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Process Control: A Practical Approach

ISBN: 978-0-470-97666-1
416 pages
December 2010
Process Control: A Practical Approach (0470976667) cover image

Description

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

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Table of Contents

Preface ix

About the Author xv

1. Introduction 1

2. Process Dynamics 3

2.1 Definition 3

2.2 Cascade Control 9

2.3 Model Identification 11

2.4 Integrating Processes 20

2.5 Other Types of Process 22

2.6 Robustness 24

2.7 Laplace Transforms for Processes 27

References 28

3. PID Algorithm 29

3.1 Definitions 29

3.2 Proportional Action 30

3.3 Integral Action 33

3.4 Derivative Action 35

3.5 Versions of Control Algorithm 39

3.6 Interactive PID Controller 41

3.7 Proportional-on-PV Controller 43

3.8 Nonstandard Algorithms 50

3.9 Tuning 51

3.10 Ziegler-Nichols Tuning Method 52

3.11 Cohen-Coon Tuning Method 56

3.12 Tuning Based on Penalty Functions 57

3.13 Manipulated Variable Overshoot 60

3.14 Lambda Tuning Method 61

3.15 IMC Tuning Method 63

3.16 Choice of Tuning Method 65

3.17 Suggested Tuning Method for Self-Regulating Processes 66

3.18 Tuning for Load Changes 66

3.19 Tuning for Unconstrained MV Overshoot 71

3.20 PI Tuning Compared to PID Tuning 72

3.21 Tuning for Large Scan Interval 74

3.22 Suggested Tuning Method for Integrating Processes 76

3.23 Implementation of Tuning 78

3.24 Loop Gain 79

3.25 Adaptive Tuning 79

3.26 Initialisation 80

3.27 Anti-Reset Windup 81

3.28 On-Off Control 81

3.29 Laplace Transforms for Controllers 83

3.30 Direct Synthesis 85

References 88

4. Level Control 91

4.1 Use of Cascade Control 91

4.2 Parameters Required for Tuning Calculations 93

4.3 Tight Level Control 97

4.4 Averaging Level Control 100

4.5 Error-Squared Controller 105

4.6 Gap Controller 108

4.7 Impact of Noise on Averaging Control 111

4.8 General Approach to Tuning 113

4.9 Three-Element Level Control 114

5. Signal Conditioning 117

5.1 Instrument Linearisation 117

5.2 Process Linearisation 119

5.3 Constraint Conditioning 122

5.4 Pressure Compensation of Distillation Tray Temperature 124

5.5 Pressure Compensation of Gas Flow Measurement 125

5.6 Filtering 126

5.7 Exponential Filter 127

5.8 Higher Order Filters 129

5.9 Nonlinear Exponential Filter 130

5.10 Averaging Filter 131

5.11 Least Squares Filter 132

5.12 Control Valve Characterisation 136

5.13 Equal Percentage Valve 137

5.14 Split-Range Valves 140

6. Feedforward Control 147

6.1 Ratio Algorithm 147

6.2 Bias Algorithm 151

6.3 Deadtime and Lead-Lag Algorithms 152

6.4 Tuning 155

6.5 Laplace Derivation of Dynamic Compensation 161

7. Deadtime Compensation 163

7.1 Smith Predictor 163

7.2 Internal Model Control 166

7.3 Dahlin Algorithm 167

References 168

8. Multivariable Control 169

8.1 Constraint Control 169

8.2 SISO Constraint Control 170

8.3 Signal Selectors 171

8.4 Relative Gain Analysis 174

8.5 Steady State Decoupling 177

8.6 Dynamic Decoupling 180

8.7 MVC Principles 184

8.8 Parallel Coordinates 187

8.9 Enhanced Operator Displays 188

8.10 MVC Performance Monitoring 189

References 195

9. Inferentials and Analysers 197

9.1 Inferential Properties 197

9.2 Assessing Accuracy 203

9.3 Laboratory Update of Inferential 208

9.4 Analyser Update of Inferential 210

9.5 Monitoring On-stream Analysers 212

Reference 214

10. Combustion Control 215

10.1 Fuel Gas Flow Correction 215

10.2 Measuring NHV 220

10.3 Dual Firing 222

10.4 Inlet Temperature Feedforward 223

10.5 Fuel Pressure Control 225

10.6 Combustion Air Control 227

10.7 Boiler Control 236

10.8 Fired Heater Pass Balancing 237

11. Compressor Control 243

11.1 Polytropic Head 243

11.2 Flow Control (Turbo-Machines) 246

11.3 Flow Control (Reciprocating Machines) 251

11.4 Anti-Surge Control 252

12. Distillation Control 259

12.1 Key Components 262

12.2 Relative Volatility 263

12.3 McCabe-Thiele Diagram 266

12.4 Cut and Separation 271

12.5 Effect of Process Design 281

12.6 Basic Controls 285

12.7 Pressure Control 285

12.8 Level Control 299

12.9 Tray Temperature Control 315

12.10 Pressure Compensated Temperature 325

12.11 Inferentials 335

12.12 First-Principle Inferentials 342

12.13 Feedforward on Feed Rate 344

12.14 Feed Composition Feedforward 348

12.15 Feed Enthalpy Feedforward 349

12.16 Decoupling 350

12.17 Multivariable Control 352

12.18 On-stream Analysers 360

12.19 Towers with Sidestreams 361

12.20 Column Optimisation 364

12.21 Optimisation of Column Pressure 366

12.22 Energy/Yield Optimisation 368

References 370

13. APC Project Execution 371

13.1 Benefits Study 371

13.2 Benefit Estimation for Improved Regulatory Control 373

13.3 Benefits of Closed-Loop Real-Time Optimisation 380

13.4 Basic Controls 382

13.5 Inferentials 384

13.6 Organisation 385

13.7 Vendor Selection 389

13.8 Safety in APC Design 391

13.9 Alarms 392

References 393

Index 395

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Author Information

About the Author 
Myke King is the Director of Whitehouse Consulting, UK, an independent consulting organisation specialising in process control.

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Reviews

"The author is experienced and he dosen't hesitate to tell you what he thinks, making this a good book to increase your practical knowledge of regulatory control." (TCE- The Chemical Engineer, March 2012)

 

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Related Websites / Extra

Whitehouse Consulting Click here to visit the website of the author Myke King, the founder of Whitehouse Consulting. Find out more about the Engineering Toolkit, training courses, software, and more.
Interview Click here to read an interview with the author on ChemistryViews. Discover how Myke King unveils the myths of Process Control...
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