Industrial and process furnaces : Principles, design, and operation

PETER MULLIN EF? AND BARRIE JENKINS

Industrial and Process Furnaces

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Industrial and Process

Furnaces

Principles, Design and Operation

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THƯ VIỆN

PHÒỈV6 ĐỌC Peter Mullinger y_________

Associate Professor, School o f Chemical Engineering

University o f Adelaide, South Australia

Barrie Jenkins

Consulting Engineer, High Wycombe, Bucks, UK

ELSEVIER

AMSTERDAM • BOSTON • HEIDELBERG • LONDON • NEWYORK • OXFORD

PARIS • SAN DIEGO • SAN FRANCISCO • SINGAPORE • SYDNEY • TOKYO

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First edition 2008

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ELSEV IER B O O K A ID

lm cn u ili< m .il Sabre I'OLinclcttion

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.

Contents

Forew ord

Preface

A cknowledgem ents

List o f Figures

List o f Tables

Chapter 1 Introduction

1.1 What is a furnace?

1.1.1 Furnace outline

1.1.2 Furnace classification

1.1.3 Principle objectives of furnace designers and operators

1 2 Where are furnaces used? Brief review of current furnace applications

and technology

1.2.1 Ceramics, brick making and pottery

1.2.2 Cement and lime

1.2.3 Glass making

1.2.4 Metal ore smelting

1.2.5 Metal refining

1.2.6 Flash and fluid bed furnaces

1.2.7 Metal physical processing

1.2.8 Incinerators and resource recovery furnaces

1.2.9 Furnaces with reducing atmospheres

1.2.10 Oil refining and petrochemical furnaces

Drivers for improved efficiency

Concluding remarks

1.3

1.4

References

X V I1

xix

xxi

xxiii

xxxi

1

3

4

5

5

7

7

8

11

13

16

18

20

24

24

25

28

29

29

Chapter 2 The combustion process

2.1

2.2

2.3

Simple combustion chemistry

2.1.1 The complete oxidation of carbon

2.1.2 The complete oxidation of hydrogen

2.1.3 The incomplete oxidation of carbon

2.1.4 The oxidation of carbon monoxide

Combustion calculations

Chemical reaction kinetics

2.3.1 Types of reactions

2.3.2 Reaction rate theory

31

32

32

32

33

33

33

36

37

38

v iii Contents

2.3.3 Reaction rate behaviour

2.3.4 Burning droplets and particles

2.4 The physics of combustion

2.4.1 The role of primary air

The role of swirl flows

Turbulence in jets

Secondary flow aerodynamics

Effect of excess air on fuel consumption

Multiple burner installations

2.4.2

2.4.3

2.4.4

2.4.5

2.4.6

Nomenclature

References

40

43

47

50

56

57

59

61

62

63

64

Chapter 3 Fuels for furnaces

3.1

3.2

3.3

3.4

3.5

Gaseous fuels

3.1.1 Properties of natural gas

Manufactured gas

Wobbe number or index

Flammability limits

Calculation o f the flam m able limits for mixtures

o f gases

Influence o f temperature and pressure on the limits

Flame radiation from gaseous fuels

3.1.2

3.1.3

3.1.4

3.1.5

Liquid fuels

Solid fuels

3.3.1 Ash

Waste fuels

Choice of fuel

3.5.1 Furnace performance

Heat transfer

Furnace atm osphere

Flexibility o f operation

F.ffect o f ash

Refractory life

Fuel cost and security o f supply

Fuel handling system capital and running costs

3.6 Safety

3.7 Emissions

Nomenclature

References

Solid fuel bibliography

67

69

69

69

71

72

72

73

75

75

77

79

79

80

81

81

83

83

84

84

85

85

86

86

86

87

Chapter 4 An introduction to heat transfer in furnaces

4.1 Conduction

4.1.1 Steady state conduction

89

90

91

Contents ix

4.1.2 Transient conduction 93

Analytical approach 93

N um erical 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

D irect resistance heating 129

Indirect resistance heating 129

4.4.2 Arc heating 129

E lectrode devices 130

E lectrodeless 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

Atom isation o f liquid fuels and pulverisation o f coal 146

The im portance o f 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

E ffect o f excess air (mixture ratio) on flam e tem perature 160

Radiant wall burners 161

Use o f prem ix burners in low NOỵ applications 162

Safety issues with prem ix burners 162

Size limitations 165