Gas Cyclones and Swirl Tubes (eBook)

Preface 6
Foreword to the First Edition 10
Foreword to the Second Edition 13
Acknowledgments 15
About the Authors 17
Contents 18
1 Introduction 24
1.1 Some Historical Background 24
1.2 Removal of Particles from Gases 29
1.3 A Closer Look at Centrifugal Gas Cleaning Devices 35
2 Basic Ideas 45
2.1 Gas Flow 45
2.2 Particle Motion 49
2.3 Particle Size 54
2.4 Particle Density 59
2.A Ideal Vortex Laws from the Navier-Stokes Equations 60
2.B Common Model Functions for Particle Size Distributions 63
3 How Cyclones Work 66
3.1 Flow in Cyclones 66
3.2 Separation Efficiency 72
3.3 Pressure Drop 75
3.A Worked Example: Calculating a Grade-Efficiency Curve 77
4 Cyclone Flow Pattern and Pressure Drop 80
4.1 Discussion 80
4.2 Models for the Flow Pattern 85
4.3 Models for the Pressure Drop 91
4.4 Model Assumptions in Light of CFD and Experiment 99
4.5 Overview 103
4.A Worked Example for Calculating Cyclone Pressure Drop 104
4.B The Meissner and Löffler Model 106
5 Cyclone Separation Efficiency 109
5.1 Discussion 109
5.2 Models 110
5.3 Comparison of Model Predictions with Experiment. 117
5.4 Overview 122
5.A Worked Example for the Prediction of Cyclone Separation Performance 123
5.B The Cyclone Efficiency Models of Dietz and of Mothes and Löffler 126
6 The Muschelknautz Method of Modeling 130
6.1 Basis of the Model 131
6.2 Computation of the Inner Vortex Cut-Point, x50 137
6.3 Computation of Efficiency at Low Solids Loadings 139
6.4 Determining if the Mass Loading Effect will Occur 141
6.5 Overall Separation Efficiency when co > coL
6.6 Computation of Pressure Drop 143
6.A Example Problems 144
6.B Incorporation of the ‘Inner Feed’ 152
7 Computational Fluid Dynamics 157
7.1 Simulating the Gas Flow Pattern 158
7.2 Simulating the Particle Flow 165
7.3 Some Simulations of the Gas and Particle Flow in Cyclones 167
7.A Transport Equations 179
8 Dimensional Analysis and Scaling Rules 181
8.1 Classical Dimensional Analysis 182
8.2 Scaling Cyclones in Practice 186
8.A Inspecting the Equations of Motion 194
8.B Sample Cyclone Scaling Calculations 195
9 Other Factors Influencing Performance 201
9.1 The Effect of Solids Loading 201
9.2 The Effect of the Natural Vortex Length 213
9.A Predicting the Effect of Solids Loading on Cyclone Efficiency 223
9.B Predicting the Effect of Loading on Cyclone Pressure Drop 226
10 Measurement Techniques 230
10.1 Gas Flow Pattern 233
10.2 Pressure Drop 235
10.3 Particle Flow 236
10.4 Overall Separation Efficiency 237
10.5 Grade-Efficiency 241
10.A Estimate of Errors 248
11 Underflow Configurations and Considerations 251
11.1 Underflow Configurations 251
11.2 Importance of a Good Underflow Seal 255
11.3 Upsets Caused by ‘Too Good’ an Underflow Seal 259
11.4 Second-Stage Dipleg Solids ‘Backup’ 262
11.5 Hopper ‘Crossflow’ 264
11.6 Hopper Venting Options 266
11.A Dipleg Calculation 269
11.B Moment Balance on Flapper Valve Plate 269
12 Some Special Topics 273
12.1 Cyclone Erosion 273
12.2 Critical Deposition Velocity 295
12.3 High Vacuum Case 297
12.A Worked Example for Calculation of the Critical Deposition Velocity 299
12.B Worked Example Taking Into Account Slip in Calculation of the Cut Size 299
13 Demisting Cyclones 303
13.1 Liquid Creep and ‘Layer Loss’ 304
13.2 Demisting Cyclone Design Considerations 306
13.3 Some Vapor-Liquid Cyclone Design Geometries and Features 308
13.4 Estimating Inlet Drop Size for Two-Phase Mist- Annular Flow 315
13.5 Modeling the Performance of Vapor-Liquid Cyclones 318
13.6 Criteria for Determining if ‘Mass loading’ (‘ Saltation’) Occurs 319
13.7 Re-entrainment From Demisting Cyclones 321
13.A Example Calculations of Droplet Sizes in Pipe Flow 327
13.B Flow Distribution in Parallel Demisting Cyclones 328
13.C Method for Estimating Wall Film Thickness and Velocity 334
13.D Example calculation 340
14 Foam-Breaking Cyclones 343
14.1 Introduction 343
14.2 Some Design Considerations and Factors Influencing Behavior 346
14.3 Applications 350
14.4 Estimating Submergence Required to Prevent Gas ‘ Blow Out’ 350
14.A Example Computation of Submergence Required to Prevent Underflow Gas ‘ Blow Out’ 356
15 Design Aspects 357
15.1 Cylinder-on-Cone Cyclones with Tangential Inlet 357
15.2 Design of Swirl Tubes with Swirl Vanes 384
15.A Example Calculation of the Throat Area 389
15.B Construction of a Vane Cut-out Pattern of an Orthogonal Vane Assembly 390
16 Multicyclone Arrangements 397
16.1 Cyclones in Series 397
16.2 Cyclones in Parallel 398
16.A Example Calculation for Multicyclone Arrangements 407
17 List of Symbols 412
List of Tradenames 418
References 419
Index 424