzed chromatographi-
cally for acetone. The results are worked up (see Fig-
ure 2) into a plot of the height of an overall gas trans-
fer unit vs. the mG/L quotient, in which m is the
Henry's Law coefficient for acetone in water, G is the
air flow in moles/time, and L is the water flow in
moles/time. The final data sets of three different
blocks of seven experiments each are plotted in Figure
2. Ordinarily, a student group will obtain only about

Above all, we believe that each experiment can be a
learning experience in experimentation as such, so that
the students gain some skill and knowledge which
will help them in any future experiments.

? 0'

FIGURE 2. Height of a transfer unit (based on overall
gas) vs. mG/L for acetone absorption from air into water.
Three different symbols represent three different ses-
sions of data collection. Least-squares line is shown for
all points.

six points in a day's work. These usually represent
the sole basis the group has for an entire report on
gas absorption.
Scattered data like those in Figure 2 are usually
subjected to a scathing sort of error analysis by stu-
dent groups. Verdict: "bad data" or "defective exper-
iment" or "waste of time." Recommendations: "re-
place the gas chromatograph" or "check the pumps"
or "put controllers on all the flows." The word about
the gas absorption experiment soon reaches incoming
classes, with the result that students new to the
laboratory have to be coaxed or coerced into selecting
gas absorption as an optional experiment. After all,
who cares about error analysis in the face of what is
known via the grapevine? Replicate shmeplicate-the
experiment's a dud. Everyone knows that!
In their defense, our students have a point. The


Ht,OG values in the centre of Figure 2 scatter over
nearly a three-fold range. Also, students take only
about six points in a single lab period, often giving the
appearance of incoherence to their already sparse
data. However, they almost always fail to notice that
the data they have taken are not much, if any, worse
than what appears in the chemical engineering litera-
ture. For example, Figure 3, sketched from the
Chemical Engineers' Handbook (Perry and Chilton,
1973), shows that the mass transfer coefficient (i.e.,
height of a transfer unit) has a two- to three-fold vari-
ation at a given liquid flowrate (i.e., constant
Reynolds number). Except for a little inexperience
with the equipment, undergraduate students probably
do almost as well in experimental technique as those
who have contributed to posterity's data pool in the
handbooks. Nevertheless, somewhere in our con-
sciousness the myth persists that data points must lie
on a clean line of the sort that we plotted in physics
lab the day we measured current against voltage.
Thus, we conclude that student engineers who find
themselves confronting scattered measurements re-
ally don't understand experimental error. Changes
are needed to help them appreciate more fully the
structure of the data they are encountering in such
experiments. Unfortunately, laboratory experience
can fortify those durable prejudices about "good ex-
periments" and "bad experiments" as well as encour-
age an informed interpretation based on statistical
error analysis. Much depends on the experimental de-
sign and the way students are encouraged to regard
their results.
Specific ways to encourage clear thinking about
error analysis are:
1) Design into the undergraduate labs some opportunities to
view "real" rather than "contrived" phenomena in chemical
engineering experiments.
2) Design out the features that shield students from confronting
the large variability which is common in complex chemical
engineering systems. Instead, promote replication and other
statistical devices which help deal with variability as it exists.
3) Require students to become familiar with the chemical en-
gineering literature that shows the kind of variability that is
common to various systems.
4) Teach students to resist the temptation to try to explain "ev-
erything" about complex engineering systems.

In view of the above statements, it is clear that
the gas absorption experiment referred to previously
needs redesigning. The various items in such a rede-
sign are numbered in keeping with the above four

1) The gas absorption experiment already offers



10 100 1000
FIGURE 3. Mass transfer coefficient kg vs. gas flow rate
G for gas absorption (after Perry and Chilton, 1973).

students a chance to see something real. For example,
acetone is a material that has a high affinity for water,
so water is a logical medium for use in removing
acetone vapours from the air. Also, a glass column is
used to display the intermingling of the gas and liquid
flows over the packing. This provides a sense of real-
ity to the experiment. The only contrived aspect of
this experiment is its scale, which is kept small for
reasons of convenience.
2) The major block to students' perception that
scatter is the rule in complex chemical engineering
systems is probably the fact that in most of our teach-
ing we tend to use deterministic models without men-
tioning the associated error. Therefore, the student
who discovers a lot of scatter in an experiment may
conclude that experiments are less trustworthy than
The misunderstanding of scatter is aggravated by
the fact that students are able to obtain relatively lit-
tle data on the gas absorber during a single laboratory
session. Often, if only two of, say, six runs are done
under replicate conditions, and the two observations
are quite different, students will view the equipment
as behaving capriciously.
A further difficulty occurs in the gas absorption
experiment because of the fact that a G/L ratio tends
to compress the range of the data. For example, if
both G and L are doubled, the mG/L ratio thus re-
mains constant. This tends to reduce the experimental
data base.
One helpful idea in redesigning this undergraduate
experiment is to reduce the number of variables by
one; for example, by maintaining G constant and
varying L. This will eliminate the compression of the
data base by the use of the G/L ratio as well as reduce
Continued on page 119.



International Chemical Engineering


ISSUE 1961-1985

Celebrating the first 25 years of INTERNATIONAL CHEMICAL ENGINEERING, AIChE presents this special volume
highlighting major contributions by internationally recognized and acclaimed researchers who have had a decided
impact on innovative work in chemical engineering.
This collection presents a selection of translations of important papers previously published in INTERNATIONAL
CHEMICAL ENGINEERING which have contributed to advances in research in such areas as combustion and detonation,
transport theory, catalysis, and mass transfer. They reflect the changing character, broadening scope and international
nature of chemical engineering research.
SAMPLE CONTENTS INCLUDE: On the nature of thermal motion in liquids.
A.S. Preduoditelev (USSR)
The kinetics of steady-state complex reactions.
M.I. Temkin (USSR)

Continuous expression of slurry in a screw press.
M. Shirato, T Murase, M. Iwata, N. Hayashi, & Y. Ogawa (Japan)

Electrochemical determination of liquid-solid mass transfer in a fixed-bed
irrigated gas-liquid reactor with downward cocurrent flow.
Ch.B. DeLaunay, A. Storck, A. Laurent, & J.-C. Charpentier (France)

Catalytic reduction of nitric oxide with hydrocarbons.
S. Kasaoka, H. Tsumaki, & T. Kitamura (Japan)

Stability and dynamics of heterogenous catalytic reaction systems.
G. Eigenberger (Federal Republic of Germany)

Deactivation of catalysts. I. Chemical and kinetic aspects.
P. Forzatti, G. Buzzi-Ferraris, M. Morbidelli & S. Carra. (Italy)

Microbial processing of petroleum for the production of food.
J. Bathory & E. Vamos (Hungary)

Softcover. $50 248 pp. Foreign extra: $6
(Special 20% discount to 1989 subscribers to International Chemical Engineering.)

An important addition to the reference shelf of the practicing engineer.
An important study tool for undergraduate and graduate students.

Send Orders to: AIChE Publication Sales, 345 East 47 Street, New York, NY 10017. Prepayment in U.S. funds required
(check, international money order or bank draft drawn on a foreign bank with a New York City office). VISA or MasterCard
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OHE England.)





University of Sydney
N.S.W. Australia, 2006

LABORATORY WORK IS regarded as a vital part of
the unit operations course at the University of
Sydney. Exposed to the real world of the laboratory,
students discover the importance of concepts other
than the mathematical models that tend to be taken
as the be-all and end-all of understanding. Students
apply their ideas to a complex plant which must be
approached with preparation and respect. In planning
and executing their activities, they are inculcated with
a sense of discipline and leave the sessions with a feel-
ing of accomplishment. Properly done, the laboratory
can also be a lot of fun.
With this in mind, the department has built a
three-stage counter current leaching rig designed by
the author. The new rig was intended to overcome the
problems of previous models which were beset by poor
performance and frustrating breakdowns. Its design
contains a number of attractive features which help to
make the laboratory both satisfying and instructive.

Previous models of the leaching rig had several
unattractive features. Motors and bearings suffered
from exposure to wet and dusty conditions around
the mixers and settlers. Underflow was removed by
valves which were either fully on or fully off, with the
resultant discontinuity of flow leading to frequent
blockages. The conventional overdriven impellers in

Wayne Davies spent two years as a
lecturer in the department where he had
previously received both his bachelors and
PhD degrees. Apart from his interest in un-
dergraduate teaching using the practical
"hands-on" approach, he is also interested
in applications of both conventional and
novel unit operations to the processing of
biological products and their long-term
storage and stability.

Copyright ChE Division ASEE 1989

The new rig was intended to overcome the problems of
previous models which were beset by poor performance
and frustrating breakdowns. Its design contains a
number of attractive features which help to make the
laboratory both satisfying and instructive.

FIGURE 1. The whole rig. Three sets of mixer/settlers are con-
nected by tubing to create countercurrent solid/liquid flow.
Feed slurry enters the bottom mixer (RHS). Leached solids are
pumped from the base of the top settler (LHS). Feed water
enters the top mixer and the strong product solution emerges
from the overflow of the bottom settler. Underflows are con-
veyed upwards by pumps mounted behind the acrylic panel.

each mixer could not be restarted if they were sub-
merged under sedimented solids, and there was virtu-
ally nothing instructive to see because the vessels
were opaque. The new rig is designed around a trans-
lucent acrylic panel which separates both mixers and
settlers (the "wet side") from the motors, pumps,
bearings, and electrics (the "dry side") (see Figure 1).
This panel also acts as a convenient diffuser for a back-
light so that the behaviour of the slurry in the vessels
can be clearly seen. The vessels are a "flat cell" design
in order to simplify construction and to simulate the
usual cross-sectional view of such apparatus seen in
texts and on the chalkboard. Mixers employ exter-
nally mounted centrifugal pumps situated on opposite
sides of the acrylic panel (see Figure 2). When the
pumps are started with settled solids in the vessel,



the same volumetric flowrate. The excellent pumping
characteristics obtained allow the underflow pumps to
do dual service, and they also convey the underflow
up to the next mixer stage (Figure 1). All other flows
can gravitate from one vessel to the next by tubing
whose angles of fall were chosen to avoid blockages
by solids build-up. Thus the solids-rich streams from
mixer to settler are angled at 280 while the solids-poor
settler overflows are angled at only 8.50. Instrumenta-
tion includes an electronic tachometer on the under-
flow pump shaft in order to reproduce flowrates and
a variable area flowmeter for the feed water which is
delivered from a constant head tank.

Routinely, feed consists of a slurry of alumina (av-
erage particle size 65 jm) in water containing about
40 ppm fluorescein as the solute. The slurry is continu-
ously mixed in a 200 litre tank, and a peristaltic pump
delivers the feed to the first stage mixer where it
meets the overflow from the second stage settler.
Overflow from this mixer moves to the first stage set-

FIGURE 2. Stage 2 mixer showing pentagonal shape. Slurry to
the external pump agitator leaves the vessel about halfway
up on RHS. Slurry returns from the pump via the angled tube
at the bottom. Incoming overflow is via the top tube (LHS),
incoming underflow is via top tube (RHS) and mixed slurry
leaves the vessel via overflow tube (LHS).

clear supernatant initially enters the pump and the
return flow fluidises the sediment. After a short time
the entire contents are fully resuspended. The pen-
tagonal shape of the mixers encourages turbulent con-
ditions everywhere in the vessel and the motors are
overrated in order to cope with concentrated slurry
(up to 35% v/v settled solids). The settlers are de-
signed similarly. Natural consolidation of the sedi-
ment occurs in the steep V-bottomed shape of the ves-
sel (see Figure 3) and the inclined parallel plates in-
crease the effective surface area by a factor of about
three over that of the air/water interface. A perfo-
rated plate delivers feed to the parallel plate settling
section to help smooth pulsations in feedrate.
Almost continuous removal of the underflow is
achieved by peristaltic pumps situated on the dry side
of the acrylic panel. These are driven by a common FIGURE 3. Inclined plate settler showing wedge-shaped inlet
shaft from a variable speed gearbox and motor. Be- chamber (LHS), underflow removal tube (bottom) and over-
cause timing belts connect the shaft to the pumps, flow (RHS) as well as vertical tube conveying underflow to
there is no slip, and each pump delivers almost exactly next mixer stage above.


tler, which separates the solids-rich underflow, which
moves to the second stage mixer. The process is re-
peated over three identical stages. A stream of solute-
poor solids emerges from the third stage settler, and
the strong product solution emerges as overflow from
the first stage settler. The leached solids are collected
in a 200 litre receiver tank. When full, this tank is
simply interchanged with the now-empty feed tank
and extra dye is added. Feeding slurry instead of solid
avoids the need to dry the material between labora-
tory sessions, which was far too laborious and time-
Set up this way, the operation is strictly described
as counter-current washing since the solute dye is al-
ready in solution and not combined with the solid.
True leaching can be performed by feeding real min-
eral solids directly. Dye concentration is simply deter-
mined from its absorbance at 491 nm. Solids concen-
trations are most conveniently expressed as the vol-
ume fraction of the wet sediment after centrifuging (5
min, 1000 xg). A correlation between mass fraction
and volume fraction is obtained experimentally by stu-
Choosing the operating parameters follows a set
logic which is determined by the design limits of the
equipment. The best way to start is to select the feed-
rate of slurry and its concentration, which may be in
the range 3 to 26 ml/sec and 20% to 60% (v/v wet
solids), respectively. The feedrate of solids then dic-
tates the minimum underflow rate from the settlers.
The absolute upper limit of solids in the underflow has
been found experimentally to be 85% (v/v), as any
limit greater than this will stall the pumps. For reli-
able operation, a practical limit of 75% offers a margin
of safety.
The minimum water flowrate is determined as the
amount necessary to prevent solids concentration ex-
ceeding the design limit of the mixer pumps, which
has been found to be about 35% (v/v). This is done by
a mass balance around the third stage mixer. Once
these minimum requirements have been found,
greater values for water flowrate may be set without
problem and the underflow rate can be increased to
the point where its volumetric flowrate just equals
the combined volumetric flowrates of the feed water
and the feed slurry. Naturally enough, optimal condi-
tions usually mean that the underflow is as thick as

In the two years that the rig has been in service,
it has logged over one hundred hours of operation


Solids Concentration (% v/v)
Flowrate (ml/sec)
Dye Concentration1 (ppm)

Water Flowrate (ml/sec)

Solids Concentration (% v/v)
Flowrate (ml/sec)
Dye Concentration (ppm)

Product Stream
Flowrate (ml/sec)
Dye Concentration (ppm)
Recovery2 (%)

Solids Concentration (% v/v)







13 32

1. Dye concentration is expressed in the supernatant.
2. Based on a balance of the dye in the feedrate less the amount in the

without any problems. Most experimental runs are
based on conditions of constant flowrates and composi-
tions, the performance of the rig being determined at
steady state. For most runs starting with no dye or
solids in the system, this takes about fifty minutes to
achieve within reasonable error, much less if run
parameters are allowed to change dynamically.
Table 1 shows the results of two runs which dem-
onstrate typical extremes of operation. In Run 1 the
feed flowrate is modest and the water flowrate is
fairly generous, whereas Run 2 operated close to the
design limit of both mixer and underflow pumps, with
high feed flowrate and minimal water flowrate. Run
1 achieved almost total (99%) recovery of the solute
but at relatively low concentration (15.7 ppm). In Run
2 the recovery was less (95%) but the product concen-
tration was more than double (34.7 ppm). The solids
concentration in the underflows was fairly thick in
both runs (72% v/v), and the settlers were still produc-
ing a workable underflow with sedimented solids up
to 150 mm deep. In Run 2 the mixers were close to
their design limit for solids concentration (32% v/v),
but in Run 1 the mixers were hardly stressed at only
13% (v/v). Because of its greater water flowrate, Run
1 achieved a relatively clean washed solid with only
0.86 ppm solute in the accompanying solution. Under
nearly all conditions studied so far, the rig returns
better than 2.5 ideal stages, or 83% stage efficiency.



The leaching rig described here offers students a
worthwhile laboratory experience due to its reliable
and predictable performance. As long as a few prelim-
inary calculations are done to set the operating
parameters correctly within design limits, the run can
be expected to proceed without a hitch. Failure to
observe a simple set of logical rules will inevitably
lead to disaster, with wasted hours of misery in un-
blocking underflow tubes awaiting the unprepared.
Experimental tasks using the rig can be made sim-
ple or sophisticated to suit the ability of the group. As
most experiments attempt to demonstrate perform-
ance at steady state, one task set can be to show that
steady state has been achieved within experimental
error. More advanced questions involve adding
economic constraints, e.g., students may be told that
the solute stream is the valuable product and that
overall profitability of the operation is improved by
the total recovery of the solute but is diminished as
the stream becomes more dilute. Additional con-
straints may be that the operating costs of the opera-
tion increase as some function of the feedrate. With
these considerations in mind, students are asked to
perform an optimisation of the operation and then to
make the rig work accordingly.

The apparatus described here represents the re-
sult of an integrated approach to design with an em-
phasis on teaching. The rig is functional, fits well with
theory, and needs little maintenance. Its ultimate util-
ity is limited only by the imagination of the user.

I would like to thank the staff of the department,
especially Mr. D. Trevaskis, who helped with many
invaluable suggestions during the design and con-
struction of the rig. I am also indebted to Mr. P. Kam-
lade for the experimental results which he obtained as
part of his graduation thesis and to Associate Profes-
sor D. Bagster for critical review of the manuscript.

Coulson, J. M., and J. F. Richardson, Chemical Engineering,
Vol. 2, Pergamon Press (1978)
Kelly, E.G., and D. J. Spottiswood, Introduction to Mineral
Processing, Wiley and Sons (1982)
Taggart, A. F., Handbook of Mineral Dressing, Wiley &
Sons (1944)
Wills, B. A., Mineral Processing Technology, Pergamon
Press (1979) 0

Continued from page 85.

the needs of a diverse group of students given the
present economic and social climate. A survey of the
students who took this course reveals that while six
have jobs related to product development, only four
of the twenty-eight (four are undecided) have ac-
cepted jobs which directly involve work on chemical
processes. One has accepted a job as a financial
analyst with a major New York investment bank. The
rest are either going to graduate school (three in
chemical engineering, one in law, and one in business),
the naval officer program, or will work for firms that
specialize in business systems and consulting. Clearly,
the present format offered more to this particular
group of students than would a course which included
only topics traditionally considered as process design.
All indications are that the course was successful
in meeting the intended goals. However, it must be
noted that this was due in large part to the effort of
the students. They worked hard for the first part of
the semester to finish the design project. They also
exerted significant effort through the end of the
semester to make the product design project worth-
while, even though most of them had already accepted
The structure of the present course may break too
far from tradition for the personal taste of many chem-
ical engineering faculties. However, the time could be
right to reconsider the content and structure of pro-
cess design courses which were conceived when the
majority of chemical engineers were employed in de-
veloping and operating large chemical processes.


1. ProcessT Simulation Program, Simulation Sciences,
Inc., Fullerton, CA
2. Wei, J., in the special supplement to Chemical Engi-
neering Progress, page 3, January (1988)
3. Christensen, J. J., "3M Award Lecture" presented at the
1987 Chemical Engineering Summer School, Southwest-
ern Massachusetts University
4. Felder, R. M., "The Generic Quiz: A Device to Stimulate
Creativity and Higher-Level Thinking Skills," Chem.
Eng. Ed., 19, 176 (1985)
5. Felder, R. M., "On Creating Creative Engineers," Eng.
Ed., 77, 222, (1987)
6. Executive summary of the final report: "Quality in En-
gineering Education Project ASEE," Eng. Ed., 77, 17,
7. Massachusetts Institute of Technology, Commission on
Industrial Productivity, Michael L. Dertouzos, Chair-
man. Interim report (1988) J



stirred pots


A Continuing Tradition at Carnegie Mellon University

Carnegie Mellon University
Pittsburgh, PA 15213

ACH YEAR THE graduate students in the chem-
ical engineering department at Carnegie Mellon
University prepare for the Annual ChEGSA (Chemi-
cal Engineering Graduate Student Association) Sym-
posium, a unique event among major universities in
the United States. It was held for the tenth time in
During the symposium, which takes place over two
days each fall, the graduate students present papers
based on the research they are conducting in the de-
partment. The symposium covers a broad range of
topics in chemical engineering, reflecting the varied
research interests of the graduate students and their
thesis advisors. The presentations allow the students
to exchange ideas, develop communication skills, and
compete for awards. Students and faculty within the
department attend the event along with industrial
representatives and other guests. Although it is sup-
ported by faculty and industry, the symposium is plan-
ned, organized, and run entirely by the students,
which, we believe, makes it exceptional.
A report of the first symposium, held in 1979, ap-
peared in the winter 1981 issue of Chemical Engineer-
ing Education. The purpose of this article is to explain
how the event has evolved since then, what its present
objectives are, how it is planned and organized, what
its current format is, and how it has contributed to
the educational goals of the students. We hope that
some of this information may be of use to others who
wish to initiate a similar event.

The primary purpose of the symposium is to pro-
mote good communication skills among the graduate
students. A panel of judges evaluates the presenta-
tions and the accompanying written papers. This ex-
perience in presenting talks and in writing technical
papers is obtained in an environment similar to that

encountered at professional meetings, but without the
associated pressures. Furthermore, due to the prox-
imity of the event to the annual AIChE meeting,
many students take advantage of the symposium to
practice their talks in a formal setting under a pre-
scribed protocol.
Another objective of the symposium is to provide
a means for interaction between industry and the de-
partment. Fall is the recruiting season for many com-
panies, and recruiters often try to schedule their cam-
pus visits to coincide with the symposium. For com-
panies, the event provides an opportunity to hear
about current research in the department, while for
the students it is a chance to create a favorable
impression on the industrial representatives.
For the incoming graduate students who have just
joined the department, the symposium provides an
opportunity to hear some of the more senior students
speak about their research. This aids them in selecting
an advisor (usually a month later) and also illustrates
to them that research must be presented as well as
Perhaps most important of all, especially in an age
of increasing specialization, the symposium allows the

Ajay Modi is in the PhD program at
Carnegie Mellon University. He obtained
his BSc(Eng) at Imperial College, London,
and his MS at Northwestern University. He
was the 1987 Symposium Chairman.

Paul Bowman obtained his BS at Vir-
ginia Polytechnic Institute and State Uni-
versity and is presently in the PhD program
at Carnegie Mellon University. He was the
1986 Symposium Chairman and was the
winner of the Parfitt Award in 1986 and the
First Awards in 1986 and 1987.
Copyright ChE Division ASEE 1989


students to gain a perspective and appreciation of
what is being done outside of their own fields. The
research topics of our graduate students are ex-
tremely diverse and cover such areas as colloid sci-
ence, semiconductor processing, catalysis, reaction
engineering, computer-aided process design, bioen-
gineering, process optimization, polymer rheology,
and electrochemical engineering, to name just a few.
Most students will at some point in their lives be-
come involved in the administration of a major event.
The symposium provides the kind of experience that
will be useful to them, including tasks like fund-rais-
ing, budgeting, scheduling, designing a program book-
let, chairing sessions, and organizing a reception and
banquet, in addition to the more mundane activities
such as memo-writing and correspondence. Consider-
able skills in administration and leadership are de-
veloped in coordinating the symposium.

The idea of a symposium was first suggested in
1979 by Tomlinson Fort, who was then head of the
chemical engineering department. Due to the strong
enthusiasm generated by that first symposium,
ChEGSA turned it into an annual event. Its format
and organization, however, have undergone a number
of changes.
Industrial participation in the event, which was
first sought at the second symposium, has been most
encouraging. An average of fifteen companies has par-
ticipated each year. Their reaction to the symposium
can best be illustrated by the words of James
Aderhold of the Amoco Oil Company:

I found this annual event to be very beneficial, and I
would recommend it strongly to others. Not only did it give
me the opportunity to see what is being done in the several
research areas at CMU, but it also allowed me to see some of
the students who I would later interview in recruiting for the
Amoco Research Center. Both times I attended, I found the
proceedings to be very well organized and the speakers to be
well prepared.

The students' presentations were first com-
plemented by a speech given by a keynote speaker in
1984. The speakers have included Edward Cussler
(University of Minnesota), Dan Luss (University of
Houston), Alexis Bell (University of California, Ber-
keley), Eduardo Glandt (University of Pennsylvania),
and George Keller (Union Carbide Corporation).
The 1986 symposium marked the awarding of the
first "Geoffrey D. Parfitt Memorial Award for Excel-
lence in Oral Presentation." Dr. Parfitt, who passed
away in 1985, had been a professor of chemical en-

gineering at Carnegie Mellon since 1980, and to honor
his memory, ChEGSA established this award which
is presented to the student judged to have the best
oral presentation. The award differs from the tradi-
tional First Place Award in that it does not involve
the judging of a written paper.
The foregoing are the major changes in the sym-
posium since it began. Numerous minor refinements
and modifications have also been made.

The idea of a symposium was first suggested in 1979
by Tomlinson Fort .... Due to the strong enthusiasm
generated by that first symposium, ChEGSA
turned it into an annual event.

Preparation involves a lot of work and begins at
least six months prior to the symposium. The chair-
person starts by assembling a committee of student
volunteers and then setting a date for the program.
Various companies are then invited to participate in
the event, either by sending representatives or by
making a contribution, or both. An invitation to the
potential keynote speaker is also made at this time.
A call for papers is posted about three months be-
fore the symposium. To facilitate the design of the
program booklet, all participants are asked to send
their titles and abstracts via electronic mail according
to a specified format. This enables the booklet to be
compiled without rewriting since all of the entries con-
form to the same style.
A communications workshop is conducted a few
weeks before the symposium. The workshop covers
ways to improve presentations, gives hints about ef-
fective public speaking, and presents information
about slides and audio-visual equipment.
The two weeks before the symposium are hectic,
with many last-minute arrangements having to be
made. A wine and cheese reception is hosted at the
end of the event, and an awards banquet is held a
couple of weeks later. Speech making (especially by
the faculty) is kept to a minimum, and the event is a
enjoyable conclusion to the symposium.
The symposium is divided into four sessions, with
a morning and afternoon session on each day. Each
talk is restricted to fifteen minutes, with an additional
five minutes for questions and audience discussion.
The keynote speech lasts an hour and has traditionally
been given at the end of the morning session of the
Continued on page 105.


n classroom


The Engineer's Essential One-Page Memo

University of South Carolina
Columbia, SC 29208

MOST UNDERGRADUATE engineering students
believe that technical excellence is the sole
measure of a good engineer. The belief is nourished
by academic schedules that promote technical training
almost exclusively and it is frequently carried over to
a student's first industrial position. Once on the job,
however, new engineers find (much to their surprise)
that managers rate their performances not only on
technical expertise but on how well they communicate
that expertise. They find themselves, in short, writing
. and writing often. Some statistics we have seen
(for senior engineers) show that engineers spend an
average of 24% of their time writing [1].
Fortunately, engineering educators have begun to
recognize that communication skills play a major role
in a new engineer's success in industry, and many en-
gineering professors regularly include practice in
writing in unit operations and senior design courses.
However, this writing experience all too often focuses
on major reports while industrial experience has
shown that almost ninety percent of the writing an
engineer produces is in the form of brief (often one
page) memoranda or memos.
It cannot be taken for granted that a newly-hired
engineer will automatically know how to compose con-
cise, organized, and effective memos. In this paper
we will describe the essential elements of memos,
suggest a basic format for organizing memos, present
two problems that technical specialists' memos seem
particularly susceptible to, and include a memo assign-

... engineering educators have begun to recognize that
communication skills play a major role in a new
engineer's success..., and many engineering professors
regularly include practice in writing in unit operations
and senior design courses.

Copyright ChE Division ASEE 1989

Rob Adams McKean is president of
Chart Communications, a consulting firm
specializing in executive and technical
communications and computer training. As
a consultant to industry and government,
he has led over two hundred training
seminars for such companies as Honeywell
Bull, Gillette, Duracell Research Center, MIT
Lincoln Laboratory, and Dynamics
Research Corporation.

Emil L. Hanzevack is an associate
professor in chemical engineering at the
University of South Carolina. He teaches
the senior design course and process
control and does research in computer
applications to chemical engineering. He
was responsible for generating and
administering R&D programs at Exxon
Research and Engineering, where he
worked for ten years.


ment we have used in our senior design classes and
professional development seminars.

Purpose. Organizations spawn multiple forms of
communication, from hallway conversations that end
in handshakes through formal, deliberative docu-
ments. Within this wide range, memos play the role
of interim coordination and agreement. Memos sub-
stantiate and confirm; at other times they crystallize
important positions or attempt to persuade. But in
almost all cases, memos are critical to the orderly
coordination of an organization, and they often result
in action.
A few uses of the memo are

To request information
To give quick trip reports
To present preliminary findings
To suggest new product proposals
To formalize internal agreements
To realign internal policy
To crystalize positions in a succinct form so that
management may formulate policy.


The list could be much longer. It has been our experi-
ence that many companies ask that employees not tie
up their time by composing long reports, even in sit-
uations that traditionally call for reports. Instead,
employees are more often encouraged to adopt the
shorter memo format [2].
Audience. Memos are primarily read by an inter-
nal audience. Indeed, they are sometimes nicknamed
"in-house letters." In practical terms, the "in-house"
portion of the nickname implies that, because they
are talking within the family, memo writers can let
their hair down and express themselves with a degree
of candor and informality not possible in communica-
tions designed for external audiences. It also means
memo writers may employ (within reason) com-
pany shorthand and commonly understood abbrevia-
The "letters" portion of the nickname implies that,
because they are not formal reports, writers can per-
sonalize their memos and reach out to the reader. In
fact, as we shall see, the "human touch" is an impor-
tant element in successful memos.
Level of complexity. We roughly equate level of
complexity with length, and the most useful compari-
son to make is between memos and full-blown techni-
cal reports. Because memos are perceived differently
than reports, readers approach them differently.
Memo readers expect less complexity, fewer details,
and a summarized discussion. In essence, a memo best
serves its purpose when the writer pares discussion
to the essentials, reserving an involved treatment for
the larger canvas of a report.

Timeliness. Memos are "speed documents." They
are usually written under immediate stimulus for im-
mediate consumption. They are not meant to be de-
liberative, elaborately crafted documents. This does
not, however, excuse poorly-organized or poorly
phrased memos; it only underscores their absolute
need to go out under deadline. A late report may be
accepted; a late memo is (almost always) of no use to
In fact, if nothing else, the time-sensitivity of
memos-in which an engineer might need to write
several memos in a given day and still take care of
business-further points out the need to furnish en-
gineering students with memo-writing practice before

Although there are many memo formats, we have
found that the most important aspect of memo organi-

All workers feel a constant demand on their time. So
when readers pick up a memo, they are usually
purposeful, action-oriented readers. The want to know
right away how this particular memo affects them
or affects items under their jurisdiction.

zation-indeed, of organizing any technical presenta-
tion-is to help students to recognize that information
alone is not always the answer, and that any format
is meaningless if the writer merely pours raw informa-
tion into it.
Technical specialists often assume that their mate-
rial has a built-in structure and logic, a chronological
imperative, a necessary level of detail, an implicit
meaning. But that is not true. Facts are usually best
not presented chronologically, and technical and re-
search material has no intrinsic structure and logic,
no necessary level of detail, no implicit meaning. It is
the writer who adds all that, based on the needs of
the document's intended audience.
In a technical environment, for instance, things are
sorted and evaluated, explained, demonstrated, ar-
gued for or against, requested, denied, promised, and
so on. But all this activity takes place against the
backdrop of another person or persons. We sort and
evaluate for others, we explain, demonstrate, argue
for or against, request, deny, and promise-all, again,
with a definite audience in mind [3, 4].
With the reader in mind then, we share with our
students a basic memo format-the three-layer ap-
proach: beginning, middle, and end. Most other memo
formats are just variations of this basic format.

Beginning-the big picture. The corporate com-
munications marketplace is a busy one. All workers
feel a constant demand on their time. So when readers
pick up a memo, they are usually purposeful, action-
oriented readers. They want to know right away how
this particular memo affects them or affects items
under their jurisdiction.
The first sentence or paragraph of the memo
should state explicitly and concisely the objective or
purpose of the memo. Every reader-whether con-
sciously aware of it or not-brings a skepticism to the
memo that might be expressed idiomatically as, "Why
am I reading this memo?" Instead of fighting that
built-in negativity, we urge our students to confront
it directly. Answer that question; tell your reader
exactly why he or she is reading the memo. Establish
context, significance, overall reference, and stay away
from details.


Middle-developing your topic. In the body of
the memo the writer sets forth the discussion, accom-
panied by a moderate level of explanation or detail.
Remember that managers and supervisors do not
want just information; they want that information dis-
tilled to important facts and presented in a rational
structure that makes it accessible and significant.
We tell students that there are two basic methods
of presenting a discussion: the traditional "building
your case" approach, and a decision-making "bottom-
line first" approach. In the first method, the writer
presents facts and develops them gradually, leading
to conclusions and recommendations. In the second
method, the writer states conclusions and recommen-
dations first and then presents the supporting facts
and discussion.
Either method is an effective rhetorical model. The
first is better if the writer anticipates a cautious or
skeptical reaction, while the second is better if the
reader is less interested in the supporting details and
wishes to go straight to the heart of the matter.

End-passing the ball to the reader's court. In
the final paragraph the writer brings the memo to a
fitting conclusion. Ordinarily, this should include the
writer's suggestion for an appropriate follow-up. In a
memo that gives information, the final paragraph
might, for instance, state where more information is
available; or, in a memo that requests information,
state the date the information is needed by.
An important element of the final section is the
"human touch." Because memos can be regarded as
personal documents, it is entirely appropriate (and ef-
fective) for the writer to reach out to the audience.
This does not imply that memos should be anything
other than businesslike, but sentences such as, "I en-
joyed our meeting yesterday and look forward to
working with you in the future," or "Let me know if
I can be of any further help," are ways to bring the
memo around to a personal level and to establish a
productive working connection between writer and

"Stream-of-consciousness" writing. Too many
memos we have seen read as if the writers used
"stream-of-consciousness" writing. The term comes
from literature and is characterized by a continuous
and seemingly unedited flow of thoughts meant to rep-
resent the way a character's mind might really work.
For fiction writers this is fine. Readers enjoy
eavesdropping on the scattered and jumbled flow of

Hand-Out Memo

Inter-Office Memo

Date October 1
To ECHE 465 Class
From Emil L. Hanzevack
Subject Writing Memos

Topresent your next homework assignment
To serve as a model for writingyour own concise and
effective memos
Your homework assignment, due Thursday 10/30, is to
write me a memo concerningthe selection of your topic for the
Final Design Project. Your memo should contain the follow-
ing information: title of proposed project, a brief reason why
you chose this project (e.g., you would like to work in that in-
dustry, you were able to find interesting sources of information
on that topic, etc.), and the particular aspect of the topic you plan
to emphasize (e.g, an evaluation of economic trends over the
last decade, a comparison of two processes or companies, a
recommendation for improving future performance, etc.).
Also include a second choice topic in case several people choose
the same topic.
You may use this memo as a model for your own. The
first sentence should state explicitly and concisely the objective
or purpose. Then a moderate level of explanation or detail
should be given. Supervisors and managers want information
distilled down to important facts, not merely a list of every-
thing you know or have done on the topic. Finally, there is
usually a brief closing as described in the next paragraph.
Note that a good memo is limited to one page (or less). The tone
can be informal, but obviously grammar and spelling must be
correct. It can be done on the computer, by typewriter, or by
hand (if clearly legible).
If the memo is intended to give information, it should
close by stating where more information is available, if
needed. If the memo is intended to request information, it
should make the request and the date it is needed explicit.
Please ask me at the end of this class if you have any ques-
tions. Your memo is due Thursday, October 30.

someone else's thoughts. But in the professional
world, readers don't have the time or the inclination
to follow a torrent of tumbling thoughts. On the con-
trary, they demand focused, well-organized discus-
sions that come to the point and inform them what
action, if any, they must take in response.
Readers of stream-of-consciousness memos get
partway through the text and begin asking, "Why am
I reading this memo?", "What is the writer's point?"
or "What am I supposed to do about this memo?" We
advise our students to avoid stream-of-consciousness
memos. Writers should think before they write. They
should plan, organize, outline, draft, and revise.


Overly-technical language. Commonly called
"technical affectation," this is unnecessarily technical
and jargony language. It is often marked by an imper-
sonal, passive voice style (e.g., 42-word sentences that
begin "It has been found .. .") and sentences so heav-
ily laced with jargon that they are nearly unreadable.
When readers pick up a report, they expect in-
volved discussion, profuse detail, and heavily techni-
cal language, and they bring that degree of commit-
ment to their reading. But memos are considered to
be speed documents, and readers are reluctant to de-
vote any more time than necessary to their reading.
It is very important then that memos be written in an
understandable language-language the intended
reader will quickly grasp.

A major report, on a topic of the student's choice
with the professor's approval, is required for the
senior Chemical Process Analysis and Design course.
This written and oral report is due at the end of the
semester in lieu of a final examination. Near the mid-
dle of the semester the memo in Figure 1 is given to
the students. The memo is self-explanatory and is
handed out without comment to emphasize that point.
It typically results in very few questions, but since
reasonable-to-good memos are turned in two weeks
later, it is considered to be successful.
The memos are discussed in the following class.
Some are returned for revision, and a few of the best
ones are read aloud. This assignment, then, exposes
each senior to the concept of memos before he or she
is asked to produce one in industry.

1. Davis, Richard M., "How Important is Technical Writ-
ing? A Survey of the Opinions of Successful Engineers, "
J. of Tech. Writing and Communication, 8(3), 1978, p. 207
2. Although the passage is too long to quote in its entirety,
Thomas J. Peters and Robert H. Waterman, Jr., in In
Search of Excellence (New York, Warner Books, Inc.,
1984) pp. 150-151, vividly describe the importance one-page
memos have at Procter & Gamble: "The tradition [of the
one-page memo] goes back to Richard Deupree, past
president....Deupree strongly disliked any memoran-
dum more than one typewritten page in length....When
an interviewer once queried him about this, he explained,
'Part of my job is to train people to break down an involved
question into a series of simple matters. Then we can all
act intelligently.'"
3. McKean, Rob Adams, "Taking Aim: How to Target Your
Audience," microEconomics (a publication of The Boston
Computer Society, Boston, MA), 6, 2, 1987, p 10.
4. McKean, Rob Adams, "Coming Through Loud and Clear:
How to Write So Others Will Read You," microEconomics
(a publication of The Boston Computer Society, Boston,
MA) 6,4, 1987, p 16. CI

Continued from page 101.
first day.
The presentations are judged by a panel of judges.
The students are judged on a number of criteria based
both on their speaking ability and the technical con-
tent of the presentation. In addition to giving a talk,
the student may also submit a written paper on the
same topic. The paper is judged on criteria similar to
those used for the presentation.
Awards are given to the top three participants.
These awards are determined by combining the pre-
sentation scores and the paper scores. The top three
awards each consist of a cash prize, an individual
plaque, and a trip voucher which enables the student
to present the work at a professional meeting. The
names of the three winners are engraved on a plaque
located in the ChEGSA lounge. The winner of the Par-
fitt Award is presented with a cash prize and a certifi-
cate of recognition, and the winner's name is also en-
graved on a plaque located in the ChEGSA lounge.
We believe that the Annual ChEGSA Symposium
is an excellent vehicle for attaining a number of objec-
tives important in the education of graduate students.
It promotes good communication skills, both spoken
and written, through the presentation of talks and the
submission of papers. It provides a means for interac-
tion between industry and academia through the par-
ticipation of company representatives. It also allows
the students to learn more about the work of their
fellow students; this is especially important when so
much research in chemical engineering is shifting
away from the traditional areas into other disciplines.
One feature that we consider to be most important
is that the symposium is a professional-quality event
run entirely by students. Although the faculty are
available for guidance and support, all the decisions
concerning the planning, organization, and execution
of the symposium are made by students. This sort of
experience will undoubtedly be useful in their future
careers and lives. We would strongly suggest that any
school planning to start a similar event should ensure
that it is run by the students.
The symposium has undergone a number of
changes, large and small, since it was first held ten
years ago. We foresee it undergoing more changes in
the future, although they will probably be minor in
nature. The objectives for which it was first con-
ceived, however, remain the same and will continue
to do so. Further information concerning the sym-
posium can be obtained by contacting the authors. O





University of Louisville
Louisville, KY 40292

S FAR BACK as 1939, a report entitled "Aims and
SScope of Engineering Education," [1] (also
known as the Wickenden Report), prepared by the
Society for the Promotion of Engineering Education,
called for fundamental changes in American engineer-
ing programs. The report called for more basic sci-
ence, more humanities, and less shop work in the cur-
riculum. These ideas were reiterated in "Report of
the Committee on Engineering Education after the
War" (1944) [2]. Most engineering educators reacted
positively to these suggestions. Since then, other pub-
lished works have suggested that engineers also
needed to be more articulate and better grounded in
humanities and social studies [3, 4, 6]. Most notable
of these was the "Grinter Report" [4] which recom-
mended that approximately 20% of the curriculum
should be devoted to the humanities. As a result,
courses in literature, composition, social studies, etc.,
have been inserted into engineering curricula. It is
interesting that one author [5] advocated removing
humanities requirements. There have also been sug-
gestions that many liberal arts curricula are not
adequately preparing their graduates for the science
and technology of today's society. Consideration of
these ideas has frequently led to the concept that
there be a certain basic level of general education re-
quired of all college graduates.


The University of Louisville recent underwent an
accreditation process by the Southern Association of
Colleges and Schools. In that process, a very strong
recommendation was made that a General Education
(Gen Ed, for short) requirement be implemented for
all students. After much discussion by the various col-

0 Copyright ChE Division ASEE 1989

... other published works have suggested that engineers
need to be more articulate and better grounded in
humanities and social studies .... As a result, courses
in literature, composition, social studies, etc., have
been inserted into engineering curricula.

Minimum Guidelines for University-Wide
General Education Requirements
University of Louisville
offered by the academic units)
(The engineering school was exempted from this hour)
AREA A: Written and Oral Communication (3+ hours)
English 101 plus three "WR" (with writing) courses at least two
of which are 300-level or above
Oral communication: Completion of a program designated by
each undergraduate college or school and approved by the
General Education Committee

AREA B: Quantitative and Logical Reasoning (6 hours)
One college-level mathematics course and either statistics or

AREA C: Natural Sciences (7+ hours)
One laboratory course (4 hours) providing a substantial
introduction to the fundamental principles of matter and
energy in physical or biological systems. One additional
science course in a second discipline..

AREA D: Humanities (9 hours)
A minimum of three hours of Arts and three hours in Humani-
ties plus a third course in either area. One course at the
300-level or above.

AREA E: Social and Cultural Studies (12 hours)
A minimum of three hours in each of the following categories
plus a fourth course in any category. Two courses at the
300-level or above (except students taking 6 hours of a
foreign language are not required to take 300-level courses
in the social cultural studies area).
Historical studies
Cross-cultural studies/Foreign language
Social and behavioral sciences
The minimum guidelines require a minimum of 31 credit hours unless a student opts
not to use double-counting and cross-counting provisions (in which case 38 hours
are required). No more than seven credits (excluding WR courses) can be fulfilled by
the double-counting and cross-counting provisions except for programs that
exceed these requirements. Only three credits from the major may be applied to any
double- or cross-counting.


leges, the University produced a Minimum Guidelines
Document for a university-wide Gen Ed Requirement.
This is presented in Table 1. The Gen Ed program
stipulates 38 hours of course-work to be taken by all
students at the University of Louisville, regardless of
their anticipated majors. If that major course of study
can fit the Gen Ed requirements into its current pro-
gram, then no additional courses need to be taken.
However, if the degree program does not meet all of
the Gen Ed requirements, some additional courses
will be needed, automatically increasing the number
of hours required to earn the degree. Alternatively,
to keep the total number of credit hours the same,
some other courses must be dropped.
As a result of the recent implementation of the
Gen Ed program at the University of Louisville, the
chemical engineering program will have to add six
extra hours. These six hours must be added to keep
from compromising the current program deemed
necessary to produce a quality engineer.
A questionnaire was generated and sent to all
chemical engineering departments in the U.S. to de-
termine Gen Ed trends nationally. If the school has
Gen Ed, was it necessary to add hours to accommo-

Walden L. S. Laukhuf is a professor
of chemical engineering at the University of
Louisville, where he had taught for fifteen
years. He received his BChE, MSChE, and
PhD from the University of Louisville. He
spent four years in the Air Force at the
Rocket Propulsion Laboratory and at the
Materials Laboratory. He is currently Asso-
ciate Chairman of the chemical engineering

C. A. Plank is a professor of chemical
engineering and Distinguished University
Teacher at the University of Louisville,
where he has taught for over thirty years.
He received his BSChE, MS, and PhD
degrees from North Carolina State. He has
also served as director of Interdisciplinary
Studies for the Engineering School and as
chairman of the chemical engineering
department. His industrial experience has
been with Olin Corp.

James C. Watters is an associate
professor of chemical engineering at the
University of Louisville. He received his BE
in chemical engineering from the National
University of Ireland, University College,
Dublin, and his MS and PhD degrees from
the University of Maryland. His research in-
terests are in novel separation processes
(particularly membrane-based), polymer
synthesis, and education techniques.

date it or did they compromise their programs to keep
from adding hours? The questionnaire is shown in
Table 2. Table 3 provides a brief summary of the re-
sponses. Most programs are on a semester system;
however, those on quarters have the quarter hours
required followed by a "Q" in Table 3. Carnegie Mellon
requires 386 units to graduate; thus there is a "386 U"
in their degree hours column. In like manner, "QU"
at Northwestern refers to quarter units and "CC" at
Tufts means course credits required for graduation.
Because of these examples, a common basis of semes-
ter hours was not chosen. The total hours set by Gen
Ed, at those schools which sent their Gen Ed require-
ments, are listed in the last column of Table 4.

General Education Requirements Questionnaire

Please take a few minutes from your busy schedule and fill this in. Return
to Dr. W. L. S. Laukhuf, Chemical Engineering Department, University of
Louisville, Louisville, KY 40292, no later than 1 November 1987. Please
include a copy of your requirements if they are written down.

1. Does your University/Engineering School have a General
Education requirement of all students other than those
required by ABET?
YES_ NO_ (IfNO, go to #6 below)

2. If the answer to question 1 was YES, then what body has
specified the requirements? In what year were they

3. Did your "ideal" program as structured prior to Gen Ed
contain more hours than required by ABET?
YES NO If YES, how many more?

4. With the addition of Gen Ed, how many extra semester
hours were added?

5. In the Gen Ed implementation process, were any hours of
your 'ideal" program lost to keep from adding extra hours to
the total hours for graduation?
YES NO_ If YES, how many were removed?_

6. How many semester credit hours are required to receive a
chemical engineering degree from your school and what is
the name ofthe degree?
HOURS DegreeName

7. If you do not presently have Gen Ed, is there any movement
in that direction at your university?

8. Name of responding school

9. Name of person responding



One hundred and fifty-five questionnaires were
sent to chemical engineering departments in the
United States. Eighty-nine replies were received.

This high response (almost 60%) is, by itself, very
encouraging. Four of the responses are from unac-
credited programs. Of the 89 schools, 59 (or 66.3%)
are operating under some form of Gen Ed require-
ments. Fourteen of the remaining schools are consid-

Questionnaire Results


Brigham Young

Carnegie Mellon
Christian Brothers

Cleveland State

Colorado State
Fla A&M/Fla State

Fla Inst of Tech
Georgia Tech
Howard Univ

Johns Hopkins
Lafayette College
Louisiana State

Louisiana Tech

McNeese State
Michigan State
Michigan Tech

Montana State
New Jer. Inst. Tech
New Mexico

New Mexico State
N Carolina A&T St
North Dakota
Notre Dame

When Think Total GenEd
Have Who Set Started About GenEd Deg %of
ABMEGenE r 9enM 9oE1 d GenErd urs HIr WHrs

yes yes Univ 1965 n/a
yes yes Univ
yes yes Univ 1987 n/a
yes no o
yes yes Univ n/a

yes o -
yes no -yes
yes yes Univ 1984 n/a
yes yes Univ 1985 n/a
yes yes Univ ? n/a

yes no yes
yes yes Univ 1980 n/a
yes yes Univ 1984 n/a
yes yes Univ 1964
yes no yes

yes yes Univ F 1986 n/a
yes yes Univ 1988-89 n/a
yes o -
yes no -
no yes State n/a

yes yes Univ 1979-80 n/a
yes yes Univ-St Long ago
no yes Univ Pre-Eng n/a
yes no -
yes yes Univ 1983 n/a

yes ro yes
yes no no
yes yes Univ 1966 n/a
yes yes
yes yes Univ F 1987 n/a

yes yes State 1987 n/a
yes yes Univ 1988-89 n/a
yes yes Univ. F 1983 n/a
yes yes Univ 1980 n/a
yes yes Univ n/a

no yes State F 1987 n/a
yes o o
yes yes Univ long ago n/a
yes yes Univ n/a
yes yes Univ pre-1967 yes

yes yes EngSch 1986 n/a
yes yes Univ 1986 n/a
yes yes Univ F 1987 n/a
yes yes
yes o yes

yes o yes
ro yes Univ ? n/a
yes yes Univ 1982 n/a
yes maybe Univ yes
yes yes

28 136
50 138
12 137

18 1930
108 386 U

201 Q
39 120

37 128

19 138



45 138
38 128
36 138
39 130
39 130

43 137

48 132
S 133

38 137
48 QU


Ohio State
Ohio University
Oregon State

When Think Total GenEd
Have Who Set Started About GenEd Deg %of
ABET Gen hGenmEd Gen. Genl~E Hours Hrs fDeHrs

yes yes Univ yes
yes yes Univ 1980 n/a
yes o yes
yes yes Univ yes
yes o n/a

Polytechnic (Brooklyn) yes no -
Princeton yes yes Univ ? n/a
Purdue yes o n/a
Rhode Island yes yes Univ pre-1970 n/a
Rice yes yes Univ 1970 n/a

South Carolina
South Florida
Southern California

Southwest Louisiana
Stevens Institute
Tennessee Tech

Texas A&l
Texas A&M
Texas Tech


Washington Univ
Wayne State
West Vir. Inst. Tech.

Worcester Poly

yes yes Univ-Eng pre-1957 n/a
yes yes Univ pre-1967 n/a
yes no yes
yes yes Univ 1980+ yes
yes o yes

yes yes State 1987 n/a
yes yes Faculty 1987 n/a
yes yes Univ 1982 n/a
yes yes Univ 1988 n/a
yes ro m

yes yes Univ n/a
yes yes Univ 1982 n/a
yes yes Un,StEng 1988 n/a
yes o yes
yes yes EngSch 1986 n/a

yes yes Univ 1984 n/a
yes o yes
yes yes Fac 1950 n/a
yes o -
yes no yes

yes yes Univ 1985 n/a
yes yes Un,Dept 1986 n/a
yes o n/a
yes yes Univ F 1987 n/a
yes yes Univ 1966 yes

yes yes Univ pre-1981 n/a
yes o -
yes o -
yes o -

204 Q

36 131
36 137

S 132

47 141
29 138
56 2030
- 2000

46 138
51 138
38 CC

48 132
32 124

40 140


Table Nomenclature:
School Name of school responding.
ABET Is the ChE program accredited?
Have Gen Ed Does the school operate under Gen Ed?
Who Set Gen Ed What body required Gen Ed implementation?
When Started Gen Ed When was Gen Edirrplemented
Thirk About Gen Ed Is a school considering Gen Ed?
Total Gen Ed Hours The hours specified by Gen Ed.
Deg Hrs Total hours required for the ChE degree.
Gen Ed % of Deg Hrs Gen Ed hours as a percent of total degree hours.


ering Gen Ed. This means that 82% of the schools
replying either have Gen Ed requirements or are con-
sidering implementing such a program.
Even though the Gen Ed concept is very new to
the University of Louisville, such is not the case at
several other schools. Of those schools which replied
to the question on date of implementation, 14 had Gen
Ed before 1980, 15 began the program between 1980
and 1985, while 17 have initiated the process since
then. Of the 14 before 1980, some had Gen Ed as early
as 1957. Gen Ed was a way of life at some universities
before engineering was started at those schools. In
these cases, the engineering program was built with
Gen Ed in place. At other schools, Gen Ed was started
before any of the current faculty were employed, so
that an implementation date was not specified.
Who imposed Gen Ed requirements at the particu-
lar university was one of the questions asked. Fifty of
the 59 with Gen Ed (84.7%) stated that the university

administration had imposed Gen Ed. It is assumed
that the Gen Ed requirements for these 50 schools are
then similar to the situation at the University of
Louisville: that is, a university-wide requirement.
Seven schools stated that the engineering school had
imposed Gen Ed. It is quite possible that these 7 may
in fact be acting under university-wide requirements.
If that is the case, then 96.6% of those schools replying
as having Gen Ed had these requirements imposed at
the university level. In correlating the replies, it also
seems that the states of Texas, Florida, Louisiana,
and Georgia have imposed some Gen Ed requirements
on their various schools. It cannot be determined from
the questionnaires whether the schools in those states
have additional requirements beyond those specified
by the state or if the state requirements are more
stringent than might have been prescribed by the
The number of hours specified by the several

General Education Requirements








1 11
(6) 6 6
9 9
3 -




S 108
6 39



2 courses

2 courses -


8 6 yes


(3) 18
S 24
(9) 12

193 Q
386 U






203 Q

24 4 32 124
2 6 18 40 140

SCI Credit Hours for Science Courses
MATH Credit Hours for Math Courses
LABS Laboratory Course Requirements
COMP Computer Literacy Requirements

PE Physical Education Requirements HUM/SS Humanities andor Social Science Requirements
FOR LAN Foreign Language Requirements OTHER Other Course Requirements
COM Communications Course Requirements GEN ED TOTAL Gen Ed Total Credit Hours Required
WR COUR With Writing Emphasized Course Requirements DEG HRS Credit Hours Required for the Degree


schools to meet their Gen Ed requirements varies
widely. Of the 27 schools which sent copies of their
Gen Ed documents, 2 specify 20 or less hours, two list
between 20 and 30 hours, 13 from 30 to 40 hours, 7
between 40 and 50 hours, and 3 require more than 50
hours of Gen Ed courses. The average number of Gen
Ed credit hours is 39. The last column in Table 3 rep-
resents the percentage of the total degree hours which
are associated with Gen Ed requirements. These per-
centages range from a low of 8.8% (Arizona) to a high
of 37% (Texas A&M) of the total degree hours; the
majority of those schools that provided the required
data have more than 25% of the entire program as-
sociated with Gen Ed. Even though the number of
hours associated with Gen Ed is rather large, and the
resulting percentages of the total degree require-
ments is also large, only 23 schools added hours to
their existing program when implementing Gen Ed.
Only 4 of the 23 added more than 9 credit hours. Most
added 3 to 6 hours to the existing program. The
number of hours required for Gen Ed varies widely
from school to school because the definition of what is
required in Gen Ed also varies widely from school to
The manner in which the hours for Gen Ed are
broken up by the various schools is also interesting.
Table 4 presents how the various schools, which sub-
mitted their Gen Ed plan, specify the makeup of the
hours, as best as can be determined. The major re-
quirements appear to be (and are reflected in the col-
umn headings in Table 4) science, math, laboratory,
computer literacy, physical education, foreign lan-
guage, communications, writing courses, and human-
ities and social sciences.
All but three of the schools require Gen Ed courses
in science. Many of the schools require that at least
one course be in the physical sciences while a second
must be in the life sciences. In addition, at least 10 of
these schools require some laboratory experience in
the science area. For the 24 schools requiring sci-
ences, the average number of credit hours required is
7. This would typically indicate 2 courses, one of which
had a 1 hour lab component.
Twenty-two schools require math courses. The av-
erage number of hours required is 5.6. In some cases,
Gen Ed required combined hours of math and science
with no split indicated between the 2 areas. In these
cases, the hours were split evenly between the two in
Table 4.
Eight of the schools require computer literacy to
be determined by a test or by taking required courses.

The University of Alabama requires either 6 hours in
computer programming or 6 hours in a foreign lan-
guage. Therefore, in Table 4, 6 hours were placed in
the foreign language column and a (6) inside of
parentheses was entered in the computer column to
keep from double-counting the credit hours. Any time
a number of hours appears in the table in parentheses,
those hours are also shown somewhere else in Table
4 for that school.
Ten of the schools require physical education
courses. All but 5 require some combination of oral
and written communications courses, the average
number of hours being 6.4. Many of the schools permit
a student to test out of these hours by making a par-
ticular score on a placement test. In addition, at least
11 schools formally require "with writing (WR)"
courses. Often, these are in addition to the hours in
communication courses already mentioned.
All of the schools sending their Gen Ed plan re-
quire humanities and social science courses. The aver-
age number of hours is 19.3, which is greater than the
one-half year (16 hours) required for ABET accredita-
tion. Based on 3 credit hour courses, 18 hours are
required to get the 16 hours for ABET. However, 12
schools require more than 18 hours. These humanities/
social science hours are specified in various ways at
different schools. All schools require some courses in
each area. Most schools also require some depth in the
selection process. They either specify two-course se-
quences or require courses which are normally beyond
the introductory level.
Nine of the schools require courses which were
placed in an "other" category. These include manage-
ment, technology and society, and engineering
courses, among others. These courses fulfill one aim
of Gen Ed-that of exposing non-technical students to
the other side of the fence.

1. Hammond, H. P., "Aims and Scope of Engineering
Curricula," J. ofEng. Ed., 30, 555-556 (1939-40)
2. Report of Committee on Engineering Education After
the War, J. ofEng. Ed., 44, 589-614 (1943-44)
3. Burdell, E. S., "General Education in Engineering," J.
ofEng. Ed., 46, 619 (1956)
4. Grinter, L. E., Chairman, "Report of the Committee on
Evaluation of Engineering Education," The American
Society for Engineering Education, June 15, 1956
5. Wing, R. H., "Are Engineers Selling Their Birthright
for a Place in the Ivory Tower?" Chem. Eng. Ed., 2, 41
6. Sleicher, C. A., "Humanities and Social Science in En-
gineering Curricula," Chem. Eng. Ed., 2, 66 (1968) 0


Use CEE's reasonable Rates to advertise.
Minimum rate, 1/8 page $80;
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The Chemical Engineering Department at Virginia
Tech is seeking applicants and nominations for the
Alexander F. Giacco Presidential Professor in Chemical
Engineering. Applicants for this endowed professorship
should have a national/international reputation in an
area of chemical engineering research. Duties include
teaching at the undergraduate and graduate levels,
conducting funded research, and departmental and
university service. This appointment is at the Full
Professor level at a salary commensurate with the
endowed nature of the professorship and the applicant's
qualifications. Virginia Tech has approximately 18,500
undergraduates (5,000 in the College of Engineering,
including 150 in Chemical Engineering) and 4,180
graduate students (1,200 in the College of Engineering,
including 50 in Chemical Engineering). Send
nominations or applications to Chairman, Giacco
Professorship Search Committee, Chemical Engineering
Department, Virginia Polytechnic Institute & State Uni-
versity, 133 Randolph Hall, Blacksburg, VA 24061.
Deadline for applications is May 31, 1989. Virginia Tech
hires only U.S. citizens and lawfully authorized alien
workers. Virginia Tech is an Affirmative Action/Equal
Opportunity Employer.

Applications are invited for appointment to a tenure
track position in the Department of Chemical
Engineering at Michigan State University. This position
is jointly supported by the Composite Materials and
Structures Center (CMSC) and provides an excellent
opportunity for an individual with research and teaching
interests in polymeric material science and engineering,
polymer processing and/or composite processing.
Candidates should have a doctorate in Chemical En-
gineering or Polymer Science/Engineering. The desired
qualifications include an established record of research
in an academic or industrial environment, and a vigorous
interest in undergraduate and graduate education.
Michigan State has recently made a strong commitment
to composite materials with the establishment of the
CMSC in the College of Engineering. This provides
faculty with the opportunity to conduct individual and
joint research programs and to teach in an academically
rich and well-supported environment containing state-
of-the-art research equipment and facilities. In addition,

Michigan State is located in close proximity to a large
number of polymeric and composite materials industrial
concerns providing many consulting and collaborative
research opportunities. Applications will be accepted
until April 1, 1989 or until the position is filled. Interested
individuals should apply to Dr. L. T. Drzal, Chairperson,
Search and Selection Committee, Department of
Chemical Engineering, Michigan State University, East
Lansing, MI 48824-1226. Appointments may be made at
any level. Salary and Rank are commensurate with
experience and accomplishments. Michigan State
University is an Affirmative Action-Equal Opportunity
Employer and welcomes applications from women and
members of minority groups.

Tenure system faculty position. Doctorate in
Chemical Engineering or closely related field. A strong
commitment to teaching and the ability to develop a
quality research program is expected. The area of
research interest is open. The department will provide
start-up funds and offers opportunities for collaboration
with other faculty in a variety of areas. Teaching and/or
industrial experience desirable but not essential.
Michigan State University is an affirmative action/equal
opportunity employer and welcomes applications from
women and minority groups. Applications will be ac-
cepted until April 1, 1989 or until the position is filled. To
apply send curriculum vitae, a statement of research
interests, and names of at least three references to
Chairperson, Search Committee, Department of
Chemical Engineering, Michigan State University, East
Lansing, MI 48824-1226.

Wayne State University

Anticipated Position, Assistant or Associate
Professor with research interest in hazardous waste
management engineering preferred. Salary competitive.
Start January, 1990. Send resume to: Dr. Ralph H.
Kummler, Chairman, Department of Chemical and
Metallurgical Engineering, Wayne State University,
Detroit, MI 48202. WSU is an equal
opportunity/affirmative action employer


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class and home problems

The object of this column is to enhance our readers' collection 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, which elucidate difficult concepts. Please submit them to Professor H. Scott
Fogler, ChE Department, University of Michigan, Ann Arbor, MI 48109.


An Optimization Problem

Universidade Catolica Portuguesa
Escola Superior de Biotecnologia
4200 Porto, Portugal

ENZYMES ARE THE functional units of cell metabo-
lism. They are specialized globular proteins with
an extraordinary catalytic power and with orders of
magnitude greater than most of the synthetic
catalysts [1]. Enzymes are remarkable catalysts due
not only to their powerful activity, but also to their
high specificity and versatility. These characteristics
have emphasized their industrial application for the
catalysis of a great number of reactions within the
food, medical, and cleaning fields [2].
Many enzymes are oligomers composed of distinct
subunits or monomers. If the sites are identical and
completely independent of each other, then a classical
Michaelis-Menten kinetic equation results [3]. If the
presence of substrate on one site influences the bind-
ing of the substrate to vacant sites, or the rate of
product formation at other occupied sites, then a situ-
ation arises where the substrate itself acts as a mod-
ifier or effector yielding substrate activation or sub-
strate inhibition [4]. Such enzymes are called allosteric
enzymes, and their catalytic activity can be substan-
tially increased or decreased in response to such sub-
strate molecules acting as control signals. The be-
havior of these regulatory enzymes can be modeled by
assuming a concerted transition of protein subunits:
the first substrate molecule bound to the enzyme al-
ters the enzyme's structure so that the remaining sites
have a stronger, or weaker, affinity for the substrate
This paper concerns a particular interest in posi-
tive cooperativity for the homotropic enzyme [1]. This
phenomenon leads to a sigmoidal relationship between
0 Copyright ChE Division ASEE 1989

F. Xavier Malcata is currently a PhD
student at the University of Wisconsin,
Madison. He earned a BSc in chemical en-
gineering from the Portuguese State Uni-
versity (Oporto) in 1986. He is a member of
the teaching staff of the College of
Biotechnology of the Portuguese Catholic
University. His research interests are mainly
focused on the application of the principles
of chemical engineering to the solution of
problems in the food technology field.

the kinetic rate and the substrate concentration [6].
The simple sequential interaction model [7, 8] has
been throughly reported in literature as yielding good
fits to experimental data. This model introduces a
number of interaction parameters, or factors by which
the intrinsic binding constants are increased as the
substrate molecules bind to the active sites. Assume
that the enzyme contains n equivalent binding sites,
and that the cooperativity in substrate binding is very
marked; in this situation the concentrations of all en-
zyme-substrate complexes containing less than n
molecules of substrate are negligible at any appreci-
able substrate concentration compared to the intrinsic
dissociation constant for the substrate/enzyme com-
plex. The kinetic equation then reduces to the Hill
equation [9]
The Hill kinetic equation can be used even if the
cooperativity of the binding is not very high; however
in this case parameter n loses its physical meaning
and is commonly referred to as the apparent number
of substrate binding sites [4]. Such adjustable
parameters can be easily obtained from a graphical
logarithmic construction based on Eq.(l), known as
the Hill plot [4].
v Cn
v = (1)
K' +Cn





For homogeneous enzymatic catalysis taking place
in an aqueous solution of substrate, the continuous
stirred tank reactor (CSTR) possesses a number of
relevant features for industrial operation. Besides the
lower construction costs when compared to classical
tubular reactors, the efficient stirring of the reactor
ensures uniform temperature (thus avoiding hot
spots), coupled with ease of access to the interior sur-
face for manutention and appreciable residence times
[10]. Extensive literature is available on the optimiza-
tion procedures leading to a minimum in the overall
reactor volume of a series of CSTR's performing a
chemical reaction described by a given kinetic equa-
tion [11-15]. The main goal of this paper is to apply
the classical approach for optimization of reactor de-
sign to a slightly involved home problem in the
biochemical field. Although the general solution can
be graphically obtained, a number of analytical asymp-
totic solutions are developed. These solutions enable
one to obtain a quick estimate of the size profile of the
series of CSTR's.


Consider a system of CSTR's in series which is
currently being designed to perform a homogeneous,
enzyme-catalyzed reaction in the liquid phase de-
scribed by the Hill equation. Isothermal and steady
state conditions of operation are assumed. The charac-
teristic time scale associated with the enzyme deacti-
vation is very large when compared to the time scale
associated with the enzyme-catalyzed reaction.
1. Show that the minimum overall reactor volume
is obtained when the following condition applies

8Dai 3Dai+1
-- + -- =0 (2)
ac acI

2. Prove that the foregoing condition leads to

c* r c* 1
i-l,pt iop (3)
C* C
i,opt i ,opt

for the case where Eq. (1) is used as the kinetic equa-
tion describing the behavior of the reactive system.
3. Show that Eq. (3) leads to
C* = C* (4)
i,opt N
when n equals unity.
4. Show that the optimization condition for large
N and C*N, and small n is met when the concentration

of substrate at any intermediate stream is equal to
the arithmetic mean of the upstream and downstream
consecutive concentrations.
5. Derive the following equation

n i1 n-ll]n
1opt W] N

from Eq. (1), on the assumption that N and C*N are
small, and n is large.
6. Consider the conversion of fructose-1,6-diphos-
phate to fructose-6-phosphate catalyzed by the en-
zyme phosphofructokinase. Assume that the reaction
is carried out under such conditions that it can be con-
sidered approximately irreversible. Compute the vol-
ume of each reactor in a series of CSTR's leading to
a minimal overall volume where the foregoing reaction
will take place. The following data are available:

N= 3, n = 2, C,= 2.6x 10-2mol m-3,
C = 5.5 x 10-3mol m-, vm x = 1.3 x 10-4 mol m- 3s-1,

K'=4.6x 10-5mol2 m-6, Q=3.6x10-3m3 .s-1

1. A mass balance to the substrate for each CSTR
takes the form

c* C' K*,+ C')
Dai = -1 (6)

The minimum volume for the whole reactor system is
obtained when the following condition applies
S Da. =0 (7)
act i=l

Since C*i appears only in the ith and (i + 1)th terms of
the foregoing summation, one finally obtains Eq. (2)
from Eqs. (6) and (7).
2. Using Eq. (6) in Eq. (2), one obtains

K*(n 1) C*

2n K*C Cn-1
i,opt nK*-l,pt i,opt
C* 2n
i, pt
C n
K.+ C*+
+K + Ci+1,cpt
+ 0
C* n


Some algebraic manipulation can now be performed
on Eq. (9), yielding Eq. (3) as the resulting equation.
Eq. (3) is graphically plotted in Figure 1 for a number
of values for parameter n.
3. Eq. (3) can be easily transformed to



when n= 1. Applying the foregoing recursive relation
from i= 1 up to a generic i, one gets

0* =c

In particular, Eq. (11) gives the following result


0.2 04 06
C* /C*
i.opt i- lopt

for the case where i = N. Combination of Eqs. (11) and
(12) finally enables one to obtain Eq. (4).
4. Eq. (3) can be written in a slightly different
form, namely

"* f c* '
i-l,opt i,opt
n --- = n 1+ ex n In
icpt i+l,opt

Taking advantage from the fact that the fractional
change in concentration between consecutive stages
is small due to the large N and C*N, one can expand
the exponential term in Eq. (13) as a MacLaurin series
[16] and truncate it after the linear term in order to

C* r *
i-1,opt = 1+ In (14)

i,pt i+1,pt

Rearranging Eq. (14), one obtains

c* =0C* exl c 1 (15)
c+l,opt = Cpt C

The exponential term in Eq. (15) can be similarly ex-
panded as discussed previously in order to give

C* + C*
. i-1,,ti i+1,cpt
i,apt 2 q.e.d.

5. If n-1 is small compared to (C*i,opt/C*i+,opt)n,

FIGURE 1. Relation between Ci+ 1,,o/C*ip, and C, op/
C*i,,pt yielding the minimum overall reactor volume,
for a number of values for parameter n.

then Eq. (3) reduces to

C* = c* ipt (17)
i+l,opt it nC

Applying the foregoing recursive relation from i= 1
up to the current i, one obtains
i-i r 1 i-1
S(ci-J)[ ] i [ ]

c* =-N 1 (18)
i,opt ,
The first exponential summation in Eq. (18) can be
rearranged as follows
i-1 i-1 -1
0(i-j) = W1 Y[ j] (19)
j=1 j=l m=O

Eq. (19) can be transformed into

/1 1 (20)
(i LJ n=Ln
j=1 j=1 1-

with the aid of the summation property of the geomet-
ric series [17]. Eq. (20) can be again rearranged to


C 2
C' iop
i+l,opt C"

I I I nI /
n 2

--- n=6


i //
I I ,

C* = C*
N 1

0.8 10


i-1 3 i-1 -
C (i-jj)[] =r (21)
j=1 j=

which is equivalent to

S(i j) n -1- (22)
j=1 (n 2)

The second exponential summation in Eq. (18) can be
written as

[ -i- [1 [- (23)r
j n-I n

where a similar reasoning was followed. The combina-
tion of Eqs. (22) and (23) with Eq. (18), coupled to the
condition i= N leads, after some manipulation, to Eq.
6. Using the definition of normalized variables and
dimensionless parameters as given in the nomencla-
ture, one gets C*N = 0.212 and K* = 0.0680. Use of Eq.
(3) for i= 1 and i= 2 gives

C*, = 0.50000 C* + 11.130 C(24)
l 1pt 2, opt 2,opt

1376.9 C*

+ 185.65 C* + 19.473 C
2,opt 2, pt

+ 0.62500 C* 2.0000 = 0 (25)

A trial-and-error method applied to Eq. (25) gives
C*2,opt=0.3224 as the only solution with physical
meaning. Application of this result in Eq. (24) yields
C*1,opt=0.5342. Eq. (6) can now be used with the
foregoing results in order to obtain Da1,in,=0.5768
and Da2,mmi=0.3504. These values correspond to the
volumes of VI,, n= 0.4150 m3 and V2,zn= 0.2521 m3,

The optimal intermediate concentrations can in
general be obtained from a numerical trial-and-error
solving procedure based on Eq. (3), as outlined previ-
ously. The total number of solutions of the correspond-
ing polynomial in C*N-l,opt is, nevertheless, a strong
increasing function of N. This fact may lead to numer-
ical instability, coupled to extra numerical work when

the iterative procedure converges to roots with no
physical meaning. Therefore, a graphical iterative
construction on Figure 1 similar to the stagewise cal-
culation known as McCabe-Thiele method for binary
systems undergoing distillation [18] proves safer and
faster. The major steps of such graphical procedure
are as follows: (i) arbitrate C*,,opt; (ii) draw a horizon-
tal line from the point of coordinates (C*1,opt,C*2,opt/
C*i,opt) until intersection with the main diagonal; (iii)
draw a vertical line from the foregoing point until in-
tersection with the line corresponding to the assumed
n; (iv) iterate steps (ii) and (iii) until C*N,opt is ob-
tained; (v) if C*N,opt is larger than expected, arbitrate
a smaller C*1,opt; if C*N,opt* is smaller than expected,
arbitrate a larger C*,,opt; in both cases, repeat from
step (ii) until convergence is achieved according to a
user-defined criterion.
The result denoted as Eq. (10) was initially re-
ported by Luyben and Tramper [14] for the case of
single-sited enzymes following simple Michaelis-Men-
ten kinetics. It is interesting to note that the optimal
intermediate concentrations of substrate as given by
Eq. (3) do not depend on the kinetic constant K*.
Therefore, for any two consecutive CSTR's with
known inlet concentration to the first reactor and out-
let concentration from the second one, the inter-
mediate concentration leading to a minimal overall
reactor volume is uniquely defined.
The minimization of the objective function chosen
corresponds to the minimization of the total capital
investment if a scale-up factor of unity is assumed for
the equipment cost. Currently, however, such expo-
nent factor tends to be lower, as in the general-pur-
pose six-tenths-factor rule for geometrically and
mechanically similar reactors [19]. Moreover, the total
number of reactors remains arbitrary after the optimi-
zation procedure on the concentrations has been per-
formed. As suggested elsewhere by Malcata [15] for a
similar system, the best compromise is found when
two objective functions are combined, a hierarchical
order being defined on the basis of intrinsic costs. The
minimization of the total holding time ensures that
the thermal degradation of substrate is kept at a
minimum for any given overall conversion (first prior-
ity, or higher intrinsic cost); the actual number of
reactors required is then found by applying a suitable
fractional-exponent law for equipment scale-up (sec-
ond priority, or lower intrinsic cost).
The asymptotic expressions developed for the opti-
mal intermediate concentrations, Eqs. (16) and (18),
are useful for a direct calculation whenever the as-
sociated limiting conditions are satisfied. In practice,
Continued on page 128.




University of Louisville
Louisville, KY 40292

H ETEROGENOUS catalysis is a key technology in
the chemical industry, and it has produced
dramatic developments, but these developments have
often gone unnoticed or are little understood by the
public, including people who are technically educated.
For example, few university graduates know what a
zeolite is, and even fewer perceive the relationship
between healthy air, unleaded gasoline, and catalysts.
In contrast, the public is well aware of sophisticated
materials, such as superconductors, and relationships
such as communications and optical fibers.
In response to employment opportunities, and
closely following popular perception, the glamour of
catalysis among chemistry-oriented engineering stu-
dents has declined in favor of more exciting and more
visible technologies. Our once-popular yearly catalysis
course is now a bi-yearly course attended by about
ten graduate students from engineering and chemis-
try. This drop in attendance prompted us to change
the perspectives of the course to make it more palat-
able to the incoming graduate student. The new
catalysis course has elements of materials processing
embedded in the classical format of catalytic
mechanisms and surface chemistry. This approach
opens up avenues for those beginning graduate stu-
dents who are interested in a general understanding
of surface technology, while still preparing those stu-
dents whose main research objectives are in catalysis.
This approach is necessary at this university, where

Raul Miranda, assistant professor of
chemical engineering at the University of
Louisville, received his engineering degree
from the Universidad de Cuyo (Argentina)
and his MS and PhD degrees from the Uni-
versity of Connecticut. His current interests
include heterogeneous catalysis and solid-
state technology.

In response to employment opportunities, and
closely following popular perception, the glamour of
catalysis among chemistry-oriented engineering
students has declined in favor of more exciting
and more visible technologies.

it is the only course that exposes students to surface
The course outline shown in Table 1 clearly re-
sponds to the multidisciplinary character and breadth
of catalysis. The instructors must attain the proper
depth into each topic, realizing that it is not trivial to
find in a one-semester course the synergic combina-
tion of solid state, surface science, organic chemistry,
and catalysis practice needed to initiate the student of
catalysis. The students interested solely in catalysis
may have ambivalent feelings about this outline since
the time dedicated to topics of catalysis is reduced to
allow for general topics of materials science. On the
other hand, however, the broader knowledge acquired
about the solid state may actually benefit their re-
search careers.
The first seven topics contain traditional material
of catalysis, and the last four topics contain elements
of solid state and surface chemistry, and of materials
processing such as dopant diffusion, CVD, and sol-gel
technology. In practice the topics are never covered
sequentially. Our practice has been to dedicate two
days every week to topics one through seven, and one
day every week to topics eight through eleven. Each
of the topics is covered in two to five class periods.
The fifteen-week three-credit course is based on
current textbooks and journal publications, as listed
in the references. The graduation requirements in-
clude two literature review papers, a midterm, and a
final exam. The literature review papers are of semi-
nal importance to the preparation of the students, who
grade this activity as the most valuable of the course.
It lets them acquire depth in at least two topics, and
it also gives them the chance to improve their writing
ability. The first paper allows them to polish both
their writing and their literature searching skills. Two
separate drafts are read by the instructor before the

Copyright ChE Division ASEE 1989


final version is graded, giving the student a chance to
focus the emphasis in response to the instructor's
reactions. The second paper must be on a different
topic, to avoid specialization in a narrow subject area
and to force the student into a new literature search.
The degree of quality improvement from the first to
the second paper is generally large, justifying the dou-
ble paper requirement. Several students have later
stated that they used the second paper, without
changes, as a chapter in their theses. Some even claim
to have attached the papers to their resumes to show
their communication skills!
Examples of recent topics in catalysis chosen by
students are listed in Table 2, which may serve as a
guide to new instructors who are implementing this

course. Balance between detail and generality must
be provided by the instructor, especially for the first
paper, which tends to be either a collected summary
of a large number of publications or an organic chemis-
try approach to catalysis with little insight into the
catalyst itself. In this course, much of the emphasis is
placed on the description of structural, surface, and
electronic transformations undergone by the solid
catalyst and the adsorbed reactants, to the extent of
current knowledge. Papers on an instrumental
technique and interpretation of data from case studies
using such techniques are also accepted. Peer student
evaluation of the papers is required according to the
form shown in Table 3 and is enforced by including in
the final exam some conceptual questions related to

Course Outline

Prereuisites: Elementary steps, rate determining step,
Langmuir adsorption, heterogeneous reaction kinetics, mass
and heat transport in porous catalysts, physical characteriza-
tion techniques: BET surface area, mercury porosimetry and
densitometry, experimental techniques and reactors. (These
are part of the contents of the required graduate reaction en-
gineering course and are not duplicated in the catalysis

1.Introduction. Heterogeneous catalysis in industry. Eco-
nomic importance. Definition of catalysis. Activity,
selectivity and life. Classification of catalysts. Materials
science aspects of catalysis. Overview of other materials sci-
ences and their degree of development relative to catalysis.
Role of surface science in catalysis. (Refs. 1-5; 6, Ch. 1; 7,
Ch.1; 8, Ch. 1; 9-11)

2. Adsorption of Gases on Solids. Ideal (Languir) and non-
ideal adsorption on solids. Chemisorption. Application of
statistical and quantum mechanics to adsorption and desorp-
tion. General results on metals and non-metals. Agreement
with theory. (Refs. 6, Ch. 2; 7, Ch. 2; 12-18)

3. Selected InstrumentalAnalysisTechniques. Bulk analy-
sis: x-ray diffraction, infrared spectroscopy, electron spin
resonance. Surface analysis: x-ray photoelectron, auger,
secondary ion mass spectrometry. Electron microscopy.
Selective chemisorption. (Refs. 6, Ch. 5; 19-28; 29, Ch. 2; 30)

4. Kinetics. Collision theory, transition state theory, and
steady state approximation, applied to catalytic kinetics.
Temkin's formalism for uniform and nonuniform surfaces.
Examples: Ammonia synthesis kinetics. Chemical vapor
deposition of SiO2. (Refs. 7, Ch. 3 and 4; 31, Ch. 4 and 7; 32,
Ch. 8)

5. Major Chemical Processes. Their chemistry and cata-
lysts. Catalytic cracking, Reforming. Partial oxidation of
hydrocarbons, Hydrotreatment and demetalation. Steam re-

forming. Hydrocarbon synthesis. Catalytic conversion of
auto exhaust gases. (Refs. 33, Ch. 1 and 3-5; 6, Ch. 10; 34; 35)

6. Early Generalizations in Catalysis. Polanyi and Bronsted
relations. Compensation effect. Sabatier's principle in met-
als and nonmetals. Geometric factor. Balandin's multiplets,
Kobosev's ensembles. Electronic factor. Band theory. Va-
lence bond theory. (Refs. 7; 12; 33, Ch. 3; 36; 37; 50; 51)

7. Modern Generalizations in Catalysis. Surface acidity.
Surface compounds. The surface states. Quantum mechani-
cal approximation methods. Metal alloying. Mono and
bimetallic clusters. Structure sensitivity. Metal and non-
metal support interactions. Practical examples. (Refs. 7; 12;
33; 38-41; 43; 50)

8. Solid State Chemistry. Metals. Interstitial, ionic, layer
compounds. Alloys. Oxides, single and mixed. Sulfides.
Semi and Superconductors. Structures, some electronic fea-
tures, general crystallization techniques, and phase dia-
grams. Amorphous solids. (Refs. 42; 37; 44-45)
9. Sol-Gel Chemisr. General principles. Detailed applica-
tion to synthesis and modification of silica, alumina, silica-
alumina. Catalyst supports. High-purity fused silica materi-
als. Applications to optical materials. Hydrothermal synthe-
sis. Zeolites. Catalyst synthesis by impregnation or precipi-
tation. (Refs. 46; 47)

10.DefectStructure. Reversible and irreversible defects. De-
fect clusters. Shear structures. Diffusion and conduction in
the solid state. Coordinatively unsaturated sites. (Ref. 48)

11. Surface Structures. Relaxation and reconstruction. Ad-
sorbate-induced reconstructions. Modification of surface
electronic properties by adsorption. Catalytic promoters. De-
activation and regeneration of catalytic sites. Doping and
carrier density. Dopant-induced reconstruction. Thin-film
generation. CVD, vapor-phase epitaxy, molecular and ion
beam epitaxy. (Refs. 29; 32; 49)


Examples of Recent Review Papers

Catalytically Promising Structures of Ternary and
Quaternary Compounds
Scheelite-Structured Catalysts
SProperties of Small Metal Clusters
Thin Film Model Catalysts
Immobilization of Transition-Metal Complexes
Asymmetric Syntheses on Heterogeneous Catalysts
SShape-Selective Catalysis
SXRD of Zeolite Materials
SPreparation of Metal Clusters in Zeolites
SSynthesis of Gasoline-Range Hydrocarbons over Zeolites
Designing Hydrodesulfurization Catalysts
SHydrodenitrogenation Catalysis
SCatalysis by Single Crystals of Mo Chalcogenides
The Active Phase in Hydrodesulfurization Catalysts
Sinteringof Supported Metal Catalysts
SCatalyst Poisoning by S Compounds
SCoking of Zeolites
SOxidative Decarboxylation Catalysts
Nitrobenzene Hydrogenation
SMethanation Catalysis
Benzaldehyde Hydrogenation
Catalysts of Coal-Char Gasification
Methanol Synthesis
SPromotion by Potassium
STemperature-Programmed Desorption and Reaction
Photocatalytic Solids
Auger Electron Spectroscopy
Low Energy Electron Diffraction
SInfrared Spectroscopy ofAdsorbates
X-Ray Photoelectron Spectroscopy

the papers written by the class. Students become im-
placable judges of a classmate's writing when they
must answer questions on it in a final exam.


1. Nelson, W. L., Petroleum Refinery Engineering, Ch. 2,
"Composition of Petroleum," McGraw-Hill (1958)
2. Farah, O. G., et al., Ethylene, Ch. 1, "Ethylene Industry
and Sources of Supply," Ann Arbor Science (1980)
3. Witcoff, H., "How is it Really Done," CHEMTECH, 12,
753 (1977); 4,229 (1978)
4. Chemical and Engineering News, "Key Chemical"
sheets, ACS. One-page description of tech. and econ. data
on each indust. important chemical. Updated yearly.
5. Chemical and Engineering News, "Top 50 Chemicals"
tables, ACS. Prod. and eco. growth data. Updated yearly.
6. Satterfield, C. N., Heterogeneous Catalysis in Practice,
McGraw-Hill (1980)
7. Boudart, M., G. Djega-Mariadassou, Kinetics of Hetero-
geneous Catalytic Reactions, Princeton Un. Press (1984)
8. Smith, W. F., Principles of Materials Science and En-
gineering, McGraw-Hill (1986)
9. Psaras, P. A., H. D. Langford, eds., Advancing Materi-
als Research, National Academy Press, (1987)
10. Maugh II, T. H., "Industry Steps Up Quest for Catalysts,"
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Heterogeneous Catalysis," CHEMTECH, 8, 502 (1983);
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12. Bond, G. C., Heterogeneous Catalysis: Principles and
Applications, 2nd ed., Oxford University Press (1987)

13. Adamson, A. W., Physical Chemistry of Surfaces, 4th
ed., Wiley (1982)
14. Gasser, R. P. H., An Introduction to Chemisorption and
Catalysis by Metals, Clarendon Press (1985)
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Technol., 9, 561 (1972); Physics Today, 4, 24 (1975)
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Procedures for Polycrystalline and Amorphous
Materials, Wiley (1974)
20. Little, L. H., Infrared Spectra of Adsorbed Species,
Academic Press (1966)
21. Anderson, R. B., Experimental Methods in Catalysis
Research, v. 1-5, Academic Press (1968-on)
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Characterization and Testing of Catalysts, Academic
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23. Somorjai, G. A., M. A. Van Hove, "Methods of Structure
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Surface Phenomena in Heterogeneous Catalysis," La
Chimica e L'Industria, 52, 128 (1970)
25. Gopalaraman, C. P., "Role of Surface Science in the

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Study of Catalysis," Chemical Age of India, 32, 307 (1981)
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Way," CHEMTECH,11, 652 (1975)
28. Davidson, D. L., "How to Use SEM," CHEMTECH, 11,
670 (1983)
29. Somorjai, G. A., Chemistry in Two Dimensions:
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30. Albert, M. R., J. T. Yates, Jr., The Surface Scientist's
Guide to Organometallic Chemistry, ACS (1987)
31. Laidler, K. J., Chemical Kinetics, 3rd ed., Harper & Row
32. Ruska, W. S., Microelectronic Processing, McGraw-
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McGraw-Hill (1979)
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Automobile Exhaust Pollutants," CHEMTECH, 10, 630,
35. Wei, J., "Toward the Design of Hydrodemetallation
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Perspectives, ed. L. L. Hegedus, Wiley (1987)
36. Chianelli, R., "Catalysis by Transition Metal Sulfides,"
in Surface Preoperties and Catalysis by Non-Metals, ed.
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37. Kittel, C., Introduction to Solid State Physics, 6th ed.,
Wiley (1986)
38. Examples from Strong Metal Support Interactions, ed. R.
T. K. Baker, et al., ACS Symp. Ser. 298 (1986)
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Atomic Orbital Methods: Applications to Transition
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Reidel (1983)
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Chemistry, 4th ed., Ch. 1,2; Wiley (1980)
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Imelik, et al., Elsevier (1985)
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R. K. Grasselli, J. F. Brazdil, ACS Symp. Ser. 279 (1985)
46. Chapters of Applied Industrial Catalysis, v. 3, ed. B. E.
Leach, Academic Press (1984)
47. Breck, D. W., Zeolite Molecular Sieves, Krieger (1984)
48. Mrowec, S., Defects and Diffusion in Solids, Elsevier
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Information Service: A Handbook of Surface Structures,
Reidel (1987)
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Jr., ACS Symp. Ser. 222 (1983) 0

Continued from page 94.
the complexity of the experiment by one dimension.
Next, it is evident that because of the variability
in the gas absorption experiments, a single laboratory
session generates too few data for a meaningful error

analysis. One way out of this difficulty is to pool the
data obtained in several sessions before allowing the
various student groups to analyze it. Also, they should
attempt to get the largest range of L possible with the
equipment and concentrate on replication. At each
session, a student group will carry out duplicate ex-
periments, for example, at just three values of L:
highest, lowest, and at the mid-point to permit a test
of the linearity of the correlation. After three or four
groups have completed their experiments, the data
can be pooled and analyzed. Students who have taken
statistics courses that teach experimental design
might wish to plan a single factorial experiment to
include several student groups. In any event, the be-
tween-group variation can be analyzed to see if this is
a contributing factor to the error.
3) Students should be encouraged to go directly to
the original literature data and examine the actual
measurements without citing a correlation for the
least-squares fit of the data or some other determinis-
tic model. They should be asked to note the scatter in
the data through a variance or coefficient of variation
or some other measure of variability.
4) Because our educational system pays high re-
wards for explaining phenomena, there is a great
temptation for students to try to explain "every-
thing." Without the restraint learned from error
analysis, some students will try to explain random
error, given the opportunity, and of course, the oppor-
tunity seems very tempting when the data are so few
that the scatter is not obvious. Thus, the notion of
caution and even of reluctance to explain can be one
of the important by-products of error analysis.

While we do pay lip service to teaching mathemat-
ical statistics, its use in experimental design is often
neglected. Therefore, student engineers, faced with
experiments with large variability in the measure-
ments, do not understand experimental error. They
tend either to despair or to explain too much. Statisti-
cal analysis of error plus good experimental design
can help students account for error and become in-
formed about the relationship between theory and

Veva Reilly kindly created the scene that is Figure
1. Wm. Dale contributed the data of Figure 2.
Perry, R. H. and Chilton, C. H. (editors). 1973. Chemical En-
gineers' Handbook, 5th edition, section 18, McGraw-Hill, New
York. []




Part 2: Using Design Tools

University of Massachusetts
Amherst, MA 01003

THE CONCEPTUAL DESIGN of a chemical process
involves the invention of the process, i.e., the
selection of the process units, as well as the intercon-
nection between the units. The problem is large, open-
ended, and has a very low success rate associated with
it. Experienced designers in industry normally com-
plete a conceptual design in two days to a week, look
at possible alternatives for another two days to a
week, and then use these results to evaluate whether
additional design effort can be justified.
In order to teach undergraduate students (with no
experience) how to complete a conceptual design, it
was necessary to develop several new tools: 1) How
to use order-of-magnitude arguments to simplify prob-
lems, 2) how to derive design heuristics, and 3) how
to decompose very large problems into a set of small,
simple problems. With these it is possible to use a
J. M. Douglas is a professor of chemi-
cal engineering at the University of Mas-
sachusetts, Amherst. He received his BS
from Johns Hopkins University and his PhD
from the University of Delaware, both in
chemical engineering. He worked at ARCO
and taught at the University of Rochester
before coming to U. Mass. His research
interests include conceptual design,
control system synthesis, and reaction

Robert L. Kirkwood, a research en-
gineer in the Polymer Products Department
of E. I. du Pont de Nemours & Co., has
been involved with process design and
synthesis since 1982. He received his BS
degree in chemical engineering from
Lehigh University in 1982 and his PhD from
the University of Massachusetts in 1987.

*Current Address: E.I. Du Pont de Nemours & Company,
Polymer Products Department, Experimental Station, E262/314,
Wilmington, Delaware 19880-0262

Types of Designs
Order of magnitude estimate (Error about 40%)
Factored estimate (Error about 25%)
SBudget authorization estimationae (Error about 12%)
SProject control estimate (Error about 6%)
Contractors estimate (Error about 3%)

very structured approach to inventing petrochemical
processes that can be taught to undergraduates. In
addition, this systematic procedure can be used as the
basis for a hybrid expert system that can complete a
conceptual design in one to three hours.

The tools described in Part I* of this paper are an
important part in the evaluation part of flowsheet syn-
thesis. However, we still need to generate these dif-
ferent flowsheet configurations. In order to ac-
complish this goal we adopt a hierarchical planning
procedure, similar to that used by Sacerdotti [1] in
With Sacerdotti's approach, we break the problem
down into a hierarchy of abstraction spaces where
more detail is added to the solution at each level in
the hierarchy. Thus, we develop an initial solution
that considers both the starting point and the final
goal, but not the details of how we achieve that goal.
Then, we improve the solution by considering the next
most important set of details, and we continue to add
layers of detail in this manner until we obtain a com-
plete solution. This is the same approach described in
Table 1, except now we will define a hierarchical plan
for Level 1 only. A hierarchical approach of this type
has also been used by Meade and Conway [2] for the
design of VLSI chips.
In order to develop a hierarchical plan we can look
at a number of typical solutions and then consider
what happens if we systematically remove detail from
the solution. If we can find a general framework for
stripping away these layers of detail, then we can re-

*Published in CEE, 21 No. 1 (Winter 1988)

Copyright ChE Division ASEE 1989



The tools described in Part 1 of this paper are an
important part in the evaluation part of flowsheet
synthesis. However, we still need to generate these
different flowsheet configurations. In order to accomplish
this goal we adopt a hierarchical planning procedure ...

FIGURE 1. HDA process flowsheet (maximum energy re-

verse the order of the levels and obtain the desired

Energy Integration
Suppose we consider an energy integrated flow-
sheet for the hydrodealkylation of toluene to produce
benzene (see Figure 1). If we remove all of the heat
exchangers and simply indicate which streams need
to be heated or cooled, we obtain the much simpler
flowsheet shown in Figure 2. There is a systematic
procedure available for designing a large number of
heat exchanger network alternatives if we have a
flowsheet such as Figure 2.
The particular heat exchanger network that we
select normally will affect the optimum values of the
process flows, which may affect the best choice of the
distillation train. Hence, there may be a weak cou-
pling between the design of the heat exchanger net-
work and the remainder of the process, and we may
need to backtrack to our selection of the distillation
train in order to find the best solution.


FIGURE 2. HDA process flowsheet

FIGURE 3. HDA process (separation system flowsheet)

Distillation Column Sequencing
Normally, there are a large number of alternative
distillation sequences that can be used to separate a
mixture into a series of products. We could use heuris-
tics (see [3]) to decide which alternatives to consider,
or we could rapidly generate and evaluate all the pos-
sibilities and then consider only those alternatives
which are economically feasible. Suppose we remove
the distillation train from the flowsheet shown in Fig-
ure 2 and replace it with a black-box (see Figure 3).
For ideal mixtures, it is always possible to accomplish
a set of distillation separations, and the details will
have no effect on the equipment remaining in Figure
3. Hence, we strip away the details of the distillation
train to simplify the flowsheet.

Vapor Recovery System
Figure 2 does not include a vapor recovery system,
but in some cases it may be desirable to include one.
There are a number of types of units that we could
use as a vapor recovery system (e.g., a gas absorber,
a condensation process, an adsorption process), and
there are several locations that we could consider and
all must be evaluated. If we replace any vapor system
in Figure 2 by another black-box unit (see Figure 3),
we do not affect the structure of any of the remaining
units on the flowsheet and we have further simplified
the structure.


General Structure of the Separation System
Not all processes include both a vapor and a liquid
recovery system. For vapor-liquid process, there are
only three types of situations that can arise, depend-
ing on the phase of the reactor effluent (i.e., all liquid,
a two-phase mixture, or all vapor). Suppose we lump
all of the details of the separation system into a single
black-box (see Figure 4), and we specify the details of
what to put into this box later. Now we see that we

FIGURE 4. HDA process (recycle structure flowsheet)

have stripped away another level of detail, but we
still preserve the recycle structure of the flowsheet.

Overall Picture of the Process
Removing layers of detail from the flowsheet has
led to significant simplifications, but now suppose we
draw a black-box around the complete process. We
will be left with the input and output streams (Figure
5). This picture of the process is still significant, be-
cause the raw material costs are usually in the range
from 33 to 85% of the total processing costs. We can
start to focus on the design variables that affect the
product distribution and the optimum process flow-
rates without having to consider any of the other com-
plicating details. From our earlier discussions we
know that the optimum values of the process flows
will change as we add additional layers of detail to the
process, and therefore we must develop the design as
a function of the design variables that affect the pro-
cess flows.


Feed Benzene

loluene Benzene Process
Feed Diphenyl

FIGURE 5. HDA process (input-output flowsheet)

If we add layers of detail to a conceptual design in
the opposite order that we stripped them away in the
previous discussion, we obtain the hierarchical deci-
sion procedure presented by Douglas [4] (Table 2). (A
decision concerning the choice between the design of
continuous and batch processes has also been in-
The procedure uses a depth-first, least-commit-
ment strategy that attempts to complete a base-case
design before we consider any alternatives, because
we might encounter some decision at a later stage in
the design that will make all of the process alterna-
tives unprofitable.
Within each level of the hierarchy the decisions
that need to be made have been identified and prece-
dence ordered, so that the problem of conflicting sub-
goals is avoided. In addition, in Douglas' procedure,

Hierarchy of Decision Levels
0) Input Information
1) Batch vs. Continuous
2) Input Output Structure
3) Recycle Structure
4) Separation System
a) Vapor Recovery System
b) Liquid Separation System
5) Energy Integration
6) More Detailed Alternatives

heuristics (i.e., qualitative knowledge) are used to fix
the structure of the flowsheet, to identify the domin-
ant design variables and to fix some of the secondary
design variables, while algorithms (i.e., quantitative
knowledge) are used to calculate the process flows,
the utility flows, the equipment sizes, and both the
capital and the operating costs as a function of the
design variables.
We use cost calculations to ensure that the process
is profitable over at least some range of the design
variables before we continue on to the next level in
the hierarchy. If the process is unprofitable over the
complete range of the design variables, then we use
the previously identified backtracking points to
examine the process alternatives. If a profitable alter-
native cannot be found, then we terminate the design
An initial evaluation of this hierarchical decision
procedure was undertaken by teaching seventeen
three-day short courses at various industrial sites.
Normally twenty-five students with three to twenty


FIGURE 6. Flowchart of PIP operation

years of experience in design participated. The feed-
back obtained from these courses was used to modify
the hierarchical procedure, but all of the students be-
lieved that the course was much better than the un-
dergraduate course that they had taken. Many of the
experienced designers had previously used some of
the short-cut techniques that were presented, but all
of them were surprised that such a systematic proce-
dure could be developed.
An interactive computer code called PIP (Process
Invention Procedure) based on Douglas' procedure for
process synthesis has been described by Kirkwood [5].
The structure of the program is given in Figure 6, and
the relationship between the qualitative knowledge
bases and the quantitative knowledge bases, as well
as the backtracking points, is indicated. This software
makes it possible for an experienced user to complete
a conceptual design in one to three hours and to find
the best flowsheet alternative in about one day, for
the limited class of processes considered.
The code was written for an IBM-PC/XT in order
to make it simple for a variety of industrial companies

Input Information Menu

to be able to evaluate the synthesis procedure on their
own processes. The companies that have participated
in this effort are: American Cyanamid, Du Pont,
Exxon Chemicals, General Electric, Imperial Chemi-
cal Industries (UK), Mobil, Monsanto, and Tennessee
Eastman. The evaluations have been generally favor-
able, with the main complaint being that the concep-
tual designs that were currently under investigation
in those companies were for multiproduct plants, ag-
ricultural processes, or other processes that were
beyond the scope of the code.


The availability of the PIP program removes the
tedious computational effort from the development of
a conceptual design and the evaluation of process al-
ternatives. Some additional details concerning the
code are presented below, and more information con-
cerning the structure of the code is given in a paper
by Kirkwood [5].

Level 0-Input Data

The menu where the user enters the input data is
shown in Table 3, and a set of responses for a process
that will produce benzene via the hydrodealkylation
of toluene are given in Table 4. Help screens are avail-
able for the appropriate formats for the input data.
The available physical property data can be verified
and default data for the utilities can be changed.

Required Input Data for the HDA Process

The Primary Product is BENZENE
The Production Rate in Lb-mol/hr is 260.00
Its Purity in Mole Fraction of Product is 0.99
Does it form an Azeotrope? (Y or N) N
The Value of the Product Stream in $ Ib-mol is 9.04

Reaction # Reactio
2 2.0 BENZENE=

n Phase Temperature Pressure
(Deg. F.) (Psia)
E= BENZENE+CH4 VAPOR 1150.00 500.00
DIPHEN + H2 VAPOR 1150.00 500.00

Type the desired option and RETURN
1) Process Name
2) Primary Product
3) Reaction Information
4) Feedstream Information
5) Physical Property Date
6) Process Constraints
7) Plant and Site Data
8) Review All Input Information
9) Continue on to Decision Level Menu

Feedstream 1
Component Name Mole Fraction
H2 0.96
CH4 0.040
VAPOR Pres= 500.00 Cost = 1.32
Feedstream 2
Component Name Mole Fraction
LIQUID Pres= 15.00 Cost= 6.40



Level 2-Input-Output Structure of the Flowsheet

For a continuous process, we then proceed to
Level 2, the Input-Output Structure of the flowsheet.
The menu is shown in Table 5. For the process under
consideration, the heuristics included in the code indi-
cate that it is not desirable to purify the hydrogen
feedstream (the program noticed that the gaseous
feedstream is not pure and a heuristic indicates that
usually it is too expensive to purify gaseous
feedstreams), that the feed of an excess of one reac-
tant to the process would not normally be desirable,
that the reversible by-product (identified by PIP as
diphenyl) will be removed (this is a default decision),
and that a gas recycle and purge stream is required
(the code recognizes that the hydrogen reactant can-
not be recycled without methane building up in the
gas recycle loop). The user is required to verify these
decisions, and a function key is available to explain
the appropriate heuristic.
Heuristics are then used to determine the number
of product streams and which components are in each.
The user is then asked for the values (i.e., fuel, by-

Input-Output Structure Decision Menu

F1 (HELP) Type the desired option and RETURN F2 (HEURISTIC)
Review and Results
1) 1.1) Feedstream Purification
(N/A) 1.2) Excess Reactant Specification
1.3) Reversible Byproduct Destination
1.4) Light Component Destination
2) Component Classification
3) Product Distribution Data
3.1) Extents of Reaction
3.2) Reaction Rate Equations
4) Process Constraints
5) Review All Input-Output Information
6) Results of Calculations
7) Return to Decision Level Menu

Input-Output Result Menu

F1 (HELP) Type the desired option and RETURN
1) Design Variable Ranking
2) Flowsheet Picture
2.1) Simple Structure
2.2) With Flowrates
2.3) With Stream Costs
3) Case Study Optimization of Design Variables
3.1) Graphical Output
4) Process Alternatives
4.1) Alternatives to Consider
4.2) Current Process Decisions
5) Return to Level 2 Input Menu

Recycle Structure Decision Menu

Type the desired option and RETURN
Review and Results
1) Reactor Specifications
2) Recycle Component Classification
3) Molar Ratio Specification
4) Process Constraints
5) Review Recycle Structure Information
6) Results of Calculations
7) Return to Decision Level Menu

product, pollution treatment cost, etc.) of each stream.
Finally, information about the product distribution for
the reaction system is required. Either a correlation
of the extents of the reactions as functions of the de-
sign variables or as a kinetic model may be specified.
Once this information has been entered, the user
can proceed to the result menu for Level 2 (see Table
6). Using option 2.2, the value of the design variables
are specified and then the code will generate a picture
of the flowsheet with the total flows of each of the
process streams (Figure 7). For option 2.3, after
specifying values for the design variables, a flowsheet
that shows the stream costs can be generated. Each
of these calculations takes less than one second.
It is possible to examine the complete range of the
design variables and see where the process is profit-
able by choosing option 3.1. Assuming that profitable
operation is obtained over some range of the design
variables, the program will proceed to the next level
in the hierarchy of decisions. A list of the process al-

Input-Output Structure: Stream Flous (Lb-mol/hr)
CONV=.633 PURGE=.400

H2 479.

TOL 269.

12 481.


BEN 265.

DIP 2.18

FIGURE 7. Input-output flowsheet with stream flows


ternatives that could be considered, e.g., recycling the
reversible by-product to extinction, can also be

Level 3-Recycle Structure of the Flowsheet

The menu for Level 3 is given in Table 7, and the
user is required to verify the number of reactor sys-
tems selected, the number of recycle streams gener-
ated, and both the limiting reactant conversion and
the molar ratio of reactants will become new design
variables (if applicable).
The result menu for Level 3 is shown in Table 8.
The new flowsheet with annualized capital and operat-
ing costs (option 2.3) can be generated (see Figure 8).
Option 3.1, a two-variable plot of the profit (economic
potential) with the recycle costs included, is shown in
Figure 9. Note how the range of the design variables
where profitable operation is obtained has decreased

Recycle Structure Result Menu

Type the desired option and RETURN
1) Design Variable Ranking
2) Flowsheet Picture
2.1) Simple Structure
2.2) With Flowrates
2.3) With Stream Costs
3) Case Study Optimization of Design Variables
3.1) Graphical Output
4) Recycle Structure Process Unit Analysis
4.1) Reactor System 1
4.2) Recycle Compressor
5) Process Alternatives
5.1) Alternatives to Consider
5.2) Current Process Decisions
6) Return to Level 3 Input Menu

Recycle Structure: Stream Costs (lUh/yr)
COn=.633 PUICE=.400 IOLI=5.00


217 it/vr

Recycle Structure

S .236
oi -
S 026
o 1
Si -.288
c -
s 550
P i
o o -.812 -
t I
n -1.07
t /
i -1.34
a r

-1 6O I I I I I I
100 188 275 .362 .450 .538 .625 .713 .800
TOLUENE Conversion
FIGURE 9. Recycle structure economic potential plot

significantly, simplifying the task of synthesizing a
separation system. In addition, sensitivity studies of
the effect of changing the gas recycle pressure drop
(if any) and the reactor heat effects can be made (op-
tions 4.1 and 4.2).

Level 4-Separation System

The menu for the synthesis of the separation sys-
tem is given in Table 9. The phase of the reactor
effluent stream is determined at the current optimum
of the design variables where profitable operation is
observed in Level 3, and a heuristic is used to fix the
general structure of the flowsheet (see Figure 10). A
flash calculation is then used to determine the compo-
nent flows in the flash vapor stream (if one is present)
and the value of materials lost in the purge stream. If
these losses are significant, or if there are components
in the gas recycle stream that would be deleterious to

Separation System Menu

Type the desired option and RETURN
Review and Results
1) Separation System Structure
1.1) Reactor System 1
2) Separation Split Block
2.1) Reactor System 1
3) Vapor Recovery System
4) Liquid Separation System
4.1) Glinos-Malone-Nikolaides,
Fenske-Underwood-Gilliland Model
(i.e. short-short-cut)
4.2) Fenske-Underwood-Gilliland Model
5) Return to Decision Level Menu

FIGURE 8. Recycle Flowsheet with economics


0 -
------ ------ -----------

Separation Systei Structure

FIGURE 10. Separation system flowsheet
the reactor performance, the user can install a vapor
recovery system (Table 10). Several types of systems
and locations can be selected. In our example we do
not include a vapor recovery system.
Next we consider the synthesis of a liquid separa-
tion system (see Table 11). Currently, distillation is
the only separation process considered. We determine
the best sequence by exhaustive enumeration (it takes
about five seconds to complete this calculation). A
flowsheet showing the best distillation sequence, the
process flows, and the equipment sizes for the design
variables indicated is presented in Figure 11. Detailed
design information for each piece of equipment and
each of the process streams is available by pressing a
function key. The results of a one variable optimiza-
tion study are shown in Figure 12, and again we see
that the range where profitable operation is possible
is significantly reduced.
Level 5-Heat Exchanger Network Synthesis

We use the procedure described by Hohmann [6],
Umeda et al [7], and Linnhoff and Flower [8] to calcu-
late the minimum heating and cooling loads for the
process, and we use the surface area targeting proce-
dure of Townsend and Linnhoff [9) to estimate the
heat exchanger area required. With this information
we can estimate the capital and operating costs of the
heat exchange system. In addition, we add the
minimum approach temperature to our list of signifi-
cant design variables.
Evaluation of Process Alternatives

At this point we have completed a base-case design
and obtained a reasonable estimate of the optimum
design conditions. Hence, we return to our list of pro-

cess alternatives, and we attempt to find a better
flowsheet. We first consider alternatives that corres-
pond to decisions where there were no heuristics
available (e.g., the recycle of reversible by-products),
and then we consider alternatives that change the
structure of the flowsheet at the early levels in the
By proceeding to Level 6 we can also evaluate the
effects of alternate reactor configurations (plug flow-
CSTR combinations, temperature profiles, and feed
distributions), complex distillation column alterna-
tives, and alternative heat exchanger networks.
Hence, we can explore a number of alternatives with
relatively little effort.

Teaching Process Synthesis

In the undergraduate design course, we describe
each of the decision levels in detail, we discuss the
heuristics that are available for making the decisions,
and we derive the short-cut design equations that are
used to calculate the costs. The base-case design for
one process is developed in this way and a list of pro-
cess alternatives is generated. Then the alternatives

Vapor Recovery System Result Menu

Type the desired option and RETURN
1) Evaluate Vapor Recovery System Flows
2) Choice of Vapor Recovery System
2.1) Adsorption
2.2) Condensation
> 2.3) No Vapor Recovery System
3) Flowsheet Picture
3.1) Simple Structure
3.2) With Flowrates
3.3) With Stream Costs
4) Case Study Optimization of Design Variables
4.1) Graphical Output
5) Process Alternatives
6) Return to Level 4 Menu

Liquid Separation System Result Menu

Type the desired option and RETURN
1) Design Variable Ranking
2) Flowsheet Picture
2.1) Simple Structure
2.2) With Flowrates
2.3) With Stream Costs
3) Case Study Optimization of Design Variables
3.1) Graphical Output
4) Distillation Train Evaluation
4.1) All Possible Sequences
4.2) Best Sequence vs. Design Variables
4.3) Define Liquid Separation System
5) Process Alternatives
6) Return to Level 4 Menu


Liquid Separation System: Stream Flows (Lb-tol/kr)
CO1K=.567 PURGE=.400 O1LR=5.00

FIGURE 11. Liquid separation flowsheet with stream
are considered in an attempt to find the best process
flowsheet. Moreover, the results of the short-cut cal-
culations are compared to a rigorous computer-aided-
design solution in order to evaluate the accuracy of
the approximate calculations.
The homework assignments in the course focus the
student effort on developing a base-case design for a
different process in a step-by-step manner by hand,
at least for the early levels. Stand-alone software (a
program developed by Glinos and Malone [10], is used
to synthesize and evaluate the distillation sequences,
while data for the synthesis of a heat exchanger net-
work is generated in part by hand and in part using a
CAD package. The goal of these assignments is to

Liquid Separation System
PUliE=.400 I0LR=5.00
E -.074
c I
o i
a 1 114
Si -.153
o o -.232
t i
e $ -.272
i -.312
a r
-351 '
.450 .494 .538 .581 .625 .669 .713 .756 .800
TOLUENE Conversion
FIGURE 12. Liquid separation system economic potential

reinforce an understanding of the procedure.
Now that PIP is available we would introduce
another set of homework assignments, which would
be given in parallel with the development of the stu-
dents' base-case design, that would explore process
alternatives. This would allow students to focus their
thinking on the physics and the economic trade-offs
involved in the process and to minimize the amount of
time they spend on calculations. Near the end of the
course we would then give other assignments where
the students would be expected to design new plants
in a two-day time period. The focus in the class discus-
sion would be on the similarities and differences be-
tween various types of processes.
The current version of the software is applicable
to a limited class of petrochemical processes, and we
hope to extend it to solids processes, polymer proces-
ses, bio-processes, and batch processes. Research is
underway to develop the necessary procedures. How-
ever, even in its present form we expect that it should
provide a useful teaching tool.
We believe that it is possible to teach the concep-
tual design of chemical processes to undergraduates.
Their lack of experience can be overcome to a great
extent by providing new design tools and software
which make very rapid calculations possible, so that
even when they explore alternatives that experienced
designers know would not be profitable, the time pen-
alty will be small. The availability of the software also
makes it possible for them to gain experience more
1. Sacerdotti, E. D., "Planning in a Hierarchy of Abstraction
Spaces," Artificial Intelligence, 5, 115 (1974)
2. Meade, C., and L. Conway, Introduction to VLSI Systems,
Addison-Wesley Publishing Co., Reading, MA (1980)
3. Nishida, N., G. Stephanopoulos, and A. W. Westerberg, "A
Review of Process Synthesis," AIChE J., 27, (3), 321 (1981)
4. Douglas, J. M., "A Hierarchical Decision Procedure for
Process Synthesis,"AIChEJ., 31, 353 (1985)
5. Kirkwood, Robert L., James M. Douglas, and Michael H.
Locke, A Prototype Expert System for Synthesizing
Chemical Process Flowsheets," Compt. and Chem. Eng.,
12,4, pg. 329-343 (1988)
6. Hohmann, E. C., "Optimum Networks for Heat Ex-
change," PhD Thesis, University of S. California (1971)
7. Umeda, T., J. Itoh, and K. Shiroko, "Heat Exchange Sys-
tem Synthesis," CEP, 74, (7), 70 (1978)
8. Linnhoff, B., and J. R. Flower, "Synthesis of Heat Ex-
changer Networks," AIChE J., 24, (4), 633 (1978)
9. Townsend, D. W., and B. Linnhoff, "Surface Area Targets
for Heat Exchanger Networks," Annual Meeting of the
Inst. of Chem. Engrs., Bath, UK, April (1984)
10 Glinos, Konstantinos, "A Global Approach to the Prelimi-
nary Design and Synthesis of Distillation Trains," PhD
Thesis, University of Massachusetts, Amherst (1984) 0


Continued from page 115.

if the standard graphical construction based on Figure
1 starting with C*i not less than 0.85 (say) leads to a
final value for C*N lower than required, then Eq. (16)
can be used as a good approximation of Eq. (3). This
approximation gets better as N increases and/or C*N
increases and/or n decreases. If, on the other hand,
the reverse graphical construction based on Figure 1
starting with C*N/C*N-1 not greater than [20(n-1)]-1'"
(say) leads to a final value for C*o larger than unity,
then Eq. (5) can be used as a good approximation for
C*l,opt as obtained from Eq. (3). This approximation
gets better as N decreases and/or C*N decreases and/
or n increases.


C = concentration of substrate, molm-3
Co = concentration of substrate at the inlet
stream of the first reactor, mol-m-
Ci = concentration of substrate at the outlet
stream of the ith reactor, mol-m-3
C*i = normalized concentration of substrate at
the outlet stream of the ith reactor
C*i,opt = normalized concentration of substrate at
the outlet stream of the ith reactor leading
to the minimum overall reactor volume
Dai = Damkohler number for the ith reactor,
Dai,min = Damk6hler number for the ith reactor lead-
ing to the minimum overall reactor volume,
j = dummy integer variable for the summa-
K' = kinetic constant, mol"nm3"
K* = dimensionless kinetic constant, (K'/Co")
m = dummy integer variable for the summa-
n = apparent number of substrate binding sites
per enzyme molecule
N = total number of reactors in the series

Q = volumetric flow rate through the reactor
system, m3-s-1
Vi = volume of the ith reactor, m3
Vi,min = volume of the ith reactor leading to
minimum overall reactor volume, m3
v = kinetic rate, mol-m-'s-1
Vmax = maximum kinetic rate of the enzyme under
study, mol-m-'s-1


1. Lehninger, A. L., Principles of Biochemistry, Worth
Publishers, New York (1982)
2. Arima, K., in Global Impacts of Applied Microbiology
(M. P. Starr, Ed.), John Wiley and Sons, New York, p.
278 (1964)
3. Michaelis, L., and M. L. Menten, Biochem. Z., 49, 333
4. Segel, I. H., Enzyme Kinetics: Behavior and Analysis
of Rapid Equilibrium and Steady-State Enzyme Sys-
tems, John Wiley and Sons, New York (1975)
5. Bailey, J. E., and D. F. Ollis, Biochemical Engineer-
ing Fundamentals, McGraw-Hill Book Co., New York
6. Atkinson, D. E., Ann. Rev. Biochem., 35, 85 (1966)
7. Adair, G. S., J. Biol. Chem., 63, 529 (1925)
8. Pauling, L., Proc. Nat. Acad. Sci. U.S., 21, 186 (1935)
9. Hill, A. V., Biochim. J., 7, 471 (1913)
10. Hill, C. G., An Introduction to Chemical Engineering
Kinetics and Reactor Design, John Wiley and Sons,
New York (1977)
11. Aris, R., The Optimal Design of Chemical Reactors,
Academic Press, New York (1961)
12. Levenspiel, O., Chemical Reaction Engineering, John
Wiley and Sons, New York (1972)
13. Bischoff, K. B., Can. J. Chem. Eng., 44, 281 (1953)
14. Luyben, K. C., and J. Tramper, Biotechnol. Bioeng.,
15. Malcata, F. X., Can. J. Chem. Eng., 66, 168 (1988)
16. Stephenson, G., Mathematical Methods for Science
Students, Longman, London (1973)
17. Spiegel, M. R., Mathematical Handbook, McGraw-
Hill Book Co., New York (1968)
18. McCabe, W. L., and E. W. Thicle, Ind. Eng. Chem.,
19. Peters, M. S., and K. D. Timmerhaus, Plant Design
and Economics for Chemical Engineers, McGraw-
Hill Book Co., New York (1980) 0

books received

Carbon: Electrochemical and Physicochemical Properties, by
Kim Kinoshite. John Wiley & Sons, Inc., 1 Wiley Drive, Som-
erset, NJ 08875-1272 (1988); 533 pages, $75.00

Mixing Equipment (Impeller Type); AIChE, 345 East 47 Street,
New Yor, NY; (1988) 40 pages, AIChE members $12, others $18

Petrochemicals: The Rise of an Industry, by Peter H. Spitz.
John Wiley & Sons, 605 Third Ave., New York, NY 10158
(1988); 588 pages, $29.95 cloth

New Membrane Materials and Processes for Separation,
edited by Kamalesh Sirkar and Douglas Lloyd. AIChE, 345
East 47th Stre., New York, NY 10017 (1988). 177 pages, $20
members, $40 others.

Organic Chemistry, 4th Edition, by T.W. Graham Solomons.
John Wiley & Sons, 605 Third Ave., New York, NY 10158-0012
(1988). 1186+ pages

The Organic Chem Lab Survival Manual: A Student's Guide to
Techniques, by James W. Zubrick. John Wiley & Sons, Inc.,
One Wiley Drive, Somerset, NJ 08873 (1988). 322 pages, $15.60
soft cover



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