Chemical Engineering Design and Analysis Students taking their first chemical engineering course plunge into the "nuts and bolts" of mass and energy balances and often miss the broad view of what chemical engineers do. This innovative text offers a well-paced introduction to chemical engineering. Through a series of real-world examples and exten- sive exercises, students learn the basic engineering concepts of design and analysis. The text has two main objectives: • To have students practice engineering. Students are introduced to the fundamental steps in design and three methods of analysis: mathemati- cal modeling, graphical methods, and dimensional analysis. In addition, students apply engineering skills, such as how to simplify calculations through assumptions and approximations, how to verify calculations, determine significant figures, use spreadsheets, prepare graphs (stan- dard, semilog, and log-log), and use data maps. • To introduce the chemical engineering profession. Students learn about chemical engineering by designing and analyzing chemical processes and process units to assess product quality, economics, safety, and en- vironmental impact. This text will help undergraduate chemical engineering students develop engineering skills early in their studies and encourage an informed decision about whether to pursue this profession. Students in related fields such as chemistry, biology, materials science, and mechanical engineering can use this book to learn the underlying principles of chemical processes and their far-reaching applications. T. Michael Duncan is an associate professor of chemical engineering at Cor- nell University and Associate Director of the undergraduate program in the School of Chemical Engineering. Jeffrey A. Reimer is a professor of chemical engineering at the University of California at Berkeley and faculty scientist at the E. O. Lawrence Berkeley National Laboratory. CAMBRIDGE SERIES IN CHEMICAL ENGINEERING Series Editor: Arvind Varma, University of Notre Dame Editorial Board: Alexis T. Bell, University of California, Berkeley John Bridgwater, University of Cambridge L. Gary Leal, University of California, Santa Barbara Massimo Morbidelli, ETH, Zurich Stanley I. Sandier, University of Delaware Michael L. Schuler, Cornell University Arthur W. Westerberg, Carnegie-Mellon University Books in the Series: E. L. Cussler, Diffusion: Mass Transfer in Fluid Systems, second edition T. Michael Duncan and Jeffrey A. Reimer, Chemical Engineering Design and Analysis Liang-Shih Fan and Chao Zhu, Principles of Gas-Solid Flows Hasan Orbey and Stanley I. Sandier, Modeling Vapor-Liquid Equilibria: Cubic Equations of State and Their Mixing Rules Chemical Engineering Design and Analysis An Introduction T. Michael Duncan and Jeffrey A. Reimer CAMBRIDGE UNIVERSITY PRESS CAMBRIDGE university press Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo, Delhi, Tokyo, Mexico City Cambridge University Press 32 Avenue of the Americas, New York, ny 10013-2473, usa www.cambridge.org Information on this title: www.cambridge.org/9780521639569 © Cambridge University Press 1998 This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 1998 10th printing 2011 A catalog record for this publication is available from the British Library. Library of Congress Cataloging in Publication Data Duncan, T. Michael. Chemical engineering design and analysis : an introduction / T. Michael Duncan, Jeffrey A. Reimer. p. cm. - (Cambridge series in chemical engineering) Includes bibliographical references and index. ISBN 0-521-63041-x (hb). - isbn 0-521-63956-5 (pb) I. Chemical engineering. I. Reimer, Jeffrey A. (Jeffrey Allen). II. Title. III. Series. tp155.d74 1998 98-16452 66o'.2-dc2i CIP ISBN 978-0-521-63956-9 Paperback Cambridge University Press has no responsibility for the persistence or accuracy of urls for external or third- party Internet Web sites referred to in this publication and does not guarantee that any content on such Web sites is, or will remain, accurate or appropriate. To my son, Maxwell T. Michael Duncan To Karen, Jennifer, Jonathan, Charlotte, and Martin Jeffrey A. Reimer Contents Preface page xi Acknowledgments xiii 1 An Overview of Chemical Engineering 1 I. I Chemical Engineering 1 1.2 Summary 6 REFERENCES 6 2 Process Design 7 2.1 The Synthesis of Ammonia 7 2.2 Unit Operations and Flowsheets 16 2.3 Purifying Heptane-Creative Problem Solving 18 2.4 Flowsheet Conventions 24 2.5 The Production of Electronic-Grade Silicon 25 2.6 Generating Electrical Power with Fuel Cells 29 2.7 Desulfurization of Natural Gas-Absorbers and Adsorbers 33 2.8 Summary 37 REFERENCES 37 EXERCISES 38 Process Analysis 38 Process Design 41 Problem Redefinition 56 3 Models Derived from Laws and Mathematical Analysis 61 3.1 Desalination of Seawater 62 VII Contents 3.2 The Conversation Principles 63 3.3 Modeling a Desalinator 65 3.4 A Better Desalinator 68 3.5 An Even Better Desalinator 75 3.6 Design Tools from Mathematical Modeling 77 3.7 The Freezer Desalinator-Analysis of the Energy Flow 78 3.8 Cocurrent and Countercurrent Devices 84 3.9 Energy Balance in a Heat Exchanger 86 3.10 Heat Pumps 88 3.1 1 Refrigeration Cycle in the Desalinator 88 3.12 Refrigeration Cycles without Refrigerants 92 3.13 Mathematical Modeling-Universal and Constrained Laws 94 3.14 Process Economics 95 3.15 Summary 106 REFERENCES 106 EXERCISES 107 Mass Balances 107 Mass Balances on Spreadsheets 120 Energy Balances 126 Process Economics 132 Engineering Calculations 137 Graphical Analysis 139 4.1 Air Pollution 141 4.2 Separation by Condensation 141 4.3 Maps 143 4.4 Condensation of Benzene from Air 146 4.5 Separation by Absorption 154 4.6 Design Tools from Graphical Analysis 166 4.7 Distillation-Flash Drums 167 4.8 Distillation Columns 180 4.9 Summary 185 REFERENCES 186 VIII Contents EXERCISES 186 Phase Diagrams 187 Absorbers and Strippers 192 Flash Drums, Tie Lines, and the Lever Rule 202 Distillation Columns 207 Process Design 216 Dimensional Analysis and Dynamic Scaling 236 5.1 Units and Dimensions 239 5.2 Dimensional Analysis of a Pendulum 242 5.3 Dimensional Analysis of Walking 245 5.4 Dimensional Analysis of a Solid Sphere Moving through a Fluid 252 5.5 Design Tools from Dimensional Analysis 264 5.6 Dynamic Scaling-The Alaskan Pipeline 265 5.7 Flow through a Pipe 271 5.8 Heat Transfer from a Fluid Flowing in a Tube 273 5.9 Absorbers and Distillation Columns 276 5.10 The Compressibility of a Gas 281 5.1 I Summary 286 REFERENCES 286 EXERCISES 287 Units and Dimensions 287 Deriving Dimensionless Groups 288 Analyzing Graphical Data 290 Dynamic Scaling 294 Data Analysis on Spreadsheets 296 Transient Processes 310 6.1 The Basics-A Surge Tank 311 6.2 Residence Times and Sewage Treatment 320 6.3 Rate Constants-Modeling Atmospheric Chemistry 325 6.4 Optimization-Batch Reactors 330 6.5 Continuous Production - Plug Flow Reactors 336 6.6 Multiple Steady States-Catalytic Converters 338 IX Contents REFERENCES 342 EXERCISES 342 Numerical Integration of Differential Equations 346 Appendix A. List of Symbols 351 Appendix B. Units, Conversion Factors, and Physical Constants 353 Appendix C. Significant Figures 356 Appendix D. Graph Paper 359 Appendix E. Mathematics, Mechanics, and Thermodynamics 365 Appendix F. Glossary of Chemical Engineering 368 Index 375