Gas Treating
Absorption Theory and Practice
1. Auflage Oktober 2014
440 Seiten, Hardcover
Wiley & Sons Ltd
ISBN:
978-1-118-87773-9
John Wiley & Sons
Gas Treating: Absorption Theory and Practice provides an introduction to the treatment of natural gas, synthesis gas and flue gas, addressing why it is necessary and the challenges involved. The book concentrates in particular on the absorption-desorption process and mass transfer coupled with chemical reaction.
Following a general introduction to gas treatment, the chemistry of CO2, H2S and amine systems is described, and selected topics from physical chemistry with relevance to gas treating are presented. Thereafter the absorption process is discussed in detail, column hardware is explained and the traditional mass transfer model mechanisms are presented together with mass transfer correlations. This is followed by the central point of the text in which mass transfer is combined with chemical reaction, highlighting the associated possibilities and problems. Experimental techniques, data analysis and modelling are covered, and the book concludes with a discussion on various process elements which are important in the absorption-desorption process, but are often neglected in its treatment. These include heat exchange, solution management, process flowsheet variations, choice of materials and degradation of absorbents. The text is rounded off with an overview of the current state of research in this field and a discussion of real-world applications.
This book is a practical introduction to gas treating for practicing process engineers and chemical engineers working on purification technologies and gas treatment, in particular, those working on CO2 abatement processes, as well as post-graduate students in process engineering, chemical engineering and chemistry.
Preface xvii
List of Abbreviations xxi
Nomenclature List xxv
1. Introduction 1
1.1 Definitions 1
1.2 Gas Markets, Gas Applications and Feedstock 3
1.3 Sizes 3
1.4 Units 4
1.5 Ambient Conditions 7
1.6 Objective of This Book 7
1.7 Example Problems 7
References 13
2. Gas Treating in General 15
2.1 Introduction 15
2.2 Process Categories 16
2.3 Sulfur Removal 37
2.4 Absorption Process 43
References 45
3. Rate of Mass Transfer 49
3.1 Introduction 49
3.2 The Rate Equation 50
3.3 Co-absorption and/or Simultaneous Desorption 51
3.4 Convection and Diffusion 51
3.5 Heat Balance 51
3.6 Axially along the Column 52
3.7 Flowsheet Simulators 52
3.8 Rate versus Equilibrium Approaches 53
Further Reading 53
4. Chemistry in Acid Gas Treating 55
4.1 Introduction 55
4.2 'Chemistry' 57
4.3 Acid Character of CO2 and H2S 63
4.4 The H2S Chemistry with any Alkanolamine 65
4.5 Chemistry of CO2 with Primary and Secondary Alkanolamines 65
4.6 The Chemistry of Tertiary Amines 72
4.7 Chemistry of the Minor Sulfur Containing Gases 73
4.8 Sterically Hindered Amines 78
4.9 Hot Carbonate Absorbent Systems 80
4.10 Simultaneous Absorption of H2S and CO2 82
4.11 Reaction Mechanisms and Activators-Final Words 82
4.12 Review Questions, Problems and Challenges 82
References 83
5. Physical Chemistry Topics 87
5.1 Introduction 87
5.2 Discussion of Solvents 87
5.3 Acid-Base Considerations 90
5.4 The Amine-CO2 Buffer System 98
5.5 Gas Solubilities, Henry's and Raoult's Laws 100
5.6 Solubilities of Solids 105
5.7 N2O Analogy 105
5.8 Partial Molar Properties and Representation 106
5.9 Hydration and Hydrolysis 107
5.10 Solvation 107
References 108
6. Diffusion 111
6.1 Dilute Mixtures 111
6.2 Concentrated Mixtures 114
6.3 Values of Diffusion Coefficients 116
6.4 Interacting Species 121
6.5 Interaction with Surfaces 122
6.6 Multicomponent Situations 122
6.7 Examples 122
References 125
Further Reading 126
7. Absorption Column Mass Transfer Analysis 127
7.1 Introduction 127
7.2 The Column 128
7.3 The Flux Equations 128
7.4 The Overall Mass Transfer Coefficients and the Interface 129
7.5 Control Volumes, Mass and Energy - Balances 132
7.6 Analytical Solution and Its Limitations 135
7.7 The NTU-HTU Concept 137
7.8 Operating and Equilibrium Lines - A Graphical Representation 138
7.9 Other Concentration Units 139
7.10 Concentrated Mixtures and Simultaneous Absorption 140
7.11 Liquid or Gas Side Control? A Few Pointers 143
7.12 The Equilibrium Stage Alternative Approach 144
7.13 Co-absorption in a Defined Column 145
7.14 Numerical Examples 146
Numerical Integration 149
References 151
8. Column Hardware 153
8.1 Introduction 153
8.2 Packings 154
8.3 Packing Auxiliaries 162
8.4 Tray Columns and Trays 165
8.5 Spray Columns 170
8.6 Demisters 170
8.7 Examples 173
References 178
Further Reading 179
9. Rotating Packed Beds 181
9.1 Introduction 181
9.2 Flooding and Pressure Drop 183
9.3 Fluid Flow 184
9.4 Mass Transfer Correlations 184
9.5 Application to Gas Treating 187
9.6 Other Salient Points 189
9.7 Challenges Associated with Rotating Packed Beds 189
References 189
10. Mass Transfer Models 193
10.1 The Film Model 193
10.2 Penetration Theory 195
10.3 Surface Renewal Theory 197
10.4 Boundary Layer Theory 198
10.5 Eddy Diffusion, 'Film-Penetration' and More 198
References 199
11. Correlations for Mass Transfer Coefficients 201
11.1 Introduction 201
11.2 Packings: Generic Considerations 201
11.3 Random Packings 202
11.4 Structured Packings 206
11.5 Packed Column Correlations 206
11.6 Tray Columns 211
11.7 Examples 212
References 218
Further Reading 221
12. Chemistry and Mass Transfer 223
12.1 Background 223
12.2 Equilibrium or Kinetics 223
12.3 Diffusion with Chemical Reaction 225
12.4 Reaction Regimes Related to Mass Transfer 226
12.5 Enhancement Factors 243
12.6 Arbitrary, Reversible Reactions and/or Parallel Reactions 246
12.7 Software 247
12.8 Numerical Examples 248
References 253
Further Reading 254
13. Selective Absorption of H2S 255
13.1 Background 255
13.2 Theoretical Discussion of Rate Based Selectivity 256
13.3 What Fundamental Information is Available in the Literature? 258
13.4 Process Options and Industrial Practice 260
13.5 Key Design Points 262
13.6 Process Intensification 262
13.7 Numerical Example 262
References 264
14. Gas Dehydration 267
14.1 Background 267
14.2 Dehydration Options 268
14.3 Glycol Based Processes 269
14.4 Contaminants and Countermeasures 273
14.5 Operational Problems 274
14.6 TEG Equilibrium Data 274
14.7 Hydrate Inhibition in Pipelines 276
14.8 Determination of Water 276
14.9 Example Problems 277
References 280
15. Experimental Techniques 283
15.1 Introduction 283
15.2 Experimental Design 283
15.3 Laminar Jet 285
15.4 Wetted Wall 289
15.5 Single Sphere 291
15.6 Stirred Cell 293
15.7 Stopped Flow 295
15.8 Other Mass Transfer Methods Less Used 298
15.9 Other Techniques in Gas-Liquid Mass Transfer 300
15.10 Equilibrium Measurements 300
15.11 Data Interpretation and Sub-Models 303
References 303
16. Absorption Equilibria 307
16.1 Introduction 307
16.2 Fundamental Relations 308
16.3 Literature Data Reported 311
16.4 Danckwerts-McNeil 312
16.5 Kent-Eisenberg 313
16.6 Deshmukh-Mather 313
16.7 Electrolyte NRTL (Austgen-Bishnoi-Chen-Rochelle) 314
16.8 Li-Mather 314
16.9 Extended UNIQUAC 315
16.10 EoS - SAFT 315
16.11 Other Models 316
References 316
17. Desorption 319
17.1 Introduction 319
17.2 Chemistry of Desorption 322
17.3 Kinetics of Reaction 324
17.4 Bubbling Desorption 325
17.5 Desorption Process Analysis and Modelling 327
17.6 Unconventional Approaches to Desorption 328
References 329
18. Heat Exchangers 333
18.1 Introduction 333
18.2 Reboiler 333
18.3 Desorber Overhead Condenser 337
18.4 Economiser or Lean/Rich Heat Exchanger 338
18.5 Amine Cooler 341
18.6 Water Wash Circulation Cooler 341
18.7 Heat Exchanger Alternatives 341
References 342
Further Reading 343
19. Solution Management 345
19.1 Introduction 345
19.2 Contaminant Problem 346
19.3 Feed Gas Pretreatment 346
19.4 Rich Absorbent Flash 348
19.5 Filter 348
19.6 Reclaiming 351
19.7 Chemicals to Combat Foaming 353
19.8 Corrosion Inhibitors 355
19.9 Waste Handling 355
19.10 Solution Containment 355
19.11 Water Balance 355
19.12 Cleaning the Plant Equipment 356
19.13 Final Words on Solution Management 356
References 356
20. Absorption-Desorption Cycle 359
20.1 The Cycle and the Dimensioning Specifications 359
20.2 Alternative Cycle Variations 362
20.3 Other Limitations 364
20.4 Matching Process and Treating Demands 365
20.5 Solution Management 366
20.6 Flowsheet Variations to Save Desorption Energy 368
References 369
21. Degradation 371
21.1 Introduction to Degradation 371
21.2 Carbamate Polymerisation 372
21.3 Thermal Degradation 372
21.4 Oxidative Degradation 373
21.5 Corrosion and Degradation 373
21.6 The Effect of Heat Stable Salts (HSSs) 373
21.7 SOx and NOx in Feed Gas 373
21.8 Nitrosamines 374
21.9 Concluding Remarks 374
References 374
22. Materials, Corrosion, Inhibitors 375
22.1 Introduction 375
22.2 Corrosion Basics 376
22.3 Gas Phase 377
22.4 Protective Layers and What Makes Them Break Down (Chemistry) 378
22.5 Fluid Velocities and Corrosion 378
22.6 Stress Induced Corrosion 379
22.7 Effect of Heat Stable Salts (HSS) 379
22.8 Inhibitors 379
22.9 Problem Areas, Observations and Mitigation Actions 380
References 380
23. Technological Fronts 383
23.1 Historical Background 383
23.2 Fundamental Understanding and Absorbent Trends 384
23.3 Natural Gas Treating 385
23.4 Syngas Treating 385
23.5 Flue Gas Treating 386
23.6 Where Are We Heading? 386
References 387
24. Flue Gas Treating 389
24.1 Introduction 389
24.2 Pressure Drop and Size Issues 390
24.3 Absorbent Degradation 390
24.4 Treated Gas as Effluent 390
24.5 CO2 Export Specification 391
24.6 Energy Implications 391
24.7 Cost Issues 392
24.8 The Greenhouse Gas Problem 394
References 396
Web Sites 396
25. Natural Gas Treating (and Syngas) 397
25.1 Introduction 397
25.2 Gas Export Specification 398
25.3 Natural Gas Contaminants and Foaming 398
25.4 Hydrogen Sulfide 399
25.5 Regeneration by Flash 399
25.6 Choice of Absorbents 399
Further Reading 400
26. Treating in Various Situations 401
26.1 Introduction and Environmental Perspective 401
26.2 End of Pipe Solutions 401
26.3 Sulfur Dioxide 402
26.4 Nitrogen Oxides 402
26.5 Dusts and Aerosols 403
26.6 New Challenges 403
Index 405
List of Abbreviations xxi
Nomenclature List xxv
1. Introduction 1
1.1 Definitions 1
1.2 Gas Markets, Gas Applications and Feedstock 3
1.3 Sizes 3
1.4 Units 4
1.5 Ambient Conditions 7
1.6 Objective of This Book 7
1.7 Example Problems 7
References 13
2. Gas Treating in General 15
2.1 Introduction 15
2.2 Process Categories 16
2.3 Sulfur Removal 37
2.4 Absorption Process 43
References 45
3. Rate of Mass Transfer 49
3.1 Introduction 49
3.2 The Rate Equation 50
3.3 Co-absorption and/or Simultaneous Desorption 51
3.4 Convection and Diffusion 51
3.5 Heat Balance 51
3.6 Axially along the Column 52
3.7 Flowsheet Simulators 52
3.8 Rate versus Equilibrium Approaches 53
Further Reading 53
4. Chemistry in Acid Gas Treating 55
4.1 Introduction 55
4.2 'Chemistry' 57
4.3 Acid Character of CO2 and H2S 63
4.4 The H2S Chemistry with any Alkanolamine 65
4.5 Chemistry of CO2 with Primary and Secondary Alkanolamines 65
4.6 The Chemistry of Tertiary Amines 72
4.7 Chemistry of the Minor Sulfur Containing Gases 73
4.8 Sterically Hindered Amines 78
4.9 Hot Carbonate Absorbent Systems 80
4.10 Simultaneous Absorption of H2S and CO2 82
4.11 Reaction Mechanisms and Activators-Final Words 82
4.12 Review Questions, Problems and Challenges 82
References 83
5. Physical Chemistry Topics 87
5.1 Introduction 87
5.2 Discussion of Solvents 87
5.3 Acid-Base Considerations 90
5.4 The Amine-CO2 Buffer System 98
5.5 Gas Solubilities, Henry's and Raoult's Laws 100
5.6 Solubilities of Solids 105
5.7 N2O Analogy 105
5.8 Partial Molar Properties and Representation 106
5.9 Hydration and Hydrolysis 107
5.10 Solvation 107
References 108
6. Diffusion 111
6.1 Dilute Mixtures 111
6.2 Concentrated Mixtures 114
6.3 Values of Diffusion Coefficients 116
6.4 Interacting Species 121
6.5 Interaction with Surfaces 122
6.6 Multicomponent Situations 122
6.7 Examples 122
References 125
Further Reading 126
7. Absorption Column Mass Transfer Analysis 127
7.1 Introduction 127
7.2 The Column 128
7.3 The Flux Equations 128
7.4 The Overall Mass Transfer Coefficients and the Interface 129
7.5 Control Volumes, Mass and Energy - Balances 132
7.6 Analytical Solution and Its Limitations 135
7.7 The NTU-HTU Concept 137
7.8 Operating and Equilibrium Lines - A Graphical Representation 138
7.9 Other Concentration Units 139
7.10 Concentrated Mixtures and Simultaneous Absorption 140
7.11 Liquid or Gas Side Control? A Few Pointers 143
7.12 The Equilibrium Stage Alternative Approach 144
7.13 Co-absorption in a Defined Column 145
7.14 Numerical Examples 146
Numerical Integration 149
References 151
8. Column Hardware 153
8.1 Introduction 153
8.2 Packings 154
8.3 Packing Auxiliaries 162
8.4 Tray Columns and Trays 165
8.5 Spray Columns 170
8.6 Demisters 170
8.7 Examples 173
References 178
Further Reading 179
9. Rotating Packed Beds 181
9.1 Introduction 181
9.2 Flooding and Pressure Drop 183
9.3 Fluid Flow 184
9.4 Mass Transfer Correlations 184
9.5 Application to Gas Treating 187
9.6 Other Salient Points 189
9.7 Challenges Associated with Rotating Packed Beds 189
References 189
10. Mass Transfer Models 193
10.1 The Film Model 193
10.2 Penetration Theory 195
10.3 Surface Renewal Theory 197
10.4 Boundary Layer Theory 198
10.5 Eddy Diffusion, 'Film-Penetration' and More 198
References 199
11. Correlations for Mass Transfer Coefficients 201
11.1 Introduction 201
11.2 Packings: Generic Considerations 201
11.3 Random Packings 202
11.4 Structured Packings 206
11.5 Packed Column Correlations 206
11.6 Tray Columns 211
11.7 Examples 212
References 218
Further Reading 221
12. Chemistry and Mass Transfer 223
12.1 Background 223
12.2 Equilibrium or Kinetics 223
12.3 Diffusion with Chemical Reaction 225
12.4 Reaction Regimes Related to Mass Transfer 226
12.5 Enhancement Factors 243
12.6 Arbitrary, Reversible Reactions and/or Parallel Reactions 246
12.7 Software 247
12.8 Numerical Examples 248
References 253
Further Reading 254
13. Selective Absorption of H2S 255
13.1 Background 255
13.2 Theoretical Discussion of Rate Based Selectivity 256
13.3 What Fundamental Information is Available in the Literature? 258
13.4 Process Options and Industrial Practice 260
13.5 Key Design Points 262
13.6 Process Intensification 262
13.7 Numerical Example 262
References 264
14. Gas Dehydration 267
14.1 Background 267
14.2 Dehydration Options 268
14.3 Glycol Based Processes 269
14.4 Contaminants and Countermeasures 273
14.5 Operational Problems 274
14.6 TEG Equilibrium Data 274
14.7 Hydrate Inhibition in Pipelines 276
14.8 Determination of Water 276
14.9 Example Problems 277
References 280
15. Experimental Techniques 283
15.1 Introduction 283
15.2 Experimental Design 283
15.3 Laminar Jet 285
15.4 Wetted Wall 289
15.5 Single Sphere 291
15.6 Stirred Cell 293
15.7 Stopped Flow 295
15.8 Other Mass Transfer Methods Less Used 298
15.9 Other Techniques in Gas-Liquid Mass Transfer 300
15.10 Equilibrium Measurements 300
15.11 Data Interpretation and Sub-Models 303
References 303
16. Absorption Equilibria 307
16.1 Introduction 307
16.2 Fundamental Relations 308
16.3 Literature Data Reported 311
16.4 Danckwerts-McNeil 312
16.5 Kent-Eisenberg 313
16.6 Deshmukh-Mather 313
16.7 Electrolyte NRTL (Austgen-Bishnoi-Chen-Rochelle) 314
16.8 Li-Mather 314
16.9 Extended UNIQUAC 315
16.10 EoS - SAFT 315
16.11 Other Models 316
References 316
17. Desorption 319
17.1 Introduction 319
17.2 Chemistry of Desorption 322
17.3 Kinetics of Reaction 324
17.4 Bubbling Desorption 325
17.5 Desorption Process Analysis and Modelling 327
17.6 Unconventional Approaches to Desorption 328
References 329
18. Heat Exchangers 333
18.1 Introduction 333
18.2 Reboiler 333
18.3 Desorber Overhead Condenser 337
18.4 Economiser or Lean/Rich Heat Exchanger 338
18.5 Amine Cooler 341
18.6 Water Wash Circulation Cooler 341
18.7 Heat Exchanger Alternatives 341
References 342
Further Reading 343
19. Solution Management 345
19.1 Introduction 345
19.2 Contaminant Problem 346
19.3 Feed Gas Pretreatment 346
19.4 Rich Absorbent Flash 348
19.5 Filter 348
19.6 Reclaiming 351
19.7 Chemicals to Combat Foaming 353
19.8 Corrosion Inhibitors 355
19.9 Waste Handling 355
19.10 Solution Containment 355
19.11 Water Balance 355
19.12 Cleaning the Plant Equipment 356
19.13 Final Words on Solution Management 356
References 356
20. Absorption-Desorption Cycle 359
20.1 The Cycle and the Dimensioning Specifications 359
20.2 Alternative Cycle Variations 362
20.3 Other Limitations 364
20.4 Matching Process and Treating Demands 365
20.5 Solution Management 366
20.6 Flowsheet Variations to Save Desorption Energy 368
References 369
21. Degradation 371
21.1 Introduction to Degradation 371
21.2 Carbamate Polymerisation 372
21.3 Thermal Degradation 372
21.4 Oxidative Degradation 373
21.5 Corrosion and Degradation 373
21.6 The Effect of Heat Stable Salts (HSSs) 373
21.7 SOx and NOx in Feed Gas 373
21.8 Nitrosamines 374
21.9 Concluding Remarks 374
References 374
22. Materials, Corrosion, Inhibitors 375
22.1 Introduction 375
22.2 Corrosion Basics 376
22.3 Gas Phase 377
22.4 Protective Layers and What Makes Them Break Down (Chemistry) 378
22.5 Fluid Velocities and Corrosion 378
22.6 Stress Induced Corrosion 379
22.7 Effect of Heat Stable Salts (HSS) 379
22.8 Inhibitors 379
22.9 Problem Areas, Observations and Mitigation Actions 380
References 380
23. Technological Fronts 383
23.1 Historical Background 383
23.2 Fundamental Understanding and Absorbent Trends 384
23.3 Natural Gas Treating 385
23.4 Syngas Treating 385
23.5 Flue Gas Treating 386
23.6 Where Are We Heading? 386
References 387
24. Flue Gas Treating 389
24.1 Introduction 389
24.2 Pressure Drop and Size Issues 390
24.3 Absorbent Degradation 390
24.4 Treated Gas as Effluent 390
24.5 CO2 Export Specification 391
24.6 Energy Implications 391
24.7 Cost Issues 392
24.8 The Greenhouse Gas Problem 394
References 396
Web Sites 396
25. Natural Gas Treating (and Syngas) 397
25.1 Introduction 397
25.2 Gas Export Specification 398
25.3 Natural Gas Contaminants and Foaming 398
25.4 Hydrogen Sulfide 399
25.5 Regeneration by Flash 399
25.6 Choice of Absorbents 399
Further Reading 400
26. Treating in Various Situations 401
26.1 Introduction and Environmental Perspective 401
26.2 End of Pipe Solutions 401
26.3 Sulfur Dioxide 402
26.4 Nitrogen Oxides 402
26.5 Dusts and Aerosols 403
26.6 New Challenges 403
Index 405
Dag A. Eimer
Tel-Tek and Telemark University College, Norway
Tel-Tek and Telemark University College, Norway
