Fluidized Bed Combustion

Fluidized Bed Combustion......Page 9
Foreword......Page 11
Preface......Page 13
Contents......Page 18
1.1. Problems of modern energy production and the requirements posed for coal combustion technologies......Page 25
1.2. Development of FBC technology—background......Page 29
1.3. A short review of FBC history......Page 30
1.4. Development of FBC technology in Yugoslavia......Page 34
1.5. Bubbling fluidized bed boilers—the state-of-the-art......Page 36
1.6. The features of first generation FBC boilers......Page 38
1.7. Reasons for circulating FBC boiler development......Page 44
1.8. Basic principles and description of circulating FBC boilers......Page 45
1.9. Characteristics of second generation FBC boilers......Page 48
1.10. Circulating fluidized bed combustion boilers—the state-of-the-art......Page 50
1.11. Application of the FBC boilers for energy production......Page 53
References......Page 56
CHAPTER 2: HYDRODYNAMICS OF GAS-SOLID FLUIDIZATION......Page 61
2.1. Basic definitions and properties of the particulate solids......Page 62
2.1.1. Physical properties of the particulate solids......Page 63
2.1.2. Geometrical characteristics of the particulate solids......Page 64
2.1.3. Hydrodynam ic properties of solid particles......Page 74
2.2.1. Different possible states of the gas-solid mixtures......Page 79
2.2.2. Fluidization regimes......Page 84
2.2.3. Relative gas-particle velocity......Page 92
2.3.1. General characteristics and macroscopic behavior of the bubbling fluidized bed......Page 93
2.3.2. Minimum fluidization velocity......Page 97
2.3.3. Bed expansion......Page 105
2.3.4. Particle elutriation from fluidized bed......Page 112
2.3.5. Bubbles in a fluidized bed......Page 120
2.3.6. Gas and particle mixing in fluidized bed......Page 132
2.4. Mathematical modelling of the fluidized bed......Page 152
Nomenclature......Page 157
Greek symbols......Page 159
References......Page 160
Table of Contents......Page 0
3.1. Heat transfer processes in bubbling fluidized bed combustion boiler furnaces......Page 170
3.2. Heat transfer between gas and solid particles in bubbling fluidized beds......Page 173
3.3. Heat and mass transfer between fuel particles and a bubbling fluidized bed......Page 178
3.3.1. Mass transfer between fuel particles and bubbling fluidized beds......Page 179
3.3.2. Heat transfer between fuel particles and bubbling fluidized bed......Page 183
3.4. Apparent conductive heat transfer in bubbling fluidized beds......Page 188
3.5.1. Mechanisms of bed-to-surface heat transfer......Page 191
3.5.2. Heat transfer to immersed surfaces—experimental results......Page 195
3.5.3. Influence of geometrical parameters on heat transfer......Page 208
3.5.4. Radiative heat transfer in the fluidized bed......Page 212
3.5.5. Modelling of heat transfer processes to immersed surfaces......Page 215
3.6. Heat transfer to the walls of the fluidized bed combustion boiler furnace......Page 218
Nomenclature......Page 223
Greek symbols......Page 224
Dimensionless criterial numbers......Page 225
References......Page 227
CHAPTER 4: FUNDAMENTAL PROCESSES DURING COAL COMBUSTION IN FLUIDIZED BEDS......Page 234
4.1.1. Combustion conditions in fluidized beds......Page 235
4.1.2. Physical processes during coal particle combustion in fluidized beds......Page 237
4.1.3. Parameters influencing combustion in the fluidized bed......Page 240
4.2.1. Classification of coals......Page 242
4.2.2. Coal petrography......Page 247
4.2.3. Chemical structure of organic matter in coal......Page 248
4.2.5. Porosity of coal and char particles......Page 251
4.2.6. Coal characteristics that influence the combustion process......Page 252
4.3. Fragmentation of coal particles in fluidized beds......Page 255
4.3.1. Primary fragmentation......Page 256
4.3.2.Secondary fragmentation......Page 258
4.3.3. Attrition of char particles......Page 259
4.4. Devolatilization and combustion of volatile matter......Page 263
4.4.1. Volatile matter yield and composition......Page 264
4.4.2. Control processes and kinetics of devolatilization......Page 277
4.4.3. Devolatilization time in fluidized beds—experimental results......Page 288
4.4.4. Ignition and combustion kinetics of volatile matter......Page 293
4.5.1. High volatile coal combustion in real conditions......Page 298
4.5.2. Coal particle behavior during the devolatilization process in fluidized beds......Page 299
4.5.3. Distribution and combustion of volatile matter in fluidized beds......Page 303
4.5.4. Modelling of volatile matter distribution and combustion in fluidized beds......Page 307
G. Combustion above the bed......Page 308
4.6. Char combustion......Page 309
4.6.1. Kinetics of heterogeneous chemical reactions on the surface of carbon (char) particles......Page 311
4.6.2. Chemical reactions and control processes during carbon (char) particle combustion......Page 315
4.6.3. Carbon (char) particle burning models......Page 320
4.6.4. Mathematical modelling of single char particle combustion in a fluidized bed......Page 325
4.6.5. Char combustion kinetics in fluidized beds—experimental results......Page 335
(a) Char burn-out time......Page 345
(b) Chemical reactions in char particle combustion in fluidized beds......Page 348
(c) Char combustion rate......Page 350
(d) Kinetic parameters......Page 354
4.6.6. Temperature of burning particles in a fluidized bed......Page 356
4.7. Mathematical modelling of processes in solid fuel combustion in fluidized bed boilers......Page 362
Nomenclature......Page 374
Dimensionless criterial numbers......Page 377
References......Page 378
(a) Purpose and applications......Page 389
(b) Basic parameters and requirements......Page 390
(d) Some construction solutions......Page 391
(a) Purpose and applications......Page 393
(b) Basic parameters and requirements......Page 395
(d) Basic designs of industrial bubbling FBC boilers......Page 396
(a) Purpose and application......Page 416
(b) Basic parameters and requirements......Page 418
(c) Basic design problems......Page 419
(d) Basic design solutions for large power bubbling FBC boilers......Page 420
5.1.4. Choice of boiler concept-problems and the choice of basic parameters......Page 424
5.2. The purpose and description of auxiliary systems in FBC boilers......Page 433
5.3. Efficiency of solid fuel combustion in the FBC boilers......Page 446
5.3.1. Influence of fuel properties......Page 448
5.3.2. Influence of combustion regime parameters......Page 453
5.3.3. Influence of furnace design......Page 456
5.4. Load control in FBC boilers......Page 459
5.5. Erosion of heat transfer surfaces immersed into the fluidized bed......Page 461
5.6. Ash sintering during combustion in fluidized bed......Page 468
Coal from small local mines......Page 470
Biomass fuels......Page 471
Municipal solid wastes......Page 472
Hazardous and special wastes......Page 473
High-sulphur pitch......Page 474
Greek symbols......Page 475
References......Page 476
6.1. Effects of fuel characteristics on the design and FBC boiler concept and its operational behavior......Page 484
6.2. ITE-IBK methodology for investigation of solid fuel suitability for combustion in fluidized beds......Page 486
6.2.1. Principles of the ITE-IBK methodology......Page 487
6.2.2. Description of the ITE-IBK methodology......Page 492
6.2.3. Characteristics of the investigated fuels......Page 496
6.2.4. Determination of the start-up temperature......Page 501
6.2.5. Effects of fuel characteristics on fuel behavior during combustion in fluidized beds......Page 509
6.3. Justification of the application of laboratory furnace investigation results in designing industrial boilers......Page 518
Nomenclature......Page 520
References......Page 521
7.1. Introduction......Page 525
7.1.1. Combustion of coal and formation of harmful matter......Page 526
7.1.2. Regulations on air protection......Page 528
7.1.3. Air pollution in Yugoslavia......Page 531
7.1.4. The role of FBC boilers in reduction of air pollution......Page 532
7.2. Characteristics of the first generation industrial and demonstration FBC boilers in operation—SO2, NOx, CO, and particle emission......Page 534
7.2.1. Design requirements for the first generation FBC boilers......Page 535
7.2.2. Emission measured during operation of several characteristic first generation FBC boilers......Page 536
7.2.3 Comparison of emissions from bubbling and circulating FBC boilers......Page 537
7.3. Carbon-monoxide emission in bubbling fluidized bed combustion......Page 539
7.4.1. Physical and chemical processes controlling rate and degree of limestone sulphation during fluidized bed combustion......Page 541
7.4.2 The effects of design and operating parameters on SO2 emission in fluidized bed combustion......Page 547
7.4.3. Effects of limestone characteristics......Page 554
7.4.4. Efficiency of limestone utilization......Page 555
7.5.1. Nitrogen balance during coal combustion in FBC boilers......Page 568
7.5.2. Mechanisms of N2O and NOx formation and destruction......Page 573
7.5.3. Effects of coal characteristics on NOx and N2O formation......Page 576
7.5.4. Effects of operating parameters......Page 577
7.5.5. Measures for reduction of NOx and N2O emission in fluidized bed combustion......Page 585
7.6.1. Types and characteristics of solid combustion products from FBC boilers......Page 587
7.6.2. Experience with baghouse filters......Page 590
7.6.3. Experience in the application of electrostatic precipitators......Page 591
References......Page 592