Process Control Instrumentation Technology

by Johnson, Curtis D.

• ISBN13: 9780139382000
• ISBN10: 0139382003
• Edition: 6th
• Format: Hardcover
• Copyright: 1999-05-01
• Publisher: Pearson College Div

Summary

For Sophomore/Junior-level courses in Automatic Control Systems, Process Controls, and Instrumentation and Measurement. This text is designed to provide students with an understanding and appreciation of some of the theoretical concepts behind control system elements and operations, without the need of advanced math and theory. It also presents some of the practical details of how elements of a control system are designed and operated, such as would be gained from on-the-job experience. This middle ground of knowledge enables students to design the elements of a control system from a practical, working perspective, and comprehend how these elements affect overall system operation and tuning.

Table of Contents

1 INTRODUCTION TO PROCESS CONTROL	1	(46)
Instructional Objectives	1	(1)
1.1 Introduction	1	(1)
1.2 Control Systems	2	(3)
1.2.1 Process-Control Principles
1.2.2 Servomechanisms
1.2.3 Discrete-State Control Systems
1.3 Process-Control Block Diagram	5	(4)
1.3.1 Identification of Elements
1.3.2 Block Diagram
1.4 Control System Evaluation	9	(4)
1.4.1 Stability
1.4.2 Steady-State Regulation
1.4.3 Transient Regulation
1.4.4 Evaluation Criteria
1.5 Analog and Digital Processing	13	(7)
1.5.1 Data Representation
1.5.2 ON/OFF Control
1.5.3 Analog Control
1.5.4 Digital Control
1.5.5 Programmable Logic Controllers
1.6 Units, Standards, and Definitions	20	(13)
1.6.1 Units
1.6.2 Analog Data Representation
1.6.3 Definitions
1.6.4 Process-Control Drawings
1.7 Sensor Time Response	33	(3)
1.7.1 First-Order Response
1.7.2 Second-Order Response
1.8 Significance and Statistics	36	(11)
1.8.1 Significant Figures
1.8.2 Statistics
Summary
Problems
2 ANALOG SIGNAL CONDITIONING	47	(62)
Instructional Objectives	47	(1)
2.1 Introduction	47	(1)
2.2 Principles of Analog Signal Conditioning	48	(4)
2.2.1 Signal-Level and Bias Changes
2.2.2 Linearization
2.2.3 Conversions
2.2.4 Filtering and Impedance Matching
2.2.5 Concept of Loading
2.3 Passive Circuits	52	(25)
2.3.1 Divider Circuits
2.3.2 Bridge Circuits
2.3.3 RC Filters
2.4 Operational Amplifiers	77	(7)
2.4.1 Op Amp Characteristics
2.4.2 Op Amp Specifications
2.5 Op Amp Circuits in Instrumentation	84	(13)
2.5.1 Voltage Follower
2.5.2 Inverting Amplifier
2.5.3 Noninverting Amplifier
2.5.4 Differential Instrumentation Amplifier
2.5.5 Voltage-to-Current Converter
2.5.6 Current-to-Voltage Converter
2.5.7 Integrator
2.5.8 Differentiator
2.5.9 Linearization
2.6 Design Guidelines	97	(12)
Summary
Problems
3 DIGITAL SIGNAL CONDITIONING	109	(54)
Instructional Objectives	109	(1)
3.1 Introduction	109	(1)
3.2 Review of Digital Fundamentals	110	(9)
3.2.1 Digital Information
3.2.2 Fractional Binary Numbers
3.2.3 Boolean Algebra
3.2.4 Digital Electronics
3.2.5 Programmable Logic Controllers
3.2.6 Computer Interface
3.3 Converters	119	(31)
3.3.1 Comparators
3.3.2 Digital-to-Analog Converters (DACs)
3.3.3 Analog-to-Digital Converters (ADCs)
3.3.4 Frequency-Based Converters
3.4 Data-Acquisition Systems	150	(13)
3.4.1 DAS Hardware
3.4.2 DAS Software
Summary
Problems
4 THERMAL SENSORS	163	(50)
Instructional Objectives	163	(1)
4.1 Introduction	163	(1)
4.2 Definition of Temperature	164	(4)
4.2.1 Thermal Energy
4.2.2 Temperature
4.3 Metal Resistance Versus Temperature Devices	168	(9)
4.3.1 Metal Resistance Versus Temperature
4.3.2 Resistance Versus Temperature Approximations
4.3.3 Resistance-Temperature Detectors
4.4 Thermistors	177	(4)
4.4.1 Semiconductor Resistance Versus Temperature
4.4.2 Thermistor Characteristics
4.5 Thermocouples	181	(12)
4.5.1 Thermoelectric Effects
4.5.2 Thermocouple Characteristics
4.5.3 Thermocouple Sensors
4.6 Other Thermal Sensors	193	(7)
4.6.1 Bimetal Strips
4.6.2 Gas Thermometers
4.6.3 Vapor-Pressure Thermometers
4.6.4 Liquid-Expansion Thermometers
4.6.5 Solid-State Temperature Sensors
4.7 Design Considerations	200	(13)
Summary
Problems
5 MECHANICAL SENSORS	213	(60)
Instructional Objectives	213	(1)
5.1 Introduction	213	(1)
5.2 Displacement, Location, or Position Sensors	214	(8)
5.2.1 Potentiometric
5.2.2 Capacitive and Inductive
5.2.3 Variable Reluctance
5.2.4 Level Sensors
5.3 Strain Sensors	222	(14)
5.3.1 Strain and Stress
5.3.2 Strain Gauge Principles
5.3.3 Metal Strain Gauges (SGs)
5.3.4 Semiconductor Strain Gauges (SGs)
5.3.5 Load Cells
5.4 Motion Sensors	236	(12)
5.4.1 Types of Motion
5.4.2 Accelerometer Principles
5.4.3 Types of Accelerometers
5.4.4 Applications
5.5 Pressure Sensors	248	(9)
5.5.1 Pressure Principles
5.5.2 Pressure Sensors (p is greater than 1 atmosphere)
5.5.3 Pressure Sensors (p is less than 1 atmosphere)
5.6 Flow Sensors	257	(16)
5.6.1 Solid-Flow Measurement
5.6.2 Liquid Flow
Summary
Problems
6 OPTICAL SENSORS	273	(48)
Instructional Objectives	273	(1)
6.1 Introduction	273	(1)
6.2 Fundamentals of EM Radiation	274	(10)
6.2.1 Nature of EM Radiation
6.2.2 Characteristics of Light
6.2.3 Photometry
6.3 Photodetectors	284	(16)
6.3.1 Photodetector Characteristics
6.3.2 Photoconductive Detectors
6.3.3 Photovoltaic Detectors
6.3.4 Photodiode Detectors
6.3.5 Photoemissive Detectors
6.4 Pyrometry	300	(5)
6.4.1 Thermal Radiation
6.4.2 Broadband Pyrometers
6.4.3 Narrowband Pyrometers
6.5 Optical Sources	305	(6)
6.5.1 Conventional Light Sources
6.5.2 Laser Principles
6.6 Applications	311	(10)
6.6.1 Label Inspection
6.6.2 Turbidity
6.6.3 Ranging
Summary
Problems
7 FINAL CONTROL	321	(48)
Instructional Objectives	321	(1)
7.1 Introduction	321	(1)
7.2 Final Control Operation	322	(2)
7.2.1 Signal Conversions
7.2.2 Actutators
7.2.3 Control Element
7.3 Signal Conversions	324	(7)
7.3.1 Analog Electrical Signals
7.3.2 Digital Electrical Signals
7.3.3 Pneumatic Signals
7.4 Industrial Electronics	331	(10)
7.4.1 Silicon-Controlled Rectifier (SCR)
7.4.2 TRIAC
7.5 Actuators	341	(11)
7.5.1 Electrical Actuators
7.5.2 Pneumatic Actuators
7.5.3 Hydraulic Actuators
7.6 Control Elements	352	(17)
7.6.1 Mechanical
7.6.2 Electrical
7.6.3 Fluid Valves
Summary
Problems
8 DISCRETE-STATE PROCESS CONTROL	369	(42)
Instructional Objectives	369	(1)
8.1 Introduction	369	(1)
8.2 Definition of Discrete-State Process Control	370	(1)
8.3 Characteristics of the System	371	(14)
8.3.1 Discrete-State Variables
8.3.2 Process Specifications
8.3.3 Event Sequence Description
8.4 Relay Controllers and Ladder Diagrams	385	(10)
8.4.1 Background
8.4.2 Ladder Diagram Elements
8.4.3 Ladder Diagram Examples
8.5 Programmable Logic Controllers (PLCs)	395	(16)
8.5.1 Relay Sequencers
8.5.2 Programmable Logic Controller Design
8.5.3 PLC Operation
8.5.4 Programming
8.5.5 Advanced Features
Summary
Problems
9 CONTROLLER PRINCIPLES	411	(42)
Instructional Objectives	411	(1)
9.1 Introduction	411	(1)
9.2 Process Characteristics	412	(2)
9.2.1 Process Equation
9.2.2 Process Load
9.2.3 Process Lag
9.2.4 Self-Regulation
9.3 Control System Parameters	414	(6)
9.3.1 Error
9.3.2 Variable Range
9.3.3 Control Parameter Range
9.3.4 Control Lag
9.3.5 Dead Time
9.3.6 Cycling
9.3.7 Controller Modes
9.4 Discontinuous Controller Modes	420	(9)
9.4.1 Two-Position Mode
9.4.2 Multiposition Mode
9.4.3 Floating-Control Mode
9.5 Continuous Controller Modes	429	(9)
9.5.1 Proportional Control Mode
9.5.2 Integral Control Mode
9.5.3 Derivative Control Mode
9.6 Composite Control Modes	438	(15)
9.6.1 Proportional-Integral Control (PI)
9.6.2 Proportional-Derivative Control Mode (PD)
9.6.3 Three-Mode Controller (PID)
9.6.4 Special Terminology
Summary
Problems
10 ANALOG CONTROLLERS	453	(38)
Instructional Objectives	453	(1)
10.1 Introduction	453	(1)
10.2 General Features	454	(1)
10.3 Electronic Controllers	455	(22)
10.3.1 Error Detector
10.3.2 Single Mode
10.3.3 Composite Controller Modes
10.4 Pneumatic Controllers	477	(5)
10.4.1 General Features
10.4.2 Mode Implementation
10.5 Design Considerations	482	(9)
Summary
Problems
11 DIGITAL CONTROLLERS	491	(50)
Instructional Objectives	491	(1)
11.1 Introduction	491	(1)
11.2 Digital Electronics Methods	492	(5)
11.2.1 Simple Alarms
11.2.2 Two-Position Control
11.2.3 Multivariable Alarms
11.3 Computers in Process Control	497	(13)
11.3.1 Programmable Logic Controllers
11.3.2 Data Logging
11.3.3 Supervisory Control
11.3.4 Computer-Based Controller
11.4 Characteristics of Digital Data	510	(5)
11.4.1 Digitized Value
11.4.2 Sampled Data Systems
11.5 Controller Software	515	(16)
11.5.1 Software Format
11.5.2 Input Data Operations
11.5.3 Controller Modes
11.6 Computer Controller Examples	531	(10)
Summary
Problems
12 CONTROL-LOOP CHARACTERISTICS	541	(40)
Instructional Objectives	541	(1)
12.1 Introduction	541	(1)
12.2 Control System Configurations	542	(5)
12.2.1 Single Variable
12.2.2 Cascade Control
12.3 Multivariable Control Systems	547	(2)
12.3.1 Analog Control
12.3.2 Supervisory and Direct Digital Control
12.4 Control System Quality	549	(8)
12.4.1 Definition of Quality
12.4.2 Measure of Quality
12.5 Stability	557	(5)
12.5.1 Transfer Function Frequency Dependence
12.5.2 Stability Criteria
12.6 Process Loop Tuning	562	(19)
12.6.1 Open-Loop Transient Response Method
12.6.2 Ziegler-Nichols Method
12.6.3 Frequency Response Methods
Summary
Problems
APPENDIXES	581	(38)
REFERENCES	619	(2)
GLOSSARY	621	(4)
SOLUTIONS TO THE ODD-NUMBERED PROBLEMS	625	(48)
INDEX	673