Essentials of Fluidization Technology

TABLE OF CONTENTS
Preface xix

Acknowledgement xxi

1 Introduction, History, and Applications 1
John R. Grace

1.1 Definition and Origins 1

1.2 Terminology 2

1.3 Applications 3

1.4 Other Reasons for Studying Fluidized Beds 4

1.5 Sources of Information on Fluidization 8

References 8

Problems 9

2 Properties, Minimum Fluidization, and Geldart Groups 11
John R. Grace

2.1 Introduction 11

2.2 Fluid Properties 11

2.3 Individual Particle Properties 12

2.4 Bulk Particle Properties 16

2.5 Minimum Fluidization Velocity 18

2.6 Geldart Powder Classification for Gas Fluidization 24

2.7 Voidage at Minimum Fluidization 27

Solved Problem 28

Notations 28

References 29

Problems 31

3 Liquid Fluidization 33
Renzo Di Felice and Alberto Di Renzo

3.1 Introduction 33

3.2 Field of Existence 33

3.3 Overall Behaviour 35

3.4 Superficial Velocity–Voidage Relationship 37

3.5 Particle Segregation and Mixing 40

3.6 Layer Inversion Phenomena 41

3.7 Heat and Mass Transfer 46

3.8 Distributor Design 48

Solved Problems 48

Notations 51

References 52

Problems 53

4 Gas Fluidization Flow Regimes 55
Xiaotao Bi

4.1 Onset of Fluidization 55

4.2 Onset of Bubbling Fluidization 55

4.3 Onset of Slugging Fluidization 57

4.4 Onset of Turbulent Fluidization 58

4.5 Termination of Turbulent Fluidization 62

4.6 Fast Fluidization and Circulating Fluidized Bed 62

4.7 Flow Regime Diagram for Gas–Solid Fluidized Beds 64

4.8 Generalized Flow Diagram for Gas–Solid Vertical Transport 65

4.9 Effect of Pressure and Temperature on Flow Regime Transitions 68

Solved Problems 70

Notations 71

References 72

Problems 74

5 Experimental Investigation of Fluidized Bed Systems 75
Naoko Ellis

5.1 Introduction 75

5.2 Configuration and Design 76

5.3 Fluidizability and Quality of Fluidization 84

5.4 Instrumentation and Measurements 87

5.5 Operation of Fluidized Beds 93

5.6 Data Analysis 95

Solved Problem 98

Notations 98

References 100

Problems 104

6 Computational Fluid Dynamics and Its Application to Fluidization 109
Tingwen Li and Yupeng Xu

6.1 Two-Fluid Model 110

6.2 Discrete Particle Method 115

6.3 Gas–Solid Interaction 119

6.4 Boundary Conditions 122

6.5 Example and Discussion 123

6.6 Conclusion and Perspective 126

Solved Problem 126

Notations 127

References 128

7 Hydrodynamics of Bubbling Fluidization 131
John R. Grace

7.1 Introduction 131

7.2 Why Bubbles Form 133

7.3 Analogy Between Bubbles in Fluidized Beds and Bubbles in Liquids 134

7.4 Hydrodynamic Properties of Individual Bubbles 135

7.5 Bubble Interactions and Coalescence 139

7.6 Freely Bubbling Beds 139

7.7 Other Factors Influencing Bubbles in Gas-Fluidized Beds 146

Solved Problem 147

Notations 147

References 148

Problems 152

8 Slug Flow 153
John R. Grace

8.1 Introduction 153

8.2 Types of Slug Flow 153

8.3 Analogy Between Slugs in Fluidized Beds and Slugs in Liquids 155

8.4 Experimental Identification of the Slug Flow Regime 155

8.5 Transition to Slug Flow 156

8.6 Properties of Single Slugs 156

8.7 Hydrodynamics of Continuous Slug Flow 158

8.8 Mixing of Solids and Gas in Slugging Beds 159

8.9 Slugging Beds as Chemical Reactors 160

Solved Problem 160

Notations 161

References 161

9 Turbulent Fluidization 163
Xiaotao Bi

9.1 Introduction 163

9.2 Flow Structure 165

9.3 Gas and Solids Mixing 168

9.4 Effect of Column Diameter 172

9.5 Effect of Fines Content 173

Solved Problem 173

Notations 175

References 176

Problems 180

10 Entrainment from Bubbling and Turbulent Beds 181
Farzam Fotovat

10.1 Introduction 181

10.2 Definitions 182

10.3 Ejection of Particles into the Freeboard 184

10.4 Entrainment Beyond the Transport Disengagement Height 185

10.5 Entrainment from Turbulent Fluidized Beds 190

10.6 Parameters Affecting Entrainment of Solid Particles from Fluidized Beds 191

10.7 Possible Means of Reducing Entrainment 195

Solved Problem 195

Notations 196

References 197

Problems 201

11 Standpipes and Return Systems, Separation Devices, and Feeders 203
Ted M. Knowlton and Surya B. Reddy Karri

11.1 Standpipes and Solids Return Systems 203

11.2 Standpipes in Recirculating Solids Systems 212

11.3 Standpipes Used with Nonmechanical Solids Flow Devices 216

11.4 Solids Separation Devices 222

11.5 Solids Flow Control Devices/Feeders 230

Solved Problem 232

Notations 233

References 235

Problems 237

12 Circulating Fluidized Beds 239
Chengxiu Wang and Jesse Zhu

12.1 Introduction 239

12.2 Basic Parameters 241

12.3 Axial Profiles of Solids Holdup/Voidage 243

12.4 Radial Profiles of Solids Distribution 246

12.5 The Circulating Turbulent Fluidized Bed 249

12.6 Micro-flow Structure 250

12.7 Gas and Solids Mixing 256

12.8 Reactor Performance of Circulating Fluidized Beds 258

12.9 Effect of Reactor Diameter on CFB Hydrodynamics 261

Notations 262

References 263

Problems 268

13 Operating Challenges 269
Poupak Mehrani and Andrew Sowinski

13.1 Electrostatics 269

13.2 Agglomeration 273

13.3 Attrition 274

13.4 Wear 278

Solved Problems 280

Notations 286

References 287

Problem 290

14 Heat and Mass Transfer 291
Dening Eric Jia

14.1 Heat Transfer in Fluidized Beds 291

14.2 Mass Transfer in Fluidized Beds 318

Solved Problem 320

Notations 323

References 325

Problem 329

15 Catalytic Fluidized Bed Reactors 333
Andrés Mahecha-Botero

15.1 Introduction 333

15.2 Reactor Design Considerations 334

15.3 Reactor Modelling 334

15.4 Fluidized Bed Catalytic Reactor Models 342

15.5 Conclusions 356

Notations 357

References 358

Problems 361

16 Fluidized Beds for Gas–Solid Reactions 363
Jaber Shabanian and Jamal Chaouki

16.1 Introduction 363

16.2 Gas–Solid Reactions for a Single Particle 364

16.3 Reactions of Solid Particles Alone 377

16.4 Conversion of Particles Bathed by Uniform Gas Composition in a Dense Gas–Solid Fluidized Bed 378

16.5 Conversion of Both Solids and Gas 381

16.6 Thermal Conversion of Solid Fuels in Fluidized Bed Reactors 386

16.7 Final Remarks 390

Solved Problems 391

Acknowledgments 398

Notations 398

References 401

Problems 403

17 Scale-Up of Fluidized Beds 405
Naoko Ellis and Andrés Mahecha-Botero

17.1 Challenges of Scale 405

17.2 Historical Lessons 407

17.3 Influence of Scale on Hydrodynamics 408

17.4 Approaches to Scale-Up 412

17.5 Practical Considerations 415

17.6 Scale-Up and Industrial Considerations of Fluidized Bed Catalytic Reactors 419

Solved Problems 424

Notations 426

References 426

Problems 429

18 Baffles and Aids to Fluidization 431
Yongmin Zhang

18.1 Industrial Motivation 431

18.2 Baffles in Fluidized Beds 432

18.3 Other Aids to Fluidization 449

18.4 Final Remarks 452

Notations 452

References 452

Problem 455

19 Jets in Fluidized Beds 457
Cedric Briens and Jennifer McMillan

19.1 Introduction 457

19.2 Jets at Gas Distributors 457

19.3 Mass Transfer, Heat Transfer, and Reaction in Distributor Jets 467

19.4 Particle Attrition and Tribocharging at Distributor Holes 467

19.5 Jets Formed in Fluidized Bed Grinding 469

19.6 Applications 471

19.7 Jet Penetration 471

19.8 Solids Entrainment into Jets 471

19.9 Nozzle Design 472

19.10 Jet-Target Attrition 473

19.11 Jets Formed When Solids Are Fed into a Fluidized Bed 475

19.12 Jets Formed When Liquid Is Sprayed into a Gas-Fluidized Bed 477

19.13 Jet Penetration 478

Solved Problems 483

Notations 487

References 488

Problem 497

20 Downer Reactors 499
Changning Wu and Yi Cheng

20.1 Downer Reactor: Conception and Characteristics 499

20.2 Hydrodynamics, Mixing, and Heat Transfer of Gas–Solid Flow in Downers 501

20.3 Modelling of Hydrodynamics and Reacting Flows in Downers 508

20.4 Design and Applications of Downer Reactors 514

20.5 Conclusions and Outlook 523

Solved Problem 523

Notations 525

References 526

Problems 528

21 Spouted (and Spout-Fluid) Beds 531
Norman Epstein

21.1 Introduction 531

21.2 Hydrodynamics 532

21.3 Heat and Mass Transfer 538

21.4 Chemical Reaction 538

21.5 Spouting vs. Fluidization 539

21.6 Spout-Fluid Beds 540

21.7 Non-conventional Spouted Beds 543

21.8 Applications 546

21.9 Multiphase Computational Fluid Dynamics 547

Solved Problem 547

Notations 548

References 549

22 Three-Phase (Gas–Liquid–Solid) Fluidization 553
Dominic Pjontek, Adam Donaldson, and Arturo Macchi

22.1 Introduction 553

22.2 Reactor Design and Scale-up 556

22.3 Compartmental Flow Models 558

22.4 Fluid Dynamics in Three-Phase Fluidized Beds 562

22.5 Phase Mixing, Mass Transfer, and Heat Transfer 569

22.6 Summary 574

Solved Problems 574

Notations 582

References 585

Problems 587

Index 591