Introduction to. Process Control. Ahmet Palazoglu. Second Edition. Jose A. Romagnoli. CRC Press. Taylor & Francis Group. Taylor & Francis Group,

Transcription

1 Introduction to Process Control Second Edition Jose A. Romagnoli Ahmet Palazoglu CRC Press Taylor & Francis Group Boca Raton London NewYork CRC Press is an imprint of the Taylor & Francis Group, an informa business

2 Contents Preface Authors Introduction -xix xxiii xxv PART I Introduction Chapter 1 Why Process Control? Historical Background Role of Control in Process Industries Traditional Role of Process Control Expanded Role of Process Control Objectives of Control What about Performance? Economic Benefits of Control Summary 11 Continuing Problem 11 Solution 12 References 12 _ Chapter 2 Definitions and Terminology Concepts and Definitions Control Design Problem Control System Design Control Design Project Preliminary Engineering Detailed Engineering Implementation Installation Commissioning First Production Start-Up and Turnover Training Summary 27 Continuing Problem 27 Solution 27 Reference 28 ix

3 x Contents Part I Summary 29 Additional Reading 29 Exercises 30 References 39 PART II Modeling for Control Chapter 3 Basic Concepts in Modeling Why Is Process Modeling Necessary? Application Areas and Benefits Goal of Modeling Classification of Models Linear versus Nonlinear Distributed Parameter versus Lumped Parameter Deterministic versus Stochastic Types of Models Models Based on Source of Information Models Based on Mathematical Representation State-Space Models Input-Output Models Degrees of Freedom Models and Control Summary 57 References 57 Chapter 4 Development of Models from Fundamental Laws Principles of Modeling Models Based on Fundamental Laws Constitutive Relations Steady-State Condition Modeling of Processes Involving Chemical Reactions Modeling of Complex Systems Distributed Parameter Systems Numerical Solution of Model Equations Summary 81 Continuing Problem 81 Solution 81 References 84 Chapter 5 Input-Output Models Linear (Linearized) Model Deviation Variables 86

4 Contents Xl Higher Dimensional Equations Linear State-Space Model Concept of Transfer Function Transfer Functions of Single-Input Single-Output Processes Asymptotic Theorems Initial Value Theorem Final Value Theorem Properties of Transfer Functions Nonrational Transfer Functions Summary 102 Continuing Problem 103 Solution 103 Chapter 6 Models from Process Data Development of Empirical Models Steps in Developing Empirical Models Performing the Experiments Building the Model Evaluating the Model Model Structures Process Reaction Curve Method Ill 6.4 Regression in Modeling Linear Regression Nonlinear Regression Summary 124 Continuing Problem 124 References 126 Part II Summary 127 Additional Reading 127 Exercises 128 References 140 PART III Process Analysis Chapter 7 Stability Stability of Linear Systems Input-Output Stability Routh's Criterion Root-Locus Method 152

5 xjj Contents 7.5 Direct Substitution Method Summary 155 References 155 Chapter 8 Dynamic Performance Input Types First-Order Processes Special Case: Integrating Processes Second-Order Processes Special Case: Step Response of Underdamped Processes Multicapacity Processes Special Case: Interacting Processes Effect of Zeros Special Case: Right Half-Plane Zeros Effect of Time Delays Summary 179 Continuing Problem 179 Chapter 9 Frequency Response What Is Frequency Response? Complex Numbers in Polar Coordinates Construction of Frequency Response Evaluation of Frequency Response Frequency Response of Common Systems Bode Diagrams Nyquist Diagrams Systems in Series Summary 198 Continuing Problem 199 Part III Summary Additional Reading Exercises Reference PART IV Feedback Control Chapter 10 Basic Elements of Feedback Control Feedback Control Problem Control Law Proportional Mode 215

6 Contents xiii Integral Mode Derivative Mode Three-Mode Controller (PID) Special Case: Discrete PID Physical Realizability Closed-Loop Transfer Functions Analysis of Individual Terms in PID Controllers Proportional Mode Integral Mode Derivative Mode Integral Windup Practical Issues in PID Design Direct and Reverse Action Bumpless Transfer PID Equation Forms Interacting/Noninteracting Derivative on Error/Derivative on Measurement Positional/Velocity Summary 230 Continuing Problem 230 Solution 231 Reference 233 Chapter 11 Stability Analysis of Closed-Loop Processes Closed-Loop Stability Routh's Criterion Dealing with Delays Root-Locus Method Zeros at Infinity Modeling Errors Frequency Response Methods Summary 249 Continuing Problem 249 Solution 250 Chapter 12 Feedback Control Design Design Objectives Response-Based Criteria Error-Based Criteria Controller Tuning Techniques Open-Loop Tuning (Cohen-Coon) Method 259

7 xiv Contents Closed-Loop Timing (Ziegler-Nichols) Method Direct Synthesis Method Processes without Time Delay Processes with Time Delay Comparing the Methods Summary 272 Continuing Problem 273 Solution 273 References 277 Part IV Summary 279 Additional Reading 279 Exercises 280 PART V Model-Based Control Chapter 13 Model-Based Control Feedforward Control Feedforward-Feedback Control Strategy Implementation Aspects Delay Compensation (Smith Predictor) Internal Model Control Concept of Perfect Control IMC Design Procedure PID Tuning Using IMC Rules Summary 306 Continuing Problem 306 Solution 306 References 313 Chapter 14 Model Uncertainty and Robustness IMC Structure with Model Uncertainty Description of Model Uncertainty Additive Uncertainty Multiplicative Uncertainty Estimation of Uncertainty Bounds IMC Design under Model Uncertainty Robust Stability Robust Performance Summary 326 References 326

8 Contents xv Chapter 15 Model Predictive Control General Principles Model Forms Impulse-Response Models Step-Response (Convolution) Models State-Space Models Dynamic Matrix Control Single-Input-Single-Output Unconstrained DMC Problem Controller Tuning Process Constraints State-Space Formulation of MPC Infinite Horizon Problem Summary 339 Continuing Problem 340 Solution 340 References 342 Part V Summary 343 Additional Reading 343 Exercises 344 PART VI Multivariate Control Chapter 16 Multivariable Systems Cascade Control Ratio Control Ratio Computation Set-Point Computation Split-Range Control Override Control Summary 362 Continuing Problem 362 Solution 363 References 368 Chapter 17 Multivariable Systems Characteristics of Multivariable Processes Modeling of Multivariable Processes 370

9 xvi Contents 17.3 Transfer Functions of Multivariable Processes Poles and Zeros of MIMO Systems Multivariable Feedback Control Structure Closed-Loop Poles and Zeros Stability of MIMO Closed-Loop Systems Summary 390 Continuing Problem 390 References 395 Chapter 18 Design of Multivariable Controllers Multiple-Input-Multiple-Output Feedback Analysis LoopF,,-^ Loopft.-*B RGA Interaction Measure Selection of Loops Multiloop Controller Design Design of Noninteracting Control Loops: Decouplers Summary 414 Continuing Problem 414 Solution 415 References 419 Part VI Summary 421 Additional Reading 421 Exercises 422 References 428 PART VII Control in Modern Manufacturing Chapter 19 Practical Control of Nonlinear Processes Operating Regime Modeling Approach Global Model Structure Gain-Scheduling Controller Determination of Process Gains Gain-Scheduling Implementation Multimodel Controller Design Multimodel Predictive Control (MMPC) Summary 447 References 448

10 Contents xvii Chapter 20 Process Optimization and Control Process Optimization Objective Function Constraints Equality Constraints Inequality Constraints Optimizing Control of Disturbances Open-Loop Back-Off Closed-Loop Back-Off Dynamic Optimization and Transition Planning Summary 470 References Chapter 21 Industrial Control Technology Evolution of Industrial Control Technology Generic Industrial Control Systems Architecture Supervisory Environment Control Environment Communication Environment Data Exchange Summary 490 Continuing Problem 490 References 493 Chapter 22 Role of Process Control in Modern Manufacturing Expanded Role of Control in Modern Manufacturing LayerJ Control Layer_2 Control Layer_3 Control Model-Centric Technologies Integrated Control Systems Summary 513 References 513 Chapter 23 Data Processing and Reconciliation Dealing with Missing Points Outliers Characterizing Process Data Modeling Model Fitting Based on Least-Squares Estimation 524 Process Data Data Reconciliation 525

11 xviii Contents 23.6 Issues in Data Reconciliation Process Model Classification of Process Variables Linear Data Reconciliation with Unmeasured Variables Gross Errors Data Reconciliation and Model-Centric Technologies Summary 539 References 539 Chapter 24 Process Monitoring Process Monitoring Statistical Process Control Univariate Control Charts Control Chart Interpretation Multivariate Charts Principal Component Analysis Calculation of Principal Components Multivariate Performance Monitoring Elliptical Normal Operation Region T2 and Squared Prediction Error Charts Contribution Plots Fault Diagnosis 24.6 Controller Performance Monitoring 563 and Classification State Classification Model Validation Stochastic Performance Monitoring Controller Oscillation Assessment Summary 567 References 567 Part VII Summary 569 Additional Reading 569 Exercises 572 Appendix A: Linearization 577 Appendix B: Laplace Transformation 585 Appendix C: Matrix Operations 593 Appendix D: Basic Statistics 601 Index 609