Handbook of Gasification Technology
Description
But gasification is not just used for fossil fuels. Waste products that would normally be dumped into landfills or otherwise disposed of can be converted into energy through the process of gasification. The same is true of biofeedstocks and other types of feedstocks, thus making another argument for the widespread use of gasification.
The Handbook of Gasification Technology covers all aspects of the gasification, in a "one-stop shop," from the basic science of gasification and why it is needed to the energy sources, processes, chemicals, materials, and machinery used in the technology. Whether a veteran engineer or scientist using it as a reference or a professor using it as a textbook, this outstanding new volume is a must-have for any library.
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James G. Speight, PhD, has more than forty-five years of experience in energy, environmental science, and ethics. He is the author of more than 65 books in petroleum science, petroleum engineering, biomass and biofuels, and environmental sciences. Although he has always worked in private industry which focused on contract-based work, Dr. Speight has served as Adjunct Professor in the Department of Chemical and Fuels Engineering at the University of Utah and in the Departments of Chemistry and Chemical and Petroleum Engineering at the University of Wyoming. In addition, he was a Visiting Professor in the College of Science, University of Mosul, Iraq and has also been a Visiting Professor in Chemical Engineering at the University of Missouri-Columbia, the Technical University of Denmark, and the University of Trinidad and Tobago.
Content
Preface xiv
Part 1: Synthesis Gas Production 1
1 Energy Sources and Energy Supply 3
1.1 Introduction 3
1.2 Typical Energy Sources 6
1.2.1 Natural Gas and Natural Gas Hydrates 6
1.2.2 The Crude Oil Family 7
1.2.3 Extra Heavy Crude Oil and Tar Sand Bitumen 10
1.3 Other Energy Sources 11
1.3.1 Coal 12
1.3.2 Oil Shale 14
1.3.3 Biomass 16
1.3.4 Solid Waste 19
1.4 Energy Supply 22
1.4.1 Economic Factors 22
1.4.2 Geopolitical Factors 22
1.4.3 Physical Factors 23
1.4.4 Technological Factors 24
1.5 Energy Independence 25
References 29
2 Overview of Gasification 35
2.1 Introduction 35
2.2 Gasification Processes 38
2.2.1 Processes 40
2.3 Feedstocks 41
2.3.1 Influence of Feedstock Quality 48
2.3.2 Feedstock Preparation 50
2.3.2.1 Crushing/Sizing/Drying 51
2.3.2.2 Pelletizing and Briquetting 51
2.4 Power Generation 52
2.5 Synthetic-Fuel Production 53
2.5.1 Gaseous Products 54
2.5.1.1 Synthesis Gas 54
2.5.1.2 Low Btu Gas 55
2.5.1.3 Medium Btu Gas 55
2.5.1.4 High Heat-Content Gas 56
2.5.2 Liquid Fuels 56
2.5.3 Tar 57
2.6 Advantages and Limitations 58
2.7 Market Developments and Outlook 60
References 62
3 Gasifier Types- Designs and Engineering 67
3.1 Introduction 67
3.2 Gasifier Types 68
3.2.1 Fixed Bed Gasifier 72
3.2.2 Fluid Bed Gasifier 75
3.2.3 Entrained Bed Gasifier 78
3.2.4 Molten Salt Gasifier 79
3.2.5 Plasma Gasifier 80
3.2.6 Slagging Gasifier 82
3.2.7 Other Types 83
3.3 Designs 83
3.3.1 General Design Aspects 84
3.3.2 Chemical and Physical Aspects 85
3.3.2.1 Chemical Aspects 85
3.3.2.2 Influence of Feedstock Quality 86
3.3.2.3 Mineral Matter Content 88
3.3.2.4 Mixed Feedstocks 89
3.3.2.5 Moisture Content 89
3.3.3 Physical Effects 90
3.3.3.1 Bulk Density 90
3.3.3.2 Char Gasification 90
3.3.3.3 Devolatilization and Volatile Matter Production 91
3.3.3.4 Particle Size and Distribution 92
3.4 Mechanism 92
3.4.1 Primary Gasification 93
3.4.2 Secondary Gasification 93
3.4.3 Hydrogasification 94
3.4.4 Catalytic Gasification 95
3.5 Energy Balance 96
3.6 Gasifier-Feedstock Compatibility 97
3.6.1 Feedstock Reactivity 97
3.6.2 Energy Content 98
3.7 Products 99
3.7.1 Gases 100
3.7.2 Tar 102
References 103
4 Chemistry, Thermodynamics, and Kinetics 107
4.1 Introduction 107
4.2 Chemistry 108
4.2.1 Pretreatment 109
4.2.2 Gasification Reactions 110
4.2.2.1 Primary Gasification 113
4.2.2.2 Secondary Gasification 114
4.2.2.3 Water Gas Shift Reaction 117
4.2.2.4 Carbon Dioxide Gasification 118
4.2.2.5 Hydrogasification 119
4.2.2.6 Methanation 120
4.2.2.7 Catalytic Gasification 121
4.2.2.8 Effect of Process Parameters 122
4.2.3 Physical Effects 122
4.3 Thermodynamics and Kinetics 124
4.3.1 Thermodynamics 126
4.3.2 Kinetics 127
4.4 Products 128
4.4.1 Gaseous Products 131
4.4.1.1 Low Btu Gas 132
4.4.1.2 Medium Btu Gas 133
4.4.1.3 High Btu Gas 134
4.4.1.4 Synthesis Gas 134
4.4.2 Liquid Products 135
4.4.3 Tar 136
4.4.4 Soot 136
4.4.5 Char 137
4.4.6 Slag 138
References 138
Part 2: Process Feedstocks 141
5 Coal Gasification 143
5.1 Introduction 143
5.2 Coal Types and Reactions 147
5.2.1 Types 148
5.2.2 Reactions 149
5.2.3 Properties 151
5.3 Processes 152
5.3.1 Coal Devolatilization 154
5.3.2 Char Gasification 154
5.3.3 Gasification Chemistry 155
5.3.4 Other Process Options 156
5.3.4.1 Hydrogasification 157
5.3.4.2 Catalytic Gasification 157
5.3.4.3 Plasma Gasification 158
5.3.5 Process Optimization 158
5.4 Product Quality 160
5.4.1 Low Btu Gas 160
5.4.2 Medium Btu Gas 161
5.4.3 High Btu Gas 161
5.4.4 Methane 162
5.4.5 Hydrogen 162
5.4.6 Other Products 163
5.5 Chemicals Production 164
5.5.1 Coal Tar Chemicals 164
5.5.2 Fischer-Tropsch Chemicals 166
5.5.2.1 Fischer-Tropsch Catalysts 167
5.5.2.2 Product Distribution 168
5.6 Advantages and Limitations 168
References 169
6 Gasification of Viscous Feedstock 173
6.1 Introduction 173
6.2 Viscous Feedstocks 177
6.2.1 Crude Oil Resids 178
6.2.2 Heavy Crude Oil 180
6.2.3 Extra Heavy Crude Oil 180
6.2.4 Tar Sand Bitumen 181
6.2.5 Other Feedstocks 182
6.2.5.1 Crude Oil Coke 183
6.2.5.2 Solvent Deasphalter Bottoms 185
6.2.5.3 Asphalt, Tar, and Pitch 187
6.3 Gas Production 188
6.3.1 Partial Oxidation Technology 189
6.3.1.1 Shell Gasification Process 191
6.3.1.2 Texaco Process 191
6.3.1.3 Phillips Process 192
6.3.2 Catalytic Partial Oxidation 192
6.4 Products 193
6.4.1 Gas Purification and Quality 194
6.4.2 Process Optimization 195
6.5 Advantages and Limitations 195
References 198
7 Gasification of Biomass 201
7.1 Introduction 201
7.2 Biomass Types and Mixed Feedstocks 205
7.2.1 Biomass 205
7.2.2 Black Liquor 209
7.2.3 Mixed Feedstocks 210
7.2.3.1 Biomass with Coal 211
7.2.3.2 Biomass with Waste 213
7.3 Chemistry 214
7.3.1 General Aspects 215
7.3.2 Reactions 218
7.3.2.1 Water Gas Shift Reaction 222
7.3.2.2 Carbon Dioxide Gasification 222
7.3.2.3 Hydrogasification 223
7.3.2.4 Methanation 224
7.4 Gasification Processes 225
7.4.1 Gasifiers 226
7.4.2 Fischer-Tropsch Synthesis 231
7.5 Gas Production and Products 232
7.5.1 Gas Production 233
7.5.2 Products 234
7.5.2.1 Synthesis Gas 235
7.5.2.2 Low-Btu Gas 236
7.5.2.3 Medium-Btu Gas 237
7.5.2.4 High-Btu Gas 237
7.5.3 Liquid Products 238
7.5.4 Solid Products 239
7.6 The Future 240
References 243
8 Gasification of Waste 249
8.1 Introduction 249
8.2 Waste Types 251
8.2.1 Solid Waste 251
8.2.2 Municipal Solid Waste 252
8.2.3 Industrial Solid Waste 253
8.2.4 Biosolids 254
8.2.5 Biomedical Waste 254
8.2.6 Mixed Feedstocks 255
8.3 Feedstock Properties and Plant Safety 255
8.4 Fuel Production 256
8.4.1 Pre-Processing 257
8.4.2 Gasifier Types 259
8.4.2.1 Counter-Current Fixed Bed Gasifier 259
8.4.2.2 Co-Current Fixed Bed Gasifier 259
8.4.2.3 Fluidized Bed Gasifier 260
8.4.2.4 Entrained Flow Gasifier 260
8.4.2.5 Other Types 261
8.4.3 Process Design 262
8.4.4 Plasma Gasification 263
8.5 Process Products 264
8.5.1 Synthesis Gas 264
8.5.2 Carbon Dioxide 265
8.5.3 Tar 265
8.5.4 Particulate Matter 267
8.5.5 Halogens/Acid Gases 267
8.5.6 Heavy Metals 268
8.5.7 Alkalis 269
8.5.8 Slag 269
8.6 Advantages and Limitation 270
References 271
9 Gas Cleaning 275
9.1 Introduction 275
9.2 Gas Streams 277
9.3 Water Removal 282
9.3.1 Absorption 282
9.3.2 Adsorption 283
9.3.3 Cryogenics 285
9.4 Acid Gas Removal 285
9.4.1 Adsorption 287
9.4.2 Absorption 288
9.4.3 Chemisorption 289
9.4.4 Other Processes 294
9.5 Removal of Condensable Hydrocarbons 297
9.5.1 Extraction 299
9.5.2 Absorption 300
9.5.3 Fractionation 300
9.5.4 Enrichment 301
9.6 Tar Removal 302
9.6.1 Physical Methods 302
9.6.2 Thermal Methods 304
9.7 Particulate Matter Removal 304
9.7.1 Cyclones 304
9.7.2 Electrostatic Precipitators 305
9.7.3 Granular-Bed Filters 305
9.7.4 Wet Scrubbers 306
9.8 Other Contaminant Removal 306
9.8.1 Nitrogen Removal 307
9.8.2 Ammonia Removal 308
9.8.3 Siloxane Removal 308
9.8.4 Alkali Metal Salt Removal 309
9.8.5 Biological Methods 309
9.8.5.1 Biofiltration 310
9.8.5.2 Bioscrubbing 312
9.8.5.3 Bio-Oxidation 313
9.9 Tail Gas Cleaning 313
9.9.1 Claus Process 314
9.9.2 SCOT Process 315
References 316
Part 3: Applications 321
10 Gasification in a Refinery 323
10.1 Introduction 323
10.2 Processes and Feedstocks 324
10.2.1 Gasification of Residua 327
10.2.2 Gasification of Residua with Coal 328
10.2.3 Gasification of Residua with Biomass 328
10.2.4 Gasification of Residua with Waste 330
10.3 Synthetic Fuel Production 332
10.3.1 Fischer-Tropsch Synthesis 334
10.3.2 Fischer Tropsch Liquids 334
10.3.3 Upgrading Fischer-Tropsch Liquids 336
10.3.3.1 Gasoline Production 338
10.3.3.2 Diesel Production 339
10.4 Sabatier-Senderens Process 340
10.4.1 Methanol Production 341
10.4.2 Dimethyl Ether Production 342
10.5 The Future 344
References 347
11 Hydrogen Production 353
11.1 Introduction 353
11.2 Processes Requiring Hydrogen 359
11.2.1 Hydrotreating 360
11.2.2 Hydrocracking 361
11.3 Feedstocks 362
11.4 Process Chemistry 362
11.5 Commercial Processes 364
11.5.1 Autothermal Reforming 365
11.5.2 Combined Reforming 366
11.5.3 Dry Reforming 367
11.5.4 Steam-Methane Reforming 367
11.5.5 Steam-Naphtha Reforming 370
11.6 Catalysts 370
11.6.1 Reforming Catalysts 371
11.6.2 Shift Conversion Catalysts 372
11.6.3 Methanation Catalysts 373
11.7 Hydrogen Purification 373
11.7.1 Cryogenic Separation 374
11.7.2 Desiccant Separation Systems 374
11.7.3 Membrane Separation Systems 374
11.7.4 Pressure Swing Adsorption Separation Systems 375
11.7.5 Wet Scrubbing Systems 376
11.8 Hydrogen Management 376
References 377
12 Fischer-Tropsch Process 381
12.1 Introduction 381
12.2 History and Development of the Process 385
12.3 Synthesis Gas 388
12.4 Production of Synthesis Gas 391
12.4.1 Feedstocks 393
12.4.2 Product Distribution 396
12.5 Process Parameters 397
12.6 Reactors and Catalysts 400
12.6.1 Reactors 400
12.6.2 Catalysts 402
12.7 Products and Product Quality 406
12.7.1 Products 407
12.7.2.1 Gases 407
12.7.1.2 Liquids 407
12.7.2 Product Quality 412
12.7.3 Upgrading Fischer-Tropsch Liquids 415
12.8 Fischer-Tropsch Chemistry 415
12.8.1 Chemical Principles 416
12.8.2 Refining Fischer-Tropsch Products 421
References 423
13 Fuels and Chemicals Production 427
13.1 Introduction 427
13.2 Historical Aspects and Overview 438
13.3 The Petrochemical Industry 440
13.4 Petrochemicals 445
13.4.1 Primary Petrochemicals 446
13.4.2 Products 447
13.4.3 Gaseous Fuels and Chemicals 453
13.4.3.1 Ammonia 453
13.4.3.2 Hydrogen 454
13.4.3.3 Synthetic Natural Gas 455
13.4.4 Liquid Fuels and Chemicals 455
13.4.4.1 Fischer-Tropsch Liquids 455
13.4.4.2 Methanol 456
13.4.4.3 Dimethyl Ether 456
13.4.4.4 Methanol-to-Gasoline and Olefins 456
13.4.4.5 Other Chemicals 457
13.5 The Future 457
References 463
14 Gasification - A Process for Now and the Future 467
14.1 Introduction 467
14.2 Applications and Products 468
14.2.1 Chemicals and Fertilizers 468
14.2.2 Substitute Natural Gas 469
14.2.3 Hydrogen for Crude Oil Refining 470
14.2.4 Transportation Fuels 470
14.2.5 Transportation Fuels from Tar Sand Bitumen 471
14.2.6 Power Generation 472
14.2.7 Waste-to-Energy 473
14.2.8 Biomass to Chemicals and Fuels 473
14.3 Environmental Benefits 475
14.3.1 Carbon Dioxide 476
14.3.2 Air Emissions 476
14.3.3 Solids Generation 477
14.3.4 Water Use 477
14.4 Gasification - The Future 477
14.4.1 The Process 478
14.4.2 Refinery of the Future 479
14.4.3 Economic Aspects 480
14.4.4 Market Outlook 481
14.5 Market Development 482
14.6 Outlook 483
References 485
Coversion Factors 487
Glossary 491
About the Author 519
Index 521
1
Energy Sources and Energy Supply
1.1 Introduction
The Earth contains a finite supply of fossil fuels - the major fossil fuels are natural gas, crude oil, and coal - although there are debates related to the actual amounts of these fossil fuels remaining and the time left for use of these fuels (Speight, 2011c; Speight and Islam, 2016). In fact, at the present time, the majority of the energy consumed worldwide is produced from the fossil fuels (crude oil: approximately 38 to 40%, coal: approximately 31 to 35%, natural gas: approximately 20 to 25%) with the remainder of the energy requirements to come from nuclear sources and from hydroelectric sources. As a result, fossil fuels (in varying amounts depending upon the source of information) are projected to be the major sources of energy for the next fifty years (Crane et al., 2010; World Energy Council, 2008; Gudmestad et al., 2010; Speight, 2011a, 2011b, Khoshnaw, 2013; BP, 2014; Speight, 2014a; BP, 2019).
The current estimates for the longevity of each fossil fuel is estimated from the reserves/ production ratio (BP, 2019) which gives an indication (in years) of how long each fossil fuel will last at the current rates of production. The estimates vary from at least fifty years of crude oil at current rates of consumption with natural gas varying upwards of 100 years. On the other hand, coal remains in adequate supply and at current rates of recovery and consumption, the world global coal reserves have been variously estimated to have a reserves/ production ratio of at least 155 years. However, as with all estimates of resource longevity, coal longevity is subject to the assumed rate of consumption remaining at the current rate of consumption and, moreover, to technological developments that dictate the rate at which the coal can be mined. But most importantly, coal is a fossil fuel and an unclean energy source that will only add to global warming. In fact, the next time electricity is advertised as a clean energy source just consider the means by which the majority of electricity is produced - almost 50% of the electricity generated in the United States derives from coal (EIA, 2007; Speight, 2013).
In addition, the amounts of natural gas and crude oil located in tight sandstone formations and in shale formations has added a recent but exciting twist to the amount of these fossil fuels remaining. Peak energy theory proponents are inclined to discount the tight formations and shale formation as a mere aberration (or a hiccup) in the depletion of these resources while opponents of the peak energy theory take the opposite view and consider tight formations and shale formations as prolonging the longevity of natural gas and crude oil by a substantial time period (Speight and Islam, 2016). In addition, some areas of the Earth are still relatively unexplored or have been poorly analyzed and (using crude oil as the example) knowledge of in-ground resources increases dramatically as an oil reservoir is exploited.
Energy sources have been used since the beginning of recorded history and the fossil fuel resources will continue to be recognized as major sources of energy for at least the foreseeable future (Crane et al., 2010; World Energy Council, 2008; Gudmestad et al., 2010; Speight, 2011a, 2011b, Khoshnaw, 2013; Speight, 2014a; BP, 2019). Fossil fuels are those fuels, namely natural gas, crude oil (including heavy crude oil), extra heavy crude oil, tar sand bitumen, coal, and oil shale produced by the decay of plant remains over geological time represent an unrealized potential, with liquid fuels from crude oil being only a fraction of those that could ultimately be produced from heavy oil and tar sand bitumen (Speight, 1990, 1997, 2011a; 2013d, 2013e, 2014a).
Fuels from fossil fuels (especially the crude oil-based fuels) are well-established products that have served industry and domestic consumers for more than one hundred years and for the foreseeable future various fuels will still be largely based on hydrocarbon fuels derived from crude oil. Although the theory of peak oil is questionable (Speight and Islam, 2016), there is no doubt that crude oil, once considered inexhaustible, is being depleted at a measurable rate. The supposition by peak oil proponents is that supplies of crude oil are approaching a precipice in which fuels that are currently available may, within a foreseeable short time frame, be no longer available. While such a scenario is considered to be unlikely, the need to consider alternate technologies to produce liquid fuels that could mitigate the forthcoming effects of the shortage of transportation fuels is necessary and cannot be ignored.
Alternate fuels produced from source other than crude oil are making some headway into the fuel demand. For example, diesel from plant sources (biodiesel) is similar in performance to diesel from crude oil and has the added advantage of a higher cetane rating than crude oil-derived diesel. However, the production of liquid fuels from sources other than crude oil has a checkered history. The on-again-off-again efforts that are the result of the inability of the political decision-makers to formulate meaningful policies has caused the production of non-conventional fuels to move slowly, if at all (Yergin, 1991; Bower, 2009; Wihbey, 2009; Speight, 2011a, 2011b, Yergin, 2011; Speight, 2014a).
In the near term, the ability of conventional fuel sources and technologies to support the global demand for energy will depend on how efficiently the energy sector can match available energy resources (Figure 1.1) with the end user and how efficiently and cost effectively the energy can be delivered. These factors are directly related to the continuing evolution of a truly global energy market. In the long term, a sustainable energy future cannot be created by treating energy as an independent topic (Zatzman, 2012). Rather, the role of the energy and the inter-relationship of the energy market with other markets and the various aspects of market infrastructure demand further attention and consideration. Greater energy efficiency will depend on the developing the ability of the world market to integrate energy resources within a common structure (Gudmestad et al., 2010; Speight, 2011b; Khoshnaw, 2013).
As the 21st Century matures, there will continue to be an increased demand for energy to support the needs of commerce industry and residential uses - in fact, as the 2040 to 2049 decade approaches, commercial and residential energy demand is expected to rise by considerably - by approximately 30 percent over current energy demand. This increase is due, in part, to developing countries, where national economies are expanding and the move away from rural living to city living is increasing. In addition, the fuel of the rural population (biomass) is giving way to the fuel of the cities (transportation fuels, electric power) as the life-styles of the populations of developing countries changed from agrarian to metropolitan. Furthermore, the increased population of the cities requires more effective public transportation systems as the rising middle class seeks private means of transportation (automobiles). As a result, fossil fuels will continue to be the predominant source of energy for at least the next fifty years.
Figure 1.1 Types of energy resources.
However, there are several variables that can impact energy demand from fossil fuels. For example, coal (as a source of electrical energy) faces significant challenges from governmental policies to reduce greenhouse gas emissions and fuels from crude oil can also face similar legislation (Speight, 2013a, 2013b, 2014a) in addition to the types of application and use, location and regional resources, cost of energy, cleanness and environmental factors, safety of generation and utilization, socioeconomic factors, as well as global and regional politics (Speight, 2011a). More particularly, the recovery of natural gas and crude oil from tight sandstone and shale formations face challenges related to hydraulic fracturing.
Briefly, hydraulic fracturing is an extractive method used by crude oil and natural gas companies to open pathways in tight (low-permeability) geologic formations so that the oil or gas trapped within can be recovered at a higher flow rate (Speight, 2015a). When used in combination with horizontal drilling, hydraulic fracturing has allowed industry to access natural gas reserves previously considered uneconomical, particularly in shale formations. Although, hydraulic fracturing creates access to more natural gas supplies, but the process requires the use of large quantities of water and fracturing fluids, which are injected underground at high volumes and pressure. Oil and gas service companies design fracturing fluids to create fractures and transport sand or other granular substances to prop open the fractures. The composition of these fluids varies by formation, ranging from a simple mixture of water and sand to more complex mixtures with a multitude of chemical additives. Hydraulic fracturing has opened access to vast domestic reserves of natural gas that could provide an important stepping stone to a clean energy future. Yet questions related to the safety of hydraulic fracturing persist and the technology has been the subject of both enthusiasm and increasing environmental and health concerns in recent years, especially in relation to the possibility (some would say reality) of contaminated drinking water because of the chemicals used in the process and the disturbance of the geological formations (Speight, 2015a).
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