AIR POLLUTION CONTROL
TECHNOLOGY AND COSTS
IN NINE SELECTED AREAS
INDUSTRIAL GAS CLEANING INSTITUTE, INC.
STAMFORD, CONNECTICUT
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IGCI
THE CLEAN AIR PEOPLE
INDUSTRIAL GAS CLEANING INSTITUTE, INC.
P.O. BOX 1333. STAMFORD. CONN. O69O4
Contract No. 68-02-0301
AIR POLLUTION CONTROL
TECHNOLOGY AND COSTS
IN NINE SELECTED AREAS
FINAL REPORT
(Submitted September 30, 1972)
by
L. C. Hardison, Coordinating Engineer
and
Carroll A. Greathouse, Project Director
Industrial Gas Cleaning Institute
Box 1333, Stamford, Connecticut 06904
Prepared for
The Environmental Protection Agency
Durham, North Carolina 27701
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INDUSTRIAL GAS CLEANING INSTITUTE, INC.
Box 1333
Stamford, Connecticut 06904
MEMBERS
AIR CORRECTION DIVISION, UOP
AMERICAN AIR FILTER CO., INC.
AMERICAN STANDARD, INC.
Industrial Products Division
ARCO INDUSTRIES CORPORATION
BELCO POLLUTION CONTROL CORP.
BUELL, Div. of Envirotech Corp.
BUFFALO FORGE CO.
THE CARBORUNDUM COMPANY
Pollution Control Division
THE CEILCOTE CO.
CHEMICAL CONSTRUCTION CORP.
Pollution Control Division
THE DUCON COMPANY, INC.
DUSTEX DIVISION
American Precision Industries
FISHER-KLOSTERMAN, INC.
FULLER CO., DRACCO PRODUCTS
GALLAGHER-KAISER CORP.
KIRK AND BLUM MANUFACTURING CO.
KOERTROL CORPORATION
KOPPERS COMPANY, INC.
Metal Products Division
MIKROPUL
Div. of The Slick Corporation
NATIONAL DUST COLLECTOR CORP.
Subsidiary of Environeering, Inc.
PEABODY ENGINEERING CORP.
POLLUTION CONTROL - WALTHER, INC.
PRECIPITAIR POLLUTION CONTROL, INC.
Subsidiary of Advance-Ross Corp.
PRECIPITATION ASSOC. OF AMERICA
RESEARCH-COTTRELL, INC.
SEVERSKY ELECTRONATOM CORP.
THE TORIT CORPORATION
WESTERN PRECIPITATION DIVISION
Joy Manufacturing Co.
WHEELABRATOR CORPORATION
ZURN INDUSTRIES, INC.
STATEMENT OF PURPOSES
The Industrial Gas Cleaning Institute, incorporated in 1960 in the State of New
York, was founded to further the interests of manufacturers of air pollution control
equipment, by
encouraging the general improvement of engineering and technical standards in the
manufacture, installation, operation, and performance of equipment
disseminating information on air pollution; the effect of industrial gas cleaning on
public health; and general economic, social, scientific, technical, and governmental
matters affecting the industry, together with the views of the members thereon; and
promoting the industry through desirable advertising and publicity.
ACKNOWLEDGEMENT
The efforts of the IGCI Engineering Standards Committee in the preparation, editing
and reviewing of this Report are gratefully acknowledged:
Harry Krockta, Chairman, The Ducon Company, Inc.
G. L. Brewer, Air Correction Division, UOP
C. A. Gallaer, Buell Division of Envirotech Corp.
N. D. Phillips, Fuller Co., Dracco Products
E. P. Stastny, Koppers Company, Inc., Metal Products Division
IGCI
INDUSTRIAL GAS CLEANING INSTITUTE, INC.
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TABLE OF CONTENTS
Page No.
Introduction 1
Technical Data 2
A. General Description 2
1. Format
2. Selection of Applicable Equipment Types
3. Basis for Preparing Specifications and Bid Prices
4. Presentation of Data
B. Process Description and Costs 17
1. Rendering Industry 17
a. Cookers
b. Expellers
c. Room Ventilation
2. Petroleum Refining Industry 83
a. Fluidized Bed Catalytic Cracking Units With
CO Boilers
3. Asphalt Batching Industry 115
4. Iron and Steel Industry 151
a. Basic Oxygen Furnaces
5. Coal Cleaning Industry 211
6. Brick and Tile Kilns 239
7. Copper Smelting Industry 271
a. Roasting Ovens
b. Reverberatory Furnaces
8. Kraft Paper Industry 317
a. Bark Boilers
9. Ferroalloys Industry 349
a. Ferrosilicon Furnaces
b. Ferrochrome Furnaces
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TABLE OF CONTENTS (cont.)
Page No.
C. Additional Cost Data 397
1. Discussion of Cost Basis 397
2. Derived Cost Indices 399
3. Operating Costs at Various
Utility Cost Levels 455
4. Generalized Cost Data 561
III. Conclusions & Recommendations 573
List of Figures
List of Tables
List of Appendices
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LIST OF FIGURES
Page No.
Figure 1 Dry Rendering Operation 23
Figure 2 Continuous Rendering Flow Scheme 24
Figure 3 Wet Rendering Operation 25
Figure 4 Rate of Vapor Evolution from Dry Rendering 31
Figure 5 Activated Carbon Deodorizer Integrated with Solids
Collector and Condenser 37
Figure 6 Capital Cost of Medium Efficiency Scrubbers Only
for Rendering Plants 52
Figure 7 Capital Cost of High Efficiency Scrubbers Only
for Rendering Plants 53
Figure 8 Capital Cost of Medium Efficiency Scrubbers plus
Auxiliaries for Rendering Plants 54
Figure 9 Capital Cost of High Efficiency Scrubbers plus
Auxiliaries for Rendering Plants 55
Figure 10 Capital Cost of Medium Efficiency Turnkey Scrubbing
Scrubbing Systems for Rendering Plants 56
Figure 11 Capital Cost of High Efficiency Turnkey Scrubbing
Systems for Rendering Plants 57
Figure 12 Confidence Limits for Capital Cost of Medium
Efficiency Scrubbers Only for Rendering
Plants 58
Figure 13 Confidence Limits for Capital Cost of High Efficiency
Scrubbers Only for Rendering Plants 59
Figure 14 Annual Costs for Wet Scrubbers for Rendering
Plants 60
Figure 15 Capital Cost of Incinerators Only for Rendering
Plants 76
Figure 16 Capital Cost of Incinerators plus Auxiliaries
for Rendering Plants 77
Figure 17 Capital Cost of Turnkey I ncinerator Systems
for Rendering Plants 78
Figure 18 Confidence Limits for Incinerators plus Auxiliaries
for Rendering Plants 79
Figure 19 Confidence Limits for Turnkey Incinerator Systems
for Rendering Plants 80
Figure 20 Annual Costs for Incinerators for Rendering Plants 81
Figure 21 Flow Diagram of FCC Unit 88
Figure 22 Capital Cost of Electrostatic Precipitators for FCC Units 106
Figure 23 Annual Costs for Electrostatic Precipitators for FCC Units .... 107
Figure 24 Confidence Limits for Capital Cost of Installed Electrostatic
Precipitators for FCC Units 108
Figure 25 Confidence Limits for Capital Cost of Precipitators Only for
FCC Units 109
Figure 26 Capital Costs for Tertiary Cyclones for FCC Units 112
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LIST OF FIGURES (cont.)
Page No.
Figure 27 Annual Costs for Tertiary Cyclones for FCC Units 113
Figure 28 Flow Diagram for Hot-Mix Asphalt Batch Plant H7
Figure 29 Rotary Dryer Configuration 118
Figure 30 Dryer Production Capacity Vs. Drum Gas Velocity 119
Figure 31 Dust Carryout Vs. Drum Gas Velocity 120
Figure 32 Ring Type Hood on a Dryer 125
Figure 33 Flow Diagram Showing Primary Collection 126
Figure 34 Capital Costs for Fabric Collectors for Asphalt Batching
Plants 136
Figure 35 Annual Costs for Fabric Collectors for Asphalt Batching
Plants 137
Figure 36 Confidence Limits for Capital Cost of Installed
Fabric Collectors for Asphalt Batching Plants 138
Figure 37 Confidence Limits for Capital Cost of Fabric Collectors
Plus Auxiliaries for Asphalt Batching Plants 139
Figure 38 Capital Costs for Wet Scrubbers for Asphalt Batching
Plants (LA-Process Weight Case) 144
Figure 39 Capital Costs for Wet Scrubbers for Asphalt Batching
Plants (High Efficiency Case) 145
Figure 40 Annual Costs for Wet Scrubbers for Asphalt Batching
Plants 147
Figure 41 Steel Production - United States 153
Figure 42 Flow Scheme BOF Steelmaking 154
Figure 43 Gas Cleaning Equipment for BOF
Steelmaking 155
Figure 44 Configuration of Typical BOF Vessel 159
Figure 45 Vapor Pressure of Iron and Other Materials of Importance
in BOF Steelmaking 162
Figure 46 Impurity Content as a Function of Time During Oxygen
Lancing 168
Figure 47 Two Patterns of Flow Rate from BOF's 169
Figure 48 Volume of BOF Gas Discharge Vs. Oxygen Blow Rate 170
Figure 49 Capital Costs for Precipitator Systems for BOF Steelmaking
(Intermediate Efficiency) 184
Figure 50 Annual Costs for Precipitators for BOF Steelmaking
(Intermediate Efficiency) 185
Figure 51 Capital Costs for Precipitator Systems for BOF Steelmaking
(High Efficiency) 186
Figure 52 Annual Costs for Precipitators for BOF Steelmaking
(High Efficiency) 187
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LIST OF FIGURES (cont.)
Page No.
Figure 53 Confidence Limits for Capital Costs of Precipitators for
BOF Steelmaking (Intermediate Efficiency) 188
Figure 54 Confidence Limits for Capital Costs of Precipitators for
BOF Steelmaking (High Efficiency) 189
Figure 55 Capital Costs for Wet Scrubber Systems for BOF Steelmaking
(Open Hood - High Efficiency) 200
Figure 56 Annual Costs for Wet Scrubber Systems for BOF Steelmaking
(Open Hood - High Efficiency) 201
Figure 57 Confidence Limits for Wet Scrubber Capital Cost Data,
BOF Steelmaking (Open Hood - High Efficiency) 202
Figure 58 Capital Costs for Wet Scrubber Systems for BOF Steelmaking
(Closed Hood - High Efficiency) 204
Figure 59 Annual Costs for Wet Scrubber Systems for BOF Steelmaking
(Closed Hood - High Efficiency) 205
Figure 60 Confidence Limits for Capital Cost of Wet Scrubbers Only
for BOF Steelmaking (Closed Hood - High Efficiency) , 206
Figure 61 Flow Diagram for Coal Cleaning Plant 213
Figure 62 Particle Size Distribution of Feed to Fluidized Bed Dryer .... 217
Figure 63 Particle Size Distribution Before and After Cyclone 218
Figure 64 Basic Types of Wet Scrubbers Used for Coal Cleaning 225
Figure 65 Capital Costs for Wet Scrubbers for Coal Cleaning Plants
(LA-Process Weight) 234
Figure 66 Annual Costs for Wet Scrubbers for Coal Cleaning Plants
(LA-Process Weight) 235
Figure 67 Capital Costs for Wet Scrubbers for Coal Cleaning Plants
(High Efficiency) 236
Figure 68 Annual Costs for Wet Scrubbers for Coal Cleaning Plants
(High Efficiency) 237
Figure 69 Plan Section of Tunnel Kiln 244
Figure 70 Capital Costs for Wet Scrubbers for Brick and Tile Kilns 260
Figure 71 Annual Costs for Wet Scrubbers for Brick and Tile Kilns .... 261
Figure 72 Confidence Limits for Capital Cost of Wet Scrubbers Only
for Brick and Tile Kilns 262
Figure 73 Capital Costs for Thermal Incinerators for Brick and Tile Kilns 268
Figure 74 Annual Costs for Thermal Incinerators for Brick and Tile Kilns 269
Figure 75 Schematic Diagram of Smelting Processes 274
Figure 76 Multiple Hearth Roaster 276
Figure 77 Schematic Drawing of Roaster Gas Cleaning System 281
Figure 78 Reverberatory Furnace 284
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LIST OF FIGURES (cont.)
Page No.
Figure 79 Capital Costs for Combined Gas Cleaning System for
Roasting Furnaces 300
Figure 80 Annual Costs for Combined Gas Cleaning System for
Roaster Furnaces 301
Figure 81 Capital Costs for Electrostatic Precipitators for Copper
Reverberatory Furnaces (High Efficiency) 306
Figure 82 Annual Costs for Electrostatic Precipitators for Copper
Reverberatory Furnaces (High Efficiency) 307
Figure 83 Capital Costs for Wet Scrubbers for Copper Reverberatory
Furnaces (High Efficiency) 314
Figure 84 Annual Costs for Wet Scrubbers for Copper Reverberatory
Furnaces (High Efficiency) 315
Figure 85 Bark Flow Diagram 318
Figure 86 Moisture Content of Bark and Wood 320
Figure 87 The Effect of Bark Moisture on Boiler Efficiency 322
Figure 88 Particle Size Distributions of Bark Boiler Fly Ash 325
Figure 89 Dust Loading of Boiler Exhaust Gases 329
Figure 90 Total Refuse Emission Rates 330
Figure 91 Capital Costs for Electrostatic Precipitators for Bark Boilers . . 338
Figure 92 Annual Costs for Electrostatic Precipitators for Bark Boilers . 339
Figure 93 Capital Costs for Wet Scrubbers for Bark Boilers 344
Figure 94 Annual Costs for Wet Scrubbers for Bark Boilers 345
Figure 95 Confidence Limits for Capital Costs of Wet Scrubbers Only
for Bark Boilers 346
Figure 96 Electric Furnace for Ferroalloy Production 350
Figure 97 Process Diagram for Low Carbon Ferrochrome Production .. . 353
Figure 98 Process Diagram for Low Carbon Ferrochrome Production .. . 355
Figure 99 Capital Costs for Fabric Filters for Ferrosilicon Furnaces .... 372
Figure 100 Annual Costs for Fabric Filters for Ferrosilicon Furnaces .... 373
Figure 101 Capital Costs for Fabric Filters for Ferrochrome Furnaces .. . 378
Figure 102 Annual Costs for Fabric Filters for Ferrochrome Furnaces ... 379
Figure 103 Capital Costs for Wet Scrubbers for Ferrosilicon Furnaces ... 388
Figure 104 Annual Costs for Wet Scrubbers for Ferrosilicon Furnaces .. . 389
Figure 105 Capital Costs for Wet Scrubbers for Ferrochrome Furnaces
(High Efficiency) 394
Figure 106 Annual Costs for Wet Scrubbers for Ferrochrome
Furnaces (High Efficiency) 395
Figure 107 Annual Costs for Wet Scrubbers for Rendering Cookers
and Hoods (Low Unit Cost) 459
Figure 108 Annual Costs for Wet Scrubbers for Rendering Cookers
and Hoods (High Unit Cost) 46Q
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LIST OF FIGURES (cont.)
Page No.
Figure 109 Annual Costs for Wet Scrubbers for Rendering Room Vents
(Low Unit Cost) 463
Figure 110 Annual Costs for Wet Scrubbers for Rendering Room Vents
(High Unit Cost) 464
Figure 111 Annual Costs for Wet Scrubbers for Rendering Combined
Vents (Low Unit Cost) 467
Figure 112 Annual Costs for Wet Scrubbers for Rendering Combined
Vents (High Unit Cost) 468
Figure 113 Annual Costs for Incinerators for Rendering Cookers
and Hoods (Low Unit Cost) 471
Figure 114 Annual Costs for Incinerators for Rendering Cookers
and Hoods (High Unit Cost) 472
Figure 115 Annual Costs for Incinerators for Rendering Room Vents
(Low Unit Cost) 475
Figure 116 Annual Costs for Incinerators for Rendering Room Vents
(High Unit Cost) 476
Figure 117 Annual Costs for Incinerators for Rendering Combined
Vents (Low Unit Cost) 479
Figure 118 Annual Costs for Incinerators for Rendering Combined
Vents (High Unit Cost) 480
Figure 119 Annual Costs for Electrostatic Precipitators for FCC Units
(Low Unit Cost) 483
Figure 120 Annual Costs for Electrostatic Precipitators for FCC Units
(High Unit Cost) 484
Figure 121 Annual Costs for Tertiary Cyclones for FCC Units
(Low Unit Cost) 487
Figure 122 Annual Costs for Tertiary Cyclones for FCC Units
(High Unit Cost) 488
Figure 123 Annual Costs for Fabric Collectors for Asphalt Batching
Plants (Low Unit Cost) 491
Figure 124 Annual Costs for Fabric Collectors for Asphalt Batching
Plants (High Unit Cost) 492
Figure 125 Annual Costs for Wet Scrubbers for Asphalt Batching
Plants (High Efficiency, Low Unit Cost) 495
Figure 126 Annual Costs for Wet Scrubbers for Asphalt Batching
Plants (High Efficiency, High Unit Cost) 496
Figure 127 Annual Costs for Precipitators for BOF Steelmaking
(Intermediate Efficiency, Low Unit Cost) 499
Figure 128 Annual Costs for Precipitators for BOF Steelmaking
(Intermediate Efficiency, High Unit Cost) 500
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LIST OF FIGURES (cont.)
Page No.
Figure 129 Annual Costs for Precipitators for BOF Steelmaking
(High Efficiency, Low Unit Cost) 501
Figure 130 Annual Costs for Precipitators for BOF Steelmaking
(High Efficiency, High Unit Cost) 502
Figure 131 Annual Costs for Wet Scrubber Systems for BOF
Steelmaking (Open Hood — High Efficiency,
Low Unit Cost) 505
Figure 132 Annual Costs for Wet Scrubber Systems for BOF
Steelmaking (Open Hood — High Efficiency,
High Unit Cost) 506
Figure 133 Annual Costs for Wet Scrubber Systems for BOF
Steelmaking (Closed Hood — High Efficiency,
Low Unit Cost) 509
Figure 134 Annual Costs for Wet Scrubber Systems for BOF
Steelmaking (Closed Hood — High Efficiency,
High Unit Cost) 510
Figure 135 Annual Costs for Wet Scrubbers for Coal Cleaning Plants
(LA-Process Weight, Low Unit Cost) 513
Figure 136 Annual Costs for Wet Scrubbers for Coal Cleaning Plants
(LA-Process Weight, High Unit Cost) 514
Figure 137 Annual Costs for Wet Scrubbers for Coal Cleaning Plants
(High Efficiency, Low Unit Cost) 515
Figure 138 Annual Costs for Wet Scrubbers for Coal Cleaning Plants
(High Efficiency, High Unit Cost) 516
Figure 139 Annual Costs for Wet Scrubbers for Brick and Tile Kilns
(Low Unit Cost) 519
Figure 140 Annual Costs for Wet Scrubbers for Brick and Tile Kilns
(High Unit Cost) 520
Figure 141 Annual Costs for Thermal Incinerators for Brick and
Tile Kilns (Low Unit Cost) 523
Figure 142 Annual Costs for Thermal Incinerators for Brick and
Tile Kilns (High Unit Cost) 524
Figure 143 Annual Costs for Combined Gas Cleaning Systems for
Copper Roasting Furnaces (Low Unit Cost) 527
Figure 144 Annual Costs for Combined Gas Cleaning Systems for
Copper Roasting Furnaces (High Unit Cost) 528
Figure 145 Annual Costs for Electrostatic Precipitators for Copper
Reverberatory Furnaces (High Efficiency, Low Unit Cost) 531
Figure 146 Annual Costs for Precipitators for Copper Reverberatory
Furnaces (High Efficiency, High Unit Cost) 532
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LIST OF FIGURES (cont.)
Page No.
Figure 147 Annual Costs for Wet Scrubbers for Copper Reverberatory
Furnaces (High Efficiency, Low Unit Cost) 535
Figure 148 Annual Costs for Wet Scrubbers for Copper Reverberatory
Furnaces (High Efficiency, High Unit Cost) 536
Figure 149 Annual Costs for Electrostatic Precipitators for Kraft Mill
Bark Boilers (Low Unit Cost) 539
Figure 150 Annual Costs for Electrostatic Precipitators for Kraft Mill
Bark Boilers (High Unit Cost) 540
Figure 151 Annual Costs for Wet Scrubbers for Bark Boilers
(Low Unit Cost) 543
Figure 152 Annual Costs for Wet Scrubbers for Bark Boilers
(High Unit Cost) 544
Figure 153 Annual Costs for Fabric Filters for Ferrosilicon Furnaces
(Low Unit Cost) 547
Figure 154 Annual Costs for Fabric Filters for Ferrosilicon Furnaces
(High Unit Cost) 548
Figure 155 Annual Costs for Fabric Filters for Ferrochrome Furnaces
(Low Unit Cost) 551
Figure 156 Annual Costs for Fabric Filters for Ferrochrome Furnaces
(High Unit Cost) 552
Figure 157 Annual Costs for Wet Scrubbers for Ferrosilicon Furnaces
(High Efficiency; Low Unit Cost) 555
Figure 158 Annual Costs for Wet Scrubbers for Ferrosilicon Furnaces
(High Efficiency; High Unit Cost) 556
Figure 159 Annual Costs for Wet Scrubbers for Ferrochrome Furnaces
(High Efficiency, Low Unit Cost) 559
Figure 160 Annual Costs for Wet Scrubbers for Ferrochrome Furnaces
(High Efficiency, High Unit Cost) 560
Figure 161 Capital Cost of Wet Scrubbers 562
Figure 162 Total Installed Cost of Wet Scrubber Systems 563
Figure 163 Capital Cost of Electrostatic Precipitators 564
Figure 164 Installed Cost of Electrostatic Precipitators 565
Figure 165 Annual Direct Operating Cost of Electrostatic
Precipitators 567
Figure 166 Capital Cost of Incinerators 568
Figure 167 Installed Cost of Incinerators 569
Figure 168 Direct Hourly Operating Cost for Incinerators 570
Figure 169 Capital Cost of Fabric Filters 571
Figure 170 Installed Cost of Fabric Filters 572
Figure 171 Annual Direct Operating Cost for Fabric Filters 573
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LIST OF TABLES
Page No.
Table 1 Proposed Table of Applications 5
Table 2 LA-Process Weight and Allowable Emissions 9
TableS Definition of "High Efficiency" Performance Level 10
Table 4 Conversion of Loadings from gr/ACF to gr/SCF 11
Table 5 City Cost Indices 14
Table 6 Average Hourly Labor Rates by Trade 15
Table 7 Weight of Inedible Waste from Slaughtered Livestock 18
Table 8 Composition of Typical Rendering Charge Materials 19
Table 9 Partial Chemical Composition of Rendered Animal
Byproducts 20
Table 10 Analysis of Condensate from the Dry Rendering of
Flesh in Fresh and Stale Conditions 27
Table 11 Sources of Odor in Rendering Plants 28
Table 12 Odor Concentrations and Emission Rates from
Inedible Reduction Processes 29
Table 13 Odor Removal Efficiencies for Condensers and
Condenser-Incinerator Combinations 35
Table 14 Scrubber Process Description for Rendering Cookers
and Hoods Specification 40
Table 15 Scrubber Operating Conditions for Rendering Cookers
and Hoods Specification 41
Table 16 Scrubber Process Description for Rendering Room
Vents Specification 42
Table 17 Scrubber Operating Conditions for Rendering Room
Vents Specification 43
Table 18 Scrubber Process Description for Combined Rendering
Vents Specification 44
Table 19 Scrubber Operating Conditions for Combined Rendering
Vents Specification 45
Table 20 Estimated Capital Cost Data for Wet Scrubbers for
Rendering Cookers and Hoods 46
Table 21 Annual Operating Cost Data for Wet Scrubbers for
Rendering Cookers and Hoods 47
Table 22 Estimated Capital Cost Data for Wet Scrubbers for
Rendering Room Vents 48
Table 23 Annual Operating Cost Data for Wet Scrubbers for
Rendering Room Vents 49
Table 24 Estimated Capital Cost Data for Wet Scrubbers for
Rendering Combined Vents 50
Table 25 Annual Operating Cost Data for Wet Scrubbers for
Rendering Combined Vents 51
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LIST OF TABLES (com.)
Page No.
Table 26 Incinerator Process Description for Rendering Cookers
and Hoods Specification 62
Table 27 Incinerator Operating Conditions for Rendering Cookers
and Hoods Specification 63
Table 28 Incinerator Process Description for Rendering Room
Vents Specification 66
Table 29 Incinerator Operating Conditions for Rendering Room
Vents Specification 67
Table 30 Incinerator Process Description for Rendering Combined
Vents Specification 68
Table 31 Incinerator Operating Conditions for Rendering Combined
Vents Specification 69
Table 32 Estimated Capital Cost Data for Incinerators for Rendering
Cookers and Hoods 70
Table 33 Annual Operating Cost Data for Incinerators for Rendering
Cookers and Hoods 71
Table 34 Estimated Capital Cost Data for Incinerators for Rendering
Room Vents 72
Table 35 Annual Operating Cost Data for Incinerators for Rendering
Room Vents 73
Table 36 Estimated Capital Cost Data for Incinerators for Rendering
Combined Vents 74
Table 37 Annual Operating Cost Data for Incinerators for Rendering
Combined Vents 75
Table 38 Installed Capacities of Three Types of Catalytic Cracking Units 84
Table 39 Schematic Representation of Cracking Reactions 84
Table 40 Typical Operating Conditions for a Medium-Size FCC Unit... 86
Table 41 Typical Properties of Fresh and Equilibrium FCC Catalysts. . . 86
Table 42 Operating Results — Fluid Catalytic Cracking Process 90
Table 43 Calculated Composition of Gas from FCC Regenerator
and CO Boiler 90
Table 44 Typical Contaminant Rates from FCC Unit Regenerators ... 94
Table 45 Emissions from FCC Regenerators 94
Table 46 Typical Properties of FCC Catalyst Fines 97
Table 47 Electrostatic Precipitator Process Description for
Fluidized Bed Catalytic Cracking Unit Specification . . . 102
Table 48 Electrostatic Precipitator Operating Conditions for
Fluidized Bed Catalytic Cracking Unit Specification ... 103
Table 49 Estimated Capital Cost Data for Electrostatic Precipitators
for FCC Units 104
Table 50 Annual Operating Cost Data for Electrostatic Precipitators
for FCC Units 105
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LIST OF TABLES (cont.)
Page No.
Table 51 Estimated Capital Cost Data for Tertiary Cyclones
for FCC Units 110
Table 52 Annual Operating Cost Data for Tertiary Cyclones
for FCC Units 111
Table 53 Particle Size Distribution Before and After Primary
Collection 127
Table 54 Fabric Filter Process Description for Asphalt Batching
Plant Specification 132
Table 55 Fabric Filter Operating Conditions for Asphalt Batching
Plant Specification 133
Table 56 Estimated Capital Cost Data for Fabric Collectors for
Asphalt Batching Plants 134
Table 57 Annual Operating Cost Data for Fabric Collectors for
Asphalt Batching Plants 135
Table 58 Wet Scrubber Process Description for Asphalt Batching
Plant Specification 140
Table 59 Wet Scrubber Operating Conditions for Asphalt Batching
Plant Specification 141
Table 60 Estimated Capital Cost Data for Wet Scrubbers for
Asphalt Batching Plants 142
Table 61 Annual Operating Cost Data for Wet Scrubbers for
Asphalt Batching Plants 143
Table 62 Electrostatic Precipitator Process Description for
Asphalt Batching Plant Specification 148
Table 63 Electrostatic Precipitator Operating Conditions for
Asphalt Batching Plant Specification 149
Table 64 Calculation of Oxygen Requirements for 100 Ton Melt 166
Table 65 Calculated Gas Composition for 100 Ton BOF Blown
at 12,000 SCFM 02 Rate for 20 Minutes 167
Table 66 Electrostatic Precipitator Process Description for BOF
Steelmaking Specification 177
Table 67 Electrostatic Precipitator Operating Conditions for BOF
Steelmaking Specification 180
Table 68 Estimated Capital Cost Data for Electrostatic Precipitators
for BOF Steelmaking 182
Table 69 Annual Operating Cost Data for Electrostatic Precipitators
for BOF Steelmaking 183
Table 70 Wet Scrubber Process Description for BOF Steelmaking
Specification 190
Table 71 Wet Scrubber Operating Conditions for BOF Steelmaking
Specification (Open Hood System) 192
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LIST OF TABLES (cont.)
Page No.
Table 72 Wet Scrubber Operating Conditions for BOF Steelmaking
Specification (Closed Hood System) 194
Table 73 Estimated Capital Cost Data for Wet Scrubbers for BOF
Steelmaking (Open Hood) 196
Table 74 Annual Operating Cost Data for Wet Scrubbers for BOF
Steelmaking (Open Hood) 197
Table 75 Estimated Capital Cost Data for Wet Scrubbers for BOF
Steelmaking (Closed Hood) 198
Table 76 Annual Operating Cost Data for Wet Scrubber Systems
for BOF Steelmaking (Closed Hood) 199
Table 77 Estimated Capital Cost Data for Wet Scrubbers for BOF
Steelmaking at Very High Efficiency (Open Hood) 207
Table 78 Estimated Capital Cost Data for Electrostatic Precipitators
for BOF Steelmaking at Very High Efficiency
(Open Hood) 208
Table 79 Coal Cleaning Methods and Corresponding Production Rates . 212
Table 80 Theoretical Combustion Products 220
Table 81 Calculated Heat Requirements for Coal Drying 221
Table 82 Gaseous Discharge From a Hypothetical 500 Ton/hr Dryer .. 222
Table 83 Wet Scrubber Process Description for Coal Cleaning
Specification 228
Table 84 Wet Scrubber Operating Conditions for Coal Cleaning
Specification 229
Table 85 Estimated Capital Cost Data for Wet Scrubbers for Coal
Cleaning Plants 232
Table 86 Annual Operating Cost Data for Wet Scrubbers for Coal
Cleaning Plants 233
Table 87 Breakdown Temperatures of Clay Impurities 242
Table 88 Temperatures Attained in Burning 243
Table 89 Chemical Formulation of Brickmaking Clays 246
Table 90 Some Naturally Occurring Impurities 247
Table 91 Calculated Composition of Combustion Products from
100 Ton/day Tunnel Kiln 248
Table 92 Wet Scrubber Process Description for Brick and Tile
Kiln Specification 256
Table 93 Wet Scrubber Operating Conditions for Brick and Tile
Kiln Specification 257
Table 94 Estimated Capital Cost Data for Wet Scrubbers for
Brick and Tile Kilns 258
Table 95 Annual Operating Cost Data for Wet Scrubbers for
Brick and Tile Kilns 259
Table 96 Thermal Incinerator Process Description for Brick and
Tile Kiln Specification 264
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LIST OF TABLES (cont.)
Page No.
Table 97 Thermal Incinerator Operating Conditions for Brick
and Tile Kiln Specification 265
Table 98 Estimated Capital Cost Data for Thermal Incinerators
for Brick and Tile Kilns 266
Table 99 Annual Operating Cost Data for Thermal Incinerators
for Brick and Tile Kilns 267
Table 100 Calculated Composition of Reverberatory Furnace Flue
Gas (from Coal Burning) 287
Table 101 Calculated Composition of Reverberatory Furnace Flue
Gas (from Gas Burning) 288
Table 102 Combined Gas Cleaning System Process Description for
Copper Roasting Furnace Specification 294
Table 103 Roaster Operating Conditions for Abatement Equipment .... 296
Table 104 Estimated Capital Cost Data for Combined Gas Cleaning
Systems for Copper Roasting Furnaces 298
Table 105 Annual Operating Cost Data for Combined Gas Cleaning
Systems for Roasting Furnaces 299
Table 106 Process Description for Copper Reverberatory Furnace
Electrostatic Precipitator Specification 302
Table 107 Operating Conditions for Copper Reverberatory Furnace
Electrostatic Precipitator Specification 303
Table 108 Estimated Capital Cost Data for Electrostatic Precipitators
for Copper Reverberatory Furnaces 304
Table 109 Annual Operating Cost Data for Electrostatic Precipitators
for Copper Reverberatory Furnaces 305
Table 110 Process Description for Copper Reverberatory Furnace
Wet Scrubber Specification 308
Table 111 Operating Conditions for Copper Reverberatory Furnace
Wet Scrubber Specification 309
Table 112 Estimated Capital Cost Data for Wet Scrubbers for Copper
Reverberatory Furnaces , 312
Table 113 Annual Operating Cost Data for Wet Scrubber for Copper
Reverberatory Furnaces 313
Table 114 Exhaust Gas Composition 326
Table 115 Summary of Tests on Bark Boiler Tubular Collectors 327
Table 116 Electrostatic Precipitator Process Description for Kraft Mill
Bark Boiler Specification 334
Table 117 Electrostatic Precipitator Operating Conditions for Bark
Boiler Specification 335
Table 118 Estimated Capital Cost Data for Electrostatic Precipitators
for Bark Boilers 336
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LIST OF TABLES (cont.)
Page No.
Table 119 Annual Operating Cost Data for Electrostatic Precipitators
for Bark Boilers
Table 120 Wet Scrubber Process Description for Kraft Mill
Bark Boiler Specification
Table 121 Wet Scrubber Operating Conditions for Bark Boiler
Specification
Table 122 Estimated Capital Cost Data for Wet Scrubbers for Bark
Boilers
Table 123 Annual Operating Cost Data for Wet Scrubbers for Bark
Boilers
Table 124 Compositions of Typical Ferroalloys
Table 125 Weight Balance for Production of 45% Ferrosilicon
Table 126 Comparison of Gas Flows from Open and Closed Hood 50 mw
Submerged Arc Furnaces Making 50% Ferrosilicon
Table 127 Weight Balance for Production of Low Carbon Ferrochrome .
Table 128 Properties of Particulate Emissions from Ferroalloy
Furnaces
Table 129 Distribution of Domestic Ferroalloy Furnaces
Table 130 Fabric Filter Process Description for Ferrosilicon
Furnace Specification
Table 131 Fabric Filter Operating Conditions for Ferrosilicon
Furnace Specification
Table 132 Estimated Capital Cost Data for Fabric Filters for
Ferrosilicon Furnaces
Table 133 Annual Operating Cost Data for Fabric Filters for
Ferrosilicon Furnaces
Table 134 Fabric Filter Process Description for Ferrochrome
Furnace Specification
Table 135 Fabric Filter Operating Conditions for Ferrochrome
Furnace Specification
Table 136 Estimated Capital Cost Data for Fabric Filters for
Ferrochrome Furnaces
Table 137 Annual Operating Cost Data for Fabric Filters for
Ferrochrome Furnaces
Table 138 Electrostatic Precipitator Process Description for
Ferrosilicon Furnace Specification
Table 139 Electrostatic Precipitator Operating Conditions for
Ferrosilicon Furnace Specification
Table 140 Electrostatic Precipitator Process Description for
Ferrochrome Furnace Specification
337
340
341
342
343
351
358
359
360
362
365
368
369
370
371
374
375
376
377
380
381
382
-------
LIST OF TABLES (cont.)
Page No.
Table 141 Electrostatic Precipitator Operating Conditions for
Ferrochrome Furnace Specification 383
Table 142 Wet Scrubber Process Description for Ferrosilicon
Furnace Specification 384
Table 143 Wet Scrubber Operating Conditions for Ferrosilicon
Furnace Specification 385
Table 144 Estimated Capital Cost Data for Wet Scrubbers for
Ferrosilicon Furnaces 386
Table 145 Annual Operating Cost Data for Wet Scrubbers for
Ferrosilicon Furnaces 387
Table 146 Wet Scrubber Process Description for Ferrochrome
Furnace Specification 390
Table 147 Wet Scrubber Operating Conditions for Ferrochrome
Furnace Specification 391
Table 148 Estimated Capital Cost Data for Wet Scrubbers for
Ferrochrome Furnaces 392
Table 149 Annual Operating Cost Data for Wet Scrubbers for
Ferrochrome Furnaces 393
Table 150 Computer Program for Cost Indices Calculations 402
Table 151 Units of Plant Size for Each Process Area 404
Table 152 Derived Cost Indices for Wet Scrubbers for
Rendering Cookers 405
Table 153 Derived Cost Indices for Wet Scrubbers for
Rendering Room Vents 406
Table 154 Derived Cost Indices for Wet Scrubbers for
Rendering Combined Vents 407
Table 155 Derived Cost Indices for Incinerators for
Rendering Cookers 408
Table 156 Derived Cost Indices for Incinerators for
Rendering Room Vents 409
Table 157 Derived Cost Indices for Incinerators for
Rendering Combined Vents 410
Table 158 Derived Cost Indices for Precipitators for FCC Units 411
Table 159 Derived Cost Indices for Cyclones for FCC Units 412
Table 160 Derived Cost Indices for Fabric Filters for
Asphalt Batching 413
Table 161 Derived Cost Indices for Wet Scrubbers for
Asphalt Batching 414
Table 162 Derived Cost Indices for Precipitators for BOF
Steelmaking 415
-------
LIST OF TABLES (cont.)
Page No.
Table 163 Derived Cost Indices for Wet Scrubbers (Open Hood)
for EOF Steelmaking 416
Table 164 Derived Cost Indices for Wet Scrubbers (Closed Hood)
for BOF Steelmaking 417
Table 165 Derived Cost Indices for Wet Scrubbers for
Coal Cleaning 418
Table 166 Derived Cost Indices for Wet Scrubbers for
Brick and Tile Kilns 419
Table 167 Derived Cost Indices for Incinerators for
Brick and Tile Kilns 420
Table 168 Derived Cost Indices for Combined System for
Copper Roasting Furnaces 421
Table 169 Derived Cost Indices for precipitators for
Copper Reverberatory Furnaces 422
Table 170 Derived Cost Indices for Wet Scrubbers for
Copper Reverberatory Furnaces 423
Table 171 Derived Cost Indices for Precipitators for Bark Boilers 424
Table 172 Derived Cost Indices for Wet Scrubbers for Bark Boilers 425
Table 173 Derived Cost Indices for Fabric Filters for
Ferrosilicon Furnaces 426
Table 174 Derived Cost Indices for Fabric Filters for
Ferrochrome Furnaces 427
Table 175 Derived Cost Indices for Wet Scrubbers for
Ferrosilicon Furnaces 428
Table 176 Derived Cost Indices for Wet Scrubbers for
Ferrochrome Furnaces 429
Table 177 Derived Cost Per SCFM for Wet Scrubbers for
Rendering Cookers 430
Table 178 Derived Cost Per SCFM for Wet Scrubbers for
Rendering Room Vents 431
Table 179 Derived Cost Per SCFM for Wet Scrubbers for
Rendering Combined Vents 432
Table 180 Derived Cost Per SCFM for Incinerators for
Rendering Cookers 433
Table 181 Derived Cost Per SCFM for Incinerators for
Rendering Room Vents 434
Table 182 Derived Cost Per SCFM for Incinerators for
Rendering Combined Vents 435
Table 183 Derived Cost Per SCFM for Precipitators for FCC Units 435
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LIST OF TABLES (cont.)
Page No.
Table 184 Derived Cost Per SCFM for Cyclones for FCC Units 437
Table 185 Derived Cost Per SCFM for Fabric Filters for
Asphalt Batching 438
Table 186 Derived Cost Per SCFM for Wet Scrubbers for
Asphalt Batching 439
Table 187 Derived Cost Per SCFM for Precipitators for BOF
Steelmaking 440
Table 188 Derived Cost Per SCFM for Wet Scrubbers (Open Hood) for
BOF Steelmaking 441
Table 189 Derived Cost Per SCFM for Wet Scrubbers (Closed Hood) for
BOF Steelmaking 442
Table 190 Derived Cost Per SCFM for Wet Scrubbers for Coal Cleaning . 443
Table 191 Derived Cost Per SCFM for Wet Scrubbers for
Brick and Tile Kilns 444
Table 192 Derived Cost Per SCFM for Incinerators for
Brick and Tile Kilns 445
Table 193 Derived Cost Per SCFM for Combined Systems for
Copper Roasting Furnaces 446
Table 194 Derived Cost Per SCFM for Precipitators for
Copper Reverberatory Furnaces 447
Table 195 Derived Cost Per SCFM for Wet Scrubbers for
Copper Reverberatory Furnaces 448
Table 196 Derived Cost Per SCFM for Precipitators for Bark Boilers .... 449
Table 197 Derived Cost Per SCFM for Wet Scrubbers for Bark Boilers . . 450
Table 198 Derived Cost Per SCFM for Fabric Filters for
Ferrosilicon Furnaces 451
Table 199 Derived Cost Per SCFM for Fabric Filters for
Ferrochrome Furnaces 452
Table 200 Derived Cost Per SCFM for Wet Scrubbers for
Ferrosilicon Furnaces 453
Table 201 Derived Cost Per SCFM for Wet Scrubbers for
Ferrochrome Furnaces 454
Table 202 Various Values for Unit Operating Costs , 456
Table 203 Annual Operating Cost Data for Wet Scrubbers for
Rendering Cookers and Hoods (Low Unit Cost) 457
Table 204 Annual Operating Cost Data for Wet Scrubbers for Rendering
Cookers and Hoods (High Unit Cost) 458
Table 205 Annual Operating Cost Data for Wet Scrubbers for Rendering
Room Vents (Low Unit Cost) 461
Table 206 Annual Operating Cost Data for Wet Scrubbers for Rendering
Room Vents (High Unit Cost) 462
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LIST OF TABLES (cont.)
Page No.
Table 207 Annual Operating Cost Data for Wet Scrubbers for Rendering
Combined Vents (Low Unit Cost)
Table 208 Annual Operating Cost Data for Wet Scrubbers for Rendering
Combined Vents (High Unit Cost)
Table 209 Annual Operating Cost Data for Incinerators for Rendering
Cookers and Hoods (Low Unit Cost)
Table 210 Annual Operating Cost Data for Incinerators for Rendering
Cookers and Hoods (High Unit Cost)
Table 211 Annual Operating Cost Data for Incinerators for Rendering
Room.Vents (Low Unit Cost) ,
Table 212 Annual Operating Cost Data for Incinerators for Rendering
Room Vents (High Unit Cost) ,
Table 213 Annual Operating Cost Data for Incinerators for Rendering
Combined Vents (Low Unit Cost)
Table 214 Annual Operating Cost Data for Incinerators for Rendering
Combined Vents (High Unit Cost)
Table 215 Annual Operating Cost Data for Electrostatic Precipitators
for FCC Units (Low Unit Cost)
Table 216 Annual Operating Cost Data for Electrostatic Precipitators
for FCC Units (High Unit Cost)
Table 217 Annual Operating Cost Data for Tertiary Cyclones for
FCC Units (Low Unit Cost)
Tab'e 218 Annual Operating Cost Data for Tertiary Cyclones for
FCC Units (High Unit Cost)
Table 219 Annual Operating Cost Data for Fabric Collectors
for Asphalt Batching Plants (Low Unit Cost)
Table 220 Annual Operating Cost Data for Fabric Collectors
for Asphalt Batching Plants (High Unit Cost)
Table 221 Annual Operating Cost Data for Wet Scrubbers for Asphalt
Batching Plants (Low Unit Cost)
Table 222 Annual Operating Cost Data for Wet Scrubbers for Asphalt
Batching Plants (High Unit Cost)
Table 223 Annual Operating Cost Data for Electrostatic Precipitators
for BOF Steelmaking (Low Unit Cost)
Table 224 Annual Operating Cost Data for Electrostatic Precipitators
for BOF Steelmaking (High Unit Cost)
Table 225 Annual Operating Cost Data for Wet Scrubber Systems
(Open Hood) for BOF Steelmaking (Low Unit Cost)
Table 226 Annual Operating Cost Data for Wet Scrubber Systems
(Open Hood) for BOF Steelmaking (High Unit Cost)
465
466
469
470
473
474
477
478
481
482
485
486
489
490
493
494
497
498
503
504
-------
LIST OF TABLES (cont.)
Page No.
Table 227 Annual Operating Cost Data for Wet Scrubber Systems
(Closed Hood) for BOF Steelmaking (Low Unit Cost) . . 507
Table 228 Annual Operating Cost Data for Wet Scrubber Systems
(Closed Hood) for BOF Steelmaking (High Unit Cost) . . 508
Table 229 Annual Operating Cost Data for Wet Scrubbers for Coal
Cleaning Plants (Low Unit Cost) 511
Table 230 Annual Operating Cost Data for Wet Scrubbers for Coal
Cleaning Plants (High Unit Cost) 512
Table 231 Annual Operating Cost Data for Wet Scrubbers for
Brick and Tile Kilns (Low Unit Cost) 517
Table 232 Annual Operating Cost Data for Wet Scrubbers for
Brick and Tile Kilns (High Unit Cost) 518
Table 233 Annual Operating Cost Data for Thermal Incinerators for
Brick and Tile Kilns (Low Unit Cost) 521
Table 234 Annual Operating Cost Data for Thermal Incinerators for
Brick and Tile Kilns (High Unit Cost) 522
Table 235 Annual Operating Cost Data for Combined Gas Cleaning Systems
for Copper Roasting Furnaces (Low Unit Cost) 525
Table 236 Annual Operating Cost Data for Combined Gas Cleaning Systems
for Copper Roasting Furnaces (High Unit Cost) 526
Table 237 Annual Operating Cost Data for Electrostatic Precipitators
for Copper Reverberatory Furnaces (Low Unit Cost) ... 529
Table 238 Annual Operating Cost Data for Electrostatic Precipitators
for Copper Reverberatory Furnaces (High Unit Cost) . . . 530
Table 239 Annual Operating Cost Data for Wet Scrubbers for Copper
Reverberatory Furnaces (Low Unit Cost) 533
Table 240 Annual Operating Cost Data for Wet Scrubbers for Copper
Reverberatory Furnaces (High Unit Cost) 534
Table 241 Annual Operating Cost Data for Electrostatic Precipitators
for Bark Boilers (Low Unit Cost) 537
Table 242 Annual Operating Cost Data for Electrostatic Precipitators
for Bark Boilers (High Unit Cost) 538
Table 243 Annual Operating Cost Data for Wet Scrubbers for
Bark Boilers (Low Unit Cost) 541
Table 244 Annual Operating Cost Data for Wet Scrubbers for
Bark Boilers (High Unit Cost) 542
Table 245 Annual Operating Cost Data for Fabric Filters for
Ferrosilicon Furnaces (Low Unit Cost) 545
Table 246 Annual Operating Cost Data for Fabric Filters for
Ferrosilicon Furnaces (High Unit Cost) 546
-------
LIST OF TABLES (cont.)
Page No.
Table 247 Annual Operating Cost Data for Fabric Filters for
Ferrochrome Furnaces (Low Unit Cost) 549
Table 248 Annual Operating Cost Data for Fabric Filters for
Ferrochrome Furnaces (High Unit Cost) 550
Table 249 Annual Operating Cost Data for Wet Scrubbers for
Ferrosilicon Furnaces (Low Unit Cost) 553
Table 250 Annual Operating Cost Data for Wet Scrubbers for
Ferrosilicon Furnaces (High Unit Cost) 554
Table 251 Annual Operating Cost Data for Wet Scrubbers for
Ferrochrome Furnaces (Low Unit Cost) 557
Table 252 Annual Operating Cost Data for Wet Scrubbers for
Ferrochrome Furnaces (High Unit Cost) 558
-------
LIST OF APPENDICES
Appendix I Process Weight Regulation (Rule 54, Air Pollution
Control District of Los Angeles County)
Appendix II Instructions for Submitting Cost Data
Appendix 111 Complete Sample Specification
Appendix IV Statistical Basis for Data Presentation
-------
I. INTRODUCTION
The Industrial Gas Cleaning Institute (IGCI) is an association of
manufacturers of industrial gas cleaning equipment. Under this contract,
members of the IGCI collected and formalized information on air pollution
control for sixteen processes in nine industrial areas:
1. Rendering
2. Asphalt Batch Plants
3. Petroleum Refining
4. BOF Steelmaking
5. Coal Cleaning
6. Brick and Tile Kilns
7. Primary Copper Smelting
8. Kraft Pulp Industry Bark Boilers
9. Ferroalloy Furnaces
This report includes a completed narrative description of each area,
describing the processes and air pollution abatement methods in use. In
addition, specifications for abatement equipment have been written for large
and small processes, and for two levels of air pollution control. These
specifications were submitted to three member companies active in furnishing
equipment to the industry involved. The capital and operating cost data
prepared for each process were summarized and average costs are included in
this report.
In addition, correlations were made between process size, gas flow and
abatement cost where meaningful relationships appeared to exist.
-------
II. TECHNICAL DATA
This section contains all of the data collected relative to process
descriptions, air pollution requirements, specifications and capital and
operating costs for abatement equipment. Narrative material was generated by
the combined efforts of Air Resources, Inc. personnel acting as editors and
coordinators for the program, and the most qualified personnel of the member
companies active in the field. The cost data, however, is entirely the product of
the member companies judged most qualified. These companies prepared cost
estimates independently of one another. Air Resources, Inc. consolidated the
data and edited it with regard to format only.
A. General Description
The format chosen for presentation of the material collected groups all of
the information pertaining to a given industrial area in a single section of the
report. The final summary section describes the findings in general terms, and
contains generalizations of cost factors common to all the areas covered.
1. FORMAT
There are nine sections, each covering one of the industrial areas. For each
area, the following format is used:
1. Description of the Process
a. Manufacturing or Production Aspects
b. Air Pollution Control Equipment
2. Specifications and Costs
a. Electrostatic Precipitators
(1) Specifications
(2) Capital Costs
(3) Operating Costs
-------
b. Wet Scrubbers
c. Fabric Collectors
d. Other
3. Summary Comments
This material is not presented in outline form, nor is each item necessarily
included for each process area.
2. SELECTION OF APPLICABLE EQUIPMENT TYPES
Most of the processes covered by this report require abatement devices for
the control of particulate emission. These devices include:
Electrostatic Precipitators
Wet Scrubbers
Fabric Collectors
Mechanical (Cyclonic) Collectors
One of the processes — rendering — has little need for particulate control,
but requires instead the removal of a variety of gaseous materials which give
rise to local odor nuisance problems. The devices used for gaseous emission
control are:
Wet Scrubbers
Incinerators
Adsorption Units
In general, a given process is amenable to control by one or more of the
equipment types, but seldom by all of them. For this reason, a meeting of the
Engineering Standards Committee of the Industrial Gas Cleaning Institute was
held early in the program for the purpose of selecting the equipment types
applicable to each process.
-------
The results of this selection for all nine areas are presented in Table 1.
There were several changes in the definition of applicable equipment types
after the initial selection. These are made as evidence emerged during the
preparation of narratives that a particular process was amenable to control by
equipment not previously considered applicable or was not ordinarily
controlled by one of the equipment types listed. The changes are discussed in
the following paragraphs.
Rendering emissions were considered amenable to control by absorption
(wet scrubbing with chemical oxidation of the organic odor precursors) or
thermal incineration. The third method of emission control - adsorption - was
ruled out because of the presumption that activated carbon or other adsorption
beds would plug with the heavier grease-like organic compounds. It was found
that one of the companies active in the field has used a combination scrubbing
carbon adsorption system for cooker applications. Data on costs for this
combination system are presented, but Table 1 does not show adsorption
(alone) as a suitable method of control.
Asphalt Batch Plants were considered amenable to control by all three
types of particulate control equipment, but electrostatic precipitators were
omitted from Table 1 initially because most batch plants are relatively small in
terms of gas flow, and usually below the size range in which precipitators are
economically applied. However, it was learned during the course of the study
that one of the member companies has provided a number of small
precipitators for batch plants. In view of this, precipitators were added, and
specifications written. Only one company has supplied precipitators for the
asphalt industry, however, and no comparative cost data is included.
Petroleum Refining was considered amenable to control by wet scrubbers
and precipitators, but no installations of wet scrubbers have been made in the
U.S., so they were deleted. However, it was found that mechanical collectors
used as "final stage external cyclones" do satisfy most air pollution
requirements for plants with normal emission levels, and these were permitted
as alternatives to the electrostatic precipitator where they would meet the
performance specifications.
BOF Steelmaking was presumed amenable to treatment by wet scrubbers
and precipitators, and this was not changed during the course of the program.
Closed hood systems were assumed to be limited to wet scrubbing because of
the combustion hazard with precipitators.
-------
TABLE 1
PROPOSED TABLE OF APPLICATIONS
(1) Rendering
(a) Cookers
(b) Expellers
(c) Room Vents
(2) Petroleum Refining
(3) Asphalt Batching
(4) BOF Steel Making
(a) With CO Burning
(b) Without CO Burning
(5) Coal Cleaning
(a) Fluidized Bed Dryer
(b) Flash Dryer
(6) Brick and Tile
(7) Copper Smelting
(a) Reverb., no S02 Control
(b) Reverb., with SO2 Control
(c) Converter (or Roaster)
(8) Kraft Mill Bark Boilers
(9) Ferroalloy Furnaces
(a) Ferrosilicon
(b) Ferrochrome
Elect. Fabric
X
X* X
X
X**
X**
X X**
X**
X X**
X
X*** X
X*** X
Incin-
Wet erator
X X
X X
X X*
X
X
X
X
X**
X X
X
X
X
X
X
Total
Applies
tions
2
2
2
1
3
2
1
1
2
2
2
2
3
3
"These were added during the course of the program.
**These were deleted during the course of the program.
***These were retained through specification writing, but no equipment bids
were obtained.
-------
Coal Cleaning was originally described as controlled by both fabric
collectors and wet scrubbers. Current practice is limited to wet scrubbers,
however. This is related to the difficulty in treating nearly saturated gas streams
with fabric collectors. For this reason, fabric collectors were deleted from this
section of the study.
Brick and Tile Kilns emit contaminants only when materials such as
sulfur, fluorine or organics are present in the clay. Wet scrubbing is the method
used for removal of SC>2 and HF, while incineration is useful for removing
smoke produced by combustibles in the clay.
Copper Smelting was modified substantially. It was found that no
reverberatory furnaces are being treated with fabric collectors so this category
was deleted. In addition, no reverberatory furnaces with SC>2 control were
found, so this entire category was dropped. Lastly, the roasting furnace was
substituted for the converter to obtain costs for conditioning gas to be fed to a
sulfuric acid plant.
Kraft Mill Bark Boilers have been treated by both electrostatic
precipitators and wet scrubbers. This was not altered during the course of the
program.
Ferroalloy Furnaces are difficult to treat adequately, but all three
methods have been applied with some degree of success. All three were
included at the beginning of the program but only fabric collection was found
to be suitable for both types of operation.
3. BASIS FOR SPECIFICATIONS
The degree of reduction of emissions required in a given application will
influence the cost significantly for wet scrubbers and electrostatic precipitators.
Fabric filters, mechanical collectors and thermal incinerators are, on the other
hand, relatively insensitive to the efficiency level specified. In all cases, the cost
is directly related to size or gas handling capacity required.
In order to make a meaningful comparison of capital and operating costs,
it is necessary to specify the performance level, or degree of reduction of
emissions required. For this project, two arbitrary levels of performance were
specified:
a) An "intermediate level" which corresponds to the Los Angeles
County Air Pollution Control District process weight requirements, and
-------
b) A "high level" of performance which should show little or no
subjective evidence of emissions; that is no visible paniculate matter, and no
detectable odor level.
These levels are arbitrary and should not be used as guides to selection of
abatement equipment without a good understanding of the local requirements
and any special conditions affecting the emissions from the process.
The LA-Process Weight Specification is typical of many such ordinances
throughout the country. It is based on an allowable emission of particulate
matter which increases with process feed rate. However, the allowable emission
rate in pounds per hour of particulate increases more slowly than does the feed
rate to the process. Because the emission produced in most processes is
proportional to the feed rate, the particulate collection efficiency must be
higher for large processes than for small ones. The law also specifies an absolute
maximum of 40 Ib/hr of particulate matter, regardless of process size, so that
very large process units must have very efficient collection devices. Many of the
processes covered by this study are relatively small in terms of total feed rate,
and the 40 Ib/hr maximum emission level will not be applicable. Others such as
catalytic cracking units and BOF furnaces normally operate at high process
weights and have a 40 Ib/hr emission limit.
A list of allowable emission rates under the LA—Process Weight regulation
is given in Table 2. A more detailed version of Rule 54 of the Air Pollution
Control District of Los Angeles County is given in Appendix I. This rule was
modified during the course of the contract, and the version in effect on July 1,
1971 has been used throughout.
In general, this type of regulation is easy to interpret and leads to definite,
clear-cut levels of performance required for air pollution control systems,
provided the rate at which particulate matter is generated by the process and
the process feed rate (or process weight) are known. The particulate emission
rate is best obtained by direct measurement by a qualified source test engineer
or company if the process is an existing one, or obtained from the
manufacturer of the furnace or kiln if the installation is in the planning stage.
The process weight is the sum of all of the feed materials to the process,
excluding air and liquid or gaseous fuels. The process weight ordinarily exceeds
the rated product capacity of the equipment because it includes output
product, plus losses and byproducts.
The second specification included for each of the air pollution control
systems covered by this report is called the "High Efficiency" case. This is
taken as an arbitrary stack grain loading (concentration of particulate matter,
-------
measured in grains per actual cubic foot) which should produce an effluent
with little or no visible opacity, excluding that due to water. This grain loading
is based on the best judgment of the members of the IGCI Engineering
Standards Committee. The levels specified are arbitrary, and while most
member companies will guarantee performance to the grain loading specified,
they will not ordinarily represent or guarantee freedom from visible emissions.
(Exceptions to this rule exist. A manufacturer may have an identical
installation known to produce a color-free effluent and be willing to guarantee
performance on this basis.) Table 3 lists the values assigned by the Engineering
Standards Committee to this "High Efficiency" case.
It should be noted that the experience of the member companies over a
period of many years has been drawn upon to establish the grain loading figures
indicated. Although there has been no single standardized test method used in
the past, the methods prescribed by the American Society of Mechanical
Engineers and embodied in Power Test Codes 21 and 27 have had the widest
use. The "High Efficiency" grain loadings may be presumed to relate to these
methods more closely than to others such as the recently developed "EPA
sampling train", (Test Method No. 5, Federal Register 12/23/71).
Table 3 shows loadings in gr/ACF because these should correlate better
with visibility of the discharge than gr/SCF. Most frequently the measured
emissions are reported in gr/SCF and the conversion to gr/ACF should not be
overlooked. In order to make this easier. Table 4 has been prepared. This lists
various levels of emission in terms of gr/ACF in the left-hand column, and
corresponding values of gr/SCF at various stack temperatures.
For the case of rendering equipment, the particulate emission standards
do not apply and a basis for odor emission was defined by the committee and
reviewed with the Project Officer. This basis is described in the following
paragraph.
High efficiency performance has been defined as that which shows little or
no subjective evidence of emission. For rendering, the equivalent of a clear
stack is an undetectable odor. For this reason the "High Efficiency" level was
defined as 1.0 or less odor units at ground level. The Coordinating Engineer
specified the stack height and abatement level required to accomplish this. The
"LA-Process Weight" does not apply to odors. In order to accomplish the
equivalent of this specification, the use of 8.0 o.u./SCF max. at ground level
was agreed upon.
-------
TABLE 2
LA-PROCESS WEIGHT AND ALLOWABLE EMISSION
* Process
Wt/hr(lbs)
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
2600
2700
2800
2900
3000
3100
3200
3300
Maximum Weight
Disch/hr(lbs)
.24
.46
.66
.85
1.03
1.20
1.35
1.50
1.63
1.77
1.89
2.01
2.12
2.24
2.34
2.43
2.53
2.62
2.72
2.80
2.97
3.12
3.26
3.40
3.54
3.66
3.79
3.91
4.03
4.14
4.24
4.34
4.44
4.55
4.64
4.74
4.84
4.92
5.02
5.10
5.18
5.27
5.36
* Process
Wt/hr(lbs)
3400
3500
3600
3700
3800
3900
4000
4100
4200
4300
4400
4500
4600
4700
4800
4900
5000
5500
6000
6500
7000
7500
8000
8500
9000
9500
10000
12000
13000
14000
15000
16000
17000
18000
19000
20000
30000
40000
50000
60000
or
more
Maximum Weight
Disch/hr(lbs)
5.44
5.52
5.61
5.69
5.77
5.85
5.93
6.01
6.08
6.15
6.22
6.30
6.37
6.45
6.52
6.60
6.67
7.03
7.37
7.71
8.05
8.39
8.71
9.03
9.36
9.67
10.63
11.28
11.89
12.50
13.13
13.74
14.36
14.97
15.58
16.19
22.22
28.3
34.3
40.0
"See Definition in Rule 2fj) (Reproduced in Appendix I)
-------
TABLE 3
DEFINITION OF "HIGH EFFICIENCY" PERFORMANCE LEVEL
Collector
Outlet Concentration
(1) Rendering 1.0 o.u.*/SCF max. instantaneous
ground level value (8.0 o.u,/SCF
max. instantaneous ground level =
low efficiency)
(2) Petroleum Refining
Cat Crackers 0.015 gr/ACF
(3) Asphalt Batch Plants 0.03 gr/ACF
(4) Coal Dryers 0.03 gr/ACF
(5) Brick and Tile Kilns 0.005 gr/ACF (for
organic particulate)
(6) Copper Smelting
Reverberatory without S02 Control 0.015 gr/ACF
Convenors 0.01 gr/ACF
(7) Kraft Bark Boilers 0.04 gr/ACF
(8) Basic Oxygen Furnaces 0.01 gr/ACF
(9) Ferroalloy Furnaces 0.01 gr/ACF
*"o.u." is the abbreviation for odor unit, or the concentration of an odor
precursor just high enough to bring the odor of one SCF of air to the
detectable threshold.
10
-------
TABLE 4
CONVERSION OF LOADINGS FROM gr/ACF to gr/SCF*
gr/ACF
gr/SCF
0.005
0.0075
0.01
0.015
0.02
0.025
0.03
0.035
0.04
70
0.005
0.0075
0.01
0.015
0.02
0.025
0.03
0.035
0.04
100
0.0053
0.0079
0.011
0.016
0.021
0.026
0.032
0.037
0.042
Temperature, °F
200 300
0.0062
0.0093
0.012
0.019
0.025
0.031
0.037
0.044
0.050
0.0072
0.011
0.014
0.021
0.029
0.036
0.043
0.050
0.057
400
0.0081
0.012
0.016
0.024
0.032
0.041
0.049
0.057
0.065
500
0.009
0.014
0.018
0.027
0.036
0.045
0.054
0.063
0.073
600
0.010
0.015
0.020
0.030
0.040
0.050
0.060
0.070
0.080
*Based upon 70° F, 14.7 psia standard conditions and presumption that
emission is also at 14.7 psia. The SCF, as used here, has the same water vapor
content as the ACF. This should not be confused with the dry standard
volume, or DSCF.
11
-------
BASIS FOR PREPARING SPECIFICATIONS AND BID PRICES
Several simplifications were made in the preparation of the specifications
which have some bearing on the results which are reported here. These should
be kept in mind when using the prices, operating costs, etc.
The form of the specification for equipment may have an influence over
the price quoted. Overly-restrictive specifications may add 5 10% to the
equipment price without a corresponding increase in value received by the
purchaser. In each of the cases presented in this report, prices are based on a
specification which covers most of the conditions of purchase in an equitable
way. Instead of writing each specification independently, the participants
agreed upon the general terms and conditions to be specified, and these
conditions were made identical for each specification. The final specification in
each case was made by inserting one page of descriptive material and one page
of operating conditions pertaining to the specific application into the standard
format. To avoid unnecessary repetition, a sample of the complete specification
for one of the six applications is included as Appendix III to this report. Only
the pages pertinent to specific applications are contained in the body of the
report.
Prices were requested in such a way as to indicate three bases:
(a) Air pollution control device. This includes only the flange-to-flange
precipitator, fabric collector, or scrubber.
(b) Air pollution control system equipment. This includes major items
such as fans, pumps, etc.
(c) Complete turnkey installation. This includes the design, all materials
and equipment and startup.
In order to maintain a consistent approach to quoting in each area, the
specifications were written around the air pollution control device. The process
description was, however, made general enough to allow the members to quote
on the auxiliary equipment, such as fans, pumps, solid handling devices, etc.,
and to quote on an approximate installation cost. A complete set of
instructions for preparing specifications and for quoting is given in Appendix
Labor costs are a variable from one location to another, and it was not
possible to establish the complex pattern of variations in turnkey prices which
occurs as a function of local variations in hourly rate, productivity and
availability of construction tradesmen. In order to provide a consistent basis for
12
-------
the preparation of price quotations, the cost indices given in Table 5 were used.
This was taken from "Building Construction Cost Data, 1970".* This gives a
construction cost index for 90 cities, using 100 to represent the national
average. These figures are for the building trades, but they should be
representative of field construction rates in general.
These figures do not take productivity differences into account and may
understate the variations in cost from one city to another.
The participating companies were instructed to estimate the installation
costs as though erection or installation of the system would be in Milwaukee,
Wisconsin or another city relatively convenient to the participants point of
shipment with a labor rate near 100. Readers are cautioned to take local labor
rates and productivity into account when making first estimates of air pollution
control system installed costs based on the data in this report. Table 6 shows
the tabulated hourly rates for various construction trades (based on national
averages) which may be useful for this purpose.*
Considerable emphasis was placed on estimation of operating costs.
Manufacturers submitting costs for equipment were asked to estimate the
operating costs in terms of utility requirements, maintenance and repair labor,
and operating labor. These were requested in terms of the quantity required,
rather than the cost. This is because the costs will be analyzed in terms of low,
average and high utility and labor cost areas for the final report. For this
report, only the average utility costs given below were used for preparing total
annual cost figures.
4. PRESENTATION OF DATA
Capital cost data is presented as a series of three graphs which relate the
capital cost of the air pollution abatement device, the total equipment, and the
complete "turnkey" system respectively to plant size or exhaust gas rate.
Where it was possible, an analysis was made of the confidence limits of the
sample — three quotations from perhaps 20 possible suppliers. Appendix IV
contains a description of the mathematical procedure involved.
Operating costs are also presented in graphical form. A total annual cost
has been calculated for each process by combining an annual capital charge
with a direct annual operating cost. The resulting figures are presented as a
graph of total annual cost versus plant size or exhaust gas rate. Section C
includes a more detailed discussion of the basis for presentation of this data.
Both capital and operating cost data are presented in 1971 dollars
throughout the report.
'Published by the Robert Snow Means Company
13
-------
TABLE 5
CITY COST INDICES
Average 1969 Construction Cost & Labor Indices
City
Albany, N.Y.
Albuquerque, N.M.
Amarillo, Tx.
Anchorage, Ak.
Atlanta, Ga.
Baltimore, Md.
Baton Rouge, La.
Birmingham, Al.
Boston, Ma.
Bridgeport, Ct.
Buffalo, N.Y.
Burlington, Vt.
Charlotte, N.C.
Chattanooga, Tn.
Chicago, III.
Cincinnati, Oh.
Cleveland, Oh.
Columbus, Oh.
Dallas, Tx.
Dayton, Oh.
Denver, Co.
Des Moines, la.
Detroit, Mi.
Edmonton, Cn.
El Paso, Tx.
Erie, Pa.
Evansville, In.
Grand Rapids, Mi.
Harrisburg, Pa.
Hartford, Ct.
Honolulu, Hi.
Houston, Tx.
Indianapolis, In.
Jackson, Ms.
Jacksonville, Fl.
Kansas City, Mo.
Knoxville, Tn.
Las Vegas, Nv.
Little Rock, Ar.
Los Angeles, Ca.
Louisville, Ky.
Madison, Wi.
Manchester, N.H.
Memphis, Tn.
Miami, Fl.
Index
Labor
98
86
87
131
88
90
83
79
106
104
104
86
70
81
107
108
121
106
86
100
94
93
117
80
77
98
93
103
90
104
99
92
97
73
78
94
82
115
78
113
92
95
89
83
98
Total
100
95
84
148
94
93
88
86
103
102
107
90
75
84
103
104
112
99
89
103
91
96
111
83
83
99
97
99
92
100
109
89
98
75
79
93
82
107
81
102
93
98
92
82
94
City
Milwaukee, Wi.
Minneapolis, Mn.
Mobile, Al.
Montreal, Cn.
Nashville, Tn.
Newark, N.J.
New Haven, Ct.
New Orleans, La.
New York, N.Y.
Norfolk, Va.
OklahomaCity.Ok.
Omaha, Nb.
Philadelphia, Pa.
Phoenix, Az.
Pittsburgh, Pa.
Portland, Me.
Portland, Or.
Providence, R.I.
Richmond, Va.
Rochester, N.Y.
Rockford, III.
Sacramento, Ca.
St. Louis, Mo.
Salt Lake City, Ut.
San Antonio, Tx.
San Diego, Ca.
San Francisco, Ca.
Savannah, Ga.
Scranton, Pa.
Seattle, Wa.
Shreveport, La.
South Bend, In.
Spokane, Wa.
Springfield, Ma.
Syracuse, N.Y.
Tampa, Fl.
Toledo, Oh.
Toronto, Cn.
Trenton, N.J.
Tulsa, Ok.
Vancouver, Cn.
Washington, D.C.
Wichita, Ks.
Winnipeg, Cn.
Youngstown, Oh.
Index
Labor
103
99
94
77
79
122
102
89
132
73
82
90
106
101
110
82
102
98
76
110
109
117
110
93
82
111
124
72
94
104
82
99
101
99
105
81
105
84
114
85
81
98
85
62
107
Total
108
98
90
89
82
109
100
95
118
77
88
93
101
97
106
87
103
97
79
107
109
110
103
95
82
107
109
77
96
99
89
97
100
97
103
84
105
93
103
89
91
94
90
82
106
Historical Average
Year
1969
1968
1967
1966
1965
1964
1963
1962
1961
1960
1959
1958
1957
1956
1955
1954
1953
1952
1951
1950
1949
1948
1947
1946
1945
1944
1943
1942
1941
1940
1939
1938
1937
1936
1935
1934
1933
1932
1931
1930
1929
1928
1927
1926
1925
1924
Index
100
91
86
83
79
78
76
74
72
71
69
67
65
63
59
58
57
55
53
49
48
48
43
35
30
29
29
28
25
24
23
23
23
20
20
20
18
17
20
22
23
23
23
23
23
23
14
-------
TABLE 6
AVERAGE HOURLY LABOR RATES BY TRADE
Trade
Common Building Labor
Skilled Average
Helpers Average
Foremen (usually 35i6over trade)
Bricklayers
Bricklayers Helpers
Carpenters
Cement Finishers
Electricians
Glaziers
Hoist Engineers
Lathers
Marble & Terrazzo Workers
Painters, Ordinary
Painters, Structural Steel
Paperhangers
Plasterers
Plasterers Helpers
Plumbers
Power Shovel or Crane Operator
Rodmen (Reinforcing)
Roofers, Composition
Roofers, Tile & Slate
Roofers Helpers (Composition)
Steamfitters
Sprinkler Installers
Structural Steel Workers
Tile Layers (Floor)
Tile Layers Helpers
Truck Drivers
Welders, Structural Steel
1970
$5.00
6.85
5.15
7.20
7.15
5.20
6.95
6.75
7.50
6.25
7.05
6.60
6.45
6.20
6.50
6.30
6.60
5.30
7.75
7.20
7.30
6.30
6.35
4.75
7.70
7.70
7.45
6.50
5.25
5.15
7.15
1969
$4.55
6.05
4.65
6.40
6.40
4.70
6.15
5.90
6.45
5.50
5.90
5.95
5.60
5.45
5.80
5.60
5.95
4.85
6.90
6.20
6.35
5.55
5.60
4.45
6.90
6.90
6.45
5.60
4.80
4.60
6.35
1968
$4.10
5.50
4.20
5.85
5.85
4.30
5.40
5.30
5.95
5.10
5.40
5.45
5.25
5.05
5.30
5.15
5.50
4.45
6.15
5.65
5.80
5.05
5.10
4.00
6.10
6.10
5.90
5.20
4.35
4.30
5.80
1967
$3.85
5.15
4.00
5.50
5.55
4.05
5.10
5.05
5.60
4.75
5.10
5.20
5.05
4.75
4.95
4.75
5.15
4.15
5.75
5.35
5.45
4.75
4.85
3.75
5.70
5.70
5.55
4.90
4.15
3.95
5.45
1966
$3.65
4.90
3.85
5.25
5.35
3.95
4.90
4.85
5.45
4.60
4.85
5.05
4.90
4.50
4.80
4.55
5.00
4.00
5.55
5.05
5.15
4.65
4.80
3.55
5.50
5.50
5.25
4.80
4.05
3.65
5.10
15
-------
16
-------
JO
m
z
o
m
30
-------
1. RENDERING INDUSTRY
The production of meat for human consumption produces a large amount
of inedible waste. The process of converting this waste, along with other
inedible animal wastes, into salable products is called rendering. Rendering has
long been classified among the "offensive trades" and has merited the
classification. It does however perform the desirable task of eliminating the
problem of disposing of these massive quantities of animal wastes. Both feed
materials and process gases have highly objectionable odors.
The inedible matter which comprises the charge to rendering operations
comes from two primary sources: waste products from meat packing and
processing, and the carcasses of animals which have died due to accidents,
disease, or natural causes. Rendering operations run by meat packers are
generally confined to processing captive wastes from their own plants. The
quantities of wastes available per head from packing house operations are
shown in Table 7 for several different classes of animals. Scavenger plants
process wastes from packers who do not have their own rendering plants, as
well as the carcasses of animals who have died for reasons other than
slaughtering. Both kinds of plants produce two classes of products: fats used in
the production of soaps, fatty acids, glycerol, and export; and protein
concentrates used for animal feeds.
The chemistry of rendering depends heavily upon the source and kind of
materials fed to the process. Qualitatively, the process employs mild heating to
break down the cell structure in fatty tissues. The fat in these cells is thereby
released and withdrawn as one of the products, generally called grease or
tallow. The solid residue is high in protein and is used as the basis of the
protein concentrate which is the other product. Large amounts of water are
driven off as steam during the reaction. Volatile organics are also given off
during the reaction and produce the infamous odors associated with the
process.
Table 8 shows the differences in composition among possible rendering
charge materials. Fat or grease contents can vary from nearly zero for blood
and feathers to 70% for beef killing fat. Solids contents can vary from less than
10% for beef killing fat and hog lard to over 30% for steers.
A further indication of the chemical complexity involved is given by Table
9 which lists partial chemical analyses of the rendered protein concentrates
from different charge materials. Protein contents vary from 6% in products
from bone rendering to 85% in products containing ground, coagulated, dried
blood. Other characteristics vary over similarly wide ranges.
17
-------
TABLE 7
WEIGHT OF INEDIBLE WASTE FROM
SLAUGHTERED LIVESTOCK*31
Slaughtered Livestock
Cows
Canner Cows
Steers
Baby Beef
Calves
Sheep
Hogs (lard — edible)
Hogs (inedible)
Ib Blood/Head
55
55
5
4
Ib Offal and
Bone/Head
110-125
90-100
90-100
60-90
15-20
8-10
30-50
10-15
18
-------
TABLE 8
COMPOSITION OF TYPICAL RENDERING CHARGE MATERIALS'3 4)
Slaughtered Livestock Waste From:
Cows
Canner Cows
Steers
Baby Beef
Calves
Sheep
Hogs (lard—edible)
Hogs (inedible)
Beef Killing Fat
Beef Offal
Dead Stock Wastes:
Cattle
Cows
Sheep
Horses
Other Materials:
Blood
Feathers
Butcher Shop Scrap
Wt. %
Grease
8-20
10-15
20-30
15-25
8-12
25-35
70-80
15-20
65-70
15-20
12
8-10
22
30
—
-
37
Wt. %
Solids
20-30
30-35
30-35
20-30
20-25
20-25
7-10
18-25
6-10
20-25
25
23
25
25-30
12-13
20-30
25
Wt. %
Moisture
50-72
50-60
35-50
45-65
63-72
40-55
10-23
55-67
20-29
55-65
63
67-69
53
40-45
87-88
70-80
38
19
-------
TABLE 9
PARTIAL CHEMICAL COMPOSITION OF
RENDERED ANIMAL BYPRODUCTS111
Poultry Steamed
Meat and
Bone Meal
Protein (N x 6.25) (%)
Fat (%)
Moisture (%)
Ash (%)
Calcium (%)
Phosphorus (%)
Pepsin Digestibility (%)
Vitamins
Riboflavin (mg/lb)
Niacin (mg/lb)
Pantothenic acid (mg/lb)
51.0
11.8
4.4
28.4
10.0
5.0
91.8
1.5
21.0
4.3
Tankage
61.1
8.1
6.6
20.7
6.0
3.0
95.7
0.88
20.2
1.3
Vitamin B12 (mg/lb) 33.9 26.8
Amino Acids (expressed as percent of sample)
Arginine
Glutamic acid
Histidine
Lysine
Leucine
Isoleucine
Methionine
Cystine
Phenylalanine
Threonine
Tryptophan
Tyrosine
Valine
Glycine
3.01
4.95
0.71
2.55
3.29
1.33
0.72
0.35
1.59
1.73
0.55
0.85
2.41
7.19
2.99
5.28
1.59
3.58
5.21
1.25
0.71
0.29
2.38
2.03
0.82
1.12
3.76
6.65
Blood
Meal
84.5
-
6.8
5.2
0.28
0.28
95.6
0.5
10.2
1.2
4.5
3.64
—
5.00
6.30
14.06
0.90
1.16
-
5.93
3.83
1.06
2.33
8.21
—
Byproduct Bone
Meal Meal
56.4
16.1
5.8
14.6
3.5
1.7
83.3
3.5
31.7
13.8
168.0
3.08
5.52
0.77
3.21
4.15
1.83
0.81
0.81
1.77
2.42
0.68
1.47
2.92
7.45
6.5
3.0
3.0
79.0
25.0
13.0
-
0.5
2.0
1.0
—
0.50
—
0.19
0.88
0.97
0.46
0.18
—
0.56
0.58
0.05
—
0.72
_
20
-------
Variability exists in the fat and grease products as well. Several different grades
of fat can be produced depending upon the type of charge processed and the
processing severity. Increased processing severity tends to produce poorer color
and higher fatty acid content, both of which detract from the salability of the
fat produced.
PROCESS DESCRIPTION
There are two basic process schemes by which rendering is carried out.
They are known as the wet process and the dry process. The choice of
processing scheme depends somewhat upon the size of the total operation and
the type of waste products available as charge. However, by far the most widely
used process is the dry process.
The dry process employs a steam jacketed, agitated vessel. This vessel,
called a cooker or dry melter, is typically a horizontal tank of sufficient size to
hold 8000 to 12000 Ib of charge. Charge material, often hashed or cut into
small pieces, is put into the vessel and heated indirectly through the steam
jacket. The agitator helps distribute heat uniformly throughout the contents of
the tank and prevents material from adhering to the hot wall. A typical layout
of the equipment is shown as Figure 1. Operating conditions vary widely
depending upon the composition of the charge materials and the products
desired from the operation. Typical ranges are:11-41*
Pressure: 0 to 50 psig
Temperature: ambient at start of batch, increasing
to 240° F at completion, or higher
for pressure operation
Batch Time: 45 min to 6 hr
Agitator Speed: 25 to 65 rpm
Batch Size: <. 70% of cooker capacity
During the cooking process, water vapor and volatile organics are given off as
the cell structures in the tissue break down. Pressure in the cooker is created
and controlled by the rate of release of these vapors.
Determination of the end point of the reaction is difficult and critical.
Overcooking will yield poor fat color and high fatty acid content.
Undercooking will produce solids which are difficult to press for fat removal
after cooking. Thermal conductivity instruments are used in many operations
to determine optimum processing time, but empirical estimates based upon
charge composition still find application.
*Superscripts refer to literature references listed at the end of the section.
21
-------
When cooking has been completed, the products are discharged from the
cooker onto perforated plates where the fat is allowed to drain away. The
solids, called cracklings, are collected and put into a press for further reduction
of their fat content to 6 to 12%. Solvent extraction can be used in place of the
press.
In some areas, continuous dry rendering processes are used. They tend to
be highly mechanized using grinders, multistage cooking, and centrifugal
separation. One such process'61 is shown in Figure 2. It employs a modified
falling film evaporator as the cooker and conveys the ground fresh charge to
the process slurried in a stream of recycled product fat. Final product
separation is achieved using two stage centrifugation.
Wet rendering is a much older process than dry rendering. It is used less
frequently than the dry process but still finds current use in the handling of
dead stock — whole animals dead of natural causes, accident, or disease — and
in the production of edible fats and oils from lard. The wet process uses a
closed cooking vessel, usually mounted vertically. A typical wet rendering
process layout is present in Figure 3. The vessel is charged with wastes, and live
steam is introduced. Cooking proceeds under rising temperature and pressure.
The process takes 6 to 8 hours and is completed under 50 to 60 psig steam
pressure. During some operations, pressure is released after initial cooking and
the process completed at atmospheric pressure. When the reaction has been
completed, the grease is decanted. The solids, called tankage, are separated
from residual water and dried.
The solids from both processes are dried, ground, and mixed with grain to
produce the protein concentrate meal used for animal feeds. The fat products
are dried and clarified before sale as raw materials for soaps, fatty acids,
glycerol, and export.
Processes using solvents are also used. One such scheme is called the
Vio-Bin process. It is based upon the fact that ethylene dichloride and water
form a minimum boiling azeotrope. Solvent is put into the cooker with the
animal matter and heat is applied indirectly through the walls. As water is
released from the tissue, it boils off at a constant temperature below the boiling
point of either water or ethylene dichloride. When almost all of the water has
been removed, the temperature will increase, driving off the rest. What remains
in the cooker are the solid product and a mixture of fat and solvent called
miscella. Solid and liquid are separated by a filter cloth supported in a rotary
drier. Solvent is driven off from the solids in the drier using indirect steam heat.
The clear miscella is pumped to a jacketed fat kettle where the solvent is
vaporized using steam heat and vacuum. Solvent vapors from the fat kettle and
the drier are condensed, separated from the water by decantation, and reused.7
22
-------
NJ
CO
CUTTER
WASHER
fr!
VACUUM
PUMP
FEEDING
DOME
CRACKLING
RECEIVING
RENDERING
COOKER
CRACKLING
PRESS
FIGURE 1
DRY RENDERING OPERATION
CRACKLING
GRINDER
-------
DISINTEGRATOR
Cooling water supply
Steam
SHOP FAT & BONE
KILL FLOOR
MAGNET
a
PREBREAKER
FLUIDIZING LEVEL CONTROL
TANK TOWER I 1
Cooling water
return
FIGURE 2
CONTINUOUS RENDERING FLOW SCHEME
Cake meal
to grinding
-------
ro
(71
HYDRAULIC
PRESS
PRESS CAR
O 1?
LARD
LINE
HYDRAULIC
PRESS PUMP
VACUUM
PUMP
FIGURE 3
WET RENDERING OPERATION
-------
NATURE OF THE GASEOUS DISCHARGE
A typical dry rendering reaction will reduce the moisture content of the
animal matter from 60 to 70% down to 9%. For a 5000 Ib batch size, this is
equivalent to removing 2800 Ib of moisture as a vapor. Rates of vapor
evolution for this batch size have been reported'51 to vary from 40,000 ACFH
during the initial minutes at temperature to 20,000 ACFH during the rest of
the reaction. Both rates were measured at 212° F. Further measurement
indicated that 5% of this vapor was non-condensable.'51
Very little analytical work has been done on the vapors evolved during
rendering. Roland's'91 work gives some indication of the kinds of compounds
involved and why the associated odors cause so many complaints. His analysis
of the condensate from dry rendering vapors is reproduced in Table 10. These
data clearly show that the bad reputation of these vapors is well deserved and
that rendering stale materials augments the problem.
Although the cooker is the worst odor producer in rendering operations,
odors are emitted from several other sources and are caused by different classes
of compounds. Several of these sources are listed in Table 11 along with a
qualitative indication of the odor causing compounds.
Odors from rendering are emitted in high concentrations. Table12
summarizes odor concentrations and emission rates from some typical
rendering operations. The data in the table are expressed in "odor units". One
odor unit per cubic foot is that concentration of odor which is numerically
equivalent to its odor threshold. A level of 5000 odor units per cubic foot
would require 5000 dilutions with clean air to make it just detectable. As
shown in the table, rendering can emit gases with odor concentrations as high
as one million o.u./SCF at a rate of almost four billion odor units per ton of
feed. The wide range of odor concentrations exists due to variability in process
severity, type of charge material, and age of charge material.
POLLUTION CONTROL CONSIDERATIONS
Gases discharged from rendering operations originate from three main
sources:
1. Exhausts from cookers or similar process equipment
2. Ventilation of other equipment
3. Ventilation of storage areas
26
-------
TABLE 10
ANALYSIS OF COMPENSATE FROM THE DRY RENDERING
OF FLESH IN FRESH AND STALE CONDITIONS'9'
Water
Ammonia and monoethylamine
Diethylamine
Triethylamine
Hydrogen Sulphide
Carbon Dioxide
Oil (nonvolatile at 100° C.)
Other Nonvolatile Organic Matter
Biochemical Oxygen Demand (ppm)
Oxygen Absorbed, (ppm) 3 min.
Percent of
Original Flesh
Fresh Flesh
62.75
0.0329
Traces
Traces
0.0027
0.0133
-
0.0045
158
61.5
Stale Flesh
67.04
0.3913
0.0133
0.0236
0.0024
0.0664
0.0436
0.0226
134
244
27
-------
TABLE 11
SOURCES OF ODOR IN RENDERING PLANTS
Source
Dry Cooker Vapors
Vapor Leaks From Cookers
Hot Fat Dumping
Feather Driers
Feather Meal Dumping
Loading Docks
Compound Class Causing Odor
Amines, aldehydes
Aldehydes, fats, amines
Fats, fatty acids
Sulfides
Mercaptans
Fats, fatty acids
28
-------
TABLE 12
ODOR CONCENTRATIONS AND EMISSION RATES FROM
INEDIBLE REDUCTION PROCESSES'4'
Odor Concentration,
Odor Units/SCF
Typical Moisture
Typical Content of Exhaust Products,
Range Average Feeding Stocks, % SCF/ton of feed3
Rendering cooker,
dry-batch typeb
Blood cooker
dry -batch typeb
Feather drier,
steamtubec
Blood spray
drierc- d
5,000 to 50,000 50
500,000
10,000 to 100,000 90
1 million
600 to 2,000 50
25,000
600 to 800 60
1,000
20,000
38,000
77,000
100,000
Modal Emission
rate, odor units/
ton of feed
1,000x 106
3,800 x 106
153x 106
80 x 106
CO
a) Assuming 5% moisture in solid products.
b) Non-condensible gases are neglected in determining emission rates.
c) Exhaust gases are assumed to contain 25% moisture.
d) Blood handled in spray drier before any appreciable decomposition occurs.
-------
Exhausts from process equipment vary widely with the charge, the process
step involved, and as indicated earlier, with time over any batch. The two
principal pieces of equipment which emit exhaust gases are the cooker and the
air drier used primarily for cooked feathers.
Exhaust rates from cookers can be estimated from the quantity of
moisture to be removed from the charge. Average rates can be calculated from
the cycle time and the moisture contents of feed and product. As indicated
earlier the specific rate of emission at any one time varies widely during the
process cycle. The maximum rate is normally twice the average.'4* For
example, if 5000 Ib of material is processed with a reduction in moisture
content from 65% to 9% over four hours, 2800 Ib of moisture will be removed
at an average rate of 700 Ib/hr. The maximum rate will be 1400 Ib/hr.
Expressed in volumetric terms the maximum rate is 31,000 SCFH, assuming 5%
noncondensibles in the gas. Evaporation rates rise to a maximum early in the
cook and decline thereafter following the pattern shown in Figure 4. Emission
rates from continuous processes can be estimated from throughput rates and
feed and product analyses. Emission rates from batch blood cookers are lower
due to longer processing times. They seldom exceed 500 ACFM and are usually
lower.'4)
Feather driers are run continuously to produce an exhaust gas containing
10 to 30% moisture and a cooked-feathers product containing 5% moisture.'41
If such a drier processed 1000 Ib/hr of cooked feathers containing 50%
moisture, it would exhaust 555 ACFM of gas at 30% moisture.
Ventilation of other equipment and storage areas is handled in three
different ways in the rendering industry. These three styles of ventilation
produce a wide range in the quantity of odorous air emitted from rendering
plants. Older plants ventilate the storage rooms and the rooms in which the
equipment operates. Ventilation consists of drawing room air out through the
ceiling or walls while replacing it with fresh air which flows in through other
openings. Ventilation in this way uses large quantities of air which, when
exhausted, is contaminated with odors.
Newer plants use hoods over some of their equipment such as charge
grinders, expellers, and fat separating plates. Hooding in this way can also cause
large quantities of odorous air to be exhausted. Velocities of 100 fpm at the
hood are common for this service.'41 The amount of ventilation air exhausted
by either this or the previous style of ventilation can easily exceed the amount
of gas exhausted from the cooker.
The most modern rendering plants have designed their ventilation systems
with the criterion of minimizing the air exhaust rate from the plant. These
designs involve closed hooding of process equipment and tightly closed dead
stock storage areas.
30
-------
<
cc.
I
INSTANTANEOUS RATE
FIGURE 4
RATE OF VAPOR EVOLUTION
FROM DRY RENDERING
AVERAGE RATE
FRACTION OF TIME TO END OF COOK
31
-------
Because the emission problem is basically limited to odors, the pollution
control systems of interest are:
1. Condensation
2. Incineration
3. Absorption
4. Adsorption
In rendering processes using solvents either for processing or product
extraction, solvent loss is also an emission problem and its recovery is desirable
from both environmental and economical viewpoints.
The major component of vapors from the cooker is steam. Reduction in
the volume of this gas through condensation is often advisable in view of the
attendant reduction in odor and the reduction in the size of subsequent
equipment.
Several types of condensers have been successfully employed in rendering
plants. These include contact condensers and surface condensers, both air and
water cooled. Reductions in gas volume by a factor of 10 to 20 are common
due to the high moisture content of the exhaust gas. Odor reductions due to
condensation are high but are often insufficient to eliminate the problem by
themselves. Typical reductions of odor emission rates are 50% for a surface
condenser and 99% for a contact condenser. Although contact condensers are
inexpensive to install, they require large quantities of once-through cooling
water. Cooling water requirements range from 15 to 20 pounds per pound of
steam condensed.141 This may overload sewage systems or create water
pollution problems as the used water contains dissolved odor compounds.
Surface condensers can be installed at a cost of about 50% more than contact
condensers, but operating charges will be 65 to 80% less due primarily to far
lower water requirements.
One source151 reports comparative costs for surface and contact
condensers sized to handle a maximum flow of 40,000 ACFH and an average
flow of 20,000 ACFH. The contact condenser installed cost was $2000
compared to $5050 for a water cooled surface condenser. The contact
condenser used only one-third as much electricity (V/2 hp vs. 414 hp) but
required 28% times as much water (2000 GPH vs. 70 GPH). The net result was
that the surface condenser operating cost was 78% less than the contact
condenser.
Materials of construction for surface condensers can be a problem. Both
acidic and alkaline vapors are possible. Rendering of dead stock can produce
both during each cycle. Heavy gauge mild steel or stainless steel may be
required, depending upon the specific wastes processed.
32
-------
Incineration
The most positive control method for odors is incineration. The Los
Angeles Air Pollution Control District uses this method as a standard, and in
Rule 64 states that any alternative method used must be equal or better than
direct flame incineration at 1200°F for a period of not less than 0.3 sec.
Incinerators are seldom used directly on gas streams from rendering due to
the high moisture content of these gases. More often they are used after
condensers which reduce the moisture content of the gas discharged to the
incinerator so as to reduce fuel cost. The break-even point between direct
incineration of the total exhaust stream and combination condensation-
incineration lies between 15% and 40% moisture content of the exhaust gas,
depending upon gas volume and exit temperature, fuel cost, water cost and
availability, and equipment costs.'41
Odor removal efficiencies for combined condenser-incinerator systems are
shown in Table 13 compared to the performance of condensers alone. The data
are based upon a typical exhaust gas from a hypothetical cooker. The gas is
emitted at 500 SCFM and is 95% condensible. Odor removal efficiencies in
excess of 99.9% are shown for combined systems employing either surface or
contact condensers.
Incineration is an expensive abatement process due to its high operating
temperatures. Operation at 1200°F is the standard and temperatures as high as
2000° F have been reported for units processing rendering gases'81. Fuel costs
increase with the temperature requirements for odor control.
Catalytic incineration can reduce the operating cost of odor control
relative to thermal incineration through reduced operating temperatures.
Operating temperature reductions of more than 400° F have been reported
using currently available catalytic equipment'81. The drawbacks to catalytic
incineration are the much higher capital and maintenance costs of the
equipment. This is due to the large quantity of catalyst necessary to achieve the
high efficiencies required at the low combustible concentrations as well as the
catalyst regeneration costs due to the decline in activity during use.
Justification of a catalytic unit therefore must be based upon the difference in
operating versus the capital and maintenance costs.
Absorption
Absorption has also been used to some extent to control rendering plant
odors. The most common system employs a wet scrubber with air oxidizing
33
-------
chemical such as potassium permanganate in the scrubbing liquor. The solution
is used in concentrations below 5% and is buffered to an alkaline pH. Odor
compounds are oxidized by the permanganate leaving a manganese dioxide
solid residue in the scrubbing system. Periodic washing is required to remove
these deposits.
Experiments have been run demonstrating the odor control potential of
the system for the types of odors emitted by rendering processes and several
commercial installations are in operation.'1' • ' 2)
Where low odor removal efficiency is acceptable, sodium hydroxide
solution can be used in place of the permanganate solution. A pH of 10 in the
circulating liquor has been found to be effective where odor removal
requirements are not high. A sodium hydroxide scrubbing stage can also be
used as a pretreatment step to a permanganate scrubber or a carbon bed in
cases where the odor removal efficiency required is high. Other oxidation
reagents such as chlorine and sodium hypochloride may also be used.
Adsorption
Adsorption systems have been used to control odors from rendering
operations. There are however several limitations to their use.
1. The adsorbent material is restricted to activated carbon because of
the high moisture content of the gases present.
2. The adsorption capacity of the activated carbon is low at
temperatures above 120°F. Gases must therefore be cooled prior to
entering the bed.
3. Regeneration cycles may be short. This is due to the high odor
concentrations in rendering gases and to the tendency of light but
smelly compounds such as NHg and h^S to be easily desorbed as
heavier compounds adsorb.
4. A means must exist for destruction of the odor compounds given off
during regeneration or the carbon must be used once through.
Within these limitations, activated carbon can deodorize rendering gases.
Adsorption capacities have been reported at 0.10 to 0.25 Ib adsorbate per
pound of carbon. The performance is as good as incineration. Several
commercial installations have been reported.<5> 10| In each case the carbon bed
is used in combination with a condenser to cool the gases (see Figure 5).
Although numerical performance data were not reported, the gases treated
were characterized as acceptable in odor concentration.
34
-------
TABLE 13
ODOR REMOVAL EFFICIENCIES FOR CONDENSERS AND
Odors from Cooker
CONDENSER-INCINERATOR COMBINATIONS'4'
Odors from Control System"
Concentra-
tion, Odor
Units/SCF
50,000
Emission
rate, odor Condenser
units/min Tvoe
25,000,000 None
Surface
Surface
Contact
Contact
Condensate Afterburner
Temp..°F TemD..°F
1,200
80 None
140 1,200
80 None
140 1,200
Concentration,
Odor
Units/SCF
100 to 150
100,000 to
10 million
(Mode 500,000)
50 to 100
(Mode 75)
2,000 to
20,000
(Mode 10,000)
20 to 50
(Mode 25)
Modal
Emission
rate. Odor
Units/min
90,000
12,500,000
6,000
250,000
2,000
Odor
Removal
Efficiency,
%
99.40
50
99.98
99
99.99
CO
01
'Based on a hypothetical cooker that emits 500 SCFM of vapor containing 5 percent noncondensable gases.
-------
No matter what kind of primary control device is used, it should be
designed with an intercepter tank between the cooker and the control
equipment. It is common during rendering for the cooker vent to plug
momentarily. When that plug breaks, a pressure surge carries solids and liquids
out the vent. Unless provision is made to catch the material carried over, it can
seriously impair performance of the control equipment.
Effective odor control in rendering requires control of many sources.
Control of only the process gases, no matter how efficient, will not be effective
due to odor emissions from the room ventilators and equipment hoods. Since
these odors are emitted in such high concentrations, all sources of odor must be
identified and treated.
SPECIFICATIONS AND COSTS
Incinerator and scrubber specifications have been written for each of three
services at a batch rendering plant. The three services are:
1. Cooker vent gas combined with gas from expeller and charge grinder
hoods
2. Room ventilation gases
3. The above two services combined.
Each specification was written on the basis of a gas rate rather than a plant size.
This was done because of the wide range of gas flow rates which can occur in
rendering plants of comparable production rates, as was explained earlier in the
section titled Pollution Control Considerations. Specifications were written in
such a way that the cost information generated from them covers the relevant
range of gas flow rates. Each scrubber specification requests bids for both high
and low efficiency at each of two gas rates. Each incinerator specification
shows data for both high and low efficiency but requests only one quote for
each gas rate coupled with a representation of the performance level which will
be achieved. The complete specifications are shown in Tables 14 thru 19 and
26 thru 31.
36
-------
w
-J
HUMID AIR
OUTLET
DRIFT WATER
ELIMINATOR
WARM WATER
DISTRIBUTOR
H.D. POLYETHYLENE
COOLING
SURFACES
DRY AIR
INLET
INLET FOR CONTAMINATED
PROCESS VAPORS A GASES
t 111 ft
MAKE-UP
WATER
INLET
OUTLET FOR
NONCONDENSIBLE
GASES
\\\\\\
IIV 11
r
ii
ACTIVATED
CARBON
FILTER BEOS
FAT CONDENSING
SCREENS
r
OUTLET FOR
CONDENSED
EFFLUENT
COLD WATER
PUMP
/ SOLIDS
*- COLLECTING
BASKET
CONDENSING
COILS
FIGURE 5
ACTIVATED CARBON DEODORIZER INTEGRATED
WITH SOLIDS COLLECTOR AND CONDENSER
-------
Capital cost data for scrubbers are presented on six graphs which show the
relationship between cost and gas flow rate through the unit. Figures 6 and 7
show the cost of the scrubbers only. Figures 8 and 9 show the cost of the
scrubbers plus auxiliaries such as fans, pumps, drives, solids disposal equipment,
etc. Figures 10 and 11 show the cost of the turnkey scrubbing systems. The
first figure in each pair presents data for the medium efficiency case while the
second shows data for high efficiency performance. The data presented are the
averages of either two or three bids. Statistical confidence limits were
calculated for the quotes of the scrubbing device alone. The results for the
medium efficiency case are presented in Figure 12. Those for high efficiency
are presented in Figure 13. The calculations were made based upon the
assumption that the quotations came from a population of twenty potential
suppliers.
Annual operating costs for both levels of efficiency are presented in
Figure 14. In all cases, the chemical usage represents more than 95% of the
total annual charges. Two of the bidders quoted chemical systems other than
the specified potassium permanganate solution buffered with borax. One
supplier quoted a dissolved chlorine system for the room vent scrubbers.
Another supplier quoted a two stage system; a sodium hydroxide stage
followed by a potassium permanganate stage. At medium efficiency, the
permanganate stage was not used. Chemical usage costs for each of these
alternatives were much lower than those quoted for the specified system. These
numbers were not included in the averages presented either on the tables or the
graphs.
Capital cost data for incinerators are presented on three graphs which
relate cost to gas flow rate. Figure 15 shows the cost of the incinerator only.
Figure 16 shows the incinerator plus auxiliaries, such as the fan and fan drive.
Figure 17 shows the cost of the complete turnkey system. Confidence limit
calculations, similar to those made for scrubbers, were made for the
incinerators alone and for the turnkey price of the incineration systems.
Results of these calculations are presented in Figures 18 and 19.
Annual operating cost data for the incineration systems are shown in
Figure 20.
38
-------
39
-------
TABLE 14
SCRUBBER PROCESS DESCRIPTION FOR
RENDERING COOKERS AND HOODS SPECIFICATION
PROCESS DESCRIPTION
The scrubber is to deodorize exhaust gases from the cooker and the hoods over the
charge grinders and expellers in a dry rendering plant. The plant is operated batchwise. The
time required in the cooker for each batch is three hours. Since two or three batches will be
run each day, the scrubber will be in use for 8 to 12 hours dally. Cooker exhaust gases are
sent through the plant wall to a 30 ft stack located outside the building. Hood ventilation is
exhausted on the roof at a height of 20 ft. A 30 ft square area is available for new equipment
next to the location of the stack. A four inch concrete slab covers the area. Sufficient
electric power and fresh water are available at the site. The sewer is available and will accept
water in the 4 to 10 pH range, if it contains less than 1 wt. % solids content.
The scrubbing liquor is to consist of a 3 wt. % solution of potassium permanganate
buffered to 9.0 pH with borax. Materials of construction should be consistent not only with
the permanganate solution but also the possibility of both acidic and basic gases coming
from the cooker. Bids should include the following:
1. Low energy wet scrubber and mist eliminator.
2. Necessary fans and motors. Fans should operate at less than 2,000 rpm.
3. 20 ft stack.
4. Recirculating tank.
5. Permanganate makeup and storage tank.
6. Inter connecting ductwork for all equipment furnished.
7. Appropriate control system.
8. Necessary provisions for periodic cleaning of manganese dioxide residue.
All of the above, except the scrubber proper, should be treated as auxiliaries.
Each bidder will submit four separate and independent quotations; one for each of two
efficiency levels at each of two plant sizes.
40
-------
TABLE 15
SCRUBBER OPERATING CONDITIONS
FOR RENDERING COOKERS AND HOODS SPECIFICATION
OPERATING CONDITIONS
SMALL LARGE
AVE. MAX. AVE. MAX.
Cooker
Gas Rate, ACFM 283 567 850 1,700
Gas Temp., °F 2)2 212
Odor Concentration,
o.u./SCF 150,000 150,000
Odor Emission Rate,
o.u./min 32.9 x 106 65.8 x 106 98.6 x 1O6 197.2 x JO6
Expeller and"Grinder Hoods
Gas Rate, ACFM 2,000 5,000
Gas Temp., °F 100 ' 100
o.u./SCF 90,000 90,000
o.u./min 167 x 106 418 x 10**
Combined Gases
Gas Rate, ACFM 2,600 6,750
Gas Temp., °F 130 130
o.u./SCF 102,000 103,000
o.u./min 233x JO6 615 x 10s
Low Efficiency Case
o.u./SCF @ Ground 8* 8 *
% Removal 45 46
High Efficiency Case
o.u./SCF @ Ground <1* < 1 *
% Removal 93 93
*30 min average as calculated by Bosenquet-Pearson and Bosenquet-Carey-Halton.
41
-------
TABLE 16
SCRUBBER PROCESS DESCRIPTION
FOR RENDERING ROOM VENTS
SPECIFICA TION
PROCESS DESCRIPTION
The scrubber is to deodorize room ventilation gases from a dry rendering plant. The
plant is operated batchwise. The time required in the cooker for each batch is three hours.
Since two or three batches will be run each day, the scrubber will be in use for 8 to 12 hours
daily. Ventilation air from the feed storage area is currently exhausted through the roof at a
height of 20 ft. Cooker gases are sent to a 30 ft stack located outside the building. A 30 ft
square area is available for new equipment next to the location of the stack. A four inch
concrete slab covers the area. Sufficient electric power and fresh water are available at the
site. A sewer is available and will accept water in the 4 to 10 pH range, if it contains less than
1 wt. % sol ids content.
The scrubbing liquor is to consist of a 3 wt. % solution of potassium permanganate
buffered to 9.0 pH with borax. Bids should include the following:
1. Low energy wet scrubber and mist eliminator.
2. Necessary fans and motors. Fans should operate at less than 2,000 rpm.
3. 30 ft stack.
4. Recirculating tank.
5. Permanganate makeup and storage tank.
6. Inter connecting ductwork for all equipment furnished.
7. Appropriate control system.
8. Necessary provisions for periodic cleaning of manganese dioxide residue.
All of the above, except the scrubber proper, should be treated as auxiliaries.
Each bidder will submit four separate and independent quotations; one for each of two
efficiency levels at each of two plant sizes.
42
-------
TABLE 17
SCRUBBER OPERATING CONDITIONS
FOR RENDERING ROOM VENTS
SPECIFICATION
OPERATING CONDITIONS
SMALL
Room Ventilation
Effluent Gas Rate, ACFM 3,000
Effluent Gas Temp., °F 90
Odor Concentration,
o.u./SCF 100,000
Odor Emission Rate,
o.u./min 234 x 10s
Low Efficiency Case
Concentration @ Ground,
o.u./SCF 8 *
% Odor Removal 44
High Efficiency Case
Concentration @ Ground,
o.u./SCF < 1 *
% Odor Removal 93
LARGE
14,000
90
100,000
1,320* 106
8
44
< 1'
93
*30 min average as calculated by Bosenquet-Pearson and Bosenquet-Carey-Halton.
43
-------
TABLE 18
SCRUBBER PROCESS DESCRIPTION
FOR COMBINED RENDERING VENTS
SPECIFICATION
PROCESS DESCRIPTION
The scrubber is to deodorize the total gases emitted from a dry rendering plant. The
plant is operated batchwise. The time required in the cooker for each batch is three hours.
Since two or three batches will be run each day, the scrubber will be in use for 8 to 12 hours
daily.
Ventilation air from the hoods and storage area is currently exhausted through the roof
at a height of 20 ft. Cooker gases are sent to a 30 ft stack located outside the building. A 30
ft square area is available for new equipment next to the location of the stack. A four inch
concrete slab covers the area. Sufficient electric power and fresh water are available at the
site. The sewer is available and will accept water in the 4 to 10 pH range, if it contains less
than 1 wt. % solids content.
The scrubbing liquor is to consist of a 3 wt. % solution of potassium permanganate
buffered to 9.0pH with borax. Bids should include the following:
1. Low energy wet scrubber and mist eliminator.
2. Necessary fans and motors. Fans should operate at less than 2,000 rpm.
3. 30 ft stack.
4. Recirculating tank.
5. Permanganate makeup and storage tank.
6. Inter connecting ductwork for all equipment furnished.
7. Appropriate control system.
8. Necessary provisions for periodic cleaning of manganese dioxide residue.
All of the above, except the scrubber proper, should be treated as auxiliaries.
Each bidder will submit four separate and independent quotations; one for each of two
efficiency levels at each of two plant sizes.
44
-------
TABLE 19
SCRUBBER OPERATING CONDITIONS
FOR COMBINED RENDERING VENTS
SPECIFICATION
OPERATING CONDITIONS
Total Gas Stream
Effluent Gas Rate,ACFM
Effluent Gas Temp., °F
Odor Concentration,
o.u./SCF
Odor Emission Rate,
o.u./min
Low Efficiency Case
Concentration @ Ground
o.u./SCF
% Odor Removal
High Efficiency Case
Concentration @ Ground
o.u./SCF
% Odor Removal
SMALL
5,620
110
101,000
517x 106
8
45
LARGE
21,400
120
101,000
1,935x 106
8
45
93
93
*30 minute averages as calculated by Bosenquet-Pearson and Bosenquet-Carey-Halton.
45
-------
TABLE 20
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR
RENDERING COOKERS AND HOODS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost >
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other J
*•
(4) Total Cost
LA Process Wt.
Small
2,600
130
2,340
2,510
103
2,370
45
2,000
825
1,600
250
3,630
2,050
8,305
18,660
Large
6,750
130
6,060
6,500
103
6,150
46
3,125
925
1,700
250
4,180
2,725
11,155
24,060
High Efficiency
Small
2,600
130
2,340
2,510
103
2,370
93
2,778
825
1,750
250
3,630
2,075
8,757
20,065
Large
6,750
130
6,060
6,500
103
6,150
93
4,525
1,025
1,950
250
4,180
2,725
11,855
26,510
46
-------
TABLE 21
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR RENDERING COOKERS AND HOODS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating LatDor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify *KMn04
Borax
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2.600
$6/hr
$8/hr
I .01I/kw-h
$0.25/Mga
0.38/lb
10.0625/lb
LA Process Wt.
Small
2,512
27
2 .539
1,650
-
: 300
L 122
114,900
101,250
216,572
220,761
1,866
222,627
Large
2,625
38
2,663
1,750
-
490
289
269,040
243,000
512,819
517,232
2,406
519,638
High Efficiency
Small
2,512
27
2,539
1,700
-
362
122
172,368
101,250
274.102
278,341
2,006
280,347
Large
2,625
38
2,663
1,800
-
554
289
410,400
243,000
654.243
658,706
2,651
661,357
Not all quotes used this system of chemicals. Based on only one
chemical cost quote.
-------
TABLE 22
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR
RENDERING ROOM VENTS *
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. 9
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. 9
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(,
'0
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost >
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other J
(4) Total Cost
>
LA Process Wt.
Small
3,000
90
2,890
2,950
75
2,920
44
2,487
949
1,250
244
3,190
633
9,801
18,554
Large
14,000
90
13,500
13,800
75
13,700
44
5,453
1,769
1,417
311
3,757
1,400
14,555
28,662
High Efficiency
Small
3,000
90
2,890
2,950
75
2,920
93
3,005
982
1,350
244
3,191
650
10,068
19,490
Large
14,000
90
13,500
13,800
75
13,700
93
6,707
1,948
1,583
310
3,757
1,433
15,359
f
31,097
'Based on two bids
48
-------
TABLE 23
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR RENDERING ROOM VENTS*
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify **KMn04
Borax
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$6/hr
$8/hr
f .011/kw-t
J.25/M gal
?.38/lb
J .0625/lb
LA Process Wt.
Small
1,745
23
1.768
1,100
-
f 322
168
123,200
111,375
235,065
237,933
1,502
239,435
Large
1,840
30
1.870
1,200
-
1,026
738
541,728
500,000
1,043,492
1,046,562
2,533
L ,049, 095
High Efficiency
Small
1,745
23
1.768
1,117
-
366
168
184,680
111,375
296,589
299,474
1,595
301,069
Large
1,840
30
1.870
1,268
-
1,256
738
820,000
500,000
,321,994
1,325,132
2,774
,327,906
CO
Based on two bids.
** Not all quotes used this system of chemicals.
Based on one quote .
-------
TABLE 24
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS
FOR RENDERING COMBINED VENTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s>
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost ~"^
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other )
>
(4) Total Cost
LA Process Wt.
Small
5,620
110
5,230
5,400
83
5,280
45
2,730
925
1,725
250
5,330
1,130
10,440
22,530
Large
21,400
120
19,600
20,500
83
20,000
45
6,425
2,350
2,000
250
5,380
2,400
19,155
37,960
High Efficiency
Small
5,620
110
5,230
5,400
83
5,280
93
3,922
925
1,950
250
5,330
1,175
11,103
24,655
Large
21,400
120
19,600
20,500
83
20,000
93
9,100
2,800
2,450
250
5,380
2,600
20,830
43,410
50
-------
TABLE 25
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR RENDERING COMBINED VENTS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify *KMn04
Borax
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$6/hr
$8/hr
$,011/kw-hi
J.25/M ga:
$.3S/lb
$ .0625/lb
LA Process Wt.
Small
2,400
15
2,415
1,725
-
445
229
215,870
195,750
412,294
416,434
2,253
418,687
Large
2,700
45
2,745
1,900
-
1,164
824
820,800
742,500
1,565,288
1,569,933
3,796
1,573,729
High Efficiency
Small
2,400
15
2,415
1,750
-
562
229
328,320
195,750
624,861
629,026
2,466
631,492
Large
2,700
45
2.745
2,000
-
1,495
824
1,231,200
742,500
1,976,019
1,980,764
4,341
1,985,105
Not all quotes used this system of chemicals. Based on one quote.
-------
FIGURE 6
CAPITAL COST OF MEDIUM EFFICIENCY SCRUBBERS ONLY
FOR RENDERING PLANTS
C/J
cc
o
o
V)
Q
<
CO
O
X
o
o
10
8
6
5
1
O
C)
2000 3000
5000
7000
10000
20000
EXHAUST GAS RATE, ACFM
52
-------
FIGURE 7
CAPITAL COST OF HIGH EFFICIENCY SCRUBBERS ONLY
FOR RENDERING PLANTS
10
V)
tc
O
Q
u.
O
CO
Q
<
CO
O
I
00
O
O
8
6
5
4
3
2
1
2C
X8
X^
X
k"
O
^
,x
1
X
X
r
>x
s
^/£>
IOO 3000 5000 7000 10000 20000
EXHAUST GAS RATE, ACFM
53
-------
FIGURE 8
CAPITAL COST OF MEDIUM EFFICIENCY SCRUBBERS
PLUS AUXILIARIES FOR RENDERING PLANTS
CO
cc
o
o
CO
O
CO
O
2000 3000 5000 7000 10000
EXHAUST GAS RATE, ACFM
20000
54
-------
FIGURE 9
CAPITAL COST OF HIGH EFFICIENCY SCRUBBERS
PLUS AUXILIARIES FOR RENDERING PLANTS
CO
cc
o
Q
CO
a
CO
O
I
CO
O
O
2000 3000 5000 7000 10000
EXHAUST GAS RATE, ACFM
20000
55
-------
FIGURE 10
CAPITAL COST OF MEDIUM EFFICIENCY TURNKEY
SCRUBBING SYSTEMS FOR RENDERING PLANTS
100
80
CO
cc
O
I
10
2000
3000 5000 7000 10000
EXHAUST GAS RATE, ACFM
20000
56
-------
FIGURE 11
CAPITAL COST OF HIGH EFFICIENCY TURNKEY
SCRUBBING SYSTEMS FOR RENDERING PLANTS
Vi
cc
o
Q
V)
O
V)
D
O
X
fe
o
o
100
80
60
50
40
30
20
10
2000
0
3000 5000 7000 10000
EXHAUST GAS RATE, ACFM
20000
57
-------
FIGURE 12
CONFIDENCE LIMITS FOR CAPITAL COST OF
MEDIUM EFFICIENCY SCRUBBERS ONLY FOR RENDERING PLANTS
50
40
30
20
oc
5 10
_i
8 8
O
o 6
o
0
Z 4,
CO
D o
O °'
X
L_- 2.
fe
8
o
'
6.
.5.
*
s
s
^
'"
s
s'
*~
<
s
/
(
^
^
\s
S
s
s>
,'
^ _r
^ ^*~
^•^ ^
./^
S^
/'
''
/
, 90°/
• 7R°/I
. [W]F^
^ 75%
90°/
>
,M
1000 2000 4000 7000 10000 20000 50000 100000
EXHAUST GAS RATE, ACFM
58
-------
FIGURE 13
CONFIDENCE LIMITS FOR CAPITAL COST OF
HIGH EFFICIENCY SCRUBBERS ONLY FOR RENDERING PLANTS
10
cc
<
o
Q
1
I
o
I
o
o
1
2000
X
3000 5000 7000 10000
EXHAUST GAS RATE, ACFM
20000
59
-------
FIGURE 14
ANNUAL COSTS FOR WET SCRUBBERS
FOR RENDERING PLANTS
2000
V)
cc.
o
Q
CO
Q
CO
O
X
O
O
1000
800
600
500
400
300
200
2000
/I MEDIUM
EFFICIENCY
3000 5000 7000 10000
EXHAUST GAS RATE, ACFM
20000
60
-------
61
-------
TABLE 26
INCINERATOR PROCESS DESCRIPTION
FOR RENDERING COOKERS AND HOODS
PROCESS DESCRIPTION
SPECIFICATION
The incinerator is to deodorize exhaust gases from the cooker and the hoods over the
expellers and charge grinders in a dry rendering plant. The cooker is operated batchwise in
this plant. Time required in the cooker for each batch is three hours. Since two or three
batches will be run each day, the incinerator will be in use for 8 to 12 hours daily.
Cooker gases are exhausted through the plant wall to a condenser located on the
ground outside the building. Effluent gases from the condenser are vented into a 30 ft stack.
Ventilation from the hoods is exhausted on the roof at a heigh t of 20 ft. A 30 ft square area
is available for new equipment next to the location of the condenser and the stack. A four
inch concrete slab covers the area. Sufficient electric power is available at the site.
The incinerator is to be natural gas fired. Gas is available at 1.0 psig having the
following composition:
Component
CO2
N2
°2
CH
i-C4Hw
n-C4H1Q
Specific Gravity: 0.589
Volume %
0.90
0.38
0.00
94.96
3.02
0.48
0.07
0.09
0.10
100.00
Higher Heating Value: 1034 Btu/SCF
This specification covers the incinerator, burner, 30 ft stack, controls, and other
equipment included as a part of the incinerator, such as insulation, jacketing, etc. A suitable
control panel and two days startup service by a competent engineer should be included.
Incinerator operation and safety controls are to be designed to meet FIA * insurance
requirements. The stack, controls, control panel, startup service, etc., should be considered
as auxiliaries.
Although specifications have been written for two efficiency levels at each plant size,
vendors'quotations should consist of only one quotation for each plant size with a
representation of the efficiency expected. Every effort should be made to achieve the
performance indicated by the high efficiency specification.
*FIA indicates Factory Insurance Association.
62
-------
TABLE 27
INCINERATOR OPERATING CONDITIONS
FOR RENDERING COOKERS AND HOODS
SPECIFICATION
OPERATING CONDITIONS
SMALL
LARGE
Cooker
Gas Rate, ACFM
Gas Temp., °F
Odor Concentration,
o.u./SCF
Odor Emission Rate,
o.u./min
Condenser Gas Discharge
Gas Rate, ACFM
Gas Temp., °F
%Air
%H2O
Odor Concentration,
o.u./SCF
Odor Emission Rate,
o.u./min
Expeller and Grinder Hoods
Gas Rate, ACFM
Gas Temp., °F
%Air
Relative Humidity, %
Odor Concentration,
o.u./SCF
Odor Emission Rate,
o.u./min.
Combined Gas Stream
Gas Rate, ACFM
Gas Temp., °F
%Air
Relative Humidity, %
Odor Concentration,
O.U./SCF
Odor Emission Rate,
o.u./min
AVE.
283
MAX.
567
AVE.
850
MAX.
1,700
212
150,000
32.9 x 106 65.8 x 1O6
212
150,000
98.6x 106
197.2 x 106
14.2
140
~0
~20
1.34 x JO6
16.4x 1O6
-100
-20
28.4
140
-0
"20
1.34 x 1O6
32.9 x 106
2,000
100
-100
-20
90,000
167x 106
2,030
101
98.5
21
97,500
200 x 1O6
42.5 85
140 140
~o -o
-20 -20
1.34 x 106 1.34 x
49.3 x 106 98.6 x
5,000
100
- 100 ~ 100
-20 ~20
90,000
417 x 106
5,090
101
98
21
102,000
516x 106
106
10s
63
-------
Low Efficiency Case
Concentration Ground,
o.u./SCF 8 *
% Odor Removal 43
High Efficiency Case
Concentration @ Ground
o.u./SCF < 1 * < /
% Odor Removal 93 93
*30 minute average as calculated by Bosenquet-Pearson and Bosenquet-Carey-Halton.
64
-------
65
-------
TABLE 28
INCINERATOR PROCESS DESCRIPTION
.FOR RENDERING ROOM VENTS
PROCESS DESCR IPTION SPEC/PICA TION
The incinerator is to deodorize room ventilation gases from a dry rendering plant. The
plant is operated batchwise. The time required in the cooker for each batch is three hours.
Since two or three batches will be run each day, the incinerator will be in use for 8 to 12
hours daily.
Ventilation from the feed storage area is currently exhausted through the roof at a
height of 20 ft. Cooker gases are sent to a condenser located on the ground outside the
building. Effluent gases from the condenser are vented into a 30 ft stack. A 30 ft square area
is available for new equipment next to the location of the condenser and the stack. A four
inch concrete slab covers the area. Sufficient electric power is available at the site.
The incinerator is to be natural gas fired. Gas is available at 1.0 psig having the
following composition:
Component Volume %
CO 2 0.90
N2 0.38
O2 0.00
CH4 94.96
3.02
0.48
i-C4HJO 0.07
0.09
C5+ 0.10
100.00
Specific Gravity: 0.589 Higher Heating Value: 1034 Btu/SCF
This specification covers the incinerator, burner, a 30 ft stack, controls, and other
equipment included as a part of the incinerator, such as insulation, jacketing, etc. A suitable
control panel and two days startup service by a competent engineer should be included.
Incinerator operation and safety controls are to be designed to meet FIA insurance
requirements. The stack, controls, control panel, startup service, etc., should be considered
as auxiliaries.
Although specifications have been written for two efficiency levels at each plant size,
vendors' quotations should consist of only one quotation for each plant size with a
representation of the efficiency expected. Every effort should be made to achieve the
performance indicated by the high efficiency specification.
66
-------
TABLE 29
INCINERATOR OPERATING CONDITIONS
FOR RENDERING ROOM VENTS
SPECIFICATION
OPERATING CONDITIONS
Room Ventilation
Effluent Gas Rate, ACFM
Effluent Gas Temp., °F
%Air
Relative Humidity, %
Odor Concentration,
o.u./SCF
Odor Emission Rate,
o.u./min
Low Efficiency Case
Concentration @> Ground,
o.u./SCF
% Odor Removal
High Efficiency Case
Concentration @ Ground,
o.u./SCF
% Odor Removal
SMALL
8*
44
LARGE
3,000
90
~ 100
25
100,000
284 x 1O6
14,000
90
-100
25
100.000
7,520 x 106
93
93
*30 minute averages as calculated by Bosenquet-Pearson and Bosenquet-Carey-Halton.
67
-------
TABLE 30
INCINERATOR PROCESS DESCRIPTION
FOR COMBINED RENDERING VENTS
SPECIFICATION
PROCESS DESCRIPTION
The incinerator is to deodorize the total gases emitted from a dry rendering plant. The
plant is operated batchwise. The time required in the cooker for each batch is three hours.
Since two or three batches will be run each day, the incinerator will be in use for 8 to 12
hours daily.
Ventilation from the hoods and storage area is currently exhausted through the roof at
a height of 20 ft. Cooker gases are sent to a condenser located on the ground outside the
building. Effluent gases from the condenser are vented into a 30 ft stack. A 30 ft square area
is available for new equipment next to the location of the condenser and the stack. A four
inch concrete slab covers the area. Sufficient electric power is available at the site.
The incinerator is to be natural gas fired. Gas is available at 1.0 psig having the
following composition:
Component Volume %
CO2 0.90
N2 0.38
O2 0.00
CH4 94.96
3.02
0.48
i-C4Hw 0.07
n-C4Hw 0.09
C5+ 0.10
100.00
Specific gravity: 0.589 Higher heating value: 1034BW/SCF
This specification covers the incinerator, burner, 30 ft stack, controls, and other
equipment included as a part of the incinerator, such as insulation, jacketing, etc. A suitable
control panel and two days startup service by a competent engineer should be included.
Incinerator operation and safety controls are to be designed to meet FIA insurance
requirements. The stack, controls, control panel, startup service, etc., should be considered
as auxiliaries.
Although specifications have been written for two efficiency levels at each plant size,
vendors'quotations should consist of only one quotation for each plant size with a
representation of the efficiency expected. Every effort should be made to achieve the
performance indicated by the high efficiency specification.
68
-------
TABLE 31
INCINERATOR OPERATING CONDITIONS
FOR COMBINED RENDERING VENTS
SPECIFICATION
OPERATING CONDITIONS
Total Gas Stream
Effluent Gas Rate, ACFM
Effluent Gas Temp., °F
%Air
Relative Humidity, %
Odor Concentration,
o.u./SCF
Odor Emission Rate,
o.u./min
Low Efficiency Case
Concentration @ Ground,
o.u./SCF
% Odor Removal
High Efficiency Case
Concentration @ Ground,
o.u./SCF
% Odor Removal
SMALL
8'
46
LARGE
5,030
95
~99
23
103,000
484 x JO6
19,090
95
~99
23
103,000
1,836x 106
s*
46
> 93
>93
*30 minute averages as calculated by Bosenquet-Pearson and Bosenquet-Carey-Halton.
69
-------
TABLE 32
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR INCINERATORS FOR RENDERING COOKERS AND HOODS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other
(4) Total Cost
LA Process Wt.
Small
Large
High Efficiency
Small
2,030
101
1,918
1,970
6
93
8,750
787
_
71
2,750
893
2,090
494
600
170
_
930
475
1,225
19,235
Large
5,090
101
4,809
4,920
6
93
11,000
1,098
81
(J -L
3,188
1,015
2,485
633
712
220
_
930
475
1,225
23,062
70
-------
TABLE 33
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR INCINERATORS FOR RENDERING COOKERS AND HOODS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$6/hr
$8/hr
$6/hr
$0.011/kw-
50 . 8 0/MMBTL
LA Process Wt.
Small
.r
Large
High Efficiency
Small
780
48
828
384
166
550
158
0.1
6,032
6,032
7,568
1,924
9,492
Large
780
48
828
390
220
610
158
0.1
14,789
14,789
16,385
2,306
18,691
-------
TABLE 34
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR INCINERATORS FOR RENDERING ROOM VENTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other
(4) Total Cost
LA Process Wt.
Small
Large
High Efficiency
Small
3,000
90
2,891
2,960
6
93
10,000
890
_
_
2,813
933
2,230
540
631
185
-
930
475
1,225
20,852
Large
14,000
90
13,491
13,820
6
93
18,000
2,206
_
_
4,250
1,340
3,798
1,025
1,155
358
-
930
475
1,225
7
34,762
72
-------
TABLE 35
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR INCINERATORS FOR RENDERING ROOM VENTS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$6/hr
$8/hr
$6/hr
$0.011/kw
$0.80/1VMBT
LA Process Wt.
Small
hr
i
Large
High Efficiency
Small
780
48
828
390
220
610
158
0.4
8,736
8,736
10,332
2,085
12,417
Large
780
48
828
480
270
750
158
1.91
40,872
40,874
42,610
3,476
46,086
-g
CO
-------
TABLE 36
ESTIMATED CAPITAL COST DATA^
(COSTS IN DOLLARS)
FOR INCINERATORS FOR RENDERING COMBINED VENTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other
(4) Total Cost
LA Process Wt.
Small
Large
High Efficiency
Small
5,030
95
4,803
4,915
6
94
11,000
1,098
-
202
3,188
1,015
2,850
633
713
220
_
930
475
1,225
23,549
Large
19,090
95
18,240
18,670
6
94
19,500
2,693
_
248
4,750
1,488
4,600
1,210
1,280
438
_
930
475
1,225
38,837
74
-------
TABLE 37
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR INCINERATORS FOR RENDERING COMBINED VENTS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$6/hr
$8/hr
$6/hr
$.011/kw-
$.80/MVIBIU
LA Process Wt.
Small
IT
Large
High Efficiency
Small
780
48
828
384
186
570
158
0.1
14,539
14,539
16,095
2,355
18,450
Large
780
48
828
465
235
700
158
0.3
55,162
55,162
56,848
3,884
60,732
01
-------
FIGURE 15
CAPITAL COST OF INCINERATORS ONLY
FOR RENDERING PLANTS
co
cc
o
Q
CO
Q
<
CO
O
I
V)
O
O
2000 3000 5000 7000 10000
EXHAUST GAS RATE, ACFM
20000
76
-------
FIGURE 16
CAPITAL COST OF INCINERATORS
PLUS AUXILIARIES FOR RENDERING PLANTS
V)
DC
§
U.
O
Vi
O
<
w
O
8
2000 3000 5000 7000 10000
EXHAUST GAS RATE, ACFM
20000
77
-------
FIGURE 17
CAPITAL COST OF TURNKEY INCINERATOR SYSTEMS
FOR RENDERING PLANTS
50
co
cc
§
u.
O
co
O
CO
O
I
1
40
30
20
10
8
6
5
o.
2000 3000 5000 7000 10000
EXHAUST GAS RATE. ACFM
20000
78
-------
FIGURE 18
CONFIDENCE LIMITS FOR INCINERATORS PLUS
AUXILIARIES FOR RENDERING PLANTS
V)
cc
o
Q
CO
Q
CO
o
X
fe
O
O
2000
3000
5000
7000
10000
20000
EXHAUST GAS RATE, ACFM
79
-------
FIGURE 19
CONFIDENCE LIMITS FOR TURNKEY INCINERATOR SYSTEMS
FOR RENDERING PLANTS
CO
cc.
O
Q
it-
CD
CO
Q
I
O
X
te
O
O
20
10
2000
3000 5000 7000 10000
EXHAUST GAS RATE, ACFM
20000
80
-------
FIGURE 20
ANNUAL COSTS FOR INCINERATORS
FOR RENDERING PLANTS
100
V)
DC
O
Q
u.
O
W
O
x
V)
O
o
80
60
50
40
30
20
10
8
20
(OP
C/s
S <*
S
2?
.TOTAL
ERATINC
PITAL C
X
COST
JCOST
HARGE
V
PLUS
:s)
y
K S
D
^
X
Of
/
(ER
/
\T
.^r^F
.^r \^r^
/3s
/
NG COST
00 3000 5000 7000 10000 200
EXHAUST GAS RATE, ACFM
81
-------
REFERENCES
1. The Science of Meat and Meat Products, The American Meat Institute
Foundation, W. H. Freeman & Co., London, 1960.
2. Beef, Veal and Lamb Operations, The Committee on Recording of the
American Meat Institute.
3. Dillen, Clyde, Meat Slaughtering and Processing, Von Hoffman Press, St.
Louis, 1947.
4. Air Pollution Engineering Manual, U.S. Dept. of Health, Education, and
Welfare, Public Health Services Publication No. 999-AP-40, Anncenate,
1967.
5. Strauss, W., "The Development of a Condenser for Odor Control from
Dry Rendering Plants", Journal of the Air Pollution Association, 14:10,
Oct. 1964, pp. 424-426.
6. Barr, Allen, "From Waste Materials: Tallow and High Protein Meal",
Chemical Engineering, June 20, 1966, pp. 130-132.
7. Bates, R. W., "Edible Rendering", Journal of the American Oil Chemists
Society, 45, Aug. 1968, p. 420A-422A, 424A, 430A, 462A, 464A.
8. Pircon, L. J., and Wilder, O.H.M., "Odor Control by Catalytic Oxidation
of Renderer Exhaust Vapors", American Meat Institute Foundation
Bulletin No. 37, April 1955, Chicago.
9. Roland, P., Handbook on Offensive Trades, William Hodge, London,
1935.
10. Teller, A. J., "Odor Abatement in the Rendering and Allied Industries",
Journal of the Air Pollution Control Association, April 1963, p. 148, 149,
166.
11. "Double Stack Scrubber Effectively Reduces Odor from Blood Dryer",
Food Processing, June, 1971.
12. Posselt, H. S. and Reidies, A. H., "Odor Abatement with Potassium
Permanganate Solutions", Industrial and Engineering Chemistry, 4, March
1965, pp. 48-50.
13. Private Communication from Carus Chemical Company.
82
-------
o
I
o
o
3J
>
O
-------
2. THE PETROLEUM REFINING INDUSTRY FLUIDIZED BED
CATALYTIC CRACKING UNITS (with CO Boilers)
Petroleum Refineries process crude oil to produce a variety of products,
most of which are used for fuel. These products include:
Product Use
propane (LPG) fuel
butane (LPG) fuel
gasoline automotive fuel
kerosene jet fuel
142 distillate burner and diesel fuel
#6 residual oil burner fuel
asphalt road paving
These products are differentiated from each other more by their boiling
temperature range (which is related to the molecular weight and hydrocarbon
type) than any other single factor. Those fuels boiling at temperatures in the
gasoline range (200-400° F) and below command premium prices. Kerosene
(350-550° F) and distillate fuels (450-600° F) are desirable for jet and diesel
fuels as well as for heating purposes. However, those materials boiling above
600° F are generally undesirable products, and one objective of refinery
operation is to minimize them. Catalytic Cracking is the principal process used
to convert high boiling point hydrocarbons into more valuable lower boiling
point materials.
A typical crude petroleum may contain as much as 70% high boiling point
materials. After the gasoline, kerosene and distillate oils have been fractionated
out of crude petroleum, the remaining materials are fractionated in vacuum
distillation columns to remove asphalt (the very heaviest portion of the crude
oil). The heavy distillate material is called gas oil. Cracking of this material to
reduce the molecular weight and boiling point may be accomplished thermally
(by the application of heat without a catalyst), in fixed catalyst beds, in
moving beds or in fluidized beds. Because cracking is accompanied by the
formation of very heavy byproduct hydrocarbons called coke, the fluidized or
moving bed processes, in which the catalyst can be regenerated by a continuous
removal of the coke, are widely used in the petroleum refining industry to
produce gasoline and distillate components from gas oils and deasphalted
stocks. As of January 1, 1971, the installed capacity for catalytic cracking units
amounted to 4,512,545 barrels per stream day* of fresh feed for all units in
253 U.S. refineries.<1)
"Barrels per stream day is the usual unit of flow in petroleum refining. This unit, abbreviated BPSD, is the
number of 42-gallon barrels processed per day of operation. Occasionally the average number of barrels
processed per day over a typical year is used. This designation is barrels per calendar day, or BPCD. The
BPCD figure takes into account a period of down-time for service which ordinarily amounts to two weeks
per year. Thus the BPCD capacity of a FCC unit is about 50/52 or 96% of the BPSD capacity.
83
-------
This represents 37.5% of the total amount of crude oil processing capacity
in the U.S. as of January 1, 1971.(1)
Three general types of moving bed catalytic units are used in the United
States. These types and their installed capacities as of January 1, 1970 are as
shown in Table 38.
TABLE 38
INSTALLED CAPACITIES OF THE THREE TYPES
OF CATALYTIC CRACKING UNITS
Combined Feed Percent
Capacity (BPSD) (2> Of Total
Fluid Catalytic Cracking (FCC)
Thermofor Catalytic Cracking (TCC)
Houdriflow Catalytic Cracking (HCC)
5,007,470
669,870
186,500
85.4
11.4
3.2
5,863,840
100.0
TABLE 39
SCHEMATIC REPRESENTATION OF CRACKING REACTIONS13'
Charge Stock C30H60 (Heavy Gas Oil)
+
*• Cracked Stock C14H28:CH2 (Heavy Cycle Oil)
t
Additional Cracking C2Hg + (C4Hg + CgH18 + CgH12:CH2)
(gas) (gasoline)
Polymerization
Coke Formation
CHo-CH • CHiCH ' CH-3 + Ci^Hoo'CHo
(Gum Forming Material) (Heavy Cycle Oil)
C60H60
84
-------
In this table, the combined feed capacity is used. This includes some
partially cracked heavy cycle oil which is recycled back into the process. The
"size" or capacity of catalytic cracking units is generally given in terms of the
combined feed rate.
Each of the above types of catalytic cracking units employs the same
general process principals and feed stocks to produce similar products.
Powdered catalysts which can be maintained in a fluidized state by the flow of
gases upward through the catalyst beds are used in FCC units while large beads
of catalyst are used in the TCC process for moving bed operation.
As noted in the above tabulation, the FCC type dominates and no TCC or
HCC units have been sold for about 10 years in this country. Therefore, the
remainder of this discussion will center on the FCC process only.
PROCESS DESCRIPTION
FCC units of all types are essentially comprised of a reactor, a regenerator
and product separation equipment, as shown in Figure No. 21. The relative
position of reactor and regenerator installation may vary among various process
installations. The reactor is either located above or adjacent to the regenerator.
The relative positions are important only in that the catalyst is circulated by
"hydrostatic" pressure head developed by the fluidized beds of catalyst.
Fresh feed stock and recycle stock are charged separately or as combined
feed to the reactor section. The feed is commingled in a riser with hot
regenerated catalyst removed from the base of the regenerator. In the riser, the
cracking reaction is initiated and a catalyst-hydrocarbon vapor mixture is then
introduced into the reactor section of the unit where a fluidized bed of catalyst
may be maintained. The combination of catalyst, temperature and time cause
the hydrocarbon to undergo a cracking reaction which produce products of
lower boiling point than the charge stock. In most new units the design causes
all of the reaction to occur in the riser. The riser then either discharges into the
reactor vessel or directly into the cyclones contained in this vessel. No bed is
maintained in the reactor. In addition to the new units, many older units have
to be converted to this type of design. However, not all of the reactions lead to
desirable products. A fraction of the combined feed is converted into
byproducts even heavier than the feed stock, which will not vaporize and leave
the surface of the catalyst. This carbonaceous residue on the catalyst — called
coke - is composed mainly of carbon, hydrogen, sulfur and oxygen.
A simplified picture of the overall reactions taking place in cracking
reactors'3' is shown in Table 39.
85
-------
TABLE 40
TYPICAL OPERATING CONDITIONS FOR
A MEDIUM-SIZE FCC UNIT
Feed Rate, BPSD
Fresh Feed 40,000
Recycle Feed 10,000
Total Feed 50,000
Operation Ranges
Catalyst/Oil Weight Ratio 17
Catalyst Circulation Rate. Tons/hr. 4,500
Reactor
Temperatu re, ° F 913
Pressure, psig 22.0
Regenerator
Tern peratu re, ° F 1,240
Pressure, psig 27.5
Carbon Burning Rate, Ib/hr 33,000
TABLE 41
TYPICAL PROPERTIES OF FRESH AND
EQUILIBRIUM FCC CATALYSTS
Fresh Equilibrium
Catalyst Catalyst
Composition, wt. %
Si 35.0 34.3
Al 13.2 12.9
O 51.8 50.8
C (from coke) - 1.9
H (from coke) - 0.1
Total 100.0 100.0
Particle Size Distribution*5)
(microns)
<20 2 0
<40but>20 18 12
<80 but > 40 50 76
> 80 J30 12
100 100
Geometric Mean Diameter, microns 60 60
Particle Density, g/cc 1.3 1.5
Apparent Bulk Density, Ib/ft3 40 44
86
-------
A portion of the fluidized catalyst separates by gravity from the cracked
components of hydrocarbon vapor in the reactor. The cracked components are
passed through one, two, or three stage cyclone separators to remove entrained
catalyst and then charged to product fractionation equipment. The separated
fluid catalyst containing deposit of tar and polymers, or coke, flows by gravity
through a steam stripper. In the stripper the catalyst is contacted with steam to
remove volatile materials from the catalyst prior to its introduction in the
regenerator. The volatile matter and much of the steam goes back into the
reactor. The catalyst bed in the regenerator is contacted with air to burn coke
deposits from the catalyst. This produces CO, CC^ and HoO as the reaction
products, and supplies hot regenerated catalyst to be comingled with the feed
hydrocarbon.
Products of combustion, or regenerator flue gas, are passed through either
two or three cyclone stages to effect catalyst separation before processing for
heat recovery. Modern FCC unit regenerators run from 1150 to 1350° F exit
gas temperature. Typical FCC operation conditions for a medium sized unit
might be as shown in Table 40.
The products of combustion are at a sufficiently high temperature that
heat recovery in some form is usually economical. The heat recovery is usually
accomplished using a gas heat exchanger and/or a carbon monoxide (CO) boiler
to produce steam; however, a few FCC units use power recovery turbines as
well as steam generation. A gas heat exchanger alone is used on some FCC units
and consists simply of a shell and tube heat exchanger to produce steam by
absorption of some of the sensible heat of the flue gas prior to discharge to the
atmosphere. A CO boiler is essentially a furnace which utilizes the sensible heat
of the flue gas and the heat of combustion of carbon monoxide to produce
steam. While high carbon monoxide concentrations are present in regenerator
flue gas, supplementary fuel is usually needed to support combustion.(4) Many
CO Boilers have been added because of regulations limiting CO emissions rather
than because of the economics of heat recovery. The FCC unit illustrated in
Figure No. 21 uses both a flue gas heat exchanger and a CO Boiler.
Catalyst used in FCC units may be of several types. These catalysts are
fine powders of synthetic or natural materials of silica-alumina composition. In
recent years, the use of "molecular sieve type" catalyst has grown substantially
due to the improved activity (the ability to bring about the desired cracking
reaction) and stability (the retention of activity for a long time) of these
materials. The sieve catalysts are synthetic aluminosilicate materials processed
to give special crystalline structures. Some of the properties of typical fresh
(unused) and equilibrium (used) FCC Catalysts are listed in Table 41.
87
-------
00
03
REACTOR
REGENERATOR
FRACTIONATOR
STACK
CO BOILER
ELECTROSTATIC
PRECIPITATOR
CYCLONE
REACTOR
CATALYST
STRIPPER
STEAM
CLARIFIED
OIL
STEAM
SLURRY
GAS AND GASOLINE
TO CONCENTRATION
UNIT
AIR
CHARGE
STOCK
ENE
RATOR \
\
fc
>
/
/
(
^
iC 1 1 LCK
lOMBUSTION
AIR
iniM
-*
V
1
j
(1 1
1
* *
WATER
t
1
k
-<
—*t — ,
FRACTIONATOR
LIGHT ^
CYCLE OIL
HEAVY
CYCLE OIL
FIGURE 21
FLOW DIAGRAM OF FCC UNIT
-------
FEED MATERIALS AND PRODUCTS
Feed materials for FCC units are comprised of a variety of high molecular
weight hydrocarbon fractions. The most common charge material is vacuum
distilled gas oil. However, deasphalted* oils and some cracked materials
produced by thermal cracking or related processes such as visbreaking or coking
are also processed.
Products from FCC units consist of light hydrocarbon gases, gasoline,
distillate and heating oils. The hydrocarbon products all leave the reactor as
vapors which pass through the cyclones to separate catalyst and return it to the
reactor. The mixed products are cooled and part of the product condensed.
The liquid condensate is pumped and the uncondensed gases are compressed to
about 250 psig and a complex absorption-fractionation system is used to
separate the total product into the following fractions:
Noncondensable gases
Hydrogen
Methane
Ethane
Ethylene
Inert Gases
LPG
Propane
Propylene
Butanes (optional)
Gasoline
Light Cycle Oil (#2 fuel oil)
Heavy Cycle Oil (Returned to the reactor or blended into #6 fuel oil)
Each of these products is subjected to additional treatment or processing
before release as salable product. Table 42 lists the product distribution'61 for
typical FCC operations.
From the standpoint of air pollution control, the non-hydrocarbon feed
materials - catalyst and air - are of significance.
Catalyst is added to the process for two reasons. Losses reduce the
inventory in the unit and would cause reduced conversion if the lost material
were not replaced. The principal functions of the internal cyclones is to prevent
the loss of excessive catalyst with the gas, so that fresh catalyst additions can
be minimized.
•This is a term for heavy oils from which the asphalt has been removed t>v solvent extraction rather
than by vacuum distillation.
89
-------
TABLE 42
OPERATING RESULTS
FLUID CATALYTIC CRACKING PROCESS l61
Catalyst
Conversion
Yields (Volume Percent):
Debutanized Gasoline
Light Cycle Oil
Heavy Cycle Oil
Butylenes
Butanes
Propylene
Propane
Fuel Gas, FOE"
*Fuel oil equivalent basis
High AI203 Zeolite Zeolite
70
44.43
18.54
11.45
8.90
8.13
6.96
3.41
5.69
70
56.76
21.00
9.0
6.42
7.37
5.84
2.65
3.10
80
60.11
12.24
7.76
8.32
9.49
8.00
3.43
4.48
TABLE 43
CALCULATED COMPOSITION OF GAS
FROM
FCC REGENERATOR AND CO BOILER
From
FCC Regen.
CH4
CO
CO2
N2
02
Water Vapor
Vol. ^
-
9.5
10.0
69.7
1.0
9.6
YO SCFM
-
8,550
8,940
61,300
880
8,610
Aux. Comb. Total Total
Fuel Air to from
CO Boiler CO Boiler
SCFM SCFM SCFM SCFM
1,600 - 1,600
8,550
8,940 18,940
25,400 86,700 86,700
7,460 8,340 880
8,610 11,720
Vol. %
-
-
16.0
73.4
0.7
9.9
100.0 88,280 1,600 32,860 122,740 118,240 100.0
90
-------
The cyclones must retain not only the powdered catalyst of the particle
size range added to the unit, but they must also limit the loss of fine material
produced by attrition or breakage of the catalyst particles. Modern cyclones
serve this process requirement satisfactorily, and often operate at efficiencies
over 99.99% in multistage systems.
In addition to physical loss of catalyst from the FCC system there is a loss
of activity which takes place gradually. This must also be corrected by the
addition of new, fresh catalyst to the unit. The requirement for new catalyst
addition to maintain activity runs from about 0.1 to 0.3 Ib of new catalyst per
barrel of combined feed.
In order to add this much catalyst to the system, an equivalent volume
must be removed from the system. The mechanisms available for removal are:
1. loss through the regenerator cyclones
2. loss through the slurry settler or the reactor cyclones
3. manual withdrawal
In most cases cyclone losses are substantially less than the required
catalyst addition rate and it is necessary to manually withdraw some catalyst.
The withdrawals and additions of catalyst may be continuous,-or intermittent.
NATURE OF THE GASEOUS DISCHARGE
The effluent from the FCC regenerator consists of the products of
combustion of coke burned off the catalyst with the regenerator air. The
important variables in establishing the gas flow rate and composition are:
1. the rate of coke burning
2. the completeness of combustion of carbon to C02-
The coke burning rate is influenced by a number of variables, some of
which are properties of the charge stock, and others which are under the
control of the operators. The coke make tends to run between 5 and 10
percent by weight of the fresh feed. Operation with very heavy charge stocks,
or poorly deasphalted materials tends to increase the coke make. Operation at
very high catalyst/oil ratios also tends to raise the coke make.
However, it is not possible to allow the coke burning rate to vary
independently of other considerations. The size of the regenerator air blower
91
-------
may limit the throughput of feed. For example, if the regenerator air blower is
limited to 50,000 SCFM, the coke burning rate will be limited to around
23,000 Ib/hr. Operating conditions which tend to produce coke faster than this
rate cannot be sustained. The unit is said to be limited by coke burning
capacity if the charge rate is limited in this way.
Similarly, the necessity for the entire unit to run in heat balance places
restrictions on the rate at which coke can be burned off of the catalyst. It is
necessary that the heat produced by burning coke in the regenerator just equal
the heat leaving with the flue gas, plus that absorbed by the processes taking
place in the reactor.
Changes in the feed stock, the type of catalyst being used and the desired
product mix all tend to produce changes in the coke make and the heat
balance. For this reason it is desirable to size the gas treating equipment for the
maximum coke burning rate which can be handled; that is, for the maximum
rate at which flue gas can be generated with the regenerator air blower at its
maximum capacity.
In order to establish the gas flow to a collector following a regenerator,
but upstream of any CO Boiler, it is necessary to know:
1. the maximum air blower capacity
2. the ratio of hydrogen to carbon in the coke
3. the ratio of CO to CO2 in the flue gas.
The blower capacity is specified as a part of the FCC unit design, and may
be used for selection of abatement equipment. The actual maximum air rate
established by operation of the FCC unit is more reliable and should be used if
it is available.
The ratio of hydrogen to carbon in the coke influences the weight of coke
which can be burned per standard cubic foot of air supplied by the blower.
Usually this ratio runs around 7 to 9 wt. % hydrogen in the total coke, or
nearly a 1:1 atomic ratio of hydrogen to carbon.
The ratio of CO/C02 is important for those cases where the gas cleaning
equipment receives gas directly from the regenerator, whether or not a CO
Boiler is used. The ratio ordinarily runs close to 1:1, or one mol of CO per mol
92
-------
of CC>2. However, regenerator design and operating conditions can influence
the ratio significantly. Increases in residence time in the regenerator tend to
increase the ratio, as the carbon tends to burn to CC^ which in turn reacts with
carbon according to
CO2 + C -> 2CO.
The conditions specified by the FCC unit designer may be used, but actual
operating experience is preferable for existing units.
Where the CO Boiler is located ahead of the gas cleaning equipment, as
shown in Figure 21, the design ratio of CO/CC^ is significant only to the
extent that it can be used to calculate how much additional air will be required
for combustion of the CO. In order to properly burn the CO, auxiliary fuel
must be added to achieve the proper combustion temperature. Therefore, when
designing gas cleaning equipment to follow a CO Boiler, the design exhaust gas
conditions from the CO Boiler should be used, and these modified by actual
operating experience whenever it is possible.
The composition of major gas components for flue gases from a FCC
regenerator and from the corresponding CO boiler are calculated on the basis of
a 1:1 ratio of hydrogen to carbon in the coke, and a 0.95:1 ratio of CO/C02 in
the effluent from the regenerator. The results are shown in Table 43 for a FCC
unit with a coke burning capacity of 33,000 Ib/hr. Sufficient auxiliary fuel is
added to bring the total heat content of the feed gases to 60 BTU/SCF of total
gas fired to the boiler. Values lower than about 50 are not ordinarily capable of
sustaining combustion. Typically, larger amounts of auxiliary fuel and excess
air are used to insure reliable operation.
NATURE OF GASEOUS CONTAMINANTS
Regeneration of catalyst in FCC units is carried out by burning coke off
of the catalyst with air, and results in the formation and discharge of air
contaminants. These contaminants arise due to thermal and catalytic oxidation
reactions with the coke constituents, which include carbon, hydrogen, sulfur
and nitrogen containing compounds. Particulate contamination also is caused
by fine or low micron size materials present in the initial catalyst charge and
generated by attrition of the catalyst during processing. Typical amounts of
contaminants produced by regeneration shown in Table 44(4> have been
estimated based on a number of FCC units.
93
-------
TABLE 44
TYPICAL CONTAMINANT RATES FROM FCC UNIT REGENERATORS
Contaminant
Carbon monoxide
Sulfur dioxide
Hydrocarbons
NOX as nitrogen dioxide
Particulate matter
Ammonia
Sulfur trioxide
Aldehydes as formaldehyde
Cyanides as hydrogen cyanide
Ib/hr
36,940
828
351
122
99.6
87.2
49.7
32.8
0.50
38,510.8
TABLE 45
EMISSIONS FROM FCC REGENERATOR
Ib/hr
Mol/hr
Vol. %
27,252,730 13,523
Combustion Air, SCFM
Flue gas, SCFM 88,280
Flue gas, ACFM @ 1200° F 276,300
100.0
PPM
C02 61,100
N2 27,132,000
02 4,410
Water Vapor 23,710
(Contaminants) (38,510)
CO 36,940
S02 828
HC(asC3) 351
NOx(asN02) 122
Particulate 99-6
NH3 87.2
S03 49.7
Aldehydes (as
formaldehyde) 32.8
Cyanides (as HCN) 0.5
1,388
9,333
137.7
1,317
(1,348)
1,319
11.4
8.0
2.70
—
5.13
0.62
1.08
0.018
10.0
69.7
1.0
9.6
9.5
0.093
0.057
0.019
—
0.035
0.005
0.007
0.0002
-
-
-
—
930
570
190
(0.13gr/SCF)
350
50
70
2
94
-------
These can be placed in better perspective for consideration as air
pollutants by casting them in terms of their concentration in the regenerator
flue gas. This is done on the basis of a hypothetical regenerator with 9% CO by
volume in Table 45.
The carbon monoxide (CO) waste heat boiler converts essentially all of
the carbon monoxide to carbon dioxide. In addition, other combustibles such
as hydrocarbons, ammonia, aldehydes and cyanides are also oxidized in the CO
Boiler, and leave as h^O, CO2 and ^.
After conversion of carbon monoxide in the CO Boiler, the principal
contaminant remaining is particulate matter. This particulate matter is
comprised of catalyst particles which were passed through the cyclone
separator. The amount of particulate can vary widely with the type of catalyst
used, the operation conditions and the number, as well as the condition of
cyclone stages used. Particulate emission rates for a number of FCC unit stacks
were reported by Sussman(7) as follows:
Total particulate,
Ib/hr*
57.50
61.00
181.00
58.70
28.30
6.42
The chemical composition of the solids discharged from the FCC
regenerators differ little from the composition of equilibrium catalyst, as
shown in Table 41. The properties of the particulate contaminants of the
greatest importance with respect to air pollution abatement are given in Table
46.
*Note: Plant capacities were not available.
95
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POLLUTION CONTROL CONSIDERATIONS
FCC units with CO Boilers ordinarily require additional particulate
collection equipment in order to achieve acceptable pollutant emission. While
adding an external cyclone stage will reduce particulate emissions, and may
produce relatively clear stacks on small units, optimum results require more
efficient collection devices. Electrostatic precipitators have been widely used
on FCC units to provide high particulate removal efficiencies. Wet scrubbers of
the high energy Venturi type also offer the capability for acceptable particulate
reduction; however, these have not been used to date for FCC service. Fabric
collectors are considered unsuitable because of the temperature variability.
Electrostatic Precipitators
Electrostatic precipitators can be used efficiently for particulate collection
on FCC units. Power requirements are low and in the range of 35 KVA for
small units to 140 KVA for the larger units141. Precipitators are installed either
ahead of or after the CO Boiler on FCC units. With installation ahead of the CO
Boiler, a flue gas heat exchanger is required to reduce the gas temperature
entering the precipitator.
The wide range of possible pressures, temperatures and moisture
concentrations which can be selected makes the application of electrostatic
precipitators to FCC units particularly challenging. The size of the unit is
minimized by installation on the upstream side of the CO Boiler. This is due to
the fact that the auxiliary fuel and combustion air do not pass through the
precipitator. However, mechanical design considerations require the installation
of a gas cooler or steam generator to reduce the temperature before it is
introduced into the casing.
Design for operation at the regenerator pressure further reduces the
volume of gas to be treated, but the cost reduction is more than offset by the
high cost of the casing.
The temperature chosen for the outlet of the gas cooler is of prime
importance. Temperatures in the 600 to 700° F range provide a good
compromise between optimizing mechanical design, which becomes more
difficult at higher temperatures, and acceptable resistivity of the collected
catalyst, which generally improves with increasing temperature.
Generally, the resistivity of the particulate matter collected is too high for
96
-------
TABLE 46
TYPICAL PROPERTIES OF FCC CATALYST FINES
PARTICLE SIZE DISTRIBUTION RANGE
Size, Microns Fine Coarse
< 10 77 50
> 10 but < 20 21 24
> 20 but < 40 2 23
> 40 but < 80 Trace 3*
100 100
Electrical Resistivity, ohm-cm'9' 5x 1011
at350°F,25%H20
same with ammonia added 1.4.x1010
Density, g/cc of particles 1.6
Density (apparent bulk density) 25-30
Ib/ft3
*When more than 3 wt. % is greater than 40 microns, there is usually something
wrong with the cyclone system.
97
-------
optimum performance of the precipitator without one or more circumstances
operating to reduce the resistivity. Some of the factors effective in bringing
about decreased resistivity, or of "conditioning" the particulate matter are
1. High carbon or coke content
2. High gas temperature
3. Presence of adsorbable electrolyte materials, such as
a. Ammonia
b. Ammonium Sulfate
c. Diethanolamine
In the case of electrolyte conditioning agents, water vapor in the effluent
also contributes somewhat to improved performance. High temperatures tend
to reduce the effectiveness of electrolytes and water vapor, however.
Where the precipitator is installed after the CO Boiler, a significantly
higher gas volume must be handled, but the precipitator casing may be designed
for near-atmospheric pressure, and many of the mechanical problems associated
with pressure design can be eliminated.
Temperature is an important variable in the case of installation after
the CO Boiler. High temperatures cannot be used because of the loss in boiler
efficiency. The same basic factors affecting resistivity operate at this location,
but with some significant differences.
1. The particulate matter is burned cleaner; there is less coke remaining
on it.
2. The natural "conditioning agents" present in FCC gas such as NHg
and SOg tend to decompose irvthe furnace.
3. The lower pressure reduces absorption of water vapor and
electrolytes.
These factors all tend to make the resistivity higher and the dust more
difficult to collect at atmospheric pressure following the CO Boiler. In many
installations, ammonia injection is used ahead of the precipitator to decrease
electrical resistivity of the collected solids in order to obtain high particulate
removal efficiency.
98
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Wet Scrubbers
High energy wet scrubbers offer an alternative abatement approach.
Energy in the flue gas stream is available to supply the power requirements for
efficient scrubbing. Both water consumption and steam plume formation will
depend to a large extent on inlet gas temperatures at the scrubbers. For this
reason it is desirable to locate these in a manner to process flue gas with the
lowest possible temperature.
Two approaches suggest themselves here. One involves the use of a
Venturi scrubber ahead of the CO Boiler preceded by a high efficiency steam
generator to reduce the regenerator flue gas temperature to a low level, say
350° F. The Venturi scrubber would then operate as a partial throttling device,
and pressure differences of 100 or more inches water column could be utilized
without any cost for gas moving equipment or power. Operation at this
velocity would, however, make the scrubber subject to high erosion rates. This
is particularly significant since continuous operation for periods as long as three
years is normal practice. The CO Boiler would require more auxiliary fuel to
sustain combustion and would operate at a somewhat lower efficiency level.
However, the two largest drawbacks associated with scrubbers (the high power
cost and the steam plume formation) would be eliminated. Very high
efficiencies can be projected for scrubbers at this energy level.
The other approach involves application of the scrubber to the CO Boiler
discharge. Here it is unlikely that the boiler will be capable of withstanding the
pressure required to push the gas through the scrubber (40 inches w.c.
minimum, or about 1.3 psi). Therefore a fan capable of moving the gas through
the scrubber and a heat exchanger or reheat burner will be required.
In addition, several problems are associated with the handling and disposal
of the catalyst/water slurry produced by the scrubber. The catalyst cannot be
returned to the regenerator. To do so would set up a high recirculation rate
between the regenerator and the pollution control equipment and defeats the
purpose of the pollution control equipment. In most cases, the disposal of the
water will be difficult, and water recycle will be required in the majority of
cases.
Due to the large size of FCC units and the large volumes of regenerator
flue gas produced, space considerations are a prime factor. The piping and
ductwork required to install a precipitator represents a major portion of
installation cost, and convenience of location can, therefore, affect these costs
significantly. Wet scrubber installations will be similarly affected. They will,
however, require less space adjacent to the FCC than precipitators since
thickeners and/or settling ponds may be located at some distance from the
FCC.
99
-------
Application of either electrical precipitators or high energy wet scrubbers
should both be evaluated economically for the specific installation involved.
Precipitators can be of carbon steel construction while corrosion and erosion
resistant construction is required for wet scrubbers. The precipitator provides a
dry collection of particulate and presents a dry particulate disposal
consideration. Wet scrubbing will recover a water slurry stream containing
catalyst particulate which will also require disposal consideration and possibly
additional processing. However, wet scrubbers can be used for gaseous
pollution control as well as particulate control, and this may be an important
consideration where SC>2 emissions must be abated.
There is some potential for use of the particulate collection device to
collect catalyst for return to the process. However, this is likely to be a
marginal operation. First the catalyst would have to be classified and that
portion smaller than 20 microns discarded. This step is necessary to prevent
recirculating small particles between pollution control device and regenerator.
For example, a 60 Ib/hr catalyst loss, if fully returnable to the process, would
have an operating credit of
60 Ib/hr x 24 hr/day x $400/ton
2000 Ib/ton =
This is likely to be unrealizable because:
1. Most of the collected material is too fine for return to the
regenerator, and
2. The amount which must be discarded to accommodate the
desired activity level is likely to be 60#hr or more.
However, the potential for some economic payback may be significant for
special cases.
100
-------
SPECIFICATIONS AND COST
Equipment specifications have been written only for the case of control
by an electrostatic precipitator. Those specifications appear in Tables 47 and
48. Cost data generated from those specifications appear in Tables 49 and 50.
Capital costs are presented in Figure 22. The primary collector averages about
one-third of the total system price. Turnkey installation prices are shown in
Figure 24 along with the 75% and 90% statistical confidence limits. Confidence
limits for the precipitator alone are shown in Figure 25.
One quotation was also received for tertiary cyclones operating in the
same service. Cost data from this quote are presented in Tables 51 and 52. The
capital costs are shown in Figure 26.These costs show much greater sensitivity
to plant size than do the comparable costs for precipitators. They also indicate
that the installation cost is a lower fraction of the total system price.
Operating costs for precipitators are presented in Figure 23. Operating
costs for cyclone are shown in Figure 27. As in the case of capital costs,
operating cost of cyclones is much more sensitive to size than precipitators.
Cyclone costs fall between the costs of precipitators operating at low and high
efficiency.
101
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Table 47
ELECTROSTATIC PRECIPITATOR PROCESS DESCRIPTION FOR
FLUIDIZED BED CATALYTIC CRACKING UNIT SPECIFICATION
A single electrostatic precipitator is to treat the regenerator flue gas from a
conventional FCC unit with a CO Boiler. The FCC unit processes a combination of
atmospheric and vacuum gas oils from a typical midcontinent crude oil.
Both the FCC and CO Boiler are new, and are expected to operate within the design
limitations given in the attached specifications. The regenerator air blower is to be assumed
to limit the carbon burning rate to the level indicated. Regenerator superficial velocity is 2.5
FPS maximum. Catalyst is to be "high alumina" silica-alumina initially, but molecular sieve
type catalysts will be used in the future.
The flue gas from the regenerator passes through a pressure reducing manifold and slide
valve to reduce the gas pressure from approximately 25 psig to approximately 6" w.c.
pressure before introduction into the CO Boiler. Air and natural gas auxiliary fuel are also
supplied to the burners.
The precipitator is to continuously reduce the paniculate content of the flue gas
leaving the CO Boiler to the levels specified. A minimum of two fields in the direction of gas
flow must be provided to reduce the effect of an electrical failure.
The precipitator must be equipped with hoppers capable of retaining the dust collected
over 24 hours of normal operation. During normal operation the hoppers will be emptied by
a screw conveyor discharging into a dust bin, with a 15 ft elevation above grade to allow for
truck loading. The storage bin will be located adjacent to the precipitator and will be sized
for seven days storage capacity. Automatic voltage control shall be provided to maximize
operating efficiency. Rappers shall be adjustable both as to intensity and rapping period. The
precipitator shall be equipped with a safety interlock system which prevents access to the
precipitator internals unless the electrical circuitry is disconnected and grounded. A safety
interlock shall be provided to automatically de-energize the precipitator in the event of
flame failure in the CO Boiler.
A model study for precipitator gas distribution will be required. The precipitator, dust
handling equipment and auxiliaries are to be included in the vendors proposal. The stack will
be supplied by the CO Boiler contractor.
102
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Table 48
ELECTROSTATIC PRECIP1TATOR OPERATING CONDITIONS FOR
FLUID/ZED BED CATALYTIC CRACKING UNIT SPECIFICATION
Two sizes of electrostatic precipitators are to be quoted for each of two efficiency
levels. Vendors quotation should consist of four separate and independent quotations.
Unit Size, BPSD
Fresh feed
Recycle feed
Combined feed
Catalyst circulation rate,
ton/hr.
Coke burnoff rate, Ib/hr
Process weight, Ib/hr
CO Boiler outlet gas
Flow, ACFM
Temp., °F
% Moisture
Precipitator inlet loading,
Ib/hr
Precipitator inlet loading,
gr/ACF
Small
(low loading)
9,400
1,000
10,400
1,040
8,000
2,200,000
70,000
470
9.9
27
0.045
Large
(high loading)
40,000
10,OOO
50,000
5,000
38,000
10,000,000
335,000
470
9.9
278
0.10
Case 1 — Moderate Efficiency
Outlet loading, Ib/hr
Outlet loading, gr/ACF
Efficiency, wt. %
40
0.10
No Collection
Required
Case 2 - High Efficiency *
Outlet loading, Ib/hr
Outlet loading, gr/ACF
Efficiency, wt. %
9
0.015
70**
40
0.014
86**
43
0.015
85**
*NOTE: Removal of paniculate matter at 470° F does not assure a color free effluent.
**This specification may be satisfied by a third stage mechanical cyclone.
***Process weight is the weight of catalyst circulated to the regenerator.
103
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TABLE 49
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR ELECTROSTATIC PRECIPITATORS FOR
FCC UN ITS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
( 1 ) Gas Cleaning Device Cost
(2) Auxiliaries Cost ~>
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment ^
(3) Installation Cost >,
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other
>
>
(4) Total Cost
LA Process Wt.
Small
70,000
470
9.9
0.045
27
70,000
470
9.9
0.045
27
none
Large
335,000
470
9.9
0.10
278
335,000
470
9.9
0.014
40
86
249,333
44,667
487,167
781,167
High Efficiency
Small
70,000
470
9.9
0.045
27
70,000
470
9.9
0.015
9
67
78,233
25,934
159,400
263,567
Large
335,000
470
9.9
0.10
278
335,000
470
9.9
0.015
42
85
249,333
44,667
487,167
781,167
104
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TABLE 50
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS
FOR FCC UNITS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
(Ammonia)
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8,000
$6/hr
$8/hr
$6/hr
$.011/kw-l
$.03/lb
LA Process Wt.
Small
-
-
-
-
-
_
r
-
:
Large
300
TOO"
1,968
500
2,468
7,400
7,400
25,052
8,940
33,992
44,160
78,117
122,277
High Efficiency
Small
300
300
672
150
822
2,275
2,275
15,675
2,160
17,835
21,232
26,357
47,589
Large
300
300
1,968
500
2,468
7,400
7,400
25,052
8,940
33,992
44,160
78,117
122,277
o
Ol
-------
O
X
CO
O
O
FIGURE 22
CAPITAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR FCC UNITS
700
600
500
400
300
CO
cc
j 200
_i
O
Q
100
80
60
40
30
TURNKEY
INSTALLATION
COLLECTOR
PLUS
AUXILIARIES
COLLEC
ONLY
OR
10
20
30
40 50 60
COMBINED FEED RATE, THOUSANDS
OF BARRELS PER STREAM DAY
106
-------
FIGURE 23
ANNUAL COSTS FOR ELECTROSTATIC
PRECIPITATORS FOR FCC UNITS
300
200
oo
tr
o
o
to 100
CO
O
I
80
g 60
o
50
40
30
20
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
40 50 60
COMBINED FEED RATE, THOUSANDS
OF BARRELS PER STREAM DAY
107
-------
1000
900
to
cc
8
u.
o
700
600
500
< 400
O
X
I"
o
300
200
100
FIGURE 24
CONFIDENCE LIMITS FOR CAPITAL COST OF INSTALLED
ELECTROSTATIC PRECIPITATORS FOR FCC UNITS
.^—^f
*f
&
90%
75%
MBAM/
75%,
/
90%
20
30
.'
40 50 60
COMBINED FEED RATE, THOUSANDS
OF BARRELS PER STREAM DAY
108
-------
400
FIGURE 25
CONFIDENCE LIMITS FOR CAPITAL COST OF
PRECIPITATORSONLY FOR FCC UNITS
50 60
COMBINED FEED RATE, THOUSANDS
OF BARRELS PER STREAM DAY
109
-------
TABLE 51
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR TERTIARY CYCLONES
FOR FCC UNITS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s>
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other
(4) Total Cost
LA Process Wt.
Small
1,200
28.000
is.o
0.09
27
34,500
1,175
28,000
15.0
_
-
-
Large
1,200
133,300
15.0
0.2
278
164,000
1,175
133,300
15.0
O.OlliP
41.1
85.2
563,300
25,000
22,500
55,000
18,000
-
-
-
4,000
_
4,100
-
1,500
-
693,400
High Efficiency
Small
1,200
28,000
15.0
0.093
27
34,500
1,175
28,000
15.0
o.oogF-1
5.7
78.9
ss^oo0"1
12,000
5,100
12,500
4,100
-
-
-
1,000
„
900
-
1,500
-
122,300
Large
1,200
133,300
15.0
0.2
278
164,000
1,175
133,300
15.0
O.Oltf
' 41.1(2
85.2C2
563,300J
25,000
22,500
55,000
18,000
-
-
-
4,000
4,100
_
1,500
_
693,400
(1) Based on flow leaving CO Boiler and Cyclone pressure drop of 1.3 psi
(2) Could be designed for 40 Ib/hr at slightly higher pressure drop
(3) This device normally installed ahead of CO Boiler, 40% of the weight of the gas leaving the
CO Boiler was assumed at the cyclone
110
-------
TABLE 52
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR TERTIARY CYCLONES
FOR FCC UNITS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8,000
LA Process Wt.
Small
Large
-
1,000
-
-
1,000
69,340
70,340
High Efficiency
Small
-
1,000
-
-
1,000
12,230
13,230
Large
-
1,000
-
-
1,000
69,340
70,340
-------
1000
800
600
CO
cc
o
Q
I
I
o
I
8
o
400
300
200
100
FIGURE 26
CAPITAL COSTS FOR TERTIARY CYCLONES
FOR FCC UNITS
10
20
30
40
50 60
COMBINED FEED RATE, THOUSANDS
OF BARRELS PER STREAM DAY
112
-------
CO
cc.
LL
O
8
O
X
I-
8"
O
100
80
60
50
40
30
20
10
FIGURE 27
ANNUAL COSTS FOR TERTIARY CYCLONES
FOR FCC UN ITS
TOTAL ANNUAL
:OST
(includes 1000/yr
operating cost)
10
20
30
40
50 60
80 100
COMBINED FEED RATE, THOUSANDS
OF BARRELS PER STREAM DAY
113
-------
REFERENCES
(1) Cantrell, Ailleen, Annual Refining Survey, Oil and Gas Journal, March 2,
1971, P. 94.
(2) "Worldwide Directory - Refining and Gas Processing 1970/71",
Petroleum Publishing Company, (Tulsa, Oklahoma), May, 1970.
(3) Nelson, W. L, Petroleum Refinery Engineering, Second Edition, McGraw
Hill (New York) 1941.
(4) Danielson, J. A., Air Pollution Engineering Manual, U.S. Dept. of HEW,
(Cincinnati) 1967.
(5) Braca, R. M. and A. A. Fried, "Operation of Fluidization Processes",
Fluidization in Practice Symposium, February 25, 1955, Polytechnic
Institute of Brooklyn (in cooperation with the AICHE).
(6) Bell, H. S., American Petroleum Refining, fourth ed., D. Van Nostrand,
Princeton, N.J., 1959, P. 262.
(7) Sussman, W. H., "Atmospheric Emissions from Catalytic Unit Regenerator
Stacks", Report No. 4. Joint Project for Evaluation of Refinery
Emissions. Los Angeles Air Pollution Control District, (Los Angeles),
1957.
(8) Wilson, J. G., and D. W. Miller, "The Removal of Particulate Matter from
Fluid Bed Catalytic Cracking Unit Stack Gases", Journal of the Air
Pollution Control Association, V. 17, N. 10, October 1967, pp. 682-685.
(9) White, Harry J., Industrial Electrostatic Precipitation, Ann Arbor Press,
Ann Arbor, Michigan, 1963.
114
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CO
TJ
X
CO
n
z
o
-------
3. ASPHALT BATCHING INDUSTRY
Hot-mix asphalt plants produce the familiar asphalt paving material which
consists of an aggregate of mineral load-bearing material that has been
uniformly mixed with hot asphalt cement in a batch production process. As
each batch is completely mixed, it is loaded into waiting trucks for immediate
transportation to the paving site, where it is deposited and then compacted by
heavy rolling equipment. There is an emerging technology known as "Hot
Storage" used by a few asphalt plants. In this technique a smaller dryer and a
smaller mixer can be used to make paving material on a 24 hour a day basis and
store it in the finished form. Delivery to the contractors doing the paving
usually takes place only during a 6 to 8 hour day. The hot-mix asphalt industry
in the United States produces about 251 million tons of paving material a
year'71, but production is scattered among a number of small plants, producing
about 100 to 200 ton/hr during the working hours of the local paving season.
These plants are located near the sites of potential use, due to the great
importance of transportation costs in overall profitability.
PROCESS DESCRIPTION
A typical configuration for such a hot-mix asphalt batch plant is given in
Figure 28. The production flow in the plant starts with the cold aggregate
which is stored in bins until required. At that time it is transported by elevator
to a rotary drier which heats the aggregate and drives off surface moisture. In
place of bins, many plants use open pile storage with front end loader retrieval
and feed to the drier. The hot aggregate, as it leaves the drier, is conveyed by
elevator to a size classifier that commonly takes the form of a series of
vibrating screens. Here, the hot aggregate is sorted into various size categories
and is stored separately, by category, in bins just above the mixer. When a
batch is to be mixed, proper portions of each size of aggregate are loaded into
the mixer by means of a weigh hopper. In the mixer, the hot asphalt cement, as
drawn from a heated tank, and possibly a very fine mineral filler, are added to
the hot aggregate, and the batch is agitated until it is mixed thoroughly. When
mixing is complete, the batch is loaded into trucks and transported to the
paving site.
The equipment in a hot-mix asphalt batch plant varies from design to
design; for example, conveyors may replace or supplement the aggregate
elevators, or storage bins may be arranged differently. However, the most
critical piece of equipment from the standpoint of emission abatement, the
rotary drier, is usually of a fairly standard direct, countercurrent design,
although other designs exist. Such a drier is basically a rotating cylinder which
115
-------
is inclined to the horizontal with a stationary oil or gas-fired burner on or near
the axis at the depressed end, and the aggregate entrance at the elevated end.
The aggregate is directly exposed to the burner flame, and the direction of the
aggregate flow is opposed to that of the burner combustion gases (see Figure
29). Often the drier will contain internal flights to agitate the aggregate and
further expose it to the heating and drying action of the combustion gas
stream. In typical operations, the burner heats the aggregate to 250 to 450° F,
and the gas stream has a velocity of 450 to 800 ft/min with a volume rate of
20,000 to 70,000 ACFM. The air flow through the drier is usually maintained
by an exhaust fan and stack system, and the temperature and air flow are
regulated as necessary to remove the maximum amount of aggregate surface
moisture and heat the material.
Thus, the exact operating parameters of the rotary drier depend upon the
desired production rate and the surface moisture of the aggregate. It has been
determined, in general, that an increase in drier gas velocity permits an almost
directly proportional increase in maximum production (see Figure 30*).
However, the dust carryout increases in proportion to the square of the
velocity (see Figure 31*). Thus, production and air flow levels must be
balanced against increased dust loss in drier operation11'.
The other equipment in a hot-mix plant is fairly conventional in design
and operation, and is, in any event, usually non-critical. However, such factors
as the amount of aggregate transportation system enclosure and the quality of
ventilation and burning in the asphalt and fuel oil heater burners should be
examined in any analysis of emission potential.
FEED MATERIALS AND PRODUCTS
The raw materials for a hot-mix asphalt batch plant are essentially the
aggregate, the asphalt cement, and the fuel, either oil or gas. Fuel oil or gas are,
of course, excluded in any process weight consideration. Paving mixes are
produced for different uses with correspondingly different characteristics, as
determined primarily by the size distribution of the aggregate used. Although
there are detailed mix classifications used within the industry which are based
on more elaborate distribution specifications, the primary mix characteristics
are determined by the fraction of the total aggregate in each of the following
three categories:
Coarse aggregate (retained on No. 8 mesh sieve)
Fine aggregate (passing No. 8 mesh sieve)
Mineral dust (passing No. 200 mesh sieve)
'Courtesy of Barber—Greene
116
-------
COLD
AGGREGATE
ELEVATOR
HOT
AGGREGATE
ELEVATOR
COLD .
AGGREGATE
STORAGE
\
ROTARY
DRYER
^
n
i
VIBRATING
SCREENS
SORTED HOT
AGGREGATE
STORAGE
BINS
WEIGH
HOPPER
MIXER
HOT MIX
TRUCK
i i
'
1
^» x^
/ASPHALT
[ CEMENT
VSTORAGE
FIGURE 28
FLOW DIAGRAM FOR HOT-MIX ASPHALT
BATCH PLANT
-------
00
EXHAUST
AGGREGATE
FEED
BURNER
PRODUCT
EXIT
FIGURE 29
ROTARY DRIER CONFIGURATION
-------
100
>- 90
£-
^ 80
UJJj 70
Z<
Oo: 60
g? 50
25 40
£*£ 30
n i Q-
0 20
10
FIGURE 30
DRYER PRODUCTION CAPACITY
VS
DRUM GAS VELOCITY
10 20 30 40 50 60 70 80 90 100
DRUM GAS VELOCITY (PERCENT INCREASE)
600 700 800 900 1,000 1,100 1,200
DRUM GAS VELOCITY ( Fpm )
CO
-------
FIGURE 31
275
j}J 250
LLJ
ot 225
U
- 200
i—
m 175
U
? 150
O
125
100
U 75
§ 50
Q
25
0
DUST CARRYOUT
VS
DRUM GAS VELOCITY
10 20 30 40 50 60 70 80 90 100
DRUM GAS VELOCITY (PERCENT INCREASE)
600 700 800 900 1,000 1,100 1,200
DRUM GAS VELOCITY ( Fpm )
-------
Coarse aggregate is used in all diameters up to 2-1/2 inches. This usually
consists of crushed stone, slag, or gravel, or naturally fractured aggregate, or
combinations thereof. Fine aggregate is usually natural sand with such added
materials as crushed stone, slag, or gravel. Mineral dust is a special filler that is
used in certain applications. It is usually finely ground particles of crushed
rock, limestone, hydrated lime, Portland cement or other similar mineral
matter.11'
The asphalt cement is mixed at about 3 to 12% by weight with the
aggregate in the final paving mix, depending upon the specific mix design and
the end use. The asphalt is manufactured from crude petroleum, and is
semi-solid at ambient temperature. On heating it becomes liquid in the range
275 to 375° F, at which it is stored and mixed. Thus, each batch plant must
provide heat sources for the asphalt storage facilities. The asphalt cement is
graded by an industrial classification or penetration. The proper penetration for
a particular use is usually specified under local or state highway specifications.
The fuel used in the rotary drier and in the asphalt heaters is fuel oil or
natural gas. Natural gas is a required fuel in some locations, but fuel oil is often
used because of the lower cost. The grade of fuel oil is usually No. 6, and
provisions for heating the oil to provide for efficient burning may be necessary
if ambient temperatures are low.
NATURE OF THE A(R CONTAMINANTS
The air pollutant emissions from a hot-mix asphalt plant are both gaseous
and particulate. Of these, the gaseous pollutants are the least troublesome and
can occur in the following ways:
1. Combustion gases
a. Combustion of high sulfur fuel oil in the drier and heater will
produce S02 emissions.
b. Poor combustion maintenance in the drier or heaters will lead
to CO emissions.
2. Mixer — the entrance and mixing of the asphalt cement in the mixer
will cause hydrocarbon emission.
3. Hot-mix trucks — significant odor primarily attributed to some
oxidation of the liquid asphalt after encountering the hot aggregate.
121
-------
The particulate pollution consists of:
1. Unburned fuel oil droplets — these result from poor combustion
maintenance in the drier or heaters.
2. Soot — particles of unburned carbon that are emitted due to
insufficient oxygen at the drier or heater burners.
3. Fly ash — noncombustible impurities which are emitted from the
combustion of fuel oil.
4. Stone dust — this is the primary air pollutant from hot-mix asphalt
manufacture. It results from the air flow in the drier carrying off fine
particles of aggregate and from fine aggregate being thrown off
during the transportation, screening and mixing processes.
A number of these emissions are not amenable to abatement through gas
cleaning equipment or may more easily be corrected through a proper choice of
fuels and proper combustion management. The odor problem from the loading
of hot-mix trucks is an example of such a problem. Gas cleaning equipment is
clearly.not applicable here, but some success has been reported in curtailing the
odor emissions through the coating of truck bodies with lime-water slurries
instead of fuel oil or kerosene13'. In the latter category, SC>2 and fly ash
emissions may be controlled by using fuel oil that has a lower sulfur and ash
content, or switching to natural gas; while soot, unburned fuel oil droplets, and
CO emissions may be reduced by the practice of good combustion management
at all burners, which is desirable anyway.
If the above elementary emission abatement procedures are followed, the
only emissions that will warrant consideration are the hydrocarbons released in
the mixer and the production of stone dust in the aggregate handling. The
hydrocarbon emission problem is a difficult one that can really only be handled
by thermal incineration. However, this technique is not frequently used; the
primary method of control is to maintain a tight enclosure of the mixer. This
will certainly eliminate some problems, but, unless this enclosure is ventilated,
it is quite likely that ground level leakage will occur. If the mixer enclosure is
ventilated, the advisability of coupling -this with the stone dust ventilating
system will depend upon the ultimate design of the stone dust control system,
as is discussed with the consideration of types of pollution control equipment.
If separate ventilation of the mixer is attempted, minor amounts of stone dust
should be anticipated in the exhaust. At the present time, such separate
ventilation is uncommon and in most plants the mixer is merely closed and
vented to the stone dust system.
122
-------
The emission of stone dust from hot-mix plants is their primary air
pollution problem. Dust is produced in the plant in two major areas; the first
and most important is the rotary drier. In the drier, dust is produced by the gas
flow picking up fine particles of aggregate and fracture dust from the aggregate
and carrying it out in the exhaust gases. The second area of dust emission
includes a variety of sources at which aggregate is handled; these may be
termed collectively the "secondary sources", and the dust emitted from them
"fugitive dust". These include the aggregate elevators, storage bins, screen
classifier, and mixer. In a typical plant, the hourly weight production of stone
dust from the drier is about 3 to 5 times that of the secondary sources and the
total dust loss from the plant is about 40 pounds per ton of paving mix
produced'1 • 7 . For a reasonably sized plant producing 150 tons of paving mix
an hour, the dust emission is on the order of 6000 Ib/hr. Therefore, the design
of air pollution control equipment for the hot-mix asphalt batch plant is
essentially for the regulation of these significant amounts of dust emission.
AIR POLLUTION CONTROL CONSIDERATIONS
The first step in controlling dust emission at any hot-mix plant is to
completely enclose and ventilate all areas where dust is produced. At the drier,
suitable equipment consists, at the exhaust end, of complete hooding to carry
off the exhaust gases and entrained dust. At the burner end, the ventilation
requirements are less critical. In most cases, a hood will not be required due to
the large inflow of secondary combustion air. Where a hood is required, a
suitable arrangement is a ring type hood between the stationary and rotating
portion of the drier with a spacing that produces at least the standard 200 feet
per minute in the opening between the drier and the hood (see Figure 32).
The sources of fugitive dust emission, including the storage bins, elevators,
vibrating screens, and mixer, should be completely enclosed, and these
enclosures should be ventilated as well. The volume rate sufficient for
ventilation of these secondary sources is typically 3000 to 4000 ACFM.
Primary Collector
The air used for ventilation of the sources of dust emission must be
treated to remove the entrained dust in order to avoid serious air pollution
problems. However, these systems should be designed with the consideration
that much of the entrained dust is valuable as a mineral dust filler in the mix
and should be recovered if possible.
Therefore, it is usual for all dust sources to be ventilated in the same
123
-------
system and the air carried to a primary collector such as a cyclone or knockout
chamber which will remove a sizable percentage (usually 50 to 90% by weight)
of the entrained dust, mostly of the larger sizes'81 (see Table 53), and return it
to the system at the hot aggregate storage bins or some other point, in the form
of mineral dust. This primary mechanical collector can be considered as a part
of the process, since it is merely a device for returning escaped materials to the
system, and since its use is usually advantageous for economic reasons alone.
(See Figure 33 for augmented plant design.)
The dust which is not retrieved by the primary collector is predominantly
of small diameter and has a large percentage of clay and organic particles that
were brought in originally with the aggregate. This dust may or may not be
usable as a mineral filler depending upon the nature of the aggregate used, the
specification of the product being produced, and the method of dust collection
employed. The device used to capture this dust is termed the secondary
collector.
The types of gas cleaning equipment suitable for application as the
secondary collector in an asphalt batch plant are the wet scrubber, fabric filter,
and electrostatic precipitator. Historically, the wet scrubber has been used most
frequently, but in recent years the fabric filter has seen increasing use. Each
type can, within its own technical limits, handle the dust and gas stream
emitted from the primary, and the final choice between the three types will
hinge on relative costs, plant room for ancillary equipment, plant room for
collection equipment, the exact nature of local regulations, and the need for
maximizing the retention of <200 mesh material for filler.
Wet Scrubbers
The types of wet scrubbers first applied to batch plant service were
primarily low energy centrifugal or baffled spray chamber types. These,
especially the latter, do not provide the desired collection efficiencies and,
recourse has been made to moderate to high energy configurations, such as the
dynamic, Venturi, or orifice types. The technical advantages of a wet scrubber
include the lack of any need for exhaust precooling and the capability of
ventilating the mixer into the fugitive dust system and thus allowing dispersion
of the hydrocarbon emissions from the exhaust stack. Moreover, the amount of
space required by the scrubber proper within the working area of the plant is
small.
The disadvantages of the wet scrubber lie primarily in its need for large
quantities of recycle water. This requires a pumping and piping system designed
to prevent the dust-slurry from settling until it reaches a settling pond or tank
124
-------
t
AGGREGATE
FEED
171
EXHAUST
DUCT
f
HOOD
(CLOSE HOODING
t
EXHAUST
DUCT
RING HOOD
AGGREGATE
^~ EXIT
FIGURE 32
RING TYPE HOOD ON A DRIER
-------
PRIMARY
COLLECTOR
EXHAUST
FAN
COLD
AGGREGATE
STORAGE
COLD
5ATE
FOR )
HOT
AGGREGATE
ELEVATOR
1
VIBRATING
SCREENS
SORTED HOT
AGGREGATE
STORAGE
BINS
WEIGH
HOPPER
MIXER
HOT MIX
TRUCK
FIGURE 33
FLOW DIAGRAM SHOWING PRIMARY COLLECTION
ASPHALT
CEMENT
STORAGE
-------
TABLE 53
PARTICLE SIZE DISTRIBUTION
BEFORE AND AFTER PRIMARY COLLECTION
FROM DRYER AND VENT
FROM PRIMARY COLLECTOR
Size
5
10
15
20
25
30
35
40
45
i Less Than
19.5
30.5
38.2
45.1
50.1
55.5
60.0
64.0
67.5
5
10
15
20
25
30
35
40
45
i Less Than
78.00
96.40
97.50
97.80
97.90
98.03
98.20
98.28
98.40
127
-------
12.8
-------
located near the plant. The recycle water generally becomes alkaline or acidic
and odoriferous, and may be corrosive if high sulfur fuel oil is burned. This
requires added protection through construction or chemical additives in the
piping system and care in disposal of the sludge so as not to cause water
pollution.
Fabric Collectors
The alternative to the wet scrubber is the fabric filter. In a hot-mix plant,
the fabric filter configuration is frequently that of a pulse jet automatic
baghouse without compartments, although conventional shaker-type bag
houses may also be used. The advantages of a baghouse are that it is a small
compact installation (although it may require more of the working area
immediately within the plant than a wet scrubber) and that the only water in
the baghouse exhaust comes from the aggregate, and does not produce a steam
plume except at low ambient temperature. Moreover, the material recovered
from a baghouse is dry and may be disposed of by land fill methods or
used as < 200 mesh mineral filler.
The disadvantages of a baghouse, however, are certainly worth noting. The
inlet temperature of a baghouse must be high enough to prevent condensation
anywhere in the gas stream and low enough to meet the temperature limits of
the filtering medium. Some batching plants operate at a very steady
temperature condition with relatively dry aggregate so that temperatures in the
250° F range can be maintained on a steady basis and insulation is not required.
Other plants operate at temperatures down to 150°F in the dust collector
because they are making a product known as "Cold Mix." In these cases, very
often not only insulation but secondary heat is required to keep the bags above
the dew point at all times. At the other end of the scale, there are many plants
that operate either steadily or occasionally up to temperatures in the 350 to
400° F range. These plants may require special bleed-in air systems to prevent
over temperature in the bag collectors. Many of the baghouses currently in
operation use media with a temperature limitation of 425° F. A smaller number
use a lower temperature media with a limitation of 275° F. Finally, when a
baghouse is used, the mixer may not be ventilated through the fugitive dust
system, as the hydrocarbon emissions may blind the fabric filter.
129
-------
SPECIFICATIONS AND COSTS
With this consideration of the job to be performed and the applicable type
of equipment, suitable specifications may be written for pollution abatement
measures at hot-mix asphalt batch plants. Two such specifications are given in
Tables 54, 55, 58 and 59; one set for a wet scrubber system and one set for a
fabric collector. In the case of the scrubber, specifications are given for two
levels of efficiency. The fabric collector, however, is written so as to solicit a
single quotation for the high efficiency level. Cost data generated from the
filter specification are presented in Tables 56 and 57 while data from the
scrubber specification are presented in Tables 60 and 61.
During the course of this study, it was found that one IGCI member
company had supplied a number of electrostatic precipitators for asphalt batch
plants. As a result, a specification was written for this application, and is
presented as Tables 62 and 63. However, no precipitators were quoted by
member companies, and they are not presumed to be available.
Although specifications were written for a precipitator and one manu-
facturer was asked to supply cost data, none was available at the time this
report was prepared. Apparently current applications of precipitators are quite
rare as compared with many scrubber and filter installations.
Fabric Collector capital costs are presented in Figure 34. The primary
mechanical collector cost is included with the fabric collector in the "collector
only" cost. This combined cost is over half the total system cost. Turnkey
prices are shown in Figure 36, along with the 75% and 95% confidence limits.
The fabric collector installed costs present a reasonably consistent pattern. The
"collector plus auxiliaries" figures (present in Figure 37) are not so consistent,
which probably indicates varying levels of pre-assembly of the collectors
supplied by the manufacturers.*
The wet scrubber pattern is considerably less consistent. The averages
shown in Figure 38 are for only two.of the three potential bidders, and are
based on quotations quite inconsistent with one another. Significant
differences in scrubbers and system design probably accounts for this variation.
*The specifications written for fabric collectors indicated that the equipment
should be portable. This requirement added about 10% to the cost of the
system.
130
-------
As expected, fabric collector operating costs (Table 57 and Figure 35) are
lower than those for scrubbers (Table 61 and Figure 40). but on a total annual
cost basis they present a competitive picture.
131
-------
Table 54
FABRIC FILTER PROCESS DESCRIPTION FOR
ASPHALT BATCHING PLANT SPECIFICATION
A fabric filter is to treat the effluent from a typical asphalt batching plant operation.
All of the air required to ventilate the following items of equipment must be treated so as to
conform to the specified paniculate emission limits.
1. Cold aggregate elevator
2. Rock dryer
3. Ho t aggregate elevator
4. Vibrating screens
5. Sorted hot aggregate storage bins
6. Weigh hopper
The necessary enclosures to minimize escapement of dust from conveyors, elevators,
etc., will be provided by others. The vendor is to furnish all interconnecting ductwork,
primary collector, baghouse proper, fans, solids collection bin, and solids conveying system.
A booster fan supplying 3" w.c. will be required for the fugitive dust sources. The air rate
through this fan will be 10% of the total flow to the collector. Dust from the primary
cyclone is to be returned to the bottom of the hot elevator, whereas dust collected in the
filter will be used for landfill.
The plant is located outside, adjacent to a public highway, and with little likelihood of
interferences of roadways, buildings, etc. with the location of pollution control equipment.
The plant is considered temporary (2 to 4 years expected life in this location) and may be
moved. Ability of the pollution abatement equipment to be dismantled and relocated is of
prime importance.
132
-------
Table 55
FABRIC COLLECTOR OPERATING CONDITIONS FOR
ASPHALT BATCHING PLANT SPECIFICATIONS
Two sizes of fabric collectors are specified for each of two efficiency levels. Vendors
quotations should, however, consist of one quotation for each of the two sizes, with a
representation of the efficiency expected for the unit quoted. The efficiency quoted may be
better than the "high efficiency" case.
Small
Large
Plant Capacity, ton/hr
Process Weight, Ib/hr
Gas Flow to Primary Collector
Flow, ACFM
Temp., °F
% Moisture
Primary Collector Inlet
Loading, Ibs/hr
Primary Collector Outlet
Loading, Ibs/hr
Primary Collector Efficiency, %
Temperature Drop Primary Collector
Inlet, °F
Outlet, °F
Gas to Fabric Collector
Flow, ACFM
Temp., °F
% Moisture
Dew Point, °F
Outlet from Secondary Collector
Flow, ACFM
Temp., °F
WO
204,000
31,400
370
17
4,000
1,000
75
370
350
30,600
350
17
173
30200
340
200
408,000
44,000
370
21
8,000
2,000
75
370
350
42,900
350
21
176
42,400
340
Case 1 — Medium Efficiency
Outlet Loading, Ib /hr
Outlet Loading, gr/ACF
Efficiency, Wt. %
40
0.154
96
40
0.110
98
Case 2 - High Efficiency
Outlet Loading Ib /hrs
Outlet Loading, gr/ACF
Efficiency, Wt. %
7.8
0.03
99.28
10.9
0.03
99.46
133
-------
TABLE 56
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR FABRIC COLLECTORS FOR ASPHALT BATCHING PLANTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
*>-
Equipment [
(e) Dust Disposal
Equipment '
(3) Installation Cost — N
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other J
>•
(4) Total Cost
LA Process Wt.
Small
.
Large
High Efficiency
Small
31,400
370
17
1,000
30,600
350
17
0.03
7.8
99.28
49,901
10,046
23,687
83,634
Large
44,000
370
21
2,000
42,900
350
21
0.03
10.9
99.46
61,160
11,544
28,485
101,189
134
-------
TABLE 57
ANNUAL OPERATING COST DATA .
(COSTS IN $/YEAR)
FOR FABRIC COLLECTORS FOR ASPHALT BATCHING PLANTS*
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Bag Replacement per yr
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
^i3Q
$5/hr
$6/hr
$8/hr
$6/hr
$0.011/kw-h:
LA Process Wt.
Small
-
-
-
-
-
Large
-
-
-
-
-
High Efficiency
Small
180
180
200
~200
2,250
2,250
792
792
3,422
8,363
11,785
Large
180
180
288
'"288
3,075
3,075
792
792
4,335
10,119
14,454
CO
01
-------
FIGURE 34
CAPITAL COSTS FOR FABRIC COLLECTORS
FOR ASPHALT BATCHING PLANTS
300
200
C/3
oc
o
Q
u_
O
CO
Q
I
O
I
I-
O
o
100
50
30
TURNKEY SYSTEM
COLLECTOR PLUS
AUXILIARIES
I I _
COLLECTOR
ONLY _
100
200
300
400 500 600
PLANT CAPACITY, TON/HR
136
-------
FIGURE 35
ANNUAL COSTS FOR FABRIC COLLECTORS
FOR ASPHALT BATCHING PLANTS
50
40
30
20
CO
cc
o
Q
CO
o
\
O
I
CO
O
O
D
Z
Z
<
TOTAL COST*
(OPERATING COST PLUS
CAPITAL CHARGE)
10
'BASED ON 960 HR/YEAR
60
100
200 300
PLANT CAPACITY
TON/HR
400 500 600
137
-------
FIGURE 36
CONFIDENCE LIMITS FOR CAPITAL COST OF
INSTALLED FABRIC COLLECTORS
FOR ASPHALT BATCHING PLANTS
300
200
C/3
DC
O
Q
LL.
O
C/}
O
I
O
I
O
o
100
100 200 300
PLANT CAPACITY, TON/HR
400 500 600
138
-------
FIGURE 37
CONFIDENCE LIMITS FOR CAPITAL COST OF
FABRIC COLLECTORS PLUS AUXILIARIES
FOR ASPHALT BATCHING PLANTS
300
30
100 200 300
PLANT CAPACITY, TON/HR
400 500 600
139
-------
Table 58
WET SCRUBBER PROCESS DESCRIPTION FOR
ASLPHALT BATCHING PLANT SPECIFICATION
A single wet scrubber is to treat the effluent from a typical asphalt batching plant
operation. All of the air required to ventilate the following items of equipment must be
treated so as to conform to the specified paniculate emission limits.
1. Cold aggregate elevator
2. Rock dryer
3. Hot aggregate elevator
4. Vibrating screens
5. Sorted hot aggregate storage bins
6. Weigh hopper
7. Mixer
The necessary enclosures to minimize escapement of dust from conveyors, elevators,
etc. will be provided by others. The vendor is to furnish all interconnecting ductwork,
primary collector, wet scrubber, fan, slurry pumps, settler and clarified water return pumps.
Dust from the primary cyclone is to be returned to the bottom of the hot elevator, whereas
dust collected in the scrubber is to be settled to approximately 60% solids content by weight
and removed by truck.
The plant is located outside, adjacent to a public highway, and with little likelihood of
interferences of roadways, buildings, etc. with the location of pollution control equipment.
The plant is considered temporary (2-4 years expected life in this location) and may be
moved. Ability of the pollution abatement equipment to be dismantled and relocated is of
prime importance.
140
-------
Table 59
WET SCRUBBER OPERATING CONDITIONS FOR
ASPHALT BATCHING PLANT SPECIFICATION
Two sizes of wet scrubbers are to be quoted for each of two efficiency levels. Vendors
quotation should consist of four separate and independent quotations.
Small
Large
Plant Capacity, ton/hr
Process Weight, Ib/hr
Gas to Primary Collector
Flow, ACFM
Temp., °F
% Moisture
Primary Collector Inlet
Loading, Ib/hr
Primary Collector Outlet
Loading, Ib/hr
Primary Collector efficiency, %
Gas to Secondary Collector
(Scrubber)
Flow, ACFM
Temp., °F
% Moisture
Outlet from Secondary Co/lector
Flow, ACFM
Temp., °F
Moisture Content, Vol. %
100
204,000
31,400
370
17
4,000
1,000
75
30,600
350
17
25,000
147
23
200
408,000
44,000
370
21
8,000
2,000
75
42,900
350
21
35,200
152
26.2
Case 1 — Medium Efficiency
Outlet Loading, Ib/hr
Outlet Loading, gr/ACF
Efficiency, Wt. %
40
0.187
96
40
0.133
98
Case 2 — High Efficiency
Outlet Loading, Ib/hr
Outlet Loading, gr/ACF
Efficiency
6.43
0.03
99.68
9.06
0.03
99.77
141
-------
TABLE 60
ESTIMATED CAPITAL COST DATA^
(COSTS IN DOLLARS)
FOR SCRUBBERS FOR ASPHALT BATCHING PLANTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) GasCleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other J
(4) Total Cost
LA Process Wt.
Small
30,600
350
17
1,000
25,000
147
23
0.187
40
96
9,975
11,013
26,157
47,145
Large
42,900
350
21
2,000
35,200
152
26.2
0.133
40
98
12,229
14,539
31,934
58,702
High Efficiency
Small
30,600
350
17
1,000
25,000
147
23
0.03
6.43
99.68
12,181
13,062
27,360
52,603
Large
42,900
350
21
2,000
35,200
152
26.2
0.03
9.06
99.77
15,930
18,210
33,571
67,711
142
-------
TABLE 61
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR ASPHALT BATCHING PLANTS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
960
$6/hr
$0.01/KW-I
$0.25/M gal
LA Process Wt.
Small
-
291
50
341
185
185
r 590
464
1,054
1,580
4,714
6,294
Large
-
283
75
358
226
226
885
610
1,495
2,079
5,870
7,949
High Efficiency
Small
-
291
50
341
194
194
1,162
547
1,709
2,244
5,260
7,504
Large
-
283
75
358
244
244
1,730
731
2,461
3,063
6,771
9,834
CO
-------
C/5
cc
o
o
CO
Q
CO
O
I
80
70
60
50
40
30
20
10
60
FIGURE 38
CAPITAL COSTS FOR WET SCRUBBERS
FOR ASPHALT BATCHING PLANTS
(LA-PROCESS WEIGHT)
TURNKEY
SYSTEM
COLLECTOR
PLUS
AUXILIARIES
COLLECTOR
ONLY
100 200 300
PLANT CAPACITY, TON/HR
400 500 600
144
-------
80
70
60
50
40
30
§
LL
O
V)
Q
I
O
8
CJ
20
10
FIGURE 39
CAPITAL COSTS FOR WET SCRUBBERS
FOR ASPHALT BATCHING PLANTS
(HIGH EFFICIENCY CASE)
TURNKEY
SYSTEM
COLLECTOR PLUS
AUXILIARIES
COLLECTOR ONLY
60
100 200 300 400 500 600
PLANT CAPACITY, TON/HR
145
-------
146
-------
I
I
o
z
<
20
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
10
5
4
60
I
OPERATING COST*
'BASED ON 960 HR/YEAR
100 200 300 400 500 600
PLANT CAPACITY TON/HR
FIGURE 40
ANNUAL COSTS OF WET SCRUBBERS
FOR ASPHALT BATCHING PLANTS
(HIGH EFFICIENCY CASE ONLY)
147
-------
Table 62
ELECTROSTATIC PRECIPITATOR PROCESS DESCRIPTION FOR
ASPHALT BATCHING PLANT SPECIFICATION
An electrostatic precipitator is to treat the effluent from a typical asphalt batching
plant operation. All of the air required to ventilate the following items of equipment must
be treated so as to conform to the specified paniculate emission limits.
1. Cold aggregate storage hopper
2. Cold aggregate elevator
3. Rock dryer
4. Hot aggregate elevator
5. Vibrating Screens
6. Sorted hot aggregate storage bins
7. Weigh hopper
A booster fan supplying 3" w.c. will be required for the fugitive dust sources. The air
rate through this fan will be 10% of the total flow to the collector. Dust from the primary
cyclone is to be returned to the bottom of the hot elevator, whereas dust collected in the
filter will be used for landfill.
Automatic voltage control shall be provided to maximize operating efficiency. Rappers shall
be adjustable both as to intensity and rapping period. The precipitator shall be equipped
with a safety interlock system which prevents access to the precipitator internals unless the
electrical circuitry is disconnected and grounded.
The plant is located outside, adjacent to a public highway, and with little likelihood of
interferences of roadways, buildings, etc. with the location of pollution control equipment.
The plant is considered temporary (2 to 4 years expected life in this location) and may be
moved. Ability of the pollution abatement equipment to be dismantled and relocated is of
prime importance.
148
-------
Table 63
ELECTROSTATIC PRECIPITATOR OPERATING CONDITIONS FOR
ASPHALT BATCHING PLANT SPECIFICATION
Two sizes of electrostatic precipitators are specified for each of two efficiency levels.
Vendors quotations should consist of four separate and independent quotations.
Plant Capacity, ton/hr
Process Weight, Ib /hr
Gas Flow to Primary Collector
Flow, ACFM
Temp., °F
% Moisture
Primary Collector Inlet
Loading, Ib /hr
Primary Collector Outlet
Loading, Ib /hr
Primary Collector Efficiency
Gas to Precipitator
Flow, ACFM
Temp., °F
% Moisture
Dew Point, °F
Small
100
204,000
31,400
370
17
4,000
1,000
75
31,400
370
17
173
Large
200
408,000
44,000
370
21
8,000
2,000
75
44,000
370
21
176
Case 1 — Medium Efficiency
Outlet Loading, Ib /hr
Outlet Loading, gr/ACF
40
0.148
40
0.106
Case 2 - High Efficiency
Outlet Loading, Ib /hr
Outlet Loading, gr/ACF
Efficiency, Wt. %
8.1
0.03
99.29
11.3
0.03
99.44
149
-------
REFERENCES
1. Danielson, J. A., ed. Air Pollution Engineering Manual. U.S. Department
of Health, Education, and Welfare, publication No. 999-AP-40,
(Cincinnati, 1967), pp. 325-334, 367-371.
2. Friedrich, H. E., "Air Pollution Control Practices: Hot-mix Asphalt Paving
Batch Plants." Journal of the Air Pollution Control Association, Vol. 19,
(December 1969), pp. 974-978.
3. National Asphalt Pavement Association, Environmental Pollution Control
of Hot Mix Asphalt Plants, Information series 27, (Riverdale, Maryland).
4. Roads and Streets, "Bag Collectors Meet Chicago Pollution Code", (July
1969), pp. 97-98.
5. Schell, T. W., "Cyclone/Scrubber System Quickly Eliminate Dust
Problems." Rock Products, (July 1968), pp. 66-68.
6. Skinner, C. F., "New Use for Baghouse Filter: Handling Hot Effluent."
Plant Engineering, (June 26, 1969), pp. 57-59.
7. Vandeguft, A.E.; Shannen, L. J.; Sallee, E. E.; Gorman, P.G.; Park, W. R.,
"Paniculate Air Pollution in the United States." Journal of the Air
Pollution Control Association, Vol. 21, (June 1971), pp. 321-327.
8. Rock Products, July 1969, p. 67.
150
-------
00
o
•n
m
m
r
z
o
-------
4. IRON AND STEEL INDUSTRY
BASIC OXYGEN FURNACES
This section deals with one of the processes used in integrated
steelmaking. The overall steelmaking process involves a number of basic steps,
most of which are carried out in a single plant. These include11 • 8):
1. Raw material preparation (coke ovens, ore sintering, pelletizing,
limestone preparation).
2. Making iron (blast furnaces and direct reduction).
3. Making steel (removal of carbon and other impurities from iron).
4. Casting steel.
5. Rolling steel into semi-finished products such as plate and rod
(rolling mills, annealing, galvanizing, scarfing, vacuum degassing).
6. Manufacture of finished steel products.
These processes, taken together, constitute one of the major industries in
the U.S., with a production capacity of some 155 to 160 million tons of steel
per year11'.
Most important of the processes are blast furnace operation, which
produces iron by the reduction of iron ore to molten iron, and steelmaking, in
which the impurities in the blast furnace product (called pig iron when solid
and hot metal when molten) are removed to make steel.
There are three steel making processes in use:
1. Open hearth furnaces
2. Basic oxygen furnaces (BOF)
3. Electric furnaces
In prior years most steel was produced by the open hearth process, but
since the introduction of the basic oxygen furnace (BOF) process about 15
years ago, the BOF has gradually replaced the open hearth as the primary
method of steel making. The output of domestic steel in 1970 was distributed
asfollows:111
151
-------
Open hearths 36%
BOF 49%
Electric furnaces 15%
100%
The growth of BOF usage in the U.S.A. is illustrated in Figure 41(8).
The BOF steelmaking process was developed at a small steel plant in Linz,
Austria and at about the same time in nearby Donowitz. For a number of years
it was referred to as the Linz-Donowitz or L-D process. Other names for the
same process are the top-blown oxygen process and the basic oxygen process.
"Basic" here refers to the composition of the lining and results in a basic slag.
In order to maintain a basic slag, in which the ratio of CaO and MgO to Si02 is
greater than one, burned lime is added to the furnace either prior to or during
oxygen lancing.
The process is alternatively described as the basic oxygen process (BOP)
and as steelmaking in basic oxygen furnaces (BOF), or BOF steelmaking. In the
remainder of this section the latter terminology will be used.
PROCESS DESCRIPTION
The flow scheme for a BOF steelmaking operation is shown in Figure 42.
Figure 43 illustrates the flow schemes utilizing electrostatic precipitators or
high energy scrubber systems for gas cleaning.
The blast furnace operates continuously, but is tapped intermittently. The
BOF operates on a batch basis, and is charged more frequently than the blast
furnace is tapped. Therefore, there must be some provision for intermediate
storage of the hot metal.
Steelmaking processes vary with regard to the storage of hot metal. In
some plants, the hot metal retention is kept to a minimum. In others, hot metal
mixers are employed to provide storage capacity and improve uniformity of the
hot metal from one submarine car load to the next.
The sequence of steps in the transfer and charging operations is as follows:
1. Hot metal tapping at the blast furnace.
2. Transfer from submarine car to hot metal mixer.
152
-------
FIGURE 41
STEEL PRODUCTION - UNITED STATES (IN MILLION SHORT TONS OF INGOTS)
150
oo
O
H
LL.
O
oo
'.00
o
Q
O
DC
0.
50
153
-------
RELIEF
DAMPER
GAS
CLEANING
SYSTEM
'(SEE FIGURE 3)
FLUX HOPPERt 4
AND CHUTE \ /
SCRAP WEIGHING
SCALE
OXYGEN
LANCE
KISH COLLECTION
SYSTEM
CHARGING
FUME
HOOD
O,,FUEL
MIXING
PRE-HEAT
LANCE
SUBMARINE
CAR
WATER COOLED
HOOD
SCRAP
CHARGING
HOT METAL
LADLE
SLAG TRANSFER
CAR
HOT METAL MIXER
( OPTIONAL )
FIGURE 42
FLOW SCHEME BOF STEELMAKING
I
5 — C! 1
LT~C
U C
INGOT
MOLDS
-------
~ STEAM OR H2O
CONDITIONING
SPRAYS
1
FROM BOF
HOOD
r
FALL-OUT
HEADER
ELECTROSTATIC
PRECIHTATOR
\
r V
L/
FAN
TO WASTE
OR SINTER
STACK
ELECTROSTATIC PRECIPITATOR GAS CLEANING SYSTEM
GAS FROM
OTHER BOF'S
FROM
COOLING
TOWER I I
7C
STACK
TO
COOLING
TOWER
TO FINISHING
CLARlFlER
AND SEWER
| SOLIDS TO
FILTER /"*-+ WASTE/SINTER
VENTURI SCRUBBER GAS CLEANING SYSTEM
FIGURE 43
GAS CLEANING EQUIPMENT FOR BOF STEELMAKING
-------
3. Transfer from hot metal mixer to charging ladle.
4. Addition of scrap to BOF.
5. Addition of hot metal to BOF.
The trend is away from using hot metal mixers and many mills are taking hot
metal from the blast furnace directly to the BOF without intermediate
transferring.
The hot metal mixer (where it is used) serves as a reservoir from which the
charging ladles are filled periodically. The charging ladle sets in a pit below the
level of the mixer. To charge the ladle, the mixer is rotated slightly, and hot
metal pours from the discharge opening into the charging ladle.
The BOF process is sufficiently exothermic that scrap steel can be added
to the charge without preheating. Approximately 30% of the BOF furnace
capacity is made up of scrap steel from various sources. Higher fractions of
scrap steel can be included if the scrap is heated prior to charging. This is more
common in Europe than in the U.S. The usual practice in the U.S. is to preheat
the scrap in the vessel using a special ©2 fuel lance. This preheating is done
before hot metal addition.
The charging process is irregular, and may take as little as a few seconds if
the scrap slides in easily, or may take as much as five minutes to complete if
the operator has trouble dislodging the irregular pieces.
After the scrap steel is positioned or heated in the BOF, the furnace is
tilted to receive the hot metal charge. The crane operator lifts the ladle and
moves it gently to the mouth of the furnace. During the transport of the ladle,
little or no fuming takes place. The crane operator tips the ladle by means of a
small auxiliary hook. A large amount of fuming takes place during hot metal
charging. All fume control systems should provide for this but few do at this
time. Secondary hooding is frequently used to capture charging fumes.
BOF Operation
The basic oxygen furnace functions to convert hot metal into steel by
oxidation of carbon, phosphorus, silicon, sulfur, and other impurities in the
156
-------
iron. The pear-shaped vessel is lined with magnesia and has a charging opening
at the top, and a small nozzle on one side near the top for tapping of finished
steel.
The vessel is filled to about 1/3 of its depth with hot metal and scrap. As
soon as the metal charging is completed, the furnace is rotated into an upright
position and carefully measured amounts of slag-forming fluxes are added.
These consist principally of burned lime, dolomite or dolomitic lime, fluorspar,
and mill scale.141 The addition of these materials takes place with the furnace
vertical and positioned under the ventilating hood, so that there are no
uncontrolled emissions of particulate matter during this part of the cycle.
Frequently these fluxes are added after 02 ignition is started. The sequence
appears to be the operator's choice.
As soon as the furnace is in the vertical position, the oxygen lance is
lowered into position through the hood. This lance consists of a water-cooled
pipe through which pure oxygen gas is blown into the furnace and impinges on
the surface of the melt. Oxygen pressure is generally held between 140 and 180
pounds per square inch, and the extremely turbulent impingement of the jet on
the surface of the melt plays an important part in the refining process.12'
Oxygen reacts with the surface of the bath to form carbon monoxide and
also to produce substantial quantities of FeO which diffuse through the melt.
The increased FeO concentrations result in carbon monoxide formation and
vigorous boiling of the molten metal. Oxygen lancing continues for about 20
minutes, during which time the carbon content of the melt drops from above
3.5% to less than 0.5%. Similar reductions in the silicon and phosphorous
content take place during finishing of the steel.(2)
Prior to completion of the blow, the oxygen flow is stopped, the vessel
rotated, and a sample of the molten steel is taken for analysis. When the
analysis is returned, it is compared to the desired analysis. If within acceptable
limits the blow is finished. If the actual analysis is not as desired, a reblow is
required. The furnace is brought to the vertical position, the oxygen lance
relowered, and oxygen flow resumed for a very short period, usually 1 to 2
minutes. Dependent on the correction desired, measured amounts of additives,
such as carbons for re-carburizing, may be manually introduced into the bath
prior to oxygen or during the reblow. Metallic alloying additives, such as
ferrosilicon, are added to the ladle after tapping the BOF, if the analysis so
dictates. The furnace is then rotated into a near horizontal position with the
mouth of the teeming side of the building, and molten steel flows through the
discharge port into a teeming ladle.
157
-------
The steel poured into the ladle is modified or brought to specification by
the addition of other alloying agents such as ferromanganese, ferrochromium,
ferrosilicon, etc.111 These alloys are discharged into the ladle directly from
ladle additive hoppers through chutes. At times substantial emission of
particulate matter occurs in pouring the steel into the ladle, and creates a real
problem in the shop area. Adequate and economical means of controlling this
problem have yet to be developed.
As soon as the steel is poured from the BOF, the furnace is rotated
quickly toward the other side of the building and the slag is poured into slag
transfer cars. During rotation of the furnace and slag pouring, the furnace emits
white fumes. The emission appears to be caused by thermal convection carrying
air into the vessel and contacting it with the residual metal on the walls of the
furnace. The rotation of the furnace and slag pouring takes 1 to 3 minutes.
The teeming ladle differs from the submarine ladles and charging ladles in
that it is designed for withdrawal of the molten steel through the bottom rather
than by tipping the ladle and pouring the metal out. This is accomplished by
means of a nozzle at the bottom of the ladle which is equipped with a ceramic
plug. The plug is lifted vertically out of the opening by means of a ceramic
lined steel rod known as a stopper rod which extends through the molten
metal. A lever actuator at the top of the ladle permits the operator in the
teeming area to open the nozzle.
The teeming ladle is lifted by a crane and carried either to the teeming
area adjacent to the BOF, or to a continuous casting machine, or to vacuum
degassing to provide additional purification. The ladle shows no visible
emissions of particulate matter during this transport process. The teeming area
contains a number of railroad tracks on which ingot cars are lined up. The
teeming ladle is transported to the far end of the line of ingot molds resting on
individual ingot cars and fills each mold in turn by opening the nozzle at the
bottom of the ladle while it is directly above the vertical ingot mold. A fuming
problem develops in the teeming area when lead shot is added to the steel in
the ingot molds for producing leaded steels. This shop problem is frequently
controlled by venting to bag collectors having atmospheric exhausts.
EQUIPMENT DESCRIPTION
The BOF process is the simplest which has been devised for steel-
making.141 The BOF is a batch reactor, in which up to 350 ton charges of hot
metal and scrap steel are converted to steel by oxidation of impurities which
include carbon, phosphorus, silicon and magnesium. Figure 44 is a sketch of
158
-------
STEEL SHELL
TANK LINING
WORKING
LINING
LEVEL OF STEEL BATH
FIGURE 44
CONFIGURATION OF TYPICAL BOF VESSEL
159
-------
the simple, jug-shaped vessel which is filled to about 1/3 of its depth with hot
metal. This allows plenty of room for splashing of the molten metal and
slag.'21
The furnace is ordinarily a cylindrical, .refractory-lined vessel. Basic (high
magnesia) linings are used. A course of burned magnesite brick forms the outer
layer of the lining, next to the steel shell. A middle layer of basic ramming mix
supports the inner or working lining. The inner lining consists of a layer of
unfired bricks of dolomite (CaC03-MgC03). The furnace bottom is usually
built up of three courses of brick, with compositions similar to the side lining.
The linings deteriorate rapidly during operation of the furnace, and must be
replaced frequently. The middle and inner linings are ordinarily removed and
replaced on a routine basis.12' From 400 to 1000 heats can be obtained per
lining.
High purity oxygen is introduced into the furnace through a water-cooled
sparge-pipe, with a nozzle at the end, normally referred to as the oxygen lance.
Oxygen under a pressure of about 150 psig passes through the lance and
impinges on the molten metal surface at supersonic velocities. At the top of the
lance, armored rubber hoses are connected to a pressure-controlled oxygen
supply. Lance cooling water is also provided through flexible hose connections,
to protect the lance when it is retracted from the hot vessel to allow furnace
tipping for charging and pouring.121
The vessel is rotated about a horizontal axis by an electric motor and gear
train. The vessel is tipped at about 45° off vertical to receive charge materials
(hot metal and scrap steel). Charging of limestone and fluxes is done with the
furnace vertical under the ventilating hood.
The furnace is then tipped the opposite direction to pour steel through
the tap hole into the teeming ladle. The position of the furnace is rapidly
reversed after pouring and molten slag is poured through the open top. The
entire process is carried out in 20 to 40 minutes. When several furnaces are
operated in a group, the cycle time for a single furnace is likely to be between
30 and 50 minutes.
CHEMISTRY AND PHYSICS OF THE PROCESS
The charge to a BOF furnace typically consists of about 70% hot metal
from a blast furnace, and 30% scrap steel. Other ingredients are lime, fluorspar
and other fluxes. These materials interact to produce ordinary low carbon steel.
Additional carbon and other alloying ingredients such as ferrochromium and
160
-------
ferromanganese are added to individual heats to produce special alloys.
However, these do not enter into the formation of air pollutants in the BOF,
and will not be discussed here.
HOT METAL COMPOSITION
The hot metal leaves the blast furnace at a temperature on the order of
2450° F. The blast furnace operates at a pressure of two or three atmospheres
with a high CO content in the gas phase, and produces a hot metal composition
typically as follows:(5'
Component Weight %
Fe 93.8
C 4.4
Si 0.8
P 0.25
Mn 0.75
100.00
The hot metal withdrawn through the iron notch on the blast furnace
produces several emissions whenever it is exposed to the air. These are:
1. CO
2. Red iron oxide
3. Kish
The CO evolution doesn't produce any significant pollution problem,
because it burns immediately to C02- The iron which vaporizes does produce
fuming and is responsible for emissions at the points of transfer into the ladles
and furnaces. Collectors are frequently provided at reladling stations. The vapor
pressure of iron is given inFigure 45.The inclusion of carbon in the liquid phase
tends to reduce the boiling point and increase the vapor pressure of iron
substantially. The addition of oxygen tends to have the opposite effect. (This
effect is probably due in part to the formation of FeO).
Kish is a flaky, black material which is ordinarily presumed to form
spontaneously whenever hot metal with a carbon content greater than the
eutectoid value (4.5% C for pure iron, and less for iron containing silicon or
161
-------
a.
CO
O
UJ
cc
CO
CO
UJ
cc
a.
<
a
o
1
1
A
K
e
0
-9
10
11
1*5
14.
10
M
/
f_
/
/
/
/
f
/
/
/
/
/
/Mn
n
>
/
— ^-
/
/
r
4
/
f
1
1
1
/
/
/
/•
/
/
/
/Fe-
/
f
\
'siO:
/
/
>
4
/
/"IV
/
/
//
/
>
4
/
/
/
/
InO /t
tf
if
f
i
/
/
J^
X
/
/
^
/>
/
L
>
/
/
f
/
*>»*
4
/
/
4\
://
w
/
t
/
,'
XH
^'
/
/
/c
^
^-
4
/
/
/
^Si
^
MgO
/
/
^
°2
X
^^.
^
200 400 600 800 1000 1200 1400 1600 180012000 2200 2400 2600 2800
TEMPERATURE, °C
FIGURE 45
VAPOR PRESSURE OF IRON AND OTHER MATERIALS
OF IMPORTANCE IN BOF STEELMAKING
162
-------
oxygen) is cooled below the liquidous temperature.12' This results in the
formation of solid FeoC which is unstable and decomposes into graphite and
(6)
iron.1
Reactions Prior To Charging
The reactions taking place in the hot metal charging equipment and in the
BOF prior to oxygen lancing may be represented as follows:
co(dissolved) •+ C0 +
and
CO + 1/2 02 ->• C02
which represent out-gassing and burning of CO.
Fe(liquid) - Fe(vapor)
and
Fe(vapor) + 1/202 ^ Fe°(vapor)
or
Fe(vapor) + 1/3°2 - 1/2 Fe2°3(vapor)
These represent the vaporization and oxidation of iron to form red fume, and
finally
->• \
Fe(liquid) + 1/3 C(disso!ved) 1/3 Fe3'C(solid)
1/3 Fe3C(so|id) - Fe+1/3C(graphjteso|jd)
which represent the formation of kish.
REACTIONS IN THE BOF
The reactions taking place in the BOF during oxygen lancing are mainly
involved with oxidizing carbon, phosphorus, manganese, sulfur, and silicon.
The mechanism involves impinging commercial purity oxygen on the surface of
163
-------
the molten metal with sufficient force to penetrate the slag layer and cause
violent contact with the hot metal surface. Oxygen dissolves in the molten
metal and diffuses rapidly through the melt. The reactions involved in
purification are:
Fe(liquid) + 1/202 -* Fe°(dissolved)
Fe°(dissolved) + c(dissolved) Fe(liquid) + C0 f
Fe°(dissolved) + Si(dissolved) ^ Fe(liquid) + Si°2(liquid slag)
Fe°(dissolved) + 2/5 p(dissolved) + Fe(liquid) + 1/5 P2°5 +
Fe°(dissolved) + 1/2 Mn(dissolved) ^ Fe(liquid) + 1/2 Mn°2(liquid slag)
The formation of CO bubbles in the melt is responsible for a violent
boiling action which adds to the turbulence created by the impingement of the
liquid oxygen jet and brings about the formation of a great deal of atomized
droplets of molten iron, many of which oxidize.
HEAT BALANCE
A great deal of heat is released by oxidation of the impurities in the metal.
The burning of carbon is of prime importance, but oxidation of the other
impurities and oxidation of a part of the iron also add significantly to the heat
production. During the 20 minute lancing, the temperature increases from
2300 to 2400° F to about 2900° F, in spite of a large heat loss to the products
of combustion of carbon and other components of the melt with oxygen.
In order to provide a good heat balance of the melt, it is necessary to
remove some heat. This is most conveniently done by adding about 30% cold
scrap steel which must be reprocessed anyway. Scrap additions are made for
end point temperature control. The reasons that 30% scrap is used are
economics and the availability of heat for melting. The scrap serves to "soak
up" some of the heat of combustion. If more than 30% scrap is to be recycled
to the melt, it is necessary to preheat the scrap. This is common practice in
Europe, and is gaining in popularity in the U.S., particularly in plants where the
supply of hot metal is limited or marginal. The preheating of scrap is
accomplished in much the same manner as the regular blow except that a
separate oxygen-fuel lance with much lower flow rates is used and the oxygen
is mixed with natural gas or oil, and ignited prior to insertion into the vessel.
The preheat cycle usually takes from 10 to 15 minutes.
164
-------
The time-concentration relationship for each of the dissolved impurities in
atypical BOF operation is shown in Figure 46(2)'
Theoretical Oxygen Requirement
The quantity of oxygen required during the blow period may be estimated
on the basis of an average gas composition leaving the furnace top of 87% CO
and 13% CO?. The total requirement must include sufficient oxygen to
eliminate substantially all of the carbon in the melt, plus the metalloid
(phosphorus, silicon, etc.) and a fraction of the iron. Between 40 and 70 Ib. of
Fe2O3 are ordinarily collected per ton of steel produced.l8)Table 64shows a
sample calculation of the total oxygen requirement and products of
combustion for a 100 ton melt. The oxygen lancing is usually carried out at a
steady rate throughout the blow.
However, both the flow rate and composition of emitted converter
products vary during the blow period.
GAS EFFLUENT FROM BOF STEELMAKIIMG
In addition to the products of combustion, air is drawn into the hoods to
provide for combustion of CO to C02, and leakage of air into the system will
occur. For the design of air pollution control systems, it is necessary to design
for total flow as a function of furnace size, oxygen blow rate, excess air, metal
composition, type of gas cooling used (steam or water), with an allowance for
shop air cleaning in the vicinity of the BOF.
Figure 47 illustrates two patterns of flow rate variation with time181,
while Figure 48 is a plot of the volume of total gas discharged in ACFM at
combustion temperature versus the volume of oxygen blow.11' Gases are
evolved during the blow period ranging from 200,000 to 1,200,000 ACFM at
temperatures between 3,000 and 3,500°F(9). The inclusion of enough air for
combustion of the CO will raise the temperature to over 4,000° F.
In Table 65 the gas composition is calculated on the basis that there is
100% conversion of blown 02 to CO at the peak flow rates, that the tight hood
draws a constant amount o.f infiltrated air at all periods of the blow, and that
the open hood system maintains constant SCFM of products during the entire
blow.
165
-------
TABLE 64
CALCULATION OF OXYGEN REQUIREMENTS
FOR 100 TON MELT
(70% Hot Metal, 30% Scrap Steel)
Charge
Ib/Melt
Weight
%
Scrap Steel
Hot Metal
Fe
Carbon
Silicon
Phosphorus
Manganese
143,730
6,742
1,226
383
1,149
65,670
153,230
30
70
(65.66)
( 3.08)
( 0.56)
( 0.18)
( 0.52)
Total
153,230
218,900
100.0
Oxygen Required For Ib oxidized
Ib oxygen/
Ib oxide
Ib oxygen
required
Fe*
Carbon
Silicon
Phosphorus
Manganese
3,770
6,742
1,226
383
1.149
0.425
1.50
1.14
1.29
0.58
1,600
10,013
1,400
494
666
*Based on 40 Ib/ton Fe or 55 Ib/ton Fe203.
14,173
166
-------
TABLE 65
CALCULATED GAS COMPOSITION FOR 100 TON BOF
BLOWN AT 12,000 SCFM O2 RATE FOR 20 MINUTES
CO
C02
°2
N2
Total
Combustion
Air Induced
Converter Emissions
Total/Heat
Lb
11,800
2,800
14,600
SCF
161,000
24,000
185,000
Peak Rate
SCFM
24,000
0
24,000
Open 1,426,000
Tight 114,200
Peak Gas Flow
Rates After
Combustion,
SCFM
Tight Hood
(10% Com-
bustion)
21,600
2,400
0
4,510
28,510
Open Hood
(20% Excess
Air)
0
24,000
2,400
54,150
80,550
5,710 68,550
Peak Hood Gas Flow Rates, ACFM
Lower Portion
of Hoods
Tight
at
3200 F
152,000
16,900
0
31,800
200,700
Open
at
4000 F
0
206,000
20,600
465,000
691,600
Leaving Hoods
Tight
at
1800F
94,000
10,400
0
19,600
124,000
Open
at
3000F
0
160,000
16,000
361,000
537,000
O)
-------
FIGURE 46
IMPURITY CONTENT AS A FUNCTION OF TIME
DURING OXYGEN LANCING
4.0
O
O
O
O
3,0.
2.0
UJ
w
UJ
1.0
1
oc
•*• ^.^ Mn
0 2
8 10 12 14 . 16 , 18
TIME, MINUTES
0.08
0.06
0.04
cc
O
X
w
O
I
a.
aT
LL
0.02
20 22
168
-------
co z
< O
"I
/
8.5
UI
I 5
SHOP A
CO2 FLOW AS MEASURED
C02 - MAXIMUM
THEORETICAL FROM
62 BLOWING RATE
BLOWING TIME
z
o
* .3
g o
3;£
§'t
SHOPS
CO2- MAXIMUM THEORETICAL
FROM O2 BLOWING RATE
CO2 FLOW
AS MEASURED
BLOWING TIME
FIGURE 47
TWO PATTERNS OF FLOW RATE FROM BOF's
169
-------
o
CO
z
o
00
Z
LLI
>
X
o
LL
O
01
18
16
14
12
10
8
6
4
2
VESS.EL TONNAGE, NOMINAL
—O
,90T
165T
162T
200T
>/T
0 50 100 150 200 250 300 350 400 450
EXHAUST GAS VOLUME, 1000 ACF
FIGURE 48
VOLUME OF BOF GAS DISCHARGE VS. OXYGEN BLOW RATE
170
-------
PARTICULATE CONTAMINANTS
The participate matter collected in BOF gas cleaning equipment consists
mainly of iron oxide. Concentrations of 85 to 95% are common for an open
hood or full combustion type system.'101 Most are small (less than 1 y),
rounded particles of red iron oxide ^6203). Some particles of black oxide or
magnetite ^6364) are present, usually covered with red oxide.(1) The other
constituents are mainly metalloid oxides (MnC^^C^ and Si02) or slag
components (CaO, Na20, etc.)(10)
Particle size is generally agreed to be very small, with reports of
95%<0.1yand 99%<0.2y.(1) Sargent'101 suggests that the primary
particles formed by condensation are around 0.01 to 0.1 y in diameter, but
that they easily agglomerate, forming particles 1 y and larger. This mechanism,
which produces rapid particle growth below about 0.3 y , would account for
the large differences reported by various investigators; the growth was arrested
at different stages by different experimenters according to where they took
their samples.
Concentrations of dust during the blow have been reported between 6
gr/SCF and 15 gr/SCF. However, more data is available for the total rate of
production than for the concentration. Values between 40 and 70 Ib/ton of
steel are reported.'81 It is very difficult to obtain grain loadings on an
instantaneous basis because of the fluctuations in gas flow, temperature and
dust content with time
In a "partial combustion" system, oxidation of the emitted particulates to
the fine red oxides is apparently arrested, due to the reducing atmosphere
present in the partially combusted gas. The resultant dust is black in color, and
reportedly of slightly larger size. Total solids evolution in a "closed" system is
lower than in a conventional, and averages about 20 Ib/ton of steel. However,
because of the severely reduced gas volumes which convey it, the dust loading
(gr/SCF) is greater than in a "full combustion" system where loadings are
diluted by large amounts of gas.
POLLUTION CONTROL CONSIDERATIONS
In the operation of the BOF shop there are four important sources
requiring pollution control:
1. Reladling or mixing operations
2. Hot metal charging
171
-------
3. Furnace operation
4. Tapping
Reladling and Mixing Operations
Large amounts of kish and iron oxide are released during the transfer of
hot metal to the charging ladle. This kish or oxide can be controlled by a fixed
hood over the transfer station. The gases collected can be processed through
the gas cleaning system for the furnace but experience has generally been that
this source is better controlled by having its own small gas cleaning system.
Hot Metal Charging
During the charging of hot metal to the furnace, large amounts of dense
black smoke are produced, partially released from the hot metal and partially
created from the burning of surface contaminants in the scrap charge.
Because of the tilted position of the furnace during the hot metal charge, the
regular furnace hood is not very effective for controlling these fumes and
auxiliary hoods are required. The hood, located over the charging side of the
furnace, ducts the gases to the furnace gas cleaning system.
Tapping
During tapping, iron oxide fuming occurs. If metallic alloys are added to
the ladle after tapping, a white fuming emission often results. This area is also
beyond the furnace hood. To date this problem has not been controlled and a
workable system has yet to be developed.
HOODING SYSTEMS
Two types of hooding systems are used for BOFs. Open hooding systems
provide a space between the bottom of the hood and the top of the furnace.
This provides room for the furnace to tilt to receive charge and to pour without
movement of the hood. Also, the clearance allows for infiltration of enough air
to bring about complete combustion of the CO in the flue gas.131
Closed hooding systems provide some form of movable members to allow
172
-------
the hood to be attached to the furnace when it is in the vertical position, in
order to prevent infiltration of air. Wheeler131 has indicated that closed systems
are capable of maintaining gas flows of as little as 20% of the flow into open
systems. In addition, there is some potential for recovery of the fuel value of
the CO in mills where additional fuel can be utilized economically. Fairly high
quality CO gas also holds the potential for utilization in petrochemical
processes.
Table 65 illustrates the difference in calculated gas flow for the two
systems. Hood construction to withstand the 3,000° F and higher temperatures
encountered during lancing is of extreme importance. Two systems of
construction of water-cooled hoods are in common use. These are the panel
system, in which the hood and duct are constructed of water-filled panels of
steel, and the membrane system, which utilizes water filled tubes connected by
webs. Steam production to recover some of the sensible heat in the gases has
been used if the plant system can tolerate the very cyclic nature of steam
formation; otherwise the steam is condensed, subcooled, and recycled into the
hood. Often the steam produced is used for conditioning the gas to the
precipitator.
The membrane hood is the most recently developed of the two. It offers
several advantages, principal of which is that it can easily be designed to
withstand internal pressure, and hence can accommodate high cooling water
temperatures or steam formation. Also, it is basically a gas-tight construction
which can be used to hold air leakage to a minimum in closed hood
systems111'. Capital investment, though, will be higher.
The hoods are designed to conduct the hot gases to a quench section
where the temperature is dropped by spraying water into the hot gas stream.
Water sprays are used to bring the gas down to about 450 to 550° F in the case
of precipitator installations, and 150 to 185°F for wet scrubbers.191
APPLICABLE POLLUTION CONTROL EQUIPMENT SYSTEMS
Venturi scrubbers and electrostatic precipitation are the two methods in
use for BOF gas cleaning. Since 1957, there have been 92 BOFs installed in
North America. Of these, 45 have been equipped with precipitators and 47
with high energy scrubbers.181 Fabric collectors are considered unsuitable
because of the high temperature gases and extreme variability of flow, although
they have been applied in Europe.'31 These factors tend to produce
temperature upsets which might destroy the bags in a conventional fabric
collector. The hazard involved with possible CO combustion in electrostatic
173
-------
precipitators makes them less desirable for closed-hood systems, and such
systems require elaborate controls. Several such installations are in operation
outside the U.S.
Either precipitators or scrubbers are capable of producing the high
efficiency levels required to meet air pollution regulations or to obtain
color-free stacks. In either case, the application requires special considerations
because of the high temperatures and intermittent nature of the operation. The
system is extensive because of the large gas flows involved.
Precipitators have the advantage of operating at high enough temperatures
to produce a gas stream which will not generate a steam plume except in very
cold weather. Also, they do not require a high pressure drop and, hence, use
much less horsepower than a scrubber. Several drawbacks also exist. The
resistivity of the collected fume materials is high, and careful control of the
moisture in the gas stream is required to "condition" the dust, and bring the
resistivity to an acceptable level. This may require injection of steam at the
beginning and end of the cycle.131 For most precipitator installations in the
U.S., the gas volumes range between 500,000 and 1,000,000 ACFM.
Scrubbers require upwards of 40 inches of water column in order to
produce suitable emission levels. This requires a very large fan and high horse-
power driver. In addition, the scrubber system has the potential for production
of an objectionable steam plume. In order to avoid this, it is customary to
install an after-cooler between the scrubber and. fan which condenses a
substantial fraction of the water vapor before it passes through the fan. This
also reduces substantially the total quantity of gas which is reflected in a
considerable reduction of fan power requirements.
The scrubber produces a slurry of iron oxide and water which cannot be
discharged into rivers or lakes, and must be treated to separate the dust.
Usually, clarifiers are provided to settle the dust, and frequently filters or
centrifuges follow to provide a wet, but solid oxide product.
Although complex, the scrubbing system has generally given satisfactory
service in BOF operation. The recovered product does not have the dusting
problems involved in precipitators. Also, if there is no zinc (from galvanized
scrap) in the BOF charge, the fines collected may be recycled directly through
the sinter plant to provide fresh charge for the blast furnaces, whereas dust
from precipitators requires wetting and pugging before going to the sinter
plant.
Because of the cyclic operation of BOF steelmaking, the maintenance
174
-------
requirements for either scrubbers or precipitators are higher than those
required for continuous industrial processes. Auxiliary equipment, such as
handling systems for the collected oxides, must take into consideration the
cyclic operation, and all auxiliaries must be functional to realize long term
optimum performance of the pollution control system.
SPECIFICATIONS AND COSTS
Specifications were originally written for 75 ton and 300 ton furnace
capacities. At the request of the EPA Project Officer, the size of the smaller
unit was increased to 140 ton. In addition, the specifications were originally
intended to cover only the equipment ordinarily supplied by the air pollution
control equipment manufacturers. This does not include the hooding and
ductwork, except in the case of the closed hood system. In order to put the
equipment prices on a comparable basis, the specifications were modified to
include both hoods and ductwork.
Precipitator specifications are given in Tables 66 and 67. These are only
for the open hood arrangement. The cost data submitted is listed in Tables 68
and 69. The data is plotted in Figures 49 through 52 for both the intermediate
efficiency (LA—process weight) case and high efficiency cases.
The precipitators quoted do not show detailed breakdowns for the cost of
auxiliaries. This is because the costs in most cases were scaled from actual bid
prices of recent installations. This process did not permit the scaling of
individual prices of the auxiliary equipment.
The specifications for scrubbing equipment are given in Tables 70 and 71
for the open hood system, in which air is induced into the hoods over the
furnaces to complete the combustion of CO. The first costs and operating costs
are given in Tables 73 and 74 and plotted in Figures 55 and 56.
Figures 55 and 56 represent costs for the high efficiency cases only. The
operating cost figures are probably less accurate than the first cost values
because the manufacturers do not have direct responsibility for operating costs
as they do have for the cost of equipment.
The closed hood systems are specified in Tables 70 and 72, and the capital
and operating costs given in Tables 75 and 76.
In these systems, the flow of air into the furnace is limited and the CO
175
-------
produced in the furnace remains unburned in the gas cleaning system. This
presupposes that the gas will be used for fuel within the plant and will NOT be
discharged into the atmosphere without some further processing in a furnace.
The specifications were, however, written as though it would be discharged
from the fan, and the grain loadings set accordingly. One of the bidders stated
that he would not be willing to guarantee performance at the high efficiency
level in either the open or closed hood case.
The pressure levels are given in the specifications at various points in the
system. This was done in order to establish the flowing volumes and other
properties of the gas streams at the fan, the scrubber, etc. There was no
intention here to guide the manufacturers with respect to the pressure levels
required for the scrubber and other equipment items. The responses were based
on the manufacturers estimates of the most suitable pressure drop. One of the
manufacturers wished to keep the pressure drop requirement confidential.
Another responded with the following pressure drop information.
Required
A P, in w.c.
Open Hood Closed Hood
Scrubber for
LA—Process wt
small 44 " 23
Large 51 27
High Efficiency 61 42
Cooler for
LA—Process wt 76
High Efficiency 8 5
Costs for abatement equipment operating at removal efficiencies better
than the "high efficiency" cases were solicited from the same sets of bidders as
those who provided the original costs. Table 77 shows the capital costs for
scrubbers operating at 0.005 gr/ACF outlet grain loading. Table 78 shows
comparable data for precipitators operating at outlet grain loadings of 0.005
gr/ACF and 0.0025 gr/ACF. These data represent estimates only. The
manufacturers who quoted the numbers would be reluctant to guarantee
performance at these levels due to the lack of operating data.
176
-------
TABLE 66
ELECTROSTATIC PRECIPITATOR PROCESS DESCRIPTION
FOR BOF STEELMAKING SPECIFICATION
The air pollution abatement system is to serve a new BOF shop in which two furnaces
will be installed. The operating cycle is to involve operation of one furnace at any given
time, with the second out of service for refining, or on standby. The precipitator shall be
designed to accommodate the gas flow produced by lancing a single furnace at any one time.
The system shall be quoted complete including all of the following as detailed in our
drawings: *
(1) Dirty gas mains
(2) Gas conditioning equipmen t
(3) Inlet header
(4) Electrostatic precipitator(s)
(5) Dust transfer and storage hoppers
(61 Fans, dampers, and pressure control system
^7) Outlet ductwork and stack
(8) Auxiliary equipment
*NOTE: It is customary for integrated steel companies to undertake major system design
projects with their own engineering personnel. Detailed drawings might well accompany
requests for final contract bids.
In addition to the design specifications for the precipitator given in Section 3, the
following operating data is given for the BOF shop:
Small Large
Capacity, ton/melt 140 250
Oxygen lance rate, Ib/hr 86,000 152.000
Oxygen lance rate, SCFM 16,800 30,000
Operating cycle, minutes 50
Charge scrap 5
Charge hot metal 3 Throttled flow
Charge time 1
Blow 2O
Sample 3 Full flow
Finish blow 2
Tap 3
Pour slag 3 Throttled flow
Idle 5-10
177
-------
TABLE 66 (cont.)
The cycle for the two furnaces shall be timed in such a way that both are not being
blown at one time. Therefore, the dust collection system will be required to handle the
maximum flow from one furnace plus throttled flow from the other during lining burn-in.
Membrane hoods and evaporation chambers shall be provided by others on each
furnace so that for the purposes of this specification, the scope of the gas cleaning
installation shall begin at the outlet of the hood evaporation chamber. The volumes and gas
temperatures given in Section 3 shall apply at this point. The bidders shall take into account
all temperature losses and gas conditioning through the system furnished by them.
'• Dirty Cas Mains from the outlet of each hood shall be provided to a common main
carrying the gases to the inlet header of the precipitator. Each individual main shall be 120'
long running from the top of the mill building to the main on the eave of the building, and
shall contain an isolation damper with controls for full flow, throttled flow and closed
operating conditions. A motor operated isolation gate shall also be provided downstream of
each damper to facilitate repairs to the dampers, while the rest of the system is operating.
The common main to the precipitator inlet header shall be sized to maintain carrying
velocities during one furnace operation, and yet not have so great a velocity under two
furnace operations as to create excessive pressure drops. It will be 350' long.
2. Gas Conditioning Equipment in the form of steam sprays, shall be furnished in the
common dirty gas main to provide for additional moisture during the periods at the start and
finish of each blow, when the quenching water may not be sufficient to provide the proper
moisture content for efficient precipitation.
3. Inlet Header shall be provided to receive the gases from the dirty gas main and assist in
distribution to all the precipitator chambers.
4- Precipitators shall be single stage, plate type units, with a minimum of two fields in the
direction of gas flow for the intermediate efficiency case, and three fields in the direction of
gas flow for the high efficiency case. Inlet face velocity shall not exceed 4 FPS in either case.
The precipitator shall be divided into gas tight chambers parallel to gas flow and shall be
sized to have one spare chamber when operating one furnace. Each chamber will have slide
gates at inlet and outlet, in order to isolate the chamber for repairs while the remainder of
the precipitators are operating. Dampers or similar flow balancing device shall be furnished
for each chamber.
Automatic controls shall be provided to continuously optimize the voltage level in each
independent field. All control circuits shall be energized through a safety interlock system so
that no access to high voltage equipment can be made without first de-energizing all fields.
Hoppers shall be separate for each field, or shall be equipped with partition plates to
prevent bypassing of uncleaned gas through the hoppers. Hopper capacity shall be such that
operation can be maintained for 8 hours after failure of any piece of dust transfer
equipment.
All materials of construction are to be carbon steel. The minimum plate thickness shall
be 3/8", except for collecting electrodes.
178
-------
TABLE 66 (cont.)
5. Dust Removal & Storage equipment shall be provided for continuous removal of dust
from the precipitator hoppers and conveyed to a dust storage bin. The dust storage bin shall
have sufficient capacity for storage of all dust from 48 hours of continuous operation and
shall be arranged to facilitate clean removal by truck.
6. Fans and dampers shall be provided to move and control the volume of gas called for in
Section 3. The fans shall develop sufficient static pressure to adequately draft the furnace
hoods without puffing. Three (3) fans shall be provided and sized so that any two fans can
provide adequate draft for handling the full flow conditions from one furnace and the
throttled flow from the other furnace. The arrangement will be compatible for the future
addition of fans to move the volume of gas generated by two furnaces blowing
simultaneously. A pressure control system shall be provided to balance the flow between
precipitator chambers and balance the load between fans while maintaining a system set
pressure by controlling fan inlet dampers.
7. Outlet ductwork and stack will be required to convey the cleaned gases to the
atmosphere. The discharge from each fan should go to a common header leading to a
common stack. The stack should be 200' in height.
The precipitator, hoppers, inlet header and all ductwork from the beginning of the system to
the outlet flange of the fans shall be insulated with three (3) inches of insulation and covered
with 24 ga. galvanized steel.
8. Auxiliary equipment required for the operation of the system, shall be furnished. This
will include Control Room building for the gas cleaning equipment, control room, 440V
motor control center, systems controls, instrumentation and lighting.
179
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TABLE 67
ELECTROSTATIC PRECIPITATOR OPERATING CONDITIONS
FOR BOF STEELMAKING SPECIFICATION
Two efficiency levels are to be quoted for each of two sizes for the open hood system
described. The high efficiency case is listed first.
Small Large
Process Capacity, ton/melt 140 250
Oxygen Blowing Rate, SCFM 17,000 30,000
Waste Gas Volume <§> design
Blowing Rate @ 650° F, ACFM 530,000 950,000
Gas Temperature & Inlet to
Gas Cleaning System, ° F 650 650
Precipitator Design Pressure, in, w.c. -15 -15
Inlet Dust Loading, gr/SCF, dry 12 12
Inlet Dust Loading, Ib/hr 23,200 41,000
Outlet Residual, gr/ACF 0.010 0.010
Outlet Dust Loading, Ib/hr 45.6 81.5
Required Efficiency, % 99.80 99.80
% Moisture @ 30 sec. after 02
& up to last 2 min. of blow 15 15
Gas Volume @> throttled operation
and vessel lining burn in, A CFM 55,000 100,000
Gas Volume for leakage through
dampers of idle vessels by bidder
The system is to be designed for an operating volume of 530,000 or 950,000 ACFM @
650 degrees entering the system from one active furnace plus the leakage from the two other
furnaces.
As an alternate, the bidder shall describe the additional equipment necessary to handle
the full flow from one furnace and the throttled volume from another furnace, which may
be being charged at the same time.
For the purpose of fan sizing, the following pressure drops will be used:
a. Hoodand evaporation chamber, in.w.c. 2
b. Ductwork from evaporation chamber
to inlet header, in.w.c. 4
c. Inlet Header through precipitator to fan By Vendor
d. Fan to stack outlet By Vendor
Alternatively, the intermediate efficiency level should be quoted for the same inlet
conditions, but with the following loadings and efficiency:
Solids, Ib/hr 40 40
Solids, gr/ACF 0.0088 0.0049
Required Efficiency, % 99.83 99.9
180
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181
-------
TABLE 68
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR ELECTROSTATIC PRECIPITATORS FOR BOF STEELMAKING
Effluent Gas Flow ^
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow (2)
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF (2)
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other \
(4) Total Cost
LA Process Wt.
Small
600,000
650
286,000
4.5
23,200
600,000
650
286,000
0.0078
40
9.9.83
747,000
5,202,000
(Includes
1,940,OQQ
for
hoods)
5,949,000
Large
1,020,000
650
535,000
4.5
41,000
1,020,000
650
535,000
0.0046
40
99.9
1,249,250
6,551,47=
(Includes
2,330,000
for
loods)
7,800,725
High Efficiency
Small
600,000
650
286,000
4.5
23,200
600,000
650
286,000
0.01
51.5
99.8(3)
700,400
5,162,330
(Includes
1,940,000
for
hoods)
5,862,730
Large
1,020,000
650
535,000
4.5
41,000
1,020,000
650
535,000
0.01
51.5
99.8(3)
1,140,800
5,862,730
(Includes
2,330,000
for
hoods)
7,003,530
182 (1) Based upon two quotations.
(2) Includes leakage through non-lancing furnace hood
(31 Prices below correspond to 99,88% efficiency
-------
TABLE 69
.ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS FOR BOF STEELMAKING
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor ( if any)
Operator
Supervisor
Total Operating Labor
Maintenance ( 2 )
Labor
Materials
Total Maintenance
R eplacement Parts ( 3 )
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7850
$6/hr
$8/hr
$.011/kw-
LA Process Wt.
Small
-
147,400'
29,900
\r 83,675
83,675
260,975
594,900
855,875
Large
<-
167,400
34,200
131,700
131,700
333,300
780,072
.,113,372
High Efficiency
Small
-
147,400
29,900
83,675
83,675
260,975
586,273
847,248
Large
-
167,400
34,200
131,700
131,700
333,300
757,560
1,090,860
53
CO
(1) Based upon two quotations
(2) Based on 5% of system cost
(3) Based on 1% of system cost
-------
FIGURE 49
CAPITAL COSTS FOR PRECIPITATOR SYSTEMS
FOR BOF STEELMAKING
(INTERMEDIATE EFFICIENCY)
7000
5000
co
DC
O
Q
u.
O
CO
Q
I
O
X
CO
O
O
4000
3000
2000
1000
800
• TURNKEY INSTALLATION
COLLECTOR ONLY
60
80
100
200
300
400 500 600
PLANT CAPACITY
TONS
184
-------
FIGURE 50
ANNUAL COSTS FOR PRECIPITATORS
FOR BOF STEELMAKING
(INTERMEDIATE EFFICIENCY)
COST, THOUSANDS OF DOLLARS
£3 y *> ui en >j o
§ 88888 8
^
*J&^
^-^
^
^
^
^
^
OPER
(OPEF
CAI
AT ING
TOT>
I ATI IV
SITAL
COS
XLC(
JGCC
. CHf
T
)ST
)ST
VRG
PLL
ES)
S
00 200 300 400 500 600
PL ANT CAPACITY
TONS
185
-------
FIGURE 51
CAPITAL COSTS FOR PRECIPITATOR SYSTEMS
FOR BOF STEELMAKING
(HIGH EFFICIENCY)
LLARS
LL
O
V)
Q
I
O
H 2000
te
O
o
COLLECTOR ONLY
TURNKE
SYSTE
100
200
500
PLANT CAPACITY
TONS
186
-------
FIGURE 52
ANNUAL COSTS FOR PRECIPITATORS
FOR BOF STEELMAKING
(HIGH EFFICIENCY)
1000
CO
-------
FIGURE 53
CONFIDENCE LIMITS FOR CAPITAL COSTS
OF PRECIPITATORS FOR BOF STEELMAKING
(LA-PROCESS WEIGHT)
V)
cc
O
G
LL
O
3
V)
O
X
GO
O
O
4000
3000
2000
1000
800
600
500
400
300
*
'V
90%
73%
MEAIV
75%
60 80 100 200 300 400 500
PLANT CAPACITY TONS
188
-------
FIGURE 54
CONFIDENCE LIMITS FOR CAPITAL COSTS
OF PRECIPITATORS FOR BOF STEELMAKING
(HIGH EFFICIENCY)
CO
DC
o
o
LL
O
V)
Q
<
00
D
O
I
000
nnn
nrm
800
oUU
ROO
400
nn
/
/
/A
X X
' fS /
X X^
fij '
,**
^ I
X
2
X X
^x>
^/ y^
^ X
,®'
s
*
JCT^
^
90%
75%
/
/ ME
X '
^^«
***
\N
5%
90%
60 80 100 200
PL ANT CAPACITY
300 400 500 600
TONS
189
-------
TABLE 70
WET SCRUBBER PROCESS DESCRIPTION
FOR BOF STEELMAKING SPECIFICATION
The air pollution abatement system is to serve a new BOF shop in which two furnaces
will be operated. The scrubbing system shall be designed for oxygen lancing of a single
furnace at any one time, but provision for future gas cleaning equipment to handle two
lancing operations simultaneously shall be made.
The system shall be quoted complete including all of the following items as detailed in
dur drawings: *
(J) In terconnec ting due twork
(2) Quench chamber(s)
(3) Venturi scrubber(s) with mist eliminators
(4) After-cooling chamber (s)
(5) Cooling tower(s)
16) Fan(s)
17) Single 200 foot stack
The system shall be quoted on each of the following bases:
(1) Scrubber(s) only
(2) Complete equipment, consisting of
la) Scrubbers
(b) Cooling chambers and towers
(c) Fans
*NOTE: It is customary for integrated steel companies to undertake major system design
projects with their own engineering personnel. Detailed drawings might well accompany
requests for final contract bids.
(3) Complete turnkey system
In addition to the design specifications for the scrubber given in Section 3, the
following operating data is given for the BOF shop:
190
-------
Smal! Large
Capacity, ton/melt 140 250
Oxygen lance rate. Ib/hr 85,000 152,000
Oxygen lance rate (SCFMj 16,800 30,000
Operating cycle, minutes 50
Charge scrap 5
Charge hot metal 3 Throttled flow
Charge lime 1
Blow 20
Sample 3 Full flow to scrubber
Finish Blow 2
Tap 3
Pour slag 3 Throttled flow
Idle 5-10
The cycle for the two furnaces shall be timed in such a way that both are not being
blown at one time. Therefore, the scrubbing system will be required to handle the maximum
flow from one furnace, plus throttled flow from the other during lining burn-in.
Scrubbers shall be Venturi-type with sufficient pressure drop to perform as specified in
Section 3. The liquid-gas ratio shall be specified by the vendor but shall in no event be lower
than 5 GPM per 1,000 ACFM (saturated). Vendor shall specify the actual pressure drop at
which the scrubbers will operate.
Aftercoolers shall reduce the temperature of the gas exiting the scrubbers to 95° F. by
counter-current contact with 90°F. cooling water. The aftercoolers and cooling towers shall
be provided as a part of the turnkey proposal.
Fans shall be capable of overcoming the system pressure drop at the design flow rate
while operating at no more than 90% of "red-line" speed. Motors shall be capable of driving
fans at "red-line" speed and the corresponding pressure differential at 20% over the design
flow rate.
Slurry Settler(s) shall be capable of producing a reasonably thickened underflow
product while returning water fully treated to minimize solids content.
Filters shall be provided to dewater the slurry product. Filters shall produce a cake with
a minimum of 70% solids, suitable for transportation by open truck. A minimum of two
filters shall be provided, such that one may be out of service for repair at any time without
interfering with normal operation.
191
-------
TABLE 71
WET SCRUBBER OPERATING CONDITIONS
FOR BOF STEELMAK1NG SPECIFICATION
(OPEN HOOD SYSTEM)
Two efficiency levels are to be quoted for each of two sizes for the open hood system
described. The high efficiency case is listed first:
Process Capacity, ton/melt
Process Weight, ton/hr*
Scrap Steel
Hot Metal
Fluxes
Total
Small _
140
110
258
22
390
Large
250
197
460
41
698
Gas from Furnace
Temp., °F 4,000
Pressure, psia 14.7
Pressure, in w.c. -1
FlowACFM 970,000
Gas to Scrubber**
Temp., °F 3,000
Pressure, psia 14.6
Pressure, in w.c. -3
* Based on two blow periods per 50 minute cycle
**Prior to water contact
Flow A CFM (A vg. over blow)
Composition, mol %
CO
CO2
N2
°2
H2O
Solids loading, Ib/hr
Solids loading, gr/ACF
Solids loading, gr/DSCF
Gas from Scrubber
Temp., °F
Pressure, psia
Pressure, in w.c.
FlowACFM (Avg. overblow)
Composition, Mol %
CO
C02
N2
°
750,000
0.0
29.8
67.2
3.0
0.0
23200
3.6
24
180
13.1
-45
366,000
0.0
12.7
28.6
1.3
57.4
4,000
14.7
-1
1,730,000
3,000
14.6
-3
1,340,000
0.0
29.8
67.2
3.0
0.0
41,000
3.6
24
180
13.1
-45
655,000
0.0
12.7
28.6
1.3
57.4
192
700.0
100.0
-------
Solids loading, Ib/hr
Solids loading, gr/ACF
Solids loading, gr/DSCF
Scrubber Efficiency, %
Gas from Cooling Tower
Temp., °F
Pressure, psia
Pressure, in w.c.
Flow, ACFM
Gas Comp. Mol %
CO
co
H20
11.1
0.0036
0.0117
99.95
105
12.9
-50
151,000
0.0
27.6
62.3
2.7
7.5
100.0
20.3
0.0036
0.0117
99.95
105
12.9
-50
270,000
0.0
27.6
62.2
2.7
7.5
100.0
Solids loading, Ib/hr
Solids loading, gr/ACF
Solids loading, gr DSCF
Gas from Fan
Temp., °F
Pressure, psia
Pressure, in w.c.
Flow, ACFM
Solids loading, Ib/hr
Solids loading, gr/ACF
Solids loading, gr/DSCF
11.1
0.009
0.0117
130
14.7
0
132,000
11.1
0.010
0.0117
20.3
0.009
0.0117
130
14.7
0
235,000
20.3
0.010
0.0117
Alternatively, the intermediate efficiency case should be quoted for the same inlet
conditions as specified previously, but with the following outlet loadings from the scrubber.
Small Large
Gas from scrubber
Temp., °F
Pressure, psia
Pressure, in w.c.
Flow, ACFM
Water Content, Mol'.
Solids loading, Ib/hr
Solids loading, gr/ACF
So/ids loading, gr/DSCF
Scrubber Efficiency, %
180
13.1
-45
366,000
57.4
40
0.0122
0.0412
99.83
180
13.1
-45
655,000
57.4
40
0.00715
0.023
99.9
193
-------
TABLE 72
WET SCRUBBER OPERATING CONDITIONS
FOR BOF STEELMAKING SPECIFICATION
(CLOSED HOOD SYSTEM)
Two efficiency levels are to be quoted for each of two sizes for the closed hood system
described. The high efficiency case is listed first.
Process Capacity, ton/melt
Process Weight, ton/hr*
Scrap Steel
Hot Metal
Fluxes
390
698
Gas from Furnace
Temp., °F
Pressure, psig
Pressure, in w.c.
Flow,ACFM
Gas to Scrubber
Temp., °F
Pressure, psig
Pressure, in w.c.
Flow,ACFM
Gas Composition, Mol'.
CO
CO2
N2
°2
H2O
Solids loading, Ib/hr
Solids loading, gr/ACF
Solids loading, gr/DSCF
Gas from Scrubber
Temp., °F
Pressure, psia
Pressure, in w.c.
Gas Flow, ACFM
Moisture Content, Vol.
Solids loading, Ib/hr
Solids loading, gr/ACF
Solids loading, gr/DSCF
Scrubber Efficiency, %
3200
14.7
-1
282,000
1,800
2
174,000
75.8
8.4
15.8
0.0
100.0
23200
15.5
67.5
170
12.7
-55
100.000
47.3
4.2
0.0050
0.012
99.98
3,200
14.7
•1
502,000
1,800
-2
310,000
75.8
8.4
15.8
0.0
100.0
41,000
15.5
67.5
170
12.7
-55
177.000
47.3
7.45
0.0050
0.012
99.98
194
-------
TABLE 72 (cont.)
Gas from Cooling Tower
Temp., °F
Pressure, psia
Pressure, in w.c.
Flow, ACFM
Gas Comp., Mot %
CO
C02
N2
°
Solids loading, Ib/hr
Solids loading, gr/ACF
Solids loading, gr/DSCF
Gas from Fan
Temp., °F.
Pressure, psia
Pressure, in w.c.
Flow, ACFM
Solids loading, Ib/hr
So/ids loading, gr/ACF
Solids loading, gr/DSCF
105
12.5
-60
46.400
70.1
7.8
14.6
7.5
100.0
4.2
0.087
0.012
125
14.7
0
48.500
4.2
0.010
0.012
105
12.5
-60
102.000
70.1
7.8
14.6
7.5
100.0
7.45
0.087
0.012
125
14.7
0
87,000
7.45
0.010
0.012
195
-------
TABLE 73
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR BOF STEELMAKING
(OPEN HOOD)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow C1)
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost (3) N
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment ,
(3) Installation Cost N
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other J
y
>
(4) Total Cost
LA Process Wt.
Small
970,000
3,000
121,000
0
3.6
23,200
132,000
130
121,000
9.7
/2)
o . ds 4
24.0
99.83
287,133
2,592,200
!, 280, 867
i, 160, 200
Large
1,730,000
3,000
200,000
0
3.6
41,000
235,000
130
202,000
9.7
(21
0.020
40.0
99.9
411,16
3,351,06!
2,745,97(
6,508,200
High Efficiency
Small
970,000
3,000
121,000
0
3.6
23,200
132,000
130
121,000
9.7
0.0117
9.1
99.95
287,133
2,603,434
2,287,267
>, 177, 834
Large
1,730,000
3,000
200,000
0
3.6
41,000
235,000
130
202,000
9.7
0.0117
20.3
99.95
411,167
3,364,433
2,749,834
6,525,434
196
(1) At fan discharge.
(2) Lower outlet loadings quoted by one manufacturer as "highest
reasonable".
(3) Includes cooling tower, ductwork and hoods.
-------
TABLE 74
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBER SYSTEMS FOR BOF STEELMAKING
(OPEN HOOD)
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance (1)
Labor
Materials
Total Maintenance
Replacement Parts C2)
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling) (3)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7 Rc;n
S6/hr
S8/hr
$6/hr
$.QLl/kw-hi
$. 25/M Gal
LA Process Wt.
Small
8,690
i 285,500
" 285,500
57,150
247,000
222,500
469,500
820,840
571,500
1,392,340
Large
8,690
j 367,100
367,100
73,810
484,000
404,500
888,500
1,338,100
738,100
2,076,200
High Efficiency
Small
8,690
> 286,500
286,500
57,300
377,300
222,500
599,800
952,290
573,000
1,525,290
Large
8,690
J-367,800
367,800
73,970
606,100
404,500
1,010,600
1,461,060
739,700
2,200,760
CD
(1) Based on 51 of
(2) Based on \\ of
(3) Closed cooling
system cost.
system cost.
systems are used.
Pump HP is in power cost.
-------
TABLE 75
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR BOF STEELMAKING
(CLOSED HOOD)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow ^
ACFM
°F
SCFM (Dry)
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other
(4) Total Cost
LA Process Wt.
Small
174,000
1,800
41,000
0
15.5
23,200
Large
310,000
1,800
73,500
0
15.5
41,000
High Efficiency
Small
174,000
1,800
41,000
0
15.5
23,200
Note
80,000
160
41,000
40
0.010
7.0
99.97
111,850
L
Large
310,000
1,800
73,500
0
15.5
41,000
(2)
143,000
160
73,500
40
0.010
12.6
99.97
207,900
\
/ /
I 1
J2,250,000 K, 900, 000
1
fl
r
1
h
1
f
}
I 1
§4,400,000 >5, 300, 000
1
i
/
6,701,850
1
8,407,900
(1) At discharge to atmosphere
198
(2) OG systems are not ordinarily quoted with cooling towers.
-------
TABLE 76
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBER SYSTEMS FOR BOF STEELMAKING (CLOSED HOOD)
4 - Note 1
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance (2)
Labor
Materials
Total Maintenance
Replacement Parts (3)
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Nitrogen
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7.850
$6/hr
$8/hr
$6/hr
$.01I/kw-ln
$.25/M Gal
$2/Ton
LA Process Wt.
Small
Large
High Efficiency
Small
8,690
338,100
338.100
67,600
67,600
435,000
255,000
47,200
17,500
754,700
1,169,090
573,000
1,742,090
Large
8,690
a fion
420,400
42or4nn
84,100
84,100
660,000 •
255,000
88,500
17,500
1,021,000
1,534,190
739,700
2,273,890
(1) O.G. system quoted without cooling tower, but with auxiliary cleaning system for tilted
furnace.
(2) Based on 5% of system cost.
(3) Based on \\ of system cost.
-------
FIGURE 55
CAPITAL COSTS FOR WET SCRUBBER
SYSTEMS FOR BOF STEELMAKING
(OPEN HOOD-HIGH EFFICIENCY)
8000
CO
cc
t 5000
CO
Q
Z
CO
O
I
8
o
3000
2000
1000
300 400 500 600 800 1000
PLANT CAPACITY, TONS
200
-------
FIGURE 56
ANNUAL COSTS FOR WET SCRUBBER
SYSTEMS FOR BOF STEELMAKING
(OPEN HOOD-HIGH EFFICIENCY)
3000
cr 2000
O
0
u.
O
1
1
g 1000
I
O
o
800
600
400
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
100
200
300
500
PLANT CAPACITY, TONS
201
-------
FIGURE 57
CONFIDENCE LIMITS FOR WET SCRUBBER
CAPITAL COST DATA, BOF STEELMAKING
(OPEN HOOD-HIGH EFFICIENCY)
V)
cc
o
Q
u.
O
V)
O
CO
O
I
O
u
600
400
200
100
200
300 400 500 600 800 1000
PLANT CAPACITY, TONS
202
-------
203
-------
FIGURE 58
CAPITAL COSTS FOR WET SCRUBBER
SYSTEMS FOR BOF STEELMAKING
(CLOSED HOOD-HIGH EFFICIENCY)
8000
CO
cc
O
Q
CO
Q
CO
O
I
O
O
5000
-F
-TURNKEY INSTALLATION.
COLLECTOR PLUS AUXILIARIES
2000
1000
800
600
500
400
300
200
CO
CC
CO
Q
I
O
100
200
300
100
PLANT CAPACITY, TONS
204
-------
FIGURE 59
ANNUAL COSTS FOR WET SCRUBBER
SYSTEMS FOR BOF STEELMAKING
(CLOSED HOOD-HIGH EFFICIENCY)
3000
2000
GO
it
8
u.
O
GO
O
< 1000
CO
O
I- 800
O
u
600
400
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
100
200
500
PLANT CAPACITY, TONS
205
-------
FIGURE 60
CONFIDENCE LIMITS FOR CAPITAL COST OF
WET SCRUBBERS ONLY
FOR BOF STEEL MAKING
o
G
Q
Z
<
CO
z>
O
X
o
o
400
300
200
100
80
60
50
40
7
75%
MEAN
75%
60 80 100
200
300 400 500
PLANT CAPACITY, TONS
206
-------
TABLE 77
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR BOF STEELMAKI1MG
AT VERY HIGH EFFICIENCY
(OPEN HOOD)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow d)
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost (2) \
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
>
(d) Conditioning, [
Equipment
(e) Dust Disposal
Equipment J
(3) Installation Cost N
(a) Engineering |
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other J
>-
(4) Total Cost
LA Process Wt.
Small
Large
High Efficiency
Small
970,000
3,000
121,000
0
3.6
23,200
132,000
130
121,000
9.7
0.005
5.66
99.98
.sys , zuu
2,845,100
2,784,650
6,027,950
Large
1,730,000
3,000
200,000
0
3.6
41,000
235,000
130
202,000
9.7
0.005
10.09
99.98
609,250
3,797,800
3,403,850
7,810,900
co
(2)
Based upon two quotations.
Includes leakage through non-lancing furnace hood.
207
-------
TABLE 78
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR ELECTROSTATIC PRECIPITATORS FOR BOF STEELMAKING
AT VERY HIGH EFFICIENCY
(OPEN HOOD)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost ^
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(1) Other )
>"
(4) Total Cost
LA Process Wt.
Small
600,000
650
286,000
4.5
23,200
600,000
650
286,000
0.005
25.7
99.89
799,800
i, 236, 000
6,035,800
Large
1,020,00(
650
535, 00(
4.5
41,00(
1,020,00(
650
535, 00(
0.005
43.6
99.89
1,286,75(
6,551,475
7,838,225
High Efficiency
Small
600,000
650
286,000
4.5
23,200
600,000
650
286,000
0.0025
12.8
99.94
839,650
5,248,160
6,087,810
Large
1,020,000
650
535,000
4.5
41,000
1,020,000
650
535,000
0.0025
21.8
99.95
1,371,400
6,586,195
7,957,595
208
-------
REFERENCES
(1) Varga, J. Jr. and H. W. Lownie, Final Technological Report on A Systems
Analysis of the Integrated Iron and Steel Industry (Contract No. PH
22-68-65) Division of Process Control Engineering, NAPCA, DHEW, May
15, 1969.
(2) McGannon, Harold E., The Making, Shaping and Treating of Steel, 8th
Ed., U.S. Steel Corp., Pittsburgh, Pa. 1964.
(3) Wheeler, D. H., "Fume Control in L. D. Plants", Journal of the Air
Polution Control Association, Vol. 18, No. 2, Jan/1968 (98-101).
(4) Chipman, John, "Chemistry -in the Metallurgy of Iron and Steel",
(Thirty-first Annual Priestly Lectures), Pennsylvania State University,
University Park, Pennsylvania, April 1-5, 1957.
(5) Bashforth, G. R., The Manufacture of Iron and Steel, 2nd Ed.,
Arrowsmith, Ltd., Bristol, England, 1957.
(6) Haltgran, Ralph, Fundamentals of Physical Metallurgy, Prentice-Hall, New
York, 1952.
(7) Groen, R. G., "Scrap Metal Preheating in the Basic Oxygen Furnace",
American Gas Association Monthly. March, 1967, 28-31.
(8) Wheeler, D. H., "The Iron and Steel Industry" Proceedings at the Electro-
static Precipitator Symposium, Sponsored by APCO/EAA, Feb. 23-25,
1971.
(9) Parker, Charles M., "BQP Air Cleaning Experiences", Journal of the Air
Pollution Control Association, Vol. 16, No. 8, August, 1966, 446-448.
(10) Sargent
(11) Rowe, A. D., H. K. Jaworoski, and B. A. Bassett, "Waste Gas Cleaning
Systems for Large Capacity Oxygen Furnaces", Iron and Steel Engineer,
January, 1970, 74-78.
209
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210
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o
O
o
r
m
O
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5 COAL CLEANING
Coal as recovered from the mine contains waste materials which must be
removed before it is marketed. The coal also must be crushed and sorted into
standard sizes. The process of removing these wastes and crushing and sorting
the coal is called coal preparation or coal cleaning.
The growth and importance of coal cleaning is illustrated by the increase in.the
annual processing rate from 5 percent of the coal mined in 1927 to almost 64
percent in 1966. This increase has resulted from the need to produces higher
quality fuel, with higher heating values, containing less ash, from mines with
lower quality deposits. There is also increased emphasis on removal of waste
materials before the coal is burned so that they are not subsequently released
to the atmosphere as pollutants.141 Since 1966, the production of cleaned coal
has decreased somewhat.
A typical coal cleaning plant employs any one of, or combination of, methods
for removing waste materials. Table 79 lists the various methods which are in
common use, together with the tons cleaned and the percentage processed by
each. Approximately 93% of the coal cleaning is done by wet methods. Of the
available wet methods, the most popular are jigs, dense-medium processes and
concentration tables. These three account for approximately 88 percent of the
total coal cleaned.
Coal cleaning plants range in size from 100 to 1000 ton/hr with an average size
of about 500 ton/hr.
PROCESS DESCRIPTION
The principal purposes of cleaning plants are to crush the coal, classify it into
standard sizes and to remove the waste materials mined with the coal. Because
of the economies to be realized in reduced shipping costs for coal without
waste materials, most coal cleaning operations are located at the mine.
The flow diagram for a typical coal cleaning plant is shown in Figure61. Coal
recovered from the mine is first conveyed to a storage pile or silo. The coal is
then conveyed to a double screen where the very large and very small pieces are
separated from the rest of the coal. The very large pieces (the size of which
varies with each mine) are discarded as refuse. The very small pieces
(approximately 1/2 inch and smaller) are either conveyed to a clean coal pile or
sent to the cleaning circuit, again varying from mine to mine. That portion of
the coal passing through the large screen but not the smaller - the "middling"
— is then conveyed to the crusher where it is reduced to the desired size and
211
-------
TABLE 79
COAL CLEANING METHODS AND
CORRESPONDING PRODUCTION RATES
Cleaning Methods
Cleaning Methods
Wet Types
Jigs
Dense-medium process
Concentration tables
Froth Flotation
Classifiers
Launders
Sub Total
Dry Types
Pneumatic
Total
Coal Cleaned
(net tons)
156,789,000
97,301,000
45,427,000
7,438,000
4,775,000
4,691,000
316,421,000
24,205,000
340,626,000*
Percentage
Cleaned
46.0
28.6
13.3
2.2
1.4
1.4
92.9
7.1
100.0
'Represents 63.8 percent of the total net tons of coal produced in 1966.
212
-------
STACK
ro
FIGURE 61
FLOW DIAGRAM FOR
COAL CLEANING PLANT
INDUCED POLLUTION
DRAFT ABATEMENT
FAN EQUIPMENT
~*\
:
//I J
*—*s
////
////
MINE
MOUTH
STORAGE
SILO
FIRST
SCREENS
CRUSHER
WET
SECOND CLEANING THERMAL
SCREEN CIRCUIT DRYER
c HOT
-^GASES
PRIMARY
DUST
COLLECTOR
CLEAN COAL
PILE
-------
rescreened. The coal retained on the screen is conveyed to the cleaning circuit
while that passing through is conveyed to the clean coal pile.151
Separation Equipment
A typical wet cleaning circuit includes one or more of the following types of
separation equipment.
1. Jigs
2. Dense-Medium Process
3. Concentration Tables
Jigs separate materials of different specific gravities by the pulsation of a
stream of liquid flowing through a bed of the materials. The up and down or
"jigging" action of the liquid causes the heavier materials to work their way to
the bottom of the bed, thereby allowing the different materials to be drawn off
separately. The pulsing action is caused by alternately applying and exhausting
air of a pressure of approximately 2.5 Ib/sq. in. from the pulsion chamber.12)
Jigs can be used for washing unsized coal as coarse" as 7 inches. A typical
Jeffrey-Baum type coal jig will process 3 ton/hr/sq ft of active screen area when
cleaning coal 4 inches and less, with the capacity decreasing with a decrease in
the size of the raw feed stock. In 1966 about 157,000,000 tons of coal were
processed by jigs. This amounts to 46 percent of all the coal cleaned during
that year.'11
Jigs are simple to operate and can be constructed with a low initial cost. Power
and water consumption rates, however, are high with power requirements of
about 0.1 hp/sq ft of screen, and water requirements of about 1500 gal/ton of
material processed. Direct operating costs vary with the type of feed stock and
its size, the number of stages and the annual capacity of the plant. Operating
costs for a large plant will be in the range of 15 cents per ton.
The second most widely used separation method, the dense-medium process,
accounted for 97,000,000 tons or about 29 percent of the coal cleaned in
1966.'1> This method is used where there is an appreciable difference in the
specific gravities of the coal and the waste material.
The separation is accomplished by placing the mined product in a liquid
suspension of finely divided high gravity solids which forms the dense medium.
The most widely used solids are ferrosilicon and magnetite. Coal cleaning plants
use magnetite to form a dense medium with a specific gravity of approximately
2.20.
214
-------
A typical dense-medium plant operates in the following manner. The mined
material is fed to a vessel containing the dense medium. The lighter portion of
the mined product floats, while the heavier material sinks. The floaters, in this
case, the coal, overflow a weir and are transferred to a drain screen for rinsing
and de-watering. The heavy waste, which sinks, is removed by a conveyor and
similarly de-watered and rinsed before being discarded. The water drained from
both the floaters and the sinkers is sent to a storage tank where the magnetite is
recovered for reuse by magnetic separation.
Dense-medium plants are capable of processing up to 30 ton/hr of raw coal per
foot of vessel width when the feed material is +1/4 inch in size. While
separation vessels have been designed to handle materials up to 12 inch, the
usual size range is 3 to 6 inch. A typical plant processing 3x1/8 coal with 50
percent in the 1/4 to 1/8 inch size would have a feed rate of about 20
ton/hr.12'
The third most commonly used wet cleaning method is the concentration table,
which accounted for 45,000,000 tons or 13 percent of the coal processed in
1966.'11
The separation is accomplished by flowing the mined material across a riffled
plane surface inclined slightly from the horizontal. The plane is differentially
shaken in the direction of the long axis while washed with an even flow of
water at right angles to the direction of motion. As with the dense-medium
process, the separation is a function of the specific gravities, and to a lesser
extent of the sizes and shapes of the material.
The heavier materials are least affected by the wash water and collect in, and
move across, the riffles on the high side of the table. The lighter materials on
the other hand ride over the heavier materials and collect on the low side of the
table. Launders are located at the end of the low side to separate the large
pieces from the middlings, and the middlings from the fines. To improve the
quality of the separation some of the middlings are returned to the head of the
circuit for reprocessing. The amount of middlings recirculated may be as high
as 25 percent of the weight of the feed to the table.
In a coal cleaning plant using multiple-deck tables with a single operator, as
much as 1200 ton/hr can be processed with low power and maintenance cost.
The principal cost associated with a concentration table is that of the labor to
operate it.
Dryers
After the coal has been cleaned by one of the above methods it proceeds to the
215
-------
next step which is the thermal drying operation. It is during this operation that
flue gases are contacted with the coal and entrained particulate matter can be
discharged to the atmosphere as a pollutant.
The dryer is simply a contacting device in which hot flue gases and air are used
to heat the wet coal, evaporate much of the moisture, and transport the water
vapor out of the system. While simple in principal, the large weight of materials
handled continuously poses some interesting problems.
Several types of dryers have been used, of which the most popular is the
fluidized bed dryer. In fluidized bed dryers, the coal is suspended in a fluid
state above a perforated plate by a rising column of hot gases. The dried coal is
discharged from the dryer by an overflow weir.
The second most widely used dryer in coal processing plants is the direct-fired
"flash dryer". Here hot gases generated by burning fuel in a furnace are used to
transport the coal up a riser. The time of transport is very short, but highly
turbulent contact of the gases and coal particles brings about good drying with
a minimum of coal volume in the drying system.
Usually the flue gas is used on a once-thru basis; that is, the flue gas passes
through the dryer once, becomes saturated with water (or nearly so) and is
discharged into the atmosphere. In theory the volume of gas could be reduced
somewhat by recirculating some of the cooled gas back to the furnace.
However, this is not done in practical drying applications.
Gas volumes from fluidized bed dryers will range from 50,000 to 250,000
ACFM as a function of the rated throughput. The exit temperatures will
average around 150° F with 5 to 10 percent moisture. The specific gravity of
the gases exiting the dryer will range between 0.90 and 0.95 when related to
air.
A typical particle size distribution'3) for the feed to a fluidized bed dryer is
shown in Figure62. The "minus 200 mesh" material is carried over to the
primary collector while the remainder is recovered as product.
The hot gases leaving the thermal dryer are sent to a cyclone-type primary
collector for the purpose of product recovery and to clean the stack gases
before they are discharged to the atmosphere. Typical particle size
distributions'31 for material entering and exiting primary collectors from flash
dryers and fluidized bed dryers are shown in Figure 63. A typical collector uses
a large number of 9 to 12 inch diameter tubes in a common housing.
Most coal cleaning plants are adding higher efficiency secondary collectors in
216
-------
s
5
.01 .05.1 .2 .5 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 99.5 99.9 99.99
WT.% LESS THAN INDICATED SIZE
FIGURE 62
PARTICLE SIZE DISTRIBUTION OF
FEED TO FLUIDIZED BED DRYER
217
-------
o
cc
o
UJ
N
53
iu
_i
o
.01 .05 .1 .2 .5 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 99.5 99.9 99.99
WT.% LESS THAN INDICATED SIZE
FIGURE 63
PARTICLE SIZE DISTRIBUTION
BEFORE AND AFTER CYCLONE
218
-------
series with the primary collectors. The reasons for this are twofold; the
secondary collector can improve product recovery and reduces air pollution.
The type of secondary collector used is most often a wet scrubber.
The final piece of equipment in the typical coal cleaning plant is the induced
draft fan, which provides for the movement of the exhaust gas from the
thermal dryer through the primary and secondary collectors and finally
through the stack to the atmosphere.
NATURE OF THE GASEOUS DISCHARGE
The gaseous discharge from a typical coal cleaning plant originates from the
thermal dryers161 and consists mainly of products of combustion and water
vapor.
Because thermal dryers are used in coal mining operations, it is natural that
coal is the fuel used to produce the heat required for operation. The gaseous
discharge from either flash dryers or fluidized bed dryers utilizing coal consists
of the products of combustion of the coal plus the moisture removed from the
coal passing through the dryer. The composition of the flue gas produced by
burning coal with sufficient excess air to reduce the temperature of the furnace
gases to 1000° F is given in Table 80.
This gas is generated in sufficient quantity that it can heat the coal to an exit
temperature of 150 to 190° F and supply the latent and sensible heat
requirements to drive off most of the moisture in the coal being dried. A
typical heat balance of a dryer with 17 wt% moisture prior to drying and an
exit temperature of 190° F is shown in Table 81.
From Table 81 it can be seen that 230.8 Btu are required to dry a pound of
coal. Now, the flue gas loses about 800° F x 0.24 Btu/lb-°F or 192 Btu/lb of
gas as it cools off in the dryer. The gas rate required is therefore
p
= 1.20 Ib flue gas/lb coal dried
For a 500 Ton/hr unit:
500 x 2000 x 1.20 = 1,200,000 Ib/hr
of flue gas are liberated, along with 150,000 Ib/hr water vapor. The gaseous
discharge is given in Table 82 for a hypothetical 500 Ton/hr dryer.
219
-------
TABLE 80
THEORETICAL COMBUSTION PRODUCTS
Ultimate Analysis
of Coal
Component
C
H
0
N
S
Ash
Wt%
81.0
2.4
5.9
0.0
1.1
9.6
Combustion Products
per Ib Coal
Component
C02
H20
°2
N2
S02
Theoretical Combustion
Air, SCF Products,SCF
25.7
4.6
28.2 -28.2
106.3
0.1
Excess
Air, SCF
-
-
121.4
456.9
—
Total
SCF
25.7
4.6
121.4
563.2
0.1
100.0
134.5
2.2
578.3 715.0
220
-------
TABLE 81
CALCULATED HEAT REQUIREMENTS FOR COAL DRYING
(Basis one pound dry weight of product)
Coal Feed
Ib
Temp.,°F
1.28
Btu/lb
Btu/lb dry coal
Fines
Coal
Water
0.06
1.00
0.22
60
60
60
0
0
0
0
0
0
Product
Ib
Temp,,°F Btu/lb Btu/lb dry coal
.Fines
Water Vapor
Dry Coal
Water
0.06
0.17
1.00
0.05
190
190
170
170
39.0
1114.0
33.0
110.0
2.3
190.0
33.0
5.5
1.28
230.8
221
-------
TABLE 82
GASEOUS DISCHARGE FROM A HYPOTHETICAL 500 TON/HR DRYER
CO-
SO-
H00
Flue
Gas
SCFM
186000
49300
12400
50
2250
250000
Water
from Coal
SCFM
60000
60000
Total
Discharge
SCFM
186000
49300
12400
50
62250
310000
Total
Discharge
ACFM@ 190°F
228000
60500
15200
60
76360
380120
222
-------
From Table 82 it is apparent that the gas exhausted from the dryer contains
enough water vapor to bring about an increase in gas flow by a factor of about
25%.
The composition of the discharge gas will vary somewhat with the analysis of
the fuel being fired. In some instances oil or gas may be substituted for coal as
the dryer fuel. This may be true where high sulfur coal is being processed and
strict regulations exist with respect to SC>2 emission. The quantity of flue gas
will vary little with the fuel type, and will be nearly proportional to the rate at
which water must be evaporated. This is, in turn, proportional to the product
of the coal feed rate and the moisture content.
POLLUTION CONTROL CONSIDERATIONS
As indicated in Figure 63, the particles in the dryer feed which are less than
200 mesh are assumed to be carried over to the primary collector. This
carryover represents grain loadings in the range of 100 to 300 gr/ACF which is
about 28 percent by weight of the total feed to the dryer.
When an average loading of 200 gr/ACF is applied to dryers having gas flows in
the 50000 to 250000 ACFM range, emissions of 1400 to 7000 Ib/min are
possible. It is obvious that some form of collection equipment must be
provided to recover this product and to reduce atmospheric emissions.
Cyclones are the most commonly installed equipment. However, alone they are
not capable of the high collection efficiency required; their selection and design
is normally confined to providing the best product recovery consistent with the
lowest maintenance and operating costs. Typical emissions from a cyclone are
about 10 gr/ACF which corresponds to an atmospheric discharge of 70 to 350
Ib/min. Grain loadings may vary greatly from one installation to another.
Current national, state and local air pollution regulations require that further
gas cleaning be provided before the cyclone exhaust gases can be discharged to
the atmosphere.
The gases from the cyclones following the thermal drying step constitute the
principle source of air pollutants. The high dust loading of these gases (as high
as 10 gr/ACF) results in a dense visible plume when discharged to the
atmosphere. Coal dust is visible to the eye in concentrations exceeding 0.05
gr/ACF for stacks of moderate size.
In addition to the obvious need to clean the gases to limit atmospheric
223
-------
pollution, it is also desirable to process the cyclone gases for product
recovery. A collector removing 10 gr/ACF of coal dust from 250,000 ACFM
discharge from a cyclone, will recover almost 11 ton of product per hour.
This represents a recovery of 2 percent of the total feed.
Because the emission problem is one of providing a clean stack and product
recovery, the applicable control system is wet scrubbing. Filters are seldom
used because of the high humidity of the gas stream, and electrostatic
precipitators are not ordinarily used.
Wet Scrubbing
The most widely used control system is wet scrubbing. Several types of
scrubber designs have been applied, including the impingement tray, Venturi,
and impingement baffle scrubber. Figure 64 illustrates the configuration of
each as it is applied in coal cleaning.'31
The impingement tray scrubber has been used for many years. However, this
type of scrubber is subject to plugging and has a relatively low collection
efficiency. It is not ordinarily good enough to meet either set of regulations
covered in this study.
The second type of scrubber which has found use in this service is the Venturi.
The Venturi scrubber type is virtually free from plugging problems, even when
a high solids content is built up in the scrubbing liquid. Another advantage of
this type of scrubber is that the scrubbing liquid can be recirculated, thereby
keeping water usage to a minimum. The Venturi scrubber provides the highest
collection efficiency when operated at high pressure drop.
Disadvantages of the Venturi scrubber include the high operating cost, when
high pressure drop across the throat section is required.
The impingement baffle scrubber combines a relatively high collection
efficiency with lower pressure drop requirements than the Venturi. Dust
emission levels of 0.10 gr/ACF or less have been reported for systems operating
with less than 15 inches w.g.
224
-------
FIGURE 64
BASIC TYPES OF WET SCRUBBERS
USED FOR COAL CLEANING
OUTLET
GAS
OUTLET
GAS
OUTLET
GAS
INLET
GAS
WATER
SCRUBBING
WATER
SCRUBBING
WATER
SCRUBBING
WATER
IMPINGEMENT
TRAY
VENTURI
IMPINGEMENT
BAFFLE
225
-------
Some of the advantages of scrubbing systems include their resistance to fire and
explosion and adaptability to absorption of SC>2 from the combustion gases.
Bag Filters
Bag filters have an inherently high collection efficiency, provide for dry
product recovery, and they are relatively simple in their construction and
operation.
Disadvantages of bag filters include susceptibility to fire and explosion, and
high bag replacement cost. Gas inlet temperature to the filter must be kept
above the dew point to prevent the formation of a mud which will blind the
filter. This is particularly difficult on dryer effluents, where the dew point of
the exit gas approaches the gas temperature. Bag houses on coal cleaning plant
dryers would require extraordinary precautions to prevent condensation, such
as steam traced hoppers, heavy insulation, and systems for diverting gases
around the bag house if the temperature drops below a predetermined limit.
For these reasons, they are seldom used.
SPECULATIONS AND COSTS
Specifications were prepared for wet scrubbing equipment to meet two levels
of efficiency for two equipment sizes. Because the rate of material handled in
coal cleaning processes is very high, the process weight specification provides a
more stringent requirement for emission control than does the "high
efficiency" case. These specifications are shown in Tables 83 and 84.
The large size of the process equipment poses another problem in the
specification of the scrubbing equipment. That is, the largest plants process
more coal than can be handled in a single fluidized-bed drier. Although a single
scrubber system was specified for the largest plant, the quotations received
were based on two complete scrubbing units. This is likely to be the case in all
plants designed for more than about 500 ton/day, and for smaller plants if
more than one dryer train is included for flexibility.
All of the scrubbers quoted in response to these specifications were Venturis.
These have generally supplanted impingement-type scrubbers which were
widely used in the past as emission limitations became more stringent.
226
-------
The cost data obtained in response to the specifications are presented in Tables
85 and 86. Plots of first cost versus plant size are given in- Figures 65 and 67
and operating cost versus plant size is plotted in Figures 66 and 68.
227
-------
TABLE 83
WET SCRUBBER PROCESS DESCRIPTION
FOR COAL CLEANING SPECIFICATIONS
The air pollution abatement system is to serve a new coal cleaning plant in which one or two
fluid bed thermal dryers will be operated.
The system shall be quoted complete, including all of the following items as detailed in our
drawings. *
1. Interconnecting ductwork
2. Wet scrubber(s) complete with mist eliminator(s) and stack
3. Fan(s)
The system shall be quoted on each of the following bases.
1. Scrubber(s) only
2. Complete equipment, consisting of
a. Scrubberfs)
b. Pump(s)
c. fan is)
d. Dampers
3. Complete turnkey system
Scrubbers shall be designed for sufficient pressure drop to meet the performance specified.
The liquid-gas ratio shall be specified by the vendor, but in no event shall the ratio be lower
than 5 GPM per 1000 ACFM (saturated). Vendor shall specify the actual pressure drop at
which the scrubbers will operate.
Fans shall be capable of overcoming the system pressure drop at the design flow rate while
operating at no more than 90% of the maximum recommended speed. Motors shall be
capable of driving fans at maximum recommended speed and the corresponding pressure
differential at 20% over design flow rate.
Scrubbing water supply and disposal. Scrubbing water shall be taken from the cleaning
plants refuse thickener overflow. The spent scrubbing water will be returned to the refuse
thickener. During normal scrubbing operations the expected solids content of the slurry will
be less than 5% by weight leaving the scrubber. The vendor shall include in his proposal the
cost of the piping, valves, fittings, hanger and support required to connect the scrubbing
system with the plant refuse thickener.
*NOTE: It would be reasonable to assume that the engineering company designing the
entire plant would specify the abatement equipment as a part of their work.
228
-------
TABLE 84
WET SCRUBBER OPERATING CONDITIONS
FOR COAL CLEANING SPECIFICATION
Two efficiency levels are to be quoted for each of the two sizes.
Plant Capacity, ton/hr
Dried coal product, ton/hr
Process weight, ton/hr*
Gas to Scrubber
Flow, ACFM
Temp, °F
Pressure, psia
Pressure, in w.c.
Composition, mol %
co
Molecular Weight
Solids loading, Ib/hr
Solids loading, gr/ACF
Solids loading, gr/DSCF
Gas from Scrubber
Flow, ACFM
Temp, °F
Pressure, psia
Pressure, in w.c.
Composition, mol %
co2
°2
»
Molecular Weight
Small
600
250
305
190,000
190
14.16
-15.0*'
4.00
15.90
60.00
20.10
100.00
27.28
16,300
10
15.3
180,000
143
13.62
-40.0
3.91
15.58
58.75
21.76
100.00
27.07
Large
1800
750
915
570,000
190
14.16
-15.0**
4.00
15.90
60.00
20.10
100.00
27.28
48,900
10
15.3
540,000
143
13.62
-40.0
3.91
15.58
58.75
21.76
100.00
27.07
'Process weight is greater than dryer capacity because only a fraction of the cleaned coal is
dried.
**The value specified includes the furnace draft, thermal dryer, and the primary collector
pressure drop.
229
-------
Outlet loading, Ib/hr
Outlet loading, gr/ACF
Efficiency, wt. %
Case 1 — LA-Process Weight
40
0.026
99.75
40
0.009
99.95
Outlet loading, Ib/hr
Outlet loading, gr/ACF
Efficiency, wt. %
Case 2 - "High Efficiency"*
77
0.05
99.53
139
0.03
99.72
*This case is less restrictive than the "Medium Efficiency" or Process Weight basis.
230
-------
231
-------
TABLE 85
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR COAL CLEANING PLANTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s) *
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other
(4) Total Cost
LA Process Wt.
Small
190,000
190
116,980
20.1
10
16,300
172,720
144
116,980
21.5
0.027
114,100
55,345
4,630
1,800
19,700
22,950
45,000
-
38,200
22,050
3,725
1,890
6 '650
2,100
1,850
16,750
356,740
Large
570,000
190
350,950
20.1
10
48,900
518,150
144
350,950
21.5
0.009
340,425
190,405
12,840
4,250
21,950
46,500
110,500
_
97,250
58,000
7,900
3,350
12,150
3,550
2,250
42,700
954,020
High Efficiency
Small
190,000
190
116,980
20.1
10
16,300
172,720
144
116,980
21.5
0.05
112,600
50,078
4,338
1,700
19,700
22,450
46,300
_
37,600
23,550
3,750
1,890
6,650
2,100
1,850
16,600
351,156
Large
570,000
190
350,950
20.1
10
48,900
518,150
144
350,950
21.5
0.03
337,425
144,205
12,040
3,935
21,950
42,350
113,725
_
82,800
58,000
7,900
3,350
12,150
3,550
2,250
40,050
885,680
Data based upon two bids.
* Fan cost adjusted to attribute 37%% to process, 62%% to abatement.
232
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TABLE 86
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR COAL CLEANING PLANTS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power *
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2^500
$6/hr
$flll/kw-hr
S.25/M gal
LA Process Wt.
Small
750
1,426
832
27,569
4,244
31813
34,821
35,674
70,495
Large
750
3,604
2,870
95,425
12,731
108156
115,380
95,402
210,782
High Efficiency
Small
750
1,437
794
26,297
4,244
30,541
33,522
35,116
68,638
Large
750
3,408
2,258
83,566
12,731
96,297
102,713
88,568
191,281
ro
•oo
CO
Data based upon two bids.
* Power cost adjusted to attribute 37%% to process, 62%% to abatement.
-------
FIGURE 65
CAPITAL COSTS FOR WET SCRUBBERS
FOR COAL CLEANING PLANTS
(LA - PROCESS WEIGHT)
900
Cfl
CC
o
O
0.
O
C/5
O
z
I
o
I
o
o
200
100
400 600 800 1000
PLANT CAPACITY, TON/HR
2000
3000
234
-------
• FIGURE 66
ANNUAL COSTS FOR WET SCRUBBERS
FOR COAL CLEANING PLANTS
(LA-PROCESS WEIGHT)
300
N>
o
O
V)
cc
<
-J
o
Q
u.
O
1
I
O
H
400
600 800 1000
PLANT CAPACITY, TON/HR
2000
3000
235
-------
FIGURE 67
CAPITAL COSTS FOR WET SCRUBBERS FOR
COAL CLEANING PLANTS
(HIGH EFFICIENCY)
900
700
V)
(C
500
400
CO
a
CO
O
CO
O
a
300
1 I I I
TURNKEY SYSTEM
COLLECTOR PLUS
AUXILIARIES
200
100
400 600 800 1000
PLANT CAPACITY, TON/HR
2000
3000
236
-------
FIGURE 68
300
200
CO
O
0
|
O
I
O
O
100
90
80
70
60
50
40
ANNUAL COSTS FOR WET SCRUBBERS
FOR COAL CLEANING PLANTS
(HIGH EFFICIENCY)
TOTAL COST
'(OPERATING COST PLUS
CAPITAL CHARGES)
400 600 800 1000
PLANT CAPACITY, TON/HR
2000
3000
237
-------
REFERENCES
1. Frankel, R. J., "Economic Impact of Air and Water Pollution Control on
Coal Preparation", Mining Congress Journal, Oct. 1968, p. 56-63.
2. Perry, J. H., Perry's Chemical Engineers' Handbook, Fourth Edition,
McGraw-Hill, New York, 1963.
3. Walling, J. C., "Air Pollution Control Systems for Thermal Dryers", Coal
Age, Sept. 1969, p. 74-9.
4. Stern, A. C., Air Pollution, Volume III, Sources of Air Pollution and Their
Control, Second Edition, Academic Press, New York, 1968.
5. Jones, D. W., "Dust Collection at Moss No. 3", Mining Congress Journal,
July 1969, p. 53-6.
6, Porterfield, C. W., "Dust Collection at Itmann Preparation Plant", Mining
Congress Journal, Nov. 1970, p. 67-70.
7. "Preparation, Quality Control, Environmental Protection", Coal Age, Oct.
1970, p. 137-46.
8. Scollon, T. R., "Impact of Air Pollution Regulations on Coal", Mining
Engineering, Aug. 1970, p. 67-9.
238
-------
00
33
O
0)
0.
m
-------
6. BRICK AND TILE KILNS
Brick manufacture dates back thousands of years. Bricks were formed by hand
or in crude molds and baked in the sun. The art of baking or burning brick to
produce a hard, durable product was developed prior to 500 B.C.11' The two
basic operations in the manufacture of brick or tile, the forming of the ware,
and firing, persist to this day.
The basic raw material is, as it was in the earliest times, naturally occuring clay.
The properties of clay products depend upon the shape into which they are
formed, and to a very large extent upon the nature of the clay from which they
are produced.
Clays comprise natural earth materials which form plastic self-adherent masses
when wet, and after drying form hard, brittle structures. All clays are the result
of decomposition of rock, and consist of very fine, water-insoluble particles
which have been carried in suspension in ground water and deposited in
geologic basins according to their specific gravity and degree of fineness.'1'
Chemically, the clays are hydrates of alumino-silicates with various impurities
such as powdered feldspar, quartz, sand, limestone, carbonaceous materials
such as coal, and pyrites.
While the crushing and grinding of clay materials in preparation for forming the
ware may produce significant particulate emissions, the burning of brick and
clay products, with which this section is concerned, produces air pollution
emission only when the raw material contains impurities which lead to
generation of contaminants. Such impurities may produce fluoride emissions
when substances such as fluorite and fluoapetite are present, sulfur oxides
when iron pyrites or other sulfur bearing minerals are present, and
carbonaceous soot when fossilized organic matter such as coal is present as an
impurity. Because of the importance of these trace materials in the
consideration of air pollution problems in the brick and tile industry, a great
deal of stress will be laid upon the chemical composition of the clay used in
any given location.
Throughout most of the narrative, reference will be made to the manufacture
of brick. It should be understood throughout, that the processing steps are
substantially identical for the manufacture of structural clay products generally
grouped under the name tile. Some of the products included in this category
are drainage tile, floor tile, roof tile, and multiple duct tile used as underground
utility conduit.
239
-------
FORMING BRICK AND TILE PRODUCTS
Brick and tile are manufactured by two basic forming processes. These are the
dry press method and the stiff mud method. These are not significantly
different, however, from the standpoint of air pollution emissions and the
description of the forming processes serves only to provide some background
for the discussion of kiln operation.
In the dry press method, the clay is usually ground in a relatively dry state and
taken directly to the brick forming machinery without the addition of any
water. The brick making machine, generally called a dry press machine, exerts
an enormous amount of pressure on the clay to form a dense product. The
ware produced by a dry press machine can be taken directly to the kiln for
firing without any intermediate drying step. This method is frequently used for
clays which tend to crack on drying.
In the stiff mud process the clay is ground very thoroughly and mixed in apug
mill. It is then conveyed to an auger machine, or stiff mud machine. The stiff
mud machine consists of a section in which further mixing and tempering of
the clay are carried out, followed by an auger which compresses the plastic clay
through a die. The column of clay extruded through the die is then passed
through a ware cutter which cuts the column to the desired brick length. The
standard size for common brick is 8" x 3-3/4" x 2-1/4". The cross section of
the clay column is not quite rectangular and the top is slightly wider than the
bottom. This makes it slightly easier for masons to handle the bricks when
setting them up. The stiff mud machine can be used for extruding any shape of
clay product. This method is ordinarily used for the production of drain tile,
roof tile, etc.
In either case, the final step in the processing of the brick is heating of the ware
in a kiln. This is alternately known as burning or firing the ware. In the case of
dry press method manufacture, no drying step is required. When the stiff mud
or stiff plastic method is used for forming, the bricks are sometimes dried prior
to burning.
Several changes occur during the firing of the ware:11'
1. The "free" or chemically uncombined water is driven off.
2. Decomposition of the clay, with liberation of the combined water, or
water of hydration, takes place.
3. Combustion and removal of combustible matter occurs.
240
-------
4. Decomposition of impurities (see Table87<2') is completed.
5. Partial combination of some of the impurities with the silica and
alumina from the clay occurs, and a molten glassy material is formed.
6. Upon cooling, this glassy material bonds the solid particles together,
forming a tough hard product.
The temperature of the ware should be raised slowly to allow the water and
products of combustion to escape without damaging the structure of the ware.
Also, the highest temperature reached and the time the ware is held at this
temperature determine the amount of glassy material formed. Table 88 gives
firing temperatures for various materials.
Practically all modern brick and tile plants use a tunnel kiln to fire their
ware.'2' The configuration of a typical tunnel kiln is shown in Figure69.The
ware is placed on cars and charged to the left end of the kiln and moves
continuously to the right. As it moves it is gradually heated, reaching a
maximum temperature in the hot zone between the furnaces. The charge is
then cooled as it passes out of the kiln. Air is passed through the kiln
countercurrent to the direction of movement of the ware. Cold air is forced in
the right end of the kiln and passes through the charge, cooling it by
exchanging heat. Some air is withdrawn from this section for use as the primary
air for combustion in the burners. The remaining air continues to the left into
the combustion zone, mixes with the combustion gases, and then passes
through the incoming charge, losing heat to it. The temperature of the flue
gases ranges from 150 to 300° C, depending on the length of the preheating
zone and the amount of air recirculated. Air is drawn out the left end of the
kiln with a suction fan. Air locks are used at both ends so that the flow
conditions in the kiln will not be disturbed by the entrance or exit of cars.
The output of tunnel kilns varies from 100 to 250 ton/day with an air flow of
15,000 to 37,000 ACFM. The exact operating parameters of a kiln are
determined by the raw material used and the nature of the product desired.
RAW MATERIAL
Clays are classified according to the use for which they are best suited, and
according to their chemical properties. Clays may be alternately described as
brick clay, fire clay, potters clay, etc. or categorized as to marls, loams, shales,
fire clays and boulder clays.
241
-------
TABLE 87
BREAKDOWN TEMPERATURES OF CLAY IMPURITIES
FeS2 + 02
4FeS + 702 ->• 2Fe203 + 4S02
Fe2(S04)3 -> Fe203 + 3S03
CaC03 -> CaO + C02
MgC03 ^MgO + C02
FeC03 + 302 ->• 2Fe203 + 4CO2
CaS04 -»• CaO + S03
Temperature
°C
350-450
500-800
560-775
350
250-920
600-1050
400-900
800
1250-1300
Temperature
°F
660-840
930-1470
1040-1430
660
480-1690
1110-1920
750-1650
1470
2280-2370
242
-------
TABLE 88
TEMPERATURES ATTAINED IN BURNING
Clays rich in lime and iron
Gault clays
Red-burning clays and shales
Clinkers, pavers, vitrified bricks
Stoneware; salt glaze
Majolica glazes
Glazed bricks (hard fire)
Fireclays
Silica bricks; High-alumina bricks, magnesia
bricks and chromite bricks
Temperature,
°C
790-1080
855-940
900-1140
1100-1300
1180-1300
900-1000
1200-1280
1230-1530
1460-1670
243
-------
EXHAUST
FAN
/£. > > Y//////////////7///7777A
FURNACES
BLOWER
CHARGING
END
PREHEATING
ZONE
FURNACES
COOLING
ZONE
DISCHARGE
END
FIGURE 69
PLAN SECTION OF TUNNEL KILN
-------
Marls contain a substantial amount of lime in the form of chalk or limestone.
Loams contain a good deal of sand which makes them easy to work. Shales are
very hard materials formed by geologic processes into nearly rock-like masses.
Fire clays contain a high proportion of minerals with very high decomposition
temperatures, such as magnesia, and are used for furnace linings, etc. Boulder
clays are produced by glacial action and generally contain round stones or
boulders. Clays with a low percentage of constituents such as sand or limestone
and a high fraction of plastic alumino-silicates are termed fat c/a/s.They are
usually improved by the addition of other materials such as sand or limestone.
Table 89 contains a chemical formulation of some of the alumino-silicate
materials which are suitable for brick making.
It can be seen from Table89that the clay minerals themselves are not a source
of sulfur dioxide or fluoride emission with the possible exception of hectorite,
which contains fluorine. It is impurities in the clay (see Table 90 ) that are
responsible. In addition to these naturally occurring impurities, materials such
as sand, ground fired bricks, coal, coke, ashes, sawdust, and water are added to
clay to impart useful properties to it.11'
NATURE OF THE GASEOUS DISCHARGE
Tunnel kilns are basically furnaces in which the water of hydration of the clay
minerals is removed by firing. The kiln operates continuously, and has a
relatively steady flow of gas and constant heat input. The effluent gas leaving
the kiln consists of air from which some of the oxygen has been removed by
combustion of fuel along with the carbon dioxide, water vapor, and sulfur
dioxide or other contaminants produced by combustion of the fuel. In
addition, the water driven off of the brick is contained in the effluent gas.
Tunnel kilns can be fired with any of the commonly available fuels such as
natural gas, fuel oil, or coal. The composition of the gas leaving the kiln
depends but little on the type of fuel used in that the kiln operates at a very
high ratio of total air to theoretical combustion air and the composition is
altered minimally by the combustion of the fuel. In order to illustrate this,
Table91 lists the products of combustion calculated for a 100 ton/day kiln
using clean natural gas and high sulfur coal as fuels. For most purposes, the
tunnel kiln effluent can be presumed to consist of air plus'water vapor.
NATURE OF THE AIR .CONTAMINANTS
Due to the diverse nature of the raw material and its effect on the emission
from the kiln, three types of operation will be discussed.
1. Where the clay contains no sulfur or fluorine-containing material
245
-------
Kaolinite Group
Kaolinite
AI2(Si205) (OH)4
TABLE 89
CHEMICAL FORMULATION OF BRICKMAKIIMG CLAYS
Montmorillonite Group Micaceous Group
Pyrophyllite* Muscovite*
AI2Si4010(OH)2
AI4K2(Si6AI2)020(OH)4
Aluminous Group
Gibbsite*
Al (OH)3
Dickite
AI2(Si205) (OH)4
Nacrite
AI2(Si205) (OH)4
Anauxite
AI2.n(Si2+n05) (OH)4
Endellite
AI2(Si205) (OH)42H20
Halloyste
AI2(Si205) (OH)4
Allophane, amorphous
Montmorillonite
Si4°10(OH)2
Nat
a0.33
Beidellite
AI2.17°102
Na
'0.33
Nontronite
(Fe200)AI033Si362)010(OH)2
Na0.33
Saponite
M93(AI033Si362)010(OH)2
Na
'0.33
Hectorite
(Mg267Li033)Si4010(F,OH)2
Na0.33
Sauconite
Zn3(AI0.33Si3.67J°10(OH)2
Bravaisite
AI4Kx(Si3.xAlx)020(OH)4
Brommallite
AI4Nax(Si8.xAlx)020(OH)4
Attapulgite
(Mg5Si8)020(OH)22H20
Ordovician bentonites
(Most of the minerals in this
group are not very specific.)
Diaspore*
Hal02
Boehmite
HAlOo
Na
'0.33
*These minerals are not usually considered among the clay minerals, but when finely ground behave like clays in ceramic processes.
-------
TABLE 90
SOME NATURALLY OCCURRING IMPURITIES
Quartz
Feldspars (orthoclase, plagioclase)
Micas (muscovite and biotite)
Iron minerals (hematite, magnetite, limonite, pyrites, siderite)
Titanium minerals (rutile, anatase)
Limestone (calcite, dolomite)
Magnesite
Gypsum
Garnet
Tourmaline
Fluorspar
Organic matter
247
-------
TABLE 91
CALCULATED COMPOSITION OF COMBUSTION PRODUCTS
FROM 100 TON/DAY TUNNEL KILN
Total
Gas Fired
9000
*HF derived from clay impurities
100.0
Coal Fired
02
N2 + A
C02
H20
S02 + HF*
SCFM
1490
6620
135
745
10*
Mol %
16.5
73.6
1.5
8.3
0.1*
SCFM
1400
6660
260
660
20
Mol %
15.6
74.0
2.9
7.3
0.2
9000
100.0
248
-------
2. Where the raw material does contain sulfur and fluorine
3. Where the clay contains organic matter such as lignite or sawdust.
In the first case, the contaminants are derived only from the fuel used. Where
natural gas is used, there should be no problems. High sulfur fuel oil or coal will
produce both SC>2 and flyash emissions. There is a possibility of CO emissions
from passing the hot gases over the incoming bricks, but the concentration
should be negligible.
In the second case, the fuel will produce contaminants as it does in the first
case. Fluorides and additional SC>2 will be emitted from the impurities in the
clay. One common fluorine containing impurity is fluorite or fluorspar, CaF2,
which can react as follows:<3)
1. CaF2 + 3/2 Si02 = CaSi03 + 1/2 SiF4
2. CaF2 +1/2CaSi03 = 3/2CaO +1/2SiF4
3. CaF2 + H20 = CaO + 2HF
4. CaF2 + H20 + Si02 = CaSi03 + H F
In addition, silicon tetrafluoride can react with water vapor as follows:131
5. SiF4 + 2H20 = Si02 + 4HF
The equilibrium constants for these reactions at 1200°C are, respectively:
1. 0.13
2. 1.6X10'6
3. 2.0 X10'4
4. 0.36
5. 16.4
It can be seen from the above that essentially all SiF4 formed in the presence
of the water vapor from the combined and free water in the clay should be
hydrolyzed to HF.(3) Therefore, the fluorine is emitted in the form of HF
rather than SiF4.
249
-------
With a fuel containing 15% ash and 2% sulfur, the flue gas of a kiln using 150
Ibs of fuel per ton of ware fired and 600% excess air141 will contain about 0.74
gr/ACF flyash and 125 ppm S02.
If the raw material contains 0.1% sulfur and 300 to 500 ppm fluorine which is
30 to 90% volatilized, the flue gas will contain about 290 ppm SO2 and from
25 to 125 ppm HF. The HF probably hydrolizes to form hydrofluoric acid mist
at the flue gas condition.
The third case, involves the generation of air pollutants when organic matter
such as sawdust or powdered coal is added to the clay with the objective of
burning it out in the kiln and leaving a porous, low density brick. Such bricks
have improved insulating qualities as well as being light in weight. In this case,
and also when there is a high percentage of naturally occurring organic material
such as coal in the clay, there may be a partial volitilization of the organic
matter in the kiln followed by condensation and partial oxidation. One result
of this sequence is the production of a black organic smoke consisting of very
tiny carbon particles. Unlike the sulfur oxides or hydrofluoric acid, the
carbonaceous smoke may be decomposed to some extent in the furnace.
However, there is likely to be sufficient emission to cause violation of visible
smoke ordinances in circumstances where a substantial amount of organic
matter is included in the clay. For example, if a clay is blended with sawdust to
form a 1% organic matter mixture, the total amount of carbonaceous material
present in the clay would be sufficient to produce a grain loading of 0.85
gr/ACF at the kiln discharge. However, only a fraction of the total
carbonaceous matter is likely to be vaporized and survive as black paniculate
matter.
ABATEMENT EQUIPMENT
It is apparent that air pollution abatement equipment must be tailored to the
specific contaminants generated from impurities in the clay or in the fuel.
These may be divided into:
Gaseous Contaminants Particulates
S02 flyash
HF smoke
The gaseous contaminants can be removed by either absorption in a solvent or
adsorption on a solid material. Of the two, absorption using water as the
scrubbing medium is the method accepted in practice. Wet scrubbers are
suitable for removal of both gaseous impurities.
250
-------
Gaseous absorption is carried out in a variety of scrubbing devices, most of
which involve counter-current contacting of the gas and liquid. Where gases are
absorbed into liquid streams free of solids, fixed beds of packing material are
most frequently used. The presence of solids in either the liquid or gas phases
tends to cause plugging problems and requires the use of non-plugging
scrubbers. These may be co-current Venturi scrubbers, cross-flow packed
scrubbers, or a variety of proprietary devices utilizing moving packings or
self-cleaning impingement surfaces.
Where collection of particulate matter and absorption are required, Venturi
scrubbers, mobile packing devices and self-cleaning scrubbers are necessary.
This case was chosen for the specification of a hypothetical kiln in which
sulfur-bearing coal is burned and both S02 and HF are generated by
decomposition of the clay impurities.
HF is readily absorbed in water until the pH becomes quite low. However,
fluoride-containing effluent water cannot ordinarily be discharged into natural
bodies of water, so it is necessary to add some reagent which will precipitate
the fluoride as a solid. Typically lime or limestone is used for this purpose and
insoluble CaF2 is produced. This material is most frequently deposited in a
pond in which the scrubber effluent is impounded and from which water is
recycled.
Where SC>2 is present in the gas, it may be removed by absorption, but the pH
requirement is higher than for HF absorption. For this reason, addition of lime
to the scrubber system rather than to the pond may be chosen for a system
specification.
The removal of flyash can be accomplished by wet scrubbing, electrostatic
precipitation or fabric filtration. However, the flyash problem is relatively
limited in scope because of the predominance of gas fired kilns and because of
the low ratio of coal to total ventilating air. The flyash collection has been
limited, for purposes of this report, to wet scrubbing with the concurrent
removal of HF and S02- Special circumstances at a given plant might indicate
the use of an electrostatic precipitator or fabric collector for flyash collection
where no gaseous contaminants are involved.
"Smoke" produced by volatilization of organic material present in the clay or
added to modify the properties of the ware presents a somewhat different
problem. Here the conventional particulate collection devices such as fabric
collectors and precipitators may operate satisfactorily or may be subject to a
variety of operating problems because of the nature of the particles. These can
251
-------
vary from droplets of liquid oil to dry, solid carbon particles. Where there is a
possibility of caking or of wetting the collecting elements, both filters and
precipitators present special design problems. In particular, fabric collectors are
prone to "blinding" of the cloth, which restricts the gas volume sharply. This
would interfere with or prevent the normal operation of the kiln. Precipitators
have difficulty in handling solids with a caking tendency, and are also subject
to fire hazards when operating with combustible particulate in oxygen-rich gas
streams.
Scrubbers have difficulty collecting particulate "smokes" which are formed by
volatilization and carbonization of organic materials. This is due to the small
particle size rather than to the hydrophobic nature of the particulate matter,
and high pressure drop across a Venturi scrubber contributes toward improved
operation. The application of a high energy scrubber for smoke abatement
usually requires careful measurement with a pilot unit to determine the
pressure drop and horsepower requirement.
Incineration is an acceptable method of abatement for smokes generated by
volatilization of organic material in ovens. There are two limiting cases which
have different requirements, however. Where the volatile material is vaporized
at relatively low temperature and passes through the oven without oxidation,
the result is usually a white or blue-white plume similar in appearance to a light
steam plume. This material is generally in the vapor phase at temperatures
above 500° F and can be oxidized by passing it over a catalyst, or by thermal
incineration. Typical operating conditions for catalytic and thermal
incinerators on volatile hydrocarbons which tend to produce white smoke are:
Catalytic Thermal
Temperature, °F 700 1250
Residence time, sec 0.05 0.5
The second condition involves a partial incineration or oxidation of the organic
vapors in the furnace at a high temperature, and frequently in the absence of
sufficient oxygen to produce complete combustion. The resultant material is a
carbonaceous solid similar to lamp black. The appearance of a plume of this
material is gray to black. This material must be treated as a solid in the
incineration equipment. Catalytic incineration is not suitable, in that only
materials reaching the surface of the catalyst as vapors are subject to the
rate-increasing action of the catalyst. Thermal incineration is suitable but
requires a much more severe combination of time and temperature to provide
time for complete burning of the carbon particles. Reasonable conditions for
252
-------
incineration of the black smoke are in the range of 1400 to 2000° F and 1 to 2
seconds residence time. The smoke produced by brick kilns is relatively low in
concentration and is likely to require no more than 1 second residence time at
1500°F.
Because of the possibility that both types of organic emissions can exist in a
kiln firing clay to which organic materials have been added, a thermal
incinerator was specified for the hypothetical plants covered by the
specifications in this section.
Thermal incinerators have a substantial fuel requirement and some form of heat
recovery equipment is usually included. In this case, a self-regenerative heat
exchanger was prescribed for the incinerator. The choice between this kind of
heat recovery and using the heat to preheat furnace makeup air is purely an
economic one and will be specific to each application.
SPECIFICATIONS AND COSTS
Because emissions from brick and tile kilns are limited to those cases where
impurities in the clay are present, it is difficult to describe a general case which
covers all of the possibilities. The alternatives considered in this section are:
1) No air pollution control required
2) Inorganic gaseous pollutants generated by fluorides and sulfur in the
raw materials
3) Organic emissions from vegetable matter or oil in the clay
4) Both inorganic and organic impurities.
To cover these possibilities, two specifications were written. The first specifies
the installation of a wet scrubbing system for limiting fluoride and S02
emissions. This was based on the presumption of a high level of natural fluoride
minerals in the clay and emission requirements of the same order of magnitude
as those currently imposed by the State of Florida. In addition, sulfur and
flyash from combustion of high sulfur coal are included.
The second specification covers the installation of thermal incineration
equipment for the removal of carbonaceous smoke produced in the kiln by
incomplete burning of sawdust inclusions in the clay.
253
-------
These specifications are given in Tables 92, 93, 96 and 97. The averages of the
quotations submitted in response are given in Tables 94, 95, 98 and 99 and
plotted in Figures 70, 71, 73 and 74. The first cost for the scrubber
installations varies considerably because these systems are not common and
there is no stereotype which can be followed. It might be expected that the
costs for commercial installations solicited without a preliminary process design
might vary over a wide range.
The thermal incineration system quotations were received from two companies
of the IGCI who furnish this type of equipment. Of these, only one quoted the
complete turnkey installation, while the other supplied only the cost of the
incineration equipment.
There are few operating systems using either incineration or scrubbing equip-
ment. It is unlikely that any single instance exists where both of the problems
described are present in the same operation. If there is such a situation, it
would be necessary to install the two systems in tandem, and the costs would
approach the sum of the individual system costs.
254
-------
255
-------
TABLE 92
WET SCRUBBER PROCESS DESCRIPTION
FOR BRICK AND TILE KILN SPECIFICATION
This specification describes the air pollution aspects of a tunnel kiln used alternately for
manufacture of common brick and drainage tile. The ware is manufactured from a local clay
containing both fluorspar and pyrites, and therefore produces both fluoride and sulfur
dioxide emissions. In addition, the kiln is fired with high sulfur coal burned on a moving
grate. The scrubber must handle the paniculate and sulfur dioxide emissions from the fuel as
well as the gaseous emissions from the ware.
SCRUBBER SECTION
The scrubber is to be a medium energy level type, capable of the specified paniculate
efficiency, and concurrent reduction of SO? and fluorine to the desired levels. The scrubber
shall circulate at least 10 gallons of slurry per WOO ACFM of gas discharge from the
scrubber.
The scrubber is to maintain a recycle of scrubbing liquor to limit the consumption of fresh
water. Make-up water to offset evaporation losses shall be added automatically as required.
The ID fan shall precede the scrubber so as to avoid corrosion problems relating to wet
fluoride and sulfite gases. The fan and ductwork preceding the scrubber may be constructed
of carbon steel. The scrubber proper and all of the inter-connecting piping shall be rubber
lined, or equal. A rubber lined stack extension shall be provided to raise the discharge point
to approximately 50 ft above grade.
INSTALLATION
The scrubbing system is to be located adjacent to a railroad siding which will run between
the kiln and the scrubber system. The flue gas must be conducted across the siding, a
distance of approximately 30' at elevation + 25' with respect to grade, to the inlet of the ID
fan. A dequate space is available for all equipmen t in this area. Soil bearing pressures of 2,000
Ib/ff may be assumed for the area. Equipment is to be located outside and freeze
protection must be provided for ambient temperatures down to -1O°F. All utilities are
available at a substation adjacent to the scrubber area. The flow control instruments, alarms
for high and low liquid levels and motor control stations shall be assembled on a single
control panel, located inside the existing kiln control room.
256
-------
TABLE 93
WET SCRUBBER OPERATING CONDITIONS
FOR BRICK AND TILE KILN SPECIFICATION
Because the absorption of HF is one principal objective of this system, only one efficiency
level is specified.
- " Large
Capacity, ton/day
Process weight, ton/day
Dry ware
Water
Sulfur
Fluorine
Coal
Total
Small
100
124.8
100
16.8
0.25
0.25
7.5
124.8
250
312.06
250
42
0.63
0.63
18.8
312.06
Kiln discharge gas
Flow,ACFM
Temp., °F
Flow, SCFM
Flow, DSCFM
Moisture content, vol. %
15,000
270
11,000
10,300
6.0
36,000
290
25,500
23,900
6.4
Discharge Gas Contaminants
HF, ppm
SO2, Ppm
Fly ash, gr/ACF
F, Ib/hr (as F)
SO2, Ib/hr
Fly ash, Ib/hr
350
715
0.60
11.5
80.0
77
375
770
0.65
28.7
200
195
Scrubber Additions
Water, GPM total
evaporation, GPM
entrainment, GPM
4.2
4.0
0.2
9.6
9.1
0.5
Scrubber discharge
Flow, AC FM
Temp., °F
Flow, SCFM
Moisture content, vol %
Flow, DSCFM
72,500
119
11,600
11.2
10,300
29,600
120
27,000
11.5
23&00
< 100
< 3.4
71.5
270*
32*
Discharge gas contaminants
HF.ppm
HF, Ib/hr
Efficiency required, %
SO2, ppm
SO2- Ib/hr
Efficiency required, % —
paniculate, gr/ACF 0.02
paniculate, Ib/hr 2.2
efficiency required, % 97.1
'NOTE: These values are expected at a scrubber pH of 5.
< 100
< 8.1
73.5
290*
80*
0.02
5.1
97.3
257
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TABLE 94
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS
FOR BRICK AND TILE KILNS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol.
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol.
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
%
%
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost "**
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other J
(4) Total Cost
>
LA Process Wt.
Small
Large
High Efficiency
Small
15,000
270
11,000
6.0
0.6
77
12,900
119
11,600
11.2
0.02
2.2
97.1
13,697
3,735
1,589
533
68,752
88,306
Large
36,000
290
25,500
6.4
0.65
195
-
29,600
120
27,000
11.5
0.02
5.1
97,3
22,250
8,245
2,854
750
81,610
115,709
258
-------
TABLE 95
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR BRICK AND TILE KILNS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$6/hr
$.011/kw-hi
S.25/M gal
LA Process Wt.
Small
Large
High Efficiency
Small
600
2,520
1,007
3,894
722
4,616
8,743
8,831
17,574
Large
600
2.659
2,216
9,438
1,651
11,089
16,564
11,571
28,135
NJ
Ul
CO
-------
FIGURE 70
CAPITAL COSTS FOR WET SCRUBBERS FOR
BRICK AND TILE KILNS
CO
cc
CO
o
CO
o
I
1-
100
80
68
50
40
30
20
10
50
COLLECTOR PLUS AUXILIARIES
100 200
PLANT CAPACITY, TON/DAY
300 400 500
260
-------
FIGURE 71
ANNUAL COSTS FOR WET SCRUBBERS
FOR BRICK AND TILE KILNS
40
30
20
C/3
EC
o
O
LL
O
V)
a
o
i
o
o
10
TOTAL COST
JOPE RATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
80 100 200 300 400
PLANT CAPACITY, TON/DAY
261
-------
-------
263
-------
TABLE 96
THERMAL INCINERATOR PROCESS DESCRIPTION
FOR BRICK AND TILE KILN SPECIFICATION
This specification describes the requirements for a thermal incinerator for abatement of a
gray or black smoke plume produced by the kiln. The smoke plume exists only when organic
filler (sawdust) is added to the clay to improve the insulation characteristics of bricks. Other
than the emission of this paniculate matter, the kiln produces no byproducts which could be
construed as air pollutants. Natural gas is the fuel used for firing, and the native clay may be
considered free of fluoride, sulfur or any other noxious materials.
The incinerator must be designed to abate the smoke plume from the effluent stream as
presently comprised. However, reuse of heat is a prime concern and is to be accomplished by
a self regenerative heat exchanger.
The incinerator shall be maintained under a negative pressure by virtue of a fan at the outlet
of the heat exchanger on the flue gas side. This fan is to be selected to overcome the pressure
drop of the incinerator and both sides of the heat exchanger. This new ID fan is to discharge
into a 50 ft stack, which may be constructed of carbon steel.
The incinerator shall be fueled by natural gas. The burner shall be of the 100% secondary air
type, utilizing oxygen in the furnace effluent for combustion. The burner shall be equipped
with a continuous pilot, and shall be controlled to maintain an outlet temperature no higher
than 150O°F. Gas piping flame failure controls, etc. shall be designed to meet F.I.A. * safety
standards.
A damper shall be provided to prevent overloading the fan during startup if required.
INSTALLATION
The incineration system is to be located adjacent to a railroad siding which will run between
the kiln and the incineration system. The flue gas must be conducted across the siding, a
distance of approximately 30' at elevation + 25' with respect to grade, to the inlet of the
incinerator. Adequate space is available for all equipment in this area. Soil bearing pressures
of 2,000 Ib/fr may be assumed for the area. Equipment is to be located outside. All utilities
are available at a substation adjacent to the area.
For purposes of this proposal, the fan and dampers are to be considered auxiliaries. A
complete turnkey proposal including foundations, stack, etc. is requested. Ductwork from
present stacks to the incinerator shall be included in the turnkey price.
^Factory Insurance Association
264
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TABLE 97
THERMAL INCINERATOR OPERATING CONDITIONS
FOR BRICK AND TILE KILN SPECIFICATION
One incinerator should be quoted for each size kiln listed below.
Small
Kiln capacity, ton/day
Process weight, ton/day
Dry ware
Water
Total
Kiln discharge conditions
Gas flow, ACFM
Temp, °F
Gas flow, SCFM
Organic content, Btu/SCF
Organic content, gr/SCF
Organic content, Ib/hr
Incinerator discharge conditions
Gas flow. SCFM
Temp, °F
Organic content, gr/SCF
Organic content, Ib/hr
Incineration efficiency, %
Hot gas discharge from heat exchanger, °F
Cold gas flow, SCFM
Cold gas temp, °F
Cold gas discharge temp, °F
Heat exchanger duty, MM Btu/hr
100
116.8
100.0
16.8
116.8
15,000
270
11,000
0.5
0.35
33
Large
250
292
250.0
42.0
36,000
290
25,500
0.5
0.3
79
-11,150
7,500
0.0039
.033
99.9
770
1 1,000
270
1,010
~ 9.6
~25,900
7,500
0.0036
.079
99.9
770
25,500
290
1,010
~ 22.4
265
-------
TABLE 98
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR THERMAL INCINERATORS
FOR BRICK AND TILE KILNS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr Comb.
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr comb.
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)*
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
( i) Supervision
(j) Startup
(k) Performance Test
(I) Other
(4) Total Cost
LAProcessWt.
Small
Large
High Efficiency
Small
15,000
270
11,000
64
33
24,862
725
11,120
84
0.033
99.9
50,900
12,463
15,932
10,621
31,863
7,300
5,311
3,540
1,770
4,200
2,700
1,800
2,500
150,900
Large
36,000
290
25,500
64
79
58,115
735
25,775
84
0.079
99.9
89,300
25,177
20,182
15,122
40,366
10,061
7,060
6,707
3,354
6,200
3,600
2,700
3,500
233.329
* Includes motors, starters, drives
Based on one quote.
266
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TABLE 99
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR THERMAL INCINERATORS FOR BRICK AND TILE KILNS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$6/iir
$6/hr
$0.80/NflBTU
LA Process Wt.
Small
,1
Large
High Efficiency
Small
1,500
1.500
960
40
1,000
300
44,720
44,720
47,520
16,700
64,220
Large
1,500
1.500
960
40
1,000
300
103,200
103,200
106,000
27,003
133,003
ISJ
-------
FIGURE 73
CAPITAL COSTS FOR THERMAL INCINERATORS
FOR BRICK AND TILE KILNS
400
300
200
C/3
EC
§
1
I
o
I
u
100
80
70
60
50
40
TURNKEY SYSTEM
COLLECTOR PLUS AUXILIARIES
.COLLECTOR ONLY
80 100 200 300
PLANT CAPACITY, TON/DAY
400
268
-------
FIGURE 74
ANNUAL COSTS FOR THERMAL INCINERATORS
FOR BRICK AND TILE KILNS
V)
cc
o
Q
I
I
o
o
200
100
80
70
60
50
40
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
80 100 200 300
PLANT CAPACITY, TON/DAY
400
269
-------
REFERENCES
1. Searle, A. B., Modern Brickmaking, 1956.
2. Norton, F. H., Refractories, 1968.
3. Semrau, K. T., "Emission of Fluorides .from Industrial Processes — A
Review", Journal of APCA, Vol. 7, No. 2, Aug. 1957.
4. Clews, F. H., Heavy Clay Technology, Academic Press, Inc., 2nd ed.. New
York, 1969.
270
-------
o
O
3
m
30
m
Z
n
-------
7. COPPER SMELTING
Copper is a widely used metal because of its high thermal and electrical
conductivity, and because it is very resistant to corrosion. The latter property is
due to the formation of a thin protective layer of basic salts on the surface
when it is exposed to the atmosphere.111 Copper is also widely used as an
alloying element in corrosion resistant materials such as brass, bronze, monel
metal and cupro-nickel.
Almost all of the industrial uses of copper require the metal in relatively pure,
metallic form. Most natural copper deposits in the U.S. occur as sulfides, and
this discussion deals primarily with the methods used to obtain pure metal
from the natural sulfide ores. Some copper deposits in oxide form and as
metallic or "native" copper are found in the U.S., but these are of secondary
interest, both as sources of copper and as air pollution sources.
Most of the copper mined in the U.S. is from deposits of:
Gornite
Chalcopyrite
and Enargite Cu32
control and recovery will be discussed.
THE OVERALL SMELTING PROCESS
Copper almost always occurs in deposits with other metals such as iron, lead,
arsenic, tin or mercury. The smelting process must be adapted to the particular
ore type and concentration at any given mine. In the U.S., about 94% of the
271
-------
copper ore is processed by a series of operations consisting of mining,
concentrating, smelting and refining.(2) These steps can be further subdivided
as follows:
mining
concentrating
smelting
refining
/"drilling
I blasting
| loading
(^handling
crushing
grinding
classification
flotation
dewatering
| roasting
•< reverberatory smelting
[^converting
{fire refining
electrolytic refining
Although this discussion is aimed primarily at the smelting area, some
discussion of the other operations is included for background.
MINING
Most U.S. produced copper comes from large open-pit mines such as those in
the Southwest (Arizona, Nevada and Utah) and in Montana. The porphyry
deposits are scraped clear of over burden, and blasting operations with
ammonium nitrate or other low-cost explosives are used to loosen the ore.
Electric shovels, with bucket capacities as large as 15 cubic yards, load trucks
of 60 to 85 ton capacity. The ore is hauled to a mill for concentration from 1%
or so up to 15 to 30% copper by weight.
CONCENTRATION
Sulfide ores can be separated from the non-copper bearing rock or gangue by a
froth flotation process. In order to accomplish this separation, the porphyry
must be ground to a powder and the valuable minerals "liberated" from the
gangue.
272
-------
The grinding usually starts in gyratory crushers which reduce the maximum size
to the 6 to 9 inch range. These are followed by cone-type crushers which
reduce the size to 1 to 2 inches. Wet grinding operations in rod mills and,
finally, wet grinding in ball mills are used to produce a nominal 65 to 200 mesh
product. The ball mills are generally built with a particle size classifier on the
outlet, which separates the ground product into a fraction which is acceptable
to the flotation process, and an oversize fraction which is recycled to the mill.
Lime is often added to the ore before final grinding if FeS2 is present.12'
Flotation is accomplished by introducing air into the water slurry along with
chemical agents called "frothers" and "collectors". These materials produce a
froth of air bubbles which rise to the top. The copper sulfide minerals attach
themselves to the froth bubbles and are carried out the top of the flotation cell,
while the gangue sinks to the bottom and is discarded as "tailings".
Many complex procedures are used in flotation processes to upgrade the ore to
the optimum concentration by operation of flotation cells in series, by
"differential flotation" to separate sulfide salts of other metals such as FeS2
and MoS2. Chemicals such as xanthates, dithiophosphates, and dextrin are used
as collectors, "activators", "dispersants", etc. in these processes.
The usual product of copper sulfide ore concentration is a washed and
dewatered concentrate, containing 15 to 30 wt. % copper, and suitable for
smelting.
SMELTING
"Smelting" covers all of the processes necessary to transform copper salts into
metallic copper. These processes usually include reverberatory smelting. Figure
75 is a schematic representation of the relationship between these processes.11'
The steps in the smelting process are aimed at making two types of separations:
1) between the metals and the gangue
2) between copper and the chemically combined contaminants sulfur
and iron
The reverberatory furnace accomplishes the main separation between the
minerals and gangue which is withdrawn as a molten slag. The ratio of Cu/S/Fe
is adjusted in the mineral portion of the melt to produce a "matte" with about
273
-------
NJ
WASTE
TAILINGS *-
SO2 RICH
FLUE GAS
WATER
1
HOT
I
GASES
WASTE
HEAT
BOILER
STEAM
HOT FLUE
GAS TO
COPPER ORE
ORE
DRESSING
1-
CONCENTRATE
li
» b I
1
J
!INC OR PYRITIC
CONCENTRATE
AND PLANT REVERTS
ROASTING
REVERBERATORY
FURNACE
.SMELTING
MATTE
•> DUMP SLAG
AIR
QUARTZ
CONVERTER
DUST COLLECTOR
SLAG
RECYCLE
BLISTER COPPER
TO ELECTROLYTIC
REF NING
FIGURE 75
SCHEMATIC DIAGRAM OF SMELTING PROCESSES
-------
45% Cu content. This is then taken to the converter where the iron is oxidized
and withdrawn as a slag, after which the sulfur is oxidized to S02 and
discharged as a gas.
Each of the smelting steps is described in more detail in the following
paragraphs.
ROASTING
Roasting of dried ore concentrate prior to reverberatory furnace smelting is not
as widely practiced now as it was in the past. Over the past 30 years, a trend
toward discontinuing roasting and feeding "green" concentrates directly into
the reverberatory furnace resulted in shutting down most roasting furnaces.
However, there has been a reversal in this trend, and a number of new roasting
processes as well as processes of new design have been started up recently'4'.
Roasting is basically involved with heating the ore concentrate to a temperature
below the melt point in order to drive off some of the sulfur as sulfur dioxide.
This is a useful step in adjusting the sulfur content of the concentrate so that
the reverberatory furnace product will be optimized. Several other advantages
of roasting are:
1) the ore is dried and conditioned so as to minimize handling problems
2) the roaster permits easy arsenic and antimony removal
3) some oxidation of iron and copper improves iron removal in the
reverberatory furnace.
ROASTING PROCESS DESCRIPTION
Roasting has been done mainly in multiple hearth roasting furnaces known as
Nichols-Herreshoff or MacDougall furnaces, and in fluidized solids devices such
as that used in the Fluo Solids Process.* These furnaces contain a series of
circular hearths, arranged one above another. The solid ore is moved from the
outer edge of the top hearth toward the center by rotating "rabble arms"
supported by a central shaft. At the center of the hearth, the ore falls through
an opening onto the next hearth down, where it is raked toward the outside.
Eight to 12 hearths are provided in conventional roasters. Figure 76 shows a
schematic drawing of a multiple hearth roaster.
'Registered trademark of the Dorr Company
275
-------
N)
-»J
O>
DISCHARGE
TO
ATMOSPHERE
t
MULTIPLE
HEARTH
ROASTING
FURNACE
J
ROASTED
ORE
00
REVERBERATORY
FURNACE
SETTLING DUST
CHAMBER COLLECTOR
\\\\ \x\ \\) K\\\x\\\x\\\
FIGURE 76
MULTIPLE HEARTH ROASTER
\/
-------
These units are fed with cold concentrate and gradually raise the temperature
to 1400°F or so. Heat may be supplied by burners installed beneath any hearth
level although firing beneath the lowest hearths only is most common.
"Autogenous roasts" where the heat requirements are supplied entirely by the
heat of oxidation of sulfur to SC>2 can be made at sulfur contents of about 24
wt. % and higher. Even then, heat generated by gas or oil burners is required to
bring the roaster up to temperature.
Multiple hearth roasting has been largely discontinued, and the fuel,
maintenance and air pollution control costs associated with the operation of
these furnaces eliminated. This has been made possible by the improvement of
concentration processes, which produce a rich enough green concentrate for
charging directly to the reverberatory furnace.
The air pollution problems in reverberatory furnace smelting are increased by
the omission of the roasting step because the SC>2 ordinarily discharged from
the roaster must be discharged from the reverberatory furnace. The roaster is
basically a more efficient heating device, and produces a more concentrated
862 product than the reverberatory furnace. A typical roaster operates with
flue gas at 400 to 600°F and an 862 content of 3 to 10% by volume, whereas
the flue gas from a reverberatory furnace is about 2300°F and 1 to 2 volume %
so2.m-(4)
Where no SC>2 abatement is practiced, it is obvious that the lower
concentrations and higher temperatures produced by the reverberatory furnace
result in better dispersion of S02 into the atmosphere. However, when
minimizing SC>2 emission or recovering the sulfur values is an objective, the
advantage lies clearly with the lower temperatures and higher concentrations
produced in roasting.
This is the principal reason for the resurgence of interest in roasting. The newer
operations in which roasting is being used have tended toward use of a fluidized
solids technique such as the Fluo Solids Process (a registered trademark of the
Dorr Company). In this process, the concentrate is maintained in a fluidized
bed by upflow of heated air. For those concentrates with sufficient sulfur
content, the fluidized bed can be operated autogenously with minimum excess
air, and S02 concentrations of about 15% can be achieved.15' This provides an
excellent feed gas for a contact sulfuric acid plant, and minimizes the cost of
S02 abatement.
Much development work is preceding in the area of process modification to
further reduce emissions of SC^. This is aimed primarily at recovery of sulfuric
acid from gas equivalent to that o'f the flash roaster, without the subsequent,
difficult-to-treat emission from the reverberatory furnace.
277
-------
NATURE OF GASEOUS DISCHARGE FROM ROASTERS
The gases leaving a roaster consist principally of air which has been modified by
oxidation of fuel in the gas or oil-fired burners, followed by oxidation of some
of the sulfur in the ore. The combination of these processes can be represented
by the equations:
CH4 + 202 ^C02 + 2H20
and
Fe2S + 2O2 -»• 2FeO + SO2.
The relationship between heat requirement, oxygen content and effluent gas
composition can be calculated for any combination of circumstances. The
concentration of SO2 is influenced by the amount of heat required as input to
the burners, and by the efficiency of contacting the furnace gases with the
charge. S02 concentrations somewhat lower than theoretical for the oxygen
content are usually obtained.(6)
Some additional oxygen usage for oxidation of arsenic and other impurities can
bring about higher ratios of S02 to oxygen than indicated by theoretical
equations. However, calculations of this sort should produce results accurate
enough for sizing pollution control equipment.
Gaseous Contaminants
In addition to these gaseous constituents, there may be enough SOg to cause
acidic corrosion problems whenever the gas temperature is reduced sufficiently
to produce liquid condensate. This probably arises from the following sequence
of reactions:
Fe2S + 202 -> 2FeO + S02
2S02 + 02 Catalyst 2S03
Roaster operations take place at a low enough temperature to favor formation
of sulfur trioxide, but there is insufficient residence time or available catalyst
to convert more than 1 to 3% of the S02 to S03.(6)
There may also be traces of HCI and HF from the decomposition of halogen
bearing minerals such as fluorite or fluorapetite rock, present as gangue in the
roaster charge. These are most objectionable because of the severe corrosion
problems generated when these acids co-absorb with SOg to form halogen
278
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contaminated strong acids.
Particulate Contaminant
The roaster gases contain substantial concentrations of dust, produced
mechanically by the handling of the concentrate as it is dumped into the
roaster, pushed around each hearth and dumped from hearth to hearth. In
addition, there is some formation of SOg which combines with water vapor at
temperatures below about 400°F to form sulfuric acid mist. This mist is of
very small particle size, and is more difficult to remove by mechanical means
than is the dust.
In order to clean the gas sufficiently for charging to a contact-type sulfuric acid
plant, the paniculate material must be removed to prevent plugging the catalyst
bed, and also to minimize contamination of the product acid. H^SC^ mist
must be removed to prevent corrosion and plugging in the "front end" of the
acid plant. Also any acid mist formed will pass through the converters and
absorbers.
The particulate contaminants vary in composition with the specific ore in
question. Common constituents are arsenic, antimony, mercury, and lead,
which appear as oxides in the roaster effluent. Upper limits'61 for
contamination of the gas stream may be estimated on the assumption that all
of the contaminants appear in the product acid. These are shown below.
S02Content, Vol. % of Dry Gas 7 9
Sol ids Content gr/DSCF
Chlorides as Cl 0.055 0.071
Fluorides as F 0.011 0.014
Arsenic as As203 0.087 0.11
Lead as Pb 0.087 0.11
Mercury as Hg 0.0011 0.014
Selenium as Se 0.044 0.056
Total Solids 0.44 0.56
GAS CLEANING EQUIPMENT
The treatment of roaster gases for particulate removal is practiced whether or
not the gases are processed for the removal of sulfur. However, the high
concentration and low gas temperature usually require some form of sulfur
dioxide removal before discharge into the atmosphere.
279
-------
Sulfuric acid plants are capable of bringing about SOo removal at efficiencies as
high as 99.5%, while manufacturing 98 wt. % sulfuric acid of salable quality.'61
This approach has been used on most roasters now in operation.
The roaster effluent must be treated to remove coarse dust, fine dust, gaseous
halogens, SOg in particulate and gaseous form, and water vapor before it is
acceptable for charge to a contact sulfuric acid plant. One of several possible
schemes for treatment is shown in Figure 77.
Coarse dust is most often removed by a large mechanical collector or settling
chamber or a combination of the two. The dust is returned to the process —
usually by way of the reverberatory furnace — and this collection step is
ordinarily treated as a part of the process rather than as a gas cleaning
operation. Precipitators may be used instead of the mechanical collector in
special cases.
The removal of halogen gases, part of the particulate solids and some of the
SOg is accomplished in a wet scrubber. This may be located after the
precipitator, but it is customary to minimize the dust loading to the
precipitator by using the flow scheme shown. The scrubber is ordinarily a
"medium-energy" impingement tray type in which jets of gas impinge on
wetted baffles.
The scrubber can build up a substantial concentration of sulfuric acid if the
scrubbing liquor is recycled. This can cause severe corrosion problems in the
scrubbing circuit, even when stainless steel is used throughout, if there is much
chloride or fluoride present. In order to avoid this problem, the acid
concentration is limited by withdrawing acid and adding fresh water make-up
to the system. Acid concentrations from less than 3 wt. % to over 30 wt. %
have been used.'61 Concentrations in excess of 10 wt. % have led to corrosion
problems in the field.
The precipitator following the scrubber serves mainly to remove sulfuric acid
mist and also to do the final cleanup of particulate matter. This is of very small
particle size and is not effectively removed by medium-energy scrubbers. The
mist precipitator collects the acid mist as a relatively concentrated liquid — up
to 60 or 70 wt. %. The precipitator needs no rappers, of course, because the
tubes are washed by the acid as it runs down into a collection sump at the
bottom. The entire unit must be designed to withstand acidic corrosion. In
addition to the mist, some residual dust will, of course, be collected. This
material becomes a contaminant in the product, and reduces the desirability of
the dilute acid. In some areas it may be salable for pickling or other
applications where high strength and purity are not important.
280
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ROASTING FURNACES
r
ABATEMENT EQUIPMENT
COOLING
CHAMBER
DOUBLE CONTACT
SULFURIC ACID PLANT
ROASTED
PRODUCT
L
1,
/*
tev
SOLIDS TO
REVERBERATORY
FURNACE
ACID TO ORE
CONCENTRATION
ACID TO I I
STORAGE
I I CONCENTRATION
_J L
J
MAKE-UP
WATER
98 Vo ACID
FIGURE 77
SCHEMATIC DRAWING OF ROASTER GAS CLEANING SYSTEM
-------
The precipitator must remove acid mist to a low enough level that it will not be
troublesome in the sulfuric acid plant. One stage of precipitation (one electrical
field in the direction of gas flow) may be satisfactory but a conservative design
will require two fields in order to minimize the effect of an electrical failure.
At elevated temperatures, the ratio of water to S02 in the gas stream is likely
to be too high to allow the production of concentrated acid. For this reason it
is customary to cool the gases. The cooling can be done in the scrubber by
evaporation or in a contact cooling chamber located between scrubber and
precipitator. The temperature required may be calculated on the basis of the
chemistry taking place in the acid plant. For example, to produce 98 wt. %
sulfuric acid at 99% efficiency, the combining proportions are:
S02 + V202 + H20 -> H2S04
64 Ib + 16 Ib + 18 Ib ->• 98 Ib
for 100% acid, or
64 Ib + 15 Ib + 20 Ib ->• 100 Ib
for 98% acid. The ratio of water vapor to reacted acid is (20/64) provided all of
the S02 is converted to acid. If only 99% of the S02 is converted but all of the
water is, then the allowable weight ratio of water to acid is reduced to 0.99 x
(20/64) =0.31/1, or a volume ratio of (64/18) xO.31 = 1.11.
For a gas stream containing 9 volume % on a dry basis, the water content can
be 9 x 1.11 = 10 volumes per 100 volumes of dry gas. This corresponds to a
saturation temperature of about 110°F at sea level.
REVERBERATORY FURNACE SMELTING
Reverberatory furnace smelting is an essential step in the production of most of
the copper minedjn the U.S. Either calcine from a roaster or green concentrate
is charged to the reverberatory furnace. Molten slag and a molten product
called "matte", containing the copper, iron and residual sulfur are produced.
The reverberatory furnace accomplishes several functions/21 which include:
(1) melting the minerals
(2) separation of valuable minerals from the gangue
282
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(3) final adjustment of sulfur content of the matte for charging to the
converter
(4) removal of precious metals from the gangue by extraction with the
liquid matte.
The basic reverberatory smelting process is shown diagramatically in Figure 76
and Figure 78.
Roasted calcine or green concentrate is added to the reverberatory furnace
from cars or belt conveyors located above and to the sides of the furnace. The
solid is added at the sides and along the length of the furnace, as shown in
Section A-A of Figure78,This forms a trough consisting of a pile of solid charge
along either side of the furnace, with molten matte and slag toward the center.
The furnace is heated by gas or oil-fired burners located above the charge at
one end and firing toward the other end. Pulverized coal firing is occasionally
used. The heat produced by the burner flame is transferred to the molten slag
and matte, and to a lesser extent to the solid charge, by convection and by
radiation from the hot refractory arch and sidewalls.
As heat is transferred to the cold charge, moisture is released and some sulfur is
driven off. At about 1650°F, the cuprous and ferrous sulfides begin to diffuse
into one another, and at about 1800°F they melt to form liquid matte. This
trickles down through the remaining solid charge and heats it. At the same
time, silver, gold, arsenic, antimony, and other metallic impurities are dissolved
in the matte.'3)
Matte forms continuously and is tapped at intervals from matte taps at the
bottom of the hearth, along the length of the furnace. The slag floats on top
and is skimmed through slag tap holes at the flue end of the furnace.
Although many of the operations such as charging, tapping matte and
skimming are done intermittently, the process is basically continuous, with
relatively stable firing of the burners and production of flue gas.
CHEMISTRY AND PHYSICS OF THE PROCESS
Reverberatory smelting involves a relatively complex set of reactions between
copper, sulfur, iron and oxygen; simultaneously complex side reactions
involving impurities such as precious metals, arsenic, antimony and other
minerals are also going on. The basic Cu—Fe—S—0 reactions are relatively
283
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ROASTED
OR
GREEN
CHARGE
FUEL
GAS
COMBUSTION
BRICK
REFRACTORY
SLAG
MATTE
SLAG
SOLID
CHARGE
MATTE
MATTE
TAP
HOLES
WASTE HEAT
BOILER
\ \\ \\X\\\NI rs.\ \ \ \
FIGURE 78
REVERBERATORY FURNACE
SECTION A-A
-------
consistent from one smelter to another, while those involving impurities show
great variability.
Ore is ordinarily charged to a reverberatory furnace in the green state, with a
copper content of 15 to 30 wt. %.(2>
A green concentrate of chalcopyrite has approximately the following
composition11 ' of elements:
Atomic Wt. Wt. %
Cu 63.57 34.3
Fe 58 31.2
S 64 34.5
100.0
In order for this to have 30 wt. % copper, it is necessary that diluent material
(gangue) to the extent of 0.143 Ib per pound of chalcopyrite, or 0.125 Ib/lb
ore be included.
Now, in the smelting furnace, the copper preferentially attaches itself to sulfur
as cuprous sulfide, Cu2S. Some of the sulfur is driven off as S02, and some
remains with the iron as FeS. However, the temperature and oxygen content
are sufficiently high that part of the iron is oxidized to FeO, and becomes more
soluble in the slag than in the matte. The overall reactions might be represented
in oversimplified form, as:
2CuFeS2 + 2y202 -*• Cu2S + FeS + FeO + 2S02
This process produces a matte that is substantially free of gangue, and has
between 30 and 50% copper content by weight. In order to reach 50% copper,
about half of the iron charged, and half of the sulfur charged must be removed
by the products of combustion, or with the slag.
Several reactions are important in the removal of iron from the matte without
an inordinate amount of copper loss. Ferrous oxide (FeO) combines readily
with silica or calcium silicate. For this reason both lime and silica are added to
the reverberatory furnace as fluxes. Some magnetite (FegO^ may be present in
the charge as an impurity, or may be formed by the oxidation of ferrous oxide.
This dissolves readily in the slag, and tends to cause high solubility of copper in
the slag. Magnetite has several other undesirable effects.121
285
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GASEOUS EFFLUENT FROM THE PROCESS
The flue gas produced by a reverberatory furnace is relatively rich in C02 and
water because of combustion of the fuel, and little of the oxygen is used for
combustion or replacement of sulfur. Typically., the flue gas contains around
13% C02 and only 11/2% S02.'4' The reactions involved in the generation of
the flue gas are summarized below.
Combustion:
CH4 + 02 + N2 • C02 + H20 + 02 + N2
oxidation of sulfur, iron:
02 + CuFeS2 - Cu2S + FeS + FeO + S02.
H. Lanier121 gives the composition limits for reverberatory furnace effluent
gases as follows:
Volume %
Minimum Maximum
02 56
N2 72 76
C02 10 17
H20 4 10
CO 0 0.2
SO2 1 2
The composition may be derived on a theoretical basis for any given oxygen
and S02 content in the flue gas by presuming that the only reactions which
take place will be:
(CH) + 11/a02 • C02 + y2H20 (using coal for example)
and
Ore + 21/202 > slag + matte + 2S02.
A material balance such as that shown in Table 100 may be prepared. This gas
composition falls into the range indicated. However, most reverberatory
furnaces are now gas fired, and the combustion products are likely to be much
wetter and contain less C02. Table 101 illustrates a calculation of flue gas
composition for a gas-fired furnace. Fuel oil fired furnaces should fall between
these limits. It appears that the fuel composition should have a more
286
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TABLE 100
CALCULATED COMPOSITION OF REVERBERATORY
FURNACE FLUE GAS
(from coal burning)
Mol/100 Mol Air
02
N2
CO 2
H20
S02
(CH)
Burner
Air Fuel Reaction
20.8 - -12.6
79.2
- ' +10.0
+ 5.0
- - -
10.0 -10.0
Combustion Smelting
Products Reaction
8.2 -2.0
79.2
10.0
5.0
+1.6 ,
— —
Furnace
Flue Gas
6.2
79.2
10.0
5.0
1.6
—
Vol.
%
6.1
77.6
9.8
4.9
1.6
—
100.0 10.0 - 7.6 102.4 - 0.4 102.0 100.0
287
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°2
N2
C02
H20
SO2
TABLE 101
CALCULATED COMPOSITION OF REVERBERATORY
FURNACE FLUE GAS
(from gas burning)
Mol/100 Mol Air
Air Fuel
20.8
79.2
- -
- -
— —
Burner
Reaction
-12.2
-
+ 6.1
+ 12.2
—
Combustion
Products
8.6
79.2
6.1
12.2
—
Smelting
Reaction
-2.1
-
-
-
+1.7
Furnace
Flue Gas
6.5
79.2
6.1
12.2
1.7
Vol.
6.1
74.2
5.7
11.4-
1.6
CH4 6.1 - 6.1
100 6.1 0.0 106.1 - 0.4 105.7 99.0
288
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pronounced effect on flue gas composition than indicated in the literature.
The rate of flue gas production by a given furnace varies with the type of fuel,
the excess air (or oxygen content of the flue gas) and the rate of heat
generation.
Typically, a reverberatory furnace may have the following fuel
requirements:<2)
coal 275 - 400 Ib/ton of charge
oil 0.5 - 1.5 bbl/ton of charge
fuel gas 30 — 80 therm/ton of charge
These values represent heat requirements between about 3 and 8 million
BTU/ton of charge. If one presumes gas firing with a flue gas composition as
given in Table 2, 105.7 mols of flue gas are produced per 6.1 mols of natural
gas. At a value of 5 MMBTU/ton charge and 970 BTU/SCF, the furnace should
produce
105.7
6.1
or, on the basis of a 30% Cu charge and 45% product, the value of
89,000 X -||- = 134,000 SCF/ton matte
should be applicable. Corresponding numbers can be derived for other fuels,
oxygen contents, etc.
PARTICULATE CONTAMINANTS
Reverberatory furnaces charge several powdered or granular materials which
may become suspended in the flue gas and create a dust emission problem.
These are:
1. fresh concentrate or calcine
2. lime
3. silica
The dusts are relatively coarse and are removed to a considerable extent by
gravity settling within the furnace, settling within the waste heat boiler, or
collection in cyclone collectors. Dusts collected in these locations may contain
as much as 25% copper12) and collection improves the overall process
economy. 289
-------
Fumes, on the other hand, consist mainly of high vapor pressure impurities
which have vaporized out of the matte, and recondensed as tiny oxide particles.
Arsenic, antimony, lead, and zinc are common fume-forming materials. Sulfur
trioxide, formed to the extent of perhaps 1 to 3% of the SC>2 produced, and
carbonaceous smoke produced by improper combustion may also be
contributors to the fume loading. Also considerable lime may be present.
Fume-like materials settle only to a limited extent, and most of the effort to
limit paniculate air pollution must be directed toward these materials. For
purposes of this discussion, it may be assumed that a typical reverberatory
furnace produces a flue gas with about 11/2% SC>2 by volume, and that this
concentration is too low for economical recovery of the sulfur values as
1^804. The gas discharge from the furnace must be treated to remove the
fume-like materials to a suitable degree for discharge into the atmosphere.
POLLUTION CONTROL CONSIDERATIONS
Reverberatory furnaces are ordinarily equipped with steam generators to
recover heat from the flue gases. The combination of the waste heat boiler and
a tall stack for S02 dispersal allows for natural draft ventilation of the furnace
when there is no air pollution control equipment.
Installation of an electrostatic precipitatorfor particulate control may be made
without the installation of an induced draft fan. However, any application of
scrubbers or filters, and many precipitator applications will require the
installation of an induced draft fan to offset the pressure losses in the
abatement equipment. The application of induced draft fans allows a higher
degree of control of the furnace draft, and provides for minimum outleakage of
hot, contaminated flue gases prior to cleaning.
Common practice is to install flue gas cleaning equipment which handles only
the gases passing through the steam generator. Dusting, which occurs as
concentrate, lime and other solids are added to the furnace, is held to a
minimum by the design of the hoppers and conveyors and frequently by the
processing of these materials while they are still wet. The charging system is
designed to minimize air infiltration into the furnace, and the "closed-in"
design also helps minimize dusting problems.
The slag tapping and matte withdrawal produce some fume which is released
into the building. This fume is not sufficiently troublesome to require hooding
of the matte taps, slag taps, launders or ladles.
290
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The dust collected from the copper reverberatory furnace flue has a definite
economic value. The dust consists of copper concentrate, fluxes and partially
smelted materials. Ordinarily, the collected material may be returned directly
to the reverberatory furnace for resmelting. Very fine dusts may require
sintering before re-addition to the furnace. Some furnaces produce particulate
materials too rich in arsenic, antimony or other impurities to be returned to the
furnace without chemical treatment.
There may be a significant difference in composition between the coarse dust —
produced by mechanical action in the furnace — and the fine fume which is
generated by vaporization of such volatile metals as antimony and zinc. The
coarse material may contain as much as 25% copper by weight, and be suitable
for direct addition to the furnace, whereas the fume is likely to be low in
copper content, and have a high fraction of objectional volatile metals. It is
customary to make a crude separation between these two by providing large
"balloon flues" which serve as settling chambers for the coarse dust, and
minimize the "catch" in the final gas cleaning device.
APPLICABLE EQUIPMENT TYPES
Electrostatic precipitators were originally developed in the 1890's to solve the
fume problem produced by copper smelters. These devices have many
advantages when processing hot gases at high flow rates. These include:
1. minimal gas moving equipment
2. low operating cost
3. freedom from corrosion problems
4. ability to capture fine fume particles
5. production of a dry solid.
Wet scrubbers have been used for fume collection on reverberatory furnaces.
Although they require a substantial pressure drop — with the attendant
operating cost — to produce satisfactory performance, they offer some
advantages. These include:
1. production of a wet slurry (which is advantageous if wet chemical
operations follow)
2. the scrubber does not require careful control of gas temperature or
humidity, as does the precipitator
3. first cost is relatively low.
291
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Offsetting these advantages are three disadvantages.
1. When used for cooling purposes, scrubbers exhibit high water
consumption.
2. Corrosion and maintenance costs can be high.
3. Scrubbers produce steam plumes.
For the purposes of this study, both approaches have been included in the
specifications and cost comparisons.
SPECIFICATIONS AND COSTS
The copper roasting furnace gas cleaning system as described in the
specifications in Table 102 differs from all the other applications covered by
this study, in that it covers only a part of the air pollution abatement system.
The complete system is comprised of the gas cleaning equipment described and
a sulfuric acid manufacturing plant for the removal of S02 from the gas stream.
The gas cleaning equipment serves to clean the gas sufficiently to keep the
sulfuric acid plant catalyst clean and to produce the proper temperature and
humidity to yield the desired acid strength. The system specified describes a
multiple hearth roaster, but should be applicable to fluidized bed roasters at
similar SO2 levels.
This portion of the system is included in the study to procure costs for the
precleaning equipment to add to costs for sulfuric acid plants already
assembled by the EPA.
The equipment described serves to remove entrained dust in an impingement
scrubber; then the moisture content of the gas stream is reduced by direct
contact cooling so the acid produced will not contain too much water diluent.
Finally the sulfuric acid mist present in the gas stream must be removed at near
100% efficiency to prevent "front-end" corrosion in the acid plant and damage
to the catalyst bed.
It is customary for the entire train to be quoted by the precipitator
manufacturer, as though the scrubber and cooler were auxiliaries to the
precipitator. In this case, the quotations were prepared for the complete train
installed as a system.
292
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The precipitator for this application is of the vertical tubular variety, quite
different in design from the more conventional plate-type precipitators used in
dry applications. In particular, when two or more independent fields are
specified, as is the case here, it is necessary to provide two separate housings, or
in effect, two separate precipitators. Two housings, connected by lead
ductwork were quoted for both efficiency levels. For plate-type precipitators, a
single casing can house two or more fields.
It should be noted that a single efficiency level was specified for this section.
This efficiency was chosen to protect the sulfuric acid plant and has no
relationship to the level of pollution abatement.
Copper reverberatory furnaces produce an effluent contaminated with
paniculate matter and SC^. Because of the low 862 concentration, the
economics of S02 removal are very unattractive; it is not customary to equip
reverberatory furnaces with sulfuric acid plants. Particulate collection by either
electrostatic precipitator or wet scrubber is common, however.
In this section, specifications are written for precipitators (Tables 106 and 107)
and alternatively for wet scrubbers (Tables 110 and 111). The capital costs
submitted in response to these specifications are given in Table 108 for the
precipitators and 112 for the scrubbers. These costs are plotted in Figures 81
and 83. It is apparent that the first costs for the precipitators are higher than
those for scrubbers regardless of size or efficiency level. However, when
operating costs, listed in Tables 109 and 113 and plotted in Figures 82 and 84,
are taken into account, the positions are reversed.
The costs submitted by the member companies correspond to new or "grass
roots" construction, in which none of the problems of backfitting to an
existing process exist. The same equipment, installed in an old plant, might cost
considerably more because of the greater complexity of ductwork, plot
restrictions, etc.
293
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TABLE 102
COMBINED GAS CLEANING SYSTEM
PROCESS DESCRIPTION FOR COPPER ROASTING FURNACE SPECIFICATION
The gas cleaning system is to serve a group of Herreschoff multiple hearth roasters which
reduce the sulfur content of a chalcopyrite ore concentrate from 32 wt. % sulfur to 20 wt. %
sulfur. The furnaces are equipped with a waste heat boiler which reduces the flue gas
temperature to 40CPF, followed by mechanical dust collectors which effectively remove
dust particles 20 p and larger. The coarse dust is conveyed to the reverberatory furnace for
smelting.
The specification covers two plant sizes. The "small" plant consists of three, one hundred
ton/day Herreschoff 10-hearth roasters operated in parallel. The equipment must be capable
of satisfactory performance at the design flow rates specified, and with one furnace out of
service. The "large"plant consists of four, two hundred ton/day furnaces.
The mechanical dust collector outlet will be located at elevation +40 ft relative to grade. The
air pollution abatement system will begin at this point and will include all of the equipment,
auxiliaries, etc., thru the discharge from the cooling tower. The gases will be piped into a
new sulfuric acid plant by others. The major equipment items include:
1. A scrubbing tower
2. A cooling tower
3. An electrostatic mist precipitator
Each piece of equipment is described in the following paragraphs, and in the table of
operating conditions. The ductwork run from the mechanical collector outlet to the
scrubber inlet is of minimum length, and may be constructed of 316L stainless steel.
Scrubber
A single impingement type (or other suitable non-plugging) scrubber is to be supplied. The
scrubber is to remove paniculate materials and soluble fluoride and chlorides each at
approximately 95% efficiency. Recirculated liquor is to be maintained at approximately 3
wt. % sulfuric acid. Net liquid is to be discharged into the ore concentration unit, from
which it will be recycled into the reverberatory furnace.
The scrubber is to be constructed of type 316L stainless steel or Alloy 20 throughout The
scrubber is to be equipped with a recycle pump suction tank with automatic make-up water
control. Net solids-bearing effluent from the recycle pump discharge is to be maintained by a
density control instrument. Pumps, piping, etc. shall be either type 316L stainless steel or
rubber-lined carbon steel. FRP piping may also be used.
The scrubber is to be equipped with emergency flush water connections, so that the interior
may be washed down with fresh water in the event of recycle pump or general electric power
failure.
294
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Cooling Chamber
The effluent from the scrubber shall pass through a cooling tower designed to reduce the gas
temperature from 140°F to approximately 105°F, and to accomplish an equivalent
reduction in moisture content. The cooling tower shall be constructed of 304L stain/ess
steel. Ceramic saddles or other acid resistant packing material is suitable for this service.
The cooling chamber shall produce an effluent with less than 1 gr/DSCF entrained water.
The cooling chamber shall be complete with fin-tube air cooler operating between 125°F
and 95°F. Provision shall be made to hold the normal circulating water inventory of the
system plus the accumulation of condensate over a 4 hour period. Condensate shall be
discharged into the scrubbing section on automatic control. Pumps shall be acid resistant
construction (either 316L stainless steel or rubber lined carbon steel). All concrete, metal
and other wetted parts shall be able to withstand contact with dilute sulfuric acid of 1/2 of 1
wt.% concentration.
Precipitator
The electrostatic mist precipitator is to be designed for wet acid service. The precipitator is
to collect substantially all of the sulfuric acid mist in the cooler effluent. A t least two fields
must be provided in the direction of gas flow in order to minimize the effect of an electrical
failure. Interconnecting ductwork shall be lead or lead-lined.
Construction is to be acid resistant throughout. Acid concentrations up to 10 wt. % sulfuric
acid must be acceptable at normal operating temperature. The precipitator shall be equipped
with a sump capable of retaining acid mist accumulation for 8 hours.
The precipitator shall be equipped with an electrical interlock system such that no personnel
access to any high voltage equipment can be made without first de-energizing and grounding
all primary circuits. Test ports shall be provided for sampling inlet and discharge gases, and
these shall not be located so as to permit accidental contact with high voltage equipment.
Installation
The contractor shall assume, for the preparation of his installation bid, that there are no
serious space limitations, and that adequacy of soil bearing pressures have been determined
by tests. No unusual physical limitations or access restrictions exist in the area. As this
equipment discharges into the sulfuric acid plant, no stack is required.
295
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TABLE 103
COMBINED GAS CLEANING SYSTEM OPERATING CONDITIONS
FOR COPPER ROASTING FURNACE SPECIFICATION
Furnace feed rate, ton/day
Furnace product ton/day
Process weight, ton/hr
Effluent from furnace
Flow, ACFM
Temp., °F
Gas Composition, vol.
N2 + A
°2
H2O
CO2
SO?
Flow, SCFM
Flow, DSCFM
Solids loading, Ib/hr
Solids loading, gr/ACF
SO3 loading, Ib/hr
SO3 loading, gr/ACF
Outlet from scrubber
Flow DSCFM
Temp., °F
Moisture content, vol. %
Flow, ACFM
Dust loading, Ib/hr
Dust loading, gr/DSCF
Efficiency, %
Gas to cooling chamber
Flow, ACFM
Temp., °F
Moisture, vol. %
Flow, DSCFM
Gas from cooling chamber
Flow, ACFM
Temp., °F
Moisture, vol. %
Flow, DSCFM
Small
395
300
16.8
24,200
500
79.1
3.4
8.9
0.4
8.2
100.0
13.250
12,120
2,060
10
300
1.5
12,120
140
19.5
16,800
100
0.1
95
16JBOO
140
19.5
12,120
14,350
105
9.1
12,120
Large
1,080
800
45
64,000
500
79.1
3.4
8.9
0.4
8.2
100.0
35,000
32,000
5,500
10
825
1.5
32,000
140
19.5
45,000
275
0.1
95
45,000
140
19.5
32,000
37,900
105
9.1
32,000
296
-------
Gas from precipitator
Dust loading, Ib/hr 0.05 0.137
Dust loading, gr/DSCF 0.005 0.005
Dust loading, gr/ACF 0.004 0.004
Dust removal efficiency, % 99.95 99.95
H2 SO4 mist loading, Ib/hr 0.72 2.0
H2S04 mist loading, gr/ACF 0.06 0.06
H2 SO4 mist removal efficiency, % 99.75 99.75
297
-------
TABLE 104
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR COMBINED GAS CLEANING SYSTEM
FOR COPPER ROASTING FURNACE
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. 9
Effluent
gr/ACF Solids
gr/ACF Mist
Cleaned Gas Flow
ACFM
°F
SCFM (Dry)
Moisture Content, Vol. "/
Cleaned Gas
gr/ACF Solids
gr/ACF, Mist
&
f
0
Cleaning Efficiency, % Solids
Mist
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost ^s
(a) Fan(s)
(b) Pump(s)
(c) Damper(s) I
(d) Conditioning, f
Equipment I
(e) Dust Disposal I
Equipment I
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(1) Other J
(4) Total Cost
>
LA Process Wt.
Small
Large
High Efficiency
Small
24,200
500
13,250
8.9
10
2,060
14,350
105
12,120
9-1
0.06
0.72
99.75
183,670
51,600
94,390
329,660
Large
64,000
500
35,000
8.9
10
5,500
37,900
105
32,000
9.1
0.06
2.0
99.75
401,040
93,550
163,705
658,295
298
-------
TABLE 105
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR COMBINED GAS CLEANING SYSTEM
FOR COPPER ROASTING FURNACE
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$*/hr
$.011/kw-h]
J.25/M ga]
LA Process Wt.
Small
Large
High Efficiency
Small
-
780
780
1,750
10,697
4,379
15,076
17,606
32,966
50,572
Large
-
780
780
2,450
22,493
11,096
33,589
36,819
65,830
102,649
-------
CO
oc
CO
Q
I
O
§
FIGURE 79
CAPITAL COSTS FOR COMBINED GAS CLEANING
SYSTEM FOR ROASTING FURNACES
800
600
500
400
300
200
TURNKEY SYSTEM
COLLECTOR PLUS
AUXILIARIES -
COLLECTOR ONLY
100
200
300 400 500 600 800 1000
PLANT CAPACITY, TON/DAY PRODUCT
300
-------
FIGURE 80
ANNUAL COSTS FOR COMBINED GAS CLEANING
SYSTEM FOR ROASTING FURNACE
o
Q
V)
O
I
O
X
CO
O
CJ
80
60
50
40
30
20
10
TOTAL COST
(OPERATING COST
CAPITAL CHAR(
OPERATING
r c
r PLUS X
3ES)
COST /
_>
X
X
y
tX
>
X
x
X
^
/
;
\
s
200 300 400 500 600 800 1000
PLANT CAPACITY, TON/DAY PRODUCT
301
-------
TABLE 106
ELECTROSTATIC PRECIPITATOR PROCESS DESCRIPTION
FOR COPPER REVERBERATORY FURNACE SPECIFICATION
The precipitator is to serve a pair of reverberator/ furnaces in each case. Two sizes and two
efficiency levels are specified. These should be considered as completely independent
specifications and four separate quotations should be prepared.
In each case, the reverberatory furnaces process green concentrate plus several recycled
materials such as flue dust and precipitate from other operations. The furnaces are equipped
with a waste heat steam generator and a mechanical dust collector which effectively removes
all particulate material larger than 20 y in diameter. The flue duct is carried outside the
smelting building wall at elevation +40 ft relative to grade. The precipitator, ID fan and stack
are to be installed in an area without encumberances adjacent to the building at this point.
The precipitator is to remove the particulate matter to the degree specified during normal,
sustained operation.
Provisions must be made for collecting and storing within the hoppers the dust generated
during an 8 hour period. Hoppers shall be equipped with screw conveyors for continuously
removing the dust for discharge onto a closed belt conveyor for return to the concentration
plant, or shipment to a refining plant.
A single precipitator casing shall be supplied. Sectionalization of the precipitator shall be
sufficient to allow operation at greater than 90% efficiency with any one section out of
service. In each case it shall be assumed that a 100 foot stack will be provided as apart of
the furnace contract, and that the precipitator contractor must tie into this duct.
302
-------
TABLE 107
ELECTROSTATIC PRECIPITATOR OPERATING CONDITIONS
FOR COPPER REVERBERATORY FURNACE SPECIFICATION
Four separate quotations should be prepared for the following conditions:
Small Large
Product (matte) production, ton/day
(total for both furnaces!
Charge Materials, ton/day
Green Concentrate (30% Cu, dry basis)
Copper Precipitate
Fluxes
Flue Dust
Converter Slag
Gas Fuel Fired, SCFM
Process Weight, ton/hr
Effluent from Steam Generator
Pressure, inches w.c.
Flow, SCFM
Temp., °F
Flow, ACFM
Composition, Mol %
co2
"2°
SO,
Solids loading, Ib/hr
Solids loading, gr/ACF
400
560
20
60
6
220
886
3,000
37
-6
52,000
600
104,000
77.6
6.1
9.8
4.9
1.6
100.0
2,700
3.0
1,000
1,400
50
150
15
550
2,165
7,500
92.5
-6
130,000
600
260,000
77.6
6.1
9.8
4.9
1.6
100.0
6,800
3.0
Outlet loading, Ib/hr
Outlet loading, gr/ACF
Efficiency, Wt. %
Case 1 — Medium Efficiency
40
0.045
98.5
40
0.018
99.4
Outlet loading, Ib/hr
Outlet loading, gr/ACF
Efficiency, Wt. %
Case 2 — High Efficiency
13.4
0.015
99.5
33.4
0.015
99.5
303
-------
TABLE 108
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR ELECTROSTATIC PRECIPITATORS FOR COPPER
REVERBERATORY FURNACES
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost >
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other )
>
>
(4) Total Cost
LA Process Wt.
Small
104,000
600
52,000
4.9
3.0
2,700
104,000
600
52,000
4.9
.045
40
98.5
175,510
52,470
206,887
434,867
Large
260,000
600
130,000
4.9
3.0
6,800
260,000
600
130,000
4.9
.018
40
99.4
395,895
91,712
385,206
872,813
High Efficiency
Small
104,000
600
52,000
4.9
3.0
2,700
104,000
600
52,000
4.9
.015
13.4
99.5
221,037
55,633
269,923
546,593
Large
260,000
600
130,000
4.9
3.0
6,800
260,000
600
130,000
4.9
.015
33.4
99.5
401,312
93,810
409,587
904,709
304
-------
TABLE 109
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS
FOR COPPER REVERBERATORY FURNACES
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8^600
$6/hr
$8/hr
$6/hr
'.OU/kw-hr
LA Process Wt.
Small
1,050
105
1,155
575
500
1,075
4,250
3,443
3,443
9,923
43,487
53,410
Large
1,050
105
1,155
575
500
1,075
7,500
6,831
6,831
16,561
87,281
103,842
High Efficiency
Small
1,050
105
1,155
575
500
1,075
5,250
3,443
3,443
10,923
54,659
65,582
Large
1,050
105
1.155
575
500
1,075
7,500
6,831
6,831
16,561
90,461
107,022
o
CJ1
-------
FIGURE 81
CAPITAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR COPPER REVERBERATORY FURNACES
V)
oc
<
O
Q
LL
O
VI
O
I
&
O
o
1000
800
600
500
400
300
200
100
-TURNKEY SYSTEM
COLLECTOR PLUS AUXILIARIES
I ,
COLLECTOR ONLY
200 300 400 500 600 800 1000
PLANT CAPACITY, TON/DAY
306
-------
FIGURE 82
ANNUAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR COPPER REVERBERATORY FURNACES
100,
80
TOTAL COST
60
1
Vi
cc.
O
Q
O
O
O
50
(OPERATING COST PLUS
_ CAPITAL CHARGES)
40
30
20
10
OPERATING COST
i I
200 300 400 500 600
PLANT CAPACITY, TON/DAY
800 1000
307
-------
TABLE 110
WET SCRUBBER PROCESS DESCRIPTION
FOR COPPER REVERBERATORY FURNACE SPECIFICATION
The scrubber system is to serve a pair of reverberatory furnaces in each case. Two sizes and
two efficiency levels are specified. These should be considered as completely independent
specifications and four separate quotations should be prepared.
In each case, the reverberatory furnaces process green concentrate plus several recycled
materials such as dust and precipitate from other operations. The furnaces are equipped with
a waste heat steam generator and a mechanical dust collector which effectively removes a/I
paniculate matter larger than 20 y in diameter. The flue duct is carried outside the smelting
building wall at an elevation +40 ft relative to grade. The scrubber, ID fan and stack are to
be installed outside in an area without encumberances adjacent to the building at this point.
The settling and filtering equipment to provide for a completely closed water system must
also be located in an area adjacent to the smelting building, about 100 ft away from the flue
duct exit.
The scrubber is to remove the paniculate matter to the degree specified, and provide the
recovered fines as a semi-dry solid containing no more than 40% moisture by weight. This
material is to be returned by conveyor to the concentration plant. The vendor is to furnish
the following items:
(1) Scrubber
(2) Reheat burner
(3) Fan
14) Settling pond or clarifier
(5) Filter
(6) Necessary ductwork, piping, pumps, controls, etc.
(71 200 ft stack for SO2 dispersion
All of the wetted equipment shall be constructed of type 316L stainless steel, rubber, or
other acid resistant materials. Installation and freeze protection suitable for -20°F operation
shall be provided as required. The scrubber — fan combination shall be capable of operation
without exceeding the specified discharge weight at gas flows as low as 50% of the design
rates specified. Adequate controls are to be provided to maintain a constant 0.5 inches w.c.
draft at the steam generator inlet with gas flows between 50 and 110% of the normal flow
specified.
A natural gas reheat burner to reheat the scrubber effluent approximately 100°F shall be
provided to protect the fan, ductwork and stack from corrosion, and to provide for steam
plume dissipation.
308
-------
TABLE 111
WET SCRUBBER OPERATING CONDITIONS
FOR COPPER REVERBERATORY FURNACE SPECIFICATION
Four separate quotations should be prepared for the following conditions.
Small Large
Product (matte) production, ton/day
(total for both furnaces)
Charge Materials, ton/day
Green Concentrate
Copper Precipitate
Fluxes
Flue Dust
Converter Slag
Gas fuel fired, SCFM
Process weight, ton/hr
Effluent from Steam Generator
Pressure, inches w.c.
Flow, DSCFM
Temp., °F
Flow, ACFM
Composition, Mol %
4
C02
SO,
Effluent from Scrubber
Pressure, psia *
Flow, DSCFM
Temp., °F
Flow, ACFM
Moisture, Vol. %
SO2, Vol. %
Reheat Burner
Duty, MM BTU/hr
Gas usage, SCFM
Air Usage, SCFM
Effluent from Fan
Pressure, psia
Flow, DSCFM
Temp., °F
Flow, ACFM
Moisture, Vol. %
SO2, Vol. %
400
560
20
60
6
220
886
3,000
37
-6
49,500
600
104,000
100.0
13.7
49,500
137
75,000
20
1.35
7.5
124
1,240
14.7
50,740
250
85,000
23.5
1.3
1,000
2,165
7,500
92.5
-6
124,000
600
260,000
100.0
13.7
124.000
137
187,000
20
1.35
18.5
310
3,100
. 14.7
127,400
250
213,000
23.5
1.3
*Vendor should specify actual scrubber inlet pressure and pressure drop required.
309
-------
Small Large
Paniculate Loading to Scrubber
Ib/hr 2,700 6,800
gr/DSCF 6.35 6.35
gr/ACF 3.00 3.00
Case 1 — Medium Efficiency
Outlet loading, Ib/hr 40 40
Outlet loading, gr/DSCF at fan discharge 0.092 0.037
Outlet loading, gr/ACF at fan discharge 0.055 0.022
Efficiency, wt % 98.5 99.4
Case 2 — High Efficiency
Outlet loading, Ib/hr 11.0 28.4
gr/DSCF at fan discharge 0.025 0.025
gr/ACF at fan discharge 0.015 0.015
gr/DSCF at scrubber outlet 0.026 0.026
gr/ACF at scrubber outlet 0.017 0.017
Efficiency, wt % 99.6 99.6
310
-------
311
-------
TABLE 112
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR
COPPER REVERBERATORY FURNACES
Effluent Gas Flow
ACFM
°F
SCFM- Dry
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s) $ Motors
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost ">
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other J
*
(4) Total Cost
LA Process Wt.
Small
104,000
600
49,500
4.9
3
2,700
85,000
250
50,740
23.5
0.055
40
98.5
38,750
50,000
2,400
4,000
28,500
32,500
50,000
206,150
Large
260,000
600
124,000
4.9
3
6,800
213,000
250
127,400
23.5
0.022
40
99. n
68,000
150,000
8,000
7,500
51,000
73,000
85,000
442,500
High Efficiency
Small
104,000
600
49,500
4.9
3
2,700
85,000
250
50,740
23.5
0.015
11.0
99.6
38,750
71,000
2,400
4,000
28,500
32,500
63,000
240,150
Large
260,000
600
124,000
4.9
3
6,800
213,000
250
127,400
23.5
0.015
28.4
99.6
68,000
200,000
8,000
7,500
51,000
73,000
104,000
511,500
Based on one quote.
312
-------
TABLE 113
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR
COPPER REVERBERATORY FURNACES
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$.011/kw-l
$ 0.80/MMBT
LA Process Wt.
Small
-
-
r 59,400
I 40,400
99,800
99,800
20,615
120,415
Large
-
-
89,100
99,200
188,300
188,300
44,250
232,550
High Efficiency
Small
-
-
198,000
40,400
238,400
238,400
24,015
262,415
Large
-
-
244,200
99,200
343,400
343,400
51,150
394,550
CO
CO
Based on one quote.
-------
FIGURE 83
CAPITAL COSTS FOR WET SCRUBBERS FOR
COPPER REVERBERATORY FURNACES
(HIGH EFFICIENCY)
V)
cc.
(A
Q
<
CO
O
X
CO
O
u
800
600
500
400
300
200
100
COLLECTOR
TURN KEY SYSTEM
COLLECTOR PLUS AUXILIARIES
V 50
ji5 40
100
80
60
30
20
200
300 400 500 600 800 1000
PLANT CAPACITY, TON/DAY
314
-------
FIGURE 84
ANNUAL COSTS FOR WET SCRUBBERS
COPPER REVERBERATORY FURNACES
(HIGH EFFICIENCY)
CO
cc
§
LL
O
V)
Q
Z
O
X
8
O
600
500
400
300
200
100
TOTAL COST
(OPERATING COST* PLUS
CAPITAL CHARGES)
OPERATING COST
200 300 400 500 600 800 1000
PLANT CAPACITY, TON/DAY
*This does not include operating labor, maintenance labor or repair parts costs.
315
-------
REFERENCES
1. Tseidler, Aleksandr Albertovich, Metallurgy of Copper and Nickel,
Jerusalem, Israel Program for Scientific Translations, 1964 (original in
Russian)
2. Standen, Anthony, Kirk-Othmer Encyclopedia of Chemical Technology,
2nd Edition, Interscience Publishing Co., New York, 1968
3. Butts, Allison, Copper: The Science and Technology of the Metal, Its
Alloys and Compounds, Reinhold, New York, 1954
4. Semarau, Konrad T., "Control of Sulfur Oxide Emissions From Primary
Copper, Lead and Zinc Smelters", J. Air Pollution Control Association,
April, 1971. p. 185-194
5. Blair, J. C., "Fluo Solids Roasting of Copper Concentrate at Copperhill",
Journal of Metals, Volume 18, Number 3, March, 1966
6. Donovan, J. R. and P. J. Stuber, "Sulfuric Acid Production From Ore
Roaster Gases", Journal of Metals, November, 1967, p. 45-50
316
-------
2
71
*
00
O
m
3
CO
-------
8. KRAFT MILL BARK BOILERS
Bark is a byproduct waste of the Kraft mill and ever since the first log was cut
for the production of wood chips or lumber, disposal of this waste has been a
problem. Bark is one of the most difficult fuels to burn. It normally has a
moisture content of 50% or greater and a heating value of only 7600 to 9600
BTU/lb on a dry basis, depending on wood type. It contains a significant
amount of sand, ash and other non-combustible materials, and it is difficult to
prepare, handle and properly distribute. Because of its high moisture content it
requires more time and higher temperatures for combustion than conventional
fuels. On a dry basis, bark has a volatile content approaching 80 percent by
weight.
The application of modern bark boilers in the Kraft mill is one of the most
economical refuse or byproduct disposal methods in industry. The major
breakthrough came in the mid-40's with the development of the spreader
stoker which offered a much more efficient method of burning than the earlier
"Dutch-oven" type furnaces. A modern bark boiler, in conjunction with the
other heat and chemical recovery units, can supply all the steam requirements
of the mill.
PROCESS DESCRIPTION
While this narrative will concentrate on the bark boiler and related firing and
handling equipment, it will also consider the influence of the wood yard area
and the dust collection and ash handling equipment. On this basis, the bark
handling system in a paper mill can be divided into:
1. Bark handling in wood yard
2. Bark boilers
3. Dust collection
Figure 85 gives a schematic representation of the bark flow in the above areas.
The quality of the bark is partially determined before it arrives at the wood
yard and its ash content and moisture content initially depend on handling
technique and location. Dry-handled logs, grown in areas of sandy soil such as
the east and southeast coast and the state of Michigan, have ash contents which
range from 3 to 7 percent.111 Logs that have been transported over water,
flume handled, or hydraulically debarked, in general, have lower ash contents.
317
-------
LUMBER
SAW MILL
AREA
oo
00
LOGS
FLUE GAS
AIR
HEATER
SCRUBBER
OR
PRECIPITATOR
1.0. FAN
DEBARKER
LOGS FROM
WOOD YARD
OPTIONAL
HOGGING
I 1
MECHANICAL
COLLECTOR
, r
1 L
FIER
Y CARBON
INJECTION
^ *-
t
BOILER
1
r
BAR
FUE
O_
1
AND
V7
_D
FUEL FEED AND
DISTRIBUTOR CHUTE
FIGURE 85
BARK FLOW DIAGRAM
-------
This is due to the washing effect which removes most of the sand and dirt,
causing the ash content to drop to the range of 1/2 to 2%. Also, hardwood
barks have an ash content about twice that of softwood barks which have
received the same processing.
The first processing step takes place in the wood yard and consists of
continuous and automatic debarking of the logs to be used by the Kraft process
or for lumber. The debarking is accomplished in a variety of methods which
utilize natural or mechanical friction. In the most commonly used method, logs
are fed into the upper end of a rotating drum and debarking results from the
abrasion of one log upon another. Hydraulic debarkers are also used and
employ high pressure water jets against the logs in such a way as to break up
and remove the bark. Typical moisture content of bark and wood for different
types of handling is given in Figure 86(1'.
The second processing step, which also takes place in the wood yard, is bark
hogging. This consists of feeding the various sizes of bark from the debarking
operation through a disintegrator or "hog" to produce a uniform size bark
chip. Bark hogging adds to the cost of processing, and is not always employed.
In some mills the bark from the debarker is screened and only the oversized is
hogged. In general, however, most new plants do use hogged bark, since it can
be handled more easily and fired more efficiently. Boiler operation is also more
reliable and the burning equipment maintenance is reduced.
Typical bark sizes for different types of firing are shown below.121
% Retained on Screen
Screen Unhogged Bark Hogged Bark
Size, in. Stoker-Fired Stoker-Fired Suspension-Fired
4x4 0 -
2x2 50
3/4x3/4 - - 0
1/4 x 1/4 — 50 minimum 50 maximum
After hogging, the bark is conveyed to a surge bin or storage facility sized to
allow for one to two hours of boiler firing at maximum capacity. In some cases,
for economic considerations, the bark is conveyed directly to the boiler
without surge capacity but this makes boiler control much more difficult and
tends to result in less efficient operation.
Conveying, distributing and proportioning of the bark to the boiler feeding
device are the final operations prior to burning. It is of importance to good
319
-------
FIGURE 86
MOISTURE CONTENT OF BARK AND WOOD
Kiln
Dried
Air
Dried
Drum Barked
Dry Handled
Drum Barked
Wet Handled
Hydraulic
Barked
10
20
30
40 50 60
PERCENT MOISTURE
70
80
-------
boiler control and a difficult and troublesome operation. A well operating
conveyor system should insure a continuous non-pulsating feed and uniformly
proportion the fuel to each of the boiler chutes. A variety of devices are in use
which include belt conveyors, pneumatic conveyors and vibrating conveyors.
Final distribution of the bark is accomplished from the individual boiler chutes
with either a pneumatic or mechanical distributor. The mechanical distributor
consists of a rotating cylinder with arms that throw the bark over the furnace
grates. Pneumatic distribution is accomplished with an air swept spout
distributor which employs a rotary air damper to alternately increase and
decrease both the air quantity and pressure several cycles per minute. Both
types of distributors can satisfactorily burn hogged bark, but some mechanical
distributors have a tendency to become plugged on stringy or unhogged bark.
For hogged bark, the distributors can be placed about three feet above the
boiler grate while for unhogged bark they must be elevated to about 12 ft to
assure good distribution.11' This results in less residence time for portions of
the bark and a decrease in boiler efficiency.
In general, bark boilers can be divided into two ranges of size, less than
150,000 Ib/hr of steam and 150,000 to 800,000 Ib/hr of steam. For the larger
size boilers, there are three main types of burning equipment: stoker (traveling
grate or water cooled sloping grate), suspension firing, and cyclone firing. For
the smaller size furnaces a greater variety of stoker grates are used such as
dump grates, water-cooled pinhole grates, stationary air-cooled grates and
vibrating grates. Pile burning is also used in the smaller size boilers.
Within a given size range, the type of burner equipment used is also affected by
the size, moisture and ash content of the bark, and the type and requirements
for auxiliary fuel, if any.
The general effect of bark moisture on boiler efficiency is shown in Figure
87.
Bark with a moisture content between 55 and 65% is normally pile burned in a
refractory-lined furnace. In this type of burning the major burning area supplies
enough heat for evaporation of moisture from the surrounding bark so that the
overall combustion is self-sustaining without the need of auxiliary fuel. Stokers
generally are limited to a bark with a maximum moisture content of 55%. To
burn a higher moisture bark, auxiliary fuel may have to be supplied.
Of the three major types of firing equipment, cyclone furnaces have the least
application for bark burning. They are limited to a maximum bark input of
30% of the total fuel value and require a finely hogged bark, 100% through 3/4
inch mesh, for proper burning. They also require, as the primary fuel, a lower
321
-------
CO
ro
10
80
70
s?
>
£ 60
UJ
U
LL
U-
LU
CC
"J 50
5
03
40
"^^^
"^•^^
V
s,
N
X.
\
\
\
\
\
\
20 30 40 50 60
MOISTURE IN BARK, WT. %
FIGURE 87
THE EFFECT OF BARK MOISTURE ON BOILER EFFICIENCY
70
-------
ash fusion coal to provide a slag coating around the cyclone and insure proper
burning of the bark. From an air pollution control standpoint, this type of
furnace can be considered as a coal-fired boiler for equipment design purposes.
Another type of boiler that, as yet, has had limited application, is the
suspension-fired boiler which is similar to a pulverized coal fired boiler. This
type of boiler requires finely hogged bark to assure that the bark will burn in
suspension. Most boilers also employ a small dump grate to burn the large bark
particles which do not burn in suspension and might otherwise fall into the
dust hoppers only partially burned. The bark is conveyed to the boiler with
either hot or cold air. Most of these units have a maximum heat input from
bark ranging between 30 and 50% and require supplementary fuel. Gas or oil
are the auxiliary fuels normally used, but coal can also be used when provided
for in the design. From an overall cost standpoint, suspension-fired boilers are
not as economical as stoker-fired units until the bark percentage of total fuel
drops below 30 percent. They are not a dominant factor in bark boilers and the
associated air pollution problems.
Most bark boilers have spreader stoker firing equipment and burn the bark on
the grate in a thin layer. The most popular type of stoker is the traveling grate
stoker. It is ideally suited for areas with high ash content bark, since it provides
for continuous ash discharge. It can also better compensate for bad bark
distribution than can a dump grate stoker. Because of this, it requires less grate
area and results in a smaller physical size boiler. Fixed position, water-cooled,
pin hole grate stokers are also used. They are used primarily for burning bark
with a low ash and sand content. They are available in a sloped grate or manual
rakeout type, although the manual rakeout type is limited to the smaller size
and used only with low ash and sand bark. The sloped grate boiler has the
advantage of no moving parts. The flow of fuel and ash over the grates is
controlled by steam jets and the ash is discharged to the ash hoppers. The
major problem with the water-cooled grate stoker is fusion of the fuel ash over
the grate. Even distribution of the bark over the stoker is a must to prevent
formation of small bark piles and high grate temperatures. The air temperature
to the boilers is also normally limited to around 450°F.
NATURE OF GASEOUS DISCHARGE
The discharge from a bark boiler consists of gaseous products of combustion
containing particulate bark char, and sand. Unlike most other stacks in a Kraft
mill, there are no significant gaseous air pollutants emitted, and, unlike most
coal-fired boilers, there is not an S02 problem, since there is little or no sulfur
in the bark. In general, the composition of boiler exhaust gas will be typical of
the exhaust composition of most coal-fired power boilers. It will have a higher
323
-------
moisture content and lower ash content which will vary widely depending on
the type of bark fired.
The quantity of the gaseous exhaust depends primarily, of course, on the size
of the boiler. For a given sized boiler firing 100% bark (no auxiliary fuel), the
quantity varies with boiler efficiency, bark moisture content, bark sand and ash
content, ash reinjection requirements, and excess air requirements. A 1,000
ton/day unbleached Kraft mill processing only unbarked pine would produce
about 560 tons of bark per day or 12% of the total 4,600 tons of logs handled
each day. Assuming a moisture content of 45%, an ash content of 1-1/2%, an
excess air requirement of 20%, and a heating value on a dry basis of 9,000
BTU/lb, the exhaust gas composition and volume would be as shown in Table
114,
PARTICULATE CONTAMINANTS
The paniculate carried in the boiler exhaust gas consists of two separate and
distinguishable materials: sand and bark char or flyash. These two particulate
materials have quite different physical properties and can be expected to
behave differently in the carrier gas and air pollution abatement equipment.
There is a strong incentive to recover each of these materials for reasons other
than air pollution control.
The bark flyash, unlike most flyash, is primarily unburned carbon and, with
collection and reinjection, can increase boiler efficiencies from 1 to 4%. Its
physical properties are also quite different from normal flyash. It has a low
specific gravity, 0.15 to 0.5, and a large surface area to particle mass ratio.(3> It
is very fragile and difficult to sample and analyze. A typical size distribution
curve is given in Figure 88. Because of its irregular shape, as compared to
most typical solid spherical particulate, its reaction to gas stream turbulence
and changes in direction Is more pronounced.
The sand particulate, on the other hand, is more representative of normal solid
spherical particulate. It is finely divided and highly abrasive and can cause
serious boiler erosion problems. Because of this problem, velocities through
bark boilers and economizers handling sandy flyash are limited to help prevent
tube erosion. Single pass boilers are used almost exclusively. Separation of sand
from the char, if reinjection is being used, is also required to help minimize
boiler and particulate collection equipment damage due to sand erosion.
The dust loading of boiler exhaust gases varies over a wide range. Table 115A
Summary of Tests on Bark Boiler Collectors, shows loading from 0.5 to 4.0
324
-------
FIGURE 88
PARTICLE SIZE DISTRIBUTIONS OF
BARK BOILER FLYASH
I
o
a:
m
o_
O_
O
uf
N
20
30
40
1000y
— 100 u
10 y
% UNDER BY WEIGHT
325
-------
TABLE 114
EXHAUST GAS COMPOSITION
Gas Flow, SCFM 54,900
Temperature, °F 400
Gas Flow, ACFM 91,000
Estimated Composition, Mol. %
N2 68.4
C02 11.5
02 3.0
H20 17.1
Total 100.0
Dust Loading
Lb/Day 16,200
Lb/103 Ib of Gas 2.73
Lb/106 BTU 2.91
Gr/SCFM 1.43
326
-------
TABLE 115
SUMMARY OF TESTS ON BARK BOILER TUBULAR COLLECTORS(6)
Number of tubes
Design, frVmin
Design temperature, °F
Design draft loss, in. water gage
Type of fuel
Rated steam load, Ib/hr
Bark
Bark and auxiliary fuel
Auxiliary fuel
Steam load, Ib/hr
Actual oper. temp., °F
Actual oper. draft loss, in. water gage
106Btu/hr fired
Max. rated Ib/hr of bark
Volume
ACFM, inlet
SCFM, inlet
Dust loading
Inlet, Ib/day
Outlet, Ib/day
Inlet, lb/103lb gas
Outlet, lb/103 Ibgas
Inlet. lb/106Btu
Outlet, lb/106 Btu
Grain loading, grains/std. ft3/min
Inlet
Outlet
Efficiency of collection, %
Louisiana
204
152,530
500
2.73
Bark & Gas
150,000
150,000
165,000
200,000
150,000
460
228
54,700
150,190
85,323
60.120
4.096
6.797
0.497
10.98
0.75
3.426
0.242
93.19
Tennessee
285
215,000
725
2.5
Bark, Gas,
and Oil
300,000
340,000
270,000
738
408
60,000
267,181
119,911
93.432
7.464
7.566
0.606
9.54
0.76
3.788
0.3027
92.19
Florida
No. 1
384
230,000
450
2.5
Bark & Oil3
300,000
300,000
420
3.0
457
222,713
134,000
13.940
1.056
1.029
0.0707
1.29
0.0965
0.5056
0.0343
93.36
Florida
No, 2
384
230,000
240
2.5
Bark & Oilb
300,000
268,000
410
2.5
407
188,510
1 14,800
20.799
1.455
1.804
0.1052
2.13
0.149
0.8805
0.05286
94.12
South
Carolina
344
293,000
679
3.0
Bark& Oil
300,000
300,000
455^125
3.5
457
241,618
139,500
47.902
3.509
3.376
0.2658
4.36
0.317
1.6688
0.13018
92.25
Alabama
340
297,542
725
3.0
Bark & Gas
300,000
300,000
640
2.0
457
279,000
133,613
77.592
5.718
5.92
0.513
7.07
0.52
2.8055
0.2345
91.64
GJ
PO
35% Bark hardwood; 65% oil.
b79% Bark pine; 21% oil.
-------
gr/SCFM.(3) The loading increases exponentially as the boiler load increases,
due primarily to increased char production. Sand loading also increases, but to
a lesser degree, since it is directly related to bark feed rate and sand content of
the bark feed. Due to the large increase in char production, the size also
increases. Reinjection of collected ash also significantly increases the dust
loading. This is graphically illustrated in Figures 89 and 90.
Since the objective of the reinjection is to reburn the collected char, the
increase in dust loading is due primarily to an increased sand load. This, in turn,
decreases the particle size distribution due to the finer particles that are
developed by attrition. This effect is illustrated in Figure 88.
POLLUTION CONTROL CONSIDERATIONS
It has been estimated (NAPCA Contract CPA 22-69-104) that pulp mill bark
boilers emitted a total of 82,000 tons of paniculate annually after application
of existing air pollution control techniques. At present, most bark boilers are
equipped with multi-cyclone mechanical collectors. Collection efficiencies for
this type of control range from 85 to 95 percent.
At present, bark boiler emissions are more affected by the various process
operations than they are by the application of air pollution control equipment.
Boiler design, auxiliary equipment design, bark handling techniques and
equipment operation all have a significant effect. The most predominant effect
by far, however, is the type and amount of flyash reinjection.
The primary purpose of a reinjection system is to assist in the disposal of the
bark char without affecting boiler reliability or stack particulate emissions. As
shown on Figures89 and 90 it is not possible to eliminate this solid waste
disposal problem without increasing the air pollution emissions. The net effect,
however, is a decrease in total waste. Reinjection also has the advantage of
increasing boiler efficiency. It can raise it as much as 4% on a boiler firing 100%
bark.111
The disadvantage to reinjection, especially when firing bark with a high sand
content, is high dust loading in the boiler gases, which results in increased
boiler tube wear and higher stack emissions. This can be compensated for by
the use of sand separators or decantation type dust collectors. In a decantation
type collector, the fine particles are separated from the larger bark fly carbon.
The bark fly carbon is reinjected to the boiler and the fines are reinjected to
the ash pit. The more common method of sand-char separation is accomplished
with a screening device. The most common devices are rotary drum screens.
328
-------
Q
ill
O
LLJ
LLJ
cc
i
a
cc
O
u
o
o
LU
O
cc
100 i
80
60
40
20
40 80 120 160 200 240
EMISSION RATE, LB FLYASH/HR
280
320
CO
N>
CO
FIGURE 89
DUST LOADING OF BOILER EXHAUST GASES
-------
cc
I
CO
_I
tiT
cc
Q
U
CO
5
z
Q
CO
u.
LU
CC.
1800
1600
1400
1200
1000
800
600
400
7
Total Reinjection
Partial Reinjection
250
300
STEAM FLOW, M LB/HR
FIGURE 90
TOTAL REFUSE EMISSION RATES
350
330
-------
sloped vibrating screens and horizontal vibrating conveyors. The amount of
separation of sand and char varies primarily with the screen mesh size used. It is
possible on a 30 mesh screen to produce a sand containing no char.131 It is also
possible to remove all the char from stack emission by reinjection if the boiler
is using a high efficiency collector which is in good operating condition.
Operation in this fashion leads to the maximum rate of stack emission, and the
mechanical collector becomes a piece of process equipment rather than a piece
of air pollution control equipment.
The ideal approach to air pollution control for bark boilers is operation in the
fashion just described, with the addition of a more efficient piece of air
pollution control equipment on the mechanical collector outlet gases. It may
be possible, depending on the sand and dirt content of the bark, to eliminate
the need for sand-char screening prior to 100% reinjections.
The pollution control requirements used in this study limit the emission rates
from boilers as outlined below:
SIZE SMALL LARGE
Steam Rate, Ib/hr 100,000 300,000
Bark Feed, Ib/hr 21,000 63,000
Exhaust Volume, ACFM 74,000 222,500
Medium Efficiency
Ib/hr 16.79 40
gr/ACFM 0.038 0.021
High Efficiency
gr/ACFM 0.040 0.040
As can be seen from the above listing, the medium efficiency requirement is
more stringent than the high efficiency or clear stack requirement, and in both
cases, they are more stringent than any of the mechanical collector outlet grain
loadings outlined in Table 115.
Wet Scrubbers
Wet scrubbers are easily capable of providing the collection efficiency required
by the process weight limitation, or of producing a clear stack. There are no
requirements for absorption of gaseous pollutants and the particulate should be
easily collectable with a low pressure drop Venturi scrubber. Based on the
331
-------
particle size distribution presented in Figure 4 and assuming 100% reinjection,
a Venturi pressure drop between 6 and 10 inches w.c. should be adequate.
There is no sulfur in the bark fuel and most boilers use natural gas as the
auxiliary fuel. Corrosion problems in these cases will be minimal, and discharge
of the scrubbing water to the sewer system without neutralization should be
permissible. The particulate should be removed first, of course, in either a
settling pond, mechanical settler or drum-type filter. This is required to limit
water consumption and to minimize water pollution problems. If sulfur bearing
auxiliary fuels such as fuel oil or coal are used, it will probably be necessary to
add an alkaline material to neutralize the sulfurous acid (h^SC^) formed to
minimize corrosion and discharge of acidic water to the system sewer.
Collection of SC^ may be required if a high sulfur auxiliary fuel is used.
Reheating of flue gases may be required to limit the steam plume formed where
wet scrubbers discharge into the atmosphere.
Electrostatic Precipitation
Electrostatic precipitators have been successfully employed to obtain high
particulate removal efficiencies on bark boiler flue gas. Because of their high
minimum capital cost, they tend to be non-competitive on small boilers. In
many cases, the boiler sizes will be large enough to make a precipitator
installation economical. However, the optimum performance is obtained while
collecting dust within a narrow band of electrical resistivity. On a bark boiler
using 100% reinjection, the resistivity of the remaining sand and flyash is likely
to be quite high. This can be compensated for in the precipitator design, but
leads to an abnormally large precipitator or requires the addition of chemical
conditioning agents. Both of these substantially increase the capital and
operating costs of the precipitator. Precipitators will likely find limited use in
this application.
Fabric Filters
Fabric filters could also be applied to this problem. The disadvantages involved
in their use cannot be justified by the air pollution control requirements for
this process. The disadvantages are:
1. Danger of boiler shutdown due to loss of bags from high boiler outlet
temperatures and extraordinary operating cost for bag replacement
and lost production.
332
-------
2. Danger of boiler shutdown due to blinding of bags from
condensation at low boiler outlet temperature.
3. High operating cost for bag replacements under normal operating
conditions.
The air pollution control requirements can be adequately and more safely
satisfied by either a wet scrubber or electrostatic precipitator.
SPECIFICATIONS AND COSTS
Bark boiler gas cleaning specifications for both electrostatic precipitators
(Tables 116 and 117) and wet scrubbers (Tables 120 and 121) are given in this
section. In both cases, the specifications are written for 100% reinjection of the
mechanical collector catch.
Because the ash is relatively coarse, the LA-process weight case requires a
higher gas cleaning efficiency than does the "high efficiency" case. For this
reason, a single level, expected to produce a clear, or nearly clear, stack
discharge was specified. It should be noted that historical "clear stack"
emission levels may have been based on <100% reinjection.
The costs submitted show a first cost advantage for wet scrubbers, even though
a relatively elaborate gas reheating system was included in the specification.
These costs are given in Tables 118 and 122. When operating costs are taken
into account, they are nearly equivalent. These are given in Tables 119 and
123. Plots of the capital and operating cost data are given in Figures 91, 92, 93
and 94.
333
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TABLE 116
ELECTROSTATIC PRECIPITATOR PROCESS DESCRIPTION
FOR KRAFT MILL BARK BOILER SPECIFICATION
A single electrostatic precipitator is to treat the flue gas from a conventional spreader stoker
fired boiler. The boiler is equipped with a mechanical collector which serves as the initial
collection device for the bark char and sand. 100 percent of the collected bark char is
reinjected to the boiler after screening on a 30 mesh sloped vibrating screen. Thirty percent
of the initial ash content of the bark is removed in the screening operation while the other
70 percent eventually escapes from the mechanical collector with the outlet gases. The
mechanical collector and sand classifying and handling equipment are not to be supplied by
the vendor.
The exhaust gas will be brought from the existing mechanical collector to a point 20 feet
outside the building and 60 feet above grade. The precipitator will be located at grade in area
at the termination of the duct work and the area is free of space limitation. Duct work is
also to be supplied to an existing ID fan which is connected to an existing 150 ft stack.
The precipitator is to continuously reduce the paniculate content of the flue gas leaving the
bark boiler to the levels specified. A minimum of two fields in the direction of gas flow must
be provided to reduce the effect of an electrical failure.
The precipitator must be equipped with hoppers capable of retaining the dust collected over
24 hours of normal operation. During normal operation the hoppers will be emptied by a
screw conveyor discharging into a dust bin, with a 15 ft elevation above grade to allow for
truck loading. The storage bin will be located adjacent to the precipitator and will be sized
for seven days storage capacity. Automatic voltage control shall be provided to maximize
operating efficiency. Rappers shall be adjustable both as to intensity and rapping period. The
precipitator shall be equipped with a safety interlock system which prevents access to the
precipitator internals unless the electrical circuitry is disconnected and grounded.
A model study for precipitator gas distribution will be required. The precipitator dust
handling equipment and auxiliaries are also to be included in the vendors proposal.
334
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TABLE 117
ELECTROSTATIC PRECIPITATOR OPERATING CONDITIONS
FOR BARK BOILER SPECIFICATION
Two sizes of electrostatic precipitators are to be quoted for one efficiency level. Vendors'
quotation should consist of two separate and independent quotations.
Rated steam load. Ib/hr
Process weight bark feed, Ib/hr wet
Moisture content, wt. %
Ash content, wt. %
Excess air rate, %
Gas to mechanical collector
Flow, SCFM
Flow, ACFM
Temp., °F
% moisture
Inlet loading, Ib/hr
Outlet loading, Ib/hr
Collector efficiency
Gas to electrostatic precipitator
Flow, ACFM
Temp., °F
% moisture
Inlet loading, Ib/hr
Size distribution
<10 U
<100 \i
Small
100,000
21,000
45
1.5
20
45,000
74,000
400
17.1
1,600
400
75
74,000
400
15
400
10
35
Large
300,000
63,000
45
1.5
20
135,000
222,000
400
17.1
4,800
1,200
75
222,000
400
15
1,200
10
35
Outlet loading, Ib/hr
Outlet loading, gr/ACF
Efficiency, wt. %
Case 1 — Medium or High Efficiency
16.79 40
.0265 0.0211
95.9 96.8
'Based on 100% reinjection of collected char from mechanical collector.
335
-------
TABLE 118
FSTlMATFn CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR ELECTROSTATIC PRECIPITATORS
FOR BARK BOILERS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other (Model Study)
(4) Total Cost
LA Process Wt.
Small
Large
High Efficiency
Small
74,000
400
45,000
15
0.63
400
74,000
400
45,000
15
.0265
16.79
95.9
114,500
50,090
Included
22,630
23,420
Existing
5,680
30,610
1,500
13,120
2,380
5,250
21,250
290,430
Large
222,000
400
135,000
15
0.63
1,200
222,000
400
135,000
15
.0211
40
96.8
262,260
1
!
;
97,390
Included
65,160
33,540
Existing
11,740
59,360
3,750
31,250
4,620
8,750
21,250
599,070
Data based upon one quote.
336
-------
TABLE 119
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS
FOR BARK BOILERS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
8,600
£ .011/kw-l-
LA Process Wt.
Small
r
Large
High Efficiency
Small
480
$500
2,629
3,609
29,043
32,652
Large
480
$1,000
7,190
8,670
59,907
68,577
Data based upon one quote.
-------
CO
cc
CO
Q
s
o
X
CO
O
O
FIGURE 91
CAPITAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR BARK BOILERS
COLLECTOR PLUS AUXILIARIES
300
200
100
100 . 200 300 400 500
PLANT CAPACITY, M LBSTEAM/HR
338
-------
CO
cc
o
Q
V)
Q
I
O
X
CO
O
O
FIGURE 92
ANNUAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR BARK BOILERS
9
8
7
6
5
_>
/\
//
'/
y
s
/v
of-
f
x
-------
TABLE 120
WET SCRUBBER PROCESS DESCRIPTION
FOR KRAFT MILL BARK BOILER SPECIFICATION
A single wet scrubber is to treat the flue gas from a conventional spreader stoker fired boiler.
The boiler is equipped with a mechanical collector which serves as the initial collection
device for the bark char and sand. 100 percent of the collec ted bark char is reinjected to the
boiler after screening on a 30 mesh sloped vibrating screen. Thirty percent of the initial ash
content of the bark is removed in the screening operation, while the other 70 percent
eventually escapes from the mechanical collector with the outlet gases. The mechanical
collector and sand classifying and hand/ing equipment are not to be supplied by the vendor.
The exhaust gas will be brought from the existing mechanical collector to an existing ID fan
located outside the building at grade. The scrubber will be located in the adjoining area
which is free of space limitations. The scrubber is to be located in series with and between
the existing ID fan and an existing 150 ft stack. The existing fan and stack are connected by
a 25 ft straight run of duct work. This existing straight run is to serve as the scrubbing
system bypass and the vendor shall furnish and install the required bypass damper.
The scrubbing system shall contain a Venturi-type scrubber capable of developing the
necessary pressure drop to scrub gases of contaminants to meet outlet emissions specified in
the operating conditions. The scrubber Venturi is to be constructed of type 304 stainless
steel. The de-entrainment separator may be type 304 stainless steel or rubber lined carbon
steel. The de-entrainment device shall be a cone-bottom center drained vessel to avoid the
collection of paniculate. It shall have adequate capacity to serve as the surge tank for the
recirculation system. Liquor effluent shall be piped from the bottom of the separator to the
recirculation pump. Discharge from the recirculation pump is to be returned to the scrubber
and part withdrawn to a slurry settling basin to be provided by the customer. The slurry
withdrawal is to be set to maintain about 5 wt. % solids. Fresh water is to be added to the
system at the separator on level control. External piping is to be constructed of carbon steel.
Control valve seat and trim are to be stainless steel alloy.
The vendor is also to supply the following auxiliary equipment:
(1) Pumps — Rubber lined carbon steel or equivalent. Packing glands of slurry pumps to be
flushed with fresh water.
(2) Fan — Induced draft with flow control damper. Carbon steel construction. Fan to be
sized to overcome scrubbing system pressure drop only. Existing fan v.-ill supply static
pressure for existing duct work and stack.
13) Connecting Ductwork and External Piping — Ductwork to be constructed of carbon
steel except where condensation may occur where 304 stainless steel construction will
be required.
(41 Controls
(5) Reheat Exchanger — Exchanger to be sized to reheat scrubber effluent 100°F. Design
to be vertical shell and plain tube type with dirty gas up or down flow on the tube side.
Materials of construction to be carbon steel except where condensation may occur.
340
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TABLE 121
WET SCRUBBER OPERATING CONDITIONS
FOR BARK BOILER SPECIFICATION
Two sizes of wet scrubbers are to be quoted for one efficiency level. Vendors' quotation
should consist of two separate and independent quotations.
Rated steam load, Ib/hr
Process weight bark feed, Ib/hr wet
Moisture content, wt. %
Ash content, wt. %
Excess air rate, %
Gas to mechanical collector
Flow, SCFM
Flow, ACFM
Temperature, °F
Moisture, vol. %
Inlet loading, Ib/hr
Outlet loading, Ib/hr
Collector efficiency, %
Gas to wet scrubber
Inlet temp, to reheater tube side, °F
Inlet temp, to scrubber, °F
Inlet flow to scrubber, ACFM
Inlet load, Ib/hr
Size distribution
Scrubber outlet, °F
Scrubber outlet, ACFM
Reheater outlet temp., °F
Reheater outlet flow, ACFM
Reheater tube area, fir
Small
100,000
21,000
45
1.5
20
45,000
74,000
400
17.1
1,600
400
75
400
290
65,400
400
10
35
143
55,300
243
64,500
7,720
Large
300,000
63,000
45
1.5
20
135,000
222,000
400
17.1
4,800
1,200
75
400
290
196,200
1,200
10
35
143
165,900
243
193,500
23,160
Outlet loading, Ib/hr
Outlet loading, gr/ACF
Efficiency, wt. %
Case 1 — Medium or High Efficiency
16.79 40
.0304 .0241
95.9 96.8
341
-------
TABLE 122
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS
FOR BARK BOILERS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow (from reheat(
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost |
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment J
(3) Installation Cost N
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other J
>
(4) Total Cost
LA Process Wt.
Small
r)
Large
High Efficiency
Small
65,400
290
45,000
17.1
0.71
400
64,500
243
47,500
21.5
0.0304
16.79
95.9
31,399
39,463
114,126
184,988
Large
196,200
290
135,000
17.1
0.71
1,200
193,500
243
143,000
21.5
0.0241
40
96.8
92,781
t
81,521
J
280,230
454,532
342
-------
TABLE 123
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR BARK BOILERS
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8.600
$6/hr
$.011/kw-J
$.25/M ga]
LA Process Wt.
Small
r
Large
High Efficiency
Small
1,200
5,200
6,200
24,387
5,450
29,837
42,437
18,499
60,936
Large
1,200
12,483
13,843
84,568
14,925
99,493
127,019
45,453
172,472
CO
J*
CO
-------
FIGURE 93
CAPITAL COSTS FOR WET SCRUBBERS
FOR BARK BOILERS
O
O
LL
O
V)
O
I
O
c/5
O
O
500 r
400
300
200
TURNKEY SYSTEM
COLLECTOR PLUS AUXILIARIES
100
80
60
50
40
30
COLLECTOR ONLY
z
80 100 200 300 400
PLANT CAPACITY, M LBSTEAM/HR
600
344
-------
FIGURE 94
ANNUAL COSTS FOR WET SCRUBBERS
FOR BARK BOILERS
300
200
V)
a:
O
Q
CO
Q
s
O
X
O
O
100
80
60
50
40
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES) >/
OPERATING COST
80 100 200 300 400
PLANT CAPACITY, M LBSTEAM/HR
600
345
-------
FIGURE 95
CONFIDENCE LIMITS FOR
CAPITAL COST OF WET SCRUBBERS ONLY
FOR BARK BOILERS
V)
cc
O
100 200 300 400 500
PLANT CAPACITY, M LBSTEAM/HR
346
-------
REFERENCES
1. Elmore, C. P. and Rochford, "Simultaneous Burning of Pulverized Coal,
Bark, and Oil or Gas", TAPPI, Vol. 46, June 1963, pp. 157A-160A.
2. Roberson, James E., "Bark Burning Methods", TAPPI, Vol. 51, June
1968, pp. 90A-98A.
3. Barron, Alvah Jr., "Studies on the Collection of Bark Char Throughout
the Industry", TAPPI, Vol. 53, August 1970, pp. 1441-1448.
4. Bush, Charles C. and Tribble, Joseph J., "Simultaneous Burning of Bark
and Gas or Oil", TAPPI, Vol. 46, June 1963, pp. 160A-163A.
5. Green, Bobby L., "Boiler for Bark Burning", Power Engineering,
September 1968, pp. 52-53.
6. Despain, J. R., "Vibratory Feeding of Bark-Burning Boilers", TAPPI, Vol.
52, March 1969, pp. 435-438.
347
-------
348
-------
m
3J
30
O
O
V)
-------
9. FERROSILICON AND FERROCHROME
Ferroalloy is a generic name for the alloys of iron with materials such as silicon,
chromium, manganese, and phosphorus. The nonferrous portion of these alloys
can vary from 5 to 90%. They are used primarily as alloying agents and
deoxidants in iron and steel production.
Most ferroalloys made in the USA are produced in two kinds of equipment —
blast furnaces and electric furnaces. Blast furnace operations can be used to
produce Spiegeleisen*, ferromanganese, ferrosilicon, and ferrophosphorus.
These products are made at a lower cost, but are limited to alloys containing a
high carbon level and a low percentage of nonferrous metal. Electric furnaces
are required to produce low carbon alloys and high nonferrous metal content
alloys. For example, ferrosilicon from a blast furnace is limited — primarily by
the limited temperature level available — to a maximum of about 17%
silicon.'11 A typical carbon content for this product is 1.5 wt. %. Electric
furnaces can produce ferrosilicon with a silicon content in excess of 85% and a
carbon level less than 0.15%. Typical ferroalloy compositions are shown in
Table 124.
Since the vast majority of domestic ferroalloy production is done by electric
furnaces, this narrative will deal with this type of processing exclusively and
will concentrate upon ferrosilicon and ferrochrome production.
The electric furnaces used for ferroalloy production are different from those
used for iron and steel melting. The majority of the energy expended is used to
perform a chemical reaction rather than to supply heat for melting. In most
cases the electrodes are buried in the charge rather than suspended above. A
typical ferroalloy furnace is illustrated in Figure 96, The power supplied is
generally three phase and there are, consequently-, three or six electrodes. The
furnaces range in size from a few hundred to 50,000 kw(1) and exhibit a
requirement of 1 to 6 kwh/lb of alloy produced.(2)
The furnaces are fed continuously at the top and tapped at the bottom in small
batches relative to the furnace size at one to two hour intervals. The furnace
charge consists of iron ore, nonferrous metal ore, reducing agent, and fluxes.
The reducing agent may be coke, coal, coke fines, wood chips, or ferrosilicon
alloys. As the reactions proceed, the products sink to the bottom of the
furnace. Gaseous reaction products rise to the top of the furnace and, if
combustible, burn. The unreacted charge remains at the top. The tops of the
electrodes are submerged about halfway into the mix to allow mass transfer to
occur between the reaction gases and the descending charge.
*Spiegeleisen is the name for low manganese content ferromanganese.
349
-------
PLAN
~__ 0)
SECTION
(a) ELECTRODES. (f) FLEXIBLE CONNECTORS.
(b) ELECTRODE HOLDERS (g) CABLES TO COUNTERBALANCES.
(c) CARBON HEARTH (h) TAP HOLE
(d) CHARGE (i) PLATFORM
(e) BUSBARS (z) CAR
FIGURE 96
ELECTRIC FURNACE FOR FERROALLOY PRODUCTION
350
-------
TABLE 124
COMPOSITIONS OF TYPICAL FERROALLOYS
ALLOY TYPE C Mn P S Si V Cr Ti Al
Ferromanganese (Std.) 7.5* 80 0.35* 0.05* 1.25*
Ferromanganese(LC.) 0.1-0.75 83 0.35 0.05 1.25
Ferrosilicon 0.15* 0.05* 0.04* 50
Ferrochromium (H.C.) 6 3* 73
Ferrochromium (L.C.) 0.03-2.0 1.5* 73
Ferrovanadium 3.5* 0.25* 0.40* 13* 35 1.5*
Silicomanganese 65 20
Ferrotitanium 4 2.5 20 1.5
Spiegeleisen 6.5* 17 0.25* 0.05* 1.0-4.0
Silvery Iron 1.5* 0.15* 0.06* 17
'Maximum
oo
01
-------
FERROCHROME
Ferrochrome is produced by the direct reduction of chromium spinels often
incorrectly called chromite. Chromite is a compound with the formula FeO •
Cr203 and containing 67.8% Cr203. The ores commonly used contain - 62%
Cr203 and have a molar ratio of Cr/Fe greater than 2/1.(3) The product of the
reduction done in an electric furnace will be 65 to 70% chrome.14' The carbon
content will vary depending upon the process by which it was made.
Ferrochrome is sold on the market in grades delineated by carbon content.
High carbon ferrochrome is used for low alloy steels needing the addition of
both chrome and carbon. Intermediate carbon levels are used for stainless
steels. Low carbon ferrochrome is used for austenitic stainless steels where
excess carbon will cause Cr23Cg precipitation at grain boundaries.141
High carbon ferrochrome is made by a multi-stage reduction of the chromite
ore by carbon. Either coke or anthracite may be used as the source of carbon.
The major reactions involved are:'31
1. 7 Cr203 + 27C t 2 Cr7C3 + 21 CO
2. FeO + C $ Fe + CO
3. The Cr7C3 is dissolved by Fe to yield (CrFe)7C3
The theoretical carbon content is 8.7%. It is usually lower in practice due to
the presence of impurities. If the raw ore contains Al203, MgO, or Si02, a
little additional decarburization takes place during production. The high carbon
ferrochrome can be reduced to an intermediate carbon level by oxygen lancing
in the ladle after tapping.
Low carbon ferrochrome is made by the reduction of high carbon ferrochrome.
The most common reducing agent is silicon. The processes used are multi-step
involving more than one furnace as well as reaction vessels. A diagram of one
such process is shown in Figure 97. Chromite ore, silica, and coke are charged
to a submerged arc furnace using Soderberg electrodes. The product is a high
carbon ferrosiliconchrome from the following reaction:'4'
Cr203 • FeO + Si02 + 6C ^ Cr2FeSi + 6CO
This product is tapped into a silica lined ladle and from there sent to the
second reaction vessel.
352
-------
ELECTRODE
PASTE
ELECTRODE
PASTE
CHROMITE
ORE* LIME
r
SODERBERG
ELECTRODE
CHROMITE
ORE
SLAG FURNACE
ROTATING
ALLOY FURNACE
SILICA ROCK
SiOz
COKE
SLAG 30
INTERMEDIATE
i y> UN i cnrviEL/
% Cr,O3 / ALLOY
I <
1st REACTION
VESSEL 11
LOW C F. Cr SLAG >4 V. Cr2 O3
7
INGOTS
FOR SALE,
FINAL LEAN
SLAG TO WASTE
INTERMEDIATE
ALLOY Ft Si Cr
FIGURE 97
PROCESS DIAGRAM FOR LOW CARBON
FERROCHROME PRODUCTION
353
-------
Other chromite ore is mixed with quicklime, preheated and sent to an open arc
furnace using Soderberg electrodes. This furnace produces a 30% C^C^ slag
which is tapped to the first reaction vessel. In the first reaction vessel the slag
reacts with intermediate ferrosiliconchrome alloy from the second reaction
vessel to yield low carbon ferrochrome and 14% C^C^ slag. The low carbon
ferrochrome is cast into ingots for sale. The 14% C^C^ slag is sent to the
second reaction vessel where it reacts with high carbon ferrosiliconchrome from
the alloy furnace to form intermediate ferrosiliconchrome alloy and final lean
slag which is sent to waste.
Both furnaces in this process generally operate with 40 inch diameter
Soderberg electrodes and range from 8000 to 12,000 KVA. The process
consumes 1 1,500 kwh/ton chrome and produces an alloy whose carbon level is
as low as 0.015 wt. %. In addition to the carbon, a typical product analysis
Cr - 68 to 76 wt. %
S - 0.01 wt. %
P - 0.02 wt. %
As - 0.001 wt. %
Mn - 0.45 wt. %
Ni - 0.45 wt. %
Si - 0.75 wt. %
A second process for low carbon ferrochrome is shown in Figure 98 High
carbon ferrochrome is briquetted with an oxidant and dried. The bricks are
then heated to 1370°C at a programmed rate to -yield a porous product which
has the same shape as the briquettes. A typical analysis is:
C - 0.008 wt. %
Si - 1.10wt. %
Cr - 69.5 wt. %
FERROSILICON
Ferrosilicon is produced in the United States in both blast furnaces and electric
furnaces. The blast furnaces are similar to but not identical with those used for
steel. They can produce only alloys with low silicon content because of
temperature limitations. Higher quality alloys must be made in electric
furnaces. These furnaces operate with their electrodes buried in the charge and
use the majority of the energy developed to force the combination of iron and
carbon with the silica. The raw materials charged to the furnace include a silica
source, an iron source, and a reducing agent. Commonly used silica sources are
354
-------
CRUSHED HIGH CARBON
FERRO-CHROME
| BALL MILL |
^
FINE MESH HIGH CARBON FERRO-CHROME
POWDER
OXIDIZER
OXIDIZED
HIGH CARBON FERRO-CHROME
SHAPING PRESSES |
DRYING OVEN
BRICKS AND BRIQUETS
[VACUUM FURNACE
SIMPLEX FERRO-CHROME
FIGURE 98
PROCESS DIAGRAM FOR LOW CARBON
FERROCHROME PRODUCTION
355
-------
quartz, quartzites, chalcedony, sandstone, and sand. Commonly used reducing
agents are coke, coal, and charcoal. Steel scrap and iron ore provide iron for the
reaction. The net reactions which occur are:
Si02 + 2C = S1 + 2CO
Fe203 + 3C = 2Fe + 3CO
Temperatures up to 2000° C are used. The actual reactions which occur are
complex multi-step ones which net out to the simple relationships shown
above. As examples:131
SiO2 + 3C = SiC + 2CO
2SiC + Si02 = 3Si + 2CO
and
Si02(|) + Sl(1) = 2SiO(g)
2SiO(g) + 2C(s) = 2Si(|) + 2CO(g)
Ferrosilicon is produced in a one step process and consumes 1 to 6 kwh per
pound of alloy produced.' 2)
NATURE OF THE GASEOUS DISCHARGE
The gaseous effluent is different for each of the three types of electric furnaces
used in the domestic production of ferrosilicon and ferrochrome. The furnace
types are:
Submerged Arc Open Hood Furnace
Submerged Arc Closed Hood Furnace
Open Arc Furnace.
The open arc furnace is used only in low carbon ferrochrome production. The
other two types are used in all of the other cases.
CLOSED HOOD
The emission from a closed hood furnace is principally carbon monoxide
356
-------
resulting from the reduction of metallic oxides by the carbon reducing agent.
The weight of carbon monoxide given off can exceed the weight of the
ferroalloy produced. As an example, the weight balance for a hypothetical
batch of 45% silicon content ferrosilicon is presented in Table 125. The
numbers in the table are based upon an assumed production rate of 2 tons/hr
of alloy. Raw materials assumed were quartzite as the silica source, coke as the
reducing agent, steel shavings as the iron source, and Soderberg electrodes.
The calculated emission of carbon monoxide is 2.12 tons/hr compared to the
alloy production rate of 2.00 tons/hr.
OPEN HOOD
Emissions from an open hood furnace are quite different because the carbon
monoxide which is evolved burns at the top of the furnace as it comes into
contact with air being drawn into the hood. This combustion produces a
large volume of high temperature gas in the hood going to the abatement
equipment. The actual volume of gas depends upon the amount of air induced
into the collection system. A specific comparison of gas volumes and
temperatures for closed and open furnaces producing 50% ferrosilicon is
presented in Table 126. The comparison in the table shows a factor of 26
between the two furnace types. Factors as high as fifty have been reported.
Gas is not produced at a steady rate. The amount of variation depends upon
operation of the furnace and the hooding system. Variations in flow can be
as much as 40%.
Furnaces used in the production of low carbon ferrochrome produce a much
lower rate of gaseous discharge because the products of the reduction reactions
are not gaseous. A hypothetical weight balance for the production of low
carbon ferrochrome is given in Table 127. Notice that the reducing agent
utilized is ferrosiliconchrome rather than carbon. The reaction products of the
reduction process leave the furnace as slag rather than as carbon monoxide.
Those gaseous products which do occur result from impurities in the chromium
ore charged to the process.
NATURE OF THE PARTICULATE EMISSION
Operation of ferroalloy furnaces produces particulate emissions at three
principal points:
1. The top of the furnace carried out with the reaction gases or hot air
stream
357
-------
TABLE 125
WEIGHT BALANCE FOR PRODUCTION OF 45% FERROSILICON
Production Rate Basis: 2 tons/hr of alloy
Input, tons/hr Output, tons/hr*
Quartzite 2.02 Ferrosilicon 2.00
Coke 1.18 Slag 0.06
Steel Shavings 1.15 Gas 2.33
Electrode Mass 0.04
4.39 4.39
Major Components of Gas Emission
Wt%
CO 91.2
SiO 1.6
H2 0.5
H20 2.0
Si 1.0
Volatile** 3.7
100.0
Averaged over operating cycle
"Volatile matter from coke, steel shavings, and electrodes
358
-------
TABLE 126
COMPARISON OF GAS FLOWS FROM OPEN AND CLOSED HOOD
50MW SUBMERGED ARC FURNACES MAKING 50% FERROSILICON
Closed Hood Open Hood
Flow, ACFM 20,000 310,000
Temperature, °F 1,100 460
Flow, SCFM 6,600 175,000
359
-------
TABLE 127
WEIGHT BALANCE FOR PRODUCTION OF LOW CARBON FERROCHROME
Production Rate Basis: 2 tons/hr of alloy
Input, tons/hr Output, tons/hr*
Chromium Ore 3.51 Ferrochromium 2.00
Ferrosilicon chromium 1.45 Slag 6.51
Lime 3.72 Gas 0.35
Oxygen from air** 0.18 _
8.86 8.86
Major Components of Gas Emission
Wt%
CO2 99.6
P2°5 _°A
100.0
* Averaged over operating cycle
**For oxidation of the silicon
360
-------
2. The furnace tapholes. Since most furnaces are tapped cyclically
rather than continuously, this source is active only about 15% of the
time
3. The ladle after tapping, which is also a non-continuous source of
particulate.
The particulate emitted is small in size and is composed of the oxides of the
metals being produced and used in the process. Some examples are given in
Table 128. Agglomeration of the particles can make the effective particle size
to the collector much larger than that indicated in the table. Grain loadings
have been reported in the range of 5 to 30 gr/SCF for closed hood systems and
0.1 to 2 gr/SCF for open hood systems.'5 >
POLLUTION CONTROL EQUIPMENT
Three types of pollution control equipment have been used to control the
emissions from ferroalloy furnaces; high energy scrubbers, electrostatic
precipitators, and fabric filters.
The only type of scrubber which is applicable to the control of ferroalloy
furnaces is the high energy Venturi. This limitation results from the small size
of the particulate emitted which requires a high pressure drop for collection.
Venturi scrubbers have been successfully employed at collection efficiencies in
excess of 98%. Recirculation of the scrubbing water keeps the net water usage
at a low level. The Venturi also has the ability to handle the sudden
temperature surges common in ferroalloy furnace operation.
There are several drawbacks to their use, however. The high pressure drop
causes high energy consumption and power cost. Operating costs are further
increased by the requirement of disposal of the sludge produced.
Fabric collectors have also been successfully employed on ferroalloy furnace
emissions. Each of these applications has involved a pressure type filter with
the fan, on the dirty gas side to aid in maintenance of the baghouse. They
produce no visible plume and can handle the small sized particulate at a lower
energy input than scrubbers. The high temperature of the gas emitted is a
problem, however. Filters in this service usually employ high temperature rated
bags, such as fiberglass, but can use synthetics if sufficient gas cooling is
provided.
361
-------
TABLE 128
PROPERTIES OF PARTICIPATE EMISSIONS
FROM FERROALLOY FURNACES
Alloy Type 50% FeSi
Furnace Hood Type Open
Particle Size, y
Maximum 0.75
Range of most particles 0.05-0.3
H.C. FeCr Chrome Ore-Lime Melt
Covered Open
1.0 0.50
0.1-0.4 0.05-0.2
Chemical Analysis, wt %
Si02 63-88
FeO
MgO
CaO
MnO
AI2°3
Cr2°3
Na20
LOI
20.96
10.92
15.41
—
2.84
7.12
29.27
—
—
10.86
7.48
7.43
15.06
—
4.88
14.69
1.70
13.86
362
-------
The filter system must include a gas cooler to protect the bags. Usually a
mechanical collector is used to prevent large burning particles which have been
ejected from the furnace from reaching the bags and burning holes in them.
The type of dust being collected has a marked effect on the pressure drop
encountered.
Electrostatic precipitators operate at the lowest pressure drop of the three
alternatives. They produce no visible plume and can handle high temperatures
more easily than baghouses. Ferroalloy particulate emissions, however, have
resistivities which are too high for good precipitator operation.'5) Either
operation at high temperature, where the resistivity is acceptable, or
conditioning, to alter the resistivity, is required to achieve acceptable
performance. Either alternative increases the cost of collection.
SPECIFICATIONS AND COSTS
Specifications have been written for a furnace producing ferrosilicon and for
one producing ferrochrome. In each case, the furnace chosen was an open hood
submerged-arc type. This type was selected because it is the one used in the
majority of industrial applications. Table 129 shows the number and types of
furnaces used in the U.S.121 About 75% of the furnaces used in this country are
open hood submerged arc types.
The sizes of the ferrosilicon furnaces selected for the specification were 10 mw
and 40 mw. This corresponds to a production rate of 2 tons/hr and 8 tons/hr of
50% ferrosilicon. The ferrochrome furnace sizes selected were 8 mw and 30 mw
which produce 1.9 tons/hr and 7.1 tons/hr of high-carbon ferrochrome
containing 70% chromium. For each of the four furnaces, specifications were
written for a scrubber, a fabric collector, and an electrostatic precipitator.
The exhaust gas volumes used in the specifications were based upon published
data for open hood submerged-arc furnaces.151 Exhaust gases for the 50%
ferrosilicon cases were based upon a gas generation of 130 to 140 SCFM/mw
and a dilution factor in the hood of 27. Gases for the ferrochrome cases were
based upon a gas generation of 80 to 90 SCFM/mw and the same hood dilution
factor as for ferrosilicon.
363
-------
There were no quotations received in response to the precipitator specification.
One supplier reported no industrial experience in this application and, as it is a
difficult application, could supply no cost estimates. A second supplier cited
extensive pilot plant data which demonstrated that conventional precipitator
design was not applicable and that the modifications necessary prevented
precipitators from being competitive. As a result, this supplier will not quote
dry precipitators for ferroalloy applications. The combination of a low energy
scrubber followed by a wet precipitator offers an attractive alternative.
Responses to the scrubber specification were varied. All suppliers commented
that the pressure drops required to achieve the specified performance levels
were high. The quotations from one of the suppliers were based on equipment
which, in some cases, could not achieve the cleaning efficiency specified. The
supplier quoted equipment for the maximum performance level he could
supply. The specified cleaning efficiency was quoted only for the ferrochrome
furnace scrubbers designed for the LA Process Weight efficiency. The other
supplier who quoted scrubber systems for these applications stated that pilot
plant pressure drop determinations would have to be made before the systems
could be guaranteed. The cost shown for scrubbing systems, therefore, must be
classified as representing undemonstrated technology.
Scrubbing systems were quoted including gas cooling towers. One of the
suppliers commented that savings could be effected by the elimination of gas
cooling with only minor increases in the capital and operating cost of fans and
motors. Capital cost savings would average about 3% for the small furnaces and
5% for the large furnaces. Total annual operating costs would also be lower.
Only one response was received to the fabric filter specification. Only costs for
the high efficiency level were presented, as in the case of all of the fabric filter
quotations solicited in this contract.
Capital and operating costs for fabric filters are presented in Tables 132, 133,
136, and 137. The data are plotted in Figures 99, 100, 101, and 102. All of the
data are based upon a single quotation.
Capital and operating costs for wet scrubbers are presented in Tables 144, 145,
148, and 149. These data are plotted in Figures 103, 104, 105, and 106. Only
those data which represent cleaning efficiencies at the levels designated in the
364
-------
TABLE 129
DISTRIBUTION OF DOMESTIC FERROALLOY FURNACES
Furnace Type
Submerged Arc — Open Hood
Submerged Arc — Closed Hood
Open Arc
Number In Use
100-150
30-35
12
% of Total
71-76
21-18
8-6
Alloy Type
Silicon Alloys
Chromium Alloys
Manganese Alloys
Calcium Carbide
Approximate Percent of Total
Production Facilities
40
25
20
10
365
-------
equipment specification have been presented. Graphs for the ferrosilicon
furnaces are limited to the LA-Process Weight Case in order to avoid
presentation of data based on extrapolation to higher efficiency levels than
those within the experience of any of the participants in this study.
366
-------
367
-------
TABLE 130
FABRIC FILTER PROCESS DESCRIPTION
FOR FERROSILICON FURNACE SPECIFICATION
The air pollution abatement system is to serve a new ferroalloy furnace installation. The
furnace is the submerged arc type and has been equipped with an open hood by the furnace
supplier. The furnace is charged with raw material continuously and is tapped intermittently
on a two hour cycle. Hooding of the tap holes has also been installed by the furnace
supplier.
The abatement system shall include the following:
(a) Fans sized with at least 20% excess capacity when operating at the design pressure drop
and 90% of the maximum recommended operating speed.
(b) A mechanical collector upstream of the baghouse to help protect the bags from burning
particles.
(cj A gas cooler to lower the temperature of the gas going to the baghouse to 40CPF during
normal operation.
(d) Compartmented design of the baghouse which permits shutdown of each section for
maintenance.
(e) Sufficient capacity for operation with one compartment out of service.
(f) Bags with a temperature rating of - 500°F.
(gi A high temperature bypass around the fabric filter for use during operational upsets.
(h) Dust hoppers and conveyors.
(i) Dust storage bins with 24 hour capacity.
Two sizes of fabric collectors have been specified for each of the two efficiency levels.
Vendors responses should, however, consist of only one quotation for each of the two sizes,
with a representation of the efficiency expected.
368
-------
TABLE 131
FABRIC FILTER OPERATING CONDITIONS
FOR FERROSILICON FURNACE SPECIFICATION
Small Large
Furnace Size, mw 10 40
Alloy Production Rate, ton/hr * 2 8
Process Weight, ton/hr 4.4 17.6
Gas to Dilution Cooler
Flow, ACFM 63,700 255,000
Temp.,°F 460 460
Flow, SCFM 36,000 144,000
Gas to Collector
Flow, ACFM 72,500 290,100
Temp.,°F 400 400
Flow. SCFM 44,750 180,000
Paniculate Loading, gr/ACF 0.91 0.91
Ib/hr 463 1.852
Case 1 — Medium Efficiency
Outlet Loading, Ib/hr 9.23 40.0
Outlet Loading, gr/ACF 0.0181 0.0196
Efficiency, wt. % 98.0 97.8
Case 2 - High Efficiency
Outlet Loading, Ib/hr 5.10 20.4
Outlet L oading, gr/A CF 0.01 0.01
Efficiency, wt % 98.9 98.9
*A verage over operating cycle
369
-------
TABLE 132
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR FABRIC FILTERS
FOR FERROSILICON FURNACES
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other, erection
(4) Total Cost
Small
Large
High Efficiency
Small
63,700
460
36,000
-
.85
463
72,500
400
44,750
«0.01
« 5.9
99.9 +
126,350
20,000
0
4,000
4,500
12,000
7,200
163,400
6,620
10,140
5,750
5,750
2,140
19,300
2,140
Incl
83,780
473,070
Large
255,000
460
144,000
-
.85
1,852
290,100
400
180,000
« 0 . 0 1
« 5.9
99.9 +
489,470
107,000
0
9, 500
11,900
25,800
17,000
359,200
12,280
26,000
23,000
23,000
3,440
43,000
4,000
. Startup
316,480
1,471,070
370
-------
TABLE 133
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR FABRIC FILTERS FOR FERROSILICON FURNACES
Operating Cost Item
Operating Factor, He/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
7,700
$6/hr
$8/hr
$.011/kw-f
Small
18,000
1,200
19,200
4,560
7,500
T 17,730
17,730
48,990
47,300
98,290
Large
18,000
1,200
19,200
11,800
31,640
62,300
62,300
124,940
147,100
272,040
High Efficiency
Small
Large
CO
•-J
-------
CO
cc
O
O
CO
Q
I
O
O
3000
2000
400
300
FIGURE 99
CAPITAL COSTS FOR FABRIC FILTERS FOR
FERROSILICON FURNACES
8 10 20
FURNACE SIZE, MW
30 40 50
372
-------
FIGURE 100
ANNUAL COSTS FOR FABRIC FILTERS
FOR FERROSILICON FURNACES
400
300
200
V)
tr
o
Q
I
<
CO
O
X
CO
O
O
100
80
60
50
40
TOTAL COST
(OPERATING COSTS PLUS
CAPITAL CHARGES)
8 10 20
FURNACE SIZE, MW
40 50 60
373
-------
TABLE 134
FABRIC FILTER PROCESS DESCRIPTION
FOR FERROCHROME FURNACE SPECIFICATION
The air pollution abatement system is to serve a new ferroalloy furnace installation. The
furnace is the submerged arc type and has been equipped with an open hood by the furnace
supplier. The furnace is charged with raw material continuously and is tapped intermittently
on a two hour cycle. Hooding of the tap holes has also been installed by the furnace
supplier. The abatement system shall include the following:
(a> Fans sized with at least 20% excess capacity when operating at the design pressure drop
and 90% of the maximum recommended operating speed.
fb) A mechanical collector upstream of the baghouse to help protect the bags from burning
particles.
(c) A gas cooler to lower the temperature of the gas going to the baghouse to 400° F during
normal operations.
(d) Compartmented design of the baghouse which permits shutdown of one section for
maintenance.
500°F.
(g) A high temperature bypass around the fabric filter for use during operational upsets.
(h) Dust hoppers and conveyors.
(i) Dust storage with a capacity of 24 hours.
Two sizes of fabric collectors have been specified for each of two efficiency levels. Vendors
responses should, however, consist of only one quotation for each of the two sizes with a
representation of the efficiency expected.
374
-------
TABLE 135
FABRIC FILTER OPERATING CONDITIONS
FOR FERROCHROME FURNACE SPECIFICATION
Small Large
Furnace Size, mw 8 30
Alloy Production Rate, ton/hr* 1.9 7.1
Process Weight, ton/hr 4.9 18.3
Gas to Dilution Cooler
Flow, ACFM 33,200 125,000
Temp., °F 480 480
Flow, SCFM 18,400 69,000
Gas to Collector
Flow, ACFM 39,400 148200
Temp., °F 400 400
Flow, SCFM 23,300 91,500
Paniculate Loading
gr/ACF 0.67 0.67
Ib/hr 174 650
Case 1 — Medium Efficiency
Outlet Loading, Ib/hr 10.25 26.32
Outlet L oading, gr/A CF 0.0394 0.0269
Efficiency, wt. % 94.1 95.9
Case 2 — High Efficiency
Outlet Loading, Ib/hr 2.60 9.76
Outlet Loading, gr/ACF 0.01 0.01
Efficiency, wt. % 98.5 98.5
*A verage over operating cycle.
375
-------
TABLE 136
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR FABRIC FILTERS
FOR FERROCHROME FURNACES
Effluent Gas Flow
ACFM
op
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other
(4) Total Cost
Small
Large
High Efficiency
Small
33,200
480
18,400
0.61
174
39,400
400
23,300
«0.01
«2.60
99.9 +
102,270
17,000
0
2,900
3,600
12,000
7,200
132,300
3,870
8,400
5,750
5,750
1,700
17,000
1,700
75,940
397,080
Large
125,000
480
69,000
0.61
650
148,200
400
91,500
«0.01
«2.60
99.9 +
283,260
57,000
0
3,200
4,000
15,700
10,700
185,800
8,070
14,230
13,000
13,000
3,000
28,500
2,150
180,990
822,600
376
-------
TABLE 137
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR FABRIC FILTERS FOR FERROCHROME FURNACES
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7,700
$6/hr
$8/hr
$.011/kw-hi
Small
18,000
1,200
19,200
4,400
6,540
10,600
10,600
40,740
39,700
80,440
Large
18,000
1,200
lo^nn
6,600
17,840
32,200
32,200
75,840
82,300
158,140
High Efficiency
Small
Large
CO
•>J
-J
-------
FIGURE 101
CAPITAL COSTS FOR FABRIC FILTERS FOR
FERROCHROME FURNACES
C/J
cc
o
Q
Q
<
s
O
x
CO
O
O
1000
800
600
500
400
300
200
100
TURNKEY SYSTEM
COLLECTOR PLUS AUXILIARIES
7 8 10
40 50
FURNACE SIZE, MW
378
-------
FIGURE 102
ANNUAL COSTS FOR FABRIC FILTERS FOR
FERROCHROME FURNACES
300
200
o
Q
1
<
C/J
O
X
8
o
100
80
60
50
40
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
10 20
FURNACE SIZE, MW
30
40 50
379
-------
TABLE 138
ELECTROSTATIC PRECIPITATOR PROCESS DESCRIPTION
FOR FERROSILICON FURNACE SPECIFICATION
The air pollution abatement system is to serve a new ferroalloy furnace installation. The
furnace is the submerged arc type and has been equipped with an open hood by the furnace
supplier. The furnace is charged with raw material continuously and is tapped intermittently
on a two hour cycle. Hooding of the tap holes has also been installed by the furnace
supplier. The abatement system shall include the following:
(a} A gas conditioning system to overcome the high resistivity of the paniculate emitted.
(b) Fans sized with at least 20% excess capacity when operating at the design pressure drop
and 90% of the maximum recommended operating speed.
(c) A precipitator with a minimum of two fields in the direction of gas flow.
(d) A safety interlock system which prevents access to the precipitator internals unless the
electrical circuitry is disconnected or grounded.
(e) Dust hoppers and conveyors.
(f) Dust storage with 24 hour capacity.
(g) A model study for the precipitator gas distribution.
Two sizes of precipitators are to be quoted for each of two efficiency levels. Vendors quotes
should consist of four separate and independent sets of figures.
380
-------
TABLE 139
ELECTROSTATIC PRECIPITATOR OPERATING CONDITIONS
FOR FERROSILICON FURNACE SPECIFICATION
Small Large
Furnace Size, mw 10 40
Alloy Production Rate, ton/hr* 2 8
Process Weight, ton/hr 4.4 17.6
Gas to Conditioner
Flow, ACFM 63,700 253,000
Temp., °F 460 460
Flow, SCFM 36,000 144,000
Gas to Collector
Flow, ACFM 84,000 336,000
Temp., °F 185 185
Flow, SCFM 67,700 271,000
Humidity, Ib H2O/lb DA 0.55 0.55
Paniculate loading
gr/ACF 0.64 0.61
Ib/hr 463 1,852
Case 1 — Medium Efficiency
Outlet Loading, Ib/hr 9.23 43.1
Outlet Loading, gr/ACF 0.0128 0.0139
Efficiency, wt. % 98.0 97.8
Case 2 - High Efficiency
Outlet Loading, Ib/hr 7.20 28.8
Outlet Loading, gr/ACF 0.01 0.01
Efficiency, wt. % 98.4 98.4
V. verage over operating cycle.
381
-------
TABLE 140
ELECTROSTATIC PRECIPITATOR PROCESS DESCRIPTION
FOR FERROCHROME FURNACE SPECIFICATION
The air pollution abatement system is to serve a new ferroalloy furnace installation. The
furnace is the submerged arc type and has been equipped with an open hood by the furnace
supplier. The furnace is charged with raw material continuously and is tapped intermittently
on a two hour cycle. Hooding of the tap holes has also been installed by the furnace
supplier. The abatement system shall include the following:
(a) A gas conditioning system to combat the high resistivity of the paniculate emitted.
(b) Fans sized with at least 20% excess capacity when operating at the design pressure drop
and 90% of the maximum recommended operating speed.
(c) A precipitator with a minimum of two fields in the direction of gas flow.
(d) A safety interlock system which prevents access to the precipitator internals unless the
electrical circuitry is disconnected or grounded.
(e) Dust hoppers and conveyors.
(f) Dust storage with 24 hour capacity.
(g) A model study for the precipitator gas distribution.
Two sizes of precipitators are to be quoted for each of two efficiency levels. Vendors quotes
should consist of four separate and independent sets of figures.
382
-------
TABLE 141
ELECTROSTATIC PftECIPITATOR OPERATING CONDITIONS
FOR FERROCHROME FURNACE SPECIFICATION
Furnace Size, mw
Alloy Production Rate, ton/hr*
Process Weight, ton/hr
Gas to Conditioner
Flow, ACFM
Temp., °F
Flow, SCFM
Gas to Co/lector
Flow, SCFM
Temp., °F
Flow, SCFM
Humidity, Ib H^/lb DA
Paniculate Loading
gr/ACF
Ib/hr
Small
8
1.9
4.9
33,200
480
18,400
37,400
185
30,200
0.40
0.54
174
Large
30
7.1
18.3
125,000
480
69,000
140,000
185
113,000
0.40
0.54
650
Outlet Loading, Ib/hr
Outlet Loading, gr/ACF
Efficiency, wt. %
Case 1 — Medium Efficiency
10.25
0.032
94.1
26.32
0.022
95.9
Outlet Loading, Ib/hr
Outlet Loading, gr/ACF
Efficiency, wt. %
Case 2 — High Efficiency
3.21
0.01
98.2
12.00
0.01
98.2
"A verage over operating cycle.
383
-------
TABLE 142
WET SCRUBBER PROCESS DESCRIPTION
FOR FERROSILICON FURNACE SPECIFICATION
The air pollution abatement system is to serve a new ferroalloy furnace installation. The
furnace is the submerged arc type and has been equipped with an open hood by the furnace
supplier. The furnace is charged with raw material continuously and is tapped intermittently
on a two hour cycle. Hooding of the tap holes has also been installed by the furnace
supplier. The abatement system shall include the following:
(a) Fans sized with at least 20% excess capacity when operating at the design pressure drop
and 90% of the maximum recommended operating speed.
(b) A Venturi type scrubber with a liquid to gas ratio in excess of 7 GPM/1000 ACFM
(saturated).
(c) An entrainment separator which will limit entrained water in the effluent.
(d) Aftercoolers capable of reducing the effluent gas temperature to 105°F by
countercurrent contact with 90°F cooling water.
(e) A slurry settler capable of producing a reasonably thickened underflow product while
returning water fully treated to minimize solids content.
(f) Filters to dewater the slurry product which are capable of producing a filter cake
with -70% solids content suitable for open truck transportation. A minimum of two
units shall be provided.
Vendors shall specify the pressure drop at which the scrubber will operate. Two sizes of
scrubber have been specified at each of two efficiency levels. Vendors quotations shall
consist of four separate and independen t sets of numbers.
384
-------
TABLE 143
WET SCRUBBER OPERATING CONDITIONS
FOR FERROSILICON FURNACE SPECIFICATION
Furnace Size, mw
Alloy Production Rate, ton/hr*
Process Weight, ton/hr
Gas to Scrubber
Flow, ACFM
Temp., °F
Flow, SCFM
Paniculate Loading
gr/ACF
Ib/hr
Gas from Scrubber
Flow, ACFM
Temp.. °F
Flow, SCFM
Moisture Content, mol. %
Gas from After Cooler
Flow, ACFM
Temp., °F
Flow, SCFM
Moisture Content, mol. %
Small
10
2
4.4
63,700
460
36,000
0.85
463
45,300
117
40,800
11
42,400
105
39,000
7.6
Large
40
8
17.6
253,000
460
144,000
0.85
1,852
180,000
117
162,000
11
169,000
105
156,000
7.6
Outlet Loading, Ib/hr
Outlet Loading, gr/ACF
Efficiency, wt. %
Case 1 — Medium Efficiency
9.23
.0254
98.0
25.4
.0175
98.6
Outlet Loading, Ib/hr
Outlet Loading, gr/ACF
Efficiency, wt. %
Case 2 — High Efficiency
3.63
0.01
99.2
14.48
0.01
99.2
* Average over the operating cycle
385
-------
TABLE 144
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS
FOR FERROSILICON FURNACES
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost ^
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
^
Equipment — -/
(3) Installation Cost >
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
(I) Other J
>
(4) Total Cost
LA Process Wt.
Small
63,700
460
36,000
0.85
463
42,400
105
39,000
7.6
.025
9.2
98.0
40,200
129,700
874,100
1,044,000
Large
253,000
460
144,000
0.85
1,852
169,000
105
156,000
7.6
0.0175
25.4
98.6
134,900
299,700
1,750,400
2,185,000
High Efficiency
Small
63,700
460
36,000
0.85
463
42,400
105
39,000
7.6
.01
3.6
99.2
40,200
181,500
929,300
1,151,000
Large
253,000
460
144,000
0.85
1,852
169,000
105
156,000
7.6
.01
14.5
99.2
134,900
400,000
1,877,200
2,413,000
386
-------
TABLE 145
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR FERROSILICON FURNACES
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities *
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
7,700
p.Oll/kw-h
I.05/M gal
LA Process Wt.
Small
3,600
52,000
31,000
r 66,000
_
36,750
102J750
189,350
104,400
293.750
Large
4,800
109,000
65,500
286,550
_
148,040
434,590
613,890
218,500
832.390
High Efficiency
Small
3,600
57,500
34,500
119,900
44,005
163.905
259,505
115,100
374,605
Large
4..800
122,.000
72,000
490,600
173,155
663.755
861,555
241,300
1 1 n? s<;c;
CO
00
-J
-------
FIGURE 103
CO
cc
-------
FIGURE 104
ANNUAL COSTS FOR
WET SCRUBBERS FOR
FERROSILICON FURNACES
oo
cc
O
Q
LL
O
C/J
O
X
c/5
O
O
800
600
500
400
(
300
200
TOTAL COST
(OPERATING COSTS PLUS
, CAPITAL
100
OPERATING COST
10
20 30 40 50 60
FURNACE SIZE, MW
389
-------
TABLE 146
WET SCRUBBER PROCESS DESCRIPTION
FOR FERROCHROME FURNACE SPECIFICATION
The air pollution abatement system is to serve a new ferroalloy furnace installation. The
furnace is the submerged arc type and has been equipped with an open hood by the furnace
supplier. The furnace is charged with raw material continuously and is tapped intermittently
on a two hour cycle. Hooding of the tap holes has also been installed by the furnace
supplier.
The abatement system shall'include the following:
(a) Fans sized with at least 20% excess capacity when operating at the design pressure drop
and 90% of the maximum recommended operating speed.
(b) A Venturi-type scrubber with a liquid to gas ratio in excess of 5 GPM/1000 ACFM
I saturated I.
(c) An entrainment separator which will limit entrained water in the effluent.
(d) Aftercoolers capable of reducing the effluent gas temperature to 705° F by
countercurrent contact with 90°F cooling water.
(e) Slurry settler capable of producing a reasonably thickened underflow product while
returning water fully treated to minimize solids content.
(f) Filters to dewater the slurry product which are capable of producing a filter cake
with -70% solids content suitable for open truck transportation. A minimum of two
units shall be provided.
Vendors shall specify the pressure drop at which the scrubber will operate. Two sizes of
scrubbers have been specified at each of two efficiency levels. Vendors quotations shall
consist of four separate and independent sets of numbers.
390
-------
TABLE 147
WET SCRUBBER OPERATING CONDITIONS
FOR FERROCHROME FURNACE SPECIFICATION
Furnace Size, mw
Alloy Production Rate, ton/hr'
Process Weight, ton/hr
Gas to Scrubber
Flow. ACFM
Temp., °F
Flow, SCFM
Paniculate Loading
gr/ACF
Ib/hr
Gas from Scrubber
Flow, ACFM
Temp., °F
Flow, SCFM
Moisture Content, mol. %
Gas from Cooling Tower
Flow, ACFM
Temp., °F
Flow, SCFM
Moisture Content, mol. %
Small
8
1.9
4.9
33,200
480
18,400
0.61
174
23,200
119
20,800
12
21,500
105
19,800
7.6
30
7.1
18.3
125,000
480
69,000
0.61
650
87,000
119
78,100
12
81,000
105
74,500
7.6
Outlet Loading, Ib/hr
Outlet Loading, gr/ACF
Efficiency, wt. %
Case 1 — Medium Efficiency
10.25
.056
94.1
26.32
.038
95.9
Outlet Loading, Ib/hr
Outlet Loading, gr/ACF
Efficiency, wt. %
Case 2 — High Efficiency
1.84
0.01
98.9
6.95
0.01
98.9
*A verage over the operating cycle
391
-------
TABLE 148
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS
FOR FERROCHROME FURNACES
Effluent Gas Flow
ACFM
op
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
* gr/ACF
*lb/hr
Cleaning Efficiency, %
(1) Gas Cleaning Device Cost
(2) Auxiliaries Cost ^
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment ^
(3) Installation Cost ~*
(a) Engineering
(b) Foundations
& Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
(h) Painting
(i) Supervision
(j) Startup
(k) Performance Test
X
>
(I) Other ^
(4) Total Cost
LA Process Wt.
Small
33,200
480
18,400
0.61
174
25,400
105
20,140
.05
10.0
23,225
66,850
463,250
553,325
Large
125,000
480
69,000
0.61
650
95,000
105
75,325
.03
26.0
50,625
165,125
799,200
1,014,950
High Efficiency
Small
33,200
480
18,400
0.61
174
31,000
105
20,550
.01
1.8
26,200
142,100
664,700
833,000
Large
125,000
480
69,000
0.61
650
116,000
105
76,860
.01
6.9
62,100
267,700
1,153,200
1,483,000
392
-------
TABLE 149
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR
FERROCHROME FURNACES
Operating Cost It6m
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process) 1
Water (Cooling) J
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7.700
$0.011/kw-h
&0.05/M GaL
LA Process Wt.
Small
14,900
27,700
11,700
27,000
-
12,900
39,900
94,200
55,300
149,500
Large
14,900
50,800
20,500
95,500
_
47,400
"
142,900
229,100
101,500
330,600
High Efficiency
Small
14,900
42.000
25,000
63,700
_
20,000
"
83,700
165,600
83,300
248,900
Large
14.900
74.000
44,500
176,200
_
72,650
~
248,850
382,250
148,300
530,550
CO
CO
CO
-------
FIGURE 105
CAPITAL COSTS FOR WET SCRUBBERS
FOR FERROCHROME FURNACES
(HIGH EFFICIENCY)
CO
DC
o
Q
I
I
O
I
CO
O
O
4000
3000
400
300
200
COLLECTOR PLUS AUXILIARIES
30
200
40 50
FURNACE SIZE, MW
394
-------
FIGURE 106
ANNUAL COSTS FOR WET SCRUBBERS
FOR FERROCHROME FURNACES
(HIGH EFFICIENCY)
cc
2
_l
o
O
1000
800
600
500
400
300
TOTAL COST
(OPERATING COSTS PLUS
~ CAPITAL CHARGES)
CO
O
I
I-
200
100
.X
OPERATING COST
7 8 10 20
FURNACE SIZE, MW
30
40 50
395
-------
REFERENCES
1. Bocey, John L. Ferrous Process Metallurgy, John Wiley & Sons, Inc.,
NYC, 1954, p. 149-153,278,351-355
2. Person, R. A., "Emission Control of Ferroalloy Furnaces", Fourth Annual
North Eastern Regional Antipollution Conference, 1971
3. Elyutun, V. P. et al, Production of Ferroalloys, Electrometallurgy,
Moscow, 1957, p. 23-69, p. 158-213
4. Sully, A. H., and Brandes, E. A., Metallurgy of the Rare Metals —
Chromium Plenum Press, 1954, NYC, p. 19-25
5. Person, R. A., "Control of Emissions from Ferroalloy Furnaces
Processing", Journal of Metals, April, 1971
6. Bain, Edgar C. and Paxton, Harold W., Alloying Elements in Steel,
American Society for Metals, 1939, Metals Park, Ohio
7. The Making of Steel, American Iron and Steel Institute, 1964, NYC
8. Chaler, W. J. B., and Harrison, J. E. (eds) Recent Advances with Oxygen
in Iron and Steel Making, Butterworth & Co., 1964, Washington, D. C., p.
32-34
9. Schofield, M., "Industrial Silicon and Ferrosilicon" Metallurgia, July,
1967
396
-------
o
o
o
o
35
33
m
.
c/3
-------
C. Additional Cost Data
The previous section of this report has dealt with the costs of air pollution
control for specific processing applications. This section deals with generalized
cost correlations based upon the data obtained for the specific applications.
Four sections are presented:
1. A brief discussion of the basis for presenting annual operating costs,
including the capital charge portion of this cost
2. Derived capital cost indices for each specific process application
3. A presentation of the annual operating cost data for each process
area calculated at two different levels of utility costs
4. Graphical correlations of capital and operating costs for each type of
control equipment.
1. DISCUSSION OF COST BASIS
As previously noted in Section II A, the total annual cost for a particular
process is the sum of the direct annual operating cost and an annual capital
charge.
The direct annual operating cost includes the following cost items:
Operating (operator and supervisor) Labor
Maintenance Labor and Materials
Replacement Parts
Utilities and Supplies
The annual costs for these operating items are calculated from two sets of unit
cost data; one approaching the upper limit of unit cost, the other the lower
limit. An intermediate value was used in calculating annual operating costs in
the preceding section of this report.
The approach to calculation of the capital charge portion of the annual
operating cost for a pollution control system used in this program represents an
attempt at spreading the investment cost of the system, including taxes and
interest, across the useful life of the equipment. Many schemes for quantifying
this charge have been proposed. These schemes fall into three major categories:
397
-------
1. Straight line method which applies the capital charges at a fixed rate
over the useful life of the control system.
2. Accelerated methods which apply the capital charges at a declining
rate over the useful life, on the theory that aging or loss in value of
equipment occurs to a greater degree on new equipment than on old
equipment.
3. Methods which relate capital charges to some measure of equipment
usage. These methods are seldom applied to processing equipment.
The most common example is mileage-based depreciation of
automobiles.
Of the two kinds of methods applicable to processing equipment, the
most commonly used is the straight line method and it is the one used for the
data presented in this report. Reasons for its common use are:
1. It is easy to understand and calculate.
2. It is thought by many to be the best approximation to the rate of
obsolescence of process equipment.
3. It makes alternative control systems comparable on an annualized
cost basis since the capital charges based upon this method are
constant from year to year.
Once the decision has been made to use this method, the only critical
issue is what value to use for the useful life of the control system. The useful
life of any control system is, in reality, a composite of the useful lives of its
component parts. Some of those parts have relatively long lives, others
relatively short lives. The value chosen for the economic evaluation of a control
system depends upon: the nature of the primary control device, the differences
in expected useful life of similar equipment from different manufacturers, the
maintenance practices of the owning firm, the battery limits defined for the
system, the number and kind of structures built, and the accounting practices
of the owning firm, among others. For these reasons, the value chosen will vary
from firm to firm even for similar systems.
Taxes may also play a part in the determination of useful life. Under
normal circumstances, control systems are depreciated over their normal useful
lives. They may, however, be depreciated for tax purposes at an accelerated
rate. Under certain circumstances, defined by the Internal Revenue Service, all
398
-------
or part of the air pollution control equipment may be amortized over a sixty
month period. In most cases, this period is much shorter than the normal useful
life. Accelerated depreciation for tax purposes, especially the sixty month
amortization, has the effect of decreasing effective operating cost by deferring
tax payments into the future. The discounted value of the cash outflow caused
by the operation of the pollution control system is thereby reduced.
The money market at the time of equipment purchase is another
important variable in the determination of capital charges. The rate at which
money is available varies widely from firm to firm as well as with overall
economic considerations. The cost of capital for financing by means other than
borrowing also varies over a wide range from firm to firm. Variations in the
cost of financing can be large enough to affect the choice between alternative
control systems.
For the purpose of presenting the annual operating cost data in this
report, it was decided to use the same fixed percentage of total installed cost as
the capital charge for all of the applications studied. The rate chosen was 10%.
It was based upon an estimated useful equipment life of 15 to 20 years, debt
capital availability at 6 to 8%, and a correction for the tax incentives available
to installers of pollution control hardware of 2 to 4%. Although the rate chosen
is a good general estimate, it does not purport to be the correct rate for any
specific situation. It is used only as a good estimate to assist the cost
presentations in this report.
2. DERIVED CAPITAL COST INDICES
In each of the process applications discussed in the previous section of this
report, capital costs have been presented for two different sizes of equipment.
This permits development and evaluation of a mathematical expression for
capital cost as a function of size for each application. The mathematical form
chosen was the expotential form usually used for relating cost and size of
equipment.
Capital Cost = K (Size)x
Where
K and x are constants, and
Size is the plant capacity of the process to which the abatement
equipment is being applied.
This relationship assumes that a log-log plot of cost and size is a straight line.
For most types of equipment, this assumption is good.
399
-------
The constants K and x were evaluated by computer for each abatement
application studied. Calculations were made for each of the three capital cost
categories presented in each application:
1. Collector only
2. Collector plus auxiliaries
3. Turnkey system
Calculations were made using the computer program listed in Dartmouth Basic
Language in Table 150.
The units of the "Size" term in the equation for each application are the
same as those used in the prior discussion of that application. They are
summarized in Table 151.
The results of these calculations for generating capital costs in dollars, are
presented in the following tables:
Process Area Table Numbers
Rendering 152 157
FCC 158 159
Asphalt Batching 160 161
BOF Steelmaking 162 164
Coal Cleaning 165
Brick and Tile 166-167
Copper Smelting 168 - 170
Bark Boilers 171 172
Ferroalloys 173-176
Also shown on these tables are the ratios of turnkey system cost to collector
cost, total equipment cost to collector cost, and turnkey system cost to total
equipment cost.
Generalization of the results of these calculations is difficult. Calculated
values of the exponents for the power function vary from 0.165 to 1.069. No
pattern seems apparent. The only general conclusion which can be drawn is
that, on average, the cost of pollution control equipment goes up faster with
size than the 0.6 exponent usually assumed.
The use of the derived capital cost equations outside the range of the data
from which they were calculated is valid within certain limitations. Very small
400
-------
equipment installations tend to have relatively high capital costs which do not
correlate well with size. Small systems cost roughly the same regard less of the
treated gas throughput. Very large systems are frequently based on different
designs than their smaller counterparts, or are composed of several smaller units
which are joined together. Cost correlations based upon data from smaller units
consequently will be inaccurate for these larger sizes. Numerical values for
these large and small limitations depend upon both the nature of the abatement
equipment and the nature of the process to which it is applied. Generalizations
of these numerical values can be made, however, and they are presented below
as guidelines.
Small Limit, ACFM Large Limit, ACFM
Scrubbers 2,000 100,000
Fabric Filters 2,000 -
Precipitators 50,000 -
Incinerators 2,000 50,000
The basic capital cost data collected were also used to calculate the cost
per SCFM for each application. Results of these calculations are presented in
the following tables:
Process Area Table Numbers
Rendering 177 - 182
FCC 183 184
Asphalt Batching 185 186
EOF Steelmaking 187 - 189
Coal Cleaning 190
Brick and Tile 191-192
Copper Smelting 193 195
Bark Boilers 196 197
Ferroalloys 198 201
401
-------
TABLE 150
COMPUTER PROGRAM FOR
COST INDICES CALCULATIONS
IGCA 15:43 08/14/72
100 INPUT J5
110 F$ = " -"
120 FILES COST
130 INPUT #1,T,NS
140 INPUT #1,E$,C$
150 IF J-l GOTO 230
160 PRINT USING 520,T
170 PRINT
180 PRINT USING 530,N$
185 PRINT
187 PRINT
188 PRINT
190 PRINT
200 PRINT USING 550,"COLLECTOR TYPE"," K»"," X""," B/A"," C/A"," C/B"
210
230 PRINT
240 FOR M = 1 TO 4
250 FOR N = 1 TO 2
260 INPUT #1, A(M,N)
270 NEXT N
280 NEXT M
290 FOR N = 1 TO 2
310 NEXT N
320 FOR M - 1 TO 3
330 XCM) = (LOGCACM,1))-LOGCACM,2)))/CLOG(AC4,1))-LOG(AC4,2)))
340 PCM) = CLOGCACM,1)) + LOG(ACM,2)))-XCM)5!CLOGCAC4,1)) + LOGCA(4,2)))
350 PCM) = EXPCPCM)/2)
360 NEXT M
370 FOR N = 1 TO 2
375 RC1,N)=AC2,N)/AC1,N)
380 RC2,N) = AC3,N)/AC1,N)
390 RC3,N)= AC3,N)/AC2,N)
400 NEXT N
410 PRINT USING 560,E$
415 PRINT USING 560,C$
420 PRINT USING 540, "COLLECTOR ONLYCA)", PCD , XQ), F$ , F$ , F$
430 PRINT USING 540,"TOTAL EQUIPMENTCB)",PC2),XC2),F$,F$,F$
440 PRINT USING 540,"TURNKEYCC)",PC3),XC3),F$,F$,F$
450 PRINT
460 PRINT USING 540," SMALL",F$,F$,RCl,1),RC2,1),RC3,D
470 PRINT USING 540," LARGE",F$,F$,RC1,2),RC2,2),RC3,2)
480 PRINT
490 IF END #1 GOTO 650
500 J = 1
510 GOTO 140
402
-------
520: TABLE #H
530: DERIVED COST INDICES FOR HHHHHH
########
540: HHHWHHHWiH ####### #.«## #.#*#
550: «m###H###Htt#HH### #«##### ###**## #tttt#«#tt «#####
######
560: #tt###
570: #tttt
580 PRINT
590 PRINT
600 PRINT " "FOR USE IN EQUATION COST = K"(S I ZE)"EXP(X)"
610 FOR N = 1 TO 30
620 PRINT
630 NEXT N
640 END
650 FOR Y=l TO 12
660 PRINT
670 NEXT Y
680 GOTO 600
READY
403
-------
TABLE 151
UNITS OF PLANT SIZE FOR EACH PROCESS AREA
Process Area
Rendering
Fluid Catalytic Cracking
Asphalt Batching
BOF Steelmaking
Coal Cleaning
Brick and Tile Kilns
Copper Smelting
Bark Boilers
Ferroalloys
Plant Size Units
ACFM exhaust rate
bbls. combined feed/stream day
ton/hr hot mix product
ton/heat product
ton/hr dried coal product
ton/day product
ton/day product
Ib steam/hr
megawatts
404
-------
TABLE 152
DERIVED COST INDICES FOR RENDERING COOKERS
COLLECTOR TYPE
WET SCRUBBERS
MED. EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEYCCO
SMALL
LARGE
WET SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
51
168?
2297
_
"
50
1335
2020
_
X5:
.468
.231
.266
_
"""
.511
.272
.292
_
B/A
_
-
-
5.177
4.130
_
_
-
4.071
3.239
C/A
_
_
-
9.330
7-699
_
-
-
7.223
5.859
C/B
_
_
-
1.802
1.864
„
_
-
1.774
1.809
:FOR USE IN EQUATION COST = K-(SIZE)"EXP(X)
405
-------
TABLE 153
DERIVED COST INDICES FOR RENDERING ROOM VENTS
COLLECTOR TYPE
WET SCRUBBERS
MED. EFFICIENCY
COLLECTOR ONLYCA)
TOTAL EQUIPMENTCB)
TURNKEY(C)
SMALL
LARGE
WET SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
42
733
1936
—
46
655
1719
-
X-
.510
.310
.282
-
.521
.333
.303
-
B/A
3.520
2.587
-
3.135
2.3^7
C/A
_
7.460
5.256
—
6.486
4.636
C/B
-
2.120
2.032
-
2.069
1.976
:FOR USE IN EQUATION COST = K::(S IZE)"EXPCX)
406
-------
TABLE
DERIVED COST INDICES FOR RENDERING COMBINED VENTS
COLLECTOR TYPE
WET SCRUBBERS
MED. EFFICIENCY
COLLECTOR ONLYCA)
TOTAL EQUIPMENTCB)
TURNKEY(C)
SMALL
LARGE
WET SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLYCA)
TOTAL EQUIPMENTCB)
TURNKEYCC)
SMALL
LARGE
K"
11
698
776
-
17
501
639
-
x::
.640
.330
.390
_
"
.629
.382
.423
_
B/A
_
_
-
4.429
2.927
_
_
-
3.4rJ5
2.481
C/A
_
_
-
8.253
5.908
_
_
-
6.286
4.770
C/B
„
_
-
1.864
2.019
_
_
-
1.819
1.922
:FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
407
-------
TABLE 155
DERIVED COST INDICES FOR RENDERING COOKERS
COLLECTOR TYPE
INCINERATORS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCB)
TURNKEYCC)
SMALL
LARGE
K"
1314
1347
4278
__
"
X"
.249
.258
.197
_
"
B/A
-
-
-
1.098
1.107
C/A
-
-
-
2.198
2.097
C/B
-
-
-
2.002
1.894
"FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
408
-------
TABLE 156
DERIVED COST INDICES FOR RENDERING ROOM VENTS
COLLECTOR TYPE
INCINERATORS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCB)
TURNKEYCC)
SMALL
LARGE
K"
471
438
1464
_
X"
.382
.401
.332
_
"
B/A
_
_
-
1.089
1.123
C/A
_
_
-
2.085
1.931
C/B
^
_
-
1.915
1.720
"FOR USE IN EQUATION COST = K»(SIZE)"EXP(X)
409
-------
TABLE 157
DERIVED COST INDICES FOR RENDERING COMBINED VENTS
COLLECTOR TYPE
INCINERATORS
HIGH EFFICIENCY
COLLECTOR ONLYCA}
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
283
264
963
_
x!!
.429
.451
.375
_
"
B/A
-
-
-
1.118
1.151
C/A
-
-
-
2.141
1.992
C/B
—
-
-
1.915
1.731
"FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
410
-------
TABLE 158
DERIVED COST INDICES FOR FCC UNITS
COLLECTOR TYPE
PRECIPITATOR
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(O)
TURNKEY(C)
SHALL
LARGE
K*
o5
231
438
—
X"
.738
.661
.692
_
"
B/A
-
-
-
1.331
1.179
C/A
-
-
-
3.369
3.133
C/li
-
-
-
2.530
2.657
"FOR USE IN EOUATION COST = K"(SIZE)-EXP(X)
411
-------
TABLE 159
DERIVED COST INDICES FOR FCC UNITS
COLLECTOR TYPE
CYCLONE
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
•
K"
1
2
4
—
~
X"
1.203
1.147
1.105
—
"•
U/A
-
-
-
1.141
1.044
C/A
-
-
-
1.435
1.231
C/B
-
-
—
1.258
1.179
"FOR USE IN EQUATION COST = K"(SIZE)"EXPCX)
412
-------
TABLE 160
DERIVED COST INDICES FOR ASPHALT BATCHING
COLLECTOR TYPE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENTCS)
TURNKEY (C)
SMALL
LARGE
f
K"
12914
16637
23583
_
X"
.294
.278
.275
_
"
B/A
_
-
-
1.201
1.189
C/A
_
_
-
1.676
1.654
C/3
_
_
-
1.395
1.392
-FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
413
-------
TABLE
DERIVED COST INDICES FOR ASPHALT BATCHING
COLLECTOR TYPE
WET SCRUBBERS
MED. EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
WET SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
2577
4169
10036
_
—
2049
3396
9829
_
X"
.294
.351
.316
«.
—
.387
.436
.364
_
B/A
-
-
-
2.104
2.189
-
-
-
2.072
2.143
C/A
-
-
-
4.726
4.800
_
-
-
4.318
4.251
C/B
-
-
-
2.246
2.193
—
-
-
2.084
1.983
:FOR USE IN EQUATION COST = K"(S IZE)!JEXPCX)
414
-------
TABLE 162
DERIVED COST INDICES FOR BOF STEELMAKING
COLLECTOR TYPE
PRF.CIPITATOR
MED. EFFICIENCY
COLLECTOR ONLYCA)
TOTAL EQUIPMENTCB}1"
TURNKEY (C)
SMALL
LARGE
PRECIPITATOR
MIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EOUIPMENTCB?"
TURNKEY(C)
SMALL
LARGE
K"
9331
0
590734
—
10957
0
659736
~"
X"
.887
.000
.467
~
.841
.000
.442
^
B/A
-
-
™
.000
. 000
-
-
—
. 000
.000
C/A
-
-
"
7. 9 64
6. 244
-
-
0.371
. 641
C/LS
-
-
-
-
™
"FOR USE IN EQUATION COST = K"CS I ZE)'"EXP(X)
""TOTAL EQUIPMENT COST NOT AVAILABLE
415
-------
TABLE 163
DERIVED COST INDICES FOR BOF STEELMAKING
COLLECTOR TYPE
WET SCRUBBER, OPEN HOOD
MED. EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCB)
TURNKEY(C)
SMALL
LARGE
WET SCRUBBER, OPEN HOOD
HIGH EFFICIENCY
COLLECTOR ONLYCA)
TOTAL EQUIPMENTCB)
TURNKEYCO
SMALL
LARGE
K::
13461
294677
713875
—
13461
296702
721013
_
X"
.619
.461
.400
—
—
.619
.461
.399
_
B/A
-
-
-
10.028
9.150
-
-
-
10.067
9.183
C/A
-
-
-
17-971
15.829
-
-
-
18.033
15.871
C/B
-
-
-
1.792
1.730
-
-
-
1.791
1.728
:FOR USE IN EQUATION COST = K::( SI ZE)"EXPCX)
416
-------
TABLE 164
DERIVED COST INDICES FOR I30F STEELMAKING
COLLECTOR TYPE
WET SCRUBBER, CLOSED HO
MED. EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)»"
TURNKEY (C)
CMAI 1
I Apflp
WET SCRUBBER, CLOSED H0(
HIGH EFFICIENCY
COLLECTOR ONLY(AJ)
TOTAL EQUIPMENT(B)""
TURNKEYCO
SMALL
i ADTP
i;;;
)D
563
0
643736
>n
568
227623
1055911
X"
1.069
.000
.328
1.069
.473
.376
B/A
. 000
.000
'* #» •» *» *»
C/A
2y . 03o
lo. o90
60.455
40.442
C/U
_
" ' "'
2.863
2.705
!FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
!TOTAL EQUIPMENT COST NOT AVAILABLE
417
-------
TABLE 165
DERIVED COST INDICES FOR COAL CLEANING
COLLECTOR TYPE
WET SCRUBBERS
MED, EFFICIENCY
COLLECTOR ONLYCA)
TOTAL EQUIPMEIMTCB;>
TURNKEY(C)
SMALL
LARGE
WET SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLYCA)
TOTAL EQUIPMENTCB)
TURNKEY(C)
SMALL
LARGE
K::
196
254
1103
__
—
189
375
1638
_
X"
.995
1.049
.917
_
—
.999
.981
.852
_
B/A
-
-
-
1.832
1.9M5
_
-
-
1.765
1.730
C/A
-
-
—
3.418
3.138
-
-
-
3.385
2.880
C/B
-
-
—
1.865
1.613
-
-
-
1.918
1.665
!FOR USE IN EQUATION COST = K"CSIZE)"EXP(X)
418
-------
TABLE 166
DERIVED COST INDICES FOR BRICK AMD TILE KILNS
COLLECTOR TYPE
WET SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLYCA}
TOTAL EQUIPMENTCFO
TURNKEYCC)
SMALL
LARGE
K"
1196
1195
22702
-
x:-
.529
.607
.295
_
"
b/A
_
_
-
1.428
1.533
C/A
_
_
-
6.1*147
5.200
C/B
_
_
-
4.516
3.393
"FOR USE IN EQUATION COST = K"(S I ZE)"f.AP(X)
419
-------
TABU- 16?
DERIVED COST INDICES FOR BRICK AND TILE KILNS
COLLECTOR TYPE
INCINERATORS
HIGH EFFICIENCY
COLLECTOR ONLYCA)
TOTAL EQUIPMENT(B)
TURNKEYCC)
SMALL
LARGE
K-
3018
3242
168B1
_
"
X-
.613
.646
.476
_
~
B/A
-
-
-
1.245
1.282
C/A
-
-
-
2.965
2.613
C/B
-
-
—
2.382
2.038
!FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
420
-------
TABLE 168
DERIVED COST INDICES FOR COPPER ROASTING FURNACE
COLLECTOR TYPE
COMBINED SYSTEM
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EOUIPHENT(B)
TURNKEYCC)
SMALL
LARGE
K"
195»
3127
5908
_
X"
.796
.758
.705
_
"
B/A
-
-
-
1.281
1.P33
C/A
-
-
-
1.795
1.641
C/B
-
—
-
1.401
1.331
"FOR USE IN EQUATION COST = K«CSIZE)"EXP(X)
421
-------
TABLE 169
DERIVED COST INDICES FOR COPPER REV. FURNACES
COLLECTOR TYPE
PRECIPITATORS
MED. EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
PRECIPITATORS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCB)
TURNKEYCC)
SMALL
LARGE
K"
a 60
isai
4570
_
'~
U47S
4797
20276
-
X"
.88b
.830
.760
_
™
.651
.671
.5^0
_
B/A
_
_
-
1.299
1-232
_
-
-
1.211
1.23^
C/A
-
-
_
2.^78
2.205
_
_
-
2.473
2.254
C/B
—
-
-
1.907
1.790
_
_
-
2.042
1.827
CFOR USE IN EQUATION COST = K"(S IZE^/::EXPCX)
422
-------
TABLE 170
DERIVED COST INDICES FOR COPPER REV. FURNACES
COLLECTOR TYPE
WET SCRUBBERS
MED. EFFICIENCY
COLLECTOR ONLYCA;
TOTAL EOUIPKENT(B)
TURNKEY(C)
SMALL
LARGE
WET SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLYf A)
TOTAL EQUIPMENT(B)
TURNKEYCC)
SMALL
LARGE
K"
980
694
1397
_
"
980
763
1711
_
X"
.514
.904
.834
_
^
.614
.909
.825
—
B/A
_
-
-
4.030
5.257
_
-
-
4.572
5.993
C/A
_
-
-
5.320
6.507
_
-
-
6.197
7.522
C/B
_
-
-
1.320
1.238
_
_
-
1.356
1.255
:FOR USE IN EQUATION COST = K"CSIZE;"EXP(X)
423
-------
TABLE 171
DERIVED COST INDICES FOR BARK BOILERS
COLLECTOR TYPE
PRECIPITATORS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTS)
TURNKEYCCJ)
SMALL
LARGE
K-
19
^6
1^7
__
—
x»
.7514
.712
.659
_
^
B/A
-
-
—
1.437
1.371
C/A
-
-
—
2.537
2.284
C/B
-
-
—
1.765
1.666
"FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
424
-------
TABLE 172
DERIVED COST INDICES FOR BARK BOILERS
COLLECTOR TYPE
WET SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEYCC)
SMALL
LARGE
K"
.37
5.63
14.99
_
"
X*'
"
.986
.819
.818
—
™
E/A
_
—
-
2.257
1.879
C/A
_
-
-
5.892
4.899
C/B
_
_
-
2.611
2.608
!FOR USE IN EQUATION COST = K:c(S J ZE)"EXPCX)
425
-------
TABLE 173
DERIVED COST INDICES FOR FERROSILICON FURNACES
COLLECTOR TYPE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCB)
TURNKEYCC)
SMALL
LARGE
K:c
13466
17719
71871
_
*•"
X"
.974
.974
.818
_
~"
B/A
-
-
-
1.315
1.315
C/A
-
-
—
3.729
3.005
C/B
-
-
-
2.835
2.285
"FOR USE IN EQUATION COST = K"(S1ZEV'EXPCX)
426
-------
TABLE 174
DERIVED COST INDICES FOR FERROCHROME FURNACES
COLLECTOR TYPE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
20591
29985
.126254
_
"
X"
.771
.733
.551
_
"
B/A
—
-
-
1.3^7
1.282
C/A
-
-
-
3.883
2.904
C/B
-
-
-
2.882
2.265
"FOR USE IN EQUATION COST = K::(S IZE):SEXP(X)
427
-------
TABLE 175
DERIVED COST INDICES FOR FERROSILICON FURNACES
COLLECTOR TYPE
WET SCRUBBERS
MED. EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUJPMENT(B)
TURNKEYCC)
SMALL
LARGE
WET SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCB)
TURNKEY(C)
SMALL
LARGE
K"
5382
357U,:
306157
_
_
5382
513 :8
336593
_
X."
.873
.678
.533
_
""*
.873
.635
.53^
_
B/A
_
-
-
4.226
3.222
—
-
-
5.515
3.965
C/A
-
-
-
25.970
16.197
_
-
-
28.632
17.887
C/B
_
-
-
6.145
5.028
_
—
-
5.192
4.511
!SFOR USE IN EQUATION COST = K«CS IZE)-EXP(X)
428
-------
TAB LF 176
DERIVED COST INDICES FOR FERROCHROME FURNACES
COLLECTOR TYPE
WET SCRUBBERS
MED. EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCBJ)
TURNKEYCO
SMALL
LARGE
WET SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCB)
TURNKEYCO
SMALL
LARGE
K"
6816
22793
213053
-
6740
58403
336166
-
X-
.590
.661
.^59
_
"
.653
.50Q
.436
_
B/A
—
-
-
3.878
4.262
_
-
-
6.424
5.311
C/A
_
_
-
23.825
20.04S
_
—
-
31.794
23.881
C/B
_
_
-
6.143
4.704
_
_
-
4.949
4.497
!CFOR USE IN EQUATION COST = K"CSIZE)5!EXPCX)
429
-------
TABLE 177
DERIVED COST PER SCFM" FOR RENDERING COOKERS
COLLECTOR TYPE
WET SCRUBBER
MED. EFFICIENCY
GAS FLOW, SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
WET S CRUDE* ER
HIGH EFFICIENCY
GAS FLOW, SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
SMALL
2336
.86
4.43
7.99
2336
1.19
4.84
8.59
LARGE
6064
.52
2.13
3.97
6064
.75
2.42
4.37
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
430
-------
TABLE 178
DERIVED COST PER SCFM" FOR RENDERING ROOM VENTS
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBER
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY 'SYSTEM
2891
.86
3.03
6.42
.40
1.05
2.12
WET SCRUBBER
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
2891
1.04
3.26
6.74
13491
.50
1.17
2.31
:BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
431
-------
TABLE 179
DERIVED COST PER SCFM" FOR RENDERING COMBINED VENTS
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBER
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
5230
.52
2.31
'1.31
19600
.33
.96
WET SCRUBBER
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY 'SYSTEM
5230
.75
2.59
4.71
19600
.46
1.15
2.21
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
432
-------
TABLE 180
DERIVED COST PER SCFM" FOR RENDERING COOKERS
COLLECTOR TYPE
SMALL
LARGE
INCINERATORS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY 'SYSTEM
1918
4.56
5.01
10.03
4809
2.29
2.53
4.80
"BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
433
-------
TABLE l8l
DERIVED COST PER 5CFM" FOR RENDERING ROOM VENTS
COLLECTOR TYPE
SMALL
LARGE
INCINERATORS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
2891
3.46
3.77
7.21
13*191
1.33
1.50
2.58
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
434
-------
TABLE 182
DERIVED COST PER SCFM" FOR RENDERING COMBINED VENTS
COLLECTOR TYPE
SMALL
LARGE
INCINERATORS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY 'SYSTEM
1803
2.29
2.56
4.90
18210
1.07
1.23
2.13
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
435
-------
TABLE 183
DERIVED COST PER SCFM" FOR FCC UNITS
COLLECTOR TYPE
SMALL
LARGE
PRECIPITATOR
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
39892
1.96
2.61
6.61
190914
1.31
1.5*
4.09
"BASED ON
INLET
SCFM AT 70 DEG.
INCLUDING V.'ATER
F AT COLLECTOR
VAPOR
436
-------
TABLE 181
DERIVED COST PER SCFM" FOR FCC UNITS
COLLECTOR TYPE
SMALL
LARGE
CYCLONE
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
28000
3.04
3.^7
1.37
133300
4.23
4.41
5.20
''-BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
437
-------
TABLE 185
DERIVED COST PER SCFM" FOR ASPHALT BATCHING
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
20051
2.49
2.99
4.17
28096
2.18
2.59
3.60
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
438
-------
TABLE 186
DERIVED COST PER SCFM" FOR ASPHALT BATCHING
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBERS
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY 'SYSTEM
20022
.50
1.05
2.35
28070
.44
.95
2.09
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
20022
.61
1.26
2.63
28070
.57
1.22
2.41
:BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
439
-------
TABLE 187
DERIVED COST PER SCFM" FOR DOF STEELMAKING
COLLECTOR TYPE
SMALL
LARGE
PRECIPITATOR
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT1
TURNKEY 'SYSTEM
286486
2.61
.no
20.77
187027
2.57
.00
16.02
PRECIPITATOR
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT1
TURNKEY SYSTEM
286486
2.44
.00
20.46
487027
2.34
.00
15.55
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
-"TOTAL EQUIPMENT COST NOT AVAILABLE
440
-------
TABLE 188
DERIVED COST PER SCFM" FOR BOF STEELMAKING
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBER,OPEN HOOD
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY 'SYSTEM
1485811
1.93
19.38
34.73
265000
1.55
14.20
24.56
WET SCRUBBER,OPEN HOOD
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
148584
1.93
19.45
34.85
265000
1.55
14.25
24.62
:BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
441
-------
TABLE 189
DEPsIVED COST PER SCFM" FOR DOF STEELMAKING
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBER,CLOSED HOOD
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT::::
TURNKEY 'SYSTEM
40805
2.74
.00
79.60
72699
2.86
.00
54.02
WET SCRUBBER,CLOSED HOOD
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
40805
2.74
57.88
165.71
72699
2.86
42.75
115.65
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
""TOTAL EQUIPMENT COST NOT AVAILABLE
442
-------
TABLE 190
DERIVED COST PER SCFM" FOR COAL CLEANING
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBERS
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
15^923
.74
1.35
2.52
464769
.73
1.42
2.30
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
154923
.73
1.28
2.46
464769
.73
1.26
2.09
5!BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
443
-------
TABLE 191
DERIVED COST PER SCFM" FOR BRICK AND TILE KILNS
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
10743
1.27
1.8?
8.22
25784
.86
1.32
4.49
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
444
-------
TABLE 190
DERIVED COST PER SCFM" FOR COAL CLEANING
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBERS
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
15^923
.74
1.35
2.52
464769
.73
1.42
2.30
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
154923
.73
1.28
2.46
464769
.73
1.26
2.09
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
443
-------
TABLE 191
DERIVED COST PER 5CFM:c FOR BRICK AND TILE KILNS
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
10743
1.27
1.8?
8.22
25784
.86
1.32
4.49
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
444
-------
TABLE 192
DERIVED COST PER SCFM- FOR BRICK AND TILE KILNS
COLLECTOR TYPE
SMALL
LARGE
INCINERATORS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
10743
4.74
5.90
1-4.05
257H4
3.46
4.44
9.05
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
445
-------
TABLE 193
DERIVED COST PER SCFM- FOR COPPER ROASTING FURNACE
COLLECTOR TYPE
SMALL
LARGE
COMBINED SYSTEM
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
13360
13.75
17.61
35333
11.35
14.00
18.63
"BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
446
-------
TABLE 194
DERIVED COST PER SCFM" FOR COPPER REV. FURNACES
COLLECTOR TYPE
SMALL
LARGE
PRECIPITATORS
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
52000
3.38
4.38
8.36
130000
3.05
3.75
6.71
PRECIPITATORb
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
52000
4.25
5.15
10.51
1^0000
3.09
3.B1
6.96
'BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLF.T. INCLUDING WATER VAPOR
447
-------
TABLE 195
DERIVED COST PER SCFM" FOR COPPER REV. FURNACES
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBERS
MEDc EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
52000
.75
3.00
3.96
130000
.52
2.75
3.^0
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
52000
.75
130000
.52
3.13
3.93
"BASED ON SCFM AT 70 DHG. F AT COLLECTOR
INLET INCLUDING WATb.R VAPOR
448
-------
TABLE 196
DERIVED COST PER SCFM" FOR BARK BOILERS
COLLECTOR TYPE
SMALL
LARGE
PRECIPITATORS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
4560-,
2.51
3.61
6.37
136814
1.92
2.63
4.38
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
449
-------
TABLE 197
DERIVED COST PER SCFM" FOR BARK BOILERS
COLLECTOR TYPE
SMA LI-
LARGE
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
40305
.78
1.76
4.59
120914
.77
1.44
3.76
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
450
-------
TABLE 198
DERIVED COST PER SCFM" FOR FERROSILICON FURNACES
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
36697
3.46
4.5b
12.89
146902
3.33
4.38
10.01
"BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
451
-------
TABLE 199
DERIVED COST PER SCFM" FOR KERROCHROME FURMACES
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
18719
5.46
7.36
21.21
70479
4.02
5.15
11.67
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
452
-------
TABLE 200
DERIVED COST PER SCFM" FOR FERROSILICON FURNACES
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBERS
MEDo EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
36697
1.10
4.63
28.145
145750
.93
2.95
14.99
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
36697
1.10
6.04
31.37
145750
o93
3.67
16.56
:BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
453
-------
TABLE 201
DERIVED COST PER >CFM" FOR FERROCHROME FURNACES
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBERS
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY "SYSTEM
18719
1.24
4.81
29.56
70479
.72
3.06
14.40
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL. EQUIPMENT
TURNKEY SYSTEM
18719
1.40
8.99
44.50
70479
.88
4.68
21.04
"BASED ON SCFM AT 70 DHG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
454
-------
3. OPERATING COSTS AT VARIOUS UTILITY COST LEVELS
The annual operating costs for air pollution control equipment for specific
processing applications were calculated by using an average value of the unit
cost for the various operating cost items. These costs were summarized in tables
and the direct operating cost and total cost curves (based on two different
plant capacities) were then plotted. In this section, the same procedure has
been used with the single exception that a high and low value of the unit costs
have been used instead of the average one to calculate direct operating costs.
The high, intermediate, and low values for the various unit costs are
summarized in Table 202. The total cost data are tabulated in Tables 203 - 252.
The subsequent cost curves are the upper and lower limits of cost versus plant
capacity, and are contained in Figures 107 - 160.
455
-------
TABLE 202
VARIOUS VALUES FOR UNIT OPERATING COSTS
Unit Cost Item High Average _Low
Operating Labor
Operator $ 9/hr $ 6/hr $ 4/hr
Supervisor $12/hr $ 8/hr $ 6/hr
Maintenance Labor $ 9/hr $ 6/hr $ 4/hr
Utilities
Electric Power $.020/kw-hr $.011/kw-hr $.005/kw-hr
Fuel $1.25/MM BTU $.80/MM BTU $.50/MM BTU
Water (Process) $0.50/M gal $.25/M gal $.10/Mgal
Water (Cooling) $0.09/M gal $.05/M gal $.02/M gal
456
-------
TABLE 203
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR RENDERING COOKERS AND HOODS
Low Unit Cost
Oneratina Onct ItPm
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify * KMn04
Borax
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2 600
$4/hr
$6/hr
$4/hr
:.005/kw-h
1.10/M gal
!.38/lb
;.0625/lb
LA Process Wt.
Small
1,674
20
1,694
1,650
136
.
48
114,900
101,250
216,334
219,678
1,866
221,544
Large
-
1,750
28
1.778
1,750
222
"~
115
269,040
243,000
512,377
515,905
2,406
518,311
High Efficiency
Small
1,674
20
1 6Q4
1,700
164
-.
48
172,368
101,250
273,830
277,224
2,006
279,230
Large
1,750
28
1.778
1,800
251
_
115
410,400
243,000
653,766
657,344
2,651
659,995
* Not all quotes used this system of chemicals. Based on only one
chemical cost quote, 2 quotes for other operating cost
-------
TABLE 204
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR RENDERING COOKERS AND HOODS
01
00
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify * KMn04
Borax
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$9/hr
$12/hr
$9/hr
$.020/kw-l
$.50/M ga;
$.38/lb
$.0625/lb
LA Process Wt.
Small
3,768
40
3,808
1,650
-
r 545
-
224
114,900
101,250
216,919
222,377
1,866
224,243
Large
3,937
57
3,994
1,750
-
890
-
578
269,040
243,000
513,508
519,252
2,406
521,658
High Efficiency
Small
3,768
40
3,808
1,700
-
658
-
22",
172,368
101^250
274,500
280,008
2,006
282,014
Large
3,937
57
3,994
1,800
-
1,007
-
578
410,400
243 000
654,385
660,779
2,651
663,430
* Not all quotes used this system of chemicals. Based on only one
chemical cost quote, 2 quotes for other operating cost
-------
FIGURE 107
ANNUAL COSTS FOR WET SCRUBBERS
FOR RENDERING COOKERS AND HOODS
(Low Unit Cost)
V)
Q
I
O
z
V)
O
u
<
z
<
1000
700
600
500
400
300
200
HIGH EFFICIENCY
100
LA-PROCESS WEIGHT
4 5 6 7 8 9 10 20
PLANT CAPACITY, THOUSANDS OF POUNDS PER BATCH
459
-------
V)
CC
O
Q
V)
O
V)
O
U
<
z
<
FIGURE 108
ANNUAL COSTS FOR WET SCRUBBERS
FOR RENDERING COOKERS AND HOODS
(High Unit Cost)
1000
700
600
500
400
300
200
100
HIGH EFFICIENCY
/
/
x
LA-PROCESS WEIGHT
5 6 7 8 9 10
20
PLANT CAPACITY, THOUSANDS OF POUNDS PER BATCH
460
-------
TABLE 205
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR RENDERING ROOM VENTS
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify * KMn04
Borax
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$4/hr
$6/hr
$4/hr
$.005/kw-
$.10/M ga
$.38/lb
$.0625/lb
LA Process Wt.
Small
1,163
17
1,180
1,100
—
r 146
67
123,200
111,375
234,788
237,068
1,502
238,570
Large
1,226
22
1,248
1,200
__
466
295
541,728
500,000
1,042,489
1,044,937
2,533
1,047,470
High Efficiency
Small
1,163
17
1,180
1,117
.
166
67
184,680
111,375
296,288
298,585
1,595
300,180
Large
1,226
22
1,248
1,268
570
295
820,000
500,000
1,320,865
1,323,381
2,774
1,326,155
* Not all quotes used this system of chemicals. Based on one quote
for chemical, three for other cost.
-------
TABLE 206
&
NJ
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR RENDERING ROOM VENTS
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify * KMn04
_ ....... Borax
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$9/ hr
$12/hr
$9/hr
$.020/kw-
$.50/M ga
$.38/lb
$.0625/lb
LA Process Wt.
Small
2,617
34
2,651
1,100
-
ir 585
336
123,200
111,375
235,496
239,247
1,502
240,749
Large
2,760
45
2,805
1,200
_
1,865
1,470
541,728
500,000
1,045,063
1,049,068
2,533
1,051,601
High Efficiency
Small
2,617
34
2,651
1,117
_
665
336
184,680
111,375
297,056
300,824
1,595
302,419
Large
2,760
45
2,805
1,268
2,283
1,476
820,000
500,000
1,323,759
1,327,822
2,774
1,330,606
* Not all quotes used this system of chemicals. Based on one
for chemical, three quotes for other costs.
quote
-------
CO
(L
O
O
u.
O
CO
O
z
O
I-
O
_l
3
z
z
<
2000
1000
700
600
500
400
300
200
100
FIGURE 109
ANNUAL COSTS FOR WET SCRUBBERS
FOR RENDERING ROOM VENTS
(Low Unit Cost)
7
7
7
Z
LA-PROCESS WEIGHT
5 6 7 8 9 10
20
PLANT CAPACITY THOUSANDS OF POUNDS PER BATCH
463
-------
V)
-------
TABLE 207
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR RENDERING COMBINED VENTS
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify * KMn04
Borax
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$4/hr
$6/hr
$4/hr
$.005/kw-I
$.10/M ga.
$.38/lb
$.0625/lb
LA Process Wt.
Small
1,600
11
1,611
1,725
r 201
91
215,870
195,750
411,912
415,248
2,253
417,501
Large
1,800
33
1,833
1,900
529
329
820,800
742,500
1,564,158
1,567,891
3,796
1,571,687
High Efficiency
Small
1,600
11
1.611
1,750
255
91
328,320
195,750
524,416
527,777
2,466
530,243
Large
1,800
33
1.833
2,000
679
329
1,231,200
742,500
.,974,708
1,978,541
4,341
1,982,882
&
Ul
* Not all quotes used this system of chemicals. Based on one quote
for chemicals, three quotes for other costs.
-------
TABLE 208
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR RENDERING COMBINED VENTS
High Unit Cost
o>
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify KMnO«
Borax
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$9/hr
$12/hr
$9/hr
f.020/kw-h
f.50/M ga]
5.38/lb
.0625/lb
LA Process Wt.
Small
3,600
22
3,622
1,725
-
809
458
215,870
195,750
412,887
418,234
2,253
420,487
Large
-
4,050
67
4,117
1,900
-
2,116
1,648
820,800
742,500
1,567,064
1,573,081
3,796
1,576,877
High Efficiency
Small
3,600
22
3,622
1,750
_
1,021
458
328,320
195,750
525,549
530,921
2,466
533,387
Large
4,050
67
4,117
2,000
.
2,718
1,648
1,231,200
742,500
1,978,066
1,984,183
4,341
1,988,524
-------
FIGURE 111
ANNUAL COSTS FOR WET SCRUBBERS
FOR RENDERING COMBINED VENTS
(Low Unit Cost)
4000
3000
2000
to
tc
O
Q
|
<
CO
O
I-
u
_l
<
z
1000
800
700
600
500
400
300
HIGH EFFICIENCY
LA-PROCESS WEIGHT
4 5 6 7 8 9 10 20
PLANT CAPACITY. THOUSANDS OF POUNDS PER BATCH
467
-------
4000
3000
2000
en
cc
O
X
I
Z
1000
800
700
600
500
400
300
FIGURE 112
ANNUAL COSTS FOR WET SCRUBBERS
FOR RENDERING COMBINED VENTS
(High Unit Cost)
HIGH EFFICIENCY
LA-PROCESS WEIGHT
4 5 6 7 8 9 10 20
PLANT CAPACITY, THOUSANDS OF POUNDS PER BATCH
468
-------
TABLE 209
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR INCINERATORS FOR RENDERING COOKERS AND HOODS
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$4/hr
$6/hr
$4/hr
$.005/kw-
$. SO/MM B'
LA Process Wt.
Small
T
'U
Large
High Efficiency
Small
520
36
556
256
166
422
158
47
3,770
3,817
4,953
1,924
6,877
Large
520
36
556
260
220
480
158
82
9,243
9,325
10,519
2,306
12,825
CD
-------
TABLE 210
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR INCINERATORS FOR RENDERING COOKERS AND HOODS
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$9/hr
$12/hr
$9/hr
$.020/kw-
$1.25/MM
LA Process Wt.
Small
ir
!TU
Large
High Efficiency
Small
1,170
72
1,242
576
166
742
158
186
9,425
9,611
11,753
1,924
13,677
Large
1,170
72
1,242
585
220
805
158
326
23,107
23,433
25,638
2,306
27,944
-------
o
Q
CO
Q
U)
O
X
8
40
30
20
10
9
8
7
6
FIGURE 113
ANNUAL COSTS FOR INCINERATORS
FOR RENDERING COOKERS AND HOODS
(Low Unit Cost)
TOTA
(OPEF
CAPIT
>
J\
LCOS1
ATINC
ALCH
X
<
x
r
r
5 COS'
ARGE
x
x^
x
X
rpn
.)
X
x
X
JS
X
X
x
X
x
/
*
*
OPERATING COST
4000
7000
10,000
20,000
PLANT CAPACITY
LB/BATCH
471
-------
FIGURE 114.
ANNUAL COSTS FOR INCINERATORS
FOR RENDERING COOKERS AND HOODS
(High Unit Cost)
40
30
20
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
cc
<
1
I
O
to
O
O
10
9
8
7
6
5
4
OPERATING COST
4000
7000
10,000
20,000
PLANT CAPACITY
LB/BATCH
472
-------
TABLE 211
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR INCINERATORS FOR RENDERING COOKER ROOM VENTS
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$4/hr
$6/hr
$4/hr
$.005/kw-
$.50/MM B
LA Process Wt.
Small
r
ru
Large
High Efficiency
Small
520
36
556
260
220
480
158
59
5,460
5,519
6,713
2,085
8,798
Large
520
36
556
320
270
590
158
279
25,545
25,824
27,128
3,476
30,604
w
-------
TABLE 212
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR INCINERATORS FOR RENDERING COOKER ROOM VENTS
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$9/hr
$12/hr
$9/hr
$.020/kw-
$1.25/MM
LA Process Wt.
Small
r
TU
Large
High Efficiency
Small
1,170
72
1,242
585
220
805
158
237
13,650
13,887
16,092
2,085
18,177
Large
1,170
72
1,242
720
270
990
158
1,117
63,862
64,979
67,369
3,476
70,845
-------
FIGURE 115
ANNUAL COSTS FOR INCINERATORS
FOR RENDERING ROOM VENTS
(Low Unit Cost)
CO
cc
O
Q
CO
Q
<
CO
O
I
O
u
40
30
20
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
10
9
8
4000
10,000
20,000
PLANT CAPACITY
LB/BATCH
475
-------
FIGURE 116
ANNUAL COSTS FOR INCINERATORS
FOR RENDERING ROOM VENTS
(High Unit Cost)
CO
oc
o
Q
CO
Q
I
o
X
100
90
80
70
60
50
40
30
20
10
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
OPERATING COST
4000
10,000
20,000
PLANT CAPACITY
LB/BATCH
476
-------
TABLE 213
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR INCINERATORS FOR RENDERING COMBINED VENTS
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$4/hr
$6/hr
$4/Lr
$.005/kw-
$. SO/MM B1
LA Process Wt.
Small
X
U
Large
High Efficiency
Small
520
36
556
256
186
442
158
82
9,086
9,168
10,324
2,355
12,679
Large
520
36
i^fi
310
235
545
158
304
34,476
34,780
36,039
3,884
39,923
-------
TABLE 214
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR INCINERATORS FOR RENDERING COMBINED VENTS
00
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
2,600
$97hr
$12/hr
$9/hr
$.020/kw-
$1.25/MM
LA Process Wt.
Small
r
TU
Large
High Efficiency
Small
1,170
. 72
1,242
576
186
762
158
,327
22,717
23,046
25,206
2,355
27,561
Large
1,170
72
1 ,242
697
235
932
158
1,217
86,190
87,407
89,739
3,884
93,623
-------
FIGURE 117
ANNUAL COSTS FOR INCINERATORS
FOR RENDERING COMBINED VENTS
(Low Unit Cost)
I
I
o
I
o
o
100
90
80
70
60
50
40
30
20
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
10
4000
10,000
PLANT CAPACITY
LB/BATCH
20,000
479
-------
FIGURE 118
ANNUAL COSTS FOR INCINERATORS
FOR RENDERING COMBINED VENTS
(High Unit Cost)
eo
cc
i
I
o
te
o
o
100
90
80
70
60
50
40
30
20
10
4000
10,000
PLANT CAPACITY
LB/BATCH
20,000
480
-------
TABLE 215
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS FOR FCC UNITS
Low Unit Cost
Onpratinn f^nct Ifpm
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
(ammonia)
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8,000
$4/hr
$6/kr
$4/hr
$.005/kw-I
$.03/lb
LA Process Wt.
Small
r
Large
200
-
200
1,312
500
1,812
7,400
7,400
11,387
-
-
-
8,940
20,327
29,739
78,117
107,856
High Efficiency
Small
200
-
200
448
150
598
2,275
2,275
7,124
_
_
_
2,160
9,284
12,357
26,357
38,714
Large
200
-
200
1,312
500
1,812
7,400
7,400
11,387
_
_
_
8,940
20,327
29,739
78,117
107,856
-------
TABLE 216
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS FOR FCC UNITS
NJ
High Unit Cost
Oneratmn Cnct Ifpm
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
(ammonia)
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8 000
$9/hr
$12/hr
$9/hr
$.020/kw-
$.03/lb
LA Process Wt.
Small
r
Large
450
-
450
2,952
750
3.702
7,400
7,400
45,549
~
-
8,940
54,489
66,041
78,117
144,158
High Efficiency
Small
450
450
1,008
225
1.233
2,275
2,275
28,500
~
-
2,160
30,660
34,618
26,357
60,975
Large
450
4^n
2,952
750
3.702
7,400
7,400
45,549
-
-
8,940
54,489
66,041
78,117
144,158
-------
200
to
cc
CO
Q
CO
o
X
o
o
100
80
60
50
40
30
20
FIGURE 119
ANNUAL COSTS FOR ELECTROSTATIC
PRECIPITATORS FOR FCC UNITS
(Low Unit Cost)
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
10
OPERATING COST
10
20
30
40
50 60
COMBINED FEED RATE, THOUSANDS
OF BARRELS PER STREAM DAY
483
-------
FIGURE 120
ANNUAL COSTS FOR ELECTROSTATIC
PRECIPITATORS FOR FCC UNITS
(High Unit Cost)
co
tc
O
Q
CO
O
CO
O
X
te
O
O
100
80
60
50
40
30
20
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
OPERATING COST
10
1 20
30
40 50 60
COMBINED FEED RATE, THOUSANDS
OF BARRELS PER STREAM DAY
484
-------
TABLE 217
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR TERTIARY CYCLONES
FOR FCC UNITS
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8^000
LA Process Wt.
Small
Large
-
1,000
-
1,000
69,340
70,340
High Efficiency
Small
-
1,000
-
1,000
12,230
13,230
Large
-
1,000
-
1,000
69,340
70,340
Ul
-------
£
CD
TABLE 218
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR TERTIARY CYCLONES
FOR FCC UNITS
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8 nnn
LA Process Wt.
Small
Large
-
1,000
-
-
1,000
69,340
70,340
High Efficiency
Small
-
1,000
-
-
1,000
12,230
13,230
Large
-
1,000
-
-
1,000
69,340
70,3.40
-------
FIGURE 121
ANNUAL COSTS FOR TERTIARY CYCLONES
FOR FCC UNITS
(Low Unit Cost)
c/}
EC
Q
I
O
X
O
O
100
80
60
50
40
30
20
TOTAL ANNUAL COST
(INCLUDES 1000/YR
OPERATING COST)
10
10
20
30
40
50 60
80 100
COMBINED FEED RATE, THOUSANDS
OF BARRELS PER STREAM DAY
487
-------
FIGURE 122
ANNUAL COSTS FOR TERTIARY CYCLONES
FOR FCC UNITS
(High Unit Cost)
100
V)
DC
o
Q
v>
O
<
V)
O
X
te
O
O
80
60
50
40
30
20
10
1
TOTAL ANf
(INCLUPES
OPERATINi
/
/
MUAL COST
1000/YR__,
3 COST) 7
/
/
/
/
/
f
/
"
0 20 30 40 50 60 80 100
COMBINED FEED RATE, THOUSANDS
OF BARRELS PER STREAM DAY
488
-------
TABLE 219
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR FABRIC COLLECTORS FOR ASPHALT BATCHING PLANTS
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Bag Replacement Per Yr .
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
960
$4/hr
$6/hr
$4/hr
I.OOS/kw-h
LA Process Wt.
Small
Large
High Efficiency
Small
180
180
200
200
2,250
2,250
1,124
1,124
3,754
8,363
12,117
Large
180
180
288
288
3,075
3,075
1,124
1,124
4,579
10,119
14,698
CO
-------
TABLE 220
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR FABRIC COLLECTORS FOR ASPHALT BATCHING PLANTS
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Bag Replacement Per Yr.
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
Qfin
$9/hr
$12/hr
$9/hr
$.020/kw-f
LA Process Wt.
Small
r
Large
High Efficiency
Small
360
360
200
200
2,250
2,250
4,500
-
4,500
7,310
8,363
15,673
Large
360
360
288
288
3,075
3,075
4,500
-
4,500
8,223
10,119
18,342
-------
FIGURE 123
ANNUAL COSTS FOR FABRIC COLLECTORS
FOR ASPHALT BATCHING PLANTS
(Low Unit Cost)
50
40
30
20
o
O
O
X
o
CJ
D
Z
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
10
OPERATING COST
60
100
200
300
400 500 600
PLANT CAPACITY
TON/HR.
491
-------
FIGURE 124
it
O
Q
V)
Q
O
I
O
O
_l
<
z
50
40
30
20
10
9
8
7
6
ANNUAL COSTS FOR FABRIC COLLECTORS
FOR ASPHALT BATCHING PLANTS
(High Unit Cost)
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
OPERATING COST
60
100
200
300
400 500 600
PLANT CAPACITY
TON/HR.
492
-------
TABLE 221
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR ASPHALT BATCHING PLANTS
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
960
$4/hr
$6/hr
$4/hr
i.OOS/kw-h
MO/H Gal
LA Process Wt.
Small
194
50
244
185
185
r 838
580
1,418
1,847
4,714
6,561
Large
188
75
263
226
226
1,257
761
2,018
2,507
5,870
8,377
High Efficiency
Small
194
50
244
194
194
1,650
684
2,334
2,772
5,260
8,032
Large
188
75
263
244
244
2,456
913
3,369
3,876
6,771
10,647
CO
CO
-------
TABLE 222
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR ASPHALT BATCHING PLANTS
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
960
$9/hr.
$12/hr.
$9/hr.
£.020/kw-l
f.SO/M Ga]
LA Process Wt.
Small
-
328
50
378
185
185
r. 3,354
. 2,900
6,254
6,817
4,714
11,531
Large
-
424
75
499
226
226
5,030
3,808
8,838
9,563
5,870
15,433
High Efficiency
Small
-
328
50
378
194
194
6,600
3,420
10,020
10,592
5,260
15,852
Large
-
424
75
499
244
244
9,827
4,568
14,395
15,138
6,771
21,909
-------
FIGURE 125
CO
cc
O
Q
LL
O
Q
O
I
8
O
<
z
<
20
10
9
8
7
ANNUAL COSTS FOR WET SCRUBBERS
FOR ASPHALT BATCHING PLANTS
(HIGH EFFICIENCY)
(Low Unit Cost)
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
OPERATING COST
60
100
200
300 400 500 600
PLANT CAPACITY TON/HR.
495
-------
FIGURE 126
ANNUAL COSTS FOR WET SCRUBBERS
FOR ASPHALT BATCHING PLANTS
(HIGH EFFICIENCY)
(High Unit Cost)
40
C/3
CC
o
Q
V)
0
I
O
30
20
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
<
Z
<
10
9
8
7
6
OPERATING COST
60
100 200 300 400 500 600
PLANT CAPACITY TON/HR.
496
-------
tABLE 223
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS FOR BOF STEELMAKING
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance (2)
Labor
Materials
Total Maintenance
Replacement Parts (3)
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7 8SO
$4/hr
$6/hr
$4/hr
5.005/kw-J
LA Process Wt.
Small
-
147,400
29,900
r 38,033
38,033
215,333
594,900
810,233
Large
-
167,400
34,200
59,863
59,863
261,463
780,072
1,041,535
High Efficiency
Small
-
147,400
29,900
38,033
38,033
215,333
586,273
801,606
Large
-
167,400
34,200
59,863
59,863
261,463
757,560
1,019,023
(1) Based upon two quotations.
(2) Based on 5% of system cost,
(3) Based on 1% of system cost,
-------
TABLE 224
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS FOR BOF STEELMAKING
00
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance ( 2 )
Labor
Materials
Total Maintenance
Replacement Parts (3)
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
7,850
$9/hr
$12/hr
$9/hr
$.020/kw-l
LA Process Wt.
Small
-
147,400
29,900
r 152,136
152,136
329,436
594,900
924,336
Large
-
167,400
34,200
239,454
239,454
441,054
780,072
1,221,126
High Efficiency
Small
-
147,400
29,900
152,136
152,136
329,436
586,273
915,709
Large
-
167,400
34,200
239,454
239,454
441,054
757,560
1,198,614
(1) Based upon two quotations.
(2) Based on 5% of system cost
(3) Based on II of system cost
-------
FIGURE 127
ANNUAL COSTS FOR PRECIPITATORS
FOR BOF STEELMAKING
(INTERMEDIATE EFFICIENCY)
(Low Unit Cost)
2000
c/)
cc.
§
u.
o
C0
o
<
v>
O
1000
800.
600
500.
400
300
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
200
OPERATING COST
100 200
PLANT CAPACITY
TONS
300
400 500 600
499
-------
FIGURE 128
ANNUAL COSTS FOR PRECIPITATORS
FOR BOF STEELMAKING
(INTERMEDIATE EFFICIENCY)
(High Unit Cost)
CO
tc.
§
a
<
00
O
I
1
2000
1000
900
700
600
500
400
300
— --]
(
fOT
OPE
:API
AL
RA
TA
CO!
TIIV
LC
ST
JG COST PLUS
HARGE)
.^
ox*^
*^
^^
^
^
OPERATING COST
i
100 200 300 400 500 60
PLANT CAPACITY
TONS
500
-------
FIGURE 129
ANNUAL COSTS FOR PRECIPITATORS
FOR BOF STEELMAKIIMG
(HIGH EFFICIENCY)
(Low Unit Cost)
2000
(a
a:
to
Q
<
to
O
I
8
1000
800
600
500
400
300
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
OPERATING COST
100
200
300
400 500 600
PLANT CAPACITY
TONS
501
-------
FIGURE 130
ANNUAL COSTS FOR PRECIPITATORS
FOR BOF STEELMAKING
(HIGH EFFICIENCY)
(High Unit Cost)
co
cc
CO
O
CO
O
I
2000
1000
900
700
600
500
400
300
TO'
(OP
CA
FAl
ER
PIT
.COST
ATING COST PLUS
AL CHARGE)
_^
>X^
*^
^
^
,J^
r~
OPERATING COST
i _i
100
200
300
400 500 600
PLANT CAPACITY
TONS
502
-------
TABLE 225
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBER SYSTEMS FOR BOF STEELMAKING
(OPEN HOOD)
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance (1)
Labor
Materials
Total Maintenance
Replacement Parts (2)
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling) (3)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7 8SO
$4/hr
$6/hr
$4/hr
1.005/kw-h
..10/M Gal
LA Process Wt.
Small
5,793
5.793
f 285,500
285,500
57,150
112,272
89,000
201,272
549,715
571,500
1,121,215
Large
5,793
5.79^
f 367,100
367.100
73,810
220,000
161,800
381,800
828,503
738,100
1,566,603
High Efficiency
Small
5,793
5,79^5
> 286,500
' 286.500
57,300
171,500
89,000
260,500
610,093
573,000
1,183,093
Large
5,793
5.793
. 367,800
367r800
73,970
275,500
161,800
437,300
884,863
739,700
1,624,563
01
8
(1) Based on 5% of
(2) Based on U of
.Closed cooling
system cost.
system cost
systems are used.
Pump HP is in power cost,
-------
TABLE 226
en
g
ANNUAL OPERATING COST DATA
' (COSTS IN $/YEAR)
FOR WET SCRUBBER SYSTEMS FOR BOF STEELMAKING
(OPEN HOOD)
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance ( 1 )
Labor
Materials
Total Maintenance
Replacement Parts (2)
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling) (3)
Chemicals, Specify -
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
/ ,«bU
$9/hr
$12/hr
$9/hr
f.020/kw-i
&.50/M Gal
LA Process Wt.
Small
13,035
13,055
285,500
285,500
57,150
r 449,090
445,000
894,090
1,249,775
571,500
1,821,275
Large
13,035
i ^rn1;
367,100
367,100
73,810
880,000
809,000
1,689,000
2,142,945
738,100
2,881,045
High Efficiency
Small
13,035
i i 035
286,500
286,500
57,300
686,000
445,000
1,131,000
1,487,835
573,000
2,060,835
Large
13,035
13~035
367,800
367,800
73,970
1,102,000
809,000
1,911,000
2,365,805
739,700
3,105,505
(1) Based oh 5% of system cost.
(2) Based on It of system cost.
(3) Closed cooling systems are used,
Pump HP is in power cost,
-------
FIGURE 131
ANNUAL COSTS FOR WET SCRUBBER
SYSTEMS FOR BOF STEELMAKING
(OPEN HOOD-HIGH EFFICIENCY)
(Low Unit Cost)
3000
2000
V)
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
Q
<
V)
O
X
fe
O
O
1000
800
600
400
100
200
300
500
PLANT CAPACITY
TONS
505
-------
FIGURE 132
ANNUAL COSTS FOR WET SCRUBBER
SYSTEMS FOR BOF STEELMAKING
(OPEN HOOD-HIGH EFFICIENCY)
(High Unit Cost)
3000
2000
o
Q
O
z
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
400
100
200
300
500
PLANT CAPACtTY
TONS
506
-------
TABLE 227
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBER SYSTEMS FOR BOF STEELMAKING
(CLOSED HOOD)
•« Note (1) • *• •«-
Low Unit Cost
•Note (2)
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance (3)
Labor
Materials
Total Maintenance
Replacement Parts ( 4 )
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
(nitrogen)
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7,850
$4/hr
$6/hr
$4/hr
$.005/kw-l
$.50 /MM Bl
$.10/M ga
$2.00/ton
LA Process Wt.
Small
5,793
5,793
162,900
162,900
32,500
32,500
r 23,000
U
18,880
17,500
59,380
260,573
571,500
832,073
Large
5,793
5,793
196,300
196,300
39,300
39,300
42,500
35,400
17,500
95,400
336,793
738,100
1,074,893
High Efficiency
Small
5,793
5,793
338,100
338,100
67,600
67,600
197,727
159,375
18,880
17,500
393,482
804,975
573,000
1,377,975
Large
5,793
5,793
420,400
420.400
84,100
84,100
300,000
159,375
35,400
17,500
512,275
1,022,568
739,700
1,762,268
01
o
(1) Closed hood systems are not ordinarily quoted at this low
(2) O.G. system quoted without cooling tower, but with auxil
for tilted furnace
(3) Based on 51 of system cost
(4) Based on 1| of system cost
efficiency level.
iary cleaning system
-------
TABLE 228
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBER SYSTEMS FOR BOF STEEL MAKING
(CLOSED HOOD)
^ Note (1) 9-
High Unit Cost
Note (2)
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance (3)
Labor
Materials
Total Maintenance
Replacement Parts (43
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
7,850
$9/hr
$12/hr
$S/hr
H.020/kw-fi
1.2 5 /MM !
.5Q/M gal
2.QO:/ton
LA Process Wt.
Small
13,035
13,035
162,900
162.900
32,500
32,500
r 92,000
ru
94,400
17,500
203,900
412,335
571,500
983,835
Large
13,035
1 ^ fl^c;
196,300
196.300
39,300
39,300
170,000
177,000
17,500"
364,500
613,135
738,100
1,351,235
High Efficiency
Small
13,035
13.035
338,100
338,100
67,600
67,600
790,909
398,437
94,400
17,500
1,301,246
1,719,981
573,000
2,292,981
Large
13,035
13.035
420,400
420, 40n
84,100
84,100
1,200,000
398,437
177,000
17,500
1,792,937
2,310,472
739,700
3,050,172
Closed hood systems are not ordinarily quoted
O.G. system quoted without cooling tower, But
for tilted furnace.
at this low efficiency level.
with auxiliary cleaning system
(3) Based on 5% of system cost.
(43 Based on I? of system cost.
-------
FIGURE 133
ANNUAL COSTS FOR WET SCRUBBER
SYSTEMS FOR BOF STEELMAKING
(CLOSED HOOD-HIGH EFFICIENCY)
(Low Unit Cost)
3000
2000
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
CO
Q
I
O
I
1000
800
600
400
OPERATING COST
100 200
PLANT CAPACITY
TONS
500
509
-------
FIGURE 134
ANNUAL COSTS FOR WET SCRUBBER
SYSTEMS FOR BOF STEELMAKING
(CLOSED HOOD-HIGH EFFICIENCY)
(High Unit Cost)
3000
2000
V)
tc.
o
Q
u.
O
O
X
k
o
u
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
1000
800
600
400
OPERATING COST
100
200
500
PLANT CAPACITY
TONS
510
-------
TABLE 229
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR COAL CLEANING PLANTS
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
2^500
$4/hr
$6/hr
$.005/kw-:
50.10/M ga
LA Process Wt.
Small
500
soo
1,426
832
r 20,048
L 1,698
21,746
24,504
38,994
63,498
Large
500
500
3,604
2,870
69,393
5,092
74,485
81,459
106,826
188,285
High Efficiency
Small
500
500
1,437
794
19,123
1,698
20,821
23,552
38,120
61,672
Large
500
500
3.408
2,258
60,769
5,092
65,861
72,027
97,191
169,218
CJl
Data based on two bids.
-------
TABLE 230
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR COAL CLEANING PLANTS
01
NJ
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
2,500
$9/hr
$12/hr
1.020/kw-h
&0.50/M ga
LA Process Wt.
Small
1,125
1,125
1,426
832
• 80,196
L 8,488
88,684
92,067
38,994
131,061
Large
1,125
1,125
3,604
2,870
277,588
25,462
303,050
310,649
106,826
417,475
High Efficiency
Small
1,125
If125
1,437
794
76,497
8,488
84,985
88,341
38,120
126,461
Large
1,125
1,125
3,408
2,258
243,089
25,462
268,551
275,342
97,191
372,533
Data based on two bids.
-------
FIGURE 135
ANNUAL COSTS FOR WET SCRUBBERS
FOR COAL CLEANING PLANTS
(LA-PROCESS WEIGHT)
(Low Unit Cost)
200
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
o
8
I
o
X
8
o
100
80
60
50
40
30
20
V
Z
7
OPERATING COST
600 800 1000 2000
PLANT CAPACITY, TON/HR
3000
513
-------
FIGURE 136
500
400
300
V)
tr
o
Q
LL
O
O
X
00
O
(J
200
100
80
60
40
ANNUAL COSTS FOR WET SCRUBBERS
FOR COAL CLEANING PLANTS
(LA-PROCESS WEIGHT)
(High Unit Cost)
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES.)
1
OPERATING COST
400 600 800 1000
PLANT CAPACITY, TON/HR
2000
3000
514
-------
FIGURE 137
ANNUAL COSTS FOR WET SCRUBBERS
FOR COAL CLEANING PLANTS
(HIGH EFFICIENCY)
(Low Unit Cost)
20Q
100
w
cc.
o
Q
u.
O
CO
o
<
tn
O
X
§
o
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
600 800 1000 2000
PLANT CAPACITY, TON/HR
3000
515
-------
FIGURE 138
ANNUAL COSTS FOR WET SCRUBBERS
FOR COAL CLEANING PLANTS
(HIGH EFFICIENCY)
(High Unit Cost)
500
400
300
t/5
cc
O
i
I
O
I
§
200
100
80
60
50
40
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
400 600 800 1000
PLANT CAPACITY, TON/HR
2000
3000
516
-------
TABLE 231
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR BRICK AND TILE KILNS
Low Unit Cost
Operating Cost Item
Operating Factor, Mr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$4/hr
$6/hr
$.005/kw-
$0.10/M g
LA Process Wt.
Small
ir
1.
Large
High Efficiency
Small
400
4 00
2,520
1,007
1,770
289
2,059
5,986
8,831
14,817
Large
400
400
2,659
2,216
4,290
660
4,950
10,225
11,571
21,796
en
-------
Ol
00
TABLE 232
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR BRICK AND TILE KILNS
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
$9/hr
$12/hr
0.20/kw-h
$0.50/M g
LA Process Wt.
Small
.1
Large
High Efficiency
Small
900
900
2,520
1,007
7,080
1,444
8,524
12,951
8,831
21,782
Large
900
900
2,659
2,216
17,160
3,302
20,462
26,237
11,571
37,808
-------
FIGURE 139
ANNUAL COSTS FOR WET SCRUBBERS
FOR BRICK AND TILE KILNS
(Low Unit Cost)
40
30
V)
DC
o
Q
LL
O
I
I
O
I
I-
£
o
o
20
10
5
4
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
80 100 200 300 400
PLANT CAPACITY, TON/DAY
519
-------
FIGURE 140
ANNUAL COSTS FOR WET SCRUBBERS
FOR BRICK AND TILE KILNS
(High Unit Cost)
40
30
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
CO
DC
O
Q
u.
O
O
I
w
O
U
20
10
8
6
5
OPERATING COST
80 100 200 300
PLANT CAPACITY, TON/DAY
400
520
-------
TABLE 233
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR THERMAL INCINERATORS FOR BRICK AND TILE KILNS
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$4/hr
$6/hr
$4/hr
$0.50/MM
LA Process Wt.
Small
ITU
Large
High Efficiency
Small
1,000
1,000
640
40
~6TO~
300
27,950
27,950
29,930
16,700
46,630
Large
1,000
1.000
640
40
~6TO~
300
64,500
64,500
66,480
27,003
93,483
01
NJ
-------
TABLE 234
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR THERMAL INCINERATORS FOR BRICK AND TILE KILNS
01
to
NJ
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$9/hr
$12/hr
$9/hr
U.25/MM I
LA Process Wt.
Small
ru
Large
High Efficiency
Small
2,250
2,250
1,440
40
1,480
300
69,875
69,875
73,905
16,700
90,605
Large
2,250
2,250
1,440
40
1,480
300
161,250
161,250
165,280
27,003
192,283
-------
FIGURE 141
ANNUAL COSTS FOR THERMAL INCINERATORS
FOR BRICK AND TILE KILNS
(Low Unit Cost)
200
CO
cc
8
u.
O
O
I
I-
to*
O
u
100
80
30
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
J2L
60 80 100 200
PLANT CAPACITY, TON/DAY
300
400
523
-------
FIGURE 142
ANNUAL COSTS FOR THERMAL INCINERATORS
FOR BRICK AND TILE KILNS
(High Unit Cost)
200
&o
cc
8
u.
O
CO
Q
I
O
X
O
O
100
80.
60.
50
40-
30.
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
60 80 100 200
PLANT CAPACITY, TON/DAY
300
400
524
-------
TABLE 235
ANNUAL OPERATING COST DATA
(COST IN $/YEAR)
FOR COMBINED GAS CLEANING SYSTEMS FOR COPPER ROASTING FURNACES
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$4/hr
$6/hr
$4/hr
;.005/kw-h
10.10/M ga
LA Process Wt.
Small
L-
Large
High Efficiency
Small
-
780
780
1,750
4,862
1,752
6,614
9,144
32,966
42,110
Large
-
780
780
2,450
10,224
4,438
14,662
17,892
65,830
83,722
CJI
M
Ol
-------
01
TABLE 236
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR COMBINED GAS CLEANING SYSTEMS FOR COPPER ROASTING FURNACES
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$9/hr
$12/hr
$9/hr
$.020/kw-
$0.50/M g
LA Process Wt.
Small
.r
1
Large
High Efficiency
Small
-
780
780
1,750
19,449
8,758
28,207
30,737
32,966
63,703
Large
-
780
780
2,450
40,896
22,182
63,078
66,308
65,830
132,138
-------
FIGURE 143
ANNUAL COSTS FOR COMBINED GAS CLEANING SYSTEMS
FOR COPPER ROASTING FURNACES
(Low Unit Cost)
O
Q
O
I
v>
O
O
80
60
50
40
30
20
10
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
200
300
400 500 600
800 1000
PLANT CAPACITY, TON/DAY
527
-------
FIGURE 144
ANNUAL COSTS FOR COMBINED GAS CLEANING SYSTEMS
FOR COPPER ROASTING FURNACES
(High Unit Cost)
200
o
Q
1
I
o
oo
8
100
80
60
50
40
30
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
a
OPERATING COST
200 300 400 500 600 800 1000
PLANT CAPACITY, TON/DAY
528
-------
TABLE 237
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS FOR COPPER REVERBERATORY FURNACES
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$4/hr
$6/hr
$4/hr
$.005/kw-
LA Process Wt.
Small
700
70
TTU
383
500
8T3"
4,250
ir 1,565
1,565
7,468
43,487
50,955
Large
700
70
77U
383
500
8TT
7,500
3,105
3,105
12,258
87,281
99,539
High Efficiency
Small
700
70
TTTj
383
500
8~8~3
5,250
1,565
1,565
8,468
54,659
63,127
Large
700
70
TTU
383
500
WSJ
7,500
3,105
3,105
12,258
90,461
102,719
Ul
-------
TABLE 238
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS FOR COPPER REVERBERATORY FURNACES
ui
CO
o
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$9/hr
$12/hr
$9/hr
.020/kw-h
LA Process Wt.
Small
1,575
157
1,732
863
500
1,363
4,250
6,260
-
6,260
13,605
43,487
57,092
Large
1,575
157
1,732
863
500
1,363
7,500
12,420
-
12,420
23,015
87,281
110,296
High Efficiency
Small
1,575
157
863
500
1,363
5,250
6,260
-
6,260
14,605
54,659
69,264
Large
1,575
157
1,732
863
500
1,363
7,500
12,420
-
12,420
23,015
90,461
113,476
-------
FIGURE 145
ANNUAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR COPPER REVERBERATORY FURNACES
(HIGH EFFICIENCY)
(Low Unit Cost)
c/j
tc
u.
O
O
O
100
80
60
40
30
20
10
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
600 800 1000
PLANT CAPACITY, TON/DAY
2000
531
-------
FIGURE 146
ANNUAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR COPPER REVERBERATORY FURNACES
(HIGH EFFICIENCY)
(High Unit Cost)
100
80
60
cc
<
8
LL
O
O
X
50
40
20.
10
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
400 600 800 1000
PLANT CAPACITY, TON/DAY
2000
532
-------
TABLE 239
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR COPPER REVERBERATORY FURNACES
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$.005 kw-
$0.50/MM I
LA Process Wt.
Small
.r 27,000
ru 25,250
52,250
52,250
20,615
72,865
Large
40,500
62,000
102,500
102,500
44,250
146,750
High Efficiency
Small
90,000
25,250
115,250
115,250
20,015
135,265
Large
110,000
62,000
172,000
172,000
51,150
223,150
s
CO
-------
TABLE 240
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR COPPER REVERBERATORY FURNACES
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor ( if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$.020/kw-
$1.25/MMB
LA Process Wt.
Small
r 108,000
'U 63,125
171,125
171,125
20,615
191,740
Large
162,000
155,000
317,000
317,000
44,250
361,250
High Efficiency
Small
360,000
63,125
423,125
423,125
24,015
447,140
Large
440,000
155,000
595,000
595,000
51,150
646,150
-------
CO
tr
8
u.
O
CO
Q
I
O
X
O
u
500
FIGURE 147
ANNUAL COSTS FOR WET SCRUBBERS
FOR COPPER REVERBERATORY FURNACES
(HIGH EFFICIENCY)
(Low Unit Cost)
300
200
100
80
60
40
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)*
OPERATING COST*
400 600 800 1000 2000
PLANT CAPACITY, TON/DAY
*This does not include operating labor, maintenance labor, or repair parts costs.
535
-------
FIGURE 148
ANNUAL COSTS FOR WET SCRUBBERS
FOR COPPER REVERBERATORY FURNACES
(HIGH EFFICIENCY)
(High Unit Cost)
4000
to
tc
o
o
LL
O
V)
Q
O
I
I-
te
o
o
2000
1000
800
600
500
400
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)*
400
2000
600 800 1000
PLANT CAPACITY, TON/DAY
*This does not include operating labor, maintenance labor, or repair parts costs.
536
-------
TABLE 241
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS FOR BARK BOILERS
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$.005/kw-l
LA Process Wt.
Small
r
Large
High Efficiency
Small
480
500
1,195
1,195
2,175
29,043
31,218
Large
480
1,000
3,268
3,268
4,748
59,907
64,655
s
-------
Ol
CO
00
TABLE 242
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS FOR BARK BOILERS
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
An Dualized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$.020/kw-
LA Process Wt.
Small
T
Large
High Efficiency
Small
480
500
4,780
4,780
5,760
29,043
34,803
Large
480
1,000
13,073
13,073
14,553
59,907
74,460
-------
FIGURE 149
ANNUAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR KRAFT MILL BARK BOILERS
OC
<
O
Q
LL
O
O
I
O
O
0
8
6
5
4
3
2
4
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
S
S
/f-
/—/
/ ^°
S
/
^
PERATING C
S
^
*
OST
100
80
60
50
40
30
20
60 80 100 200
PLANT CAPACITY, M LB STEAM/HR
300
400
539
-------
FIGURE 150
CO
cc
8
LL
O
8
I
O
I
CO
O
U
ANNUAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR KRAFT MILL BARK BOILERS
(High Unit Cost)
20
10
6
5
4
200
TOTAL COST
(OPERATING COST P.LUS
CAPITAL CHARGES)
100
80
60
50
40
30
60 80 100 200
PLANT CAPACITY, M LB STEAM/HR
300
400
540
-------
TABLE 243
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR BARK BOILERS
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor ( if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$4/hr
$.005/kw-:
$0.10/M g;
LA Process Wt.
Small
r
1
Large
High Efficiency
Small
800
800
5.200
6,200
11,085
2,180
13,265
25.465
18,499
43,964
Large
800
800
12.483
13,843
38,440
5,970
44,410
71,536
45,453
116,989
(71
-------
TABLE 244
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR BARK BOILERS
Ul
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
8,600
$9/hr
f.020/kw-J
&0.50/M ga
LA Process Wt.
Small
r
L
Large
High Efficiency
Small
1,800
1.800
5,200
6,200
44,340
10,900
55,240
68,440
18,499
86,939
Large
1,800
1.800
12,483
13,843
153,760
29,850
183,610
211,736
45,453
257,189
-------
FIGURE 151
ANNUAL COSTS FOR WET SCRUBBERS
FOR BARK BOILERS
(Low Unit Cost)
200
(A
DC
o
Q
U.
O
I
I
O
T.
100
80
60
50
40
30
20
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
60 80 100 200
PLANT CAPACITY, M LB STEAM/HR
300
543
-------
400
300
CO
tr
200-
100
FIGURE 152
ANNUAL COSTS FOR WET SCRUBBERS
FOR BARK BOILERS
(High Unit Cost)
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
100 200 300 400 500
PLANT CAPACITY, M LB STEAM/HR
544
-------
TABLE 245
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR FABRIC FILTERS FOR FERROSILICON FURNACES
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7,700
$4/hr
$6/hr
;.005/kw-h
LA Process Wt.
Small
Large
High Efficiency
Small
12,000
800
12,800
4,560
7,500
8,059
8,059
32,919
47,300
80,219
Large
12,000
800
12,800
11,800
31,640
28,318
28,318
84,558
147,100
231,658
en
-------
TABLE 246
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR FABRIC FILTERS FOR FERROSILICON FURNACES
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power '
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7,700
$9/hr
$12/hr
0.020/kw-
LA Process Wt.
Small
r
Large
High Efficiency
Small
27,000
1,800
28.800
4,560
7,500
32,236
32,236
73,096
47,300
120,396
Large
27 ,000
1,800
28.800
11,800
31,640
113,273
113,273
185,513
147,100
332,613
-------
FIGURE 153
ANNUAL COSTS FOR FABRIC FILTERS
FOR FERROSILICON FURNACES
(Low Unit Cost)
CO
cc
8
u.
O
CO
Q
<
CO
O
i
O
400
300
200
100
80
60
50
40
30
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
10 20
FURNACE SIZE, MW
30
40 50
547
-------
FIGURE 154
ANNUAL COSTS FOR FABRIC FILTERS
FOR FERROSILICOIM FURNACES
(High Unit Cost)
400
300
t/5
CC
o
Q
Q
\
O
to
O
O
200
100
80
60
50
40
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
10 20
FURNACE SIZE, MW
30
40 50
548
-------
TABLE 247
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR>
FOR FABRIC FILTERS FOR FERROCHROME FURNACES
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
7^700
$4/hr
$6/hr
f.005/kw-h
LA Process Wt.
Small
c
Large
High Efficiency
Small
12,000
800
12,800"
4,400
6,540
4,818
4,818
28,558
39,700
68,258
Large
12,000
800
12,800
6,600
17,840
14,636
14,636
51,876
82,300
134,176
CJ1
-u
CO
-------
TABLE 248
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR FABRIC FILTERS FOR FERROCHROME FURNACES
8
o
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power '
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7,700
$9/hr
$12/hr
0.020 kw-:
LA Process Wt.
Small
r
Large
High Efficiency
Small
27,000
1,800
28,800
4,400
6,540
19,273
-
-
19,273
59,013
39,700
98,713
Large
27,000
1,800
28,800
6,600
17,840
58,545
-
-
58,545
111,785
82,300
194,085
-------
FIGURE 155
ANNUAL COSTS FOR FABRIC FILTERS
FOR FERROCHROME FURNACES
(Low Unit Cost)
200
V)
oc
_
8
LL
O
V)
Q
<
C/5
O
I
I-
o
O
100
80
60
50
40
30
20
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
8 10
FURNACE SIZE, MW
20
30
40
551
-------
FIGURE 156
ANNUAL COSTS FOR FABRIC FILTERS
FOR FERROCHROME FURNACES
(High Unit Cost)
400
300
V)
tc
o
Q
u.
O
O
X
200
100
80
60
50
40
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
10 20
FURNACE SIZE, MW
30
40
50
552
-------
TABLE 249
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR FERROSILICON FURNACES
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
7,700
$4/hr
.005/kw-h
$0.02/M g£
LA Process Wt.
Small
2,400
38,000
23,000
14,227
1 6,920
21,147
84,547
104,400
188,947
Large
2,400
65,500
39,000
33,773
2 5, "080
58,853
165,753
218,500
384,253
High Efficiency
Small
2,400
42,000
25,000
28,955
8,000
36,955
106,355
115,100
221,455
Large
2,400
74,000
44,500
80,091
29,"100
109,191
230,091
241,300
471,391
CJl
01
w
-------
Ol
Ol
TABLE 250
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR FERROSILICON FURNACES
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7,700
$9/hr
$.020/kw-l
$0.09/M g£
LA Process Wt.
Small
5,400
38,000
23,000
r 56,909
L 31,140
88,049
154,449
104,400
258,849
Large
5,400
65,500
39,000
135,091
112,860
247,951
357,851
218,500
576,351
High Efficiency
Small
5.400
42,000
25,000
115,818
36,000
151,818
224,218
115,100
339,318
Large
5.400
74,000
44,500
320,364
130,950
451,314
575,214
241,300
816,514
-------
FIGURE 157
ANNUAL COSTS FOR WET SCRUBBERS
FOR FERROSILICON FURNACES
(HIGH EFFICIENCY)
(Low Unit Cost)
500
400
300
CO
cc
o
Q
u.
o
I
I
O
I
O
u
200
100
80
60
40
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
10 20
FURNACE SIZE, MW
30
40
50
555
-------
FIGURE 158
ANNUAL COSTS FOR WET SCRUBBERS
FOR FERROSILICON FURNACES
(HIGH EFFICIENCY)
(High Unit Cost)
V)
cc.
_
8
LL
O
O
I
V)
O
O
1000
800
600
500
400
300
200
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGE)
OPERATING COST
8 10
FURNACE SIZE, MW
20
30
40
556
-------
TABLE 251
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR FERROCHROME FURNACES
Low Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process) \
Water (Cooling) J
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
7,700
$4/hr
£.005 /kw-:
S0.02/M ga
LA Process Wt.
Small
9,934
27,700
11,700
r 12,273
L 5,160
17,433
66,767
55,300
122,067
Large
9,934
50,800
20,500
43,409
18,960
62,369
143,603
101,500
245,103
High Efficiency
Small
9.934
42,000
25,000
28,955
8,000
36,955
113,889
83,300
197,189
Large
9.934
74,000
44,500
80,091
29,100
109,191
237,625
148,300
385,925
CJl
Ul
•vl
-------
O1
Ol
00
TABLE 252
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR FERROCHROME FURNACES
High Unit Cost
Operating Cost Item
Operating Factor, Hr/Year
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials
Total Maintenance
Replacement Parts
Total Replacement Parts
Utilities
Electric Power
Fuel
Water (Process) "1
Water (Cooling) /
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
7,700
$9/hr
$.020/kw-
;0.09/M ga
LA Process Wt.
Small
22,350
27,700
11,700
T 49,091
. 23,220
72,311
134,061
55,300
189,361
Large
22,350
50,800
20,500
173,636
85,320
258,956
352,606
101,500
454,106
High Efficiency
Small
22.350
42,000
25,000
115,818
36,000
151,818
241,168
83,300
324,468
Large
22.350
74,000
44,500
320,364
130,950
451,314
592,164
148,300
740,464
-------
FIGURE 159
ANNUAL COSTS FOR WET SCRUBBERS
FOR FERROCHROME FURNACES
(HIGH EFFICIENCY)
(Low Unit Cost)
oo
cc
O
a
LL
O
8
1
CO
O
I
I-
co
O
U
1000
800
600
500
400
300
200
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
8 10
FURNACE SIZE, MW
20
30
40
559
-------
FIGURE 160
ANNUAL COSTS FOR WET SCRUBBERS
FOR FERROCHROME FURNACES
(HIGH EFFICIENCY)
(High Unit Cost)
CO
cc
o
CO
O
I
CO
O
o
1000
800
600
500
400
300
200
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
8 10 20
FURNACE SIZE, MW
30
40
560
-------
4. GENERALIZED COST DATA
A series of correlations were made relating the cost of equipment to the
gas flow rate. Here, as in the rest of this report, costs are reported in 1971
dollars.
SCRUBBERS
Correlations for scrubbers were made both for the scrubber cost and for
the total installed cost of the scrubber system. Figure 161 shows the cost of the
scrubber alone. Although there is a little scatter in the data, the results can be
well represented by one curve. Scrubbers for all applications studied appear to
have the same cost basis. This is not true for the installed scrubber system costs
as shown on Figure 162. Here the data fall into three groups. These groups are
not differentiated by operating efficiency. Instead, they group by the
complexity of the system involved. Scurbbers for steelmaking and ferroalloys
fall on the upper curves. These are complex systems for which the total system
cost is quite large relative to the scrubber cost.
Scrubbing systems for rendering and asphalt batching fall on the lower
line. These systems have very little extra equipment and are simple in scope.
The remaining four applications fall on the center line.
An attempt was made to correlate direct operating costs in a similar way.
Although a positive relationship was shown to exist, the data was widely
scattered. This occurred because of wide variations in the amount of
maintenance and operating labor required from system to system. The principle
operating cost common to all scrubbing systems is power cost which is directly.
related to the system pressure drop. Power cost correlates well with gas rate
using parameters of system pressure drop. Maintenance and operating labor
requirements have very little to do with gas throughput, however, and this fact
prevents adequate correlation.
PRECIPITATORS
Similar correlations were made for electrostatic precipitators. Figure 163
shows the cost of the precipitator alone. As opposed to the scrubber
correlation, the equipment costs fall into three groups. The groups are
characterized by the required level of performance. Costs for total installed
cost, shown on Figure 164, do not relate to the required efficiency. Instead,
like scrubbers, they relate to the complexity of the system. Systems operating
on BOF steelmaking furnaces are expensive relative to others.
561
-------
FIGURE 161
CAPITAL COST OF WET SCRUBBERS
Rendering
Asphalt Batching
BOF - Open Hood
BOF - Closed Hood
Coal Cleaning
Brick and Tile
Copper Rev. Furnaces
Bark Boilers
Ferroalloys
103
INLET GAS RATE, ACFM
-------
§
Rendering
Asphalt Batching
A BOF - Open Hood
Coal Cleaning
Bark Boilers
<] Brick and Tile
Ferroalloys
BOF Closed Hood
Copper Rev. Furnaces
TOTAL INSTALLED COST OF WET SCRUBBER SYSTEMS
(PARAMETERS INDICATE THE LEVEL OF SYSTEM COMPLEXITY) 1_M
10
INLET GAS FLOW RATE, ACFM
10C
10'
-------
V)
cc
o
Q
O
o
O FCC
A BOF
Copper Rev. Furnace
Bark Boilers
95-97% EFF.
70-86% EFF.
FIGURE 163
CAPITAL COST OF ELECTROSTATIC PRECIPITATORS
INLET GAS RATE, ACFM
-------
HIGH
COMPLEXITY
BOF
Copper Rev. Furnace
Bark Boilers
LOW
COMPLEXITY
FIGURE 164
INSTALLED COST OF PRECIPITATORS
10
INLET GAS RATE, ACFM
-------
An attempt was made to show a similar correlation for operating costs.
The result is presented in Figure 165. Correlation exists only for equipment
grouped by process application. No general relationship appears to exist.
INCINERATORS
Data were collected for only two incinerator systems. One of these,
rendering, had no heat exchange. The other, brick and tile kilns, had 65% heat
recovery. The cost relationship between these two kinds of systems is clearly
shown in Figures 166 - 168. Figure 166 shows the purchase cost of the
incinerators. Incinerators with heat recovery are more expensive, by a factor of
three, on the range shown on the plot. Cost of the total system is shown on
Figure 167. Again, systems with 65% heat recovery cost about four times those
without heat recovery. Direct hourly operating costs are presented in Figure
168. The major component of operating cost for these systems is fuel cost.
Operating cost is therefore nearly inversely proportional to heat recovery. This
relationship is apparent in Figure 168.
FABRIC FILTERS
Only two fabric filter applications were included in the nine process areas
studied; asphalt batching and ferroalloys. The purchased cost of the fabric
filters is shown on Figure 169. Installed costs for those two types of systems
are shown correlated with size on Figure 170. Costs for the two applications
are quite different. Although the performance of the systems are comparable,
the difficulty of accomplishing that performance differs widely. Requirements
for particle size, temperature, and air to cloth ratio all cause ferroalloy systems
to cost most. The relationship of operating cost to size shown on Figure 171 is
similar. For asphalt batching, roughly two-thirds of the operating cost goes for
bag replacement. While ferroalloys have high bag replacement costs, they also
have significant labor costs which total to much greater operating cost per
cubic foot of flow.
566
-------
O FCC
A BOF
D Copper Rev. Furnace
Bark Boilers
FIGURE 165
ANNUAL DIRECT OPERATING COST
OF ELECTROSTATIC PRECIPITATORS
(Basis: Round the clock operation 7700-8600 hr/hr)
1! 11 fjj; TittM
10'
INLET GAS RATE, ACFM
10'
-------
CO
DC
§ 10*
CO
O
o
::: ::!V
65% HEAT RECOVERY
NO HEAT RECOVERY
FIGURE 166
CAPITAL COST .OF INCINERATORS
INLET GAS RATE, ACFM
568
-------
106
9
8
7
6
M
EE
S 106-
7
6
INSTALLED COST OF INCINERATORS
10*
65% HEAT RECOVERY
NO HEAT RECOVERY
103
104
INLET GAS RATE, ACFM
105
569
-------
100
oc
X
e/5
cc
O
D
O
O
FIGURE 168
DIRECT HOURLY OPERATING COST
FOR INCINERATORS
NO HEAT RECOVERY
65% HEAT RECOVERY
INLET GAS RATE, ACFM
570
-------
CAPITAL COST OF
FABRIC FILTERS
ASPHALT BATCH ING
INLET GAS RATE, ACFM
571
-------
INSTALLED COST OF
FABRIC FILTERS
ASPHALT BATCHING
106
INLET GAS RATE, ACFM
-------
CO
oc
o
Q
8
o
z
z
<
FIGURE 171
FERROALLOY
(Basis: 7700 hr/yr)
ANNUAL DIRECT OPERATING COST
FOR FABRIC FILTERS
ASPHALT BATCHING
(Basis: 960 hr/yr)
106
INLET GAS RATE, ACFM
01
^i
CO
-------
III. CONCLUSIONS AND RECOMMENDATIONS
The data collected during the course of this program substantiate several
major conclusions with regard to the application areas covered:
A. Rendering odors can be controlled by thermal incineration at
reasonable cost if the gas flow from odor-containing sources is limited severely
by proper use of condensers, enclosures around equipment, etc. The cost is
nearly proportional to the air flow rate treated. Scrubbing with permanganate
or other oxidizing chemicals costs a great deal to operate, if all of the organics
are reacted out of the gas stream by the oxidation chemicals.
B. Fluidized Bed Catalytic Cracking units in petroleum refineries may
be equipped with electrostatic precipitators which are adequate for control of
paniculate emissions in all of the cases considered. For small units or those
with relatively low catalyst losses, the addition of an external cyclone may be
sufficient for good particulate control. On units with very low rates of attrition
of catalyst, it may be possible to meet existing regulations without external
particulate control devices.
C. Asphalt Batch Plants are adequately treated by both wet scrubbers
and fabric collectors, with economic factors likely to influence the installation
of one system over the other. Electrostatic precipita'tors have also been applied
with some degree of success in the past.
D. Basic Oxygen Furnace steel making processes have been treated by
both scrubbers and precipitators. The scrubbing systems can be designed in
such a way as to minimize or eliminate infiltration of ambient air (closed hood
system) and thereby minimize the system size. However, the complexity of this
approach tends to increase the system cost in comparison with the larger open
hood systems with either scrubbers or precipitators as the primary abatement
device. Precipitator systems have no upper limit on efficiency during most of
the cycle, but have potential resistivity problems at the beginning and end of
the blow. The open hood scrubbers require high head fans (two fans in series,
or positive displacement blowers) to hold particulate losses as low as those for
the closed hood system.
E. Coal Cleaning Processes are treated exclusively by scrubbers, which
have no unusual problems or performance limitations.
574
-------
F. Brick and Tile Kilns normally produce no significant emissions. However,
hydrocarbons, fluorine and/or sulfur oxides may be emitted if precursor impurities are
present in the raw material or fuel. The hydrocarbon emissions may require incineration
to eliminate visible smoke, and fluorine or sulfur oxides may require treatment by wet
scrubbers.
G. Copper Smelting by roasting and reverberatory furnaces of conventional design
were covered in this study. Smelting technology is changing rapidly in this area and may
eliminate these processes as separate steps. However, the two types of gas cleaning
processes covered should be appropriate to combined smelting processes as they emerge.
One process deals with the cleaning of a gas stream used as feed to a sulfuric acid plant.
This involves cooling, acid mist precipitation and paniculate scrubbing. The other
approach deals with wet scrubbing of gases vented to the atmosphere with a significant
concentration of SC^, or use of electrostatic precipitators on this gas stream.
H. Bark Boilers produce a carbonaceous ash which is easily removed from the flue
gas by mechanical collectors, and a fine flyash which requires precipitation or scrubbing.
Both methods are employed in plants where recycle of carbonaceous ash to the furnace is
practiced.
I. Ferrochrome and Ferrosilicon Furnaces present difficult paniculate control
problems which have been handled adequately only by fabric collectors. Wet scrubbers of
very high pressure drop are capable of satisfactory operation, but are unlikely to be
competitive, whereas precipitators have not functioned satisfactorily because of resistivity
problems.
Several additional conclusions can be drawn relative to the equipment types covered
by generalizing data from all of the areas:
A. Thermal incinerators were quoted for two applications. Data relating cost to
size is relatively consistent between the two if the presence or absence of heat exchange is
taken into account. The main variable in both capital and operating cost is gas flow, not
process unit capacity.
B. Electrostatic precipitator costs can be generalized well using gas flow as a
primary variable and system complexity as a coarse parameter. Efficiency level was not as
critical in installed cost as was the nature and complexity of the overall system in which
the precipitator was used. This study covered a wide range of complexity.
575
-------
C. Scrubber costs varied largely with gas flow and only slightly with efficiency.
However, the fan cost increased sharply as particulate collection efficiency or complexity
of the system increased.
D. Fabric collector costs varied nearly linearly with gas flow, as expected, and did
not include efficiency as a parameter. However, the cost of the system was influenced
sharply by temperature and the necessity for protecting the fabric. Here again,
"difficulty" of the service is the best coarse correlation parameter.
576
-------
m
z
o
-------
APPENDIX I
Rule 54 of the Air Pollution Control
District of Los Angeles County
-------
Rule 54. Dust and Fumes
A person shall not discharge in any one hour from any source
whatsoever dust or fumes in total quantities in excess of the
amount shown in the following table: (see next page)
To use the following table, take the process weight per hour
as such is defined in Rule 2(j).* Then find this figure on the
table, opposite which is the maximum number of pounds of contam-
inants which may be discharged into the atmosphere in any one hour.
As an example, if A has a process which emits contaminants into
the atmosphere and which process takes 3 hours to complete, he will
divide the weight of all materials in the specific process, in this
example, 1,500 Ibs. by 3 giving a process weight per hour of 500
Ibs. The table shows that A may not discharge more than 1.77 Ibs.
in any one hour during the process. Where the process weight per
hour falls between figures in the left hand column, the exact
weight of permitted discharge may be interpolated.
* Rule 2 (j). Process Weight Per Hour. "Process Weight" is the
total weight of all materials introduced into any
specific process which process may cause any discharge
into the atmosphere. Solid fuels charged will be
considered as part of the process weight, but liquid
and gaseous fuels and combustion air will not. "The
Process Weight Per Hour" will be derived by dividing
the total process weight by the number of hours in
one complete operation from the beginning of any
given process to the completion thereof, excluding
any time during which the equipment is idle.
i
(k). Dusts. "Dusts" are minute solid particles released
into the air by natural forces or by mechanical
processes such as crushing, grinding, milling, drilling,
demolishing, shoveling, conveying, covering, bagging,
sweeping, etc.
(1). Condensed Fumes. "Condensed Fumes" are minute solid
particles generated by the condensation of vapors
from solid matter after volatilization from the molten
state, or may be generated by sublimation, distillation,
calcination, or chemical reaction, when these processes
create air-borne particles.
-------
TABLE
•Proceei
Wt.'hr(lbt)
50
100
150
200
250
300
350
400
450
500
550
600
650
700
750
800
850
900
950
1000
1100 '
1200
1300
1400
1500
1600
1700
1800
1900
2000
2100
2200
2300
2400
2500
2600
2700
2800
2900
3000
3100
3200
3300
•See Definition
Htllmum Weight
Dl»ch/hr(l b»)
.24
.46
.66
.85
..03
.20
.35
.50
.63
.77
.89
2.01
2.12
2.24
2.34
2.43
2.53
2.62
2.72
2.80
2.97
1.12
3.26
3.40
3.54
3.66
3.79
3.91
4.03
4.14
4.24
4.34
4.44
4.55
, 4.64
4.74
4.84
4.92
5.02
5.10
5.18
5.27
5.36
In Rule 2(j).
•• roceit
Wt/hr(lb«)
3400
3500
3600
3700
3800
3900
4000
4100
4200
4300
4400
4500
4600
4700
4800
4900
5000
5500
6000
6500
7000
7500
8000
8500
9000
9500
10000
11000
12000
13000
14000
15000
16000
17000
18000
19000
20000
30000
40000
50000
60000
or
more
Maximum Weight
Disch/hr(lbi)
5.44
5.52
. 5.61
5.69
5.77
5.85
5.93
6.01
6.08
6.15
6.22
6.30
6.37
6.45
6.52
6.60
6.67
7.03
7.37
7.71
8.05
8.39
8.71
9.03
9.36
9.67
10.0
10.63
11.28
11.89
12.50
13.13
13.74
14.36
14.97
15.58
16.19
22.22
28.3
34.3
40.0
-------
APPENDIX II
INSTRUCTIONS FOR SUBMITTING
COST DATA
Two forms (two copies each) are enclosed with each specification. These are
for submitting:
(A) Estimated Capital Cost Data
(B) Annual Operating Cost Data
These forms will also be used to exhibit averages of the three cost estimates for
each process and equipment type. Because your costs will be averaged with
those of other IGCI members, it is necessary to prepare them in accordance
with instructions given in the following paragraphs.
(A) Estimated Capital Cost Data
The upper part of this form should already be filled out for the particular
application when you receive it. This information on operating conditions
should be identical to that in the specification and is repeated here only for the
convenience of those reading the form.
You should fill in the dollar amounts estimated in the appropriate spaces on
the bottom half of the form. It should not be necessary to add any information
other than the dollar amounts. If you wish to provide a description of the
equipment proposed, please do so on one or more separate sheets of paper, and
attach it to the form. If any item is not involved in the equipment you are
proposing, please indicate this by writing "none" in the space rather than
leaving it blank or using a zero.
(1) The "gas cleaning device" cost should be reported just as you would
report a flange-to-flange equipment sale to the IGCI. That is, a complete device
including necessary auxiliaries such as power supplies, mist eliminators, etc. Do
NOT include such items as fans, solids handling equipment, etc., unless these
are an integral part of your gas cleaning device.
-------
(2) "Auxiliaries" are those items of equipment which are frequently
supplied with the gas cleaning device. There is a purely arbitrary definition of
those items included here and those included in the "Installation" Costs. Do
NOT include any of the cost of erecting or installing auxiliaries in this category.
(3) "Installation Cost" should include all of the material not in (1) or (2)
and the field labor required to complete a turnkey installation. In cases where
the equipment supplier ordinarily erects the equipment but does not supply
labor for foundations, etc., it is necessary to include an estimated cost for these
items.
The installation should be estimated for a new plant, or one in which there are
no limitations imposed by the arrangement of existing equipment. Installation
labor should be estimated on the basis that the erection will take place in an
area where labor rates are near the U.S. average, and the distance from your
plant is no more than 500 miles. Milwaukee, Wisconsin is an example of a city
with near-average labor rates.
(B) Annual Operating Cost Data
Some of the information will be supplied by Air Resources, such as unit costs
for labor and utilities, and annualized capital charges. You should fill in the
usage figures for the complete abatement system units indicated below:
Labor hrs/year
Maintenance Materials Dollars/year
Replacement Parts Dollars/year
Electric Power kw-hr/year
Fuel MMBTU/year
Water (Process) MM gal/year
Water (Cooling) MM gal/year
Chemicals Dollars/year
Air Resources will average the consumption figures reported, and convert them
to dollar values for inclusion in the final report.
-------
APPENDIX III
SPECIFICATIONS FOR ABATEMENT EQUIPMENT
7. SCOPE
A. This specification covers vendor requirements for air pollution control
equipment for the subject process. The intent of the specification is to describe the service as
thoroughly as possible so as to secure vendor's proposal for equipment which is suitable in
every respect for the service intended. Basic information is tabulated in sections 2 and 3. The
vendor should specify any of the performance characteristics which cannot be guaranteed
without samples of process effluent.
B. The vendor shall submit a bid showing three separate prices as described below.
1. All labor, materials, equipment, and services to furnish one pollution
abatement device together with the following:
a. All ladders, platforms and other accessways to provide convenient
access to all points requiring observation or maintenance.
b. Foundation bolts as required.
c. Six (6) sets of drawings, instructions, spare parts list, etc., pertinent
to the above.
2. Auxiliaries including
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning Equipment
(e) Dust Disposal Equipment
3. A turnkey installation of the entire system including the following
installation costs:
(a) Engineering
(b) Foundations & Support
(c) Ductwork
(d) Stack
(e) Electrical
(f) Piping
(g) Insulation
-------
(h) Painting
(i) Startup
(k) Performance Test
(I) Other
C. For the "pollution abatement device only" quotation, the vendor shall furnish
the equipment FOB point of manufacture, and shall furnish as a part of this project
competent supervision of the erection, which shall be by others.
D. Vendor shall furnish * the following drawings, etc., as a minimum:
1. With his proposal:
a. Plan and elevation showing general arrangement.
b. Typical details of collector internals proposed.
c. Data relating to projected performance with respect to pressure
drop, gas absorption efficiency and paniculate removal efficiency to
operating parameters such as gas flow.
2. Upon receip tof order:
a. Proposed schedule of design and delivery.
3. Within 60 days of order:
a. Complete drawings of equipment for approval by customer.
b. 30 days prior to shipment:
1) Certified drawings of equipment, six sets
2) Installation instructions, six sets
3) Starting and operating instructions, six sets
4) Maintenance instructions and recommended spare parts lists,
six sets
E. The design and construction of the collector and auxiliaries shall conform to the
general conditions given in Section 5, and to good engineering practice.
*This is a typical request. The member companies are NOT to furnish this material under the
present project.
-------
2. PROCESS DESCRIPTION
A single wet scrubber is to treat the effluent from a typical asphalt batching plant
operation. Ml of the air required to ventilate the following items of equipment must be
treated so as to conform to the specified paniculate emission limits.
1. Cold aggregate elevator
2. Rock dryer
3. Ho t aggregate elevator
4. Vibrating screens
5. Sorted hot aggregate storage bins
6. Weigh hopper
7. Mixer
The necessary enclosures to minimize escapement of dust from conveyors, elevators,
etc. will be provided by others. The vendor is to furnish all interconnecting ductwork,
primary collector, wet scrubber, fan, slurry pumps, settler and clarified water return pumps.
Dust from the primary cyclone is to be returned to the bottom of the hot elevator, whereas
dust collected in the scrubber is to be settled to approximately 60% solids content by weight
and removed by truck.
The plant is located outside, adjacent to a public highway, and with little likelihood of
interferences of roadways, buildings, etc. with the location of pollution control equipment.
The plant is considered temporary (2-4 years expected life in this location) and may be
moved. Ability of the pollution abatement equipment to be dismantled and reloacted is of
prime importance.
-------
3. OPERATING CONDITIONS
Two sizes of wet scrubbers are to be quoted for each of two efficiency levels. Vendors
quotation should consist of four separate and independent quotations.
Plant Capacity, ton/hr
Process Weight, Ib/hr
Gas to Primary Collector
Flow, ACFM
Temp., °F
% Moisture
Primary Collector Inlet
Loading, Ib/hr
Primary Collector Outlet
Loading, Ib/hr
Primary Collector Efficiency, %
Gas to Secondary Collector
(Scrubber)
Flow, ACFM
Temp., °F
% Moisture
Outlet from Secondary Collector
Flow, ACFM
Temp., °F
Moisture Content, Vol. %
Small
100
204,000
31,400
370
17
4,000
1,000
75
30,600
350
17
25,000
147
23
Large
200
408,000
44,000
370
21
8,000
2,000
75
42,900
350
21
35,200
152
26.2
Case 1 — Medium Efficiency
Outlet Loading, Ib/hr
Outlet Loading, gr/ACF
Efficiency, Wt. %
40
0.187
96
40
0.133
98
Outlet Loading, Ib/hr
Outlet Loading, gr/ACF
Efficiency
Case 2 - High Efficiency
6.43
0.03
99.68
9.06
0.03
99.77
-------
4. PROCESS PERFORMANCE GUARANTEE
A. The equipment will be guaranteed to reduce the paniculate and/or gas
contaminant loadings as indicated in the service description.
B. Performance test will be conducted in accordance with I.G.C.I, test methods
where applicable.
C. Testing shall be conducted at a time mutually agreeable to the customer and the
vendor.
D. The cost of the performance test is to be included in vendor's turnkey proposal.
E. In the event the equipment fails to comply with the guarantee at the specified
design conditions, the vendor shall make every effort to correct any defect expeditiously at
his own expense. Subsequent retesting to obtain a satisfactory result shall be at the vendor's
expense.
5. GENERAL CONDITIONS
A. Materials and Workmanship
Only new materials of the best quality shall be used in the manufacture of items
covered by this specification. Workmanship shall be of high quality and performed by
competent workmen.
B. Equipment
Equipment not of vendor's manufacture furnished as a part of this collector shall be
regarded in every respect as though it were of vendor's original manufacture.
C. Compliance with Applicable Work Standards and Codes
It shall be the responsibility of the vendor to design and manufacture the equipment
specified in compliance with the practice specified by applicable codes.
D. Delivery Schedules
The vendor shall arrange delivery of equipment under this contract so as to provide for
unloading at the job site within a time period specified by the customer. Vendor shall
provide for expediting and following shipment of materials to the extent required to comply
with delivery specified.
-------
APPENDIX IV
STATISTICAL BASIS FOR DATA PRESENTATION
The cost quotations received from member companies have in every case been
averaged and the resulting values presented graphically in the body of the
report. Provided there is no more than a reasonable spread between the
quotations, it is helpful to treat the data received as a random selection from
among a "population" of twenty or so potential bidders. Statistical values for
the confidence limits of the mean cost have been calculated.
Calculation Method — The calculations performed by ***CONLIM are based
on the following formulas:
Confidence limits = X ± stn_i. Y
where
X = the sample mean, based on three bids in most cases
s= the sample standard deviation
t „ ,. Y the (yX 100) percentage point of the student-t distribution
with n-1 degrees of freedom
Size of sample - n, usually three
1 n
Sample mean value =— 3"^ Xj
" i= 1
1 n
Variance of sample = ~ 5"? (Xj - X)2
Standard deviation of sample =
Estimated population standard deviation =
n-1
-------
s
Standard error of mean =•==.
where
S - sample standard deviation
When the population is finite, a correction factor of (—^2 — ) is included in both
the variance and the standard deviation computations, as follows:
where
2
S =the corrected variance for finite populations
o
S - the non-corrected variance for infinite populations
N - the population size, usually taken as 20
n - the sample size, usually three
The results are presented graphically using a solid line on log-log paper for the
mean cost vs. equipment size, and dotted lines for the 75% and 90% confidence
intervals based on three bids (or the actual number of bids received) out to an
approximate population of 20 possible bidders.
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