Essentials of Process Control McGraw-Hill Chemical Engineering Series Editorial Advisory Board James J. Cat-berry, Pro~ssor of Cltc~tttiutl Ett,qitwcrittg, iJttil~cr.si!\~ of No,rc I~rrttw James R. Fair, Professor of Cltctttical Engitwcrittg, Univcrsi~y of l?.w.s, Austitt Eduardo D. Glandt, Prof~~ssor ~~/‘Cltcmitul Ettgittwrittg, Utriv~r.si!\~ (?f Pottt.s~~I~Vtttitr Michael T. Klein, Prof~~ssot- o~‘Chcttric~tl Ettgirtwrittg, Utti\~c~rsity of’l~c~lttwtrc Matthew Tirrell, Profc~s.sor of Chcttticai Ettgitrwrittg, Utti\rt sity of‘Mitmc.sortr Emeritus Advisory Board Max S. Peters, Retired Professor of Chemical Engineerittg, Univer.sity of Colorado William P. Schowalter, Dean, School of Engineering, University of 1Ilinoi.s James Wei, Dean, School (?f’Engineering, Prittceton University . Building the Literature of a Profession Fifteen prominent chemical engineers first met in New York more than 60 years ago to plan a continuing literature for their rapidly growing profession. From industry came such pioneer practitioners as Leo H. Baekeland, Arthur D. Little, Charles L. Reese, John V. N. Dorr, M. C. Whitaker, and R. S. McBride. From the universities came such eminent educatdrs as William H. Walker, Alfred H. White, D. D. Jackson, J. H. James, Warren K. Lewis, and Harry A. Curtis. H. C. Parmelee, then editor of Chemical and Metallurgical Engineering, served as chairman and was joined subsequently by S. D. Kirkpatrick as consulting editor. After several meetings, this committee submitted its report to the McGraw-Hill Book Company in September 1925. In the report were detailed specifications for a correlated series of more than a dozen texts and reference books which have since become the McGraw-Hill Series in Chemical Engineering and which became the cornerstone of the chemical engineering curriculum. From this beginning there has evolved a series of texts surpassing by far the scope and longevity envisioned by the founding Editorial Board. The McGraw-Hill Series in Chemical Engineering stands as a unique historical record of the devel- opment of chemical engineering education and practice. In the series one finds the milestones of the subject’s evolution: industrial chemistry, stoichiometry, unit oper- ations and processes, thermodynamics, kinetics, and transfer operations. Chemical engineering is a dynamic profession, and its literature continues to evolve. McGraw-Hill, with its editor B. J. Clark and its consulting editors, remains committed to a publishing policy that will serve, and indeed lead,. the needs of the chemical engineering profession during the years to come. . ‘P ;try i L. ties ;on, litor ned .Hill for a ;ince 2 the ir the I-Hill ievel- Is the oper- ues to :mains of the The Series Bailey and Oiiis: Biochcnlicul Ertgiwcrirrg l;rtrrtltrrilcrltlrls Bennett and Myers: Momentum, Heat, and Mass Transfer Brodkey and Hershey: Transport Phenomena: A Un$ed Approach Carberry: Chemical and Cutulytic Reaction Engineering Constantinides: Applied Numerical Methods with Personal Computers Coughanowr: Process Systems Analysis and Control de Nevers: Air Pollution Control Engineering de Nevers: Fluid Mechanics for Chemical Engineers Douglas: Conceptual Design of Chemical Processes Edgar and Himmelblau: Optimization of Chemical Processes Gates, Katzer, and Schuit: Chemistry of Catalytic Processes Holland: Fundamentals of Multicomponent Distillation Katz and Lee: Natural Gas Engineering: Production and Storage King: Separation Processes Lee: Fundamentals of Microelectronics Processing Luyben: Process Modeling, Simulation, and Control for Chemical Engineers Luyben and Luyben: Essentials of Process Control McCabe, Smith, and Harriott: Unit Operations of Chemical Engineering Marlin: Process Control: Designing Processes and Control Systems .for Dynamic Pe$ormance Middlemann and Hochberg: Process Engineering Analysis in Semiconductor Device Fabrication Perry and Chilton (Editors): Perry S Chemical Engineers’ Handbook Peters: Elementary Chemical Engineering Peters and Timmerhaus: Plant Design and Economics for Chemical Engineers Reid, Prausnitz, and Poling: Properties of Gases and Liquids Smith: Chemical Engineering Kinetics Smith and Van Ness: Introduction to Chemical Engineering Thermodynamics Treybal: Mass Transfer Operations Valle-Reistra: Project Evaluation in the Chemical Process Industries Wentz: Hazardous Waste Management [...]... Preface 1 1 Introduction 1. 1 1. 2 2 Examples of Process Dynamics and Control Some Important Simulation Results 6 1. 2 .1 Proportional and Proportional-Integral Level Control / 1. 2.2 ,Temperature Control of a Three-Tank Process 1. 3 1. 4 General Concepts and Terminology Laws, Languages, and Levels of Process Control 1. 4 .1 Process Control Laws / 1. 4.2 Languages qf Process Control / 1. 4.3 Levels of Process Control. .. / 11 .3.3 I-‘rol’ortiorltrl-Intc~Srcrl-Deri~)ative Controller (PlD) 3 01 I I 4 Examples 397 11 .4 I Three-CSTR Process / 11 .4.2 First-Order Ltrg with Deudtime / 11 .4.3 Ol’enloop-Unstcrhlc Processes 3 01 308 11 .5 11 .6 Use of MATLAB for Frequency Response Plots Capacity-Based Method for Quantifying Controllability 11 .7 Conclusion Problems 316 3 31 3 31 V 11 .2 I I’Iimt~ Mtrrgirr / 11 .2.2 Goin Margin / ! 1. 2.-j... Condenser 5.3 Simple Quantitative Example 99 99 11 7 11 7 11 8 12 0 12 2 12 5 12 6 12 8 12 9 13 5 13 5 1. 51 1 51 152 15 3 5.3 .1 Steady-State Design / 5.3.2 Dynamic Controllability / 5.3.3 Maximum Heat Removal Rate Criterion 5.4 Impact of Controllability on Capital Investment and Yield 5.4 .1 Single-Reaction Case / 5.4.2 Consecutive Reactions Case 5.5 5.6 General Trade-off between Controllability and Thermodynamic Reversibility... a, 2 ? I 11 ; 60 80 I I 10 0 12 0 Time (min) I 14 0 16 0 I 18 0 200 PI Level Control, Reset=& Kc=0. 314 12 1 3z 40 I I I ! I I I I I ~ ;~ “ , : ~ .~ .~ 1~ ,. ,_; 10 :‘ ! H; j ‘; ; ‘ _ : \ : , ,;;-i.j i i g t j ‘.\i '1, j i '.I;.: t :./ : t ! 81 0 E 12 0 E y& 1 1 5 t i 40 ; 60 i ‘80 I 12 5 i 20 ! I I i i 10 0 12 0 Time (min) ! I i 16 0 i 18 0 I I I : /: 1: r.~.x... Functions / 14 .4.3 Effect of Deadtime / 14 .4.4 z Transform Theorems / 14 .4.5 Inversion 14 .5 14 .6 14 .7 14 .8 14 .9 496 498 499 509 5 1 1 511 Pulse Transfer Functions Hold Devices Openloop and Closedloop Systems Stability in the z Plane Conclusion Problems 15 Stability Analysis of Sampled-Data Systems 513 513 5 21 15 .1 Root Locus Design Methods 15 .2 Frequency-Domain Design Techniques 15 .2 .1 Nyquist Stabiliry... Decoupling 12 .4 Conclusion Problems 452 452 360 13 Design of Controllers for Multivariable Processes 13 .1 Problem Definition 13 .2 Selection of Controlled Variables 369 370 456 457 13 .2 .1 Engineering Judgment / 13 .2.2 Singular Wue Decomposition 13 .3 Selection of Manipulated Variables 13 .4 Elimination of Poor Pairings 13 .5 BLT Tuning 13 .6 Load Rejection Performance 372 372 h 456 459 460 4 61 466 xvi (‘0N’I‘l;Nl’S... Response 10 .5 Conclusion Problems 11 Frequency-Domain Analysis of Closedloop Systems I 1. 1 Nyquist Stability Criterion 11 .1 I Proof / 11 I.? tk~mples / Il 1. 3 Representation 369 370 372 372 (‘ON’I‘I’N’l‘S I I 2 276 Closedloop Spccilications in the Frequency Domain I I 3 386 Frequency Response of Feedback Controllers 395 11 .3 I t’roporiionc~l Cor~troller (I’) / 11 .3.2 I’rop~~rtioncil-Intcsrul Controller... 10 .8 16 0 I2 _, .; ; :_ : : i 18 0 200 .: .:i 10 i 0 20 40 60 80 10 0 12 0 Time (min) I I I 14 0 16 0 18 0 200 I I I I I I I I i i .i i i i .i i ._ ; ; ; ; ; ; ; ; ; .; .: .; .; .; ; .; ._ ; ; ; ; ; 1 f ~ , i : ~ , : .: ~ .ii I::::::::! : : z 10 2 -I I j f i .: : : .: ~ I;:::::::: I I 1 I I I I 1 I 10 01 * 0 20 40 60 80 10 0 12 0 14 0 16 0 18 0... 308 316 323 326 9.5 .1 Direct Synthesis / 9.5.2 Internal Model Control 9.6 Conclusion Problkms P A R T 3 3 31 3 31 Frequency-Domain Dynamics and Control 10 Frequency-Domain Dynamics 10 .1 Definition 10 .2 Basic Theorem 10 .3 Representation 339 339 3 41 344 10 .3 .1 Nyquist Plots / 10 .3.2 Bode Plots / 10 .3.3 Nichols Plots 10 .4 Computer Plotting 360 10 .4 .1 FORTRAN Programs for Plotting Frequency Response / 10 .4.2... Criterion / 15 .2.2 Rigorous Method / 15 .2.3 Approximate Method / 15 .2.4 Use of MATLAB 528 529 535 535 15 .3 Physical Realizability 15 .4 Minimal-Prototype Design 15 .5 Conclusion Problems P A R T 6 Identification 16 Process Identification 545 16 .1 Fundamental Concepts 16 .1 I Controol-Relevant Content 546 Identification / 16 .1. 2 Frequency of tlw Innut Civnnl / Ifi I 1 Mml~l Order (3 )N~l‘I’Nl‘S 4 71 472 472 16 .2 . Systems 02 99 99 1. 51 1 51 152 15 3 16 5 92 99 99 17 17 18 20 22 25 .26 .28 ,29 13 5 13 5 15 1 15 1 15 2 15 3 16 5 17 4 17 5 18 2 18 3 18 3 18 4 ,18 5 Ii (‘ON’l’l;.NTS ‘. XIII 6.4 llsc of Steady-State Sensitivity Analysis to Screen Plantwide Control Structures 19 0 6.4. I Control StrircYurt~s . Control 6 .1 Series Cascades of Units 6.2 Effect of Recycle on Time Constants 6.3 Snowball Effects in Recycle Systems 02 99 99 1. 51 1 51 152 15 3 16 5 92 99 99 17 17 18 20 22 25 .26 .28 ,29 13 5 13 5 15 1 15 1 15 2 15 3 16 5 17 4 17 5 18 2 18 3 18 3 18 4 ,18 5 Ii (‘ON’l’l;.NTS. Conclusions Problems 4 Advanced Control Systems 11 7 4 .1 Ratio Control 11 7 4.2 Cascade Control 11 8 4.3 Computed Variable Control 12 0 4.4 Override Control 12 2 4.5 Nonlinear and Adaptive Control 12 5 4.6 Valve Position