Introduction to Particle Technology (eBook)

Martin Rhodes holds a Bachelor's degree in chemical engineering and a PhD in particle technology from Bradford University in the UK, industrial experience in chemical and combustion engineering and many years experience as an academic at Bradford and Monash Universities. He has research interests in various aspects of gas fluidization and particle technology, areas in which he has many refereed publications in journals and international conference proceedings. Martin is on the editorial boards of Powder Technology and KONA and on the advisory board of Advanced Powder technology. Martin has a keen interests in particle technology education and has published books and CDROM on Laboratory Demonstrations and directed continuing education courses for industry in the UK and Australia. He was co-founder of the Australasian Particle Technology Society. Martin has a Personal Chair in the Department of Chemical Engineering at Monash University, Australia, where he is presently Head of Department.

Introduction to Particle Technology 1
Contents 7
About the Contributors 15
Preface to the Second Edition 17
Preface to the First Edition 19
Introduction 23
1 Particle Size Analysis 25
1.1 Introduction 25
1.2 Describing the Size of a Single Particle 25
1.3 Description of Populations of Particles 28
1.4 Conversion Between Distributions 29
1.5 Describing the Population by a Single Number 31
1.6 Equivalence of Means 34
1.7 Common Methods of Displaying Size Distributions 35
1.7.1 Arithmetic-normal Distribution 35
1.7.2 Log-normal Distribution 35
1.8 Methods of Particle Size Measurement 36
1.8.1 Sieving 36
1.8.2 Microscopy 37
1.8.3 Sedimentation 37
1.8.4 Permeametry 39
1.8.5 Electrozone Sensing 39
1.8.6 Laser Diffraction 40
1.9 Sampling 40
1.10 Worked Examples 41
Test Yourself 49
Exercises 49
2 Single Particles in a Fluid 53
2.1 Motion of Solid Particles in a Fluid 53
2.2 Particles Falling Under Gravity Through a Fluid 55
2.3 Non-Spherical Particles 57
2.4 Effect of Boundaries on Terminal Velocity 58
2.5 Further Reading 59
2.6 Worked Examples 59
Test Yourself 68
Exercises 70
3 Multiple Particle Systems 75
3.1 Settling of a Suspension of Particles 75
3.2 Batch Settling 77
3.2.1 Settling Flux as a Function of Suspension Concentration 77
3.2.2 Sharp Interfaces in Sedimentation 78
3.2.3 The Batch Settling Test 80
3.2.4 Relationship Between the Height – Time Curve and the Flux Plot 83
3.3 Continuous Settling 85
3.3.1 Settling of a Suspension in a Flowing Fluid 85
3.3.2 A Real Thickener (with Upflow and Downflow Sections) 87
3.3.3 Critically Loaded Thickener 88
3.3.4 Underloaded Thickener 89
3.3.5 Overloaded Thickener 89
3.3.6 Alternative Form of Total Flux Plot 90
3.4 Worked Examples 92
Test Yourself 103
Exercises 105
4 Slurry Transport 115
4.1 Introduction 115
4.2 Flow Condition 115
4.3 Rheological Models For Homogeneous Slurries 117
4.3.1 Non-Newtonian Power-law Models 118
4.3.2 Pressure Drop Prediction for Slurries Exhibiting Power-law Rheology 120
4.3.3 Non-Newtonian Yield Stress Models 123
4.3.4 Pressure Drop Prediction for Slurries Exhibiting Bingham Plastic Rheology 125
4.4 Heterogeneous Slurries 127
4.4.1 Critical Deposition Velocity 128
4.5 Components of a Slurry Flow System 128
4.5.1 Slurry Preparation 128
4.5.2 Pumps 129
4.5.3 Pipeline 132
4.5.4 Slurry De-watering 132
4.6 Further Reading 133
4.7 Worked Examples 133
Test Yourself 138
Exercises 138
5 Colloids and Fine Particles 141
5.1 Introduction 141
5.2 Brownian Motion 142
5.3 Surface Forces 144
5.3.1 van der Waals Forces 145
5.3.2 Electrical Double Layer Forces 148
5.3.3 Adsorbing Polymers, Bridging and Steric Forces 151
5.3.4 Other Forces 152
5.3.5 Net Interaction Force 153
5.4 Result of Surface Forces on Behaviour in Air and Water 154
5.5 Influences of Particle Size and Surface Forces on Solid/Liquid Separation by Sedimentation 156
5.5.1 Sedimentation Rate 156
5.5.2 Sediment Concentration and Consolidation 157
5.6 Suspension Rheology 158
5.7 Influence of Surface Forces on Suspension Flow 163
5.7.1 Repulsive Forces 163
5.7.2 Attractive Forces 164
5.8 Nanoparticles 168
5.9 Worked Examples 169
Test Yourself 173
Exercises 174
6 Fluid Flow Through a Packed Bed of Particles 177
6.1 Pressure Drop – Flow Relationship 177
6.1.1 Laminar Flow 177
6.1.2 Turbulent Flow 179
6.1.3 General Equation for Turbulent and Laminar Flow 179
6.1.4 Non-spherical Particles 180
6.2 Filtration 181
6.2.1 Introduction 181
6.2.2 Incompressible Cake 181
6.2.3 Including the Resistance of the Filter Medium 183
6.2.4 Washing the Cake 183
6.2.5 Compressible Cake 184
6.3 Further Reading 185
6.4 Worked Examples 185
Test Yourself 189
Exercises 189
7 Fluidization 193
7.1 Fundamentals 193
7.2 Relevant Powder and Particle Properties 196
7.3 Bubbling and Non-Bubbling Fluidization 197
7.4 Classification of Powders 198
7.5 Expansion of a Fluidized Bed 202
7.5.1 Non-bubbling Fluidization 202
7.5.2 Bubbling Fluidization 204
7.6 Entrainment 206
7.7 Heat Transfer in Fluidized Beds 210
7.7.1 Gas – Particle Heat Transfer 210
7.7.2 Bed – Surface Heat Transfer 212
7.8 Applications of Fluidized Beds 215
7.8.1 Physical Processes 215
7.8.2 Chemical Processes 215
7.9 A Simple Model for the Bubbling Fluidized Bed Reactor 218
7.10 Some Practical Considerations 222
7.10.1 Gas Distributor 222
7.10.2 Loss of Fluidizing Gas 222
7.10.3 Erosion 223
7.10.4 Loss of Fines 223
7.10.5 Cyclones 223
7.10.6 Solids Feeders 223
7.11 Worked Examples 223
Test Yourself 229
Exercises 230
8 Pneumatic Transport and Standpipes 235
8.1 Pneumatic Transport 235
8.1.1 Dilute Phase and Dense Phase Transport 236
8.1.2 The Choking Velocity in Vertical Transport 236
8.1.3 The Saltation Velocity in Horizontal Transport 238
8.1.4 Fundamentals 239
8.1.5 Design for Dilute Phase Transport 243
8.1.6 Dense Phase Transport 248
8.1.7 Matching the System to the Powder 254
8.2 Standpipes 255
8.2.1 Standpipes in Packed Bed Flow 255
8.2.2 Standpipes in Fluidized Bed Flow 256
8.2.3 Pressure Balance During Standpipe Operation 259
8.3 Further Reading 261
8.4 Worked Examples 261
Test Yourself 267
Exercises 268
9 Separation of Particles from a Gas: Gas Cyclones 271
9.1 Gas Cyclones – Description 272
9.2 Flow Characteristics 273
9.3 Efficiency of Separation 273
9.3.1 Total Efficiency and Grade Efficiency 273
9.3.2 Simple Theoretical Analysis for the Gas Cyclone Separator 274
9.3.3 Cyclone Grade Efficiency in Practice 276
9.4 Scale-up of Cyclones 277
9.5 Range of Operation 279
9.6 Some Practical Design and Operation Details 281
9.6.1 Effect of Dust Loading on Efficiency 281
9.6.2 Cyclone Types 281
9.6.3 Abrasion 281
9.6.4 Attrition of Solids 282
9.6.5 Blockages 282
9.6.6 Discharge Hoppers and Diplegs 282
9.6.7 Cyclones in Series 283
9.6.8 Cyclones in Parallel 283
9.7 Worked Examples 283
Test Yourself 286
Exercises 287
10 Storage and Flow of Powders – Hopper Design 289
10.1 Introduction 289
10.2 Mass Flow and Core Flow 289
10.3 The Design Philosophy 292
10.3.1 Flow–No Flow Criterion 292
10.3.2 The Hopper Flow Factor, ff 293
10.3.3 Unconfined Yield Stress, ?y 293
10.3.4 Powder Flow Function 293
10.3.5 Critical Conditions for Flow 294
10.3.6 Critical Outlet Dimension 294
10.3.7 Summary 295
10.4 Shear Cell Test 296
10.5 Analysis of Shear Cell Test Results 298
10.5.1 Mohr’s Circle–in Brief 298
10.5.2 Application of Mohr’s Circle to Analysis of the Yield Locus 298
10.5.3 Determination of ?y and ?c 299
10.5.4 Determination of ? from Shear Cell Tests 300
10.5.5 The Kinematic Angle of Friction between Powderand Hopper Wall, ?w 300
10.5.6 Determination of the Hopper Flow Factor, ff 301
10.6 Summary of Design Procedure 302
10.7 Discharge Aids 305
10.8 Pressure on the Base of a Tall Cylindrical Bin 305
10.9 Mass Flow Rates 308
10.10 Conclusions 309
10.11 Worked Examples 309
Test Yourself 313
Exercises 313
11 Mixing and Segregation 317
11.1 Introduction 317
11.2 Types of Mixture 317
11.3 Segregation 318
11.3.1 Causes and Consequences of Segregation 318
11.3.2 Mechanisms of Segregation 319
11.4 Reduction of Segregation 322
11.5 Equipment for Particulate Mixing 323
11.5.1 Mechanisms of Mixing 323
11.5.2 Types of Mixer 324
11.6 Assessing the Mixture 325
11.6.1 Quality of a Mixture 325
11.6.2 Sampling 326
11.6.3 Statistics Relevant to Mixing 326
11.7 Worked Examples 329
Test Yourself 333
Exercises 333
12 Particle Size Reduction 335
12.1 Introduction 335
12.2 Particle Fracture Mechanisms 336
12.3 Model Predicting Energy Requirement and Product Size Distribution 338
12.3.1 Energy Requirement 338
12.3.2 Prediction of the Product Size Distribution 342
12.4 Types of Comminution Equipment 344
12.4.1 Factors Affecting Choice of Machine 344
12.4.2 Stressing Mechanisms 344
12.4.3 Particle Size 350
12.4.4 Material Properties 351
12.4.5 Carrier Medium 352
12.4.6 Mode of Operation 352
12.4.7 Combination with other Operations 352
12.4.8 Types of Milling Circuit 352
12.5 Worked Examples 353
Test Yourself 356
Exercises 357
13 Size Enlargement 361
13.1 Introduction 361
13.2 Interparticle Forces 362
13.2.1 van der Waals Forces 362
13.2.2 Forces due to Adsorbed Liquid Layers 362
13.2.3 Forces due to Liquid Bridges 362
13.2.4 Electrostatic Forces 364
13.2.5 Solid Bridges 364
13.2.6 Comparison and Interaction between Forces 364
13.3 Granulation 365
13.3.1 Introduction 365
13.3.2 Granulation Rate Processes 366
13.3.3 Simulation of the Granulation Process 373
13.3.4 Granulation Equipment 376
13.4 Worked Examples 379
Test Yourself 381
Exercises 381
14 Health Effects of Fine Powders 383
14.1 Introduction 383
14.2 The Human Respiratory System 383
14.2.1 Operation 383
14.2.2 Dimensions and Flows 385
14.3 Interaction of Fine Powders with the Respiratory System 386
14.3.1 Sedimentation 386
14.3.2 Inertial Impaction 387
14.3.3 Diffusion 388
14.3.4 Interception 388
14.3.5 Electrostatic Precipitation 388
14.3.6 Relative Importance of These Mechanisms Within the Respiratory Tract 388
14.4 Pulmonary Delivery of Drugs 391
14.5 Harmful Effects of Fine Powders 393
Test Yourself 395
Exercises 395
15 Fire and Explosion Hazards of Fine Powders 397
15.1 Introduction 397
15.2 Combustion Fundamentals 398
15.2.1 Flames 398
15.2.2 Explosions and Detonations 398
15.2.3 Ignition, Ignition Energy, Ignition Temperature – a Simple Analysis 398
15.2.4 Flammability Limits 401
15.3 Combustion in Dust Clouds 402
15.3.1 Fundamentals Specific to Dust Cloud Explosions 402
15.3.2 Characteristics of Dust Explosions 403
15.3.3 Apparatus for Determination of Dust Explosion Characteristics 404
15.3.4 Application of the Test Results 406
15.4 Control of the Hazard 407
15.4.1 Introduction 407
15.4.2 Ignition Sources 408
15.4.3 Venting 408
15.4.4 Suppression 409
15.4.5 Inerting 410
15.4.6 Minimize Dust Cloud Formation 410
15.4.7 Containment 410
15.5 Worked Examples 410
Test Yourself 416
Exercises 417
16 Case Studies 419
16.1 Case Study 1 419
16.2 Case Study 2 423
16.3 Case Study 3 427
16.4 Case Study 4 428
16.5 Case Study 5 429
16.6 Case Study 6 430
16.7 Case Study 7 438
16.8 Case Study 8 444
Notation 449
References 457
Index 465
End User License Agreement 475

"It is well written and pedagogical.... Appreciable are the efforts to enrich each chapter with examples which help the reader to better understand the argument and to evaluate what he/she has learned. 'Introduction to Particle Technology' is a book surely recommendable." (Materials and Manufacturing Process, Volume 24, Issue 6)