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Chemical Reaction
Engineering—Plenary Lectures
James Wei, EDITOR
Massachusetts Institute of Technology
Christos Georgakis, EDITOR
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1 Based on the 7th
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ACS SYMPOSIUM SERIES
AMERICAN CHEMICAL SOCIETY
WASHINGTON, D.C. 1983
Library of Congress Cataloging in Publication Data
International Symposium on Chemical Reaction
Engineering
(7th: 1982: Boston, Mass.)
Chemical reaction engineering—plenary lectures.
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0 (ACS symposium series, ISSN 0097-6156; 226)
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6.f Includes bibliographies and index.
22 1. Chemical engineering—Congresses. 2. Chemical
3-0 reactions—Congresses. I. Wei, James, 1930-
8 II. Georgakis, Christos, 1947- . III. Series.
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k- TP5.I67 1982a 660.2'99 83-11876
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cati Copyright © 1983
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u American Chemical Society
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All Rights Reserved. The appearance of the code at the bottom of the first page of each
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The citation of trade names and/or names of manufacturers in this publication is not to be
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permission, to the holder, reader, or any other person or corporation, to manufacture, repro
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related thereto.
PRINTED IN THE UNITED STATES OF AMERICA
ACS Symposium Series
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6.f M. Joan Comstock, Series Editor
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98 Robert Baker Geoffrey D. Parfitt
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Marvin Margoshes Charles S. Tuesday
Donald E. Moreland C. Grant Willson
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6.f FOREWORD
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9 The ACS SYMPOSIUM SERIES was founded in 1974 to provide
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21/ format of the Series parallels that of the continuing ADVANCES
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0.1 IN CHEMISTRY SERIES except that in order to save time the
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3 | d mitted by the authors in camera-ready form. Papers are re
8 viewed under the supervision of the Editors with the assistance
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8, of the Series Advisory Board and are selected to maintain the
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PREFACE
01 IN THE NARROW SENSE, CHEMICAL REACTION ENGINEERING (CRE) is
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pr concerned with the design, operation, optimization, and control of process
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2 ing equipment called chemical reactors. CRE is the counterpart to unit
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3- operations (UO), which is concerned with processing equipment in which
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19 no chemical reactions take place. Both chemical reaction engineering and
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b unit operations integrate many disciplines to attain practical engineering
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02 goals. They differ from the engineering science subjects of kinetics, thermo
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0. dynamics, fluid mechanics, and transport phenomena that seek to isolate
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oi: and analyze an individual aspect of a complex piece of machinery or to
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3 | understand and describe quantitatively the material behavior at micro
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9 scopic or molecular scales.
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28, The main difference between chemical reaction engineering and unit
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ul operations lies in the presence or absence of chemical reactions. Except
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e: for purely separational processes, such as the production of oxygen from
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D air, the heart of any chemical process is one or more chemical reactions
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atio that transform less valuable feed material to more valuable products. In
blic the case of combustion, the main products are heat and energy rather than
Pu material products. In the case of pollution control equipment, the conver
sion of a harmful feed to harmless products is the main objective. Chemical
reactors lie in the heart of any chemical plant, and the unit operations
equipment serves the needs or compensates for the inadequacies of the
chemical reactors. The design of a chemical plant must start with the
chemical reactors, which usually run 10-20% of the total plant cost. When
you look over the flowchart of a process, you will find the chemical reactor
as a small unit in a very large network; yet, the design of all other equip
ment revolves around the chemical reactors. The optimum design of a
chemical reactor does not necessarily lead to the optimum design of a
chemical plant. The peripheral equipment of unit operations (the tail)
usually wags the chemical reactors (the dog). A good design engineer
chooses the dog that has the smallest tail.
ix
In a comparison of the salient features, the following may be noted:
Chemical Reactors Unit Operations
Function Chemical reactions Physical operations
needed to service the reactors
Design Individually tailored Modular; often can be
for each reaction ordered from catalogs
Cost 10-20% of total plant 80-90% of total plant
Performance Highly nonlinear due to Nearly linear
kinetic dependence on
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6. trations
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3- Intellectual Chemists and chemical Mechanical engineers
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1 Collaborators engineers
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oi: In the broader sense, chemical reaction engineering is also concerned
3 | d with the components needed for the synthesis of chemical reactors, such as
8 kinetics, catalysis, catalyst design, mixing, multiphase systems, fluid me
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8, chanics and transport in fixed and fluidized beds, and solid movement
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y mechanics in moving and fluidized beds. Study of the maldistribution of gas
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at mechanics, but this subject is very seldom studied by the major researchers
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but are hardly ever studied. Polymerization reactors are enormously impor
tant in the chemical industries and are beginning to attract serious re
searchers with backgrounds in reaction engineering.
Reaction engineers form a living and changing tribe that keeps in touch
through professional meetings and journals. They share a common set of
textbooks and tools, the same vocabulary and analytical scheme to analyze
problems, and the same set of triumphant classic achievements in the past.
They agree on what are proper problems to be tackled and what are proper
standards for admissible reports and papers. In short, they form a paradigm
of their own. New people are constantly recruited by this tribe through the
process of apprenticeship and junior partnership, or by adoption into this
tribe of brilliant outsiders with brand new ideas. Whatever is accomplished
by a member of this tribe will be shared with the rest of the members and
is by definition chemical reaction engineering.
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In this volume, we print the six plenary speeches given at the 7th Inter
national Symposium on Chemical Reaction Engineering at Boston. First,
the intellectual foundation of chemical reaction engineering is described by
Aris, and second, the study of alternative reactors for the methanol-to-
gasoline process is described by Penick. These two chapters form a powerful
contrast between the academic intellectual approach and the industrial
pragmatic approach. Fluidized beds are reviewed by Rowe, and fluidized-
bed combustors are reviewed by Sarofim. These two chapters are concerned
with one of the most powerful reactors, in which scale up by design engi
neers is still done with great trepidation, and one of its most important
future applications. If fluidized-bed combustors for coal are well engi
neered, there will be little demand for clean synthetic fuels, except for
liquid fuels for transportation. Combustion should have been one of the
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0 most central problems in reaction engineering. Only historical events decree
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6. that it should be a meeting ground of chemical engineers, mechanical engi
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0 neers, and chemists with their own Combustion Institute and highly suc
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98 cessful International Symposium series. It is overdue for us to build bridges
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k- to these outstanding people. Micromixing is reviewed by Villermaux, and
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1/ polymerization reactors are reviewed by Ray. These two chapters are con
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1 cerned with homogeneous phase and nearly homogeneous phase reactors
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d rather short sections on polymerization, a subject found more often in
83 | polymer textbooks. These reviews will go a long way toward remedying
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8, this defect.
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y The plenaries serve as a powerful centralizing force among reaction
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Dat rivulets and drying out. These plenaries should be read by all students of
on chemical reaction engineering, whatever their subspecialty. They augment
cati the basic textbooks as part of "what every educated reaction engineer
ubli should know."
P
JAMES WEI
Massachusetts Institute of Technology
Cambridge, MA
October 22, 1982
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Chemical Reaction Engineering as an Intellectual
Discipline
R. ARIS
University of Minnesota, Department of Chemical Engineering and Materials
Science, Minneapolis, MN 55455
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0 What, you are entitled to ask, do you mean by an intellectual
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ch discipline? Before attempting any formal answer, let me turn to
26. two of the traditional disciplines and try to sketch some of the
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3-0 characteristics that they may have or induce in their adepts.
8 I take my text from the advice given to President Gilman, the
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1/b classical scholar and the best mathematician that he could find.
02 The latter was none other than the great James Joseph Sylvester,
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0. retired from Woolwich since 1870 and spending his time in the
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d principles of his "Laws of Verse"—a pamphlet by which he set great
83 | store. With his appointment to Hopkins at the age of 62 there came
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1 the second flowering of his genius and with it his exploration of
28, the fundamental system of invariants and the syzygies of algebraic
uly forms.
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at studies at Cambridge had been interrupted by illness he took his
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ati Green. To say that he took his degree is not quite accurate, for
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Pu holding "the faith in which the founder of Christianity was
educated" to compete for the mathematical tripos, could not com
plete his degree without subscribing to the 39 Articles of the
Church of England—a subscription he was unwilling to make. He
therefore went to Trinity College, Dublin from which he received
his degrees in 1841. His Cambridge degree he did not receive
until 1872, when the religious barriers had at length been
removed. In 1890 he was given an honorary Sc.D. at the same time
as Benjamin Jowett, Henry Perry Liddon and other notables. The
Public Orator could, by then, bracket him with Newton as
"Sylvester noster" in the accolade: "Nonnulla quae Newtonus
noster, quae Fresnelius, Iacobius, Sturmius, alii, imperfecta
reliquerunt, Sylvester noster, aut elegantius explicavit aut
argumentis veris comprobavit." After two years at University
College, he crossed the Atlantic to the University of Virginia but
0097-6156/83/0226-0001$06.00/0
© 1983 American Chemical Society
