Essentials of Process Control – Michael L. Luyben, William L. Luyben – 1st Edition

Preface

1 Introduction 1

1.1 Examples of Process Dynamics and Control 2

1.2 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 General Concepts and Terminology 2 0

1.4 Laws, Languages, and Levels of Process Control 2 2

1.4.1 Process Control Laws

1.4.2 Languages qf Process Control

1.4.3 Levels of Process Control

1.5 Conclusion

PART I Time Domain Dynamics and Control

2 Time Domain Dynamics

2.1 Classification and Definition 2 7

2.2 Linearization and Perturbation Variables 31

2.2.1 Linearization

2.2.2 Perturbation Variables

2.3 Responses of Simple Linear Systems

2.3.1 First-Order Linear Ordinary Differential Equation

2.3.2 Second-Order Linear ODES with Constant CoefJicients

2.3.3 Nth-Order Linear ODES with Constant Coefficients

2.4 Solution Using MATLAB

2.5 Conclusion

Problems

3 Conventional Control Systems and Hardware

3.1 Control Instrumentation

3.1. I' Sensors

3.1.2 Transmitters

3.1.3 Control Valves

3.1.4 Analog and Digital Controllers

3.1.5 Computing and Logic Devices

3.2 Performance of Feedback Controllers

3.2.1 SpeciJications for Closedloop Response

3.2.2 Load Pcrjormance

3.3 Contrciler Tuning

3.3. I Rules of Thumb

3.3.2 On-Line Trial and Error

3.3.3 Ziegler-Nichols Method

3.3.4 Tyreus- Luybcrr Method

3.4 Conclusions

Problems

4 Advanced Control Systems 117

4.1 Ratio Control 117

4.2 Cascade Control 118

4.3 Computed Variable Control 120

4.4 Override Control 122

4.5 Nonlinear and Adaptive Control 125

4.6 Valve Position (Optimizing) Control 126

4.7 Feedforward Control Concepts 128

4.8 Control System Design Concepts 129

4.9 Conclusion 135

Problems

5 Interaction between Steady-State Design and Dynamic Controllability

5.1 Introduction

5.2 Qualitative Examples

5.3 Simple Quantitative Example

5.4 Impact of Controllability on Capital Investment and Yield

5.5 General Trade-off between Controllability and Thermodynamic Reversibility

5.6 Quantitative Economic Assessment of Steady-State Design and Dynamic Controllability

5.7 Conclusion

6 Plantwide Control

6.1 Series Cascades of Units

6.2 Effect of Recycle on Time Constants

6.3 Snowball Effects in Recycle Systems

6.4 llsc of Steady-State Sensitivity Analysis to Screen Plantwide Control Structures

6.5 Second-Order Reaction Example

6.6 Plantwide Control Design Procedure

6.7 Conclusion

Problems

P A R T 2 Laplace-Domain Dynamics and Control

7 Laplace-Domain Dynamics

7.1 Laplace Transformation Fundamentals

7.2 Laplace Transformation of Important Functions

7.3 Inversion of Laplace Transforms

7.4 Transfer Functions

7.5 Examples

7.6 Properties of Transfer Functions

7.7 Transfer Functions for Feedback Controllers

7.8 Conclusion

Problems

8 Laplace-Domain Analysis of Conventional Feedback Control Systems

8.1 Openloop and Closedloop Systems

8.2 Stability

8.3 Performance Specifications

8.4 Root Locus Analysis

8.5 Conclusion

Problems

9 Laplace-Domain Analysis of Advanced

Control Systems

9.1 Cascade Control

9.2 Feedforward Control

9.3 Openloop-Unstable Processes

9.4 Processes with Inverse Response

9.5 Model-Based Control

9.6 Conclusion

Problems

P A R T 3 Frequency-Domain Dynamics and Control

10 Frequency-Domain Dynamics

10.1 Definition

10.2 Basic Theorem

10.3 Representation

10.4 Computer Plotting

10.5 Conclusion

Problems

11 Frequency-Domain Analysis of Closedloop Systems

I 1.1 Nyquist Stability Criterion

I I .2 Closedloop Spccilications in the Frequency Domain

I I .3 Frequency Response of Feedback Controllers

I .4 Examples

11.5 Use of MATLAB for Frequency Response Plots

11.6 Capacity-Based Method for Quantifying

11.7 Conclusion

Problems

P A R T 4 Multivariable Processes

12 Matrix Representation and Analysis

12.1 Matrix Representation

12.2 Stability

12.3 Interaction

12.4 Conclusion

Problems

13 Design of Controllers for Multivariable Processes

13.1 Problem Definition

13.2 Selection of Controlled Variables

13.3 Selection of Manipulated Variables

13.4 Elimination of Poor Pairings

13.5 BLT Tuning

13.6 Load Rejection Performance

13.7 Model Predictive Control

13.8 Conclusion

Problems

P A R T 5 Sampled-Data Systems

14 Sampling, z Transforms, and Stability

14.1 Introduction

14.2 Impulse Sampler

14.3 Basic Sampling Theorem

14.4 z Transformation

14.5 Pulse Transfer Functions

14.6 Hold Devices

14.7 Openloop and Closedloop Systems

14.8 Stability in the z Plane

14.9 Conclusion

Problems

15 Stability Analysis of Sampled-Data Systems

15.1 Root Locus Design Methods .

15.2 Frequency-Domain Design Techniques

15.3 Physical Realizability

15.4 Minimal-Prototype Design

15.5 Conclusion

Problems

P A R T 6 Identification

16 Process Identification

16.1 Fundamental Concepts

16.2 Direct Methods

16.3 Pulse Testing

16.4 Relay Feedback Identification

16.5 Least-Squares Methods

16.6 Use of the MATLAB Identification Toolbox

16.7. Conclusion

Problems

Appendix A

Computer Programs

Nonlinear Model

Appendix B: Instrumentation Hardware

Index