Chapter 8: Fractionators and Absorbers
| 8.1 | Introduction | 6 |
| 8.1.1 | Fractionation and Absorber related references | 6 |
| 8.2 | Distillation fundamentals | 6 |
| 8.2.1 | Process Design Software | 6 |
| 8.2.2 | Hydraulic Design | 6 |
| 8.2.3 | Distillation | 6 |
| 8.2.4 | Relative Volatility (?) | 7 |
| 8.3 | Process Design | 10 |
| 8.4 | Selection of Trays and Packing | 11 |
| 8.4.1 | Packings versus Trays | 11 |
| 8.4.2 | Packed towers | 12 |
| 8.4.3 | Trayed Towers | 12 |
| 8.4.4 | Tray and Packing characteristics | 13 |
| 8.5 | Design of Trayed Columns | 14 |
| 8.5.1 | Noteworthy Point | 15 |
| 8.6 | The Design of a Distillation Column | 16 |
| 8.6.1 | Selection of Key Components in Feed | 17 |
| 8.6.1.1 | Relative volatility of binary liquid mixtures | 17 |
| 8.6.1.2 | Relative volatility of multi-component mixtures | 18 |
| 8.6.1.3 | Effect of temperature or pressure on relative volatility | 18 |
| 8.6.2 | Understanding the Nature of Chemical Constituents | 20 |
| 8.6.3 | Establishing the design basis of distillation | 20 |
| 8.6.4 | Selection of operating pressure of column | 21 |
| 8.7 | Binary Fractionation | 25 |
| 8.7.1 | Nomenclature and Subscripts | 25 |
| 8.7.2 | Tools for Distillation Analysis | 26 |
| 8.7.3 | Envelope Technique | 26 |
| 8.7.3.1 | Binary Distillation Material Balances | 27 |
| 8.8. | Equilibrium | 29 |
| 8.8.1 | Concept | 29 |
| 8.8.2 | Equilibrium Line Equations | 30 |
| 8.8.3 | Non-Ideal Systems | 31 |
| 8.9 | McCabe-Thiele Diagram | 32 |
| 8.9.1 | Introduction | 32 |
| 8.9.2 | Equilibrium Curve | 33 |
| 8.9.3 | Operating Lines | 33 |
| 8.9.4 | Physical Meaning of Points on McCabe-Thiele | 34 |
| 8.9.4.1 | Feed Conditions | 35 |
| 8.9.4.2 | Feed Tray | 36 |
| 8.9.5 | Minimum Reflux/Infinite Trays | 38 |
| 8.10 | Ruheman-Ponchon-Savarit Graphical Method | 39 |
| 8.10.1 | Distillation in Enriching Section of Tower | 40 |
| 8.10.2 | Distillation in Stripping Section of Tower | 41 |
| 8.10.2.1 | Rectifying section | 42 |
| 8.10.2.2 | Stripping section | 43 |
| 8.11 | Analytical Techniques | 46 |
| 8.11.1 | Minimum Reflux/Infinite Trays | 46 |
| 8.11.2 | Minimum Trays/Total Reflux | 47 |
| 8.11.3 | Feed Tray | 47 |
| 8.11.4 | Design Reflux and Trays | 49 |
| 8.12 | Tray Efficiency | 50 |
| 8.13 | Multi-Component Distillation Design | 50 |
| 8.13.1 | Introduction | 50 |
| 8.13.2 | Shortcut Method in Multicomponent Distillation | 51 |
| 8.13.3 | Rigorous Multicomponent Distillation Methods | 52 |
| 8.13.4 | Columns Sequencing Approach for Multicomponent distillation | 53 |
| 8.13.5 | Tray-To-Tray Calculation Approach for Multicomponent Distillation | 54 |
| 8.13.5.1 | Minimum Reflux and Trays | 55 |
| 8.13.5.2 | Design Parameters | 56 |
| 8.13.5.3 | Tray–to–Tray Calculation | 60 |
| 8.13.5.4 | Constant Molal Overflow Procedure | 62 |
| 8.13.5.5 | Procedure with Heat Balance | 62 |
| 8.14 | Absorption and Stripping | 64 |
| 8.15 | Absorbers and Strippers – Simplified Kremser Approach | 78 |
| 8.15.1 | Absorber or stripper with components in lean oil or stripping gas | 79 |
| 8.16 | Efficiency | 82 |
| 8.17 | Designing a Column | 83 |
| 8.18 | Tray Sizing | 84 |
| 8.18.1 | Preliminary Diameter Estimate | 85 |
| 8.18.2 | Tray Spacing | 85 |
| 8.18.3 | Number of Passes | 86 |
| 8.18.4 | Swaging of Towers | 86 |
| 8.19 | Steam Distillation | 87 |
| 8.20 | Column Internal Design Guidelines | 93 |
| 8.20.1 | Selecting the Controlling Case | 94 |
| 8.20.2 | Tray Count and Tower Layout | 95 |
| 8.20.3 | Types of trays | 95 |
| 8.20.3.1 | Overview of Choice of Column Internals | 96 |
| 8.20.4 | Hydraulic Parameters | 105 |
| 8.20.4.1 | Jet Flooding | 106 |
| 8.20.4.2 | Downcomer Backup | 107 |
| 8.20.5 | Geometric Parameters | 111 |
| 8.20.5.1 | Tray Configurations | 111 |
| 8.20.5.2 | One Pass Tray | 112 |
| 8.20.5.3 | Two Pass Tray | 113 |
| 8.20.5.4 | Three Pass Trays | 114 |
| 8.20.5.5 | Four Pass Tray | 115 |
| 8.20.5.6 | Discussion on Tray Configurations | 117 |
| 8.20.5.7 | Tray Action | 118 |
| 8.20.5.8 | Weir Height, Length, Type and Swept Back Weirs | 118 |
| 8.20.6 | Important Formulae Used in Sieve and Valve Trays Design | 126 |
| 8.20.6.1 | Downcomer Backup – Clear Liquid | 126 |
| 8.20.6.2 | Aerated Downcomer Backup | 126 |
| 8.20.6.3 | Total Tray or Wet Tray Pressure Drop | 126 |
| 8.20.6.4 | Weir Crest | 127 |
| 8.20.6.5 | Head Loss under Downcomer | 127 |
| 8.20.6.6 | Throw over Weir | 128 |
| 8.20.6.7 | Anti-Jump Baffles | 128 |
| 8.20.6.8 | Zf and Zh | 128 |
| 8.20.6.9 | Special Considerations for Four-Pass Tray Designs | 128 |
| 8.20.7 | Feed and Draw for Trayed Towers | 129 |
| 8.20.7.1 | Nozzle Sizing | 129 |
| 8.20.7.2 | Reboilers and Bottom Compartments | 164 |
| 8.20.7.2.1 | Reboiler Types | 164 |
| 8.20.8 | Tower Bottom Arrangements | 168 |
| 8.20.8.1 | Flow classifications | 168 |
| 8.20.8.2 | Reboiler Compartments | 174 |
| 8.20.9 | Other Topics | 214 |
| 8.21 | Tray Efficiencies and Turndown | 222 |
| 8.21.1 | Tray Efficiencies | 222 |
| 8.21.2 | Murphree Efficiency | 222 |
| 8.21.3 | Overall Efficiency | 223 |
| 8.21.4 | Derating (‘system’) factors | 227 |
| 8.21.5 | Turndown | 229 |
| 8.21.6 | Tray hydraulic design procedure and guidelines | 230 |
| 8.21.7 | Tips on Balancing Trays | 231 |
| 8.22 | Flow regimes | 231 |
| 8.22.1 | Stability Limits | 232 |
| 8.23 | Tower System Design Pressure, Temperature Determination | 235 |
| 8.23.1 | Approach to Determining Design Pressure & Temperature | 236 |
| 8.24 | Packed Columns | 237 |
| 8.24.1 | Design of Packed Columns | 237 |
| 8.24.2 | Packed Tower Sizing Strategy | 244 |
| 8.24.3 | Example of Bid Evaluation Report for Packed Tower | 244 |
| 8.25 | Tower Packings | 250 |
| 8.25.1 | Random Packings | 250 |
| 8.25.2 | Structured Packings | 256 |
| 8.25.3 | Grid Packings | 258 |
| 8.25.4 | Packing Selection | 259 |
| 8.25.5 | Packing Hydraulics | 261 |
| 8.25.5.1 | Minimum Wetting Rates | 261 |
| 8.25.5.2 | Loading and Flooding | 262 |
| 8.25.5.3 | Pressure Drop | 263 |
| 8.25.5.4 | Liquid Holdup | 265 |
| 8.25.5.5 | Minimum Vapor Rate | 266 |
| 8.25.5.6 | Foaming and Safety Factor | 266 |
| 8.25.5.7 | Other Considerations | 266 |
| 8.25.5.8 | Material and Thickness of Packings | 267 |
| 8.25.6 | Random Packing Efficiency | 267 |
| 8.25.6.1 | Concepts of Packing Efficiency | 267 |
| 8.25.6.2 | Procedure of Random Packing Efficiency Estimate | 269 |
| 8.25.6.3 | Data of Packing Efficiency | 269 |
| 8.25.6.4 | F.R.I. Models for Random Packing Efficiency | 272 |
| 8.25.6.5 | Rules-of-Thumb | 274 |
| 8.25.6.6 | Design Considerations of Random Packing HETP | 275 |
| 8.25.6.7 | Structured Packing Efficiency | 276 |
| 8.25.6.8 | Data of Structured Packing Efficiencies | 278 |
| 8.25.6.9 | Rules of Thumb for HETP for structured packing | 278 |
| 8.25.6.10 | Factors Affecting HETP of Structured Packings | 281 |
| 8.25.6.11 | General Considerations of Structured Packing HETP | 282 |
| 8.25.6.12 | General Considerations of Structured Packing HETP | 283 |
| 8.26 | Liquid Distribution | 283 |
| 8.26.1 | Liquid Distribution and Redistribution | 283 |
| 8.26.2 | Liquid Distribution Quality | 284 |
| 8.26.3 | Types of Liquid Distributors | 287 |
| 8.26.3.1 | Liquid Distributor Selection | 290 |
| 8.26.3.2 | Tower Arrangement for Liquid Distribution Devices | 299 |
| 8.26.3.3 | Liquid Distributor Models from Major Vendors | 301 |
| 8.26.3.4 | Liquid Distributor Assessment | 302 |
| 8.26.3.5 | Distributors for Structured and Grid Packings | 304 |
| 8.26.3.6 | Testing of Liquid Distributors | 304 |
| 8.26.3.7 | Feed Devices | 307 |
| 8.26.3.7 | Intermediate Liquid Draw-Off | 309 |
| 8.26.4 | Draw Nozzle Sizing | 313 |
| 8.26.5 | Support Plates | 317 |
| 8.27 | Datasheet Preparation | 320 |
| 8.27.1 | Column Datasheets | 320 |
| 8.28 | Specialized Services | 323 |
| 8.29 | Distillation Examples | 324 |
| 8.30 | Go-By Column Data Sheets and Tray Data Sheets | 388 |
| 8.31 | References | 396 |
Mihir’s Handbook at just USD 2.0/ebook (India: Rs.150/ebook)
