Powders and Bulk Solids (eBook)

Preface 5
Foreword 9
Contents 11
1. Introduction 17
1.1 Common problems with bulk solids 17
1.2 Milestones of bulk solids technology 20
2 Fundamentals 24
2.1 Particles or continuum? 24
2.2 Forces and stresses 25
2.3 Stresses in bulk solids solids solids 27
2.4 Bulk density 35
2.5 Elastic and plastic deformation 36
2.6 Adhesive forces 38
2.7 Influence of particle size on the behavior of a bulk solid 47
3 Flow properties of bulk solids 50
3.1 Uniaxial compression test 50
3.2 Principles of shear testing 62
3.3 Wall friction 84
4 Practical determination of flow properties 90
4.1 Measurement with shear testers 90
4.2 Selection of stresses 114
4.3 Application-related measurement of flow properties 125
5 A more detailed look at properties of bulk solids 127
5.1 Anisotropy and influence of deformation on stresses 127
5.2 Shear deformation, shear zones, localization 143
5.3 Yield locus 161
5.4 Influence of velocity 174
6 Discussion of testers and test procedures 176
6.1 Influences on test results 176
6.2 Requirements for testers to measure flow properties 181
6.3 Measuring techniques and equipment (overview) 182
6.4 Remarks on reliability and accuracy 206
6.5 Measurement of adhesive forces 209
6.6 Summary 211
7 Properties exhibited by some bulk solids 212
7.1 Effects in flowing bulk solids 212
7.2 Parameters and conditions influencing flow behavior 223
8 Examples of measured flow properties 244
8.1 Flow agent 244
8.2 Moisture content 246
8.3 Temperature 248
8.4 Time consolidation 249
8.5 Particle size 250
8.6 Attrition 253
8.7 Bulk density 254
8.8 Stress dependency of wall friction 256
8.9 Influence of wall material on wall friction angle 258
9 Stresses 261
9.1 Stress states in silos 261
9.2 Assessment of stresses 270
9.3 Loads on feeders 284
9.4 Disturbances to the stress distribution 290
10 Silo design for flow 302
10.1 Flow profiles: mass flow and funnel flow 302
10.2 Flow problems in silos 304
10.3 Jenike’s procedure for silo design 306
10.4 Application of results 323
10.5 Design diagrams 324
11 Silo configurations 329
11.1 Influence of flow properties on silo configuration 329
11.2 Hopper configurations 330
11.3 Inserts 338
12 Discharge of bulk solids 348
12.1 Maximum discharge rate 348
12.2 Discharge aids 356
12.3 Feeders and other discharge devices 362
12.4 Feeder dimensions and placement of discharge aids 386
13 Segregation 390
13.1 Segregation mechanisms 390
13.2 Techniques to reduce segregation 399
13.3 Sampling 412
13.4 Final remarks 413
14 Silo quaking and silo honking 414
14.1 Phenomenon 414
14.2 Shocks as a result of sudden flow 415
14.3 Sudden flow and pulsating flow caused by slip-stick friction 417
14.4 Shear zones in silos 418
14.5 Silo shocks due to slip-stick friction 422
14.6 Shocks and vibrations due to other reasons 438
14.7 Means for reducing silo quaking and silo honking 440
15 Sample problems and solutions 447
15.1 General remarks 447
15.2 Sample problems 447
Symbols 474
References 479
Index 509