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 Front Cover
 Table of Contents
 On the treadmill of the windfall...
 Professor Neal Amundsen
 News
 Ch E division activities
 Departments of chemical engineering:...
 Environmental studies
 Process computers and chemical...
 Mass transfer operations
 Audio-module experiments
 Non-Newtonian pipeline flow
 Diffusion and reaction in catalyst...
 A simple forced convection...
 Zone refining
 Enzyme-catalysis experiment
 Complex chemical engineering...
 Book reviews
 Back Cover


































Chemical engineering education
http://cee.che.ufl.edu/ ( Journal Site )
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Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/AA00000383/00033
 Material Information
Title: Chemical engineering education
Alternate Title: CEE
Abbreviated Title: Chem. eng. educ.
Physical Description: v. : ill. ; 22-28 cm.
Language: English
Creator: American Society for Engineering Education -- Chemical Engineering Division
Publisher: Chemical Engineering Division, American Society for Engineering Education
Publication Date: Summer 1971
Frequency: quarterly[1962-]
annual[ former 1960-1961]
quarterly
regular
 Subjects
Subjects / Keywords: Chemical engineering -- Study and teaching -- Periodicals   ( lcsh )
Genre: serial   ( sobekcm )
periodical   ( marcgt )
 Notes
Citation/Reference: 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
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Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 01151209
lccn - 70013732
issn - 0009-2479
sobekcm - AA00000383_00033
Classification: lcc - TP165 .C18
ddc - 660/.2/071
System ID: AA00000383:00033

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Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Table of Contents
        Page 101
        Page 102
    On the treadmill of the windfall of windmill research & Letters from readers
        Page 103
    Professor Neal Amundsen
        Page 104
        Page 105
    News
        Page 106
    Ch E division activities
        Page 107
    Departments of chemical engineering: Illinois Tech
        Page 108
        Page 109
        Page 110
        Page 111
    Environmental studies
        Page 112
        Page 113
        Page 114
        Page 115
    Process computers and chemical engineering education
        Page 116
        Page 117
        Page 118
        Page 119
        Page 120
        Page 121
    Mass transfer operations
        Page 122
        Page 123
        Page 124
        Page 125
    Audio-module experiments
        Page 126
        Page 127
    Non-Newtonian pipeline flow
        Page 128
        Page 129
    Diffusion and reaction in catalyst pellets
        Page 130
        Page 131
        Page 132
        Page 133
    A simple forced convection experiment
        Page 134
        Page 135
        Page 136
        Page 137
    Zone refining
        Page 138
        Page 139
        Page 140
    Enzyme-catalysis experiment
        Page 141
        Page 142
        Page 143
    Complex chemical engineering systems
        Page 144
    Book reviews
        Page 145
        Page 146
        Page 147
        Page 148
    Back Cover
        Back Cover 1
        Back Cover 2
Full Text












cheica en gin ei ed




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Your parents didn't put you through school

to work for the wrong company.


We think we're the right company.
We're big, but not too big.
We've climbed halfway up Fortune's
Directory of 500 Largest Corporations.
But compare the share of sales that
paper companies plow back into research.
Suddenly, we're no less than second.
What does this mean when you're
considering a career in paper production?
It means that production engineering
at Westvaco is influenced by continuous
research feedback. It means lots
of development work. Diversification.
Excitement. Research has given us
processes and equipment to make better


papers for printing, packaging, and
structures. But we need to continually
improve our processes. Speed them up.
Make them more efficient. That's your job.
Research has given us useful by-products,
too. High-grade specialty chemicals for
coatings, pharmaceuticals, inks and waxes.
And activated carbon adsorbents and
systems to alleviate water pollution.
But we need good engineers to recover
these by-products more efficiently. To
improve them. To find new uses for them.
In our company, working with paper
and paper by-products can mean good
careers in design engineering,


fluid dynamics, specialty chemicals,
process control, process R & D
and product development. And more.
Chances are, whatever you liked
and did best in college, we're doing
right now. And doing it well.
But find out for yourself. See our
campus representative, or contact
Andy Anderson, Westvaco,
299 Park Avenue, New York 10017.
Remember, all your parents want for
you is the best of everything. The least
you could do is join the right company.

Westvico
An equal opportunity employer










EDITORIAL AND BUSINESS ADDRESS
Department of Chemical Engineering
University of Florida
Gainesville, Florida 32601

Editor: Ray Fahien
Associate Editor: Mack Tyner
Business Manager: R. B. Bennett

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SUMMER 1971


Chemical Engineering Education
VOLUME 5, NUMBER 2 SPRING 1971


Special Pa1Wo4a4&V 9dae
126 Audio-Module Experiments
G. E. Klinzing
128 Non-Newtonian Pipeline Flow
P. J. F. Kanitz and J. D. Ford
130 Diffusion and Reaction in Catalst Pellets,
J. B. Anderson
134 A Simple Forced Convection Experiment,
0. C. Sandall and D. A. Mellichamp
13o Zone Refining,
R. R. Hudgins
141 Enzyme-Catalysis Experiment,
D. M. Borber and J. M. Scharer

Departments
103 Views and Opinions
On the Treadmill of the Windfall of
Windmill Research, J. M. Douglas
103 Letters from Readers
104 The Educator
Professor Neal Amundsen
108 Departments of Chemical Engineering
Illinois Tech, R. C. Kintner and D. T. Wasan
112 The Curriculum
Environmental Studies, F. W. Kroesser
122 The Classroom
Mass Transfer Operations, W. L. Conger
144 Problems for Teachers
Complex ChE Systems
Wooyoung Lee and Yuichi Ozawa
145 Book Review
106, 147 News
107 Ch E Division Activities

Feature Articles
Process Computers and Ch E Education
T. M. Stout and J. H. Hiestand

CHEMICAL ENGINEERING EDUCATION is published quarterly by the Chemical
Engineering Division, American Society for Engineering Education. The publication
is edited at the Chemical Engineering Department, University of Florida. Second-class
postage is paid at Gainesville, Florida, and at DeLand, Florida. Correspondence
regarding editorial matter, circulation and changes of address should be addressed
to the Editor at Gainesville, Florida 32601. Advertising rates and information are
available from the advertising representatives. Plates and other advertising material
may be sent directly to the printer: E. 0. Painter Printing Co., P. 0. Box 877,
DeLeon Springs, Florida 32028. Subscription rate U.S., Canada, and Mexico is $10 per
year to non-members of the ChE Division of ASEE, $6 per year mailed to members
and $4 per year to ChE faculty in bulk mailing. Individual copies of Vol. 2 and 3
are $3 each. Copyright ( 1971, Chemical Engineering Division of American Society
for Engineering Education, Ray Fahien, Editor. The statements and opinions
expressed in this periodical are those of the writers and not necessarily those of the
ChE Division of the ASEE which body assumes no responsibility for them. Defective
copies replaced if notified within 120 days.










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CHEMICAL ENGINEERING EDUCATION










views and opinions


On tke treadmill of Me windfall of windmill research


J. M. DOUGLAS
University of Massachusetts
Amherst, Mass.

The latest ploy in the university fund raising
game is to develop pollution free power sources.
However, individual proposals are no longer chic
and interdisciplinary research is going out of
vogue. Instead, the "bureaucrats with the bills"
are now looking for interuniversity proposals and
for regional solutions to problems.
Recently our dean issued an indirect directive
calling for interdisciplinary research proposals
concerned with a number of specific types of pol-
lution free power sources; and the list included
windmills. In an attempt to get "one-up," I de-
cided to see if it was possible to develop an inter-
university research effort. Thus, I asked Chemical
Engineering Education to perform a public serv-
ice by publishing my list of proposed topics for
windmill research. This list was put together
without any thought, but if any of you are in-
terested perhaps we can submit a joint proposal.

1. Visual Pollution of Windmills-According to a moti-
vational study undertaken by the Santa Barbara Insti-
tute for the Bewildered (and sponsored by the National
Science Foundation, Grant No. G6438), one of the major
reasons the use of windmills fell into disrepute was the
fact that they are most unsightly. (The other major rea-
son was that Don Quixote has opposed to all products of
the military-industrial complex). A statistical analysis of
the data revealed that the visual pollution caused by wind-
mills was even worse than that due to electrical trans-
mission lines. Hence, in order to create a resurgence of
windmills we need to develop the technology for installing
them underground.
2. Thermal Pollution of the Air-In order to meet the
power demand in 1984 of 13.628 x 1056 joule microseconds
it will be necessary to build 13.628 x 1022 windmills.
While the heat generated by friction in each windmill is
not very great, it has been estimated that the total heat
generated by all these additional windmills will be suffi-
cient to raise the ambient temperature throughout the
world by 8.624�F. Again, at first glance, this does not
seem to be a significant factor, but in addition to com-
pletely melting the polar ice cap in 13.628 years (which
would lead to complete flooding of all the world's land
mass), it would also raise the average body temperature
1.83290 and therefore greatly increase the world supply
of hot blooded males. Hence, estimates indicate that the
population would increase 2.764 fold in the 13.628 years


remaining before complete disaster, and man would be
guilty of even greater crimes against humanity. To avoid
this eco-catastrophe we need to develop the technology of
water-cooling the windmills. Alternately we could study
the use of nuclear energy to power the windmills, rather
than wind, because less heat is generated by friction with
this approach.
3. Orbital Stability of the Earth.--It is well known that
all windmills in the northern hemisphere rotate clock-
wise while all those in the southern hemisphere rotate
counterclockwise. However, since most of the industrial
nations are located north of the equator, the tremendous
excess of windmills which will exist there can be expected
to cause the earth's orbit to process. Calculations show
that on Thursday, April 24, 2073 at 4:23 P.M. the town of
Slobbering Jaw, Minnesota will be coincident with the
North Pole of the earth and that the polar cap will com-
pletely cover the U.S. Hence we need to establish a re-
search team to study real estate prices in South America.
4. Preventing the Eco-Disaster-After reading the pre-
dictions of all the leading politicians, particularly thons
in lesser offices than they aspire to, it is readily apparent
that the world is headed toward an eco-disastei which
only the leadership of those politicians, and lots of money;
can avert. Fortunately, I have a research idea, which if
it receives the rock bottom funding of $1.365 billion pe*
day, will prevent this eco-tragedy. The idea is based enat
little publicized observation of Dr. Hollering Bascombe,
Harvard, Class of 03, who noted that there is a geological
cliff formation in South Hadley, Mass. which produces
louder echoes than anywhere else in the world. Hence I
propose that we build a technical school near this spot-
The South Hadley Institute of Technology, and we will
admit as students all of those great, heart-warming, in-
telligent, idealistic . . . kids who attended the Woodstock
Rock Festival. Next, we will arrange a large number
of windmills in a parabolic arc facing the cliffs, so that
the school is at the focus of the parabola. The windmills
will be operated in a reverse fashion so that they blow air
toward the cliffs. Now, if we get all the Woodstock kids,
who shouted to the heavens for hours for the rain to
stop, to yell the initials of the university- S.-.-.-. at
the top of their lungs until they are hoarse, their cry will
echo off the cliffs, be carried back to the cliffs by wind
from the parabolic reflector of windmills, and thus rever-
brate forever. Moreover, the country will finally wake-up
and heat the cry of ECHO-HOARSE-S - - -.


from our READERS
Sir: The point raised by Dr. Davidson in the Spring issue,
on the proper handling of variable heat capacity terms, is
well taken. Dr. Davidson's arguments can, however, be
presented in a much simpler manner.
(Continued on page 147)


SUMMER 1971


Chrm







































THE CHIEF
by some of his Frontiersmen
B ACK IN THE DAYS when it was not yet
clear how far the analytical insights of the
mathematically inclined could usefully penetrate
the forests of practical Chemical Engineering or
cross the lakes of empirical knowledge, there
arose a frontiersman of unusually penetrating
gaze and persistent hardihood. Not only did he
start to explore the country himself in a series
of daring expeditions, either on his own or with
a lone companion, but with a Pisgah-sight of the
vastness and variety of the terrain he brought
together a band of voyageurs and mountain men
and fired them with a zeal for exploring and push-
ing back boundaries. No band of frontiersmen
has had a better "Chief" than Neal Amundson,
and least not on the frontiers of scholarship and
teaching. The statement stands whether you put
his department alongside others in science and
engineering or match it with all comers on the
University scene, for leadership of the quality


[ -j educator


NEAL AMUNDSEN

OF MINNESOTA


.. ."leadership of the quality Amundsen has
shown at Minnesota is as rare as a temperature
of 80� on a January day in Minnesota."


Amundson has shown at Minnesota is as rare as
a temperature of 80� on a January day in Minne-
apolis !
Prosaically enough, the title "Chief" goes back
to the times when Chemical Engineering was but
one division in a Department of Chemistry, but
though all those little fiefdoms have been reor-
ganized many times and Chemical Engineering
has long been a department of the Institute of
Technology with its official "Head," the more
familiar title persists appropriately enough as an
unofficial mark of esteem and a witness to the fact
that not all prophets are without honor in their
own territory.
When Neal Amundson was made Acting Head
of Chemical Engineering in 1949, he took over a
department that was at low ebb. It was fortunate
that the efforts that he and others made to bring
in a new Head were frustrated, for it allowed
Dean Spilhaus to put on the required pressure
and make Amundson himself the permanent Head
-an administrator of the only valid and safe kind,
reluctant enough to be saved from the snares of
power politics and efficient enough to make admin-
istration a means and not an end. Certainly Spil-
haus, himself an unusual Dean, must have seen
the promise of a 33 year old professor who had
spent as much time in departments of Mathe-
matics as he had in Chemical Engineering. For
after getting his Bachelor's degree in Chemical
Engineering in 1937, Amundson worked for Esso
at Baton Rouge before returning to Minnesota to
take a Ph.D. in Mathematics. As a bridge be-


. . . he brought together a band of voyageurs
and mountain men and fired them with a zeal
for exploring and pushing back boundaries.


CHEMICAL ENGINEERING EDUCATION








In the analysis of the control and stability of
chemical reactors, Neal has produced a long
series of papers which go back to the early 50's.

tween the two he picked up an M.S. in Chemical
Engineering along the way; his thesis-the first
purely theoretical one to be accepted in the depart-
ment-concerned a problem that he suggested
himself, the application of matrix theory to staged
processes. Then in 1944-45 he was at Brown Uni-
versity at a time when the chances of war had
brought together in one place an unusually large
group of distinguished mathematicians. On his
return he was the effective cause of getting one of
them, Stefan Warshawski, to head the Mathe-
matics Department in the Institute of Technology
and build it up into a first-class department, re-
markable among departments of mathematics for
the willingness of so many of its members to dis-
cuss problems with engineers. Nor did Neal's
connection with the Department of Mathematics
end there, for in 1964 when it found itself tempo-
rarily leaderless he stepped in as a head pro-tem
to steer it through some particularly critical
rapids.
But to return to the early explorations that
Neal made with individual scouts. One such area
was the theory of distillation with Andy Acrivos
for company, an area in which they found some
remarkable systematic results and laid the basis
for work that Neal later did with others on com-
puter methods for distillation. Another was that
of chromatography and ion exchange with Leon
Lapidus, an area to which he returned more than
fifteen years later to break new ground with
Hyun-Ku Rhee. In the analysis of the control and
stability of chemical reactors Neal has produced
a long series of papers which go back to the early
'50's when he first had the insight to apply the
methods of non-linear mechanics and the enig-
matic Bilous was fiddling all night with an ancient
analog computer. This line has had many ramifi-
cations in exploring all sorts and conditions of
reactors. From the simplicities of the stirred tank
with a single reaction he advanced to two-phase
reactions, polymerizations, tubular reactors and
other distributed forms and most recently to spray
reactors. All these forays are marked by the pre-
cision of thought that is proper to the mathemati-
cal arts and the map of the territory which he
brings back is always accurate and as complete
as the conditions of the terrain and the resources
of the expedition allow. To the average explorer


it has always been a source of amazement that he
could manage so many of these forays while still
providing the leadership of the troupe and doing
so many of its chores. He might say that he had
been fortunate in his scouts-Acrivos, Bilous,
Goldstein, Kuo, Lapidus, Liu, Luss, Rudd, Rhee,
Schmeal, Schmitz, Valentas, Warden, Wissler,
Zeman - to mention only an alphabetical few-
but they would say that they had been more than
fortunate in having a guide who could not only
lead their first excursion but also teach them the
lore that has allowed them to go still farther on
their own.
IN 1954-55 AMUNDSON took his first and only
sabbatical, leaving the Northwest Territory to
spend a year in Cambridge, England at a critically
interesting time. A year later they would have
been dispersed, but that year saw Denbigh, Danck-
werts, and Sellers all there under the professor-
ship of Fox and the department soon to expand
into new quarters. For Neal there was the oppor-
tunity not only to work up some earlier lines of
research and exchange ideas with a fresh group of
colleagues, but also to lay plans for strengthening
his crew and for many of his later explorations.

. . . his scouts-Acrivos, Bilous, Goldstein, Kuo,
Lapidus, Liu, Luss, Rudd, Rhee, Schmeal, Schmitz,
Valentas, Warden, Wissler, Zeman

This break followed the difficult years of
planning and moving into a new building in which
he had yeoman help from Isbin, Preckshot, Mad-
den and Ceaglske-some of the original members
of the department. In 1956 the first non-chemical
engineer, microbiologist, Tsuchiya, joined the
band to reinforce the tradition of intimate coop-
eration with other disciplines, for strong connec-
tions with bacteriology, as well as with mathe-
matics and chemistry, had existed since the
1920's. During the academic year of 1958-59 Piret
departed for the highest circles of international
intrigue just as a motly crew were assembling on
the east bank of the Mississippi. Even those
brought up as chemical engineers were a little
"irregular"; Ranz had travelled a lot with me-
chanical engineers and coped with the fogs of
aerosol science while farmer Frederickson, for
all his annular, Avian and non-Newtonian revels
at Wisconsin, had the seeds of his later botani-
cal interests and the germs of his bacterio-
logical predilections at work within him. After
post-docing in Holland and surviving a spell


SUMMER 1971








in the Air Force, Dahler, an Hirschfeldian
theoretical chemist, contributing not only a new
expertise and the highest intellectual stand-
ards to the group but also a new awareness
of the world around. From Edinburgh Aris
("almost a mathematician") came that year, and
in 1959 Scriven, the rectitude of whose technical
upbringing was matched by the variety of his
interests and thoroughness of his work. It was
never true that the department had a prejudice
against chemical engineers or experimentalists,
though the Dean was once heard to wonder when
the next would be hired. The next in fact was a
chemical physicist, the fire-eating Davis, whom
Dahler attracted to the troupe and who, like the
others, took to the routine mapping as conscien-
tiously as to the more exciting excursions, peri-
odically returning from Hilbert space to teach
compressible flow. From Admiral Rickover via the
Johns Hopkins came the urbane and able Keller
in 1964, his biomedical interests reinforcing the
teaching and research of Frederickson and Tsuchi-
ya. Yankee Carr and plainsman Schmidt, a brace
of gifted experimentalists, followed a year later
to strengthen and broaden the work in kinetics
and surface chemistry and the far-travelled Hick-
man, with interests ranging from electro-chemis-
try and ecology to Teilhard de Chardin and the
Fish, joined a few years later. Such a various
bunch would never have been knit without the
superb leadership they found in "The Chief."
Most recently the troupe had an even larger ad-
dition when four materials scientists-Hutchin-
son, Nicholson, Sivertsen and Toth-moved en
bloc from a redistributed metallurgy department
and Macosko came from Princeton, to polymerize
in place and help cement the structure. As it did
before in the interactions with biology, chemistry
and mathematics, so now with materials science
is the process of cross-fertilization in teaching
and research beginning again.

P ERHAPS IT WAS THE problems of cross-
fertilization that attracted Neal to the art of
growing orchids, another project-this time for
personal rather than public good-that blossomed
under his hand. A few years ago, his wife's gift
of African violets, for "the man who had every-
thing," started this interest which, followed up

It was never true that the department had a
prejudice against chemical engineers or
experimentalists...


When he disappears at meetings, it is usually to
the local orchid growers and he is commonly
rumored to count their chromosomes before
going to bed at night

with characteristic thoroughness, soon led him to
graduate to orchids. When, a year or so ago, he
built a new house, it was distinguished not only
for the tastefulness of its architecture-to which
he would readily admit that his wife made a major
contribution-but also for a 20' x 30' greenhouse
now stocked with a few hundred orchid plants.
When he disappears at AIChE meetings, it is
usually to the local orchid growers and he is com-
monly rumored to count their chromosomes before
going to bed at night.
To recite the honors and awards that Neal has
received would be like decorating a voyageur's
buckskins with boy scout badges. But his Regents'
Professorship perhaps deserves mention. In the
University of Minnesota a handful of professors
are entitled "Regents' Professors," an honor for
which they are proposed and judged by their
peers. From the morass of the present-day state
university, overburdened with top-heavy adminis-
tration and forced to make meretricious advances
to all and sundry, the distribution is intended to
select a few outstanding faculty members among
those who have kept faith with the traditions of
scholarship and service. It would be a strange in-
terpretation of the charge of that selection in any
university if Neal Amundson were not among
those few.


UN s news

ONE WEEK COURSES AT
SAN FERNANDO VALLEY STATE COLLEGE
Control Systems Design. A short course covering basic
principles of control system design for linear, non-linear,
continuous, and discrete-data systems using modern opti-
mization techniques will be presented July 26-30, 1971.
Applications to chemical and petroleum industries will
include the analyses -and design of control systems for
distillation columns, blending systems, and chemical re-
action systems. The fee is $300. Contact E. J. Hriber, 227
Engineering Building, San Fernando Valley State College,
Northridge, California 91324.
Analog Simulation and Computation. A lecture-laboratory
course in basic concepts and advanced techniques for the
solution of engineering problems by analog simulation will
be presented August 2-6, 1971. No prior knowledge of
analog computers is required. The fee is $300. Contact
J. F. Paul, 414 Engineering Building, San Fernando Valley
State College, Northridge, California 91324.


CHEMICAL ENGINEERING EDUCATION













CHEMICAL ENGINEERING DIVISION ACTIVITIES


Ninth Annual Lectureship

Award to William R. Showalter
The 1971 ASEE Chemical Engineering Divi-
sion Lecturer was Dr. William R. Showalter of
Princeton University. The purpose of this award
lecture is to recognize and encourage outstanding
achievement in an important field of fundamental
chemical engineering theory or practice. The 3M
Company provides the financial support for this
annual lecture award.
Bestowed annually upon a distinguished engi-
neering educator who delivers the Annual Lec-
ture of the Chemical Engineering Division, the
award consists of $1,000 and an engraved cer-
tificate. These were presented to this year's
Lecturer at the Annual Chemical Engineering
Division Meeting June 23, 1971 at the U.S. Naval
Academy. Dr. Showalter spoke on "The Art and
Science of Rheology."


PREVIOUS LECTURES

1963, A. B. Metzner, University of Delaware,
"Non-Newtonian fluids."
1964. C. R. Wilke, University of California, "Mass
transfer in turbulent flow"
1965, Leon Lapidus, Princeton University, "As-
pects of modern control theory and applica-
tion."
1966, Octave Levenspiel, Illinois Institute of
Technology, "Changing Attitudes to Reactor
Design."
1967, Andreas Acrivos, Stanford University,
"Matched Asympototic Expansions."
1968, L. E. Scriven, University of Minnesota,
"Flow and Transfer at Fluid Interfaces."
1969, C. J. Pings, California Institute of Tech-
nology, "Some Current Studies in Liquid
State Physics."
1970, J. M. Smith, University of California at
Davis, "Photo chemical Processing-Photo
Decomposition of Pollutants in Water."


William R. Schowalter was born in Milwaukee, Wis-
consin, in 1929. He attended public schools in a suburb of
that city and then entered The University of Wisconsin,
from which he graduated with a Bachelor of Science de-
gree in Chemical Engineering in 1951. Following a year
at The Institute of Paper Chemistry in Appleton, Wiscon-
sin, he moved to the University of Illinois and received
a Master of Science degree in Chemical Engineering in
1953. After a period in the Service he returned to the
University of Illinois and completed his Ph.D. degree
in 1957. Since that time he has been a member of the
faculty of Princeton University, where he currently
serves as Professor of Chemical Engineering.
Professor Schowalter's research deals with theoretical
and experimental aspects of fluid mechanics, with spe-
cial emphasis on flows of rheologically complex fluids.
He has applied his interests in these areas to industrial
problems during summer periods spent with chemical and
petroleum companies. He also serves as an industrial con-
sultant on problems in fluid mechanics.
During 1964 Professor Schowalter was on academic
leave at the University of Minnesota, and in 1970 he was
at the University of Cambridge as a Senior Visiting Fel-
low of the British Science Research Council. He has also
served for several years as a member of the Chemical
Engineering Advisory Board to the McGraw-Hill Book
Company. Professional Societies of which he is a member
include the American Institute of Chemical Engineers,
American Chemical Society, and Society of Rheology.
April, 1971.


SUMMER 1971

























R. C. KINTNER and D. T. WASAN


Armour Institute of Technology was incorpo-
rated as such on June 20, 1895, although the
elements of a technical educational institution ex-
isted in various preceding organizations dating
back to 1874. A curriculum in chemical engi-
neering was first offered in 1901 under the direc-
torship of Professor W. T. McClement but the real
beginning of the department dates from the
arrival at the Institute of Professor Harry
McCormack in 1904. For the next forty-two
years he developed the department and kept it at
the top of the list of fully accredited chemical
engineering curricula. It was only coincidental that
its name began with the first letter in the alpha-
bet. Merging with Lewis Institute of Arts and
Sciences in 1940, the name became Illinois Insti-
tute of Technology. Movement from the old Build-
ing into the present modern structure was ac-
complished in 1947. Considerably more room,
especially for graduate research, became avail-
able to an expanded teaching staff of eight;
Rushton, Peck, Kintner, Swanson, Smith, Sel-
heimer, Griswold, and Resnick.
EDUCATION EMPHASIS AND DEVELOPMENT
The four-year undergraduate teaching pro-
gram in engineering has always been the primary
effort at IIT. For over forty years the department
enjoyed a complete monopoly on chemical engi-
neering education in Chicago. If a Chicago stu-
dent wished to follow such a career he had to
either come to Armour Institute or leave the city
for a college a hundred or more miles away. As late
as 1937, ninety eight percent of the undergraduate
student body was from Chicago and the adjacent
suburbs. But to acquire and keep a progressive
108


IC

S H

Illinois Institute of Technology
Chicago, Ill.

instructional staff it became necessary to insti-
tute graduate courses. Advanced courses are also
in demand as continuation education efforts in
every large industrial city and IIT was and still
is the agency for this in Chicago. About 1935 the
evening undergraduate work was expanded and
integrated with the day program. Every teacher
was expected to teach an evening course as a part
of his total work load. Almost every course of
the curriculum is offered in the evening. Every
course in the regular program is available every
semester. Taught, for the most part, by the same
teachers who teach the course in the daytime, the
evening work is part of each accredited curricu-
lum. Several (about ten percent) of each gradu-
ating senior class have completed a seven-year
evening degree program. It is not uncommon to
see a man in his forties walk across the platform
at Commencement while his teen age children
cheer from the audience.
The undergraduate program has been con-
tinuously changed. It is very doubtful that any
student has graduated upon the precise curriculum
on which he entered. Everyone became a special
case. The department chairman spent considerable
time advising as to substitutions for courses
which no longer existed. Each phase, or style, of
undergraduate education has been reflected in
these changes. The old "wash tub" chemistry ap-
proach to the problems of industry served very
well until modified by the Unit Operations ap-
proach around 1920. A very special type of Chemi-
cal Engineering Thermodynamics was developed
in the late 1930s as a result of the summer school
course at IIT given by visiting Professor B. F.


CHEMICAL ENGINEERING EDUCATION












The four-year
undergraduate
r teaching program
has always been
the primary effort
at lIT.


H. McCormack
Chairman
1904-1946
Dodge of Yale University. When Kinetics became
a key aspect of chemical engineering education,
work in Chemical Reaction Engineering was in-
stituted. The work involving analog computers
was developed with the very important element
that the students maintained the equipment. They
took it apart, put the pieces back together and
made it work. An improved method of operating
the experiments in the big general laboratory was
introduced when larger enrollments made the old
methods cumbersome. The work in Fluid Me-
chanics was repeatedly modernized. With the ar-
rival of new staff members a high grade effort in
Mass Transfer was instituted. Every acquisition
to the staff has left his mark upon the educational
structure that exists today. It is fully expected
that the process will continue with the infusion
of new ideas by new and very bright young men.

THE LABORATORY
Much of the knowledge of the beginning of
chemical engineering laboratory work at Armour
Institute of Technology has been lost in the limbo
of ancient history. A teaching laboratory can not
be purchased. Those who have tried have always
ended up with a museum. Each experiment must
have an objective and must be a challenge to the
student. The answer must not be available from
either books or fraternity files.
It is certain that the Unit Operations outlook
was developed by Professor McCormack through
the Senior Projects medium. It has been said that
the Unit Operations Laboratory at Armour In-
stitute of Technology was the first one in the
country. The laboratory instruction book contrib-
uted many of the experiments in the cooperative
book on Applications of Chemical Engineering,
edited by Professor McCormack. Each senior stu-


dent, with a student partner, chose a project from
a list prepared by the instructional staff or pro-
posed one of his own. Usually the project involved
the building of equipment. At the end of the aca-
demic year, Professor McCormack would choose
the most promising of these from an instructional
viewpoint and have the skilled technician build a
more sophisticated version of the equipment. Such
experiments were modified each year until better
ones replaced them. Experiments in thermody-




WJs, o A teaching laboratory
can not be purchased.
. �w t Those who have
tried have always
ended up with a museum.



J. H. Rushton
Chairman
1946-1953
namics, kinetics and process control have been de-
veloped by the same procedures. Many an alumnus
can come back on Visitor's Day and note with
pride, "Hey! There's my old equipment." They
all have a stake in it. The laboratory portion of
the curriculum required the completion of twenty
four of these home-grown and continuously modi-
fied experiments over a span of three semesters.
The result was a chemical engineering graduate
who could devise a practical way to evaluate the
results of industrial processes and to determine
the best way to develop them.

GRADUATE STUDY
The graduate program of the department has
changed significantly during the last thirty years.
The first MS degree in Chemical Engineering was
awarded in 1932 and the first PhD degree seven
years later. The changing attitude to graduate
curricula had its beginning with the graduate
course offered in the department by the leading
educator Dr. Olaf A. Hougen in the spring of 1937.
Dr. Barnett F. Dodge and Dr. Vasili I. Komarew-
sky offered graduate courses in thermodynamics
and catalysis, respectively, at the summer gradu-
ate institute held on the campus in 1940. These
two leaders also imparted a significant direction
in these areas of graduate education at IIT.


SUMMER 1971












SThe general philosophy
... has been to
encourage faculty to
seek answers to impor-
tant industrial problems
through fundamental
approaches to them.

R. E. Peck
Chairman
1953-1967

A total of over twenty courses are offered
either in the evening or day programs in the de-
partment. About half of those in the evening are
taught by the regular faculty, the remainder in-
volving experts from industry. The current course
list includes courses in the more fundamental
areas of chemical engineering and in the applied
subfields. A partial list includes heat transfer,
mass transfer, fluid mechanics, transport phe-
nomena, topics in dispersed phase systems, chemi-
cal reaction engineering, process dynamics and
controls, thermodynamics, optimization, air pol-
lution, environmental control, food engineering,
plant design and process economics and manage-
ment of the chemical enterprise.
An industrial advisory committee for Chemical
Engineering was established two years ago.
Through the activities of this committee there has
been a constant and continued improvement in
communication with industry, as a result of this,
instruction in several of the courses offered by
the department has noticeably improved.
The research interests of the faculty encom-
pass areas in the fundamentals of chemical engi-
neering as well as many subfields in engineering
technology. Current research interests of the
faculty are in Dispersed Phase Systems, Drying,
Interfacial Phenomena, Water Desalination, Water
Pollution, Aerosol Technology, Turbulent mixing
of jets, Reactor Engineering including biological
reactions, Analysis of the Human Circulation and
Biomedical Simulation. The general philosophy
of the departmental chairman has been to en-
courage the faculty to seek answers to important
industrial problems through fundamental ap-
proaches to them. The departmental faculty has
been assisted in accomplishing this goal by in-


dustry. This help has taken the form of fellow-
ship and scholarship grants, equipment grants and
research assistance.
The department has seen a large expansion in
research facilities and graduate enrollment in the
last decade. As a result of this rapid growth, the
present faculty of the department has published
widely. Over 40 papers and articles have been
published in the past two years alone and more
than 25 papers have been presented at the national
and international technical meetings over the
same period. In addition to teaching and research,
the faculty in general has actively participated at
the local and national level of AIChE. Most of the
faculty members are serving on the National Pro-
gram Committee of AIChE in various subfields of
their specialties and have chaired or co-chaired
various technical symposia in recent years.





The cooperative
Environmental
Engineering f4
Center is being
developed on the
campus


B. S. Swanson
Chairman
1967-Present
Members of the Chemical Engineering faculty
frequently participate in research activities in the
Institute of Gas Technology and IIT Research In-
stitute. These two internationally known centers
are located on the institute campus. The research
program on the human circulation is carried out
at the Michael Reese Hospital which is located
near the campus and the hybrid simulation of bio-
medical systems has been carried out with a team
from the hospital of the University of Pennsyl-
vania. In addition to these interdisciplinary re-
search activities, the cooperative Environmental
Engineering Center is being developed on the
campus and has recently received a considerable
endowment from Pritzker Foundation.
Finally, it can be stated with pride that the
Chemical Engineering department at IIT has
graduated a considerable number of competent en-
gineers, several of whom have obtained significant
national prominence in their professional careers.


CHEMICAL ENGINEERING EDUCATION








The university where classes never end.







Union Carbide's research centers are in many ways like a university.
In any one of them you'd meet a faculty with advanced degrees in practically every science.
You'd see them scribbling complicated formulas on blackboards and working with complex
scientific instruments.
You'd hear them discussing the uses of tremendous pressures, unearthly heat, intense
cold-as well as problems in oceanography, outer space, atomic energy.
In any one of our many research centers and laboratories which we maintain here and
abroad, you'd sense the vast and diversified scope of Union Carbide technology.
Finding better ways to do things is the aim of this research. And when a better way is found
to revolutionize an industrial process-or simply develop a new product for your comfort or
convenience-our research scientists don't graduate.
They move on to new and exciting challenges created by today's advancing technology.
________ .


U I
CARBIDEf


For additional information on our activities, write to Union Carbide Corporation, Department of University
Relations, 270 Park Avenue, New York, N.Y. 10017. An equal opportunity employer.










Curriculum


ENVIRONMENTAL STUDIES


F. WILLIAM KROESSER
Tufts University
Medford, Mass. 02155


On the Tufts University campus, as elsewhere
in this country, interest in the Environment is
high. You can see this in the extent of student in-
volvement in activities related to the environment.
You also see it in the number of teachers bringing
environmental problems into their classrooms.
This includes teachers in a wide variety of disci-
plines covering the social sciences, basic sciences,
and engineering.
The question, of course, arises as to how to
best use this intense and diversified interest. The
result has been a number of Environmental Pro-
grams springing up around the country. These are
quite varied in their stated purposes, in their
leadership and organization, and in their method
of obtaining financial support. For those of you
who would like to know the specifics on these pro-
grams, Congressional Representative Daddario,
from Connecticut, has made a survey. As Chair-
man of the House subcommittee on Science, Re-
search and Development, he sent questionnaires
to Colleges and Universities in 1969 and compiled
the results in the form of a booklet known as the
Daddario Study.' The study is a good introduction
to the kinds of Environmental Programs at var-
ious schools. For more recent information to up-
date this study, the group which keeps up on
these programs is the Scientists Institute for
Public Information.2
I WOULD LIKE TO describe one kind of pro-
gram, one which we recently began at Tufts.
It is essentially multi-disciplinary in nature, not
residing in any one department. It does not have
the kind of funding associated with a department,
but it is separate, and has its own degree require-
ments.
Let us look at the reasons for developing such
a program. First, some students would like to
major in this field, and the program allows them
to do this without being limited to a traditional
department. There are certainly a handful of stu-


F. William Kroesser is an Assistant Professor in the
Chemical Engineering Department at Tufts University.
He received his undergraduate education at the Lafayette
College and did his graduate work at the University of
Rochester. In addition to his work in the Chemical Engi-
neering Department, he is Moderator of the Mystic River
Watershed Association, is a member of the Somerville
Conservation Commission, serves on the Education Pro-
gram Committee of the AIChE, and teaches Multidisci-
plinary courses in the Environment.

dents each year who want to do this. Essentially,
majoring in the environment means that the stu-
dent first expresses an interest and takes such
courses. Later he decides whether he would like
to specialize in the social, political, scientific or
engineering aspects of the field. Presently, tra-
ditional departments do the reverse, and our stu-
dents are quite emphatic in their preference for
this new approach.
A second purpose for having such a program
is that it allows students to minor in this field.
These students might be engineers or they might
be social scientists desiring some exposure to the
problems of the environment. They want to re-
main in their traditional disciplines. Having such
a program gives them the opportunity to become
involved on a part time basis. Also the existence
of a program means that the courses are properly
catalogued so that a student can find what he
wants. We compiled our own lists which describe
the courses and emphasize the relation of each to
the environment. College catalogs do not effec-
tively fill this purpose.
A third purpose is to serve the needs of those
students with a smaller interest in the environ-
ment. Almost every student should have some


CHEMICAL ENGINEERING EDUCATION


4Q M4ufdiei~cipkaa~r �~~ p'zo~lcm








exposure to the environment and the program
gives him a wide variety to choose from, as well
as a place to seek advice on his choice.
Finally, the program encourages people from
diverse backgrounds to work together. Some of
our courses are oriented toward local community
problems.3 The needs are real and the interest is
high.

T HE PROGRAM WAS created by a group of
faculty and students who were interested in a
multi-disciplinary approach. After a tentative
outline of goals was made, students were encour-
aged to develop their own individual programs in
the environment. A few hardy souls answered the
challenge. They visited departments, discussing
with each the courses which might properly fit
into their program. We learned a great deal this
way. Most importantly, we found that the number
of offerings was much greater than anticipated.
This is common everywhere, I think, and arises
because a college catalog records history rather
than predicts the material to be taught in the
coming semester.
As a result of the work these students put in,
we had a listing of interesting courses, and a list-
ing of faculty who would volunteer to be advisors.
When students put enthusiasm into this kind of
program it gains momentum. For example, some
faculty members not directly involved offered to
help. When we pointed out the need for a certain
course not yet available, we found faculty who
were willing to create the course.
In order to save future students the trouble
of visiting so many departments, we have com-
piled lists of the actual program planned by each
student, as examples, and some recommended pro-
grams that we developed.
Eventually we had a number of students who
had participated for one to two years. Each of
these students had a program planned for his col-
lege education. However, I don't think you could
say that Tufts had a Program. We had a group of
interested people and a list of interesting courses,
but you wouldn't call it a Program.
To decide on a regular program we entered a
debate which included the entire group of stu-
dents, faculty, and administrators who had shown
interest. Using the Winter Study Period to do this
we came up with the plan shown on Table 1.
As you see, the student chooses one of the
three areas of emphasis. He begins with the intro-
ductory course, which we would like to have in


Interest in the Environment is high ... the Daddario
Study is a good introduction to the kinds of
Environmental Programs at various schools

the freshman year, and which give him a broad
survey of the need for a health environment and
the problems involved in trying to obtain it. Then
he picks an area of emphasis, and chooses from a
list of courses dealing in that area. For each of
these areas, the student has available two lists of
courses: one called recommended courses and the
other called related courses. One can see that these
areas are interdependent and therefore, courses in
each area should be considered to be related
courses for both the other areas.

ECOLOGY &
r NATURAL RESOURCES 8
INTRODUCTORY POLLUTION & SENIOR
COURSES -----> ENVIRONMENTAL -- SEMINARS
HEALTH
MAN IN HIS
ENVIRONMENT

Finally, we have what I call Senior Seminars,
whose purpose is to bring together the knowledge
gained in these various fields, and to use it to
solve an existing problem. That is, the students
are given some task in their community. The task
involves problems in Man's Interaction with his
Environment. The students are asked to use
their previous training, to learn to work together,
and to develop a solution.
Table 2 shows how this fits in with the Uni-
versity degree requirements. The Liberal Arts
College at Tufts has a Plan of Study whereby a
student develops his own program in consultation
with several academic advisors. The Program is
submitted to a board of review and, if accepted,
the student can earn a degree for that program.
The students who began early in our program
are using this kind of option. We require two in-
troductory courses, and then five courses chosen
from the areas of specialization. Two additional
advanced courses help give some depth to the plan.
Table 2. Degree requirements
2 Introductory Ecology Courses
5 Courses from Biology, Chemistry, Geology, Physics,
Economics, Political Science, Sociology, Ch.E., C.E.
2 Advanced Courses from above list
2 Courses on multi-disciplinary approaches
2 Advanced Courses on current problems
1 Independent Study Project
Foundation requirements-4 courses; Distribution require-
ments-8 courses; Free electives-6 courses.


SUMMER 1971









Environmental Studies give our students the
opportunity to minor in this field while
remaining in Chemical Engineering.

Next, two courses of a multi-disciplinary nature,
and two courses on current problems must be
chosen. The senior seminars could fall in these
categories. An independent study project is us-
ually included.
At the bottom of Table 2 University founda-
tion and distribution requirements and free elec-
tives are listed. This adds up to 32 courses, which
would take four years on a four course per se-
mester system. These requirements result in a
Liberal Arts degree. The Engineering College has
a set of requirements which are quite similar.
They would lead to an Engineering degree. How-
ever, it is not accredited by ECPD as the degrees
in each of our Engineering Departments are. The
students now in the program are about equally
divided between Liberal Arts and Engineering.
Table 3. Introductory Courses
Ecology
Natural Resources; use and disposal
Pollution
Environmental Health
Public and Political Attitudes
N OW I WILL GO through the topics, showing
'what each would include. Table 3 shows the
material for the introductory courses. This is
probably a two semester sequence, with the two
courses covering Ecology, Natural Resources, Pol-
lution, Health and the Attitudes toward these. We
do not have such a sequence yet. Instead, the Bi-
ology Department moved their Ecology course to
the freshman year by removing all prerequisites.
It covers one semester which is probably about
the correct amount of time. We are still talking
about the other course, and when it is finally
created it will probably cover the other four areas
you see listed. In the meantime, we can get along
without it, since all but the most naive student
can pick up the introductory material on his own.
The main benefit of such a course is to help stu-
dents choose an area of specialization.
Table 4 shows some of the courses for the
Ecology and Natural Resources specialty. This is
the list of recommended courses. Here we draw
considerably from the Biology and Geology De-
partments. The student has already taken the
Ecology course, and probably needs one of the
basic Biology courses. Then he might take some of
the Biology courses and some of the Geology


Table 4. Ecology and Natural Resources
Biology courses
Advanced Ecology
Evolution
Biology of Populations
Biostatistics
Geology courses
Oceanography
Geomorphology of Rivers
Geomorphology of Beaches and Coastlines

courses. That last course is particularly relevant
to our area, since removal of sand by builders has
caused a number of homes to be washed into the
sea. It is said that Logan International Airport
is next to go.
For related courses, one can find a long list of
courses in sciences, including Chemistry, Biology,
Geography. A stronger emphasis on the use of
natural resources might be good, but such courses
are not now available. Our Chemical Engineering
course on the Chemical Process Industries empha-
sizes the uses of natural resources and the prod-
ucts which result. We are now emphasizing how
these materials eventually return to nature. Such
a course might also be included. Our History
Department offers courses on the History of
Science and Civilization, which are quite good
for this area. We do have a specific list of such
related courses, but it is quite long, and so I have
not shown it here.
In the specialty called Pollution and Public
Health, in Table 5, we have a program similar to
what the Civil Engineers at Tufts have been
doing for a long time. However, this program is
less technical and deals more in the social sciences.
The science courses emphasize the basic resources
of a city; air and water, while the social science
courses are centered around urban problems. Re-
search on noise is just beginning, and we expect to
include those courses soon.
There is a sizable list of related courses, and
again I have not shown them. The list includes
additional courses in Biology, Chemistry, Eco-

Table 5. Pollution and Public Health
Biology of Populations
Water Resources
Water Supply and Sewerage
Sewage and Water Treatment
Water and Wastewater Chemistry
General Chemistry
Urban Economics
Public Administration
Problems in Urban Social Planning
Contemporary Social Change


CHEMICAL ENGINEERING EDUCATION









nomics, Engineering, History, Political Science
and Sociology. One course we were delighted with
was a Medical School course on Environmental
Health. Another course, the Political Science
course on Administrative Law, is a good example
of how relevant some of these courses can be. The
course this year was centered around the question
of how one would set up a federal water pollution
control administration. As more engineers become
involved, more emphasis can be placed on how to
go about developing the appropriate engineering
tests on which the law might be made workable.
The third specialty, shown on Table 6, deals
with the interaction of man with his environment.
It attempts to show what man does to his environ-
ment and what the environment does to man, and
then focuses on the means for changing the en-
vironmental situation. The courses shown here
are of a nontechnical nature. However, some ex-
posure to the science and technology of the prob-
lems is recommended.
Table 6. Man in his Environment
Social Control of Industry
Science and Civilization
Citizenship and Political Behavior
Social Psychology
Urban Sociology
The Sociology of Law
The list of related courses is similar in kind,
and somewhat longer than this one. Again I must
emphasize that the recommended courses in each
of these three areas are to be considered related
courses for each of the other areas.
The upper level seminars are still in the ex-
perimental stage, although several have been
offered. These are generally offered in the Ex-
primental College, which accepts non-traditional
courses, and courses which do not have a specific
field.
One senior seminar offered two years in suc-
cession deals with the environmental quality of
the Mystic River Basin. The Mystic River Valley
encompasses 85 square miles to the north of Bos-
ton, with a variety of development including some
of the areas most intensive industry as well as
some of its most handsome wooded areas. The
Tufts University Campus is located in the valley.
The courts deals with four aspects of the area: air
quality, water quality, land use and recreation.
The students survey the area, analyze air and
water samples, and plan good land use. The course
culminates in a symposium in which the appro-
priate town government officials and the various


pollution agencies are invited. Technical reports3
are prepared and made available to cities and
citizens groups.
The Mystic River Valley, though quite small,
includes almost a dozen towns. Because of the lack
of metropolitan control and planning, we were the
first to consider the entire basin in one study.
The results met with enthusiastic response by the
community, which has now organized a watershed
association4 which resides at Tufts.
Another senior seminar was called the Future
of our Environment. The students formed small
groups and each focused on one problem. The
members of each group were from a variety of dis-
ciplines, and each member was to bring to bear
his own background to help in a mutual solution.
Class time was spent in background lectures on the
causes and effects of the problems, student dis-
cussions on the methods to be used to solve them
and on final reports by each group. Biologists and

There is a lot of work to be done here . . . In the
past we have said that it is really a political or
social problem . . . The political and social
scientists are at the same time calling it a
problem in technology.

Politicians, as well as Engineers were brought
in as guest lecturers.
The student reports were as varied as they
were informative. On group, composed of students
majoring in Religion, Philosophy, and Chemical
Engineering traced the relationship between the
political, psychological, technical and religious
aspects of the pollution problems. At the other
extreme, another group came up with specific
recommendations to manufacturers of detergents
and to household consumers to reduce eutrophica-
tion of waterways.
Why should Chemical Engineers be interested
in Environmental Studies? After all, there may be
very little engineering in such a program. First,
there may be little engineering here, but there is
a need for more, and we can meet this need. These
activities are widespread, and will continue to
grow.
Second, there are the benefits our students
derive. These are many and varied and I have al-
ready mentioned them. The most important, I
think, is the opportunity for our students to minor
in this field while remaining in the Chemical Engi-
neering Department. They will learn a great deal
(Continued on page 121)


SUMMER 1971











PROCESS COMPUTERS


AIn 9nddtt&f V/iew


and Chemical Engineering Education


T. M. STOUT and J. H. HIESTAND
Profimatics, Inc.
Woodland Hills, California, 91364

Let's start this paper with a few assertions
about computers:
*Process computers as discussed here are on-line digi-
tal computers for closed-loop regulation, optimization and
sequencing of industrial processes. In a much broader
philosophic sense, they are a means for placing corpo-
rate managements (business and technical) in almost
direct control of production facilities.
eProcess computer systems were first installed about
ten years ago, but the number of installations has grown
rapidly and the activity will continue to expand.
*Process computers can produce significant improve-
ments in process performance under the right conditions.
Prepared for presentation at the AIChE 61st Annual
Meeting, Los Angeles, California, December 1-5, 1968.
eEssential elements of successful process computer
installations are a suitable application, well-chosen objec-
tives, adequate hardware and software, a competent and
dedicated project team, and aggressive management.
eInstallation of a process computer requires many
different skills and therefore necessitates a team effort by
many people.
eInstallation of a process computer is engineering in
its finest sense.
These assertions are based on extensive ex-
perience in the field and are regarded as funda-
mental truths. Some of their consequences for
chemical engineering education will be discussed
in the remainder of the paper.

SOME SYMPATHY FOR ENGINEERING EDUCATORS

Before getting into the subject at hand, we
want to express our sympathy for today's engi-
neering educators in their attempts to deal with
the winds that now blow through the campuses.
We are not speaking of such current problems as
protests against the war, the draft, and manufac-
turers of products used in connection with these
unhappy activities. Nor do we mean the perennial
problems of "publish or perish" or the related
conflict between teaching and research. We are
talking about problems of the engineering schools
in coping with today's rapid changes in technology
and their attempts to meet this challenge by em-
phasis on science as opposed to engineering.1, 14-.1


Thomas M. Stout is president of Profimatics Inc., an
engineering firm specializing in the design and installation
of advanced process control systems. He was formerly
manager of the Advanced Systems Department, Bunker-
Ramo Corporation, where he participated in and super-
vised feasibility studies, design and evaluation of com-
puter control systems for petroleum refining, chemical,
cement, steel, paper, and other process industries. Stout
taught at the University of Washington (Seattle) for six
years and also worked for Schlumberger Instrument
Company and Emerson Electric Manufacturing Company.
He earned a BSEE at Iowa State College, and MS and
PhD degrees at the University of Michigan.
John H. Hiestand is a member of the professional staff
of Profimatics, Inc., where he has done consulting on ad-
vanced control technology for the process industries and
developed mathematical models for kraft pulping, bleach-
ing, alcohol, ethylene oxide, butadiene extraction, cata-
lytic reforming, fluid catalytic cracking, and other pro-
cesses. He previously worked on computer control sys-
tems for pulping and papermaking at the Bunker-Ramo
Corporation and General Electric, and he did papermaking
research at the West Virginia Pulp and Paper Company.
Hiestand received his BSChE at Lehigh University, and
MSE and PhD degrees at the University of Michigan.

The digital computer is, in reality, a post-
World War II development, even though it roots
go back much farther. Process computers are even
more recent, having been introduced in the late
1950's. Having graduated somewhat ahead of the
process computer, we had no academic training
in this field. It would be very easy to suggest that
engineering curricula should be changed to cover
this new activity-in the same way that every
engineering alumnus probably feels the colleges


CHEMICAL ENGINEERING EDUCATION








. . . the treatment of hypothetical control problems
as mathematical exercises . . . is unfortunate
. . . remedies are manifold . . .


should teach his current specialty, whether it be
heat exchanger, crankshaft or telephone circuit
design. However, we will resist this temptation,
and we urge educators to reject pressures of this
type.
Fortunately, it is not necessary to overturn
a modern chemical engineering curriculum to fit
the needs of students who will be working with
process computers. As will be seen subsequently,
this field calls upon almost all of the subject
areas now taught in progressive departments.
Anything the student learns will be useful at some
time or other, and very little that a student learns
will be wasted.
On the other hand, it is impossible to cram into
one student, in the regulation number of credit
hours required for a bachelor's or even a master's
degree, all the material that will prove useful in
his process computer work. In this field, as in
others, students must be convinced that educa-
tion is a life-long activity and that a diploma is, as
somebody put it, only a "license to learn." This
attitude must be stressed, if only because there
will be other new technical fields in the future,
just as process computers are new today.

FUNDAMENTAL TRAINING FOR ENGINEERS
To cope with the expansion of technology and
the limited hours available in an undergraduate
program, engineering educators must emphasize
fundamentals, and we wish them well in their
struggle to decide what is fundamental. Probably
it means a stress on basic science-mathematics,
physics and chemistry. However, our work with
process computers causes us to urge that engi-
neering schools should produce engineers. And
what does this mean?
An early definition of engineering, put forth
by the civil engineers in 1818, described it as
the art of utilizing the forces of nature for the
use and convenience of man. A more recent
definition2 states that Engineering is a general
term covering many branches of technology . . .
through which the materials and forces of nature
are developed and controlled for various purposes
of mankind. These branches differ among them-
selves in areas of specialization, size, and historical
background, but the following characteristics

SUMMER 1971


which are common to all branches identify them
as belonging to the field of engineering:
* A concern with specific practical results, usually
achieved by means of technical projects involving planning,
design, execution, and operation;
* The application of principles of science, together
with judgments based upon knowledge of the state of
the art in the branch of technology involved, with due
consideration of cost factors, in carrying out these pro-
jects;
* A capacity for organizing and directing the human
skills essential to the accomplishment of complex projects.
Emphasis has been added to stress that practical
results, cost factors, and human skills are as much
a part of engineering as principles of science. Pro-
cess computer work at its best involves all of
these characteristics and is, as we have already
mentioned, engineering in the finest sense: creat-
ing something that works on a schedule, and at
a price.
It probably goes without saying that, to train
engineers, the teachers should themselves be engi-
neers. In the automatic control field, perhaps more
than others, instructors are frequently young
PhD's with recent degrees and very little engi-
neering background in the sense described above.
The result, evident in the literature of the field, is
treatment of hypothetical control problems as
mathematical exercises. The situation is unfortu-
nate, and remedies are manifold: hiring experi-
enced engineers as faculty members (waiving, if
necessary, the usual requirement of a doctorate
for candidates whose other credentials are attrac-
tive); having faculty members undertake part-
time or summer work in industry; persuading in-
industry (instead of government) to sponsor uni-
versity work ;13 and participating actively in pro-
fessional society activities concerned with current
technology. These corrective measures will not be
easy to accomplish, but few worthwhile results
ever are.

RECOMMENDED SUBJECTS FOR PROCESS
COMPUTER ENGINEERS
Training of chemical engineers has undergone
great changes in the last fifty years or so. The
changes were capably summarized by Dr. Olaf A.
Hougen, Professor Emeritus of Chemical Engi-
neering at the University of Wisconsin, in an ad-
dress3 presented at the dedication of the H. K.
Benson Hall at the University of Washington on
March 3, 1967. His first-hand account of the his-
tory of chemical engineering education is ex-

117









tremely detailed, very interesting, and deserves
wide circulation. Early in his address, Dr. Hougen
made the following remarks about his own under-
graduate education:
"In 1911-15 there were no courses in unit operations,
none in diffusional principles, none in material and
energy balances, none in chemical thermodynamics!
There were no courses in process measurements, none
in heat and mass transfer, none in applied kinetics,
process design or transport phenomena! I saw no
laboratory equipment in unit operations! There was
little or no quantitative approach to chemical-engi-
neering problems. The use of higher mathematics be-
yond the calculus was too time consuming to be of
practical value as it is today with our high-speed
computers. We had no textbooks and no handbooks in
chemical engineering! In the main library we were
referred to the German texts of E. Hausbrand and of
J. P. Kuenen. The slide rule was still an exciting
novelty! Instruction in mathematics, the basic sciences
and other branches of engineering was excellent, but
there was no integration between chemistry and engi-
neering."

As Dr. Hougen pointed out later in his address
and as we are all aware, recent years have seen
the introduction of courses in process design,
applied kinetics, process control, computer pro-
gramming, physical chemistry, differential equa-
tions, measurements, process dynamics, and trans-
port phenomena. All of these subjects are impor-
tant for chemical engineers concerned with pro
cess computer application. Yet, essential as they
are, they are not enough.
Suggested lists of courses or subjects to be
studied by process control systems engineers have


been presented by many people with knowledge of
the field.4-10 A summary of their suggestions would
produce the list given in Table I.
The subjects listed in Table I provide a back-
ground for process computer work in the chemical
and petroleum industries. For other industries,
other useful courses could be added, e.g., courses
in metallurgy and ceramics for engineers con-
cerned with iron and steel production or minerals
processing. But most of the subjects will be valu-
able for any kind of process computer application.
We have omitted the introductory science,
mathematics, English and other humanities
courses which form the basis for an engineering
education. Even so, the list is long; we will not
attempt to justify putting each subject on the
list.
Many subjects are listed under Mathematics.
Some of these subjects will be covered in engi-
neering courses, either as topics in mathematics
or in connection with an engineering subject,
while others may only be available from a mathe-
matics department. Analog and digital computer
programming, essential subjects for process con-
trol systems engineers, are listed here although
they may actually be taught in any of several
departments.
One group of subjects, those concerned with
Engineering Management, will be valuable to all
engineers, including those who do not become
involved with process computers. Indeed, one
might argue that engineering schools have an
obligation to cover these subjects since it is man-


Mathematics
Calculus
Differential Equations
Ordinary
Partial
Operational calculus
Matrix Algebra
Numerical methods
Probability and statistics
Fourier Analysis
Optimization
Linear Programming
Gradient Methods
Variational Calculus
Dynamic Programming
Computer programming
Analog
Digital
Boolean (logical) algebra


TABLE I
Suggested Courses for Process Control Systems
Engineers
Chemical Engineering
Inorganic and organic chemistry
Stoichiometry
Material and energy balances
Mass and energy transfer
Thermodynamics
Reaction kinetics
Unit operations
Process dynamics
Instrumentation (measurements)
Control Engineering
Basic control theory
Time-domain analysis
Frequency-domain analysis
Stability
Synthesis
Sample-data systems
Multivariable systems
Nonlinear systems
Adaptive systems


Engineering Management
Personnel supervision
Industrial organization
Elementary accounting
Evaluation of investments
Scheduling (PERT, CPM)
Contracts and specifications
Electrical Engineering
Network analysis
Field theory
Electronics
Logic devices
Other Fields
System concepts
Economics
Operations research
Information theory
Psychology
Human engineering


CHEMICAL ENGINEERING EDUCATION









agerial skill that distinguishes engineers from
scientists. It is interesting to note that Dr. Hou-
gen3 lists "Contracts and Specifications" among
the subjects that moved out of the chemical engi-
neering curriculum in the 1930's to make room
for more technical subjects. Perhaps subjects of
this type should be restored to the curriculum.
We have already acknowledged that any one
student cannot include all of the worthwhile
courses in his program. This impossibility leads
to two conclusions: (1) the need for further study
beyond the last academic degree, and (2) the need
for a team approach to process computer pro-
jects.* The second of these conclusions reinforces
the argument for development of management
skills in the education of process systems engi-
neers.
Considering the long list of subjects which
form a desirable background for process com-
puter work, it might appear reasonable to advo-
cate training through the PhD for engineers going
into this field. Plausible as it might appear, this
idea is not necessarily sound. For one thing, it
imposes an undue burden on engineers desiring
to enter the field and restricts the supply of avail-
able manpower. A more important consideration,
however, is the nature of PhD training.
Mardon and Cripps have recently published a
paper'1 on training systems engineers. They rec-
ognize three sources of potential systems engi-
neers: the PhD, the young BS or MS, and the ex-
perienced engineer from industry, each with his
advantages and disadvantages. They believe each
of these individuals will need additional training
and on-the-job experience. Mardon and Cripps
think a recent BS or MS may be the best candi-
date, although they point out that he lacks ex-
perience in taking a large-scale unsolved prob-
lem, defining it and carrying it through to a solu-
tion.
Discussing the disadvantages of PhD's, Mar-
don and Cripps write:
"Unfortunately, -a PhD is all too often characterized by
a second set of qualities which make him undesirable
to industrial environments, such as in a systems engi-
neering department. The more important of these
*A typical team might include one chemical engineer
with operating experience and another from the process
engineering or research department, an electrical engineer
with experience in digital equipment and instrumentation,
a systems engineer with training in process control tech-
niques, and a specialist in computer programming-al-
though all members of the team should acquire some skill
in programming.


qualities are: (1) His narrow scope of interest. The
PhD is too often interested only in that problem which
has constituted his thesis work. Such a characteristic
is to be expected, perhaps, since he has channeled his
effort along this path for years. (2) The PhD is
usually a researcher, not an applications engineer. That
this is generally the case can easily be surmised by
noting that the most important characteristic of a re-
searcher is his ability and desire to "channel" effort
on one subject. (3) The PhD demonstrates, in almost
every case, an attitude of academic aloofness. Needless
to say, such a characteristic is disastrous in an indus-
trial environment."
To this gloomy description, we might add an-
other long-standing and strongly-held observation
of our own: people with a research orientation
often have a difficult time working on a process
computer project because their training and ex-
perience cause them to concentrate on the un-
known rather than the known. Like the pessimis-
tic drinker, who views his glass as half empty,
not as half full, they tend to stress the gaps in
existing knowledge and always want to investi-
gate one more area or run one more experiment.
In short, they are unwilling to get on with the job
by using what is already known and looking for
ways to circumvent the real or imagined diffi-
culties.


TRAITS AND ATTITUDES

Production of engineers with the requisite aca-
demic background for process computer work
does not require drastic revision of the chemical
engineering curriculum. However, there are some
essential traits and attitudes necessary for this
work" which might be developed more fully in
the standard curriculum. Let's summarize the
characteristics that distinguish the process com-
puter systems engineer:
* He must be interested in results, that is, he must be
interested in having the process computer perform useful
functions. He must concentrate on the solution of prob-
lems with economic significance, not those which are
merely interesting.
sHe must be able to communicate with corporate man-
agement, members of the project team, and process op-
erators.
* He must be skilled in human relations. To design a
system used by operators to run the plant for manage-
ment, he must be diplomatic in guiding the project to a
successful conclusion which meets the needs of many
people.
* He must be patient and persistent. Process com-
puter projects often take many months and require solu-
tion of many problems in getting the computer hardware,
programs and instruments to work together as planned.


SUMMER 1971









* He must be creative and inventive. Because the field
is still new and packaged solutions are not available he
must be able to find his own answers to the multitude of
complex problems he faces in designing a system and
making it work.
To some extent, these traits and attitudes are
personality characteristics acquired in early child-
hood. Hopefully, they can be enhanced in the
course of an engineering education. If so, they
are perhaps best acquired as by-products of the
regular engineering courses, through such meas-
ures as discussions of the instructors' industrial
or consulting work; use of problems with a prac-
tical flavor; assignments that encourage creative
as opposed to strictly analytical activity; empha-
sis on oral and written communication; projects
requiring group efforts, including preparation of
plans and schedules; and so on.

DESIGN VS. OPERATION
Finally, the process computer systems engi-
neer-and those he works with in industry-must
have a viewpoint toward process operation which
may necessitate some adjustments on the part of
engineering educators. Operation of a process
plant with a computer requires that the plant and
its control equipment be considered as a system
in relation to its physical and economic environ-
ment. The traditional curriculum generally does
not adequately prepare a graduating engineer to
think in these terms.
An engineer must, of necessity, learn the fun-
damental principles of science and engineering.
Since there are many such principles, they are
taken one at a time, and the student practices
their use by solving appropriate problems. He be-
comes accustomed to solving simple problems re-
quiring use of only a few principles. When he
moves into more advanced courses in the practice
of the technology, he continues in the same pat-
tern.
At some point, the engineering student pro-
gresses from analysis to design. Now the result-
a product to be made at a specified rate from
given raw materials- is stated, and the problem
is to determine a suitable process configuration,
equipment sizes, materials, etc. If time permits,
attempts may be made to optimize the design.*

*Perry and Singer12 have recently published an inter-
esting paper illustrating how a computer can be used to
determine both equipment dimensions and operating con-
ditions to meet a production rate specification at minimum
cost.


Hopefully, measuring and regulating devices are
selected simultaneously with design of the basic
processing equipment, rather than added as an
afterthought, but we don't want to go deeply into
this old problem in this paper! In any case, when
all of the equipment is specified, the problem is
regarded as solved
In real life, of course, the engineer's job is
not finished when the plant is designed and con-
structed; it must still be operated. Now the prob-
lem changes. The equipment layout and dimen-
sions are fixed (barring breakdowns and expan-
sions), but the raw materials, ambient conditions,
equipment performance, and market requirements
change. Unfortunately, we cannot put plants in a
controlled environment (like Houston's Astro-
dome), supply them with USP-grade raw mater-
ials, and turn out a fixed slate of products for
delivery at arbitrary prices to easy-to-please cus-
tomers. People remote from the plants-which
means process industry management, plant de-
signers, and engineering educators-seem prone
to forget these day-to-day operating problems.
These operating problems are, however, the
basic justification for use of a process computer.
This device is a tool for improving process per-
formance by near-continuous adjustment of op-
erating conditions to satisfy a pre-established cri-
terion. With a process computer, the objective is
not simply to hold everything constant but to re-
act in the best possible way to the inevitable pro-
cess disturbances.4 The goal can be as general as
maximum profit or as specific as producing at a
prescribed rate with minimum variations in pro-
duct quality. Defining the goals) is a task re-
quiring management participation, and developing
a system to meet the goals is the job of a team of
process computed systems engineers. For success,
all parties must have a realistic understanding
of process disturbances, objectives, limitations,
and permissible operating practices.

CONCLUSIONS
Process computers are here to stay, and engi-
neering schools need to adapt themselves to this
fact. Fortunately, since educators already have
too many subjects to teach and too few credit
hours for teaching them, the necessary adapta-
tion is primarily a change in approach rather
than a fundamental revision of curriculum.

Engineering schools now make available the subjects
(Table I) which provide the needed background for work


CHEMICAL ENGINEERING EDUCATION









with process computers. If any deficiencies exist, they
are found in the area of training in management skills,
useful not only for process computer work but for all
engineering activities. No student can cover all of the
worthwhile subjects, even with graduate study; for this
reason, and because many students will find themselves
in other new fields in the future, the need for life-long
learning must be stressed.
Training through the PhD level is not the only or
best way to produce people with the requisite skills. It
is an unnecessary hurdle for the individuals, and the
total demand would make an excessive load for the uni-
versities. More important, the usual emphasis in a PhD
program on research in a narrowly-defined specialty does
not provide the right technical background and mental
outlook for process computer systems engineers.
Above all, we hope the engineering schools will pro-
duce engineers-men who combine a knowledge of scien-
tific principles with an interest in practical results, an
appreciation of cost factors, and skill in human rela-
tions. Among their other attributes, they should be able
to communicate, patient and persistent, creative and in-
ventive. These traits and attitudes need not be taught in
special courses but should be imparted throughout the
curriculum.
Engineering students also need to learn that, contrary
to much literature on the question, design is not the ulti-
mate goal of engineering; an engineer has to make things
work. In the process industries, he must run plants and
solve what might be called the operating problem: with a
given plant facing varying raw materials, product require-
ments and equipment characteristics, what is the best
way to operate? This responsibility does not receive
sufficient recognition in engineering education.
The process computer is a tool for attacking the oper-
ating problem. Solving the problem (with or without an
on-line computer) calls for skills in process simulation,
optimization, instrumentation, process economics, and in-
dustrial management. Successful installation of a process
computer is an engineering achievement of the highest
order.

REFERENCES
1. Final Report of the Goals Committee, J. of Eng. Ed.,
58, January, 1968, pp. 367-446.
2. W. C. White, Definition of Engineering, Ibid, 50,
June, 1960, pp. 892-893.
3. 0. A. Hougen, Progress and Responsibilities in Chem-
ical Engineering Education, The Trend in Engineer-
ing (University of Washington, Seattle, Wash.), 19,
April, 1967, pp. 2-7, 32.
4. E. F. Johnson, Control Systems Engineering-The
Challenge, Chem. Eng. Prog., 54, March, 1958, pp.
41-45.
5. G. E. Russell, Organization for Systems Engineering
in the Chemical Industry, Paper No. PCW-6-58-1,
ISA Annual Conference, September, 1958.
6. D. P. Eckman, Engineering Education in Computer
Control, Paper No. 15-H60, ISA Winter Conference,
1960.
7. J. 0. Hougen, Process Understanding Required for
Systems Engineering, Tappi, 43, April, 1960, pp.
180A-183A.


8. J. 0. Hougen, Process Dynamics-Accomplishments
and Prospects, 12th Institute Lecture, AIChE, Wash-
ington, D.C., December 5, 1960.
9. T. C. Wherry, Chemical Process Systems Engi-
neering, Chem Eng., 67, December 12, 1960, pp.
153-160.
10. J. Mardon and W. C. Cripps, New Problem-Training
Systems Engineers, Pulp & Paper, 42, April 15, 1968,
pp. 30-33.
11. A. D. Hall, A Methodology for Systems Engineering,
D. Van Nostrand, 1962, pp. 16-17.
12. R. H. Perry and E. Singer, Practical Guidelines for
Process Optimization, Chem. Eng. 75, February 26,
1968, pp. 163-168.
13. J. R. Pierce, What Are We Doing to Engineering?,
Science, 149, 23 July 1965, pp. 397-399.
14. H. Brooks, Dilemmas of Engineering Education,
IEEE Spectrum, 4, February, 1967, pp. 89-91.
15. D. V. De Simone, Education for Innovation, Ibid, 5,
January, 1968, pp. 83-89.
16. A. D. Moore, The Modern Engineering Bandwagon,
Ibid, July, 1968, pp. 79-82.
17. T. von Karman, The Wind and Beyond, Little, Brown
and Company, Boston, 1967.



ENVIRONMENTAL STUDIES: KROESSER
(Continued from p. 115)

through this interaction in areas we cannot cover
ourselves. The experience can be a tremendous
asset to a young Chemical Engineer, and therefore
can be a valuable part of his technical education.
Finally, there is a lot of work to be done here,
for our local community, for the nation and for
the world. In the past, too many times we have
said, "Well, I'd like to help, but that is really a
political or social problem." The political and social
scientists are at the same time calling it a problem
in technology. Here is the kind of group where
you find out what kind of problem it is and then
solve it. This means utilizing our talents for
solving some of our most important problems.

REFERENCES

1. U.S. Congress, House Subcommittee on Science, Re-
search and Development, "Environmental Science
Centers at Institutions of Higher Learning." Report
91st Cong., 1st session, Washington, D.C. 1969.
2. Scientists' Institute for Public Information, 30 East
68th Street, New York, N.Y. 10021.
3. "The Environmental Quality of the Mystic River
Basin," Vol. I: December, 1970; Vol. II: May 1971. A
series of reports available through the Experimen-
tal College, Tufts University, Medford, Mass. 02155.
4. The Mystic River Watershed Association, c/o the
Experimental College, Tufts University, Medford,
Mass. 02155,


SUMMER 1971









M H PJclassroom


4 Se4-Paced ea.u.


MASS TRANSFER OPERATIONS


WILLIAM L. CONGER
University of Kentucky
Lexington, Kentucky

It has always bothered me that my lectures
do not seem to reach all of the students in my
classes. The students, who we say are very in-
telligent, are often bored because we move too
slowly. The students who we say are dull, are
often so far behind that they have no hope of
passing the course. Those students in the middle
get the most benefit. I have often thought that
there should be some way of challenging those
"intelligent" students, keeping their interest, and
motivating them to do more, while still handling
the problems of the middle of the class and saving
those of the "dull" group that were worth saving.
I have tried various methods such as extra as-
signments, reports, etc. with very limited success.

A POSSIBLE SOLUTION
I was assigned by my dean as a young faculty
delegate to the national meeting of the ASEE in
June of 1970. This was a very profitable meeting
for me, as I was exposed to a number of teaching
techniques of which I had not known before. One
of these the Self-Paced Course or as Keller1'2 calls
it, the Personalized System of Instruction (PSI),
appeared that it might answer some of my criti-
cisms on the lecture system.
Dr. F. S. Keller has developed the PSI method
in order to obtain the most of every student's po-
tential. In its unmodified form it includes the
following features:
(1) Go at your own pace. The student moves through
the course at a speed commensurate with his
ability and other demands upon his time.
(2) A unit-perfection requirement for advancement.
The student is allowed to proceed to new material
only after demonstrating that he has a mastery
over all proceeding material.
(3) The use of lectures and demonstrations as moti-
vation devices. The student is allowed to attend
special lectures only after achieving a specified
level in the course.
(4) Stress upon the written word for communication
between student and teacher.


(5) The use of proctors. The student is assigned to a
proctor who tests, scores, and tutors on an im-
mediate one to one basis.
In my case I had to modify Keller's ideal some-
what to eliminate (5), as I did not have the per-
sonnel nor the funds to provide a sufficient num-
ber of procters to run the course exactly as Keller
suggests. I decided that elimination of (5) was
possible, because Chemical Engineering classes at
the University of Kentucky generally contain
under thirty persons (Keller's classes were in
excess of one hundred students) and, therefore,
I could assume those tasks assigned to the proc-
tors in the system.
Of the remaining four points, (1) and (2)
interested me the most. The system would accom-
modate the quick and the slow student (often
confused with intelligence and dullness) and in
addition would have equal reward for everyone
for completing the same amount of material.
I decided to test the system as Dr. Billy Koen3
(University of Texas, Mechanical Engineering)
and Dr. G. David Shelling4 (University of Rhode
Island, Chemical Engineering) did with material
given me by Dr. Koen and by Dr. Clyde H.
Sprague of the Department of Mechanical Engi-
neering, Kansas State University as a model, I
developed a self-paced course in mass transfer
based on the text Mass Transfer Operations.5

DEVELOPING THE COURSE
The first step in building the course was to
determine exactly what material I wanted to
cover in the course. I decided to cover the first ten
chapters in the book with the exception of chapter
7 "Humidification Operations." I then broke this
material down into twenty five individual assign-
ments or tasks. The student must complete a
task satisfactorily before proceeding to the next
one.
The second step was to find and correlate other
references on the same block material so that the
student would have several authors to read if he
had difficulty understanding his primary text.
This was then presented to the students in twenty
five separate assignment sheets or blocks each


CHEMICAL ENGINEERING EDUCATION
















... the system would - %1
accommodate the quick
and the slow student...







William L. Conger is a graduate of the University of
Louisville and the University of Pennsylvania (PhD '65).
He has been teaching at the University of Kentucky since
January 1967 and has developed an interest in teaching
techniques. His research interests are in the biomedical
area.

giving an objective for the block, a reading as-
signment in the text, additional readings in other
references, and problems to do with answers.
The third step was writing supplemental ma-
terial of my own design to further reinforce the
text material. In this supplement I spelled out the
rules of the course, noted sections of the reading
material that were of particular importance, and
amplified sections of the text. A portion of this
supplemental material explaining the course to
the students is given below:

We are about to enter into a new type of learning
process for most of you. This method that we will be
using in this class is called "Self Paced Instruction." The
method was developed by a Education Psychologist by the
name of Keller; the method is designed so that everyone in
the course will learn the maximum amount.
I have taken the material in Mass-Transfer Operations,
Treybal, R. E., 2nd edition, McGraw-Hill (1968) and have
divided a portion of it into block tasks. You will be given
these blocks one at a time. You must finish the block
given you before getting the next one in the sequence.
Anyone finishing all the blocks will receive an "A" in
the course, all but one block , "B", all but 2 blocks a "C".
Anyone completing less than all minus 2 will be given an
incomplete in the course. An incomplete must be removed
from my books by the third week of the next semester. The
deal of A, B, or C will still apply. Any incomplete not
removed from my books will be given an E.
Everyone can get an "A," then what is this incentive
to study and what rules apply
Rule 1 You must complete each block by answering
with near 100% accuracy a very short assessment quiz.
Don't memorize the material- learn it, for each subse-
quent block will depend on the previous blocks. Also I
* Examples of the tasks, quizes and supplementary
material are available from the author.


~P�~,


SUMMER 1971


reserve the right to ask you a question on any previous
block in an assessment quiz. If you fail to get 100% on
the quiz, I will ask you a question or two orally to see
if you just didn't understand my question. If I determine
that it was my question, and you really know the material,
I will pass you to the next block. If you miss too many
questions on the assessment quiz, I won't use the oral
exam.
Rule 2 You may take the assessment quiz, as many
times as you need to get 100%. A new quiz will be used
each time.
Rule 3 You may not take more than 2 assessment
quizzes on any one day, and at least one hour must elapse
between starting quizzes.
Rule 4 Quizzes will be administered at noon and at
normal class time on Monday, Wednesday, and Friday.
Quizzes will be administered at noon and an hour of the
students selection on Tuesday and Thursday. No quizzes
will be given on Saturday, Sunday or Holidays. If there
is a conflict on the normal M.W.F. schedule so that a
student can't use the noon hour for quizzes, exception
to the above rule will be made.
Rule 5 All assessment quizzes will be closed book.
Rule 6 The classroom and hour assigned to this class
will be used for studying the material. You are to study
outside class also, but I expect you to show up and use
the time and space allotted.
Rule 7 Once you have finished all blocks satisfactorily
you receive your "A" and you are finished with the course.
I don't care if you finish in 6 weeks as long as you finish.
Once finished you don't have to attend class anymore.
What is all of this worth to you? Well, if you finish the
course, you get an "A," and you should have an excellent
grasp of the material. Studies have shown that students
using this method learn more-more quickly and retain
the material better.
This method does this for you also: no longer are you
competing with your fellow student-you are competing
with the material only.
Now some study hints:
1. When you get a new block, look over the instruction
sheets I give you thoroughly. Then skim the re-
quired reading just looking at the topics to be
covered.
2. Next, go back over the reading and try to pick out
the important points. Now put the material down
and do something else for some time.
3. Go back to the reading and go over it once again,
hitting the high spots you have picked out.
4. Now go to the problems, if any, and work with
them until you can get the correct answers.
5. Study together-teach each other. The best way
to learn something is to try to explain it to some-
one else. If you can make another person understand
a particular principle, then you will know it.
6. Now we get down to my function besides organizing
this, writing the supplemental material, etc. If you
go through step 5 and still have questions, your
next recourse is me. Ask me the questions; make
me answer them. I will be available at class time
and at the times posted on my door. Your job is to
learn the material-my job is to clarify the ma-
terial if you have trouble.








The students were overwhelmingly in favor of the
PSI method. They liked the continuous testing and
found it easy to pace themselves.

The fourth and last step was developing a
series of quizzes to test the students capabilities
with the material. The quizzes should not be
exactly the same so I developed up to eight sepa-
rate ones for some blocks down to only two for
one block. The average was about four quizzes per
block which covered the material from previous
blocks to test retention. The quizzes were gener-
ally short averaging 15 to 20 minutes to complete.
Several were longer, however, taking up to an
hour to complete.

RESPONSE TO THE COURSE

We have seen the reasons why I chose to teach
a course this way, and how I applied Keller's theo-
ries to the course materials. Now, what were the
results of my efforts. The assessment quiz for
the final block was a course evaluation modeled
somewhat after Koen's3 but modified to meet my
personal situation. The results of several selected
questions are given below. I was happy to find
basically the same responses as Dr. Koen found.
I had 21 students taking the course. All but one
completed the course in the normal semester;
that one has completed all but two blocks at this
writing and should complete these shortly.
No. of responses
Def. Def.
Yes Yes No No


Questions
The quiz material was designed to
make the block material more
meaningful to me.
This course caused me to work
beyond the normal effort I put
into a course
I felt that there should be some lecture
associated with the course
I was able to get help from other
students in the class when I
had a question
I understood what was expected of me
in the course.
I missed the usual grading system
and tests.
I would like to see more classes
taught this way
I was frustrated to have to pace
myself.


13


7 0 0


The supplemental reading material
was helpful.
The material I covered has caused
me to think.


3 10 6 1

16 4 0 0


I think I learned a substantial fraction
of the material in the book 17 3 0 0
The quizzes were general enough to
cause me to study all the
material. 10 8 2 0
I could find out what to study from
the people who had already been
through a block. 0 11 9 0
I did not study all the material in
every block because I could find
what was going to be on the
quiz. 0 1 15 4


I found it difficult to pace myself. 1
I was hurried to complete the course. 1
Is this approach worth continuing in
this class in the future? 18
Should there be regular lectures, say
once a week on Friday, to cover
related material to the course? 3


Questions


This course was


4 8 7
1 12 6

2 0 0


8 8 1

No. of
Responses


of the courses I have taken.


a) the best
b) one of the best
c) above average quality
d) average or lower
Among the courses I have had this course was
--..------ for stimulating me to new ideas.
a) the best
b) one of the best
c) above average
d) average or lower
I consider this self-paced instruction to be:


9 8 2 1 a) better than the lecture method 19
b) as good as the lecture method 1
0 7 10 3 c) inferior to the lecture method 0
d) a detriment to the student learning. 0

As we can see the students were overwhelm-
4 13 3 0 ingly in favor of the PSI method, and the results
that it gave. They liked the continuous testing
12 8 0 0 even though they spent several more hours in
testing than they would normally. The self-paced
0 0 5 15 feature did not frustrate their efforts (I had two
students drop the course: one because of personal
17 3 0 0 problems, another because he did not pace himself
correctly), and most found it easy to pace them-
0 2 10 8 selves. In general they did not miss the lecture


CHEMICAL ENGINEERING EDUCATION









but indicated that they would like a few through-
out the semester. Most important to me, they
knew what was expected of them, and showed a
strong desire to have this method continued.
It appears from this data and in independent
course evaluation conducted by the Student Coun-
cil in the College of Engineering that the students
did like the course and how the material was pre-
sented. The students think that they have a better
grasp of more material than previous classes, but
is this true? A comparison of grade distribution
with previous classes is not a fair measure, since I
promised an A to everyone who met all the course
requirements. How then can I compare the level
of understanding of these students with previous
classes ?
The comparison I needed was made unwillingly
by the students themselves. The present seniors
had taken the same course the previous year
under one of our faculty who is consistently rated
by the students as one of the best teachers in our
department. I found many cases where the seniors
had gone to my juniors to have a principle or
problem explained to them. The seniors have cate-
gorically stated that my class has a far better
understanding of the material covered than they
have. I might note here that we covered more
material than previous years. I therefore feel that
the course accomplished its objective of conveying
a certain level of understanding of an engineering
subject to all the students in a class (fast, aver-
age, or slow learners).

ANALYSIS OF RESPONSES
I have asked myself, was the improvement I
saw a result of the course structure or a result of
just changing format? If I had used any other
format modifying the normal lecture, would I get
similar results? Is this a Hawthorne effect where
any change produces an increase in productivity?
I don't think so. I believe that this method can
answer many of the problems that we have in con-
veying information to our students. I do not,
however, believe that this is the only method that
should be employed. I think that a variety of
teaching methods will help the students generate
the motivation that is so often missing.

EFFECT ON INSTRUCTOR
One final note on how all this effects the in-
structor of a course. The amount of work neces-
sary in order to prepare a course like this far


surpasses what is normally necessary. But once
organized, the course can be used again and again
with minor modifications. The overall economy of
time would then approach conventional courses.
The instructor can feel somewhat left out at
times in using this method. Lecturing makes
many of us feel secure; the absence of the regular
lecture eliminates this secure feeling. The instruc-
tor does have more personal contact with each in-
dividual however, and this allows us to bring out
the student's capabilities.
The method lends more flexibility to the in-
structor. I had a student who had to serve in the
armed forces for three months during the sum-
mer. Unfortunately for him his tour of duty lasted
into the first of our semester, and the University
would not let him register. If he had been allowed
into normal courses, he would have been far be-
hind and would not have derived the full benefit of
the course. In addition the course in question here
is a prerequisite for a number of courses, and he
would have had at least one full year added to
the time for graduation had he not had to serve.
I am able to give this student this course (because
of its structure) so that he will be able to take the
following courses. He will register for independent
study next semester and get credit for his work.
This will allow this young man to graduate as he
had planned.

CONCLUSIONS
I have found the PSI method developed by
Keller a powerful tool in teaching Chemical Engi-
neering subject material, and I intend to continue
using the method in the future. Because of the
reinforcement technique used in the method, there
is every reason to believe the students' retention
of the material will be excellent. Students agreed
that they generally worked harder and enjoyed
this course more than most.

REFERENCES
1. Keller, F. S., "Good-Bye Teacher" J. Appl. Behavior
Anal., 1, 79 (1968).
2. Keller, F. S., "PSI, A personalized System of In-
struction," Presented 1968, Institute for Behavioral
Research, Silver Springs, Maryland.
3. Koen, B. V., "Self-Paced Instruction In Engineering:
A Case Study," Presented at the Annual Meeting
of ASEE, June 22-25, 1970.
4. Shilling, G. D., "A Self-Pacing, Auto-Graded Course,"
Chem. Eng. Educ., 3, 130 (1969).
5. Treybal, R. E., Mass-Transfer Operations, McGraw
Hill (1968).


SUMMER 1971










IK laboratory


This work was originally presented at the Third Joint
Meeting AIChE-IMIQ, Denver, August 1970.


AUDIO-MODULE EXPERIMENTS


G. E. KLINZING
University of Pittsburgh
Pittsburgh, Pennsylvania 15213

I N THE TEACHING of undergraduate chemical
engineering laboratories innovated thinking
into the modernization of equipment and opera-
tion is essential to stimulate the interest of the
student and faculty alike. In this search for im-
provement, care must be taken not to overstruc-
ture the system which may stymie the creativity
of the student or to understructure the system
which may entirely frustrate the student. In an
effort to achieve the above mentioned objective
one suggested course of action would be to com-
pile a laboratory manual to guide the student in
the laboratory experimentation. Proceeding along
these lines one may be met with only mediocre
success for a number of reasons. One of these
reasons for moderate success is that students sel-
dom read the manual before attending class, and
on many occasions the manual is not even brought
to class to consult during the laboratory period.
The reason for this may be the student's laziness
to read because of the requirement of concentra-
tion.
To overcome this dilemma the audio-module
experiments were developed based on the premise
that it is easier to listen than to read.
The audio-module experiment is a three-sided
enclosed booth having all the necessary equip-
ment, services and reagents for enacting the ex-
periment. The unique feature in the module is the
tape recorder with instructions, trouble shooting,
and suggested analysis for the experiment. The
tape recorders are of the cassette type which fa-
cilitates usage.
Three audio-module experiments have been
constructed and employed. These experiments are
in the areas of diffusion, calibration and fermen-
tation reaction. Photographs 1 to 3 show the de-
tails of these experiments.
These units have now been in operation for
a half of a year with favorable student reaction.
Often this is the first time students come in con-
tact with chemical engineering equipment and
experimentation and the audio description helps


Fig. 1. Audio Module of Diffusion Experiment.


significantly. The students felt that a considerable
amount of time was saved in familiarizing them-
selves with the equipment by use of the module.
Ideal usage of the modules is now being employed
in the first courses in chemical engineering where
the unit on calibration of instruments is of special
utility. The cassette tape permits repeating the
tape contents with ease to clarify a particular
point when necessary. The concern that the tape
does nothing more than repeat the operational
procedure of the laboratory manual did not matter
to the students but seemed to serve as a reinforce-
ment to the manual. By using the human voice via
the tapes emphasis can be placed on critical points
by intonation patterns of the voice and a more
personal touch can be given to rather mundane
business of procedure and description.


S~~C.-7

i I,


Fig. 2. Audio Module of Calibration Experiment.


CHEMICAL ENGINEERING EDUCATION








... it is easier to listen than to read.


F UTURE WORK ALONG these lines is planned.
An audio-module unit on the aspects of report
writing is being constructed. This unit will be
located on a desk top enclosed on three sides with
its own tape recorder and containing samples of
previously written and corrected reports. This
will serve as a guide to the students in preparing
their final laboratory reports.
The coupling of the visual to the audio section
of module is also being developed. The visual part
will consist of a 21" x 21" screen box containing
a Kodak Carousel projector whose slides will be
synchronized with the tape recorder in a compact
arrangement. The added visual media offers a
more complete educational tool. More complex


44


Fig. 3. Audio Module of Batch Reactor.


operating procedures can be covered by the audio-
visual module. Several of these units can be placed
on carts and wheeled to the appropriate experi-
ment using the designate cassette tape and slide
tray of that experiment. Photographs 4 and 5
show the audio-visual module.
By compiling these audio and audio-visual
modules one will find that his experiments will
become even more organized and efficient than
they were in the past. Utilizing these units makes
one consolidate the equipment and anticipate the
needs of the student for successful completion of
the experiment.
The overall usage of the modules presents an
exciting aspect in scheduling of student labora-
tories. At present most laboratories are scheduled
aa particular times in a fixed block of time. Ulti-
mately the laboratory by use of the modules would
be accessible to the student any time he desired
to perform the work. A technician would need to


Fig. 4. Audio-Visual Module.


be present to take care of difficulties that may
arise but in general these laboratories would be
self-operating and give considerable flexibility to
the present scheduling system.
Projecting even further, a closed circuit TV
camera could be operated between the laboratory
and the professor's office, and its usage could be
employed when difficult problems would arise.
During the summer of 1970 the tapes for the
audio experiments were translated into Spanish
with the help of colleagues at Universidad Tecnica
Federico Santa Maria in Valparaiso, Chile. Some
interest in employing these modules has been ex-
pressed by a few professors of chemical engineer-
ing at Latin American universities.
These modules thus present an efficient manner
of laboratory operation at a relatively low invest-
ment cost.


Fig. 5. Projection Screen.


SUMMER 1971










NON-NEWTONIAN PIPELINE FLOW


P. J. F. KANITZ* and J. D. FORD
University of Waterloo,
Waterloo, Ontario, Canada

Processing of non-Newtonian fluids is com-
monly encountered in engineering operations. In
this pipeline flow experiment, the student is ex-
posed to some of the problems involved in hand-
ling these liquids, and in addition, is able to accu-
rately determine the flow behaviour index and
consistency for a typical pseudoplastic fluid.

EXPERIMENTAL DETAILS
The apparatus, as shown schematically in
Figure 1, was developed for use in the third year
Unit Operations Laboratory at the University of
Waterloo. The solution to be studied is stored in a
200 litre holding tank equipped with sight glass,
pressure gauge, and necessary pipe connections
including high pressure air (125 psig) and vacuum
lines. Under air pressure, the solution can be
forced through one of three heavy wall acrylic
tubes containing 12.02 in. test sections for press-
ure drop measurements. The tube inside diameters
are 0.1273, 0.1926 and 0.3725 in., respectively, and
the overall length 59.1 in. After passing through
the selected tube, the solution is discharged into
a weighing tank and can then be returned to the
holding tank under vacuum. A detailed description
of the apparatus is available.5
The pressure taps on the test sections were
carefully constructed to avoid burrs or ridges


*Seneca College
Willowdale, Ontario,


of Applied Arts and Technology
Canada.


Fig. 1.-Apparatus. 1. High Pressure Air Line; 2. Vacuum Line; 3. Hold-
ing Tank with Sight Glass; 4. Test Sections; 5. Manometer Manifold;
6. Manometer; 7. Thermometer; 8. Balance; 9. Return Line.


from the upstream and downstream taps were
connected through valves and common manifolds
to a series of three manometers. The manometers
containing mercury, tetrabromoethane and carbon
tetrachloride, respectively, complemented each
other over a wide range making possible the study
of a large number of different solutions and con-
centrations.
An aqueous solution containing 1.25 wt% car-
boxymethylcellulose is suitable for the laboratory
work. To perform an experimental run, it is neces-
sary to pressurize the holding tank, select the tube
with the desired diameter, and determine the
manometer with the proper range. A wide range of
flow rates can be obtained by varying the air
pressure in the holding tank. Required readings
consist of the manometer levels, the mass flow
rate (determined by weighing the discharge per
unit time), and the temperature of the solution.


0.8 r


o -0.1273"
A. 0.1926"
a -0.3725"


0.2H


0.0 , I , , , , , I
2.5 3.0 3.5 4.0


FIG. 2.-Flow curve for 1.25% CMC solution at 250C.

RESULTS AND DISCUSSION
A typical set of results' is shown in Figure 2.
This represents experimental work carried out in
one afternoon. A log-log plot of the experimental
data in the form DAP/4L vs. 8V/D is prepared,
following the analysis of Metzner and Reed.2 Flow
conditions are, of course, adjusted to ensure opera-
tion in the laminar region. There is a slight scatter


CHEMICAL ENGINEERING EDUCATION
























Peter J. Kanitz received his BASc in Chemical Engi-
neering from the University of Toronto ('63). Then, he
joined Union Carbide Canada Limited to work in various
areas including New Product Development, Technical
Service and Customer Service. He returned to Graduate
School at the University of Waterloo to study the trans-
port of gases through modified polymer films receiving
an MASc (67) and the PhD ('70). He is currently on the
Engineering Technology Faculty at Seneca College of Ap-
plied Arts and Technology, Toronto, Canada. (left)
James D. Ford is an Associate Professor in ChE at
University of Waterloo. He received the BEng degree
from McGill and the MASc -and PhD (67) degrees from
Toronto. His research interests include heat transfer and
reactions at high temperature. (right)


in the data, but one can conclude that the flow
behaviour index (n') for this solution is constant,
and obtain a least squares fit. The slope (n') is
0.500. K', the consistency, is then obtained from:

DAP , 8V ri n' (1)
4L ~k D
The value of K' is 0.055 Ibf-sec'/ft2. These re-
sults are for a 1.25% solution of Type 7H3S CMC
in water, at 25�C. These values compare favour-
ably with those reported in the literature.
When transferred to the Fanning friction fac-
tor-generalized Reynolds number plot, Figure 3,
these results can be expressed in terms of the
normal relationship:

DAP/4L 16 16(8)'-1 K'g
(PV2/2gc) NRe,gen Dn'V2-n' (2)
where the generalized Reynolds number and fric-
tion factors are as defined by Metzner and Reed.2
In summary, this experiment exposes the stu-
dent to common problems encountered in handling
polymeric solutions, such as degradation, mixing,
pumping, etc. By incorporation of simple experi-
mental measurements, fundamental fluid proper-
ties are obtained, permitting an insight into the


0 - 0.1273"
A - 0.1926"
0- 0.3725"


.... .........


101 102 103
NRe,gen.

FIG. 3.-Fanning friction factor-Reynolds number correlation for 1.25%
CMC solution.

behaviour of such systems in terms useful in en-
gineering design. As a further development, one
could introduce smaller pipe diameters, to illus-
trate the "diameter effect"-see for example Ko-
zicki et al.3

ACKNOWLEDGEMENT

P. J. Catania4 built and tested the first apparatus, and
V. Arunachalam5 modified and debugged the final version.
Their help is gratefully acknowledged.

NOMENCLATURE
D-inner diameter of tube, ft.
L-tube length between pressure taps, ft.
AP-pressure drop over length L, lbf/ft2
V-bulk velocity of fluid, ft/sec.
K'-consistency, lbf-secn'/ft2
n'-flow behaviour index
Ne.,ge,,-generalized Reynold's number

REFERENCES

1. Data taken by Steenburg, W. (Group Leader), T.
Francis and M. Pyatt, Department of Chemical En-
gineering, University of Waterloo (March, 1970).
2. Metzner, A. B. and J. C. Reed, AIChE. J., 1, 434
(1955).
3. Kozicki, W., S. N. Pasari, A. R. K. Rao and C. Tiu,
Chem. Eng. Sci., 25, 41 (1970).
4. Catania, P. J., "Flow Behaviour of non-Newtonian
Liquids," B.A.Sc. Project, Department of Chemical
Engineering, University of Waterloo (April, 1967).
5. Arunachalam, V., "Studies on the Reduction of Fric-
tion Losses in Turbulent Pipe Flow by Means of
Active Additives," Ph.D. Thesis, University of Water-
loo (1970).


SUMMER 1971


I I










DIFFUSION AND REACTION IN CATALYST PELLETS


JAMES B. ANDERSON*
Princeton University
Princeton, N. J.

The coupling of chemical reaction with mass
transport by diffusion provides some of the most
difficult problems in reactor design. Because of
this the interaction of diffusion and reaction pro-
cesses is given extensive treatment in most chemi-
cal engineering reactor textbooks. For diffusion
and reaction within catalyst pellets the theory is
sufficiently developed to allow computation of
coupling effects for systems with known intrinsic
kinetic behavior. This experiment was developed
in order to provide students with first hand ex-
perience with intraparticle diffusion effects on re-
action rates.
In the Thermofor catalytic cracking (TCC)
process oil feed stocks are cracked in a reactor
containing porous silica-alumina catalyst pellets
in the form of beads which become contaminated
by a carbonaceous material. Beads are circulated
to a regeneration chamber for removal of the car-
bonaceous material by oxidation with air. A com-
plete description of the process has been given by
a group at Mobil Oil Company.1 The coupling of
diffusion and reaction rates in the oxidation of
the carbonaceous deposits is examined in this ex-
periment.
As in the investigations by Weisz and Good-
win,2 oxidation of the carbonaceous deposits is
carried out in small furnaces at several tempera-
tures. Sample pellets are removed at intervals
during the course of reaction. For oxidation at less
than 850�F the process is reaction-rate limited
and the carbon concentration decreases uniformly
within the bead. The bead, initially black through-
out, becomes lighter in color passing through gray
and eventually becomes nearly clear. At tempera-
tures above 1000�F the process is limited by the
diffusion of oxygen into the pellet and carbon re-
moval takes place in a shell-progressive manner.
The spherical carbon-containing region shrinks
in the course of reaction and disappears. Since a
partially oxidized pellet has the appearance of a
fish's eye, high temperature oxidation has been re-

*Present Address: Department of Engineering and
Applied Science, Yale University, New Haven, Conn. 06520.


Ce xdcal Ieacht .2aao tawii


aJb


J. B. ANDERSON is an associate professor of chemi-
cal engineering in the Department of Engineering and
App ied Science at Yale University. He received his BS
f'om Pennsylvania State University, MS from the Uni-
versity of Illinois and PhD from Princeton University.
Professor Anderson taught at Princeton for four years
before joining Yale in 1968. His research interests are in
the fields of chemical kinetics and chemical reaction
engineering.

ferred to as "fish-eye burning." At intermediate
temperatures the reaction is partially rate-limited
and partially diffusion-limited. Oxidation in this
regime produces a diffuse boundary for the
carbon-containing region.
Since the carbon-free regions of the beads are
nearly clear the qualitative characteristics of
operation in the three regimes are immediately
observable. For quantitative analysis the beads
are ground on a lapping wheel to obtain flat center
sections. Measurements of the size of carbon-con-
taining regious are made with a cathetometer. If
sufficient time is available measurements of the
carbon density profiles for beads oxidized at inter-
mediate temperatures can be made with an optical
densitometer. Quantitative comparison of results
with theoretical predictions is made only for beads
oxidized in the diffusion limited regime.

THEORETICAL BACKGROUND
The reaction may be represented as
nC +02 - 2 (n - 1) CO + (2 - n) C02
where n is the number of atoms of carbon re-


CHEMICAL ENGINEERING EDUCATION









moved per molecule of oxygen consumed. The re-
action rate is assumed to be first order in carbon
concentration and in oxygen concentration. Oxy-
gen and the reaction products are assumed to
undergo equimolar counter diffusion with constant
effective diffusivities. Pellet temperature is taken
as constant.
For a spherical pellet of radius Ro, the con-
tinuity equations for carbon and oxygen are as
follows:
ac
t - kn C C (1)

C C 2Cox a ox (2)
=-k Cc Cox + D Cx +2
Sr
with boundary conditions
at t = 0, 0 < r < Ro, Cc = CcO, Cox

t > , r = Ro, Co C
Sox x
rc

where
C, = carbon concentration per unit volume
Co- = oxygen concentration per unit volume of gas
E = void fraction within pellet
D = effective diffusivity of oxygen
k = intrinsic rate constant
r = radial distance
t = time
R. = pellet radius
CO = initial carbon concentration
C00O = oxygen concentration at pellet surface

The equations may be made dimensionless by the
following substitutions:
C 0
C ' -= -- c , _ -0 r -
c c � ox - c o 5
c Cox 0

/kn C�
ROV - D--2 t kn Co�, c . -
ox E
The resulting dimensionless equations are:
ac '
at' c Cox (3)
c / + , 2 a ox, ,
at - Cc' Cox 2 .' r,2 r' tr (4)

t'=O, 0 < r' i, Cc' = i Co, = 0

t' > 0, r = , c ' -= ,

Cox 0.
t' >0, r' =0, o x 0.


The solution for this set of equations will de-
pend only on two parameters: the ratio of carbon
and oxygen concentrations as give by i and the
Thiele modulus 4. Since q is not varied significant-
ly in the experiments the regime of operation de-
pends on the Thiele modulus alone. For large


values of ) the reaction is diffusion limited while
at small values of 0 the reaction is rate limited.
The equations may be simplified for extreme
values of 0. In the intermediate regime, solution
of the equations as written is necessary. Numeri-
cal integration may be used but requires a rela-
tively large amount of computing time (typically
20 minutes on an IBM 7094 for a single integra-
tion). A perturbation technique shows some
promise in obtaining approximate solutions.
Weisz and Goodwin2 have given solutions for
both the rate-limited and diffusion-limited re-
gimes. When the reaction is rate limited, the oxy-
gen concentration may be assumed uniform
throughout the bead and equal to the external
oxygen concentration. Equation (1) may then be
integrated to give

Cc = Cc exp (- kn Cox t). (5)

For the diffusion-limited regime, Weisz and
Goodwin relate the rate of carbon removal (and
the change in radius of the carbon-containing
sphere) to the rate of diffusion of oxygen into
the pellet. A steady-state assumption is made in
order to simplify determination of the oxygen
diffusion rate. The resulting equations give the
fraction carbon remaining y as a function of
burning time where
(I y2/3) 1 nC 0
2 - - ( - y) Kt, Where K = -- (6)
R0 C
The fraction carbon remaining is related directly
to the radius Rb of the carbon-containing region
by

y - Ro (7)


MATERIALS AND APPARATUS

The silica-alumina catalyst beads used contain ap-
proximately one per cent by weight carbonaceous material.
These were obtained as a sample from a commercial TCC
unit. Typical pellet characteristics are as follows:


Material:
Diameter:
Carbon
concentration:
Density:
Pore volume:
Thermal
conductivity:
Effective
diffusivity
for 0,:


SiO,, A120,-10% wt., Cr0,,-0.15% wt.
0.4 to 0.5 cm

1.0% wt.
1.2 gm/cm3
0.4 cm2/gm

10-. cal/sec-cm-oC


2 x 10-3 cm2/sec (5000C)


The pellet regeneration apparatus is shown in the
photograph of Figure 1. When in operation the oven is


SUMMER 1971





















FIG. 1.-Apparatus for combustion of carbonaceous material in cata-
lyst pellets.

located within a fume hood. Auxiliary components are
located outside the hood.
Compressed air is supplied at about 50 psig to mani-
fold with outlets to four rotameters (full scale - 1.12
SCFM air). Pressure is reduced to about one atmosphere
and flow is controlled by �s-inch needle valves at the
manifold outlets. The air from each rotameter passes
to the oven through '/4-inch ID rubber tubing.
Details of the construction of the oven are shown in
Figure 2. The oven is made by stacking sections of Mari-
nite 15, an absestos material, drilled to provide four sepa-
rate chambers together with necessary gas inlet, elec-
trical lead and thermocouple ports. Each chamber is 1.5
inches ID and 13 inches high. The air supplied at the
bottom of each chamber passed upward across a 2000-watt
electrical heating coil (a heat gun replacement element),
through a stainless steel safety screen past a thermocouple
to stainless steel mesh baskets in which 10 to 20 pellets
are placed. The baskets are cylindrical, 1-%s inches in
diameter, 1/2 inch high. These are supported on wires about
5 inches from the tops of the chambers. A second thermo-
couple is inserted from the top and located immediately
above the basket in each chamber. Gas exhausts directly
from the open top of each chamber.
Power input to each oven heater is provided by a
7-V1-ampere variable transformer. Control of oven tem-
peratures is manual. A multipoint temperature recorder
is used to monitor all eight thermocouples.
For grinding sample pellets to expose cross-sections
through their centers a 10-inch diameter, felt-covered
lapping wheel is used with an alumina abrasive. Measure-
ments of the size of carbon containing regions of the
pellets are made with a cathetometer at 10x magnifica-
tion. For measurements of density profiles of the carbon-
aceous deposits several types of optical densitometers
have been used.

PROCEDURE

Several hours before the experiments are to be run
the ovens are preheated to 850, 900, 950 and 10000F with
an air flow of about 20 SCFM. Fifteen to twenty pellets,
selected for uniformity and spherical shape, are placed
in each basket. A nitrogen flow is substituted for the air
flow and the baskets are placed in the ovens and allowed
to approach thermal equilibrium. At time zero the
nitrogen flow is stopped and air flow begun.
At fifteen-minute intervals each basket is lifted from
its oven and two sample pellets are removed. The remain-


ing pellets are mixed to aid in uniform oxidation. The
combustion is continued for a period of 2 to 2� hours.
After practice with unburned pellets, students grind
the sample pellets on the lapping wheel to obtain flat
center sections. A wet alumina powder is used as the
abrasive. Pellets are held by hand. The pellets are then
placed in water in a shallow dish and measurements of
the diameter of the carbon-containing core (for fish-eye
burning) and pellet diameter are made. Qualitative ob-
servations of pellets burned under rate-controlled con-
ditions are made.
The grinding operation can be avoided with some
sacrifice in accuracy by making measurements of the
carbon core in whole pellets. The measuring errors due to
refraction of light are reduced by placing the pellets
under water for the measurements. If the pellets are
placed in water about 1 mm deep capillary action causes
the water to fill the pellet without trapping air in the
pores. The water level is then raised and measurements
are made with the cathetometer.
Measurements of carbon concentration with an op-
tical densitometer require at least a second three-hour
period. One half of each pellet is removed by grinding
and the remaining half is cemented to a glass microscope
slide with a drop of rosin placed on the heated slide. The
pellet is lapped further to obtain a thin center section.
It is rinsed, saturated with water and placed in the optical
densitometer. Blank measurements are made at the center
and edges of the pellet where either all or none of the
carbon remains. Light transmission is then measured as
a function of position within the pellet. The readings are
converted to fraction carbon remaining with the assump-
tion of Beer's law. The success of the measurements de-
pends almost entirely on obtaining a section as thin as
0.1 mm so that light transmission in the sample is
adequate.

STUDENT PERFORMANCE

Because this experiment requires several hours
to conduct, students are given a complete set of
specified operating conditions and the procedure

1, r l 1 ' THERMOCOUPLEE
0i
o li !l! \\\ j 0 ELECTRICAL INPUT


th II ' CATALYST BASKET
0 II II II II 0





I--------- ���



0. 10 0


HEATING ELEMENT AIR INLET SCREEN
FIG. 2.-Drawing of oven for TCC catalyst regeneration at four
temperatures.


CHEMICAL ENGINEERING EDUCATION















FIG. 3.-Collection of , * .
partially regenerated pellets. 'i j
I d





is outlined to them. Unfortunately there is no time
available for students to determine procedures in
a single laboratory session.
Students have no difficulty with the carbon
burning operation if the laboratory air pressure
and electrical voltage are reasonably constant.
Otherwise temperature control of the ovens may
present difficulties. Initially, there were occasional
burned fingers in removing pellets from the bas-
kets but an assortment of pliers and tweezers
eliminated this hazard. Some practice is required
for the pellet lapping to be successful but most
students have little difficulty in grinding away
half the pellet without losing the pellet or dam-
aging their fingers. The measurements with the


------------ --A-A- -


0.14-

0.12-

n in


-li 0.08

0.06


0.04


r


A
,, /


0 A A
A


F


k


0

A/


/
A o


cathetometer are straightforward.
Measurements with the optical densitometer
were attempted with several student groups. The
techniques required for obtaining thin center sec-
tions are difficult and most students were unsuc-
cessful. Reliable results were obtained only when
the instructor took charge in what approached a
"demonstration" experiment.
A collection of pellets from students' experi-
ments is shown in Figure 3. These pellets were
oxidized under the various oven conditions and
show the effects of rate-limited, intermediate and
diffusion-limited oxidation. The results obtained
by one group of students using the cathetometer
for measurements are shown in Figure 4 in which
a function of the fraction carbon remaining is
plotted against time as suggested by Eqn. (6). A
part of the scatter in the data is due to variations
in pellet diameter. This could be eliminated by
using t/R02 as a modified time parameter. The
value of K determined from the experiment was
within a factor of 2 of that calculated from the
pellet characteristics.

DEVELOPMENT OF THE EXPERIMENT
The experiment follows from the original in-
vestigations by Weisz and Goodwin. In the first
version of the oven, a tubular combustion furnace
was used. Two baskets were placed one above the
other in the vertically-mounted chamber. Tem-
perature control proved difficult and only two
regions of operations could be examined at one
time. The specially-designed oven allows four
baskets to be used and improves temperature con-
trol. The installation of a pressure regulator on
the air supply and use of packed beds of metal
below the baskets to damp fluctuations would im-
prove control still further.
It is doubtful whether the measurement of
carbon density profiles could be improved to the
extent that students could obtain satisfactory
results in a few hours. As a more lengthy project
in conjunction with numerical solutions of the
transient equations profile measurements might be
valuable.


O o
2 0


I I I I


0 10 20 30 40 50 60
TIME , MINUTES
FIG. 4.-Student correlation of results for oxidation under diffusion-
limiting conditions.


REFERENCES


1. P. B. Weisz, J. Wei, C. D. Prater, V. W. Weekman,
and B. L. Moulthrop, "Kinetics and Mass Transfer
of Burning Carbon from Catalyst," AIChE. Meeting,
Los Angeles, 1968.
2. P. B. Weisz and R. D. Goodwin, J. Catalysis 2, 397
(1963).


SUMMER 1971


0.02











A SIMPLE FORCED CONVECTION EXPERIMENT


0. C. SANDALL and D. A. MELLICHAMP
University of California,
Santa Barbara, Calif. 93106

M ASS TRANSFER EXPERIMENTS in chemi-
cal engineering programs are customarily re-
served for a "unit operations" or "transport pro-
cesses" laboratory course taken in the junior or
senior year. An attempt at introducing laboratory
experience in mass transfer at an early stage has
been made at the University of California at
Santa Barbara. Students, working in groups of
two to four, are assigned an experiment as a
term project in the mass transfer course which is
ordinarily taken during the third quarter of the
junior year. Design of the experiment, fabrica-
tion of necessary equipment, the collection of data,
and reporting of results to the rest of the class
furnish the student some "real-world" experi-
ences beyond those obtained from the usual labora-
tory demonstration or experiment.
Unfortunately, mass transfer experiments
often are more difficult to carry out than analog-
ous ones in the areas of heat and momentum
transport. Coupled with this difficulty is the
necessity to assign the students a reasonable pro-
ject to carry through in six to eight weeks; the
burden of avoiding this potential conflict obviously
is the responsibility of the instructor. The experi-
ment described in this paper meets these require-
ments very well; in particular, it furnishes a con-
vincing verification of the analogy between mass
and heat transfer and is well within the capa-
bilities of undergraduate students. The experi-
mental methods and results presented below re-
flect an evolution of techniques through three
groups of students in as many years.

PURPOSE
The basic objective of this experiment is to
measure local mass transfer coefficients for forced
convection mass transfer for flow past a circular
cylinder. Mass transfer coefficients are determined
by measuring the local rate of decrease in radius
of a naphthalene cylinder which is sublimed in
a low speed wind tunnel. Naththalene is particu-
larly well-suited for this experiment since it can
be cast into cylinders fairly easily, and it is a


solid having a significant vapor pressure at room
temperature.
By measuring the distribution of the mass
transfer coefficient around the cylinder, the results
obtained illustrate the separation of the laminar
boundary layer. The data also provide an experi-
mental verification of the analogy between heat
and mass transfer since heat transfer results are
readily available in the literature for comparison
with the mass transfer data obtained.

PREPARATION OF NAPHTHALENE CYLINDERS
Several methods of casting the naphthalene cylinders
were tried. It was found that uniformly smooth surfaces
were achieved by fast cooling, and the procedure used
was to pour the liquid naphthalene into a mold which had
been placed in liquid nitrogen. The mold was constructed
from a 12-inch long section of 2-inch diameter aluminum
pipe sealed at one end with a rubber stopper.
After the cylinders were cast and before removing
them from the aluminum pipe, a 1/2-inch hole was drilled
axially through the center. The reason for drilling out
the center is that the radius measurements were referred
to a �-inch aluminum rod that was placed through the
center of the naphthalene cylinders. As an aid in ob-
taining the desired angular orientation of the cylinders
in the wind tunnel, a 1/16-inch hole was drilled through
the cylinders on a diameter. A 1/16-inch rod was placed
through this hole and, when the cylinder was mounted
in the wind tunnel, the cylinder was oriented so that this
rod was perpendicular to the floor of the wind tunnel
test section.


FIG. 1.-Mounting Arrangement for Naphthalene Cylinders.

The aluminum tubing was removed from the naph-
thalene cylinders by taking cuts on a milling machine
along opposite sides of the tube until the wall thickness
was thin enough to remove the two halves by hand.
In order to measure the angular position along the
circumference of the cylinders, a length of masking tape
of size equal to the circumference was cut and marked


CHEMICAL ENGINEERING EDUCATION


134

























Orville C. Sandall is currently an assistant professor
in Chemical Engineering at the University of California
at Santa Barbara. He obtained his education at the Uni-
versity of Alberta (BSc, MSc) and the University of Cali-
fornia at Berkeley (PhD). His teaching and research in-
terests are in the areas of heat and mass transfer. (left).
Duncan A. Mellichamp is an assistant professor in
Chemical Engineering at the University of California at
Santa Barbara. He received the BChE at Georgia Tech,
studied one year at the Technische Hochschule Stuttgart
(Germany), and obtained the PhD at Purdue University.
His present interests are in the fields of process dynamics
and automatic control. (right).

off into 18 equal divisions to give 20-degree intervals,
The placement of the tape at one end of the cylinder was
facilitated by the orientation hole which had been drilled
on the diameter.

EXPERIMENTAL MEASUREMENTS

Measurements of the cylinder radius before sublima-
tion were made by placing a �-inch aluminum rod through
the hole drilled through the center of the naphthalene
cylinder. The aluminum rod was supported by two V-
blocks, and radius measurements were made to� 0.001
inch with a vernier height gage. The actual distance
measured was the radial distance between the center bar
and the naphthalene cylinder. It was found that the radius
measurements did not vary significantly in an axial direc-
tion, but did vary along the circumference, and for this
reason initial radius measurements were made at 20-degree
intervals around the circumference.
The students made initial estimates of how long the
experiment should proceed in order that a sufficiently
measurable change in the radius would occur. This cal-
culation indicated that a time on the order of 10 hours
was required for the Reynolds numbers of interest.
The naphthalene cylinder was mounted in a stand as
shown in Figure 1 and placed in the wind tunnel test
section. The air velocity was measured and adjusted to
give the desired Reynolds number by using either a
pitot tube or a hot wire anemometer. Air temperature
measurements were taken during the course of the ex-
periment. After the experiment had proceeded for the
pre-determined length of time, the air flow was stopped
and the final radius measurements were taken at angu-
lar positions measured from the forward stagnation point.


This experiment furnishes a convincing verification
of the analogy between mass and heat transfer
and is well within the capabilities of
undergraduate students

INTERPRETATION OF RESULTS

A mass balance at a position on the surface of
the cylinder relates the rate of decrease in radius
to the sublimation flux:
Sdr
- P O = a,s (1)
Using the nomenclature of Bennett and Myers,1
the mass transfer coefficient is defined in terms
of the diffusion flux as:
N (p -p N (2)
Na,s = (Pa,s - Pa,) Xa,sN a,s (2)
Substitution of Equation 2 into Equation 1 and
approximation of the derivative with finite differ-
ences gives upon rearrangement:

k' = - p - ) A (3)
P (Pa,s - Pa,)
In Equation 3 the density of naphthalene in the
free stream is zero (p,, c = 0), xa,s is very small
compared to 1.0 (Xa,s<
culated from the ideal gas law (pa, - Pa* Ma
RT
With these substitutions Equation 3 becomes:

P paN Ae (4)

Thus measuring the change in radius of the cylin-
der allows calculation of the mass transfer co-
efficient. The vapor pressure, pa*, in Equation 4
was obtained as a function of temperature from
the International Critical Tables.2
Figure 2 shows the data obtained at a Reynolds
number of 110,000 plotted as the local Sherwood
number. The data show the high mass transfer
coefficient that occurs at the forward stagnation
point. The mass transfer coefficient then decreases


800o-


0 20 40 60 80 100 120 140 160 180
ANGLE MEASURED FROM FORWARD STAGNATION POINT, DEGREES
FIG. 2.-Local Mass Transfer Coefficients for a Circular Cylinder
Measured at Re = 110,000.


SUMMER 1971


400

200









to a minimum as the laminar boundary layer
thickens. This minimum occurs at a position ap-
proximately 80� from the forward stagnation
point and indicates the separation point of the
laminar boundary layer. Beyond the separation
point the surface is exposed to the turbulent wake
which results in an increasing mass transfer co-
efficient to a maximum at the rear stagnation
point.
Figure 3 shows a comparison between the mass
transfer data obtained and the heat transfer data
of Zapp5 for the same Reynolds number. The good
agreement obtained between the heat and mass
transfer data provides a convincing experimental
verification of the analogy between heat transfer
and low mass flux mass transfer. For this com-
parison the heat transfer Nusselt numbers are
divided by Pr1/3 and the mass transfer Sherwood
numbers are divided by Sc1/3. The basis for these
factors is the Colburn analogy between heat and
mass transfer. The physical properties used in this
plot were obtained from Perry4.


40C
Sh/Sc'3
"' 30C


200

100


20 40 60 60 100 120 140 160 180
ANGLE MEASURED FROM FORWARD STAGNATION POINT,DEGREES
FIG. 3.-Local Mass Transfer Coefficients Compared with Heat Transfer
Data at Re = 110,000.

The heat transfer data of Zapp shown in
Figure 3 were obtained for a main-stream turbu-
lence intensity of 0.9%, which is considered to be
low, whereas, the turbulence level for the mass
transfer experiment was not measured but was
thought to be low. The deviation between the two
curves may be attributed to a higher turbulence
level in the mass transfer experiment or possibly
to an error in temperature measurement since an
error of 1�C corresponds to approximately a 10%
change in vapor pressure.
A further test of the mass transfer data was
made by comparing the mean mass transfer Sher-
wood numbers obtained with correlations de-
veloped for heat transfer. The relationship recom-


FIG. 4.-Mean Sherwood Numbers Compared with Heat Transfer
Correlation.

mended by McAdams3 for predicting the average
heat transfer coefficient for air flowing past cir-
cular cylinders is
Num = cRe" (5)
For Reynolds numbers in range of the mass trans-
fer experiments the constants c and n are given
as c = 0.239, and n = 0.805. If the constant c is
modified according to the Colburn analogy to take
the difference in Schmidt and Prandtl numbers
into account, then the mass transfer equation
equivalent to Equation 5 is
Shin = 0.0266 Sc/3Re0.805 (6)
Figure 4 gives a comparison of the data and
Equation 6. As can be seen, a favorable compari-
son was obtained.

ACKNOWLEDGMENT

The authors wish to acknowledge the capable
assistance of Messrs. H. Graeser and J. Hay in
the development of procedures for preparation of
naphthalene cylinders.

NOMENCLATURE
c-constant in Equation 5, dimensionless
C1,-heat capacity, BTU/lb �F
d-diameter of cylinder, ft.
D,,b--diffusion coefficient, ft.2/hr.
h-heat transfer coefficient, BTU/hr.-ft.2 �F
k-thermal conductivity, BTU/hr-ft-�F
k'-mass transfer coefficient, ft/hr
Ma-molecular weight of naphthalene, lb/lb mole
n-constant in Equation 5, dimensionless
N, ,--mass flux at the surface, lb/hr-ft.2
p,*--vapor pressure of naphthalene, lbf/ft.2
r-radius of cylinder, ft.
R-gas constant, lbf-ft./lb mole �R
T-temperature, �R
u oo -free stream velocity, ft./hr.
x, ,--mass fraction at surface, dimensionless
p-density of solid naphthalene, lb./ft.3
p,, s-density of naphthalene in gas phase at surface,
lb/ft3
(Continued on page 143)


CHEMICAL ENGINEERING EDUCATION


- MASS TRANSFER DATA
-----HEAT TRANSFER DATA




b, ,x ///
\ /-/


500�








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An Equal Opportunity Employer










ZONE REFINING

A Student Experiment

R. R. HUDGINS
University of Waterloo
Waterloo, Ontario


Since its invention by Pfann1 less than two
decades ago, zone melting has become a powerful
and important tool for manipulation of impurities
in solids2,3
Two objectives are served by presenting an
experiment in zone refining to chemistry or chemi-
cal engineering students. First, an unusual and
ingenious separation process is shown based on
differences in solubilities of a substance (impur-
ity) between solid and liquid phases. Secondly,
modelling of the process reinforces in a new con-
text concepts used to derive the equations for flow
tank reactors. The success of the model may then
be tested by comparing theoretical and experi-
mental results.
Numerous designs exist of simple apparatuses
for carrying out zone refining.4-7 To the author's
knowledge, the following is the only description
of a quantitative zone refining experiment for stu-
dent use. Additional impact is achieved by means
of a dye impurity, which produces changes in
colour intensity along the length of the ingot.

DERIVATION OF THE MODEL
The model will be developed by analogy with a
continuous flow stirred reactor familiar to stu-
dents of elementary reactors. Symbols conven-
tionally used with these reactors will be employed
to stress the analogy with the zone refining model.
The word reactor is used here in a broad sense
since zone refining is not necessarily concerned
with a chemical reaction.
We assume that the mixture initially contains
uniformly distributed impurity. The molten zone,
of length 1 moves through the ingot as shown in
Figure la, and is idealized to a completely mixed
region. Figure lb shows the analogous model of
the continuous flow stirred flow tank reactor
(CSTR) with constant input Co.
The transient equation for conservation is
Input - Output = Accumulation (1)
For the conservation of mass for the impurity,


Robert R. Hudgins is an associate professor in the De-
partment of Chemical Engineering, University of Water-
loo, Waterloo, Ontario, Canada. He received his BASc
(1959) and MASc. (1960) degrees from University of
Toronto, and his PhD from Princeton University (1964).
In 1967, he spent four months as a visiting professor at
Polymer Corporation, Sarnia, Ontario. His research in-
terests are kinetics, catalysis, and reactor design.

Equation (1) becomes:
V dC
PC - FC = V L (2)
FCo - FCs dt (2)
where CI, and Cs are concentrations of impurity in
molten zone* and in solid leaving molten zone,
respectively; F is the volumetric flow rate of solids
from the molten zone; t is time from the start of
operation in either the zone refining region or the
normal freezing region-See Eqn. (6) ; and Vo is
volume of the molten zone (constant) in the zone
refining region.
Relating equation (2) to that conventionally
used to describe transient behaviour of a CSTR,
we find two major differences: first there is no
output of impurity due to chemical reaction, and
second, the concentration within the reactor is CL
instead of C3. However, these two concentrations
are related through the distribution coefficient,
defined as:
k = Cs /CL (3)
Equation (3) is substituted into equation (2) and
the resulting equation is integrated noting that
C, = kCo at t = 0. Furthermore, it is apparent
that at any distance x to the edge of the molten
zone:
Ft x
V~ (4)
Thus, we obtain the equation for the zone refining
region

*All "concentrations" in this paper are given in di-
mensionless units, namely g. impurity/g. solute.


CHEMICAL ENGINEERING EDUCATION


.1
'Cl









c -kx
=1 - (1-k) e (5)
Co
0
When the leading end of the molten zone reaches
the end of the ingot, the feed into the molten zone
stops, causing a discontinuity in the process. This
region is known as the "final zone length" and the
process in this region is known as "normal freez-
ing."
Figure Ic shows the decreasing volume of the
molten zone, the analogy of which is shown in
Figure Id to be a CSTR draining at constant flow
rate.


x 9a



la








Ic


CCCL C
F V F

Ib






CLV VC
Id F


Fig. 1 (a).-Zone Refining Model. (b). CSTR Analog of (a). (c). Normal
Freezing Model. (d). CSTR Analog of (c). Heavy arrows indicate direc-
tion of zone migration.
Equation (1) for this situation is:
dVCL
0 - FC =d L
O-F dt (6)
where now, both V, the volume of the molten zone,
and CL are varying with time. For constant speed
of the molten zone interface:
V = V� - Ft (7)
Combining equation (3) and (7) and introducing
the definition
V-- = 9 (8)

we find that in the final zone length, equation (6)
becomes:
C
S=( - g)k - (9)
Where C/' = concentration of impurity in solid
leaving the molten zone as normal freezing begins.
Equations (5) and (9) are now available for cor-
relating the results of zone refining.

THE EXPERIMENT

The zone refining equipment, shown sche-
matically in Figure 2 consists essentially of an
electric heating coil mounted on a motor driven


Fig. 2.-Schematic of Zone Refiner. Arrow indicates direction of zone
migration. 1. Acetanalide-crystal violet mixture. 2. Glass sample tube
with cooling tube in center. 3. Stand. 4. Motor and gear box. 5. Worm.
6. Heater (25-watt). 7. Air cooling jets. 8. Molten zone. 9 .Asbestos
plug. 10. Guide rods. 11. Cooling air inlets.


worm and a glass tube containing the acetanilide
contaminated with crystal violet dye. Suitable
gearing allows the heater to move downwards at
10 cm/hr. This speed was used for convenience
in keeping the zone melting process itself to
within 11/2 hr. This speed is, however, somewhat
above the normally recommended rate of 0.3 to
4.0 cm/hr. The glass tube contains a hollow glass
tube in the centre. This annular format was used
for the zone in an effort to keep the melting and
freezing interfaces of the molten zone approxi-
mately perpendicular to the direction of move-
ment.
To find the impurity concentration profile of
the zone refined ingot, a number of samples are
taken from various parts of the ingot, using a
scraping tool fashioned by making teeth on one
end of a hollow tube fitting into the annulus of the
glass tube. In the first and last thirds of the ingot,
samples are taken at approximately 0.5 cm in-
tervals, whereas in the centre third, they may be
taken at 1 cm intervals. This sampling scheme is
followed in view of the expected concentration pro-
file. The samples are then weighed accurately on
a chemical balance and dissolved in methanol in
small volumetric flasks. The transmittance of each
solution is determined, and the calibration curve
for the spectrophotometer and the sample weight
are used to determine the concentration of crystal
violet dye in the acetanilide in the sampled section
of the tube. Typical results of this analysis are
shown in Figure 3.


SUMMER 1971


















08



4-
C2 ,ii

0 2 4 6 8 10 12 14
Distance along Ingot - cm
Fig. 3.-Concentration Profile of the Zone Refined Ingot Legend: 0
experimental points; dotted line represents theoretical values using
k = 0.20, I = 2.05 cm, Co 4.5 x 10-4 g crystal violet per g mix-
ture. i = Zone Refining Section; ii = Normal Freezing Section.

INTERPRETATION OF RESULTS
Figure 3 shows the results of a single pass of
the ingot through the zone refining apparatus. The
result of a single pass of the zone through the in-
got initially at uniform impurity concentration
level. The sharp break in the curve indicates the
commencement of the final zone length.
In Figure 4, the results of the zone refining
section are plotted according to equation (5) in
its semi-logarithmic form. It is readily seen that
the slope of the line in Figure 4 is equal to k/l
and that the intercept is equal to k-1. Thus, both
k and 1 may be determined independently from
this measurement.
Figure 5 shows the log-log plot of equation
(9). From this equation, the slope is obtained as
k-1. However, it is usual to see at least some
curvature of the data on this plot; thus, one con-
cludes that the distribution coefficient varies with
the concentration of crystal violet dye. Because of
the large change of impurity concentration in this
region, it is best not to rely on k and 1 data ob-
tained from the normal melting region, except to
qualitatively confirm the model described by equa-
tion (9).
Results obtained by two classes of students
using equation (5) showed values of k varying
from 0.08 to 0.21 while corresponding values of
1 varied from 1.5 to 4.0 cm. The actual heater
length was approximately 2.5 cm; therefore, the


This experiment introduces an unusual but important
separation process and relates it to the
analysis of a CSTR.


1-0
0.9
08
0.7
0.6

005
U
U0.4


0.3



no


0 2 4 6 8 10 12
x- Distance - cm
Fig. 4.-Plot of Equation (5) for Zone Refining Section.

results reporting the molting zone to be less than
2.5 appeared perplexing at first. However, upon
examining the error structure of equation (5), it
can be seen that alak = 10 cm. A similar value
was calculated from the class results. The reason
for the variation in the values of 1 is that the
value obtained for k is sensitive to the intercept
of the straight line in Figure 4, and the corre-
sponding variation in 1 is strongly correlated with
it, as the partial derivative shows. To reduce the
bias in obtaining the intercept in the plot of
Figure 4, the data should be fitted by means of a
least squares line.
100 I---- . .
80
60
40


X 20
U
10
10-0
8
6

.06 .1 .2 .4 .6 .8
I-g
Fig. 5.--Plot of Equation (9) for Normal Freezing Section.


CHEMICAL ENGINEERING EDUCATION











ENZYME-CATALYSIS EXPERIMENT


D. M. GORBER and J. M. SCHARER
University of Waterloo,
Waterloo, Ontario, Canada

The recent interest of chemical engineering
students in biological phenomena has prompted
the need for experiments illustrating enzyme ki-
netics. The study of enzymatic reactions, how-
ever, often requires elaborate apparatus not
normally available in chemical engineering lab-
oratories or reagents with prohibitive cost for
general use. Therefore, our purpose was to design
an experiment, which was simple to construct, in-
expensive, and could be performed within the as-
signed laboratory period of two hours. Of the
known enzymatic reactions, the decomposition of
hydrogen peroxide (H,20) by beef liver catalase
best suited these goals.

GENERAL THEORY

The mechanism of catalase action using H202
as its substrate has been well elucidated1'2. The re-
action sequence is initiated by the reversible for-
mation of an enzyme-substrate complex, as indi-
cated by:
k1
Catalase-Fe (oH) + (O H202H Catalase-Fe -OOH + H20 (1)
k2
Next a second H,02 acts as an oxidating agent of
the complex. This results in

Catalase-Fe -00H + H 202 Catalase-Fe ((OH) + H20 + 02 (2)

When the molar ratio of H1O0/catalase is suffi-
ciently high, the reaction sequence can be approxi-
mated b; the familiar Michaelis-Menten type
Model:
kV k'
Catalase + H11O 2 Catalase-H 0 _L H0 + 1/2 + H2 (3)

The rate of appearance of the catalase-H202
complex, ES, is given as:
dIES] = k' 1[E] [S] - (k'2 + k'3) [ES] (4)

where [E] is the free enzyme concentration and
[S] is the substrate concentration.
The rate formation of product, P, is:
d[ = k' 3 [ES] (5)
The relative magnitudes of the individual rate
constants are such that the concentration of the


J. M. Scharer received his BSc ('62) and PhD ('65)
from the University of Pennsylvania. His doctoral thesis
topic was thermal death kinetics of bacterial spores. He
then spent two years at the U.S. Army Biological Center
in Frederick, Maryland. He joined the faculty at the Uni-
versity of Waterloo in 1967 as a member of the biochemi-
cal engineering research group. His research interests in-
clude bacterial oxidation of sulfides, cellulose degradation,
and tissue culture. This experiment was developed while
Dr. Scharer was chairman of the ChE laboratory com-
mittee. (left)
D. M. Gorber is receiving his PhD in ChE from the
University of Waterloo in September '71. He obtained his
Bachelor's Degree from the University of New Brunswick
('66) and his Master's Degree from Waterloo('68). During
the past two years Mr. Gorber has been the Senior
Demonstrator in the undergraduate physical chemistry
laboratory where it has been his duty to organize the
laboratory and develop new experiments. He has a keen
interest in pollution control and has accepted a position
with James F. MacLaren Limited, environmental con-
sultants in Toronto, Ontario. (right)


complex rapidly approaches a pseudo steady state:
d =ES] 0 (6)
dt
Furthermore, the sum of the enzyme concen-
trations in free and complex form is equal to the
initial enzyme concentration, Et;
[Et] - [E] + [ES] (7)
The dependence of the rate of product formation
on the initial enzyme concentrations is obtained by
combining equations (4) to (7) yielding:
dP 1/2 k'3 [Et] [S]
dt k'2 + k3 (8)

This eliminates the [ES] term which is very diffi-
cult to measure directly during a run.


SUMMER 1971









When only a single concentration of enzyme
is used throughout the experiment equation (8)
can be rewritten as
d[P] [S]
dt Km + [S] (9)
This is the characteristic equation for enzyme re-
actions involving one substrate; Km is the
Michealis-Menten constant and 1k the maximum
reaction rate for a given enzyme concentration. To
conveniently calculate Km and Mx equation (9) is
rearranged as:
1 Km 1 1

Equation (10) is called the Lineweaver-Burk
equation. The constants M and Km can be readily
obtained from the slope of the plot and the inter-
cept.
SHIELDED CONE HEATER -CONSTANT TEMPERATURE CABINET


FIG. 1.- Schematic Diagram of Apparatus.


EXPERIMENT
The reaction vessel was constructed from a 500
ml Ehrlenmeyer flask as shown on Figure 1. The
manometer, swing arm sample holder and bubble
counter were connected to the flask with ground
glass joints. The water manometer was used to
maintain a constant pressure in the vessel, while
the swing arm sample holder provided a means
for rapid addition of the enzyme without disturb-
ing the internal pressure.
To calculate the reaction rate the oxygen
evolution was measured. Since this was achieved
by visual bubble counting, the substrate and en-
zyme concentrations had to be carefully selected.
Best results were obtained with 400 ml of 0.05 M
phosphate buffer (pH = 7) and 5 ml of diluted
(300 X) beef liver catalase, (Nutritional Bio-
chemicals). This gave a maximum bubbling rate
of 2 bubbles per second.
Biochemical rate data is very sensitive to the
choice of substrate concentration. At very high
concentrations the catalase is subject to denatura-


Our purpose was to design an experiment which
was simple to construct, inexpensive, and could
be performed within two hours.

tion; on the other hand, at low concentrations the
rate becomes too slow for measurement. On the
basis of statistical evidence, Cleland3 has recom-
mended a substrate concentration range of 0.2
Km to 5 Km as the ideal choice. This corresponded
to a reaction velocity of 1/6 to 5/6 the maximum
bubbling rate. The accepted value4 of Km (pH 7,
30�C) for this reaction is 1.1 x 10-2 M. In this
experiment we have used 0.1 ml of 30% H02z
solution (0.23 Km) to 2 ml substrate (4.5 Km)
per 400 ml working volume. Since the Lineweaver-
Burk plot involves inverse concentrations, the in-
itial substrate levels were selected in accordance
to a geometric series.

PROCEDURE
The phosphate buffer solution was brought to 30�C
overnight in the constant temperature cabinet. For each
run 400 ml of the solution and the desired amount of H,20
were placed in the reaction flask. The enzyme was pipetted
into the swing arm sample holder which was placed in
the downward position. A constant internal pressure was
obtained by adding water to the manometer until the first
bubble appeared in the bubble counter. The reaction was
initiated by moving the swing arm to an upright position.
The oxygen evolution was measured by counting bub-
bles in a 20 second interval each minute for 10 minutes.
This procedure was repeated for the various concentra-
tions of HO,2. The pH of the buffer was measured initially
and after the completion of a run. If the pH change was
more than + 0.1 pH units for some unknown reason, the
run was repeated.

RESULTS

This experiment has been performed by second
year chemical engineering students during the
past year. A sample of typical results is shown
on Figure 2. The data points were obtained by
averaging the three highest measurements of
oxygen evolution. This gave a representative
maximum evolution rate for a particular initial
substrate level. The volume of a bubble was found
to be 0.1 ml at 30�C in previous experiments.
Using this information the oxygen evolution rate
(moles/liter-min) could be readily calculated.
Linear regression analysis was performed by the
students on the inverse rate data, and they ob-
tained the characteristic constant Km from the
slope and the intercept. Results were found to be
reproducible from week to week. The experiment
involved about one and a half hours laboratory


CHEMICAL ENGINEERING EDUCATION

























0 100 200 300
moles-' liter
[s]


400 500


FIG. 2.-Lineweaver-Burk Plot.

time and about one hour to perform the calcu-
lations.
We have found that although this experiment
introduced new concepts to the students, the
theory was not beyond their grasp. We were able
to present the students with an elementary under-
standing of biochemical phenomena and arouse
interest in a growing area in chemical engineer-
ing.

REFERENCES

1. McElroy, W. D. and Glass, B., Ed., Mechanism of En-
zyme Action, p. 402, Greenwood Press, New York,
1968.
2. Dixon, M. and Webb, E. C., Enzymes, p. 311, 2nd
Ed., Academic Press, New York, 1964.
3. Cleland, W., "The Statistical Analysis of Enzyme
Kinetic Data," Advances in Enzymology, Vol. 29, p. 1,
1967.
4. Barman, T. E., "Enzyme Handbook," Vol. 1, p. 232,
Springer Verlag, New York, 1969.


ZONE REFINING: HUDGINS
(Continued from p. 140)

With a non-uniform impurity profile in the
ingot, the solution of equation (2) is no longer
analytically tractable. This need not deter fur-
ther experimentation; indeed, some students may
find it worthwhile to compute the results for two
or more passes of the molten zone, and test these
with experiment.

SUMMARY

This experiment serves to introduce an un-
usual but important separation process and pro-
vide practice in thinking through a mathematical


pH 6.76
p = 740 mm Hg
T = 30.1 �C
SKm, *3.3 0-2 mole/liter
u =6xl0-o mole/liter min.


SUMMER 1971


description of it closely related to that used for
flow tank reactors.

LITERATURE CITED

1. Pfann, W. G., Zone Melting, John Wiley & Sons, New
York, 2nd ed. 1966.
2. Schildknecht, H., Zone Melting, Translated by Ex-
press Translation Service, London, Academic Press,
New York, 1966.
3. Schoen, H. M., from New Chemical Engineering
Separation Technique, Interscience Publishing Co.,
New York, 1st ed. 1962, pp. 103-155.
4. Christian, J. D., J. Chem. Ed. 33, 32 (1956).
5. Hinton, J. F., McIntyre, J. M., Amis, E. S., J. Chem.
Ed. 45, 116 (1968).
6. Knypl, E. T., and Zielenski, K., J. Chem. Ed. 40, 392
(1963).
7. Zeif, M., Ruch, H., and Schramm, C. H., J. Chem. Ed.
40, 351 (1963).
8. Denbigh, K. G., Chemical Reactor Theory, Cambridge
University Press, London, 1965.
9. Herington, E. F. G., Zone Melting of Organic Com-
pounds, Blackwell Scientific Publications, Oxford, 1st
ed. 1963.

ACKNOWLEDGMENT

The author wishes to acknowledge the assistance of
Messrs. Wm. Cushing and Rudy Frankle in developing
the apparatus, and of some data obtained by Messrs, H.
K. Leong and J. P. Bouchard.


CONVECTION: Sandall and Mellichamp
(Continued from p. 136)

pa, oc-density of naphthalene in gas phase in free
stream, lb/ft.3
p,--absolute viscosity, lb/hr-ft.
v-kinetic viscosity, ft2/hr.
--time, hr.
Nu-Nusselt number, hd/k
Pr-Prandtl number, /CpC/k
Re-Reynolds number, u oo d/v
Sc-Schmidt number, v/Dab
Sh-Sherwood number, k'pd
Dab

REFERENCES

1. Bennett, C. 0., and Myers, J. E., "Momentum, Heat,
and Mass Transfer," McGraw-Hill Book Co., Inc.,
New York, 1962.
2. "International Critical Tables," Vol. 3 p. 208,
McGraw-Hill Book Co., Inc., New York, 1928.
3. McAdams, W. H., "Heat Transmission," 3rd ed., p.
260, McGraw-Hill Book Co., Inc., New York, 1954.
4. Perry, J. H., ed., "Chemical Engineers' Handbook,"
4th ed., McGraw-Hill Book Co., Inc., New York, 1963.
5. Zapp, G. M., M. S. Thesis, Oregon State College,
1950; Knudson, J. G. and Katz, D. L., "Fluid Dy-
namics and Heat Transfer," McGraw-Hill Book Co.,
Inc., New York, 1958, pp. 496-501.










I problems for teachers


Teclniqce jo'& Ana4lift


Complex Chemical Engineering Systems


WOOYOUNG LEE and YUICHI OZAWA
Mobil Research and Development Corp.
Paulsboro, N. J. 08066

The analysis of complex systems described by sets of
nonlinear simultaneous equations appears frequently in
chemical engineering teaching. The method1,2 proposed
here will simplify the computational procedures and pro-
vide students with better insight into the problem.
If a set of m-simultaneous equations contain n vari-
ables, we have to assign numerical values to at least
(n - m) variables to start the computation; these vari-
ables are called design variables. The selection of a set
of design variables may yield the simplest information
flow structures in which no feedback loops are involved.
(acyclic flow structure). If no acyclic structure is found
by the selection of design variables, at least parts of the
system of equations must be solved simultaneously.' We
will illustrate the method of selecting a set of design
variables to obtain an acyclic structure:
Q. The binary mixture of A and B forms an ideal
solution which has the relative volatility of a. A
batch of this mixture containing xF of A is
charged for a batch distillation. A fraction of the
initial charge is distilled and the distillate is again
charged to a second still, a fraction of which is
distilled. (See Fig. 1.) Write a mathematical model
for this operation and derive a solution procedure
for the model.
A. The material balance equations and Rayleigh's
equations for Fig. 1 are:
1st Distillation:
F XF = DY1 + (F - D1) x1 (1)


-1 x- 1 x \F

2nd Distillation:
DIY1 = D2Y2 + (D1 - D2) x2 (3)


D -D2
D ~3. 2,


xj l -x
X2 'l /


(4)


where
F = moles of initial mixture charged
Xp = mole fraction of A in initial mixture
Di = mole distilled
yi = mole fraction of A in distillates
xi = mole fraction of A in bottoms
a = relative volatility


DIn Y1 I

Ir ^i m


D2' Y2









D1 - D2, x2


F - D
x1


Fig. 1. Two-State Batch Distillation of a Binary Mixture
Notice that we have 4 independent equations
and 8 variables; 4 of which must be known to
solve the equations for the remaining variables.
The step-by-step procedure of the technique2 is
described below.
Step 1: Construct a structural array matrix
of the system as shown in Fig. 2. The rows cor-
respond to equations, and the columns to vari-
ables. An X is placed whenever a variable appears
in an equation.
The structural array matrix, compactly revealing
the pattern of interconnections of these equations,
improves one's insight into the problem consider-
ably. For example, it directly shows which vari-
able appears most frequently in which equations
and therefore its relative importance in the sys-
tem. For systems of large sizes it is extremely
useful to employ the structural array representa-
tion to systematically analyze their structures.
Step 2: Find a column which has only one X.
Assign the variable corresponding to this column
to the equation (row) that has this X, and delete
this column and row from the matrix. Repeat this
procedure of elimination until no further reduc-
tion is possible. For example, in Fig. 2, the last
column (y2) has only one X in the third row
(Eq. 3); therefore, assign y, to Eq. 3 as its output


CHEMICAL ENGINEERING EDUCATION









F xI DI x, Y, D2 x2 Y2

Eq. 1 X X X X (X-

Eq. 2 X X ( X X

Eq. 3 X X X X (X

Eq. 4 X X X E 2p
Fig. 2. Structural Array Matrix of the Example


variable and delete Eq. 3 and y, from the matrix.
This enables us to assign the 7th column (x2) to
Eq. 4 and delete these, and so on.
Assigning a variable to an equation as its out-
put variable means that this equation is solved for
the variable. If a variable appears only in one
equation, this variable must either by solved from
the equation or be given as design variable. We
prefer to assign such a variable as an output vari-
able to simplify the information flow structure.
Fortunately for our example, we could eliminate
all of the equations in the following order.
1st-Assign Y2 to Eq. 3, and delete them
2nd-Assign x2 to Eq. 4, and delete them
3rd-Assign y1 to Eq. 1, and delete them
4th-Assign D1 to Eq. 2, and delete them
When alternate choices of output variable assign-
ment are available, we can incorporate our judg-
ment into the procedure. For example, for the last
assignment above, we have assigned D, to Eq. 1.
However, we could have assigned x, to Eq. 1. The
reason that we have selected D1 over x, is that it
is easier to solve Eq. 1 for D1 than for x,. For in-
stance, Eq. 1 can be explicitly expressed for D1,
whereas not for x,. In digital computers, this
means straight computation for D1 vs. iterative
calculation for x,. This argument has been gen-
eralized, which resulted in the concept of difficulty
scores3 to account for relative difficulty of solving
an equation for a variable.
Step 3: By definition, the variables not as-
signed yet are design variables, and the order of
computation is the reverse order of the elimina-
tion in Step 2.
For our example, this technique has found one
of the acyclic structure, and hence these equations
can be solved one by one in the following order.
Assume values of x,, F, x, and D, (these are de-
sign variables). This will enable us to solve the
equations in the following order:
1st-Eq. 2 is solved for D1 and substitute this value
to other equations.
2nd-Eq. 1 is solved for y,, and substitutions.


-0


SUMMER 1971


3rd-Eq. 2 is solved for x2, and substitutions.
4th-Eq. 3 is solved for Y2
CONCLUSION

The method of design variable selection has
been illustrated with a simple example. Experi-
ences show that this technique is very useful for
the analysis of complex systems of equations
either in teaching or in industrial research.4
REFERENCES
1. Lee, W., Christensen, J. H., and Rudd, D. F., AIChE
J. 12, 1104 (1966).
2. Rudd, D. F. and Watson, C. C., Strategy of Process
Engineering, Wiley, 1968, Chapt. 3.
3. Lee, W. and Rudd, D. F., "Design Variable Selection
Method and the Concept of Difficulty Scores," to be
published.
Lee, W., "Design Variable Selection Technique and
the Information Flow Structure Analysis of a Cata-
lytic Cracking System," to be published, 1971.


book reviews
Process Analysis and Simulation: Deterministic
Systems
D. M. Himmelblau and K. B. Bischoff;
John Wiley and Sons (1968), 348pp.

I wish to mention two points before attempt-
ing a review of this excellent book. First, I have
not used this book as text in a classroom situation.
A review of a textbook without classroom testing
is akin to a monk commenting on marriage and
should perhaps be discounted fifty cents on the
dollar. Second, and somewhat as a result of the
first point, I shall adopt a broad and general,
rather than detailed and specific, point of view
in phrasing my comments. The risk associated
with the latter point of view is that of being in
error while the former point of view risks saying
nothing at all.
This text is divided into three parts plus an
introduction discussing the author's overall phi-
losophy of process analysis. Part I discusses and
tabulates the mathematical models which are
often used in the simulation of physical systems
and processes. Chapter 2 of Part I is essentially
a resume of the equations of change for mass
momentum and energy as formally taught in
transport phenomena. A clear distinction is made
between the molecular, microscopic (continuum)
and macroscopic points of view, although some of
this excellent philosophy may be unappreciated
by the student who has not completed a formal








course in transport phenomena. Chapter 3 in
Part I further discusses an heirarchy in the clas-
sification of mathematical models arising from
transport phenomena. Thus, the groupings of
deterministic vs probabilistic, linear vs nonlinear,
steady state vs transient, and lumped parameter
vs distributed parameter are discussed. Some
illustrative problems are discussed, but this chap-
ter remains essentially an amplification of the
philosophy of mathematical model building.
Again, this excellent discourse on the philosophy
of model structure might well be lost on students
who have not had formal courses in transport
phenomena and process dynamics. Chapter 4,
population balance models, completes Part I. Ob-
viously, this area is the author's forte, and they
devote considerable attention to the formalism
of description and prediction of residence-time
distributions in flow systems. The strength of
this chapter is that the population balance-derived
equations are laid out for comparison with the
transport equations of Chapter 2; the weakness
of this chapter is the emphasis on residence-time
distributions at the expense of the concept of
particle phase space. This latter concept empha-
sizes the link of population balance equations
with the transport equations in the complete de-
scription of particulate processes.
Part II commences the "nuts-and-bolts" tech-
niques of process analysis. Students who have
completed a first-year graduate transport course
together with an undergraduate process control
background could start with Part II of this book
with perhaps some additional time spent in re-
view of Chapter 4. Part II is introduced by Chap-
ter 5, which chapter presents many of the mathe-
matical techniques appropriate to the process
models previously discussed. Again, Chapter 5 is
prefaced by an excellent philosophical discussion
of the strategy of mathematical techniques as they
operate on such process models. Discussed are the
techniques of solution of differential equations,
analytically and numerically, dynamic response
to impulse and step inputs, frequency response
and stability. Thus, the techniques of process
dynamics are linked with the model equations
arising from transport phenomena and popula-
tion balances. The emphasis of this section is on
the simplistic response equations of process dy-
namics rather than the detailed gradient analysis
found in transport texts. The techniques of di-
mensional analysis, not deserving of an entire
chapter, are included at the end of Chapter 5.


Chapters 6 and 7 complete Part II. Chapter 6
illustrates the application of population balance-
derived models to the study of reactors, including
the problem of crystal size distribution analysis
in an ideal backmixed single stage crystallizer
(reactor). Chapter 7 illustrates the techniques
of solution for typical subsystem models arising
from transport-based models. The strength of
this section is that an heirarchy of simplifying
assumptions is used in the formulation of these
models and the results are in turn compared to
experimental data. The successful trade-off be-
tween rigor and simplicity in modeling processes
is perhaps the key to this art and the techniques
are well illustrated here.
Part III is potentially the most important sec-
tion of this book in that it attempts to integrate
all of the detail presented to this point, models
and techniques of analysis, into detailed studies
of complete systems. The techniques of decom-
position of large-scale systems for a rational
attack on the problem of calculating the entire
system are demonstrated in Chapter 8. This chap-
ter introduces the subjects of graph theory and
their related Boolean matrices; such tools are
essential to the rational decomposition of large-
scale systems. The techniques of signal flow
graphs and sensitivity analysis are also intro-
duced in this chapter. Chapter 9 concludes Part
III and the book with specific applications and
examples of total systems analysis. The subject
of systems analysis is very difficult to teach except
by case history and detailed example. Fortunately,
Part III is replete with complex and detailed
examples, graphically presented, and should pre-
sent a constructive challenge to the motivated
teacher. It is this writer's pessimistic opinion
that in a classroom situation, the material in
Parts I and II will be emphasized at the expense
of Part III. Intentions and motives will be pure,
but lack of time and the difficulty of teaching such
integrated material will prevail. This is a crit-
icism of academia, not of this text.
It is this writer's opinion that the ideal situa-
tion for this text would be a class of second-year
graduate students who have taken a graduate
course in transport phenomena and have at least
an undergraduate background in process control.
The issue is not intellectual difficulty of the ma-
terial, but rather the wide range of ideas and
techniques that the integrated into the content of
this text. Successful teaching of such integrated
material and the meaningful assimilation of the


CHEMICAL ENGINEERING EDUCATION









propounded philosophies of model building re-
quires a certain amount of maturity on the part
of the students as well as teacher. The material
can certainly be taught in abbreviated form as
an undergraduate senior year elective, as the
authors themselves do, but it would require a
great deal of judgment and experience as well as
enthusiasm on their part. Fortunately, the Uni-
versity of Arizona has a second-year graduate
course in the area of process simulation, follow-
ing first-year courses in transport phenomena and
process dynamics and control; this text is quite
successfully used in this graduate course. The
material in this book is as important, or more
so, to the terminating MS candidate as to the
PhD student. Three semesters are normally re-
quired for such MS students and it should not be
difficult to enroll them in the course during their
final term.
Finally, this book should be on the shelf of every
practicing engineer who is even remotely connected with
the art of process simulation or must interact with those
who are. Some books, by their language and format,
widen the gap between the academic establishment and
practicing engineers in industry. This book moves the
two groups closer together.
University of Arizona
Alan D. Randolph

LETTERS (cont'd from p. 103)
Consider a gas filling an originally empty tank. If we
assume the gas in the tank to be well mixed, the total
internal energy of the gas is given, at any instant, by
Utotal = m u [1]
where m is the total mass, and u the internal energy per
unit mass. The internal energy per unit mass may be
expressed in the following manner:

u- I d T = c d T [2]

0 0
where T. is a reference temperature and c, the heat ca-
pacity per unit mass, at constant volume. Then
T
Utotal = m [ u + J cv dT J [3]


Differentiating with respect to time
T
total + m d c dT
total dt J v


where
T T
d--t cv d T= cv d T -- (T) "-
i I\dT dt C(T) dt
T T
o o
by Leibnitz's rule. Hence we finally obtain


Utotal u + m Cv(T) [4]
total d t

It is thus incorrect to express U total in the form
d
Total =t m (T) (T-To) [5]
as noted by Dr. Davidson. In the case where c, =A c, (T),
eqs. 4 and 5 are equivalent.
University of Florida
R. J. Gordon



ChE News

CACHE Committee Established by National Academy
of Engineering ... Goal Is to Accelerate
Integration of Digital Computation into
ChE Education

A panel of chemical engineering educators called the
CACHE (Computer Aids for Chemical Engineering Edu-
cation) Committee has been established by the National
Academy of Engineering's Commission on Education. The
purpose of the committee is to coordinate and encourage
the development of computing systems for use in chemi-
cal engineering education. The National Science Founda-
tion has provided a grant to support the activities of the
CACHE Committee for a two-year period.
The 17 members of the committee are drawn from uni-
versities throughout the United States and Canada. Each
member is actively concerned with the use of computers
in chemical engineering and many of them have been at
the forefront of the rapid developments in chemical en-
gineering computing that have taken place during the
past decade.
CACHE officers elected at a recent meeting in Ann
Arbor are: W. D. Seider (Pennsylvania), chairman; L. B.
Evans (MIT), vice chairman; and A. W. Westerberg
(Florida), secretary. Other members of the committee are:
B. Carnahan (Michigan), J. H. Christensen (Oklahoma),
E. Elzy (Oregon State), E. A. Grens (California at
Berkeley), E. J. Henley (Houston), R. R. Hughes (Wis-
consin), R. V. Jelinek (Syracuse), A. I. Johnson (Mc-
Master), R. L. Motard (Houston) M. J. Reilly (Carnegie-
Mellon), J. D. Seader (Utah), P. T. Shannon (Dart-
mouth), R. E. C. Weaver (Tulane), and I. Zwiebel (Wor-
cester Polytechnic).
The principal goal of the committee will be to ac-
celerate the integration of digital computation into the
chemical engineering curriculum by promoting inter-
university cooperation in preparation of new courses,
teaching aids, and computing systems.
A major stumbling block to widespread use of the
computer in engineering education has been the difficulty
in transferring computer programs developed at one insti-
tution for use at another. Incompatibilities in computer
system conventions, data formats, and documentation have
been responsible for duplication of effort at different
schools. CACHE has established a Standards Subcom-
mittee to devise mechanisms for facilitating easier inter-
university interchange of computer programs.


SUMMER 1971









Another factor that has slowed the use of computers
in the classroom has been the problem of intergrating the
computer use with the material covered in traditional
courses. A CACHE subcommittee on curriculum is con-
sidering this problem. Its first major project will be to
compile and publish a collection of one hundred com-
puter programs representing the best of those that have
been used successfully in undergraduate courses. The
programs will be selected on the basis of a nationwide
competition with entries solicited from students and
faculty at every institution in the country.
Other CACHE subcommittees and task forces are
looking at specific areas of computer applications, in-
cluding estimation and retrieval of physical property
data, computer-aided design, simulation of dynamic sys-
tems, on-line monitoring and control of experiments, and
computer-aided process synthesis.
The idea to establish a committee such as CACHE
originated with Professors Carnahan, Motard, and Seider
who organized the first meeting of interested chemical
engineering faculty members in Ann Arbor in April, 1969.
The committee is patterned after the COSINE Committee
which is also sponsored by the NAE and which serves a
similar function in electrical engineering. Professor Car-
nahan served as acting chairman of the CACHE Com-
mittee during the two years prior to receiving NSF
funding.
Dr. Newman Hall, Executive Director of the NAE
Commission of Education remarked that "The most im-
'portant challenge facing CACHE will be to find ways to
achieve an impact on the chemical engineering programs


at a large number of universities in addition to those
represented by CACHE Committee members." The com-
mittee has already invited several additional people to
serve on various subcommittees and task forces and many
more will be involved as on-going projects develop. A
specific CACHE representative will be designated at each
of the 135 U.S. Chemical Engineering departments to co-
ordinate communication between his institution and
CACHE. A newsletter will be produced by the committee
to report news of CACHE activities and other noteworthy
developments related to the use of computers in chemical
engineering education. Copies of the newsletter will be
made available to all interested individuals.
Although there are no representatives of industry on
CACHE, the committee plans to have close liaison with
industry and to involve people from industry as members
of its task forces. Many of the proprietary computer sys-
tems developed by industry for process simulation, design,
and control have great untapped potential for use in
education. Industry also has a special interest in the work
of the CACHE Committee, because the ultimate benefit
of accelerating use of computers in engineering education
is to produce engineering graduates with the training
to better meet the needs of industry.
Anyone who wishes to learn more about the work of
the CACHE Committee may contact any member or
Dr. Newman Hall, Executive Director, National Academy
of Engineering, Commission on Education, 2102 Con-
stitution Avenue N.W., Washington, D. C. 20418. The
committee welcomes suggestions and contributions from
all who are interested in any aspect of its work.


CHEMICAL ENGINEERING EDUCATION


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