Chapter 32: Automation and Control

32.1Introduction4
32.1.1Related references4
32.2Instrument & Control System – an Overview4
32.2.1Local Indicating Type Instruments4
32.2.2Remote Indicating Type Instruments4
32.2.3Instrument Control system6
32.2.4Control Room8
32.3Control Valves8
32.3.1Selection Criteria9
32.3.2Control Valve Sizing Criteria10
32.3.3Control Valve Data Sheet11
32.3.4Control Valve Selection Rules of Thumb12
32.4Process Instrumentation16
32.4.1Flow16
32.4.2Velocity Flowmeters22
32.4.3Inferential (differential pressure)25
32.4.4Positive Displacement Meters34
32.4.5Mass Flowmeters40
32.5Level Measurement47
32.5.1Level Sensor Selection48
32.5.2Types50
32.5.3Boiling & Cryogenic Fluids62
32.5.4Sludge, Foam, & Molten Metals63
32.6Temperature64
32.7Pressure Measurement Instrumentation68
32.8Specific Types of Control Systems70
32.8.1Process Controls70
32.8.1.1Flow Control70
32.8.1.2Level Control71
32.8.1.3Temperature Control71
32.8.1.4Pressure Controls74
32.9Alarm Systems74
32.9.1Direct Connected Alarms74
32.9.2Alarms from Transmitters76
32.9.3Alarms from DCS76
32.10Recording76
32.11Valves79
32.12Miscellaneous Systems, Loops and Hand Switching80
32.13Centrifugal Pump Control85
32.14Positive displacement pump control85
32.15Reciprocating Compressors Control Methods86
32.16Control Schemes for Screw Compressors88
32.17Control Schemes for Centrifugal Compressors88
32.18Distillation Column Control93
32.18.1Distillation Control Philosophy95
32.18.2Other possible disturbances98
32.19Column Control Fundamentals99
32.20The various types of distillation column control schemes101
32.20.1Atmospheric Column Control102
32.20.2Pressure Control102
32.20.3Temperature Control120
32.20.4Control of Column Top Composition124
32.20.5Feed Preheat Control126
32.20.6Reboiler and Steam Control to Column128
32.20.7Vapour Recompression130
32.20.8Distillation Column Control Examples131
32.21Constraint Control136
32.22Miscellaneous Controls137
32.23References138