Cover image for Gas cyclones and swirl tubes : principles, design, and operation
Title:
Gas cyclones and swirl tubes : principles, design, and operation
Personal Author:
Edition:
2nd ed.
Publication Information:
Berlin : Springer, 2008
Physical Description:
xxvi, 422 p. : ill. ; 24 cm.
ISBN:
9783540746942

9783642094163
General Note:
Also available online version
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Electronic Access:
Full Text
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Accessible within UTM campus

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Summary

Summary

Believed to be a publishing first when originally brought out, this book covers all aspects of centrifugal gas cleaning devices. These are cyclones used as gas-solid separators for dedusting and as gas-liquid separators for demisting. The optimization of cyclone performance for any given task is a sought-after goal - but it is one that is seldom achieved in practice. This second edition will help mechanical and chemical engineers to achieve this optimization.


Table of Contents

1 Introductionp. 1
1.1 Some Historical Backgroundp. 1
1.2 Removal of Particles from Gasesp. 6
1.2.1 Filtrationp. 8
1.2.2 Wet Scrubbersp. 10
1.2.3 Centrifugal/Cyclonic Devicesp. 11
1.2.4 Knock-out Vessels and Settling Chambersp. 12
1.3 A Closer Look at Centrifugal Gas Cleaning Devicesp. 12
1.3.1 Applications of Centrifugal Separatorsp. 13
1.3.2 Classification of Centrifugal Separatorsp. 17
1.3.3 Two Main Classes-Cyclones and Swirl Tubesp. 20
2 Basic Ideasp. 23
2.1 Gas Flowp. 23
2.1.1 Swirling Flowp. 23
2.1.2 Static and Dynamic Pressurep. 26
2.2 Particle Motionp. 27
2.3 Particle Sizep. 32
2.3.1 Definitions of Particle Sizep. 32
2.3.2 Particle Size Distributionp. 33
2.4 Particle Densityp. 37
2.A Ideal Vortex Laws from N-S Eqsp. 38
2.B Model Functions for Size Distributionsp. 41
2.B.1 The Normal Distributionp. 42
2.B.2 The Log-Normal Distributionp. 42
2.B.3 The Rosin-Rammler Distributionp. 43
3 How Cyclones Workp. 45
3.1 Flow in Cyclonesp. 45
3.1.1 Gas Flow Patternp. 45
3.1.2 Particle Flowp. 49
3.2 Separation Efficiencyp. 51
3.2.1 Overall Separation Efficiencyp. 51
3.2.2 Grade-Efficiencyp. 51
3.2.3 Converting Between Overall Efficiency and Cut-sizep. 54
3.3 Pressure Dropp. 54
3.A Worked Example: Calculating a Grade-Efficiency Curvep. 56
4 Cyclone Flow Pattern and Pressure Dropp. 59
4.1 Discussionp. 59
4.1.1 Flow Patternp. 60
4.1.2 Pressure Dropp. 61
4.2 Models for the Flow Patternp. 64
4.2.1 n-Type Modelp. 65
4.2.2 Barthp. 66
4.3 Models for the Pressure Dropp. 70
4.3.1 Models Based on Estimating the Dissipative Lossp. 71
4.3.2 Core Modelp. 72
4.3.3 Purely Empirical Modelsp. 77
4.4 Model Assumptions in Light of CFD and Experimentp. 78
4.5 Overviewp. 82
4.A Worked Example for Calculating Cyclone Pressure Dropp. 83
4.B The Meissner and Loffler Modelp. 85
5 Cyclone Separation Efficiencyp. 89
5.1 Discussionp. 89
5.2 Modelsp. 90
5.2.1 Equilibrium-orbit Models: the Model of Barthp. 90
5.2.2 Time-of-Flight Modelsp. 93
5.2.3 Hybrid Modelsp. 96
5.2.4 Comparing the Modelsp. 96
5.3 Comparison of Model Predictions with Experimentp. 97
5.3.1 Agreement with Experiment in Generalp. 97
5.3.2 A Case Study: the Effect of Cyclone Lengthp. 98
5.4 Overviewp. 102
5.A Worked Example, Separation Performancep. 103
5.B Models of Dietz and of Mothes and Lofflerp. 106
6 The Muschelknautz Method of Modelingp. 111
6.1 Basis of the Modelp. 112
6.2 Computation of the Inner Vortex Cut-Point, x[subscript 50]p. 118
6.3 Computation of Efficiency at Low Solids Loadingsp. 120
6.4 Determining if the Mass Loading Effect will Occurp. 122
6.5 Overall Separation Efficiency when c[subscript o] > c[subscript oL]p. 122
6.6 Computation of Pressure Dropp. 124
6.A Example Problemsp. 125
6.A.1 Data from Hoffmann, Peng and Postma (2001)p. 125
6.A.2 Data from Obermair and Staudinger (2001)p. 128
6.A.3 Simulation of the Data from Greif (1997)p. 129
6.B Incorporation of the 'Inner Feed'p. 133
7 Computational Fluid Dynamicsp. 139
7.1 Simulating the Gas Flow Patternp. 140
7.1.1 Setting up the Finite Difference Equationsp. 140
7.1.2 Turbulence Modelsp. 142
7.1.3 Simulationsp. 143
7.2 Simulating the Particle Flowp. 147
7.2.1 Eulerian Modelingp. 148
7.2.2 Lagrangian Particle Trackingp. 148
7.2.3 3-D particle tracksp. 148
7.3 Some Simulations of the Gas and Particle Flow in Cyclonesp. 149
7.3.1 LES Simulations of Derksen and van den Akkerp. 149
7.3.2 Some Remarks on CFD in Cyclonesp. 160
7.A Transport Equationsp. 161
8 Dimensional Analysis and Scaling Rulesp. 163
8.1 Classical Dimensional Analysisp. 164
8.1.1 Separation Efficiencyp. 164
8.1.2 Pressure Dropp. 167
8.2 Scaling Cyclones in Practicep. 168
8.2.1 Approximately Constant Stk[subscript 50] over a Wide Range of Rep. 168
8.2.2 Eu Only Weakly Dependent on Rep. 171
8.2.3 Some other Considerationsp. 172
8.2.4 Stk-Eu Relationshipsp. 173
8.A Inspecting the Equations of Motionp. 176
8.A.1 Equation of Motion for the Gasp. 176
8.A.2 Equation of Motion for a Particlep. 176
8.B Sample Cyclone Scaling Calculationsp. 177
8.B.1 Inlet Velocity for Re Similarityp. 177
8.B.2 Prediction from Scale Modelp. 178
9 Other Factors Influencing Performancep. 183
9.1 The Effect of Solids Loadingp. 183
9.1.1 Effect on Separation Efficiency of Cyclonesp. 183
9.1.2 Models for Effect on Separation Efficiencyp. 185
9.1.3 Effect on the Separation Efficiency of Swirl Tubesp. 191
9.1.4 Effect on the Pressure Drop of Cyclonesp. 192
9.1.5 Effect on the Pressure Drop Across Swirl Tubesp. 194
9.1.6 Computing Performance with High Loadingp. 194
9.2 The Effect of the Natural Vortex Lengthp. 195
9.2.1 The Nature of the Vortex Endp. 195
9.2.2 Wall Velocity Due to Core Precessionp. 197
9.2.3 The Significance of the Vortex Endp. 199
9.2.4 Models for the Natural Vortex Lengthp. 203
9.A Predicting the Effect of Solids Loading on Cyclone Efficiencyp. 205
9.B Predicting the Effect of Loading on Cyclone Pressure Dropp. 208
10 Measurement Techniquesp. 213
10.1 Gas Flow Patternp. 216
10.2 Pressure Dropp. 218
10.3 Particle Flowp. 219
10.4 Overall Separation Efficiencyp. 220
10.4.1 On-line Sampling of Solidsp. 221
10.5 Grade-Efficiencyp. 224
10.5.1 On-Line vs. Off-Line Size Analysisp. 224
10.5.2 Sample Capture and Preparationp. 225
10.5.3 Methods for Size Analysisp. 226
10.A Estimate of Errorsp. 231
11 Underflow Configurations and Considerationsp. 235
11.1 Underflow Configurationsp. 235
11.2 Importance of a Good Underflow Sealp. 239
11.2.1 Inleakage Examplep. 242
11.3 Upsets Caused by 'Too Good' an Underflow Sealp. 243
11.4 Second-Stage Dipleg Solids 'Backup'p. 246
11.5 Hopper 'Crossflow'p. 248
11.6 Hopper Venting Optionsp. 250
11.A Dipleg Calculationp. 253
11.B Moment Balance on Flapper Valve Platep. 253
11.B.1 Examplep. 256
12 Some Special Topicsp. 257
12.1 Cyclone Erosionp. 257
12.1.1 Inlet 'Target Zone'p. 257
12.1.2 Lower Cone Sectionp. 260
12.1.3 Vortex Tube Outer Surfacep. 263
12.1.4 Erosion Protectionp. 268
12.2 Critical Deposition Velocityp. 279
12.3 High Vacuum Casep. 281
12.3.1 Application to Cyclone or Swirl Tube Simulationp. 282
12.A Worked Example for Critical Deposition Velocityp. 283
12.B Worked Example with Slipp. 283
13 Demisting Cyclonesp. 287
13.1 Liquid Creep and 'Layer Loss'p. 288
13.2 Demisting Cyclone Design Considerationsp. 290
13.3 Some Vapor-Liquid Cyclone Design Geometries and Featuresp. 292
13.4 Estimating Inlet Drop Size for Two-Phase Mist-Annular Flowp. 299
13.4.1 Estimating Drop Size Distributionp. 301
13.5 Modeling the Performance of Vapor-Liquid Cyclonesp. 302
13.5.1 Computation of Cut Sizep. 302
13.5.2 Computation of Efficiency at Low Inlet Loadingsp. 303
13.6 Criteria for Determining if 'Mass loading' ('Saltation') Occursp. 303
13.6.1 Overall Separation Efficiency when c[subscript o] > c[subscript oL]p. 304
13.7 Re-entrainment From Demisting Cyclonesp. 305
13.7.1 Re-entrainment Mechanisms and Governing Parametersp. 305
13.7.2 Data for Re-entrainmentp. 308
13.A Example Calculations of Droplet Sizes in Pipe Flowp. 311
13.A.1 Finding the Mean Droplet Sizep. 311
13.A.2 Finding the Droplet Size Distributionp. 312
13.B Flow Distribution in Parallel Demisting Cyclonesp. 312
13.B.1 Calculation of Flow Distributionp. 317
13.B.2 Calculation of Liquid Level Differencep. 317
13.C Method for Estimating Wall Film Thickness and Velocityp. 318
13.C.1 Two-Phase, Co-current, Annular Force Balance, Resolved in the Axial Directionp. 320
13.C.2 Friction Factors and Shear Stressesp. 321
13.C.3 Final Form of Void Fraction Equationp. 323
13.D Example calculationp. 324
14 Foam-Breaking Cyclonesp. 327
14.1 Introductionp. 327
14.2 Some Design Considerations and Factors Influencing Behaviorp. 330
14.3 Applicationsp. 334
14.4 Estimating Submergence Required to Prevent Gas 'Blow Out'p. 334
14.A Example Calculation of Submergence Requiredp. 340
15 Design Aspectsp. 341
15.1 Cylinder-on-Cone Cyclones with Tangential Inletp. 341
15.1.1 Some Standard Cyclone Designsp. 341
15.1.2 Design of the Inletp. 342
15.1.3 Design of the Cone Sectionp. 349
15.1.4 Solids Outlet Configurationsp. 350
15.1.5 Vortex Finder Geometriesp. 353
15.1.6 Cyclone Lengthp. 363
15.1.7 Cyclone Roofp. 364
15.1.8 Cyclone Operating Conditionsp. 367
15.2 Design of Swirl Tubes with Swirl Vanesp. 368
15.2.1 Design of the Inlet Vanesp. 368
15.2.2 Calculation of Inlet 'Throat' Areap. 370
15.2.3 Length of the Swirl Tube Body and the Solids Exitp. 372
15.A Example Calculation of the Throat Areap. 373
15.B Construction of Vane "Cut-out" patternp. 374
16 Multicyclone Arrangementsp. 381
16.1 Cyclones in Seriesp. 381
16.2 Cyclones in Parallelp. 382
16.A Example Calculation for Multicyclone Arrangementsp. 391
List of Symbolsp. 397
List of Tradenamesp. 403
Referencesp. 405
Indexp. 411