PROCESS CONTROL DESIGNING PROCESSES AND CONTROL SYSTEMS FOR DYNAMIC PERFORMANCE
McGraw-Hill Chemical Engineering Series
Editorial Advisory Board Eduardo D. Glandt, Professor of ChemicalEngineering, University ofPennsylvania
Michael T. Klein, Professor of Chemical Engineering, Rutgers University Thomas F. Edgar,Professor of Chemical Engineering, University of Texas at Austin
Bailey and Ollis: Biochemical Engineering Fundamentals Bennett and Myers: Momentum, Heat andMass Transfer Carberry: Chemical and Catalytic Reaction Engineering Coughanown Process Systems Analysis andControl de Nevers: Air Pollution Control Engineering
de Nevers: Fluid Mechanicsfor ChemicalEngineers
Douglas: Conceptual Design of Chemical Processes
Edgar andHimmelblau: Optimization of Chemical Process Gates, Katzer, and Schuit: Chemistry ofCatalytic Processes
Gupta and Kumar: Fundamentals of Polymers King: Separation Processes
Luyben: Essentials of Process Control
Luyben: Process Modeling, Simulation, and Controlfor Chemical Engineers Marlin: Process Control: Designing Processes and Control Systemsfor DynamicPerformance
Middleman and Hochberg: Process Engineering Analysis inSemiconductor Device Fabrication
Perry andGreen: Perry's Chemical Engineers'Handbook Peters and Tlmmerhaus: PlantDesign andEconomicsfor Chemical Engineers Reid, Prausnitz, and Poling: Properties ofGasses andLiquids Smith,Van Ness, and Abbott: Introduction to Chemical Engineering Thermodynamics
Treybal: Mass Transfer Operations Wentz: Hazardous Waste Management
PROCESS CONTROL DESIGNING PROCESSES AND CONTROL SYSTEMS FOR DYNAMIC PERFORMANCE
2nd Edition
Thomas E. Marlin McMaster University
Boston Burr Ridge, IL Dubuque, IA Madison, Wl New York San Francisco St. Louis Bangkok Bogota Caracas Lisbon London
Madrid
Mexico City Milan New Delhi Seoul Singapore Sydney Taipei Toronto
McGraw-Hill Higher Education ADivision ofTheMcGnav-HtUCompanies
PROCESS CONTROL
DESIGNING PROCESSES ANDCONTROL SYSTEMS FORDYNAMIC PERFORMANCE International Editions 2000
Exclusive rights byMcGraw-Hill Book Co - Singapore, for manufiicture and export This book cannot be re-exported from the country to which it is sold by McGraw-Hill. The International Edition is not available in North America.
Copyright ©2000,1995 by The McGraw-Hill Companies, Inc. All rights reserved. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form orby any means, orstored in a data base orretrieval system, without the prior written permissionof the publisher.
Some ancillaries, including electronic and print components, may not be available to customers outside the United States.
10 09 08 07 06 05 04 03 02 20 09 08 07 06 05 04 03 02 01 PMP
BJE
ISBN 0-07-039362-1
Library of CongressCataloging-in-Publication Data Marlin, Thomas E.
Process control: designing processes and control systems fordynamic performance / Thomas E. Marlin. -2nd ed. p.
cm.
Includes index. ISBN 0-07-039362-1
1. Chemical process control. TP155.75.M365
I. Title.
2000
660\2815-dc21
When ordering this title, use ISBN 0-07-116357-3 Printed in Singapore
99-026739
About the Author Thomas E. Marlin is a professor of Chemical Engineering at McMasterUniversity in Hamilton, Ontario, Canada, where he held the NSERC Industrial Research Chair
in Process Control. He received his Ph.D.. from the University of Massachusetts in 1972. Then, he worked in industry for 15 years where he applied simulation and control to a wide range of continuous process in the chemical and petroleum industries. In 1987, he served as the Visiting Fellow in Sydney, Australia, for the Warren Centre Study on benefits from process control. A team of 40 engineers investigated 7 case studies while refining methods for quantifying benefits from automation. Dr. Marlin is currently Director of the McMaster Advanced Control Consortium, which is a collaboration between university researchers and numer ous companies, resulting in leading research that is focused on challenges of great relevanceto industrial practitioners. He teaches university courses in process con
trol,process analysis, problemsolving, and processdesign. Inaddition, he presents industrial short courses on process control, benefitsestimation, and optimization. Dr. Marlin's research interests include real-time optimization and processcontrol design.
Preface Automation via feedback is not new. Early application of automatic control prin ciples appeared in antiquity, and widespread use of automation began in the nine teenth century when machinery was becoming the dominant method for manu facturing goods. Great advances have been made in theory and practice so that automation is now used in systems as commonplaceas room heatingand as excit ing as the navigation of interplanetary exploration and telecommunications. The great change over the recent years is the integral—at times essential—role of au tomation in our daily lives and industrial systems. Process control is a sub-discipline of automatic control that involves tailoring methods for the efficient operation of chemical processes. Proper application of process control can improve the safety and profitability of a process, while main taining consistently high product quality. The automation of selected functions has relieved plant personal of tedious, routine tasks, providing them withtime and
data to monitor andsupervise operations. Essentially every chemical engineer de signing or operating plants is involved with and requires a background in process control. This book provides an introduction to process control with emphasis on topics that are of useto the general chemical engineer as well as the specialist. GOALS OF THE BOOK
The intent of this book is to present fundamental principles with clear ties to applications and with guidelines on their reduction to practice. The presentation is based on four basic tenets.
vn
viii Preface
Fundamentals
First,engineers should master control technology fundamentals, since there is no set of heuristics or guidelines that can serve them through their careers. Since these fundamentals must be presented with rigor, needed mathematical tools are presentedto assistthe student. It maybe worthrecallingthat these principles were selected because they provide the simplest approaches for solving meaningful problems. Practice
Second, we are not efficient if we "start from scratch" every time we encounter a problem; similar situationscan be analyzed to develop guidelines for a defined set of applications. Also, the fundamental concepts can be best reinforced and
enriched through the presentation of good engineering practice. With this per spective, important design guidelines and enhancements are presented as logical conclusions and extensions to the basic principles. Coverage of implementation issuesincludes pitfalls with thestraightforward "textbook" approaches alongwith modifications for practical application. Complexity
Third, the presentation in this book follows the guideline"Everythingshould be made as simple as possible, and no simpler." Naturally, many issues are easily resolved using straightforward analysismethods. However, the engineer must un derstand the complexity of automating a system, even when a closed-form solution does not exist at the present time. Design
Fourth, designis a capstone topic thatenables engineers to specify, buildandoper ate equipment that satisfiespredeterminedgoals. Currently, closed-form solutions do not exist for this activity; thus, a comprehensive design method for managing the numerous interlocking designtasks is presented along with a step-by-step ap proach to guide the engineer through problem definition, preliminary analysis of degreesof freedomandcontrollability, andselectingprocessand control structures. Many guidelines,checklists,and examplesaid the student in making well-directed initial decisions and refining themthrough iterations to achievethe design goals. THE READERS
Hopefully, readers with different backgrounds will find value in this treatment of
process control. A few comments are now addressed to the three categories of likely readers of this book: university students, instructors, and practitioners. Students
Many students find process control to be one of the most interesting and enjoyable courses in the curriculum, because they apply the skills built in fluid mechanics,
heat transfer, thermodynamics, masstransfer, andreactordesign.This presentation
