Industrial and Process Furnaces (eBook)

Cover 1
Contents 8
Foreword 18
Preface 20
Acknowledgements 22
List of figures 24
List of tables 32
Chapter 1 Introduction 34
1.1 What is a furnace? 36
1.1.1 Furnace outline 37
1.1.2 Furnace classification 38
1.1.3 Principle objectives of furnace designers and operators 38
1.2 Where are furnaces used? Brief review of current furnace applications and technology 40
1.2.1 Ceramics, brick making and pottery 40
1.2.2 Cement and lime 41
1.2.3 Glass making 44
1.2.4 Metal ore smelting 46
1.2.5 Metal refining 49
1.2.6 Flash and fluid bed furnaces 51
1.2.7 Metal physical processing 53
1.2.8 Incinerators and resource recovery furnaces 57
1.2.9 Furnaces with reducing atmospheres 57
1.2.10 Oil refining and petrochemical furnaces 58
1.3 Drivers for improved efficiency 61
1.4 Concluding remarks 62
References 62
Chapter 2 The combustion process 64
2.1 Simple combustion chemistry 65
2.1.1 The complete oxidation of carbon 65
2.1.2 The complete oxidation of hydrogen 65
2.1.3 The incomplete oxidation of carbon 66
2.1.4 The oxidation of carbon monoxide 66
2.2 Combustion calculations 66
2.3 Chemical reaction kinetics 69
2.3.1 Types of reactions 70
2.3.2 Reaction rate theory 71
2.3.3 Reaction rate behaviour 73
2.3.4 Burning droplets and particles 76
2.4 The physics of combustion 80
2.4.1 The role of primary air 83
2.4.2 The role of swirl flows 89
2.4.3 Turbulence in jets 90
2.4.4 Secondary flow aerodynamics 92
2.4.5 Effect of excess air on fuel consumption 94
2.4.6 Multiple burner installations 95
Nomenclature 96
References 97
Chapter 3 Fuels for furnaces 100
3.1 Gaseous fuels 102
3.1.1 Properties of natural gas 102
3.1.2 Manufactured gas 102
3.1.3 Wobbe number or index 104
3.1.4 Flammability limits 105
3.1.5 Flame radiation from gaseous fuels 108
3.2 Liquid fuels 108
3.3 Solid fuels 110
3.3.1 Ash 112
3.4 Waste fuels 112
3.5 Choice of fuel 113
3.5.1 Furnace performance 114
3.6 Safety 119
3.7 Emissions 119
Nomenclature 119
References 120
Solid fuel bibliography 121
Chapter 4 An introduction to heat transfer in furnaces 122
4.1 Conduction 123
4.1.1 Steady state conduction 124
4.1.2 Transient conduction 126
4.2 Convection 133
4.2.1 Dimensional analysis 134
4.2.2 Application to convective heat transfer 135
4.2.3 Evaluating convective heat transfer coefficients 137
4.2.4 High temperature convective heat transfer 141
4.3 Radiation 146
4.3.1 Physical basics of radiative exchange 147
4.3.2 Emissivity and absorptivity 150
4.3.3 View factors 154
4.3.4 Mean beam length 160
4.4 Electrical heating 161
4.4.1 Resistance heating 161
4.4.2 Arc heating 162
4.4.3 Induction heating 165
4.4.4 Dielectric heating 166
4.4.5 Infrared heating 166
Nomenclature 167
References 169
Appendix 4A: Tables of emissivity data 170
Chapter 5 Flames and burners for furnaces 174
5.1 Types of flame 175
5.1.1 Premixed flames 176
5.1.2 Turbulent jet diffusion flames 178
5.1.3 Heterogeneous combustion 178
5.2 Function of a burner and basics of burner design 185
5.2.1 The essential importance of heat flux profiles 187
5.2.2 Flame stabilisation 188
5.3 Gas burners 191
5.3.1 Premixed burners 191
5.3.2 Turbulent jet diffusion burners 198
5.3.3 Precessing jet diffusion burners 200
5.4 Oil burners 201
5.4.1 Turndown 204
5.4.2 Atomisers 205
5.5 Pulverised coal burners 212
5.6 Furnace aerodynamics 215
5.6.1 Single burner systems 217
5.6.2 Multiple burner systems 219
5.6.3 Combustion air duct design 221
5.6.4 Common windbox and plenum design 225
5.7 Combustion system scaling 226
5.7.1 Example of combustion system scaling 227
5.8 Furnace noise 229
5.8.1 Combustion roar 231
5.8.2 Nozzle and turbulent jet noise 231
5.8.3 Fan noise 232
5.8.4 Pipe and valve noise 232
5.8.5 Furnace noise attenuation 233
5.8.6 Combustion driven oscillations 234
Nomenclature 237
References 238
Chapter 6 Combustion and heat transfer modelling 242
6.1 Physical modelling 244
6.1.1 Thring-Newby parameter 247
6.1.2 Craya-Curtet parameter 247
6.1.3 Becker throttle factor 248
6.1.4 Curtet number 248
6.1.5 Relationship between scaling parameters 249
6.1.6 Determining the required model flows 249
6.1.7 Applying the scaling parameter 249
6.1.8 Applying a post-measurement correction 250
6.2 Mathematical modelling 250
6.2.1 Simple well-stirred furnace models 252
6.2.2 Long furnace models 260
6.2.3 Two- and three-dimensional zone models 262
6.2.4 Computational fluid dynamics models 266
6.2.5 Particle drag in combustion systems 270
6.3 Application of modelling to furnace design 271
Nomenclature 272
References 274
Chapter 7 Fuel handling systems 276
7.1 Gas valve trains 277
7.1.1 Safety shutoff systems 278
7.2 Fuel oil handling systems 279
7.2.1 Storage, pumping and heating 280
7.2.2 Oil valve trains 282
7.3 Pulverised coal handling and firing systems 284
7.3.1 Raw coal bunkers and feeders 285
7.3.2 Coal grinding and drying 286
7.3.3 Coal mills 287
7.3.4 Coal mill grinding capacity 293
7.3.5 Pulverised coal grinding and firing systems 295
7.3.6 Coal system drying capacity 299
7.3.7 Coal firing system fans 303
7.3.8 Fine coal storage 304
7.3.9 Fine coal feeding and conveying 307
7.3.10 Pulverised coal conveying 311
7.4 Waste fuel handling 313
7.4.1 Waste gas fuel handling 314
7.4.2 Waste liquid fuel handling 315
7.4.3 Solids waste fuel handling 315
7.4.4 Environmental benefits and health hazards of waste fuel utilisation 316
Nomenclature 317
References 317
Applicable codes and standards 318
Chapter 8 Furnace control and safety 320
8.1 Process control 321
8.1.1 Basic furnace control strategies 322
8.2 Furnace instrumentation 323
8.2.1 Temperature measurement 323
8.2.2 Heat input measurement 328
8.2.3 Determination of excess air 330
8.3 Flue gas analysis 333
8.3.1 Extractive gas sampling systems and analysers 335
8.3.2 In-situ systems 339
8.4 Combustion control 345
8.5 Ensuring furnace safety 346
8.5.1 Risk factors in furnace operation 346
8.5.2 Furnace start-up 347
8.5.3 Operation with insufficient combustion air 350
8.5.4 Flame quenching 351
8.5.5 Eliminating ignition sources 352
8.6 Burner management systems 352
8.6.1 Safety requirements for burner management systems 353
8.6.2 False trips 355
8.6.3 Achieving acceptable safety standards with programmable logic controller burner management systems 356
8.6.4 Choosing an appropriate safety integrity level 357
8.6.5 Determining the safety integrity level of the BMS system 359
8.6.6 Flame detectors 362
Nomenclature 365
References 365
Certification and testing organisations 366
Chapter 9 Furnace efficiency 368
9.1 Furnace performance charts 371
9.2 Mass and energy balances 374
9.2.1 On-site measurement 375
9.2.2 Constructing mass and energy balances 379
9.3 Energy conversion 391
9.3.1 Low and high grade heat 393
9.3.2 Exergy and pinch point analysis 395
9.4 Heat recovery equipment 396
9.4.1 Recuperative heat exchangers 397
9.4.2 Regenerative heat exchangers 399
9.4.3 General heat exchanger design procedure 401
9.5 Identifying efficiency improvements 402
Nomenclature 405
References 405
Chapter 10 Emissions and environmental impact 408
10.1 Formation of carbon monoxide 410
10.2 Formation of nitrogen oxides 411
10.2.1 Thermal NO[sub(x)] formation 412
10.2.2 Fuel NO[sub(x)] formation 414
10.2.3 Prompt NO[sub(x)] formation 415
10.2.4 NO[sub(x)] modelling 417
10.3 Formation of sulphur oxides 418
10.4 Formation of intermediate combustion products 419
10.4.1 Volatile organic compounds (VOCs) 419
10.4.2 Polycyclic aromatic hydrocarbons (PAH) 419
10.4.3 PCBs, dioxins and furans 420
10.5 Particulate emissions 423
10.5.1 Formation of soot 423
10.5.2 Formation and composition of fuel ash 426
10.5.3 Non-combustible volatile cycles 427
10.6 Environmental control of emissions 429
10.6.1 Prevention and abatement of emissions 430
10.6.2 Dispersion modelling 441
References 442
Chapter 11 Furnace construction and materials 446
11.1 Basic performance requirements of the furnace structure 447
11.2 Basic construction methods 448
11.2.1 Brick lining 450
11.2.2 Monolithic linings 452
11.2.3 Furnace steelwork 458
11.2.4 Furnace roof construction 459
11.2.5 Furnace cooling systems 461
11.3 Practical engineering considerations in the use of refractories 464
11.4 Ceramic refractory materials 466
11.4.1 Testing of refractories 467
11.4.2 Properties and uses of refractories 468
11.5 Heat resisting and refractory metals 471
11.5.1 Effect of elevated temperature on metal properties 472
11.5.2 High temperature alloys 474
11.6 Practical engineering considerations in the use of high temperature metals 476
11.7 Concluding remarks 477
References 478
Selection of relevant standards 478
Advisory organisations 479
Appendix 11A: General properties of selected refractory materials 480
Chapter 12 Furnace design methods 488
12.1 Introduction 489
12.1.1 Design constraints 491
12.1.2 Cost of design changes 492
12.2 Conceptual design 492
12.2.1 Process functions 493
12.2.2 Defining the physical and chemical changes 497
12.2.3 Preliminary mass and energy balances 499
12.2.4 Reliability of available process knowledge 499
12.2.5 Effect of upstream and downstream processes 501
12.2.6 Fuel choice 502
12.2.7 Potential for heat recovery and choice of equipment 507
12.3 Furnace sizing 512
Slab heating furnace design 520
Oil heating furnace design 522
Aggregate processing furnace 525
12.4 Burner selection 529
12.5 Detailed analysis and validation of the furnace design 533
12.6 Furnace instrumentation and controls 534
Nomenclature 536
References 537
Author index 540
A 540
B 540
C 540
D 540
E 540
F 540
G 540
H 540
J 540
K 541
L 541
M 541
N 541
O 541
P 541
R 541
S 541
T 542
U 542
V 542
W 542
Z 542
Subject index 544
A 544
B 544
C 545
D 547
E 547
F 548
G 550
H 550
I 550
J 551
K 551
L 551
M 551
N 552
O 552
P 553
Q 554
R 554
S 555
T 556
U 556
V 556
W 556
Y 557
Z 557