Practical Process Control for Engineers and Technicians (eBook)

Cover 1
Contents 6
Preface 1
1. Introduction 14
1.1 Objectives 1
1.2 Introduction 1
1.3 Basic definitions and terms used in process control 1
1.4 Process modeling 1
1.5 Process dynamics and time constants 1
1.6 Types or modes of operation of process control systems 1
1.7 Closed loop controller and process gain calculations 1
1.8 Proportional, integral and derivative control modes 1
1.9 An introduction to cascade control 1
2. Process measurement and transducers 31
2.1 Objectives 1
2.2 The definition of transducers and sensors 1
2.3 Listing of common measured variables 1
2.4 The common characteristics of transducers 1
2.5 Sensor dynamics 1
2.6 Selection of sensing devices 1
2.7 Temperature sensors 1
2.8 Pressure transmitters 1
2.9 Flow meters 1
2.10 Level transmitters 1
2.11 The spectrum of user models in measuring transducers 1
2.12 Instrumentation and transducer considerations 1
2.13 Selection criteria and considerations 1
2.14 Introduction to the smart transmitter 1
3. Basic principles of control valves and actuators 65
3.1 Objectives 1
3.2 An overview of eight of the most basic types of control valves 1
3.3 Control valve gain, characteristics, distortion and rangeability 1
3.4 Control valve actuators 1
3.5 Control valve positioners 1
3.6 Valve sizing 1
4. Fundamentals of control systems 91
4.1 Objectives 1
4.2 On–off control 1
4.3 Modulating control 1
4.4 Open loop control 1
4.5 Closed loop control 1
4.6 Deadtime processes 1
4.7 Process responses 1
4.8 Dead zone 1
5. Stability and control modes of closed loops 100
5.1 Objectives 1
5.2 The industrial process in practice 1
5.3 Dynamic behavior of the feed heater 1
5.4 Major disturbances of the feed heater 1
5.5 Stability 1
5.6 Proportional control 1
5.7 Integral control 1
5.8 Derivative control 1
5.9 Proportional, integral and derivative modes 1
5.10 ISA vs Allen Bradley 1
5.11 P, I and D relationships and related interactions 1
5.12 Applications of process control modes 1
5.13 Typical PID controller outputs 1
6. Digital control principles 113
6.1 Objectives 1
6.2 Digital vs analog: a revision of their definitions 1
6.3 Action in digital control loops 113
6.4 Identifying functions in the frequency domain 1
6.5 The need for digital control 1
6.6 Scanned calculations 1
6.7 Proportional control 1
6.8 Integral control 1
6.9 Derivative control 1
6.10 Lead function as derivative control 1
6.11 Example of incremental form (Siemens S5-100 V) 1
7. Real and ideal PID controllers 121
7.1 Objectives 1
7.2 Comparative descriptions of real and ideal controllers 1
7.3 Description of the ideal or the non-interactive PID controller 1
7.4 Description of the real (interactive) PID controller 1
7.5 Lead function „ derivative control with filter 1
7.6 Derivative action and effects of noise 1
7.7 Example of the KENT K90 controllers PID algorithms 1
8. Tuning of PID controllers in both open and closed loop control systems 125
8.1 Objectives 1
8.2 Objectives of tuning 1
8.3 Reaction curve method (Ziegler–Nichols) 1
8.4 Ziegler–Nichols open loop tuning method (1) 1
8.5 Ziegler–Nichols open loop method (2) using POI 1
8.6 Loop time constant (LTC) method 1
8.7 Hysteresis problems that may be encountered in open loop tuning 1
8.8 Continuous cycling method (Ziegler–Nichols) 1
8.9 Damped cycling tuning method 1
8.10 Tuning for no overshoot on start-up (Pessen) 1
8.11 Tuning for some overshoot on start-up (Pessen) 1
8.12 Summary of important closed loop tuning algorithms 1
8.13 PID equations: dependent and independent gains 1
9. Controller output modes, operating equations and cascade control 144
9.1 Objectives 1
9.2 Controller output 1
9.3 Multiple controller outputs 1
9.4 Saturation and non-saturation of output limits 1
9.5 Cascade control 1
9.6 Initialization of a cascade system 1
9.7 Equations relating to controller configurations 1
9.8 Application notes on the use of equation types 1
9.9 Tuning of a cascade control loop 1
9.10 Cascade control with multiple secondaries 1
10. Concepts and applications of feedforward control 155
10.1 Objectives 1
10.2 Application and definition of feedforward control 1
10.3 Manual feedforward control 1
10.4 Automatic feedforward control 1
10.5 Examples of feedforward controllers 1
10.6 Time matching as feedforward control 1
11. Combined feedback and feedforward control 160
11.1 Objectives 1
11.2 The feedforward concept 1
11.3 The feedback concept 1
11.4 Combining feedback and feedforward control 1
11.5 Feedback„feedforward summer 1
11.6 Initialization of a combined feedback and feedforward control system 1
11.7 Tuning aspects 1
12. Long process deadtime in closed loop control and the Smith Predictor 163
12.1 Objectives 1
12.2 Process deadtime 1
12.3 An example of process deadtime 1
12.4 The Smith Predictor model 1
12.5 The Smith Predictor in theoretical use 1
12.6 The Smith Predictor in reality 1
12.7 An exercise in deadtime compensation 1
13. Basic principles of fuzzy logic and neural networks 168
13.1 Objectives 1
13.2 Introduction to fuzzy logic 1
13.3 What is fuzzy logic? 1
13.4 What does fuzzy logic do? 1
13.5 The rules of fuzzy logic 1
13.6 Fuzzy logic example using five rules and patches 1
13.7 The Achilles heel of fuzzy logic 1
13.8 Neural networks 1
13.9 Neural back propagation networking 1
13.10 Training a neuron network 1
13.11 Conclusions and then the next step 1
14. Self-tuning intelligent control and statistical process control 178
14.1 Objectives 1
14.2 Self-tuning controllers 1
14.3 Gain scheduling controller 1
14.4 Implementation requirements for self-tuning controllers 1
14.5 Statistical process control (SPC) 1
14.6 Two ways to improve a production process 1
14.7 Obtaining the information required for SPC 1
14.8 Calculating control limits 1
14.9 The logic behind control charts 1
Appendix A: Some Laplace transform pairs 1
Appendix B: Block diagram transformation theorems 1
Appendix C: Detail display 1
C.1 Major control variables 1
C.2 Tuning constants 1
C.3 Range, limit, alarm and status parameters 1
Appendix D: Auxiliary display 1
D.1 Controller variables 1
D.2 Process simulation variables 1
Appendix E: Configuring a tuning exercise in a controller 1
E.1 Exercise using a Honeywell controller „ configuring a tuning exercise in a basic controller 1
Appendix F: Installation of simulation software 1
F.1 Hardware requirements 1
F.2 Industrial control in practice „ training version 1.1 ICT 32 1
Appendix G: Operation of simulation software 1
G.1 Starting the program from DOS 1
G.2 Starting a customized application from the DOS prompt 1
G.3 Starting the program from MS-Windows 1
G.4 Display call up 1
G.5 How to quit an individual training application 1
G.6 Value change of variables 1
G.7 Command line parameters 1
G.8 Status change of status variables 1
G.9 Trend operation 1
G.10 Display save 1
G.11 Display assignments as delivered 1
Appendix H: Configuration 1
Appendix I: General syntax of configuration commands 1
Appendix J: Configuration commands 1
J.1 General purpose variable definitions 1
J.2 Extended variable definitions 1
J.3 Display commands 1
J.4 Algorithm definitions 1
Appendix K: Algorithms 1
K.1 Interacting PID-algorithm-blocks to build PID-controllers 1
K.2 General algorithms 1
Appendix L: Background graphics design 1
Appendix M: Configuration example 1
M.1 Example file (FLOW.PCF) 1
Introduction to exercises 1
Exercise 1: Flow control loop „ basic example 1
E.1.1 Objective 1
E.1.2 Operation 1
E.1.3 Observation 1
E.1.4 Operation 1
E.1.5 Observation 1
E.1.6 Operation 1
Exercise 2: Proportional (P) control „ flow chart 1
E.2.1 Objective 1
E.2.2 Operation 1
E.2.3 Observation 1
E.2.4 Operation 1
E.2.5 Conclusion 1
Exercise 3: Integral (I) Control „ flow control 1
E.3.1 Objective 1
E.3.2 Operation 1
E.3.3 Observation 1
E.3.4 Operation 1
E.3.5 Conclusion 1
Exercise 4: Proportional and integral (PI) control „ flow control 1
E.4.1 Objective 1
E.4.2 Operation 1
E.4.3 Observation 1
E.4.4 Operation 1
E.4.5 Conclusion 1
Exercise 5: Introduction to derivative (D) control 1
E.5.1 Objective 1
E.5.2 Operation 1
E.5.3 Observation 1
E.5.4 Operation 1
E.5.5 Conclusion 1
Exercise 6: Practical introduction into stability aspects 1
E.6.1 Objective 1
E.6.2 Operation 1
E.6.3 Observation 1
E.6.4 Operation 1
E.6.5 Observation 1
E.6.6 Operation 1
E.6.7 Observation 1
E.6.8 Operation 1
E.6.9 Observation 1
E.6.10 Conclusion 1
Exercise 7: Open loop method „ tuning exercise 1
E.7.1 Objective 1
E.7.2 Operation 1
E.7.3 Observation 1
E.7.4 Confirmation of proper tuning 1
E.7.5 Fine tuning 1
Exercise 8: Closed loop method „ tuning exercise 1
E.8.1 Objective 1
E.8.2 Operation 1
E.8.3 Observation 1
E.8.4 Confirmation of good tuning 1
E.8.5 Fine tuning 1
Exercise 9: Saturation and non-saturation output limits 1
E.9.1 Objective 1
E.9.2 With saturation of the OP 1
E.9.3 With non-saturation OP-limit-calculation 1
E.9.4 Virtual OP limit operation 1
E.9.5 Operation 1
E.9.6 Real OP limit operation 1
Exercise 10: Ideal derivative action „ ideal PID 276
E.10.1 Objective 1
E.10.2 Operation 1
E.10.3 Observation 1
E.10.4 Operation 1
E.10.5 Conclusion 1
E.10.6 Operation 1
E.10.7 Observation 1
E.10.8 Conclusion 1
Exercise 11: Cascade control 1
E.11.1 Objective 1
E.11.2 Operation 1
E.11.3 Observation 1
E.11.4 Conclusion 1
E.11.5 Operation 1
E.11.6 Conclusion 1
E.11.7 Observation 1
E.11.8 Conclusion 1
Exercise 12: Cascade control with one primary and two secondaries 1
E.12.1 Objective 1
E.12.2 Training application 1
E.12.3 Operation 1
E.12.4 Observation 1
E.12.5 Operation 1
E.12.6 Observation 1
E.12.7 Operation 1
E.12.8 Observation 1
E.12.9 Operation 1
E.12.10 Observation 1
E.12.11 Operation 1
E.12.12 Observation 1
E.12.13 Conclusion 1
Exercise 13: Combined feedback and feedforward control 1
E.13.1 Objective 1
E.13.2 Common pitfalls 1
E.13.3 Special effects with boiler level control 1
Exercise 14: Deadtime compensation in feedback control 1
E.14.1 Objectives 1
E.14.2 Operation 1
E.14.3 Observation 1
E.14.4 Operation 1
E.14.5 Observation 1
E.14.6 Conclusion 1
E.14.7 Operation of simulation tuning 1
E.14.8 Conclusion 1
Exercise 15: Static value alarm 1
E.15.1 Objective 1
E.15.2 Operation 1
E.15.3 Observation 1
E.15.4 Conclusion 1
Index 1