Process Control : A Practical Approach

This expanded new edition is specifically designed to meet the needs of the process industry, and closes the gap between theory and practice. * Back-to-basics approach, with a focus on techniques that have an immediate practical application, and heavy maths relegated to the end of the book * Written by an experienced practitioner, highly regarded by major corporations, with 25 years of teaching industry courses * Supports the increasing expectations for Universities to teach more practical process control (supported by IChemE) Title Page 5 Copyright Page 6 Contents 7 Preface 12 About the Author 17 Chapter 1 Introduction 19 Chapter 2 Process Dynamics 21 2.1 Definition 21 2.2 Cascade Control 28 2.3 Model Identification 30 2.4 Integrating Processes 44 2.5 Other Types of Process 47 2.6 Robustness 49 Chapter 3 PID Algorithm 53 3.1 Definitions 53 3.2 Proportional Action 54 3.3 Integral Action 59 3.4 Derivative Action 61 3.5 Versions of Control Algorithm 67 3.6 Interactive PID Controller 69 3.7 Proportional-on-PV Controller 74 3.8 Nonstandard Algorithms 82 3.9 Tuning 83 3.10 Ziegler-Nichols Tuning Method 84 3.11 Cohen-Coon Tuning Method 90 3.12 Tuning Based on Penalty Functions 91 3.13 Manipulated Variable Overshoot 95 3.14 Lambda Tuning Method 98 3.15 IMC Tuning Method 98 3.16 Choice of Tuning Method 101 3.17 Suggested Tuning Method for Self-Regulating Processes 102 3.18 Tuning for Load Changes 105 3.19 Tuning for SP Ramps 107 3.20 Tuning for Unconstrained MV Overshoot 109 3.21 PI Tuning Compared to PID Tuning 110 3.22 Tuning for Large Scan Interval 112 3.23 Suggested Tuning Method for Integrating Processes 115 3.24 Measure of Robustness 117 3.25 Implementation of Tuning 118 3.26 Tuning Cascades 119 3.27 Loop Gain 122 3.28 Adaptive Tuning 123 3.29 Initialisation 124 3.30 Anti-Reset Windup 126 3.31 On-Off Control 127 Chapter 4 Level Control 130 4.1 Use of Cascade Control 130 4.2 Parameters Required for Tuning Calculations 131 4.3 Tight Level Control 138 4.4 Averaging Level Control 140 4.5 Error-Squared Controller 147 4.6 Gap Controller 150 4.7 Impact of Noise on Averaging Control 152 4.8 Potential Disadvantage of Averaging Level Control 154 4.9 General Approach to Tuning 155 4.10 Three-Element Level Control 157 Chapter 5 Signal Conditioning 161 5.1 Instrument Linearisation 161 5.2 Process Linearisation 163 5.3 Control of pH 165 5.4 Constraint Conditioning 169 5.5 Pressure Compensation of Distillation Tray Temperature 171 5.6 Compensation of Gas Flow Measurement 171 5.7 Filtering 173 5.8 Exponential Filter 175 5.9 Nonlinear Exponential Filter 179 5.10 Moving Average Filter 179 5.11 Least Squares Filter 181 5.12 Tuning the Filter 187 5.13 Control Valve Characterisation 188 5.14 Equal Percentage Valve 190 5.15 Split-Range Valves 196 Chapter 6 Feedforward Control 202 6.1 Ratio Algorithm 203 6.2 Bias Algorithm 206 6.3 Deadtime and Lead-Lag Algorithms 208 6.4 Tuning 212 6.5 Laplace Derivation of Dynamic Compensation 217 Chapter 7 Deadtime Compensation 219 7.1 Smith Predictor 219 7.2 Internal Model Control 224 7.3 Dahlin Algorithm 224 Chapter 8 Multivariable Control 228 8.1 Constraint Control 228 8.2 SISO Constraint Control 229 8.3 Signal Selectors 231 8.4 Relative Gain Analysis 235 8.5 Niederlinski Index 244 8.6 Condition Number 245 8.7 Steady State Decoupling 247 8.8 Dynamic Decoupling 249 8.9 MPC Principles 255 8.10 Parallel Coordinates 257 8.11 Enhanced Operator Displays 258 8.12 MPC Performance Monitoring 260 Chapter 9 Inferentials and Analysers 266 9.1 Inferential Properties 266 9.2 Assessing Accuracy 274 9.3 Laboratory Update of Inferential 280 9.4 Analyser Update of Inferential 284 9.5 Monitoring On-Stream Analysers 286 Chapter 10 Combustion Control 288 10.1 Fuel Gas Flow Correction 288 10.2 Measuring NHV 296 10.3 Dual Firing 298 10.4 Heater Inlet Temperature Feedforward 299 10.5 Fuel Pressure Control 302 10.6 Firebox Pressure 305 10.7 Combustion Air Control 306 10.8 Boiler Control 317 10.9 Fired Heater Pass Balancing 318 Chapter 11 Compressor Control 324 11.1 Polytropic Head 324 11.2 Load Control (Turbo-Machines) 328 11.3 Load Control (Reciprocating Machines) 332 11.4 Anti-Surge Control 333 Chapter 12 Distillation Control 340 12.1 Key Components 343 12.2 Relative Volatility 343 12.3 McCabe-Thiele Diagram 346 12.4 Cut and Separation 351 12.5 Effect of Process Design 363 12.6 Basic Controls 368 12.7 Pressure Control 368 12.8 Level Control 382 12.9 Tray Temperature Control 400 12.10 Pressure Compensated Temperature 411 12.11 Inferentials 420 12.12 First-Principle Inferentials 429 12.13 Feedforward on Feed Rate 431 12.14 Feed Composition Feedforward 434 12.15 Feed Enthalpy Feedforward 436 12.16 Decoupling 437 12.17 Multivariable Control 442 12.18 On-Stream Analysers 451 12.19 Towers with Sidestreams 451 12.20 Column Optimisation 453 12.21 Optimisation of Column Pressure 456 12.22 Energy/Yield Optimisation 459 Chapter 13 APC Project Execution 462 13.1 Benefits Study 462 13.2 Benefit Estimation for Improved Regulatory Control 463 13.3 Benefits of Closed-Loop Real-Time Optimisation 473 13.4 Basic Controls 476 13.5 Basic Control Monitoring 477 13.6 Inferential Properties 482 13.7 Organisation 482 13.8 Vendor Selection 486 13.9 Safety in APC Design 489 13.10 Alarms 489 Chapter 14 Statistical Methods 491 14.1 Central Limit Theorem 491 14.2 Generating a Normal Distribution 493 14.3 Quantile Plots 495 14.4 Calculating Standard Deviation 496 14.5 Skewness and Kurtosis 498 14.6 Correlation 498 14.7 Confidence Interval 499 14.8 Westinghouse Electric Company Rules 502 14.9 Gamma Function 503 14.10 Student t Distribution 504 14.11 χ2 Distribution 507 14.12 F Distribution 510 14.13 Akaike Information Criterion 515 14.14 Adjusted R2 517 14.15 Levene’s Test 518 14.16 Box-Wetz Ratio 519 14.17 Regression Analysis 520 14.18 Outliers 531 14.19 Model Identification 532 14.20 Autocorrelation and Autocovariance 536 14.21 Artificial Neural Networks 545 14.22 Repeatability 551 14.23 Reproducibility 551 14.24 Six-Sigma 553 14.25 Data Reconciliation 553 Chapter 15 Mathematical Techniques 558 15.1 Fourier Transform 558 15.2 Recursive Filters 566 15.3 Lagrangian Interpolation 571 15.4 Padé Approximation 575 15.5 Laplace Transform Derivations 578 15.6 Laplace Transforms for Processes 581 15.7 Laplace Transforms for Controllers 587 15.8 I-PD versus PI-D Algorithm 590 15.9 Direct Synthesis 591 15.10 Predicting Filter Attenuation 596 15.11 Stability Limit for PID Control 597 15.12 Ziegler-Nichols Tuning from Process Dynamics 601 15.13 Partial Fractions 604 15.14 z-Transforms and Finite Difference Equations 606 References 612 Index 614 EULA 623 So why another book on process control' Process Control: A Practical Approach is a ground-breaking guide that provides everything needed to design and maintain process control applications. The book follows the hierarchy from basic control, through advanced regulatory control, up to and including multivariable control. It addresses many process-specific applications including those on fired heaters, compressors and distillation columns. Written with the practicing control engineer in mind, the book: -Brings together proven design methods, many of which have never been published before -Focuses on techniques that have an immediate practical application -Minimizes the use of daunting mathematics - but for the more demanding reader, complex mathematical derivations are included at the end of each chapter -Covers the use of all the algorithms, common to most distributed control systems This book raises the standard of what might be expected of even basic controls. In addition to the design methods it describes any shortcuts that can be taken and how to avoid common pitfalls. Proper application will result in significant improvements to process performance. Myke King's practical approach addresses the needs of the process industry, and will improve the working practices of many control engineers. "This book would be of value to process control engineers in any country."--Mr Andrew Ogden-Swift, Chairmain, Process Management and Control Subject Group, Institution of Chemical Engineers, UK "This book should take the process-control world by storm."--Edward Dilley, Lecturer in Process Control, ESD Simulation Training So why another book on process control? Process Control: A Practical Approach is a ground-breaking guide that provides everything needed to design and maintain process control applications. The book follows the hierarchy from basic control, through advanced regulatory control, up to and including multivariable control. It addresses many process-specific applications including those on fired heaters, compressors and distillation columns. Written with the practicing control engineer in mind, the book: Brings together proven design methods, many of which have never been published before Focuses on techniques that have an immediate practical application. Minimizes the use of daunting mathematics - but for the more demanding reader, complex mathematical derivations are included at the end of each chapter. Covers the use of all the algorithms, common to most distributed control systems This book raises the standard of what might be expected of even basic controls. In addition to the design methods it describes any shortcuts that can be taken and how to avoid common pitfalls. Proper application will result in significant improvements to process performance. Myke King's practical approach addresses the needs of the process industry, and will improve the working practices of many control engineers. "This book would be of value to process control engineers in any country."--Mr Andrew Ogden-Swift, Chairmain, Process Management and Control Subject Group, Institution of Chemical Engineers, UK "This book should take the process-control world by storm."- Edward Dilley, Lecturer in Process Control, ESD Simulation Training A ground-breaking guide that provides everything needed to design and maintain process control applications. The book follows the hierarchy from basic control, through advanced regulatory control, up to and including multivariable control. It addresses many process-specific applications including those on fired heaters, compressors and distillation columns. Written with the practicing control engineer in mind, the book: a) Brings together proven design methods, many of which have never been published before. b) Focuses on techniques that have an immediate practical application. c) Minimizes the use of daunting mathematics - but for the more demanding reader, complex mathematical derivations are included at the end of each chapter. d) Covers the use of all the algorithms, common to most distributed control systems. This book raises the standard of what might be expected of even basic controls. In addition to the design methods it describes any shortcuts that can be taken and how to avoid common pitfalls. Proper application will result in significant improvements to process performance. Myke King's practical approach addresses the needs of the process industry, and will improve the working practices of many control engineers

This expanded new edition is specifically designed to meet the needs of the process industry, and closes the gap between theory and practice.

• Back-to-basics approach, with a focus on techniques that have an immediate practical application, and heavy maths relegated to the end of the book
• Written by an experienced practitioner, highly regarded by major corporations, with 25 years of teaching industry courses
• Supportstheincreasing expectations for Universities to teach more practical process control (supported by IChemE)

Myke King. Includes Bibliographical References And Index. Mode Of Access: World Wide Web.