Chapter 15: Vacuum Systems

15.1 Introduction 3
15.1.1 Vacuum equipment related important references 3
15.1.2 Vacuum Definition 3
15.1.2.1 Vacuum measurement 4
15.1.2.2 Industrial vacuum systems 5
15.2 Vacuum equipment terminology 7
15.2.1 Suction pressure 7
15.2.2 Discharge pressure 8
15.2.3 Capacity of the unit 8
15.2.4 Air leakage 8
15.3 Types of Vacuum producing equipment 8
15.4 Vacuum pump selection 10
15.4.1 Time required to reach maximum vacuum 11
15.4.2 Vacuum at high altitudes 12
15.4.3 Mechanical Vacuum Pumps 12
15.4.3.1 Gas Transfer Pumps 14
15.4.3.2 Entrapment (Capture) Vacuum Pump 35
15.4.4 Jet Pumps and Ejectors 39
15.4.4.2 Gas-Gas Ejectors 42
15.4.4.3 Liquid-Gas Ejectors 42
15.4.4.4 Ejectors for Mass Transfer 43
15.4.4.5 Steam Ejectors 43
15.4.4.6 Estimating the Number of Stages 54
15.4.4.7 Water Vapour Associated with NC Gases 54
15.4.4.8 Estimation of Steam Consumption of Jets 55
15.4.4.9 Estimation of Water Consumption of Jets 55
15.4.4.10 Capacity of Steam Jets for Evacuation 57
15.5 Air leakage in vacuum vessels 60
15.5.1 Estimation of air leakage during design stage 61
15.6 Ejector Efficiency 70
15.6.1 Staging Ejectors 71
15.7.2 Ejector Ratings 72
15.7.3 Effect of MW and Temperature 75
15.7.4 Discharge Pressure 76
15.7.5 Changes in Steam Flow 76
15.7.6 Multi-stage Ejector Design 77
15.8 Control 77
15.9 Writing the Specifications 80
15.10 Process specification sheet 85
15.11 Go-by P&ID and layout 86
15.12 Glossary 88
15.13 References 90

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