Chapter 8: Fractionators and Absorbers

8.1.1Fractionation and Absorber related references6
8.2Distillation fundamentals6
8.2.1Process Design Software6
8.2.2Hydraulic Design6
8.2.4Relative Volatility (?)7
8.3Process Design10
8.4Selection of Trays and Packing11
8.4.1Packings versus Trays11
8.4.2Packed towers12
8.4.3Trayed Towers12
8.4.4Tray and Packing characteristics13
8.5Design of Trayed Columns14
8.5.1Noteworthy Point15
8.6The Design of a Distillation Column16
8.6.1Selection of Key Components in Feed17 volatility of binary liquid mixtures17 volatility of multi-component mixtures18 of temperature or pressure on relative volatility18
8.6.2Understanding the Nature of Chemical Constituents20
8.6.3Establishing the design basis of distillation20
8.6.4Selection of operating pressure of column21
8.7Binary Fractionation25
8.7.1Nomenclature and Subscripts25
8.7.2Tools for Distillation Analysis26
8.7.3Envelope Technique26 Distillation Material Balances27
8.8.2Equilibrium Line Equations30
8.8.3Non-Ideal Systems31
8.9McCabe-Thiele Diagram32
8.9.2Equilibrium Curve33
8.9.3Operating Lines33
8.9.4Physical Meaning of Points on McCabe-Thiele34 Conditions35 Tray36
8.9.5Minimum Reflux/Infinite Trays38
8.10Ruheman-Ponchon-Savarit Graphical Method39
8.10.1Distillation in Enriching Section of Tower40
8.10.2Distillation in Stripping Section of Tower41 section42 section43
8.11Analytical Techniques46
8.11.1Minimum Reflux/Infinite Trays46
8.11.2Minimum Trays/Total Reflux47
8.11.3Feed Tray47
8.11.4Design Reflux and Trays49
8.12Tray Efficiency50
8.13Multi-Component Distillation Design50
8.13.2Shortcut Method in Multicomponent Distillation51
8.13.3Rigorous Multicomponent Distillation Methods52
8.13.4Columns Sequencing Approach for Multicomponent distillation53
8.13.5Tray-To-Tray Calculation Approach for Multicomponent Distillation54 Reflux and Trays55 Parameters56–to–Tray Calculation60 Molal Overflow Procedure62 with Heat Balance62
8.14Absorption and Stripping64
8.15Absorbers and Strippers – Simplified Kremser Approach78
8.15.1Absorber or stripper with components in lean oil or stripping gas79
8.17Designing a Column83
8.18Tray Sizing84
8.18.1Preliminary Diameter Estimate85
8.18.2Tray Spacing85
8.18.3Number of Passes86
8.18.4Swaging of Towers86
8.19Steam Distillation87
8.20Column Internal Design Guidelines93
8.20.1Selecting the Controlling Case94
8.20.2Tray Count and Tower Layout95
8.20.3Types of trays95 of Choice of Column Internals96
8.20.4Hydraulic Parameters105 Flooding106 Backup107
8.20.5Geometric Parameters111 Configurations111 Pass Tray112 Pass Tray113 Pass Trays114 Pass Tray115 on Tray Configurations117 Action118 Height, Length, Type and Swept Back Weirs118
8.20.6Important Formulae Used in Sieve and Valve Trays Design126 Backup – Clear Liquid126 Downcomer Backup126 Tray or Wet Tray Pressure Drop126 Crest127 Loss under Downcomer127 over Weir128 Baffles128 and Zh128 Considerations for Four-Pass Tray Designs128
8.20.7Feed and Draw for Trayed Towers129 Sizing129 and Bottom Compartments164 Types164
8.20.8Tower Bottom Arrangements168 classifications168 Compartments174
8.20.9Other Topics214
8.21Tray Efficiencies and Turndown222
8.21.1Tray Efficiencies222
8.21.2Murphree Efficiency222
8.21.3Overall Efficiency223
8.21.4Derating (‘system’) factors227
8.21.6Tray hydraulic design procedure and guidelines230
8.21.7Tips on Balancing Trays231
8.22Flow regimes231
8.22.1Stability Limits232
8.23Tower System Design Pressure, Temperature Determination235
8.23.1Approach to Determining Design Pressure & Temperature236
8.24Packed Columns237
8.24.1Design of Packed Columns237
8.24.2Packed Tower Sizing Strategy244
8.24.3Example of Bid Evaluation Report for Packed Tower244
8.25Tower Packings250
8.25.1Random Packings250
8.25.2Structured Packings256
8.25.3Grid Packings258
8.25.4Packing Selection259
8.25.5Packing Hydraulics261 Wetting Rates261 and Flooding262 Drop263 Holdup265 Vapor Rate266 and Safety Factor266 Considerations266 and Thickness of Packings267
8.25.6Random Packing Efficiency267 of Packing Efficiency267 of Random Packing Efficiency Estimate269 of Packing Efficiency269 Models for Random Packing Efficiency272 Considerations of Random Packing HETP275 Packing Efficiency276 of Structured Packing Efficiencies278 of Thumb for HETP for structured packing278 Affecting HETP of Structured Packings281 Considerations of Structured Packing HETP282 Considerations of Structured Packing HETP283
8.26Liquid Distribution283
8.26.1Liquid Distribution and Redistribution283
8.26.2Liquid Distribution Quality284
8.26.3Types of Liquid Distributors287 Distributor Selection290 Arrangement for Liquid Distribution Devices299 Distributor Models from Major Vendors301 Distributor Assessment302 for Structured and Grid Packings304 of Liquid Distributors304 Devices307 Liquid Draw-Off309
8.26.4Draw Nozzle Sizing313
8.26.5Support Plates317
8.27Datasheet Preparation320
8.27.1Column Datasheets320
8.28Specialized Services323
8.29Distillation Examples324
8.30Go-By Column Data Sheets and Tray Data Sheets388