1、Advanced pHMeasurement and Control3rd EditionMcMillCam05.book Page i Thursday, September 16, 2004 4:05 PMMcMillCam05.book Page ii Thursday, September 16, 2004 4:05 PMAdvanced pHMeasurement andControl3rd EditionBy Gregory K. McMillanRobert A. CameronMcMillCam05.book Page iii Thursday, September 16, 2
2、004 4:05 PMNoticeThe information presented in this publication is for the general education of the reader. Because nei-ther the author nor the publisher have any control over the use of the information by the reader, both the author and the publisher disclaim any and all liability of any kind arisin
3、g out of such use. The reader is expected to exercise sound professional judgment in using any of the information presented in a particu-lar application.Additionally, neither the author nor the publisher have investigated or considered the affect of any patents on the ability of the reader to use an
4、y of the information in a particular application. The reader is responsible for reviewing any possible patents that may affect any particular use of the information pre-sented.Any references to commercial products in the work are cited as examples only. Neither the author nor the publisher endorse a
5、ny referenced commercial product. Any trademarks or tradenames referenced belong to the respective owner of the mark or name. Neither the author nor the publisher make any repre-sentation regarding the availability of any referenced commercial product at any time. The manufac-turers instructions on
6、use of any commercial product must be followed at all times, even if in conflict with the information in this publication.Copyright 2005 ISAThe Instrumentation, Systems, and Automation SocietyAll rights reserved. Printed in the United States of America. 109876543 2ISBN 1-55617-851-4 (hardback)No par
7、t of this work may be reproduced, stored in a retrieval system, or transmitted in any form orby any means, electronic, mechanical, photocopying, recording or otherwise, without the prior writ-ten permission of the publisher.ISA67 Alexander Drive, P.O. Box 12277Research Triangle Park, NC 27709www.isa
8、.orgLibrary of Congress Cataloging-in-Publication DataMcMillan, Gregory K., 1946-Advanced pH measurement and control.- 3rd ed. / by Gregory K.McMillan and Robert A. Cameron.p. cm.Includes index.Rev. ed. of:pH measurement and control. 2nd ed. c1994.ISBN 1-55617-851-4 (hardback)1. Hydrogen-ion concent
9、ration. 2. Chemical process control. I.Cameron, Robert A. II. McMillan, Gregory K., 1946- pH measurement andcontrol. III. Title. QD561.M46 2005541.3728-dc222004020236McMillCam05.book Page iv Thursday, September 16, 2004 4:05 PMvAcknowledgmentAt the core of this book is the original technology develo
10、ped by Vernon L. Trevathan on the use of titration curves and the importance of dead time for loop performance. The material presented is the culmination of many years of application experience of the authors in chemical and life science companies. The authors were also fortunate enough to get excel
11、lent technical reviews by Dave Mills of Chapter 4 and George Bentinck of the entire book. The improvements made based on their comments should help make this the best practical application guide for pH measurement and control in the process industry. Finally, the authors thank Terry Blevins, Jim Cah
12、ill, Brenda Forsythe, Mark Sowell, and Jim Sipowicz for the innovative cover concept and artwork.McMillCam05.book Page v Thursday, September 16, 2004 4:05 PMMcMillCam05.book Page vi Thursday, September 16, 2004 4:05 PMviiAbout the AuthorsGregory K. McMillan is a retired Senior Fellow from Solutia In
13、c. During his 33-year career with Monsanto Company and its spin-off Solutia Inc., he specialized in improving loop performance, controller tuning, valve dynamics, opportunity assessments, dynamic simulation, fermentor control, pH control, and reactor control. Greg is the author of numerous articles
14、and a dozen or so books, his most recent being the ISA best-seller for 2001 titled Good Tuning A Pocket Guide and the ISA best-seller for 2003 titled Advanced Control Unleashed. He has contributed to several handbooks, is the editor of the Process/Industrial Instrumentation and Controls handbook, an
15、d a columnist for Control magazine. He is one of InTechs 50 most influential industry innovators for advancing automation and control technologies. Greg is an ISA Fellow and received the ISA “Kermit Fischer Environmental” Award for pH control in 1991, the Control magazine “Engineer of the Year” Awar
16、d for the Process Industry in 1994, and was one of the first inductees into the Control magazine “Process Automation Hall of Fame” in 2001. He received a B.S. from Kansas University in 1969 in Engineering Physics and a M.S. from University of Missouri Rolla in 1976 in Electrical Engineering (Control
17、 Theory). Presently, Greg is a Professor at Washington University in Saint Louis, Missouri and is a consultant through EDP Contract Services in Austin, Texas.Robert A. Cameron is a process control engineer with 19 years of experience, working for Bailey Controls, Monsanto/Solutia, and GE Silicones.
18、His areas of interest and expertise are control system programming and optimization, instrumentation, and advanced control implementation. Bob is an ISA member and co-recipient of the 2001 R.N. Pond award (best ChemPID paper of the year) for the Expo2001 paper “Constrained Multivariable Predictive C
19、ontrol of Plastic Sheets.” He received a B.S. in Chemical Engineering from Clarkson University in 1985.McMillCam05.book Page vii Thursday, September 16, 2004 4:05 PMMcMillCam05.book Page viii Thursday, September 16, 2004 4:05 PMixTABLE OF CONTENTSAbout the Authors . . . . . . . . . . . . . . . . . .
20、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .viiPreface to the Third Edition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiChapter 1 The Essentials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21、. 31-1. The Heart of the Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31-2. Stage Fright . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101-3. Size Does Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22、 . . . . . . . . . 161-4. One Is the Loneliest Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191-5. Acceleration and Stagnation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241-6. Life Is a Batch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23、. . . . . . . . . . 281-7. Industrial Importance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 291-8. The Real Deal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30Chapter 2 The Chemistry . . . . . . . . . . . . . . . . . . . . . . .
24、 . . . . . . . . . . . . . . . . . . . 352-1. Nearly Normal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 352-2. Staying Active . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 402-3. Free Dissociation. . . . . . . . . . . .
25、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 422-4. A Question of Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Chapter 3 Titration Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553-1. Slippery Slopes . . . .
26、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 553-2. Laboratory Generation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 603-3. Computer Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 663-4. Field Generation
27、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 683-5. Buffering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 703-6. Uses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
28、. . . . 72Chapter 4 Electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 774-1. A Dose of Reality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 774-2. Measurement Electrodes . . . . . . . . . . . . . . . . . . . . .
29、. . . . . . . . . . . . . 944-3. Reference Electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1014-4. Application-Based Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1054-5. Smart Transmitters . . . . . . . . . . . . . . . . . . . . . . . . . .
30、 . . . . . . . . . . . . 1184-6. Failure Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1204-7. Dynamic Response of Electrodes, Holders, and SampleSystems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1214-8.
31、Installation Practices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1254-9. Calibration Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1334-10. Troubleshooting Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135C
32、hapter 5 Mixing Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1455-1. What Was Good Might Be Bad. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1455-2. Mixing Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1475-3.
33、Agitated Vessels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1495-4. Static Mixers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1605-5. Sumps, Ponds, and Lagoons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
34、62Chapter 6 Control Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1676-1. A Moving Story. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1676-2. Resolution Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . .
35、 . . . . 173McMillCam05.book Page ix Thursday, September 16, 2004 4:05 PMx Table of Contents6-3. Rangeability Requirement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1756-4. Split Ranging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1786-5.
36、 Special Strategies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180Chapter 7 Reagent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1877-1. Delivery Dilemmas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
37、. . . . . . . 1877-2. Dilution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1907-3. Buffering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1927-4. Dissolution. . . . . . . . . . . . . . . . . . . . . . .
38、. . . . . . . . . . . . . . . . . . . . . . 193Chapter 8 Control System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1998-1. Feedback Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1998-2. Feedforward Control . . . . . . . .
39、. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2008-3. Cascade Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2038-4. Linear Reagent Demand Control . . . . . . . . . . . . . . . . . . . . . . . . . . 2078-5. Adaptive Control . . . . . . . . . . . . .
40、 . . . . . . . . . . . . . . . . . . . . . . . . . . 2098-6. Advanced Batch Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2148-7. Dynamic Online pH Estimators . . . . . . . . . . . . . . . . . . . . . . . . . . . 2188-8. Model Predictive Control . . . . . . . . . . . . .
41、. . . . . . . . . . . . . . . . . . . 2208-9. Real-time Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2218-10. Controller Tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2228-11. Loop Performance . . . . . . . . . . . . . . . .
42、. . . . . . . . . . . . . . . . . . . . . . 2318-12. System Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236Appendix A Suggested Readings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243Appendix B Questions and Answers . . . . .
43、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247Appendix C Glossary of pH Control System Terminology . . . . . . . . . . . . . . 259Appendix D Review of Algebra with Logarithms . . . . . . . . . . . . . . . . . . . . . . 263Appendix E Control Talk Column Excerpts . . . . . . . . . . . .
44、. . . . . . . . . . . . . . . 267Appendix F FORTRAN Subroutine for Charge Balance Model . . . . . . . . . 275Appendix G Simplified Summary of Guidelines . . . . . . . . . . . . . . . . . . . . . . 279Appendix H Additional Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
45、283Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285McMillCam05.book Page x Thursday, September 16, 2004 4:05 PMxiPreface to the Third EditionThe pH electrode offers by far the greatest sensitivity and rangeab
46、ility of any industrial process measurement. To realize the full potential of this opportunity requires extraordinary performance of mixing equipment, control valves, reagent delivery systems, flow meters, control system design, and controller tuning. This book is designed to cover all of the bases
47、but not get the user lost in the details. Since each of these topics could be a book in itself, the emphasis here is on cutting straight to the chase of concepts critical for a successful pH system. Key insights and rules of thumb are inserted to congeal principles and practices that address the ess
48、ential requirements of pH applications. The book should appeal to both the generalist and the specialist. This book is designed to bring together the chemist, control engineer, instrument technician, process engineer, and project manager to literally and figuratively put them on the same page.Chapte
49、r 1 The Essentials provides a concise overview of what makes pH applications unique. It covers the total system requirements and is designed for the widest possible audience. It uses an adventurous style and analogies that should help make this chapter interesting enough to read from start to finish. The other chapters follow up on the seeds planted here and are intended to be used more as a reference for the design of each part of a pH measurement and control system.Chapter 2 The Chemistry gets into the engineering units and the conversion of the abscissa of the titration curv
