elsevier industrial and process furnaces principles design and operation apr 2008

Industrial and Process Furnaces
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Industrial and Process
Furnaces
Principles, Design and Operation
Peter Mullinger
Associate Professor, School of Chemical Engineering
University of Adelaide, South Australia
Barrie Jenkins
Consulting Engineer, High Wycombe, Bucks, UK
AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEW YORK • OXFORD
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08 09 10 11 12 10 9 8 7 6 5 4 3 2 1
To the late Frank David Moles, who showed us a better way of
thinking about furnaces, especially those where the product is
directly heated by the flame.

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Contents
Foreword xvii
Preface xix
Acknowledgements xxi
List of Figures xxiii
List of Tables xxxi
Chapter 1 Introduction 1
1.1 What is a furnace? 3
1.1.1 Furnace outline 4
1.1.2 Furnace classification 5
1.1.3 Principle objectives of furnace designers and operators 5
1.2 Where are furnaces used? Brief review of current furnace applications
and technology 7
1.2.1 Ceramics, brick making and pottery 7

1.2.2 Cement and lime 8
1.2.3 Glass making 11
1.2.4 Metal ore smelting 13
1.2.5 Metal refining 16
1.2.6 Flash and fluid bed furnaces 18
1.2.7 Metal physical processing 20
1.2.8 Incinerators and resource recovery furnaces 24
1.2.9 Furnaces with reducing atmospheres 24
1.2.10 Oil refining and petrochemical furnaces 25
1.3 Drivers for improved efficiency 28
1.4 Concluding remarks 29
References 29
Chapter 2 The combustion process 31
2.1 Simple combustion chemistry 32
2.1.1 The complete oxidation of carbon 32
2.1.2 The complete oxidation of hydrogen 32
2.1.3 The incomplete oxidation of carbon 33
2.1.4 The oxidation of carbon monoxide 33
2.2 Combustion calculations 33
2.3 Chemical reaction kinetics 36
2.3.1 Types of reactions 37
2.3.2 Reaction rate theory 38
viii Contents
2.3.3 Reaction rate behaviour 40
2.3.4 Burning droplets and particles 43
2.4 The physics of combustion 47
2.4.1 The role of primary air 50
2.4.2 The role of swirl flows 56
2.4.3 Turbulence in jets 57
2.4.4 Secondary flow aerodynamics 59

2.4.5 Effect of excess air on fuel consumption 61
2.4.6 Multiple burner installations 62
Nomenclature 63
References 64
Chapter 3 Fuels for furnaces 67
3.1 Gaseous fuels 69
3.1.1 Properties of natural gas 69
3.1.2 Manufactured gas 69
3.1.3 Wobbe number or index 71
3.1.4 Flammability limits 72
Calculation of the flammable limits for mixtures
of gases 72
Influence of temperature and pressure on the limits 73
3.1.5 Flame radiation from gaseous fuels 75
3.2 Liquid fuels 75
3.3 Solid fuels 77
3.3.1 Ash 79
3.4 Waste fuels 79
3.5 Choice of fuel 80
3.5.1 Furnace performance 81
Heat transfer 81
Furnace atmosphere 83
Flexibility of operation 83
Effect of ash 84
Refractory life 84
Fuel cost and security of supply 85
Fuel handling system capital and running costs 85
3.6 Safety 86
3.7 Emissions 86
Nomenclature 86

References 87
Solid fuel bibliography 88
Chapter 4 An introduction to heat transfer in furnaces 89
4.1 Conduction 90
4.1.1 Steady state conduction 91
4.1.2 Transient conduction 93
Analytical approach 93
Numerical approach 96
4.2 Convection 100
4.2.1 Dimensional analysis 101
4.2.2 Application to convective heat transfer 102
4.2.3 Evaluating convective heat transfer coefficients 104
4.2.4 High temperature convective heat transfer 108
4.3 Radiation 113
4.3.1 Physical basics of radiative exchange 114
4.3.2 Emissivity and absorptivity 117
4.3.3 View factors 121
Equivalent grey surface 126
4.3.4 Mean beam length 127
4.4 Electrical heating 128
4.4.1 Resistance heating 128
Direct resistance heating 129
Indirect resistance heating 129
4.4.2 Arc heating 129
Electrode devices 130
Electrodeless devices 131
4.4.3 Induction heating 132
4.4.4 Dielectric heating 133
4.4.5 Infrared heating 133
Nomenclature 134

References 136
Appendix 4A Tables of emissivity data 137
Chapter 5 Flames and burners for furnaces 141
5.1 Types of flame 142
5.1.1 Premixed flames 143
5.1.2 Turbulent jet diffusion flames 145
5.1.3 Heterogeneous combustion 145
Atomisation of liquid fuels and pulverisation of coal 146
The importance of drop and particle size 148
5.2 Function of a burner and basics of burner design 152
5.2.1 The essential importance of heat flux profiles 154
5.2.2 Flame stabilisation 155
5.3 Gas burners 158
5.3.1 Premixed burners 158
Effect of excess air (mixture ratio) on flame temperature 160
Radiant wall burners 161
Use of premix burners in low NO
x
applications 162
Safety issues with premix burners 162
Size limitations 165
Contents
ix
x Contents
5.3.2 Turbulent jet diffusion burners 165
5.3.3 Precessing jet diffusion burners 167
5.4 Oil burners 168
5.4.1 Turndown 171
5.4.2 Atomisers 172
Pressure jet atomisers 173

Twin fluid atomisers 176
5.5 Pulverised coal burners 179
5.6 Furnace aerodynamics 182
Burner and furnace air flow patterns 184
5.6.1 Single burner systems 184
Package burner installations 185
Rotary kilns and driers, etc. 185
5.6.2 Multiple burner systems 186
5.6.3 Combustion air duct design 188
5.6.4 Common windbox and plenum design 192
5.7 Combustion system scaling 193
5.7.1 Example of combustion system scaling 194
5.8 Furnace noise 196
5.8.1 Combustion roar 198
5.8.2 Nozzle and turbulent jet noise 198
5.8.3 Fan noise 199
5.8.4 Pipe and valve noise 199
5.8.5 Furnace noise attenuation 200
5.8.6 Combustion driven oscillations 201
Nomenclature 204
References 205
Chapter 6 Combustion and heat transfer modelling 209
6.1 Physical modelling 211
6.1.1 Thring-Newby parameter 214
6.1.2 Craya-Curtet parameter 214
6.1.3 Becker throttle factor 215
6.1.4 Curtet number 215
6.1.5 Relationship between scaling parameters 216
6.1.6 Determining the required model flows 216
6.1.7 Applying the scaling parameter 216

6.1.8 Applying a post-measurement correction 217
6.2 Mathematical modelling 217
6.2.1 Simple well-stirred furnace models 219
6.2.2 Long furnace models 227
6.2.3 Two- and three-dimensional zone models 229
6.2.4 Computational fluid dynamics models 233
Gridding of CFD models 235
Convergence of CFD models 237
6.2.5 Particle drag in combustion systems 237
6.3 Application of modelling to furnace design 238
Nomenclature 239
References 241
Chapter 7 Fuel handling systems 243
7.1 Gas valve trains 244
7.1.1 Safety shutoff systems 245
Double block and bleed 246
Leak testing and proving 246
7.2 Fuel oil handling systems 246
7.2.1 Storage, pumping and heating 247
7.2.2 Oil valve trains 249
7.3 Pulverised coal handling and firing systems 251
7.3.1 Raw coal bunkers and feeders 252
7.3.2 Coal grinding and drying 253
Coal drying characteristics 253
7.3.3 Coal mills 254
Ball mills 255
Vertical spindle mills 257
High speed mills 258
7.3.4 Coal mill grinding capacity 260
Coal fineness 261

Coal dryness 262
7.3.5 Pulverised coal grinding and firing systems 262
Direct and indirect firing systems 262
Direct firing 263
Semi-direct firing 263
Indirect firing 263
Semi-indirect firing 263
7.3.6 Coal system drying capacity 266
7.3.7 Coal firing system fans 270
7.3.8 Fine coal storage 271
7.3.9 Fine coal feeding and conveying 274
Volumetric feeders 275
Mass flow feeders 276
7.3.10 Pulverised coal conveying 278
7.4 Waste fuel handling 280
7.4.1 Waste gas fuel handling 281
7.4.2 Waste liquid fuel handling 282
7.4.3 Solids waste fuel handling 282
Size distribution 282
7.4.4 Environmental benefits and health hazards of
waste fuel utilisation 283
Nomenclature 284
References 284
Applicable codes and standards 285
Contents
xi
xii Contents
Chapter 8 Furnace control and safety 287
8.1 Process control 288
8.1.1 Basic furnace control strategies 289

Control of product temperature 289
Fuzzy logic and rule-based systems 290
8.2 Furnace instrumentation 290
8.2.1 Temperature measurement 290
8.2.2 Heat input measurement 295
Flow measurement of liquid and gaseous fuels 295
Calorific value measurement 296
Solid fuels 296
8.2.3 Determination of excess air 297
8.3 Flue gas analysis 300
8.3.1 Extractive gas sampling systems and analysers 302
Sample probe installation 302
Cold gas extractive systems 305
Hot wet gas extractive systems 305
Dilution extractive systems 306
8.3.2 In-situ systems 306
Dust monitors 307
Oxygen analysers 308
Cross-duct analysers 309
8.4 Combustion control 312
8.5 Ensuring furnace safety 313
8.5.1 Risk factors in furnace operation 313
8.5.2 Furnace start-up 314
Critical time for ignition during furnace start-up 316
8.5.3 Operation with insufficient combustion air 317
Corrective action for unintentional sub-stoichiometric operation 318
8.5.4 Flame quenching 318
8.5.5 Eliminating ignition sources 319
8.6 Burner management systems 319
8.6.1 Safety requirements for burner management systems 320

8.6.2 False trips 322
8.6.3 Achieving acceptable safety standards with programmable
logic controller burner management systems 323
8.6.4 Choosing an appropriate safety integrity level 324
8.6.5 Determining the safety integrity level of the BMS system 326
8.6.6 Flame detectors 329
Nomenclature 332
References 332
Certification and testing organisations 333
Chapter 9 Furnace efficiency 335
9.1 Furnace performance charts 338
9.2 Mass and energy balances 341
9.2.1 On-site measurement 342
Flue gas sampling and analysis 344
Calibration and errors in plant instrumentation 345
9.2.2 Constructing mass and energy balances 346
9.3 Energy conversion 358
9.3.1 Low and high grade heat 360
9.3.2 Exergy and pinch point analysis 362
9.4 Heat recovery equipment 363
9.4.1 Recuperative heat exchangers 364
9.4.2 Regenerative heat exchangers 366
9.4.3 General heat exchanger design procedure 368
9.5 Identifying efficiency improvements 369
Nomenclature 372
References 372
Chapter 10 Emissions and environmental impact 375
10.1 Formation of carbon monoxide 377
10.2 Formation of nitrogen oxides 378
10.2.1 Thermal NO

x
formation 379
10.2.2 Fuel NO
x
formation 381
10.2.3 Prompt NO
x
formation 382
10.2.4 NO
x
modelling 384
10.3 Formation of sulphur oxides 385
10.4 Formation of intermediate combustion products 386
10.4.1 Volatile organic compounds (VOCs) 386
10.4.2 Polycyclic aromatic hydrocarbons (PAH) 386
10.4.3 PCBs, dioxins and furans 387
10.5 Particulate emissions 390
10.5.1 Formation of soot 390
10.5.2 Formation and composition of fuel ash 393
10.5.3 Non-combustible volatile cycles 394
10.6 Environmental control of emissions 396
10.6.1 Prevention and abatement of emissions 397
Pre-flame control 397
In-flame control 399
End-of-pipe control 405
10.6.2 Dispersion modelling 408
References 409
Chapter 11 Furnace construction and materials 413
11.1 Basic performance requirements of the furnace structure 414
11.2 Basic construction methods 415

11.2.1 Brick lining 417
11.2.2 Monolithic linings 419
Castable refractory 419
Contents
xiii
xiv Contents
Traditional installation of castable refractory 420
Installation of castable refractory by gunning 421
Drying and curing of cast and gunned refractory 423
Mouldable and rammable refractories 424
11.2.3 Furnace steelwork 425
11.2.4 Furnace roof construction 426
11.2.5 Furnace cooling systems 428
11.3 Practical engineering considerations in the use of refractories 431
11.4 Ceramic refractory materials 433
11.4.1 Testing of refractories 434
11.4.2 Properties and uses of refractories 435
Silica and siliceous refractories 435
Alumina and aluminous refractories 435
Chromite/magnesite/alumina refractories 436
Dolomite refractories 437
Zircon and zirconia refractories 437
Carbon refractories 438
Insulating refractories 438
11.5 Heat resisting and refractory metals 438
11.5.1 Effect of elevated temperature on metal properties 439
11.5.2 High temperature alloys 441
Service temperature 442
Intergranular corrosion 442
Proprietary high nickel alloys 443

11.6 Practical engineering considerations in the use of high
temperature metals 443
11.7 Concluding remarks 444
References 445
Selection of relevant standards 445
Advisory organisations 446
Appendix 11A General properties of selected refractory materials 447
Chapter 12 Furnace design methods 455
12.1 Introduction 456
12.1.1 Design constraints 458
12.1.2 Cost of design changes 459
12.2 Conceptual design 459
12.2.1 Process functions 460
Straight-through furnace system 464
Separation furnace system 464
Combining furnace with downstream separation 464
Combining and separation furnace system 464
12.2.2 Defining the physical and chemical changes 464
12.2.3 Preliminary mass and energy balances 466
12.2.4 Reliability of available process knowledge 466
Existing processes 467
New processes and pilot plants 467
12.2.5 Effect of upstream and downstream processes 468
12.2.6 Fuel choice 469
Fuel chemical compatibility with the process 470
Heat transfer compatibility with the process 472
12.2.7 Potential for heat recovery and choice of equipment 474
Estimating the potential for heat recovery from hot
product 475
Estimating the potential for heat recovery from hot

flue gas 476
Estimating the potential for heat recovery from shell
losses or cooling water 478
Economic considerations 479
12.3 Furnace sizing 479
Slab heating furnace design 487
Oil heating furnace design 489
Aggregate processing furnace 492
12.4 Burner selection 496
12.5 Detailed analysis and validation of the furnace design 500
12.6 Furnace instrumentation and controls 501
Nomenclature 503
References 504
Author index 507
Subject index 511
Contents
xv
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Foreword
Furnaces have been used by humans for thousands of years and yet, beyond the
basic chemical reactions and heat release calculations, engineers rarely have any
formal training in relation to furnace design, combustion and their integration into
industrial processes. It is therefore not surprising that the solution to issues of emis-
sions, throughput and performance related problems have relied heavily on trial and
error and experience. Within industry in general equipment would be more success-
ful designed using the principals outlined in this book rather than relying on correla-
tions and scale up factors that have little, or no scientific basis to support them.
In the early 1970s the authors set themselves the goal of applying more scien-
tific methods to burner design than were currently used. This led to the realisation
that heat release from flames needed to be closely matched to the process require-

ments and that this was intimately related to the design of the furnace itself. Now,
more than ever before, the need to reduce ongoing energy costs and greenhouse
gas emissions requires decisions to be made on the basis of knowledge rather than
guesswork and past experience. This book, being one of only a few ever published
on the subject, highlights the applicable science which can be used to take much of
the guesswork out of furnace design. This book also emphasises the importance of
ensuring that individual pieces of equipment are appropriate for the whole process
and not simply selected on the basis of capacity or lowest capital cost.
Alcoa ’ s alumina refineries operate a range of processes and equipment includ-
ing boilers, rotary kilns, gas suspension alumina calciners and regenerative ther-
mal oxidisers and, like many other industries, have needed to address emissions,
throughput, performance and safety issues without a clear understanding of the sci-
ence and underlying design basis. This makes it difficult to undertake reliable root
cause analysis when problems occur.
In the early 1980s I was a mechanical engineer in Alcoa ’ s Equipment
Development Group. I had insufficient knowledge of, and certainly little experience
with, combustion processes and was faced with having to address throughput and
emissions related issues with alumina calciners. Fortunately I met the authors of
this book, Peter Mullinger and Barrie Jenkins, and was delighted to discover that a
scientific approach to furnace design is possible and methods are available to inves-
tigate and optimise many aspects of the combustion and associated processes.
It was highlighted through physical modelling of the flow patterns and acid
alkali modelling of the combustion process mixing that both the throughput and
emissions could be significantly improved by simply relocating fuel injection points.
These modifications proved to be effective and have now been employed on all
applicable alumina calciners at Alcoa ’ s refineries around the world saving other-
wise significant capital expenditure with potentially ineffective outcomes.
xviii Foreword
Since those early days the science as described in this book has been employed
over a wide range of process issues, from the design of new equipment and in the

solution of problems with existing equipment, positively impacting on performance
and reliability. More recently there has been a major application in relation to the
design of safety systems.
In particular the application of CFD modelling has highlighted to me that CFD
doesn ’ t replace the need for a deep understanding of the science of combustion
and furnace heat transfer processes as there are many traps for the unwary and the
uninformed.
Whether you are engaged in modelling, design of original equipment or equip-
ment upgrades or operation of combustion and furnace heat transfer processes, this
book provides much of the essential understanding required for success.
Greg Mills
Senior Consultant – Calcination
Technology Delivery Group
Alcoa World Alumina

Preface
This book has been more than 20 years in gestation; its lineage can be traced back
to Barrie ’ s lecturing at the University of Surrey in the late 1970s and early 1980s
and Peter ’ s first combustion course, provided internally to Rugby Cement ’ s engi-
neers in 1981.
We are not attempting to explain how to design any particular furnace but are
advocating a more scientific approach to furnace design than the traditional meth-
ods of scaling from the last design. New approaches are essential if we are to make
the advances needed to develop new processes for the twenty-first century and to
significantly reduce industrial energy consumption and emissions.
We have worked together to improve the efficiency of furnaces since 1977, start-
ing with rotary kilns in the cement industry when Roger Gates, Technical Director
of Rugby Cement, allowed Peter Mullinger to try the techniques developed by the
Fuels and Energy Research Group at the University of Surrey (FERGUS) on Rugby ’ s
South Ferriby No. 3 Kiln. This work was strongly encouraged by the plant manager,

the late Jim Bowman. The project was an immediate success and led to significantly
increased production and reduced fuel consumption. The success of that project
encouraged Rugby to sign a research agreement with the late Frank Moles, founder
of FERGUS, which committed Barrie Jenkins and the rest of the FERGUS team to
support Rugby Cement ’ s efforts to improve the production capacity, product quality
and fuel economy of their 21 kilns.
Following time in senior technical management roles with a company supplying
combustion equipment to the petrochemical industry, we founded our own business
where we applied more scientific methods to combustion and heat transfer problems
in all industries but principally those where the product was directly heated by the
flame.
We commercialised techniques that had been successfully developed and used
in-house by organisations such as British Gas, CEGB, and British Steel ’ s Swinden
Laboratories, Rotherham. We added acid/alkali modelling as a means of determin-
ing fuel/air mixing and flame shape, a technique that had seen little application
outside of research institutions at that time.
We built a successful business on this philosophy that continues today, managed
by our successors. During the time we managed it we applied these techniques to
over 250 projects in a wide range of furnace types in the alumina, cement, ceramic,
chrome, copper, lead, lime, steel, mineral sands, nickel, petrochemical, pulp and
paper and even the nuclear industry.
The idea for this book arose from the short course we provided on behalf of the
International Kiln Association to industry and to the Portland Cement Association
where we were regularly asked to recommend a book. We would have suggested
Professor Thring ’ s book The Science of Flames and Furnaces but it was long out of
print so all that we could offer were the course notes. We hope that this book goes
some way to filling the gap. It is the culmination of 30 years of working together,
albeit for the last few years from across the globe.
Peter Mullinger
Barrie Jenkins

xx Preface
Acknowledgements
Over the years it has been our privilege to work with many engineers, process
operators and other people who have encouraged and cooperated with us. Those
who are mentioned below are but a small selection, whose influence has strongly
encouraged the preparation of this book or who have directly contributed to it.
Of special influence was the late Frank Moles, founder of the Fuels and Energy
Research Group at the University of Surrey (FERGUS), who changed our think-
ing about industrial combustion, and Roger Gates, Technical Director of Rugby
Cement, who allowed us to implement Frank ’ s and our ideas on the company ’ s
plants.
We would like to thank many of the engineers at the former Midlands Research
Station of British Gas, especially Neil Fricker, Malcolm Hogarth, Mike Page, Rachel
Palmer, Jeff Rhine and Bob Tucker all of whom encouraged us to found Fuel and
Combustion Technology Ltd (FCT) in 1984 and to apply modelling techniques to
industrial combustion and heat transfer problems. We believe that we were the first
to use these techniques commercially on a large scale.
We owe a special debt of gratitude to those who were brave enough to give us
our early work at FCT, including Len May, Terry Henshaw and John Salisbury
of ARC Ltd, Erik Morgensen and Lars Christiansen of Haldor Topsoe A/S, Greg
Mills of Alcoa Australia, Ian Flower and Con Manias of Adelaide Brighton
Cement, Philip Alsop of PT Semen Cibinong, Terry Adams and Peter Gorog of the
Weyerhaeuser Company, all of whom were very influential in providing FCT with
its early projects.
Peter Mullinger would also particularly like to thank Emeritus Professor Sam
Luxton, who strongly supported his change of direction to an academic career in
1999. Without that change, it is unlikely that time would have ever been available
to complete this task. Peter would also like to thank his colleagues at the University
of Adelaide who either contributed directly to the book or who covered his teach-
ing duties during the first half of 2005 and first half of 2007, when the majority of

this book was written, in particular Prof. Keith King, Dr Peter Ashman, Prof. Gus
Nathan and Dr Yung Ngothai, A.Prof. Dzuy Nguyen and A.Prof. Brian O ’ Neill.
We should also like to thank those commercial companies who provided data,
photographs and drawings (who are acknowledged in the captions) but special
thanks are due to Adam Langman, who tuned our woeful sketches into artistic mas-
terpieces and Dave Crawley of DCDesign Services, who produced the process and
instrument drawings and flow diagrams. Grateful thanks are also due to Dr Christine
Bertrand, Mr Dennis Butcher and Dr John Smart for their invaluable contribution to
the sections on ‘ CFD modelling ’ , ‘ Furnace control and safety ’ and ‘ NO
x
formation
and control ’ respectively.
We hope that the errors are minimal, but there would be many more if it were
not for the excellent proofreading of Victoria Jenkins and Sheila Kelly, to whom
very special thanks are due. We could not have managed without you. Sheila, in
particular, has read every word but maintains that it is not as much fun as Harry
Potter!
Finally to all those who attended our industrial combustion short courses and
asked, ‘ What book is available? ’ It is available at last; we hope that you won ’ t be
disappointed.
xxii Acknowledgements
List of Figures
Figure 1.1 The iron bridge at Coalbrookdale showing the detail adjacent
to an abutment and Coalbrookdale by Night 2
Figure 1.2 The basic elements of a furnace 4
Figure 1.3 Classification of furnaces 6
Figure 1.4 Cross-section through a traditional downdraft pottery
batch kiln 8
Figure 1.5 Schematic of a mixed feed vertical shaft lime kiln and a
battery of six oil fired vertical shaft lime kilns 9

Figure 1.6 Twin shaft regenerative lime kiln 10
Figure 1.7 Modern cement kiln technology showing the cyclone preheater
tower on the left and the satellite cooler on the right 11
Figure 1.8 Schematic of a regenerative glass tank 12
Figure 1.9 Schematic of a modern blast furnace with Abraham Darby’s
pioneering furnace on the right 14
Figure 1.10 A reverbatory furnace for smelting copper sulphide ores 15
Figure 1.11 A Pierce-Smith converter 15
Figure 1.12 Outokumpu flash smelter for copper smelting 16
Figure 1.13 Cross-section through a copper anode furnace showing the
blowing, slag skimming and casting operations 17
Figure 1.14 A hydrogen atmosphere furnace for de-sulphurisation of
nickel briquettes 17
Figure 1.15 Fluid bed furnace for roasting copper ore 18
Figure 1.16 Flash furnace for alumina, lime or cement raw material
calcination 19
Figure 1.17 A large ingot reheating furnace 21
Figure 1.18 Continuous rapid heating furnace for small billets 22
Figure 1.19 Schematic of slab reheating furnace 22
Figure 1.20 Two large gearbox cases entering a large annealing furnace 23
Figure 1.21 A small incinerator designed by the authors to recover energy
from methanol contaminated water 24
Figure 1.22 Reducing kiln used in the mineral sands industry 25
Figure 1.23 Herreschoff multiple hearth roaster 26
Figure 1.24 Two types of refinery heater showing a cylindrical
heater and a cabin heater 26
Figure 1.25 Heat transfer coils for refinery heaters showing a coil
for a cabin heater and cylindrical heater 27
Figure 2.1 Effect of temperature on reaction rate in the extended
Arrhenius equation 40

xxiv List of Figures
Figure 2.2 Consequence of extended Arrhenius equation on temporal
consumption of species A 40
Figure 2.3 Extracted reactions from the ‘chemical soup’ of fossil fuel
combustion 41
Figure 2.4 Relationship between reactedness and mass consumption of
fuel and oxidant 42
Figure 2.5 Dependence of fuel reaction rate on the reactedness of
a flame 43
Figure 2.6 Equilibrium rate values for combustion reactions 44
Figure 2.7 Stages in the combustion of a fuel particle 45
Figure 2.8 Entrainment of secondary fluid into a free jet 48
Figure 2.9 Entrainment of fluid into a high momentum confined jet
with external recirculation 50
Figure 2.10 Entrainment of fluid into a swirling free jet with internal
recirculation 51
Figure 2.11 Typical aerodynamics in a rotary kiln associated with a grate
cooler, obtained by water-bead and air modelling 60
Figure 2.12 Typical aerodynamics in a flash calciner – obtained using
water-bead modelling 61
Figure 2.13 The effect of excess air on heat consumption (i.e. fuel
efficiency) for a cement kiln 62
Figure 2.14 The effect of excess air on flue gas heat losses 63
Figure 3.1 Combustion characteristics of methane 74
Figure 3.2 Viscosity temperature relationship for petroleum-based fuels 77
Figure 3.3 Effect of carbon/hydrogen ratio on flame emissivity 82
Figure 3.4 Effect of fuel type on heat transfer in a rotary kiln 82
Figure 4.1 Representation of section through compound refractory
furnace wall 91
Figure 4.2 Representation of ingot shape and reheating furnace firing

pattern 93
Figure 4.3 Gurnie-Lurie chart for long cylinder 94
Figure 4.4 Ingot heating predictions using Gurnie-Lurie chart 95
Figure 4.5 Representation of slab showing slice details 96
Figure 4.6 Graphical solution of slab heating problem 98
Figure 4.7 Representation of slab showing slice details with surface
heat transfer 99
Figure 4.8 Development of boundary layer over a flat plate 100
Figure 4.9 Temperature profile through a tube wall 105
Figure 4.10 The electromagnetic spectrum 113
Figure 4.11 Diagrammatic representation variation of E with  for
various types of emitter 116
Figure 4.12 Evaluation chart for approximate flame gas emissivity
calculations 120
Figure 4.13 Radiative exchange between large, closely spaced parallel
Lambert surfaces 122
Figure 4.14 Radiative exchange between two finite surfaces 123