Preface ........................................................ xv
1 Occurrence and Resources ..................................... 1
1.1 Introduction ............................................ 1
1.2 Origin of Coal .......................................... 8
1.3 Occurrence ............................................. 12
1.4 Coal Utilization and Coal Types ........................ 14
1.4.1 Lignite ......................................... 17
1.4.2 Subbituminous Coal .............................. 18
1.4.3 Bituminous Coal ................................. 19
1.4.4 Anthracite ...................................... 21
1.5 Resources .............................................. 23
1.6 Reserves ............................................... 27
1.6.1 Proven Reserves ................................. 28
1.6.2 Inferred Reserves ............................... 30
1.6.3 Potential Reserves .............................. 31
1.6.4 Undiscovered Reserves ........................... 31
1.6.5 Other Definitions ............................... 33
References .................................................. 34
2 Classification .............................................. 37
2.1 Introduction ........................................... 37
2.2 Classification Systems ................................. 40
2.2.1 Geological Age .................................. 43
2.2.2 Banded Structure ................................ 44
2.2.3 Rank ............................................ 45
2.2.4 Coal Survey (National Coal Board, U.K.) ......... 52
2.2.1 International System ............................ 52
2.2.6 Coal as an Organic Rock ......................... 54
2.2.7 A Hydrocarbon Resource .......................... 55
2.3 Coal Petrography ....................................... 58
2.3.1 Vitrinite Group ................................. 61
2.3.2 Liptinite Group ................................. 62
2.3.3 Inertinite Group ................................ 62
2.4 Correlation of the Various Systems ..................... 63
References .................................................. 67
3 Recovery, Preparation, and Transportation ................... 69
3.1 Introduction ........................................... 69
3.2 Coal Recovery .......................................... 71
3.2.1 Surface Mining .................................. 73
3.2.2 Underground Mining .............................. 77
3.3 Coal Preparation ....................................... 79
3.4 Size Reduction ......................................... 92
3.4.1 Rotary Breaker .................................. 95
3.4.2 Roll Crusher .................................... 95
3.4.3 Hammer Mill ..................................... 96
3.4.4 Impactor ........................................ 96
3.4.5 Tumbler ......................................... 97
3.5 Coal Cleaning .......................................... 98
3.5.1 Effect of Composition and Rank .................. 99
3.5.2 Methods ........................................ 100
3.6 Coal Drying ........................................... 106
3.6.1 Rotary Dryers .................................. 108
3.6.2 Fluidized Bed Dryers ........................... 110
3.6.3 Microwave Dryers ............................... 111
3.6.4 Screw Conveyor Dryers .......................... 112
3.6.5 Superheated Steam Dryer ........................ 112
3.7 Desulfurization ....................................... 113
3.8 Transportation ........................................ 115
3.8.1 Unit Train ..................................... 116
3.8.2 Barge .......................................... 117
3.8.3 Pipeline ....................................... 117
3.8.4 Truck .......................................... 119
3.8.5 Ocean .......................................... 120
3.8.6 Conveyer Belt .................................. 120
References ................................................. 121
4 Storage .................................................... 127
4.1 Introduction .......................................... 127
4.2 Oxidation and Spontaneous Ignition .................... 129
4.2.1 Oxidation and Rank ............................. 133
4.2.2 Pyrite ......................................... 136
4.2.3 Other Minerals ................................. 137
4.2.4 Coal Size and Stockpile Ventilation ............ 137
4.2.5 Moisture Content ............................... 138
4.2.6 Time Factor .................................... 140
4.3 Mechanism of Spontaneous Ignition ..................... 140
4.4 Stockpiling ........................................... 144
4.4.1 Stockpile Construction ......................... 145
4.4.2 Stockpile Management ........................... 146
4.5 Effect of Storage ..................................... 149
4.5.1 Long-Term Storage .............................. 150
4.5.2 Short-Term Storage ............................. 150
4.6 Preventing Spontaneous Ignition ....................... 151
References ................................................. 153
5 General Properties ......................................... 159
5.1 Introduction .......................................... 159
5.2 Sampling .............................................. 164
5.2.1 Methods ........................................ 166
5.2.2 In Situ Sampling ............................... 167
5.2.3 Ex-Situ Sampling ............................... 168
5.3 Proximate Analysis .................................... 171
5.3.1 Moisture ....................................... 173
5.3.2 Natural Bed Moisture ........................... 175
5.3.3 Volatile Matter ................................ 177
5.3.4 Ash ............................................ 179
5.3.5 Fixed Carbon ................................... 187
5.4 Ultimate Analysis ..................................... 187
5.4.1 Carbon and Hydrogen ............................ 189
5.4.2 Nitrogen ....................................... 189
5.4.3 Oxygen ......................................... 190
5.4.4 Sulfur ......................................... 191
5.4.5 Chlorine ....................................... 192
5.4.6 Mercury ........................................ 193
5.4.7 Trace Elements ................................. 194
5.5 Calorific Value ....................................... 195
5.6 Reporting Coal Analyses ............................... 198
References ................................................. 204
6 Physical, Mechanical, and Thermal Properties ............... 211
6.1 Introduction .......................................... 211
6.2 Physical Properties ................................... 215
6.2.1 Coal Type ...................................... 216
6.2.2 Density ........................................ 217
6.2.3 Petrographic Analysis .......................... 222
6.2.4 Porosity and Surface Area ...................... 223
6.3 Mechanical Properties ................................. 225
6.3.1 Strength ....................................... 226
6.3.2 Hardness ....................................... 227
6.3.3 Friability ..................................... 228
6.3.4 Grindability ................................... 230
6.3.5 Dustiness Index ................................ 234
6.4 Thermal Properties .................................... 234
6.4.1 Heat Capacity .................................. 236
6.4.2 Thermal Conductivity ........................... 237
6.4.3 Plastic and Agglutinating Properties ........... 238
6.4.4 Agglomerating Index ............................ 242
6.4.5 Free Swelling Index ............................ 242
6.4.6 Ash Fusion Temperature ......................... 243
6.5 Epilogue .............................................. 245
References ................................................. 245
7 Combustion ................................................. 251
7.1 Introduction .......................................... 251
7.2 General Aspects ....................................... 255
7.2.1 Coal Devolatilization and Combustion of
Volatile Matter ................................ 255
7.2.2 Char Combustion ................................ 257
7.3 Chemistry and Physics ................................. 258
7.3.1 Influence of Coal Quality ...................... 262
7.3.2 Mechanism ...................................... 266
7.3.3 Ignition ....................................... 269
7.3.4 Surface Effects ................................ 270
7.3.5 Reaction Rates ................................. 272
7.3.6 Heat Balance ................................... 272
7.3.7 Soot Formation ................................. 273
7.3.8 Conduction, Convection, and Radiation .......... 274
7.3.9 Slagging and Fouling ........................... 275
7.3.10 Additives and Catalysts ........................ 276
7.3.11 Excess Air ..................................... 278
7.3.12 Coal/Air Transport ............................. 279
7.4 Catalytic Combustion .................................. 279
7.5 Fuels ................................................. 280
7.5.1 Coal ........................................... 282
7.5.2 Coal Blends .................................... 284
7.5.3 Coal-Oil Fuels ................................. 290
7.5.4 Coal-Water Fuels ............................... 292
7.5.5 Coal-Biomass Fuels ............................. 298
References ................................................. 307
8 Combustion Systems ......................................... 315
8.1 Introduction .......................................... 315
8.2 Combustion Systems .................................... 319
8.2.1 Stoker Systems ................................. 321
8.2.2 Fixed Bed Systems .............................. 323
8.2.3 Fluidized Beds ................................. 330
8.2.4 Entrained Systems .............................. 342
8.2.5 Miscellaneous Systems .......................... 345
8.3 Fuel Feeders .......................................... 352
References ................................................. 353
9 Gasification ............................................... 355
9.1 Introduction .......................................... 355
9.2 General Aspects ....................................... 358
9.2.1 Coal Devolatilization .......................... 361
9.2.2 Char Gasification .............................. 362
9.3 Chemistry and Physics ................................. 364
9.3.1 Influence of Coal Quality ...................... 365
9.3.2 Mechanism ...................................... 368
9.3.3 Primary Gasification ........................... 370
9.3.4 Secondary Gasification ......................... 370
9.3.5 Shift Conversion ............................... 370
9.3.6 Hydrogasification .............................. 371
9.4 Catalytic Gasification ................................ 371
9.5 Plasma Gasification ................................... 373
9.6 Gasification Systems .................................. 374
9.6.1 Fixed Bed Gasifier ............................. 376
9.6.2 Fluidized Bed Gasifier ......................... 378
9.6.3 Entrained Bed Gasifier ......................... 381
9.6.4 Molten Salt Gasifier ........................... 383
9.7 Gaseous Products ...................................... 383
9.7.1 Low Btu Gas .................................... 383
9.7.2 Medium Btu Gas ................................. 385
9.7.3 High Btu Gas ................................... 385
9.7.4 Methane ........................................ 386
9.7.5 Hydrogen ....................................... 387
9.7.6 Other Products ................................. 390
9.8 Gasification of Coal with Biomass and Waste ........... 390
9.8.1 Biomass ........................................ 391
9.8.2 Waste .......................................... 393
9.8.3 Reactors ....................................... 396
9.9 Underground Gasification .............................. 397
References ................................................. 401
10 Gasification Systems ....................................... 407
10.1 Introduction .......................................... 407
10.2 Fixed-Bed Processes ................................... 409
10.2.1 Foster Wheeler Stoic Process ................... 409
10.2.2 Lurgi Process .................................. 410
10.2.3 Wellman Galusha Process ........................ 412
10.2.4 Woodall-Duckham Process ........................ 414
10.3 Fluidized-Bed Processes ............................... 416
10.3.1 Agglomerating Burner Process ................... 416
10.3.2 Carbon Dioxide Acceptor Process ................ 416
10.3.3 Coalcon Process ................................ 419
10.3.4 The COED/COGAS Process ......................... 420
10.3.5 Exxon Catalytic Gasification Process ........... 421
10.3.6 The Hydrane Process ............................ 422
10.3.7 The Hygas Process .............................. 422
10.3.8 Pressurized Fluid-bed Process .................. 424
10.3.9 Synthane Process ............................... 425
10.3.10 The U-Gas Process ............................. 427
10.3.11 Winkler Process ............................... 428
10.4 Entrained-Bed Processes ............................... 429
10.4.1 Bi-Gas Process ................................. 429
10.4.2 Combustion Engineering Process ................. 430
10.4.3 Koppers-Totzek Process ......................... 431
10.4.4 The Texaco Process ............................. 432
10.5 Molten Salt Processes ................................. 434
10.5.1 Atgas process .................................. 434
10.5.2 Pullman-Kellogg Process ........................ 435
10.5.3 Rockgas Process ................................ 436
10.5.4 Rummel Single-Shaft Process .................... 437
10.6 Underground Gasification .............................. 437
10.6.1 Borehole Producer Method ....................... 439
10.6.2 Chamber Method ................................. 440
10.6.3 Shaftless Method ............................... 440
10.6.4 Stream Method .................................. 441
References ................................................. 442
11 Electric Power Generation .................................. 445
11.1 Introduction .......................................... 445
11.2 Electricity From Coal ................................. 448
11.2.1 Conventional Power Plant ...................... 448
11.3 Steam Generation ...................................... 452
11.3.1 The Steam Generator ............................ 455
11.3.2 The Steam Turbines and the Electrical
Generator ...................................... 455
11.3.3 Steam Condensing and Cooling Towers ............ 458
11.4 Control of Emissions .................................. 461
11.4.1 Carbon Dioxide Emissions ....................... 461
11.4.2 Particulate Matter Emissions ................... 462
11.4.3 Sulfur Dioxide Emissions ....................... 463
11.4.4 Mercury Emissions .............................. 463
11.5 Power Plant Efficiency ................................ 465
11.6 Combined Cycle Generation ............................. 470
11.6.1 Cogeneration ................................... 470
11.6.2 IGCC Technology ................................ 471
References ................................................. 474
12 Gas Cleaning ............................................... 477
12.1 Introduction .......................................... 477
12.2 Environmental Legislation ............................. 482
12.3 General Aspects ....................................... 485
12.4 Air Pollution Control Devices ......................... 490
12.4.1 Nitrogen Oxide Emissions ....................... 490
12.4.2 Sulfur Oxide Emissions ......................... 491
12.5 Particulate Matter Removal ............................ 493
12.5.1 Electrostatic Precipitators .................... 494
12.5.2 Fabric Filters ................................. 495
12.5.3 Granular-bed Filters ........................... 496
12.5.4 Scrubber Systems ............................... 497
12.5.5 Cyclones ....................................... 504
12.6 Acid Gas Removal ...................................... 505
12.7 Removal of Sulfur-Containing Gases .................... 511
12.8 Removal of Nitrogen-Containing Gases .................. 515
References ................................................. 517
13 Environmental Aspects of Power Generation .................. 521
13.1 Introduction .......................................... 521
13.2 Coal Preparation ...................................... 525
13.2.1 Water Treatment ................................ 526
13.2.2 Dust Control ................................... 526
13.2.3 Noise Control .................................. 527
13.2.4 Recent Legislation ............................. 527
13.3 Transportation and Storage ............................ 529
13.3.1 Transportation ................................. 529
13.3.2 Storage ........................................ 531
13.4 Combustion ............................................ 532
13.4.1 Effect of Coal Type ............................ 533
13.4.2 Gaseous Effluents .............................. 534
13.5 Gasification .......................................... 540
14 Clean Coal Technologies for Power Generation ............... 579
14.1 Introduction .......................................... 579
14.2 Historical Perspectives ............................... 588
14.3 Modern Perspectives ................................... 590
14.4 Clean Coal Technology ................................. 593
14.4.1 Precombustion Cleaning ......................... 597
14.4.2 Cleaning during Combustion ..................... 600
14.4.3 Post-combustion Cleaning ....................... 606
14.4.4 Conversion and Added-value Products ............ 617
14.5 Managing Wastes from Coal Use ......................... 624
14.6 Carbon Dioxide Capture and Sequestration .............. 626
References ................................................. 637
15 Coal and Energy Security ................................... 645
15.1 Introduction .......................................... 645
15.2 Energy Security ....................................... 649
15.3 National Energy Plan and Coal Utilization ............. 656
15.4 Electric Power Generation ............................. 659
15.5 Hydrogen from Coal .................................... 661
15.6 Energy Security and Sustainable Development ........... 664
15.6.1 Continuing Use of Coal ......................... 664
15.6.2 Management of Coal Wastes ...................... 666
15.6.3 Sustainable Development ........................ 668
References ................................................. 673
Glossary ...................................................... 675
Common Conversion Factors Used in Coal Technology ............. 723
Index ......................................................... 727
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