Boilers and Burners Design and Theory

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Boilers and Burners Design and Theory

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Series Preface

Mechanical engineering, an engineering discipline borne of the needs of the industrial
revolution, is once again asked to do its substantial share in the call for
industrial renewal. The general call is urgent as we face profound issues of productivity
and competitiveness that require engineering solutions, among others. The
Mechanical Engineering Series features graduate texts and research monographs
intended to address the need for information in contemporary areas of mechanical
engineering.
The series is conceived as a comprehensive one that covers a broad range of concentrations
important to mechanical engineering graduate education and research.
We are fortunate to have a distinguished roster of consulting editors on the advisory
board, each an expert in one of the areas of concentration. The names of the
consulting editors are listed on the facing page of this volume. The areas of concentration
are: applied mechanics; biomechanics; computational mechanics; dynamic
systems and control; energetics; mechanics of materials; processing; production
systems; thermal science; and tribology.
I am pleased to present this volume in the series: Boilers and Burners: Design
and Theory, by Prabir Basu, Cen Kefa, and Louis Jestin. The selection of this
volume underscores again the interest of the Mechanical Engineering Series to
provide our readers with topical monographs as well as graduate texts in a wide
variety of fields.

Preface

Modern society owes a great deal to fossil fuels, which have accelerated man’s
progress from the cave to the present age of jets and computers. Utilization of
this precious gift of nature is central and critical to our lives. This book is about
rational utilization of fossil fuels for generation of heat or power. The book is
intended for undergraduate and graduate students with an interest in steam power
plants, burners, or furnaces. For researchers, it is a resource for applications of
theory to practice. Plant operators will find solutions to and explanations of many of
their daily operational problems. Designers will find this book fiiled with required
data, design methods, and equations. Finally, consultants will find it useful for
design evaluation.
This book uses a format of theory-based practice. Each chapter begins with an explanation
of a process. Then it develops equations from first principles and presents
experiment-based empirical equations. This is followed by design methodology,
which in many cases is explained by worked-out examples. Thus, the book retains
the interest of the reader and help remove doubts if any on the theory.
The present monograph is a joint effort of writers on three continents-Asia,
Europe, and North America-and a marriage of two scientific traditions-Eastern
and Western. In the West, boilers and burners are designed for high levels of
performance, but their design methods and data are buried under commercial
secrecy. Very few books or even research papers are available giving exact design
standards. Thus, there is limited opportunity for information exchange on design
data and methodologies. The energy industry in the Eastern European countries
and China, on the other hand, did not have much commercial impetus for burying
their design standards under secrecy. So their design methods and data were freely
exchanged, and debated in the scientific community. Eventually, they formed into
national standards. These elaborate thermal design standards were developed on
the basis of experience in the design and operations of thousands of boilers and
burners. However, the difference in language and scientific conventions prevented
easy access of Western readers to this wealth of information available in China
and Eastern European countries. The present book synthesizes design methods
and data from both sides of the scientific world and presents the same in a simple
Western format.
The book greally benefitted from diverse professional backgrounds of three
authors. Professor Cen Kefa, Head of the Institute of Thermal Power Engineering
of Zhejiang University, is holder of the coveted distinction of Academician for
his lifelong contribution to the Chinese boiler industry. He received his early
education in boilers and power plants in the former Soviet Union. Thereafter, he
worked closely with Chinese boiler and burner industry manufacturers perfecting
their design standards. The research and development work he and his colleagues
have carried out in the past four decades on boilers and burners greatly contributed
to this book.
Dr. Louis Jestin, Head of the Heat Exchanger Section of the Fossil Fuel Division
of the Electricite de France, is a specialist in heat transfer. He is involved in
the design review of all new circulating fluidized bed boilers commissioned by
this company. His team also carried out in-depth technical analyses of several
supercritical boiler projects. His intimate contact with modern fossil fuel boilers
and familiarity with European designs greatly enriched this book.
Dr. Prabir Basu, Professor in Mechanical Engineering in Dalhousie University
and President of Greenfield Research Inc., is a specialist in fluidized bed boilers.
He carried out extensive design and development work in government research
laboratory, boiler manufacturing company, and universities. He participated in the
development of the Indian boiler standard. His research and design experience in
fluidized bed boilers contributed much to this book.
We thank Mr. S.S. Kelkar, Ex-Vice President, Deutsche Babcock Power System
Ltd., India, who used his 30 years experience of boiler design and familiarity with
German, British, Indian, and U.S. boiler codes to write Chapter 17 on pressure
part design.
Our special thanks go to Prof. Jianren Fan, Prof. Qiang Yao, and Dr. Zuohe Chi
for their significant contributions to a number of chapters in this book. Their tireless
effort in data collection, draft preparation, and figure drafting provided critical
support to this project. Dr. Jayson Greenblatt and Prof. David Mackay proofread
many versions of the manuscript. Dr. Leming Cheng, Mrs. Sanja Boskovic, and
Mr. Animesh Dutta greatly helped with preparation of the final manuscript.
Finally the authors thank their waves for their support to this project.

Contents

Series Preface
Pmface
1 Introduction 1
1 . 1 Principles of Boiler Operation . . . . . . . . . . . . . . . . . . . 1
1-2 Classification of Boilers . . . . . . . . . . . . . . . . . . . . . . . 6
1-3 Description of Boilers . . . . . . . . . . . . . . . . . . . . . . . . 6
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2 General Design Considerations 15
2- 1 Boiler Specifications . . . . . . . . . . . . . . . . . . . . . . . . . 15
2-2 Design Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3 Fuel and Combustion Calculations 21
3- 1 Features of Fuel . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3-2 Stoichiometric Calculations . . . . . . . . . . . . . . . . . . . . . 28
3-3 Enthalpy Calculation of Air and Combustion Products . . . . . . 36
3-4 Heat Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
3-5 Generation of SO2 and NOx . . . . . . . . . . . . . . . . . . . . . 46
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4 Coal Preparation Systems for Boilers 52
4- 1 Coal Preparation Systems . . . . . . . . . . . . . . . . . . . . . . 52
4-2 Pulverizing Properties of Coal . . . . . . . . . . . . . . . . . . . 56
4-3 Pulverizing Air System . . . . . . . . . . . . . . . . . . . . . . . 59
4-4 Size-Reducing Machines . . . . . . . . . . . . . . . . . . . . . . 63
4-5 Other Components for Coal Reparation Systems . . . . . . . . . 70
4-6 Design of Coal Preparation System
for Pulverized Coal Boilers . . . . . . . . . . . . . . . . . . . . . 73
4-7 Fuel Feeding in Fluidized Bed Boilers . . . . . . . . . . . . . . . 76
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
5 Design of Oil Burners 80
5- 1 Design of Oil Supply System . . . . . . . . . . . . . . . . . . . . 80
5-2 Oil Atomizers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
5-3 Air Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
5-4 Design Principles of Oil Fired Boilers . . . . . . . . . . . . . . . 118
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
6 Boiler Furnace Design Methods 128
6-1 General Design Principles . . . . . . . . . . . . . . . . . . . . . . 128
6-2 Flame Emissivity . . . . . . . . . . . . . . . . . . . . . . . . . . 135
6-3 Heat Transfer Calculations for the PC Boiler Furnace . . . . . . . 140
6-4 Water Wall Arrangement . . . . . . . . . . . . . . . . . . . . . . 146
6-5 Fouling and Thermal Efficiency Factors
for Water Wall Tubes . . . . . . . . . . . . . . . . . . . . . . . . 147
6-6 Temperature Field Coefficient. M . . . . . . . . . . . . . . . . . 149
6-7 Furnace Ernissivity . . . . . . . . . . . . . . . . . . . . . . . . . 150
6-8 Distribution of Heat Load in Furnace . . . . . . . . . . . . . . . . 151
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
7 Convective Heating Surfaces 161
7- 1 Design of Superheater and Reheater . . . . . . . . . . . . . . . . 161
7-2 Temperature Control in Superheater and Reheater . . . . . . . . . 167
7-3 Adjustment of Heat Absorption in Superheater and Reheater . . . 172
7-4 Economizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
7-5 Air Heater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180
7-6 Arrangement of Back-Pass Heating Surfaces . . . . . . . . . . . 185
7-7 Heat Transfer Calculations for Convective Heating Surfaces . . . 187
7-8 Design Methods of Convection Heating Surfaces . . . . . . . . . 206
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
8 Swirl Burners 212
8- 1 Design of a Swirl Burner . . . . . . . . . . . . . . . . . . . . . . 212
8-2 Flow Resistance in Swirl Burners . . . . . . . . . . . . . . . . . . 225
8-3 Examples of Swirl Burners . . . . . . . . . . . . . . . . . . . . . 226
8-4 Arrangement of Multiple Swirl Burners . . . . . . . . . . . . . . 230
8-5 Design Procedure of Swirl Burners . . . . . . . . . . . . . . . . . 233
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 1
9 Design of Novel Burners 242
9- 1 Types of PC Burners . . . . . . . . . . . . . . . . . . . . . . . . . 242
9-2 PC Burner With Blunt Body . . . . . . . . . . . . . . . . . . . . 243
9-3 Precombustion Chamber Burner . . . . . . . . . . . . . . . . . . 246
9-4 BoatBurner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
9-5 Co-Flow Jet Burner With High Differential Velocity . . . . . . . 249
9-6 Counter-Flow Jet Burner . . . . . . . . . . . . . . . . . . . . . . 250
9-7 Dense and Lean Phase PC Burner . . . . . . . . . . . . . . . . . 253
9-8 Down-Shot Flame Combustion Technique . . . . . . . . . . . . . 257
9-9 Low NO. Burner . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267
18 Tangentially Fired Burners 269
10- 1 General Descriptions . . . . . . . . . . . . . . . . . . . . . . . 269
10-2 Design of Burners With Peripheral Air . . . . . . . . . . . . . 279
10-3 Design of Tilting Burners . . . . . . . . . . . . . . . . . . . . . 281
10-4 Burners for Bituminous Coal . . . . . . . . . . . . . . . . . . . 284
10-5 Anthracite and Lean Coal Fired PC Burner . . . . . . . . . . . 286
10-6 Brown Coal Fired Direct Burner . . . . . . . . . . . . . . . . . 291
10-7 Multifuel Burner . . . . . . . . . . . . . . . . . . . . . . . . . 293
10-8 Design Methods for Tangentially Fired Boilers . . . . . . . . . 294
10-9 Example of Burner Design . . . . . . . . . . . . . . . . . . . . 297
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . 300
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 301
1 Fluidized Bed Boilers 302
1 1. 1 Fluidized Bed Boiler . . . . . . . . . . . . . . . . . . . . . . . 302
1 1-2 Major Features of Fluidized Bed Boilers . . . . . . . . . . . . 304
I 1-3 Basics of Fluidized Beds . . . . . . . . . . . . . . . . . . . . . 309
11 -4 Bubbling Fluidized Bed Boilers . . . . . . . . . . . . . . . . . 314
11 -5 Circulating Fluidized Bed Boilers . . . . . . . . . . . . . . . . 319
11 -6 Distributor Plates . . . . . . . . . . . . . . . . . . . . . . . . . 327
1 1-7 Loop Seals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 331
1 1-8 Gas-Solid Separators . . . . . . . . . . . . . . . . . . . . . . . 334
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . 340
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 344
12 Steam-Water Circulation in Boiler 347
2 -1 Natural Circulation System . . . . . . . . . . . . . . . . . . . . 346
12-2 Calculations for Simple and Complex Tube Circuits . . . . . . 359
12-3 Two-Phase Flow Resistance . . . . . . . . . . . . . . . . . . . 360
12-4 Height of Economizer Section in the Riser . . . . . . . . . . . 362
12-5 Worked-Out Example . . . . . . . . . . . . . . . . . . . . . . . 364
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . 369
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371
13 Forced Circulation for Supercritical or Subcritical Boilers 372
1 3- 1 General Description . . . . . . . . . . . . . . . . . . . . . . . . 373
13-2 Design Principle of Forced Circulation Boiler . . . . . . . . . 374
13-3 Features of Forced Circulation Boilers . . . . . . . . . . . . . . 375
13-4 Supercritical Boilers . . . . . . . . . . . . . . . . . . . . . . . 381
14 Corrosion and Fouling of Heat Transfer Surfaces 385
14-1 High-Temperature Corrosion of External Surfaces . . . . . . . 386
14-2 Prevention of High-Temperature Corrosion . . . . . . . . . . . 392
14-3 Low-Temperature Corrosion on External Surfaces . . . . . . . 397
14-4 Corrosion and Scaling of Internal Surfaces . . . . . . . . . . . 402
14-5 Fouling and Slagging . . . . . . . . . . . . . . . . . . . . . . . 406
14-6 Calculation of Soot and Ash Deposition . . . . . . . . . . . . . 412
14-7 Prediction of Slagging Potential . . . . . . . . . . . . . . . . . 416
14-8 Design Measure for Reduction of Fouling and Slagging . . . . 421
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . 423
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 424
I5 Erosion Prevention in Boilers 426
15- 1 Theory of Erosion of Heating Surfaces . . . . . . . . . . . . . 426
15-2 Worked-OutExample . . . . . . . . . . . . . . . . . . . . . . . 431
15-3 Factors Influencing Tube Erosion . . . . . . . . . . . . . . . . 433
15-4 Analyses of Erosion of Tube Banks in Cross-Flow . . . . . . . 436
15-5 Permissible Gas Velocity for Safe Operation . . . . . . . . . . 439
15-6 Erosion Protection for the Economizer.
Reheater. and Superheater . . . . . . . . . . . . . . . . . . . . 444
15-7 Erosion in Tubular Air Heaters . . . . . . . . . . . . . . . . . . 448
15-8 Erosion in Fluidized Bed Boilers . . . . . . . . . . . . . . . . . 450
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . 454
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 456
16 Pressure Drop in Gas and Air Ducts 457
16- 1 Draft Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . 457
16-2 Pressure Drop in Air and Gas Duct Systems . . . . . . . . . . 459
16-3 Pressure Drop Across Heating Surfaces . . . . . . . . . . . . . 466
16-4 Pressure Drop in Natural Draft Gas Path . . . . . . . . . . . . 471
16-5 Pressure Drop Through Air Ducts . . . . . . . . . . . . . . . . 475
16-6 Selection of Fans . . . . . . . . . . . . . . . . . . . . . . . . . 479
16-7 h-essure Drop Through Water or Steam Tubes . . . . . . . . . 480
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . 481
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 483
17 Mechanical Design of Pressure Parts 485
17-1 Selection of Materials . . . . . . . . . . . . . . . . . . . . . . . 485
17-2 Important Mechanical Properties of Various Materials . . . . . 487
17-3 Fundamental Metallurgical Concepts
to Improve Steel Properties . . . . . . . . . . . . . . . . . . . 490
17-4 Design Methods . . . . . . . . . . . . . . . . . . . . . . . . . 495
17-5 Thickness (Scantling)Calculations . . . . . . . . . . . . . . . 509
Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . 523
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . 523
18 Tables of Design Data 524
Table 1 8- I Specific heat of air. flue gas and
ash at atmospheric pressure . . . . . . . . . . . . . . . . 525
Table 18-2 Some physical properties of iron.
metal. and selected steels . . . . . . . . . . . . . . . . . 526
Table 18-3 Linear thema1 expansion of steel . . . . . . . . . . . . 526
Table 18-4 Specific heat capacity of steel . . . . . . . . . . . . . . 527
Table 18-5 Electrical resistivity of steel . . . . . . . . . . . . . . . 527
Table 18-6 Thermal conductivity of steel . . . . . . . . . . . . . . 527
Table 18-7 Density. heat capacity. and heat conductivity
for metals . . . . . . . . . . . . . . . . . . . . . . . . . 528
Table 18-8 Thermal properties of the saturated water and steam
(arranged by temperature) . . . . . . . . . . . . . . . . 530
Table 18-9 Thermal properties of the saturated water and steam
(arranged by pressure) . :. . . . . . . . . . . . . . . . 532
Table 1 8- 10 Thermal properties of unsaturated water and
superheated steam at different pressures . . . . . . . . . 534
Table 18- 1 1 Conversion factors . . . . . . . . . . . . . . . . . . . . 541
Index 553