Chapter 4: Compressors

4.1Introduction4
4.1.1Compressors related important references4
4.1.2Industry Codes and Standards4
4.2Compressor Types5
4.3Compressor Selection6
4.4Centrifugal / Axial Compressor Selection11
4.4.1Advantages Attributed to Centrifugal Compressors11
4.4.2Limitations of Centrifugal Compressors12
4.4.3Axial Compressor Advantages13
4.4.4Axial Compressor Disadvantages13
4.4.5Dynamic compressor components and functions16
4.4.6Thermodynamic Equations for Gas Compression18
4.4.7Head Calculation20
4.4.8Polytropic Efficiency21
4.4.9Compressor Discharge Temperature22
4.4.10Power Requirements22
4.4.11Mollier Diagram Method23
4.4.11.1Application of Mollier Diagram24
4.4.12Casing Arrangements28
4.4.13Performance Curves for Centrifugal and Axial Compressors30
4.4.13.1Actual Volume32
4.4.14Fan Laws33
4.4.15Axial Compressor Basic Theory34
4.4.16Efficiency of an Operating Machine34
4.4.17Example of calculation of gas properties37
4.4.18Centrifugal Compressor Calculation Examples42
4.4.19Axial Compressors Sizing Example46
4.4.20Glossary for Centrifugal / Axial Compressor49
4.5Reciprocating Compressor Selection52
4.5.1Principle of Operation52
4.5.2Lubrication56
4.5.3Advantages Attributed to Reciprocating Compressors58
4.5.4Limitations of Reciprocating Compressors58
4.5.5Pulsation Control in Reciprocating compressors60
4.5.6Performance Calculations for Reciprocating compressor60
4.5.6.1Intercoolers62
4.5.6.2Volumetric Efficiency62
4.5.6.3Power Calculation for reciprocating compressor65
4.5.6.4Typical Compression ratios67
4.5.6.5Size ratings for reciprocating compressors68
4.5.7Reciprocating Compressor Calculations68
4.5.8Glossary for Reciprocating Compressor77
4.6Rotary Compressor Selection80
4.6.1Rotary compressors- general design considerations86
4.7Specialized Compression Equipment92
4.7.1Ejectors92
4.7.2Diaphragm Compressor92
4.7.3Scroll Compressor93
4.8Miscellaneous Parts for Compressors95
4.8.1Couplings95
4.8.2Gears98
4.8.3Bearings99
4.8.3.1Bearing Lubrication101
4.8.4Packing Glands105
4.8.5Compressor Seals105
4.8.6Vibration Monitoring Techniques112
4.9Definitions and Formulae114
4.10Process Datasheet Preparation118
4.10.1Design Cases119
4.10.2Specification of Overdesign Factor119
4.10.3Fluid Properties119
4.10.4Setting Compression Ratios120
4.10.5Process Staging120
4.10.6Compressor Efficiency121
4.10.7Sparing Philosophy121
4.10.8Design Pressure and Temperature122
4.11Process Control123
4.11.1Centrifugal Compressors123
4.11.1.1Phenomena of Surge in Centrifugal compressors123
4.11.1.2Antisurge Control for Compressed Air Centrifugal Compressors130
4.11.1.3Stonewall131
4.11.1.4Centrifugal Compressor Control131
4.11.2Axial Compressor Control137
4.11.3Reciprocating Compressors Process Control140
4.11.4Screw Compressors Process Control141
4.12Determination of Design Pressure in Centrifugal
Compressor System
143
4.13References149