Solid/Liquid Separation: Equipment Selection and Process Design

by Tarleton; Wakeman

• ISBN13: 9781856174213
• ISBN10: 1856174212
• Edition: 1st
• Format: Hardcover
• Copyright: 2006-12-07
• Publisher: Elsevier Science

Summary

"In this volume, the third in a set written for the industrial process and chemical engineer, the authors provide detailed information on filtration equipment and media which will allow the reader to consider the pre-treatment of suspensions, selection of the most appropriated equipment for the task, data analysis and subsequent filter design. The result is a guide for frequent reference by all involved with industrial separation processes."--BOOK JACKET.

Table of Contents

Preface	xii
1 Solid/liquid separation equipment	1
1.1 Gravity thickeners and clarifiers	2
1.1.1 Circular basin thickener	3
1.1.2 High capacity thickeners	5
1.1.2.1 Circular	5
1.1.2.2 Deep cone	6
1.1.2.3 Lamella	6
1.1.3 Clarifiers	7
1.2 Hydrocyclones	10
1.2.1 Conical reverse flow	10
1.2.2 Circulating bed	11
1.3 Centrifuges	11
1.3.1 Sedimenting centrifuges	11
1.3.1.1 Tubular bowl	12
1.3.1.2 Basket	13
1.3.1.3 Disc stack	14
1.3.1.4 Scroll decanter	16
1.3.2 Filtering centrifuges	17
1.3.2.1 Basket	19
1.3.2.2 Cone screen	20
1.3.2.3 Pusher	23
1.3.2.4 Baffle	24
1.3.2.5 Inverting bag centrifuge	24
1.4 Filters	25
1.4.1 Vacuum filters	26
1.4.1.1 Single leaf	26
1.4.1.2 Multi-element leaf	28
1.4.1.3 Horizontal belt	29
1.4.1.4 Horizontal rotary	31
1.4.1.5 Rotary drum	33
1.4.1.6 Rotary disc	35
1.4.2 Pressure filters and presses	37
1.4.2.1 Single leaf	37
1.4.2.2 Multi-element leaf or candle	38
1.4.2.3 Filter presses	40
1.4.2.4 Sheet filter	43
1.4.2.5 Variable volume filters and Presses	43
1.4.2.6 Continuous pressure filters	49
1.4.2.7 Cartridge filter	51
1.4.2.8 Bag filter	53
1.4.3 Precoat filters	54
1.4.3.1 Precoat rotary drum	54
1.4.3.2 Precoat pressure	55
1.4.4 Depth filters	55
1.4.4.1 Sand bed	56
1.4.4.2 Fibre bed	56
1.5 Classifiers	58
1.5.1 Hydraulic	58
1.5.2 Mechanical	59
1.5.3 Screen	60
1.6 Membrane filters	61
1.6.1 Dead-end	61
1.6.2 Low shear crossflow	63
1.6.2.1 Ultrafilters	64
1.6.2.2 Microfilters	66
1.6.3 High shear crossflow	67
1.7 Other equipment	69
1.7.1 Flotation	69
1.7.2 Strainer	70
1.7.3 Gravity Nutsche filters	71
1.7.4 Gravity belt filter	72
1.8 Force field assisted separations	73
1.8.1 Magnetic field	73
1.8.2 High voltage electric field	74
1.8.3 Low voltage electric field	75
1.8.4 Ultrasonic field	77
1.9 Conclusions	77
2 Filter media	78
2.1 Properties of filter media	80
2.2 Textile media	84
2.2.1 Woven fabrics	84
2.2.1.1 Yarn types	85
2.2.1.2 Fabric constructions and properties	86
2.2.1.3 Fabric finishing processes	94
2.2.2 Composite media	95
2.2.2.1 Surface coated fabrics	95
2.2.2.2 Laminated fabrics	96
2.2.2.3 Double layer weaves	97
2.2.3 Needlefelts and other nonwoven media	98
2.2.4 Selection and applications of filter cloths	101
2.2.5 Damage to filter media	102
2.3 Filter papers and sheets	109
2.3.1 Filter papers	109
2.3.1.1 Industrial papers	110
2.3.1.2 Laboratory papers	110
2.3.2 Filter sheets	110
2.4 Membranes	111
2.5 Screens and meshes	112
2.5.1 Wire cloths	113
2.5.2 Perforated sheets	114
2.5.3 Wedge wire screens	115
2.6 Porous sheets and tubes	117
2.7 Cartridges	118
2.8 Precoats and body aids (filter aids)	120
2.9 Conclusions	125
3 Pretreatment of suspensions	126
3.1 Basic concepts	126
3.2 Coagulation principles and mechanisms	130
3.2.1 Mechanical agitation	130
3.2.2 Indifferent electrolytes	130
3.2.3 Multivalent metal ions (inorganic coagulants)	132
3.2.4 Lower molecular weight polymers (organic coagulants)	134
3.3 Flocculation principles and mechanisms	134
3.3.1 Forms of flocculation and polymer adsorption	135
3.3.2 Lower molecular weight polymers (charge neutralisation)	137
3.3.3 Higher molecular weight polymers (bridging flocculation)	139
3.4 Types of pretreatment chemicals	141
3.4.1 Coagulants	141
3.4.2 Flocculants	142
3.5 Effectiveness and selection of chemical pretreatments	144
3.5.1 Jar settling test	144
3.5.2 Filter test	145
3.5.3 Capillary suction test	145
3.5.4 Coagulant and flocculant selection	146
3.6 Other methods of pretreatment	147
3.6.1 Suspension heating	147
3.6.2 Suspension freezing	148
3.6.3 Particle/crystal formation	148
3.6.4 Elutriation and suspension thickening	148
3.6.5 Ultrasonics	149
3.6.6 Irradiation	150
3.6.7 Addition of solvents/surfactants	150
3.6.8 Addition of filter aid	151
3.7 Conclusions	151
4 Data acquisition, analysis and scale-up	152
4.1 Filtration (cake formation)	152
4.1.1 Test procedures	152
4.1.2 General filtration equation	155
4.1.3 Evaluation of terms in the general filtration equation	157
4.1.4 Evaluation of filter cake properties	158
4.1.5 Example 4.1	161
4.2 Gas deliquoring	164
4.2.1 Test procedure	164
4.2.2 Data analysis procedure	165
4.2.3 Example 4.2	166
4.3 Cake washing	168
4.3.1 Test procedure	169
4.3.2 Data analysis procedure	170
4.3.3 Example 4.3	172
4.4 Jar sedimentation	174
4.4.1 Test procedure	175
4.4.2 Data analysis procedure	176
4.4.3 Example 4.4	177
4.5 Expression (cake formation/consolidation)	178
4.5.1 General test procedure	178
4.5.2 Data manipulation	180
4.5.3 Filtration phase analysis	182
4.5.4 Consolidation phase analysis	183
4.5.5 Example 4.5	184
4.5.6 Estimates of the transition point and consolidation index	189
4.6 State-of-the-art apparatus	192
4.7 Evaluation of scale-up coefficients	196
4.7.1 Example 4.6	198
4.8 Conclusions	199
5 Selection, data analysis and simulation by computer software	201
5.1 Equipment selection	201
5.1.1 Methods of equipment selection	202
5.1.2 Recommended selection procedure	205
5.1.2.1 Specification of duty	206
5.1.2.2 Specification of sedimentation performance	206
5.1.2.3 Specification of filtration performance	207
5.1.2.4 Tables of equipment and letter codings	209
5.2 Implementation of computer software	220
5.3 Descriptions of FDS	226
5.3.1 Equipment selection module	228
5.3.2 Data analysis module	230
5.3.3 Equipment simulation modules	234
5.4 Examples of FDS use	239
5.4.1 Example 5.1: Basic selection and data analysis procedures	240
5.4.2 Example 5.2: Advanced selection procedure	242
5.5 Shortlisting equipment for pilot scale testing and/or simulation	246
5.6 Conclusions	254
6 Process design for batch separations	256
6.1 Batch filter cycle configurations	257
6.1.1 Nutsche filters	257
6.1.2 Multi-element vacuum filter	257
6.1.3 Multi-element leaf and candle pressure filters	257
6.1.4 Horizontal diaphragm, plate and frame, and recessed plate presses	260
6.1.5 Vertical diaphragm presses	261
6.1.6 Tube press	261
6.2 Design equations for batch filter cycles	264
6.2.1 Filtration (cake formation) phase	265
6.2.1.1 Nutsche and multi-element vacuum filters	266
6.2.1.2 Filter and diaphragm presses and multi-element leaf pressure filters	268
6.2.1.3 Tube press	271
6.2.1.4 Multi-element candle filter	272
6.2.2 Compression deliquoring	273
6.2.3 Displacement washing	276
6.2.4 Gas deliquoring	280
6.2.5 Optimisation of filtration time for batch filters	285
6.3 Design equations for centrifugal filter cycles	286
6.4 Examples of batch filter cycle calculations	288
6.4.1 Example 6.1: Horizontal diaphragm filter press	288
6.4.1.1 Cake formation (filtration) phases	289
6.4.1.2 Consolidation (compression deliquoring) phase	295
6.4.1.3 Washing phase	298
6.4.1.4 Gas deliquoring phase	302
6.4.1.5 Summary of results and filter cycle illustrations	306
6.4.2 Example 6.2: Nutsche filter	306
6.4.2.1 Cake formation (filtration) phase	309
6.4.2.2 Washing phase	312
6.4.2.3 Gas deliquoring phase	315
6.4.2.4 Summary of results and process implications	318
6.5 Example of computer simulation – diaphragm filter press	320
6.5.1 Fixed mass of solids	320
6.5.2 Fixed filter area	325
6.6 Conclusions	328
7 Process design for continuous separations	329
7.1 Continuous filter cycle configurations	330
7.1.1 Horizontal belt filter	330
7.1.2 Rotary drum filter	331
7.1.3 Rotary table and tilting pan filters	332
7.1.4 Rotary disc filter	333
7.2 Design equations for continuous filter cycles	334
7.2.1 Filtration (cake formation) phase	336
7.2.2 Displacement washing	339
7.2.3 Gas deliquoring	341
7.3 Examples of continuous filter cycle calculations	344
7.3.1 Example 7.1: Horizontal belt filter	344
7.3.1.1 Cake formation (filtration) phase	344
7.3.1.2 Washing phase	348
7.3.1.3 Deliquoring phase	351
7.3.1.4 Summary of results and filter cycle illustrations	356
7.3.2 Example 7.2: Rotary drum filter	356
7.3.2.1 Cake formation (filtration) phase	359
7.3.2.2 Rise phase	361
7.3.2.3 Washing phase	366
7.3.2.4 Deliquoring phase	370
7.3.2.5 Summary of results and filter cycle illustrations	371
7.4 Example of computer simulation — belt filter	372
7.4.1 Effects of belt speed	373
7.4.2 Effects of applied vacuum	374
7.4.3 Effects of plant altitude (barometric pressure)	376
7.4.4 Effects of temperature	376
7.4.5 Effects of particle size	380
7.5 Conclusions	382
Nomenclature	383
Bibliography	391
Appendix A: Variable ranges for filter cycle calculations	410
Appendix B: Correlations for cake washing and gas deliquoring	420
Appendix C: Definitions and conversions for concentration	424
Appendix D: Troubleshooting filter operation	429
Appendix E: Comparisons between experimental data and design equation predictions	434
Index	441