Pneumatic Conveying Design Guide (eBook)

Cover 1
Contents 6
Preface 12
Part A: Systems and Components 14
1. Introduction to pneumatic conveying and the guide 16
1.1 Introduction 16
1.2 Pneumatic conveying 16
1.2.1 System flexibility 17
1.2.2 Industries and materials 17
1.2.3 Mode of conveying 18
1.2.3.1 Dilute phase 18
1.2.3.2 Dense phase 18
1.2.3.3 Conveying air velocity 19
1.2.3.4 Particle velocity 19
1.2.3.5 Solids loading ratio 20
1.2.4 Recent developments 21
1.2.4.1 System types 21
1.2.5 Conveying capability 22
1.2.5.1 High pressure conveying 22
1.2.5.2 Long distance conveying 23
1.2.5.3 Vertical conveying 23
1.2.5.3.1 Conveying vertically up 23
1.2.5.3.2 Conveying vertically down 24
1.2.5.4 Flow rate capability 24
1.2.5.4.1 Pressure gradient influence 25
1.2.5.4.2 Material influences 26
1.3 Information provided 26
1.3.1 Availability of design data 26
1.3.2 Scope of the work 27
1.4 Review of chapters 27
1.4.1 Systems and components 27
1.4.1.2 Review of pneumatic conveying systems 28
1.4.1.3 & 4 Pipeline feeding devices
1.4.1.5 Pipelines and valves 28
1.4.1.6 Air movers 28
1.4.1.7 Gas–solids separation devices 29
1.4.1.8 System selection considerations 29
1.4.2 System design 29
1.4.2.1 Air flow rate evaluation 29
1.4.2.2 Air only relationships 30
1.4.2.3 Conveying characteristics 30
1.4.2.4 Conveying capability 30
1.4.2.5 Material property influences 30
1.4.2.6 Pipeline scaling parameters 30
1.4.2.7 Design procedures 31
1.4.2.8 Case studies 31
1.4.2.9 First approximation design methods 31
1.4.2.10 Multiple use systems 31
1.4.3 System operation 31
1.4.3.20 Troubleshooting and material flow problems 32
1.4.3.21 Optimizing and up-rating of existing systems 32
1.4.3.22 Operating problems 32
1.4.3.23 Erosive wear 32
1.4.3.24 Particle degradation 32
1.4.3.25 Moisture and condensation 33
1.4.3.26 Health and safety 33
1.5 Definitions 33
1.5.1 Solids loading ratio 33
1.5.2 Dilute phase conveying 33
1.5.3 Dense phase conveying 34
1.5.4 Low pressure and negative pressure (vacuum) conveying 34
1.5.5 High pressure conveying 34
1.5.6 Free air conditions 34
1.5.7 Superficial air velocity 34
1.5.8 Free air velocity 35
1.5.9 Minimum conveying air velocity 35
1.5.10 Conveying line inlet air velocity 35
1.5.11 Conveying line exit air velocity 35
1.5.12 Saltation 35
1.5.13 Choking 36
1.5.14 Acceleration length 36
1.5.15 Null point 36
1.5.16 Specific humidity 36
1.5.17 Relative humidity 36
1.5.18 Stoichiometric value 36
1.5.19 Pulsating flow 36
1.5.20 Stepped pipeline 37
1.5.21 Air retention 37
1.5.22 Permeability 37
1.5.23 Hardness 37
1.5.24 Mohs' scale 37
1.5.25 Brinell hardness 37
1.5.26 Vickers hardness 38
1.5.27 Transient 38
1.6 Nomenclature 38
1.6.1 Symbols 38
1.6.1.1 Greek 39
1.6.2 Non-dimensional parameters 39
1.6.3 Superscripts 39
1.6.4 Subscripts 39
1.6.5 Prefixes 41
References 41
2. Review of pneumatic conveying systems 42
2.1 Introduction 42
2.2 System types 42
2.2.1 Open systems 43
2.2.1.1 Positive pressure systems 43
2.2.1.2 Negative pressure (vacuum) systems 44
2.2.2 Staged systems 45
2.2.2.1 Shared negative and positive pressure systems 46
2.2.2.2 Dual vacuum and positive pressure systems 46
2.2.3 Batch conveying systems 47
2.2.3.1 Semi-continuous systems 48
2.2.3.2 Single plug systems 48
2.2.4 Mobile systems 49
2.2.4.1 Road vehicles 50
2.2.4.2 Rail vehicles 51
2.2.4.3 Ships 51
2.2.5 Closed systems 51
2.2.6 Innovatory systems 52
2.2.6.1 Plug forming systems 53
2.2.6.1.1 Pressure drop considerations 54
2.2.6.2 By-pass systems 55
2.2.6.2.1 Pressure drop considerations 56
2.2.6.3 Air injection systems 57
2.2.6.3.1 The Gattys system 57
2.2.6.3.2 Booster systems 58
2.2.6.4 System selection considerations 58
2.2.7 Fluidized motion conveying systems 58
2.2.7.1 Air-assisted gravity conveyors 59
2.2.7.1.1 The Geldart classification of fluidization behaviour 59
2.2.7.2 Full channel conveyors 61
2.3 System requirements 61
2.3.1 Multiple pick-up 61
2.3.2 Multiple delivery 62
2.3.3 Multiple pick-up and delivery 62
2.3.4 Multiple material handling 62
2.3.5 Multiple distance conveying 62
2.3.6 Conveying from stockpiles 62
2.3.7 Start-up with full pipeline 63
2.4 Material property influences 63
2.4.1 Cohesive 63
2.4.2 Combustible 63
2.4.3 Damp or wet 64
2.4.4 Electrostatic 64
2.4.5 Erosive 64
2.4.6 Friable 64
2.4.7 Granular 64
2.4.8 Hygroscopic 65
2.4.9 Low melting point 65
2.4.10 Radioactive 65
2.4.11 Toxic 65
2.4.12 Very fine 65
References 66
3. Pipeline feeding devices – Part I: Low pressure and vacuum 67
3.1 Introduction 67
3.1.1 Air leakage 67
3.1.2 Pressure drop 68
3.1.3 Maintenance 68
3.1.4 Material properties 68
3.1.5 Devices available 69
3.1.5.1 Lock hoppers 69
3.1.5.2 Blow tanks 69
3.1.6 Feeding requirements 70
3.1.6.1 Flow metering 70
3.2 Rotary valves 71
3.2.1 Drop-through valve 71
3.2.1.1 Valve wear 71
3.2.2 Alternative designs 72
3.2.2.1 Off-set valve 72
3.2.2.2 Blow-through valve 72
3.2.3 Discharge period and pulsations 73
3.2.4 Air leakage 73
3.2.4.1 Positive pressure systems 73
3.2.4.2 Negative pressure systems 74
3.2.4.3 Influence of conveyed material 75
3.2.5 Air venting 77
3.2.6 Entrainment devices 77
3.2.7 Rotor types 78
3.2.7.1 Pocket types 79
3.2.8 Material feed rate 80
3.2.8.1 Pocket filling efficiency 80
3.2.8.2 Feed rate control 80
3.3 Screw feeders 81
3.3.1 The simple screw feeder 81
3.4 Venturi feeders 82
3.4.1 Commercial venturi feeder 83
3.4.2 Flow control 84
3.5 Gate lock valves 84
3.6 Suction nozzles 86
3.6.1 Feed rate control 86
3.6.2 Flow aids 88
3.6.3 Hopper off-loading 89
3.7 Trickle valves 89
3.8 Blow tanks 90
3.8.1 Pressure drop 91
3.8.2 Feed rate control 91
References 92
4. Pipeline feeding devices – Part II: High pressure 93
4.1 Introduction 93
4.1.1 Lock hoppers 93
4.2 Screw feeders 94
4.3 Rotary valves 95
4.4 Blow tanks 95
4.4.1 Basic blow tank types 96
4.4.1.1 Top and bottom discharge 96
4.4.1.2 Fluidizing membranes 100
4.4.1.3 Blow tank pressure drop 100
4.4.1.4 Problems with moisture 101
4.4.1.5 Road and rail vehicles 102
4.4.2 Single blow tank systems 102
4.4.2.1 Blow tanks without a discharge valve 102
4.4.2.2 Conveying cycle analysis 103
4.4.2.2.1 Blowing cycle 104
4.4.2.2.2 Influence of batch size 104
4.4.2.2.3 Blow tank filling 105
4.4.2.2.4 Conveying distance 105
4.4.2.2.5 Pipeline bore 106
4.4.2.3 Blow tanks with a discharge valve 106
4.4.2.3.1 Blow tank pressurizing 106
4.4.2.3.2 Blow tank venting 107
4.4.3 Single blow tank control 107
4.4.3.1 Air proportioning 107
4.4.3.1.1 Blow tank air 107
4.4.3.1.2 Supplementary air 107
4.4.3.2 Discharge rate control 108
4.4.3.3 The influence of blow tank type 108
4.4.3.3.1 Conveying line performance 109
4.4.3.3.2 Blow tank discharge performance 109
4.4.3.3.3 Material discharge performance 110
4.4.3.4 Blow tank control systems 111
4.4.4 Twin blow tank systems 112
4.4.4.1 Twin blow tanks in parallel 112
4.5 Lock hoppers 114
4.5.1 Alternative feeding arrangements 115
4.5.1.1 Rotary valves and screws 115
4.5.1.2 Venturi feeders 115
4.5.1.3 Applications 115
4.5.2 Alternative vessel configuration 116
References 116
5. Pipelines and valves 117
5.1 Introduction 117
5.2 Pipelines 117
5.2.1 Wall thickness 117
5.2.1.1 Pipeline rotation 118
5.2.2 Pipeline material 118
5.2.2.1 Hygiene 118
5.2.2.2 Hoses 118
5.2.2.3 Erosive wear 119
5.2.2.4 Material degradation 119
5.2.3 Surface finish 119
5.2.4 Bends 119
5.2.4.1 Blind tee 120
5.2.4.2 Special bends 121
5.2.4.3 Pressure drop 121
5.2.5 Steps 122
5.3 Valves 123
5.3.1 Discharge valves 124
5.3.1.1 Ball valves 124
5.3.1.2 Pinch valves 124
5.3.1.3 Dome valves 124
5.3.2 Isolating valves 124
5.3.2.1 Butterfly valves 125
5.3.2.2 Disc valves 125
5.3.2.3 Slide valves 125
5.3.3 Vent line valves 125
5.3.4 Flow diversion 125
5.3.4.1 Diverter valves 126
5.3.4.2 Isolating valves 126
5.3.5 Flow splitting 127
5.4 Rubber hose 127
5.4.1 Erosive wear and particle degradation 127
5.4.2 Pressure drop 127
5.4.3 Conveying cohesive materials 128
References 129
6. Air movers 130
6.1 Introduction 130
6.2 Types of air mover 130
6.2.1 Aerodynamic compressors 131
6.2.1.1 Fans 132
6.2.1.2 Constant speed characteristics 132
6.2.1.2.1 Regenerative blowers 133
6.2.2 Positive displacement compressors 133
6.2.2.1 Roots (positive displacement) type blowers 134
6.2.2.1.1 Compressors 135
6.2.2.1.2 Exhausters 136
6.2.2.1.3 Pressure capability 136
6.2.2.1.4 Staging 136
6.2.2.2 Sliding vane rotary compressors 137
6.2.2.3 Liquid ring compressors 138
6.2.2.4 Rotary screw compressors 139
6.2.2.5 Reciprocating compressors 139
6.2.3 Staging 140
6.2.4 Specification of air movers 140
6.2.4.1 Blowers and compressors 141
6.2.4.1.1 Pressure 141
6.2.4.1.2 Volumetric flow rate 141
6.2.4.2 Exhausters and vacuum pumps 141
6.2.4.2.1 Vacuum 142
6.2.4.2.2 Volumetric flow rate 142
6.2.4.3 Air leakage and ingress 142
6.3 Air compression effects 143
6.3.1 Delivery temperature 143
6.3.2 Oil free air 144
6.3.3 Water removal 145
6.3.3.1 Air line filters 145
6.3.4 Air drying 145
6.3.4.1 Refrigerants 145
6.3.4.2 Desiccants 146
6.3.5 The use of plant air 147
6.3.6 Power requirements 147
6.3.6.1 Idling characteristics 149
6.4 Pre-cooling systems 150
6.5 Nomenclature 150
6.5.1 Greek 151
6.5.2 Subscripts 151
6.5.3 Superscripts 151
References 151
7. Gas–solid separation devices 152
7.1 Introduction 152
7.1.1 Separation requirements 152
7.1.2 Separation mechanisms 152
7.1.3 Pressure drop considerations 153
7.2 Dust control 153
7.2.1 Particle degradation 153
7.2.2 Dust emission 154
7.3 Separation devices 154
7.3.1 Gravity settling chambers 155
7.3.1.1 Collecting efficiency 155
7.3.2 Cyclone separators 156
7.3.2.1 Reverse flow type 156
7.3.2.2 Collecting efficiency 157
7.3.2.3 Typical dimensions 157
7.3.3 Filters 159
7.3.3.1 Filtration mechanisms 159
7.3.3.2 Collecting efficiency 159
7.3.3.3 Filter media 159
7.3.3.4 Selection criteria 160
7.3.3.5 Bag filters 160
7.3.3.6 Filter size 161
7.3.3.7 Filter cleaning 162
7.3.3.8 Reverse air jet cleaning 162
7.3.3.9 Maintenance 163
7.4 System considerations 163
7.4.1 Blow tank systems 163
7.4.2 Vacuum conveying systems 164
References 164
8. System selection considerations 165
8.1 Introduction 165
8.1.1 System economics 165
8.1.2 Material considerations 166
8.2 Variables involved 166
8.2.1 The conveyed material 166
8.2.2 Conveying conditions 166
8.2.2.1 Conveying line pressure drop 167
8.2.2.2 System influences 167
8.2.2.3 Material influences 167
8.2.3 Pipeline geometry 167
8.2.3.1 Pipeline length 167
8.2.3.2 Pipeline bore 168
8.2.3.3 Pipeline bends 168
8.3 Variables investigated 168
8.3.1 The influence of material type 168
8.3.1.1 Minimum conveying air velocity 169
8.3.1.2 Conveying air requirements 170
8.3.1.3 Conveying capabilities 170
8.3.2 The influence of conveying line pressure drop 171
8.3.3 The influence of conveying distance 172
8.3.3.1 Solids loading ratio 172
8.3.3.2 Material flow rate 173
8.3.3.3 Conveying line pressure drop 175
8.3.4 The influence of pipeline bore 176
8.4 Material compatibility 177
8.5 Design curves 177
8.5.1 Conveying parameter combinations 178
8.5.2 Pipeline conveying capacity 182
8.6 Power requirements 185
8.6.1 Influence of conveying distance 186
8.6.1.1 System considerations 187
8.6.2 Influence of pipeline bore 188
8.6.2.1 Materials with good air retention properties 188
8.6.2.2 Materials with poor air retention properties 189
8.6.2.3 Material compatibility 190
8.7 System selection considerations 190
8.7.1 Summary charts 190
8.7.2 Materials capable of dense phase conveying 191
8.7.3 Alternatives to dilute phase conveying 192
Part B: System Design 194
9. Air flow rate evaluation 196
9.1 Introduction 196
9.1.1 Supply pressure 196
9.1.2 Volumetric flow rate 197
9.1.3 The influence of velocity 197
9.1.3.1 Material influences 198
9.1.4 Compressibility of air 199
9.2 Volumetric flow rate 199
9.2.1 Presentation of equations 200
9.2.2 The influence of pipe bore 200
9.2.2.1 Reference conditions 201
9.2.2.2 Pipeline influences 201
9.2.3 The Ideal Gas Law 201
9.2.3.1 Working relationships 202
9.2.3.2 Gas constants 202
9.2.3.2.1 The use of nitrogen 203
9.3 The influence of pressure 203
9.3.1 System influences 203
9.3.2 Velocity determination 205
9.3.2.1 Working relationships 205
9.3.2.2 Graphical representation 206
9.3.2.2.1 Suck-blow systems 208
9.3.2.2.2 Low pressure systems 208
9.4 Stepped pipeline systems 209
9.4.1 Step location 210
9.4.2 Dilute phase conveying 211
9.4.3 Dense phase conveying 212
9.4.4 Vacuum conveying 213
9.4.4.1 Step position 213
9.4.5 Pipeline staging 214
9.5 Pipeline purging 215
9.6 The influence of temperature 216
9.6.1 Conveyed material influences 218
9.6.1.1 Specific heat 220
9.7 The influence of altitude 221
9.7.1 Atmospheric pressure 221
9.8 The use of air mass flow rate 222
9.9 Nomenclature 223
9.9.1 Greek 223
9.9.2 Subscripts 223
10. Air only relationships 224
10.1 Introduction 224
10.2 Pipeline pressure drop 224
10.2.1 Flow parameters and properties 225
10.2.1.1 Conveying air velocity 225
10.2.1.2 Air density 225
10.2.1.3 Air viscosity 226
10.2.1.4 Friction factor 226
10.2.2 Pressure drop relationships 228
10.2.2.1 Straight pipeline 228
10.2.2.1.1 The influence of air flow rate 229
10.2.2.1.2 The influence of pipeline length 229
10.2.2.1.3 The influence of pipeline bore 230
10.2.2.2 Bends 230
10.2.2.2.1 Equivalent length 233
10.2.2.3 Other pipeline features 233
10.2.2.4 Total pipeline 234
10.2.2.4.1 Positive pressure systems 235
10.2.2.4.2 Negative pressure systems 236
10.2.3 Air only pressure drop datum 237
10.3 Venturi analysis 237
10.3.1 Atmospheric pressure applications 240
10.3.2 High pressure applications 240
10.4 Air flow rate control 240
10.4.1 Nozzles 240
10.4.1.1 Flow analysis 241
10.4.1.2 Critical pressure 242
10.4.1.3 Nozzle size and capability 243
10.4.1.4 Nozzle types 244
10.4.2 Orifice plates 244
10.4.3 Flow rate control 245
10.5 Stepped pipelines 245
10.5.1 Air only pressure drop 246
10.5.2 Position of steps 247
10.5.3 Transition sections 247
10.6 Nomenclature 247
10.6.1 Greek 248
10.6.2 Subscripts 248
10.6.3 Prefixes 248
References 248
11. Conveying characteristics 249
11.1 Introduction 249
11.1.1 Conveying characteristics 249
11.1.2 Conveying mode 250
11.2 Single phase flow 250
11.2.1 The Darcy equation for pressure drop 250
11.2.2 The use of air mass flow rate 252
11.3 Gas–solid flows 252
11.3.1 The influence of conveyed solids on pressure drop 252
11.3.2 Evaluation of velocity 253
11.3.3 Conveying limitations 254
11.3.4 Conveying air velocity effects 255
11.3.5 Solids loading ratio 256
11.4 The determination of conveying characteristics 256
11.4.1 Instrumentation and control 256
11.4.2 Experimental plan 257
11.4.3 Presentation of results 258
11.4.4 Determination of minimum conveying conditions 259
11.4.5 The use of conveying characteristics 260
11.5 Energy considerations 260
11.5.1 The influence of conveying air velocity 261
11.5.2 Power requirements 262
11.5.3 Specific energy 264
11.6 Component pressure drop relationships 265
11.6.1 Conveying vertically down 266
11.6.2 Conveying vertically up 267
11.6.3 Horizontal pipelines 268
11.6.4 Pipeline bends 269
11.7 Nomenclature 270
11.7.1 Greek 270
11.7.2 Subscripts 270
11.7.3 Prefixes 270
References 270
12. Conveying capability 271
12.1 Introduction 271
12.2 The influence of materials 271
12.2.1 Low pressure conveying – Part I 271
12.2.1.1 Coal 274
12.2.1.2 Sodium chloride (salt) 274
12.2.1.3 Sodium carbonate (heavy soda ash) 275
12.2.1.4 Pearlite 275
12.2.1.5 Pulverized fuel ash (fly ash) 275
12.2.1.6 Iron powder 275
12.2.2 Low pressure conveying – Part II 276
12.2.2.1 Alumina 276
12.2.2.2 PVC powder 277
12.2.2.3 Barytes 277
12.2.2.4 Coal 278
12.2.2.5 Fluidized bed combustor ash 279
12.2.2.6 Pulverized fuel ash 279
12.2.3 High pressure conveying – Part I 280
12.2.3.1 Wheat flour 280
12.2.3.2 Granulated sugar 282
12.2.3.3 Polyethylene pellets 282
12.2.3.4 Ordinary Portland cement 283
12.2.3.5 Iron powder 283
12.2.3.6 Barytes 283
12.2.3.7 Pearlite 283
12.2.3.8 Magnesium sulphate 285
12.2.3.9 Alumina 285
12.2.3.10 Zircon sand 286
12.2.3.11 Comparison of materials – flow rate 286
12.2.3.12 Copper concentrate 287
12.2.3.13 Coke fines 287
12.2.3.14 Comparison of materials – conveying limits 288
12.2.3.15 Fly ash 288
12.2.4 High pressure conveying – Part II 289
12.2.4.1 PVC resin 289
12.2.4.2 Terephthalic acid 291
12.2.5 High pressure conveying – Part III 291
12.2.5.1 Bentonite 291
12.2.5.2 Fluorspar 291
12.2.5.3 Coal 291
12.2.5.4 Silica sand 293
12.2.6 High pressure conveying – Part IV 293
12.2.6.1 Cement 293
12.2.6.2 Potassium sulphate 295
12.2.6.3 Sodium sulphate 295
12.2.6.4 Magnesium sulphate 295
12.3 System capability 296
12.3.1 Solids loading ratio – & #934
12.3.2 The influence of pipe bore 296
12.3.3 The influence of pressure drop 298
References 299
13. Material property influences 300
13.1 Introduction 300
13.2 Conveying modes 300
13.2.1 Dilute phase non-suspension flow 300
13.2.2 Dense phase sliding bed flow 302
13.2.2.1 Transitional conveying limit 303
13.2.3 Dense phase plug flow 305
13.2.3.1 Tests with nylon pellets 306
13.3 Conveying capability correlations 307
13.3.1 Basic property classifications 308
13.3.1.1 Modes of flow 309
13.3.1.2 Geldart's classification 309
13.3.1.3 Dixon's slugging diagram 310
13.3.2 Aeration property classifications 311
13.3.2.1 Conveying characteristics 311
13.3.2.2 Material testing 312
13.3.2.3 Conveying mode correlations 312
13.3.2.3.1 Permeability factor 312
13.3.2.3.2 Specific surface 314
13.3.2.3.3 Vibrated de-aeration constant 314
13.3.2.3.4 Empirical classification 315
13.3.2.4 Material flow rate correlations 316
13.3.2.4.1 Permeability factor 316
13.3.2.4.2 Vibrated de-aeration constant 317
13.4 Material grade influences 318
13.4.1 Alumina 318
13.4.1.1 By-pass system performance 319
13.4.2 Fly ash 321
13.4.2.1 Fly ash grades 321
13.4.3 Dicalcium phosphate 322
13.5 Material degradation effects 324
13.5.1 Granulated sugar 324
13.5.1.1 Degraded material 325
13.5.2 Coal 325
13.5.3 Sodium sulphate 326
13.5.4 Soda ash 327
13.5.4.1 Particle size changes 328
13.5.4.2 Pressure drop changes 329
13.5.4.3 Conveying tests 330
References 331
14. Pipeline scaling parameters 332
14.1 Introduction 332
14.2 Scaling requirements 332
14.2.1 Conveying air velocity 332
14.2.2 Solids loading ratio 333
14.3 Conveying distance 333
14.3.1 Minimum conveying air velocity 334
14.3.2 Scaling 334
14.3.2.1 Empty line pressure drop 334
14.3.2.2 Scaling model 335
14.3.2.3 Scaling procedure 336
14.3.2.3.1 Cement conveying limits 337
14.3.2.3.2 Potassium sulphate conveying limit 337
14.3.2.4 Scaling to longer distances 338
14.3.2.4.1 Dense phase conveying limit 338
14.3.2.5 Iterative process 339
14.3.2.5.1 Note 339
14.4 Pipeline bore 340
14.4.1 Empty line pressure drop 340
14.4.2 Scaling model 340
14.4.2.1 Working model 341
14.4.3 Scaling procedure 341
14.4.3.1 Scaling to larger bores 342
14.4.3.2 Influence on conveying parameters 344
14.4.3.2.1 Air supply pressure 345
14.4.3.2.2 Power requirements 345
14.5 Pipeline bends 346
14.5.1 Equivalent length 346
14.5.1.1 Method of analysis 347
14.5.1.1.1 Bend location 350
14.5.1.2 Pressure drop data 350
14.5.1.2.1 Classical analysis 351
14.5.2 Bend geometry 352
14.5.2.1 Air only relationships 352
14.5.2.2 Conveying data 352
14.5.2.3 Comparison of performance 353
14.6 Vertical pipelines 355
14.6.1 Conveying vertically up 355
14.6.1.1 Scaling parameter 356
14.6.2 Conveying vertically down 357
14.6.3 Inclined pipelines 357
14.6.3.1 Minimum conveying air velocity 358
14.6.3.2 Pipeline pressure gradient 359
14.7 Pipeline material 359
14.7.1 Rubber hose 360
14.7.2 Comparison with steel 361
14.8 Stepped pipelines 362
14.8.1 Conveying performance data 363
14.8.2 Velocity profiles 366
References 366
15. Design procedures 368
15.1 Introduction 368
15.2 The use of equations in system design 368
15.2.1 Logic diagram for system design 368
15.2.1.1 Specify material 370
15.2.1.2 Specify mass flow rate of material required 370
15.2.1.3 Specify conveying distance required 371
15.2.1.4 Select pipeline bore 371
15.2.1.5 Select conveying line pressure drop 371
15.2.1.6 Select conveying line inlet air velocity 372
15.2.1.7 Calculate air mass flow rate 373
15.2.1.8 Calculate solids loading ratio 374
15.2.1.9 Check conveying line inlet air velocity 374
15.2.1.10 Check conveying line pressure drop 374
15.2.1.11 Re-specify material mass flow rate 375
15.2.1.12 Re-select pipeline bore 375
15.2.1.13 Calculate power required 375
15.2.1.14 System re-assessment 376
15.2.1.15 Specify pipeline bore required 376
15.2.1.16 Specify air requirements 376
15.2.2 Logic diagram for system capability 377
15.2.2.1 Specify material to be conveyed 377
15.2.2.2 Specify conveying distance 377
15.2.2.3 Specify pipeline bore 377
15.2.2.4 Specify maximum value of conveying line pressure drop 377
15.2.2.5 Select conveying line inlet air velocity 377
15.2.2.6 Calculate air mass flow rate 379
15.2.2.7 Calculate volumetric air flow rate 379
15.2.2.8 Is the air mover capable? 379
15.2.2.9 Determine material flow rate 379
15.2.2.10 Is the material feeding device capable? 380
15.2.2.11 Calculate solids loading ratio 380
15.2.2.12 Check conveying line inlet air velocity 380
15.2.2.13 Specify material flow rate 380
15.2.2.14 Specify air requirements 380
15.3 The use of test data in system design 380
15.3.1 Logic diagram for system design 381
15.3.1.1 Specify mass flow rate of material required 381
15.3.1.2 Specify conveying distance required 382
15.3.1.3 Conveying characteristics for material 382
15.3.1.4 Scale to conveying distance 382
15.3.1.5 Can material flow rate be achieved? 383
15.3.1.6 Calculate power required 383
15.3.1.7 Scale to different pipeline bore 383
15.3.1.8 Specify pipeline bore required 383
15.3.1.9 Specify air requirements 383
15.3.2 Logic diagram for system capability 383
15.3.2.1 Specify bounding conditions 384
15.3.2.2 Material conveying characteristics 384
15.3.2.3 Scale conveying characteristics 384
15.3.2.4 Specify air requirements 384
15.3.2.5 Specify material flow rate 385
15.4 Typical pipeline and material influences 385
15.4.1 The influence of conveying distance 385
15.4.2 The influence of pipeline bore 389
15.4.3 Design curves 392
16. Case studies – Part I: Fine material 397
16.1 Introduction 397
16.1.1 Dense phase conveying of cement 397
16.2 Conveying data 398
16.2.1 Conveying duty 398
16.2.2 Conveying capability 398
16.2.3 Summary 400
16.3 Procedure 401
16.3.1 Operating point 401
16.3.1.1 Conveying line inlet air velocity 401
16.3.1.2 Air only pressure drop for operating point 402
16.3.2 Equivalent lengths 403
16.3.2.1 Test pipeline 404
16.3.2.2 Plant pipeline 404
16.3.3 Scaling for length 404
16.3.3.1 Conveying conditions – check 405
16.3.3.2 Conveying conditions – re-calculate 405
16.3.4 Scaling for bore 406
16.3.5 Air requirements 407
16.3.5.1 Air flow rate 407
16.3.5.2 Power required 407
17. Case studies – Part II: Coarse material 408
17.1 Introduction 408
17.1.1 Dilute phase conveying of magnesium sulphate 408
17.2 Conveying data 408
17.2.1 Conveying duty 409
17.2.2 Conveying capability 410
17.2.3 Summary 410
17.3 Procedure 411
17.3.1 Operating point 411
17.3.2 Air only pressure drop values 411
17.3.2.1 Test pipeline 412
17.3.2.2 Plant pipeline of 105 mm bore 412
17.3.2.3 Plant pipeline of 250 mm bore 413
17.3.3 Equivalent lengths 413
17.3.3.1 Test pipeline 414
17.3.3.2 Plant pipeline 414
17.3.4 Scaling 414
17.3.4.1 Scaling for length 414
17.3.4.2 Scaling for bore 414
17.3.5 Air requirements 415
17.3.5.1 Air flow rate 415
17.3.5.2 Power required 415
17.3.5.3 Specific cost 415
17.3.5.4 Solids loading ratio 416
18. First approximation design methods 417
18.1 Introduction 417
18.1.1 Methods presented 417
18.2 Air only pressure drop method 418
18.2.1 Basic equations 418
18.2.1.1 Solids loading ratio 418
18.2.1.2 The Ideal Gas Law 418
18.2.1.3 Volumetric flow rate 419
18.2.2 Derived relationships 419
18.2.2.1 Material flow rate 419
18.2.2.2 Pipeline bore 420
18.2.2.3 Conveying line pressure drop 420
18.2.2.4 Reference conditions 420
18.2.3 Empirical relationships 420
18.2.3.1 Conveying line inlet air velocity 420
18.2.3.2 Solids loading ratio 421
18.2.4 Working relationships 421
18.2.4.1 Material flow rate 422
18.2.4.1.1 Negative pressure systems 422
18.2.4.1.2 Positive pressure systems 422
18.2.4.2 Pipeline bore 422
18.2.4.3 Air supply pressure 423
18.2.4.3.1 Negative pressure systems 423
18.2.4.3.2 Positive pressure systems 423
18.2.4.4 Air only pressure drop 423
18.2.4.4.1 Negative pressure systems 424
18.2.4.4.2 Positive pressure systems 424
18.2.4.5 Vertical conveying 424
18.2.5 Procedure 424
18.2.5.1 Air only pressure drop 425
18.2.5.2 Air supply pressure 425
18.3 Universal conveying characteristics method 426
18.3.1 Straight pipeline 426
18.3.1.1 Vertical pipelines 427
18.3.1.2 Pipeline bore 427
18.3.1.3 Stepped pipelines 428
18.3.2 Pipeline bends 428
18.3.3 Minimum conveying air velocity 429
18.3.3.1 Conveying line inlet air velocity 429
18.3.4 Operating point 429
18.3.4.1 Solids loading ratios 430
18.3.4.2 Influence of distance and pressure 431
18.3.5 Air only pressure drop 432
18.3.6 Procedure 432
18.3.6.1 Dilute phase conveying 432
18.3.6.2 Dense phase conveying 433
19. Multiple use systems 436
19.1 Introduction 436
19.2 Multiple material handling 437
19.2.1 Air supply control 438
19.2.2 Material flow control 439
19.3 Multiple delivery points 439
19.3.1 Material influences 439
19.4 The use of stepped pipelines 441
19.4.1 Flour and sugar 441
19.4.2 Alumina 443
19.4.3 Pulverized fuel ash 445
19.4.4 Step location 448
References 448
Part C: System Operation 450
20. Troubleshooting and material flow problems 452
20.1 Introduction 452
20.2 Pipeline blockage 452
20.2.1 General 452
20.2.1.1 Check list 453
20.2.2 On commissioning 453
20.2.2.1 Incorrect air mover specification 454
20.2.2.1.1 Conveying air velocity 454
20.2.2.1.2 Influence of solids loading ratio 455
20.2.2.1.3 Air mover change 455
20.2.2.1.4 Conveying limitations 456
20.2.2.1.5 Influence of material type 457
20.2.2.1.6 Air leakage allowance 458
20.2.2.2 Over feeding of pipeline 458
20.2.2.2.1 Compressor capability 458
20.2.2.2.2 Material capability 459
20.2.2.2.3 Feeder control 460
20.2.2.2.4 Performance monitoring 460
20.2.2.2.5 Influence of pressure 462
20.2.2.3 Non steady feeding of pipeline 462
20.2.2.3.1 Commissioning 463
20.2.3 On start up 463
20.2.3.1 Moisture in line 463
20.2.3.1.1 Air drying systems 464
20.2.3.2 Cold air 465
20.2.3.3 Material in pipeline 466
20.2.3.4 After unexpected shut down 466
20.2.4 After a period of time 467
20.2.4.1 Component wear 467
20.2.4.2 Pipeline effects 468
20.2.5 With new material 469
20.2.5.1 Conveying capability 469
20.2.5.2 Air requirements 470
20.2.6 With change of distance 471
20.2.6.1 Material feed rate 471
20.2.6.2 Air flow rate 472
20.2.6.3 Conveying potential 473
21. Optimizing and up-rating of existing systems 474
21.1 Introduction 474
21.1.1 Optimizing conveying conditions 474
21.1.2 Modifying plant components 475
21.1.3 Replacing plant components 475
21.2 System not capable of duty 476
21.2.1 Material feeding 476
21.2.2 Air filtration 477
21.2.3 Reduce air flow rate 477
21.3 Optimizing existing systems 477
21.3.1 Control and instrumentation 477
21.3.2 Feeder considerations 478
21.3.3 The use of a sight glass 478
21.3.4 Off-take systems 479
21.4 Case study 480
21.4.1 The influence of changing air flow rate 480
21.4.1.1 Increasing air flow rate 482
21.4.1.2 Decreasing air flow rate 483
21.4.1.2.1 The effects of solids loading ratio 484
21.4.1.2.2 Power requirements 484
21.4.2 The influence of changing pipeline diameter 485
21.4.2.1 System potential 487
21.5 Alternative methods of up-rating 487
21.5.1 Pipeline feeding 488
21.5.2 Pipeline modifications 489
21.5.3 Air supply pressure 490
22. Operating problems 491
22.1 Introduction 491
22.1.1 Existing plant 491
22.2 Types of system 492
22.2.1 Positive pressure systems 492
22.2.1.1 Multi point feeding 492
22.2.2 Negative pressure systems 492
22.2.2.1 Air filtration 492
22.2.2.1.1 Back-up filters 493
22.2.2.2 Multi point discharge 493
22.2.2.3 Air ingress 493
22.2.2.3.1 Into reception hopper 493
22.2.2.3.2 Into pipeline 494
22.2.2.4 Stepped pipelines 494
22.2.2.5 Air mover specification 494
22.2.3 Combined systems 494
22.2.4 Fan systems 495
22.2.5 Single plug blow tank systems 495
22.3 System components 495
22.3.1 Blowers 496
22.3.1.1 Air filters 496
22.3.2 Blow tanks 496
22.3.2.1 Control 496
22.3.2.2 Discharge limits 497
22.3.2.3 Change of distance or material 497
22.3.2.4 Discharge valve 498
22.3.2.5 Moisture in air 498
22.3.2.6 Pressure drop 498
22.3.2.7 Performance monitoring 499
22.3.2.8 Granular materials 499
22.3.3 Rotary valves 499
23.3.3.1 Flow control 500
22.3.3.2 Air leakage 500
22.3.3.2.1 Venting 500
22.3.3.3 Valve seizure 501
22.3.3.4 Valve wear 501
22.3.4 Filters 501
22.3.4.1 Material degradation 501
22.3.4.2 Maintenance 502
22.3.4.3 Sizing 502
22.3.4.4 Batch cycles 503
22.3.5 Vacuum nozzles 503
22.3.5.1 Flow control 503
22.4 System related 504
22.4.1 Altitude 504
22.4.2 Condensation 504
22.4.3 Electrostatics 504
22.4.4 Erosive wear 505
22.4.5 Explosions 505
22.4.6 Pipeline purging 505
22.4.7 Plant wear 507
22.4.8 Temperature variations 507
22.5 Material related 507
22.5.1 Angel hairs 507
22.5.2 Coating of pipelines 507
22.5.3 Cohesive materials 508
22.5.4 Consolidation of materials 508
22.5.5 Degradation of materials 508
22.5.6 Granular materials 509
22.5.7 Hygroscopic materials 509
22.5.8 Large particles 509
22.5.9 Material grade 509
22.5.10 Temperature 510
22.5.11 Wet materials 510
References 510
23. Erosive wear 511
23.1 Introduction 511
23.1.1 Data sources 511
23.1.2 Issues considered 512
23.2 Influence of variables 512
23.2.1 Impact angle and surface material 512
23.2.1.1 Theories proposed 513
23.2.2 Velocity 513
23.2.2.1 Surface material 514
23.2.2.2 Bend wear 514
23.2.3 Particle size 515
23.2.3.1 Bend wear 517
23.2.4 Particle hardness 517
23.2.4.1 Bend wear 518
23.2.4.2 Hardness measurement 518
23.2.5 Surface material 519
23.2.5.1 Steels – heat treated 520
23.2.5.2 Resilient materials 522
23.2.5.3 Hard materials 522
23.2.6 Particle concentration 523
23.2.6.1 Bend wear 524
23.2.7 Particle shape 525
23.2.8 Surface finish 525
23.3 Industrial solutions and practical issues 525
23.3.1 Pipeline considerations 525
23.3.2 Bend wear 526
23.3.2.1 Influence of bend geometry 526
23.3.2.2 Long radius bends 527
23.3.2.3 Short radius bends 528
23.3.2.4 Air injection 529
23.3.2.5 The use of hard materials 529
23.3.2.6 The use of resilient materials 530
23.3.2.7 Surface coatings 531
23.3.2.8 Wear back methods 531
23.3.2.9 The use of inserts 532
23.3.2.10 Ease of maintenance 532
23.3.3 Wear patterns and deflecting flows 533
23.3.3.1 Influence of impact angle 534
23.3.4 Wear of straight pipeline 535
23.3.4.1 Following bends 535
23.3.4.2 Pipe section joints 536
23.3.4.3 Large particles 537
References 537
24. Particle degradation 539
24.1 Introduction 539
24.1.1 Particle breakage 539
24.1.2 Operating problems 540
24.1.2.1 Filtration problems 541
24.1.2.2 Flow problems 541
24.1.2.3 Potential explosion problems 541
24.1.3 Test rigs and data sources 542
24.1.3.1 Acceleration tube device 542
24.2 Influence of variables 543
24.2.1 Velocity 543
24.2.1.1 Peas 543
24.2.1.2 Quartz 544
24.2.1.3 Aluminium oxide 545
24.2.2 Particle size 546
24.2.2.1 Particle velocity influence 546
24.2.3 Surface material 547
24.2.3.1 Material type 547
24.2.3.2 Surface thickness 548
24.2.4 Particulate material 549
24.2.5 Particle impact angle 549
24.2.6 Other variables 551
24.3 Recommendations and practical issues 551
24.3.1 Particle velocity 551
24.3.1.1 Dense phase conveying 551
24.3.1.2 Dilute phase conveying 552
24.3.2 Particle impact angle 552
24.3.3 Bend material 552
24.4 Pneumatic conveying data 553
24.4.1 Experimental details 553
24.4.2 Materials tested 554
24.4.3 Conveying details 555
24.4.4 Test results 555
24.5 Particle melting 557
24.5.1 Mechanics of the process 558
24.5.2 Influence of variables 558
24.5.3 Pipeline treatment 558
References 559
25. Moisture and condensation 560
25.1 Introduction 560
25.2 Humidity 560
25.2.1 Specific humidity 561
25.2.1.1 The influence of temperature 563
25.2.1.2 The influence of pressure 563
25.2.2 Relative humidity 565
25.2.2.1 Psychrometric chart 566
25.2.3 Universal model 567
25.3 Air processes 567
25.3.1 Heating 567
25.3.2 Cooling 568
25.3.2.1 Condensation in reception hopper 569
25.3.3 Compressing 570
25.3.3.1 Adiabatic compression 571
25.3.3.2 Isothermal compression 572
25.3.4 Compression and cooling 573
25.3.5 Expanding 574
25.3.5.1 Vacuum conveying 574
25.3.6 Drying 575
25.3.6.1 Filters 575
25.3.6.2 Refrigerants 575
25.3.6.3 Desiccants 576
25.4 Energy considerations 577
25.4.1 Steady Flow Energy Equation 577
25.4.1.1 Evaporative cooling 578
25.4.1.2 Flash drying 581
25.4.1.3 Vacuum drying 581
25.5 Nomenclature 582
25.5.1 Greek 582
25.5.2 Subscripts 582
26. Health and safety 583
26.1 Introduction 583
26.1.1 System flexibility 583
26.1.2 Industries and materials 583
26.1.3 Mode of conveying 584
26.1.4 System integration 584
26.2 Dust risks 584
26.2.1 Dust emission 585
26.2.1.1 Dust as a health hazard 586
26.2.1.2 Dust concentration limits 586
26.2.1.2 Dust suppression 588
26.2.2 Explosion risks 588
26.2.2.1 Ignition sources 589
26.2.2.2 Explosibility limits 589
26.2.2.3 Pressure generation 590
26.2.2.4 Expansion effects 591
26.2.2.5 Oxygen concentration 591
26.3 Conveying systems 591
26.3.1 Closed systems 592
26.3.2 Open systems 592
26.3.2.1 Positive pressure systems 593
26.3.2.2 Negative pressure (vacuum) systems 593
26.4 System components 593
26.4.1 Blowers and compressors 594
26.4.1.1 Oil free air 594
26.4.2 Pipeline feeding 594
26.4.2.1 Rotary valves 595
26.4.2.2 Blow tanks 595
26.5 Conveying operations 596
26.5.1 Tramp materials 596
26.5.2 Static electricity 597
26.5.2.1 Earthing 597
26.5.2.2 Humidity control 598
26.5.3 Particle attrition 598
26.5.4 Erosive wear 598
26.5.5 Material deposition 599
26.5.5.1 Pipeline purging 599
26.5.6 Power failure 599
26.6 Explosion protection 600
26.6.1 Minimizing sources and prevention of ignition 601
26.6.1.1 Inerting 601
26.6.2 Containment 601
26.6.3 Explosion relief venting 602
26.6.4 Detection and suppression 603
26.6.5 Secondary explosions 604
26.6.6 Determination of explosion parameters 605
26.6.6.1 Test apparatus 606
26.6.6.2 Material classification 606
References 607
Appendix 1: Determination of relevant material properties 608
A1.1 Introduction 608
A1.1.1 The need for characterization 608
A1.1.2 Particle and bulk properties 608
A1.2 Particle size and shape 609
A1.2.1 Particle size 609
A1.2.2 Particle size distribution 610
A1.2.2.1 Cumulative representation 610
A1.2.2.2 Fractional representation 610
A1.2.2.3 Methods of determining size 611
A1.2.2.3.1 Sieving 611
A1.2.2.3.2 Sedimentation 612
A1.2.2.3.3 Elutriation 612
A1.2.2.3.4 Electrical sensing zone 612
A1.2.2.3.5 Microscopy 613
A1.2.2.3.6 Laser diffraction 613
A1.2.3 Particle shape 613
A1.2.3.1 Descriptive terms 613
A1.2.3.2 Shape factors 614
A1.2.3.3 Specific surface 615
A1.3 Particle and bulk density 615
A1.3.1 Particle density 615
A1.3.1.1 Reference values 615
A.1.3.1.2 Methods of determination 615
A1.3.1.2.1 Relative density method 616
A1.3.1.2.2 Air comparison pycnometer 616
A1.3.2 Bulk density 616
A1.3.2.1 Reference values 616
A1.3.2.1.1 As poured bulk density 616
A1.3.2.1.2 Compacted (tapped) bulk density 617
A1.3.2.1.3 Aerated bulk density 617
A1.3.2.2 Application 617
A1.3.3 Voidage 617
A1.4 Flow properties 618
A1.4.1 Factors influencing flowability 618
A1.4.1.1 Particle size 618
A1.4.1.2 Particle shape 619
A1.4.1.3 Electrostatic charge 619
A1.4.1.4 Moisture 619
A1.4.2 Tests for flowability 619
A1.4.2.1 Angle of repose 620
A1.4.2.1.1 Poured angle of repose 620
A1.4.2.1.2 Drained angle of repose 620
A1.4.2.1.3 Fluidized angle of repose 620
A1.4.2.2 Application 620
A1.5 Aeration properties 621
A1.5.1 Fluidization 621
A1.5.1.1 Fluidized angle of repose 621
A1.5.1.2 Applications 622
A1.5.2 The permeameter 622
A1.5.2.1 Superficial air velocity 622
A1.5.2.2 Permeability factor 623
A1.5.3 The fluidization process 623
A1.5.3.1 Minimum fluidizing velocity 624
A1.5.3.2 Pneumatic transport 624
A1.5.4 The influence of particle size and density 624
A1.5.4.1 The Geldart classification 624
A1.5.5 Air retention 625
A1.5.5.1 De-aeration constant 625
A1.5.5.1.1 Analysis 626
A1.5.5.1.2 Vibrated de-aeration constant 626
A1.5.5.1.3 Analysis 627
A1.5.6 Specific surface 628
A1.5.6.1 British Standard procedure 628
A1.5.6.2 Lea and Nurse method 628
A1.5.6.3 The Blaine method 629
References 629
Appendix 2: Additional conveying data 630
A2.1 Introduction 630
A2.2 Materials and pipelines listings 630
A2.3 Material properties listings 633
A2.4 Additional conveying data 635
Index 642
A 642
B 642
C 643
D 644
E 644
F 645
G 645
H 645
I 646
L 646
M 646
N 646
O 647
P 647
Q 648
R 648
S 648
T 649
V 649
W 650
Z 650