APPLIED TECHNOLOGY AND INSTRUMENTATION FOR PROCESS CONTROL APPLIED TECHNOLOGY AND INSTRUMENTATION FOR PROCESS CONTROL Douglas O.J.deSá TAYLOR & FRANCIS NEW YORK AND LONDON Denise T.Schanck, Vice President Robert L.Rogers, Senior Editor Liliana Segura, Editorial Assistant Savita Poornam, Marketing Manager Randy Harinandan, Marketing Assistant Dennis P.Teston, Production Director Anthony Mancini Jr., Production Manager Brandy Mui, STM Production Editor Mark Lerner, Art Director Daniel Sierra, Cover Designer Published in 2004 by Taylor & Francis 29 West 35th Street New York, NY 10001 www.taylorandfrancis.com This edition published in the Taylor & Francis e-Library, 2005. To purchase your own copy of this or any of Taylor & Francis or Routledge’s collection of thousands of eBooks please go to www.eBookstore.tandf.co.uk. Published in Great Britain by Taylor & Francis 11 New Fetter Lane London EC4P 4EE www.taylorandfrancis.co.uk Copyright © 2004 by Taylor & Francis Books, Inc. All rights reserved. No part of this book may be reprinted or reproduced or utilized in any form or by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publisher. 10 9 8 7 6 5 4 3 2 1 Library of Congress Cataloging-in-Publication Data deSá, Douglas O.J. Applied technology and instrumentation for process control/by Douglas O.J.deSá. p. cm. Includes bibliographical references and index. ISBN 1-59169-021-8 1. Engineering instruments. 2. Process control—Instruments. I. Title. TA165.D46 2003 670.42′75–dc22 2003049339 ISBN 0-203-49087-8 Master e-book ISBN ISBN 0-203-59495-9 (Adobe eReader Format) ISBN 1-59169-021-8 (Print Edition) Contents PREFACE viii INTRODUCTION ix NOTATION USED IN THIS BOOK xi INSTRUMENTATION SYMBOLS USED IN THIS BOOK xiv TAG NUMBER SYSTEM USED IN THIS BOOK xvi CHAPTER 1 APPLICABILITY OF MISCELLANEOUS CONTROL 1 STRATEGIES—INDUSTRYWIDE CHAPTER 2 DIGESTERS—PAPER PULP 38 CHAPTER 3 PAPER MACHINE 92 CHAPTER 4 EVAPORATORS 162 CHAPTER 5 PRODUCT DISTILLATION 205 CHAPTER 6 PRODUCT BLENDING 289 CHAPTER 7 THE BREWING INDUSTRY 332 CHAPTER 8 PROJECT MANAGEMENT AND ADMINISTRATION 379 BIBLIOGRAPHY 407 INDEX 409 Preface This work is an extension to the earlier publication Instrumentation Fundamentals for Process Control (2001) in which the basics of instrumentation were given along with some applications of instruments and control systems to real processes. Because the present work is an extension of this latter aspect, it is therefore confined mainly to the techniques of applying instrumentation and control systems to manipulate the process to give the desired results. The topics covered in this book will expose the reader to even more actual requirements that are to be found in real process plants, as well as to some of the methods used as solutions to control them. Many complex industrial applications have several common elements. Therefore, the similarity in operation of parts of the process can allow the control philosophy developed for the control loops involved in the common elements to be applied across several different industries. The reader is encouraged to look for and exploit, where possible, this feature to advantage. As mentioned earlier, much of the instrumentation used in the systems presently discussed have been previously covered in Instrumentation Fundamentals for Process Control (2001). The present text, however, has not assumed any prior knowledge, and as far as possible, steps have been taken to make this book self-sufficient. Once again I am indebted to many of my former colleagues in the Foxboro Company, especially M.J.Cooper for his constant encouragement and cooperation, J.F. Whiting, E.A.Wright, Professor G.W.Skates, and to many other friends for their useful comments to enrich this work. I owe a particular debt of gratitude to D.R. Beeton, a personal friend and former colleague for his forbearance, patience, long hours of work, and invaluable comments in his review of this text. My patient wife Halina, also, once again deserves special mention for the warmth of her encouragement and her equanimity in tolerating the many long hours I have had to spend away from her company while this book was being prepared. Doug deSá October 2003 Introduction The objective of this book is not to cover only a few selected industries. Rather it is one which, via the industries covered, shows that most of the techniques are applicable (perhaps with some modification) to many diverse industries. The things we use every day are made by a variety of processes using raw materials that in many instances do not bear any resemblance to the finished product. For example, the clothes we wear do not resemble the cotton or the wool from which they were made. The difference is even more striking if the clothes were manufactured from synthetic fibers. There is very little, if any similarity between the nylon stockings or the acrylic sweater and the crude oil from which they were produced. Even the food we eat is the subject of processing of one kind or another. This book seeks to give the reader an insight into a number of different manufacturing processes. There are far too many processes to even contemplate covering more than a small number of process industries—but many of the topics covered are universally applicable to a much wider range of industrial plant. The examples covered represent a convenient way of giving the reader insight into how basic loops are configured and made to “hang together” to produce the control techniques (sub-applications) that can tie into the real-world overall plant philosophy Solutions are seldom written on “tablets of stone,” for specific plant requirements will in almost all cases dictate a course of action that takes into account the prevailing circumstances. The control systems discussed represent one way that has been found to make the process manageable and able to consistently produce the product required. In order to concentrate on the regulatory control aspects for the control systems illustrated in the book, parameters that need to be recorded (i.e., a chart record to be made, and/or indicated or alarmed) have very largely not been included. These additional features, important as they are in any system, can always be added to the appropriate loop(s) quite easily when required, but only after their use and position within the control system have been discussed, defined, and agreed to with the process personnel involved. Therefore, the challenge to the readership is to provide other solutions that are even subtler, more advantageous, and simpler when applied to the process, but most important, the solutions offered should be easily understood by all concerned. To do this effectively, the underlying principles of the process must be understood. The objective of giving a reasonably clear understanding of these process principles and the controls without demanding that the readers have tremendous familiarity with heavy math or the intricacies of physics and chemistry has been another motivation for the work. Let it be said up front, however, that on occasion readers, in the course of their work, will be called upon to give a theoretical explanation of their design. In this case, one would be compelled to make use of the knowledge gained in the hallowed halls of academia. Therefore, the advice to the reader now, as it has been in the past, is not to ignore the theoretical approach to control engineering.