EPA-450/3-73-010
December 1973
AIR POLLUTION CONTROL
TECHNOLOGY AND COSTS
IN SEVEN SELECTED AREAS
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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EPA-450/3-73-010
AIR POLLUTION CONTROL
TECHNOLOGY AND COSTS
IN SEVEN SELECTED AREAS
by
Industrial Gas Cleaning Institute
P.O. Box 1333
Stamford, Connecticut 06904
Contract No. 68-02-0289
EPA Project Officer: Paul A. Boys
Prepared for
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Water Programs
Office of Air Quality Planning and Standards
Research Triangle Park, N.C. 27711
December 1973
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This report is issued by the Environmental Protection Agency to
report technical data of interest to a limited number of readers.
Copies are available free of charge to Federal employees, current
contractors and grantees, and nonprofit organizations - as supplies
permit - from the Air Pollution Technical Information Center,
Environmental Protection Agency, Research Triangle Park, North Carolina
27711, or from the National Technical Information Service, 5285
Port Royal Road, Springfield, Virginia 22151.
This report was furnished to the Environmental Protection Agency by
Industrial Gas Cleaning Institute, Stamford, Connecticut, in fulfillment
of Contract No. 68-02-0289. The contents of this report are reproduced
herein as received from the contractor. The opinions, findings, and
conclusions expressed are those of the author and not necessarily
those of the Environmental Protection Agency.
Publication No. EPA-450/3-73-010
11
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CONTRACT NUMBER 68-02-0289
AIR POLLUTION CONTROL
TECHNOLOGY AND COSTS
IN SEVEN SELECTED AREAS
FINAL REPORT
(Submitted December 15, 1973)
by
L. C. Hardison, Coordinating Engineer
for
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
UNIVERSAL OIL PRODUCTS CO.
AMERICAN AIR FILTER COMPANY, INC.
AMERICAN STANDARD, INC.
INDUSTRIAL PRODUCTS DIVISION
BELCO POLLUTION CONTROL CORP.
BUFFALO FORGE COMPANY
THE CARBORUNDUM COMPANY
POLLUTION CONTROL DIVISION
CE AIR PREHEATER
THE CEILCOTE COMPANY, INC.
CHEMICAL CONSTRUCTION CORP.
POLLUTION CONTROL DIVISION
THE DUCON COMPANY, INC.
SUBS. OF U.S. FILTER CORP.
DUSTEX DIVISION
AMERICAN PRECISION INDUSTRIES, INC.
ENVIRONEERING. INC.
SUBS. OF THE RILEY COMPANY
ENVIROTECH-CORPORATION
ARCO DIVISION
BUELL DIVISION
NORBLO DIVISION
FISHER-KLOSTERMAN, INC.
FULLER COMPANY, DRACCO PRODUCTS
SUBS. OF GENERAL AMERICAN TRANSPORTATION CORP.
GALLAGHER-KAISER CORPORATION
INDUSTRIAL CLEAN AIR, INC.
JOHNS MANVILLE CORP.,
ENVIRONMENTAL SYSTEMS GROUP
THE KIRK & BLUM MANUFACTURING CO.
THE KOPPERS COMPANY, INC.
ENVIRONMENTAL SYSTEMS DIVISION
MATHEY-BISHOP, INC.
MIKROPUL, DIV. OF U.S. FILTER CORP.
PEABODY ENGINEERING CORPORATION
POLLUTION CONTROL-WALTHER, INC.
PRECIPITATION ASSOCIATES OF AMERICA, INC.
RESEARCH-COTTRELL, INC.
THE TORIT CORPORATION
WESTERN PRECIPITATION DIVISION
JOY MANUFACTURING COMPANY
WHEELABRATOR-FRYE, INC.
AIR POLLUTION CONTROL DIVISION
ZURN INDUSTRIES, INC.
AIR SYSTEMS DIVISION
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., Environmental Systems Division
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TABLE OF CONTENTS
Page No.
I. INTRODUCTION 1
II. TECHNICAL DATA 2
A. General Description
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
1. Phosphate Industry 11
a. Wet Phosphoric Acid (WPPA)
b. Super Phosphoric Acid (SPA)
c. Granular Triple Superphosphate (GTSP)
d. Diammonium Phosphate (DAP)
e. GTSP Storage
2. Feed and Grain Industry 193
a. Feed Mills
b. Flour Mills
c. Feed Flash Dryers
3. Paint and Varnish Industry 249
a. Open Kettles
b. Closed Reactors
4. Graphic Arts 331
a. Web Offset Printing
b. Metal Decorating
c. Gravure Printing
5. Soap and Detergent 429
a. Spray Dryers
b. Dry Product Handling
6. Lime Kilns 481
a. Vertical Rock Kilns
b. Rotary Sludge Kilns
7. Gray Iron Foundaries 561
a. Cupolas
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TABLE OF CONTENTS
(continued)
Page No.
C. Additional Cost Data
1. Discussion of Cost Basis 605
2. Operating Cost at Various Utility Cost Levels 607
3. Derived Cost Indices 610
4. Generalized Cost Data 677
List of Figures
List of Tables
List of Appencides
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LIST OF FIGURES
Page No.
Figure 1 Outline Map of U.S. Indicating Phosphate Producing Areas 13
Figure 2 Block Diagram of Phosphate Fertilizer Manufacturing Processes .... 15
Figure 3 Simplified Flow Scheme for Strong Acid Process 21
Figure 4 Schematic Flow Diagram for Wet Phosphoric Acid Process 23
Figure 5 Contribution of HF and SiF4 to Vapor Phase Fluorine
Content at 50°C 44
Figure 6 Concentration of Fluorine in Vapor Over h^SiFg Solutions 45
Figure 7 Concentration of Fluorine in Vapor Over h^SiFg Solutions
Vs. Temperature 46
Figure 8 Comparison of Scrubber Types 49
Figure 9 Sketch of Cross-flow Packed Scrubber 50
Figure 10 Combination Scrubber for WPPA Process 51
Figure 11 Capital Costs for Wet Scrubbers for WPPA Process Plants 61
Figure 12 Confidence Limits for Capital Cost of Scrubbers for WPPA
Process Plants 63
Figure 13 Confidence Limits for Capital Cost of Scrubbers for WPPA
Process Plants 65
Figure 14 Annual Cost for Wet Scrubbers for WPPA Process Plants 67
Figure 15 Schematic Flow Diagram for Vacuum Flash Superphosphoric Acid
Process 69
Figure 16 Schematic Representation of Polyphosphoric Acid Forms 75
Figure 17 Plot of Barometric Condenser Temperature Vs. Cooling Water/
Steam Ratio 78
Figure 18 Schematic Drawing of Water-Induced Venturi Scrubber 81
Figure 19 Schematic Drawing of Venturi Scrubber with Packed
Entrainment Separater 83
Figure 20 Capital Cost for Water Induced Venturi Scrubbers for SPA
Process Plants 89
Figure 21 Confidence Limits for Capital Cost of Water Induced Venturi
Scrubbers for SPA Process Plants 91
Figure 22 Confidence Limits for Installed Cost of Water Induced Venturi
Scrubbers for SPA Process Plants 93
Figure 23 Annual Cost for Water Induced Venturi Scrubbers for SPA
Process Plants 95
Figure 24 Capital Cost for Venturi Scrubbers with Packed Section for
SPA Process Plants 97
Figure 25 Confidence Limits for Capital Cost of Venturi Scrubbers with
Packed Section for SPA Process Plants 99
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Page No.
Figure 26 Confidence Limits for Installed Cost of Venturi Scrubber with
Packed Section for SPA Process Plants 101
Figure 27 Annual Cost for Venturi Scrubbers with Packed Section for
SPA Process Plants 103
Figure 28 Flow Diagram of Granular Triple.Superphosphate Plant 105
Figure 29 Flow Scheme of Phosphate Rock Milling Operation 109
Figure 30 Capital Cost of Wet Scrubbers for GTSP Process Plants 121
Figure 31 Confidence Limits for Capital Cost of Wet Scrubbers for
GTSP Process Plants 123
Figure 32 Confidence Limits for Capital Cost of Installed Wet Scrubbers
for GTSP Process Plants 125
Figure 33 Annual Cost of Wet Scrubbers for GTSP Process Plants 127
Figure 34 Schematic Flow Drawing for Diammonium Phosphate Process 129
Figure 35 Schematic Drawing of Scrubbers Used in DAP Tail Gas Treating ... 142
Figure 36 Acceptable Scrubber Combinations for DAP Process Plants 144
Figure 37 Capital Cost of Two Stage Cyclonic Scrubbers for DAP Process
Plants 151
Figure 38 Confidence Limits for Capital Cost of Two Stage Cyclonic
Scrubbers for DAP Process Plants 153
Figure 39 Confidence Limits for Capital Cost of Installed Two Stage
Cyclonic Scrubbers for DAP Process Plants 155
Figure 40 Annual Cost of Two Stage Cyclonic Scrubbers for DAP Process
Plants 157
Figure 41 Capital Cost of Venturi Cyclone Scrubbers for DAP Process Plants .. 159
Figure 42 Confidence Limits for Capital Cost of Venturi Cyclone Scrubbers
for DAP Process Plants 161
Figure 43 Confidence Limits for Capital Cost of Installed Venturi Cyclone
Scrubbers for DAP Process Plants 163
Figure 44 Annual Cost of Venturi Cyclone Scrubbers for DAP Process Plants . 165
Figure 45 Capital Cost for Packed Cross-flow Scrubbers for DAP Process
Plants 169
Figure 46 Confidence Limits for Capital Cost of Packed Cross-flow
Scrubbers for DAP Process Plants 171
Figure 47 Confidence Limits for Installed Cost of Packed Cross-flow
Scrubbers for DAP Process Plants 173
Figure 48 Annual Cost of Packed Cross-Flow Scrubbers for DAP Process Plants. 177
Figure 49 Sketch of GTSP Storage Building with 4,000,000 ft3 Interior 180
Figure 50 GTSP Storage Building with Cyclonic Scrubbers 183
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Page No.
Figure 51 Simplified Flow Diagram of a Feed Mill 199
Figure 52 Simplified Flow Diagram of a Modern Flour Mill : . . . . 202
Figure 53 Flash Drying Combined with Disintegration 207
Figure 54 Capital Costs for Fabric Filters for Flour Milling 219
Figure 55 Annual Costs for Fabric Filters for Flour Milling 221
Figure 56 Confidence Limits for Capital Cost of Fabric Filters
for Flour Milling 223
Figure 57 Capital Costs for Fabric Filters for Feed Grinding 227
Figure 58 Annual Costs for Fabric Filters for Feed Grinding .... 229
Figure 59 Confidence Limits for Collector Only Cost of
Fabric Filters for Feed Grinding 231
Figure 60 Capital Costs for Wet Scrubbers for Feed Flash
Dryers (High Efficiency) 235
Figure 61 Annual Costs for Wet Scrubbers for Feed Flash
Dryers (High Efficiency) 237
Figure 62 Confidence Limits for Capital Cost of Wet Scrubbers
for Feed Flash Dryers (High Efficiency) 239
Figure 63 Capital Costs for Thermal Incinerators for Feed
Flash Dryers 243
Figure 64 Annual Costs for Thermal Incinerators for Feed
Flash Dryers 245
Figure 65 Confidence Limits for Capital Cost of Thermal
Incinerators for Feed Flash Dryers 247
Figure 66 Paint Manufacturing Using Sand Mill for Grinding
Operation 251
Figure 67 Materials Flow Sheet for Paint Manufacturing '. 252
Figure 68 Typical Varnish Cooking Room 255
Figure 69 Modern Resin Production System 263
Figure 70 Hydrocarbon Emission for Dowtherm Kettle 270
Figure 71 Hydrocarbon Emission for Paint Kettle 271
Figure 72 Kettle Hydrocarbon Emission — 2 Batches Monitored . 272
Figure 73 Pigment Emission Control System 274
Figure 74 Thermal Combustion System for Resin Reactor or
Closed Kettle 276
Figure 75 Schematic Diagram of a Catalytic Combustion System
for Varnish Kettles 278
Figure 76 Capital Costs for Thermal Incinerators for the
Paint and Varnish Industry (Without Heat Exchange) 306
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Page No.
Figure 77 Capital Costs for Catalytic Incinerators for the
Paint and Varnish Industry (Without Heat Exchange) 307
Figure 78 Direct Annual Costs for Thermal and Catalytic
Incinerators for the Paint and Varnish Industry
(Without Heat Exchange) 308
Figure 79 Total Annual Costs for Thermal and Catalytic
Incinerators for the Paint and Varnish Industry
(Without Heat Exchange) 309
Figure 80 Capital Costs for Thermal Incinerators for the Paint
and Varnish Industry (With Heat Exchange) 322
Figure 81 Capital Costs for Catalytic Incinerators for the
Paint and Varnish Industry (With Heat Exchange) . . 323
Figure 82 Direct Annual Costs for Thermal and Catalytic
Incinerators for the Paint and Varnish Industry
(With Heat Exchange) 324
Figure 83 Total Annual Costs for Thermal and Catalytic
Incinerators for the Paint and Varnish Industry
(With Heat Exchange) . 325
Figure 84 Total Installed Costs for Thermal and Catalytic
Incinerators for the Paint and Varnish Industry .... 327
Figure 85 Web Offset, Publication 342
Figure 86 Emission Rates from Web Offset and Web Letterpress
Employing Heatset Inks 345
Figure 87 Web Letterpress, Publication 346
Figure 88 Web Letterpress, Newspaper 348
Figure 89 Rotogravure Printing Operation 349
Figure 90 Emission Rates from a Typical Rotogravure Printing
Operation 351
Figure 91 Metal Decorating Coating Operation 352
Figure 92 Metal Decorating Printing and Varnish Overcoating . .. 353
Figure 93 Products Produced at Various Oxidation Stages During
Combustion 357
Figure 94 Flow Diagram for Thermal Combustion Including
Possibilities for Heat Recovery 358
Figure 95 Flow Diagram for Catalytic Combustion Including
Possibilities for Heat Recovery , 359
Figure 96 Flow Diagram of Adsorption Process 360
Figure 97 Schematic Flow Diagram of Thermal and Catalytic
Combustion Without Heat Exchange for Web Offset
and Metal Decorating 365
Figure 98 Capital Costs for Thermal Incinerators for Web Offset
Printing (Without Heat Exchange) 369
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Page No.
Figure 99 Annual Costs for Thermal Incinerators for Web Offset
Printing (Without Heat Exchange) 371
Figure 100 Schematic Flow Diagram of Thermal and Catalytic
Combustion Without Heat Exchange for Web Offset
and Metal Decorating 373
Figure 101 Capital Costs for Catalytic Incinerators for Web Offset
Printing (Without Heat Exchange) 377
Figure 102 Annual Costs for Catalytic Incinerators for Web Offset
Printing (Without Heat Exchange) 379
Figure 103 Schematic Flow Diagram of Thermal and Catalytic
Combustion Without Heat Exchange for Web Offset
and Metal Decorating 381
Figure 104 Capital Costs for Thermal Incinerators for Metal
Decorating (Without Heat Exchange) 385
Figure 105 Annual Costs for Thermal Incinerators for Metal
Decorating (Without Heat Exchange) 387
Figure 106 Schematic Flow Diagram of Thermal and Catalytic
Combustion With Heat Exchange for Web Offset and
Metal Decorating 389
Figure 107 Capital Costs for Thermal Incinerators for Metal
Decorating (With Heat Exchange) . . 393
Figure 108 Annual Costs for Thermal Incinerators for Metal
Decorating (With Heat Exchange) 395
Figure 109 Schematic Flow Diagram of Thermal and Catalytic
Combustion Without Heat Exchange for Web Offset
and Metal Decorating 397
Figure 110 Capital Costs for Catalytic Incinerators for Metal
Decorating (Without Heat Exchange) 401
Figure 111 Annual Costs for Catalytic Incinerators for Metal
Decorating (Without Heat Exchange) 403
Figure 112 Schematic Flow Diagram of Thermal and Catalytic
Combustion With Heat Exchange for Web Offset and
Metal Decorating 405
Figure 113 Capital Costs for Catalytic Incinerators for Metal
Decorating (With Heat Exchange) 409
Figure 114 Annual Costs for Catalytic Incinerators for Metal
Decorating (With Heat Exchange) 411
Figure 115 Schematic Flow Diagram of Thermal Combustion With
Heat Exchange for Gravure Printing 413
Figure 116 Capital Costs for Thermal Incinerators for Gravure
Printing (With Heat Exchange) 417
Figure 117 Annual Costs for Thermal Incinerators for Gravure
Printing (With Heat Exchange) 419
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Page No.
Figure 118 Capital Costs for Carbon Adsorption for Gravure
Printing 423
Figure 119 Annual Costs for Carbon Adsorption for Gravure
Printing 425
Figure 120 Confidence Limits for Capital Cost of Carbon Adsorption
for Gravure Printing 427
Figure 121 Over-All Routes to Linear Alkylate Sulfonates (LAS),
Alpha-Olefin Sulfonates (AOS) and Alcohol Sulfates 432
Figure 122 Low- and High-Active Sulfonation Using Oleum 433
Figure 123 Alpha-Olefin Sulfonation Flowsheet 434
Figure 124 Typical Spray Drying Plant 437
Figure 125 Continuous Process for Soap Manufacture 440
Figure 126 Capital Costs for Wet Scrubbers for Soap and Detergent
Spray Drying (Medium Efficiency) 455
Figure 127 Annual Costs for Wet Scrubbers for Soap and Detergent
Spray Drying (Medium Efficiency) 457
Figure 128 Capital Costs for Wet Scrubbers for Soap and Detergent
Spray Drying (High Efficiency) 458
Figure 129 Annual Costs for Wet Scrubbers for Soap and Detergent
Spray Drying (High Efficiency) 459
Figure 130 Confidence Limits for Capital Cost of Wet Scrubbers for
Soap and Detergent Spray Drying (Medium Efficiency) 461
Figure 131 Confidence Limits for Capital Cost of Wet Scrubbers for
Soap and Detergent Spray Drying (High Efficiency) . 463
Figure 132 Capital Costs for Fabric Filters for Soap and Detergent
Spray Drying 467
Figure 133 Annual Costs for Fabric Filters for Soap and Detergent
Spray Drying 469
Figure 134 Confidence Limits for Collector Only Cost of Fabric
Filters for Soap and Detergent Spray Drying 471
Figure 135 Capital Costs for Fabric Filters for Soap and Detergent
Product Handling 475
Figure 136 Annual Costs for Fabric Filters for Soap and Detergent
Product Handling 477
Figure 137 Confidence Limits for Collector Only Cost of Fabric
Filters for Soap and Detergent Product Handling .... 479
Figure 138 Simplified Flow Sheet of a Typical Lime Manufacturing
Operation 482
Figure 139 Vertical Lime Kiln 484
Figure 140 Simplified Kraft Mill Flow Diagram 491
Figure 141 Kraft Pulping Recausticizing Flow Sheet 492
Figure 142 Cyclonic Gas Scrubber 508
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Page No.
Figure 143 Variable Orifice Scrubber 509
Figure 144 Lime Kiln Venturi Scrubber System '. .. . . 510
Figure 145 Capital Costs for Wet Scrubbers for Vertical Lime
Rock Kilns (Medium Efficiency) 515
Figure 146 Annual Costs for Wet Scrubbers for Vertical Lime Rock
Kilns (Medium Efficiency) 517
Figure 147 Capital Costs for Wet Scrubbers for Vertical Lime
Rock Kilns (High Efficiency) 518
Figure 148 Annual Costs for Wet Scrubbers for Vertical Lime
Rock Kilns (High Efficiency) 519
Figure 149 Confidence Limits for Capital Cost of Wet Scrubbers
for Vertical Lime Rock Kilns (High Efficiency) .... 521
Figure 150 Capital Costs for Fabric Filters for Vertical Lime
Rock Kilns 525
Figure 151 Annual Costs for Fabric Filters for Vertical Lime
Rock Kilns 527
Figure 152 Capital Costs for Electrostatic Precipitators for
Vertical Lime Rock Kilns (Medium Efficiency) 532
Figure 153 Annual Costs for Electrostatic Precipitators for
Vertical Lime Rock Kilns (Medium Efficiency) 533
Figure 154 Capital Costs for Electrostatic Precipitators for
Vertical Lime Rock Kilns (High Efficiency) 534
Figure 155 Annual Costs for Electrostatic Precipitators for
Vertical Lime Rock Kilns (High Efficiency) 535
Figure 156 Confidence Limits for Capital Cost of Electrostatic
Precipitators for Vertical Lime Rock Kilns
(High Efficiency) 537
Figure 157 Capital Costs for Wet Scrubbers for Rotary Lime Sludge
Kilns (Medium Efficiency) 542
Figure 158 Annual Costs for Wet Scrubbers for Rotary Lime Sludge
Kilns (Medium Efficiency) 543
Figure 159 Capital Costs for Wet Scrubbers for Rotary Lime Sludge
Kilns (High Efficiency) 544
Figure 160 Annual Costs for Wet Scrubbers for Rotary Lime Sludge
Kilns (High Efficiency) 545
Figure 161 Confidence Limits for Capital Cost of Wet Scrubbers for
Rotary Lime Sludge Kilns (High Efficiency) 547
Figure 162 Capital Costs for Electrostatic Precipitatbrs for
Rotary Lime Sludge Kilns (Medium Efficiency) .... 552
Figure 163 Annual Costs for Electrostatic Precipitators for
Rotary Lime Sludge Kilns (Medium Efficiency) .... 553
Figure 164 Capital Costs for Electrostatic Precipitators for
Rotary Lime Sludge Kilns (High Efficiency) 554
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Page No.
Figure 165 Annual Costs for Electrostatic Precipitators for
Rotary Lime Sludge Kilns (High Efficiency) 555
Figure 166 Confidence Limits for Capital Cost of Electrostatic
Precipitators for Rotary Lime Sludge Kilns
(High Efficiency) 557
Figure 167 Distribution of Iron Foundry Sizes (1969) 562
Figure 168 Schematic Flow Diagram of Cast Iron Production 566
Figure 169 Flow Diagram of Major Iron Foundry Operations 567
Figure 170 Trends in Types of Iron Foundry Furnaces 569
Figure 171 Typical Gray Iron Cupola 571
Figure 172 Capital Costs for Fabric Filters for Gray Iron
Foundry Cupolas 587
Figure 173 Annual Costs for Fabric Filters for Gray Iron
Foundry Cupolas 589
Figure 174 Confidence Limits for Capital Cost of Fabric Filters
for Gray Iron Foundry Cupolas 591
Figure 175 Capital Costs for Wet Scrubbers for Gray Iron
Foundry Cupolas (Medium Efficiency) 593
Figure 176 Annual Costs for Wet Scrubbers for Gray Iron
Foundry Cupolas (Medium Efficiency) 599
Figure 177 Capital Costs for Wet Scrubbers for Gray Iron
Foundry Cupolas (High Efficiency) 600
Figure 178 Annual Costs for Wet Scrubbers for Gray Iron
Foundry Cupolas (High Efficiency) 601
Figure 179 Confidence Limits for Capital Cost of Wet Scrubbers
for Gray Iron Foundry Cupolas (High Efficiency) . . . 603
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LIST OF TABLES
Page No.
Table 1 Abatement Equipment Types Selected for the Seven Process Areas . . 5
Table 2 Process Weight Table for Medium Efficiency for Particulate
Collection Cases Only 8
Table 3 Performance Levels Selected for Phase 11 and ! 11 Areas 9
Table 4 Typical Composition and Particle Size of Commercial Grades
of Florida Phosphate Rock 28
Table 5 Analyses of Pebble Phosphate Rock 29
Table 6 Feed to WPPA Process Before and After Calcination 30
Table 7 Wet Phosphoric Acid Product Breakdown 32
TableS Distribution of Fluorine in WPPA Plant Discharge Streams 33
Table 9 Florida Fluoride Emission Law 36
Table 10 Estimated Abatement Requirements Under Florida Law 39
Table 11 Calculated Concentrations of SiF4 and HF at 50°C 41
Table 12 Calculated Concentrations of Fluorine in Vapor Phase at 60°C
and 70°C 43
Table 13 Concentration Limits at Scrubber Outlet 53
Table 14 NTU Required to Reach 2.15 ppm F Discharge Concentration 55
Table 15 Process Description for Wet Process Phosphoric Acid Plant
Cross-flow Scrubber 57
Table 16 Operating Conditions for Wet Process Phosphoric Acid Plant
Cross-flow Scrubber 58
Table 17 Estimated Capital Cost Data (Costs in Dollars) for Wet Scrubbers
for WPPA Process Plants 60
Table 18 Confidence Limits for Capital Cost of Scrubbers for WPPA
Process Plants 62
Table 19 Confidence Limits for Capital Cost of Installed Scrubbers for
WPPA Process Plants 64
Table 20 Annual Operating Cost Data (Costs in $/Year) for Wet Scrubbers
for WPPA Process Plants 66
Table 21 Forms of Phosphoric Acid 74
Table 22 Process Description for Wet Scrubber for SPA Process
Specification 84
Table 23 Operating Conditions for Wet Scrubber 86
Table 24 Capital Cost Data (Costs in Dollars) for Water Induced Venturi
Scrubbers for SPA Process Plants 88
Table 25 Confidence Limits for Capital Cost of Water Induced Venturi
Scrubbers for SPA Process Plants 90
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Page No.
Table 26 Confidence Limits for Installed Cost of Water Induced Venturi
Scrubbers for SPA Process Plants
Table 27 Annual Operating Cost Data (Costs in $/Year) for Water Induced
Venturi Scrubbers for SPA Process Plants
Table 28 Capital Cost Data (Costs in Dollars) for Venturi Scrubber with
Packed Section for SPA Process Plants
Table 29 Confidence Limits for Capital Cost of Venturi Scrubbers with
Packed Section for SPA Process Plants
Table 30 Confidence Limits for Installed Cost of Venturi Scrubbers with
Packed Section for SPA Process Plants
Table 31 Annual Operating Cost Data (Costs in $/Year) for Venturi Scrubber
with Packed Section for SPA Process Plants
Table 32 Material Balance of GTSP Process for 250 Ton/Day
Table 33 Materials Evolved as Gases from Triple Superphosphate Manufacture
for 250 Ton/Day Process
Table 34 Process Description for Granular Triple Superphosphate
Specification
Table 35 Operating Conditions for Granular Triple Superphosphate Wet
Scrubber Specification
Table 36 Estimated Capital Cost Data (Costs in Dollars) for Wet
Scrubbers for GTSP Process Plants
Table 37 Confidence Limits for Capital Cost of Wet Scrubbers for GTSP
Process Plants
Table 38 Confidence Limits for Installed Cost of Wet Scrubbers for
GTSP Process Plants
Table 39 Annual Operating Cost Data (Costs in $/Year) for Wet Scrubbers
for GTSP Process Plants
Table 40 Approximate Material Balance of 1,000 Ton/Day DAP Process
Table 41 Combined Vents from Reactor and Granulator
Table 42 Rough Heat Balance for DAP Dryer for 1,000 Ton/Day Process
Table 43 Process Description for Wet Scrubbers for DAP Process
Table 44 Operating Conditions for Primary Scrubbers for DAP Process
Dryer Vents
Table 45 Operating Conditions for Secondary Scrubbers for DAP Process
Dryer Vents
Table 46 Estimated Capital Cost Data (Costs in Dollars) for Two Stage
Cyclonic Scrubbers for DAP Process Plants
Table 47 Confidence Limits for Capital Cost of Two Stage Cyclonic
Scrubbers for DAP Process Plants
Table 48 Confidence Limits for Installed Cost of Two Stage Cyclonic
Scrubbers for DAP Process Plants
92
94
96
98
100
102
111
113
117
119
120
122
124
126
134
136
138
145
147
148
150
152
154
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Page No.
Table 49 Annual Operating Cost Data (Costs in $/Year) for Two Stage
Cyclonic Scrubbers for DAP Process Plants 156
Table 50 Estimated Capital Cost Data (Costs in Dollars) for Venturi
Cyclonic Scrubbers for DAP Process Plants 158
Table 51 Confidence Limits for Capital Cost of Venturi Cyclonic Scrubbers
for DAP Process Plants 160
Table 52 Confidence Limits for Installed Cost of Venturi Cyclonic
Scrubbers for DAP Process Plants 162
Table 53 Annual Operating Cost Data (Costs in $/Year) for Venturi
Cyclonic Scrubbers for DAP Process Plants 164
Table 54 Estimated Capital Cost Data (Costs in Dollars) for Packed
Cross-flow Scrubbers for DAP Process Plants 167
Table 55 Confidence Limits for Capital Cost of Packed Cross-flow
Scrubbers for DAP Process Plants 170
Table 56 Confidence Limits for Installed Cost of Packed Cross-flow
Scrubbers for DAP Process Plants 172
Table 57 Annual Operating Cost Data (Costs in $/Year) for Packed
Cross-flow Scrubbers for DAP Process Plants 175
Table 58 Process Description for GTSP Storage Building Scrubber 185
Table 59 Operating Conditions for Scrubber Specification for GTSP
Storage Building Vent 186
Table 60 Estimated Capital Cost Data (Costs in Dollars) for Cyclonic
Scrubbers for GTSP Storage Vents 187
Table 61 Confidence Limits for Capital Cost of Cyclonic Scrubbers
for GTSP Storage 188
Table 62 Confidence Limits for Installed Cost of Cyclonic Scrubbers
for GTSP Storage 189
Table 63 Annual Operating Cost Data (Costs in $/Year) for Cyclonic
Scrubbers for GTSP Storage Vents 190
Table 64 Composition of Typical Feedstuffs Used in Manufacture of Feed ... 194
Table 65 Rations and Supplements for Brood Sows 196
Table 66 Beef Cattle Feed Supplements 197
Table 67 Sources of Air Pollution in Feed and Grain Industry 209
Table 68 Particle Size Analysis of the Primary Cyclone Catch and the
Secondary Fabric Filter Catch of Dust from a Railroad Receiving
Hopper Hood Controlling the Unloading of a Boxcar of Feed-Type
Barley 210
Table 69 Dust Losses from Cyclones 212
Table 70 Fabric Filter Process Description for Flour Milling Specification ... 216
Table 71 Fabric Filter Operating Conditions for Flour Milling Specification ... 217
Table 72 Estimated Capital Cost Data for Fabric Filters for Flour Milling 218
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Page No.
Table 73 Annual Operating Cost Data for Fabric Filters for
Flour Milling 220
Table 74 Confidence Limits for Capital Cost of Fabric Filters
for Flour Milling 222
Table 75 Fabric Filter Process Description for Feed Grinding
Specification 224
Table 76 Fabric Filter Operating Conditions for Feed Grinding
Specification 225
Table 77 Estimated Capital Cost Data for Fabric Filters for
Feed Grinding 226
Table 78 Annual Operating Cost Data for Fabric Filters for
Feed Grinding 228
Table 79 Confidence Limits for Collector Only Cost of Fabric
Filters for Feed Grinding 230
Table 80 Wet Scrubber Process Description for Feed Flash
Dryer Specification 232
Table 81 Wet Scrubber Operating Conditions for Feed Flash Dryer
Specification 233
Table 82 Estimated Capital Cost Data for Wet Scrubbers for
Feed Flash Dryers 234
Table 83 Annual Operating Cost Data for Wet Scrubbers for
Feed Flash Dryers 236
Table 84 Confidence Limits for Capital Cost of Wet Scrubbers
for Feed Flash Dryers (High Efficiency) 238
Table 85 Thermal Incinerator Process Description for Feed
Flash Dryer Specification 240
Table 86 Thermal Incinerator Operating Conditions for Feed
Flash Dryer Specification 241
Table 87 Estimated Capital Cost Data for Thermal Incinerators
for Feed Flash Dryers 242
Table 88 Annual Operating Cost Data for Thermal Incinerators
for Feed Flash Dryers 244
Table 89 Confidence Limits for Capital Cost of Thermal
Incinerators for Feed Flash Dryers 246
Table 90 Varnish Raw Material 254
Table 91 Composition of Oil and Varnish Fumes 267
Table 92 Emission Data Summary 269
Table 93 Thermal Incinerator Process Description for Resin
Reactor Specification 282
Table 94 Thermal Incinerator Operating Conditions for Resin
Reactor Specification (Without Heat Exchange) .... 285
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Table 95 Estimated Capital Cost Data for Thermal Incinerators
for Resin Reactors (Without Heat Exchange) 286
Table 96 Annual Operating Cost Data for Thermal Incinerators
for Resin Reactors (Without Heat Exchange) 287
Table 97 Thermal Incinerator Process Description for Open
Kettle Specification 288
Table 98 Thermal Incinerator Operating Conditions for Open
Kettle Specification (Without Heat Exchange) 291
Table 99 Estimated Capital Cost Data for Thermal Incinerators
for Open Kettles (Without Heat Exchange) 292
Table 100 Annual Operating Cost Data for Thermal Incinerators
for Open Kettles (Without Heat Exchange) 293
Table 101 Catalytic Incinerator Process Description for Resin
Reactor Specification 294
Table 102 Catalytic Incinerator Operating Conditions for Resin
Reactor Specification (Without Heat Exchange) .... 297
Table 103 Estimated Capital Cost Data for Catalytic Incinerators
for Resin Reactors (Without Heat Exchange) 298
Table 104 Annual Operating Cost Data for Catalytic Incinerators
for Resin Reactors (Without Heat Exchange) 299
Table 105 Catalytic Incinerator Process Description for Open
Kettle Specification 300
Table 106 Catalytic Incinerator Operating Conditions for Open
Kettle Specification (Without Heat Exchange) 303
Table 107 Estimated Capital Cost Data for Catalytic Incinerators
for Open Kettles (Without Heat Exchange) 304
Table 108 Annual Operating Cost Data for Catalytic Incinerators
for Open Kettles (Without Heat Exchange) 305
Table 109 Thermal Incinerator Process Description for Resin
Reactor Specification 310
Table 110 Thermal Incinerator Operating Conditions for Resin
Reactor Specification (With Heat Exchange) 313
Table 111 Estimated Capital Cost Data for Thermal Incinerators
for Resin Reactors (With Heat Exchange) 314
Table 112 Annual Operating Cost Data for Thermal Incinerators
for Resin Reactors (With Heat Exchange) 315
Table 113 Catalytic Incinerator Process Description for Resin
Reactor Specification 316
Table 114 Catalytic Incinerator Operating Conditions for Resin
Reactor Specif ication (With Heat Exchange) 319
Table 115 Estimated Capital Cost Data for Catalytic Incinerators
for Resin Reactors (With Heat Exchange) 320
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Table 116 Annual Operating Cost Data for Catalytic Incinerators
for Resin Reactors (With Heat Exchange) 321
Table 117 Commercial Printing Market 333
Table 118 Ink Consumption in 1968 334
Table 119 Physical Properties of Commonly Used Solvents 337
Table 120 Percentage Breakdown of Solvent Consumed for Ink
Dilution by Printing Process and Solvent Type (1968) 333
Table 121 Volume Breakdown of Solvent Consumed for Ink Dilution
by Printing Process and Solvent Type (1968) 339
Table 122 Volume Breakdown of Total Solvent Consumption by
Use and Solvent Type (1968) 340
Table 123 Percentage Breakdown of Total Solvent Consumption by
Use and Solvent Type (1968) 341
Table 124 Analysis of Dryer Exhaust Gas from Web Offset
Publication 344
Table 125 Thermal Incinerator Process Description for Web Offset
Printing Specification 364
Table 126 Thermal Incinerator Operating Conditions for Web
Offset Printing Specification (Without Heat Exchange) 367
Table 127 Estimated Capital Cost Data for Thermal Incinerators
for Web Offset Printing (Without Heat Exchange) . . . 368
Table 128 Annual Operating Cost Data for Thermal Incinerators
for Web Offset Printing (Without Heat Exchange) . . . 370
Table 129 Catalytic Incinerator Process Description for Web
Offset Printing Specification 372
Table 130 Catalytic Incinerator Operating Conditions for Web
Offset Printing Specification (Without Heat Exchange) 375
Table 131 Estimated Capital Cost Data for Catalytic Incinerators
for Web Offset Printing (Without Heat Exchange) . . . 376
Table 132 Annual Operating Cost Data for Catalytic Incinerators
for Web Offset Printing (Without Heat Exchange) . .. 378
Table 133 Thermal Incinerator Process Description for Metal
Decorating Specification 380
Table 134 Thermal Incinerator Operating Conditions for Metal
Decorating Specification (Without Heat Exchange) . . 383
Table 135 Estimated Capital Cost Data for Thermal Incinerators
for Metal Decorating (Without Heat Exchange) 384
Table 136 Annual Operating Cost Data for Thermal Incinerators
for Metal Decorating (Without Heat Exchange) ooo
Table 137 Thermal Incinerator Process Description for Metal
Decorating Specification _00
ooo
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Table 138 Thermal Incinerator Operating Conditions for Metal
Decorating Specification (With Heat Exchange) .... 391
Table 139 Estimated Capital Cost Data for Thermal Incinerators
for Metal Decorating (With Heat Exchange) 392
Table 140 Annual Operating Cost Data for Thermal Incinerators
for Metal Decorating (With Heat Exchange) 394
Table 141 Catalytic Incinerator Process Description for Metal
Decorating Specification 396
Table 142 Catalytic Incinerator Operating Conditions for Metal
Decorating Specification (Without Heat Exchange) . . 399
Table 143 Estimated Capital Cost Data for Catalytic Incinerators
for Metal Decorating (Without Heat Exchange) 400
Table 144 Annual Operating Cost Data for Catalytic Incinerators
for Metal Decorating (Without Heat Exchange) 402
Table 145 Catalytic Incinerator Process Description for Metal
Decorating Specification 404
Table 146 Catalytic Incinerator Operating Conditions for Metal
Decorating Specification (With Heat Exchange) .... 407
Table 147 Estimated Capital Cost Data for Catayltic Incinerators
for Metal Decorating (With Heat Exchange) 408
Table 148 Annual Operating Cost Data for Catalytic Incinerators
for Metal Decorating (With Heat Exchange) 410
Table 149 Thermal Incinerator Process Description for Gravure
Printing Specification 412
Table 150 Thermal Incinerator Operating Conditions for Gravure
Printing Specification (With Heat Exchange) 415
Table 151 Estimated Capital Cost Data for Thermal Incinerators
for Gravure Printing (With Heat Exchange) 416
Table 152 Annual Operating Cost Data for Thermal Incinerators
for Gravure Printing (With Heat Exchange) 418
Table 153 Carbon Adsorption Process Description for Gravure
Printing Specification 420
Table 154 Carbon Adsorption Operating Conditions for Gravure
Printing Specification 421
Table 155 Estimated Capital Cost Data for Carbon Adsorption
for Gravure Printing 422
Table 156 Annual Operating Cost Data for Carbon Adsorption
for Gravure Printing 424
Table 157 Confidence Limits for Capital Cost of Carbon Adsorption
for Gravure Printing 426
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Table 158 Typical Operating Conditions for Continuous Sulfonating
of Linear Alkylate 436
Table 159 Typical Synthetic Detergent Formulas 446
Table 160 Wet Scrubber Process Description for Soap and
Detergent Spray Drying Specification 452
Table 161 Wet Scrubber Operating Conditions for Soap and
Detergent Spray Drying Specification 453
Table 162 Estimated Capital Cost Data for Wet Scrubbers for
Soap and Detergent Spray Drying 454
Table 163 Annual Operating Cost Data for Wet Scrubbers for Soap
and Detergent Spray Drying 455
Table 164 Confidence Limits for Capital Cost of Wet Scrubbers
for Soap and Detergent Spray Drying (Medium
Efficiency) 460
Table 165 Confidence Limits for Capital Cost of Wet Scrubbers
for Soap and Detergent Spray Drying
(High Efficiency) 462
Table 166 Fabric Filter Process Description for Soap and
Detergent Spray Drying Specification 464
Table 167 Fabric Filter Operating Conditions for Soap and
Detergent Spray Drying Specification 465
Table 168 Estimated Capital Cost Data for Fabric Filters for
Soap and Detergent Spray Drying 466
Table 169 Annual Operating Cost Data for Fabric Filters for
Soap and Detergent Spray Drying 468
Table 170 Confidence Limits for Collector Only Cost of Fabric
Filters for Soap and Detergent Spray Drying 470
Table 171 Fabric Filter Process Description for Soap and
Detergent Product Handling Specification 472
Table 172 Fabric Filter Operating Conditions for Soap and
Detergent Product Handling Specification 473
Table 173 Estimated Capital Cost Data for Fabric Filters for
Soap and Detergent Product Handling 474
Table 174 Annual Operating Cost Data for Fabric Filters for Soap
and Detergent Product Handling 476
Table 175 Confidence Limits for Collector Only Cost of Fabric
Filters for Soap and Detergent Product Handling . .. 478
Table 176 Typical Analyses of High Calcium and Dolomitic
Commercial Limestones 488
Table 177 Typical Composition of High Calcium and Dolomitic
Quicklime 489
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Table 178 Typical Composition of Reburned Quicklime ...:.... 494
Table 179 Typical Compositions of Exhaust Gases from Lime Sludge
Kilns 497
Table 180 Breakdown of Fuel Usage in Lime Rock Kilns During 196; 498
Table 181 Typical Gaseous Sulfur Concentration Ranges and Average
for Lime Sludge Kiln Exhaust 499
Table 182 Typical Emissions of a Natural Gas-Fired Lime Rock Kiln 501
Table 183 Typical Emissions of a Pulverized Coal-Fired Lime
Rock Kiln 502
Table 184 Various Compositions of Lime Sludge Kiln Dust 503
Table 185 Typical Exhaust Gas Production for Several Lime Sludge
Kiln Sizes 504
Table 186 Theoretical Lime Rock Kiln Exhaust Rates for
Different Fuels 505
Table 187 Typical Particle Size Distribution of Vertical Lime
Rock Kiln Emissions 507
Table 188 Wet Scrubber Process Description for Vertical Lime Rock
Kiln Specification 512
Table 189 Wet Scrubber Operating Conditions for Vertical Lime
Rock Kiln Specification 513
Table 190 Estimated Capital Cost Data for Wet Scrubbers for
Vertical Lime Rock Kilns 514
Table 191 Annual Operating Cost Data for Wet Scrubbers for
Vertical Lime Rock Kilns 515
Table 192 Confidence Limits for Capital Cost of Wet Scrubbers
for Vertical Lime Rock Kilns (High Efficiency) 520
Table 193 Fabric Filter Process Description for Vertical Lime
Rock Kiln Specification 522
Table 194 Fabric Filter Operating Conditions for Vertical Lime
Rock Kiln Specification 523
Table 195 Estimated Capital Cost Data for Fabric Filters for
Vertical Lime Rock Kilns 524
Table 196 Annual Operating Cost Data for Fabric Filters for
Vertical Lime Rock Kilns 526
Table 197 Electrostatic Precipitator Process Description for
Vertical Lime Rock Kiln Specification 528
Table 198 Electrostatic Precipitator Operating Conditions for
Vertical Lime Rock Kiln Specification 529
Table 199 Estimated Capital Cost Data for Electrostatic
Precipitators for Vertical Lime Rock Kilns 530
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Table 200 Annual Operating Cost Data for Electrostatic
Precipitators for Vertical Lime Rock Kilns 531
Table 201 Confidence Limits for Capital Cost of Electrostatic
Precipitators for Vertical Lime Rock Kilns
(High Efficiency) 536
Table 202 Wet Scrubber Process Description for Rotary Lime
Sludge Kiln Specification 538
Table 203 Wet Scrubber Operating Conditions for Rotary Lime
Sludge Kiln Specification 539
Table 204 Estimated Capital Cost Data for Wet Scrubbers for
Rotary Lime Sludge Kilns 540
Table 205 Annual Operating Cost Data for Wet Scrubbers for
Rotary Lime Sludge Kilns 541
Table 206 Confidence Limits for Capital Cost of Wet Scrubbers
for Rotary Lime Sludge Kilns (High Efficiency) .... 546
Table 207 Electrostatic Precipitator Process Description for
Rotary Lime Sludge Kiln Specification 548
Table 208 Electrostatic Precipitator Operating Conditions for
Rotary Lime Sludge Kiln Specification 549
Table 209 Estimated Capital Cost Data for Electrostatic
Precipitators for Rotary Lime Sludge Kilns 550
Table 210 Annual Operating Cost Data for Electrostatic
Precipitators for Rotary Lime Sludge Kilns 551
Table 211 Confidence Limits for Capital Cost of Electrostatic
Precipitators for Rotary Lime Sludge Kilns
(High Efficiency) 556
Table 212 Average Annual Foundry Production in the United States 553
Table 213 Properties of Cast Irons 565
Table 214 Exhaust Gases Compositions from Four Different Cupolas 574
Table 215 Material Balance for Theoretical Cupola 576
Table 216 Particle Size Distributions of Emissions from Three
Different Cupolas 579
Table 217 Abatement Equipment Types Used for Collecting
Particulate Matter From Foundries 580
Table 218 Fabric Filter Process Description for Gray Iron
Foundry Cupola Specification 582
Table 219 Fabric Filter Operating Conditions for Gray Iron
Foundry Cupola Specification 583
Table 220 Fabric Filter Operating Conditions for Gray Iron
Foundry Cupolas 585
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Table 221 Estimated Capital Cost Data for Fabric Filters for
Gray Iron Foundry Cupolas 586
Table 222 Annual Operating Cost Data for Fabric Filters for Gray
Iron Foundry Cupolas 588
Table 223 Confidence Limits for Capital Cost of Fabric Filters
for Gray Iron Foundry Cupolas 590
Table 224 Wet Scrubber Process Description for Gray Iron
Foundry Cupola Specification 592
Table 225 Wet Scrubber Operating Conditions for Gray Iron
Foundry Cupola Specification 593
Table 226 Estimated Capital Cost Data for Wet Scrubbers for
Gray Iron Foundry Cupolas 596
Table 227 Annual Operating Cost Data for Wet Scrubbers for
Gray Iron Foundry Cupolas 597
Table 228 Confidence Limits for Capital Cost of Wet Scrubbers
for Gray Iron Foundry Cupolas (High Efficiency) 602
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LIST OF APPENDICES
Appendix I Complete Sample Specification
Appendix 11 Instructions for Submitting Cost Data
Appendix III Labor Cost Indices
Appendix IV Statistical Basis for Data Presentation
Appendix V List of Standard Abbreviations
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I. INTRODUCTION
The Industrial Gas Cleaning Institute (IGCI) is the national association of
manufacturers of gas cleaning equipment, used primarily for the abatement of
industrial air pollution. Under this twelve-month contract, the IGCI is collect-
ing and formalizing data on air pollution control in seven industrial areas
selected by the EPA. These areas are:
1. Phosphate Industry
2. Feed and Grain Industry
3. Paint and Varnish Industry
4. Graphic Arts Industry
5. Soap and Detergent Industry
6. Lime Kilns
7. Gray Iron Foundries
Phase I
Phase 11
Phase III
This report contains all of the technical information assembled for each of
the seven process areas. The technical material consists of a narrative description
of each of the process areas tabulated above, specifications for air pollution
abatement equipment for each, and a summary of capital and operating costs
for equipment, obtained from the IGCI member companies in response to the
specifications. The following section summarizes all of the technical data
assembled for this study.
II. TECHNICAL DATA
This section contains all of the data collected as part of this program.
This includes information on process descriptions, air pollution control
requirements, specifications and capital and operating costs for abatement
equipment used in these industries. 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
companies judged most qualified. In addition to IGCI member companies,
several non-members participated by supplying cost information. These
companies prepared cost estimates independently of one another. Air
Resources, Inc. consolidated the data and edited it with regard to format only.
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GENERAL DESCRIPTION
1. FORMAT
This study includes seven industrial areas that were divided into three
groups, each of which was covered by a separate phase report. In this final
report, the three phases are summarized.
There are seven 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 Filters
d. Other
3. Summary Comments
This material will not be presented in outline form, nor will each item
necessarily be included for each process area.
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2. SELECTION OF APPLICABLE EQUIPMENT TYPES
In previous studies conducted by the IGCI, particulate emissions were of
more concern than emissions of gaseous contaminants. In this study, there are
three process areas in which the gaseous emissions predominate, or are equally
important. These are:
Phosphate Industry — HFandSiF^
Paint and Varnish — hydrocarbons
Printing — organic inks and solvents
Also included are four areas where particulate emissions predominate:
Feed and Grain
Gray Iron Foundries
Lime Kilns
Soap and Detergent
Because of the wider range of potential air pollutants covered, abatement
devices of almost every conceivable type will be involved in the program. These
will include all of the gaseous control devices:
Wet Scrubbers
Gas Incinerators
Adsorption Units
and the particulate control devices:
Electrostatic Precipitators
Wet Scrubbers
Fabric Filters
In general, a given process is amenable to control by more than one type
of equipment. The Engineering Standards Committee of the IGCI has been
-------
responsible for selecting the types which will be considered in this program. In
many areas, the EPA is conducting simultaneous programs in which industry
surveys, source tests, and other programs may furnish additional insight into
the equipment types predominating in well-controlled installations. This
information was incorporated into the judgments reached by the Engineering
Standards Committee through a series of technical exchange meetings with the
EPA.
For the seven process areas covered by this study, selections of equipment
types to be studied were made during three Engineering Standards Committee
meetings and four technical exchange meetings. Present at the technical
exchange meetings were representatives of the following groups:
EPA Economic Analysis Branch
EPA Industrial Studies Branch
EPA Performance Standards Branch
IGCI Technical Director
IGCI Project Director
IGCI Engineering Standards Committee
ARI Project Coordinator
ARI Project Engineer
The end results of this selection process are presented on Table 1.
3. BASIS FOR PREPARING SPECIFICATIONS AND BID PRICES
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 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. In previous projects, two arbitrary levels of performance
were specified:
1. An "intermediate level" which corresponded to the Los Angeles
process weight requirements, and
2. A "high level" of performance which should show little or no
subjective evidence of emissions; that is no visible particulate matter, and no
detectable odor level.
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TABLE 1
ABATEMENT EQUIPMENT TYPES SELECTED
FOR THE SEVEN PROCESS AREAS
Process Area
Emission Source
Equipment Types
Phosphates
Feed and Grain
Paint and Varnish
Graphic Arts
Wet Phosphoric Acid Reactors
Superphosphoric Acid Process
Diammonium Phosphate Process
Granular Triplesuperphosphate Reactors
GTSP Storage
Feed Mills
Flour Mills
Feed Flash Dryers
Open Kettles
Closed Reactors
Web Offset
Metal Decorating
Gravure Printing
Soap and Detergent Spray Dryers
Dry Product Handling
Lime Kilns
Vertical Rock Kilns
Rotary Sludge Kilns
Packed Cross Flow Scrubber
Water Induced Venturi Scrubber
Venturi Scrubber with Packed
Mist Eliminator
Two Stage Cyclonic Scrubber
Venturi — Cyclone Scrubber
Packed Cross Flow Scrubber
Venturi — Cyclone Scrubber
Cyclonic Scrubber
Fabric Filter
Fabric Filter
Wet Scrubber, Thermal Incinerator
Thermal and Catalytic Incinerator
Thermal and Catalytic Incinerator
Thermal and Catalytic Incinerator
Thermal and Catalytic Incinerator
Thermal Incinerator, Adsorption
Fabric Filter, Wet Scrubber
Fabric Filter
Wet Scrubber, Fabric Filter,
Precipitator
Wet Scrubber, Precipitator
Gray Iron Foundries Cupola
Fabric Filter, Wet Scrubber
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These arbitrary levels served reasonably well with regard to the
specification of performance of particulate collection equipment. However,
they did not serve the intended purpose; i.e., the development of a relationship
between system cost and efficiency or performance level when:
1. gaseous pollutants were involved
2. when the pollutants were particulate but the plant was large or
3. the pollutants were particulate but the particles were large in
diameter.
In the latter two cases, the "intermediate level" of performance was likely to
be equally or more restrictive than the "high level".
In the case of gaseous emissions, the process weight basis for specifications
and the visible emission basis are clearly inappropriate. In these circumstances,
an alternative basis for setting performance level may be drawn from
regulations in force or proposed by state or local agencies, but unanimity with
regard to appropriateness is far less likely for gaseous contaminants than was
the case for particulates.
In phosphate fertilizer plants, the emission of gaseous fluorides in the form
of hydrogen fluoride and silicon tetrafluoride is the most critical problem.
These plants are mostly located in the State of Florida, which has adopted
stringent limitations on total fluoride emissions to protect sensitive citrus crops
from damage by fluorides.
It was agreed by discussion with EPA personnel that the regulations
adopted by the State of Florida and currently applicable to new plants (to be
enforced on existing plants in 1975) would be used as the basis for the lower
efficiency level, and one-half of that absolute emission rate would be used for
the higher efficiency case.
For the six process areas covered in Phases II and III, performance levels
were chosen during the technical exchange meetings. For those areas where the
emissions are particulate matter, performance levels were generally chosen as
follows:
Medium Efficiency — The process weight table published in the
Federal Register April 7, 1971
High Efficiency — A sufficiently low grain loading to achieve
a clear stack.
The process weight table used is presented in Table 2.
For those areas where the emissions are gaseous, performance levels were
-------
selected to correspond to the maximum practical abatement efficiencies
currently available to the industry under study. Table 3 shows the list of
performance levels selected for all six industries.
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 to 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 applications is included as Appendix I 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:
1. Air pollution control device. This includes only the flange-to-flange
precipitator, fabric filter, scrubber, etc.
2. Air pollution control auxiliary equipment. This includes major items
such as fans, pumps, etc.
3. Complete turnkey installation. This includes the design, all labor and
materials, equipment fabrication, erection 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 quoting is given in Appendix II.
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
the preparation of price quotations, the cost indices given in Appendix III 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.
(text continued on p. 10)
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TABLE 2
PROCESS WEIGHT TABLE FOR MEDIUM EFFICIENCY CASES*
Process Weight Rate of
Rate (Ib/hr) Emission (Ib/h.r)
100 0.551
200 0.877
400 1.40
600 1.85
800 2.22
1,000 2.58
1,500 3.38
2,000 4.10
2,500 4.76
3,000 5.38
3,500 5.96
4,000 6.52
5,000 7.58
6,000 8.56
7,000 9.49
8,000 10.44
9,000 11.2
12,000 13.6
16,000 16.5
18,000 17.9
20,000 19.2
30,000 25.2
40,000 30.5
50,000 35.4
60,000 or more 40.0
*Federal Register April 7, 1971
8
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TABLE 3
PERFORMANCE LEVELS SELECTED
FOR PHASE II AND III PROCESS AREAS
Performance Level
Process Area
Feed and Grain
Feed Mills
Flour Mills
Paint and Varnish
Open Kettles
Closed Reactors
Graphic Arts
Web Offset
Metal Decorating
Gravure Printing
Emission Type
Particulate
Particulate
Feed Flash Dryers Odor
Hydrocarbon Gas
Hydrocarbon Gas
Hydrocarbon Gas
Hydrocarbon Gas
Hydrocarbon Gas
Soap and Detergent
Spray Dryers Particulate
Dry Prod. Handling Particulate
Lime Kilns
Vertical Rock
Rotary Sludge
Gray Iron Foundries
Cupolas
Particulate
Particulate
Particulate
Medium
(1)
(1)
67% Removal
(1)
(1)
(1)
(1)
(1)
PWT (2)
(1)
PWT (2)
PWT (2)
PWT (2)
High
0.01 gr/ACF
0.01 gr/ACF
93% Removal
1600° F Maximum Incinerator Temp.
1600° F Maximum Incinerator Temp.
1600°F Maximum Incinerator Temp.
1600° F Maximum Incinerator Temp.
1600°F Maximum Incinerator Temp.
0.01 gr/ACF
0.01 gr/ACF
0.01 gr/ACF
0.01 gr/ACF
0.02 gr/ACF
(1) Only one efficiency level specified.
(2) PWT = Process Weight Table, See Table 2.
-------
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. Appendix III
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 were used for preparing total annual cost
figures.
4. PRESENTATION OF DATA
In general, the capital cost data is presented as a series of three graphs
showing capital costs as a straight-line plot on log-log paper. One graph shows
the capital cost for the air pollution abatement device, one shows the cost for
the total equipment and one shows the cost for the complete turnkey system.
Where it was possible to do so, an analysis of the confidence limits of the
sample is presented — where three quotations were obtained as a "sample" of
perhaps 20 possible suppliers who might have quoted. The confidence limits are
shown as dotted lines. Appendix IV contains a description of the mathematical
procedure involved.
In all specifications of pollution control equipment standard temperature
is70°F (530° R).
Operating costs are presented in graphic form in this report. Expanded
tables showing operating costs for various utility cost levels are also included in
some cases.
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 unit size where such
information makes a meaningful pattern.
10
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PHOSPHATE
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PROCESS DESCRIPTIONS, SPECIFICATIONS AND COSTS
1. PHOSPHATE ROCK PRODUCTS MANUFACTURE
Phosphorus is one of the elements essential to plant growth and animal
life. For this reason, it is a major constituent of chemical fertilizers and animal
feed supplements. The fertilizer-related uses of phosphorus have generated a
large segment of industry involved with the mining and processing of natural
phosphate rock deposits. This discussion includes this entire industry in a
general way, and several specific manufacturing processes within the industry in
detail.
Those sections of the phosphate rock processing industry chosen for
detailed study are as follows:
a. Wet Process Phosphoric Acid manufacture (WPPA)
b. Superphosphoric acid manufacture (SPA)
c. Diammonium Phosphate (DAP)
d. Granular Triplesuperphosphate manufacture (GTSP)
e. GTSP Storage
Phosphate rock deposits exist in high concentration in only a few small
geographic areas within the United States. Figure 1 is an outline map of the
United States indicating those locations where phosphate rock deposits are
found.'1' It is typical of the industry that the chemical processing plants which
use phosphate rock as raw material and generate finished fertilizer products are
located in the immediate vicinity of the mines and, therefore, within the
geographic areas indicated in Figure 1.
The initial paragraphs in this section will be devoted to a generalized
description of the over-all processing pattern within the phosphate fertilizer
industry. Subsequent sections are related to the specifics of each process.
GENERAL DESCRIPTION
Phosphate rock is generally found in rich deposits of fluorapatite, with
related minerals as impurities. Fluorapatite Ca-n-^fPO^ is extremely stable
11
-------
and insoluble in water. For this reason, the phosphate content is not readily
available for use by plants, nor is it leached from the deposits by percolation of
water. In order to convert the rock to useful fertilizers, it is necessary to alter
the chemical structure in such a way that the materials become at least
moderately water soluble, or, more precisely, soluble in plant juices. Several
chemical processes are used for converting the rock to soluble forms, three of
which are among the specific subjects of this discussion. The processes in
current use are:
(1) Phosphoric acid manufacture (wet process and electric
(furnace
(2) Normal Superphosphate
(3) Diammonium Phosphate
(4) Triplesuperphosphate
(5) Superphosphoric Acid
This discussion is concerned principally with those processes likely to be
incorporated in a modern fertilizer production facility. These are generally
arranged as shown in the block diagram in Figure 2. Ordinarily, ore
benefication (upgrading) to produce a concentrate with 70 to 75% CagfPO^
content,'3' or "70-75% Bone Phosphate of Lime". The scheme shown is
tailored to the processing of Florida pebble phosphate rock, which comprises
the world's largest source of phosphates.
Each of the processing steps involves some potential for the release of
fluorine compounds into the air, and in some cases paniculate solids as well.
The description of the process sequence and basic chemistry has been
oversimplified for this general description and the discussion of emission
sources and control methods deferred to the sub-sections dealing with each
specific process.
Phosphoric Acid Manufacture
The manufacture of phosphoric acid is involved with decomposition of the
fluorapatite by sulfuric acid. This dissolution or digestion process results in the
release of much of the fluorine as hydrofluoric acid or fluosilicic acid. Some of
this is discharged from the process and becomes a potential for air
12
-------
i-Uirni^T^p: \4-rM -sXltzLcfl^
FIGURE 1
OUTLINE MAP OF U.S. INDICATING
PHOSPHATE PRODUCING AREAS
-------
pollution, some is retained in the acid product, and some is discarded with
byproduct gypsum. The basic chemistry of the manufacture of phosphoric acid
is represented by the following equation:
Ca3(P04)2 + 3H2S04 + 6H20 -> 3 [CaS04 • 2H20] + 2H3P04 (1)
Phosphate Rock + Sulfuric Acid + Water ->Gypsum + Phosphoric Acid
Although some dust is generated by processing of dry rock, release of
gaseous fluorine-containing compounds constitutes the principal air pollution
sources which must be treated in a phosphoric acid plant.
It is unusual to apply phosphoric acid directly as a fertilizer component,
but it is more generally used in the manufacture of other phosphorus-
containing compounds for direct application as fertilizers.
TSP Manufacture
Triplesuperphosphate is one of the common fertilizer forms marketed. It
has a good balance of properties, including moderate water solubility, lack of
either strong alkalinity or basicity, and ease of handling. Triplesuperphosphate
is made by reacting phosphate rock with phosphoric acid according to the
following chemical reaction:
Ca3(P04)2 + 4 H3P04 + 3H20 -»- 3 [CaH4 (P04)2 • H20] (2)
Phosphate Rock + Phosphoric Acid + Water -^Triplesuperphosphate
In the acidulation process, part of the elemental fluorine contained in the
phosphate rock is released and again presents a potential for air pollution by
HF and by SiF4. In addition, both the rock charge material and the finished
products are granular solids which have significant dusting problems associated
with the bulk handling steps in the process
Earlier processes for the digestion of phosphate rock involved the
production of normal superphosphate by acidulation with sulfuric acid, and the
production of "run of pile" triplesuperphosphate. Both of these processes are
still widely used in existing fertilizer plants, but do not represent the best
current technology. The normal superphosphate process utilizes sulfuric acid to
produce the monocalcium phosphate rich material according to
Ca3(P04)2 + 2H2S04 + 4H20 + CaH4(P04)2 + 2(CaS04-2H20) (3)
Phosphate Rock + Sulfuric Acid + Water -^Monocalcium Phosphate + Gypsum
14
-------
OPERATIONS
AT MINE
X
OPERATIONS IN
FERTILIZER PLANT
1
SULFURIC
AC. ID
ORE
BENEFACTION
MIL-LI NG
SCREENING
TAIL-INGS
TO
WASTE
CALCINATION
WATER
WATER
WET
PHOSPHORIC
ACID
MA NU FACTU RE
GYPSUM
'-PRODUCT.
GRANULAR
MANUFACTURING
SUPER
PHOSPHORIC
ACID
MANUFACTURE
11
TSP
t
GRANULAR
DAP.-if-
MANUFACTURIN <3
STORAOE
DAP
STORAGE
USUALLY GTSPANDGDAP PRODUCTION
ARE ALTERNATIVES WITHIN A GIVEN PLANT
FIGURE 2
BLOCK DIAGRAM OF PHOSPHATE FERTILIZER
MANUFACTURING PROCESSES
15
-------
This process has been supplanted by TSP manufacture because the TSP is not
diluted by gypsum as is normal superphosphate.
The initial processes for manufacture of TSP utilized the "den" method,
where solidification and curing of the product took place on a slow-moving
belt. The chemistry of this process is substantially the same as that for the
GTSP process, but the emission sources are significantly different. The physical
properties of the product, called "run of pile" are less desirable than the
granular product, and the latter is expected to be predominant in the future.
DAP Manufacture
Diammonium phosphate is a desirable component of fertilizers which
require a high ratio of nitrogen to phosphorus. In this process, ammonia and
phosphoric acid are used as raw materials, and produce diammonium phosphate
as the principal product, with HF and SiF4 as byproducts. The basic chemistry
of the process is described by the following equation:
H3PO4 + 2NH3 -» (NH4)2 HP04 (4)
Phosphoric Acid + Ammonia ^-Diammonium Phosphate
NPK Manufacture
Fertilizers are usually blends of compounds containing available nitrogen,
available phosphorus and available potassium. The proper application of
fertilizers requires that these nutrients be supplied to the soil in the proportions
required for balanced plant nutrition. Soil tests are run to establish the
deficiency of each component in terms of tons/acre requirement for each
element. Commercially available fertilizers are then applied on the basis of
weight percent specifications for each nutrient in the particular fertilizer blend.
The composition of the fertilizer is represented by the manufacturer in terms
of pounds of each nutrient available per 100 pounds of total material. In order
to make the proper application of elements to the soil in a particular area, it is
usually necessary to apply several fertilizer blends. For this reason, it is
necessary that fertilizer manufacturers make available a wide variety of blends
of nitrogen, phosphorus and potash containing materials for the agricultural
industry. Several of the products described in this study are high
phosphate-content materials which have little or no nitrogen or potash content.
Diammonium phosphate contains both nitrogen and phosphate, but most
17
-------
compounded fertilizers are simply blends of phosphate materials with other
chemicals which are rich in nitrogen or rich in potash. The plants in which this
blending operation is carried out are called NPK plants, and carry out the
chemical operations of mixing, blending, granulating and product handling
associated with combining these elements into the commercial fertilizers in the
proper proportions.
Storage and Handling
Because both raw materials and products of phosphate fertilizer plants are
granular solids, there is a significant potential for air pollution emissions in the
form of dusts at points where handling, transferring, milling, drying, storing
and bagging of the solids are carried out.
Although these potential sources are important ones, this study has been
restricted principally to those from which potentially serious gaseous fluoride
emissions are likely. The only non-process source which falls into this category
is the storage and curing buildings in which the granular TSP or DAP products
are stored, cured and sometimes bagged. Within these buildings, the reactions
involved in the final manufacturing steps are completed, and some emission of
fluorine, moisture and heat occur. High ventilation rates through the storage
buildings are required to maintain reasonable working conditions within the
building. The ventilation air discharge from either DAP or TSP storage requires
treatment to prevent significant emissions of fluorine-containing gases.
Summary of Applications
Prior to initiation of this program, representatives of the Industrial Studies
Branch, the Performance Standards Branch, and the Economic Analysis Branch
of the Environmental Protection Agency agreed upon the applications of
equipment in the foregoing areas for which additional information on which
technology and costs data should be assembled by the Industrial Gas Cleaning
Institute.
Each of these applications is developed in some detail in the following
sections.
18
-------
PHOSPHORIC ACID MANUFACTURE
Phosphoric acid manufacture is carried out by the direct digestion of
phosphate rock in su If uric acid, or by the furnace method in which the rock is
reduced to elemental phosphorus. Digestion in concentrated acid is the most
widely used method for the production of phosphoric acid for use in fertilizers,
while the electric furnace method is used to prepare high purity acid.131 This
discussion is limited to the sulfuric acid or wet process, frequently designated
as the WPPA process.
Most of the wet process phosphoric plants in use are located in central
Florida, where the product is used in the manufacture of phosphate-containing
fertilizers. Several designs are in use, which differ in the detail but utilize nearly
the same basic process flow scheme. This process is often described as the
dihydrate process, because the byproduct gypsum formed is substantially all in
the dihydrate form.
The chemical operations required for countercurrent washing, leaching
and filtering of the rock involve steps which are difficult to carry out on a
continuous basis, particularly because very corrosive acid materials are used.
These problems have been solved by several ingenious designs.
PROCESS DESCRIPTION
Because the process flow scheme for a typical WPPA plant is relatively
complex, a simplified flow diagram omitting many of the process steps is given
in Figure 3. The discussion of basic process chemistry will refer to this flow
drawing. Figure 4 is a more detailed diagram of the same process, showing an
arrangement of process equipment which corresponds more closely with the
operating plants.
In Figure 3, calcined, ground rock is introduced into a digester where it is
slurried with a mixture of 24% phosphoric acid and 93% sulfuric acid. In the
case of phosphoric acid, the acid strength refers to wt.% P2^5' while the
sulfuric acid strength is given as wt.% h^SO^ Digestion of the rock is strongly
exothermic, and requires heat removal to maintain a low and uniform digestion
temperature, to keep the CaSO^ byproduct from dissolving. The cooling is
accomplished primarily by recycling a high slurry rate through a cooler chilled
by vaporization of water and in some older plants by blowing cooling air
through the digester. The reaction goes nearly to completion within the
digestion chambers.
The slurry is agitated and circulated from compartment to compartment
within the digester and a net stream of phosphoric acid-calcium sulfate slurry is
withdrawn for filtering.
19
-------
The filtering and washing operations are carried out on a series of filter
surfaces shown symbolically as drum filters in Figure 3. Here the phosphoric
acid-rich liquor entrapped within the solid CaSO^h^O crystal matrix is
gradually replaced by washing with more and more dilute solutions, until, on
the final filter, fresh make-up water is used for washing. The gypsum and
entrained water are then sluiced to a gypsum settling pond.
The wash-water produced at each filtering-washing stage is recycled back
into the process and contacted with solids of higher phosphoric acid content,
so these streams build up in concentration and finally leave the first filter stage
at about 30 wt.% phosphoric acid (throughout this discussion, "30 wt.% acid"
refers to the percentage by weight of P2®5 rather than HgPO^. The "weight
fraction of phosphoric acid" is, in this case, 41.5% HgPC^, which is equivalent
to30%P205).
A more detailed description of the process flow and equipment can be
given using Figure 4 as a basis. Here, calcined phosphate rock is shown entering
the process in three chambers of the digester along with 24 wt.% acid produced
within the process and 93% sulfuric acid used as a raw material. These acids are
mixed in a cooler which removes the heat of dilution of the H2S04.
The slurry of rock and acid is pumped from chamber to chamber as the
digestion reaction takes place with the concurrent solution of phosphate as
^s'D^4' s'"ca as ^SiFg, precipitation of gypsum, release of HF from the
fluorapatite, and volatilization of HF and SiF^. The gaseous byproducts are
swept away from the digester by the ventilation air stream.
The slurry of digested rock and acid progresses to a final digestion tank
(shown as tank No. 9 in Figure 4) from which it is pumped to a circular flat
pan filter where the countercurrent washing steps are carried out. The digestion
tanks and filters are designed as complementary units in modern WPPA plants.
Several versions of this design are in use, the most common of which is the
Prayon design, built under license of S. A. Metalurgique de Prayon by
Wellman-Powergas.141 The filter is composed of flat, pie-shaped segments with
slurry introduced above each section, and a vacuum drawn beneath the filter
bed. The entire bed, consisting of about 8 segments, rotates beneath stationary
feeding and washing connections, and after the solids have made one complete
circuit, each filter segment is reversed top-for-bottom and the spent gypsum
washed off for sluicing to the gypsum pond. This type of filter is known as a
Bird-Prayon tilting pan filter.
20
-------
CALCINED
GROUND
ROCK
A
2-4-
S3 T^
SULFUR 1C
ACID
VACUUM
FLASH
COOLER
FROM POND
PHOSPHORIC
ACID RECYCLE
WATER WASH
SO ^ ACID
STORAGE
C5YRSUM
SLUHRY
FIGURE 3
SIMPLIFIED FLOW SCHEME
FOR STRONG 'ACID PROCESS
21
-------
10% ACID
3O% ACID
CALCINED
PHOSPHATE
POND WATER
-4-% ACID
ROTATING FIL.TER
GYPSUM
Sl-URRY
TO
POND
SPENT L.IQUOR
TO POND
FL-UOSII-ICIC
ACID SCRUBBERS
3O°/o ACID
STEAM
L-INED
DIGESTION
TANKS
3O°/o ACID
STORAGE
EVAPO RATO R
FEED TANK
EVAPORATOR
EVAPORATOR
fcd t±d td
SETTLERS
~l
Y
r
v/
3O°/o ACID
TO
DAP OR TSP
MANUFACTURE
ACID
TO
DAP OR TSP
MANUFACTURE
STEAM
STEAM
FIGURE 4
STEAM
«> 4.0/0 PHOSPHORIC
ACID PRODUCT
SCHEMATIC FLOW DIAGRAM
FOR WET PHOSPHORIC ACID PROCESS PLANT
(GULF DESIGN PLANT)
ACID
TO
SUPERPHOSPHORIC
ACID
23
-------
Acid at 30% concentration from the rotating tilting-pan filter is discharged
to a 30% acid storage tank from which part is removed for use in DAP or TSP
manufacture and part is passed through a multiple effect evaporation system in
which the concentration is raised to about 54% P^Ofr ^ne evaP°rators use high
pressure steam to distill water overhead, and operate under vacuum to maintain
low evaporation temperature. The vacuum is usually maintained by two-stage
steam-jet ejectors with barometric condensers. In the concentration process, a
substantial amount of fluorine is driven off as SiF4. This is not ordinarily a
significant air pollution source, in that most of the gas leaving the evaporators
is steam rather than air and when the steam condenses in the barometric
condensers the SiF4 is combined with HP to form H2SiFg and condenses along
with it. However, if this material is allowed to escape to the gypsum pond, the
potential for profitable recovery of the fluosilicic acid is lost and it places an
additional chemical burden on the pond system.(5)
In Figure 4, each of the evaporators is shown equipped with a packed
scrubber for the collection of H2SiFg, which can be produced at 20 wt.%
concentration. One Florida processor reported the collection and sale of 5,000
T/year (on a 100 wt.% basis) of H2SiFg.(5)
Acid leaving the final evaporator is usually around 54 wt.% P2Og 'or ^4.5
wt.% H3PO4).
The acid is passed through a series of clarifiers to remove as much as
possible of the last traces of fines, and then discharged to storage. Product acid
at 54% concentration may be taken for manufacture of DAP or TSP fertilizers
prior to the final clarification stages. Acid for sale as product or for further
concentration to superphosphoric acid may be subjected to several additional
stages of clarification and may be centrifuged for final removal of fines.
CHEMISTRY OF PROCESS
The basic chemical reaction for the production of phosphoric acid by the
dihydrate process as given in equation (1) is repeated here:
}2 + 3H2S04 + 6H20 +3 [CaS04 • 2H20] + 2H3P04 (1)
25
-------
This equation oversimplifies the reactions taking place in several respects. Most
important from an air pollution standpoint is the presence of fluorine in the
rock as fluorapatite. This may be considered to take part in a chain of reactions
represented as follows:
3 [Ca3(P04)2] CaF2 ->- 3Ca3(P04)2 + CaF2
(5)
Fluorapatite ->• Tricalcium Phosphate + Calcium Fluoride
or Fluorspar
CaF2 + H2S04 + 2H2O + CaS04-2H20 + 2HF
(6)
Fluorspar + Sulfuric Acid + Water -^-Gypsum + Hydrofluoric Acid
If pure fluorapatite were the raw material for the digestion process, the
principal gaseous byproduct would be HF, part of which would be retained in
the acid and part would be liberated as gaseous HF. A major portion of the
fluorine would probably be retained in the solid phase as CaF2, which is
extremely insoluble in water.
There are, however, some significant side reactions which have a great deal
of influence on the disposition of the fluorine in the feed.
Principal among these are the reactions involving the solution of silica to
form H2SiFg. A substantial amount of silica is present in the feed, either as
free silica or as calcium, aluminum or iron silicates. Acidification of the rock
brings about a series of reactions which may be represented as follows:
CaF2 + H2S04 + CaS04 + 2HF
(7)
Calcium Fluoride + Sulfuric Acid -^-Calcium Sulfate + Hydrofluoric Acid
Si02 + 4HF +2H20 + SiF4
(8)
Silica + Hydrofluoric Acid -s-Water + Silicon Tetrafluoride
SiF4 + 2HF •+ H2SiF6
(9)
Silicon Tetrafluoride + Hydrofluoric Acid •+ Fluosilicic Acid
These reactions work to form HF, SIF4 and H2SiFg. These three may be
assumed to form an equilibrium system in the presence of water, from which
26
-------
the principal material escaping is Sip4 in the normal range of digestion
temperatures 130-170° F.(7)
FEED COMPOSITION
Several analyses of the typical Florida pebble phosphates are given in
Table4.(6) The analyses given do not report actual components, but rather
convenient equivalents; that is, the sulfate-containing materials are not reported
as such, but the total sulfur is reported as the equivalent SOg. Such an analysis
might be restated on the presumption that most of the phosphorus is present as
fluorapatite, the CO2 as carbonate, etc. Table 5 is a restatement of a typical
analysis, first using the assumption that the principal impurities are present as
common calcium compounds. A second restatement simply gives the analysis in
terms of weight percent of each element.
The analyses shown in Table 5 are used subsequently as the raw material
for hypothetical process plants defined for purposes of obtaining abatement
equipment costs.
The reaction process is further complicated if CaC03 and organic
materials present in most rock are allowed to enter the digester. Both give rise
to serious foaming problems and require the addition of costly anti-foaming
agents. Current practice usually avoids these problems by calcination of the
rock in fluidized beds. Calcination effectively drives off C02 from the
carbonates and oxidizes the organic material, without any significant loss of
phosphorus or fluorine. Table 6 illustrates the effect of calcination on the feed
composition.
The digestion reactions are aimed at producing the highest acid strength
possible while producing crystals of gypsum byproduct which have good
filtering characteristics. High temperature favors the production of high acid
strength, but causes several operating problems, such as high rates of CaSO^ •
Vih^O, or calcium sulfate hemihydrate, which is considerably more soluble
than the dihydrate and tends to cause serious scaling problems as the acid
cools. Other problems associated with high temperature operation of the
digester are excessive corrosion and high solubility of impurities in the product
acid. In most cases, the digester is control led to about 160- 185°F to produce
a digester-acid with about 30% P2®5 content.'61
Digester temperature is controlled either by blowing air into the slurry or
by vacuum flash evaporation of a part of the slurry recycle. The use of air
cooling is being supplanted by vacuum flash evaporation in the new plants.
27
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TABLE 4
TYPICAL COMPOSITION AND PARTICLE SIZE OF
COMMERCIAL GRADES OF FLORIDA PHOSPHATE ROCK
(a)
Specified BPL^ Range
68/66
70/68
72/70
Screen Analysis
75/74
77/76
BPL (by analysis)
P20g equiv.
H20
Fe203
AI203
Organic
Si02
C02
F2
CaO
so3
68.15
31.18
1.3
1.33
1.76
2.18
9.48
3.48
3.60
45.05
1.05
70.16
32.10
1.0
1.25
0.96
1.74
8.68
3.05
3.67
46.12
1.02
72.14
33.00
1.0
1.07
0.83
1.76
6.46
2.87
3.62
48.10
1.11
75.17
34.39
1.0
1.03
0.82
1.73
4.59
2.65
3.78
50.14
0.74
77.12
35.28
1.0
0.84
0.56
1.70
2.02
2.98
3.89
51.53
0.66
% Larger or Smaller Than Indicated Mesh Size
Specified Size(c) +50
+70
+100
+200
-200
85% through 100 mesh 1.5
90% through 100 mesh 1.0
5.5
4.0
14.0
10.0
25.0
24.1
75.0
75.9
(a) Dry basis
(b) Bone Phosphate of Lime
(c) All grades
28
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TABLE 5
ANALYSES OF PEBBLE PHOSPHATE ROCK
Analysis Same Analysis Same Analysis
Given Restated Restated
Wt. % Wt. % Wt. %
BPL
P2°5
H20
Fe2°3
AI2°3
Organic
Si02
C02
F2
CaO
S03
99.82
* ' Chemical combinations of these are uncertain.
(2) Assumed to be (CH)n
(72.14)
33.0
1.0
1.07
0.83
1.76
6.46
2.87
3.62
48.10
1.11
3Ca3(P04)2-CaF2
CaC03
CaF2
S03 -|
Si02
Fe203 L (1)
AI203 f
OxygenJ
Organic (2)
Water
79.0
6.5
1.3
1.1
6.5
1.1
0.8
0.9
1.8
1.0
110.0
P
Ca
Fe
Al
Si
Co
O
S
F
H
14.40
34.35
0.75
0.44
3.01
2.40
40.17
0.44
3.62
0.24
99.87
29
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TABLE 6
FEED TO WPPA PROCESS
BEFORE AND AFTER CALCINATION
To Calciner From Calciner
Charge T/D Ib/hr T/D Ib/hr
(P205) (520) (43,330) (520) (43,300)
3 [Ca(P04)2] • CaF2 1,245 104,000 1,245 104,000
CaC03 103 8,600
CaF2 20 1,710 20 1,710
CaO - - 58 4,800
Organ ics 28 2,340 - -
Other 179 14,650 179 14,650
Total 1,575 131,300 1,502 125,160
30
-------
Excessive su If uric acid is necessary in the digester to precipitate the
gypsum and assure near-complete solution of the phosphorus. Common
practice with Florida rock is to maintain between 1.5 and 2.5% free H^SC^ by
weight in the digester. This limits the loss of ?2O^ to 0.2 - 0.7 wt.% of the total
in the feed unreacted and discharged with the gypsum. In addition to this
loss, some additional material is lost by substitution of (HPO4=) ions for
(804=) ions in the gypsum crystal lattice during washing,'2) and a loss of acid
by entrainment in the filter cake. The overall efficiency of the process in
converting ?2®5 'n tne roc^ to phosphoric acid is about 95 to 97%.'6) Table 7
gives a typical composition of product acid.'61
The distribution of impurities in the rock, and in particular of fluorine, is
of concern in establishing the levels of pollutant concentration in the gas
discharge.
Several references indicate typical concentration levels of impurities in the
streams discharged from WPPA plants, or give percentage distributions of the
total incoming fluorine. Table 8 summarizes these references. It is apparent
that the total quantity of Sip4 stripped out of the acid in the digester will vary
with the digester temperature, the amount of cooling air used (which depends
on the balance between cooling by air sparging or impingement and cooling by
flash vaporization of slurry). The more cooling air used, the higher the fraction
of fluorine stripped out and the lower the concentration.
Current practice minimizes the use of air for cooling the reactor, and as a
consequence, the fluorine emission rate has been reduced below the values
indicated in Table 8 by several-fold. The reactor cooling load is distributed
principally between the sulfuric acid dilution cooler and the flash vaporization
cooler:11 5)
MM BTU/ton
P2°5
Sulfuric Acid Dilution 1.0
Cooler
Flash Vaporization 1.3
Cooler
Cooling Air 0.1
2.4
31
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TABLE 7
WET PROCESS PHOSPHORIC ACID
PRODUCT BREAKDOWN
Wt. %
T/D
Ib/hr
P2°5
F
SO-,
AI203
Fe203
Other
Water
Total
54
1.5
1.7
2.0
0.8
0.4
39.6
500
14.3
15.8
18.6
7.4
3.7
367.2
41,690
1,190
1,315
1,545
620
310
30,610
100.0
927.0
77,280
32
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TABLE 8
DISTRIBUTION OF FLUORINE IN WPPA
PLANT DISCHARGE STREAMS
Effluent
Rock Feed
Digester Vent
Gas
Filter Vents
Sump Vents
Discharge
With Gypsum
Collected by
Evaporator
Scrubber
Discharged
With 54%
Acid
Percent of Total F
By Weight
Given By
Source
100
5-10
5(e)
—
—
18-30(d)
30
35-50(d)
40
Used In
Hypothetical
Plant
100
1.5
—
—
30
40
28.5
Concentration
3.6 wt.%(a)
33-100(b)
200-500(c)
40-80(e)
mg/SCF
10-30(c)
mg/SCF
0.5
3-10(c)
mg/SCF
—
—
2-5
wt.%
*a'To match example in Table II
(b) Reference (4)
^Reference (8)
(d) Reference (9)
te) Reference (6)
(f)
Chosen to match current practice.
33
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34
-------
The quantity of air drawn through the digester is established by the
ventilation requirements rather than by the heat load.'15' The fluorine
distribution in the second column of Table 8 was assumed for use in the
remainder of this discussion.
A similar table could be prepared indicating the distribution of silica
among the various discharges from the process; this distribution is considerably
less critical from a pollution control standpoint, and it may simply be assumed
that the gaseous fluorine discharges are all in the form of SiF^ from the
relatively low temperature digester, and HSiF from the vacuum evaporators.
NATURE OF THE GASEOUS DISCHARGE
The most significant emission source in the typical WPPA process is the
ventilating air from the digester. This is treated, in many cases, in combination
with ventilating air streams from the filtration section of the plant and from
the barometric condenser pumps. However, the digester emissions will be
considered as a completely separate source in this study.
The digester vent gas consists of ambient air to which water vapor,
particulate dust, and SiF4 have been added as the air passes through the
digester. Some old designs use air sparging through the slurry to accomplish the
heat removal, while others employed jets of air blown down on the surface of
the slurry. Recent designs do not rely upon the ventilating air to cool the
reactor.
ABATEMENT REQUIREMENTS
The present Florida law, excerpted in Table 9, limits fluorine emissions
from new WPPA plants to 0.02 Ib/ton P2C>5- ln addition, old plants are
required to conform to this restriction by July 1, 1975. In effect, this limits the
emissions from a 500 T/D plant to 10 Ib/day, or about 0.42 Ib/hr. In each case
the law uses the weight of P2®5 fgd to the process.
By the most liberal interpretation, this would require the limitation of the
digester effluent gas fluorine content to this value and require a removal
efficiency of 99.82%. However, the overall emission specification for the
process is 0.02 Ib/T, and it is necessary to take into account the small amounts
of fluorine in the gas streams vented over the filters and from the barometric
condenser sumps in specifying the efficiency requirement for the digester.
35
-------
TABLE 9
FLORIDA FLUORIDE EMISSION LAW
(c) Phosphate Processing — the emission limiting standards for
phosphate processing are:
1. Fluorides (water soluble or gaseous-atomic weight 19) the following
quantities expressed as pounds of fluoride per ton of phosphatic materials
input to the system, expressed as tons of ?2^ for:
a. New plants or plant sections:
a 1. Wet process phosphoric acid production, and auxiliary equipment —
0.02 pounds of F per ton of P205-
a 2. Run of pile triple super phosphate mixing belt and den and auxiliary
equipment — 0.05 pounds of F per ton of P205-
a 3. Run of pile triple super phosphate curing of storage process and
auxiliary equipment — 0.12 pounds of F per ton of ^2^5-
a 4. Granular triple super phosphate production and auxiliary equipment.
i. Granular triple super phosphate made by granulating run-of-pile
triple super phosphate 0.06 pounds of F per ton of P2C>5-
ii. Granular triple super phosphate made from phosphoric acid and
phorphate rock slurry — 0.15 pounds of F per ton of P2O5-
a 5. Granular triple super phosphate storage and auxiliary equipment —
0.05 pounds of F per ton of ?2®5-
a 6. Di ammonium phosphate production and auxiliary equipment —
0.06 pounds of F per ton of ?2®$-
a 7. Calcining or other thermal phosphate rock processing and auxiliary
equipment excepting phosphate rock drying and defluorinating — 0.05 pounds
of F per ton of P2O5-
a 8. Defluorinating phosphate rock by thermal processing and auxiliary
equipment — 0.37 pounds of F per ton of P2C>5-
a 9. All plants, plant sections or unit operations and auxiliary equipment
not listed in a.1 to a.8 will comply with best technology pursuant to Section
2.03(1) of this rule.
b. Existing plants or plant sections. Emissions shall comply with above
section, 17-2.04(6)(c) 1.a., for existing plants as expeditiously as possible but
not later than July 1, 1975 or
b 1. Where a plant complex exists with an operating wet process
phosphoric acid section (including any items 17-2.04(6) 1., a., a.1. through a.6.
above) and other plant sections processing or handling phosphoric acid or
products or phosphoric acid processing, the total emission of the entire
36
-------
complex may not exceed 0.4 pounds of F per ton of ?2®5 'nPut to the wet
process phosphoric acid section.
b 2. For the individual plant sections included in 17-2.04(6)(c), 1., a.,
1.1. through 6.6 above but not included as a part as defined in 17-2.04(6)(c) 1.,
b., b.1 above, if it can be shown by comprehensive engineering study and
report to the Department that the existing plant sections are not suitable for
the application of existing technology, which may include major rebuilding or
repairs and scrubber installations, the emission limiting standard to apply will
be the lowest obtained by any similar plant section existing and operating.
37
-------
Table 10contains estimated gas flows, concentrations and loadings for all
three gas streams, and illustrates the relationship of the digester vents to the
other potential emission sources in the WPPA plant.
In addition to the gaseous fluorine in the digester vent, there is likely to
be a little (0.05 gr/scf) rock dust generated by the mechanical handling of the
calcined rock. This dust is quite likely to be removed incidentally to the
removal of fluorine, however, a nominal specification for particulate removal
efficiency is reasonable in that the rock contains some fluorine and will
contribute to the overall discharge if allowed to escape from the process. A
discharge of 0.005 gr/ACF of material with 3.5 wt.% F from a 500 T/D process
would add
x 25,000 x 60 x 0.035 = 0.037 Ib/hr
7000
or nearly 10% of the allowed fluorine emission.
POLLUTION CONTROL EQUIPMENT
Of the types of pollution control equipment available, only those
involving absorption, (wet scrubbers) or adsorption (solid reagent or adsorption
systems) are capable of removing gaseous fluorine compounds from ventilating
air. Wet scrubbers have been used almost exclusively for this service although
solid packed beds of limestone or alumina have been proposed for the removal
of fluorine by adsorption.111'
In this discussion only scrubbers have been considered as a part of the
demonstrated technology.
Wet scrubbing combines the ability to remove matter from gas streams by
impaction of the particulates on the surface of liquid droplets with the ability
to absorb gaseous constituents into the liquid phase. Both of these functions
are limited by the characteristics of the scrubbing liquor, the properties of the
materials to be removed and sometimes by characteristics of the two in
combination. In this case, the chemistry of the reactions between gypsum pond
water and the fluorine-containing gases discharged from the WPPA plant
reactor produce a gelatinous precipitate which tends to plug the packing in
scrubbers and limits the types of scrubbing equipment applicable.
The basic chemistry of the compounds of fluorine, silicon and water must
38
-------
TABLE 10
ESTIMATED ABATEMENT REQUIREMENTS
UNDER FLORIDA LAW
(for 500 T/D P205 WPPA plant)
Gas Flow, SCFM
Fluorine Content
mg/SCF
ppm
Ib/hr
Required Discharge
mg/SCF
ppm
Ib/hr
Efficiency Required, %
Digester Filter
99.80
Sumps Total
99.1
85
25,000 15,000 25,000 65,000
25
1,050
80
0.05*
2.15
0.16
5.5
231
11
0.05*
2.15
0.10
0.3
13
1
0.05*
2.15
0.16
—
99
0.05*
2.15
0.42
99.58
* Assumed equilibrium limited in scrubbing system.
39
-------
be considered in order to characterize the application. In the reactor the
fluorine contained in the fluorapatite or fluorspar goes into solution according
to one or more of the following reactions:
CaF2(s) + H2S04(1) + CaS04(s) + 2HF(1) (10)
2HF(1) + SiF4(1) «- + H2SiF6(1) (11)
or
A liquid vapor equilibrium is set up between the reactants in equation 11
above, which may be regarded as the reverse of equation 12.
H2SiF6(1) +2HF + + SiF4 + (12)
High temperature tends to drive the reaction to the right, increasing the
vapor pressure of both HF and SiF4, and tending to increase the relative
significance of silicon tetrafluoride as the fluorine-containing species. These
vapor pressures set a lower limit of concentration in the gas phase leaving the
scrubber. Although vapor pressure data for both HF and SiF4 is available for
the pure compounds, relatively little data is available in the literature on the
vapor pressures of the two in water solutions. One Russian paper'1 2) does
quote vapor pressures of both HF and SiF4 and these are used throughout the
remainder of this discussion.
Table 11 gives a conversion of the vapor pressure data to equilibrium ppm
of SiF4 and HF at various concentrations of H2SiFg in the liquid phase. The
last column in Table 9 gives the concentration of total fluorine in ppm F at
50° C.
Table 12 contains similar conversions for temperatures of 60 and 70°C.
Table 11 data are plotted in Figure 5, which shows the distribution between
fluorine vapor in equilibrium with acidic water at various temperatures. Figure
6 plots the total fluorine in the vapor with temperature as a parameter. Figure
7 is a cross plot of the data in Figure 6.
In addition to the reactions given, hydrolysis of SiF4 occurs when the
concentration of this component is higher than the equilibrium values,
according to
3SiF4 + 4H20 + Si(OH)4 + 2H2SiF6 (13)
40
-------
TABLE 11
CALCULATED CONCENTRATIONS OF SiF4 AND
HF AT 50°C
wt% mmHg ppm ppm SiF4 Total
H2SiF6 HF SiF4 HF SiF4 as ppm F ppm F
0.105 .0015 .0001 2.0 .1 0.4 2.4
0.55 .0018 .0002 2.4 .26 1.44 3.8
1.00 .0023 .0002 3.0 .26 1.44 4.4
2.64 .0030 .0003 4.0 .4 1.58 5.6
5.05* .0050 .0004 6.6 0.5 2.10 8.7
5.05* .0045 .0003 5.9 0.4 1.58 7.6
7.47* .0045 .0011 5.9 1.4 5.80 11.7
7.47* .0047 .0013 6.2 1.7 6.85 13.1
9.55 .0055 .0012 7.2 1.6 6.31 13.5
11.715 .0065 .0020 8.5 2.6 10.55 19.1
*Two experimental values were obtained at these concentrations.
41
-------
42
-------
TABLE 12
CALCULATED CONCENTRATIONS OF FLUORINE
IN VAPOR PHASE
AT60°C AND70°C
60°C 70°C
ppm ppm
Wt.% 4~x Wt.%
H2SiFg HF SiF4 Total H2SiFg HF as ppm F Total F
.105 2.24 1.58 3.82
.55 3.30 1.05 4.35 0.55 6.58 2.64 7.22
.55 2.77 1.58 4.35 1.09 9.50 4.21 13.71
1.00 5.00 2.10 7.10 2.61 9.60 5.80 15.40
2.61 7.65 1.58 9.23 5.05 14.60 6.31 20.91
2.61 6.71 3.70 10.41 5.05 14.10 6.31 20.41
5.05 10.9 3.16 14.06 7.47 15.80 17.90 33.70
5.05 9.75 2.64 12.39 9.55 18.30 24.7 43.0
5.05 11.45 4.75 16.20 11.715 31.5 54.2 85.7
7.47 7.76 5.80 13.56 14.48 52.0 156.5 208.5
7.47 11.45 13.70 25.15
9.55 10.8 14.75 25.55
11.715 13.0 21.6 34.6
14.48 28.0 55.5 83.5
43
-------
FIGURE 5
CONTRIBUTION OF HF AND SiF4 TO
VAPOR PHASE FLUORINE CONTENT AT 50°C
IO
CONCETMTRATION IN LIQUOR V/T.
44
-------
FIGURE 6
CONCENTRATIONS OF FLUORINE IN VAPOR
OVER H2SiF6 SOLUTIONS
4. ©
CONCENTRATION IN LIQUOR WT;
10
H»S-i.Ffi
45
-------
1-4-
100
46
FIGURE 7
CONCENTRATION OF FLUORINE IN VAPOR OVER
H2SiF6 SOLUTIONS VS. TEMPERATURE
WEIGHT %. H2S-i-FG) 2«
110
\SO 130 \40
TEMPERATURE °F
rso
I <£>O
-------
This reaction tends to occur as the temperature of a gas stream is reduced
in the presence of water, and leads to the formation of gelatinous deposits of
polymeric silica which tend to plug scrubber packings. This problem limits the
use of conventional packed countercurrent absorbers in this service, as well as
other contacting devices which have small gas passages which might plug up.
The remaining types of scrubbers which are likely to perform well in this
service are
(1) Spray towers
(2) Wet cyclonic scrubbers
(3) Venturi scrubbers
(4) Concurrent packed absorbers
(5) Cross-flow packed absorbers
Spray towers are not capable of the high efficiencies required for
compliance with present regulations. They may, however, be useful as
pre-contactors to cool the gas stream and remove fluorine at relatively high
concentration levels. They have relatively little pressure drop and can be used
to bring large volumes of pond water into contact with the digester gas to
reduce the temperature and improve the absorption equilibrium.
Wet cyclones are also limited in efficiency, but may be used as precoolers.
They have a higher pressure drop requirement at high liquid flows than do the
spray chambers.
Venturi scrubbers can bring about effective contact and gas absorption
when sufficient energy is imparted to the gas to atomize the scrubbing liquor
and create very small droplets. The contact time in a Venturi is very short, and
it has been found that the power requirements at a given level of fluorine
absorption are high as compared with packed scrubbers.'1 2'
Countercurrent scrubbers have an inherent advantage over concurrent or
cross-flow scrubbers for gas absorption applications where the concentration of
contaminant leaving the scrubber approaches equilibrium with the scrubbing
liquor. This advantage is most clearly explained by reference to Figure 8.
Here the concentration of contaminant in the gas phase is plotted as a
function of position in the scrubber. YI represents the inlet concentration and
47
-------
Y2 the outlet concentration. In a counter-current scrubber, Figure 8a, the
liquor contains some of the contaminant and has a composition such that gas in
equilibrium with it would have a concentration \i^ at the gas outlet, and y^' at
the gas inlet. The difference between y and y' at any point in the scrubber is
the absorption driving force.
The counter-current scrubber has the highest potential removal efficiency,
because it contacts the gas leaving the scrubber with the cleanest scrubbing
liquor.
The concurrent scrubber does just the opposite and tends to bring the
discharge gas into equilibrium with the most contaminated liquor. However,
the co-current scrubbers are considerably less prone to plugging with solids
than the counter-current, and also require less gas pressure drop to operate.
Both plugging potential and bringing about a close approach to
equilibrium are important in the WPPA application, and a compromise between
the efficiency of the counter-current and the mechanical advantages of the
co-current scrubber is reached in the cross-flow packed scrubber illustrated by
Figure 8c.
This type of scrubber has been widely used, either alone or in
combination with spray towers, Venturis, or wet cyclonics in phosphoric acid
plants. Figure 9 is a sketch of a cross-flow packed scrubber.'1 4) Combination
scrubbers, treating gases from all the sources in the WPPA plant have also been
used, as shown in Figure 10.(4)
In this discussion, the use of a cross-flow packed scrubber will be
considered as the principal contacting device, either alone or preceded by a
scrubber-cooler.
CHEMICAL REQUIREMENTS
The efficiency which can be obtained by a cross-flow scrubber is limited
by the pond water composition if this is used alone as the scrubbing medium.
In addition, the "pick-up" of fluorine as the water passes through the scrubber
is of importance in setting the minimum concentration attainable.
For the case of a 500 T/D plant as illustrated in Table 10,the required
outlet concentration is about 2.15 ppm F (this is approximate because the
scrubber outlet gas flow will be slightly different than the inlet flow on which
48
-------
FIGURE 8
COMPARISON OF SCRUBBER TYPES
MOU
IN VAPOR
0-. COUNTER CURRENT
SCRUBBER
CON-CUR RE NT
SCRUBBER
C. CROSS ri_OW
SCRUBBER
49
-------
CROSS-FLOW
PACKED SCRUBBER
Capacity
ACFM
T = 70' F.
2.100
4,000
5,900
8,000
10,000
12,000
13.800
16,300
18,000
20,500
22,000
"24,300
26.000
28,500
30,000
32.000
"34.000 "
36,000
38.000
40.000
42,000
44,000
46.300
48.500
50,000
Liquid
Rale
CPM
8- 16
11-22
14-28
17-34
19-38
21 42
22-44
24 -48
25-50
26-5?
28 56
29-58
30-60
31-62
32-64
33-66
"36-72
36-72
38 - 76
38-76
40-80
40-80
42-84
42-84
43-86
Minimum
Overall
Length
0
6'
7
7'
7-
7-6"
7-6"
8'
8-
8 6"
9'
9'
9'
9' -6
10'
9' -6"
10'
9-6'
10'
9'-6-
10'
10'
10-6"
10'
10' -6"
10-6"
Overall
Width
W
2-
2' - 9"
3-6"
4-3
4 -9"
5' j
5 - 6"
6
6 -3
6 t,
7
7-3'
7- -6"
7 -9"
8'
8 - 3
9'
9
9 6"
9 6
10'
10'
10 6"
10' 6
10' 9'
Overall
Height
H
4'
5'
5-6
6
6'-6~
7
7 6"
8
8 -6'
9r
9'
9' -6'
9' - 9-
H 3
10 6
10 9"
1( 6'
1
1
116
116
12'
1?
\?' 6
Base To
C/L Inlet
E
1-9
T 3
2' -6
,' 9
3
3 3
< 6'
39-
4
4' - 3-
43'
4'-6-
4- 8"
4'- 10'
5
5'-2~
5
53-
•.' 3~
5 -6
6'
6 -3'
6-3-
6 6-
6' 6
Inlet
Outlet
Dimensions
A>B
? x 2 6
? 9'x3-6
3 6' x 4
4 3 x 4 ()"
4 9-<5'
53 x 5 6"
5-6x6
6 x6 6
6 3' x 7
6'-6' x 7'-6-
7'x 7'-6'
7-3" x 8'
7-6' x8'3"
79x8-9
8 x9'
8-3 x 9'-3"
9' x 9'
9' » 9' 6
9' 6x9-6"
9 6 x 10
10 » 10'
10' x 10'-6'
10' 6'x 10'6-
10 6' x 11-
10 9 x 1 1'
Duct
Dia.
C
1?
16'
20
24
?6'
30'
32
36'
36'
40'
40
42"
42"
44"
48"
48'
48"
48'
54"
54"
54"
54"
60
60"
60"
Shipping
Weight
(Lbs.)
525
800
1.050
1.275
1,550
1 ,800
2,050
2.350
2.600
2.900
3,100
3.300
3.600
3.900
4,000
4,280
4,400
4,700
4,850
5,100
5,300
5.650
5.800
6,100
6,200
Operating
Weight
(Us.)
1.100
1 600
2,100
2600
3.100
3,500
3,900
4,400
4,800
5.250
5.600
6.000
6.400
6,900
7,100
7,500
7,900
8,300
8,600
8,950
9.350
9.750
10100
10,500
10700
NOTE: 1. Minimum base length (L) is 4 ft. tor all units.
2. All dimensions are approximate.
3. Pressure drop is approximately 0.4 in. W.C. per foot of packed depth.
4. Final dimensions will vary to meet specific operating conditions.
FIGURE 9
SKETCH OF A CROSS-FLOW PACKED SCRUBBER
50
-------
POND
WATER
POND
WATER
DISCHARGE
TO
ATMOSPHERE
GAS
FROM
REACTOR
FIGURE 10
COMBINATION SCRUBBER
FOR WPPA PROCESS
51
-------
this value was based). In order to achieve low level, it is necessary that the
water entering the scrubber have an equilibrium vapor pressure (y') lower than
this value.
Table 13 lists a number of calculated concentrations in equilibrium with
water of various fluosilicic acid contents and temperatures. A typical pond
water is likely to contain between 0.2 and 1.5 wt.% h^SiFg and average around
80° F. This is low enough to bring about acceptable scrubbing (provided the
scrubber is large enough) as long as the concentration is below about 1.0 wt.%
and the temperature in the scrubber is below 100°F. At 120°F, the pond water
would have to be near 0.1 wt.% hSiF for satisfactory performance.
The degree to which the scrubber approaches the limit set by the
composition and temperature of the pond water is often measured in terms of
the "Number of Transfer Units", or NTU. This is defined as
NTU =
NTU =
-Y2
Y1
In
_dy
v-v'
y-i -
- Y2'
(14)
(15)
where the scrubbing liquor is pure water, and the quantity of water flow is
large, Y1' = y2' = 0 and
NTU =
In
(16)
A scrubber called upon to bring about a 95% reduction in fluorine
concentration at a gas temperature of 100°F, operating in a range where the
concentrations in equilibrium with the pond water would be negligible, and the
NTU value required would be
Y1
NTU =
In
In
3.0
0.05 y1
20
The operation of the cross-flow scrubber must be such as to reduce the
concentration to the same range as that found in equilibrium with the pond
water. This requires a great deal of additional contact as illustrated in Table 14.
52
-------
TABLE 13
CONCENTRATION LIMITS AT SCRUBBER OUTLET
(Using
— Containing Pond Water)
ppm F
Temperature
at Scrubber
Discharge, °F
80
100
120
140
0
0
0
0
0
Fluorine*
0.1
0.4
1.0
2.1
3.5
Content
0.5
0.7
1.45
2.7
4.8
of Pond
1.0
0.9
1.8
3.5
6.1
Water, Wt. «
1.5
1.1
2.3
4.3
7.6
%
2.0
1.3
2.6
5
9
144
*NOTE: h^SiFg content is approximately ~T7 = 1.26
times fluorine content.
53
-------
Here the NTU values required for reaching 0.16 Ib/hr emission of F fora 500
T/D plant are given in terms of the pond water composition and temperature.
In preparing specifications for scrubbing systems, the two scrubbing
efficiencies specified will, in effect, be those for 0.5 wt.% fluorine with and
without a prescrubber.
54
-------
TABLE 14
NTU REQUIRED TO REACH 2.15 ppm F(1)
DISCHARGE CONCENTRATION
(NTU Units)(2)
Temperature
at Scrubber
Discharge, °F
80
100
120
Fluorine Content of Water from Scrubber, Wt.%
0 0.11 0.5 1.0 1.5 2.0
6.2
6.2
6.2
6.28
6.72
10
6.59
7.32
NA
6.72 6.91
8.00 NA
NA NA
7.22
NA
NA
140 6.2 NA NA NA NA NA
'"'' Total fluorine as SiF^ and HF, reported as F°
'^'Based on an inlet concentration of 1050 ppm F°.
55
-------
SPECIFICATIONS AND COSTS
The preparation of specifications for scrubbing equipment was based on
the definition of two hypothetical WPPA plants. The smaller of the two
corresponds in size to the 500 T/day example used throughout this section.
The larger process was taken as 900 T/day.
Ventilating air from the digester was presumed to be treated separately
from the other effluent gases. This air was taken at 25,000 and 36,000 SCFM
at the digester, and it was assumed that the gas was 75% saturated at 140° F.
This would result in an adiabatic saturation temperature of about 132°F if
insufficient cooling water were provided, and it would not be possible to
achieve the required reduction in fluorine. Therefore, it is necessary for the
scrubber manufacturer to take into account the additional water requirement
to cool the gases to approximately 100°F in order to meet the efficiency
requirements.
The ventilating air usage is not proportional to the plant throughput. For
this reason, the larger process may be assumed to require a lower ventilating
rate per ton of product than the smaller one. This is likely to pick up fluorine
at about the same concentration level as the small unit and, therefore, have a
potential for emission per ton of product which is lower than for a similarly
designed small plant. However, for purposes of this specification, a scrubber
with the same NTU, and presumably the same packing height, was specified so
as to make scrubber gas flow the only variable between the two specifications.
In order to ascertain the variation in cost with scrubber size, a low
efficiency case was specified in which the gas flow through the reactor was
reduced by one-third, and the residual fluorine content held constant. This
results in increasing the allowable concentration of fluorine in the effluent by a
factor of three and reduces the efficiency requirement for the scrubber. In this
case, the cost of the abatement system will be lower, even though the same
emission level is expected.
In order to make a reasonable presentation of the cost pattern, it must be
presumed that the cost is not fixed relative to plant size and total allowable
emission, but rather varies with design gas flow rate and allowable emission.
The freedom to reduce the ventilation rate through the digester allows the
process designer to improve the emission potential of the system and at the
same time to reduce the cost of pollution abatement equipment.
56
-------
TABLE 15
PROCESS DESCRIPTION FOR WET PROCESS
PHOSPHORIC ACID PLANT CROSS-FLOW SCRUBBER
This specification describes a scrubbing system to serve a Prayon-designed WPPA
facility of the specified size. The scrubbing system is to comprise a cross-flow packed
scrubber of non-plugging design, a fan to overcome the pressure drop through the scrubber
and ductwork, a recirculating pump (if required), a 100 ft. free-standing stack, and all
interconnecting ductwork. The scrubber supplier is to furnish the ductwork connecting the
digester to the scrubber, which will be approximately 120 feet long.
The scrubbing system is intended to serve only the reactor air vent. Other arrangements
will be provided for the filter ventilation and sump vents.
Pond water is available at 80°F with the following properties:
Design Min. Max.
Pond Water pH 2.0 1.2 2.2
Temp.,0 F 80.0 55 88
S04, wt. % 0.15 -
wt.% 0.1
wt. % 0.63 0.25 1.0
Fluorine, wt.% 0.5 0.2 0.8
The scrubber is required to produce the design performance when operating with the
"design" pond water conditions. The scrubber manufacturer shall specify the required water
circulation rate through the scrubber in order to accomplish both cooling of the reactor
effluent gases to 100°F or lower and absorption of fluorine containing gases at the specified
level.
Materials of construction shall be limited to the following, which shall be selected for
hydrofluoric acid service:
PVC
Rubber (below 160° F)
FRP (Dynel lined)
No metal parts shall be used where exposure to process gas or pond water may be
significant.
57
-------
TABLE 16
OPERATING CONDITIONS FOR WET PROCESS
PHOSPHORIC ACID PLANT CROSS-FLOW PACKED SCRUBBER
Plant Capacity, Ton/Day P^Og
Acid Strength, Wt. % P^05
From Digesters
From Evaporators
Fluorine Content, Wt. % F
Gas to Scrubbers
Flow, SCFM
Flow, DSCFM
Flow, ACFM
Temp., °F
Moisture, Vol. %
Fluorine^, Ib/hr
Fluorine^, ppm
Paniculate, Ib/hr
Paniculate, gr/SCF
Gas from Scrubbers
Flow, SCFM
Flow, DSCFM
Flow, ACFM
Temp. ° F
Moisture, Vol. %
Fluorine, Ib/hr
Fluorine, ppm
Fluorine Removal, Wt. %
Small
500
30
54
1.5
B
Large
900
30
54
1.5
D
8,333
7,040
9,433
140
15.7
60
2,400
3.6
0.05
7,540
2,040
7,960
100
6.7
0.16
7.1
99.73
25,000
21,050
28,300
140
15.7
80
1,050
10.8
0.05
22,600
21,050
23,700
100
6.7
0.16
2.35
99.80
12,000
10,100
13,533
140
15.7
86.6
2,400
5.2
0.05
10,800
10,100
11,000
100
6.7
0.29
8.9
99.66
36,000
30,300
40,600
140
15.7
115
1,050
15.5
0.05
32,500
30,300
34,400
100
6.7
0.29
2.95
99.75
(1' Total Fluorine reported as F ~.
58
-------
Paniculate, Ib/hr 0.032 0.097 0.46 1.4
Paniculate, gr/SCF 0.005 0.005 0.005 0.005
Paniculate Removal, Wt. %(5) 91.1 91.1 91.1 91.1
Estimated y',ppm 1.4 1.4 1.4 1.4
Estimated NTU required 5.92(3) 7.05(4> 5.75(3) 6.50(2-4)
<1 '/f is not expected that this paniculate removal specification will influence the scrubber
design.
^Please quote a scrubber with the same packing depth and NTU as for the "small" unit —
i.e. 7.05 NTU.
c\\
1 These should be quoted on the basis of a rounded off NTU value of 6. Please see the
supplementary scrubber price sheet attached.
(4) These should be quoted on the basis of a rounded off NTU value of 7.5.
(5) Total fluorine reported as F °.
59
-------
TABLE 17
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR WPPA PROCESS PLANTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
(ppm), Fluorine
Ib/hr, Fluorine
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
(ppm), Fluorine
Ib/tir, Fluorine
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
(!) Supervision
(j) Startup
(k) Performance Test
(I) Other
(4) Total Cost
One-third Gas Flow
Small
9,433
140
8,333
15.7
2,400
60
7,960
100
7,540
6.7
7.1
0.16
99.73
8,370
4,357
2,240
2,037
— —
—
25,832
1,500
2,355
4,812
— —
3,300
_ _
710
1,475
6,900
38,559
Large
13,533
140
12,000
15.7
2,400
86.6
11,000
100
10,800
6.7
8.9
0.29
99.66
9,685
5,223
3,066
2,067
__
28,450
1,750
2,417
5,140
3,750
_ _
710
1,475
8,000
43,358
Normal Gas Flow
Small
28,300
140
25,000
15.7
1,050
80
23,700
100
22,600
6.7
2.35
0.16
99.66
17,703
8,533
4,886
3,495
—
36,270
2,000
3,000
7,285
4,575
__
710
1,475
9,150
62,506
Large
40,600
140
36,000
15.7
1,050
115
34,400
100
32,500
6.7
2.95
0.29
99.75
21,576
9,473
5,993
3,310
__
40,865
2,250
3,125
8,025
4,925
_ _
710
1,475
10,250
71,914
60
-------
FIGURE 11
500000
100000
CO
cc.
o
Q
te
o
o
0.
<
o
10000
1000
CAPITAL COSTS FOR WET SCRUBBERS
FOR WPPA PROCESS PLANTS
TURNKEY
COLLECTOR
PLUS AUXILIARIES
COLL
ECTOR ONLY '
ii
tf
f'li
if
•Vv
f
$
$\
T
;!i
'$
•f.
a
t
4
ji
.vrt^7
p^"
J
o
P'
—
-j
^*
^
^
J
(N
-- iy
(L
ASS R
5.
~ I
#^'
8^
fHfr
ORMAL GAS FLOW RANGE
1EDIUM EMISSION LEVEL)
3 NORMAL GAS FLOW RANGE
.OW EMISSION)
ANGE OF PRICES FOR
5 TO 7 NTU
I I I l l 1
1000
10000
GAS FLOW, DSCFM
100000
300000
61
-------
TABLE 18
CONFIDENCE LIMITS FOR CAPITAL COST
OF SCRUBBERS FOR WPPA PROCESS PLANTS
Population Size — 5 Sample Size — 2
Capital Cost = $17,702
Conf. Level,
50
75
90
95
Capital Cost, Dollars
Lower Limit Upper Limit
$16,663
15,401
12,930
10,262
$18,741
20,004
22,474
25,142
Capital Cost = $21,576
Conf. Level,
50
75
90
95
Lower Limit
$20,559
19,323
16,905
14,293
Upper Limit
$22,593
23,828
26,246
28,858
62
-------
FIGURE 12
CONFIDENCE LIMITS FOR CAPITAL COST
OF SCRUBBERS FOR WPPA PROCESS PLANTS
500000
100000
CO
DC
o
Q
te
o
o
_l
<
K
Q.
o
10000
1000
95% -
,75%~
MEAN
75%
95%
•;r
NORMAL GAS FLOW RANGE
(medium emission level)
10000
GAS FLOW, DSCFM
100000
300000
63
-------
TABLE 19
CONFIDENCE LIMITS FOR CAPITAL COST
OF INSTALLED SCRUBBERS FOR WPPA PROCESS PLANTS
Population Size — 5 Sample Size — 2
Installed Cost = $62,506
Conf. Level,
50
75
90
95
Installed Cost, Dollars
Lower Limit Upper Limit
$59,227
55,244
47,449
39,029
$65,785
69,767
77,563
85,982
Installed Cost = $71,914
Conf. Level,
50
75
90
95
Lower Limit
$71,609
71,238
70,513
69,730
Upper Limit
$72,219
75,589
73,314
74,097
64
-------
FIGURE 13
CONFIDENCE LIMITS FOR CAPITAL COST
OF INSTALLED SCRUBBERS FOR WPPA PROCESS PLANTS
500000.
100000
CO
DC
_i
_i
O
Q
te
O
0
51
0
10000
1000
<
M
35%
^^ ^
T /
/
9
K
!
NORMAL GAS FLOW RANGE
(medium emission level)
1000 10000 100000 300000
GAS FLOW, DSCFM
65
-------
TABLE 20
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR WPPA PROCESS PLANTS
O)
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
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$8/hr
$.011/kw-hr
$.25/M gal
$.05/M gal
One-third Gas Flow
Small
$ 854
1,920
75
850
850
3,703
3,856
7,559
Large
$1.504
2,200
100
1,400
1,400
5,209
4,336
9,545
Normal Gas Flow
Small
$ 2,404
3,105
150
2,770
2,770
8,387
6,251
14,638
Large
$ 4,204
3,415
200
4,350
4,350
12,182
7,191
19,373
-------
FIGURE 14
ANNUAL COST FOR WET SCRUBBERS
FOR WPPA PROCESS PLANTS
500000
V)
cc
o
Q
8
100000
10000
1000
4
4
>
f
*
f
s
p
/
/
u
L
r
X
r
j;
x^
x^
x^
X
>
_x
r
X
f
^
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
(
DPE
.R
A-
n
N
G COST
1000 10000 100000 300000
GAS FLOW, DSCFM
67
-------
SUPERPHOSPHORIC ACID
Superphosphoric acid (SPA) is a product of further dehydration of 54%
P20g phosphoric acid. It is useful in the manufacture of high quality fertilizers,
and in particular liquid fertilizers.
Because the further dehydration of phosphoric acid drives off most of the
remaining fluorine, super phosphoric acid is also prepared as an intermediate in
the production of low-fluorine content phosphoric acid or fertilizers.
Ordinarily, superphosphoric acid is prepared at concentrations in the
range of 72% P2^5 which corresponds to approximately 100% HgPO^
However, the product is not the pure orthophosphoric acid but a complex
mixture of ortho, pyro, tri and meta phosphoric acid forms.'21
PROCESS DESCRIPTION
Phosphoric acid of about 54 wt.% P2C>5 is charged to the process as
shown in Figure 15. Depending on the pretreatment of the 54% acid prior to
storage, and on the intended use of the SPA, further centrifugation or settling
for the removal of solids may be employed. The presence of solids in the SPA is
considerably more objectionable than in the ortho acid, especially if SPA is to
be used in the manufacture of liquid fertilizers.(6)
The 54% acid is pumped into the vacuum flash evaporator circulating
stream before the heat exchanger and admixed with hot circulating acid. The
mixture is circulated by gravity, using the density differential of the boiling
acid between the riser and the relatively cool acid in the return leg as the
driving force. The partially vaporized mixture is discharged into the vacuum
flash vessel where steam, Sip4 and HF are disengaged from the concentrated
acid. The liquid phase collects in the flash vessel and flows by gravity down the
return leg. Part of the liquid is drawn off at this point to the product cooling
tank and part is recycled to the heat exchanger.
The method of heating and vaporizing varies considerably from one
process design to another. The vacuum flash evaporator may be replaced by a
falling-film evaporator, in which the heat transfer and phase separation are
accomplished in a single vessel, or by a non-recirculated single-stage flash
process. The configuration of the vaporizer is not as important as the
down-stream equipment from an air pollution control standpoint.'6'
68
-------
VACUUM
FLASH.
EVAPORATOR
DOWTMERM
HEAT
EXCHANGER
^ PHOSPHORIC
ACID
STORAGE
n
HEATED
DOW THERM
RETURN TO
DOWTHERM HEATER
-PRODUCT
COOLER
JET EJECTORS
STEAM STEAM
POND WATER
COVERED
HO T WELL
RETURN
TO
POND
SUPER PHOSPHOR 1C
ACID PRODUCT
COOL I NO
WATER
FIGURE 15
SCHEMATIC FLOW DIAGRAM FOR
VACUUM FLASH SUPERPHOSPHORIC ACID PROCESS
69
-------
In several existing plants, the vaporization is accomplished by direct
contact of hot combustion gases with the phosphoric acid in an evaporation
chamber. This process, described as the "submerged combustion process"
differed widely from that described here. One of the principal draw-backs of
the process was the substantial volume of effluent gases contaminated with
fluorine. This problem has contributed to the reduced popularity of the
submerged combustion process.
The steam, acid fumes and non-condensable gases discharged from the
vacuum flash evaporator are cooled in a barometric condenser by circulating
pond water, and most of the steam and fluorine-containing compounds are
removed from the barometric with the water for return to the pond. It is
probable that the principal form of the fluorine compounds at the barometric
condenser inlet is HF, and that contact with the pond water causes an
equilibration between the HF and SiF4, which is the principal gaseous fluorine
compound leaving with the barometric condenser gaseous effluent.181
The barometric condenser is likely to operate at a high temperature —
130-160° F and the fluorine content of the steam-acid vapors discharged into
the condenser will be on the order of:
wt. F Fluorine removed from acid
wt. H20 Water removed from acid
wt. F 1 • (0.015-0.003) 0.012 . _,_ Ib
= 0.048
wt. H20 1 • (0.25 - 0.00)* 0.25 Ib H20
or nearly 5% fluorine. Condensation of this material in a surface condenser
would produce high concentrations of fluorine in the non-condensable gas
phase. However, the use of a large volume of pond water to condense the steam
provides for dilution of the liquid-phase fluorine content to a level closer to
that of the pond water than the calculated condensate concentration. The
concentration of fluorine discharged from the barometrics can be presumed to
be something in excess of the concentration in equilibrium with pond water at
the barometric condenser operating temperature.
'Water removed from acid in SPA process is based on:
54% P2O5 = 74.5% acid, 25.5% water
72% P2O5 = 100% acid, 0% water
71
-------
One or two stages of steam-jet ejectors may be used to pump
non-condensable gases and residual steam out of the barometric condenser and
up to atmospheric pressure. Each steam-jet ejector is equipped with a
barometric condenser to condense the steam used for motive power and the
residual steam present at the inlet.
In the flow scheme illustrated in Figure 15, it is apparent that the
non-condensables entering the system, steam load from the final barometric,
and the fluorine compounds which contaminate the combination of these two
constitute the only process emission source in the SPA plant. Two other
sources are usually piped into the same emission control device as the
barometric condenser vent. These are:
(1) the hotwells into which the discharge of cooling water from the
barometrics and product coolers flows, and from which pumps for
return of the cooling water to the gypsum pond take suction.
(2) the cooling tank.
Neither of these can be considered a process source in the ordinary use of the
term, because there is no gas generation or air usage required by the process. In
the case of the hotwells, it is a matter of convenience that these are allowed to
"breathe" through relatively loose-fitting covers which eliminate the need for
pressure controls to prevent flashing of water at the return pump suction, and
allow for easy access for cleanout and maintenance of the hotwell. Air leakage
through the covers is likely to provide the main gas source to the pollution
abatement device.
The hot liquid effluent from the flash evaporator is likely to be cooled in
a tank with cooling coils or surfaces in it. This is because the scaling properties
of the acid make it difficult to use shell-and-tube coolers. A cooler-surge tank
of this type requires a vent to accommodate changes in the liquid level, even
though the gas flow entering the tank on decreases in level ought to just equal
the gas flow leaving as the level increases. A vapor-tight surge system could
provide for intermittant breathing of the tank without any net gas flow.
However, such a system would be costly to build and maintain, and would
offer little advantage over simply venting the tank into the inlet of the
condenser vent scrubber.
The air pollution control device shown in Figure 15 as a Venturi scrubber
followed by a packed scrubbing section which serves as a gas absorber and mist
eliminator, uses pond water to provide final cleanup of the non-condensable
72
-------
gases and air leakage into the system before discharge to the atmosphere. This
gas stream is likely to be quite small, and can be treated by any of the
scrubbing devices which can handle small volumes of gas and do an effective
job of collecting aerosols and gaseous fluorides. A water-induced Venturi, or a
conventional Venturi-fan combination as shown, are the most commonly used.
CHEMISTRY OF THE PROCESS
"Phosphoric acid" may be considered as a dilute form of orthophosphoric
acid:121
392 Ib = 284 Ib + 108 Ib
4H3PO4 = P401Q • 6H20. (17)
At 54% PoOc by weight, the concentration of orthophosphoric acid in
392
water solution is 54 X 234 = 74.5. That is, a 100 pound sample of 54% ?2^^
acid may be assumed to contain 74.5 pounds of orthophosphoric acid plus 25.5
pounds of water.
More concentrated acids can be produced either by contacting the
ordinary phosphoric acid with anhydrous P2^5 or by evaporation of some of
the water. In either case, removal of the free water alone would limit the
concentration to 72.5% P2C>5 which corresponds to 100% HgPO^.
It is possible to further dehydrate the orthophosphoric acid by removal of
some of the molecular water, which converts the acid to forms other than
ortho. The forms known to exist'2' are listed in Table 21. The ions formed by
these acids are shown schematically in Figure 16.
Actually the dehydrated ortho acid species are mixed at most
concentrations above that for pure ortho, and form increasingly viscous
solutions as water is removed. Although vaporization of water from
concentrated acid can produce semi-solid syrupy products, pure solid forms of
the acids cannot be obtained by this procedure. Pure ortho and phosphoric
acids have been prepared by chemical synthesis. Orthophosphoric acid is a
white solid with a melting point of 42.3°C, and orthophosphoric acid
hemi-hydrate, 2H3P04 • H^O, melts at 29.35°C. Crystalline pyrophosphoric
acid melts at about 61°C.(2)
In order to obtain the concentrated polyacid forms, it is necessary to drive
73
-------
TABLE 21
FORMS OF PHOSPHORIC ACID
NAME
FORMULA
Orthophosphoric
or
Phosphoric Acid
or
H3P04
74.5
Pyrophosphoric
P4H1fJ:4H20
or
H4P207
80
Triphosphoric
or
Tripolysphosphoric Acid
P4H10:13° H20
or
H5P3°10
82.5
Metaphosphoric Acid
or
Tetrapolyphosphoric Acid
P4H1rj:2H20
or
HPOi
88.7
74
-------
FIGURE 16
SCHEMATIC REPRESENTATION OF
POLYPHOSPHORIC ACID FORMS
H
0
H : O : P : 0 : H
: 0 :
Orthophosphoric acid
0
0 : P : 0
0
-3
+ 3hT
(18)
H
: 0 :
H
H: 0: P: 0: P: 0: H
: O : : 0 :
H
H
H
: O : : O : : 0 :
H: 0: P: 0: P: 0: P: O: H
: 0 : : 0 : : 0 :
Pyrophosphoric acid
: 0 : : 0 :
: 0 : P : 0 : P : 0 :
: 0 : : 0 :
-4
4hT (19)
Metaphosphoric acid
: O : : O : : O :
O:P:0:P:0:P:0
: 0 : : 0 : : O :
-5
(20)
+ 5HH
75
-------
off most of the h^SiFg present in the 54% acid. This gives rise to some
potential for air pollution, although most of the fluorine-containing species are
automatically condensed with the water driven from the acid and recondensed
in barometric condensers. The fact that about 80% of the fluorine is distilled
out of the acid during the concentration process leads to the use of
superphosphoric acid to make low-fluorine orthophosphoric. As the super acid
is diluted, it reverts to the ortho form spontaneously.
In the vaporization process, temperatures as high as 700-800°F are
used.'6' The basic process is a simple flash distillation from which a vapor
consisting of water, SiF^ HF and traces of phosphoric acid is discharged, and a
liquid consisting of mixed phosphoric acids, including:
orthophosphoric
pyro
polyphosphoric
tripolyphosphoric
tetrapolyphosphoric
H2SiF6
Impurities
is produced.
POLLUTION CONTROL CONSIDERATIONS
The gas stream leaving the barometric condensers should consist mainly of
the air absorbed into the phosphoric acid charge plus air leakage into the
vacuum section of the process. While the absorbed air flow rate can be
calculated, the leakage rate cannot, as it depends upon the physical state of the
equipment. For this reason it is customary to base the design of the steam jet
ejectors on an assumed maximum leakage rate, and then to maintain the system
so as to stay within the design rate. Typical design rates for SPA plants are:
Plant Capacity Non-condensable
T/D P2O5 SCFM
100 150
300 200
500 250
The exit gas temperature from the final condenser stage is set by the ratio
76
-------
of cooling water to steam used. Figure 17 is a plot of a temperature vs. ratio for
a particular design. Thus for a non-condensable gas rate of 200 SCFM and a
ratio of 15/1 cooling water/steam on the last condenser stage, the vent from
the final condenser will have a composition as follows:
SCFM M.W. Ib/hr mo I %
non-condensables 200 28.8 942 75.8
water vapor 64 18 182 24.2
HF - 20 .00083 1 ppm
SiF4 - 104 .0085 2 ppm
Total fluorine - - .008 ~ 10 ppm
264 24.5 1,024
For other ratios of pond water to steam and other non-condensable gas
rates, similar tables could be constructed for purposes of specifying the inlet to
a scrubber for removal of fluorine.
The hotwell and tank vents are also combinations of air and
steam-HF/SiF4 vapors, where the total volume of gas is set by the design of the
hotwell covers and the composition and quantity of contaminants is
determined by the outlet temperature from the barometrics. In this case, it is
the average temperature of the water used in all of the barometric condensers
(if a combined hotwell is used) rather than the temperature from the last stage.
The leakage rate may be set by designing the covers to limit the area of
cracks around access ways and other openings, and then by designing the
ventilating system to maintain a slight negative pressure inside the enclosure to
induce an inward leakage velocity on the order of 200 FPM. This requires a
negative pressure on the order of:
2
AP= V
; Y f2P-2.r
.0086 Ib/fe
0.05 Xl^l 2 (2,1
2 X 32.2
62 4
= 0.0017 X-q^- = 0.0045 inches w.c.
A hotwell eight feet square with a 1/4 in. crack all around the edge would have
an area of:
1/4 0
(8 + 8 + 8 + 8) X ~ = 2/3 ft2.
77
-------
FIGURE 17
L
0
Id
y
DL
u
u
(A
5
£
z
y
o
o
o
E
y
0
cc
0
CO
0
0
0
t
8
ID ~
0
CO
78
CONDENSER TEMPERATURE
VS. COOLING WATER/STEAM RATIO
(FOR 80°F POND WATER)
to
20
2>O
RATIO, COOl-ING WATER TO STEAM, I_B/I_B
-------
This leakage rate is likely to be overshadowed by the need for an open
access way for maintenance and inspection. This would require about 250 FPM
ventilation rate and might be as large as 2' x 4', which would result in 2000
SCFM inward leakage. This gas flow is likely to comprise the main gas emission
source from the process. It is relatively arbitrary, in that the designer of the
process can limit the flow rate to any degree he chooses by careful design of
the enclosure. It is common to install a scrubber of nominal capacity, on the
order of 2500 SCFM for this service, regardless of the size of the plant.
Paniculate contaminants are limited to the liquid aerosols produced by
condensation within the process, or by mists formed by mechanical action in
the evaporator, condensers or elsewhere. The direct contact heat exchange
which brings about condensation of the water in the barometric condensers is
not likely to produce fine particle-size aerosols. The mechanically produced
mists have a large particle size, and can be removed from the gas stream at very
high efficiency by simple wet scrubbers. The principal problem is that of
removal of gaseous fluorides and a satisfactory scrubber for gaseous fluoride
removal will ordinarily be adequate for removal of the paniculate mists.
In the case where falling film evaporators, spray towers, or other specially
designed evaporators are used in place of the vacuum flash evaporator, it may
be possible to generate sub-micron aerosols in the evaporator. For this reason,
it should not be assumed that paniculate emissions can be ignored if an unusual
evaporator is incorporated into the system.
GAS CLEANING EQUIPMENT
As in the wet process for phosphoric acid manufacture, the SPA process
emissions are treated exclusively by wet scrubbers. This is due to the need for
gaseous fluorine removal from a wet gas stream, and the ready availability of
scrubbing liquor from the gypsum pond.
Three significant factors contribute to the frequent selection of
water-induced Venturi scrubbers for this service:
1. The gas flow is very low during normal operation.
2. There is likely to be a substantial variation in gas flow with time.
3. The water-induced scrubber does not require a fan.
79
-------
The water-induced Venturi scrubber, shown schematically in Figure 18, is
well suited for small gas flows, but seldom used for gas volumes over 5,000
ACFM. This is because it uses large quantities of water — relative to the gas
flow — to pump the gas through the scrubber, the inlet ductwork and the
discharge stack. Where the flow is not large, the inefficiency involved in the use
of the water jet is of less importance than the mechanical simplicity and
reliability gained by elimination of a fan from the system.
A second advantage of the water-induced Venturi for this service lies in its
relative insensitivity to reductions in gas flow rate.
Packed scrubbers and conventional Venturi scrubbers rely upon the
velocity of the gas passing through the scrubber for the energy required to give
good contacting of gas and liquid. For this reason they are likely to show
decreasing efficiency if the gas flow drops below 50 or 75 percent of the design
flow rate. The water-induced Venturi does not rely on the gas flow for motive
power, and will maintain high efficiency levels at extremely low gas flow rates,
provided the water supply is not reduced. This is particularly important where
the scrubber is arranged to handle gas leakage into a system with an access door
which may be opened periodically.
The water-induced Venturi is concurrent and limited to one theoretical
stage and therefore it may be necessary to add a packed section in the
entrainment separator vessel which serves to remove liquid droplets which
become entrained in the throat as well as to provide for additional gas
absorption when the gas flow rates are the highest.
The scrubbing requirements for SPA plants are rather nominal, and other
types of scrubbers, such as cross-flow packed units, conventional Venturi
scrubbers, mobile packed scrubbers and spray towers, each with an appropriate
fan, are probably acceptable but mechanically more complicated alternatives to
the water-induced Venturi in this application. A conventional Venturi scrubber
with a packed gas absorption section in the entrainment separator is shown in
Figure 19.
80
-------
FIGURE 18
SCHEMATIC DRAWING OF
WATER-INDUCED VENTURI SCRUBBER
POND
WATER
GAS
OUT LET-
OPTION AU
WATER SUPPLY
FROM POND
PACKING
WATER OUTL-ET
TO
HOTWEL.L. OR SUMP
81
-------
SPECIFICATIONS AND COSTS
Specifications were written for a scrubber for this application on the
assumption that the plant size does not significantly affect the size of the
scrubber. Rather, the requirement that the air leakage into the hot wells into
which the barometric condensers discharge is the main source of gas, and the
leakage into the hot wells is more a function of the type of access-way
ventilation required than the size of the plant.
Similarly, it was assumed that the emissions from hot wells and vents were
nominal, and that a nominal scrubber efficiency would be satisfactory.
82
-------
FIGURE 19
SCHEMATIC DRAWING OF
VENTURI SCRUBBER WITH
PACKED ENTRAPMENT SEPARATOR
POND
WATER
WATER
TO
POND
WATER
TO
POND
WATER
SUPPL-Y
FROM
POND
PACKING
t
STACK
INDUCED
DRAFT
FAN
83
-------
TABLE 22
PROCESS DESCRIPTION FOR WET SCRUBBER
FOR SPA PROCESS SPECIFICATION
The scrubber is to serve a 300 T/day Vacuum Evaporation superphosphoric acid plant.
The scrubber is to treat all of the gases discharged from the process vents as follows:
(1) Barometric Condenser vents
(2) Hotwell vents
(3) Hot product cooling tank vent
The scrubber is to use gypsum pond water with the following characteristics:
Design Min. Max.
Pond Water pH
Temperature, °F
SO4,wt.%
P2°5, wt- %
HySiFg, wt. %
Fluorine, wt. %
2.0
80
0.15
0.7
0.63
0.5
1.2
55
0.25
0.2
2.2
88
1.0
0.8
The scrubber is required to produce the specified performance when operating with
water at "design" conditions. The scrubber manufacturer shall specify the circulation rate
through the scrubber.
Materials of construction shall be limited to the following, which shall be selected for
hydrofluoric acid service:
PVC
Rubber (below 160°F)
FRP (Dynel lined)
No metal parts shall be used where exposure to process gas or pond water may be
significant.
84
-------
Two scrubbers are to be considered as alternatives for this service.
A. Water-Induced Venturi
The water-induced Venturi scrubber shall be furnished so as to provide for a negative
pressure of 1/4" w.c. at the inlet to the scrubber when processing gas at the design flow rate.
The scrubber shall be equipped with an entrainment separator and a stub stack which
extends to approximately 25 feet above grade.
The scrubber is to be located adjacent to the hotwells, to which it may be connected by
approximately 20 ft. of suitable ductwork, which is to be furnished as a part of the scrubber
installation. The o ther vents will be piped into the hotwell by the piping contractor.
B. Venturi with Optional Packed Section
The Venturi scrubber shall be furnished complete with fan, interconnecting ductwork
and 25 ft. discharge stack. The fan shall be sized so as to provide sufficient static head for
overcoming the pressure drop in the scrubber system and inlet ductwork.
The scrubber is to be located adjacent to the hotwells, to which it may be connected
with 20 ft. of ductwork which is to be furnished as a part of this installation. In addition, an
inlet damper and barometric damper shall be installed in the ductwork adjacent to the
scrubber inlet for adjusting the gas flow through the scrubber.
85
-------
TABLE 23
OPERATING CONDITIONS FOR WET SCRUBBER
FOR SPA PROCESS COMBINED VENTS SPECIFICATION
Plant Capacity, ton/day
Acid Strength, Wt.%P2O5
to Evaporator
from Evaporator
Fluorine Content, Wt.% F
to Evaporator
from Evaporator
300
54
72
1.5
0.4
Scrubber inlet Streams
Source
Flow, ACFM
Temp., °F
Flow, SCFM
Moisture, Vol.%
Flow, DSCFM
Fluorine, ppm
Fluorine, Ib/hr
Barometric
Condenser
287
147.5
250
24
190
10
0.008
Hotwell
2,120
100
2,000
6.7
1,880
5
0.030
Cooling
Chamber
264
100
250
6.7
234
30
0.024
Total to
Scrubber
2,671
105
2,500
7.8
2,304
8.25
0.062
Scrubber Outlet
Flow, DSCFM
Temp., °F
Moisture, Vol. %
Flow, SCFM
Fluorine, ppm
Fluorine, Ib/hr
Scrubber Efficiency, %
Estimated y', ppm
Estimated NTU requirement
2,304
100
6.7
2,470
1.455
0.011
82.5
1.4
5.0
86
-------
87
-------
TABLE 24
CAPITAL COST DATA (COSTS IN DOLLARS)
FOR WATER-INDUCED VENTURI SCRUBBERS
FOR SPA PROCESS PLANTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
(ppm), Fluorine
Ib/hr , Fluorine
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
(ppm), Fluorine
Ib/hr, .Fluorine
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
Nominal Efficiency
Small
1,335
105
1,250
7.8
8.25
0.031
1,310
100
1,235
6.7
1.455
0.0055
82.5
6,383
2,467
700*
250*
250*
300*
300*
375*
9,183
Large
2,671
105
2,500
7.8
8.25
0.062
2,620
100
2,470
6.7
1.455
0.011
82.5
8,603
2,673
760*
325*
250*
475*
300*
375*
11,843
Small
Large
*Items of installed cost, average of two bidders. Third bidder did not itemize.
88
-------
FIGURE 20
CAPITAL COST FOR WATER INDUCED VENTURI SCRUBBERS
FOR SPA PROCESS PLANTS
500000
V)
DC
o
Q
te
o
o
o.
<
O
100000
10000
1000
0
^^
a*^-^
^^
*&*•
/>*••
£fa
c
TURN KEY COST
i i i i i . i
COLLECTOR PLUS AUXII
1 i
OLLECTOR COST
ONLY
LIARIE
100 1000 10000 3000C
GAS FLOW, DSCFM
89
-------
TABLE 25
CONFIDENCE LIMITS FOR CAPITAL COST
OF WATER INDUCED VENTURI SCRUBBERS FOR SPA PROCESS PLANTS
Population — 5
Sample Size — 3
Capital Cost = $6,383
Conf. Level, %
50
75
90
95
Capital Cost; Dollars
Lower Limit Upper Limit
$5,162
4,018
2,258
630
$7,602
8,747
10,507
12,135
Capital Cost = $8,603
Conf. Level,
50
75
90
95
Lower Limit
$6,940
5,381
2,982
764
Upper Limit
$10,265
11,824
14,223
16,442
90
-------
FIGURE 21
CONFIDENCE LIMITS FOR CAPITAL COST
OF WATER INDUCED VENTURI SCRUBBERS
FOR SPA PROCESS PLANTS
500000
100000
CO
cc
o
D
k
O
o
_l
<
t
a.
O
10000
1000
90%
i
75%
i I
MEAN
75%
90%
1000
GAS FLOW, DSCFM
10000
30000
91
-------
TABLE 26
CONFIDENCE LIMITS FOR INSTALLED COST
OF WATER INDUCED VENTURI SCRUBBERS
FOR SPA PROCESS PLANTS
Population — 5
Sample Size — 3
Conf. Level,
50
75
90
95
Installed Cost = $9,182
Installed Cost, Dollars
Lower Limit Upper Limit
$ 7,999
6,889
5,181
3,603
$10,366
11,475
13,183
14,762
Conf. Level,
50
75
90
95
Installed Cost = $11,843
Lower Limit
$10,416
9,078
7,019
5,115
Upper Limit
$13,270
14,608
16,667
18,570
92
-------
FIGURE 22
CONFIDENCE LIMITS FOR INSTALLED COST
OF WATER INDUCED VENTURI SCRUBBERS
FOR SPA PROCESS PLANTS
500000
GO
oc
o
Q
fe
O
O
100000
10000
1000
•
1
m
1
••
*•
*•
^
3-^^-
y ^^
^-^*
J-*"
?r^
^^
^r
j€^"
90'
75^
ME
75^
90°
y -
70
/o
EA^
/D
4,
J
100 1000 10000 3000C
GAS FLOW, DSCFM
93
-------
TABLE 27
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR WATER-INDUCED VENTURI SCRUBBERS
FOR SPA PROCESS 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
Annualized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$8/hr
$6/hr
.011/kw-hr
.25/M gal
.05/M gal
Nominal Efficiency
Small
$ 200
74
442
$ 877
877
1,593
918
$2,511
Large
$ 200
76
540
$1,425
" 1,425
2,241
1,184
$3,425
Small
Large
-------
FIGURE 23
ANNUAL COST FOR WATER INDUCED VENTURI SCRUBBERS
FOR SPA PROCESS PLANTS
500000
100000
oo
DC
o
Q
fe
O
U
10000
1000
TOTAL COST
(OPERATING COST
PLUS CAPITAL CHARGES)
OPERATING COST
1000
GAS FLOW, DSCFM
10000
30000
95
-------
TABLE 28
CAPITAL COST DATA (COSTS IN DOLLARS)
FOR VENTURI SCRUBBER WITH PACKED SECTION
FOR SPA PROCESS PLANTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
(ppm), Fluorine
Ib/hr, Fluorine
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
(ppm), Fluorine
Ib/hr , Fluorine
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
Nominal Efficiency
Small
1,335
105
1,250
7.8
8.25
0.031
1,310
100
1,235
6.7
1.455
.0055
82.5
6,292
4,167
3,100*
800*
500*
13,597
2,600*
2,750*
1,500*
1,350*
2,150*
24,056
Large
2,671
105
2,500
7.8
8.25
0.062
2,620
100
2,470
6.7
1.455
.011
82.5
7,742
4,683
3,400*
800*
575*
16,155
2,650*
3,500*
^_
1,750*
1,550*
2,150*
28,580
Small
-
Large
*Items of installed cost, average of two bidders. Third bidder did not itemize.
96
-------
FIGURE 24
CAPITAL COST FOR VENTURI SCRUBBERS
WITH PACKED SECTION FOR SPA PROCESS PLANTS
500000
CO
QC
O
Q
te
o
u
Q.
<
o
100000
10000
1000
<
_•
_«
^
9&
^
9^^-
fr-^~
_r^*
&~~^
-&~
-e-
^e-~
Tl
p
JRIV
C
LUJ
JKE
OL
>AI
!Y
LE
J>
EC
(II
T(
LI
D
A
- COLLECTOR O
R
RIES
MLY
100 1000 10000 3000C
GAS FLOW, DSCFM
97
-------
TABLE 29
CONFIDENCE LIMITS FOR CAPITAL COST OF
VENTURI SCRUBBERS WITH PACKED SECTION
FOR SPA PROCESS PLANTS
Population Size —5 Sample Size — 3
Capital Cost = $6,292
Conf. Level,
50
75
90
95
Capital Cost, Dollars
Lower Limit Upper Limit
$5,515
.4,786
3,665
2,629
$7,069
7,797
8,918
9,954
Capital Cost = $7,742
Conf. Level,
50
75
90
95
Lower Limit
$6,713
5,748
4,264
2,892
Upper Limit
$8,770
9,734
11,218
12,591
98
-------
FIGURE 25
CONFIDENCE LIMITS FOR CAPITAL COST OF VENTURI SCRUBBERS
WITH PACKED SECTION FOR SPA PROCESS PLANTS
500000
V)
tr
o
o
8
_i
<
H
E
o
100000
10000
1000
•
-1
•
1
^
^
^
«*
•^
^
Or'**^~ -^
*£7 ^
l^>"_jr- *—
«-^^
^.^
fef^
©•^
• JW
^—
,-w
-•e^
90l
75
/o
%
- MEAI
7!
5%
M
_ 90%
100 1000 10000 3000C
GAS FLOW, DSCFM
99
-------
TABLE 30
CONFIDENCE LIMITS FOR INSTALLED COST OF
VENTURI SCRUBBERS WITH PACKED SECTION
FOR SPA PROCESS PLANTS
Population Size — 5 Sample Size — 3
Installed Cost = $24,055
Conf. Level,
50
75
90
95
Installed Cost, Dollars
Lower Limit Upper Limit
$22,423
20,893
18,538
16,361
$25,687
27,217
29,572
31,749
Installed Cost = $28,580
Conf. Level,
50
75
90
95
Lower Limit
$26,148
23,868
20,359
17,114
Upper Limit
$31,012
33,292
36,801
40,046
100
-------
FIGURE 26
CONFIDENCE LIMITS FOR INSTALLED COST OF VENTURI SCRUBBER
WITH PACKED SECTION FOR SPA PROCESS PLANTS
500000
V)
cc
o
o
k
8
0.
<
o
100000
10000
1000
tf
*
«
*
*
V
©, ^^
e- — -
9- —
.e-*
-e^
^^ «••
90
m
9C
%
EAF
%
M
100 1000 10000 3000C
GAS FLOW, DSCFM
101
-------
TABLE 31
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR VENTURI SCRUBBER WITH PACKED SECTION
FOR SPA PROCESS 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
Recirculating Pond Water
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$8/hr
$6/hr
$.011/kw-hr
$.05/M gal
Nominal Efficiency
Small
$1.227
700
612
610
377
987
3,526
2,406
5,932
Large
$1.227
608
728
1,164
604
1,768
4,331
2,858
7,189
High Efficiency
Small
Large
o
NJ
-------
FIGURE 27
ANNUAL COST FOR VENTURI SCRUBBERS
WITH PACKED SECTION FOR SPA PROCESS PLANTS
500000
100000
CO
oc
o
o
te
o
o
10000
1000
TOTAL COST
(OPERATING COST
PLUS CAPITAL CHARGES)
OPERATING COST
100C
GAS FLOW, DSCFM
10000
30000
103
-------
TRIPLESUPERPHOSPHATE GRANULATION PLANTS
Triplesuperphosphate is manufactured by acidulation of phosphate rock
with phosphoric acid. The two processes in common use differ in the method
of solidifying and drying the solid product. The older method discharges the
precipitated material onto a slow-moving belt or den and produces a solid
aggregate of varying particle size. This material is cured for thirty days or more
while the reactions go to completion, and is sold as run-of-pile (abbreviated
ROP), triplesuperphosphate.
The den method of production is being replaced by direct granulation of
the product as it is formed. This discussion deals exclusively with the
granulation process (GTSP) as it is applied to Florida phosphate operations.
. PROCESS DESCRIPTION
Figure 28 is a schematic flow diagram for a typical triplesuperphosphate
granulation plant.11 6)
Finely ground commercial rock is charged to the process from a ball or
roller milling and screening operation. The rock is metered onto a belt conveyer
at a fixed weight rate of flow and discharged into a reactor vessel. Thirty-eight
percent ^2®$ phosphoric acid is charged into the same reactor and formed into
a slurry with the phosphate rock. Ordinarily, this intermediate strength acid is
made by blending concentrated acid from the vacuum evaporation section of a
phosphoric plant at 54 wt. % ?2^^ strength with 30 wt. % phosphoric acid
taken directly from the digester section of the phosphoric acid plant. These
two streams are premixed in a combination mixer and hold tank which
provides some surge capacity.
The slurry is held and agitated until the reaction is near completion, and
the mixture overflows into a second reaction chamber where the acidulation
reaction is completed. Both reactor vessels are vented through a scrubber or
combination of scrubbers to the atmosphere. The slurry leaving the reactors
contains all of the product material plus additional free water which will be
vaporized in the drier. The liquid reactor effluent is fed into a horizontal
mixing vessel called a blunger where it is admixed with a recycled solid material
of smaller size than the desired product granules.
The blunger serves to further pulverize the undersized solids and mix it
into a paste with the liquid reactor product. This paste is discharged into a
104
-------
BL.UIMGER
BPL.
GROUND
PHOSPHATE
ROCK
SPRAY
CHAMBER
SCRUBBER
VENTURI
SCRUBBER
REACTORS
WATER
FROM
POND
WATER
FROM
POND
CYCLONE
PRIMARY
EN
SECONDARY
SCREENS
NATURAL.
GAS
DRIER -
<3RANUL_ATOR
SO 9«
PHOSPHORIC
ACID
ACID
PRODUCT
STORAGE
SPHERICAL.
GRANULES)
PHOSPHORIC
ACID
FIGURE 28
FLOW DIAGRAM FOR
TRIPLE SUPERPHOSPHATE
GRANULATION PLANT
105
-------
granulator-dryer from which water vapor, products of combustion and granular
solid products are discharged. The blunger and reaction tanks are usually
ventilated through a common scrubber and the gas is discharged to the
atmosphere. The dryer is heated by a direct-fired gas or oil burner. The solid
product leaving the dryer is discharged into a bucket elevator and lifted to a
primary screening device. The coarse material, larger than the desired product
granule size, is discharged from the screen into a mill which pulverizes it and
drops it onto a conveyer for return to the blunger. An intermediate screen
retains materials of approximately the desired product size range and drops the
fines through onto the same conveyer belt for return to the blunger. The
overflow from the product screen is discharged to a secondary screen where a
final separation is made between the product material and fines. Again, the
fines are returned to the blunger by the common conveyer belt. The granular
product is transported to a storage building where it is retained for six to eight
days while the "curing" reactions are completed.
The combustion gas from the granulator-dryer is discharged into a cyclone
where the fine TSP particles entrained are separated and returned to the
blunger by way of a common fines conveyer belt. The gas discharge from the
cyclone is vented to the atmosphere through a scrubbing system which serves
to remove particulate matter, chlorides, and in some cases sulfur dioxide.
CHEMISTRY OF THE PROCESS
The basic chemistry is represented in a superficial way by equation (2) as
follows:
Ca3 (PO4)2 + 4H3P04 + 3H20 -> 3 CaH4 (P04)2 • H20 (2)
Phosphate Phosphoric Water Monocalcium Phosphate
Rock Acid
This equation is oversimplified both by the omission of the fluorine component
of the f luorapitite rock, and also by the omission of the silica diluent. A better
representation is given in equation (22):
3 [Ca3(P04)2] CaF2 + 14H3PO4 + HQH20 +IOCaH4 (P04)2 ' H20 + 2HF (22)
Fluorapatite + Phosphoric Acid + Water -^Monocalcium Phosphate -> Hydrofluor-
ic Acid
107
-------
where the fluorine evolution as HF is indicated. However, as in the case of the
wet phosphoric acid manufacture, the chemical equilibrium between HF and
silicon tetrafluoride is represented by equations (23) and (24):
2HF + Si02 $ H20 + SiF4 (23)
Hydrofluoric Acid + Silica + Water + Silicon
Tetrafluoride
and
SiF4 + 2HF t H2SiF6 (24)
Silicon + Hydrofluoric + Fluorosalicic
Tetrafluoride Acid Acid
favors the emission of SiF4 at low temperatures.
A number of side-reactions take place and produce by-products such as
+ H2O
Ca3 (PO4)2 + H3P04 + 3Ca HP04 • 2H2O
Tricalcium + Phosphoric Water ->- Calcium (25)
Phosphate Acid Metaphosphate
None of these side reactions are of significance in the consideration of air
pollution emissions, however.
RAW MATERIALS
The principal raw material for the process is ground-to-size phosphate
rock similar to that used for wet process phosphoric acid manufacture. Figure 2
indicates the ore benefaction and milling and sizing steps which precede the
GTSP process.
Figure 29 shows a flow scheme of a phosphate rock milling operation.
Granular rock at about 1/4 inch size is delivered by rail or truck from a
benefaction plant to a loading hopper and loaded into a storage silo. Rock is
charged from the silo to a ball mill in which it is ground to 80% through a 100
mesh screen or finer.'1'
The mill discharge is conveyed pneumatically to a centrifugal classifier
which separates the ground rock according to particle size. The largest fraction,
108
-------
STORAGE
SIUO
BALL. MILJL.
FEED HOPPER
CENTRIFUGAL.
CL-ASSIFIER
«RANUL_AR
PHOSPHATE
ROCK—
BA1_I_ MILL.
.3OOOOO
STEEL- PA1 I *»)
AIR
TO
MANUFACTURE
TO
PHOSPHORIC
ACID
MANUFACTURE
FIGURE 29
FLOW SCHEME OF 6000 T/D
PHOSPHATE ROCK MILLING OPERATION
109
-------
TABLE 32
MATERIAL BALANCE OF GTSP PROCESS
FOR 250 TON/DAY
Acid Feed Rock Feed Product GTSP
P2°5
CaO
F
S03
AI203
Ton/day
175.0
—
4.3
5.6
6.5
Ib/hr
14,600
—
416
460
540
Ton/day
75.0
109.8
8.3
2.6
1.9
Ib/hr
6,250
9,150
685
212
163
Ton/day
250.0
109.8
9.1*
8.1
8.4
Ib/hr
20,850
9,150
800
672
703
Fe203 2.6 218 2.4 205 5.0 422
Other 1.3 108 25.2 2,100 13.7** 1,225**
Water 264.7 22,058 2.3 190 109.9*** 9,115***
Total 460.0 38,400 227.5 18,955 515.0 42,937
*Based on retention of 72.5 of F in solid product after storage.
**Based on evolution of CO2 and water as from decomposition of carbonates and
organic matter.
***Product moisture taken at 1 wt.% free hO.
111
-------
greater than 100 mesh, is returned to the mill.
Each of the ground products is transferred to intermediate storage prior to
charging to the next process in line.
Phosphoric acid makes up the only other raw material used. This is
obtained by blending 30% acid and 54% acid, which produces a total acid with
somewhat more fluorine in it than would be the case were all 54% acid used
and blended with water. However, no serious error will be introduced in this
discussion if the composition of 54% acid given in Table 7 is used.
Table 32 gives a material balance for a hypothetical process with a
production rate of 250 Ton/day P205- For purposes of preparing this table, it
was assumed that there was no loss of phosphorus values (i.e. that particulate
losses were substantially all returned to the process).
Several notations in Table 32 are significant with regard to air pollution
emissions. The following approximate fluorine balances were reported values
by Teller'6) for the POP process and by Chemico11 7> for the GTSP process.
POP GTSP
% of % of
Total F Total F
Fluorine retained in product 65 72.5
Fluorine discharged in reactor - dryer - cooler 33.5 27
Fluorine discharged in storage 1.5 0.5
100.0 100.0
The "other" materials contained in the acid and rock feed consist of
Silicates
Carbonates
Organ ics
as reported in the WPPA section of this report.
As the acidulation process takes place in the reactor, it is likely that the
carbonates and organics decompose and are discharged from the reactor and
dryer vents as CC>2 and water vapor. In addition, some of the fluorine vaporizes
as SiF and carries some of the silica out of the system.
112
-------
TABLE 33
MATERIALS EVOLVED AS GASES FROM
TRIPLESUPERPHOSPHATE MANUFACTURE
FOR 250 TON/DAY PROCESS
Water
Total
Ton/day
159.9
Ib/hr
13,370
SCFM
r
From Acid
From Organics
157.1
2.8
13,133
237
4,600
82
4,682
CO-
From Carbonates 6.6
From Organics 13.7
Total 20.3
545
1,143
1,688
78
164
242
SiF,
Fluorine
Silicon
3.4
1.25
283
104
Total
4.65
387
23.5
113
-------
Table 33 presents a calculated breakdown of the CC^, water and fluorine
balances for the reactor and dryer.
GASEOUS DISCHARGES
Four principal emission points are common in GTSP plants:
1. The reactor vents
2. Blunger vents
3. Dryer gas effluent.
4. Dust exhaust
This study is concerned with assembly of cost information only for the
dryer vents. However, some discussion of the other effluents is included for
completeness.
REACTORS
A principal source of emissions in the GTSP process is the reactor vessels.
This is ventilated at relatively high rates because of the large open areas
required for the continuous addition of ground rock. The rate of ventilation
depends largely on the mechanical design of the reactor, in that there is little
emission of gas from the reaction.
For purposes of obtaining cost data, the following gas flows were taken as
typical of current design practice for the reactor-granulator combination:
Ton/day Gas Flow,
P205 SCFM
250 15,000
500 20,000
Although the reaction of the rock and acid is strongly exothermic, and
temperatures as high as 180° F are experienced in the reactor, the temperature
of the ventilating air leaving the reactor seldom exceeds 140°F. The fluorine
emission from the reactor is relatively high, and may reach 25 Ib/ton P0.<6)
114
-------
The gaseous contaminant is reported to be SiF^ as the HF reacts with the
excess of phosphate rock and is reabsorbed.'61
For a 250 Ton/day process as illustrated in Tables 32 and 33, the reactor
vent is assumed to contain about 100 mg/SCF fluorine as SiF^ and 15 gr/SCF
particulate rock dust.
The dryer vent is a second significant source of emissions in the GTSP
process. The dryer receives granulated product from the granulator, along with
a large loading of recycled fine material. Recycled solids/net product ratios on
the order of 12/1 are common. This limits the capacity of the dryer for
production of GTSP to a lower value than for DAP, where recycle/net solids
ratios are on the order of 5/1.
The dryer is usually operated with counter-current contact between the
flue gas and wet solids. The dryer may be gas or oil fired, and the products of
combustion are tempered by dilution with ambient air to reduce the
temperature below 1000° F before contact with the product. The exhaust gases
from the dryer are again diluted somewhat with ambient air at the dryer outlet
in order to reduce the moisture content and temperature.
Gas flows for GTSP dryers are likely to approximate those for DAP dryers
handling the same moisture content. In fact, the same process equipment is
often used interchangeably for DAP and GTSP manufacture. In this study, the
gas flows were chosen so as to correspond exactly with the flowing volumes for
DAP processes in order to obtain directly comparable prices.
POLLUTION CONTROL CONSIDERATIONS
Much of the discussion of pollution control devices for WPPA processes is
also appropriate to the GTSP process. Gas absorption is of prime concern (the
limitations on fluorine emission under present Florida law are 0.15 Ib F/ton
PoOc for all process vents, and 0.05 Ib F/ton for auxiliary equipment and
storage, as given in Table 9). This requires reduction of the fluorine content to
levels approaching those in equilibrium with gypsum pond water, and also
necessitates the use of scrubbing equipment which is tolerant to deposits of
gelatinous SiO2 formed by reaction of the SiF4 with pond water.
The scrubber specifications have been set on the basis that the dryer
emission can produce one-half the total fluorine emission allowed under the
Florida law, or 0.075 Ib/ton P0. This amounts to 0.075 X 250 = 18.75
115
-------
Ib/day for the smaller of the two plants. The paniculate matter entering the
scrubber is presumed to be 3.5 wt. % fluorine and this has been taken into
account in allowing a total weight of 18 Ib/day F. This case is described as a
"low efficiency" case with respect to fluorine removal. A second higher
efficiency is defined by requiring the fluoride emission reduction to a level half
as high.
Particulate emissions from the dryer are high, and an efficient paniculate
scrubber is required to reduce the particulates to a level comparable to the
process weight limitations for particulates in general, or, to a level near the
visible threshold. A concentration of 0.01 gr/SCF was taken as an
approximation to the visible threshold.
Both of the paniculate specifications require the device chosen to be
capable of collecting paniculate matter at high efficiency, and doing so without
plugging with solids. These circumstances suggest that a Venturi-cyclonic of
conventional design should be chosen as the primary collecting device. The low
allowable emission of fluorine suggests that the Venturi-cyclonic alone may not
be suitable for the complete absorption job.
Cross-flow or counter current-flow packed scrubbers, mobile packing
scrubbers, or other gas absorption devices might be required as "tail gas"
scrubbers following the Venturi to obtain the higher absorption efficiencies
required.
116
-------
TABLE 34
PROCESS DESCRIPTION FOR GRANULAR
TRIPLESUPERPHOSPHA TE SPECIF 1C A TION
This specification describes a Venturi-packed scrubber for paniculate removal and
fluorine absorption service on a GTSP dryer. The paniculate removal function is to be
carried out in a Venturi section of conventional design using gypsum pond water as the
scrubbing medium. Removal of entrained water and absorption of fluorides is to be
accomplished in a second scrubbing stage containing a fixed plastic packing material. In
addition to these functions, the scrubber must circulate sufficient pond water to reduce the
temperature of the effluent gas to approximately 100° F in order to reduce the limiting
vapor pressure of fluoride-containing gases.
Two efficiency levels are specified with respect to fluoride removal. These are to be met
with pond water at the "design" condition specified below:
Design Min. Max.
Pond water ph 2.0 1.2 2.2
Temperature, °F 80* 55 88
S04,wt.% 0.15
P^D5,wt.% 0.1 - -
H£iF&\Nt.% 0.63 0.25 1.0
Fluorine, wt.% 0.5 0.2 0.8
The water flow shall be calculated by the supplier to provide the proper heat balance.
Materials of construction shall be limited to the following, which shall be specified for
hydrofluoric acid service:
PVC
Rubber-lined steel
FRP (Dyne/ lined)
No metal parts shall be used where exposure to process gas or pond water is likely to be
significant.
*NOTE: Pond water average temperatures as high as 90°F are common and would require a
more effective scrubber than specified here.
117
-------
Mechanical
The scrubber shall be furnished complete with interconnecting ductwork (if any)
between the Venturi section and the packed section. The scrubber shall be equipped with a
pressure regulating device, such as a barometric damper or variable throat mechanism which
shall operate to minimize pressure fluctuations at the dryer.
A fan capable of overcoming the pressure drop across the scrubber stages and all
ductwork shall be supplied as an auxiliary, and shall be located adjacent to the scrubber. A
separate hotwell, enclosed to minimize fluorine loss, a return pump, 50 foot high stack and
ductwork comprise the system.
The scrubber and all auxiliaries are to be located outside, adjacent to the dryer.
118
-------
TABLE 35
OPERATING CONDITIONS FOR GRANULAR
TRIPLESUPERPHOSPHATE WET SCRUBBER SPECIFICATION
Plant Capacity, ton/day ^2^
Plant Capacity, ton/day TSP
Process Weight, ton/hr
Gas to Scrubber
Flow, DSCFM(1)
Flow, SCFM<1)
Flow, ACFM^1)
Temp., °F
Moisture, vol.%
Paniculate, Ib/hr
Paniculate, gr/SCF
Fluorine F~, ppm
Fluorine, Ib/hr
Gas from Scrubber
Flow, DSCFM
Flow, SCFM
Flow, ACFM
250
515
40
30,000
32,000
34,000
400
825
65
30,000
33,800
40,900
180
12.64
116
0.4
195
25
48,000
54,000
65,300
180
12.64
185
0.4
195
40
48,000
51,200
54,000
Mod. Eff. High Eff. Mod. Eff. High Eff.
Temp., °F
Moisture, vol.%
Paniculate, gr/SCF
Paniculate, Ib/hr
Fluorine F~,ppm
Fluorine, Ib/hr
Paniculate efficiency, %
Fluorine efficiency, %
Estimated y'
Estimated NTU (overall)
100
6.47
0.02
5.4
5.2
0.5<2>
100
6.47
0.02
5.4
2.6
0.25^
WO
6.47
0.02
8.8
5.2
0.8<2>
100
6.47
0.02
8.8
2.6
95
98
1.95
1.95
95
99
1.95
3.55
95
98
1.95
1.95
95
99
1.95
3.55
(1) These flows have been modified slightly to correspond to flows for DAP process.
(2) Based on 1/2 of 0.15 Ib/ton permissible for entire process.
(3) Based on 1/4 of 0.15 Ib/ton permissible for entire process.
119
-------
TABLE 36
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR GTSP PROCESS PLANTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Concentration Loading
(ppm), Fluorine
Ib/hr, Particulate
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
(ppm), Fluorine
Ib/hr, Particulate
Cleaning Efficiency, % Fluorine
(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
MODERATE EFFICIENCY
Small
40,900
180
33,800
12.64
195
116
34,000
100
32,000
6.47
5.2
5.4
98
36,933
22,800
14,450*
5,050*
2,200*
—
86,197
6,200*
15,250*
16,650*
4,850*
6,250*
730*
4,250*
2,150*
13,750*
145,930
Large
65,300
180
54,000
12.64
195
185
54,000
100
51,200
6.47
5.2
8.8
98
52,827
33,733
25,300*
7,650*
2,750*
__
116,647
8,250*
22,100*
25,675*
8,100*
9,050*
1,185*
5,750*
2,150*
19,950*
203,207
High Efficiency
Small
Same
34,000
100
32,000
6.47
2.6
5.4
99
40,700
23,933
15,050*
6,150*
2,200*
__
90,457
6,200*
16,100*
16,650*
5,350*
7,250*
855*
4,250*
2,150*
14,800*
155,180
Large
Same
54,000
100
51,200
6.47
2.6
8.8
99
58,900
34,233
25,200*
8,150*
2,750*
_ _
122,657
8,250*
23,300*
25,675*
8,600*
10,550*
1,375*
5,750*
2,150*
21,325*
215,970
* Average of two bids. Third bidder did not itemize.
120
-------
FIGURE 30
CAPITAL COST OF WET SCRUBBERS
FOR GTSP PROCESS PLANTS
500000
100000
CO
oc
o
Q
te
o
o
h;
0.
<
O
10000
1000
CO
f
LU
ri
JF
tl\
KEY COS1
COLLECTOR PLUS
AUXILIARIES
EC
T(
31
3
COST ONL
•"• ~~
•*
A
'/
L
$
Y '
^ •"•
f
S*
^
7
ll
V
^H
A
rjp-
fa
W
f*
$
r
M(
fr
s>
s
s
A
Y
3D
. E
EF
F
C
HIGH EFFIC
:IENCY
IENCY
1000
10000
GAS FLOW, DSCFM
100000
300000
121
-------
TABLE 37
CONFIDENCE LIMITS FOR CAPITAL COST OF
WET SCRUBBERS FOR GTSP PROCESS PLANTS
(MOD. EFF. LEVEL)
Population — 5
Sample Size — 3
Conf. Level,
50
75
90
Capital Cost = $36,933
Capital Cost, Dollars
Lower Limit Upper Limit
$29,012
21,585
10,156
$44,855
52,282
63,710
Conf. Level, %
50
75
90
Capital Cost = $52,827
Lower Limit
$48,883
35,497
22,594
Upper Limit
$61,770
70,156
83,059
122
-------
FIGURE 31
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS
FOR GTSP PROCESS PLANTS
500000
CO
DC
O
o
fe
o
o
O.
<
o
100000
10000
1000
jt
i
'
>
J
f.
/
t
'
^
)'
f
>
r
<'
4
/
r«J
ft
/*•
9
'
Q.
a
X
_^
^
.
s
,
9
7
l\
7!
0^
'5«
IE
5°X
{,
Yo
A
90%
IV
10
D
N
El
=F.
1000 10000 100000 3000C
GAS FLOW, DSCFM
123
-------
TABLE 38
CONFIDENCE LIMITS FOR INSTALLED COST OF
WET SCRUBBERS FOR GTSP PROCESS PLANTS
(MOD. EFF. LEVEL)
Population — 5
Sample Size — 3
Conf. Level,
50
75
90
95
Installed Cost = $145,930
Installed Cost, Dollars
Lower Limit Upper Limit
$131,937
118,818
98,630
79,962
$159,923
173,042
193,230
211,898
Conf. Level,
50
75
90
95
Installed Cost = $203,207
Lower Limit
$191,793
181,092
164,626
149,400
Upper Limit
$214,620
225.321
241,787
257.013
124
-------
FIGURE 32
CONFIDENCE LIMITS FOR CAPITAL COST
OF INSTALLED WET SCRUBBERS
FOR GTSP PROCESS PLANTS
500000
V)
DC
O
o
te
o
o
Q.
<
o
100000
10000
1000
/
90% »*
75% .^
MEAN^
7fi% ^
90% /
»<
.X
'/'
')
>j2
^2
^
r
M
O
EFF.
1000 10000 100000 300000
GAS FLOW, DSCFM
125
-------
TABLE 39
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR GTSP PROCESS 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
Recirculated Pond Water
Water (Make-up)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$8/hr
$6/hr
JO.Oll/kw-hi
$.05/M gal
$.25/M gal
MODERATE EFFICIENCY
Small
$ 1,950
3,667
4,017
22,053
14,776
3,600*
38,030
47,664
14,593
62,257
Large
$ 1,950
4,333
5,800
36,726
23,660
5,400*
62,197
74,280
20,321
94,601
High Efficiency
Small
$ 1,950
3,833
4,950
25,657
16,136
3,600*
42,994
53,727
15,518
69,245
Large
$ 1,950
4,667
7,433
40,572
25,420
5,400*
67,789
81,842
21,597
103,439
NJ
O)
*From one bidder only.
-------
FIGURE 33
ANNUAL COST OF WET SCRUBBERS
FOR GTSP PROCESS PLANTS
500000
V)
cc
o
Q
to*
O
O
100000
10000
1000
_ ^ .
(.
/y
•I
f
_ __ .
^;
K
3
•i
9.
'#
>
f
>
/
M
X
^v
r
O[
(C
0
D.
)P
C
PE
El
El
A
EF
=F
1
3/
PI
?/
•|l
HIGH EFFICI
1000 10000
'OTAL CO
^ING CO
TAL CHA
mNG CO!
CIENCY
FMPY
CIML> T
ST
STPLL
RGES)
•*^F-
5T
IS
100000 300000
GAS FLOW, DSCFM
127
-------
DIAMMONIUM PHOSPHATE (DAP)
Diammonium phosphate (DAP) is produced in plants similar to those used
for the manufacture of granular triplesuperphosphate, and in fact the same
plant is often used to produce these products alternatively.
DAP is made by first reacting anhydrous ammonia with phosphoric acid in
a pre-reactor to form hot liquid DAP. This liquid is then pumped to an
ammoniator-granulator drum, where it is further mixed with NHg and recycled
solid material, and solidified. It is then dried, screened to size, cooled and sent
to DAP product storage.
Acid produced by wet process phosphoric acid plants is used almost
exclusively for the manufacture of diammonium phosphate fertilizers. Acid at
54% strength from the vacuum evaporation section of the plant is used for the
initial preneutralization reactions, and acid at 30% strength is ordinarily
blended to maintain the proper water level.'16)
DAP plants involve many of the same pollution considerations as WPP A,
SPA, and GTSP processes treated previously in this report. However, in
addition to the problems associated with absorbing gaseous fluoride
compounds, the DAP process volatilizes a substantial amount of unreacted
ammonia in the reactor and granulator-drier vessels. It is necessary to absorb
the ammonia vapors in strongly acidic solutions for return to the reactor in
order to minimize the loss of raw material and to avoid substantial air pollution
by the ammonia discharge.
Process Description
Figure 34 is a process flow diagram1161 for a diammonium phosphate
granulation plant. The following process description will make frequent
reference to this diagram.
Anhydrous ammonia is obtained in bulk as a liquid under pressure. Liquid
ammonia is ordinarily pumped from the storage vessel through a steam-jacketed
coil in which the ammonia is vaporized. The ammonia vapor is bubbled through
the liquid in a preneutralization reactor. Phosphoric acid at 54 wt.% is pumped
through the reactor from the WPPA process. In addition, phosphoric acid at 26
to 30 wt.% which has been circulated through the reactor vent scrubber is also
added to the preneutralization reactor.'7)
Substantial heat of reaction is evolved in the reactor, and some of the
128
-------
TO AATMOS.
PRENEUTRAL-IZATION
REACTOR
TEAM
TO
ATMOS.
REACTOR
VENT
SCRUBBER
POND
WETTER
DRIER VENT
SCRUBBER
POND
KTER
CYCLjONE
SEPARATOR
CONDENSATE
AMMONIA
STORAGE
POND
WATER
<3RANUL_ATOR
DRUM
PRIMARY
SCREEN
SECONDARY
SCREENS
PHOSPHORIC
ACID
STORAGE
PHOSPHORIC ACID
FROM
ACID MANUFACTURING
PHOSPHORIC ACID
FROM
ACID MANUFACTURING
PRODUCT
STORAGE
M SPHERICAL.
GRANUUES)
FIGURE 34
FLOW DIAGRAM FOR
DIAMMONIUM PHOSPHATE (DAP)
GRANULATION PLANT
129
-------
ammonia is discharged from the reactor as a vapor. Because there are no solid
feed materials added to the reactor, it is possible to operate a nearly closed
system from which only ammonia and steam, and little non-condensable gas
such as air, must be discharged.11 5)
The preneutralization reactor is operated with a somewhat lower mol ratio
of ammonia to P2C>5 than is required for the production of DAP, in order to
prevent solidification of the entire mixture in this reactor. The resulting
product is a slurry which can be pumped from the preneutralization reactor
into the ammoniator-granulator. In the granulator, the slurry is exposed to
additional ammonia vapor and solidification of the diammonium phosphate
solid takes place.161 In addition to the slurry which is fed to the granulator
from the preneutralization reactor, a recycle of finely divided solid particles is
added to the granulator from a recycle elevator as shown in Figure 25. The
diammonium phosphate formed in the granulator and solidified from the slurry
increases the particle size of the solids being recirculated through the
granulator. The solid effluent from the granulator drum is dropped to a gas
fired (or oil fired) rotary drier where excess moisture is driven off by direct
contact with the flue gases. Flue gas from the drier is vented through a dry
cyclone collector which collects the dust generated in the granulator-drier and
returns it to a recycle belt. The granular solids discharged from the drier are
elevated to a screening arrangement shown in the right hand side of Figure 25.
A primary screen removes undersized material from the flow stream and
drops it onto the fines return conveyor. Oversized material is passed to a ball
mill where it is ground to relatively small size and returned to the belt. The
material passing the primary screen falls onto a secondary screen which rejects
any fines which may have been carried over and passes the material of proper
particle size through a rotary cooler into a product storage drum.'1 6>
All of the other solids, both oversized and undersized, are recycled by
means of a single conveyor belt and elevator back to the granulator drum where
they are trapped until the particle size has grown sufficiently large for them to
be classified with finished product.
Particular attention must be given to the gas scrubber systems in the DAP
process because they form an integral and necessary part of the process.
Ordinarily, the vents from the preneutralization reactor and the granulator have
a high ammonia content. In order to recover the ammonia contained in these
gases, it is customary to circulate 20 to 30% acid (expressed as wt.% P2^)
through the scrubbers instead of pond water. The acid is circulated from a 30%
acid storage tank as shown in Figure 34 through the primary scurbbing devices
and the acid returned to the storage tank. Makeup acid from the reactor section of
131
-------
the WPPA plant is added to the acid storage tank and 30% acid for addition to
the preneutralization reactor is withdrawn from the tank.
CHEMISTRY OF THE PROCESS
In each of the processes described previously, it was necessary to
oversimplify the reactions involving fluorapatite rock in order to illustrate the
basic chemistry. In the case of the DAP process, the reactions are represented
with good accuracy by the simple equation shown as follows:
H3PO4 + 2NH3 + (NH)2HP04 - 81,500BTU (26)
(Liquid) (Gas) (Liquid) AHRat60°F)
For purposes of this discussion, it may be assumed that the ammonia feed
stock is substantially free of impurities. The phosphoric acid, on the other
hand, contains some impurities which participate in side reactions.
The acid composition given in Table 7 may be used for the development
of hypothetical process emissions, although it should be borne in mind that the
use of 30% acid or feed grade WPPA acid in addition to the 54% acid results in
bringing more fluorine into the reaction than indicated by the Table 7
composition.
The side reactions involve the formation of ammonium sulfate,
ammonium fluoride, and ammonium fluorosilicate. Also, some of the fluorine
is liberated as silicon tetrafluoride and discharged from the reactor with the
ammonia gas. It should be noted that the product weight, rather than the P2^^
content of the product, is the usual basis for rating the DAP plant. It is
apparent from Table 40 that a substantial amount of the water present in the
phosphoric acid is removed in the drying process.
NATURE OF THE GASEOUS DISCHARGE
The DAP process has two major sources of gaseous discharge and two dust
sources which may be significant from a pollution standpoint:
Gaseous
1. Reactor and granulator ventilating gas
2. Drier flue gas
132
-------
Dust
1. Cooler air discharge*
2. Transfer points and screen ventilation
In this section, all three of these sources will be considered, and pollution
control equipment applicable to each source will be specified, and cost data
will be obtained for each.
Reactor
The reactor or preneutralizer is a vessel into which about 70% of the
ammonia and all of the phosphoric acid are introduced. In some plants, 93
wt.% H2S04 is introduced to control final analysis of the product.
The reaction generates a substantial amount of heat which raises the
temperature of the reactants and results in the discharge of large quantities of
water vapor, unreacted ammonia and SiF^ In order to assure that there will be
no leakage of ammonia and phosphoric acid from the mixing vessel, the vessel
is well ventilated with outside air. The ventilating air flow rate is a critical
factor in the design of subsequent gas treating equipment, and this is set on the
basis of mechanical factors in the reactor design, rather than by any
fundamental requirement of the process. In theory, the reactor could be
designed to avoid any ventilating air flow and the system run without discharge
to the atmosphere.
In practice, ventilating air flow rates of around 2,500 SCFM through the
reactor are common.'1 5> The ventilating air serves to remove some of the heat
of reaction, and also increases the flow of ammonia out of the reactor vessel.
The ammonia "lost" from the reactor at this point is captured in the
preneutralizer scrubber through which 20 to 30% concentration acid is
circulated. Concentrations around 26% are preferred to keep the product in the
MAP range.
The rate of gas flow through the preneutralizer is established by the
inward air leakage required to prevent loss of ammonia and fluorine-containing
gases from the preneutralizer. Inward air leakage rates on the order of 2,000
SCFM are reasonable for reactors of commercial design. To this air stream is
added ammonia, water vapor, and minor components of the DAP slurry in
*ln some cases NHg losses have been observed where inadequate operation of
the dryer shifts losses to the cooler.
133
-------
NH-
TABLE 40
APPROXIMATE MATERIAL BALANCE OF
1,000 TON/DAY DAP PROCESS
Acid Feed
(@ 40% P205)
Ton/Day Lb/hr
Ammonia Feed
Ton/Day Lb/Hr
DAP Product
@ 1 wt.%
Moisture
Ton/Day Lb/Hr
240 20,000
500 41,690
F
S03
AI203
Fe203
Other
Water
Total
14.3
15.8
18.6
7.4
3.7
690.2
1,250.0
1,190
1,315
1,545
620
310
57,500
104,170
12.2
15.8
18.6
7.4
3.7
9.8<1
240 20,000 997.5
1,015
1,315
1,545
620
310
1 810
84.115
(1) Water removed is (690.2 Ton/Day total water — 190 Ton/Day combined
water in phosphoric acid — 9.8 Ton/Day in product = 490.2 Ton/Day).
134
-------
portion to the vapor pressure at the reaction temperature. Water vapor will
move toward equilibrium between the gas stream and a liquid phase which is
less than 60% water. The gas stream will never contain more than about 60%
saturated with respect to liquid water in the reactor, but will be close to
saturation at the exhaust temperature of 170 to 180° F.
At a discharge temperature of 180° F, the estimated composition of the
effluent gases for a reactor with 2,000 SCFM in-leakage of air is given in Table
41. The fluorine content of this gas stream, either as particulate or vaporized
components has in the past been of little concern as it leaves the reactor. The
ammonia content is too high for discharge into the atmosphere for reasons of
economy and pollution control, and it is necessary to contact the
ammonia-bearing gas stream with relatively concentrated phosphoric acid in
order to minimize ammonia loss. The contracting process serves to recover the
ammonia effectively, but in doing so results in volatilization of fluorine
compounds from the absorbing liquor.'6) Today, the fluorine stripping effect is
sufficient to warrant the addition of a tail gas scrubber after the primary
absorber. In the hypothetical process selected for study here, it will be assumed
that 30% acid is used for the scrubbing liquid and that the fluorine
concentration in the tail gas is significant.
GRANULATOR
A second significant source of emissions from the process is the
granulator.(8) Here, a solids recycle material consisting of under-sized solid
product is fed to the granulator from a bucket elevator or other loading device.
In addition, the slurry from the preneutralizer and the remaining ammonia are
added and final solidification of the DAP takes place. As in the case of the
preneutralization reactor, the granulator might be operated without any net
flow of gas, except that it is mechanically very difficult to maintain a sealed
rotary unit into which solids are fed. For this reason, granulators are designed
with a substantial in-leakage of air around the inlet and outlet connections. The
ventilating air flow purges a substantial amount of ammonia from the
granulator along with some water vapor and DAP dust.
There is very little evolution of fluorine-containing gases from the
granulator because of the high concentration of ammonia in the vapor phase.
Again, the recovery of ammonia from the ventilating gas is the primary concern
in the treatment of the off gases from the granulator. Substantial
concentrations of particulate matter in the DAP pose a potential fluoride
emission problem and particulate collection with return of the DAP
135
-------
TABLE 41
COMBINED VENTS FROM REACTOR
AND GRANULATOR
Temp, ° F
Moisture, vol %
Reactor
190
50
Moisture, Ib/lbs Gas 0.625
Gas Composition, SCFM
Water 2,000
Air
Ammonia
2,000
20
4,020
Granulator
150
39
0.39
11,250
18,000
200
29,450
Total
to
Scrubber
170
40
0.415
Total
from
Scrubber
135
40.8
0.430
13,250 13,750
20,000 20,000
220(2> 12°
33,470
33,762
(1) Basedon 3 Ib/ton NH3feed.
(2) Based on 11.2 ton/hr in.
136
-------
particulates to the preneutralization reactor along with the phosphoric acid
scrubbing liquid is essential to the process. An estimate of the composition of
gas from the granulator is given in Table 41. The rotary drier removes the free
water from the DAP by direct contact with flue gases. The flue gas generation
rate may be calculated approximately by heat balance of the drier. The heat
input must be sufficient to vaporize the difference between the water content
of the dry product and the water input with both phosphoric acid streams.
Little heat is added to the solid product because it enters the dryer
combination at nearly the exit temperature.
A rough heat balance of the dryer for a 500 Ton/day plant is shown in
Table 42, and the calculated gas flow on the heat balance is used in specifying
the abatement equipment at the end of this section.
At the dryer outlet, there must be some provision for in-leakage of
ventilating air to prevent loss of flue gas and product dust. The flue gas-steam
combination produced in the dryer is ordinarily vented through a mechanical
collector and serves to collect particulate solids for return to the process. The
exhaust gas from the cyclone is scrubbed either in combination with the gas
ventilated through the preneutralization reactor, or in a separate scrubber. The
two services may be combined if a common phosphoric acid circulating stream
is used for both of them. In the flow scheme shown in Figure 34, the streams
are treated separately, and in the hypothetical plant for which specifications
and prices are given, this is the case.
COOLER
The final emission sources which must be treated in a DAP plant are the
air used for cooling the solid product and ventilating the solids transfer points.
The product cooler reduces the temperature from 190° F or thereabouts to
about 110°F by direct contact of cooling air with the solids in a rotary drum.
The air flow requirement can again be calculated on an approximate basis by a
heat balance of the process. There is little in the way of volatile material given
off in the cooler as the temperature is reduced and the vapor pressure of each
of the species decreases. However, there is a substantial dusting problem due to
the mechanical handling of the granular solids. The principal pollution control
problem associated with the cooler is the recovery of this particulate matter.
Because the ammonia has been stripped out of the solid at this point, it is not
necessary to use acidic water for scrubbing, and pond water may be used in this
scrubber for convenience.
137
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TABLE 42
ROUGH HEAT BALANCE FOR DAP DRYER
FOR 1,000 TON/DAY PROCESS
Into Dryer
Wet DAP
DAP
Water
Recycle Solids
Air to Burner*1)
Fuel to Burner'21
Tempering Air(3)
Dilution Air(4)
Total Gases
Flow
SCFM
—
—
—
9,000
900
21,900
—
Flow
Ib/hr
124,905
(83,305)
(41,600)
420,725
41,000
2,280
100,000
37,000
Temp.,
°F
200
200
200
200
70
70
70
—
Heat
Content
BTU/lb
( 32.5)
(130 )
33.5
0
0
0
0
Heat
Content
BTU/hr
8.12
( 2.71)
( 5.41)
14.10
0
0
0
0
30,900 143,280
22.22
Out of Dryer
DAP Product
DAP
Water
Recycle Solids
Flue Gas
N2
02
C02
H20
_
—
—
—
46,000
(24,480)
( 4,620)
( 900)
(16,100)
84,145
(83,305)
( 840)
420,725
184,040
008,500)
(23,400)
( 6,240)
(45,900)
200
200
200
200
180
180
180
180
180
33.5
( 32.5)
(130)
—
293
27.5
(1,090)
2.82
( 2.71)
( 0.11)
14.10
53.80
( 3.80)
( 50.0)
Burner Duty = 70.72 - 22.22 = 48.50 X 106 BTU/hr.
(1) Based on 10/1 air to fuel ratio for gas firing
(2) Based on 900 BTU/SCF lower heating value
(3) Tempering air to produce 1,500° F temperature to dryer
(4) Dilution air to reduce outlet temperature to 180° F
70.70
138
-------
TRANSFER POINTS AND SCREEN VENTILATION
The DAP granulation process, as illustrated in Figure 34 involves the
handling and screening of a great deal of granular solid product and recycle
solids. At each transfer point (i.e., elevator, belt conveyor, screen or mill
discharge) there is some generation and dispersion of product dust. This must
be retained within the process by exhausting air from exclosures around the
transfer points. This dust contains a small amount of fluorine as an impurity,
but consists mainly of DAP product.
Recovery of the dust and return to the process offers some potential for
improved product yield, and phosphoric acid may be used as the scrubbing
medium. The dust may, however, be collected in scrubbers circulating pond
water, which discharges into the gypsum pond.
APPLICABLE ABATEMENT EQUIPMENT
This discussion deals with the wet scrubbing equipment conventionally
applied for removal of ammonia, fluorides and particulate dusts from effluent
gas streams generated in DAP plants. These scrubbers are designed for a variety
of functions which include:
Ammonia Recovery
Particulate Collection (and sometimes recovery)
Fluorine Removal
These functions require a complex arrangement of the scrubbing equipment.
The three major process sources in DAP plants are treated exclusively by
wet scrubbers. Several circumstances contribute to the selection of wet
scrubbers over other types of pollution control devices for these services. The
necessity for removal of gaseous ammonia and fluoride compounds from the
gas stream is a significant factor in DAP process plants, although the emphasis
here is more on control of particulate emissions than is the case for any of the
phosphate processes described in earlier sections. A second contributing factor
is the relatively high humidity of the gas streams, all of which originate in wet
reactors, driers, or other pieces of process equipment from which water vapor
emission is significant. The high concentration of water in the gas streams poses
problems in the use of fabric collectors, and, to a lesser extent, in the use of
mechanical or electrostatic collectors.
Finally, the ready availability of pond water as a scrubbing medium, and
139
-------
the gypsum pond as a settling basin for collected solids is a significant
advantage for wet scrubbers.
The combination of requirements for particulate collection and gas
absorption for NHg recovery and fluorine emission control permits the
application of a wide variety of scrubber types for DAP service. The devices
most used are:
1. Two-stage wet cyclonic
2. Venturi-cyclone* scrubbers
3. Cross-flow packed scrubbers
Figure 35 shows a schematic drawing of each of these three types. These
scrubbers are ordinarily used as follows:
Primary Secondary
Scrubber Scrubber
Reactor granulator ' Venturi-
Cyclone Cyclonic
or or
Dryer Two-Stage Packed Cross-
Cyclonic flow
Cooler + Venturi
Transfer points Cyclone
or
Two-Stage
Cyclonic
The two-stage wet cyclonic scrubbers are relatively simple in design and
construction, and have relatively low pressure drop characteristics. They are
well suited for the collection of particulate greater than about 3y in size, and
for gas absorption. They are less efficient as absorption devices than are the
scrubbers utilizing wetted packings.
*"Venturi-cyclone", rather than the more common "Venturi-cyclonic" is
used here to distinguish a scrubber in which the "cyclone" is used for
entrainment separation only. "Cyclonic" is reserved for scrubbers using the
cyclonic scrubbing principal.
140
-------
The Venturi cyclone, operating in the range of 15 to 30 inches water
column pressure drop, is perhaps the best particulate collection scrubber of the
three and also serves adequately for ammonia absorption, especially when a
packed section is installed after the primary Venturi cyclone collector, or when
water sprays are used in the entrainment separator to enhance the gas
absorption characteristics of the unit.
Typically, a 30 in. w.c. pressure drop Venturi can be used to collect not
only the dusts, but also the condensation products such as ammonium fluoride
in the sub-micron size range, formed by gas phase reactors.
The cross-flow packed scrubber is the best of the three devices from a gas
absorption standpoint, but is less effective for the collection of particulate
matter, and for this reason is used as a "tail gas" scrubber following a Venturi
or two-stage cyclonic. The packed scrubbers are seldom used as primary
scrubbers because of the tendency to plug with gelatinous silicon or DAP
deposits.
In order to generate a reasonably complete picture of the costs of these
scrubbers in the various services, a generalized pattern has been followed in
writing specifications. The equipment is presumed to be installed on a 1,000
T/D DAP process (500 T/D P2^ content) and individual scrubbers specified as
follows:
Reactor-Granulator - 20,000 DSCFM
Venturi-Cyclone
Two-Stage Cyclonic
Dryer - 30,000 DSCFM
Venturi-Cyclone
Two-Stage Cyclonic
Tail Gas Service
The particulate collection scrubber should always be the "upstream"
member of a two scrubber combination. That is, a two-stage wet cyclonic or
Venturi-cyclone would always precede a cross-flow packed scrubber. It is
difficult to envision circumstances that would lead to the installation of a
cross-flow packed scrubber ahead of a two-stage wet cyclone. Figure 36
illustrates those combinations which are reasonable from the standpoint of
performing the solid collection in the scrubber most suited for handling solids
and the gas absorption in subsequent scrubbing steps.
As in each of the previous cases, the equilibrium between the
fluorine-containing gas, SiF4 and HF, and h^SiFg in the pond water is of
141
-------
GAS
OUTLET
GAS
OUTLET
WATER
INLET
GAS
INLET
GAS
INLET
WATER
INLET
WATER
OUTLET
TWO-STAGE
CYCLONIC
SCRUBBER
WATER
OUTLET
VENTURl
CYCLONIC.
SCRUBBER
WATER
INLET
WATER
OUTLET
CROSS-FLOW RACKED
SCRUBBER
FIGURE 35
142
SCHEMATIC DRAWING OF SCRUBBERS
USED IN DAP TAIL GAS TREATING
-------
considerable importance. The equilibrium vapor pressures of these gases given
in the discussion of the WPPA process indicate that the gas stream must be
relatively cool in order for low enough values of fluorine in the ventilating gas
to meet the present Florida law to be realized. Ordinarily, gases entering a
scrubber are at a higher temperature and lower moisture content than those
exiting, due to the saturation and cooling of the gas which takes place in the
scrubber. In the DAP plant, the moisture content of gases vented to the tail gas
scrubber is too high for evaporative cooling to take place, and some
condensation of moisture from the gas must take place in the scrubber. This
requires that a substantially higher flow rate of scrubber liquor per unit of gas
must be passed through the scrubber than would be the case for cooling of the
gas by evaporation of moisture from the scrubbing liquor.
One other problem is peculiar to DAP scrubbing among the other
phosphate rock processing pollution abatement processes. Because recovery of
ammonia is of critical importance in the process economics, the scrubbers may
be operated at temperatures as high as 185°F for contacting the
ammonia-containing vent gases with 30% phosphoric acid. Many of the
materials of construction most desirable from a corrosion standpoint (PVC,
FRP and rubber) have substantially decreased physical properties in this
temperature range, and pose some specific problems in fabrication of large
scrubbers of these materials. In particular, PVC is unlikely to be acceptable in
this service because of the high temperatures.
143
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ACID
GAS
FROM
REACTOR
1
REACTOR
SCRUBBER
t
RECYCLE TO
REACTOR
POND
WATER
FROM
GRANULATOR
SCRUBBER
t
TAIL GAS
SCRUBBER
GAS TO
"ATMOSPHERE
RETURN
TO POND
CROSS-FLOW
VENTURI
TWO-STAGE CYCLONIC
OR
VENTURI
OR
CROSS-FLOW PACKED
t
C ROSS - FLOW
C ROSS- FL.OW
CROSS-FLOW PACKED
CROSS-FLOW
TWO-STAGE CYCLONIC
TWO-STAGE CYCLONIC /
OR >
CROSS-FLOW PACKED \
_t
VENTURI
VENTURI
TWO- STAGE CYCLON 1C
OR
VENTURI
OR
CROSS-FLOW PACKED
FIGURE 36
ACCEPTABLE SCRUBBER COMBINATIONS FOR DAP PROCESS PLANTS
144
-------
TABLE 43
PROCESS DESCRIPTION FOR WET SCRUBBERS
FOR DAP PROCESS
This specification describes three types of scrubbers and three process gas streams.
There is some degree of interchangeability of the scrubbers specified.
The DRYER is to be treated for paniculate and ammonia removal by either a
Venturi-cyclone or a two-stage wet cyclonic scrubber. Thirty percent phosphoric acid is used
as the scrubbing medium in these scrubbers. Either is followed by a crossflow packed
scrubber using water as the scrubbing medium for fluorine removal. These scrubbers should
be identical to those specified for the Reactor-Granulator vent, except for size. The cooler
and dryer are to be considered interchangeable applications.
. Two efficiency levels are specified for each scrubber. A separate set of process
conditions is specified for each size.
The pond water to be used for scrubbing has characteristics as follows:
Design Min. Max.
Pond Water, pH 2.0 1.2 2.2
Temperature,°F 80* 55 88
S04,Wt.% 0.15
P£)5,Wt.% 0.7
H£iF6,Wt.% 0.63 0.25 1.0
Fluorine, Wt.% 0.5 0.2 0.8
*NOTE: Pond water temperature may be considerably higher than the values given here.
Design temperatures of 90°F+ may be specified, and correspondingly high gaseous fluorine
limits may be expected.
The scrubber is required to produce the specified performance when operating with
water at the "design" conditions. The vendor shall specify the water flow rate to be used,
and that this flow rate is adequate for his scrubber design.
Materials of construction shall be limited to the following, which shall be selected for
hydrofluoric acid service:
Rubber-Lined Steel
FRP (Dynel Lined)
No metal parts shall be used where exposure to process gas or pond water may be significant.
145
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MECHANICAL
A. Two-Stage Wet Cyclonic
The scrubber shall be equipped with a cone bottom, bottom tangential gas inlet, two
stages of sprays which can be removed for cleaning of spray nozzles while the unit is
operating, and a top gas outlet.
A fan capable of overcoming the pressure drop across the scrubber stages and ductwork
shall be supplied as an auxiliary and shall be located adjacent to the scrubbers. The fan shall
operate on the discharge side of the cyclone.
A separate hotwell with a barometric leg seal must be supplied, and should be enclosed
to minimize fluorine losses.
The scrubber system shall be furnished complete with all interconnecting ductwork
from the scrubber to the fan and from the fan to the stack. A return pump, 50 ft. stack and
barometric damper to minimize pressure fluctuations at the dryer shall be provided.
The scrubber and auxiliaries are to be located outside, adjacent to the dryer.
B. Venturi-Cyclone
The Venturi cyclone scrubber shall have a pressure drop of 15-30 inch water column
and shall be designed to have no spray nozzles in the Venturi section. All interconnecting
ductwork, fan, return pump, etc. similar to that outlined under the Two-Stage Wet Cyclone
shall be provided. A variable throat may be substituted for the barometric damper to
maintain the dryer peressure constant.
C. Cross-Flow Packed
The cross-flow tail gas scrubber, if required, should be placed in series after either the
two stage cyclone or the Venturi cyclone. The fan shall be placed between the primary
scrubbers and the cross-flow tail gas scrubber.
The cross-flow scrubber should be designed to treat the gas stream in a single packed
bed of sufficient depth to obtain the required removal efficiency. Top irrigation as well as a
front face spray of the wetted bed should be used. High top liquid irrigation rates should be
used in the front packed section to prevent solids deposition.
A dry packed bed shall serve as an entrainment separator. Top water sprays shall be
furnished in the entrainment separation section for intermittent wash-down of the packing.
The scrubber sump bottom should be sloped to prevent solids build-up and should contain
baffles to prevent gas by-pass of the packed bed.
When the cross-flow packed scrubber is required all additional interconnecting
ductwork, return pump, etc., shall be provided in addition to that outlined in the Two-Stage
Wet Cyclone and Venturi Cyclone sections to comprise a complete system.
146
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TABLE 44
OPERATING CONDITIONS FOR PRIMARY SCRUBBERS
FOR DAP PROCESS DRYER VENTS*
Plant Capacity, Ton/Day DAP
Plant Capacity, Ton/Day P2O5
Process Weight, Ton/Hr
Gas to Scrubber
Flow, DSCFM
Flow, SCFM
Flow, ACFM
Temp., °F
Moisture, vol.%
Paniculate, gr/SCF
Particulate, Lb/Hr
Ammonia, Lb/Ton P^0§
Ammonia, Lb/Hr
Ammonia, ppm
Gas from Scrubber
Flow, DSCFM
Flow, SCFM
Flow, ACFM
Temp., °F
Moisture, vol.%
Particulate, gr/SCF
Particulate, Lb/Hr
Ammonia, Lb/Ton Pfl$
Ammonia, Lb/Hr
Ammonia, ppm
Particulate Efficiency, wt. 5
Ammonia Efficiency, %
1,000
500
42
30,000
46,100
55,700
180
35
0.5
200
8.0
167
1,350
30,000
46,800
53,500
164
36
0.01
4.0
0.08
1.67
13.4
98
99
1,600
800
66.7
48,000
74,000
89,000
180
35
0.5
320
8.0
267
1,350
48,000
75,000
85,500
164
36
0.01
6.4
0.08
2.67
13.4
98
99
*These are considered interchangeable with cooler vent scrubbers.
147
-------
TABLE 45
OPERATING CONDITIONS FOR SECONDARY SCRUBBERS
FOR DAP PROCESS DRYER VENTS*
Plant Capacity, Ton/Day DAP
Plant Capacity, Ton/Day ^05
Process Weight, Ton/Hr
Gas to Scrubber
Flow, DSCFM
Flow, SCFM
Flow, ACFM
Temp., °F
Moisture, vol.%
Fluorine, ppm as F-
Fluorine, Lb/Hr
Gas from Scrubber
Flow, DSCFM
Flow, SCFM
Flow, ACFM
Temp., °F
Moisture, vol.%
1,000
500
42
30,000
46,800
53,500
164
36
15
2.1
30,000
31,900
33,700
100
7
1,600
800
66.7
48,000
75,000
85,500
164
36.
15
3.35
48,000
51,000
54,000
100
7
Fluorine, ppm as F-
Fluorine, Lb/Hr(1)
Fluorine removal, %
Estimated y', ppm
Estimated NTU
Medium Efficiency Case
4.1
0.415
80
1.95
1.80
4.1
0.67
80
1.95
1.80
Fluoride, ppm as F-
Fluoride, Lb/Hr(2i
Fluorine removal, %
Estimated y'
Estimated NTU
High Efficiency Case
3.25
0.31
85
1.95
2.8
3.25
0
85
1.95
2.8
*These are considered interchangeable with cooler vent scrubbers.
(1) Based on 1/3 of 0.06 Lb F/Ton ^2^5 allowable under present Florida law.
(2) Based on 1/4 of 0.06 Lb F/Ton.
148
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SPECIFICATIONS AND COSTS
Tables 41 - 43 contain specifications for scrubbers representative of those
used in controlling DAP process emissions. Table 41 is a general process
description for the dryer, and covers both primary and secondary scrubbers.
The primary scrubber may be either a two-stage cyclonic scrubber or a
Venturi-cyclone, and the secondary scrubber is limited to a corss-flow packed
scrubber. A single efficiency level is requested for each of the two primary
scrubbers, while two levels of efficiency are requested for the secondary or tail
gas scrubber.
In order to cover the size range encountered for scrubbers used to treat
reactor and cooler gas streams as well as those of the dryer, the manufacturers
of the scrubbing equipment were asked to provide cost information for a
20,000 DSCFM scrubber (which represents the reactor-drier gas flow on a
1,000 ton/day DAP process), but which is identical in all respects except gas
flow capacity to the dryer effluent scrubbers. This should provide costs
described for a range of scrubber sizes from which estimates of the cost of
treating the reactor-granulator, the dryer, or the cooler vents can be made for
most plant sizes.
149
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TABLE 46
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR TWO STAGE CYCLONIC SCRUBBERS
FOR DAP PROCESS PLANTS
FLOW. DSCFM
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/SCF
Ib/hr, Particulate
Ib/Tir, Ammonia
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/SCF
Ib/hr, Particulate
Cleaning Efficiency, % part .
Ammonia
(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
?n nnn
37,000
180
30,800
35
0.5
133
111
35,600
164
31,200
36
0.01
2.7
98
99
48,900*
14,050*
91,700*
154,650*
30.000
55,700
180
46,100
35
0.5
200
167
53,500
164
46,800
36
0.01
4
98
99
66,400
21,767
17,350**
3,850**
1,450**
—
102,417
6,750**
19,300**
23,500**
4,400**
9,250**
5,750**
2,150**
11,500**
190,584
48 r 000
89,000
180
73,800
35
0.5
320
267
85,500
164
74,800
36
0.01
6.4
98
QQ
92,867
33,900
30,400**
5,800**
2,150**
—
145,733
10,500**
25,000**
33,750**
8,000**
15,350**
9,250**
2,150**
17,000**
272,500
* Only two bids obtained for this size.
**Auxiliaries and items of installed cost averaged from two bids.
bidder did not itemize.
150 '
Third
-------
FIGURES?
CAPITAL COST OF TWO STAGE CYCLONIC SCRUBBERS
FOR DAP PROCESS PLANTS
500000
CO
DC
O
Q
te
o
o
a.
<
O
100000
10000
1000
10(
;
£
r
/
/
f
J
^X"
r J
/
r
X^
r
X
r
^
X*
>
x
^
^
TURNKEY COST _
COLLECTOR PLUS -
AUXILIARIES
COLLECTOR COST
ONLY
)0 10000 100000 3000C
GAS FLOW, DSCFM
151
-------
TABLE 47
CONFIDENCE LIMITS FOR CAPITAL COST OF
TWO STAGE CYCLONIC SCRUBBERS FOR DAP PROCESS PLANTS
Population Size — 5
Sample Size — 2
Conf. Level. %
50
75
Capital Cost = $48,900
Capital Cost, Dollars
Lower Limit Upper Limit
$33,341
14,444
$64,459
83,356
Population Size - 5 Sample Size - 3
Capital Cost = $66,400
Conf. Level,
50
75
90
Lower Limit
$59,121
52,295
41,793
Upper Limit
$73,679
80,504
91,006
Population Size — 5 Sample Size — 3
Capital Cost = $92,867
Conf. Level, %
50
75
90
Lower Limit
$86,054
79,667
69,838
Upper Limit
$99,679
106,067
115,895
152
-------
500000
FIGURE 38
CONFIDENCE LIMITS FOR CAPITAL COST
OF TWO STAGE CYCLONIC SCRUBBERS
FOR DAP PROCESS PLANTS
100000
CO
oc
o
Q
to*
8
0.
<
U
10000
1000
T
75%
MEAN
75%
1000
10000
GAS FLOW, DSCFM
100000
300000
^Confidence limit determined from a sample of two bidders. Third bidder
did not bid for this size.
153
-------
TABLE 48
CONFIDENCE LIMITS FOR INSTALLED COST OF
TWO STAGE CYCLONIC SCRUBBERS FOR DAP PROCESS PLANTS
Population Size — 5
Sample Size - 2
Conf. Level, %
50
75
90
Installed Cost = $154,650
Installed Cost, Dollars
Lower Limit Upper Limit
$128,061
95,766
32,553
$181,239
213,534
276,747
Population Size — 5 Sample Size — 3
Installed Cost = $190,583
Conf. Level,
50
75
90
95
Lower Limit
$176,575
163,441
143,231
124,542
Upper Limit
$204,592
217,726
237,936
256,624
Population Size — 5 Sample Size — 3
Installed Cost = $272,500
Conf. Level,
50
75
90
95
Lower Limit
$257,346
243,137
221,274
201,057
Upper Limit
$287,654
301,863
323,726
343,943
154
-------
500000
FIGURE 39
CONFIDENCE LIMITS FOR CAPITAL COST
OF INSTALLED TWO STAGE CYCLONIC SCRUBBERS
FOR DAP PROCESS PLANTS
CO
cc
O
O
fe
O
O
Q.
<
O
100000
10000
1000
75%* (
. t. "ICO/ ff . j
/O70 ^
> A
y%
j
4
w
r
a
"?
P
£
!••
75
M
%
E/
^
75%
1000 10000 100000 3000C
GAS FLOW, DSCFM
'Confidence limit determined from a sample of two bidders. Third bidder
did not bid for this size.
155
-------
TABLE 49
en
at
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR TWO STAGE CYCLONIC SCRUBBERS
FOR DAP PROCESS 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
Pond Water (Make-up)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$8/hr
$6/hr
$.011/kw-hr
$.25/M gal
$.05/M gal
MODERATE EFFICIENCY
20,000 SCFM DG
$ 3,670*
6,825*
4,229*
12,030*
2,235*
14,265
28,989
15,465
44,454
30,000 SCFM DG
$ 2,447
6,033
3,801
15,814
5,259
21,073
33,354
19,058
52,412
48,000 SCFM DG
$ 2,447
7,450
5,355
24,920
8,433
33,353
48,605
27,205
75,810
Large
* Only two bids obtained for this size.
-------
FIGURE 40
ANNUAL COST OF TWO STAGE CYCLONIC SCRUBBERS
FOR DAP PROCESS PLANTS
500000
100000
CO
cc
o
Q
te
o
u
10000
1000
TOTAL COST
(OPERATING COST
PLUS CAPITAL
OPERATING
COST
^
10000
GAS FLOW, DSCFM
100000
300000
157
-------
TABLE 50
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR VENTURI CYCLONIC SCRUBBERS
FOR DAP PROCESS PLANTS
FLOW, DSCFM
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
gr/SCF
Jb/hr, Particulate
rb/'hr. Ammonia
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
gr/SCF
Ib/hr , Particulate
Cleaning Efficiency, % Part .
Ammonia
(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
20,000
37,000
180
30,800
35
0.5
Wi
35,600
164
31,200
36
0.01
2.7
98
09
33,250*
18,025*
76,680*
127,955*
30.000
55,700
180
46,100
35
0.5
200
167
53,500
164
46,800
36
0.01
4
98
99
44,433
28,500
24,000**
3,800**
2,450**
_ _
__
88,833
6,600**
15,000**
__
13,300**
5,300**
5,800**
2,100**
4,500**
2,150**.
14,750**
161,766
48rono
89,000
180
73,800
35
0.5
320
267
85,500
164
74,800
36
0.01
6.4
98
9^9
61,467
45,300
43,100**
6,700**
3,150**
• 0>
_~
128,577
8,500**
21,700**
—
29,750**
8,750**
8,600**
2,815**
6,250**
2,150**
21,600**
235,344
* Only two bids obtained for this size.
**Auxiliaries and items of installed cost averaged from two bidders,
bidder did not itemize.
158
Third
-------
500000
FIGURE 41
CAPITAL COST OF VENTURI-CYCLONE SCRUBBERS
FOR DAP PROCESS PLANTS
100000
C/5
cc
_i
_i
O
0
te
0
U
_J
<
1-
0.
U
10000
1000
>
r
L
/
I
fi
s
s
A
/
/
)
s
/
y
/
f
&
Q
/*
fi
X
x
^
rf
r
TURNKEY COST
COLLECTOR PLUS
AUXILIARIES
C(
31
.L
.ECTOR COST -
ONLY
1000 10000 100000 3000C
GAS FLOW, DSCFM
159
-------
TABLE 51
CONFIDENCE LIMITS FOR CAPITAL COST OF
VENTURI-CYCLONIC SCRUBBERS FOR DAP PROCESS PLANTS
Population Size-5 Sample Size — 2
Capital Cost = $33,250
Conf. Level, %
50
75
Capital Cost, Dollars
Lower Limit Upper Limit
$20,284
4,536
$46,215
61,963
Population Size — 5 Sample Size — 3
Capital Cost = $44,433
Conf. Level, % Lower Limit
50
75
90
95
$38,349
32,644
23,865
15,748
Upper Limit
$50,518
56,223
65,001
73,118
Population Size — 5 Sample Size — 3
Capital Cost = $61,467
Conf. Level,
50
75
90
95
Lower Limit
$54,802
48,553
38,938
30,047
Upper Limit
$68,131
74,380
83,995
92,886
160
-------
FIGURE 42
500000
CONFIDENCE LIMITS FOR CAPITAL COST
OF VENTURI-CYCLONE SCRUBBERS
FOR DAP PROCESS PLANTS
100000
CO
DC
O
Q
65
o
o
_i
<
CL
O
10000
1000
75%*
t
1000
10000
GAS FLOW, DSCFM
100000
300000
"Confidence limit determined from a sample of two bidders. Third bidder
did not bid for this size.
161
-------
TABLE 52
CONFIDENCE LIMITS FOR INSTALLED COST OF
VENTURI-CYCLONIC SCRUBBERS FOR DAP PROCESS PLANTS
Population Size — 5 Sample Size — 2
Installed Cost = $127,955
Conf. Level,
50
75
90
Installed Cost, Dollars
Lower Limit Upper Limit
$105,472
78,165
24,715
$150,438
177,745
231,195
Population Size — 5 Sample Size — 3
Installed Cost = $161,767
Conf. Level, %
50
75
90
95
Lower Limit
$151,791
142,438
128,046
114,738
Upper Limit
$171,742
181,095
195,487
208,795
Population Size — 5 Sample Size — 3
Installed Cost = $235,343
Conf. Level,
50
75
90
95
Lower Limit
$229,416
223,859
215,307
207,400
Upper Limit
$241,271
246,828
255,379
263,287
162
-------
FIGURE 43
CONFIDENCE LIMITS FOR CAPITAL COST
OF INSTALLED VENTURI-CYCLONE SCRUBBERS
FOR DAP PROCESS PLANTS
500000
CO
DC
O
Q
te
O
O
CL
<
O
100000
10000
1000
75%* (
75%* ~5
? .i
\#
;•
<
)
4
f
Sol
f
'•I
^5'
VIE
5°/
y0
LA
'o
N
1000 10000 100000 3000C
GAS FLOW, DSCFM
*Confidence limit determined from a sample of two bidders. Third bidder
did not bid for this size.
163
-------
TABLE 53
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR VENTURI CYCLONIC SCRUBBERS
FOR DAP PROCESS PLANTS
a
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
Pond Water CMake-up)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$8/hr
$6/hr
$0.011/kw-to
$.25/M gal
$.05/M gal
MODERATE EFFICIENCY
20.000 SCFM DG
$ 2,925*
4,650*
3,932*
17,850*
1,425***
18,808*
30,315*
12,795*
43,110*
30.000 SCFM DG
$ 1,950
4,100
3,511
27,645
5,562**
31,354
40,915
16,177
57,092
48,000 SCFM DG
$ 1,950
5,166
4,828
43,901
8,950**
49,868
61,812
23,534
85,346
Large
* Only two bids obtained for this size.
**Average of two bidders. Third bidder did not itemize.
'**From one bidder only.
-------
FIGURE 44
ANNUAL COST OF VENTURI-CYCLONE SCRUBBERS
FOR DAP PROCESS PLANTS
500000
CO
oc
O
Q
O
O
100000
10000
1000
(C
TOTAL COST
IPERATING COST
CAPITAL CHARC
>PI 1 IQ
rl_Uo
3ES)
JJ
r
t
OPERATING COST '
f.
s
' 6
/
7
_s
/
7
s
r
j>
fr
at
/*
/
>
s
1000 10000 100000 300000
GAS FLOW, DSCFM
165
-------
166
-------
TABLE 54
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR PACKED CROSS-FLOW SCRUBBERS
FOR DAP PROCESS PLANTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
. Contaminant Effluent Loading
(ppm) Fluorine
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
MEDIUM EFFICIENCY
Small
53,500
164
46,800
36
15
2.1
33,700
100
31,900
7
Contaminant Cleaned Gas Loading
(ppm) Fluorine
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
4.1
0.415
80
27,425
13,684
6,425
7,089
170
. .
38,462
2,000
3,500*
5,000*
5,500*
5,430*
10,550*
375
375
450
710
1,475
1,500
79,471
Large
85,500
164
75,000
36
15
3.35
54,000
100
51,000
7
4.1
0.67
80
43,200
17,470
9,400
7,755
315
_ _
50,358
2,000
5,000*
6,200*
6,000*
7,970*
15,200*
500
450
450
710
1,475
2,000
111,028
High Efficiency
Small
53,500
164
46,800
36
15
2.1
33,700
100
31,900
7
3.25
0.31
85
32,375
13,684
6,425
7,089
170
_ _
38,962
2,000
3,500*
5,000*
5,500*
5,430*
10,550*
375
375
450
710
1,475
1,500
85,021
Large
85,500
164
75,000
36
15
3.35
54,000
100
51,000
7
3.25
0.50
85
47,050
17,470
9,400
7,755
J
315
— •»
50,857
2,000
5,000*
6,200*
6,000*
7,970*
15,200*
500
450
450
710
1,475
2,000
115,377
*Items of installed cost. Itemized for materials and labor by one bidder only.
167
-------
TABLE 54 continued
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR PACKED CROSS-FLOW SCRUBBERS
FOR DAP PROCESS PLANTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Contaminant . Effluent Loading
(ppm) Fluorine
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
MEDIUM EFFICIENCY | High Efficiency
Small 20,000 DSCFM Small
Contaminant Cleaned Gas Loading
(ppm) Fluorine
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
36,500
164
30,000
36
15
1.4
22,600
100
21,400
7
4.1
0.27
80
21,025
9,502
4,350
5,000
152
- _
32,540
2,000
3,000*
4,600*
3,000*
4,040*
6,200*
325
325
450
710
1,475
1,250
63,067
20,000 DSCFM
36,500
164
30,000
36
15
1.4
22,600
100
21,400
7
3.25
0.216
85
23,525
9,502
4,350
5,000
1 ^2
J. J £<
__
33,042
2,000
3,000*
4,600*
3,000*
4,040*
6,250*
325
325
•J 4* *J
450
710
1,475
1,250
66,069
*Items of installed cost. Itemized for materials and labor by one bidder only.
168
-------
FIGURE 45
CAPITAL COST FOR PACKED CROSS-FLOW SCRUBBERS
FOR DAP PROCESS PLANTS
500000
100000
V)
cc.
o
Q
te
o
o
_l
<
t
Q.
u
10000
1000
^r
MOD. EFF.
HIGH EFF.
1000
10000
GAS FLOW, DSCFM
100000
300000
169
-------
TABLE 55
CONFIDENCE LIMITS FOR CAPITAL COST
OF PACKED CROSS-FLOW SCRUBBERS
FOR DAP PROCESS PLANTS
Population Size — 5 Sample Size — 2
Capital Cost = $21,025
Capital Cost, Dollars
Conf. Level % Lower Limit Upper Limit
50 20,001 22,049
75 18,757 23,293
90 16,322 25,729
95 13,691 28,359
Population Size — 5 Sample Size — 2
Capital Cost = $27,425
Capital Cost, Dollars
Conf. Level % Lower Limit Upper Limit
50 22,603 32,247
75 16,747 38,103
90 5,283 49,566
Population Size —5 Sample Size — 2
Capital Cost = $43,200
Capital Cost, Dollars
Conf. Level % Lower Limit Upper Limit
50 38,004 48,396
75 31,692 54,708
90 19,338 67,062
95 5,995 80,405
170
-------
FIGURE 46
CONFIDENCE LIMITS FOR CAPITAL COST
OF PACKED CROSS-FLOW SCRUBBERS
FOR DAP PROCESS PLANTS
500000
o
o
te
o
o
o
100000
10000
1000
,',
X
*
, >
c
J*
&
*' (
)'
>
fx"
*
i
'\
I
s
J
^
^
^
1
75%
IE AN
75%
1000 10000 100000 300000
GAS FLOW, DSCFM
*The disparity between bids for this size scrubber is greater than the disparity
for the other two sizes.
171
-------
TABLE 56
CONFIDENCE LIMITS FOR INSTALLED COST
OF PACKED CROSS-FLOW SCRUBBERS
FOR DAP PROCESS PLANTS
Population Size — 5 Sample Size — 2
Installed Cost = $63,070
Conf. Level
50
75
90
95
Lower Limit
61,596
59,806
56,302
52,517
Upper Limit
64,544
66,334
69,839
73,623
Population Size — 5 Sample Size — 2
Installed Cost = $79,572
Conf. Level %
50
75
90
95
Lower Limit
71,151
60,923
40,904
19,281
Upper Limit
87,992
98,220
118,239
139,861
Population Size — 5 Sample Size — 2
Installed Cost = $111,028
Conf. Level
50
75
90
95
Lower Limit
100,552
87,829
62,925
36,027
Upper Limit
121,503
134,226
159,130
186,028
172
-------
FIGURE 47
CONFIDENCE LIMITS FOR INSTALLED COST
OF PACKED CROSS-FLOW SCRUBBERS
FOR DAP PROCESS PLANTS
500000
100000
CO
cc
o
o
k
8
_l
<
H
O.
o
10000
1000
^7
75%
i i
MEAN
I I I"
75%
10000 100000
GAS FLOW, DSCFM
*The disparity between bids for this size scrubber is greater than the disparity
for the other two sizes.
300000
173
-------
174
-------
TABLE 57
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR PACKED CROSS-FLOW SCRUBBERS
FOR DAP PROCESS 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
Pond Water (Make-up)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$8/hr
$6/hr
$.011/kw-hr
$.25/M gal
$.05/M gal
MEDIUM EFFICIENCY
30,OOODSCFM
8rOOO
1,738
1,875
200
4,787
34
4,821
8,624
7,957
16,581
48,OOODSCFM
8.000
3,613
2,888
250
7,150
55
7,205
13,955
11,103
25,058
High Efficiency
30,OOODSCFM
8.000
1,738
1,875
200
4,990
35
5,025
8,828
8,502
17,330
48.000DSCFM
8.000
3,613
2,888
250
7,287
57
7,344
14,095
11,538
25,633
CJI
-------
TABLE 57 continued
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR PACKED CROSS-FLOW SCRUBBERS
FOR DAP PROCESS 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
Pond Water (Make-up)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$8/hr
$6/hr
$.011/kw-hr
$.025/M gal
$.05/M gal
MEDIUM EFFICIENCY
,20,OOODSCFM
8.000
1,738
1,838
150
3,051
23
3,074
6,800
6,307
13,107
High Efficiency
• -
20,OOODSCFM
8rOOO
1.738
1.838
150
3,183
24
3,207
6,933
6,609
13,540
•sj
O)
-------
FIGURE 48
ANNUAL COST OF PACKED CROSS-FLOW SCRUBBERS
FOR DAP PROCESS PLANTS
500000
100000
CO
cc.
o
Q
O
u
10000
1000
MOD. EFF.
. HIGH EFF.
10000
GAS FLOW, DSCFM
100000
300000
177
-------
GTSP STORAGE
The reactions initiated in the GTSP reactor are completed over a period of
several weeks after acidulation.16' During this time the granular product must
be stored under roof to protect it from the weather. The storage building must
be well ventilated to provide a safe environment for employees engaged in
loading, unloading and moving the bulk material, and the ventilating air stream
must be treated to remove dust and fluorine (or SiF^) before discharge to the
atmosphere.
Typically the storage is in gable-roofed shed buildings which are ventilated
by natural draft if no air pollution control equipment is used. Such buildings
are designed for high ventilation rates, typically from 100,000 to 1,000,000
SCFM, with thermal density differences as the driving force. The addition of
scrubbing equipment for air pollution control provides a strong incentive for
the reduction of the ventilation rate to the minimum consistent with good
working conditions. This section discusses the problem in terms of treating a
reduced flow of about 200,000 ACFM.
Process Description
The screened granular triplesuperphosphate is ordinarily discharged from
the last screening operation onto a rubber conveyor belt which carries it into
the storage building. Here it is discharged into bins or piles. The product may
be moved into position in a larger bulk storage pile by use of portable elevators,
overhead cross transfer belts, front-end loaders, or by other relocatable solids
handling equipment.
Any scheme for moving the solids inside the storage building must take
into account that all the GTSP should be held long enough to stabilize the
composition so no fluorine evolution will take place after the product is
shipped. Any additional storage time is wasteful of space. The logistics of
moving 500 or 1,000 ton/day solid material through a 30-day retention pile
requires a well planned solids handling program.
Usually the buildings are designed for holding a pyramid-shaped pile of
GTSP considerably larger than that required for a 30-day retention. This allows
for some inefficiency in use of the space to minimize handling.
The evolution of fluorine as SiF4 occurs slowly, and at a rate which
decreases with storage time. If the entire storage building is treated as a unit,
the evolution rate has been quoted as approximately 0.2 to 0.6 Ib F day/ton of
178
-------
GTSP.(6) Thus, a storage building designed for a throughput of 500 ton/day
(P205 content) might be expected to evolve 100 to 300 Ib/day of SiF4.
The size of the building determines the ventilation rate required to
produce good working conditions inside. For a 500 ton/day plant, the average
storage level should be around 15,000 ton, and the building should have an
o
interior volume of perhaps three times the average value. At 30 Ib/ft , the
volume should be on the order of
15,000 X 3 X 2000 = ^
' '
0.564 X 40
A building of the dimensions shown in Figure 28 would contain approximately
this volume.
Ventilation Requirements
Ventilation for worker safety in storage buildings is ordinarily expressed
in terms of the number of "air changes per hour", based on total building
volume. Typical values for warehouses range from 1 to 15 air changes per
hour,11 7) or one complete turnover of the air inside the building in 60 minutes
for the lower rate and 4 minutes for the higher one. For the 4,000,000 cubic
foot storage building this amounts to a minimum rate of 67,000 ACFM and a
maximu m of 1,000,000 ACFM.
The emissions of SiF4 require a higher than minimum rate of
ventilation,(6) and three air changes per hour is a reasonable value. This
corresponds to 200,000 ACFM for a hypothetical 500 ton/day GTSP plant.
Careful selection of the ventilation rate is important because the cost of gas
cleaning equipment varies in direct relation to the gas flow, and oversizing the
ventilation system will increase the cost of purchasing and operating the gas
cleaning equipment.
Design of the ventilation system in such a way as to produce acceptable
air quality in all parts of the storage building is complicated by several factors:
(1) The dust release is primarily local and associated with handling of the
stored product.
(2) The fluorine release is slow and decreases with time.
179
-------
FIGURE 49
SKETCH OF GTSP STORAGE BUILDING
WITH 4,000,000 FT3 INTERIOR
180
-------
The building ventilation system should be designed to provide for clean air
induction in a controlled pattern as well as adequate exhaust of contaminated
air.
Pollution Control Considerations
The dust generated by solids handling and the fluorine evolved by curing
of the TSP product pose potential pollution problems.' 8) These can be treated
separately by use of a fabric collector for particulate removal followed by a
cyclonic scrubber or packed scrubber for gas absorption, or by a scrubber
which serves both functions. The latter case is the only one considered here,
but combination systems are practical and have been used.
The particulate matter generated by mechanical handling of the granular
TSP is relatively fine with the coarser particles separated out of the ventilating
air stream by gravity. Particle size is predominantly above one micron,
however, any moderate scrubber pressure drop levels (less than 10" w.c.) are
adequate for collection. Typical dust loadings on the order of 0.1 gr/ACF or
0.1 X 200,000 X 60 , 1?0|b/hr
7,000
are encountered, but the rate of dust evolution is likely to be very variable and
very low levels of dust generation are likely when no materials handling
operations are being carried out. Peak emission rates, on the other hand, may
reach levels of 1 gr/ACF for short periods, and require efficiencies on the order
of 99% to avoid visible discharge and violation of particulate emission limits.
The gas absorption requirements are relatively straightforward, and may
be met by use of a variety of absorption devices. The emission from a GTSP
storage building for a 500 ton/day plant will be in the range of 0.5 Ib/ton of
P20g,(6) which is approximately 250 Ib/day of fluorine. The present Florida
law limits the total emission to 0.05 Ib/ton P205- or approximately 25 Ib/day.
This requires 90% scrubbing efficiency and an outlet concentration of about
25 x 379 x 1
19 6° ^ * 1.000.000- 1.73 ppm.
2OQ000
equivalent to 0.04 mg/SCF as F. This efficiency level demands low temperature
pond water in large quantity for scrubbing. Reference to Figure 8 and Table 13
indicates that equilibrium levels of fluorine are low enough to
181
-------
meet the required outlet concentration at temperatures on the order of 80° F at
almost any pond water fluorine content. At 100° F, a low concentration of
h^SiFg (below 1.0 wt.%) would be required, and at 120°F the specification
could not be met.
Field experience has shown that the header ducts from storage building
should be sprayed to minimize solids build-up. Further, the spraying converts
the SiF4 to h^SiFg and SiC^ which then becomes conditioned for scrubbing,
minimizing space otherwise lost in the scrubber shell.
With 80° F pond water of normal fluorine content, the absorption
requirement is not severe. For this reason, a variety of scrubbers can perform
satisfactorily in this service, and minimization of energy input is more
important than maximization of gas-liquid contact. The following scrubber
types are acceptable on this basis:
(1) Cyclonic
(2) Spray towers
(3) Cross flow packed
The use of a conventional cyclonic scrubbing stage is relatively common,
and the single specification for this service is based on this combination.
Figure is a photograph of a GTSP storage building, showing two cyclonic
scrubbers.
182
-------
CO
CO
X W
3-
P3
O F
JJ :=
DO D
DO =
m g
m
en
o
-------
184
-------
TABLE 58
PROCESS DESCRIPTION FOR GTSP
STORAGE BUILDING SCRUBBER
This specification describes a scrubber to remove paniculate matter and gaseous
fluorides from the ventilating air discharged from a granular triplesuperphosphate fertilizer
storage building. The scrubber shall consist of a cyclonic scrubber for absorption of gaseous
, particulate collection and de-entrainment of scrubbing liquor.
The scrubbing system is to include a fan to overcome the pressure drop across the
scrubber and associated ductwork, a collection plenum system equipped with internal water
sprays, which is to connect roof ventilators along the length of the storage building,
balancing dampers, scrubber inlet ductwork, a 180 ft. discharge stack, and a liquor return
sump. The building dimensions are approximately 180 ft. wide x 380 ft. long x 105 ft. at the
ridge line.
Pond water is to be used as the scrubbing medium in both stages. The scrubbing system
will discharge into a sump to be provided as a part of the scrubbing system. Pumps for
supplying the pond water will be by others, but the scrubber contractor is to supply the
pond water return pumps as a pan of his system.
Pond water characteristics are as follows:
Design Min. Max.
Pond Water, PH 2.0 1.2 2.2
Temp.,°F 80 55 88
S04,wt.% 0.15
P205,wt.% 0.1
H^iFg, wt.% 0.63 0.25 1.0
Fluorine, wt.% 0.5 0.2 0.8
The scrubber is required to produce the specified performance when operating with the
"design" pond water conditions. The scrubber manufacturer shall specify the required water
circulation rate through both the duct section and the Cyclonic scrubber.
Materials of construction shall be limited to the following:
PVC
Rubber
FRP (Dynel lined)
Minimal metal parts shall be exposed to process gas or pond water.
185
-------
TABLE 59
OPERATING CONDITIONS FOR SCRUBBER SPECIFICATION
FOR GTSP STORAGE BUILDING VENT
Plant Capacity, ton/day P^K 500
Building Dimensions, ft.
Width 180
Length 380
Height at Ridge 105
Building Volume, ft3 4,000,000
Ventilation Rate, ACFM 200,000
Gas to Scrubber
Flow, ACFM 200,000
Temperature, °F 80
Moisture Content, Vol.% 1.6
Flow, DSCFM 196,800
Gaseous Fluoride (SiFj) Loading, ppm 17.3
Gaseous Fluoride (SiF^) Loading, Ib/hr 10.4
Paniculate Solid, gr/A CF 0.10
Paniculate Solids, Ib/hr 170
Gas from Scrubber
Flow, ACFM 202,000
Flow, DSCFM 196,800
Temp., °F 68
Moisture Content, Vol.% 2.4
Gaseous Fluoride Loading, ppm 1.70
Gaseous Fluoride Loading, Ib/hr 1.0
Fluoride Efficiency, Wt.% 90.4
Paniculate Solids L oading, gr/A CF 0.01
Paniculate Solids Loading, Ib/hr 1.7
Paniculate Efficiency, Wt.% 90
Estimated Fluorine in Equilibrium with
Pond Water, ppm 0.7
Estimated NTU required 1.8
186
-------
TABLE 60
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR CYCLONIC SCRUBBERS FOR GTSP STORAGE VENTS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Concentration Loading
Cppm), Fluoride
Ib/hr, Particulate
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
(ppm), Fluoride
Ib/hr, Particulate
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
(48,000)'
Large
200,000
80
196,000
1.6
17.3
170
202,000
68
196,800
2.4
1.70
17
90
101,000
109,250
57,700*
9,975*
333,480
13,900*
21,150*
*(312,000)**
20,100*
22,000*
3,570*
10,500*
5,250*
28,750*
543,730
* Average of two bidders. Third bidder did not itemize.
**Lower price from one bidder for one stack to handle 200,000 SCFM. Higher
price from another bidder for four stacks each handling 50,000 SCFM.
187
-------
TABLE 61
CONFIDENCE LIMITS FOR CAPITAL COST OF
CYCLONIC SCRUBBERS FOR GTSP STORAGE
Population Size — 5 Sample Size — 3
Capital Cost = $101,000
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $93,149 $108,851
75 85,788 116,212
90 74,462 127,538
95 63,988 138,012
188
-------
TABLE 62
CONFIDENCE LIMITS FOR INSTALLED COST OF
CYCLONIC SCRUBBERS FOR GTSP STORAGE
Population Size — 5 Sample Size — 3
Installed Cost = $543,730
Installed Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $491,266 $596,194
75 442,076 645,384
90 366,385 721,075
95 296,394 791,066
189
-------
TABLE 63
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR CYCLONIC SCRUBBERS FOR GTSP STORAGE VENTS
CO
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
Pond Water (Make-up)
Water (Cooling)
Chemicals, Specify
Total Utilities
Total Direct Cost
Annual ized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$8/hr
$6/hr
$.011/kw-hr
$.25/M gal
LA Process Wt.
Small
Large
High Efficiency
Small
Large
$ 1,950
7,933
10,513
60,975
15,000
75,975
96,371
54,373
150,744
-------
REFERENCES
(1) Stern, Arthur C., Air Pollution, Volume III, Academic Press, New York &
London, 1968, p. 221.
(2) Waggman, W. H., Phosphoric Acid, Phosphates and Phosphatic Fertilizers,
2nd ed., Reinhold Publishing Corporation, New York, 1952.
(3) Shreve, Norris, The Chemical Process Industries, p. 340.
(4) Grant, H. 0., "Pollution Control in a Phosphoric Acid Plant", Chemical
Engineering Progress, (Vol. 60, No. 1), January, 1964, p. 53-55.
(5) Annon., "Cleanup Pays Off for Fertilizer Plant", Environmental Science
and Technology, (Vol. 6, No. 5), May, 1972, p. 401-402.
(6) Slack, A. V., Phosphoric Acid, Vol. 1, Fertilizer Science and Technology
Selves, Marcel Dekker, Inc., N.Y. 1968.
(7) Specht, R. C., and R. R. Calaceto, "Gaseous Fluoride Emissions from
Stationary Sources", Chemical Engineering Progress, (Vol. 63, No. 5),
May 1967, p. 78-84.
(8) Teller, A. J., "Control of Gaseous Fluoride Emissions", Chemical
Engineering Progress, (Vol. 63, No. 3), March 1967, p. 75-79.
(9) English, M., "Fluorine Recovery from Phosphate Fertilizer Manufacture",
Chemical and Process Engineering, December, 1967, p. 43-47.
(10) State of Florida Air Pollution Regulations 17-204(6)-1.
(11) Gilbert, Nathan, L. A. Hobbs and W. D. Sandberg, "Adsorption of
Hydrogen Fluoride in a Limestone Packed Tower", Chemical Engineering
Progress, (Vol. 49, No. 3), March, 1953, p. 120-128.
(12) Yatlov, V. S. and E. N. Pineskaya, Zhur. Priklao Khim., 14, No. 1, 11-13,
1941.
(13) Lunde, K. E., "Performance of Equipment for Control of Fluoride
Emission," Industrial and Engineering Chemistry, (Vol. 50, No. 3), March,
1958, p. 293-298.
191
-------
(14) Ceilcote Corporation, private communication.
(15) Wellman-Powergas Co., private communication.
(16) Farmland Corporation, Lakeland, Florida, private communication.
(17) Patty, Frank A., Industrial Hygiene and Toxicology, Volume I,
Interscience Publishers, Inc., New York, N.Y., 2nd Ed., 1958, p. 289-293.
192
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FEED and GRAIN
-------
2. FEED AND GRAIN INDUSTRY
Slightly more than 86% of the cereal grains raised in the United States
today and consumed domestically goes for the feeding of livestock and
poultry.11' The feed industry combines cereal grains and mixtures of grain with
other natural products and synthetics to produce what are called "formula" or
"mixed" feeds. Millions of farmers still feed some straight grain, sometimes
fortified with an oil meal, to their livestock. However, the trend is toward
wider use of commercially formulated manufactured rations.
Corn gluten* meal is recognized as the first dry protein cereal by-product
to have been fed widely to livestock. Corn gluten meal is a by-product of the
wet milling of corn. In this process, whole grain corn is steeped in a dilute
sulfurous acid solution and subsequently separated into starch, fiber, gluten,
and corn germ**.
Some of the gluten meal is mixed with coarse and fine fiber (hulls and
bran***) and other low-protein by-products to make a lower-grade feed than
the meal itself. Drying and handling of this final feed are frequently done in a
flash drying system.
Other by-product feedstuffs are frequently recovered in the manufacture
of the main food product. Whenever the by-product is high in protein value, it
is dried, ground, and sold as a high-protein feed, or mixed with low protein
by-products (chaff, hulls, bran, etc.) to increase their feed value. Other
important high-protein feeds are oil-seed meals (soybean, cottonseed, flaxseed
and safflower seed), dried distillers' solubles****, fish meal, and various animal
residues (blood, tankage*****, etc.).Table 64.'1'presents the composition of
several feedstuffs used in the manufacture of feed.
Feed manufacturing is a comparatively simple operation. Cereal grains, oil
seed meals, packinghouse by-products, and occasionally minute quantities of
vitamins, molasses, and other ingredients, are combined to produce rations. If
every trace element and vitamin additive were individually counted and added
to the total number of basic ingredients such as the grains, a formula could
easily contain 50 or more components.
*Gluten is a term which describes the protein derived from grains, principally
corn or wheat.
**Germ is the seed part of the grain.
***Bran is the skin or husk of the grain.
****Dry distillers' solubles are by-products of the brewing and distilling
industry.
*****Tankage refers to the residual solids created in the wet rendering of
animal carcasses.
193
-------
TABLE 64
COMPOSITION OF TYPICAL FEEDSTUFFS11'
USED IN MANUFACTURE OF FEED
Description
Corn (dent) grain
Wheat grain
Barley grain
Oats grain
Soybean meal
Sesame meal
Linseed meal
Cottonseed meal
Safflower meal
Cooked feathers
Raw feathers
Tankage
Rice bran
Malt sprouts
Wheat bran
Dried beet pulp
Alfalfa hay (early)
Alfalfa hay (late)
Orchardgrass (early)
Orchardgrass (late)
Timothy
Coastal Bermudagrass
Soybean hulls
Soybean straw
Barley straw
Wheat straw
Corn cobs & husk
Rice hulls
Crude
Fiber
2.2
2.3
7.0
12
6.4
6.9
9.0
12.4
35
1.5
1.3
3.7
13
12.5
11
21
23.5
39
24
35
32
32
28
43
38
42
32
43
Cell
Walls
10.1
12.4
20
31
12.0
16.8
25
27
58
19.5
9.0
25
24.1
45
47
54
40
55
52
70
65
76
63
67
72
82
83
81
Acid
Deterg.
Fiber
Dry
Matter
Basis
2.7
3.1
6.3
16.4
9.0
9.8
16.4
18.0
41
12.2
65.0
3.6
15.9
16
12.1
33
25
40
27
40
43
38
45
53
45
53
45
66
Lignin
0.6
0.7
1.0
2.8
0.3
2.0
6.7
6.6
13.7
—
—
4.3
1.1
4.0
2.5
5.3
9.0
2.7
4.7
7.0
5.6
2.0
12.0
5.2
7.6
5.0
14
Crude
Protein
9.8
11.6
12.7
13.6
44
52
38
44
24
96
96
67
15
26
17.4
10.0
20
14
24
11
10
6.4
15
11
2.6
3.2
2.3
3.0
Dry Digestibility
Matter Non-
Ruminant ruminant
86
85
80
75
84
77
81
19
50
70
<10
68
61
77
73
76
62 50
53
72 38
57 20
50
46
68
44
54
36
50
< 10
194
-------
Table 65(1) provides illustrations of rations and supplements for one class of
swine, the brood sow. The formula under "ration" is for a complete diet, ready
for the sow. If the "supplement" formula is used, a ton of complete feed would
be prepared by adding 1,100 Ib of ground corn and 400 Ib of ground oats to
500 Ib of the supplement. The supplement type of feed is usually used in the
feeding of beef cattle. It provides sufficient protein to balance that which is in
the grain and roughage which the cattle eat. Table 66(1)gives four formulas for
beef cattle supplements, three providing 32% protein and one with 65%
protein. The major difference between these supplements is that one is based
on all natural protein, while the other three include a non-protein source in the
form of urea.
The feed formulas presented inTables65and66are representative of those
being manufactured in the United States today. The composition of feed for
other animals and poultry vary from these only in relation to the differences in
their requirements for various nutrients.11'
In both the manufacture of feed and the manufacture of flour, a process
called milling is employed. However, feed milling and flour milling are two
entirely distinct processes. The function of feed milling is to reduce the cereal
grains and oilseed meals to the desired size and consistency of particle, and
then to mix this ground material with other ingredients to produce
scientifically formulated rations. The reduction in size of the cereal grains and
other constituents is usually performed in a grinding device, such as a hammer
mill.
Flour and products made from flour have been used by man for centuries.
The bland taste of food made from cereal grains has much to do with this fact.
The first articles made from flour were unleavened breads. Later, the Egyptians
introduced yeast leavened bread.
The primary reason for the continued use of cereal grains as a food is not
taste, but the ease of growing cereals and their stability in storage. The power
of drying as a means of preserving cereal grains was discovered by early man.
He used sun drying techniques to avoid spoilage and antique milling techniques
to improve the taste of the food products.
The original millstones, which have been found in ruins that date back to
4000 B.C., were essentially a crude mortar and pestle arrangement designed to
crush wheat into smaller particles. Then it was discovered that moving one
millstone on another in a semicircular fashion was a more efficient means of
reducing grain to flour. Power to run such mills often came from animals. The
water wheel was invented around 100 B.C., and wind and water then became
195
-------
TABLE 65
RATIONS AND SUPPLEMENTS FOR BROOD SOWS11'
Ration Supplement
Ground corn 1,110 Ib —
Ground oats 400 —
Middlings 50 200
17% dehy. alfalfa meal 50 200
50% meat & bone meal 75 300
60% fish meal 25 100
44% soybean meal 250 1,030
Dicalcium phosphate (18%) 10 40
Calcium carbonate 20 80
Salt 8 30
Trace mineral mix 1 4
Hog vitamin premix 5 20
Total batch 2,004 Ib 2,004 Ib
CALCULATED NUTRIENT CONTENT
Protein, % 16.2 36.2
Fat, % 3.6 2.6
Fiber, % 5.6 7.3
Calcium, % 1.02 4.0
Vitamin A, lU/lb 2,750 10,000
Phosphorus, % 0.62 1.65
Vitamin D , USPU/lb 375 1,500
Riboflavin, Mg/lb 2.4 7.7
Niacin, Mg/lb 23.3 66.5
Pantothenic acid, Mg/lb 8.9 26.0
Choline, Mg/lb 530 1,145
Vitamin B12,Mcg/lb 12.5 51.0
GUARANTEED ANALYSIS
Crude protein, min % 16.0 36.0
Crude fat, min % 3.5 2.5
Crude fiber, max % 6.0 8.0
Calcium (Ca), max% Not Needed 4.5
Calcium (Ca), min % Not Needed 3.5
Phosphorus (P), min % Not Needed 1.6
Iodine (I), min % Not Needed 0.0006
Salt (NaCI), max % Not Needed 2.0
Salt (NaCI), min % Not Needed 1.0
196
-------
TABLE 66
BEEF CATTLE FEED SUPPLEMENTS11:
Ingredients
44% Soybean meal
Wheat middlings
Corn gluten feed
17% deny, alfalfa
Urea (45%)
Dicalcium phosphate
Calcium carbonate
Salt
Trace mineral mix
"Dry" molasses product
Vitamin A
Vitamin D2
Molasses (wet)
Total batch, Ib
Protein, %
Equivalent protein, %
Fat, %
Fiber, %
Calcium, %
Phosphorus, %
Vitamin A, lU/lb
Vitamin D0, lU/lb
Crude protein, min %
This includes no more than -°A
equivalent crude protein
from non-protein nitrogen
Crude fat, min %
Crude fiber, max %
Calcium (Ca), max %
Calcium (Ca), min %
Phosphorus (P), min %
Iodine (I), min %
Salt (NaCI), max %
Salt (NaCI), min %
32% Cattle
Supplement
All Natural
Protein
1,320
100
100
150
—
30
100
50
5
—
2
1
150
2,008
32% Cattle
Supplement
with
4% Urea
600
750
—
200
80
30
110
50
5
—
2
1
180
2,008
32% Cattle
Supplement
with
6% Urea
60
450
800
200
120
40
100
50
5
—
2
1
180
2,008
65% Cattle
Supplement
with
20% Urea
50
150
—
600
400
150
60
80
10
400
4
2
100
2,006
CALCULATED NUTRIENT CONTENT
32.2
—
1.05
7.0
2.58
0.80
13,600
2,000
32.2
11.24
2.1
7.5
2.72
0.81
13,600
2,000
32.4
16.86
2.0
8.2
2.73
0.85
13,600
2,000
64.4
56.20
1.04
11.3
3.36
1.51
27,200
4,000
GUARANTEED ANALYSIS
32.0
32.0
32.0
64.0
1.0
8.0
3.0
2.5
0.8
0.0006
3.0
2.5
11.5
2.0
8.5
3.0
2.5
0.8
0.0006
3.0
2.5
17.0
2.0
9.0
3.0
2.5
0.8
0.0006
3.0
2.5
56.5
1.0
12.5
4.0
3.0
1.5
0.001
5.0
4.0
197
-------
the prime sources of energy for milling until comparatively recent times.
The function of flour milling is to separate the starchy endosperm, which
is the part that is ultimately made into flour, from the bran and germ of the
grain. The bran is composed of several outer coverings of the grain. The germ is
the embryo of the new plant.
There are many manufacturing processes used within the Feed and Grain
Industry. The scope of this contract limits detailed consideration to the
following processes:
1. Feed Milling
2. Flour Milling
3. Feed Flash Drying
FEED MANUFACTURING
Feed manufacturing involves the combining of cereal grains, oilseed meals,
and packinghouse and other by-products to produce rations most beneficial to
the production of meat, milk, eggs or fur. Molasses, vitamins, drugs and other
ingredients are occasionally used in minute quantities to further improve upon
the formulation. A flow diagram of a simplified feed manufacturing facility,
commonly referred to as a feed mill, is shown in Figure 51.(2)
Feed materials are usually shipped to the feed mill by truck or rail. The
medium-size and large-size mills sometimes receive their required grain by
barge. Grain is unloaded by gravity, by air or by hand. Frequently, railroad
boxcars are unloaded with power shovels and hand labor. Positive or negative
pressure air systems are generally used for unloading barges.
The movement of grain within the mill is usually by bucket elevator and
gravity.
Grain is usually stored in concrete bins. Its moisture content usually does
not exceed 15%, and 12% moisture content is preferred. If necessary, the grain
can be dried in a separate structure adjacent to the mill.
From the storage bins, whole grains are conveyed to cleaning, rolling,
grinding, and other plant processes. The processed grains may be shipped to
consumers or held for feed formulation. Finished feed formulas can be
198
-------
FIGURE 51
SIMPLIFIED FLOW DIAGRAM OF A
FEED MILL
r
i
i
i
V
BOX CAR
RECEIVING
HOPPER
•FABRIC FILTERS-
CYCLONES
1
1
O
u
id
1
rv
1 1
VENT
FILTERS
if 1
BIN
v'
BIN
1
B
t
1
i i
1
1
N
oe
|
kl
kl
HOPPER CAR
RECEIVING
HOPPER
31
"|CLEANER|^|ROU-E:R
I
SHIPPING
BASIC EQUIPMENT SHOWN IN SOLID LINES,
CONTROL EQUIPMENT IS DOTTED LINES.
199
-------
prepared in the form of finely ground mash*, pellets,.or mixed mash and
pellets.
Grinding
The basic grinding device is the hammer mill. The mill's grinding chamber
houses rows of loosely mounted swinging hammers and plates of hardened
steel. These hammers pulverize the grain by striking it sharply. The pulverized
grain is ejected from the mill when it is ground finely enough to pass through a
screen which is part of the mill. The screens have openings ranging from 1/8 in.
upwards to 1/2 in. The fineness of grind is determined by the type of feed in
which the ground material is to be used.
Other types of mills used in feed production include the attrition mill and
roller mills. In the attrition mill, revolving grinding plates pulverize the grain to
produce a finely textured soft product. Roller mills include pairs of corrugated
metal rolls, one of which revolves at a speed 2 to 4 times that of the other. The
grain is forced between the rolls and sheared by the corrugation.
A fan is required to convey the ground material away from the grinding
unit, whether it be a hammer mill, attrition mill or roller mill.
Cleaning
Scalpers**are one of several devices used to remove coarse, non-edible
material from the product flow before it reaches the mixer. Separators, which
consist of reciprocating sieves which classify grains of different sizes and
textures, perform a similar function.
Permanent or electric magnets are usually installed ahead of the grinder
for the removal of stray pieces of wire or metal.
Mixing
There are three basic types of feed mixers:
'Mixture of ground grain and water.
**Revolving wire cage containing curved, internal baffles.
200
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1. Vertical
2. Horizontal
3. Drum
The vertical mixer is the most widely used in the smaller plants. It can
range in capacity from 500 Ib to 7 tons and is usually a batch operation.
The ground grain and other ingredients, which may include a protein
source, vitamins, minerals, and drugs, are measured into the mixing cylinder.
The screws or paddles inside the cylinder are then operated for the necessary
time to establish the proper blending of the mixture.
A dry mash feed is ready for packaging, bulk delivery, or storage after it
has been mixed.
Pelleting
A major advantage of pellets is that all the components are bonded
together so that the bird or animal consumes the proper balance of nutrients
intended for it.
The manufacture of pellets begins with the blending of molasses or fat
with the dry mash. A binding agent is also incorporated into the mixture. Live
steam is added to the dry mixed feed as it enters the pellet mill. After the
pellets are formed and compressed, they are released into a cooling system
which hardens the pellets. Broken pellets and milling fines are returned to the
pellet mill for reprocessing.
FLOUR MILLING
Not all cereal grains are pulverized to a flour. Rice and barley are milled in
such a way that only the husk is removed. Oats are rolled into a flattened form.
The following is a description of the milling process used for the conversion of
wheat into flour.
A simplified flow diagram of a modern flour mill is shown in Figure 52.(3)
Wheat is stored at the mill in large bins. Most mills store at least 6 weeks
supply, with some having over 42 weeks storage capacity. On arrival, wheat
contains foreign impurities such as sticks, stones, string, rodent contamination,
201
-------
FIGURE 5Z
SIMPLIFIED FLOW DIAGRAM OF A
MODERN FLOUR MILL
4 RAW WHEAT
B,NS
4 UERCHEN _, ,f
FEEDERS ^i-^^
c.
DOTTED EXHAUST LINES CONNECT ALL ITEMS OF EQUIPMENT TO FABRIC FILTERS
-------
etc. which are removed before wheat goes into storage. Dust and smaller pieces
of foreign matter are removed in the cleaning done just prior to milling.
If the wheat is too wet, it is dried before going into storage. If the
moisture of the grain is above 14.5%, heat production results from the growth
of microorganisms in the grain. Hot air is used for the drying of wheat.
Evaporated moisture is carried away by air currents.
Cleaning Prior to Milling
As grain is needed for milling, it is withdrawn from storage and sent
through a cleaning operation.
Prior to entering the cleaning house from storage, the wheat is weighed.
Then it goes through the same type of separator used in cleaning prior to
storage, except the separator is set to remove fine impurities and dust. Light
impurities such as wheat chaff are removed by air currents. Next, the wheat
passes through magnetic separators which remove bits of metal which
inadvertently found their way into the wheat mix.
Then additional aspiration is provided, from which the wheat enters a
machine designed to remove cereal grains other than wheat and to remove
foreign seeds, particularly weed seeds. The unwanted seeds are caught in
specially designed pockets in a revolving metal plate, and are lifted up and
carried away, while the wheat passes through the machine.
Another cleaning operation is performed in a scourer. Scouring, a dry
operation, involves the removal of dirt on the surface of the wheat by friction.
Sometimes a light washing is performed prior to scouring in order to toughen
the bran coat.
The final cleaning step is a water wash, which dissolves the dirt and
permits stones and bits of metal to sink. The washer adds about 1% to the
moisture content of the wheat. In a typical washer, wheat is conveyed through
a trough of water where dirt is floated away and stones sink. After washing,
excess surface moisture is removed from the wheat by centrifugal forces.
Tempering and Conditioning
Tempering refers to the addition of water to the bran and endosperm. The
bran becomes tough and rubbery while the endosperm becomes softer, which
203
-------
improves the milling efficiency. Conditioning employs a controlled heating
process in addition to the moistening procedure.
Wheats can be broadly classified into the classes of hard wheat and soft
wheat according to their milling characteristics. Hard wheats require about 20%
more horsepower to grind to a given size. When hard and soft wheats are found
in the same wheat mix, the problem evolves into one of overgrinding the soft
wheat or undergrinding the hard wheat. If hard wheats are maintained in the
presence of moisture under the proper conditions and for appropriate periods
of time, they grind more like soft wheats.
Tempering, as it is still practiced in the United States, involves adding
water to grain to raise the moisture to 15 to 19% for hard wheats and 14.5 to
17% for soft wheats. An excessive amount of water is added to the grain, which
lies in tempering bins. The unabsorbed surface moisture is drained from the
tempering bins, and the wheat is allowed to lie in the bins for periods of 18 to
72 hours. Usually, tempering is done in successive steps since it is impractical to
add more than a few percent of water to wheat at one time.
Conditioning, in contrast to tempering, always involves the use of heat.
Quick diffusion of water into the endosperm as well as the bran is the purpose.
Normally, a temperature of 115°F cannot be exceeded without causing
detectable changes in the baking quality of the flour.
Wheat conditioners consist of four sections. The first section heats the
wheat to the proper temperature. The second adds moisture and holds the
wheat for the proper time. The third section cools the wheat to room
temperature. The final section allows time for the moisture in the wheat to
equilibrate prior to milling.
The wheat goes through the first three sections in 1.5 hours or less. The
wheat is held in the fourth section for 8 to 18 hours, with the longer times
being used for the harder wheats.
Grinding
The purpose of flour milling is first to separate the endosperm from bran
and germ in chunks as large as possible and then to reduce the size of the
endosperm chunks to flour-sized particles through a series of grinding steps.
The grinding of wheat is done between pairs of rolls. These rolls move in
opposite directions and at different rates of speed. They are set with an
204
-------
appreciable gap between them, such that they do not grind the wheat primarily
by crushing, but rather by shearing forces which are relatively gentle. The
rapidly moving roll runs about 2.5 times faster than the slower one and at
speeds from 250 to 450 rpm.
The roller milling area is divided into the break section and the reduction
section. The bran is broken open and the endosperm is milled away in the
break section. This section usually involves four or more sets of rolls, each
taking stock from the preceding one. After each break, the mixture of free
bran, free endosperm, free germ, and bran containing adhering endosperm is
sifted. The bran having endosperm still attached goes to the next break roll,
and the process is repeated until as much endosperm has been separated from
the bran as is possible.
The surface of break rolls is always fluted to obtain the necessary grinding
effect. The number of saw-tooth flutes increase from 10 to 12 flutes per inch
on the first break, to about 28 flutes per inch on the fourth break.
A sifting system (called scalping) follows each set of break rolls. The
scalping system is a combination of a sieving operation (plansifters) and air
aspiration (purifiers).
A plansifter consists of flat sieves piled in tiers, one above the other. The
action of the sifter is rotary in a plane parallel with the floor. As the sifter
moves in a 3.5 in. circle, the small-sized particles travel across the sieve to a
collecting trough and are removed. Large pieces of bran are first removed and
are sent to the next break roll. Bran and germ are scalped off the finer sieves.
Below these are the flour sieves. The resulting flour and endosperm chunks
(middlings) still contain minute size bran particles. These are removed by
sending the product through a purifier where air currents carry the bran away.
A purifier is a long oscillating sieve, inclined downwards, with air currents
passing through the sieve in the direction from floor to ceiling. The buoyancy
effect of the air causes the flour to stratify into endosperm chunks of different
sizes. Thus, a purifier is used to make a coarse separation of middlings as well as
for the removal of bran. The endosperm chunks fall through the sieve openings
and are sent to the appropriate reduction rolls. The overs are a composite of
bran and bran plus endosperm. These go back to the break rolls or to millfeed
stock. Aspirated materials go to millfeed.
For a flour roll break section, a scalping system containing 12 purifiers is
normal. The fine middlings from the first, second, third and fourth breaks
normally go through a double purification step while only one purification
205
-------
treatment is needed for the coarser middlings.
The reduction system consists of two parts, roll mills and sifting machines.
The major difference from the break system is that the surface of the reduction
mills is smooth rather than grooved. The reduction rolls reduce endosperm
middlings to flour size and facilitate the removal of the last remaining particles
of bran and germ.
In a reduction system the roll stands are divided into coarse rolls and fine
rolls. Coarse and fine is in reference to the setting of the rolls, whether they are
set wide to produce coarse grinding or close to produce fine grinding. The
middlings produced from the coarse rolls are sent to the fine rolls to be ground
to flour.
After each reduction, the resulting product is classified by particle size in
a sifter. Oversized material is sent back to the reduction rolls for further
processing. Normally there is at least one sifting device for every reduction roll
stand.
Conveying System
Older mills depend upon gravity for the transport of flour stock from
machine to machine. The wheat and flour is moved to the top of the mill by
bucket elevators, and then the material flows by spouts to the rolls and to the
sifters.
Bucket elevators are dusty and they provide a place for insects to grow.
Consequently, flour mills are abandoning bucket elevators and gravity spouts,
and are converting to air conveying. Powerful suction fans provide the negative
pressure. The air intake is through the roller mills. This air movement has the
desirable effect of keeping the rolls and the flour cool during grinding. The
simplified flow diagram of a modern flour mill shown in Figure 2 includes an
air conveying system.
FEED FLASH DRYING
Flash drying systems, as applied to the feed industry, are usually designed
to accomplish drying with disintegration. Such a system is shown in Figure
53.(2) This is in contrast to simultaneous drying and grinding operations. Since
the desired particle size has been established in the original wet feed, the dried
material is simply disintegrated, i.e., separation of loosely packed materials.
206
-------
FIGURE 53
FLASH DRYING COMBINED WITH DISINTEGRATION
AIR
INLET
OIL
OR GAS
BURNER
DRY
DIVIDER
EXPANSION
JOINT
•
1 1
AIR
HEATER
1 1
1 1
TO DRYING
SYSTEM
MIXER
CAGE
MILL
207
-------
Disintegration is usually accomplished with a cage mill.
In a flash dryer, or pneumatic conveyer dryer, moisture is removed by
dispersing the material to be dried in a hot gas zone followed by conveying at
high velocities. The dispersion is usually accomplished with a cage mill, a device
designed to break up loosely packed materials, or an imp mill for more tightly
compacted materials. The imp mill is a high-speed impact pulverizer.
The dryer system consists of a furnace or other source of hot gases, a
dispersion device, a duct through which the gases convey the material, and a
collection system for removing the dry product from the gas stream.
Frequently, the wet feed must be conditioned by mixing with recycled
dry product in a mixer. This is required in order to achieve good dispersion in
the cage mill. Filter cakes, the form of many by-products of wet milling
processes, have very unfavorable drying characteristics. They are usually
conditioned by mixing with previously dried material.
NATURE OF THE GASEOUS DISCHARGE
There are many sources of air pollution in the feed and grain industry.
Table 67(4) presents the more common sources.
The air pollution problems with regard to receiving, handling, and storing
operations are generally due to the fine dusts found in field run grains. Fine
particles are produced from the grain itself, by abrasion in handling and storing.
The fine dust may include the soil in which the grain was grown, or fine
particles originating from weeds or insects. Therefore, because of these possible
sources of fine dust, no reliable prediction of the kind and amount of dust in
any specific shipment of field run grain can be made.
Table 68<2) presents the particle size distribution of dusts generated during
the unloading of barley from a boxcar. The barley was received in a deep
hopper equipped with a control hood. A blower carried the dust picked up by
the control hood to a cyclone where the larger particles dropped out and were
collected in a sack (sample no. 1). The cyclone was vented to a fabric filter,
which collected the finer material in a hopper (sample no. 2).
Grain grinding, which is commonly done in feed mills with a hammer mill,
generates a large amount of fine dust. A fan conveys away the ground materials
from the hammer mill and discharges it into a cyclone. Typical dust losses from
a hammer mill cyclone, along with the dust losses from some grain cleaner
208
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TABLE 67
SOURCES OF AIR POLLUTION IN FEED AND GRAIN INDUSTRY141
Source
Grain Unloading
Grain Handling & Transport
Grain Cleaning
Grain Storage
Grain Grinding
Pelletizing of Feed Mixtures
Feed Loading into Trucks & Rail Cars
Flour Milling
Loading of Middlings & Chaff from
Flour Milling into Rail Cars
Loading Grain Dust Cars
Oil-Seed Expelling
Flash Drying
Barley Malt Toasting
Emission Type
Fine Dust
Fine Dust
Fine Dust
Fine Dust
Fine Dust
Fine Dust
(sometimes Odor)
Fine Dust
Very Fine Dust
Fine Dust
Fine Dust
Odor
Dust, Vapors & Odor
Odor
209
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TABLE 68(2)
PARTICLE SIZE ANALYSIS OF THE
PRIMARY CYCLONE CATCH AND THE SECONDARY
FABRIC FILTER CATCH OF DUST FROM A RAILROAD
RECEIVING HOPPER HOOD CONTROLLING THE
UNLOADING OF A BOXCAR OF FEED-TYPE BARLEY(al
Particle Size Distribution by Weight
Sample No. 1 Sample No. 2
Particle Size, y
Oto5
5 to 10
10 to 20
20 to 44
44 to 74
74 to 149
149 to 250
Over 250 (60 mesh)
Cyclone Bottoms, % F
0.9
0.9
3.9
9.3
12.9
16.2
5.4
50.5
abric Filter Hopper, %
4
25
66
5
0
0
0
0
(a)Specific gravity of both samples was 1.8.
210
-------
cyclones, are presented in Table 69.(2)
During the drying of a high-protein feed, the air contaminants that may be
emitted are dusts, vapors, and odors. If the material is agitated or stirred during
the drying process, such as in a flash drying system, dust emissions are likely to
be a problem. The nature of the emissions is determined by the material being
dried and the operating conditions of the drying system.
A typical flash drying system will reduce the moisture content of wet feed
from 60% down to 30%. For a 20,000 Ib/hr feed rate, this is equivalent to
removing 8,570 Ib/hr of moisture as a vapor. The gas flow associated with this
rate of water removal is 20,000 ACFM at 220° F.
In the modern flour mill the product flows by gravity from the top of the
building, through the various machines, to the ground floor. At the completion
of each phase of processing, the material is relifted to the top floor by
pneumatic conveyors for further processing. Many passes up and down the
building are required to produce the finished product. A considerable amount
of piping and auxiliary equipment is required in connection with these
pneumatic conveying systems. The conveying systems are typically divided up
according to their function as follows:
1. System for delivery of raw wheat from a nearby grain elevator
2. Pneumatic relift conveyors for the wheat cleaning and tempering
processes
3. Pneumatic conveyor for collecting the screenings from the cleaning
process
4. Pneumatic relifts for the wheat milling process
5. Pneumatic conveyors for the storage of finished flour and feed
All of the above pneumatic conveying systems are shown in Figure 52. The
design of each of these systems is a function of the nature of the material being
moved as well as the distance and rate of flow.
At the end of each pneumatic conveying line, the material is fed to a
receiver or cyclone. From the receiver or cyclone, the material falls by gravity
through rotary air-locks directly into processing machinery.
Each one of the pneumatic conveying systems is equipped with a dust
211
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TABLE 69
DUST LOSSES FROM CYCLONES'21
Grain
Basic Equipment
Process wt, Ib/hr
Exhaust Air Volum
SCFM
Dust Concentration
gr/SCF
Dust Loss, Ib/hr
Malted Barley
Grain Cleaner
Test No. 1
53,000
'/
2,970
0.194
4.95
Test No. 2
50,000
2,970
0.160
4.07
Feed Barley
Hammer Mill
10,350
3,790
0.488
15.8
Milo*
Grain Cleaner
11,250
First Cyclone
3,680
0.058
1.83
Second Cyclone
2,610
0.006
0.13
*A sorghum similar to millet and grown for forage
212
-------
collection system. Each of the five dust collection systems uses fabric filters. In
the cleaning section, for example, the dust collector aspirates all receivers on
the intermediate relift conveyors. In addition it aspirates the screenings suction
conveyor, all cleaning machinery, all feeders and all of the screw conveyors in
the cleaning section. The other four filters serve other areas of the plant in a
similar manner.
Therefore, the gaseous discharges from a modern flour mill should be,
except during periods of upset operation, extremely clean. In fact, since the
design of most pneumatic conveying systems allows for recycle of the air used
in them, there should be no gaseous discharges, except during periods of upset
operation.
POLLUTION CONTROL CONSIDERATIONS
Gases discharged from the following pieces of equipment and/or systems
will be considered:
1. Feed Grinder
2. Pneumatic Relift System for the flour milling process
3. Flash Drying System
In the cases of feed grinders and pneumatic relift systems, the emission
problem is limited to fine dusts. These fine dusts are the result of losses from
product recovery cyclones. Since it is desirable to recover the material lost
from these cyclones in a dry state the only practical means of control is the
fabric filter.
Since the exhaust fan in a flash drying system is usually placed at the
product discharge end of the system, the entire system is under negative
pressure. This precludes any emissions, except from the final collector where
the product is separated from the air stream.
Since the emissions from a flash drying system include odors as well as
fine dusts, the pollution control systems of interest are combustion and
absorption. The odor levels in the flash dryer specifications 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 1500 odor units per
cubic foot would require 1500 dilutions with clear, odor-free air to make it just
detectable.
213
-------
214
-------
SPECIFICATIONS AND COSTS
Specifications for air pollution control systems were written for three
sources in the feed and grain industry:
Flour mill pneumatic conveying systems
Feed mill grinders
Feed flash dryers
A fabric filter system was specified for the flour mill pneumatic
conveyors. The specifications are shown in Tables 70 and 71. The system was
not specified for total control of the mill. It was only designed to handle the air
from the cyclonic dust collectors on the pneumatic conveying system which
lifts milled grain from the rolls up to the classifying equipment. Other mill
emission sources, such as grain cleaning, are controlled by separate fabric filter
systems. Cost data are presented on Tables 72 and 73 and on Figures 54 and 55.
Confidence limits for the capital cost data are presented on Table 74 and
Figure 56.
A fabric filter system was also specified for the feed mill grinder. In
keeping with conventional industry practice, the system was designed to handle
only the grinder exhaust rather than the total mill exhaust. Specifications are
presented on Tables 75 and 76. Cost data are presented on Tables 77 and 78
and on Figures 57 and 58. Confidence limits for the capital cost data are shown
on Table 79 and Figure 59.
The emissions from the feed flash dryer consist of both particulate matter
and odor. Specifications were written to deal primarily with the odor problem
but included a request that suppliers quote the particulate removal efficiency
which would be achieved in their system. Both scrubber systems, using
buffered potassium permanganate, and thermal combustion systems were
quoted.
Specifications for wet scrubber systems are shown on Tables 80 and 81.
Cost data are presented on Tables 82 and 83 and on Figures 60 and 61.
Estimated removal efficiencies for particulate matter are also shown on Table
82. The primary component of the operating costs for the wet scrubber
systems is the consumption of potassium permanganate and borax. The cost of
these chemicals represents about 99% of the direct operating cost. These
chemical consumption numbers are based upon theoretical reaction calcu-
lations rather than upon actual operating data.
Specifications for thermal combustion systems are shown on Tables 85
and 86. Cost data are presented on Tables 87 and 88 and on Figures 63 and 64.
215
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TABLE 70
FABRIC FILTER PROCESS DESCRIPTION
FOR FLOUR MILLING SPECIFICATION
A fabric filter is to treat the effluent from the product recovery cyclones in a flour mill.
These cyclones are an integral part of the pneumatic conveying systems which move the
product from the mills to the associated plansifters at higher elevation for classification.
Conveying air and solid are separated by cyclone. The air from the top of the cyclones will
be routed to the subject fabric filter. The filtered air is recycled back to the pneumatic
conveying systems.
The required ductwork from the cyclone collector outlets to the fabric filter will be
provided by others. The vendor is to furnish the fabric filter proper, including hoppers
equipped with rotary air locks, the required booster fan, ductwork between the fabric filter
and fan, and controls.
The entire collection system will be located inside a building, which will be adjacent to
a public highway. There is little likelihood of interference caused by other equipment with
the location of pollution control equipment.
The fan 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. The system
pressure drop should include enough suction for the interconnecting ductwork between the
cyclone collector outlets and the control system inlet. Motors shall be capable of driving fans
at maximum recommended speed and the corresponding pressure differential at 20% over
design flow rate.
216
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TABLE 71
FABRIC FILTER OPERATING CONDITIONS
FOR FLOUR MILLING SPECIFICATION
Two sizes of fabric filters are specified at one efficiency level. Vendors' quotations
should 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
efficiency called for in this specification.
Plant Capacity, cwt./day
Process Weight, Ib/hr
Inlet to Fabric Filter
Flow.ACFM
Temperature, °F
% Saturation
Dew Point, °F
Loading, Ib/hr
Loading, gr/ACF
Loading, gr/DSCF
Small Large
3,000 10,000
12,500 41,700
6,000 20,000
70 70
30 30
38 38
40 134
0.778 0.778
0.779 0.779
CASE 1 - HIGH EFFICIENCY
Outlet Solids Rate, Ib/hr
Outlet Solids Loading, gr/ACF
Outlet Solids Loading, gr/DSCF
Collection Efficiency, wt. %
Air-To-Cloth Ratio
0.515
0.01
.01
98.7
6/1
1.72
0.01
.01
98.7
6/1
217
-------
TABLE 72
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR FABRIC FILTERS FOR FLOUR MILLING
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. °/
t
D
Cleaned Gas Contaminant 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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other ->
(4) Total Cost
>
'
Small
Large
High Efficiency
Small
6,000
70
6,000
.75
0.778
40
6,000
70
6,000
.75
0.01
0.515
98.7
5,537
1,409
-
233
654
509
2,197
10,539
Large
20,000
70
20,000
.75
0.778
134
20,000
70
20,000
.75
0.01
1.72
98.7
11,764
3,197
-
317
1,421
1,018
4,583
22,300
218
-------
FIGURE 54
CAPITAL COSTS FOR FABRIC FILTERS
FOR FLOUR MILLING
500000
CO
DC
O
o
O
o
100000
10000
1000
t
*
4
L
s^
f
>
^
>
<
^
X
y
x
/
/
X
/
,/
,x
A
^
^
J^
r
/,
s
/
TURNKEY SYSTEM
COLLECTOR PLUS
Al
CC
iX\
)LL
LI/
EC
kR
TC
IE
)R
S
(
31
SILY
1000 10000 100000 3000C
GAS FLOW, ACFM
219
-------
K)
NJ
O
TABLE 73
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR FABRIC FILTERS FOR FLOUR MILLING
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
8,000
$6/hr
$8/hr
f.Oll/kw-hr
Small
Large
High Efficiency
Small
165
236
-
350
1,246
1,246
1,997
1,054
3,051
Large
165
554
-
974
3,576
3,576
5,269
2,230
7,499
-------
FIGURE 55
ANNUAL COSTS FOR FABRIC FILTERS
FOR FLOUR MILLING
500000.
100000
O
Q
te
O
O
a.
<
O
10000
1000
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
J*±
OPERATING COST
10000
GAS FLOW, ACFM
100000
300000
221
-------
TABLE 74
CONFIDENCE LIMITS FOR CAPITAL COST
OF FABRIC FILTERS FOR FLOUR MILLING
Population Size - 20 Sample Size - 3
Capital Cost = $10,540
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $9,921 $11,158
75 9,341 11,738
90 8,449 12,630
95 7,624 13,455
Capital Cost =$22,300
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $21,809 $22,790
75 21,349 23,250
90 20,641 23,958
95 19,987 24,612
222
-------
FIGURE 56
CONFIDENCE LIMITS FOR CAPITAL COST
OF FABRIC FILTERS FOR FLOUR MILLING
500000
CO
DC
O
Q
te
O
U
Q.
<
U
100000
10000
1000
90°x
75°/
EA
75°/
90°/
'4
it
° *
r
4
\*
J 4
/^
)
s
s
/
s
^"
>
s
s
s
f1
s
s,
'/
^
-------
TABLE 75
FABRIC FILTER PROCESS DESCRIPTION
FOR FEED GRINDING SPECIFICATION
A fabric filter is to treat the effluent from the product recovery cyclone collectors in a
feed mill. These cyclone collectors are an integral part of the feed grinders.
The required ductwork from the cyclone collector outlets to the fabric filter will be
provided by others. The vendor is to furnish the fabric filter proper, including hoppers
equipped with rotary air locks, the required booster fan, ductwork between the fabric filter
and fan, and controls.
The entire collector system will be located inside a building, which will be adjacent to a
public highway. There is little likelihood of interference caused by other equipment with the
location of pollution control equipment.
The fan 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. The system
pressure drop shall be defined to include enough suction for the interconnecting ductwork
between the cyclone collector outlets and the control system inlet, i.e., ductwork provided
by others than the vendor. Motors shall be capable of driving fans at maximum
recommended speed and the corresponding pressure differential at 20% over design flow
rate.
224
-------
TABLE 76
FABRIC FILTER OPERATING CONDITIONS
FOR FEED GRINDING SPECIFICATION
Two sizes of fabric filters are specified at one efficiency level. Vendors' quotations
should 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
efficiency called for in this specification.
Plant Capacity, ton/hr
Process Weight, Ib/hr
Inlet to Fabric Filter
Flow,ACFM
Temperature, °F
% Saturation
Dew Point, °F
Loading, Ib/hr
Loading, gr/ACF
Loading, gr/DSCF
Small
6
13,200
Large
24
52,800
4,700
100
30
64
18.3
0.454
0.490
19,000
100
30
64
73.2
0.454
0.490
CASE 1 - HIGH EFFICIENCY
Outlet Solids Rate, Ib/hr
Outlet Solids Loading, gr/ACF
Outlet Solids Loading, gr/DSCF
Collection Efficiency, wt. %
Air-to-cloth ratio
0.40
0.01
0.011
97.8
6/1
1.63
0.01
0.011
97.8
6/1
225
-------
TABLE 77
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR FABRIC FILTERS FOR FEED GRINDING
Effluent Gas Flow
ACFM
°F
SCFM
. Moisture Content, Vol.
%
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol.
%
Cleaned Gas Contaminant Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
•
Small
(1) Gas Cleaning Device Cost
(incl.Dust Disposal Equip)
(2) Auxiliaries Cost ]
(a) Fan(s)
(b) Pump(s)
(c) Damper(s)
(d) Conditioning,
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other -^
(4) Total Cost
I
Large
High Efficiency
Small
4,700
100
4,420
.75
.454
18.3
4,700
100
4,420
.75
.01
.40
97.8
5,201
1,048
-
71
5,961
12,281
Large
19,000
100
17,800
.75
.454
73.2
19,000
100
17,800
.75
.01
1.63
97.8
14,395
2,476
-
117
15,074
32,062
226
-------
FIGURE 57
CAPITAL COSTS FOR FABRIC FILTERS
FOR FEED GRINDING
500000
100000
CO
DC
O
Q
O
O
10000
1000
TURNKEY SYSTEM
COLLECTOR!
XPLUS AUXILIARI
ES-
COLLECTOR ONLY
1000
10000
GAS FLOW, ACFM
100000
300000
227
-------
ro
N3
CO
TABLE 78
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR FABRIC FILTERS FOR FEED GRINDING
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
8.000
$8/hr
$.011/kw-h]
Small
Large
High Efficiency
Small
845
134
120
680
-
680
1,779
1,228
3,007
Large
845
327
481
2,960
.
2,960
4,613
3,206
7,819
-------
FIGURE 58
ANNUAL COSTS FOR FABRIC FILTERS
FOR FEED GRINDING
500000
O
Q
O
O
100000
10000
1000
X
X
/3
^
f
\/
^
^
/
/
/
/•
^
/
^
/
J*
_s
/
y81
X
7
{
>/;
x^ c
/c
OT/
OPE
API
)PEF
\L
RA
TA
?A1
CO
TIIS
L C
'IN
51
IG
H
G
C
Al
C
:c
=K
OJ
s
3E
>'
T PLUS
:S)
1000 10000 100000 3000G
GAS FLOW, ACFM
229
-------
TABLE 79
CONFIDENCE LIMITS FOR COLLECTOR ONLY COST
OF FABRIC FILTERS FOR FEED GRINDING
Population Size - 20 Sample Size - 3
Collector Cost = $5,201
Collector Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $4,670 $5,733
75 4,171 6,232
90 3,404 6,999
95 2,695 7,708
Collector Cost = $14,395
Collector Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $12,129 $16,660
75 10,005 18,784
90 6,737 22,053
95 3,715 25,075
230
-------
FIGURE 59
CONFIDENCE LIMITS FOR COLLECTOR ONLY COST
OF FABRIC FILTERS FOR FEED GRINDING
500000
c/j
cc
O
Q
te
O
O
_l
<
CL
O
100000
10000
1000
r
q
(J
£
^
jS
Y
<
f
jr
y
f
/
/
s
/
'
/
s
s
X
^
'//
s ^
/ >/
/
/ ^Q
^
x
/ 90%
5/ 75%
/ME
f
P
IAN
%
kv' 900/-
1000 10000 100000 300000
GAS FLOW, ACFM
231
-------
TABLE 80
WET SCRUBBER PROCESS DESCRIPTION
FOR FEED FLASH DRYER SPECIFICATION
The scrubber is to deodorize the total gases emitted from the product recovery cyclone
of a feed flash drying system. The scrubber will be located outside and will be in use on a
continuous basis. 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.%
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. Recirculation tank.
5. Permanganate makeup facilities and storage tank.
6. Interconnecting ductwork for all equipment furnished.
7. Appropriate control system.
8. Necessary provisions for periodic cleaning of manganese dioxide residue.
9. Winterizing protection down to -20°F.
All of the above, except the scrubber proper, should be treated as auxiliaries.
The scrubber must be designed to abate the odor from the effluent stream. However, an
estimate of paniculate removal efficiency is required.
Each bidder will submit four separate and independent quotations; one for each of two
efficiency levels at each of two plant sizes.
232
-------
TABLE 81
WET SCRUBBER OPERATING CONDITIONS
FOR FEED FLASH DRYER SPECIFICATION
Small Large
Product Rate, Ib/hr 7,360 51,300
Dryer Capacity, Ib/hr 10,500 73,300
Dryer System Discharge Conditions
Gas Flow, ACFM 10,000 70,000
Volume % Air 75 75
Water Content, Vol.% 10 10
Temperature, °F 170* 170*
Gas Flow, SCFM 8,250 57,800
Organic Content, gr/SCF 0.2 0.2
Organic Content, Ib/hr 14.2 99
Paniculate Loading, gr/DSCF 0.2 0.2
Odor Concentration, O.U./SCF 1,500 1,500
Odor Emission Rate, O.U./min. 12.4 x 10s 86.7 x 106
Medium Efficiency Case
Concentration @ Scrubber
Outlet O.U./SCF 500 500
% Odor Removal 67 67
High Efficiency Case
Concentration @ Scrubber
Outlet O.U./SCF 100 100
% Odor Removal 93.2 93.2
*Possibly as high as 250°F
233
-------
TABLE 82
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR FEED FLASH DRYERS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
Odor Cone., o.u./SCF
Odor Rate, o.u./min.
Cleaning Efficiency, % *
( 1 ) Gas Cleaning Device Cost
(Incl. Fan $ Motor)
(2) Auxiliaries Cost
(a) Pump(s)
(b) Damper(s)
(c) Conditioning,
Equipment
(d) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering ^
(b) Foundations
& Support
Ductwork
Stack
Electrical
Piping ?•
Insulation
Painting
Supervision
Startup
Performance Test
Other
_,/
(4) Total Cost
Medium Efficiency
Small
10,000
170
8,250
10
0.2
14.2
9,230
120
8,435
12.5
500
4.22 x 106
67
10,098
717
70
2,167
16,383
29,435
Large
70,000
170
57,800
10
0.2
99.0
64,570
120
59,000
12.5
500
29.5 x 106
67
33,050
1,295
141
5,500
29,577
69,563
High Efficiency
Small
10,000
170
8,250
10
0.2
14.2
9,230
120
8,435
12.5
100
0.84 x 106
93.2
10,478
717
70
2,167
16,383
29,815
Large
70,000
170
57,800
10
0.2
99.0
64,570
120
59,000
12.5
100
5.9 x 106
93.2
35,043
1,295
141
5,500
29,577
71,556
*Estimated particulate removal
234
for both cases is 99.
-------
FIGURE 60
CAPITAL COSTS FOR WET SCRUBBERS
FOR FEED FLASH DRYERS
(HIGH EFFICIENCY)
500000
CO
cc
§
te
8
u
100000
10000
1000
«•
••
y
X
*
£
£
J
^
7
,/
H
^
X
x
x^
2
—
X
^
x
X
X
'
Jj
I*
I
^
^
r1
fl
<
TURNKEY SYSTEM
""
•»
'
COLLECTO
PLUS AUX
COLLECTO
'-
R
ILIARIES
R ONLY
1000 10000 100000 300000
GAS FLOW, ACFIVI
235,
-------
TABLE 83
ANNUAL OPERATING COST DATA (COSTS IN S/YEAR)
FOR WET SCRUBBERS FOR FEED FLASH DRYERS
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
8,000
$.011/kw-hr
$.25/M gal
$0.39/lb
$0.0625/lb
Medium Efficiency
Small
170
1,207
300
2,126
1,800
203,830
175,090
382,846
384,523
2,944
387,467
Large
170
1,207
550
14,784
15,600
1,421,753
1,221,286
2,673,423
2,675,350
6,956
2,682,306
High Efficiency
Small
170
1,207
300
2,196
1,800
283,577
243,593
531,166
532,843
2,982
535,825
Large
170
1,207
550
15,616
15,600
1,977,737
1,698,876
3,707,829
3,709,756
7,156
3,716,912
-------
FIGURE 61
5,000,000
ANNUAL COSTS FOR WET SCRUBBERS
FOR FEED FLASH DRYERS
(HIGH EFFICIENCY)
1,000,000
e/J
oc
O
Q
te
O
O
100,000
10,000
TOTAL COST
(OPERATING COST
PLUS CAPITAL CHARGES)
10000
GAS FLOW, ACFM
100000
300000
237
-------
TABLE 84
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS FOR FEED FLASH DRYERS
(HIGH EFFICIENCY)
Population Size — 20 Sample Size — 3
Capital Cost = $29,815
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $23,569 $36,061
75 17,713 41,917
90 8,702 50,928
95 370 59,260
Capital Cost = $71,556
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $60,701 $82,412
75 50,523 92,590
90 34,862 108,251
95 20,380 122,733
238
-------
FIGURE 62
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS FOR FEED FLASH DRYERS
(HIGH EFFICIENCY)
500000
V)
cc
o
o
te
o
o
Q.
<
o
100000
10000
1000
•
^
6
(•
>
&
>
-X-
^*"^^-
<^
^
T
^
^
r
*
/
sX
7
^ •
'" ^~
.x»"
^
^
/
X
_^ •
^
•^
^
/
X
^,
r
***
*s
f^
/'
— '
X
jf
/
£
(.
(
^
f,
J*
Y
tf
!f
JT
f
g
7
3'
5'
VIE
'o
y0
AN
75%
£
0
%
1000 10000 100000 300000
GAS FLOW, ACFM
239
-------
TABLE 85
THERMAL INCINERATOR PROCESS DESCRIPTION
FOR FEED FLASH DRYER SPECIFICATION
The incinerator is to deodorize the total gases emitted from the product recovery
cyclone of a feed flash drying system. The incinerator will be in use on a continuous basis.
The incinerator is to be natural gas fired. The burner shall be of the 100% secondary air
type, utilizing oxygen in the flash drying system effluent for combustion. The burner shall
be equipped with a continuous pilot, and shall be controlled to maintain an outlet
temperature no higher than 1,500°F. Gas piping, flame failure controls, etc., shall be
designed to meet F.I.A. * safety standards.
The incinerator must be designed to abate the odor from the effluent stream.
Also, reuse of heat is a prime concern and is to be accomplished by a self-recuperative
heat exchanger. Dirty gas will be on the tube side of the heat exchanger.
The incinerator will be located outdoors near the flash dryer outlet. The incinerator
shall be maintained under a slightly positive pressure by virtue of a fan at the inlet of the
heat exchanger on the odorous gas side. This fan is to be selected to overcome the pressure
drop of the incinerator, both sides of the heat exchanger, and the 30 feet of interconnecting
ductwork between the product recovery cyclone outlet and the heat exchanger inlet. The
fan will be provided with a draft breaker to prevent upsetting the pressure balance at the
product recovery cyclone.
*Factory Insurance Association
240
-------
TABLE 86
THERMAL INCINERATOR OPERATING CONDITIONS
FOR FEED FLASH DRYER SPECIFICATION
One incinerator should be quoted for each size dryer listed below.
Product Rate, Ib/hr
Dryer Capacity, Ib/hr
Dryer System Discharge Conditions
Gas Flow, ACFM
Volume % Air
Water Content, vol.%
Temperature, °F
Gas Flow, SCFM
Organic Content, Btu/SCF
Organic Content, gr/SCF
Organic Content, Ib/hr
Particulate Loading, gr/SCF
Odor Concentration, O.U./SCF
Odor Emission Rate, O.U./min
Incinerator Discharge Conditions
Gas Flow, SCFM
Temperature, °F
Odor Concentration, O.U./SCF
Odor Emission Rate, O.U./min
Combustion efficiency, %
Hot gas discharge from heat exchange, °F
Cold gas flow, SCFM
Cold gas temperature, °F
Cold gas discharge temperature, °F
Heat exchanger duty, MM Btu/hr
Small
7,360
10,500
10,000
75
10
170
8250
0.5
0.2
14.2
0.2
1,500
12.4 x 106
^€,400
1,500
100
.84 x 106
93.2
622
8250
170
1,058
-8.2
Large
51,300
73,300
70,000
75
10
170
57,800
0.5
0.2
99
0.2
1,500
86.7 x 106
^68,700
1,500
100
5.87 x 106
93.2
622
57,800
170
1,058
-8.2
241
-------
TABLE 87
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR THERMAL INCINERATORS FOR FEED FLASH DRYERS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Dust Loading
Odor Cone. ,o.u./SCF
Odor Rate, o.u./min.
ftrprmiir Printout , RTII/SPF
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Dust Loading
Odor Cone. ,o.u./SCF
Odor Rate, o.u./min.
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other (Unit Erection)
(4) Total Cost
Small
Large
High Efficiency
Small
10,000
170
8,250
10
1,500
12.4 x 106
0.5
31,352
1,500
8,315
11
100
0.83 x 106
93.2
59,875
3,583
-
308
2,050
2,400
3,100
875
875
250
750
50
700
450
1,750
3,000
80,016
Large
70,000
170
57,800
10
1,500 ,
86.7 x 106
0.5
219,240
1,500
58,195
11
100
5.82 x 106
93.2
210,700
19,205
-
605
4,500
8,750
10,000
3,200
3,415
750
2,000
100
2,000
1,100
1,750
6,700
274,775
242
-------
FIGURE 63
CAPITAL COSTS FOR THERMAL INCINERATORS
FOR FEED FLASH DRYERS
500000
100000
oo
cc
fc
8
Q.
<
U
10000
1000
^COLLECTOR
PLUS AUXILIARIES
COLLECTOR ONLY
URNKEY SYSTEM
10000
GAS FLOW, SCFM
100000
300000
243
-------
TABLE 88
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR THERMAL INCINERATORS FOR FEED FLASH DRYERS
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
8,000
$6/hr.
$6/hr.
$.011/kw-h:
$.80/MMBtu
LA Process Wt.
Small
Large
High Efficiency
Small
1,575
1,575
360
65
425
125
2,845
44,890
47,735
49,860
8,002
57,862
Large
2,325
2,325
720
300
1,020
275
19,750
212,512
232,262
235,882
27,478
263,360
-------
FIGURE 64
ANNUAL COSTS FOR THERMAL INCINERATORS
FOR FEED FLASH DRYERS
o
Q
O
O
100000
10000
1000
1
/
#
s
V
/
/
(OPEF
r>i 1 1
-------
TABLE 89
CONFIDENCE LIMITS FOR CAPITAL COST
OF THERMAL INCINERATORS FOR FEED FLASH DRYERS
Population Size — 5 Sample Size — 2
Capital Cost = $80,015
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $79,891 $80,139
75 79,740 80,289
90 79,446 80,584
95 79,128 80,902
Capital Cost = $274,775
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $259,065 $290,485
75 239,985 309,565
90 202,637 346,913
95 162,298 387,252
246
-------
FIGURE 65
CONFIDENCE LIMITS FOR CAPITAL COST
OF THERMAL INCINERATORS FOR FEED FLASH DRYERS
500000
100000
oo
DC
O
Q
te
O
O
a.
<
O
10000
1000
90%
75%
JgfMEAN
75%
90%
10000
GAS FLOW, SCFM
100000
300000
247
-------
REFERENCES
1. Matz, Samuel A., Ph.D., Cereal Technology, The AVI Publishing
Company, Inc., Westport, Conn., 1970.
2. Air Pollution Engineering Manual, U.S. Dept. of Health, Education, and
Welfare, Public Health Services Publication No. 999-AP-40, Cincinnati,
Ohio, 1967.
3. "Plant Services Beat Explosion Hazards," Modern Power and Engineering,
pp. 40-4, November, 1970.
4. McLouth, Malcolm E. and Paulus, Harold J., "Air Pollution from the
Grain Industry," Journal of the Air Pollution Control Association, Vol.
11:7, p. 313-17, July, 1961.
248
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PAINT and VARNISH
-------
3. PAINT AND VARNISH
The Paint and Varnish industry is one of the oldest manufacturing
industries in the United States. The industry is made up of about 1,600
companies operating 1,875 plants.11' It is well distributed geographically
throughout the country and the number of plants or production volume is
definitely related to density of population. Even though about 27 companies
account for about 57% of the total sales, the industry is one of the few
remaining which contains numerous small companies that specialize in a limited
product line to be marketed within a geographical region. There are fewer than
20 companies that sell paint nationwide.
The industry is now emerging as a scientific business from its beginning as
an art 50 years ago. Even with rapid growth in technology, the industry
processing techniques still are not well defined and vary from one producer to
another. To add further complication, the industry is technically one of the
most complex of the chemical industry. A plant that produces a broad line of
products might utilize over 600 different raw materials and purchased
intermediates. These materials can be generally classified in the following
categories: oils, metallic dryers, resins, pigment extenders, plasticizers, solvents,
dyes, bleaching agents, organic monomers for resins and additives of many
kinds.
The industry produces an equally large number of finished products which
are generally classified as trade sale finishes, maintenance finishes, and
industrial finishes.
Trade sale products are stock-type paints generally distributed through
wholesale-retail channels and packaged in sizes ranging from 1/2 pint to 1
gallon. A subdivision of trade sale products are maintenance finishes which are
used for the protection and upkeep of factories, buildings, and structures such
as bridges and storage tanks. Since they are usually stock type, they come
under the Department of Commerce definition of trade sales.
The other major type of paint products is industrial finishes which are
generally defined as those applied to manufactured products. These finishes
such as automotive, aircraft, furniture and electrical are usually specifically
formulated for the using industry. Within these major product lines there are
literally thousands of different products for many different applications and
types of customers. Trade sales finishes and industrial finishes are produced in
almost equal volume with the production for this year estimated at 475 million
gallons for each type. Trade sales, however, are expected to account for 55% of
the dollar sales or about $1,685 million dollars.
249
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PROCESS DESCRIPTION
Starting with all purchased raw material, the manufacturing process for
pigmented products is deceptively simple from a process viewpoint. Basically, it
consists of mixing or dispersing pigment and vehicle to give the final product.
This is schematically illustrated in Figure 66.
The paint vehicle is defined as the liquid portion of the paint and consists
of volatile solvent and non-volatile binder such as oils and resins. The
non-volatile portion is also called the vehicle solid or film former. The pigment
portion of the paint consists of hiding pigments such as titanium dioxide
(Ti02), extenders or fillers such as talc or barium sulfate, and any mineral
matter used for flatting or other purposes.
The incorporation of the pigment in the paint vehicle is accomplished by a
combination of grinding and dispersion or dispersion alone. When it is
necessary to further grind the raw pigment, the pebble or steel ball mills are
normally used. With the advent of fine particle grades of pigment and
extenders, as well as the wide spread use of wetting agents, the trend is toward
milling methods that are based on dispersion without grinding. This dispersion
consists of breakup of the pigment clusters and agglomerates, followed by
wetting of the individual particles with the binder or vehicle. Some of the more
popular methods currently being used are high speed disc impellers, high speed
impingement mills and sand mills.
Aside from this dispersion step, pigment paint manufacturing involves
handling of raw material as well as handling and packaging of finished product.
Operations of a typical plant may be summarized as a raw material and finished
product handling problem with a variety of interdispersed batch operations.
The interrelationship of all these operations is schematically illustrated in
Figure 67.The operations depicted are those of a plant that makes its own resins
and produces both trade sale and industrial finishes.
Many of the larger and some of the medium size manufacturers produce a
significant amount of their formulation ingredients, primarily resins. A few
large manufacturers also produce pigments, modified oils, and basic chemicals.
Certain manufacturers produce these ingredients in an amount exceeding their
requirements and sell the excess to other manufacturers. A significant number
also produce only a portion of their resins and purchase the remainder from
their competitors or suppliers who specialize in resin manufacturing.
The manufacturing of resins and varnishes is by far the most complex
250
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FIGURE 66
RAINIT MANUFACTURING USING
SAND MILL. FOR GRINDING OPERATION
MIXER
n
PRE-MIX
TANK
PRE-M1X
TANK
/ LOADING HATCH
PRE-MIX
RECIRCULAT1NG'
LINE
SAND
GRINDING
VESSEL
STORAGE
"TANK
TO
CAN
FILLING
LINE
FEED
PUMP
TAKE
AWAY
PUMP
ro
Ui
-------
FIGURES?
MATERIALS FLOW SHEET FOR PAINT MANUFACTURING
RAW MATERIALS HANDLING
FORMULATION
PACKAGING
TRADE SALES
CATALYST,
1 ADDITIVES
ADDITIVES i
INDUSTRIAL SALES
LACQUER
TYPE
£
CELLULOSE
HFDl VATIVP^
i
PREMIX
MIXI NG
TO
PAINT
STORAGE
i
CONTAINER
HANDLING
TO SHIPMENT
-------
process in a paint plant, primarily as the result of the large variety of different
raw materials, products and cooking formulas utilized. The complexity begins
with the nomenclature used in classification of the final product. Originally,
varnishes were all made from naturally occurring material and they were easily
defined as a homogeneous solution of drying oils and resins in organic solvents.
As new synthetic resins were developed, the resulting varnishes were classified
as resins rather than varnishes. Examples of this are alkyd, epoxy, and
polyurethane resin varnishes.
There are two basic types of varnishes, spirit varnishes and oleoresinous
varnishes. Spirit varnishes are formed by dissolving a resin in a solvent and they
dry by solvent evaporation. Shellac is a good example of a spirit varnish.
Another material that might fall in this category is lacquer. Technically,
lacquers are defined as a colloidal dispersion or solution of nitro-cellulose, or of
similar film-forming compounds, with resins and plasticizers, in solvent and
diluents which dry primarily by solvent evaporation.
Oleoresinous varnishes, as the name implies, are solutions of both oils and
resins. These varnishes dry by solvent evaporation and by reaction of the
non-volatile liquid portion with oxygen in the air to form a solid film. They are
classified as oxygen convertible varnishes and the film formed on drying is
insoluble in the original solvent. A summary of the various types of material
used in the production of classical varnishes is given in Table 90.(2)
Varnish is cooked in both portable kettles and large reactors. Kettles are
still being used, to a limited extent, by the smaller manufacturers, but some
continue to be phased out each year. The very old, coke fired, 30 gallon
capacity copper kettles are no longer used. The varnish kettles which are used,
have capacities of 150 to 375 gallons. These are fabricated on stainless steel,
have straight sides and are equipped with three or four-wheel trucks. Heating is
done with natural gas or fuel oil for better temperature control. The kettles are
fitted with retractable hoods and exhaust pipes, some of which may incor-
porate solvent condensers. Cooling and thinning are normally done in special
rooms. A typical varnish production operation is illustrated in Figure 68.
The manufacturing of oleoresinous varnishes is somewhat more complex
than for spirit varnishes. This manufacture consists of the heating or cooking of
oil and resins together for the purpose of obtaining compatability of resin and
oil and solubility of the mixture in solvent, as well as for development of higher
molecular weight molecules or polymers.
The time and temperature of the cook are the operating variables used to
253
-------
NJ
CJ1
*••
OILS
1. Hard
a. Tung
b. Oiticica
c. Dehydrated castor oil
2. Soft
a. Linseed
b. Safflower
c. Soya
d. Fish
e. Tall oil fatty acids
3. Chemically Modified
a. Maleic-treatment
TABLE 90
VARNISH RAW MATERIAL*2'
RESINS
1. Natural
a. Fossil resin, congo
kauri, pontianak
b. Semi-fossil resin
manila, boea, batu,
eastindia
c. Recent and crop resin
dammar, accroides
sandaral mastic, elemi,
shellac
d. Rosin
Gum rosin
Wood rosin
Tall oil rosin
Rosin esters
2. Synthetic Resin
a. Maleic resin
phenolic resin
3. Metallic Soaps
a. Limed rosin
b. Zinc resinate
SOLVENTS
1. Mineral Spirits
2. VM&P Naphtha
3. Toluol
4. Xylol
5. Terpene Solvents
DRYERS
Lead
Manganese
Cobalt
Calcium
Zirconium
ADDITIVES
Anti-skinning
Agents
Ultra-violet
absorber
Flattening
Agents
-------
FIGURE 68
YPICAL_ VARNISH OOOKINC3 ROOM
NJ THINNING
S ROOM
RECYCLE
RUMR
OILS AND
VARNISH
TO SEWER
WET
SCRUBBER
COOLING
STATION
COOKING
STATION
-------
develop the desired end product polymerization or "body". The chemical
reactions which occur are not well defined. The resin is a polymer before
cooking and may or may not increase in molecular size during the cook. This
resin may react with the oil to produce copolymers of oil and resin or it may
exist as a homogeneous mixture or solution of oil homopolymers and resin
homopolymers.
It is possible to blend resins and heat-bodied oil and obtain the same
varnish that can be produced by cooking the resin and the unbodied oils. This
indicates that copolymerization is not the fundamental reaction in varnish
cooking.
Heat bodying or polymerization of an oil is done to increase its viscosity
and is carried out in a kettle in a fashion similar to varnish cooking. The
fundamental reaction that occurs is polymerization of the oil monomers to
form dimers with a small portion of trimers.
There is a large variety of synthetic resins produced for use in the
manufacture of surface coatings. A listing of the more popular resins is given
below. They are listed by order of consumption by the coatings industry:'6'
Alkyd Styrene Butadiene
Vinyl Phenolic
Amino Polyester
Epoxy Urethane
Acrylic Silicone
By far the most widely used of these resins are the alkyds and the vinyls. Alkyd
consumption is approximately five times that of the vinyl, which is
approximately twice that of the amino resins. Further discussion will
concentrate on alkyd resins.
Alkyd resins comprise a group of synthetic resins which can be described
as oil-modified polyester resins. They are produced from the reaction of
polyols or polyhydric alcohol, polybasic acid and oil or fatty monobasic acid.
A listing and discussion of commonly used raw materials will follow.
256
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1. Oils or Fatty Acid'2'
Linseed
Soybean
Safflower
Tall Oil Fatty
Tall Oil
Fish
Tung (minor)
Oiticica (minor)
Castor
Coconut
Cottonseed
Laurie Acid
Pelargonic Acid
Isodecanoic Acid
Dehydrated Castor (minor)
The materials in the first column are oxidizing or drying types. The
materials in the second column are non-oxidizing and yield soft non-drying
alkyds which are used primarily as plasticizers for hard film resins. The acids
shown in this column are the only materials that are strictly synthetic in origin.
2. Polyols
Name
Ethylene glycol
Formula
HC - OH
HC - OH
H
Form
Liquid
H H H H
Diethylene HO-C - C - 0-C— C-OH
glycol H H H H
Liquid
Propylene glycol
H H H
HC- C- OH
H | H
OH
Liquid
Glycerine
CP-95% glycerine
Super-98%
H
HC -
I
HC -
I
HC -
H
OH
OH
OH
Liquid
Pentaerythritol
HOCH-
COH
White Solid
HOCH2'
H2COH
257
-------
Glycerol or glycerine was the first polyol used for alkyds. It is also the
most widely used polyol for alkyds.
The second polyol, based on usage, is pentaerythritol (PE), which came
into common use in the 1940' s. PE is supplied as "technical grade" material
and contains mono, di, tri, and polypentaerythritol. The material consists
primarily of the mono form which was illustrated previously in the list of
polyols.
The important distinguishing feature of the various polyols is the number
of potentially reactive hydroxyl groups in the molecule, known as
functionality. The glycols with a functionality of two produce only straight
chain polymers and their resins are soft and flexible. The resultant products are
used primarily as plasticizers for hard resins. Glycerine has a functionality of
three and is used primarily in short and medium oil alkyds. Pentaerythritol,
with a functionality of four, cross links to a greater extent, forming harder
polymers. It is ideal for use in long oil alkyds.
3. Acids and Anhydrides
Name
Formula
Form
Phthalic
anhydride
(ortho)
HC
i
HC
White solid
0
H
Isophthalic
acid (meta)
HC
1
HC
H
OH
White needles
0
OH
Terephthalic
acid (para)
HC
II
HC
White crystals
CH
CH
258
-------
Maleic # White solid
anhydride HC C
O
HC C
0
The acidic material can be used as an acid or anhydride. The anhydride is
formed from two molecules of acid minus a molecule of water or removal of
one molecule of water from a di-acid. It is preferred, since it reacts faster and
yields less water for removal from the cook.
For many years, ortho phthalic anhydride (PA) was the only polybasic
acid used in substantial proportions in alkyds. It still remains the predominant
dibasic acid. PA is produced from the catalytic oxidation of naphthalene or
ortho-xylene.
The chemistry of alkyd resin systems is very complex. So much so that
theoretical considerations offer only a good starting point. Final formulae and
variations are developed by trial and error changes, based on performance
requirements and shortcomings of previous batches.
Condensation is the reaction basic to all polyester resins, including alkyds.
This reaction follows the elementary equation for esterification as shown
below:
+ H20
Acid + Alcohol Ester + Water
For Alkyd Resins
PA + Glycerine $=i Ester + H20
The ester monomer formed is very complex and further reacts to form
large polymers called resins. The polymers formed are low in molecular weight
259
-------
by comparison to other resins. For example alkyd resins have molecular
weights ranging from 1,000 to 7,000 while some vinyl and acrylic resins have
average molecular weights in excess of 100,000 and in some cases as high as
500,000.
The alkyd polymers also react with oil or fatty acid and are generally
classified by the amount of oil or PA used in the formulation, as described
below:
% Oil % PA
Short Oil
Medium Oil
Long Oil
Very Long Oil
33 to 45
46 to 55
56 to 70
71 up
35
30 to 35
20 to 30
20
The resulting reactants of the PA, polyol and oil may be represented in
part as shown below.
Phthalic Anhydride (PA) + Glycerine (G) •*
I
OH
-G-PA-G-PA-G-PA-G-PA-
OH O 0 OH
HOOC - PA PA - COOH
This will then react with the long chain oil monoglyceride or fatty acid
(FA) to yield:
HOOC -PA-G-PA-G-PA-G-PA-G-PA-G-PA-G-OH
OH > OH OH > OH
Short oil alkyd
Alkyds can be manufactured directly from a fatty acid, polyol and acid
or from the fatty acid oil, polyol and acid. The second combination (oil.
260
-------
glycerine and PA) produces glyceryl phthalate which is insoluble in the oil and
precipitates. This problem can be overcome by first converting the oil to a
monoglyceride by heating with a polyol in the presence of a catalyst. This
process is called alcoholysis of the oil. The basic reaction is shown below:
CH2OOCR CH2OH CH2OH
I I I
C-HOOCR + 2CHOH -> 3CHOH
C-H2OOCR C-H2OH CH2OOCR
Triglyceride Glycerine Monoglyceride
This is an ester interchange reaction with no loss of water.
When fatty acid rather than oil is used as the starting material, this is
called the "one-stage" process. In this process, the fatty acid and glycerine are
added to the kettle, the agitator is started and heat is introduced. When the
batch reaches 440° F, the PA is slowly added and cooking continued for
another 3 to 4 hours until the desired body and acid number are reached.
If the fusion process is being used, a continuous purge of inert gas is
maintained to remove the water formed in the reaction. This water may also be
removed by what is known as the solvent process. It is similar to the fusion
process except that about 10% aromatic solvent (usually xylene) is added at the
start. The vaporized solvent is passed into a condenser. The condensate then
flows to a decant receiver for separation of reaction water. Recovered solvent is
returned to the reactor.
As discussed earlier, when oil is used rather than fatty acid, the alkyds are
produced in a two stage process. In the first stage the monoglyceride is first
produced from the linseed oil and glycerol. Catalyst and oil are added and the
alcoholysis of the polyol and oil is carried out between 450 and 500° F until
the desired end point is reached. When the alcoholysis is completed, any
additional polyol needed is added.
Following this, the required amount of PA and esterification catalyst are
slowly added. If solvent cooking is to be used, the solvent is also added at this
time. Cooking then proceeds as before.
A typical manufacturing formula for a 50% oil-modified glyceryl
phthalate alkyd using the two stage process is given below.'4'
261
-------
Ib
First stage
Linseed oil 51.3
Glycerol (95%) 12.8
Catalyst, Ca(OH)2 0.026
Second stage
Glycerol (95%) 6.2
Phthalic Anhydride 39.7
Catalyst
Methyl p-Toluene Sulfonate 0.2
110.2
Approx. Loss 10.2
Solids Yield 100.0
Alkyd and other resins are cooked in closed set kettles more properly
called reactors. They vary in size in commercial production from 500 to 10,000
gallons. A typical reactor system is shown in Figure 69. They are generally
fabricated of Type 304 or 316 stainless steel with well polished surfaces to
assure easy cleaning. Design pressure is usually 50 psig. These reactors may be
heated electrically, direct fired with gas or oil, or indirectly heated using a heat
transfer medium such as Dowtherm(R>. They are also equipped with a
manway, sight-glass, charging and sampling line, condenser system, weigh tanks,
temperature measuring devices and agitator. The manway is used both for
charging solid material and for access to the kettle for cleaning and repair.
The reactor may be equipped with a variety of different condenser
systems. The system shown in Figure 69 includes a packed fractionating
column, a reflux condenser and a main condenser. The condensers are water
cooled shell and tube type and may be either horizontally or vertically inclined.
Vapors are processed and condensed on the tube side and drain to a decant
receiver for separation and possible return as solvent to the reactor. A dual
function aspirator Venturi scrubber is often added to the system. It is used to
ventilate the kettle during addition of solid materials and may also remove
entrained unreacted or vaporized solids and liquids from the venting gases.
262
-------
FIGURE 69
MODERN RESIN PRODUCTION SYSTEM
• SPRAY TOWER
REIFL-UX
COMDEMSER
CONDEFNISER
FRAC T IONIAT IMG
DISTILLATION!
COLUMN
DECANTER
REICEIIVEIR
FUN/IE
SCRUBBER
REACTOR
PORTHOLE
FOR SOLIDS
OVERFLOW
TO SEWER
COMDEMSET.R
THINIISI IMG
DIRECT FIRED OR
JACKETED FOR HIGH
TEMPERATURE VAPOR
R LIQUID
pro REIS>IN)
STORAGE
263
-------
Thinning tanks are always included as part of the reactor system. They are
normally water cooled and equipped with a condenser and agitator. The
partially cooled finished alkyd is transferred from the reactor to the partially
filled thinning tank. Since most alkyd resins are thinned to 50% solids, the
capacities of these tanks are normally twice the capacity of the reactors. These
tanks are also frequently mounted on scales so that thinning solvents may be
accurately added.
The final step in a reactor system is filtering of the thinned resin prior to
final storage. This is normally done while it is still hot. Filter presses are the
most commonly used filtering device.
The manufacturing procedures and equipment used for the production of
other resins listed at the beginning of this discussion are quite similar. The
major differences are the raw materials and the process steps utilized. A
detailed discussion of these other resins is beyond the scope of this narrative.
NATURE OF GASEOUS DISCHARGE
There are two major types of emissions from a paint plant. These are
non-fugitive and fugitive. Non-fugitive emissions are those that are collected by
and confined within an exhaust system. Fugitive emissions are those that
escape into the plant atmosphere from various operations and exit the plant
building through the doors and windows in an unregulated fashion.
In today's typical paint plant there are two types of fugitive emissions.
These are pigment paniculate and paint solvents. In a small percentage of the
plants an attempt is made to collect these emissions. The incentive for doing so
is based on insurance requirements as well as occupational health and safety
rather than air pollution considerations or regulations. The newly passed OSHA
regulations will have a dramatic effect on the paint industry practice and
necessitate the regulation of fugitive emissions.
PARTICULATE CONTAMINANTS
Fugitive particulate emissions consist primarily of the various pigments
used. As a general rule, the pigments are received and stored in 25 to 50 pound
paper sacks or fiber drums. Modern pigment manufacturing has developed fine
sized pigment, 0.05 to 0.25 microns, for ease of dispersion into the paint
vehicle. Loading of these fine pigments into grinding equipment results in
264
-------
fugitive particulate dust emissions into the surrounding plant areas. This dust is
either collected by a ventilation and exhaust system or allowed to settle and
later collected as part of the general housekeeping requirements.
A variety of resins are received as granular or flaked solids which are of
large size and do not result in a fugitive dust emission. The manufacturer of
these solid resins, however, does encounter fugitive emission problems in his
flaking or grinding operations.
GASEOUS CONTAMINANTS
Solvent emissions occur in almost every phase of paint and varnish
manufacturing and in numerous locations throughout individual plants. A
listing of emission points is given below.
Location Operation Temp., °F Pressure
1. Resin Plant Thinning 200 to 300° F Atmospheric
2. Resin Plant Filtering 200 to 300° F Atmospheric
3. Resin Plant Storage Tanks 100°F Atmospheric
4. Paint Plant Blending Tanks Ambient Atmospheric
5. Paint Plant Milling Ambient Atmospheric
6. Paint Plant Dispersion Ambient Atmospheric
7. Paint Plant Holding Tank Ambient Atmospheric
8. Paint Plant Filtering Ambient Atmospheric
9. Paint Plant Packaging Ambient Atmospheric
The extent of these emissions varies with the type of operation and the
effort extended to control atmospheric losses. The high temperature thinning
and filtering result in the largest emissions while packaging in drums and cans
contributes the smallest emission. Other operations contribute intermediate
emissions which vary depending on the degree of control exercised and the
vapor pressure of the solvent used.
In some cases, efforts are made to collect fugitive emissions by use of
ventilation hoods and a closed exhaust system. More frequently, however, they
are exhausted from the building by general building exhaust fans which
ventilate areas having the highest contaminant concentration.
Resin plants or paint plants producing resins and varnishes are likely to
have a number of regulated emissions. These emissions consist primarily of
265
-------
gaseous hydrocarbons in air or inert gas streams. The three major sources of
these non-fugitive emissions are:
1. Varnish cooking
2. Resin cooking
3. Thinning
Other less concentrated streams that may or may not be regulated are:
1. Storage and rundown tank vent systems
2. Filter press vent systems
3. Sandmi 11 vent systems
Considerable effort has been expended to identify the various types of
chemical compounds emitted during a varnish cook. The majority of this work
was done in the 1950's and is well summarized by R. L. Stenburg'31 in the
H.E.W. Technical Report A58-4. A copy of his summary is included here as
Table 91.(3) In general, one or more of the following compounds are emitted,
depending upon the ingredients in the cook and the cooking temperature:
water vapor, fatty acids, glycerine, acrolein, phenols, aldehydes, ketones,
terpene oils and terpene. These materials are mainly decomposition products of
the varnish ingredients.
Varnishes and oils are cooked or boiled at temperatures from 200 to
650° F. At about 350° F decomposition begins and continues throughout the
cooking cycle which normally runs between 8 and 12 hours. The quantity,
composition and rate of emissions depend upon the ingredients in the cook as
well as the maximum temperature, the length, the method of introducing
additive, the degree of stirring and the use of inert gas blowing. In general, the
emissions will average between one to three percent of the charge in oil
bodying and three to six percent in varnish cooking. Aside from academic
interest, the exact chemical structure of these emissions is not too important.
Of more importance are the characteristics of the emissions related to ease of
removal by the applicable pollution control devices.
Modern resin reactors and varnish cookers account for the majority of
clear coatings production in the paint and varnish industry. As described
earlier, these products are cooked in larger more carefully controlled reactors
equipped with product recovery devices which also help reduce atmospheric
emission.
As with the old varnish kettles, the amount of emissions varies with the
type of cook, the cooking time, the maximum temperature, the initial
266
-------
TABLE 91
COMPOSITION OF OIL AND VARNISH FUMES'31
Bodying Oils
Water vapor
Fatty acids
Glycerine
Acrolein
Aldehydes
Ketones
Carbon dioxide
Running Natural
Gums
Water vapor
Fatty acids
Terpenes
Terpene Oils
Tar
Manufacturing
Oleo resinous
Varnish
Water vapor
Fatty acids
Glycerine
Acrolein
Phenols
Aldehydes
Ketones
Manufacturing
Alkyd Varnish
Water vapor
Fatty acids
Glycerine
Phthalic anhydride
Carbon dioxide
Terpene Oils
Terpenes
Carbon dioxide
267
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ingredients as well as the type and method of introducing ingredients.
For solvent cooking the quantity of emission does not vary significantly
with the size of the reactor but is rather more a function of the volatility of the
solvent being used and the size and/or efficiency of the condenser. Since there
is no sparge gas used in solvent cooking, exhaust volumes are small and consist
primarily of non-condensed solvent fumes. Emissions will run from 0.1 to 0.5
pounds per hour and will be less cyclic in nature than for fusion cooks.
Emissions during fusion cooking run much higher and vary with the size
of the reactor. The total exhaust volume is dependent primarily on the sparge
rate of inert gas. Dean H. Parker'4' indicated typical sparge rates of 0.04
ft3/min/gal of charge during the first hour, 0.02 ft3 during the second, and
0.01 ft3 during the remainder of the cook. The exhaust rate will average from 2
ft3/min/100 gallons of capacity on small reactors to 1 ft3/min/100 gallons of
capacity on large reactors. A summary of source test results from a variety of
resin reactors is presented in Table 92.<11'
Since fusion cooking is a cyclic batch process, the concentration of
emission will vary from the start to finish of the cook. Hydrocarbon
concentration will vary from 15,000 to 80,000 ppm as methane equivalent,
depending on the time of the cycle and the type of cook. There are at least 100
different emission curves that could be encountered if one tried to cover all of
the different cooking formulas. Particulate phthalic anhydride (PA) is also
emitted from the kettle and concentration levels vary depending on cycle time,
types of cook, method of charging and type of PA used. Charging of liquid PA
rather than dry solid PA significantly reduces the emission rate. However, if the
linear velocity of the sparge gas is maintained below 150 ft/min, the carry-over
of PA is also significantly reduced. Entrained and sublimed PA will run
between 1 to 3 pounds per hour over a period of 50 to 70 minutes during and
following the charging period. Plots of hydrocarbon emission level vs. time for
three of many possible cooks are given as Figures 70, 71 and 72.(10) These
emission concentrations are those measured directly out of a closed kettle or
reactor.
Figure 72 shows typical variations in emissions from one batch to another
when cooking the same product in the same kettle. Variations twice as great as
this are not uncommon. Emissions increase dramatically and rapidly as
indicated on Figures 70 and 71 whenever the loading hatches are opened. This
is a result of forced exhaust of the kettle to prevent spillage of fumes into the
room from the open hatch.
268
-------
TABLE 92
EMISSION DATA SUMMARY
Resin
Type
Alkyds
Polyester
Reactor
Size
(gal)
4,000
1,000
1,000
4,000
1,000
EMISSION:
RANGE
(Ib/hr)
0.07-1.45
0.17-0.75
0.44-1.74
1.32-27.3
0.35-2.23
EMISSION:
AVERAGE
(ib'/hr)
0.7
0.3
1.0
12.9
1.18
Average
Major Reaction
Component Temp. (°F.
Xylene 410-460
Xylene
Xylene
Propylene 400-410
Glycol
Propylene
Glycol
O)
CD
Acrylics,
Melamines 4,000
1,000
0.06-0.21 0.10 Butanol
0.15-0.16 0.15 Butanol
410-460 Solvent Cook, based upon 4 resins.
Solvent/fusion cook, based upon
7 resins.
Solvent cook, based upon 4 resins.
Emissions exceeded 8 pounds/hour
during second stage changing.
Fusion cook, based upon 4 resins.
Emissions exceeded 8 pounds/hour
during changing exotherm, and
sparging.
Fusion cook, based upon 8 resins.
220-250 Solvent cook, based upon 11 resins.
Solvent cook, based upon 2 resins.
-------
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O
z
UJ
I
0
u
a.
a.
0
Q.
Z
0
0
o:
<
0
0
o:
o
FIGURE 70
HYDROCARBON EMISSIOM FOR DOWTHE1RM KETTL-E Oo>
VAPOR TEMPERATURE RANGED FROM IOO*F *TO
KETTLE TEMPERATURE FROM SO~F TO ^OO* F
C.OOK RAN 20 HOURS
so coo
OREIMED MAISIHOL-EI
TO CHARGE PA
-4OOOO
3OOOO
^0000
IOOOO
OPEIMED
MANHOL.E:
TO
CHARGE
PE
TIME-HOURS
-------
I-
u
Q.
0
I
Q-
Q-
l
£
0
Q.
z
0
ID
o:
<
0
0
IT
Q
FIGURE 71
HYDROC.ARBOM EMISSION FOR PAINT KEITTLE Clo)
VAPOR TEMPERATURE: RANGED FROM ioo*» F TO 310° F
KETTLE TEMPERATURE FROM »O*F TO
so,ooo
-40,000
300OO
20,000
IOOOO
DROPPEZD BATCH
STARTED TO THIN IN
O
TIN/IE , HOURS
-------
NJ
-»J
ro
£_ SOOOO
h
z
LJ
i
D
0
y
1
I
0
*^_—
I
Q.
Q.
I
£
0
(L
z
0
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It
<
U
0
It
Q
FIGURE 72
KETTL-E HYDROC.ARBON EMISSON - 2 BATC.HES MONITORED ClO)
VAPOR TEMPERATURE RANGED FROM IOO*F TO 3IO"F
KETTLE TEMPERATURE RANGED UP TO -49O°F
-40000
SOOOO
2OOOO
IOOOO
(—OPEN M/A.NIHOL.E:
BATCH
BATCH 2. —^.-—
PUN/IP OUT
TIME - HOURS
-------
The storage of liquid PA will result in significant vaporization losses from
the storage tank and an effort must be made to control these losses. The most
widely used method consists of an inert gas blanketing in conjunction with a
pressure controlled unit. The tank is also equipped with a water cooled
condenser used to vent the tank during filling. After filling the condenser is
then heated with steam to remove collected PA by melting.
POLLUTION CONTROL CONSIDERATIONS
Collection of particulate pigment or resin emission is a simple
straightforward job. The only practical control device is a fabric filter, and it is
ideally suited for this application. Collection efficiency for the submicron
pigment dust (0.05 to 0.25 microns) is in the range of 99.9%. There are no
temperature problems since the exhaust system runs at ambient temperatures.
The grain loading is very low and baglife is extensive. Approximately 0.01% of
the loaded pigments are lost and collected. Grain loadings to the fabric filter
run around 0.19 grain/SCF. A typical collection system is shown in Figure 73.
The collection system can be a fixed hood which can handle both dust and
pigment bags or a flexible hose positioned above the loading hatch or attached
to the top of the tank. The tank attachment provides the most positive control
of fugitive dust emission but also increases pigment and solvent losses slightly.
The application of control equipment to this problem is quite simple and
can be solved with standard off-the-shelf equipment from a host of suppliers.
For this reason, detailed equipment cost and installation bids will not be
required.
The control of hydrocarbon and odors from the various emission sources
listed earlier is not quite as straightforward as the dust emission. There are
three types of control equipment that have been applied to this problem. They
are catalytic and thermal combustion devices, and wet scrubbers.
As a general rule, wet scrubbing does not provide a satisfactory solution
for the following reasons:
1. Removal efficiency of fine hydrocarbon aerosol is not good at
economically practical pressure drops.
2. Non-condensible hydrocarbon solvent vapors will not be removed.
3. Odor removal without the addition of an oxidizing agent such as
273
-------
FIGURE 73
NJ
PIGMENT EMISSION CONTROL. SYSTEM
ALTERNATE
METHOD USING
"LEXIBLE HOSE
JP
/
/— FIXED v
X STATIONS N^
X /
\
1
1
C
YCLONE
1
L FABRIC
FILTER
«
1
^
1
]
•
MEZZANINE
FLOOR
ft •
PE
K.
BE
1IL
/- LOADING v
/f H ATC H X
^— M-*
5LE
.L
«.NW>
» •
^Y — ^
ROLLER
MILL
m 4
HIGH SREED
MIXING TANK
RECOVERED RIGMENT
RECYCLE FOR DARK
PRIMER PAINTS
TO
SOLID WASTE
DISPOSAL
-------
potassium permanganate or sodium hypochorite is unsatisfactory. If
an oxidizing agent is used, operating cost will be quite high due to
the high concentration of other oxidizable material such as phthalic
anydride, resins and oil.
4. Mobile packing and high make-up water rates are required to prevent
plugging of the scrubber beds and spray nozzles.
5. Correction of the air pollution problem with wet scrubbing causes an
equivalent water pollution problem which in many areas is more
costly to correct than the original air pollution problem.
The only control technique currently being used that has proven effective
for all cases is combustion. Three general methods are employed to combust
waste gases:
1. Flame Combustion
2. Thermal Combustion
3. Catalytic Combustion
All of the above methods are oxidation processes. Ordinarily, each
requires that the gaseous effluents be heated to the point where oxidation of
the combustible will take place. The three methods differ basically in the
temperature to which the gas stream must be heated.
Flame combustion is the easiest of the three to understand, as it comes
the closest to everyday experience. When a gas stream is contaminated with
combustibles at a concentration approaching the lower flammable limit, it is
frequently practical to add a small amount of natural gas as an auxiliary fuel
and sufficient air for combustion when necessary, and then pass the resulting
mixture through a burner. The contaminants in the mixture serve as a part of
the fuel. Flame incinerators of this type are most often used for closed
chemical reactors. They are not used on resin reactors at present. They may be
an ideal solution some day, however, when methods of operating a closed,
pressurized resin reactor are developed.
It is far more likely that the concentration of combustible contaminants
in an air stream will be well below the lower limit of flammability. When this is
the case, direct thermal combustion is considerably more economical than
flame combustion. Direct thermal combustion is carried out by equipment such
as that illustrated in Figure 74. In this equipment, a gas burner is used to raise
the temperature of the flowing stream sufficiently to cause a slow thermal
reaction to occur in a residence chamber.
275
-------
FIGURE 74
THERMAL COMBUSTION SYSTEM
FOR
RESIN REACTOR OR CLOSED KETTLE
HIGH-VELOCITY
VENTURI
SECTION
HEAT EXCHANGER
(OPTIONAL)
FUEL
GAS
NJ
COMBUSTION
DEVICE-^
(hd
MINIMUM FLOW DAMPER
MANUAL CONTROL
PRESS HOOD
TEMPERATURE INDICATOR ALARM HIGH
TEMPERATURE INDICATOR CONTROLLER
-DIVERSION
STACK
FROM
REACTOR
FROM
THINNING TANK
-------
Whereas flame temperatures bring about oxidation by free radical
mechanisms at temperatures of 2500° F and higher, thermal combustion of
.ordinary hydrocarbon compounds begins to take place at temperatures as low
as 900 to 1000° F. Good conversion efficiencies are produced at temperatures
in the order of 1400° F with a residence time of 0.3 to 0.6 seconds.
Catalytic combustion is carried out by bringing the gas stream into
intimate contact with a bed of catalyst. In this sytem, the reaction takes place
directly upon the surface of the catalyst, which is usually composed of precious
metals, such as platinum and palladium. While thermal combustion equipment
brings about oxidation at concentrations below the limits of flame combustion,
catalytic combustion takes place below the limits of flammability and below
the normal oxidation temperatures of the contaminants. The reaction is
instantaneous by comparison to thermal combustion and no residence chamber
is required. Catalytic combustion is carried out by equipment such as that
illustrated in Figure 75.
In general, catalytic afterburners are less expensive to operate. However,
they depend directly on the performance of the catalyst for their effectiveness.
They will not function properly if the catalyst becomes deactivated. Because of
this, catalytic units are not inherently functional when operated at design
conditions. In many areas, means for ensuring adequate performance of the
catalyst on a long term basis will be required by environmental control offices.
The basis for design of either catalytic or thermal combustion is the
hydrocarbon concentration of the exhaust gases handled by the incinerator.
The maximum hydrocarbon level is set by most insurance companies at
one-quarter of the lower explosive limit (LED which is equivalent to 13
Btu/SCF of exhaust gas. As outlined earlier, the quantity of emission may vary
significantly with cooking time and the type of cook. There is also likely to be
a very large variety of different hydrocarbons emitted. For this reason,
theoretical calculations of emission for design purposes are not satisfactory. On
site emission measurements, as shown earlier on Figures 70 and 71, are
required. Once the rate of emission is determined, it is then necessary to
calculate the dilution air required to meet 1/4 LEL and set up the duct work
system to provide for this dilution. When possible, dilution air should be
utilized to help capture as many fugitive fume emissions as possible. For
example this can be accomplished by taking the dilution air from a hood
positioned over the resin filter press and venting the thinning tanks and product
run down tanks into the same system.
A concentration of 1/4 LEL or 13 Btu/SCF will give a temperature rise of
277
-------
FIGURE 75
NJ
^1
00
SCHEMATIC DIAGRAM OF A CATALYTIC
COMBUSTION SYSTEM FOR VARNISH KETTLES
STACK
DISCHARGE
HIGH-LOW
LIK/1IT
CONTROLLER
SENSING
T/C'S
BURNER
CONTROLLER
CONTROL
CABINET
INSULATED —I
DOUBLE /
MANIFOLD 1
RECYCLING
DAMPER
ALARM
CATALYST
PREHEAT
BURNER
COOKI NG
STATIONS
-------
about 600° F in the afterburner. This is too high if a heat exchanger is to be
used, and in these cases, dilution will be required to a maximum concentration
of 12 Btu/SCF. In all cases, the heat exchangers will be the parallel flow type
having a thermal efficiency of 42%. This is required to assure temperature
balance and control, due to the high emission concentration.
The major problem with catalytic or thermal afterburners as applied to
open or closed resin and varnish kettles is the danger of fires and/or explosions.
This has happened in numerous occasions in the past due primarily to excessive
hydrocarbon emission from kettles. These problems have been all but
eliminated on newer units by assuring that the design was based on actual
emission measurements of the highest emitting cook and the addition of some
of the following system safety features:
1. High limit temperature alarm to shut off burner and activate a
diversion system.
2. High velocity duct section to assure gas flow to afterburner
substantially exceeds flame propogation velocity of hydrocarbons
being burned.
3. Double manifolding or hot gas recycle to prevent condensation of
heavy hydrocarbons or phthalic anhydride.
4. Diversion system to block off hydrocarbon emissions to unit,
by-passing them directly out of separate exhaust, and introduce fresh
air to purge the unit.
5. Pneumatic operation of the diversion system to assure fast positive
action and provide a fail safe system in the event of either air or
electrical failure.
6. Purging with inert gas in the event of power failure.
The above general requirements are applicable to all types of afterburner
control. Specific details for each type of system will be given in the equipment
specifications.
279
-------
280
-------
SPECIFICATIONS AND COSTS
Specifications were written for combustion systems applied to two
sources typical of those in the paint and varnish industry: closed resin reactors
and open cooking kettles. Each of these sources emits primarily hydrocarbons.
Both thermal and catalytic combustion systems were specified for abatement in
each application. For those applications where the gas flow was sufficient,
separate, but parallel, specifications were written for combustion systems with
and without heat exchange. Separate specifications and cost tables are
presented for each application.
For the graphical presentation of cost data, however, sets of similar data
were grouped together rather than showing one set of cost graphs for each
application. This grouping permits the presentation of cost graphs covering a
wider range of combustion system sizes. Operating cost curves for similar
thermal and catalytic systems are presented on the same figure for comparison
purposes. The data were grouped and presented as follows:
System Capital Cost Operating Cost
Type Figure Figure
Thermal, without heat exchange 26 28,29
Catalytic, without heat exchange 27 28,29
Thermal, with heat exchange 30 32, 33
Catalytic, with heat exchange 31 32,33
In addition to the cost data gathered under this contract, similar cost data
gathered at the same time under contract No. 68-02-0259, Air Pollution
Control Engineering and Cost Study of the Paint and Varnish Industry, are also
presented on these figures. These additional data are not included in the
average cost tables.
281
-------
TABLE 93
THERMAL INCINERATOR PROCESS DESCRIPTION
FOR RESIN REACTOR SPECIFICATION
This specification describes the requirements for a thermal combustion system for
abatement of the hydrocarbon emissions from the resin production facility of a paint and
varnish plant. The system will be similar to that shown in Figure 24. All reactor thinning
tanks and product rundown tanks will be vented to the collection system. Dilution air will
be supplied through a hood over the resin filter press(es). A minimum flow damper is to be
supplied in this part of the ventilation system. It is to be sized to allow for a maximum fume
concentration of 40% LEL in the fully closed position. A high velocity Venturi section is to
be located at the incinerator inlet to assure gas flow is in excess of flame propagation
velocity at 1/2 design flow rate.
The afterburner is to be natural gas fired. Sufficient gas, having a specific gravity of
0.60 and an upper heating value of 1040 Btu/SCF, is available at pressure of 1.0 psig.
The exhaust gas contains sufficient oxygen, greater than 16% 0£/ to allow firing of the
afterburner with a raw gas or process air burner. A combustion air system is not required.
Fume load to the incinerator is composed of 75% kettle emission and 25% from other
sources. Average emissions are 60% of peak. The system is to be designed on peak emission
but operating costs are to be based on average emissions. Operating conditions listed are
based on peak emissions. Fume destruction in burner is to be calculated as follows:
10% for catalytic units with or without heat exchange
10% for thermal units with heat exchange
20% for thermal units without heat exchange.
Please fill in estimated efficiency of afterburner and burner duty.
The afterburner is to be supplied with a suitable control panel and all equipment is to
be designed for outdoor operation. Incinerator operating and safety controls are to be
designed to meet F.I.A. (Factory Insurance Association) requirements. All dampers are to be
pneumatically operated and contain an integral fail-safe air reservoir. The system is to
automatically divert in the event of low flow, high afterburner temperature, high reactor
pressure, and afterburner preheat burner failure. The exhaust system should also be purged
with inert gas on fan failure or loss of flow. Damper operating is to be sequential with the
position switches mounted on the damper arm and not the operator. The system fan shall be
located after the preheat burner or the incinerator outlet and shall be constructed to
withstand 200°F higher than design operating temperature. The fan shall have a V-belt drive
and fan and motor shall have the capacity to overcome the pressure drop of the ductwork,
afterburner and any heat exchanger that may be used. System ductwork should be sized for
a maximum A P of 2 in. w.c. hot. The fan motor may be sized for restricted flow cold start.
The ductwork to the incinerator should be heated either by the use of a double manifold or
hot gas recycle or a combination of both.
282
-------
INSTALLATION
A complete turnkey proposal including ductwork, structural steel, fuel and inert gas
piping, etc., is requested. For the purpose of this proposal fan and damper including
operators are to be considered as auxiliary. The controls and control cabinet are to be
included with the afterburner price. The afterburner will be assumed to be located on a
structural steel base on the resin plant roof. No modification to the building structural steel
is required. A tie through the roof from the base to the building steel is required. The base
and tie-in are part of the installed structural cost. All utilities are available within 30 ft of the
control cabinet, motor, and burner. Plant air is available at 100 psig and located within 30 ft.
Inert gas is available and will require 30 ft of piping from supply to ductwork. The existing
stack can be used for the diversion stack. A 10 ft exhaust stack will be mounted on the
incinerator, double manifold or exhaust fan. A total of thirty-five (35) feet of new exhaust
ductwork and twenty-five (25) feet of double manifold will be required.
283
-------
284
-------
TABLE 94
THERMAL INCINERATOR OPERATING CONDITIONS
FOR RESIN REACTOR SPECIFICATION
(WITHOUT HEAT EXCHANGE)
Process Conditions
Small
Large
Reactors, Number
Size each, gal
Hcbn Emission Max, Ib/hr
Hcbn Emission Ave, Ib/hr
Total Exhaust Rate, SCFM
Exhaust Temperature, °F
Heat of Combustion of
Reactor Fume, Btu/lb
Hydrocarbon Concentration
Maximum, Btu/SCF
Average, Btu/SCF
1
4,000
95
57
3,000
110
17,000
12
7
3
5,000
317
190
10,000
110
17,000
12
7
Incinerator Without Heat Exchange
Unit Inlet 325
Burner AT" from Fuel Gas, °F 550
*Burner A T from Flame Combustion, °F 125
Burner Outlet Temperature, °F 1,000
* *Unit A T from Thermal Combustion, °F 435
Unit Outlet Temperature, °F 1,435
* * * Burner Duty, MM Btu/hr 3.36
325
550
125
1,000
435
1,435
11.19
* Assumes 20% fume combustion in burner flame
** Assumes 95% overall fume combustion
*** ,
Supplied by bidders
285
-------
TABLE 95
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR THERMAL INCINERATORS FOR RESIN REACTORS
(WITHOUT HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
Ib/hr, Max
Ib/hr, Avg
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
Small
Large
High Efficiency
Small
3,225
110
3,000
4.3
95
57
10,840
1,435
3,036
9.2
4.8
95
14,806
1,636
1,085
1,800
1,913
2,600
850
600
510
900
400
1,500
28,600
Large
10,750
110
10,000
4.3
317
190
36,130
1,435
10,120
9.2
16
95
27,071
4,655
1,405
2,650
2,725
4,150
1,750
1,100
720
900
400
1,500
49,026
286
-------
TABLE 96
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR THERMAL INCINERATORS FOR RESIN REACTORS
(WITHOUT HEAT EXCHANGE)
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
8,760
$6/hr
$6/hr
;.011/kw-hr
1.80/MM Btu
Small
Large
High Efficiency
Small
375
_
375
390
160
550
375
2,024
20,784
22,808
24,108
2,860
26,968
Large
375
_
375
390
210
600
475
5,059
69,026
74,085
75,535
4,903
80,438
N)
00
-------
TABLE 97
THERMAL INCINERATOR PROCESS DESCRIPTION
FOR OPEN KETTLE SPECIFICATION
This specification describes the requirements for a thermal combustion system for
abatement of the hydrocarbon emissions from the resin production facility of a paint and
varnish plant. The system will be similar to that shown in Figure 24. All reactor thinning
tanks and product rundown tanks will be vented to the collection system. Dilution air will
be supplied through a hood over the resin filter press(es). A minimum flow damper is to be
supplied in this part of the ventilation system. It is to be sized to allow for a maximum fume
concentration of 40% LEL in the fully closed position. A high velocity Venturi section is to
be located at the incinerator inlet to assure gas flow is in excess of flame propagation
velocity at 1/2 design flow rate.
The afterburner is to be natural gas fired. Sufficient gas, having a specific gravity of
0.60 and an upper heating value of 1040 Btu/SCF, is available at pressure of 1.0 psig.
The exhaust gas contains sufficient oxygen, greater than 16% 0^ to allow firing of the
afterburner with a raw gas or process air burner. A combustion air system is not required.
Fume load to the incinerator is composed of 75% kettle emission and 25% from other
sources. Average emissions are 60% of peak. The system is to be designed on peak emission
but operating costs are to be based on average emissions. Operating conditions listed are
based on peak emissions. Fume destruction in burner is to be calculated as follows:
10% for catalytic units with or without heat exchange
10% for thermal units with heat exchange
20% for thermal units without heat exchange.
Please fill in estimated efficiency of afterburner and burner duty.
The afterburner is to be supplied with a suitable control panel and all equipment is to
be designed for outdoor operation. Incinerator operating and safety controls are to be
designed to meet F.I.A. (Factory Insurance Association) requirements. All dampers are to be
pneumatically operated and contain an integral fail-safe air reservoir. The system is to
automatically divert in the event of low flow, high afterburner temperature, high reactor
pressure, and afterburner preheat burner failure. The exhaust system should also be purged
with inert gas on fan failure or loss of flow. Damper operating is to be sequential with the
position switches mounted on the damper arm and not the operator. The system fan shall be
located after the preheat burner or the incinerator outlet and shall be constructed to
withstand 200°F higher than design operating temperature. The fan shall have a V-belt drive
and fan and motor shall have the capacity to overcome the pressure drop of the ductwork,
afterburner and any heat exchanger that may be used. System ductwork should be sized for
a maximum A P of 2 in. w.c. hot. The fan motor may be sized for restricted flow cold start.
The ductwork to the incinerator should be heated either by the use of a double manifold or
hot gas recycle or a combination of both.
288
-------
INSTALLATION
A complete turnkey proposal including ductwork, structural steel, fuel and inert gas
piping, etc., is requested. For the purpose of this proposal fan and damper including
operators are to be considered as auxiliary. The controls and control cabinet are to be
included with the afterburner price. The afterburner will be assumed to be located on a
structural steel base on the resin plant roof. No modification to the building structural steel
is required. A tie through the roof from the base to the building steel is required. The base
and tie-in are part of the installed structural cost. All utilities are available within 30 ft of the
control cabinet, motor, and burner. Plant air is available at lOOpsig and located within 30 ft.
Inert gas is available and will require 30 ft of piping from supply to ductwork. The existing
stack can be used for the diversion stack. A 10 ft exhaust stack will be mounted on the
incinerator, double manifold or exhaust fan. A total of thirty-five (35) feet of new exhaust
ductwork and twenty-five (25) feet of double manifold will be required.
289
-------
290
-------
TABLE 98
THERMAL INCINERATOR OPERATING CONDITIONS
FOR OPEN KETTLE SPECIFICATION
(WITHOUT HEAT EXCHANGE)
Small Large
Process Conditions
Kettles, Number 1 3
Size each, gal 200 375
Hcbn Emission Max, Ib/hr 16.8 101.1
Hcbn Emission A ve, Ib/hr 10.1 60.6
Total Exhaust Rate, SCFM 500 3,000
Exhaust Temperature, °F 80 80
Heat of Combustion of
Kettle Fume, Btu/lb 16,000 16,000
Hydrocarbon Concentration
Maximum, Btu/SCF 12 12
Average, Btu/SCF 7 7
Incinerator Without Heat Exchange
Unit Inlet 300 300
Burner A 7from Fuel Gas, °F 575 575
*Burner A T from Flame Combustion, °F 125 125
Burner Outlet Temperature, °F 1,000 1,000
**Unit AT" from Thermal Combustion, °F 435 435
Unit Outlet Temperature, °F 1,435 1,435
* * * Burner Duty, MM Btu/hr 0.58 3.43
Assumes 20% fume combustion in burner flame
** Assumes 95% overall fume combustion
***,
f Supplied by bidders
291
-------
TABLE 99
ESTIMATED CAPITAL COST DATA {COSTS IN DOLLARS)
FOR THERMAL INCINERATORS FOR OPEN KETTLES
(WITHOUT HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
Ib/hr, Max
Ib/hr, Avg
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
Small
Large
High Efficiency
Small
509
80
500
1.7
16.8
10.1
1,810
1,435
506
6.7
8.4
95
12,081
720
923
1,650
1,650
2,360
750
550
470
800
350
1,150
23,454
Large
3,056
80
3,000
1.7
101.1
60.6
10,860
1,435
3,036
6.7
50.5
95
14,806
1,636
1,085
1,913
1,913
3,025
850
600
510
900
350
1,250
28,838
292
-------
TABLE 100
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR THERMAL INCINERATORS FOR OPEN KETTLES
(WITHOUT HEAT EXCHANGE)
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
8,760
$6/hr
$6/hr
;.011/kw-hr
1.80/MMBtu
Small
Large
High Efficiency
Small
.375
375
390
110
500
325
482
3,554
4,036
5,236
2,345
7,581
Large
375
375
390
160
550
375
2,024
21,003
23,027
24,327
2,884
27,211
CO
CO
-------
TABLE 101
CATALYTIC INCINERATOR PROCESS DSCRIPTION
FOR RESIN REACTOR SPECIFICATION
This specification describes the requirements for a catalytic combustion system for
abatement of the hydrocarbon emissions from the resin production facility of a paint and
varnish plant. The system will be similar to that shown in Figure 24. All reactor thinning
tanks and product rundown tanks will be vented to the collection system. Dilution air will
be supplied through a hood over the resin filter press(es). A minimum flow damper is to be
supplied in this pan of the ventilation system. It is to be sized to allow for a maximum fume
concentration of 40% LEL in the fully closed position. A high velocity Venturi section is to
be located at the incinerator inlet to assure gas flow is in excess of flame propagation
velocity at 1/2 design flow rate.
The afterburner is to be natural gas fired. Sufficient gas, having a specific gravity of
0.60 and an upper heating value of 1040 Btu/SCF, is available at pressure of I.Opsig.
The exhaust gas contains sufficient oxygen, greater than 16% 02, to allow firing of the
afterburner with a raw gas or process air burner. A combustion air system is not required.
Fume load to the incinerator is composed of 75% kettle emission and 25% from other
sources. Average emissions are 60% of peak. The system is to be designed on peak emission
but operating costs are to be based on average emissions. Operating conditions listed are
based on peak emissions. Fume destruction in burner is to be calculated as follows:
10% for catalytic units with or without heat exchange
10% for thermal units with heat exchange
20% for thermal units without heat exchange.
Please fill in estimated efficiency of afterburner, burner duty, catalyst face velocity,
and catalyst volume.
The afterburner is to be supplied with a suitable control panel and all equipment is to
be designed for outdoor operation. Incinerator operating and safety controls are to be
designed to meet F.I.A. (Factory Insurance Association) requirements. All dampers are to be
pneumatically operated and contain an integral fail-safe air reservoir. The system is to
automatically divert in the event of low flow, high afterburner temperature, high reactor
pressure, and afterburner preheat burner failure. The exhaust system should also be purged
with inert gas on fan failure or loss of flow. Damper operating is to be sequential with the
position switches mounted on the damper arm and not the operator. The system fan shall be
located after the preheat burner or the incinerator outlet and shall be constructed to
withstand 200°F higher than design operating temperature. The fan shall have a V-belt drive
and fan and motor shall have the capacity to overcome the pressure drop of the ductwork,
afterburner and any heat exchanger that may be used. System ductwork should be sized for
a maximum A P of 2 in. w.c. hot. The fan motor may be sized for restricted flow cold start.
The ductwork to the incinerator should be heated either by the use of a double manifold or
a combination of both.
294
-------
INSTALLATION
A complete turnkey proposal including ductwork, structural steel, fuel and inert gas
piping, etc., is requested. For the purpose of this proposal fan and damper Including
operators are to be considered as auxiliary. The controls and control cabinet are to be
included with the afterburner price. The afterburner will be assumed to be located on a
structural steel base on the resin plant roof. No modification to the building structural steel
is required. A tie through the roof from the base to the building steel is required. The base
and tie-in are part of the installed structural cost. All utilities are available within 30 ft of the
control cabinet, motor, and burner. Plant air is available at WOpsig and located within 30 ft.
Inert gas is available and will require 30 ft of piping from supply to ductwork. The existing
stack can be used for the diversion stack. A 10 ft exhaust stack will be mounted on the
incinerator, double manifold or exhaust fan. A total of thirty-five (35) feet of new exhaust
ductwork and twenty-five (25) feet of double manifold will be required.
295
-------
296
-------
TABLE 102
CATALYTIC INCINERATOR OPERATING CONDITIONS
FOR RESIN REACTOR SPECIFICATION
(WITHOUT HEAT EXCHANGE)
Small
Large
Process Conditions
Reactors, Number
Size each, gal
Hcbn Emission Max, Ib/hr
Hcbn Emission Ave, Ib/hr
Total Exhaust Rate, SCFM
Exhaust Temperature, °F
Heat of Combustion of
Reactor Fume, Btu/lb
Hydrocarbon Concentration
Maximum, Btu/SCF
Average, Btu/SCF
1
4,000
95
57
3,000
110
17,000
12
7
3
5,000
317
190
10,000
110
17,000
12
7
Incinerator Without Heat Exchange
Unit Inlet
Burner hTfrom Fuel Gas, °F
* Burner AT from Flame Combustion, °F
Burner Outlet Temperature, °F
**Unit AT" from Thermal Combustion, °F
Unit Outlet Temperature, °F
Burner Duty, MM Btu/hr
300
240
60
600
500
1,100
300
240
60
600
500
1,100
* Assumes 10% fume combustion in burner flame
** Assumes 95% overall fume combustion
297
-------
TABLE 103
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR CATALYTIC INCINERATORS FOR RESIN REACTORS
(WITHOUT HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
Ib/hr, Max
Ib/hr, Avg
Cleaned Gas Flow
ACFM
°F
SCFM
Cleaned Gas Contaminant Loading
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other ^
>
(4) Total Cost
Small
Large
High Efficiency
Small
3,225
110
3,000
4.3
95
57
8,880
1,100
3,015
4.8
95
22,988
3,990
11,386
38,364
Large
10,750
110
10,000
4.3
317
190
29,600
1,100
1,000
15.9
95
43,260
8,515
18,123
69,898
298
-------
TABLE 104
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR CATALYTIC INCINERATORS FOR RESIN REACTORS
(WITHOUT HEAT EXCHANGE)
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
8,760
$6/hr
$8/hr
$6/hr
I.Oll/kw-hr
1.80/MMBtu
Small
Large
High Efficiency
Small
675
200
875
510
115
625
1,265
1,118
9,251
10,369
13,134
3,836
16,970
Large
675
200
875
510
145
655
4,045
3,239
30,835
34,074
39,649
6,990
46,639
NJ
CO
CO
-------
TABLE 105
CATALYTIC INCINERATOR PROCESS DESCRIPTION
FOR OPEN KETTLE SPECIFICATION
This specification describes the requirements for a catalytic combustion system for
abatement of the hydrocarbon emissions from the resin production facility of a paint and
varnish plant. The system will be similar to that shown in Figure 24. All reactor thinning
tanks and product rundown tanks will be vented to the collection system. Dilution air will
be supplied through a hood over the resin filter press(es). A minimum flow damper is to be
supplied in this part of the ventilation system. It is to be sized to allow for a maximum fume
concentration of 40% LEL in the fully closed position. A high velocity Venturi section is to
be located at the incinerator inlet to assure gas flow is in excess of flame propagation
velocity at 1/2 design flow rate.
The afterburner is to be natural gas fired. Sufficient gas, having a specific gravity of
0.60 and an upper heating value of 1040 Btu/SCF, is available at pressure of 1.0psig.
The exhaust gas contains sufficient oxygen, greater than 16% Oy, to allow firing of the
afterburner with a raw gas or process air burner. A combustion air system is not required.
Fume load to the incinerator is composed of 75% kettle emission and 25% from other
sources. Average emissions are 60% of peak. The system is to be designed on peak emission
but operating costs are to be based on average emissions. Operating conditions listed are
based on peak emissions. Fume destruction in burner is to be calculated as follows:
for catalytic units with or without heat exchange
10% for thermal units with heat exchange
20% for thermal units without heat exchange.
Please fill in estimated efficiency of afterburner, burner duty, catalyst face velocity,
and catalyst volume.
The afterburner is to be supplied with a suitable control panel and all equipment is to
be designed for outdoor operation. Incinerator operating and safety controls are to be
designed to meet F.I.A. (Factory Insurance Association) requirements. All dampers are to be
pneumatically operated and contain an integral fail-safe air reservoir. The system is to
automatically divert in the event of low flow, high afterburner temperature, high reactor
pressure, and afterburner preheat burner failure. The exhaust system should also be purged
with inert gas on fan failure or loss of flow. Damper operating is to be sequential with the
position switches mounted on the damper arm and not the operator. The system fan shall be
located after the preheat burner or the incinerator outlet and shall be constructed to
withstand 200°F higher than design operating temperature. The fan shall have a V-belt drive
and fan and motor shall have the capacity to overcome the pressure drop of the ductwork,
afterburner and any heat exchanger that may be used. System ductwork should be sized for
a maximum A P of 2 in. w.c. hot. The fan motor may be sized for restricted flow cold start.
The ductwork to the incinerator should be heated either by the use of a double manifold or
hot gas recycle or a combination of both.
300
-------
INSTALLATION
A complete turnkey proposal including ductwork, structural steel, fuel and inert gas
piping, etc., is requested. For the purpose of this proposal fan and damper including
operators are to be considered as auxiliary. The controls and control cabinet are to be
included with the afterburner price. The afterburner will be assumed to be located on a
structural steel base on the resin plant roof. No modification to the building structural steel
is required. A tie through the roof from the base to the building steel is required. The base
and tie-in are part of the installed structural cost. All utilities are available within 30 ft of the
control cabinet, motor, and burner. Plant air is available at 100 psig and located within 30 ft.
Inert gas is available and will require 30 ft of piping from supply to ductwork. The existing
stack can be used for the diversion stack. A 10 ft exhaust stack will be mounted on the
incinerator, double manifold or exhaust fan. A total of thirty-five (35) feet of new exhaust
ductwork and twenty-five (25) feet of double manifold will be required.
301
-------
302
-------
TABLE 106
CATALYTIC INCINERATOR OPERATING CONDITIONS
FOR OPEN KETTLE SPECIFICATION
(WITHOUT HEAT EXCHANGE)
Small Large
Process Conditions
Kettles Number 1 3
Size each, gal 200 375
Hcbn Emission Max, Ib/hr 16.8 101.1
Hcbn Emission Ave, Ib/hr 10.1 60.6
Total Exhaust Rate, SCFM 500 3,000
Exhaust Temperature, °F 80 80
Heat of Combustion of
Kettle Fume, Btu/lb 16,000 16,000
Hydrocarbon Concentration
Maximum, Btu/SCF 12 12
Average, Btu/SCF 7 7
Incinerator Without Heat Exchange
Unit Inlet 280 280
Burner kTfrom Fuel Gas, °F 260 260
*Burner AT" from Flame Combustion, °F 60 60
Burner Outlet Temperature,0 F 600 600
**Unit [\T from Thermal Combustion, °F 500 500
Unit Outlet Temperature, °F 1,100 1,100
Burner Duty, MM Btu/hr
* Assumes 10% fume combustion in burner flame
* Assumes 95% overall fume combustion
303
-------
TABLE 107
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR CATALYTIC INCINERATORS FOR OPEN KETTLES
(WITHOUT HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
Ib/hr, Max
Ib/hr, Avg
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
Ib/hr
Cleaning Efficiency, %
( 1 ) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s) 1
(b) Pump(s)
(c) Damper(s)
(d) Conditioning, >
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
>
(4) Total Cost
Small
Large
High Efficiency
Small
509
80
500
1.7
16.8
10.1
1,480
1,100
503
5.4
0.8
95
11,974
2,218
9,003
23,195
Large
3,056
80
3,000
1.7
101.1
60.6
8,880
1,100
3,018
5.4
5.0
95
22,988
3,990
11,773
38,751
304
-------
TABLE 108
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR CATALYTIC INCINERATORS FOR OPEN KETTLES
(WITHOUT HEAT EXCHANGE)
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
8,760
$6/hr
$8/hr
$6/hr
:.011/kw-hr
;.80/MM Btu
Small
Large
High Efficiency
Small
675
200
875
510
85
595
300
253
1,752
2,005
3,775
2,320
6,095
Large
675
200
875
510
110
620
1,265
1,118
10,232
11,350
14,110
3,875
17,985
CO
o
Ol
-------
FIGURE 76
CAPITAL COSTS FOR THERMAL INCINERATORS
FOR THE PAINT AND VARNISH INDUSTRY
(WITHOUT HEAT EXCHANGE)
500000
100000
CO
cc
3
o
Q
te
o
o
Q.
<
o
10000
TURNKEY SYSTEM
COLLECTOR PLUS
AUXILIARIES
1000
100
COLLECTOR ONLY
UBASED ON DATA FROM EPA CONTRACT NO. 68-02-0289
ABASED ON DATA FROM EPA CONTRACT NO. 68-02-0259
1000
GAS FLOW, SCFM
10000
30000
306
-------
FIGURE 77
CAPITAL COSTS FOR CATALYTIC INCINERATORS
FOR THE PAINT AND VARNISH INDUSTRY
(WITHOUT HEAT EXCHANGE)
500000
100QOO
c/j
QC
o
Q
te
8
t
Q.
<
u
10000
1000
COLLECTOR PLUS
AUXILIARIES
r i
COLLECTOR ONLY
TURNKEY SYSTEM
BASED ON DATA FROM EPA CONTRACT NO. 68-02-0289
BASED ON DATA FROM EPA CONTRACT NO. 68-02-0259
100
1000
GAS FLOW, SCFM
10000
30000
307
-------
FIGURE 78
DIRECT ANNUAL COSTS FOR THERMAL AND CATALYTIC INCINERATORS
FOR THE PAINT AND VARNISH INDUSTRY
(WITHOUT HEAT EXCHANGE)
500000
C/3
DC
o
Q
o
O
Z
100000
10000
1000
TLJ cf
~~ CATAL
3MAL
YTIC
^
,
>
X
s
/
j*
f
/
f
4
r
X
.
r
s
i
/
4
*
r >
S'
.S
/
0. 68-02-0289
O. 68-02-0259
100 1000 10000 3000G
GAS FLOW, SCFM
308
-------
FIGURE 79
TOTAL ANNUAL COSTS FOR THERMAL AND CATALYTIC INCINERATORS
FOR THE PAINT AND VARNISH INDUSTRY
(WITHOUT HEAT EXCHANGE)
500000
100000
V)
DC
o
o
00
O
U
D
Z
10000
1000
THERMAL
I I I
CATALYTIC
jl
A,
BASED ON DATA FROM EPA CONTRACT NO. 68-02-0289
'BASED ON DATA FROM EPA CONTRACT NO. 68-02-0259
1000
GAS FLOW, SCFM
10000
30000
309
-------
TABLE 109
THERMAL INCINERATOR PROCESS DESCRIPTION
FOR RESIN REACTOR SPECIFICATION
This specification describes the requirements for a thermal combustion system for
abatement of the hydrocarbon emissions from the resin production facility of a paint and
varnish plant. The system will be similar to that shown in Figure 24. All reactor thinning
tanks and product rundown tanks will be vented to the collection system. Dilution air will
be supplied through a hood over the resin filter press(es). A minimum flow damper is to be
supplied in this part of the ventilation system. It is to be sized to allow for a maximum fume
concentration of 40% LEL in the fully closed position. A high velocity Venturi section is to
be located at the incinerator inlet to assure gas flow is in excess of flame propagation
velocity at 1/2 design flow rate.
The afterburner is to be natural gas fired. Sufficient gas, having a specific gravity of
0.60 and an upper heating value of 1040 Btu/SCF, is available at pressure of 1.0 psig.
The exhaust gas contains sufficient oxygen, greater than 16% 0^ to allow firing of the
afterburner with a raw gas or process air burner. A combustion air system is not required.
Fume load to the incinerator is composed of 75% kettle emission and 25% from other
sources. Average emissions are 60% of peak. The system is to be designed on peak emission
but operating costs are to be based on average emissions. Operating conditions listed are
based on peak emissions. Fume destruction in burner is to be calculated as follows:
10% for catalytic units with or without heat exchange
10% for thermal units with heat exchange
20% for thermal units without heat exchange.
Please fill in estimated efficiency, of afterburner, burner duty, heat exchanger duty,
thermal efficiency, overall heat transfer coefficient (U), and tube surface area.
The afterburner is to be supplied with a suitable control panel and all equipment is to
be designed for outdoor operation. Incinerator operating and safety controls are to be
designed to meet F.I.A. (Factory Insurance Association) requirements. All dampers are to be
pneumatically operated and contain an integral fail-safe air reservoir. The system is to
automatically divert in the event of low flow, high afterburner temperature, high reactor
pressure, and afterburner preheat burner failure. The exhaust system should also be purged
with inert gas on fan failure or loss of flow. Damper operating is to be sequential with the
position switches mounted on the damper arm and not the operator. The system fan shall be
located after the preheat burner or the incinerator outlet and shall be constructed to
withstand 200°F higher than design operating temperature. The fan shall have a V-belt drive
and fan and motor shall have the capacity to overcome the pressure drop of the ductwork,
afterburner and any heat exchanger that may be used. System ductwork should be sized for
a maximum A P of 2 in. w.c. hot. The fan motor may be sized for restricted flow cold start.
The ductwork to the incinerator should be heated either by the use of a double manifold or
hot gas recycle or a combination of both.
310
-------
The heat exchanger is to be the parallel flow shell and tube type and designed to
operate at an afterburner outlet temperature of 1500°F. Maximum exchanger pressure drop,
both sides, should not exceed a total of 6 in. w.c. hot. Dirty gas is to flow through the tube
side.
INSTALLATION
A complete turnkey proposal including ductwork, structural steel, fuel and inert gas
piping, etc., is requested. For the purpose of this proposal fan and damper including
operators are to be considered as auxiliary. The controls and control cabinet are to be
included with the afterburner price. The afterburner will be assumed to be located on a
structural steel base on the resin plant roof. No modification to the building structural steel
is required. A tie through the roof from the base to the building steel is required. The base
and tie-in are part of the installed structural cost. All utilities are available within 30 ft of the
control cabinet, motor, and burner. Plant air is available at WOpsig and located within 30 ft.
Inert gas is available and will require 30 ft of piping from supply to ductwork. The existing
stack can be used for the diversion stack. A 10 ft exhaust stack will be mounted on the
incinerator, double manifold or exhaust fan. A total of thirty-five (35) feet of new exhaust
ductwork and twenty-five (25) feet of double manifold will be required.
311
-------
312
-------
TABLE 110
THERMAL INCINERATOR OPERATING CONDITIONS
FOR RESIN REACTOR SPECIFICATION
(WITH HEAT EXCHANGE)
Process Conditions
Small
Reactors, Number
Size each, gal
Hcbn Emission Max, Ib/hr
Hcbn Emission Ave, Ib/hr
Total Exhaust Rate, SCFM
Exhaust Temperature, °F
Heat of Combustion of
Reactor Fume, Btu/lb
Hydrocarbon Concentration
Maximum Btu/SCF
Average Btu/SCF
Residence Time, sec 1500°F
Incinerator with Heat Exchange
Inlet Tube Side, °F
Unit Inlet, °F
Burner AT" from Fuel Gas, °F
* Burner AT"'from Flame Combustion, °F
Burner Outlet Temperature, °F
**Unit A T from Thermal Combustion, °F
Unit Outlet Temperature, °F
Outlet Shell Side, °F
***Burner Duty, MM Btu/hr
***H.E. Duty, MM Btu/hr
Thermal Efficiency, %
***Overall Heat Trans Coef, U
* * *Tube Surface Area, fl2
1
4,000
95
57
3,000
110
3
5,000
317
190
10,000
110
17,000
12
7
0.6
17,000
12
7
0.6
325
825
115
60
1.000
500
1,500
1,030
1.66
1.77
42
4.9
628
325
825
115
60
1,000
500
1,500
1,030
5.4
5.9
42
4.9
2.095
* Assumes 10% fume combustion in burner flame
* * Assumes 95% overall fume combustion
***,
* Supplied by bidders
313
-------
TABLE 111
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR THERMAL INCINERATORS FOR RESIN REACTORS
(WITH HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
Ib/hr, Max
Ib/hr, Avg
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
Small
Large
High Efficiency
Small
3,225
110
3,000
4.3
95
57
8,510
1,030
3,015
7.2
4.8
95
29,674
1,863
1,100
2,050
2,688
2,600
850
600
525
900
400
1,500
44,750
Large
10,750
110
10,000
4.3
317
190
28,400
1,030
10,050
7.2
16
95
46,840
4,740
1,405
3,000
4,375
4,150
1,750
1,400
720
900
400
1,500
71,180
314
-------
TABLE 112
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR THERMAL INCINERATORS FOR RESIN REACTORS
(WITH HEAT EXCHANGE)
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
8,760
$6/hr
$6/hr
Mll/kw-hr
MO/MM Btu
Small
Large
High Efficiency
Small
375
375
390
160
550
375
2,746
6,590
9,336
10,636
4,475
15,111
Large
375
375
390
210
600
475
8,528
21,800
30,328
31,778
7,118
38,896
00
Ul
-------
TABLE 113
CATALYTIC INCINERATOR PROCESS DESCRIPTION
FOR RESIN REACTOR SPECIFICATION
This specification describes the requirements for a catalytic combustion system for
abatement of the hydrocarbon emissions from the resin production facility of a paint and
varnish plant. The system will be similar to that shown in Figure 24. All reactor thinning
tanks and product rundown tanks will be vented to the collection system. Dilution air will
be supplied through a hood over the resin filter press(es). A minimum flow damper is to be
supplied in this part of the ventilation system. It is to be sized to allow fora maximum fume
concentration of 40% LEL in the fully closed position. A high velocity Venturi section is to
be located at the incinerator inlet to assure gas flow is in excess of flame propagation
velocity at 1/2 design flow rate.
The afterburner is to be natural gas fired. Sufficient gas, having a specific gravity of
0.60 and an upper heating value of 1040 Btu/SCF, is available at pressure of 1.0 psig.
The exhaust gas contains sufficient oxygen, greater than 16% 0^ to allow firing of the
afterburner with a raw gas or process air burner. A combustion air system is not required.
Fume load to the incinerator is composed of 75% kettle emission and 25% from other
sources. Average emissions are 60% of peak. The system is to be designed on peak emission
but operating costs are to be based on average emissions. Operating conditions listed are
based on peak emissions. Fume destruction in burner is to be calculated as follows:
10% for catalytic units with or without heat exchange
10% for thermal units with heat exchange
20% for thermal units without heat exchange.
Please fill in estimated efficiency of afterburner, burner duty, heat exchanger duty,
overall heat transfer coefficient (U), tube surface area, catalyst face velocity, and catalyst
volume.
The afterburner is to be supplied with a suitable control panel and all equipment is to
be designed for outdoor operation. Incinerator operating and safety controls are to be
designed to meet F.I.A. (Factory Insurance Association) requirements. All dampers are to be
pneumatically operated and contain an integral fail-safe air reservoir. The system is to
automatically divert in the event of low flow, high afterburner temperature, high reactor
pressure, and afterburner preheat burner failure. The exhaust system should also be purged
with inert gas on fan failure or loss of flow. Damper operating is to be sequential with the
position switches mounted on the damper arm and not the operator. The system fan shall be
located after the preheat burner or the incinerator outlet and shall be constructed to
withstand 200°F higher than design operating temperature. The fan shall have a V-belt drive
and fan and motor shall have the capacity to overcome the pressure drop of the ductwork,
afterburner and any heat exchanger that may be used. System ductwork should be sized for
a maximum A P of 2 in. w.c. hot. The fan motor may be sized for restricted flow cold start.
The ductwork to the incinerator should be heated either by the use of a double manifold or
hot gas recycle or a combination of both.
316
-------
The heat exchanger is to be the parallel flow shell and tube type and designed to
operate at an afterburner outlet temperature of 1500°F. Maximum exchanger pressure drop,
both sides, should not exceed a total of 6 in. w.c. hot. Dirty gas is to flow through the tube
side.
INSTALLATION
A complete turnkey proposal including ductwork, structural steel, fuel and inert gas
piping, etc., is requested. For the purpose of this proposal fan and damper including
operators are to be considered as auxiliary. The controls and control cabinet are to be
included with the afterburner price. The afterburner will be assumed to be located on a
structural steel base on the resin plant roof. No modification to the building structural steel
is required. A tie through the roof from the base to the building steel is required. The base
and tie-in are part of the installed structural cost. All utilities are available within 30 ft of the
control cabinet, motor, and burner. Plant air is available at 100 psig and located within 30 ft.
Inert gas is available and will require 30 ft of piping from supply to ductwork. The existing
stack can be used for the diversion stack. A 10 ft exhaust stack will be mounted on the
incinerator, double manifold or exhaust fan. A total of thirty-five (35) feet of new exhaust
ductwork and twenty-five (25) feet of double manifold will be required.
317
-------
318
-------
TABLE 114
CATALYTIC INCINERATOR OPERATING CONDITIONS
FOR RESIN REACTOR SPECIFICATION
(WITH HEAT EXCHANGE)
Process Conditions
Small
Large
Reactor Number
Size each, gal
Hcbn Emission Max, Ib/hr
Hcbn Emission A ve, Ib/hr
Total Exhaust Rate, SCFM
Exhaust Temperature, °F
Heat of Combustion of
Resin Fume, Btu/lb
Hydrocarbon Concentration
Maximum Btu/SCF
Average Btu/SCF
Incinerator with Heat Exchange
Inlet Tube Side, °F
Unit Inlet, °F
Burner AT" from Fuel Gas, °F
* Burner AT" from Flame Combustion, °F
Burner Outlet Temperature, °F
**Unit t^T from Thermal Combustion, °F
Unit Outlet Temperature, °F
Outlet Shell Side, °F
Burner Duty, MM Btu/hr
HE Duty, MM Btu/hr
Thermal Efficiency
***Overall Heat Trans Coef, U
* * *Tube Surface Area, ft2
1
4,000
95
57
3,000
110
17,000
12
7
300
500
40
60
600
500
1,100
915
23%
4.2
405
3
5,000
317
190
10,000
110
17,000
12
7
300
500
40
60
600
500
1,100
915
"23%
4.2
1,350
* Assumes 10% fume combustion in burner flame
* * Assumes 95% overall fume combustion
* * *
Supplied by bidders
319
-------
TABLE 115
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR CATALYTIC INCINERATORS FOR RESIN REACTORS
(WITH HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
Ib/hr, Max
Ib/hr, Avg
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other _,
>
(4) Total Cost
Small
Large
High Efficiency
Small
3,225
110
3,000
4.3
95
57
7,775
915
3,002
7.0
4.8
95
31 , 698
4,608
11,561
47,867
Large
10,750
110
10,000
4.3
317
190
25,900
915
10,007
7.0
15.9
95
53,890
10,230
17,173
81,293
320
-------
TABLE 116
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR CATALYTIC INCINERATORS FOR RESIN REACTORS
(WITH HEAT EXCHANGE)
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
8,760
$6/hr
$8/hr
$6/hr
f.Oll/kw-hr
;.80/MM Btu
Small
Large
High Efficiency
Small
675
200
875
510
115
625
1,265
2,004
841
2,845
5,610
4,787
10,397
Large
675
200
875
510
145
655
4,045
5,436
3,083
8,519
14,094
8,129
22,223
CO
-------
FIGURE 80
CAPITAL COSTS FOR THERMAL INCINERATORS
FOR THE PAINT AND VARNISH INDUSTRY
(WITH 42% EFFICIENT HEAT EXCHANGE)
500000
100000
eo
oc
o
Q
fc
o
o
o.
<
O
10000
1000
TURNKEY SYSTEM ^
COLLECTOR WITH
PLL
ISA
UX
ILI
AF
\\
ES
E
i
XCHANGE
CO
EX
°BASEDON t
ABASED ON c
R -H
--<
LLEC'
CHAN
5ATA FF
)ATA FF
^
r^
r*~
•OR
GEF
*OM I
IOM E
**•
**
*»
Wl
Ol
EPA
EPA
^
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^
TH
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CON
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^
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r
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N
^
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jl
6
r
O. 68-02-0289
O. 68-02-0259
100
1000
GAS FLOW, SCFM
10000
30000
322
-------
FIGURE 81
CAPITAL COSTS FOR CATALYTIC INCINERATORS
FOR THE PAINT AND VARNISH INDUSTRY
(WITH 23% EFFICIENT HEAT EXCHANGE)
500000
100000
CO
DC
O
Q
te
O
U
Q.
<
U
10000
1QDO
T
URN KEY SYSTEM
I 1^
COLLECTOR WITH EXCH£
PLUS AUXILIARIES
•T
JXIGEP
—^
— <
COLLECTOR
EXCHANGER
°BASEDON C
ABASED ON
)ATA FF
DATA F
V
WIT
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H
LY
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>
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^
^
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^
s
TS
r
0. 68-02-0289
0. 68-02-025E
100
1000
GAS FLOW, SCFM
10000
30000
323
-------
FIGURE 82
DIRECT ANNUAL COSTS FOR THERMAL AND CATALYTIC INCINERATORS
FOR THE PAINT AND VARNISH INDUSTRY
(WITH HEAT EXCHANGE)
500000
CO
DC
O
Q
CO
O
u
z
<
100000
10000
1000
THERMAL
A
^~
CATALYTIC ^
DBASEDON C
A BASE DON [
ATA FR
3ATA FF
^
S
r
OM E
HOM I
S
]r
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j
/
>
N(
N
/
/
/
3. 68-02-0289
O. 68-02-0259
100 1000 10000 3000G
GAS FLOW, SCFM
324
-------
FIGURE 83
TOTAL ANNUAL COSTS FOR THERMAL AND CATALYTIC INCINERATORS
FOR THE PAINT AND VARNISH INDUSTRY
(WITH HEAT EXCHANGE)
500000
CO
DC
o
Q
CO
O
U
D
Z
100000
10000
1000
c
THERMAL
ATALYTIC
°BASED ON
A BASE DON
J(
t
k ^^^*
DATA Fl
DATA F
<
fS
^OM
ROM
S
s
EPA
EPA
A
/
>
COI\
cor
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t
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VIT
/
'
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RA
.
*
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C1
/\
>
N
r r
/
/
'
S
0. 68-02-0289
*IO. 68-02-025
3
100 1000 10000 3000C
GAS FLOW, SCFM
325
-------
326
-------
FIGURE 84
TOTAL INSTALLED COSTS FOR THERMAL AND CATALYTIC INCINERATORS
FOR THE PAINT AND VARNISH INDUSTRY
500000
100000
CO
tc
o
Q
te
o
o
Q.
<
O
10000
1000
THE
CATALY
CAT/
:RMAL WITH 42% HEAT EXCHANC
• i i i i i i i •- -1
TIC WITHOUT HEAT EXCHANGE
d
M
B
£
*
m
*
m
=^
THERr
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JE ^j
^
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l/IALW
CW
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r
fITH
TH
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S
^
OU
23
^
^
S
*>
Th
%
X
x
^
IE
H
^
^
xi
X
A'
E/
^
X
j
**
r
\-
i
$
<*
E;
' EXCHAIS
^^^f
£s
}r
s
KCHANGE
IGE
100
1000
GAS FLOW, SCFM
10000
30000
327
-------
REFERENCES
1. Marketing Guide to the Paint Industry, Patricia Noble, Ed., Charles H.
Kline & Co., Inc., Fairfield, New Jersey, 1969.
2. Federation Series on Coating Technology, Units
1. Introduction to Coating Technology, Oct., 1964
3. Oils for Organic Coatings, Sept., 1965
4. Modern Varnish Technology, May, 1966
5. Alkyd Resins, March, 1967
12. Principles of Formulation and Paint Calculation, June, 1969
17. Acrylic Resins, March, 1971
19. Vinyl Resins, April, 1972, Federation of Societies for Paint
Technology, Philadelphia, Pennsylvania
3. Stenburg, R. L, Control of Atmospheric Emissions from Paint and
Varnish Manufacturing Operations, U.S. Department of Health, Education
and Welfare, Robert A. Taft Sanitary Engineering Center, Technical
Report A58-4, Cincinnati, Ohio (June, 1958).
4. Parker, Dean H., Principles of Surface Coating Technology, John Wiley &
Sons, Interscience Publishers Division, New York, N.Y., 1965.
5. The Technology of Paints, Varnishes and Lacquers, Charles R. Martens,
Ed., Reinhold Book Corp., New York, N.Y., 1968.
6. Spence, J. W. and Haynie, F. H., Paint Technology and Air Pollution: A
Survey and Economic Assessment, Environmental Protection Agency,
National Environmental Research Center, Office of Air Programs
Publication No. AP-103, Research Triangle Park, North Carolina,
February, 1972.
7. Hardison, L. C., "A Summary of the Use of Catalyst for Stationary
Emission Source Control", presented at Franklin Institute, Philadelphia,
Pennsylvania (Nov., 1968).
8. Hardison, L. C., "Disposal of Gaseous Wastes", presented at East Ohio Gas
Company Seminar on Waste Disposal, Cleveland, Ohio (May, 1967).
9. Hardison, L. C., "Controlling Combustible Emissions", Paint and Varnish
Production, July, 1967.
328
-------
10. Unpublished source tests of 11 different kettles, Hirt Combustion
Engineers, Montebello, California, August, 1971.
11. Unpublished source tests of 10 different kettles, PPG Industries.
12. Rolke, R. W., et al. Afterburner Systems Study, Shell Development Co.,
Emeryville, California.
329
-------
330
-------
GRAPHIC ARTS
-------
4. THE GRAPHIC ARTS INDUSTRY
The graphic arts industry encompasses all operations involved in the
printing of an image onto a surface. The images may consist of alphabetical and
numerical figures, illustrations, and photographs, while the surfaces may consist
of various grades of paper, metal, plastic, fabric, and glass. The industry is
composed of over 40,000 commercial establishments'1' scattered throughout
the country and ranks seventh in value-added to the Gross National Product
and eighth in employment.121 Although the industry is large on a national
scale, it is one of the few remaining industries composed mainly of small
businesses. Approximately 80%'3) of the commercial printing establishments
employ less than twenty people.
The industry can be classified into three general categories:
1. Publishing — newspapers, books, magazines, etc.
2. Package Printing — paper containers, labels, etc.
3. Metal Decorating — metal containers, bottle caps, metal signs, etc.
Generally, these categories differ in the type of surfaces (substrates) to which
the printing images are applied. The publishing and package printing industries
generally employ various grades of paper as substrates, while the metal
decorating industry employs various types of sheet metal.
The majority of commercial printing operations employ one of the
following printing processes:
Letterpress
Lithography
Gravure
Flexography
Screen Printing
Each process has a unique method of applying the printing image onto the
substrate and a unique ink composition.
In letterpress printing, the printing image* is relief outward from the
non-image area. Originally, the printing surface was a flat plate; however, in
modern letterpress printing, the printing image is transferred to a flexible mat
from which a cylindrical plate is made. The curved plates are then attached to
*That portion of the printing plate or cylinder which transfers the ink to the
substrate.
331
-------
rollers in the press. The process is capable of both sheet-fed and web-fed (roll)
printing with press speeds up to 1500 feet per minute (web).
Letterpress is the oldest and most basic form of printing and still
predominates in periodical and newspaper publishing. Approximately 93% of
the nation's newspapers are printed by this process.'41 Letterpress accounts for
35.6% of the eight billion dollar commercial printing market (Table 117)'5> and
57.3?/o of the industry's ink consumption (Table 118).(6)
Lithography printing is characterized by having the image area on the
same plane as the non-image area. The image area chemically attracts ink (ink
receptive area) while the non-image area chemically repels ink (water receptive
area). The printing image is applied to a cylinder which transfers the inked
image directly to the substrate (direct lithography) or to a rubber blanket
cylinder which in the same revolution prints the wet inked image onto the
substrate (offset lithography). When a web or continuous roll of paper is
employed with the offset process, it is called web-offset printing.
Lithography currently accounts for 50.9% of the commercial printing
market and 10.9% of the industry's ink consumption. It is considered the
fastest growing printing process and finds its greatest use in books, pamphlets,
metal decorating, and newspapers of over 100,000 circulation.
In gravure or intaglio printing, the image area is relief inward from the
non-image area. During the inking process, both the image and non-image
surfaces are submerged in an ink bath, and the excess ink is scraped from the
non-image area with a blade (Doctor's blade). After removal of the excess ink,
the inked image area is transferred directly to the substrate. In sheet-fed
gravure, the image carrier may be either a flat plate or a curved plate attached
to a cylinder. In roll-fed gravure or rotogravure, the image is engraved into a
metal cylinder. Rotogravure presses are capable of press speeds up to 2,000
feet per minute.'2'
Gravure printing accounts for 6.6% of the commercial printing market and
19.1% of the industry's ink consumption. The process is widely used in package
printing (cellophane, metallic foil, gift wrap, and labels), magazines, catalogues,
and Sunday newspaper supplements.
Flexography is very similar to letterpress in that the printing image is
relief outward from the non-image area; however, in flexography the printing
plate is made of rubber. The process is always web-fed and is used primarily in
package printing (milk cartons).
332
-------
TABLE 117
COMMERCIAL PRINTING MARKET'5'
Printing
Process
Letterpress
Lithography
Gravure
Flexography
Screen Printing
Value of Receipts
1963 1967
2,074
1,896
287
263
69
2,236
2,787
207
304
130
($ Million)
1970
2,814
4,032
525
337
210
Percentage of Market
1963 1967 1970
45.3
41.3
6.2
5.7
1.5
38.2
47.5
6.9
5.2
2.2
35.6
50.9
6.6
4.3
2.6
Total
4,589 5,664 7,918
100.0 100.0 100.0
333
-------
TABLE 118
INK* CONSUMPTION IN 1968(6)
Printing
Process
Ink* Consumed
Pounds x 10'6
Ink* Consumed
% of Total
Lithography
Letterpress
(Publication)
(Newspaper)
Gravure
Flexography
Screen Printing
81.5
459.0
(143.0)
(316.0)
153.0
66.5
41.0
11.0
57.0
(18.0)
(39.0)
18.0
9.0
5.0
Total
801.0
100.0
*Undiluted Ink
334
-------
In screen printing, the printing image is a fine screen through which the
ink or paint flows. Non-image areas are produced by impregnating the screen
with a waxy material which prevents flow of the ink through the screen.
This process is entirely sheet-fed and is employed mainly in the printing of
greeting cards, signs, and wallpaper.
INKS AND SOLVENTS
In the printing processes, the main sources of air pollution result from the
printing inks which usually consist of three components.
1. Pigments, which produce the desired colors, are composed of finely
divided organic and inorganic materials.
2. Resins, which bind the pigments to the substrate, are composed of
organic resins and polymers.
3. Solvents, which dissolve or disperse the resins and pigments, are
usually composed of organic compounds. The solvent is removed
from the ink and emitted to the atmosphere during the drying
process.
Solvents can be classified into five general categories according to their
chemical composition.
1. Aromatics: benzene, toluene, xylene, ethylbenzene, unsaturates, and
mixtures with aromatic contents greater than 25%.
2. Aliphatics and Intermediates: normal and isoparaffins, cyclo-
paraffins, and mineral spirits containing less than 15% aromatics.
3. Oxygen-containing Compounds: methanol, propanol, isopropanol,
butanol, isobutanol, glycols, esters, and ketones.
4. Chlorinated Compounds: trichloroethylene, trichloroethane, methy-
lene chloride.
5. Nitrogen-containing Compounds: nitroparaffins and dimethyl forma-
mide.
The distribution of solvent usage among the various printing processes is
335
-------
tabulated in Tables 120<2) and 121(2) and chemical properties of representative
solvents for each group are contained in Table 119.(1'
The viscosity of printing inks is controlled by the solvent content and may
vary from a paste-like substance in letterpress and lithography to a very fluid
substance in gravure. Gravure inks must be fluid enough to flow into and out of
the engraved cells of the printing cylinder, while letterpress and lithography
inks must be viscous enough to adhere to the image areas during the printing
process.
Gravure inks usually have a solvent concentration of approximately 65%
and are composed of highly volatile aromatics (toluene and xylene) which
evaporate very rapidly at room temperature. Letterpress and lithography inks
can be divided into two categories: oxidative drying inks and heat set inks. The
oxidative drying inks (newspaper printing) contain very little solvent and dry
by oxidative polymerization without the addition of heat. Heatset inks contain
approximately 40% aliphatic solvent, and during the high temperature (=;
400° F) drying operation, approximately 50% of the original solvent is removed
and emitted to the atmosphere.
Small quantities of solvents are also consumed in the printing industry as
washing solutions and varnish thinners. The relative quantities consumed for
these purposes are tabulated in Tables 122(2) and 123.(2)
SOLVENT FLOW DIAGRAMS AND EMISSION RATES
Web-offset - Heatset Ink
A solvent flow diagram of a web-offset operation employing a heatset ink
is illustrated in Figure 85. The web travels through the presses (one for each
color), where it is printed on both sides simultaneously. The wet web is then
passed through a dryer (=: 400°F) where approximately 60% of the initial
solvent is removed, and then through chill rolls where it is cooled prior to
folding and cutting.
The dryer may be either a hot air dryer (as shown in the illustration)
where a minimum of flame impingement occurs or an all flame dryer where
direct impingement of the flame on the web occurs. The composition of the
dryer effluent gas depends on the type of dryer being employed.
In the hot air dryer, very little if any solvent decomposition occurs. As the
336
-------
TABLE 119
PHYSICAL PROPERTIES OF COMMONLY USED SOLVENTS*1'
SOLVENT
ESTERS:
Methyl Acetate
Ethyl Acetate
Isopropyl Acetate
Secondary Butyl Acetate
Normal Butyl Acetate
Amyl Acetate
ALCOHOLS:
Methyl Alcohol
Isopropyl Alcohol
Normal Butyl Alcohol
GLYCOL-ETHER:
Methyl "Cellosolve"
"Cellosolve"
KETONES:
Acetone
Methyl Ethyl Ketone
Methyl Isobutyl Ketone
Cyclohexanone
AROMATICS:
Toluene
Xylene
ALIPHATIC NAPHTHAS:
Hexane
Fast Diluent Naphtha
Heptane
Lacquer Diluent Naphtha
Octane
Mineral Spirits
BOILING
RANGE, °F
125 to 136
161 to 176
183 to 194
219 to 242
239 to 266
248 to 302
147 to 149
177 to 181
240 to 246
253 to 258
269 to 278
132 to 134
172 to 177
237 to 242
266 to 343
229 to 233
275 to 290
150 to 158
140 to 180
200 to 210
200 to 240
21 5 to 230
310 to 400
FLASH
POINT, °F
less than 30
42
60
90
102
116
61
70
115
115
130
less than 15
less than 30
80
130
45
82
less than 0
less than 0
less than 0
less than 30
30
100
Ib/gal
@ 68° F
7.55
7.40
7.25
7.18
7.30
7.20
6.60
6.55
6.75
8.03
7.74
6.60
6.71
6.68
7.88
7.24
7.26
5.70
5.75
6.05
6.20
6.20
6.50
337
-------
TABLE 120
PERCENTAGE BREAKDOWN OF SOLVENT CONSUMED FOR INK DILUTION
BY PRINTING PROCESS AND SOLVENT TYPE (1968)(2)
PRINTING SOLVENT TYPE (VOLUME %)
PROCESS A B C D E F TOTAL
Lithography 12.8 20.4 14.4 0.04 0.58 0.30 48.52%
Letterpress 0.1 0.4 0.3 0.06 - - 0.86%
Flexography 0.05 0.5 8.7 - - 0.15 9.40%
Gravure 8.6 21.1 11.1 - 0.02 - 40.82%
Screen Printing 0.05 0.2 - - - 0.15 0.40%
Total 21.60% 42.60% 34.50% 0.10% 0.60% 0.60% 100.0%*
*Total solvent consumed as ink diluent was 1 1,682,500 gal in 1968.
Solvent Types:
A — Benzene, toluene, xylene, ethylbenzene, unsaturates and mixtures with aromatic content greater than
25% by volume
B — Normal and isoparaffins, cycloparaffins, mineral spirits containing less than 15% aromatics,
heavy naphthas with aromatic contents greater than 25%, turpentine
C — Methanol, ethanol, propanol, isopropanol, butanol, isobutanol, glycols, esters, ketones
D — Trichloroethylene, trichloroethane, methylene chloride
E — Nitroparaffins and dimethyl formamide
F — Miscellaneous
-------
TABLE 121
GO
00
CO
VOLUME BREAKDOWN OF SOLVENT CONSUMED FOR INK DILUTION
BY PRINTING PROCESS AND SOLVENT TYPE (1968)
(2)
PRINTING
PROCESS
Lithography
Letterpress
Flexography
Gravure
Screen Printing
A
14,972
98
58
10,089
34
SOLVENT TYPE (HUNDRED GALLONS)
B CD E F TOTAL
23,941
444
606
24,637
173
16,691 38
399 52
10,180
12,868
85
723 408 56,773
1 994
1 170 11,015
12 - 47,606
145 437
Total
25,251 49,801 40,223 90
736
724
116.825
Solvent Type - See Table 60
-------
CO
4*
O
TABLE 122
VOLUME BREAKDOWN OF TOTAL SOLVENT CONSUMPTION
BY USE AND SOLVENT TYPE (1968)'2'
SOLVENT TYPE (THOUSAND GALLONS)
USE A B C D, E, & F TOTAL
Ink Dilution
Washes*
Coating & Varnish Thinner
2,525
579
614
4,980
1,774
1,156
4,022
519
984
155
—
—
11,682
2,872
2,754
Total 3,718 7,910 5,525 155 17,308
*Washing presses, rollers, blankets, etc.
Solvent Type — See Table 60
-------
TABLE 123
PERCENTAGE BREAKDOWN OF TOTAL SOLVENT CONSUMPTION
BY USE AND SOLVENT TYPE (1968)(2)
USE A B C D. E, & F TOTAL
Ink Dilution 14.5 28.8 23.2 1.0 67.5
Washes* 3.4 10.2 3.0 - 16.6
Coating & Varnish Thinner 3.5 6.7 5.7 - 15.9
Total 21.4 45.7 31.9 1.0 100.0%
"Washing presses, rollers, blankets, etc.
Solvent Type - See Table 60
GO
-------
FIGURE 85
WEB OFFSET, PUBLICATION
£
x. I.2LB./HR.
OF SOLVENT
XHAUST
1500 "TO aooof-V
SCFM ^-S
, ALIPHAl
SOLVENT
WASH-UP
SOLVENT -- -
INK
--FOUNTAINS
30 IN. WEB, IOOO FPM
2 SIDES ,
COVERAGE COATED
PAPER
WATER
DAMPENING
ISOPROPANOL
O.3LB./LB. OF INK
I A
I I
?
PRESS
FILTER
6
-AIR AT TS°F
FILTER
300 SCFM
TO BURNER
GAS
I2OO SCFM
r
AIR HEATER
(SSO°F)
6OOO TO IOOOO
SCFM
WATER S.
-^ ISOPROPANOL
VAPOR
DRYER
s-4OO°F
AIR & SMOKE
PRODUCT
PLUS <4-O°/o
OF INITIAL
SOLVENT
AIR AT TS°F
AIR AT 7S°F
"Emission rates shown are "typical", however, because of wide variation of printing jobs and
operating conditions, large variations will exist.
-------
amount of flame impingement increases, the quantity of solvent decomposition
also increases.
Exhaust gas analyses from a web-offset publication operation* with and
without ink and for coated and non-coated paper are included in Table 124.(2)
These analyses indicate that the ink is not the only source of emissions from
the printing operation. The paper coating also emits substantial quantities of
hydrocarbons.
The operation illustrated in Figure 85 represents a "typical" web-offset,
heatset ink, printing process operating at the following conditions:
Web Width 38 in.
Press Speed 1,000 ft/min
Number of Sides Printed 2
Ink Coverage 150%
Ink Mileage 0.41 Ib ink/106 in.2
Solvent Content of Ink 35% (Aliphatic)
% of Initial Solvent Removed in Dryer 60%
The emission rate of solvent from the operation as a function of press speed is
shown in Figure 86.
Letterpress — Publication
Letterpress differs from lithography (web-offset) in that the web is
printed on one side at a time, and the web is dried after each color is printed.
When four colors are printed, a procedure calied double ending may be
employed: the web passes through one press and one dryer, is then turned over,
and returned to the same press where it runs adjacent to the first pass on the
same cylinder. In this manner, only four presses and four dryers are required
for four-color, two-sided printing. The exhaust and solvent emission rates
shown in the solvent flow diagram (Figure 87) represent one color, two-sided
printing. In an actual four-color operation, the four dryers would be
manifolded together to a common exhaust stack and the emission rates would
be four times as great as those shown in the illustration.
Letterpress publication ink is very similar in composition to the
web-offset ink (heatset' - 35% aliphatic solvent), and consequently, the
* Dryer type not included.
343
-------
TABLE 124
ANALYSIS OF DRYER EXHAUST GAS
FROM WEB-OFFSET PUBLICATION121
Web-Offset - Publication
Component A B C D
CO, ppm 55 36.5 7.3 55
CH4/ppm 18 9 9.1 18
C02, ppm 3,010 2,970 3,180 2,850
HCBN* 1.03 0.703 0.297 0.985
Carbon, Ib/hr 0.279 0.190 0.077 0.266
*CH4 free hydrocarbons, (IbC/ft3) x 105
A — Coated paper, 30 in. web, 60% coverage, 4 color, one side 1,500
impressions/min, 300° F oven temperature, exhaust = 4,500 SCFM
B — Same as A except no ink was used.
C — News stock (uncoated) paper, same conditions as B. No ink.
D — News stock, same conditions as A.
344
-------
FIGURE 86
UJ
I-
z
o
5
UJ
o.4 r
I °-3
\
H
z
UJ
_l
o
m
0.2
O.I
EMISSION RATES* FROM WEB OFFSET AND
WEB LETTERPRESS EMPLOYING HEATSET INKS
WE
WE
B OFFSE
B LET
TE
RPRESS
500 1000 1500
PRESS SPEED, FEET/MIN.
2000
*Emission rates shown are "typical", however, because of wide variations of printing
jobs and operating conditions, large variations will exist. The basis used for calculat-
ing emission rates is the following:
Web width
Number of sides printed
Ink coverage
Ink mileage
38 in.
2
150%
0.41 Ib ink coated,
106 in.2
Offset
0.58 Ib ink coated,
106 in.2
0.62 Ib ink non-coated
106 in.2
0.79 Ib ink non-coated
106 in.2
Solvent content of ink
35% - 60% removed during drying.
345
-------
FIGURES?
WEB LETTERPRESS, PUBLICATION
EXHAUST JS.I2 L.B.,
w 7000 SCFM SOLVE N-i
en
IP-ILJ. "T'Z? 1 R /HR, te. .
ll>jrs-x3SP/o AL.IPHATIC
SOLVENT
i
38 1 N . WEB , ISOO FPM
2 SIDES., 1 COLOR
l£>O*Vo COVERAGE
4
i
i
D
I
I
(0
/HR.*
.
'
i
1
1
1
h
z
y
>,
F LTERJ j [ FILTER
S*
J£M
1 Is
AIR
(SOO-F)
1
s^ ,^ AIR A. SMOKE
' " t
^ DRVER ^ CHIL.L. PRODUCT _
OF INITIAL."
SOLVENT
1 I 11
AIR AT TS°F AIR H2O
Emission rates shown are "typical", however, because of wide variation of printing jobs
and operating conditions, large variations will exist.
-------
composition of the effluent gas also depends on the type of dryer employed.
Emission rates as a function of press speed for a letterpress, heatset ink
operation are shown in Figure 86 for the following operating conditions.
Web Width 38 in.
Number of Sides Printed 2
Ink Coverage 150%
Ink Mileage 0.58 Ib ink/106 in.2
% of Initial Solvent Removed in Dryer 60%
Web-Offset and Letterpress Newspaper Publication
Web-offset and letterpress newspaper printing operations employ
oxidative drying inks which contain little, if any, solvent; therefore, the
exhaust gases from these operations are not a source of hydrocarbon emissions.
Usually the only materials emitted from these operations are ink mist and
paper dust, which may be removed with filters as shown in Figure 88.
Rotogravure
Rotogravure printing is similar to web-letterpress in that the web is
printed on one side at a time and must be dried after each color is printed. In
publication printing, the web is usually passed through four presses where four
colors are applied to one side of the web. The web is then turned over and
passed through four additional presses for the reverse side printing.
Consequently, for four-color, two-sided printing, a total of eight presses must
be employed, and each press will include a steam drum or hot air dryer where
nearly all of the initial solvent is removed.
A solvent flow diagram for a single press operation is contained in Figure
89. For an integrated eight press operation, all of the dryers would be
manifolded to one or two exhaust stacks; therefore, the exhaust rate shown in
Figure 89 should be multiplied by four or eight for an actual operation.
As previously described, rotogravure inks are composed ot approximately
65% highly volatile, aromatic solvent which is not subject to decomposition in
the drying process. For most commercial operations, the solvent concentrations
in the exhaust gases range between 25 and 40% of the lower explosive limit
(LED. Solvent emission rates as a function of press speed for a "typical"
rotogravure printing operation running at the following conditions are
contained in Figure 90.
347
-------
FIGURE 88
WEB LETTERPRESS, NEWSPAPER
AIR ^
CO
ICFM/6FT.3 OF PRESSROOM
FI LITER
INK MIST,
PAPER DUST
HOOD &
EXHAUST
FAN
30 IN. WEB
IOOO FPM
PRESS
)NK= -4-.SL.B. /HR
PRODUCT
CARBON
NO SOLVENT
VENTIL.ATING
AIR TO PRESSROOM
* Emission rates shown are "typical", however, because of wide variation of printing jobs and operating conditions,
large variations will exist.
-------
FIGURE 89
ROTOGRAVURE PRINTING OPERATION
GRX*/URE INK
«65°/£, SOLVENT
( AROMATIC «
6OL.B/MIN. YELLOW
t
INK
FOUNTAIN!
SOLVENT L.ADEN AIR
I. OF SOLVENT*
*
63 IN. WEB ,ISOOFPM
ONE
SIDE PRINTING
COVERAGE
PRESS
(ONE UNIT)
STEAM
DRUM
OR HOT
DRYER
9O TO ISO°F
AIR
3OOO SCFM
CHIL.L.
ROL.L.S
PRODUCT
AIR
PER COL.OR
CO
4^
CO
HEAT
FROM
STEAM,
HOT W^TER
OR
HOT AIR
MT
AIR COOL.
WATER
^Emission rates shown are "typical", however, because of wide variation of printing jobs
and operating conditions, large variations will exist.
-------
Web Width 63 in.
Number of Sides Printed 2
Number of Colors 4
Ink Coverage 125%
Ink Mileage 10.67 Ib ink/T06in.2
Solvent Content of Ink 65%
Metal Decorating
The metal decorating industry includes all operations involved in the
printing of an image onto a sheet of metal. The printing image is usually
applied to a coated sheet of metal with a lithographic press, sometimes
followed by a final coating applied over the wet ink. The entire process involves
three operations: application of the undercoating to the bare metal, application
of the printing image to the dried coating, and application of the final
overcoating to the wet image. The steps involved in a common three-stage
metal decorating operation are illustrated in Figures 91 and 92.
The coating is usually a lacquer containing approximately 70% solvent
which is applied with a roller type device (Figure 91). The sheets are then
passed through a wicket oven where they are contacted with hot air at
approximately 375° F. The quantity of solvent emitted from the oven is
dependent on the thickness and solvent content of the lacquer coating;
however, the ovens are usually operated from 10 to 25% of the lower explosive
limit. If the metal must be coated on both sides, the sheets are coated and dried
on one side, turned over, and the procedure is repeated.
The second and third steps (Figure 92) include the printing of the image
onto the dry coated sheet of metal and the application of the overcoating. The
coated sheets are printed with lithographic inks containing very little if any
solvent. The wet inked sheets are then coated with a varnish containing
approximately 50% solvent and dried in wicket ovens (=320°F) which again are
operated at 10 to 25% of the lower explosive limit.
Since many metal decorating operations are for containers, three piece
being older and more common than two piece, it should be mentioned that
within some plants there are inside container spraying and baking emissions
following seaming of the container body after the undercoating and printing.
Frequently this operation is carried out by the packager at his location and
since it is not directly involved in the printing operation, it is not considered in
this study.
The newer two piece containers are not handled in sheet form nor does
the body require seaming and the handling is much different although the
emissions are similar.
The solvents employed in the varnish and lacquer coatings are usually
composed of methyl isobutyl ketone (MIBK), xylol, and aliphatic solvent, all
of which are removed in the wicket ovens.'8' The extent of solvent
decomposition is a function of the variation of temperature due to a variation
of the mixing efficiencies of the hot and cold gases in the oven.
350
-------
FIGURE 90
EMISSION RATES* FROM A TYPICAL
ROTOGRAVURE PRINTING OPERATION
20
UJ
I-
D
Z
CO
_l
—
O
<
cc
z
o
g 5
s
UJ
^
<>£*
x'
Emission Rate
Concentration
9000
8000
7000
6000
5000
4000
3000
Q.
QL
O
2
u
Z
-------
FIGURE 91
METAL DECORATING
COATING OPERATION
CO
ui
HOOD
TOO
CFM i
AIR & SOLVENT*
2.29 LB. /MIN.
7D°F -
ROOM
AIR
IO,OOO
i
1
SCFM
^ A ^»
_ AIR
so SHEETS /MIN.
28 IN. X 35 IN.
EXTRA
SOLVENT
LACQUER, INSIDE
OR REVERSE '
SIDE, T0°/0 SOLVENT
ROOM OR
OUTSIDE AIR
INVERT
STACK
20 MILLIGRAMS <4 IN.
ESSENTIALLY DRY
AIR
TO OUTSIDE
(HOT AIR)
GAS
WEIGHT
RATIOS
28 MIBK
36 XYLOL
36 ALIPHATIC
'Emission rates shown are "typical", however, because of wide variation of printing jobs and operating conditions,
large variations will exist.
-------
FIGURE 92
METAL DECORATING
PRINTING AND VARNISH OVERCOATING
WATER
VAPOR
HOOD
30 SHEETS/s/IIN.
Z.& IN. X
IN.
CO
Ul
CO
PRESS
UNIT
I
PRESS
UNIT
WATER FOR
FOUNTAIN
SOLUTION
7O°F O.3O LB
TOO SCFM 4-4-OOOSCFM
k ROOM
AIR
VARNISH
OVER-
COATER
EXTRAI
SOLVENT,
-f
IN.|
WAX;
NO SOLVENT
ROOM OR
OUTSIDE AIR
OVEN
AIR | L.
AIR
L—OAS
WICKET
PRE-
HEAT
VARNISH.
'• SOLVENT,
SAME RATIO 4 '
AS FIG. -4-1
AJR
GAS
INK ,
5°/o ALIPHATIC SOLVENT
MAY BE ADDED ON PRESS
1
WAXER
NOT FOR
CANS)
•STACK
STACK
ONLY.
12 MILLK3RAMS/-4-IN£
ESSENTIALLY DRY
HOT AIR
TO OUTSIDE
* Emission rates shown are "typical", however, because of wide variation of printing jobs and operating conditions,
large variations will exist.
-------
ABATEMENT SYSTEMS
In the printing and metal decorating industries, gaseous emissions of
hydrocarbons are potential sources of photochemical smog and control of these
emissions can be accomplished. Possible control techniques applicable to the
graphic arts industry may be classified into the following categories:
1. Process modification
2. Ink modification
3. Conventional air pollution control equipment
Process Modification
Since the major portion of hydrocarbon emissions from a printing
operation is produced during the drying process, the most logical area for
modification is the dryer. The type of dryer employed in a particular operation
depends on the substrate, ink composition, press speed, and type of printing
process and may consist of flame and high velocity air, heated air, or steam.
Several novel methods of drying are currently being developed which may
reduce or completely eliminate hydrocarbon emissions: microwave drying,
ultraviolet drying, electron beam drying, and infrared drying.
In microwave drying, the temperature of the ink is increased by the
application of electromagnetic energy (alternating electric field). Since fuel is
not directly consumed in this type of operation, the oven exhaust will not
contain combustion products; however, solvent vapors will still be emitted if
conventional inks are used.(9)
In infrared drying, the ink is dried by a free radical polymerization
mechanism which requires a non-volatile, monomer-based ink. Since the ink
will not contain a volatile solvent, hydrocarbon emissions will be eliminated.
This type of drying is still in the early experimental stages.
Electron beam drying requires inks composed of monomers or pre-
polymers which solidify by electron-induced polymerization. This procedure
is currently being employed in a small number of commercial operations;
however, equipment costs are high and since X-rays are produced when the
electrons strike the target, shielding of the entire unit is required.
354
-------
In ultraviolet drying, lamps operating at 2400 to 3600 angstroms activate
monomer-based inks resulting in rapid polymerization. It is anticipated that
ultraviolet drying will be employed in 80% of the offset printing operations and
70% of the letterpress printing operations within five years. Although
hydrocarbon emissions are eliminated in this type of drying, the system does
have some inherent disadvantages: the monomer-based inks are more expensive
than conventional inks, ozone is produced in the process and must be vented,
and the inks are not easily removed during paper reclamation.
Ink Modification
A great deal of research is currently underway to develop non-pollutant
inks. The majority of the research is aimed at the development of aqueous and
solventless inks.
Aqueous inks are already being used in some flexographic operations. One
major disadvantage of the aqueous system is that the relatively high latent heat
of water limits the press speeds when conventional dryers are employed;
however, the application of microwave drying to aqueous systems has actually
enabled press speeds to increase.'1 0)
Solventless inks are currently being marketed for web-offset and
web-letterpress operations. In contrast to solvent base inks which are dried by
evaporation, solventless inks are dried by a thermally-induced polymerization
reaction which appreciably reduces or completely eliminates hydrocarbon
emissions. The ink manufacturers claim that these inks can be adapted to
present equipment without modification and, since lower oven temperatures
are required, press speeds may be increased. Some problems have apparently
been encountered in areas of gloss, sharpness of printing, and quality, and the
ink manufacturers are actively pursuing solutions to these problems.
Conventional Air Pollution Control Equipment
Exhaust gases from printing and metal decorating plants may be treated
with conventional pollution control equipment to eliminate the organic
emissions. Three conventional abatement systems are applicable to the graphic
arts industry, and the advantages and disadvantages of each will be discussed:
thermal and catalytic combustion and solvent recovery (adsorption).
Thermal combustion involves burning the effluent gas directly in a gas or
355
-------
oil fired flame. The combustible components of the exhaust stream are heated
to their auto-ignition temperature in the presence of sufficient oxygen to
complete the following reaction:
CNHM +
-------
FIGURE 93
PRODUCTS PRODUCED AT SERIOUS
OXIDATION STAGES DURING
COMBUSTION
INPUT
RH
SATURATED
HYDROCARBONS
(ALMOST ODORLESS^
ROM
Al_COHOL_S
(LOW ODORS)
PARTIAL
oxiDATioTsi
(STAGE I)
CHUO
FOR M ALDEHYDE
(TYPICAL ALIPHATIC
END-GROUP PRODUCT)
RCOOH
ORGANIC ACIDS
(SOUR ODORS)
ADDITIONAL
OXIDATION
(STAGE 2)
COMPLETE
)XIDATION
STAGE 3)
PARTIAL
OXIDATION
GENERALIZED BURNED
ODORS v SUBOXIDES
SUCH AS CO ETC
CO
01
ArH
AROMATICS
(MODERATE ODORS)
, RCOOR'
TESTERS, MODERATE
ODORS)
RCOCR1
'KETONES, MODERATE
ODORS)
PARTIAL
OXIDATION
ArCHO
AROMATIC
ALDEHYDES
(FRUITY ODORS)
-c=c-c
002
&
ODOR
COMPLETE
OXIDATION
MOST
COMPONENTS
UNKNOWN
L
J[,$ - UNSATUR ATED
ALDEHYDES & ACIDS
(IRRITATING PUNGENCY-
EXAMPLE , ACROLEIN) i
-------
FIGURE 94
CO
01
00
FLOW DIAGRAM FOR THERMAL. COMBUSTION
INCLUDING POSSIBILITIES FOR HEAT RECOVERY
CONTAMINATED
AIR OUT
3OO TO -4-OO °F
FAN
AIR IN
TO TO 90
°F
PRESS
DRYER
OR
METAL
DECORATING
OVEN
I
I
TOO TO
HEAT
EXCHANGER
IOOO TO ISOO °F
AUXILIARY
FUEL-
6OO TO IOOO°F
IOOO°F
1
IOOO TO I5OO°F
RESIDENCE
CHAMBER
I
IOOO
ISOO
TO
°F
TO STACK
^ OR
PLAMT
HEATIMC3
SYSTEM
J
TO STACK
OR
PLANT HEATING
SYSTEM
-------
FIGURE 95
FLOW DIAGRAM FOR CATALYTIC COMBUSTION
INCLUDING POSSIBILITIES FOR HELAT RECOVERY
CONTAMINATED
AIR OUT
300 TO 4-OO -F
FAN
ffl
AIR IN
/O TO OO
•F
CO
en
CO
PRESS
DRYER
OR
METAL
DECORATING
OVEN
T
HEAT
EXCHANGER
TOO TO 9OO °F
AUXILIARY
FUEL
600 TO SOO «F
1
CATAL-YST
BED
9OO°F
RESIDENCE
CHAMBER
I
TOO TO I
9OO
TO STACK
^ OR
PLANT
HEATING
SYSTEM
I
I I
TO STACK
OR
PLANT HEATING
SYSTEM
-------
FIGUKE96
FLOW DIAGRAM OF ADSORPTION PROCESS
ADSORPTION (SOLVENT-RECOVERY SYSTEM)
EXHAUST AIR
TO
ATMOSPHERE
(SOLVENT FREE)
DRV
0
OVI
'ER
R
EN
VAPOR
-^ LADEN,
AIR
I
1 ,
T J
1
1
— »i
-
,
i
^^
•
*
r •»
1
— — ^_ — •— ^^_ ^^_ ^^ ^^_ .^_ ^^ ^_
ACTIVATED CARBON
ADSORBER
,
1
ACTIVATED CARBON
ADSORBER
^—
^ LC-VV PKh.Sl=>
FOR REGENI
AND RECOVE
te
1
__^_l
URE
ERAT
E:RY
i
4
1
| STEAM PLUS
1 SOLVENT VAPORS
i
A
T "
;
f
CONDENSER
^ RECOVERED
SOLVENT
///
STEAM /// DECANTER
•ION '///
i
•WATER
SWITCHING OR AIR FLOWS WOULD BE NECESSARY TO
ADSORPTION — REGENERATION CYCLE
ACHIEVE:
-------
adsorption capacity of the bed has been reached. The gas stream is then
diverted to an alternate bed while the original bed is regenerated with steam or
hot air. If the hydrocarbon solvent is not miscible with water, it can be
recovered by simple decantation; otherwise, recovery of the hydrocarbon will
require distillation.
Adsorption is governed by the laws of chemical equilibrium and diffusion
and, therefore, the following operation variables will influence the capacity of a
carbon bed for an organic solvent:
Partial Pressure — the adsorption capacity of a bed
increases as the partial pressure of
the vapor in the gas stream increases.
Temperature — the capacity of the bed increases
as the temperature decreases.
Molecular Size — the bed capacity decreases as the
molecular size increases.
Water Vapor — water vapor decreases the capacity
of a bed.
Performance will also be influenced by the presence of and the nature of
solid and liquid paniculate matter in the gas stream being treated. In most
designs, filters precede the carbon beds in order to remove suspended
paniculate matter.
Generally, in a well-designed adsorption unit, the activated carbon will
adsorb approximately 15% of its own weight of solvent before regeneration is
required.
361
-------
362
-------
SPECIFICATIONS AND COSTS
Abatement specifications for three sets of graphic arts applications were
written: web offset printing, metal decorating, and gravure printing. In the case
of web offset printing, both thermal and catalytic combustion systems without
heat exchange were specified. Heat exchange was not included in the
specifications because the ventilation rates from the model printing presses
studied were too low. Cost data and equipment specifications for the web
offset applications are presented in Tables 125 to 132 and in Figures 97 to 103.
Thermal and catalytic combustion systems were also specified for the
metal decorating application. Since the gas flows were higher for the metal
decorating cases, however, systems both with and without heat exchange were
specified. Cost data and equipment specifications are presented in Tables 133 to
148 and in Figures 103 to 114.
Gravure printing applications require that large volumes of ventilation air
be treated relative to metal decorating or web offset printing applications.
Specifications were written for two types of abatement systems: thermal
combustion systems and activated carbon adsorption systems. The thermal
combustion system specifications were written to apply to one or two presses
in the printing plant. This is in keeping with the industry practice of using one
incinerator for every one or two press vents. The flow from each gravure press
vent is large enough to clearly justify heat exchange in the combustion system
and the specifications have been written accordingly. Cost data and equipment
specifications are presented in Tables 149 to 152 and in Figures 115 to 117.
The carbon adsorption system specifications were written to apply to all
of the presses in a printing plant. The model plants studied in this contract
contained four and twelve roughly equivalent presses. Cost data and equipment
specifications are presented in Tables 153 to 157 and in Figures 118 to 120. The
carbon adsorption system differs from the other abatement systems studied in
that it recovers the hydrocarbon emissions in a form reusable as solvent in the
gravure printing process. The value of the recovered solvent is significant
relative to the total operating costs of the adsorption system and, in the cases
studied here, offers an attractive payout on the capital investment. The
recovered solvent credit, valued at $0.04/lb is shown with the operating cost
data in Table 156 and Figure 119.
363
-------
TABLE 125
THERMAL INCINERATOR PROCESS DESCRIPTION FOR
WEB-OFFSET PRINTING SPECIFICA TION
This specification describes the requirements of a thermal combustion system for the
abatement of hydrocarbon emissions from a web-offset printing facility. A schematic flow
diagram of the desired combustion system is included in Figure 97 while processing
conditions and specifications for small and large facilities are tabulated in Table 126.
The incinerator will be gas fired using natural gas available at a pressure of 1.0psig and
having a specific gravity of 0.6 and an upper heating value of 1,040 Btu/SCF. The exhaust
gas from the printing press will contain sufficient oxygen (greather than 16%) to allow firing
of the burner without the addition of a combustion air system.
A fan equipped with a V-belt drive will be required at the incinerator inlet. The fan will
have the capacity to overcome the pressure drop of the ductwork and the system. The
system's ductwork will be sized for a maximum A P of 2 in. w.c. (hot).
The incinerator will be supplied with suitable control panels and all equipment will be
designed for outdoor operation and to meet Factory Insurance Association's standards.
The cost estimate shall include the following items:
Incinerator
Burner
10 ft stack
Controls
Control panel
Structural steel
Fuel gas piping
Electrical
Ductwork
Insulation
Fan
Fan motor
Two day start-up service
All items with exception of the incinerator and burner shall be considered auxiliaries.
The unit will be designed for the maximum hydrocarbon concentration, while
operating costs shall be estimated at the average hydrocarbon concentration.
The incinerator will be located on the roof of the printing facility and no modification
of the building structure is required. All utilities are available within 30 ft of the control
cabinet, motor, and burner.
364
-------
FIGURE 97
SCHEMATIC FLOW DIAGRAM OF
THERMAL AND CATALYTIC
COMBUSTION WITHOUT
HEIAT EXCHANGER FOR
WEB-OFF SET AND METAL DECORATING
BURNER
FUEL.
STACK
FAN
CO
05
O1
RESIDENCE CHAMBER
OR
CATALYST BED
CON TA MINI ATE D GASES
FROM PRINTING PRESS
rrn TEMPERATURE INDICATOR
VTC\ TEMPERATURE CONTROL.
-------
366
-------
TABLE 126
THERMAL INCINERATOR OPERATING CONDITIONS
FOR WEB-OFFSET PRINTING SPECIFICATION
(WITHOUT HEAT EXCHANGE)
Plant Size
Process Conditions
Small
Large
Effluent Gas Temperature, F
Effluent Gas Rate, SCFM
Effluent Gas Rate, ACFM
Hcbn Concentration, ppm' '
Hcbn Emission Rate, Ib/hr
Maximum
Average
Heat of Combustion of Hcbn,
Heating Value of Gas, Btu/SCF
Maximum
Average
Incinerator Specifications
Inlet Temperature, °F
Outlet Temperature, °F
Residence Time @ Temperature, sec
Burner Duty, MMBtu/hr*
350
2,000
3,060
500-2.000
10.0
6.3
19,500
1.5
0.9
350
1,500
0.6
3.35
350
7,000
10,700
500-2,000
35.4
22.1
19,500
1.5
0.9
350
1,500
0.6
10.52
(1) Measured as methane equivalents
(2) Assumed as n-hexane
*To be filled in by supplier
367
-------
TABLE 127
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR THERMAL INCINERATORS FOR WEB-OFFSET PRINTING
(WITHOUT HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
ppm
ID Rt.ii/scf
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
ppm
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
Small
Large
High Efficiency
Small
3,060
350
2,000
-
500-2,000
6.3
0.9
7,550
1,500
2,039
5.35
5-20
<0.3
>95
16,075
1,870
1,950
1,200
2,150
650
625
300
600
450
1,750
2,450
30,070
Large
10,700
350
7,000
-
500-2.000
22.1
0.9
26,480
1,500
7,136
5.35
5-20
<1. 1
>95
21,025
3,420
2,450
1,625
2,850
850
800
350
600
450
1,750
2,688
38,858
368
-------
FIGURE 98
CAPITAL COSTS FOR THERMAL INCINERATORS
FOR WEB-OFFSET PRINTING
(WITHOUT HEAT EXCHANGE)
500000
100000
O
O
k
8
Q.
<
O
10000
10.00
TURNKEY SYSTEM
COLLECTOR PLUS AUXILIARIES
COLLECTOR
ONLY
1000
10000
GAS FLOW, SCFM
100000
300000
369
-------
TABLE 128
GO
•vj
o
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR THERMAL INCINERATORS FOR WEB-OFFSET PRINTING
(WITHOUT HEAT EXCHANGE)
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
$6/hr
$6/hr
$.011/kw-hr
$.80/MMBtu
Small
Large
High Efficiency
Small
4,000
1,500
1,500
336
135
471
125
125
222
10,026
10,248
12,344
3,007
15,351
Large
4,000
1,500
1,500
336
160
496
125
125
813
33,196
34,009
36,130
3,886
40,016
-------
FIGURE 99
ANNUAL COSTS FOR THERMAL INCINERATORS
FOR WEB-OFFSET PRINTING
(WITHOUT HEAT EXCHANGE)
500000
CO
cc
O
Q
te
o
O
100000
10000
1000
4
•^
t
//
^
^
f
£
<
r
>
>
^
1C
(OPE
PLUS C/i
^
DTAL
RAT^
iPITAl
COS
JG C
. Cl-
;T
:os
IAF
OPERATING COST
T
IGES]
1000 10000 100000 300000
GAS FLOW, SCFM
371
-------
TABLE 129
CATALYTIC INCINERATOR PROCESS DESCRIPTION FOR
WEB-OFFSET PRINTING SPECIFICATION
This specification describes the requirements of a thermal combustion system for the
abatement of hydrocarbon emissions from a web-offset printing facility. A schematic flow
diagram of the desired combustion system is included in Figure 100 while processing
conditions and specifications for small and large facilities are tabulated in Table 130.
The incinerator will be gas fired using natural gas available at a pressure of I.Opsig and
having a specific gravity of 0.6 and an upper heating value of 1,040 Btu/SCF. The exhaust
gas from the printing press will contain sufficient oxygen (greather than 16%) to allow firing
of the burner without the addition of a combustion air system.
A fan equipped with a V-belt drive will be required at the incinerator inlet. The fan will
have the capacity to overcome the pressure drop of the ductwork and the system. The
system's ductwork will be sized for a maximum A P of 2 in. w.c. (hot).
The incinerator will be supplied with suitable control panels, and all equipment will be
designed for outdoor operation and to meet Factory Insurance Association's standards.
The cost estimate shall include the following items:
Incinerator
Burner
10 ft stack
Controls
Control panel
Structural steel
Fuel gas piping
Electrical
Ductwork
Insulation
Fan
Fan motor
Two day start-up service
All items with exception of the incinerator and burner shall be considered auxiliaries.
The unit will be designed for the maximum hydrocarbon concentration, while
operating costs shall be estimated at the average hydrocarbon concentration.
The incinerator will be located on the roof of the printing facility and no modification
of the building structure is required. All utilities are available within 30 ft of the control
cabinet, motor, and burner.
372
-------
FIGURE 100
SCHEMATIC FLOW DIAGRAM OF
THERMAL- AND CATALYTIC
COMBUSTION • WITHOUT
HEAT EXCHANGE FOR
WEB-OFFSET AND METAL DECORATING
BURNER
FUEL
FAN
CO
^j
CO
STACK
RESIDENCE CHAMBER
OR
CATALYST BED
CONTAMINATED GASES
FROM PRINTINGS PRESS
TEMPERATURE
TEMPERATURE
INDICATOR
CONTROL
-------
374
-------
TABLE 130
CATALYTIC INCINERATOR OPERATING CONDITIONS
FOR WEB-OFFSET PRINTING SPECIFICATION
(WITHOUT HEAT EXCHANGE)
Plant Size Small Large
Process Conditions
Effluent Gas Temperature, °F 350 350
Effluent Gas Rate, SCFM 2,000 7,000
Effluent Gas Rate, ACFM 3,060 10,700
Hcbn Concentration, ppm^V 500-2,000 500-2,000
Hcbn Emission Rate, Ib/hr
Maximum 10.1 35.4
Average 6.3 22.1
Heat of Combustion of Hcbn, Btu/lb(2) 19,500 19,500
Heating Value of Gas, Btu/SCF
Maximum 1.5 1.5
Average 0.9 0.9
Incinerator Specifications
Inlet Temperature, °F 350 350
Outlet Temperature, °F /, WO 1,100
Burner Duty, MMBtu/hr* 1.89 6.60
(1) Measured as methane equivalents
(2) Assumed as n-hexane
*To be filled in by supplier
375
-------
TABLE 131
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR CATALYTIC INCINERATORS FOR WEB-OFFSET PRINTING
(WITHOUT HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
ppm
D/nr 8Rt,,/<;rf
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
Small
Large
High Efficiency
Small
3,060
350
2,000
-
500-2,000
6.3
0.9
5,970
1,100
2,031
-
0.3
95
17,960
1,790
9,485
29,235
Large
10,700
350
7,000
-
500-2,000
22.1
0.9
20,900
1,100
7,105
-
1.1
95
34,300
3,690
11,938
49,928
376
-------
FIGURE 101
CAPITAL COSTS FOR CATALYTIC INCINERATORS
FOR WEB-OFFSET PRINTING
(WITHOUT HEAT EXCHANGE)
500000.
100000
CO
DC
fc
o
u
_l
<
t
0.
u
10000
1000
TURNKEY SYSTEM
COLLECTOR
PLUS AUXILIARIES
COLLECTOR ONLY
1000
10000
GAS FLOW, SCFM
100000
300000
377
-------
TABLE 132
CO
•>j
00
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR CATALYTIC INCINERATORS FOR WEB-OFFSET PRINTING
(WITHOUT HEAT EXCHANGE)
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
$6/hr
$8/hr
$6/hr
$.011/kw-hi
$ . 80/MMBtu
LA Process Wt.
Small
Large
High Efficiency
Small
4,000
875
510
110
620
943
943
423
5,842
6,265
8,703
2,924
11,627
Large
4,000
875
510
135
645
2,950
2,950
1,369
20,466
21,835
26,305
4,993
31,298
-------
FIGURE 102
ANNUAL COSTS FOR CATALYTIC INCINERATORS
FOR WEB-OFFSET PRINTING
(WITHOUT HEAT EXCHANGE)
500000.
100000
CO
DC
O
O
te
O
O
10000
1000
/
s
>
s
k
*f
5
/
,
>
<
<
/
^
^
/
(OPERA'
CAPI1
>
^
OPERA'
)TAL COST
FING COST P
•AL CHARGE
FING
:os
T
LUS
S)
1000
10000
GAS FLOW, SCFM
100000
300000
379
-------
TABLE 133
THERMAL INCINERATOR PROCESS DESCRIPTION FOR
METAL DECORATING SPECIFICATION
This specification describes the requirements of a thermal combustion system for the
abatement of hydrocarbon emissions from metal decorating facilities. Schematic flow
diagrams of the desired combustion systems are included in Figure 103 while processing
conditions and specifications for small and large facilities are tabulated in Table 134.
The incinerators will be gas fired using natural gas available at a pressure of 1.0 psig and
having a specific gravity of 0.6 and an upper heating value of 1,040 Btu/SCF.
The exhaust gas from the printing press will contain sufficient oxygen (greater than
16%) to allow firing of the burner without the addition of a combustion air system.
A fan equipped with a V-belt drive will be required at the incinerator inlet. The fan will
have the capacity to overcome the pressure drop of the ductwork, burner, and heat exchange
that may be incorporated in the system. The system's ductwork will be sized for a maximum
A/*of2in. w.c. (hot).
The incinerators will be supplied with suitable control panels, and all equipment will be
designed for outdoor operation and to meet Factory Insurance Association's standards.
The cost estimates for each combustion system will include the following items;
Incinerator
Burner
10 ft stack
Controls
Control panel
Structural steel
Fuel gas piping
Electrical
Ductwork
Insulation
Fan
Fan motor
Two day start-up service
Dampers (when included)
All items with exception of the incinerator and burner will be considered auxiliaries.
The incinerators shall be located on the roof of the printing facility, and no
modification of the building structure is required. All utilities are available within 30 ft of
the control cabinet, motor, and burner.
380
-------
FIGURE 103
SCHEMATIC FLOW DIAGRAM OF
THERMAL. AND CATALYTIC
COMBUSTION WITHOUT
HEAT EXCHANGE FOR
WEB~OFFSET AND METAL DECORATING
BURNER
FUEU
STACK
FAN
CO
00
|< RESIDENCE CHAMBER
' OR
CATAUYST BED
CONTAMINATED GASES
FROM PRINTING PRESS
TM TEMPERATURE INDICATOR
TEMPERATURE CONTROL
-------
382
-------
TABLE 134
THERMAL INCINERATOR OPERATING CONDITIONS
FOR METAL DECORATING SPECIFICATION
(WITHOUT HEAT EXCHANGE)
Plant Size Small Large
Process Conditions
Effluent Gas Temperature, °F 350 350
Effluent Gas Rate, SCFM 4,000 10,000
Effluent Gas Rate, ACFM 6,100 15250
Hcbn Concentration, % LEL 15 15
Hcbn Emission Rate, Ib/hr 97 242
Heating Value of Gas, Btu/SCF 7.4 7.4
Heat of Combustion of Hcbn, Btu/lb 18,400 18,400
Incinerator Specifications
Inlet Gas Temperature, °F 350 350
Outlet Gas Temperature, °F 1,500 1,500
Residence Time Temperature, sec 0.6 0.6
Burner Duty, MMBtu/hr* 4.21 11.07
*To be filled in by supplier
383
-------
TABLE 135
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR THERMAL INCINERATORS FOR METAL DECORATING
(WITHOUT HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Hydrocarbon
%LEL
lb/hr Btu/scf
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
-
Small
Large
High Efficiency
Small
6,100
350
4,000
*•
-I •-
15
97
7.4
15,070
1,500
4,075
-
<4.9
>95
16,775
2,338
2,850
2,450
2,750
825
750
250
950
450
1,750
4,525
36,663
Large
15,250
350
10,000
-
"1 r"
15
242
7.4
37,684
1,500
10,190
-
<12.1
>95
27,800
3,995
3,500
2,800
4,000
1,325
1,250
425
950
450
1,750
5,925
54,170
384
-------
FIGURE 104
CAPITAL COSTS FOR THERMAL INCINERATORS
FOR METAL DECORATING
(WITHOUT HEAT EXCHANGE)
500000
CO
cc
o
a
o
o
Z
<
o
100000
10000
1000
^
>
f
4
—
y*
s
r
1*
',
*
*
'
'
0
s
+
if
*
«•
it.
k
k
•
TIJ
_^
^r
_^
tf?
r COLLE
RNKEY SYSTEM
CC
PLUS
ECTOF
)LLE
AU)
i or
EC7
-------
TABLE 136
oo
00
05
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR THERMAL INCINERATORS FOR METAL DECORATING
(WITHOUT HEAT EXCHANGE)
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
$6/hr
$6/hr
$.011/kw-hi
$.80/MMBtu
Small
Large
High Efficiency
Small
4,000
1,500
1,500
336
135
471
125
125
510
14,488
14,998
17,094
3,666
20,760
Large
4,000
1,500
1,500
336
160
496
125
125
1,097
37,044
38,141
40,262
5,417
45,679
-------
FIGURE 105
ANNUAL COSTS FOR THERMAL INCINERATORS
FOR METAL DECORATING
(WITHOUT HEAT EXCHANGE)
500000
100000
CO
cc
o
G
te
o
o
10000
1000
//
r /
&
TOTAL COST
(OPERATING COST PLUS
I_ CAPITAL CHARGES) .
OPERATING COST
10000
GAS FLOW, SCFM
100000
300000
387
-------
TABLE 137
THERMAL INCINERATOR PROCESS DESCRIPTION FOR
METAL DECORATING SPECIFICATION
This specification describes the requirements of a thermal combustion system for the
abatement of hydrocarbon emissions from metal decorating facilities. Schematic flow
diagrams of the desired combustion systems are included in Figure 106 while processing
conditions and specifications for small and large facilities are tabulated in Table 138.
The incinerators will be gas fired using natural gas available at a pressure of 1.0 psig and
having a specific gravity of 0.6 and an upper heating value of 1,040 Btu/SCF.
The exhaust gas from the printing press will contain sufficient oxygen (greater than
16%) to allow firing of the burner without the addition of a combustion air system.
A fan equipped with a V-belt drive will be required at the incinerator inlet. The fan will
have the capacity to overcome the pressure drop of the ductwork, burner, and heat exchange
that may be incorporated in the system. The system's ductwork will be sized for a maximum
AP of 2 in. w.c. (hot).
The heat exchanger shall be a parallel flow shell and tube exchanger and designed to
operate at an incinerator outlet temperature of 1,500°F. Maximum exchanger pressure drop,
both sides, shall not exceed 6.0 in. w.c. (hot), and dirty gas shall flow through the tube side.
Approximate thermal efficiencies of the exchangers are tabulated in the specification sheets.
The incinerators will be supplied with suitable control panels, and all equipment will be
designed for outdoor operation and to meet Factory Insurance Association's standards.
The cost estimates for each combustion system will include the following items:
Incinerator
Burner
10 ft stack
Controls
Control panel
Structural steel
Fuel gas piping
Electrical
Ductwork
Insulation
Fan
Fan motor
Two day start-up service
Heat exchanger
Dampers (when included)
All items with exception of the incinerator, burner, and heat exchanger will be
considered auxiliaries.
The incinerators shall be located on the roof of the printing facility, and no
modification of the building structure is required. All utilities are available within 30 ft of
the control cabinet, motor, and burner.
388
-------
FIGURE 106
SCHEMATIC FLOW DIAGRAM OF
THERMAL AND CATALYTIC
COMBUSTION WITH
HEAT EXCHANGE FOR
WEB-OFF SET AND METAL DECORATING
1
BURNER
FUEL
FAN
GO
00
CO
RESIDENCE CHAMBER
OR
CATALYST BED
HEAT
EXCHANGE
STACK
CONTAMINATED GASES
FROM PRINTING PRESS
n~C\ TEMPERATURE CONTROL
-------
390
-------
TABLE 138
THERMAL INCINERATOR OPERATING CONDITIONS
FOR METAL DECORATING SPECIFICATION
(WITH HEAT EXCHANGE)
Plant Size Small Large
Process Conditions
Effluent Gas Temperature, °F 350 350
Effluent Gas Rate, SCFM 4,000 10,000
Effluent Gas Rate, A CFM 6,100 15,250
Hcbn Concentration, % LEL 15 15
Hcbn Emission Rate, Ib/hr 97 242
Heating Value of Gas, Btu/SCF 7.4 7.4
Heat of Combustion of Hcbn, Btu/lb 18,400 18,400
Incinerator Specifications
Residence Time, sec Temperature 0.6 0.6
Inlet Tubeside Temperature, °F 350 350
Unit Outlet Temperature, °F 1,500 1,500
Thermal Efficiency ^42 ^42
Burner Duty, MMBtu/hr* 1.83 3.49
*To be filled in by supplier
391
-------
TABLE 139
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR THERMAL INCINERATORS FOR METAL DECORATING
(WITH HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Hydrocarbon
%LEL
lb/hr Btu/scf
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
ppm
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
Small
Large
High Efficiency
Small
6,100
350
4,000
-
15
97
7.4
15,070
1,500
4,075
-
<4.9
>95
32,500
2,788
3,100
2,750
2,750
800
875
250
1,050
450
1,750
5,860
54,923
Large
15,250
350
10,000
-
15
242
7.4
37,684
1,500
10,190
-
<12.1
>95
39,575
5,680
3,750
4,000
4,000
1,300
1,625
400
1,050
450
1,750
5,960
69,540
392
-------
FIGURE 107
CAPITAL COSTS FOR THERMAL INCINERATORS
FOR METAL DECORATING
(WITH HEAT EXCHANGE)
500000.
100000
oo
DC
o
Q
te
o
o
_l
<
t
Q.
o
10000
1000
TURNKEY SYSTEM
COLLECTOR
PLUS AUXILIARIES
COLLECTOR ONLY
1000
10000
GAS FLOW, SCFM
100000
300000
393
-------
TABLE 140
CO
CO
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR THERMAL INCINERATORS FOR METAL DECORATING
(WITH HEAT EXCHANGE)
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
$6/hr
$6/hr
$.011/kw-hr
$.80/MMBtu
Small
Large
High Efficiency
Small
4,000
1,575
1,575
360
135
495
125
125
1,043
5,479
6,522
8,717
5,492
14,209
Large
4,000
1,575
1,575
360
160
520
125
125
2,149
12,036
14,185
16,405
6,954
23,359
-------
FIGURE 108
ANNUAL COSTS FOR THERMAL INCINERATORS
FOR METAL DECORATING
{WITH HEAT EXCHANGE)
500000
100000
CO
DC
O
O
O
O
10000
1000
3E
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
10000
GAS FLOW, SCFM
100000
300000
395
-------
TABLE 141
CATALYTIC INCINERATOR PROCESS DESCRIPTION FOR
METAL DECORATING SPECIFICATION
This specification describes the requirements of catalytic combustion systems for the
abatement of hydrocarbon emissions from metal decorating facilities. Schematic flow
diagrams of the desired combustion systems are included in Figure 109 while processing
conditions and specifications for small and large facilities are tabulated in Table 142.
The incinerators will be gas fired using natural gas available at a pressure of 1.0 psig and
having a specific gravity of 0.6 and an upper heating value of 1,040 Btu/SCF.
The exhaust gas from the printing press will contain sufficient oxygen (greater than
16%) to allow firing of the burner without the addition of a combustion air system.
A fan equipped with a V-belt drive will be required at the incinerator inlet. The fan will
have the capacity to overcome the pressure drop of the ductwork, burner, and any heat
exchange that may be incorporated in the system. The system's ductwork will be sized for a
maximum &Pof2in. w.c. (hot).
The incinerators will be supplied with suitable control panels, and all equipment will be
designed for outdoor operation and to meet Factory Insurance Association's standards.
The cost estimates for each combustion system shall include the following items:
Incinerator
Burner
10 ft stack
Controls
Control panel
Structural steel
Fuel gas piping
Electrical
Ductwork
Insulation
Fan
Fan motor
Two day start-up service
Dampers (when included)
All items with exception of the incinerator and burner will be considered auxiliaries.
The incinerators will be located on the roof of the printing facility, and no
modification of the building structure is required. All utilities are available within 30 ft of
the control cabinet, motor, and burner.
396
-------
FIGURE 109
SCHEMATIC FLOW DIAGRAM OF
"THEIRMAL AND CATALYTIC
COMBUSTION! WITHOUT
HE: AT EXCHANGE: FOR
WEB OFFSET AND METAL DECORATING
BURNER
FUEL.
FAN
CO
CD
I V
STACK
\
RESIDENCE CHAMBER
OR
CATAL.YST BED
CONTAMINATED GASES
FROM PRINTING PRESS
~ I TEMPERATURE INDICATOR
TEMPERATURE CONTROL
-------
398
-------
TABLE 142
CATALYTIC INCINERATOR OPERATING CONDITIONS
FOR METAL DECORATING SPECIFICATION
(WITHOUT HEAT EXCHANGE)
Plant Size Small Large
Process Conditions
Effluent Gas Temperature, °F 350 350
Effluent Gas Rate, SCFM 4,000 10,000
Effluent Gas Rate, ACFM 6,100 15,250
Hcbn Concentration, % LEL 15 15
Hcbn Emission Rate, Ibs/hr 97 242
Heating Value of Gas, Btu/SCF 7.4 7.4
Heat of Combustion of Hcbn, Btu/lb 18,400 18,400
Incinerator Specifications
Inlet Gas Temperature, °F 350 350
Outlet Gas Temperature, °F 1,100 1,100
*Burner Duty, MMBtu/hr 1.97 4.92
*To be filled in by supplier
399
-------
TABLE 143
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR CATALYTIC INCINERATORS FOR METAL DECORATING
(WITHOUT HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Hydrocarbon
% LEL
lb/hr Btu/scf
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
Small
Large
High Efficiency
Small
6,100
350
4,000
15
97
7.4
11,860
1,100
4,033
4.9
95
26,010
2,270
10,565
38,845
Large
15,250
350
10,000
15
242
7.4
29,650
1,100
10,083
12.1
95
42,560
4,940
14,775
62,275
400
-------
FIGURE 110
CAPITAL COSTS FOR CATALYTIC INCINERATORS
FOR METAL DECORATING
(WITHOUT HEAT EXCHANGE)
500000
CO
cc
o
Q
te
o
o
5Z
<
o
100000
10000
1000
+
+
>
f
^
4
vS
J
f
^
4
+
x>
^
'
4
''
s
'
s
L
*"^
A
TURNK
xX
iT
CEY S
VST
EM
COLLECTOR
' ^<. PLUS AUXILIARIES
^
COLLI
ECTOF
I Of
slL\
i
1000 10000 100000 300000
GAS FLOW, SCFM
401
-------
TABLE 144
£
to
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR CATALYTIC INCINERATORS FOR METAL DECORATING
(WITHOUT HEAT EXCHANGE)
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
$6/hr
$8/hr
$6/hr
$.011/kw-hi
$.80/MMBtu
Small
Large
High Efficiency
Small
4,000
875
510
110
620
1,708
824
6,490
7,314
10,517
3,885
14,402
Large
4,000
875
510
135
645
4,175
2,058
16,225
18,283
23,978
6,228
30,206
-------
FIGURE 111
ANNUAL COSTS FOR CATALYTIC INCINERATORS
FOR METAL DECORATING
(WITHOUT HEAT EXCHANGE)
500000
V)
cc
o
Q
O
O
100000
10000
1000
,
',
/
f
j'
/
/
/
/
/
/
/
/
(
>
^
TOTAL
COST
(OPERATING COST
PLUS C^
Sr *
Y
1 OPEF
^PITAL CHARGES
*ATIN
G C
OS
T
1000 10000 100000 300000
GAS FLOW, SCFM
403
-------
TABLE 145
CATALYTIC INCINERATOR PROCESS DESCRIPTION FOR
METAL DECORATING SPECIFICATION
This specification describes the requirements of catalytic combustion systems for the
abatement of hydrocarbon emissions from metal decorating facilities. Schematic flow
diagrams of the desired combustion systems ary included in Figure 112 while processing
conditions and specifications for small and large facilities are tabulated in Table 146.
The incinerators will be gas fired using natural gas available at a pressure of 1.0 psig and
having a specific gravity of 0.6 and an upper heating value of 1,040 Btu/SCF.
The exhaust gas from the printing press will contain sufficient oxygen (greater than
16%) to allow firing of the burner without the addition of a combustion air system.
A fan equipped with a V-belt drive will be required at the incinerator inlet. The fan will
have the capacity to overcome the pressure drop of the ductwork, burner, and any heat
exchange that may be incorporated in the system. The system's ductwork will be sized for a
maximum NPof2in. w.c. (hot).
The heat exchanger will be a parallel flow shell and tube exchanger and designed to
operate at an outlet temperature of 1,100°F. Maximum exchanger pressure drop, both sides,
will not exceed 6.0 in. w.c. (hot), and dirty gas will flow through the tube side. Approximate
thermal efficiencies of the exchangers are tabulated in the specification sheets.
The incinerators will be supplied with suitable control panels, and all equipment will be
designed for outdoor operation and to meet Factory Insurance Association's standards.
The cost estimates for each combustion system shall include the following items:
Incinerator
Burner
10 ft stack
Controls
Control panel
Structural steel
Fuel gas piping
Electrical
Ductwork
Insulation
Fan
Fan motor
Two day start-up service
Heat exchanger
Dampers (when included)
All items with exception of the incinerator, burner, and heat exchanger will be
considered auxiliaries.
The incinerators will be located on the roof of the printing facility, and no
modification of the building structure is required. All utilities are available within 30 ft of
the control cabinet, motor, and burner.
404
-------
FIGURE 112
SCHEMATIC FLOW DIAGRAM OF
"THERMAL AND CATALYTIC
COMBUSTION WITH
HEAT EXCHANGE FOR
WEB-OFFSET AND METAL DECORATING
BURNER
FUEL. """
FAN
I
k
K RESIDENCE CHAMBER
k OR
l<£ CATALYST BED
K%
HEAT
EXCHANGE
STACH
CONTAMINATED GASES
FROM PRINTING PRESS
fTC) TEMPERATURE CONTROL-
-------
406
-------
TABLE 146
CATALYTIC INCINERATOR OPERATING CONDITIONS
FOR METAL DECORATING SPECIFICATION
(WITH HEAT EXCHANGE)
Plant Size
Small
Process Conditions
Effluent Gas Temperature, F
Effluent Gas Rate, SCFM
Effluent Gas Rate, ACFM
Hcbn Concentration, % LEL
Hcbn Emission Rate, Ib/hr
Heating Value of Gas, Btu/SCF
Heat of Combustion of Hcbn, Btu/lb
350
4,000
6,100
15
97
7.4
18,400
350
10,000
15250
15
242
7.4
18,400
Incinerator Specifications
Inlet Tubeside Temperature, °F
Unit Outlet Temperature, °F
Burner A T from Fuel Gas, °F
Thermal Efficiency
*Duty, MMBtu/hr
*Burner Duty, MMBtu/hr
*0verall Heat Transfer Coef., U
*Tube Surface Area, fir
350 350
1,100 1,100
25°F (min) 25°F (min)
To obtain min burner A T
1.71
1.97
4.5
1,100
4.28
4.92
4.5
2,740
*To be filled in by supplier
407
-------
TABLE 147
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR CATALYTIC INCINERATORS FOR METAL DECORATING
(WITH HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Hydrocarbon
%LEL
lb/hr Btu/scf
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
Small
Large
High Efficiency
Small
6,100
350
4,000
-
15
97
7.4
11,800
1,100
4,000
-
4.85
95
36,160
3,053
11,915
51,128
Large
15,250
350
10,000
-
15
242
7.4
29,400
1,100
10,000
•
12.1
95
55,950
6,635
16,275
78,860
408
-------
FIGURE 113
CAPITAL COSTS FOR CATALYTIC INCINERATORS
FOR METAL DECORATING
(WITH HEAT EXCHANGE)
500000
V)
DC
o
Q
te
o
O
51
<
o
100000
10000
1000
*
«
«l
c
-------
TABLE 148
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR CATALYTIC INCINERATORS FOR METAL DECORATING
(WITH HEAT EXCHANGE)
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
$6/hr
$8/hr
$.011/kw-hi
$.80/MMBtu
Small
Large
.
High Efficiency
Small
4,000
875
510
110
620
1,708
1,314
266
1,580
4,783
5,113
9,896
Large
4,000
875
510
135
645
4,175
2,891
657
3,548
9,243
7,886
17,129
-------
FIGURE 114
ANNUAL COSTS FOR CATALYTIC INCINERATORS
FOR METAL DECORATING
(WITH HEAT EXCHANGE)
500000
o
o
te
o
U
100000
10000
1000
^>
/
r
s*
s
s
J
/
J
s
Jt
^/
s
/
s
/
'
f
I
6
TOTAL COST
(OPERATING COST PLUS
^ CAPITAL CHARGES)
r
. OPE
>T
ERATI
MG
CO
5T
1000 10000 100000 300000
GAS FLOW, SCFM
411
-------
TABLE 149
THERMAL INCINERATOR PROCESS DESCRIPTION FOR
GRAVURE PRINTING SPECIFICATION
This specification describes the requirements of a thermal combustion system for the
abatement of hydrocarbon emissions from gravure printing facilities. A schematic flow
diagram of the desired combustion system is included in Figure 115 while processing
conditions and specifications for small and large facilities are tabulated in Table 150.
The incinerator will be gas fired using natural gas available at a pressure of I.Opsig and
having a specific gravity of 0.6 and an upper heating value of 1,040 Btu/SCF. The exhaust
gas from the printing press will contain sufficient oxygen (greather than 16%) to allow firing
of the burner without the addition of a combustion air system.
A fan equipped with a V-belt drive will be required at the incinerstor inlet. The fan will
have the capacity to overcome the pressure drop of the ductwork, burner, and heat
exchanger. The system's ductwork will be sized for a maximum A P of 2 in. w.c. (hot).
The heat exchanger will be a parallel flow shell and tube exchanger and be designed to
operate at an outlet incinerator temperature of 1,500°F. Maximum exchanger pressure drop,
both sides, will not exceed 6.0 in. w.c. (hot) and dirty gas will flow through the tube side.
The approximate thermal efficiency of the exchanger is tabulated in the specification sheet.
The incinerator will be supplied with a suitable control panel, and all equipment will be
designed for outdoor operation and to meet Factory Insurance Association's standards.
The cost estimate for the combustion system will include the following items:
Incinerator
Burner
10 ft stack
Controls
Control panel
Structural steel
Fuel gas piping
Electrical
Ductwork
Insulation
Fan
Fan motor
Two day start-up service
Heat exchanger
Dampers
All items with exception of the incinerator, burner, and heat exchanger will be
considered auxiliaries.
The incinerator will be located on the roof of the printing facility, and no modification
of the building structure is required. All utilities are available within 30 ft of the control
cabinet, motor, and burner.
Since the hydrocarbon concentration of the exhaust gas from this gravure printing
operation is greater than 25% of the LEL, the exhaust gas will be diluted with sufficient hot
recycle gas to lower the hydrocarbon concentration to 25% LEL.
412
-------
FIGURE 115
SCHEMATIC FLOW DIAGRAM OF
THERMAL COMBUSTION WITH
HEAT EXCHANGE FOR
GRAVURE PRINTING
1
BURNER_
FUEL-
FAN
CO
k
I
RESIDENCE CHAMBER
OR
CATALYST BED
HEAT
EXCHANGE
DAMPER
STACK
CONTAMINATED GASES
FROM PRINTING PRESS
(TO TEMPERATURE CONTROL-
-------
414
-------
TABLE 150
THERMAL INCINERATOR OPERATING CONDITIONS
FOR GRAVURE PRINTING SPECIFICATION
(WITH HEAT EXCHANGE)
Plant Size
Small
Large
Process Conditions
Effluent Gas Temperature
Effluent Gas Rate, SCFM
Effluent Gas Rate, ACFM
Hcbn Concentration, % LEL
Hcbn Emission Rate, Ibs/hr
Heating Value of Gas, Btu/SCF
Heat of Combustion of Hcbn,
90
12,000
12,500
35
621
15.2
17,600
90
24,000
25,000
35
1,242
15.2
17,600
Incinerator Specifications
Inlet Hcbn Concentration, %
Residence Time @ Temperature, sec
Inlet Tubeside Temp., °F
Unit Outlet Temperature, °F
Burner A T from Fuel Gas, °F
Thermal Efficiency
25% (max)
0.6
90
1,500
25°F (min)
25% (max)
0.6
90
1,500
25°F (min)
To obtain min burner A T ^
(1)Assumed as toluene
(2) To be obtained with hot recycle gas dilution
415
-------
TABLE 151
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR THERMAL INCINERATORS FOR GRAVURE PRINTING
(WITH HEAT EXCHANGE)
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol %
Effluent Hydrocarbon
%LEL
lb/hr Btu/SCF
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
Small
Large
High Efficiency
Small
12,500
90
12,000
35
621
15.2
44,750
1,500
12,100
-
<31
>95
47,600
5,125
3,100
3,750
3,245
950
1,000
275
1,050
450
1,750
5,960
74,255
Large
25,000
90
24,000
35
1,242
15.2
89,500
1,500
24,200
-
<62
>95
72,350
10,578
3,750
5,850
4,870
1,600
1,654
488
1,200
550
1,750
6,260
110,900
416
-------
FIGURE 116
CAPITAL COSTS FOR THERMAL INCINERATORS
FOR GRAVURE PRINTING
(WITH HEAT EXCHANGE)
500000
CO
oc
O
O
te
8
_i
<
z
o
100000
10000
1000
.s
s^
(Si i
s J^>
J3r
SJ0
^
_/
a
rS
r
r
1000 10000
1
r 1
f
CCJ
•URNKEY) SYSTEM
COLLECTOR
'LUS AUXILIARIES
1 1 l
LLECTOR Of
ill \f
MLY
100000 300000
GAS FLOW, SCFM
417
-------
TABLE 152
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR THERMAL INCINCERATORS FOR GRAVURE PRINTING
(WITH HEAT EXCHANGE)
oo
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
$6/hr
$6/hr
Small
Large
High Efficiency
Small
4,000
1,575
1,575
360
135
495
125
125
1,796
6,520
8,316
10,511
7,426
17,937
Large
4,000
1,575
1,575
360
260
620
125
125
4,334
13,020
17,354
19,674
11,090
30,764
-------
FIGURE 117
ANNUAL COSTS FOR THERMAL INCINERATORS
FOR GRAVURE PRINTING
(WITH HEAT EXCHANGE)
500000.
100000
CO
cc
§
te
8
10000
1000
X
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
10000
GAS FLOW, SCFM
100000
300000
419
-------
TABLE 153
CARBON ADSORPTION PROCESS DESCRIPTION FOR
GRAVURE PRINTING SPECIFICATION
A carbon adsorption system is to remove hydrocarbon emissions from a gravure
printing facility and to provide for their recovery for reuse at the facility. Effluent gas from
each of the presses will be combined and treated in the single adsorption system. Process
conditions and specifications for a small and large facility are tabulated in Table 154.
The system will be of the continuous, regenerative type. Regeneration will be
accomplished with low pressure steam and air. The hydrocarbon to be recovered will be
toluene. Suitable carbon will be selected for this sytem. The system will be designed for
automatic operation but will have manual overrides. In order to insure adequate ventilation,
the ducts leading from each of the presses will be designed for equal pressure losses. Bids will
include the following:
1. Carbon adsorption devices.
2. A booster fan sufficient to handle the total gas effluent from the vent fans over
each press and to overcome the pressure drop across the system's ductwork and
across the carbon adsorption beds.
3. A continuous type filter located before the carbon beds. The filter will remove ink
and dust particles, in order to prevent clogging and/or fouling of the carbon beds.
4. Two hundred fifty feet of rectangular ductwork which will provide for the
collection of the effluent gas from the different presses and provide for their
transport after their exit from the adsorption system. The manifold duct will be
left open at one end in order to provide for capacity differences due to changes in
press operation.
5. An automatic control system which continually measures and records the toluene
level at the outlet of the adsorption system.
6. Appropriate recovery and storage facilities for the hydrocarbon solvent.
7. Dampers.
All items other than the first will be considered auxiliaries.
The adsorption system will be located on the roof and no modifications of the existing
structure will be necessary. Low pressure steam, city water at 90°F, and electric power at
440 v, 220 v, and 110 v are all available within 30 ft of the site.
420
-------
TABLE 154
CARBON ADSORPTION OPERATING CONDITIONS
FOR GRAVURE PRINTING SPECIFICATION
Small Large
Number of Presses 4 12
ACFM/Press 12,450 12,450
Adsorption Equipment Inlet
Gas Rate, ACFM 49,800 149,400
Temperature, °F 90 90
Gas Rate, SCFM 48,000 144,000
Hydrocarbon Solvent
%LEL 35 35
ppm by vol 3,560 3,560
Ib/hr 2,484 7,452
Relative Humidity, % < 50 <. 50
Heating Value, Btu/SCF 15.2 15.2
Performance Requirement
Hydrocarbon Recovery, % >95 >95
421
-------
TABLE 155
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR CARBON ADSORPTION FOR GRAVURE PRINTING
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, R.H.%
Effluent Contaminant Loading
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
ppm
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
(a) Engineering ">
(b) Foundations
& Support
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test J
Other - Carbon
(4) Total Cost
Small
Large
High Efficiency
Small
49,800
90
48,000
50
3,560
2,484
50,990
105
47,836
178
124
95
215,150
9,850
172,567
25,029
422,596
Large
149,400
90
144,000
50
3,560
7,452
152,970
105
143,508
178
372
95
504,516
20,950
325,867
61,901
913,234
*Included in item (1)
422
-------
FIGURE 118
CAPITAL COSTS FOR CARBON ADSORPTION
FOR GRAVURE PRINTING
GO
DC
O
O
te
O
o
O.
<
O
,000,000
lOOjOOO
lf\ /%/N/N
TURNKEY SYSTEM >
COLLECTOR PL
I- AUXILIARIES
I
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423
-------
TABLE 156
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR CARBON ADSORPTION FOR GRAVURE PRINTING
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)
Steam (low pressure)
Carbon make-up 4%/yr
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$.011/kw-hr
$.05/M Gal
$1.00/Mlb
Small
Large
High Efficiency
Small
8,000
2,844
2,844
4,973
3,346
12,833
14,975
74,667
1,001
103,476
114,639
42,260
156,899
Large
8,000
2,844
2,844
10,967
7,427
38,148
44,925
210,667
2,476
296,216
317,454
91,324
408,778
-------
FIGURE 119
5000000
1000000
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ANNUAL COSTS FOR CARBON ADSORPTION
FOR GRAVURE PRINTING
1000
r~ CREDIT FOR
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GAS FLOW, ACFM
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300000
425
-------
TABLE 157
CONFIDENCE LIMITS FOR CAPITAL COST
OF CARBON ADSORPTION FOR GRAVURE PRINTING
Population Size — 20 Sample Size — 3
Capital Cost = $422,629
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $382,846 $462,412
75 345,547 499,711
90 288,152 557,106
95 235,079 610,179
Capital Cost = $913,235
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $753,573 $1,072,900
75 603,877 1,222,590
90 373,531 1,452,940
95 160,533 1,665,940
426
-------
FIGURE 120
CONFIDENCE LIMITS FOR CAPITAL COST
OF CARBON ADSORPTION FOR GRAVURE PRINTING
GO
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GAS FLOW, ACFM
427
-------
REFERENCES
1. U.S. Department of Commerce, U.S. Industrial Outlook 1970,
Washington, Government Printing Office, 1969, Chapter 5.
2. Gadomski, R. R., David, M. P., Blahut, J. A., Evaluation of Emissions and
Control Technologies in the Graphic Arts Industries, Graphic Arts
Technical Foundation, 1970.
3. U.S. Department of Commerce, 1967 Census of Manufacturers
Preliminary Reports, Industry Series, Washington, U.S. Department of
Commerce, 1969.
4. Anon., Printing Plates Magazine, Vol. 56, No. 4, April, 1970, p. 28.
5. Drury, H. F., Total Products Shipments— 1970, Inland Printer/American
Lithographer, Vol. 164, No. 4, Jan., 1970, p. 46-48.
6. Anon., Survey of Gravure Printing, Gravure Technical Association
Bulletin, Vol. 20, No. 2 Summer, 1969, p. 10-24.
7. Cartright, H. M., Jackay, R., Rotogravure — A Survey of European and
American Methods, Mackay Publishing Co., 196, p. 240.
8. Hays, D. R., Official Digest, Vol. 36, No. 473, 1963, pp. 605-624.
9. Bock, R. F., Ink Drying — GATF Research Department Report of
Progress 1969, Pittsburgh, Pa., Graphic Arts Technical Foundation, 1970.
10. 'Heuser, A. R., Friends in Air Conservation in the Graphic Arts Industry,
Gravure, Vol. 15, No. 2, Feb., 1969, pp. 22-25, 45-48.
428
-------
SOAP and DETERGENT
-------
5. SOAP AND DETERGENTS
Soaps and synthetic detergents are two of the most common products in
the Western World. With approximately 14.5 million tons of soap and detergent
produced in 1969,'1) they may be called the most widely used chemical
compounds in the modern world. U. S. production of synthetic detergents
(syndets) in 1968 was reported to be 2.75 million tons; this was 83% of total
soap and detergent consumption which was approximately 3.3 million tons.'1'
Water, which wets unevenly, is not a very efficient cleaning compound.
The major function of all soaps and detergents is to reduce the surface tension
and improve the wetting efficiency of the water. The surface tension prevents
the water from fully contacting the material to be cleaned and removing the
dirt. Soaps and detergents have both hydrophilic and hydrophobic groups. The
hydrophilic group enables the detergent to dissolve in water and reduce surface
tension, while the hydrophobic part contacts the dirt. The dirt is removed by
agitation and prevented from resettling by electrical charges produced by the
detergent.'2'
Soap making is an ancient practice, dating back to Roman civilization.
However, the first synthetic detergent was not made until World War I. Around
1930, long chain alkyl-aryl sulfonates were introduced in the U. S. and began
to compete with soap. In the early 1950's, tetra-propylene benzene sulfonate
(TPBS) dominated the synthetic detergent market. This detergent caused
extensive foam formation in inland waterways. TPBS has a branched alkyl
chain and, consequently, resists biological degradation. In 1965, U. S. detergent
manufacturers switched to linear alkyl sulfonates (LAS), a biodegradable
product with detergency values comparable with TPBS. Recently, the use of
sodium tripolyphosphate as a builder in most detergent formulations has been
suspected of encouraging algae growth in natural waterways, so additional
formulation changes may be expected in the near future.
PROCESS DESCRIPTION
This section will deal mainly with synthetic detergent manufacture. The
major source of air pollution in detergent production is spray drying. The air
pollution problems found in soap making are generally not as severe as those
in detergent making because soap flakes are primarily produced in a drum dryer.
Only one-third of the soap produced is spray dried to flake or powder form.'1'
Modern detergent formulations are extremely varied. The active
429
-------
ingredient, usually linear alkyl benzene sulfonate, alcohol sulfate, alcohol ether
sulfonate, alcohol ethoxylate, or sodium alkenyl sulfonate, comprises a third or
less of the detergent weight. The remainder of the detergent consists of a
sequestering agent, an anti-corrosion agent, an anti-soil redeposition agent, a
foam booster, bleach, a brightener, filler, and in some cases, enzymes.'31
Basically, the manufacture of powdered detergents consists of the
following steps:
1. Sulfation or sulfonation of the raw material (fatty alcohol or linear
alkylate).
2. Neutralization of the acid to produce the sulfate or sulfonate.
3. Blending the sulfonate paste with other ingredients.
4. Spray drying of this mixture.
5. Packaging and storing of the detergent.
In the manufacture of liquid detergents, a foam stabilizer and solubilizer is
blended in before the detergent is bottled. Liquid detergents accounted for 20
to 25% of total syndet production in 1968.
Detergents and soaps may be broken down into three main classes:
1. Anionic detergents — ionize in water to produce a negatively charged
organic ion; used mainly in soaps and powdered synthetic detergents.
2. Nonionic detergents — do not ionize in water; used mainly in liquid
synthetic detergents.
3. Cationic detergents — ionize in water to produce a positively charged
organic ion; not normally classified as detergents, but as germicides.
In 1966, anionic detergents (including soap) represented 74.3% of total
detergent production, nonionic, 20.6%, and cationic, less than 5%.<4)
The most frequently used active ingredient in anionic synthetic detergents
today is linear alkylbenzene sulfonate (LAS). Alcohol sulfatesand alpha-olefin
sulfonates (AOS) are also used. Although AOS consumption in 1968 was about
19% of total sulfonate consumption, it has been discussed as the most serious
430
-------
competition to LAS.*^' Overall routes to these three ingredients are shown in
Figure 121.(2>5) The major feed materials to the detergent manufacturing plant
for these three processes would be linear alkylbenzene, primary alcohol, and
linear paraffin wax (or ethylene), respectively.
Of the nonionic active ingredients in synthetic detergents, ethoxylated
long chain alcohols and to a lesser extent, ethoxylated alkyl-phenols are the
most common. These materials are produced by reacting the linear alcohol or
alkyl-phenol with ethylene oxide in a mole ratio of 1 :(2 to 10).(6)
The sulfonation (or sulfation) of the raw materials in anionic synthetic
detergent production is very similar for the three main processes. Flow sheets
are shown in Figures 122 and 123 for the sulfonationof linear alkyl benzene and
linear alpha-olefins.<2) In the actual sulfonation reaction, a mixture of 4% SOo
(vol/vol air) is generally used. For optimum reaction conditions, this mixture
should be at a pressure of 1.0 to 1.3 atmospheres, a temperature of 100 to
140° F, a dew point of — 58° F, and free of acid mists.121 This S03/air mixture
is usually prepared from one of three reagents. Stabilized liquid sulfur trioxide
is probably the most versatile. It is exclusively used in alpha-olefin sulfonation.
Sulfuric acid, usually in the form of oleum (H2 804 • SOg), and occasionally
sulfur are also used to produce the S03/air mixture.
In some plants oleum or less frequently sulfuric acid is directly mixed
with alkyl benzene to produce the sulfonate. However, large excesses of oleum
and larger excesses of sulfuric acid are required to drive the reaction to
completion, causing these processes to be relatively expensive.'7)
Sulfonation processes are typically composed of a raw material metering
system, a sulfonation reactor, a cooling circuit, a separating circuit, and a
hydrolyzer.
In the manufacture of linear alkyl benzene sulfonate, the linear alkyl
benzene and SOg/air mixture are metered into the reactor at a SOg/raw
material mole ratio of 1.0 to 1.1.(2) The reaction is very quick and exothermic,
and heat must be rapidly removed to prevent discoloration. The heat of
reaction is removed by recycling the reactants through a temperature
controlled heat exchanger. The reaction is completed as the overflow from the
reactor flows through a reaction coil. Although feed materials other than linear
alkyl benzene (alpha-olefins, fatty alcohols) may require different post-treat-
ment, the sulfonation step is much the same.
Typical operating conditions for the sulfonation of linear benzene
431
-------
N)
FIGURE 121
OVER-ALL. ROUTES TO LINEAR ALKYLATE SULFONATES (LAS),
ALPHA-OLEFIN SULFONATES (AOS) AND ALCOHOL SULFATES
LAS
KEROSENE RANGE HYDROCARBONS
MOLECULAR
Y SIEVES
STRAIGHT CHAIN HYDROCARBON
AOS
WAX RANGE CRUDE DISTILLATE
ALCOHOL SULFATES
(
SOLVENT
DEOILING
COCONUT OIL
1. N»OH
OLEFINS
ETHYLENE
STRAIGHT CHAIN PARAFFIN WAX
Cl
UI2
(
1 A D A ETPIfc.1
#
CATALYTIC
DEHYDROGENATION
DEHYDRO f
1
THERMAL
CRACKING
STRAIGHT CHAIN ALPHA OLEFINS
1
1
DISTILLATION
C|5-C|8 ALPHA OLEFINS
I. BENZENE, AICI3
Z. DISTILLATION
I. BENZENE ,HF
2. DISTILLATION
SULFONIC ACID
AND SULTONES
STRAIGHT CHAIN ALKYLBENZENE
(LINEAR ALKYLATE)
I
nc
I
1
I. N«OH,HEAT
2. BLEACHING
SO^OR OLEUM
SODIUM SULFONATE
SULFONIC ACID
NaOH
SODIUM SULFONATE
2.NaREDUCTION
ETHYLENE GROWTH
BY ZIEGLER
CATALYSTS
LAURYL
ALCOHOL
SYNTHETIC
ALCOHOLS
*
PRIMARY
LINEAR
ALCOHOLS
SO3 OR
CHLOROSULFONIC ACID
ALCOHOL SULFATE
SODIUM ALCOHOL SULFATE
-------
FIGURE 122
LOW- AND HIGH-ACTIVE: SULFONATION USING OLEUM
BYPASS FOR LOW ACTIVE
SULFONATION OPERATION
ALKYL
BENZENE
REACTOR
OLEUM
CO
CO
SULFONATION
COOLER
PROPORTIONING
PUMP
MIXING
PUMP
ALKYL
BENZENE
SULFONATION
NEUTRALIZATION
COOLER
MIXING
PUMP
WATER
ALKALI
SULFONATION
DILUTION
SULFONIC ACID
CONCENTRATION
NEUTRALIZATION
-------
FIGURE 123
ALPHA - OL-EFIN SULFONATION FLOWSHEET
ALPHA-
OLEFIN
PROPORTIONING
PUMP
LIQUID
FILM
REACTOR
BLEACH
AND pH
MIX TANK
i r
1 1
l-J
SULFURIC
ACID
BLEACH
DIGESTER
CYCLONE
COOLER
PUMP
DEMISTER
ALKALI
PROPORTIONING
PUMPS
SODIUM
HYPOCHLORITE
SODIUM
ALKENE
SULFONATE
HYDROLYZER
PUMP COOLER
-------
alkylates are given in Table 158.(7) Reactor capacities range from less than 1
million Ib/yr to more than 20 million Ib/yr of sulfonic acid, based on 6000
hr/yr of operation.17)
The reactor effluent consists mainly of sulfonic and sulfuric acids. The
excess sulfuric acid is usually removed by first diluting it with water; after
dilution, the difference in densities is large enough to permit phase separation
and the spent acid is removed after a residence time of about 15 minutes.
The sulfonic acid is next neutralized to form the sulfonate. Caustic soda is
generally used. The neutralization reaction is also rapid and extremely
exothermic and the reactants are recirculated through a cooler. The solids
content of this slurry will normally be about 46%.(2)
In the sulfation of primary alcohols, chlorosulfonic acid is usually
employed as the sulfating agent.'81 Gaseous HCI is liberated during sulfation
and this necessitates absorption and disposal of the acid, which is extremely
corrosive. For this reason the reaction is usually carried out batchwise in
glass-lined kettles at about 86°F.(9> Sulfuric acid can be used in alcohol
sulfation but because of the reverse hydrolysis reaction, equilibrium conversion
to the sulfonic acid is only 65%, and a large excess of acid must be used. It
appears that SO^ gas may be the best method for sulfation, as well as for
sulfonation. An excess of 3.5% SOg (converter gas) provides good sulfation of
linear alcohols (lauryl or synthetic), with a sulfation time of 40 minutes and
mean temperature of 95°F.(8)
After sulfonation (or sulfation), the sulfonate paste is blended with the
numerous detergent additives. The dry ingredients are weighed and fed to a
screw conveyor which acts also as a mixer. The conveyor transports the dry
ingredients to the main mixer, where they are blended with the liquid
ingredients (including the sulfonate paste). The blended materials are then
conveyed to an aging crutcher, where the slurry is aged and further mixed.
Final drying is done in a spray dryer.
Synthetic detergent and soap powders are formed by spray drying. Since
World War II, vacuum spray dryers have also been used to perform the
functions of hot-air dryers in soap drying.'12) A flowsheet for a typical
detergent spray drying plant is shown in Figure 124.'21
Neat soap is generally about 60 to 70% solids, while the detergent
sulfonate paste is usually 55 to 60% solids. The paste comes from the blending
unit at a temperature of 120 to 175°F, is filtered, and pumped at pressures up
435
-------
TABLE 158
TYPICAL OPERATING CONDITIONS FOR
CONTINUOUS SULFONATING OF LINEAR ALKYLATE(7)
Temperature, °F
Linear alkylate feed 65-85
Vaporized S03 - dry air mixture 100-110
Product sulfonic acid 120-140
Flow rates, Ib/hr
Linear alkylate feed 1240
Vaporized S03 433
Dry air feed (SCFM) 800
Product sulfonic acid 1670
Molar ratio, S03:alkylate 1.03:1.0
SO3 carried by air, vol % 4
Aging time, minutes 15
436
-------
FIGURE 124
TYPICAL SPRAY DRYING PLANT
TO
ATMOSPHERE
SUURRY
TO
ATMOSPHERE
CO-CURRENT
AIR
STREAM
CYC l_ ONES
SPRAY
DRYER
COUNTERCURRENT
AIR STREAM
CYCL-ONE
ORANUI-ATOR
DETERGENT
PRODUCT
-------
to 70 atmg through feed nozzles at the top of the spray tower.121 The towers
are usually larger than 14 ft in diameter and about 60 to 100 ft high, with a
60° bottom cone. The nozzles spray the paste into a hot drying air stream.
When the paste reaches the right density, it settles to the bottom of the dryer
and is removed by a belt conveyor to packaging. Moisture contents of the dry
powder bead are in the 3 to 18 wt.% range.'2' The bead is rather coarse,
spherical, stable, and has a large surface area.
The air for drying is taken from the atmosphere and heated in an oil or gas
fired furnace to 645 to 710° F. Three different air systems are generally
employed in spray dryers:
1. Parallel or co-current
2. Countercurrent
3. Mixed air flow
In the co-current system, hot air is introduced at the top of the tower and
flows down the tower with the sprayed detergent particles. In the discharge
cone, the drying air is separated from the beads and drawn through a cyclone.
Cool- air, drawn in at the bottom of the tower, cools the beads and separates
the hollow beads from the fines, which are collected in the cyclone. The
product produced in this system will have density of 0.08 to 0.15 g/cc and a
moisture content of 3 to 8%.(2) The countercurrent system is most often used
in spray drying. Hot air enters at the bottom of the tower and contacts the
downward flowing detergent beads. An average tower will dry 10,000 ton/yr
with larger towers handling up to 100,000 ton/yr.'3' The product bead will
have a 0.18 to 0.4 g/cc density and a 6 to 15% moisture content.'2' In the
mixed air flow system a reduced amount of hot air enters through the top,
while a large quantity of cold air enters at the bottom. The upper part of the
tower consequently operates as a co-current unit, while the lower part acts as a
countercurrent unit. The powder produced is in the form of a hollow bead
containing a very high percentage of water of crystallization; the water content
is usually 20 to 25%.
The detergent beads are conveyed from the bottom of the drying tower to
a pneumatic air lift. The beads are cooled as they travel up the air lift. At the
top of the lift they are separated from the air stream by a cyclone or gravity
separator and fall to a vibrating screen which removes the oversized particles.
The detergent is then sprayed with perfume and packaged.
438
-------
The manufacture of soap is a bit simpler. Soap consists of the sodium or
potassium salts of various fatty acids, usually in the C-|2 to C-|g range. Soap is
usually manufactured either by saponification of fats or the hydrolysis of fats
followed by neutralization of the resultant fatty acids. The trend today is
toward the latter process, although direct saponification is much older and still
widely used.
The main raw materials used in soap manufacture are tallow, greases, and
coconut oil. These are the fatty materials which are hydrolyzed, or split, into
fatty acids and glycerine. In some cases, however, free fatty acids are used as
raw material and are neutralized directly. Fatty acids are usually produced
from fats in one of three processes: Twitchell, batch autoclave, or continuous
high-pressure process. The Twitchell process is the oldest. The fats are boiled
for 12 to 48 hours at 212 to 220° F in an open tank with 0.75 to 1.25%
Twitchell's reagent (alkyl-aryl sulfonic acids) and 0.5% sulfonic acid.
Hydrolysis is 85 to 98% complete.11 °- 11' A 5 to 15% aqueous glycerine
solution is drawn off, neutralized and concentrated by evaporation.11 0) The
batch autoclave process is a faster process (5 to 10 hr) and operates at pressures
from 75 to 150 psig and temperatures of 300 to 350° F in the presence of 1 to
2% zinc, calcium, or magnesium catalyst.'11' In the continuous countercurrent
process, the fats (or fatty oil) are first deaerated under a vacuum. Deaerated
fatty oil is charged to the bottom of the hydrolyzing tower. Deaerated water
enters at the top of the tower. The oil at the bottom extracts the fatty material
dissolved in the glycerine phase, while the water extracts the glycerine dissolved
in the fatty phase. Final splitting occurs at about 485° F and 600 to 700 psig;
direct high pressure steam is used for heating. The fatty acids exit through the
top and the glycerine at the bottom.
The fatty acids produced in one of these processes (mainly the continuous
countercurrent process) are now neutralized, usually with sodium hydroxide.
This process is shown in Figure 125.<10) The crude fatty acids from the
hydrolyzing tower first have the water flushed off, and then are purified by dry
vacuum distillation. The distillate is then condensed and neutralized in a high
speed mixer with a NaOH solution. The neat soap, or soap of the higher fatty
acids, is discharged at temperature greater than 200° F to a blending tank. This
soap contains 0.02 to 0.10 wt.% free caustic as Na20, 0.3 to 0.6% salt, and
about 30% moisture. The soap is now dried in hot-air dryers, spray dryers, or
steam heated tubes. Most soap is dried in hot-air dryers. Soap used in chips,
bars and flakes is dried this way and then milled and broken into chips. The
chips can be charged to mixers where other ingredients (perfume) are added.
The chips are now finally rolled, and finished as bars or flakes.111) Soap
powders are produced by spray drying, which has been previously discussed.
439
-------
FIGURE 12i>
CONTINUOUS PROCESS FOR SOAP MANUFACTURE
STEAMS
STEAM
FLASH
TANK
STEAM
1
1
>N DENSER
EXCHANGER
HYDROLYZER
FATS AND
CATALYST
HIGH VACUUM
STILL
CAUSTIC
SODA
MIXER-
NEUTRALIZER
COO LINO
WATER
DISTILLATE
RECEIVER
»
SOAP
STORAGE
BOTTOMS ,TO
STORAGE S.
RECOVERY
I U
CONVENTIONAL
SOAP FfMISHING I
BAR,FLAKE OR
POWDER | CUTTER
STEAM
CRUDE
3LYCERINE
EVAPORATORS
£
HIGH
PRESSURE
PUMP
STEAM
FREEZER
PACK OFF
-------
This entire process takes about 24 hours.
In contrast, the kettle or batch processes take several days to produce an
equivalent amount of soap. The major batch process is the "full boiled
process". This process employs direct saponification of fats, and consists of
several steps, or "changes." The fats are first melted and mixed with 12.6%
NaOH in the soap kettle, which is heated with open steam. After 3 to 4 hours,
a sodium chloride solution is added until a concentration of 10 to 12% is
achieved and the soap mixture separates distinctly into soap and spent lye. The
steam is removed and the lye, containing 1 to 8% glycerine, is settled and is
drawn off. The soap is again boiled and water is added until the mixture is
again creamy; more caustic may be added and the process repeated. These
series of processes are called the "brine changes." On the third day, the last of
the oil and fats are saponified with 18.6% NaOH; the mixture is heated with
closed steam until separation and then allowed to cool for 3 to 4 hours. The lye
is run off and used in saponification of a new batch of fats; this step is called
the "strengthening change." In the "finishing change," the soap is again heated
and water is added, and the mixture is boiled. Upon cooling, the soap separates
into 3 layers. The top layer is neat soap, the middle layer consists of nigre (a
dark, alkaline soap), and the bottom layer is a mixture of soap and lye. The
neat soap is finished as described above. The nigre is used either in the next
batch or degraded and used in darker, cheaper grades of soap, and the lye is
neutralized and recycled after the glycerine has been removed. The Sharpies
process is a continuous full-boiled process which takes 2 hours to produce neat
soap. This process contains the same stages as the batch process, but the flow
of lye is countercurrent to the flow of fat and oil. The soap, lye, and nigre are
separated in 15,000 rpm centrifuges which develop a centrifugal force 13,200
times that of gravity.'10>
PROCESS CHEMISTRY
Many chemical reactions are involved in soap and detergent manufacture.
The reactions involved in soap manufacture can be summarized as follows:'1 ol
1. Saponification of fats
3 NaOH + (C17H35COO)3C3H5 +
Caustic Soda Glyceryl Stearate
3C17H35COONa + C3H5(OH)3
Sodium Stearate Glycerine
441
-------
2a. Hydrolysis of fats
(C17H35COO)3C3H5 + 3H20 -»• 3C17H35COOH + C3H5(OH)3
Glyceryl Stearate Stearic Acid Glycerine
b. Neutralization of fatty acids
C17H35COOH + NaOH -»• C17H35COONa + H20
Stearic Acid Caustic Sodium Stearate
Although Stearate has been shown in these reactions, other fats with
carbon chains of 12 to 18 atoms, such as oleate, laurate, or palmitate are also
present.
The formation of sulfonated detergents takes place mainly by the
reactions summarized below.
1. Alkyl-benzene sulfonation:(2>
a. Sulfonation stage, 98+% conversion
+ H9S04
S03H Z *
Alkyl Benzene, Oleum Sulfonic Acid 96%Sulfuric
C^QtoC-|4 acid
* An S03-air mixture is often used instead of oleum.
b. Neutralization
+ NaOH -> I 1+ Na9SOd + 3H9O
\ x/\
S03H S03Na
"Sodium alkyl benzene sulfonate
442
-------
2. Alpha-olefin sulfonation:'2'
a. Sulfonation, 96 to 98+% conversion
R-CH =
linear alpha-olefin,
C14toC18
R-CH = CH2 + S03 •* R'-
linear alpha-olefin
H = CH-(CH2)n-S03H
alkene sulfonic acid
H;C
+ R-CH
\
so-
Sultones
b. Neutralization
7
R-CH
\
+ NaOH
\
CH
Sultone
SO
R' - CH2 - CH(OH) - CH2 - CH2 - S03 Na
Sodium hydroxy sulfonate
R - CH2 - CH = CH - CH2 - S03 Na
Sodium alkene sulfonate
R'-CH = CH-(CH2)n-SO3H + NaOH ^ R'- CH = CH - (CH2)n - SO3Na + H2O
Alkene sulfonic acid Sodium alkene sulfonate
Composition of final product:'5'
50 to 60% alkene sulfonate
40 to 50% hydroxy sulfonate
3. Alcohol sulfation:
a. Sulfation'81
I. With chlorosulfonic acid; 95 to 98% conversion'31
R-OH
Primary linear
alcohol, Cj2 to
CIS03H
Chlorosulfonic
acid
R-0-S03H + . HCI t
Alkyl sulfuric acid
443
-------
II. With sulfur trioxide, 95 to 98% conversion
R - OH + S03 -»- R - 0 - S03H
3.5%
excess
III. With sulfuric acid (oleum or monohyd rated), 65% conversion
R - OH + H2S04 £ R - 0 - S03H + H20
70%
excess
b. Neutralization
I. R-0-S03H + NaOH -> R - 0 - SO3Na + H20
Sodium alcohol sulfate
II. R-0-S03H + H2S04 + SNaOH
4. Alcohol ethoxylation and sulfation:'6- 10)
a. Ethoxylation
R-0-S03Na
55%
Na2S04 + 3H20
45%
R-CHoOH
Linear alcohol,
R -CH20(CH2CH2O)nH
Alcohol ethoxylate
C12toC
18
Ethylene oxide
n = 2 to 10 moles
or alkyl
(=Cg) phenol
b. Sulfation and Neutralization
R-CH2O(CH2CH20)nH +
Alcohol ethoxylate
R = CiitoC-|7
n = 2 to 4
R-CH2O(CH2CH2O)nS03H +
S03 -> R-CH2O(CH2CH2O)nSO3H
NaOH -* R-CH20(CH2CH20)nS03Na
Alcohol ethoxy sulfate
H0
444
-------
RAW MATERIALS AND PRODUCTS
The raw materials for soap manufacturing consist mainly of tallow,
greases, coconut oil, and free fatty acids. Tallow is obtained mainly by the
steam rendering of cattle fat; greases are obtained from the steam rendering of
the fats of hogs, smaller domestic animals, and from garbage.
An extremely wide range of compounds, both natural and synthetic may
be classified as raw materials for the manufacture of synthetic detergents. The
active ingredient in detergents comprises about 14 to 37% of the total product;
the remainder is composed of builders, fillers, etc., which are not generally
produced by the detergent manufacturers. Table 159 shows typical formulations
of modern detergent products.'31
The basic raw material used in the manufacture of LAS is a linear alkyl
benzene, mainly dodecyl alkyl benzene. This alkylated benzene is produced by
either dehydrogenation or chlorination of a n-paraffin, followed by Friedel-
Craft alkylation.
Alpha-olefin sulfonate is made by employing a linear paraffin wax or
ethylene to produce a C-jg to C-jg alpha-olefin, which is then sulfonated. In the
production of alcohol sulfates or ethoxylated sulfates, straight chain primary
alcohols (C-|2 to C-jg) are usually the feed material. Lauryl alcohol, derived
from coconut oil, is often used, but it is being replaced by synthetic alcohols
made by either ethylene growth over Ziegler catalysts or the reaction of olefins
with carbon monoxide and then hydrogen.(6)
The major materials used in sulfonation or sulfation are, as previously
mentioned, stabilized liquid sulfur trioxide, oleum, chlorosulfonic acid, or
sulfur. Alcohol ethoxylates are prepared by reacting ethylene oxide or propy-
lene oxide with linear alcohols. Neutralization of the sulfonic acid is carried out
by an agent which does not produce gaseous side products. Sodium hydroxide
is generally used, but potassium, lithium, magnesium, and ammonium hydrox-
ides, as well as trietanolamine are also employed.
Soaps and synthetic detergents are available in powder, liquid, bar, flake
and chip form. They are used primarily as cleaning compounds, and have a
large range of home and industrial applications. Major products include laundry
detergents, toilet soap, and dish washing detergents used in the home.
Detergents are also used in textile finishing, dyeing, laundries, dairies, and
metal cleaning. They are used as a frothing agent in wallboard manufacture and
as an entraining agent in portland cement. Soap is used in the manufacture of
445
-------
&
TABLE 159
TYPICAL SYNTHETIC DETERGENT FORMULAS'31
Heavy-duty
product
U.S., Canada
Active ingredient
(e.g., alkylbenzene
sulfonate, fatty alcohol
sulfate)
Foam booster
(e.g., lauryl alcohol,
cocomonoethanolamide)
Sodium tripolyphosphate
14 to 20%
1.5 to 2%
40 to 60%
Anti-soil redeposition agent
(e.g., sodium carboxy
methyl cellulose) 0.5 to 0.9%
Anti-corrosion agent
(e.g., sodium silicate)
Optical brightener
Enzymes
Moisture
5 to 7%
0.30 to 0.75%
0.20 to 0.75%
6 to 12%
Filler (e.g., sodium
sulfate)
Other ingredients
remainder
Light-duty
powders
all countries
25 to 32%
2 to 15%
0.02 to 0.08%
1 to 4%
60 to 68%
Light-duty
liquids
all countries
30 to 37%
5 to 12%
Detergent
laundry bars
20 to 25%
6 to 9%
15 to 25%
0.3 to 0.5%
3 to 8%
0.05 to 0.25%
3 to 8%
15 to 30%
15 to 20%
-------
synthetic rubber, textile processing and as an emulsifier in cold cream and
cosmetic preparations. Glycerine, which is a major by-product of soap
manufacture, is used in the manufacture of alkyd resins and explosives, as a
humectant in tobacco, as a plasticizer in cellophane, and in products such as
cosmetics, dentrifices, corks, gaskets, and Pharmaceuticals.'10)
NATURE OF THE GASEOUS DISCHARGE
In soap manufacturing plants, paniculate and/or odors are the main
atmospheric contaminant. The odors are mostly due to the storage and
unloading of the fat charge stock particularly rendered fats and greases, and the
vacuum distillation of higher molecular weight fatty acids. Excepting spray
dryers, dust emissions in soap making cause little more than dust problems
within the plant.
The main source of air pollution in a detergent plant is the exhaust air
from the spray dryer. Dust from dry product handling and acid fumes from the
sulfonation process can also be problems.
The exhaust air from a countercurrent spray dryer will be at a
temperature of 150 to 250° F, typically about 210 to 220° F. The air is
exhausted to a collector, either a cyclone or a wet scrubber, and the collected
particles (in the form of fines or in a slurry) are recycled to the process. The
spray dryer is essentially an evaporator, reducing the moisture content from
about 40% to between 6 and 15%. The wet bulb temperature of the exhaust gas
before entering the collector will be 120 to 150°F and the paniculate dust
loading will be in the 3 to 7 gr/SCF range. This paniculate content will depend
on the tower rates, the fineness of the sprays, the characteristics of the specific
product being dried and other variables. The particles will be rather large,
approximately 50% being greater than 40 microns.113) The composition of the
particles will be very close to that of the finished product, with the exception
that sodium perborate, enzymes, and organic foam boosters are not present. A
problem is caused by the great amount of moisture evaporated, which is
discharged in the exhaust gas and condenses in the atmosphere, forming a dense
white plume.
Detergent formulations have recently been undergoing changes in response
to public concern over the possible connection of phosphates to algae growth
in inland waterways. As a result, the industry trend has been toward
non-phosphate formulations. It is speculation as to the make-up of the new
detergents, but the emphasis appears to be on non-ionic surfactants such as
447
-------
alcohol ethoxylates.'14' At any rate, these new formulations produce problems
in spray dryer emission control. The spray dryer emits a blue haze which has
not been controlled by conventional technology. This haze is believed to be a
sub-micron organic aerosol mist. As the scope of this contract is limited to
conventional emission control technology, only the phosphate detergent
pollution problem will be dealt with in detail.
The pneumatic air lift used to cool and convey the dried product contains
the potential for sizable paniculate emissions. Paniculate rates from the
separating device at the top of the lift average about 3 to 4% of the amount of
beads conveyed. The air used in the pneumatic lift will be approximately 1
cfm/lb/hr of product and will have a temperature of near 100°F.(13)
There are various gaseous contaminants released during the sulfonation
processes. In the burning of sulfur to produce the SC^-air sulfonating mixture,
some of the SC>2 is not converted to SOg. This will result in a small amount of
sulfur dioxide emission. If oleum is used as the sulfonating agent, a small
amount of acid vapor will escape from the unloading, storage, sulfonating,
aging, and neutralization equipment. When chlorosulfonic acid is used in the
sulfation process, large quantities of gaseous hydrogen chloride are produced
and must be disposed of.
POLLUTION CONTROL CONSIDERATIONS
The control of odors in a soap and detergent manufacturing plant,
compared to the control of product paniculate, is a rather simple problem. The
majority of odor emissions in soap making plants will come from the vacuum
type steam stills in the neutralization process, or the soap kettles in the
full-boiled process. These odors may be controlled by spray condensers or.
surface condensers and the noncondensibles vented to the firebox of a
continuous boiler.'1 3) The odor level from detergent spray dryers will be about
four or five odor units/SCF. Although usually this will not constitute a
problem, discharging the exhaust gas at a high velocity from a tall stack will
greatly lessen the chance of the plume reaching ground in any noticeable
concentration.'13)
In the control of paniculate emissions from spray dryers, cyclones are
frequently employed, as the fines from the dryer amount to an economically
recoverable portion. The cyclones used are high efficiency (90% or better) and
relatively high pressure drop (4 to 5 in. w.c.), and are used alone or with one or
more additional units in series. Two-stage cyclone collectors operating at 12 in.
448
-------
w.c. are reported to obtain collection efficiencies of 99%. The small tube type
of cyclone is not usually employed. The cyclones are usually carefully insulated
to prevent solids build-up.
The gases discharged from a single cyclone will generally have a particulate
loading of 0.3 to 0.6 gr/SCF. Much of this weight will be accounted for by a
few large particles which escape the cyclone.(13) This level of particulate
loading is not economically recoverable, but may be in violation of many
emission standards. Therefore, some form of subsequent control equipment
will be required. A two-stage cyclone will have emission loadings in the order of
0.1 gr/SCF.
Problems may be encountered when fabric filters are used as control
devices for detergent drying towers, as the exhaust gas is very humid and the
product particles are sticky at high temperatures. These conditions can cause
caking and build-up problems in the filter.
Wet scrubbing seems to offer the best means of reducing the particulate
loading of the cyclone exhaust gas. Spray chambers, centrifugal impingement
scrubbers, and Venturi scrubbers have all been used. Velocities in spray
chambers should be a maximum of 250 ft/min to prevent water entrainment;
scrubbing liquid rates as low as 1 to 2 gpm for every 1000 cfm of exhaust are
satisfactory. Emission concentrations of about 0.15 gr/SCF are normal for
spray chambers. Venturi scrubbers would use a scrubbing liquid rate of about 8
to 10 gpm/1000 acfm. A medium pressure drop (8 to 10 in. w.c.) Venturi
scrubber would discharge air with particulate loadings as low as 0.02 to 0.03
gr/SCF. If a low gas pressure drop (3 to 5 in. w.c.) were used, the particulate
loading would be about 0.1 gr/SCF.(1 3> To prevent foaming in the scrubber, a
high detergent concentration should be maintained in the recirculated liquid;
40 to 45 wt.% solids is a typical range.
The emissions from the pneumatic air lift represent an economically
important fraction of the product. This 3 to 4% fraction is equivalent to a grain
loading of 3.5 to 4.7 gr/ACF in the separator exhaust. The usual method of
recovering these fines is the use of a fabric filter. Filter caking is not as much of
a problem here as the detergent beads are less sticky at lower temperatures.
449
-------
450
-------
SPECIFICATIONS AND COSTS
Abatement system specifications have been written to control the
emissions from two sources in a detergent manufacturing plant. The first of
these sources is the spray dryer vent. Both wet scrubber and fabric filter
systems have been specified. Each system is based upon the presumption that
the detergent being made is of the conventional high phosphate variety and,
therefore, no hydrocarbon mist problem exists. Cost data and equipment
specifications for these two systems are presented in Tables 160 to 170 and
Figures 126 to 134.
The second source for which specifications have been written is the dry
product handling operation which transfers spray dried product from the spray
dryer to the storage facility. Transfer is done by pneumatic conveying in which
the air both transports and cools the detergent product. The single abatement
device specified for this application is the fabric filter. Cost data and
specifications are presented in Tables 171 to 175 and Figures 135 to 137.
451
-------
TABLE 160
WET SCRUBBER PROCESS DESCRIPTION FOR
SOAP AND DETERGENT SPRAY DRYING SPECIFICATION
The wet scrubber is to remove entrained detergent particles from the exhaust gas of a
gas-fired spray dryer producing conventional phosphate detergents. The flow of air and
detergent in the spray dryer is countercurrent. Detergent product is collected at the bottom
of the spray drying tower and sent to storage by a conveyor system. The exhaust gases leave
the tower at the top.
The exhaust gas from the spray dryer will be brought to a fan located outside of the
building. The fan outlet is to be five feet above grade. The wet scrubber will be located
beyond the fan in an area free of space limitations. The scrubber is to be designed to
withstand the discharge pressure developed by the fan. The ducting to the scrubber should
be insulated to alleviate build-up.
The scrubber will recirculate a slurry of 40 to 45 wt.% solids content in order to
minimize foaming problems in the unit. Fresh water is available at the site for make-up.
Slurry withdrawn from the unit will be returned to the detergent manufacturing process.
The temperature of the slurry in the recycle tank should be kept in the range of
approximately 13GPF.
The scrubbing system will include:
1. A wet scrubber equipped with suitable connections for periodic cleaning of solids
build-up.
2. Carbon steel construction with manufacturer's standard prime paint applied.
3. A fan capable of overcoming the system pressure drop at the design flow rate
while operating at no more than 90% of the maximum recommended speed. The
fan motor shall be capable of driving the fan at the maximum recommended speed
and the corresponding pressure differential at 20% over the design flow rate.
4. Pumps capable of handling slurrys at the design solids content.
5. A fifty foot stack following the scrubber.
All equipment other than the scrubber should be considered auxiliary equipment.
452
-------
TABLE 161
WET SCRUBBER OPERATING CONDITIONS FOR
SOAP AND DETERGENT SPRAY DRYING SPECIFICATIONS
Two sizes of wet scrubbers are to be quoted for each of two efficiency levels. Vendors'
quotations should consist of four separate and independent quotations.
Dryer Capacity, Ib/hr
Process Wt., Ib/hr
Inlet Gas to Scrubber
Flow.ACFM
Temperature, °F
Flow, SCFM
% Moisture (vol)
Solids Rate, Ib/hr
Solids Loading, gr/DSCF
Scrubber Outlet Gas
Volume, ACFM
Temperature, °F
% Moisture (vol)
Small
20,000
30,000
30,290
210
23,960
15
1,298
7.44
27,450
134
17
Large
80,000
120,000
121,150
210
95,840
15
5,192
7.44
109,800
134
17
Outlet Solids Rate. Ib/hr
Outlet Solids Loading, gr/DSCF
Efficiency, wt.%
Scrubber, &P
Case 1 - Medium Efficiency *
25.2
0.14
98.04
10 in. w.c.
Case 2 — High Efficiency *
Outlet Solids Rate, Ib/hr
Outlet Solids Loading, gr/ACF
Outlet Solids Loading, gr/DSCF
Collection Efficiency, wt. %
Scrubber, A P
2.35
0.01
0.0135
99.82
40 in. w.c.
40.0
0.06
99.23
10 in. w.c.
9.41
0.01
0.0135
99.82
40 in. w.c.
*See page 6 for definition of efficiency levels.
453
-------
TABLE 162
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR SOAP AND DETERGENT SPRAY DRYING
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant 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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
•
(4) Total Cost
Medium Efficiency
Small
30,290
210
23,960
15
5.00
1,298
27,450
134
24,492
17
0.11
25.2
98.0
28,500
13,750
52,300
94,550
Large
121,150
210
95,840
15
5.00
5,192
109,800
134
97,970
17
0.04
40.0
99.3
69,300
34,100
94,400
197,800
High Efficiency
Small
30,290
210
23,960
15
5.00
1,298
27,450
134
24,492
17
0.01
2.35
99.8
28,000
22,275
67,050
117,325
Large
121,150
210
95,840
15
5.00
5,192
109,800
134
97,970
17
0.01
9.41
99.8
62,650
53,650
124,450
240,750
454
-------
TABLE 163
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR WET SCRUBBERS FOR SOAP AND DETERGENT SPRAY DRYING
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
$.011/kw-hr
$.25/M gal
Medium Efficiency
Small
8,000
1,800
3,975
1,825
5,199
1,140
6,339
13,939
9,455
23,394
Large
8,000
1,800
5,660
2,925
38,500
4,560
43,060
53,445
19,780
73,225
High Efficiency
Small
8,000
1,800
5,100
2,485
22,880
2,578
25,458
34,843
11,733
46,576
Large
8,000
1,800
7,500
4,005
86,790
9,660
96,450
109,755
24,075
133,830
CJI
Ol
-------
FIGURE 126
CAPITAL COSTS FOR WET SCRUBBERS
FOR SOAP AND DETERGENT SPRAY DRYING
(MEDIUM EFFICIENCY)
500000
100000
CO
cc
o
o
te
8
_i
<
t
0.
o
10000
1000,
TURNKEY SYSTEM
COLLECTOR PLUS
AUXILIARIES
COLLECTOR ONLY
1000
10000
GAS FLOW, ACFM
100000
300000
456
-------
FIGURE 127
ANNUAL COSTS FOR WET SCRUBBERS
FOR SOAP AND DETERGENT SPRAY DRYING
(MEDIUM EFFICIENCY)
500000
CO
oc
O
O
O
O
100000
10000
1000
(OF
(
»EF
:AF
T(
!A
Jll
31
Tl
'A
•fi
N
L
^L
G
(
COST
COST PL
:HARGES)
us>^
/
/
OPERATING CO5
/
?T
/
'
/
/
A
f
A
/
/
/
s^
s^
yf _/
' /
of
'
1000 10000 100000 300000
GAS FLOW, ACFM
457
-------
500000.
FIGURE 128
CAPITAL COSTS FOR WET SCRUBBERS
FOR SOAP AND DETERGENT SPRAY DRYING
(HIGH EFFICIENCY)
100000
CO
DC
fc
o
o
a.
<
o
10000
1000
TURNKEY SYSTEM
COLLECTOR PLUS
AUXILIARIES
COLLECTOR ONLY
1000
10000
GAS FLOW, ACFM
100000
300000
458
-------
FIGURE 129
ANNUAL COSTS FOR WET SCRUBBERS
FOR SOAP AND DETERGENT SPRAY DRYING
(HIGH EFFICIENCY)
500000.
100000
CO
cc
o
Q
te
o
o
10000
1000
TOTAL COST-
OPERATING COST PLUS^
"""CAPITAL CHARGESnfer"
OPERATING COST
10000
GAS FLOW, ACFM
100000
300000
459
-------
TABLE 164
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS FOR SOAP AND DETERGENT SPRAY DRYING
(MEDIUM EFFICIENCY)
Population Size - 20 Sample Size - 2
Capital Cost = $94,550
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $ 90,142 $ 98,958
75 84,787 104,313
90 74,307 114,793
95 62,987 126,113
Capital Cost = $197,800
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $168,127 $227,473
75 132,086 263,514
90 61,540 334,060
460
-------
FIGURE 130
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS FOR SOAP AND DETERGENT SPRAY DRYING
(MEDIUM EFFICIENCY)
500000
CO
DC
O
Q
te
8
Q.
<
O
100000
10000
1000
SJ
&
~^k
~€
£
' ^
r
»•-.
X
^
^
_—•
X
/
^
**
-mm.
/
4
*
'
^
•mm
/
f
'
«•
r;
X
•»»
X
• '
«
^
y
^
^
•
X
^ x'
x,
<#^
^'
"•e- — -
90%
75%
VIE AN
75%
90%-
1000 10000 100000 3000G
GAS FLOW, ACFM
461
-------
TABLE 165
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS FOR SOAP AND DETERGENT SPRAY DRYING
(HIGH EFFICIENCY)
Population Size - 20 Sample Size - 2
Capital Cost = $117,325
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $92,036 $142,614
75 61,321 - 173,329
90 1,200 233,450
Capital Cost = $240,600
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $239,083 $242,117
75 237,241 243,959
90 233,635 247,565
95 229,740 251,460
462
-------
FIGURE 131
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS FOR SOAP AND DETERGENT SPRAY DRYING
(HIGH EFFICIENCY)
500QQO.
cc
<
ws
O
O
_i
<
CL
<
O
100000
10000
1000
90% 1
75% .
MEAN •
^
/
75% '
91
)% (
>— '
J-—
^
/
f
J
/
1
1
1
p
•• •
X
y
/
I
1
1
1
r
m -
X
/
/
/
*
f
•
^
^
/
;
i
1
^M
•*
^«
/
/
1
/
*
•
**
y
/
m
&
04
I
/
^
^ /
/
/
/
1000 10000 100000 30000
GAS FLOW, ACFM
463
-------
TABLE 166
FABRIC FILTER PROCESS DESCRIPTION FOR
SOAP AND DETERGENT SPRAY DRYING SPECIFICATION
The fabric filter is to remove entrained detergent particles from the exhaust gas of a
spray dryer processing conventional phosphate detergents. The flow of air and detergent in
the dryer is countercurrent. The dryer is fired by natural gas. Before entering the filter, the
dryer exhaust gas passes through one or more high efficiency cyclones with a combined
efficiency of 90%. The recovered fines are returned to the process.
The exhaust gas from the cyclones will be brought to the filter by means of a fan. The
fabric filter is to be located outside of the building in an area free of space limitations. The
fan is to follow the filter and discharge into the base of a thirty foot stack. The ducting to
the filter should be insulated to alleviate build-up.
The fabric filter is to consist of a minimum of five compartments and will allow for
isolation of an individual compartment for cleaning during operation. Any four of these
compartments should be capable of handling the full flow at designed differential pressure.
Each section should also be capable of isolation for maintenance and have provisions for
personal safety during filter operation. The collecting process is to be continuous and should
include the following:
1. Pulse jet fabric filter or equal, fully insulated, top removal design, compart-
merited as described above, with a maximum air-to-cloth ratio of 6/1 and a
design differential pressure of 6 in. w.c.
2. Insulated hoppers with a minimum side angle of 60° and a manual slide gate at the
screw conveyor for isolation. The hopper should be strong enough to support a
full load although in routine operation the hopper will not be full.
3. Insulate and heat trace entire system ductwork.
4. Carbon steel construction with manufacturer's standard prime paint applied.
5. An insulated screw conveyor equipped with a single rotary air lock.
6. A fan, located downstream of the filter sized with 20% excess capacity when
operating at the design pressure and 90% of the maximum recommended speed.
464
-------
TABLE 167
FABRIC FILTER OPERATING CONDITIONS FOR
SOAP AND DETERGENT SPRAY DRYING SPECIFICATION
Two sizes of fabric filters are specified for the "high efficiency" level. Vendors'
quotations should 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.
Dryer Capacity, Ib/hr
Process wt, Ib/hr
Inlet Gas to Primary Collector
Flow, ACFM
Temperature, °F
Flow, SCFM
% Moisture (vol)
Inlet Sol ids Rate, Ib/hr
Inlet Solids Loading, gr/ACF
Inlet Gas to Fabric Filter
Flow, ACFM
Temperature, °F
Flow, SCFM
% Moisture (vol)
Dew Point, °F
Inlet So/ids Rate, Ib/hr
Inlet Solids Loading, gr/ACF
Inlet Solids Loading, gr/DSCF
Small
20,000
30,000
30,290
210
23,960
15
616
2.37
29,840
200
23,960
15
132
61.6
0.24
0.35
Large
80,000
120,000
121,150
210
95,840
15
2,464
2.37
119,350
200
95,840
15
132
246.4
0.24
0.35
Outlet Solids Rate, Ib/hr
Outlet Solids Loading, gr/ACF
Outlet Solids Loading, gr/DSCF
Co/lection Efficiency, wt. %
Air-To-Cloth Ratio
High Efficiency
2.56
0.01
0.015
95.94
6/1
10.23
0.01
0.15
95.85
6/1
465
-------
TABLE 168
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR FABRIC FILTERS FOR SOAP AND DETERGENT SPRAY DRYING
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant 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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
•
Small
Large
High Efficiency
Small
30,290
210
23,960
15
2.37
616
30,290
210
23,960
15
0.01
2.56
95.94*
35,278
11,558
4,905
35,375
87,116
Large
121,150
210
95,840
15
2.37
2,464
121,150
210
95,840
15
0.01
10.23
95.85*
138,250
31,293
13,993
126,393
309,929
466
*Cleaning efficiency for
efficient cyclone.
baghouse only; proceeded by 90%
-------
FIGURE 132
CAPITAL COSTS FOR FABRIC FILTERS
FOR SOAP AND DETERGENT SPRAY DRYING
500000
V)
QC
O
Q
to'
O
u
Q.
<
O
100000
10000
1000
1
"U
RNKEYSYSTEI\
/I >
COLLECTOR PLUS
AUXILIARIES
CO
LI
LE
C
T
OR ONLY
J\
'J
/
y
5
/
^ /
1
/
f
/
>
/
f
/
y
y
/
/
/
/
/
/
/
/
/
f
$
r
1000 10000 100000 300000
GAS FLOW, ACFM
467
-------
00
TABLE 169
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR FABRIC FILTERS FOR SOAP AND DETERGENT SPRAY DRYING
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/hr
$6/hr
$.011/kw-hr
Small
Large
High Efficiency
Small
8,000
290
290
1,300
719
2,019
1,075
1,075
3,932
3,932
7,316
8,712
16,028
Large
8,000
290
290
4,298
2,597
6,895
3,600
3,600
17,508
17,508
28,293
30,993
59,286
-------
FIGURE 133
ANNUAL COSTS FOR FABRIC FILTERS
FOR SOAP AND DETERGENT SPRAY DRYING
500000.
CO
DC
O
Q
8
100000
10000
1000
1
(
•QT
OPE
AP
AL
ER/
IT/
0
C
\T
^L
PE
:o
IIS
C
ER
S
1C
:h
A
T
i
\A
T
COST PLL
Df* CO\ 1
n(jtb)
ING COST
y
s
t
s
s
/
>
s
<
T
/
/
/
/
/
/
>
/
x
r/
*
/
1000 10000 100000 300000
GAS FLOW, ACFM
469
-------
TABLE 170
CONFIDENCE LIMITS FOR COLLECTOR ONLY COST
OF FABRIC FILTERS FOR SOAP AND DETERGENT SPRAY DRYING
Population Size — 20 Sample Size — 2
Capital Cost = $35,277.5
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $ 24,022.1 $ 46,532.9
75 10,351.3 60,203.7
Capital Cost = $138,250
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $ 97,911.5 $178,589
75 48,916.7 227,583
470
-------
FIGURE 134
CONFIDENCE LIMITS FOR COLLECTOR ONLY COST
OF FABRIC FILTERS FOR SOAP AND DETERGENT SPRAY DRYING
500000
100000
CO
tr
O
Q
fc
O
O
a.
<
O
10000
1000
75%_
50%-
MEAN-
75%J
1000
10000
100000
300000
GAS FLOW, ACFM
471
-------
TABLE 171
FABRIC FILTER PROCESS DESCRIPTION FOR
SOAP AND DETERGENT PRODUCT HANDLING SPECIFICATION
The fabric filter is to remove entrained detergent from the exhaust gas of the cyclone
separator in the dry product pneumatic air conveying system. This device separates the air
from the dried detergent beads being transferred from the spray dryer to dry product
storage. Air used in the conveying system is atmospheric air. The fines recovered by the
fabric filter represent an economically significant amount and are to be returned to the
process.
The exhaust gas from the separating device will be brought to the filter by means of a
fan. The fabric filter is to be located outside of the building in an area free of space
limitations. The fan is to follow the filter.
The fabric filter is to consist of a minimum of five compartments and will allow for
isolation of an individual compartment for cleaning during operation. Any four of these
compartments should be capable of handling the full flow at designed differential pressure.
Each section should also be capable of isolation for maintenance and have provisions for
personal safety during filter operation. The collecting process is to be continuous and should
include the following:
1. Pulse jet fabric filter or equal, top removal design, compartmented as described
above, with a maximum air-to-cloth ratio of 6/1 and a design differential pressure
of 6 in. w.c.
2. Insulated hoppers with a minimum side angle of 60P and a manual slide gate at the
screw conveyor for isolation. The hopper should be strong enough to support a
full load, although in routine operation the hopper will not be full.
3. Insulate and heat trace entire system ductwork.
4. Carbon steel construction with manufacturer's standard prime paint applied.
5. An insulated screw conveyor equipped with a single rotary air lock.
6. A fan, located downstream of the filter sized with 20% excess capacity when
operating at the design pressure and 90% of the maximum recommended speed.
472
-------
TABLE 172
FABRIC FILTER OPERATING CONDITIONS FOR
SOAP AND DETERGENT PRODUCT HANDLING SPECIFICATION
Two sizes of fabric filters are specified for the "high efficiency" level. Vendors'
quotations should 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.
Pneumatic Air Conveying System
Product Rate, Ib/hr
Inlet Gas to Fabric Filter
Flow, ACFM
Temperature, °F
Flow, SCFM
% Moisture (vol)
Dew Point, °F
Inlet Solids Rate, Ib/hr
Inlet Solids Loading, gr/ACF
Inlet Solids Loading, gr/DSCF
Small
20,000
20,000
WO
18,900
0.3
15
600
3.5
3.7
Large
80,000
80,000
WO
75,700
0.3
15
2,400
3.5
3.7
Outlet Solids Rate, Ib/hr
Outlet Solids Loading, gr/ACF
Outlet Solids Loading, gr/DSCF
Collection Efficiency, wt. %
Air-To-Cloth Ratio
High Efficiency
1.71
0.01
0.01
99.80
6/1
6.86
0.01
0.01
99.80
6/1
473
-------
TABLE 173
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR FABRIC FILTERS FOR SOAP AND DETERGENT PRODUCT HANDLING
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant 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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other J
(4) Total Cost
Small
Large
High Efficiency
Small
20,000
100
18,900
0.3
3.5
600
20,000
100
18,900
0.3
0.01
1.71
99.80
24,768
8,665
4,850
24,025
62,308
Large
80,000
100
75,700
0.3
3.5
2,400
80,000
100
75,700
0.3
0.01
6.86
99.80
98,993
24,338
10,200
91,400
224,931
474
-------
FIGURE 135
CAPITAL COSTS FOR FABRIC FILTERS
FOR SOAP AND DETERGENT PRODUCT HANDLING
500000
CO
DC
O
O
te
O
O
O
100000
10000
1000
TURNKE
Y
COLLECTO
AUXILIAR
CO
LLE
ECT
O
SY
R
E
R
F
5
C
S-
>L
>l\
C
FEM y/
us ^
LY
S^
/
f
/^
*/
<
r
A
/
/
/
>
'
/
/
V
f
/
/
^
/
r
^
>
/i
/
^
7
»T
)
s
/
/
',
1000 10000 100000 3000C
GAS FLOW, ACFM
475
-------
Ol
TABLE 174
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR FABRIC FILTERS FOR SOAP AND DETERGENT PRODUCT HANDLING
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/hr
$6/hr
$.011/kw-hr
Small
Large
High Efficiency
Small
8,000
290
290
975
493
1,468
775
775
2,841
2,841
5,374
6,231
11,605
Large
290
290
3,250
1,740
4,990
2,700
2,700
11,704
11,704
19,684
22,493
42,177
-------
FIGURE 136
ANNUAL COSTS FOR FABRIC FILTERS
FOR SOAP AND DETERGENT PRODUCT HANDLING
500000
CO
cc
O
Q
te
o
U
100000
10000
1000
(Ol
CA
TAL COST
'ERATING (
PITAL CHA
Of
:c
RC
>ERATING
S
31
T
ES
C(
>
s
r
PLUS
)
L
/
JSI
/
:/
s
r
/
X
s
s
/
/
/
/
/
f\
f
/•
1
/
y
A
,
/
/
1000 10000 100000 300000
GAS FLOW, ACFM
477
-------
TABLE 175
CONFIDENCE LIMITS FOR COLLECTOR ONLY COST
OF FABRIC FILTERS FOR SOAP AND DETERGENT PRODUCT HANDLING
Population Size - 20 Sample Size - 2
Capital Cost = $24,768.5
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $ 18,007.6 $ 31,529.4
75 9,795.99 39,741.0
Capital Cost = $98,993.5
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $ 63,815.5 $134,171
75 21,088.8 176,898
478
-------
FIGURE 137
CONFIDENCE LIMITS FOR COLLECTOR ONLY COST
OF FABRIC FILTERS FOR SOAP AND DETERGENT PRODUCT HANDLING
500000
CO
DC
O
Q
k
O
O
o.
<
o
100000
10000
1000
7E
f
A
* V*i
50% y^
MEAN' fr
50% ^
t
/
/
y
^
»
f
t
>
f A
/
S'
>
/
y*
y
r
/
^**
/
V
/
^<
>
'
I
»
/
C
^
f
^
^
<
3
?f
^
/
.
<
,
>
^
'
«•
1000 10000 100000 3000C
GAS FLOW, ACFM
479
-------
REFERENCES
1. "World Soap, Detergent Production," Soap & Chem. Specialties, 46: p.
40-4+; (Sept. 1970)
2. Duckworth, R. A., "Synthetic Detergent Powders," Chem. and Proc.
Engineering, 51:4, p. 63-65+ (1970)
3. Silvis, S. T.; "Detergents," Chemical Week, 105:12; p. 72-4+, (1969)
4. Hatch, L. F., "What's Ahead for Synthetic Detergents," Hydrocarbon
Processing. 47, 3, p. 93 (1968)
5. Marquis, D. M., "Make AOS from Olefins and 803," Hydrocarbon
Processing, 47, 3, p. 109-114 (1968)
6. Hollis, G. L., "Domestic Detergents: today-tomorrow," Chemistry and
Industry; p. 1309-15; October 10, 1970
7. Kremers, F. J., and Shultz, A., "Continuous Sulfonation with Sulfur
Trioxide," Soap and Chem. Specialties, 46: p. 44-6+ (1970)
8. Holzman, S. and Zoller, U., "Long Chain Alcohol Sulfates from Converter
Gas," Soap and Chem. Specialties, 45, 9, p. 43-46+ (1969)
9. Gilbert, E. E., Sulfonation and Related Reactions, Interscience Publishers,
N.Y., 1965
10. Shreve, R. N., The Chemical Process Industries, McGraw-Hill Book
Company, Inc. N.Y., 1956
11. Danielson, John A., Air Pollution Engineering Manual, Public Health
Service, Cincinnati, 1967, p. 716-20.
12. Spitz, L., "Advances in Saponification, Drying and Soap Finishing
Technology," Soap and Chem. Specialties 44: p. 60+ (October, 1968)
13. Phelps, A. H., "Air Pollution Aspects of Soap and Detergent
Manufacture," Journal of Air Pollution Control Association, 17, 8, p.
505-7 (1967)
14. "Market Newsletter," Chemical Week, p. 33, October 18, 1972
480
-------
LIME KILNS
-------
6. LIME KILNS
The manufacture of lime is an ancient practice, dating back to the Roman,
Greek, and Egyptian civilizations. In the colonial period of America, lime was
manufactured by burning limestone in brick or masonry kilns dug out of the
side of a hill. The kilns used either a coal or wood fire at the bottom, and were
open at the top. Lime manufacture did not change substantially until the
twentieth century, and most of the progress has been made since 1935.
Today, the manufacture of lime is a large industry using sophisticated
technical control and making a product of high quality and uniformity. The
manufacture of lime involves the burning of limestone (CaCC^ or
CaCOg-MgCC^) to release carbon dioxide and form quicklime (CaO or
CaO'MgO). There are two types of limestone used to produce lime. The
limestone is classified as "high calcium" or "calcite" if the magnesium
carbonate content is less than 5%, and "dolomitic limestone" or "dolomite" if
the magnesium carbonate content is 30 to 40%.(1) Figure 88 is a flowsheet
showing the manufacture of lime in its entirety.(2)
In the United States, limestone is calcined in either vertical or rotary kilns.
In 1964, about 15% of the open-market lime and over 50% of the captive
market lime was produced in vertical kilns.'31 In that year about 30% of the
11.4 million tons of lime produced was captive market lime.<2) This "captive
market" lime consists mainly of the lime produced and used in the alkali, sugar,
and pulp and paper industries.
This section will discuss vertical limestone calcining kilns and those rotary
lime kilns used in the pulp and paper industry. Other rotary kilns were studied
under NAPCA Contract CPA70-150.
VERTICAL KILNS
Process Description
Vertical, or shaft, kilns are the oldest and most widely used type of lime
calcining kilns. Consequently, the particulars of kiln design vary greatly. All
vertical kilns do operate similarly, however, and have four distinct zones from
top to bottom:
1. Stone storage zone
2. Preheating zone
3. Calcining zone
4. Cooling and discharge zone
481
-------
FIGURE 138
SIMPLIFIED FLOW SHEET OF A TYPICAL LIME MANUFACTURING OPERATION
ro
LIME MANUFACTURING
KILN
i
PULVERIZING
COMMERCIAL PRODUCTS
LIMESTONE MINE
OR QUARRY
CRUSHING
AND
SCREENING
<
I
*•
....I
STOCKPILES
COMMERCIAL PRODUCTS
LIME KILN FEED
COMMERCIAL
PRODUCTS
LIME CRUSHING
AND SCREENING
GRINDING AND
PULVERIZING
LIME STORAGE
BINS
COMMERCIAL
PRODUCTS
LIME HYDRATOR
FEED
i
GRINDING AND/ OR
AIR CLASSIFICATION
HYDRATE
STORAGE
BINS
COMMERCIAL PRODUCTS
BULK LOADING AND /OR
BAG LOADING
-------
These zones are shown in a schematic diagram of a vertical kiln contained in
Figure 139.(2-3)
The flow of stone in the kiln is countercurrent to the flow of cooling air
and combustion gases. The stone is charged at the top and preheated by the hot
exhaust gases from the calcining zone. The stone is burned in the calcining zone
in various ways which will be described below. Air blown into the bottom of
the kiln cools the lime before it is discharged. This air is heated sufficiently by
the time it reaches the calcining zone to be used as secondary combustion air.
The lime is discharged to cars on tracks or to conveyor belts, and either shipped
or further processed by hydrating.
The limestone is usually charged to the kiln continuously by inclined
conveyor belt, although some older kilns still are charged in batches by skip
hoist. Modern vertical kilns are enclosed and vent exhaust gases through flues
or dampers. In these kilns either a forced or induced draft moves the gases
through the kiln. There are some old kilns left that are open at the top, but
they have serious disadvantages. Winds interfere with the draft, sometimes
causing downdrafts, or rains wet the stone charge.
The hot exhaust gases rising from the calcining zone contain more than
enough heat for preheating, and the excess is frequently recycled to the
calcining zone and mixed with cooling air to be used as secondary combustion
gas. This exhaust gas recirculation is one reason that emission rates from
enclosed vertical kilns are generally lower than those of rotary kilns.
In most modern lime kilns, gaseous rather than solid fuels are employed.
This prevents a reduction in quality due to fuel ash. The gaseous fuels
employed are natural gas, fuel oil, or producer gas. Natural gas is preferred in
the United States. Most modern natural gas and oil fired kilns are equipped
with center burners on two or four sides of the kiln in the calcining zone. Side
burners are usually used also. This arrangement provides good uniformity in
temperature throughout the calcining zone, improving kiln performance, fuel
efficiency, lime quality, and kiln capacity. Producer gas kilns burn solid fuel in
separate furnaces. The fuel is burned with a deficient air supply, or with an
air-steam mixture, producing carbon monoxide and hydrogen. This hot
combustible gas is burned in the calcining zone, either undiluted or diluted
with primary air.
There are two types of kilns where solid fuel is in direct contact with the
limestone. The standard vertical kiln, which was common in the United States
up to 1940, is largely of the direct hand fired type. These kilns are manually
483
-------
FIGURE 139
VERTICAL LIME KILN
STONE
CHARGING
DOOR
ZONES
EXHAUST
KILN HOUSING
LIME
DISCHARGE
KILN
SHAFT
FIRE BOX
OR
FUEL PORTS
STORAGE
PREHEATING
FINISHING
CALCINING
COOLING
j
484
-------
fueled by periodic coal shoveling. Usage of kilns of this type is declining
because of considerable manual labor, low kiln capacity, poor thermal
efficiency, and inadequate quality and uniformity of lime.(3> The second type
of solid fuel kiln is the mixed feed kiln. This kiln is widely used in Europe
although it produces a generally poorer grade of lime. The fuel used in mixed
feed kilns is usually anthracite coal or a metallurgical grade of low reactivity
coke. The fuel is comparable in size with the limestone and the two are
intimately mixed in fixed proportions before charging. The overriding
advantage of a mixed feed kiln is its fuel economy. It has the lowest fuel
consumption of any type of lime kiln, and is a great improvement over earlier
solid fuel kilns. In these older solid fuel kilns, substantial heat losses occur as
the result of carbon monoxide formation. Carbon dioxide reacts with hot fuel
to form carbon monoxide with a subsequent loss of heat
(C02 + C + heat -> 2CO). For 1% CO in the exhaust gas, the heat loss will be
about 240,000 Btu/ton of lime.<3) The intimate fuel-limestone mixing in
mixed feed kilns greatly reduces the possibility of fuel-carbon dioxide contact
and the occurrence of the resultant heat loss.
Vertical kilns range from 6.5 to 25 ft in outside diameter and 16 to 100 ft
in height; an average size is 12 ft in diameter by 50 ft in height. Lime kilns are
generally constructed of insulated refractory brick, and a heavy steel boiler
plate casing. Kiln capacities vary greatly; the older standard kilns have
capacities from 1/4 to 1/2 ton/day/ft2 cross-sectional area, while large direct
gas fired kilns have 1 to 2 ton/day/ft2 capacities. The majority of kilns have
capacities ranging from 50 to 250 plus tons of lime/day.(3) Some kilns recently
built have capacities up to 680 ton/day.(4) Fuel consumption for direct and
indirect gas fired kilns range from 4 to 6 million Btu/ton of lime produced. For
large mixed feed kilns, consumption of 3 million Btu/ton has been reported.(3)
The vertical kiln has several advantages over a rotary kiln:
1. Lower fuel consumption.
2. Greater flexibility due to smaller producing units.
3. Lower first cost.
The major disadvantages are:
1. Cannot effectively handle small feed sizes.
2. Chemical reactivity is less, producing less product uniformity.
3. Longer calcining time required.
4. Lesser degree of quality control possible.
485
-------
Process Chemistry
The calcination of limestone involves thermal decomposition and can be
represented by the following reactions:
1. CaC03(c) + Heat J CaO(c) + C02(g)
(high calcium limestone) (high calcium quicklime)
2. CaC03 • MgC03(c) + Heat J CaO • MgO(c) + 2C02(g)
(dolomitic limestone) (dolomitic quicklime)
There are three essential factors in limestone decomposition kinetics:(3>
1. The limestone must be heated to the dissociation temperature of
carbonates. This temperature is 1648° F for calcite and from 930 to
1480° F for dolomite. The dissociation temperature of dolomite is
dependent on the amount of magnesium carbonate (MgCC^) present,
as it dissociates at lower temperatures (756 to 896° F). The heat
required to reach the theoretical minimum dissociation temperature
is approximately 1.5 million Btu/ton of high calcium quicklime and
1.25 million Btu/ton of dolomitic quicklime produced.
2. The minimum dissociation temperature must be maintained through-
out the reaction. The heat consumed here is about 2.77 million
Btu/ton of high calcium quicklime and 2.6 million Btu/ton of
dolomitic quicklime produced. In practice, however, higher
temperatures are maintained and more heat is consumed. Inadequate
control of the temperature will lead to fuel losses and poor product
quality. The correct temperature depends on the limestone being
calcined, but generally ranges from 1900 to 2450°F for calcium
carbonate and 1750 to 2300° F for dolomitic limestone.
3. The CC>2 gas that is produced must be removed to minimize
carbonate reformation, as the reaction is reversible.
Raw Materials and Products
The feed to lime kilns consists of the carbonates of calcium or magnesium,
which are obtained from natural deposits of limestone, marble, chalk,
dolomite, or oyster and clam shells. Limestone is generally used as the raw
material for lime manufacture. Some plants, particularly along the Gulf Coast,
486
-------
use oyster shells. Limestone deposits exist throughout the country, but only a
small portion are of sufficient purity to be used in lime manufacture.
Table 176'21 presents some typical lime kiln feed compositions.
Greater than 90% of the limestone quarried is from open pit operations.
The remainder is extracted from underground mines.'21 The stone that is
quarried contains as few impurities as possible. These impurities include silica,
alumina, iron and clay.
The size distribution used in vertical lime kilns is critical. Ample voids
must be present in the bulk limestone to insure unrestricted circulation of flue
gases and air around and through the stone and lime. This is necessary for
uniform heat transfer and expulsion of the CC^. The ideal external void
fraction is 45%.<3) A range of particle sizes may have lower void fraction (i.e.
the small particles fill in between the large ones) than either uniform large
particles or uniform small particles. Stones less than 2 inches in diameter can-
not be successfully calcined in a vertical kiln. Stone sizes range from 8 by 12
in. to a minimum of 2 by 4 in., with an average size being 4 by 8 in.'3*
Limestone and lime have as many different uses in industry as any natural
substance. Lime is a close second to sulfuric acid in total production among the
basic chemicals. Lime is used in building construction, agriculture, and highway
construction. Lime is used in the pulp and paper industry to causticize the
waste sodium carbonate solution in the sulfate process. This particular process
will be discussed in detail in the second half of this section. Lime is also used in
the manufacture of pig iron, steel, magnesia or magnesium metal, alkalis, sugar,
calcium carbide, insecticides, bleaches, and other chemicals. Lime, in terms of
tonnage, is the main water treatment chemical. It is employed in water
softening, purification, coagulation, neutralization of acid wastes, sewage
treatment, and treatment of industrial waste water. Lime has also been used in
the form of a slurry for the scrubbing of stack gases to remove SC>2, HCI, HF,
and other acidic gases.
Most lime produced is high calcium quicklime of at least 90% calcium
oxide content. Table 177 shows a typical composition of high calcium and
dolomitic quicklime.'31 The composition of the lime varies depending on its
intended usage. This composition is controlled by proper selection of the stone
and specific conditions of the manufacturing process used.
ROTARY KILNS (PULP MILL)
Rotary lime sludge kilns are widely used in alkali pulping processes in the
487
-------
TABLE 176
TYPICAL ANALYSES OF HIGH CALCIUM
AND DOLOMITIC COMMERCIAL LIMESTONES*21
High
Calcium Dolomitic
Component Wt.% Wt.%
Calcium carbonate
(CaC03) 97.40 52.34
Magnesium carbonate
(MgCO3) 1.25 47.04
Iron oxide
(Fe203) 0.11 0.04
Aluminum oxide
(AI203) 0.35 0.20
Silica (Si02) plus
acid insolubles 0.95 0.26
Loss on ignition (C02) 43.40 47.67
488
-------
TABLE 177
TYPICAL COMPOSITION OF HIGH CALCIUM
AND DOLOMITIC QUICKLIME131
Component
CaO
MgO
Si02
Fe203
AI203
C02
S03
p
High Calcium,
Range, wt.%
93.00 to 98.00
0.30 to 2.50
0.20 to 2.00
0.10 to 0.40
0.10 to 0.60
0.40 to 2.00
0.01 to 0.10
trace to 0.05
Dolomitic,
Range, wt.%
55.00 to 57.50
37.00 to 41.00
0.10 to 1.75
0.05 to 0.40
0.05 to 0.50
0.40 to 2.00
0.01 to 0.10
trace to 0.05
489
-------
pulp and paper industry. These processes basically convert wood to wood pulp
by "cooking" the wood in an alkaline solution known as the cooking liquor.
The function of the kiln is to reburn lime for use in the regeneration of this
wood cooking liquor.
Alkali pulping is a term applicable to two similar processes used in the
preparation of cellulose wood pulp. These are the sulfate pulping (Kraft) and
the soda pulping processes. In both processes, sodium hydroxide is the major
ingredient in the cooking liquor. The main difference between the processes is
that sodium sulfate is used in the former instead of sodium carbonate as a
make-up chemical for the cooking liquor. The sulfate is reduced to sulfide, so
in the sulfate process, not only caustic soda but also sodium sulfide is a
component of the cooking liquor. A simplified sulfate pulping flow diagram is
shown in Figure 140.(5i6)
Process Description
In sulfate pulping, wood chips are cooked in a digester at elevated
temperature and pressure. The "fresh" cooking liquor is a solution of NaOH,
Na2S, and IV^COg, called the "white liquor." The spent liquor from the
digester is separated from the pulp. This liquor, known as "black liquor,"
contains 95 to 99% of the alkali, mostly in the form of sodium carbonate.
Various organic sulfur compounds in combination with sodium sulfide are also
present, along with other numerous impurities. A portion of this "black liquor"
is recycled back to the digester. The actual cooking liquor will contain from 20
to 50% of this recycled liquor. The remainder of the black liquor is recovered
and regenerated.
The recovery of the cooking chemicals involves the concentration of the
black liquor by evaporation, burning of the concentrated liquor in a furnace to
convert the sodium compounds to IS^CC^ and Na2S, and causticizing the
carbonate "smelt" with lime to reform the white liquor. The lime used in
causticizing is regenerated by burning the CaCOg mud, which is generated in
causticizing, in a rotary lime kiln. In this way, about 90 to 95% of the total
sodium and 50% of the total sulfur are recovered.(7) Since the function of the
lime kiln is an integral part of the black liquor recovery process, the total
process will be described briefly. A flow chart of the process is shown in Figure
141.
The molten smelt from the recovery furnace is removed and dissolved in
water and weak liquor from the causticizer, forming "green liquor." This liquor
490
-------
FIGURE 140
SIMPLIFIED KRAFT MILL FLOW DIAGRAM
CHIPS
CO
BLOW HEAT
RECOVERY
BLACK LIQUOR RECYCLE
TO PULP
BLEACHING
PROCESSING
ELECTROSTATIC
PRECIPITATOR
DIRECT
EVAPORATOR
I
"
COMBUSTION
GASES
>
GREEN 3 EW
LIQUOR
Y
ER
SLAK
OXIDATION
TOWER
MULTIPLE
EFFECT
EVAPORATOR
I
KILN
EXHAUST
EMISSION
CONTROL
DEVICE
QUICKLIME
K.
N
WHITE
LIQUOR
STORAGE
(AKE-UP
TDI<
A, SO 4. ' ' '
* RECOVERY
FURNACE
.SOLVER
WHITE LIQUOR
CAL
MUD MAKE-UP
FILTER LIMESTONE
I
LIME KILN
-------
FIGURE 141
KRAFT PULPING RECAUSTICIZING
FLOWSHEET
£
NJ
__ GREEN LIQUOR
GREEN LIQUOR
CLARIFIER
1
FROM
RECOVERY
FURNACE
i
DREGS
WASHER
-]
_ GREEN
~~ LIQUOR
SMELT
DIS SOLVER
LIME
SLAKER
CLASSIFIE
TO WASTE
WHITE
LIQUOR
GRIT
TO
WASTE
CAUSTICIZERS
r
WHITE
LIQUOR
ATMOSPHERE
WHITE LIQUOR
— — — —'
CLARIFIER
QUICKLIME
WASH
WATER
1
TWO STAGE
—. ^- —
LIME MUD
WASHER
EMISSION
CONTROL
DEVICE
-------
will contain 20% Na2C03 and 5% Na2S by weight, expressed as I\la20.(8> The
green liquor is clarified to remove such impurities as Fe203, silica, alumina,
unburned carbon, and furnace brick. Quicklime from the lime kiln is converted
to slaked lime by mixing it with clarified green liquor. This mixture is sent to a
series of agitated tanks known as causticizers. In these vessels, calcium
hydroxide reacts with sodium carbonate to form sodium hydroxide and
calcium carbonate. The sodium sulfide does not react in this mixture. The lime
sludge is separated from the clean white liquor by a clarifier. The lime sludge
mainly consists of calcium carbonate and sodium hydroxide. This lime mud is
washed countercurrently, finally with fresh water on a rotary vacuum filter.
The sodium content should be reduced by washing from about 22 wt.% to
about 0.5 wt.% dry basis, but the lime mud may have about 1.5 to 3.0 wt.%
sodium (in the form of Na20) due to inadequate washing.(8)
The soda pulping process operates in a similar way with the exception that
sodium carbonate is used in place of sodium sulfate and, therefore, no sulfides
or sulfates are present at any stage of the operation.
The lime sludge from the vacuum filter, which contains 55 to 60% solids,
is the feed material for the rotary lime kiln. Some fresh limestone is usually
also burned to replenish lost lime. The kiln, which is supported by rollers, is a
long inclined horizontal cylinder made from refractory brick and lined with
steel plates. Most kilns rotate at a speed of about 1 rpm. These kilns range in
size from 6 to 11 ft in diameter and 100 to 325 ft in length.(9) Kilns in these
ranges produce from 30 to 175 tons of lime per day. Kilns built today are a bit
larger. The lime flows countercurrent to the heat, the lime mud entering at one
end and the hot air entering at the other. Most kilns are fired by either oil or
natural gas. The kiln is composed of three fairly distinct zones:'7'
1. The feed and drying zone.
2. The central or preheating zone.
3. The calcining zone.
In the drying zone, steel chains are commonly used to facilitate heat
transfer from the hot gases to the lime mud. As the kiln rotates, these chains
will alternatively contact the hot gases and the mud. The temperature in this
end of the kiln is kept below 1,000°F. In the preheating zone, the lime will
pass through a plastic or semi-liquid state, forming pellets up to 1 in. in
diameter under normal conditions.181 The operating temperature in the
preheating and calcining zones is generally in the 2,000 to 2,400° F range, with
higher temperatures being found in shorter kilns. The quicklime is discharged
directly to the slaker or to a surge bin and then to the slaker. A typical
composition of this reburned quicklime is shown in Table 178.(1 °'
493
-------
TABLE 178
TYPICAL COMPOSITION OF REBURNED QUICKLIME1101
Component
CaO
Na20
MgO
AI203
Wt.%
93
2
1
1
Fe203
Si02
C0
2
494
Total oxides 100
-------
Process Chemistry
The process chemistry of rotary lime sludge kilns is generally the same as
vertical kilns. The heat requirement is greater because the lime mud contains 40
to 45% water. The heat requirement for lime with 40% water is around
6,740,000 Btu/ton of lime.171
Several reactions take place in the different stages of the black liquor
recovery process.
1. Recovery furnace
a. Various organic combustion reactions.
b. Na20 + C02 -> Na2C03
c. Na2S04 + 2C -> Na2S + 2C02
2. Slaker
a. CaO + H20 + Ca(OH)2
b. Ca(OH)2 + Na2C03 + 2NaOH + CaC03 4-
(small extent)
3. Causticizer
a. Ca(OH)2 + Na2C03 1 2NaOH + CaC03 4-
4. Lime Kiln
a. CaC0
C0
NATURE OF THE GASEOUS DISCHARGE
The air pollutants emitted from both types of lime kilns consist mainly of
lime dust and the products of combustion. Emissions from a lime sludge kiln
will also include a small percentage of sodium and sulfur compounds. As a
result of this, odor can be a problem of lime sludge kiln exhausts.
The contaminants in vertical lime kiln gases will be similar to those found
495
-------
in rotary lime kiln exhaust gases. The emissions from a vertical kiln will present
less of a problem for the following reasons:
1. A portion of the exhaust gas from a vertical kiln is usually recycled
to salvage its heat content.
2. The particulate emissions from a vertical kiln are not as small as in
the rotary kiln case because there is much less attrition in the
former than in the latter.
3. The temperature of the exhaust gas from a vertical kiln is in the 225
to 310° F range, as opposed to a rotary kiln exhaust temperature of
300 to 1,200°F.
The exhaust gases principally consist of carbon dioxide, water, and
nitrogen. Depending on the type of fuel used, various other gaseous
contaminants will be present. Typical exhaust compositions from a gas fired
lime sludge kiln are presented in Table 179.<12) The relative usage of fuels for
limestone calcining is given in Table 180.(3) Oil and natural gas are
predominantly used in lime sludge kilns.
If sulfur-containing coal, coke, or oil is burned, a small amount of sulfur
dioxide and sulfur trioxide will be present. For coal containing 1 to 6 wt.%
sulfur, sulfur dioxide will be present in the exhaust gases in concentrations
ranging from 0.05 to 0.30 vol.%.'1) When coke and coal are used, carbon
monoxide (in the 1% range) and other combustible gases may be present in the
exhaust gases. These emissions result mainly from uneven fuel distribution, and
have been largely eliminated in the mixed feed vertical kiln. In modern oil and
gas fired shaft kilns, virtually no unburnt fuel is present in the exhaust gas.<4)
Nitrogen oxides will be present, regardless of the fuel burned, in concentrations
ranging from 100 to 1,400 ppm.(1' The NOX concentration will increase as the
amount of excess air used in combustion increases.
Various sulfur compounds are also found in the exhaust gases from lime
sludge kilns. Typical concentration ranges and averages for these compounds,
which are responsible for kiln odors, are given in Table 181.(17) However, in
comparison with other odor sources in the pulp mill, lime kiln odors are not
significant. Hydrogen sulfide is the major odorous gas emitted from the kiln. It
is caused by the presence of sodium sulfide in the lime mud and is produced by
the following reaction:
Na2S + C02 + H20 + Na2C03 + H2S
496
-------
TABLE 179
TYPICAL COMPOSITIONS OF EXHAUST GASES
FROM LIME SLUDGE KILNS112'
Component Vol.%
H20
CO2
CO
02
200 TPD*
37.1
10.4
0.0
3.2
49.3
100.0
292 TPD**
30.0
15.3
0.5
0.2
54.0
100.0
Excess air very high, kiln exhaust temp, high (415° F).
Excess air less than 5%, exhaust temp. 350° F.
497
-------
TABLE 180
BREAKDOWN OF FUEL USAGE
IN LIME ROCK KILNS DURING 1962(3)
Fuel Percent*
Natural gas 36
Coke 30
Bituminous coal 22
Oil 6
Unspecified and miscellaneous 6
100
*0f total 1962 fuel usage (weight) by lime rock kilns.
498
-------
TABLE 181
TYPICAL GASEOUS SULFUR CONCENTRATION RANGES
AND AVERAGES FOR LIME SLUDGE KILN EXHAUST117)
Pollutant Average (ppm) Cone. Range (ppm)
H2S 48 0 to 100
CH3SH 2 0 to 3
CH3SCH3 1 0 to 1
-------
If the temperature is high enough, some of the hydrogen sulfide will be
oxidized to sulfur dioxide, much of which is absorbed in the lime mud. This
oxidation can be presented as follows:(13'
2H2S + 302 + 3S02 + 2H20
Exit gas temperatures for chain equipped lime sludge kilns will be 300 to
400° F for long kilns and 400 to 500° F for short kilns. For short kilns without
a chain system, exhaust temperatures will be as high as 1,200°F.(9)
The gas leaving lime kilns carries variable amounts of dust. The rotary lime
sludge kiln exhaust will carry a greater amount of dust than the vertical lime
kiln exhaust for the reasons discussed previously.
A vertical lime kiln will generally emit particles in the amount of 1% of
the weight of the lime produced.'11' Actual particulate loadings have been
reported to range from 0.3 to 1.0 gr/SCF(2) and, for very large kilns, from 2.5
to4.4gr/SCF.(4)
Particulate loadings in lime sludge kilns range from about 3 to 20
gr/SCF.<13> 14) Several compositions of the particulate matter emitted from
high calcium limestone calcining kilns are shown in Tables 182 and 183,(1>3)
and from lime sludge kilns in Table 184. (12>14) It is evident that the
composition of the particulate matter can vary greatly. This is especially true of
lime sludge kiln emissions, and is due in these cases to the variation in the
composition of the lime mud feed. The most important variation in the lime
mud composition is in the amount of sodium sulfide present, which is
controlled by the degree of washing which the lime mud receives.
An approximate relationship between process weight and gas flow in a gas
fired lime sludge kiln is given in Table 185. Table 186 shows a theoretical
relationship between exhaust flow rates and vertical lime calcining kiln
capacities. These rates were calculated from an actual operating example'2) and
the heating content of various fuels. Excess primary combustion air was
assumed to be 10%, with 30% more air required for cooling and even heat
distribution. The lime produced was assumed to be 95 wt.% CaO, and the
exhaust gas to contain 30.1 vol.% C02, 2.5 vol.% O2 and 0 vol.% CO on a dry
basis, with the remainder being nitrogen and water vapor.
AIR POLLUTION CONTROL CONSIDERATIONS
The major contaminant in vertical lime kiln exhaust gas is lime dust. This
500
-------
TABLE 182
TYPICAL EMISSIONS OF A NATURAL
GAS-FIRED LIME ROCK KILN*1-31
Component
CaO
CaC03
Ca(OH)2
MgO
CaS04
Other
100.0 100.0
High Calcium
Wt%
66.3
23.1
6.4
1.4
1.2
1.6
Dolomitic
Wt%
7.2
64.3
—
28.2
0.3
—
501
-------
TABLE 183
TYPICAL EMISSIONS OF A PULVERIZED
COAL-FIRED LIME ROCK KlLN(1-3)
Component
Total oxides (CaO and MgO)
Total carbonates (CaCOg and MgCOg)
CaO chemically combined in compounds,
including some
Si02
R2°3
Carbon
SO-
Total
Wt.%
37
25
10
10
5
12
1
100
502
-------
TABLE 184
VARIOUS COMPOSITIONS OF LIME SLUDGE KILN DUST
Dolomitic1121 High Calcium1141
Component Wt.% Wt.%
Available CaO 6.4
CaC03 60.8 60.3 to 91.7
Na2C03 1.4 7.7 to 34.1
MgC03 18.7
Na2S04 - 0.2 to 4.4
Fe203 + AI203 2.9 \
S 0.3 to 1.2
Silica and other impurities 9.8 -^
100.0 100.0
503
-------
TABLE 185
TYPICAL EXHAUST GAS PRODUCTION
FOR SEVERAL LIME SLUDGE KILN SIZES
Lime Produced, Ton/Day Exhaust Gas, DSCFM
60 7,150
120 14,500
200 25,000
290 31,000
400 50,000
504
-------
TABLE 186
THEORETICAL LIME ROCK KILN EXHAUST RATES
FOR DIFFERENT FUELS
Exhaust Flow, SCFM (60° F)
Kiln Natural Fuel Bituminous
Capacity Gas Oil Coal Coke
25 1,100 1,280 1,400 1,500
100 4,400 5,125 5,600 6,000
250 11,000 12,800 14,000 15,000
350 15,400 17,940 19,600 21,000
700 30,800 35,875 39,200 42,000
505
-------
dust is relatively large, and in many cases, the bulk of paniculate matter can be
removed by a multiple dry cyclone unit. Collection efficiencies range from 75
to 85%.'3) Table .187 contains a typical size distribution of particulate
emissions from lime rock kilns.'11) The relatively large particle size is mainly
due to the fact that there is much less attrition in a vertical kiln than in a
rotary kiln.
Collection efficiencies will be higher if wet scrubbers, fabric filters, or
electrostatic precipitators are used. All three types of equipment have been
used successfully but precipitators have not been applied commercially in great
numbers. Where high sulfur containing coal or oil is burned, wet scrubbers
using an alkaline scrubbing solution have the advantage of controlling sulfur
dioxide emissions as well as the particulate emissions.
The two main types of emissions from lime sludge kilns which must be
controlled are the "soda fume" and the lime dust. The soda fume consists of
fine particles of sodium compounds which are volatilized at the hot end of the
kiln. The lime particles are larger and are entrained in the exhaust gas.
Wet scrubbing is the most widely used method for controlling these
emissions. The cyclonic, variable orifice, and Venturi types of scrubbers have
all been successfully employed. Diagrams of these scrubbers are shown in
Figures 142, 143, and 144.(15)
Pressure drops of 15 to 17 in. w.c. across the scrubber are sufficient to
remove about 99% of the lime dust but only 70 to 80% of the soda fume.'1 3)
This small amount of soda fume emission can cause opacity problems due to
the small size of the particles. The problem of sodium loss can be handled
several ways. The easiest method is to properly wash the lime mud before it is
burned, greatly reducing the amount of sodium sulfide put into the kiln.
Electrostatic precipitators can show better soda fume collection efficiency, but,
so far, they have not been widely used.
506
-------
TABLE 187
TYPICAL PARTICLE SIZE DISTRIBUTION OF
VERTICAL LIME ROCK KILN EMISSIONS1111
Size Range, Wt.% of Particles
microns in Range
greater than 44 28
20 to 44 38
20 to 20 24
5 to 10 8
less than 5 2
100
507
-------
FIGURE 142
OYOLONIC. GAS SORUBBEIR
GAS OUTLET
OUTLET
INLET
LIQUID
OAS INLET
508
-------
FIGURE 143
VARIABLE ORIFICE SCRUBBER
INLET CAS
ADJUSTABLE
ORIFICE
OFF GAS
LIQUOR
OUTLET
509
-------
FIGURE 144
LIME KILN VENTURI SCRUBBER SYSTEM
en
o
CYCLONIC
SEPARATOR
FRESH WATER OR
KILN COOLING
WATER
RECYCLE TO
SMELT DISSOLVING
TANK
-------
SPECIFICATIONS AND COSTS
Specifications have been written for three abatement systems applied to
vertical lime rock kilns: wet scrubbers, fabric filters, and electrostatic
precipitators. The model plant sizes chosen for the precipitator specifications
were larger than those chosen for both the fabric filter and wet scrubber
systems. This was done because precipitators are economically attractive for
only the largest sized vertical kilns. Cost data and equipment specifications for
vertical kilns are presented in Tables 188 to 201 and Figures 145 to 156.
Two systems were specified for rotary sludge kilns in paper plants: wet
scrubbers and electrostatic precipitators. Since gas flows for rotary sludge kilns
are higher than those for vertical kilns, the model plant sizes chosen for both
abatement systems were the same. A fabric filter system was not applied
because the high humidity of the exhaust gas from the kiln causes blinding
problems. Cost data and equipment specifications are presented in Tables
202 to 211 and Figures 157 to 166.
511
-------
TABLE 188
WET SCRUBBER PROCESS DESCRIPTION FOR
VERTICAL LIME ROCK KILN SPECIFICATION
The scrubber is to remove entrained limestone and lime dust from the exhaust gas of a
vertical lime rock kiln. The kiln is fired with natural gas. A portion of the hot exhaust gas
from the calcining zone is recirculated for heat recovery. The kiln is fed with 6 to 8 in. sized
pieces of high calcium limestone.
The exhaust gas is to be brought from the kiln exhaust ports to a fan located 20 feet
outside of the kiln enclosure. The fan outlet is to be five feet above grade. The scrubber will
be located beyond the fan in an area free of space limitations. The scrubber should be
designed to withstand the discharge pressure developed by the fan. Fresh makeup water is
available and is to be added to the recirculation tank. The scrubber is to operate so as to
reduce continuously the kiln outlet loading to the levels specified.
The scrubbing system should include the following:
1. Venturi scrubber with a cyclonic entrainment separator.
2. Recirculation tank and pumps.
3. Slurry settler, which will handle a portion of the recirculation pump discharge,
capable of producing a reasonably thickened underflow product while returning
water fully treated to minimize solids content. Slurry withdrawal should be set to
maintain 10% (by weight) solids when the kiln is operating at design capacity.
4. Minimum of two filters to dewater the slurry product, capable of producing a cake
with a minimum of 65% (by weight) solids.
5. Necessary fans, dampers and motors.
6. Necessary controls.
7. Carbon steel construction.
8. Packing glands flushed with fresh water to prevent binding of the seals.
512
-------
TABLE 189
WET SCRUBBER OPERATING CONDITIONS FOR
VERTICAL LIME ROCK KILN SPECIFICATION
Two sizes of wet scrubbers are to be quoted for each of two efficiency levels. Vendors'
quotations should consist of four separate and independent quotations.
Kiln Capacity, ton/day
Process wt., Ib/hr
Inlet Gas
Flow,ACFM
Temp., °F
Flow, SCFM
% Moisture (vol)
Inlet Solids Rate, Ib/hr
Inlet Solids Loading
gr/ACF
gr/DSCF
Outlet Gas
Flow,ACFM
Temp., °F
% Moisture (vol)
Small
100
15,000
7,300
275
5,300
12
80.7
1.29
2.03
6,500
130
15
Case 1 — Medium Efficiency*
Outlet Solids Rate, Ib/hr
Outlet Loading
gr/ACF
gr/DSCF
Collection Efficiency, wt. %
Scrubber A P
15.8
0.28
0.37
80.4
12 in. w.c.
Case 2 - High Efficiency *
Outlet So/ids Rate, Ib/hr
Outlet Solids Loading, gr/ACF
Outlet Solids Loading, gr/DSCF
Collection Efficiency, wt. %
Scrubber A P
0.56
0.01
<0.015
99.31
30 in. w.c.
350
51,000
25,500
275
18,400
12
288.5
1.32
2.08
22,700
130
15
35.9
0.18
0.24
87.6
12 in. w.c.
1.94
0.01
<0.015
99.33
30 in. w.c.
* See page 6 for definition of collection efficiency levels.
513
-------
TABLE 190
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR VERTICAL LIME ROCK KILNS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant 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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other J
(4) Total Cost
LA Process Wt.
Small
7,300
275
5,300
12
1.29
80.7
6,500
130
5,850
15
0.28
15.8
80.4
6,699
4,407
22,767
33,873
Large
25,500
275
18,400
12
1.32
288.5
22,700
130
20,400
15
0.18
35.9
87.6
13,141
9,426
35,717
58,284
High Efficiency
Small
7,300
275
5,300
12
1.29
80.7
6,500
130
5,850
15
0.01
0.56
99.31
6,813
6,559
25,100
38,472
Large
25,500
275
18,400
12
1.32
288.5
22,700
130
20,400
15
0.01
1.94
99.33
13,357
11,546
'
38,083
62,986
514
-------
TABLE 191
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR WET SCRUBBERS FOR VERTICAL LIME ROCK 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
Annualized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$.011/kw-hr
$.25/M gal
LA Process Wt.
Small
8,000
1,123
619
619
3,448
191
3,639
5,381
3,387
8,768
Large
8,000
1,840
1,179
1,179
10,912
647
11,559
14,578
5,828
20,406
High Efficiency
Small
8,000
1,290
727
727
4,841
191
5,032
7,049
3,847
10,896
Large
8,000
2,007
1,283
1,283
15,726
647
16,373
19,663
6,299
25,962
Ul
CJ1
-------
FIGURE 145
CAPITAL COSTS FOR WET SCRUBBERS
FOR VERTICAL LIME ROCK KILNS
(MEDIUM EFFICIENCY)
500000
100000
e/j
cc
o
o
te
8
_l
<
t
o.
o
10000
1000
TURNKEY SYSTEM-
COLLECTOR PLUS
AUXILIARIES
COLLECTOR ONLY
1000
10000
GAS FLOW, ACFM
100000
300000
516
-------
FIGURE 146.
ANNUAL COSTS FOR WET SCRUBBERS
FOR VERTICAL LIME ROCK KILNS
(MEDIUM EFFICIENCY)
500000
100000
C/J
oc
fc
8
10000
1000
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
1000
10000
GAS FLOW, ACFM
100000
300000
517
-------
FIGURE 147
CAPITAL COSTS FOR WET SCRUBBERS
FOR VERTICAL LIME ROCK KILNS
(HIGH EFFICIENCY)
500000.
100000
CO
cc
to-
O
U
o.
<
u
10000
1000
TURNKEY SYSTEM:
COLLECTOR PLUS
AUXILIARIES"
COLLECTOR ONLY
1000
10000
GAS FLOW, ACFM
100000
300000
518
-------
FIGURE 148
ANNUAL COSTS FOR WET SCRUBBERS
FOR VERTICAL LIME ROCK KILNS
(HIGH EFFICIENCY)
500000
100000
O
Q
te
o
O
10000
1000
TOTAL
.(OPERATING COST PLUS
CAPITAL CHARGES)
OPERATING COST
10000
GAS FLOW, ACFM
100000
300000
519
-------
TABLE 192
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS FOR VERTICAL LIME ROCK KILNS
(HIGH EFFICIENCY)
Population Size - 20 Sample Size - 3
Capital Cost = $38,471
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $ 31,783 $ 45,160
75 25,512 51,431
90 15,862 61,080
95 6,940 70,003
Capital Cost = $62,986
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $ 50,488 $ 75,485
75 38,770 87,203
90 20,739 105,234
95 4,065 121,908
520
-------
FIGURE 149
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS FOR VERTICAL LIME ROCK KILNS
(HIGH EFFICIENCY)
500000
CO
cc
o
a
te
o
o
a.
<
O
100000
10000
1000
1
^
4
«
•
x'
,*•
X*
••-
-
^
, ^
^
» '
<«
ir
^'
-M
IT
9
•>'
*
X
>
^
^
F
^
«•
• '
«
**
^ ^
*^ ^*
^
• ^*
^
^^"
+*>'
rV*
f*#J
.*&*
^
*^€r
^•ft''
*'
i
^
~
^^<
-•*
. !
*
* l\
30°X
75°X
/IE AN
' 75%
- !
50°/
1000 10000 100000 300000
GAS FLOW, ACFM
521
-------
TABLE 193
FABRIC FILTER PROCESS DESCRIPTION FOR
VERTICAL LIME ROCK KILN SPECIFICATION
The fabric filter is to remove entrained limestone and lime dust from the exhaust gas of
a vertical lime rock kiln. The kiln is fired with natural gas. A portion of the hot exhaust gas
from the calcining zone is recirculated for heat recovery. The kiln is fed with 6 to 8 in. sized
pieces of high calcium limestone.
The exhaust gas is to be brought from the kiln exhaust ports to a location 20 feet
outside of the kiln enclosure by means of a fan. The fabric filter will be located in an area
free of space limitations. The fan is to follow the filter and the fan outlet is to be five feet
above grade.
The fabric filter is to be compartmented to allow for isolation of an individual
compartment for cleaning during operation. A single compartment should have a maximum
of 25% of the total collecting surface area. Each section should also be capable of isolation
for maintenance and have provisions for personal safety during filter operation. No more
than two bags must be removed to permit access to all of the bags. The dust collecting
process should be continuous and should include the following:
1. Compartmented fabric filter operating with negative pressure.
2. Maximum air to cloth ratio, when one compartment is down for cleaning, of 1.80.
3. Fiberglass bags.
4. Reverse air type cleaning system. This air is to be recirculated.
5. Insulation of entire filter system.
6. Trough hoppers with a minimum side and valley angle of 67.5°. The hoppers
should be capable of retaining the dust collected over 24 hours of normal
operation.
7. Oversized screw conveyor system which includes a 9 in. diameter (min) conveyor
with a rotary air lock at its end.
8. Dust bin sized for seven days storage capacity which is to be adjacent to the filter
and have a 15 foot clearance from grade.
9. Necessary fans and motors.
522
-------
TABLE 194
FABRIC FILTER OPERATING CONDITIONS FOR
VERTICAL LIME ROCK KILN SPECIFICATION
Two sizes of fabric filters are specified for the "high efficiency" level. Vendors'
quotations should 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
Kiln Capacity, ton/day
Process wt., Ib/hr
Inlet Gas
Flow, ACFM
Temp., °F
Flow, SCFM
% Moisture (vol)
Dew Point, °F
Inlet Solids Rate, Ib/hr
Inlet Solids Loading, gr/ACF
Inlet Solids Loading, gr/DSCF
100
15,000
7,300
275
5,300
12
122
80.7
1.29
2.02
350
51,000
25,500
275
18,400
12
122
288.5
1.32
2.02
High Efficiency
Outlet Solids Rate, Ib/hr
Outlet Solids Loading, gr/ACF
Outlet Solids Loading, gr/DSCF
Collector Efficiency, wt. %
Air-To-Cloth Ratio
0.63
0.01
0.015
99.22
1.5/1
2.19
0.01
0.015
99.24
1.5/1
523
-------
TABLE 195
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR FABRIC FILTERS FOR VERTICAL LIME ROCK KILNS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
( 1 ) Gas Cleaning Device Cost
(2) Auxiliaries Cost
(a) Fan(s)
(b) Pump(s)
(c) Damper(s) Emer . Temp . a
(d) Conditioning,
Equipment
(e) Dust Disposal
Equipment
(3) Installation Cost
(a) Engineering
(b) Foundations
& Support
Ductwork
Stack
* Electrical
Piping
* Insulation
Painting
Supervision
* Startup
Performance Test
Other
(4) Total Cost
LA Process Wt.
Small
.r
Large
High Efficiency
Small
7,300
275
5,300
12
1.29
80.7
7,300
275
5,300
12
0.01
0.63
99.22
30,573
2,556
2,000
5,850
29,234
70,213
Large
25,500
275
18,400
12
1.32
288.5
25,500
275
18,400
12
0.01
2.19
99.24
78,427
6,213
2,000
5,850
52,318
144,808
*Not included.
524
-------
FIGURE 150
CAPITAL COSTS FOR FABRIC FILTERS
FOR VERTICAL LIME ROCK KILNS
500000
CO
cc
O
o
te
8
0.
<
o
100000
10000
1000
— TURNKEY SYSTEM
COLI
AL
(
-ECTOR PLUi
JXILIARIES
:OLLE
CTC
)R
•»
ON
s
/
/
L>
I?
131
f
S
/
/
^
'
/
/*
_^s~
r
.S
^r*
SjS
S
*
^
gf
Se--S
JO
'
1000 10000 100000 3000C
GAS FLOW, ACFM
525
-------
TABLE 196
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR FABRIC FILTERS FOR VERTICAL LIME ROCK KILNS
CJl
NJ
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
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$.011/kw-hr
LA Process Wt.
Small
Large
High Efficiency
Small
8,000
9,000
200
9,200
400
400
1,980
1,980
11,580
6,821
18,401
Large
8,000
12,000
600
12,600
1,400
1,400
6,600
6,600
2-0,600
14,481
35,081
-------
FIGURE 151
ANNUAL COSTS FOR FABRIC FILTERS
FOR VERTICAL LIME ROCK KILNS
500000
100000
CO
cc
o
0
fe
o
u
10000
1000
TOTAL COST
(OPERATING COST PLUS
CAPITAL CHARGES)
10000
GAS FLOW, ACFM
100000
300000
527
-------
TABLE 197
ELECTROSTATIC PRECIPITATOR PROCESS DESCRIPTION FOR
VERTICAL LIME ROCK KILN SPECIFICATION
A single electrostatic precipitator is to remove entrained limestone and lime dust from
the exhaust gas of a vertical lime rock kiln. The kiln is fired with natural gas. A portion of
the hot exhaust gas from the calcining zone is recirculated for heat recovery. The kiln is fed
with 6 to 8 in. sized pieces of high calcium limestone.
The exhaust gas is to be brought from the kiln exhaust ports to a location 20 feet
outside of the kiln enclosure and 20 feet above grade by means of a fan. The precipitator
will be at ground level in an area beyond the ductwork which is free of space limitations.
The fan will follow the precipitator. The precipitator is to reduce continuously the kiln
outlet loading to the levels specified.
The precipitator system should include the following:
1. Precipitator provided with a minimum of two independent electrical fields in the
direction of gas flow.
2. Trough type hoppers equipped with continuous dust removal by screw conveyor
to a dust tank. The conveying system must be provided with suitable sealing for
negative pressure operation.
3. Automatic voltage control.
4. Safety interlocked system which prevents access to the interior of the precipitator
unless the electrical circuitry is disconnected and grounded.
5. Rapping system which is adjustable in terms of both intensity and rapping period.
6. Necessary fans and motors.
7. Model study for precipitator gas distribution.
528
-------
TABLE 198
ELECTROSTATIC PRECIPITATOR OPERATING CONDITIONS FOR
VERTICAL LIME ROCK KILN SPECIFICATION
Two sizes of precipitators are to be quoted for each of two efficiency levels. Vendors'
quotations should consist of four separate and independent quotations.
Kiln Capacity, ton/day
Process wt., Ib/hr
Inlet Gas
Flow, ACFM
Temp., °F
Flow, SCFM
% Moisture (vol)
Dew Point, °F
Inlet Solids Rate, Ib/hr
Inlet Solids Loading, gr/ACF
Inlet Solids Loading, gr/DSCF
Small
350
51,000
25,500
275
18,400
12
122
288.5
1.32
2.08
Case 1 - Medium Efficiency'
Outlet Solids Rate, Ib/hr
Outlet Solids Loading, gr/ACF
Outlet Solids Loading, gr/DSCF
Collection Efficiency, wt. %
Drift Velocity, fps
35.9
0.16
0.25
87.6
0.25
Case 2 — High Efficiency *
Outlet Solids Rate, Ib/hr
Outlet Solids Loading, gr/ACF
Outlet Solids Loading, gr/DSCF
Collection Efficiency, wt. %
Drift Velocity, fps
2.19
0.01
0.015
99.24
0.25
Large
700
102,000
50,900
275
36,700
12
122
615.2
1.41
2.08
40.0
0.09
0.14
93.5
0.25
4.36
0.01
0.015
99.29
0.25
*Seepage 6 for definition of collection efficiency levels.
529
-------
TABLE 199
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR ELECTROSTATIC PRECIPITATORS FOR VERTICAL LIME ROCK KILNS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol.
%
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol.
%
Cleaned Gas Contaminant 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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
»
LA Process Wt.
Small
25,500
275
18,400
12
1.32
288.5
25,500
275
18,400
12
0.16
35.9
87.6
52,705
23,713
-
45,140
•
121,558
Large
50,900
275
36,700
12
1.41
615
50,900
275
36,700
12
0.09
40
93.5
71,995
36,665
68,400
177,060
High Efficiency
Small
25,500
275
18,400
12
1.32
288.5
25,500
275
18,400
12
0.01
2.19
99.24
67,745
25,838
60,060
153,643
Large
50,900
275
36,700
12
1.41
615
50,900
275
36,700
12
0.01
4.36
99.29
95,515
38,225
82,350
216,090
530
-------
TABLE 200
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR ELECTROSTATIC PRECIPITATORS FOR VERTICAL LIME ROCK 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
Annualized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$6/hr
$.011/kw-hi
LA Process Wt.
Small
2,000
2,000
1,072
1,072
600
600
1,320
1,320
4,992
12,156
17,148
Large
2,000
2,000
2,139
2,139
1,200
1,200
3,080
3,080
8,419
17,706
26,125
High Efficiency
Small
2,000
2,000
1,072
1,072
600
600
3,036
3,036
6,708
15,364.
22,072
Large
2,000
2,000
2,139
2,139
1,200
1,200
5,984
5,984
11,323
21,609
32,932
Ul
00
-------
FIGURE 152
CAPITAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR VERTICAL LIME ROCK KILNS
(MEDIUM EFFICIENCY)
500000
CO
oc
§
te
8
100000
10000
1000
_x
^
X
X
^
^G
^^
&"
X
x
^
x
^
>
^
J
X1
T
*
*
-**
'
UF
^
X
^1
^
^
\
\
C(
*•
^
IK
1
1
DL
A
E
.L
U
COL
Y SYSTEI\
ECTOR PI
XILIARIE
LECTOR (
1
LUS
S
DNLYl
1000 10000 100000 3000G
GAS FLOW, ACFM
532
-------
FIGURE 153
ANNUAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR VERTICAL LIME ROCK KILNS
(MEDIUM EFFICIENCY)
500000
100000
CO
cc
§
te
8
10000
1000
^
TOTAL COST
(OPERATING COST PLUS
— CAPITAL CHARGES) —
OPERATING COST
10000
GAS FLOW, ACFM
100000
300000
533
-------
FIGURE 154
CAPITAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR VERTICAL LIME ROCK KILNS
(HIGH EFFICIENCY)
500000
100QOO
V)
cc
o
Q
O
O
O
10000
1000
-TURNKEY SYSTEM —
COLLECTOR PLUS —
AUXILIARIES
COLLECTOR ONLY-
1000
10000
GASFLOW,ACFM
100000
300000
534
-------
FIGURE 155
ANNUAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR VERTICAL LIME ROCK KILNS
(HIGH EFFICIENCY)
500QOO
C/3
CC
O
Q
te
O
U
100000
10000
1000
X
X
*s
/*
>
x^
>
(C
x
^
)PE
Cfl
if
s
1
R>
kp
/
•o
M
T
^
O
T
•|
A
*E
A
SI
.
;F
LCOST
G COST PI
CHARGES
.US
M
; ATI NG COST"
1000 10000 100000 300000
GAS FLOW, ACFM
535
-------
TABLE 201
CONFIDENCE LIMITS FOR CAPITAL COST
OF ELECTROSTATIC PRECIPITATORS FOR VERTICAL LIME ROCK KILNS
(HIGH EFFICIENCY)
Population Size - 20 Sample Size - 2
Capital Cost = $153,643
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $143,515 $163,770
75 131,215 176,070
90 107,138 200,147
95 81,134 226,151
Capital Cost-$216,090
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $185,127 $247,053
75 147,521 284,659
90 73,910 358,270
95 5,594 437,774
536
-------
FIGURE 156
CONFIDENCE LIMITS FOR CAPITAL COST
OF ELECTROSTATIC PRECIPITATORS FOR VERTICAL LIME ROCK KILNS
(HIGH EFFICIENCY)
500000
CO
cc
o
Q
te
o
O
u
100000
10000
1000
*x
J**^
£
>V
~
//
^
.— *
X
^1
/
'/
4*
*~
«
*TJ
*.
f
V
*r
')*,
i
f
*
'
^
>
^
f
'
*
•
90%
'
I
'
)(
rs
A
'5
I0/
%
BAN
%
1000 10000 100000 3000C
GAS FLOW, ACFM
537
-------
TABLE 202
WET SCRUBBER PROCESS DESCRIPTION FOR
ROTARY LIME SLUDGE KILN SPECIFICATION
The scrubber is to remove entrained lime dust and soda fume from the exhaust gas of a
rotary kiln used to produce reburned lime for the sulfate pulping process. The kiln is fired
with natural gas. The kiln is fed with lime sludge containing 55 wt.% solids. If the sludge has
been washed properly, it will contain about 0.5 wt.% sodium, expressed as Na^O on a dry
lime mud basis. However, this is not always the case and the sludge to this kiln has a sodium
content, expressed as Na2O, of about 2.0 wt. %. The feed end of the kiln is equipped with a
dust fallout chamber and a heat recuperating chain system.
The exhaust gas will be brought from the feed end housing to a fan located 20 feet to
one side of the kiln enclosure. The fan outlet is to be five feet above grade. The scrubber will
be located beyond the fan in an area free of space limitations. The scrubber should be
designed to withstand the discharge pressure developed by the fan. Clean makeup water is to
be added to the recirculation tank. The scrubber is to operate so as to reduce continuously
the kiln outlet loading to the levels specified.
The scrubbing system should include the following:
1. Scrubber with a variable throat Venturi, flooded elbow, and a cyclonic
entrainment separator.
2. Fifty foot stack following the scrubber.
3. Recirculation tank and pumps.
4. Slurry settler, which will handle a portion of the recirculation pump discharge,
capable of producing a reasonably thickened underflow product while returning
water fully treated to minimize solids content. Slurry withdrawal should be set to
maintain 10% (by weight) solids when the kiln is operating at design capacity.
5. Minimum of two filters to dewater the slurry product, capable of producing a cake
with a minimum of 65% (by weight) solids.
6. Necessary fans, dampers, and motors.
7. Necessary controls.
8. Carbon steel construction.
9. Packing glands flushed with fresh water to prevent binding of the seals.
538
-------
TABLE 203
WET SCRUBBER OPERATING CONDITIONS FOR
ROTARY LIME SLUDGE KILN SPECIFICATION
Two sizes of wet scrubbers are to be quoted for each of two efficiency levels. Vendors'
quotations should consist of four separate and independent quotations.
Kiln Capacity, ton/day
Process wt, Ib/hr
Inlet Gas
Flow, ACFM
Temp., °F
Flow, SCFM
% Moisture (vol)
Inlet Loading
Solids Rate, Ib/hr
Solids Loading, gr/DSCF
Rate, Ib/hr
Loading, ppm
Wt. % Soda Fume, as Na20
Outlet Gas
Flow, ACFM
. Temp.,°F
% Moisture (vol)
Small
120
31,000
34,000
350
22,000
35
947.4
7.62
9.9
85
1.8
28,200
168
39
Large
400
103,400
120,000
350
77,000
35
3,702.6
8.64
34.5
85
1.8
99.600
168
39
Case 1 - Medium Efficiency
Outlet Solids Rate, Ib/hr
Outlet Solids Loading, gr/DSCF
Efficiency, wt.%
Scrubber, A P
25.7
0.21
97.3
16 in. w.c.
Case 2 — High Efficiency
Outlet Solids Rate, Ib/hr
Outlet Solids Loading, gr/ACF
Outlet Solids Loading, gr/DSCF
Efficiency, wt.%
Wt.% Soda Fume Removal Efficiency
Scrubber, A P
2.42
0.01
<0.015
99.74
95
40 in. w.c.
40.0
0.09
98.9
16 in. w.c.
8.54
0.01
<0.016
99.77
95
40 in. w.c.
539
-------
TABLE 204
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR ROTARY LIME SLUDGE KILNS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. c
-0
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. c
/o
Cleaned Gas Contaminant 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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other J
(4) Total Cost
>
LA Process Wt.
Small
34,000
350
22,000
35
3.25
947.4
28,200
168
22,000
39
0.11
25.7
97.3
15,627
12,196
45,542
73,365
Large
120,000
350
77,000
35
3.60
3,702.6
99,600
168
77,000
39
0.05
40.0
98.9
32,214
33,623
72,037
137,874
High Efficiency
Small
34,000
350
22,000
35
3.25
947.4
28,200
168
22,000
39
0.01
2.42
99.74
18,610
17,027
53,042
88,679
Large
120,000
350
77,000
35
3.6C
3,702.6
99,600
168
77,000
39
O.ffl
8.2
99.7/
36,997
45,557
83,703
166,257
*Not included.
540
-------
TABLE 205
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR WET SCRUBBERS FOR ROTARY LIME SLUDGE 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
Annualized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$.011/kw-hi
$.25/M gal
LA Process Wt.
Small
8,000
2,223
1,389
1,389
13,386
2,477
15,863
19,475
7,337
26,812
Large
8,000
3,312
2,404
2,404
45,293
9,011
54,304
60,020
13,787
73,807
High Efficiency
Small
8,000
2,889
1,833
1,833
22,117
3,435
25,552
30,274
8,868
39,142
Large
8,000
4,345
9,351
9,351
73,705
12,261
85,966
99,662
16,626
116,288
Ul
-t.
-------
FIGURE 157
CAPITAL COSTS FOR WET SCRUBBERS
FOR ROTARY LIME SLUDGE KILNS
(MEDIUM EFFICIENCY)
500000
V)
DC
fc
o
o
t
a.
O
100000
10000
1000
'
c
•URNKEY SYSTEM i
^
OLLECTOR PLUS .
AUXILIARIES'^
COLLE
-------
FIGURE 158
ANNUAL COSTS FOR WET SCRUBBERS
FOR ROTARY LIME SLUDGE KILNS
(MEDIUM EFFICIENCY)
500000
c/j
tc
o
a
te
8
100000
10000
1000
(0
PI
C)
EF
M
T
\t
>l
OTAL COS
kTING COS
TAL CHAF
OPERA
T
TPLU
GES)
TING
S ^
tf
^oo
*J\J&
/
T
r
X
/
/
A
f
/
/
/
jf
^T S^
jrf f
of
P
1000 10000 100000 300000
GAS FLOW, ACFM
543
-------
FIGURE 159
CAPITAL COSTS FOR WET SCRUBBERS
FOR ROTARY LIME SLUDGE KILNS
(HIGH EFFICIENCY)
500QOO
V)
cc
o
Q
I
O
Q.
<
O
100000
10000
1000
I
:c
IL
A
L
LJ
TURNKE'
ECTOR PL
XILIARIES
COLLECT
/SYS
^
_^r
vss
/
OR or
FEM
rV
jgr
^
^
&
JLY
F^
s
'
s
'
/
'
'
s
^
/
s
+
/
^
*s
s^
J?5
r
^*
^
1000 10000 100000 300000
GASFLOW.ACFM
544
-------
FIGURE 160
ANNUAL COSTS FOR WET SCRUBBERS
FOR ROTARY LIME SLUDGE KILNS
(HIGH EFFICIENCY)
500000
CO
cc
o
o
I
100000
10000
1000
>
TOTAL COST
(OPERA
(
JX\
iP
II
D
TING COS1
•AL CHAR(
'ERATING
FPLUS *
SEsr;
COST
w
0f
<£J
/
f
r
y
v
r
4
f
/
r
/
f
/
/
A
^
Jf)
*
1000 10000 100000 300000
GAS FLOW, ACFM
545
-------
TABLE 206
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS FOR ROTARY LIME SLUDGE KILNS
(HIGH EFFICIENCY)
Population Size — 20 Sample Size — 3
Capital Cost = $88,679
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $ 70,015 $107,342
75 52,516 124,841
90 25,590 151,767
95 691 176,666
Capital Cost-$166,257
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $143,333 $189,181
75 121,840 210,674
90 88,768 243,746
95 58,187 274,327
546
-------
FIGURE 161
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS FOR ROTARY LIME SLUDGE KILNS
(HIGH EFFICIENCY)
500000
100000
CO
DC
O
Q
te
8
a.
<
O
10000
1000
90%
• MEAN
90% X
1000
10000
GAS FLOW, ACFM
100000
300000
547
-------
TABLE 207
ELECTROSTATIC PRECIPITATOR PROCESS DESCRIPTION FOR
ROTARY LIME SLUDGE KILN SPECIFICATION
A single precipitator is to remove entrained lime dust or soda fume from the exhaust
gas of a rotary kiln used to produce reburned lime for the sulfate pulping process. The kiln is
fired with natural gas. The kiln is fed with lime sludge containing 55 wt. % solids. If the
sludge has been washed properly, it will contain about 0.5 wt.% sodium, expressed as Na^O
on a dry mud basis. However, this is not always the case, and the sludge to this kiln has a
sodium content, expressed as Na^), of about 2.0 wt.%. The feed end of the kiln is equipped
with a dust fallout chamber and heat recuperating chain system.
The exhaust gas is to be brought from the feed end housing to a location 20 feet to one
side of the kiln enclosure and 20 feet above grade. The precipitator will be at ground level in
an area beyond the ductwork which is free of space limitations. A fan will exhaust the
precipitator outlet gas to a 50 foot high stack. The precipitator is to reduce continuously the
kiln outlet loading to the levels specified.
The precipitator system should include the following:
1. Precipitator provided with a minimum of two independent electrical fields in the
direction of gas flow.
2. Trough type hoppers equipped with continuous dust removal by screw conveyor
to a dust tank. The conveying system must be provided with suitable sealing for
negative pressure operation.
3. Automatic voltage control.
4. Safety interlocked system which prevents access to the interior of the precipitator
unless the electrical circuitry is disconnected and grounded.
5. Flapping system which is adjustable in terms of both intensity and rapping period.
6. Necessary fans and motors.
7. Model study for precipitator gas distribution
548
-------
TABLE 208
ELECTROSTATIC PRECIPITATOR OPERATING CONDITIONS FOR
ROTARY LIME SLUDGE KILN SPECIFICATION
Two sizes of precipitators are to be quoted for each of two efficiency levels. Vendors'
quotations should consist of four separate and independent quotations.
Kiln Capacity, ton/day
Process wt., Ib/hr
Inlet Gas
Flow,ACFM
Temp., °F
Flow, SCFM
% Moisture (vol >
Dew Point, °F
Inlet Loading
Total Solids Rate, Ib/hr
Total Solids Loading, gr/ACF
Total Solids Loading, gr/DSCF
, Ib/hr
, ppm (vol)
, Ib/hr
afO3, gr/ACF
Na£O4, Ib/hr
Na ^S04, gr/ACF
Small
120
31,000
34,000
350
22,000
35
163
947.4
3.25
7.70
10.0
85
14.0
0.96
0.8
0.006
Large
400
103,400
120,000
350
77,000
35
163
3,702.6
3.60
8.55
35.1
85
49.5
0.96
2.9
0.006
Case 1 - Medium Efficiency'
Outlet Solids Rate, Ib/hr
Outlet Solids Loading, gr/ACF
Outlet Solids Loading, gr/DSCF
Collection Efficiency, wt. %
Drift Velocity, fps
25.7
0.09
0.21
97.3
0.25
Case 2 - High Efficiency *
Outlet Solids Rate, Ib/hr 2.92
Outlet Solids Loading, gr/ACF 0.01
Ou tlet So/ids L oading, gr/DSCF 0.02
Collection Efficiency, wt.% 99.69
Wt. % Soda Fume Removal Efficiency 95
Drift Velocity, fps 0.25
*See page 6 for definition of collection efficiency levels.
40.0
0.04
0.095
98.9
0.25
10.28
0.01
0.02
99.72
95
0.25
549
-------
TABLE 209
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR ELECTROSTATIC PRECIPITATORS FOR ROTARY LIME SLUDGE KILNS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant 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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other _,
^
(4) Total Cost
LA Process Wt.
Small
34,000
350
22,000
35
3.25
947.4
34,000
350
22,000
35
0.09
25.7
97.3
67,260
25,963
60,310
153,533
Large
120,000
350
77,000
35
3.60
3,702.6
120,000
350
77,000
35
0.04
40
98.9
137,405
46,153
130,228
313,786
High Efficiency
Small
34,000
350
22,000
35
3.25
947.4
34,000
350
22,000
35
0.01
2.9
99.69
80,190
29,848
74,770
184,808
Large
120,000
350
77,000
35
3.60
3,702.6
120,000
350
77,000
35
0.01
10.2
99.72
158,970
48,090
142,300
349,360
550
-------
TABLE 210
ANNUAL OPERATING COST DATA (COSTS IN $/YR)
FOR ELECTROSTATIC PRECIPITATORS FOR ROTARY LIME SLUDGE 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
Annualized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr
$6/hr
$.011/kw-hr
LA Process Wt.
Small
2,000
2,000
1,429
1,429
1,000
1,000
2,178
2,178
6,607
15,353
21,960
Large
2,000
2,000
5,044
5,044
2,000
2,000
8,888
8,888
17,932
31,379
49,311
High Efficiency
Small
2,000
2,000
1,429
1,429
1,000
1,000
4,796
4,796
9,225
18,481
27,706
Large
2,000
2,000
5,044
5,044
2,000
2,000
12,628
12,628
21,672
34,936
56,608
en
01
-------
FIGURE 162
CAPITAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR ROTARY LIME SLUDGE KILNS
(MEDIUM EFFICIENCY)
500000
100000
CO
DC
O
O
te
O
O
_l
<
t
0.
O
10000
1000
TURNKEY SYSTEM
COLLECTOR PLUS
AUXILIARIES^
COLLECTOR ONLY
1000
10000
GAS FLOW, ACFM
100000
300000
552
-------
FIGURE 163
ANNUAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR ROTARY LIME SLUDGE KILNS
(MEDIUM EFFICIENCY)
500000
CO
DC
o
Q
65
o
u
100000
10000
1000
PL
(
u
o
s
.>
TOTAL COST
PERATING COST
CAPITAL CHARGE
>
S
f*
ES)
G/
¥0
/
j
x
'
x
'
>
/
X
/*
X
X
rf
'
/
/
/
^
x^
x
X
OPERATING COST
1000 10000 100000 300000
GAS FLOW. ACFM
553
-------
FIGURE 164
CAPITAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR ROTARY LIME SLUDGE KILNS
(HIGH EFFICIENCY)
500000
100000
CO
DC
O
G
te
O
O
_J
<
H
Q.
O
10000
1000
TUF
KEY SYSTEM
COLLECTOR PLUS
AUXILIARIES"
-COLLECTOR ONLY
1000
10000
GASFLOW.ACFM
100000
300000
554
-------
FIGURE 165
ANNUAL COSTS FOR ELECTROSTATIC PRECIPITATORS
FOR ROTARY LIME SLUDGE KILNS
(HIGH EFFICIENCY)
500000
O
O
to*
O
O
Q.
<
O
100000
10000
1000
10(
p
LI
K
j;
)F
C
T
E
:fi
3TAL COS
RATING C
iPITAL'CH
T
OST |
ARGE
>
s~
OPERATING COST
^4
&
S)
aS
\o
X*
X
x
'
x
/
*
+
s
^.x
x
*
JO 10000 100000 300000
GAS FLOW,ACFM
555
-------
TABLE 211
CONFIDENCE LIMITS FOR COLLECTOR ONLY COST
OF ELECTROSTATIC PRECIPITATORS FOR ROTARY LIME SLUDGE KILNS
(HIGH EFFICIENCY)
Population Size — 20 Sample Size — 2
Collector Only Cost = $80,190
Capital Cost, Dollars
Conf. Level, % Lower Limit • Upper Limit
50 $ 74,417 $ 85,964
75 67,404 92,976
90 53,678 106,702
95 38,853 121,527
Collector Only Cost = $158,970
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $148,039 $169,901
75 134,763 183,177
90 108,776 209,164
95 80,709 237,231
556
-------
FIGURE 166
CONFIDENCE LIMITS FOR COLLECTOR ONLY COST
OF ELECTROSTATIC PRECIPITATORS FOR ROTARY LIME SLUDGE KILNS
(HIGH EFFICIENCY)
500000.
o
Q
te
8
_j
<
t
Q.
O
100000
10000
1000
onn/
^
yu% ^ *•
* ^
7b% X*x
IMFAfViX*,
7R%XX
o' *
^
*
X
x
,
X
»
«
"
^
^
«^
*
'
X
1
^
p-
1000 10000 100000 3000C
GAS FLOW,ACFM
557
-------
REFERENCES
1. Study of Technical & Cost Information for Gas Cleaning Equipment in
the Lime & Secondary Non-ferrous Metallurgical Industries, Industrial Gas
Cleaning Institute, 1970, pp. 24-61.
2. Lewis, C. J. & Crocker, B. B., "The Lime Industry's Problem of Airborne
Dust," J.A.P.C.A., 19(1): 31-39 (Jan. 1969).
3. Boynton, R. S., The Chemistry & Technology of Lime & Limestone,
Interscience Publishers, N.Y., 1966.
4. Schwarzkopf, F., "Comparison of Modern Lime Calcining Systems," Rock
Products, 73:68-71+ (July, 1971).
5. Stern, A. C., Air Pollution, Vol. Ill, Academic Press, N.Y., 1968, pp.
243-267.
6. Shreve, R. N., The Chemical Process Industries, McGraw-Hill Book
Company, Inc., N.Y., 1956.
7. Casey, J. P., Pulp & Paper, Vol. 1 — Pulp & Bleaching, Interscience
Publishers, N.Y., 1960.
8. Britt, K. W., Handbook of Pulp & Paper Technology, Van Nostrand,
ReinholdCo., N.Y., 1970.
9. Stephenson, J. N., Pulp & Paper Manufacture, Vol. 1 — Preparation &
Treatment of Wood Pulp, McGraw-Hill Book Co., N.Y., 1950.
10. Rydholm, S. A., Pulping Processes, Interscience Publishers, N.Y., 1965.
11. Duprey, R. L., Compilation of Air Pollutant Emission Factors, U. S.
DHEW, Public Health Service, Publication No. 999-HP-42, Durham, North
Carolina, 1968.
12. Stuart, H. H., & Bailey, R. E., "Performance Study of a Lime Kiln &
Scrubber Installation," TAPPI, 48(5):104A-108A (May, 1965).
13. Shah, I. S., "Pulp Plant Pollution Control," Chem. Eng. Progress, 64(9):
66-77 (Sept., 1968).
558
-------
14. Collins, T. T., Jr., "The Venturi Scrubber on Lime Kiln Stack Gases":
TAPPI, 42(1): 9-13 (Jan., 1959).
15. Landry, J. E., and Longwell, D. H., "Advances in Air Pollution Control in
the Pulp & Paper Industry," TAPPI, 48(6): 66A-70A (June, 1965).
16. Walker, A. B., & Hall, R. M., "Operating Experience with a Fjooded Disc
Scrubber. . .," J.A.P.C.A., 18(5): 319-23 (May, 1968).
17. Walther, J. E., and Amberg, H. R., "A Positive Air Quality Control
Program at a New Kraft Mill," J.A.P.C.A.; 20(1): 9-18 (Jan., 1970).
559
-------
560
-------
GRAY IRON FOUNDARIES
-------
7. GRAY IRON FOUNDRIES
Iron foundries are shops where iron and steel are melted and cast. These
shops exist over a wide range of sizes from small family businesses to large
shops owned by giant corporations. The total foundry population has shown a
steady decline since the end of World War II from 3,200 in 1947 to 1,600 in
1971 mostly due to closing small shops. The size of the average foundry has
risen from an annual production of 3,800 to 8,700 tons'1' during the same
period. These figures show that while small foundries are closing down, their
production is being more than offset by new large foundries, resulting in a slow
but positive growth in total foundry capacity. The distribution of foundry sizes
in 1969 is shown in Figure 167.(2)
Small foundries are generally defined as those which employ less than 50
people. They are most often "jobbing" foundries which make small quantities
or job lots of a variety of cast products for independent customers. Large
foundries are often described as captive in that they are owned by their
principal customer. They tend to produce large quantities of a few specialized
castings. Examples of industries which rely mainly on captive foundries are
automobile manufacturers and cast iron pipe producers.
Iron foundries produce three forms of cast iron: gray iron, ductile iron,
and malleable iron. Gray iron is produced in the greatest amount as indicated
on Table 212.(1) All three forms of cast iron are alloys composed principally of
iron and carbon.
All three contain carbon in the graphitic form. They differ from one
another by the size and shape of the graphite particles dispersed throughout the
alloy. The graphite in gray iron appears in large crinkled flakes. The flakes have
no strength and cause the casting to be brittle. When gray iron castings are
broken, the fracture goes through the graphite flakes, producing a gray color in
the fracture. It is from this property that gray iron gets its name. Gray iron cast
in such a way that all of the carbon occurs as the iron-carbon compound
cementite (Fe3C) is called white iron. Fractures in white iron also occur along
the carbon containing phase. Cementite, however, is steely white in appearance
and the fractures, therefore, are light colored. Iron cast with high carbon and
silicon contents will form gray iron. Lower carbon and silicon contents will
form white iron.'4'
The cementite phase of white iron can be converted into graphite by
heating in the presence of sufficient silicon after the casting has solidified. The
graphite formed by this process is different from the flakes which are present in
561
-------
Ol
o>
to
100
FIGURE 167
DISTRIBUTION OF IRON FOUNDRY SIZES (1969)
y
• .^/~»
j
D
D
0
IO
IS
2S>
-40
MELT CAPACITY , TPH
-------
TABLE 212
AVERAGE ANNUAL FOUNDRY PRODUCTION
IN THE UNITED STATES*11
Average Production Percent of Total
Type of Iron ton/yr* Production
Gray Iron 11,650,000 84.3
Malleable Iron 1,075,000 7.8
Ductile Iron 1,092,000 7.9
Total 13,817,000 100.0
'For the five year period 1965 through 1969.
563
-------
gray iron. The graphite is formed in spheroids which do not embrittle the cast
metal as much as the graphite flakes. As a result some deformation of the
casting is possible without fracture. Metal produced in this way is called
malleable iron. A comparison of the physical properties of gray iron and
malleable iron is presented in Table 213.
Further alteration in the form of the graphite can be made by
innoculating the melt with a small amount of magnesium just before casting.
The result is a cast iron containing very small spherical nodules of graphite. It is
called ductile or nodular iron. It has ductility equivalent to malleable iron and
has greater tensile strength. Its properties are also shown in Table 213.
Differences in the production of these three forms of cast iron are
illustrated in Figure 168.(1)AII of the operations shown apply to all three kinds
of cast iron unless noted otherwise on the drawing.
FOUNDRY OPERATIONS
Foundries engage in a great many separate operations in order to produce
iron castings. The major operations include:
1. Raw material storage
2. Iron melting
3. Pouring
4. Mold making
5. Core making
6. Shakeout
7. Finished product handling
8. Sand reclamation
Figure 169 shows a diagram of the flow through a foundry and relationships
among these eight operations. Most foundries carry out all eight operations,
and all have at least the first three in the list. Most of the eight operations
involve emission sources and these, too, are indicated on the flow diagram.
564
-------
TABLE 213
PROPERTIES OF CAST IRONS
Gray Iron Malleable Iron Ductile Iron
Chemical Composition*"
Carbon, wt.% 3.00 to 3.75 2.00 to 2.65 3.00 to 3.55
Silicon, wt.% 1.10 to 2.80 0.90 to 1.65 2.25 to 2.55
Manganese, wt.% 0.5 0.25 to 1.25 0.50
Magnesium, wt.% - - 0.04 to 0.1
Physical Properties'1)>(4)
Tensile Strength, psi 20,000 to 51,000 50,000 to 77,000 75,000 to 120,000
Yield Strength, psi NA 32,000 to 70,000 28,000 to 45,000
Brinell Hardness 160 to 270 110 to 245 120 to 270
Elongation, % NA 3.5 to 22 1 to 15
Impact Strength, ft-lb 1 to 3 4 to 16 NA
565
-------
FIGURE 168
SCHEMATIC FLOW DIAGRAM
OF CAST IRON PRODUCTION
RAW
MATERIAL
STORAGE
MOUD MAKING
AND
COREMAKING
I
MELTING
AND
HOLDING
LADLE
ADDITIONS
LADLE
POURING
I
I
1
MAGNESIUM
TREATMENT
J (DUCTILE IRON ONLY)
SHAKEOUT
ANNEALING
i
CLEANING
(MALLEABLE IRON ONLY)
I
FINISHING
PRESS
STRAIGHTENING
(DUCTILE AND
MALLEABLE
IRON ONLY)
566
-------
FIGURE 169
FLOW DIAGRAM OF MAJOR IRON FOUNDRY OPERATIONS
METALLICS
FLUXES
SAND
FINISHING
r*
>DUST
CJl
en
-vj
'GAS AND
PARTICULATE
EMISSIONS
GAS AND
PARTICULATE
EMISSIONS
METAL
MELTING
DUCTILE IRON
INNOCULATION
CASTING
SHAKEOUT
COOLING
AND
CLEANING
CORE SAND
AND BINDER
SAND
PREPARATION
-------
Raw materials used in the production of iron castings are iron from
various sources, alloying agents, fluxes, sand, and fuel. The iron is melted in a
furnace and brought to the proper composition with appropriate alloying
agents. The molten metal is then tapped into a ladle and poured into a sand
mold. The mold is cooled, solidifying the metal. The mold is removed from the
casting in the shakeout area and the casting is sent to cleaning and finishing.
Molds and cores are prepared in many ways, depending upon the nature of
the product. Each mold making and core making process has its own recipe and
formulation. In general, sand is mixed with water and a binding agent, and then
formed with a pattern into the desired shape. The mold is dried or heated to fix
the shape prior to pouring. After pouring and cooling, the mold is broken and
the casting removed. This may be done manually or mechanically on a large
vibrating screen. Where possible, the sand from shakeout is recovered and
reclaimed by crushing followed by abrasive or thermal removal of spent binding
agent. The reclaimed sand is sent back to mold making for use in new molds.
Four types of furnaces are used for iron melting in foundries: the cupola,
electric arc, induction, and reverberatory furnaces. Cupolas are the most
numerous but their position is declining relative to electric arc and induction
furnaces. This decline is occurring because cupolas have much higher emission
rates than do the other types. Figure 170 shows the change in the numerical
distribution of furnace types since 1959.(1'
Cupolas are vertical cylindrical furnaces which are charged with alternate
layers of iron, fuel (usually coke), and flux. The energy for melting the iron
comes from the combustion of the coke. Combustion air is forced through the
bed from the bottom with a blower. In some cupolas natural gas is added with
the combustion air as a supplementary fuel, and it is also fairly common
practice to enrich the gas stream with oxygen. Preheating of the combustion
air by direct-fired gas burners may also be used. Slag and molten iron are
withdrawn through separate tapholes at the bottom or in many cases the
cupola has only one taphole for withdrawal of, first the iron and then the
slag.
Electric arc furnaces are cup-shaped vessels with roofs. Three carbpn
electrodes protrude through the roof and extend into the metal charge held by
the furnace. The energy required for melting is obtained from the arc.
Induction furnaces are also cup- or drum-shaped vessels that use electrical
568
-------
FIGURE 170
TRENDS IN TYPES OF IRON
FOUNDRY FURNACES
(1)
0)
Id
{£
D
L
L
0
DC
LJ
ID
I
D
Z
sooo
4SOO
4600
4-4OO
4200
4000
3SOO
3eoo
3400
3200
3OOO
2SOO
26OO
24OO
22OO
2000
i©oo
I6OO
I4OO
I2OO
IOOO
8OO
6OO
4OO
200
TOTAL FURNACES
INDUCTION
ELECTRIC ARC
I959 I96I I963 IQ6S I967 I969 I9TI
I960 I962 I964 IO66 I96S I97O I9T72
YEAR
569
-------
energy to melt metal. Induction furnaces operate on the same principle as
transformers. A primary coil is energized with alternating current, which sets
up a magnetic field around it. The magnetic field induces eddy currents in the
charge which are converted into heat by the electrical resistance of the charge.
The use of reverberatory air furnaces is expected to decline as they
are replaced by electric furnaces.
The melting operation causes the majority of the emissions from a
foundry. Although all types of melting furnaces have significant emissions, the
cupola is by far the most difficult to properly control. The remainder of this
section will be limited to a discussion of control of emissions from cupolas.
THE GRAY IRON CUPOLA
Although its use is steadily declining, the cupola is the work-horse of the
foundry industry. Figure 5 shows a diagram of a typical cupola. The furnace is
a vertical cylinder charged with alternate layers of iron, coke, and flux.
A layer of sand is generally packed into the bottom of the cupola prior to
start up and stays under the iron, coke and flux bed during operation. Air
ports, or tuyeres, are located at the bottom. Blast air is forced into the furnace
through these tuyeres using a forced draft blower.
Air is required for two purposes. The greater portion is used as
combustion air for the coke. This combustion generates the energy for melting
the iron. Additional air is required to combust the carbon, silicon, and
manganese which may be present in the metal to be melted.'3) The amount of
these materials left unoxidized in the molten iron plays a large role in
determining the properties of the cast iron.
The air blown into a cupola may be preheated to increase the thermal
efficiency of the system. Two methods of preheating are available:
1. A separate external preheater for the combustion air.
2. Combustion of the CO in the exhaust gases to C02 followed by heat
exchange with the combustion air.
There is a current EPA demonstration project on recuperative heat
exchange for an iron foundry cupola,(5) however, the method is not used
conventionally.
570
-------
FIGURE 171
TYPICAL GRAY IRON CUPOLA
Cupola cap
Charging skip
Off- take (refractory lined)
Top of charging f bor
Windbox
Blastpipe connection
Tuyere box
Tap hole
and spout
Bottom plate
Bottom doors
Slag spout
Floor level
Concrete foundation
571
-------
The methods involving heat recovery are not in common use at the present
time due to high capital cost, high maintenance cost, and low operating rate
of many foundries.
Raw materials are charged to the furnace through a door located in the
side of the cupola above the charge bed. Small cupolas are charged by hand.
Larger units use mechanical charging equipment such as skip hoists.
Exhaust gases are removed from the cupola either from the top, as
indicated on Figure 171, or through an opening in the side, immediately below
the charging door.
Operation of the cupola is begun by putting coke into the bottom and
igniting it. Additional charge materials are mixed into a charge bin and con-
veyed into the cupola. As the metal melts and the coke is consumed, the entire
contents of the furnace shift downward and are replaced by new charge material.
The melting is generally considered to occur in three zones. As the new charge
moves downward in the cupola, it is preheated by the rising hot combustion
gases. These gases include carbon dioxide, carbon monoxide, nitrogen,
hydrogen, and sulfur dioxide. There is no free oxygen. As the hot metal enters
the second zone, called the melting zone, the atmosphere is highly reducing. As
the molten metal continues downward, it enters the third or combustion zone
where it is superheated to the desired tapping temperature. The atmosphere in
the combustion zone is highly oxidizing.
The gas flow through the cupola is countercurrent to the metal flow. Blast
air enters through the tuyeres into the combustion zone. In this zone it
combines with the coke as follows:
0 + C + C0 + heat
The oxidation of impurities in the metal charge also occurs in this zone. For
example:
Si + 02 +Si02
Some oxidation of iron also occurs.
As the gas moves upward, the oxygen content is depleted and the
following reaction begins to occur to a greater extent:
C02 + C $. 2CO 1 heat
572
-------
Water vapor is also reduced in this zone producing carbon monoxide and
hydrogen as follows:
C + H20 -»- CO + H2 - heat
The maximum concentration of CC>2 (14 to 18%) and maximum
temperature (2,800 to 3,400° F) occur at the boundary of the combustion and
melting zones.11' As the gases enter the preheating zone, they give up heat to
the new charge and their temperature is lowered sufficiently to prevent further
reactions from occuring between carbon, oxygen, and oxides of carbon.
Nature of the Gaseous Discharge
The gases which leave a cupola consist of the combustion products from
the cupola reactions. The principal components are: nitrogen, carbon dioxide,
oxygen, carbon monoxide, hydrogen, and sulfur dioxide.
The oxides of carbon result from the coke as described in the previous
section. Sulfur dioxide results from the combustion of the sulfur contained in
the coke. The nitrogen is brought in with the combustion air. Oxygen appears
primarily as a result of air coming in through the charging door. The relative
proportion of these components is highly variable. It depends primarily upon
the rate of flow and temperature of blast air, the amount of air coming through
the charge door, the cupola operating temperature, the ratio of coke to iron in
the cupola, and the composition of the coke. Table 214 lists some examples
which demonstrate the variability.11'
The rate of flow of exhaust gas is also variable and depends on many of
the same variables which affect the composition of the gas. It is most strongly
influenced by the quantity of blast air and the quantity of air which enters
through the charge door. A good average value is 1,000 SCFM per ton/hr of
melt capacity. The off-gas temperature can vary from 500 to 2,200° F
depending upon: whether a CO afterburner is used, blast air rate, preheat
temperature, and the rate of air entering through the charge door.
The gas discharge temperature is cyclic, and decreases as cold material is
charged into the cupola. The temperature rises gradually as the cold material
warms up. This short cycle, measured in minutes, is superimposed on a longer
cycle of light-off, melting-pouring, and burndown. After a period of a few
hours to a few days of melting, it is necessary to shut the cupola down for
573
-------
H2
TABLE 214
EXHAUST GASES COMPOSITIONS
FROM FOUR DIFFERENT CUPOLAS11'
Mole Percent in Sample
Component A B C D
CO 1320
C02 3 16 4 13
02 17 1 7 7
N2 75 80 86 80
99 100 99 100
574
-------
relining. The resulting "burndown" produces the highest emission temperatures
during the operating cycle, because no cold charge is being added during
burndown. Frequently, two cupolas are operated in tandem, so that one can
melt while another is relined. A single gas cleaning system is used for the pair.
Table 215 shows a weight balance for a theoretical cupola melting one
ton/hr of iron. The theoretical cupola has the following characteristics:
1. Lined construction
2. Gas takeoff above the charge door
3. Charge door open during operation
4. Preheated blast air, unenriched
Pollution Control Considerations
The control system which serves a cupola must deal with at least two
distinct types of emissions: carbon monoxide and paniculate matter. Emission
control systems which deal with these two problems consist of three parts:
1. An afterburner (combustion chamber or upper cupola stack) to
convert CO to COo and to burn organic matter
2. A cooling device to lower the afterburner exit temperature to a level
suitable for conventional abatement equipment
3. A collector to remove particulate matter
The afterburner may consist of a stack above the charge door containing
gas burners or torches. These should be designed to raise the exit gas
temperature to at least 1,200°F.(3) The geometry of the installation should
provide a minimum of 1/4 sec. of residence time. In large cupolas it is necessary
to create sufficient turbulence to insure that the combustibles and air become
properly mixed. This may alter the residence time required. Stratification of
the gas stream in large diameter cupolas can make mixing a problem.
575
-------
TABLE 215
MATERIAL BALANCE FOR THEORETICAL CUPOLA(7)
Input Material Ib/hr wt.%
Pig Iron 97 2.17
Silvery Piglets 66 1.48
Purchased Scrap 873 19.51
Steel Scrap 388 8.67
Returns 582 13.01
Total Metal Charge 2006 44.84
Coke 268 5.99
Natural Gas 0 -
Fuel Oil 0
Flux and Additives 40 0.89
Air 2139 47.81
Oxygen 0 —
Cupola Lining 21 0.47
Total 4474 100
Output Material
Molten Iron 2000 44.95
Slag 53 1.19
Emission Dust 20 .45
Nitrogen 1636 36.77
Carbon Dioxide 489 10.99
Carbon Monoxide 248 5.57
Hydrogen 2 .04
Sulfur Dioxide 1_ .02
Total Off Gases 2376
Total 4449 100
Top Gas Molecular Weight -31.24
Top Gas Rate, SCFM - 461
Dust Concentration, gr/SCF - 5.07
Air in Charge Door, Ib/hr/ton - 1693
CH4 into Afterburner, Ib/hr/ton — 25
Total Gas to Gas Cleaning System, Ib/hr/ton - 6167
576
-------
While the major function of the afterburner is the oxidation of carbon
monoxide for safety and environmental control, two other processes may also
occur. If oily scrap is charged to the cupola, the cupola exit gases will contain
oil aerosol. This oil will be oxidized in the afterburner, to the benefit of the
particulate collection devices which follow. There is also combustible dust in
the exhaust gases, consisting mostly of coke fines (carbon). This, too, is burned
to some extent in the afterburner.
The gases leaving the afterburner are too hot to go directly into a
particulate collector without cooling. Three types of coolers are conventionally
used: quenchers, evaporative coolers, and radiant coolers. Quenchers are
distinguished from evaporative coolers in that quenchers are devices that
adiabatically saturate using an excess amount of water, whereas evaporative
coolers control the amount of cooling by controlling the amount of water
available for evaporation. Cooling by air dilution is not widely practiced
because of the relatively large volumes required and the attendant increase in
the size of the collection device. There is a current EPA demonstration
project on recuperative heat exchange for an iron foundry cupola,151 however,
the method is not used conventionally.
The choice between radiant and direct contact water cooling depends
upon several variables:
1. The nature of the abatement equipment downstream. If a fabric
collector is used, cooling in a quencher could lead to wetting and
blinding the bags.
2. The temperature of the exhaust gas leaving the cupola. Radiant
coolers are efficient only at high temperature levels. Inlet
temperatures which are too high, however, can lead to metallurgy
problems.
3. Costs of utilities and of maintenance labor. Quenchers and
evaporative coolers consume water, may need more maintenance
than radiant coolers, and add to the total gas volume to be handled.
4. Capital cost. Radiant coolers may cost many times more than
quenchers or evaporative coolers.
5. Space. Radiant coolers require more space than quenchers or
evaporative coolers.
For most applications, quenchers or evaporative coolers will be the more
attractive choice because of the lower capital cost.
Collection of particulate matter emitted by cupolas can be accomplished
efficiently by fabric filters, wet scrubbers, and electrostatic precipitators.
Precipitators are usually uneconomical, however, because the exhaust gas rates
are too low.
577
-------
The design of the collector will be influenced by the size distribution of
the particles which are emitted. The distribution varies greatly from cupola to
cupola. Data which demonstrate the extent of this variation are shown in Table
216.
Fabric filters are effective devices in this application and have been used in
many commercial installations. The inlet gas temperature to the fabric filter
must be closely controlled, however, to prevent damage to the bags from high
temperature upsets. Fabric filter systems should have a bypass which is
activated by a high temperature alarm in the inlet gas stream. This bypass may
be the cupola closure cap. Carry-over of incandescent particles or sparks must
also be guarded against in the design of the fabric filter system.
Wet scrubber systems have also been successfully applied as control
devices on cupolas. In most cases, they require a high energy input due to the
small size of the particulate matter emitted from the cupola. In addition, they
are subject to acid corrosion resulting from the dissolving of sulfur oxides from
the cupola top gases in the scrubber recycle liquor. Where sulfur oxides exist in
significant quantity, stainless steels such as 316L must be used in the scrubber
to resist attack.
Table 217 presents a summary of abatement equipment type, and number
of units of that particular type, that have been used for collecting particulate
matter from foundries.
SPECIFICATIONS AND COSTS
Equipment specifications have been written for both fabric filters and wet
scrubbers. In each case, the specification is based upon cupola exhaust gas
leaving the afterburner. The system for both types of equipment includes a gas
cooler followed by the collector and auxiliary equipment. Two different types
of gas coolers were specified, one for each type of collection equipment. The
gas cooling equipment appropriate to each collection device is a legitimate part
of the cost of the abatement system, because no cooling of the gases is required
where collection of particulate matter is not required.
Specifications for the fabric filter system are listed in Tables 218, 219 and
220. Vendors' quotations were not obtained for the two sizes specified in Table
220. The cost data for these two sizes were determined by interpolation and
extrapolation of the cost data obtained for the two sizes specified in Table 219.
578
-------
TABLE 216
PARTICLE SIZE DISTRIBUTIONS
OF EMISSIONS FROM THREE DIFFERENT CUPOLAS
Wt.% Less Than A B
200 microns 99
100 microns 99
50 microns 92 60
20 microns 99 34 55
10 microns 93 12 45
5 microns g2 2 28
2 microns 64 13
579
-------
TABLE 217
ABATEMENT EQUIPMENT TYPES USED FOR
COLLECTING PARTICULATE MATTER FROM FOUNDRIES(6)
Abatement
Equipment
Type
Fabric Filter
Cyclones
Wet Scrubber
Electrostatic Precipitator
In Plant Dust Collection
Number of
Units Installed
5,216
1,216
2,170
50
2,629
Number of
Foundries
2,198
514
778
32
1,122
^Data represents all foundries.
580
-------
Both sets of specifications include an evaporative cooler operating at a maxi-
mum outlet temperature of 400° F. Cost data for the system are presented on
Tables 221 and 222 and on Figures 172 and 173. Also presented on these tables
and figures are the interpolated and extrapolated costs determined for the two
fabric filter sizes specified in Table 220. Confidence limits for the capital cost
data obtained for the two fabric filter sizes specified in Table 219 are presented
on Table 223 and Figure 174.
Specifications for the wet scrubber system are shown on Tables 223 and
224. The specifications include a quencher type gas cooler followed by a venturi
scrubber. For the high efficiency cases, the scrubber is followed by an
aftercooler which reduces the horsepower requirement on the system fan by
condensation. Cost data for the system are presented on Tables 225 and 226
and on Figures 175, 176, 177 and 178. Confidence limits for the capital costs
of the high collection efficiency cases are presented on Table 228 and Figure
179.
Bids were not obtained for afterburners; however, generalized costs were
obtained through private communications.18' The burners range in price from
$5,000 to $10,000/cupola.
The installation cost was estimated to be $2,100. The burner duty ranges
from 5,200,000 Btu/hr/cupola to 16,000,000 Btu/hr/cupola. This corresponds
to an annual fuel cost range of $21,900/yr/cupola to $67,000/yr/cupola. The
fuel requirement is quite varied for cupola afterburners and in many cases the
combustion of carbon monoxide could sustain itself.
Generalized cost breakdown for afterburners is as follows:
Device Cost Range $ 5,000 to $10,000/cupola
Installation Cost $ 2,100 to $2,100/cupola
Total Cost Range $ 7,000 to $12,000/cupola
Fuel Cost Range $21,900 to $67,500/yr/cupola
581
-------
TABLE 218
FABRIC FILTER PROCESS DESCRIPTION
FOR GRAY IRON FOUNDRY CUPOLA SPECIFICATION
Emissions from a pair of new gray iron cupolas are to be controlled with a fabric filter.
The cupolas are to operate alternately, so the emissions from only one need be treated. The
cupolas are conventional refractory lined units. Gas takeoffs are above the charge doors.
Products of combustion and charge door indraft are preheated to a degree sufficient to insure
that the gases leaving the cupola and entering the pollution control system will be 1,20CPF.
Each cupola is operated for 24 hours, then shut down for maintenance while the other cupola is
operating. The operating factor for the abatement system serving the cupolas is 5,280 hr/yr.
The abatement system will consist of:
1. An evaporative cooler
2. A fabric filter
An afterburner will be supplied by others. It will be located in the stack above the charge
door. The geometry of the installation will be arranged to insure sufficient turbulence for
complete combustion. Stack inserts to achieve turbulence may be used if necessary.
The evaporative cooler will be used to lower the temperature of the afterburner exhaust
gas to the required inlet temperature of the fabric collector. The cooler will be designed for a
maximum inlet temperature of 2,20CPF. Sufficient space is available for the installation of the
evaporative cooler at a distance of 15 feet from the cupola. The fabric filter will be located 40
feet from the evaporative cooler. The afterburner exhaust gases leave the top of the cupola
stack at a height of 50 feet above grade.
The fabric filter will be located immediately downstream of the evaporative cooler. The
i inlet gas stream will be monitored with a high temperature alarm and will be diverted out the
\ cupola stack in the event of an alarm condition. The filter will be either a shaker or reverse *\
' collapse type unit designed with a minimum of four isolatable compartments. The unit will
operate under either positive or negative pressure and will be equipped with screw conveyors
and air locks for solids removal. A dust storage bin with a capacity of two days operation will
be provided at the discharge of the screw conveyors. The system fan will be sized with at least
20% excess capacity when operating at the design pressure drop of the entire abatement system
and 90% of the maximum recommended speed.
582
-------
TABLE 219
FABRIC FILTER OPERATING CONDITIONS FOR
GRAY IRON FOUNDRY CUPOLA SPECIFICATION
Two sizes of fabric filters are specified at one efficiency level. Vendors' quotations
should 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
efficiency called for in this specification.
Cupola Inside Diameter, in.
Cupola Melt Rate, ton/hr
Cupola Iron/Coke Ratio
Cupola Process Weight, Ib/hr
A fterburner Exhaust Gas
ACFM
Temperature, °F
SCFM
Solids Loading
Ib/hr
gr/ACF
gr/DSCF
Cooler Outlet Gas
ACFM
Temperature, °F
SCFM
Small
36
6.6
10
14,730
27,500
2,000
5,920
108
0.459
2.42
14,600
400
9,000
Large
90
39.5
10
88,560
145,000
2,000
31,300
540
0.434
2.29
77,100
400
47,500
Solids Size Distribution
% > 10 microns
% < 10 microns
% < 5 microns
% < 1 micron
% < 0.7micron
% < 0.3 micron
68
32
24
11
8
1
68
32
24
11
8
1
Fabric Filter Inlet Gas
ACFM
Temperature, °F
SCFM
14,600
400
9,000
77,100
400
47,500
Solids Loading
Ib/hr
gr/ACF
gr/DSCF
Collector Efficiency, wt.l,
Air-to-cloth ratio
Case 1 — High Efficiency
1.25
0.01
0.018
98.8
2.0/1
6.61
0.01
0.018
99.2
2.0/1
583
-------
584
-------
TABLE 220
FABRIC FILTER OPERATING CONDITIONS FOR
GRAY IRON FOUNDRY CUPOLAS
Two sizes of fabric filters are specified. Vendors' quotations were not obtained for
either of these sizes. Cost data for these two sizes were determined by extrapolating the
cost data obtained for the two fabric filter sizes specified in Table 11.
Small
Cupola Inside Diameter, in.
Cupola Melt Rate, ton/hr
Cupola Iron/Coke Ratio
Cupola Process Weight, Ib/hr
Afterburner Exhaust Gas
ACFM
Temperature, °F
SCFM
Solids L oading
Ib/hr
gr/ACF
gr/DSCF
Cooler Outlet Gas
ACFM
Temperature, °F
SCFM
Fabric Filter Inlet Gas
ACFM
Temperature, °F
SCFM
Solids Loading
Ib/hr
gr/ACF
gr/DSCF
Collector Efficiency, wt.l,
Air-to-cloth ratio
48
10
10
22,400
41,800
2,000
9,000
108
0.302
1.60
22,150
400
13,650
22,150
400
13,650
Case 1 — High Efficiency
1.9
0.01
0.018
98.0
2/1
v/
Large
114
60
10
134,400
220,000
2,000
47,500
540
0.286
1.50
116,930
400
72,060
116,930
400
72,060
585
-------
TABLE 221
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR FABRIC FILTERS FOR
GRAY IRON FOUNDRY CUPOLAS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol.
%
Effluent Contaminant Loading
gr/ACF (ppm)
Ib/hr
Cleaned Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol.
%
Cleaned Gas Contaminant Loading
gr/ACF (ppm)
. 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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
J
(4) Total Cost
/
Extrapolated
Small
41,800
2,000
9,000
2
0.302
108
22,150
400
13,650
35.4
0.01
1.9
98.0
37,000*
45,000*
L03,000*
185,000*
Large
220,000
2,000
47,500
2
0.286
540
116,930
400
72,060
35.4
0.01
10.05
98.3
140,000*
170,000*
390,000*
700,000*
Specified
Small
27,500
2,000
5,920
2
0.459
108
14,600
400
'9"~"6obv
3-5V4— '
0.01
1.25
98.8
26,600
4,500
375
1,550
21,000
2,950
3,700
67,230
127,905
Large
145,000
2,000
31,300
2
0.434
540
77,100
400
47,500
35.4
0.01
6.61
99.2
99,850
21,600
2,375
11,925
,
65,500
21,750
11,700
218,125
s.
452,825
'Extrapolated from Cost Data presented in Figure 6
586
-------
FIGURE 172
CAPITAL COSTS FOR FABRIC FILTERS
FOR GRAY IRON FOUNDRY CUPOLAS
5000000
1000000
oo
cc
o
Q
te
o
U
a.
<
O
100000
10000
Os COST DATA OBTAINED FROM VENDORS' QUOTATIONS
X's INTERPOLATED AND EXTRAPOLATED DATA
Tl 1
1 U
CO
RN
LL
AU
KE
EC'
XII
CC
Y
rc
J>
LI
S
>R
\F
TE
Y
11
C
SI
3L
EJ
T<
/S
blvl
y
S^
S
S
.us
^ ^
/f
DR ONLY
/
S^
\r
*
S
X
/
/
/
f
/
f
/
t
f
VD
0
/
/
j
S
S
JS
S
1000
10000
100000
300000
CLEAN GAS FLOW, ACFM
587
-------
TABLE 222
S
00
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR FABRIC FILTERS FOR
GRAY IRON FOUNDRY CUPOLAS
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
$6/hr
$8/hr
$.011/kw-hr
$.25/M gal
Extrapolated
22,150 ACFM
5 .28(1
26,000*
18,500
44,500
116,930 ACFM
^ ?8f)
60,000*
70,000
130,000
Specified
5,280
3,950
1,050
5,000
4,980
6,000
2,850
2,400
5,250
21,230
12,790
34,020 '
5,280
3,950
1,050
5,000
4,980
16,500
16,900
6,750
23,650
50,130
45,282
95,412
'Extrapolated from Operating Cost Data presented in Figure 7
-------
FIGURE 173
ANNUAL COSTS FOR FABRIC FILTERS
FOR GRAY IRON FOUNDRY CUPOLAS
500000
100000
C/J
DC
O
O
O
O
10000
1000
(OPER
LCAF
TOT
ATI
MTA
0
•AL
NG
L (
C
C
C(
:H>
IPE
3J
DS
^
yr
4\
rioNs
X= INTERPOLATED AND EXTRAPOLATED DATA
1000
10000
CLEAN GAS FLOW, ACFM
100000
300000
589
-------
TABLE 223
CONFIDENCE LIMITS FOR CAPITAL COST
OF FABRIC FILTERS FOR GRAY IRON FOUNDRY CUPOLAS
Population Size - 20 Sample Size - 2
Capital Cost = $127,905
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
90 $124,829 $130,981
75 121,092 134,718
Capital Cost = $452,825
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
/?90\ $350,177 $555,473
C 75 J 225,503 680,147
590
-------
FIGURE 174
CONFIDENCE LIMITS FOR CAPITAL COST
OF FABRIC FILTERS FOR GRAY IRON FOUNDRY CUPOLAS
5,000,000
1,000,000
CO
DC
o
Q
fe
o
U
Q.
<
U
100,000
10,000
>.x
90%.
75%
MEAN
75%
90%
10000
CLEAN GAS FLOW, ACFM
100000
300000
591
-------
TABLE 224
WET SCRUBBER PROCESS DESCRIPTION
FOR GRAY IRON CUPOLA SPECIFICATION
Emissions from a pair of new gray iron cupolas are to be controlled with a wet scrubber.
The cupolas are to operate alternately, so the emissions from only one need be treated. The
cupolas are conventional refractory lined units. Gas takeoffs are above the charge doors.
Products of combustion and charge door indraft are preheated to a temperature sufficient that
the gases leaving the cupola and entering the pollution control system will be 1,20CPF. Each
cupola is operated for 24 hours then shutdown for maintenance while the other cupola is
operating. The yearly operating factor for the pollution control system is 5,280 hr/yr.
The abatement system will consist of:
1. A quencher
2. A wet scrubber
An afterburner will be supplied by others. It will be located in the stack above the charge
door. The geometry of the installation will be arranged to insure sufficient turbulence for
complete combustion. Stack inserts to achieve turbulence may be used if necessary.
The quencher will be used to lower the temperature of the afterburner exhaust gas to the
inlet temperature of the wet scrubber. The quencher should be located immediately after the
gases leave the top of the cupola. The quencher should be designed to lower the gas
temperature from a maximum of 2,200°F to less than 200°F scrubber inlet temperature. The
cupola gas leaves the unit at a height of 50 feet above grade. The duct after the quencher must
transport the cooled gas to the scrubber inlet located 40 feet away from the quencher. The
quencher is 15 feet away from the cupola.
The wet scrubber will be a venturi-type with a liquid-to-gas ratio in excess of 5 gpm/1,000
ACFM (saturated). Materials of construction will be 316L stainless steel or equivalent. The
system will include the following:
1. A fan, located downstream of the scrubber sized with 20% excess capacity when
operating at the design pressure and 90% of the maximum recommended speed.
2. A slurry settling assembly capable of producing a thickened underflow (30% solids)
while returning water with minimum solids content.
3. A minimum of at least two filters to dewater the slurry product which are capable of
producing a filter cake with > 65% solids content suitable for open truck
transportation.
4. An aftercooler capable of lowering the scrubber effluent gas temperature to 105°F
by countercurrent contact with 90°F cooling water (Case II - High Efficiency only).
592
-------
TABLE 225
WET SCRUBBER OPERATING CONDITIONS
FOR GRAY IRON CUPOLA SPECIFICATION
Small
Large
Cupola Inside Diameter, in.
Cupola Melt Rate, ton/hr
Cupola Iron/Coke Ratio
Cupola Process Weight, Ib/hr
Afterburner Exhaust Gas
ACFM
Temperature, °F
SCFM
DSCFM
Water Content, vol%
Solids Loading
Ib/hr
gr/ACF
gr/DSCF
Quencher Outlet Gas
ACFM
Temperature, °F
Water Content, vol%
SCFM
DSCFM
Solids Loading
Ib/hr
gr/ACF
gr/DSCF
Solids Size Distribution
% > 10 microns
% < 10 microns
% < 5 microns
% < 1 micron
% < 0.7 micron
% < 0.3 micron
48
10
10
22,400
41,800
2,000
9,000
8,820
2
108
0.301
1.429
18,700
200
41
15,000
8,820
108
0.21
1.429
114
60
10
134,400
220,000
2,000
47,500
46,550
2
540
0.286
1.353
98,300
200
41
73,900
46,550
540
0.20
1.353
68
32
24
11
8
1
68
32
24
11
8
1
Scrubber Outlet Gas
ACFM
Temperature, °F
Water Content, vol
SCFM
DSCFM
Aftercooler Outlet Gas
ACFM
Temperature, °F
SCFM
Water Content, vol
DSCFM
18,100
171
42
15,200
8,820
J
10,300
105
9,660
8.7
8,820
95,500
171
42
80,200
46,550
54,400
105
51,000
8.7
46,550
593
-------
594
-------
Small . Large
Case I — Medium Efficiency
Solids Loading
Ib/hr 20.4 40
gr/ACF 0.16 0.06
gr/DSCF 0.27 0.10
Collection Efficiency, wt.% 81.1 92.6
Scrubber, A P 25 in. w.c. 25 in. w.c.
Case II — High Efficiency
Solids Loading
Ib/hr 0.9 4.7
gr/ACF 0.010 0.010
gr/DSCF 0.011 0.011
Collection Efficiency, wt.% 99.1 99.1
Scrubber, A P 60 in. w.c. 60 in. w.c.
595
-------
TABLE 226
ESTIMATED CAPITAL COST DATA (COSTS IN DOLLARS)
FOR WET SCRUBBERS FOR
GRAY IRON FOUNDRY CUPOLAS
Effluent Gas Flow
ACFM
°F
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
°F
DSCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant 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
Ductwork
Stack
Electrical
Piping
Insulation
Painting
Supervision
Startup
Performance Test
Other
\
/
(4) Total Cost
LA Process Wt.
Small
41,800
2,000
9,000
2
0.301
18,100 *
171
8,820
42-"
*
0.16
20.4
81.1
19,067
56,700
117,166
192,933
Large
220,000
2,000
47,500
2
0.286
95,500
17;
46,550
42
0.06
40.0
92.6
55,833
110,120
203,467
369,420
High Efficiency
Small
41,800
2,000
9,000
2
0.301
10,300-
105"
8,820'
'.
99. 1
22,567
71,833
131,333
225,733
Large
220,000
2,000
47,500
2
0.286
54,400
105
46,550
8.7
0.01
4.7
99.1
69,000
149,567
239,800
458,367
596
-------
TABLE 227
ANNUAL OPERATING COST DATA (COSTS IN $/YEAR)
FOR WET SCRUBBERS FOR
GRAY IRON FOUNDRY CUPOLAS
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
$6/hr
$.011/kw-hr
$.25/M gal
$.05/M gal
LA Process Wt.
Small
5,280
4,560
4,560
5,923
4,290
7,969
1,520
9,489
24,262
19,293
43,555
Large
5,280
4,560
4,560
10,248
9,300
63,629
9,738
73,367
97,475
36,942
134,417
High Efficiency
Small
5,280
4,560
4,560
6,898
5,415
17,389
2,080
6,490
25,959
42,832
22,573
65,405
Large
5,280
4,560
4,560
12,398
11,770
121,055
9,738
37,734
168,527
197,255
45,837
243,092
01
CO
-------
FIGURE 175
CAPITAL COSTS FOR WET SCRUBBERS
FOR GRAY IRON FOUNDRY CUPOLAS
(MEDIUM EFFICIENCY)
500000
o
Q
b
O
O
a.
<
o
100000
10000
1000
1
URNF
;EY
S\
ST
COLLECTOR PI
AUXILIARIE
C
DLL
EC
TO
Er
r
.us
SI -J
={
/
o
•e
4
M
f
1
/
f
L'
^
_^
^^^
^r^
s
/
Y
.^
s*
^
>
/
^
^
^t
/
&
&
J?
W *f
**
^
/
1000 10000 100000 300000
GAS FLOW, DSCFM
598
-------
FIGURE 176
ANNUAL COSTS FOR WET SCRUBBERS
FOR GRAY IRON FOUNDRY CUPOLAS
(MEDIUM EFFICIENCY)
500000
V)
tr
O
a
CO
O
u
100000
10000
1000
(
PLUS
TOT
OPER;
> CAP
c
AL
vnr
TAI
)PEF
COST
JG CQ
. CHA
*A-
•IN
S'
R
A
f
G
\,
f
/
GES)
/
C
^
O
y
S'
.s
s^
s
s
/
r
r
^x*^
^
/
s
/
s
f
ti
jo
/
/
1000 10000 100000 300000
GAS FLOW, DSCFM
599
-------
FIGURE 177
CAPITAL COSTS FOR WET SCRUBBERS
FOR GRAY IRON FOUNDRY CUPOLAS
(HIGH EFFICIENCY)
500000
100000
CO
DC
O
Q
8
_j
<
H
t£
O
10000
1000
TURN
KEY SYSTEM
COLLECTOR
PLUS AUXILIARIES
COLLECTOR ONLY
1000
10000
GAS FLOW, DSCFM
100000
300000
600
-------
FIGURE 178
ANNUAL COSTS FOR WET SCRUBBERS
FOR GRAY IRON FOUNDRY CUPOLAS
(HIGH EFFICIENCY)
500000
co
DC
o
Q
o
100000
10000
1000
(OP
PLUS C
FOTAL COST
ERATING CC
IAPITAL CHX
Ol
)S7
\R(
BE
^
S)
<**
0
JV
JEF
IA
T
l\
/
/
G
J* A
S /
s
S
/
COST
^
f
J
/
Hi
,>
/
1000 10000 100000 300000
GAS FLOW, DSCFM
601
-------
TABLE 228
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS FOR GRAY IRON FOUNDRY CUPOLAS
(HIGH EFFICIENCY)
Population Size — 20 Sample Size — 3
Capital Cost = $225,733
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $187,854 $263,613
75 152,339 299,128
90 97,689 353,777
Capital Cost = $458,367 '
Capital Cost, Dollars
Conf. Level, % Lower Limit Upper Limit
50 $348,419 $568,315
75 245,333 671,401
90 86,709 830,024
602
-------
FIGURE 179
CONFIDENCE LIMITS FOR CAPITAL COST
OF WET SCRUBBERS FOR GRAY IRON FOUNDRY CUPOLAS
(HIGH EFFICIENCY)
5,000,000
1,000,000
V)
tc
o
Q
te
o
o
Q.
<
O
100,000
10,000
1000
10000
GAS FLOW, DSCFM
100000
300000
603
-------
REFERENCES
1. Systems Analysis of Emissions and Emissions Control in the Iron Foundry
Industry, Vols. I, II, and III, A. T. Kearny and Co., Chicago, III., 1971.
EPA Contract No. CPA 22-69-106
2. A Localized Study of Gray Iron Foundries to Determine Business and
Technical Commonalities Conducive to Reducing Abatement Costs, J. A.
Commins & Associates, Inc., Fort Washington, Pa., 1972. EPA Contract
No. 68-04-0043
3. Air Pollution Engineering Manual, U.S. Dept. of Health, Education, and
Welfare, Public Health Services Publication No. 999-AP-40, Cincinnati,
Ohio, 1967.
4. Hultgren, Ralph, Fundamentals of Physical Metallurgy, Prentice Hall, Inc.,
New York, N.Y., 1952.
5. Iron Foundry Cupola-Recuperator Demonstration, Conceptual Test
Program Definition, Catalytic, Inc., Charlotte, N.C., 1972. EPA Contract
No. 68-02-0241.
6. Industry Census Guide, Metal Casting Journal, 1972 edition.
7. The Cupola and Its Operation, American Foundrymen's Society, 3rd
edition, 1965.
8. Whiting Corporation, Harvey, Illinois 60426.
604
-------
COST CORRELATIONS
-------
C. ADDITIONAL COST DATA
The previous section of this report dealt with the cost of air pollution
control systems for eight specific processing applications. This section deals
with the generalized correlation of costs for each type of control system for all
eight of the process applications discussed. The discussion is divided into four
parts:
1. A discussion of the annual operating cost basis, including both the
direct and capital charge portions of this cost.
2. A discussion of the effects of utility price levels on overall costs.
3. Derivation of capital cost indices for each specific process application.
4. Generalized graphical correlations of capital and operating costs for
each type of control system.
1. Discussion of Cost Basis
As noted in the introduction to this report, the total annual cost for a
particular control system is the sum of the direct annual operating cost and an
annualized capital charge.
In the previous section of this report the annual direct operating costs for
air pollution control systems in specific processing applications were calculated
using estimates supplied by the equipment manufacturers. These estimates were
prepared in terms of the quantity of each operating cost item required, rather
than the cost. A standard price was applied to these estimates by the coordinat-
ing engineer in order to determine the equivalent cost. The standard prices used
are listed below:
Cost Item Units Price, $/Unit
Operating Labor
Operator man hrs 6
Supervisor man hrs 8
Maintenance
Materials * *
Labor man hrs 6
Replacement Parts
Utilities
Electric Power kwh 0.011
Fuel mm Btu 0.80
Process Water M Gal 0.25
Cooling Water M Gal 0.05
Chemicals *
605
-------
The sum of all the above items applied over a year's operation is the direct
annual operating cost of the system.
The total annual cost of each system is calculated by adding the annual-
ized capital charges to the direct annual operating cost. In calculating the
annualized capital charges, the investment cost of the system, including taxes
and interest, must be spread out over the useful life of the equipment. Many
methods for annualizing investment cost are used. These methods fall into
three major categories:
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 auto-
mobiles.
Of the two methods applicable to processing equipment, the most
commonly used is the straight line method. This is the method 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 of the rate of
obsolescence of process equipment.
3. It makes alternate 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
606
-------
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
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 impor-
tant 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 pre-
sentations in this report.
2. Discussion of Utility Price Levels
Evaluation of, and selection among, equivalent control systems should be
based upon both the capital cost and the operating cost. Part 1 of this section
discussed the capital portion of the total annual operating cost and showed
that the direct operating cost is composed of the following items:
607
-------
Operating (operator and supervisor) Labor
Maintenance Labor and Materials
Replacement Parts
Utilities and Supplies
The utilities portion of the operating cost is a function of utility price
levels. Price levels vary due to:
1. Geography — The price of natural gas, for example, is much higher
in the New England states than in the Gulf Coast states.
2. Demand — The demand for low sulfur black fuel oil keeps its price
as much as 50 cents per barrel higher than the equivalent higher
sulfur fuel.
3. Nature of Use — The rates for interruptible gas service are lower than
those for continuous service, and rates for peak period use of
electrical service are as much as twice the rates for off-hour power
consumption.
The total operating cost is the sum of the direct operating cost and the
capital charges and is, therefore, a function of utility costs in varying degrees.
The price level effect on the operating cost is proportional to the portion of the
total cost which is due to utilities. These portions have been calculated for each
type of control equipment considered in this report, and the results are
presented in Table 229.
Table 229 shows that, on the average, utilities account for 44 to 73% of
the total annual cost of wet scrubbers, while they account for only 13 to 18%
of the total annual cost of electrostatic precipitators. Therefore, the price level
of electrical power would effect the total annual operating cost of a wet scrub-
ber more than a precipitator.
The effect of utility cost levels also varies within a given type of system.
Capital cost is a larger part of the total cost of a small unit than it is of a large
unit of the same type. Therefore, the utility costs are smaller relative to the
total annual operating cost, and have less effect on it. Also, the operating
parameters of a system affect the relative size of the utility costs. Scrubbers
using a high pressure drop, for example, require more power to push the gas
608
-------
TABLE 229
UTILITY COSTS
System
As Percent Of
Direct Operating Cost
As Percent Of
Total Annual Cost
Fabric Filters
Small
Large
Incinerators w/o H. E.
Small
Large
Incinerators with H. E.
Small
Large
Wet Scrubbers
Small
Large
Elec. Precipitators
Small
Large
Carbon Adsorption
Small
Large
Min.
18
34
53
76
33
39
24
28
26
36
—
—
Ave.
42
56
79
89
65
74
61
73
38
49
90
93
Max.
64
68
95
98
96
98
99.7
99.9
48
58
—
—
Min.
11
20
33
61
16
21
12
28
10
12
—
—
Ave.
23
32
59
77
47
57
44
73
13
18
66
72
Max.
41
48
84
92
83
88
99.1
99.9
17
22
—
—
Overall Average
66
48
609
-------
through, than do scrubbers having a low pressure drop. Therefore, utilities will
be a larger portion of the total cost of high energy scrubbers than of low
energy scrubbers.
Table 229 shows that for all the systems considered in this report the cost
of utilities accounts, on the average, for about two thirds of the direct cost of
operating a system, and for about one half of the total annual operating cost of
a system. The general level of operating costs is substantial, and requires that
price levels be considered when alternatives are being compared.
3. Derived Capital Cost Indices
For each of the process applications discussed in the previous sections of
this report, capital costs of pollution control equipment have been presented
for two or three different process sizes. This permits development of a mathe-
matical expression for the capital cost of air pollution control systems as a
function of process size in each application. The mathematical model chosen
was the exponential form often used for relating cost and size of capital
equipment.
Capital Cost = K (Size)x
Where
K and x are constants, and
Size is the capacity of the plant 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
each application. For most types of equipment, this is a good assumption.
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
610
-------
Calculations were made using the computer program listed in Dartmouth Basic
Language in Table 230.
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 231 .
The results of these calculations for generating capital costs in dollars, are
presented in the following tables:
Process Area Table Numbers
Phosphates
- WPPA 232
- SPA 233
- GTSP 234
- DAP 235, 236, 237, 238
Feed and Grain 239,240,241,242
Paint and Varnish 243, 244, 245, 246
Graphic Arts 247, 248, 249, 250, 251
Gray Iron Foundries 252, 253
Lime Kilns 254, 255, 256, 257, 258
Soap and Detergent 259, 260, 261
Also shown in 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.
Calculated values of the exponents for the power function can be
summarized by equipment type as follows:
(Text continued on page 644)
611
-------
TABLE 230
120 FILES «
122 PRINT "FORM CONTROL"
124 INPUT Z
130 READ #1,N$
140 READ #1,E$,C$
145 IF END ttl THEN 650
150 IF J=l GO TO 230
160 PRINT
170 PRINT
180 PRINT " DERIVED COST INDICES FOR ";N$
185 PRINT
187 PRINT
188 PRINT
190 PRINT
200 PRINT " COLLECTOR TYPE";" K"";" X"";
201 PRINT " B/A";" C/A";" C/B"
230 PRINT
240 FOR M = 1 TO 4
250 FOR N = I TO 2
260 READ #1, ACM,N)
270 NEXT N
280 NEXT M
290 FOR N = 1 TO 2
310 NEXT N
320 FOR M = 1 TO 3
330 XCM) = CLOGCACM,1))-LOGCACM,2)))/CLOGCAC4,1))-LOGCAC4,2)))
340 PCM) = CLOGCACM,1))+LOGCACM,2)))-XCM)"CLOGCAC4,1))+LOGCAC4,2)))
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 " ";E$
415 PRINT " ";C$
420 PRINT, 530, PCD, XC1)
430 PRINT,540,PC2),XC2)
440 PRINT,550,PCS),XC3)
450 PRINT
460 PRINT,560,RC1,1),RC2,1),RC3,D
470 PRINT,570,RC1,2),RC2,2),RC3,2)
480 PRINT
500 J = 1
510 GOTO 140
530 FMT X10,"COLLECTOR ONLYCA)",X6,I 7,X4,F6.3,X6,"-",X8,"-",X8,"-"
540 FMT X10,"TOTAL EQUIPMENTCB)",X5,I 7,X4,F6.3,X6,"-",X8,"-",X8,"-"
550 FMT X10,"TURNKEYCC)",X13,I7,X4,F6.3,X6,"-",X8,"-",X8,"-"
560 FMT X12,"SMALL",X20,"-",X9,"-",X6,F6.3,X2,F7.3,X2,F6.3
570 FMT X12,"LARGE",X20,"-",X9,"-",X6,F6.3,X2,F7.3,X2,F6.3
580 PRINT
590 PRINT
600 PRINT " "FOR USE IN EQUATION COST = K::CS IZE )"EXPCX)"
610 FOR N = 1 TO 30
620 PRINT
630 NEXT N
640 GO TO 700
650 FOR Y=l TO 12
660 PRINT
670 NEXT Y
680 GOTO 600
700 END
612
-------
TABLE 231
UNITS OF PLANT SIZE FOR EACH PROCESS AREA
Process Area Plant Size Units
Phosphates
- WPPA Ton/day P205
- SPA Ton/day Product
- GTSP Ton/day TSP
- DAP Ton/day DAP
Feed and Grain Lb/hr Product
Paint and Varnish Gals Total Reactor Capacity
Graphic Arts SCFM Exhaust Rate
Gray Iron Foundries Ton/hr Cupola Melt Rate
Lime Kilns Ton/day Kiln Capacity
Soap and Detergent Lb/hr Product Rate
613
-------
TABLE 232
DERIVED COST INDICES FOR WPPA PROCESS PLANTS
COLLECTOR TYPE
PACKED C-F SCRUBBERS
ONE-THIRD GAS FLOW
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
PACKED C-F SCRUBBERS
NORMAL GAS FLOW
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
1789
2390
11156
»
"
2186
4421
14195
_
x::
.248
.269
.200
_
.337
.287
.239
_
B/A
-
-
—
1.521
1.539
-
-
—
1.482
1.439
C/A
-
-
—
4.607
4.477
-
-
—
3.531
3.333
C/B
-
-
—
3.030
2.908
-
-
—
2.382
2.316
:FOR USE IN EQUATION COST = K::( SI ZE)-EXP(X)
614
-------
TABLE 233
DERIVED COST INDICES FOR SPA PROCESS PLANTS
COLLECTOR TYPE
W-I VENTURI SCRUBBERS
NOMINAL EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT OB)
TURNKEY(C)
SMALL
LARGE
VENTURI-PACKED SCRUBBE
NOMINAL EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
738
738
1460
_
*
1405
3011
6922
-
X"
.431
.431
.367
_
.299
.249
.249
-
B/A
_
1.000
1.000
_
1.662
1.605
C/A
_
1.439
1.377
_
3.823
3.692
C/B
_
1.439
1.377
_
2.300
2.300
:FOR USE IN EQUATION COST = K"(SIZE)-EXP(X)
615
-------
TABLE 234
DERIVED COST INDICES FOR GTSP PROCESS PLANTS
COLLECTOR TYPE
VENTURI-PACKED SCRUBBEF
MOD. EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
VENTURI-PACKED SCRUBBEI
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
322
438
1814
—
"
304
511
1943
—
X"
.760
.787
.703
»
.784
.775
.701
__
B/A
-
-
—
1.617
1.639
-
-
—
1.588
1.581
" C/A
-
-
—
3.951
3.847
-
-
—
3.813
3.667
C/B
-
-
—
2.443
2.348
-
-
—
2.401
2.319
:FOR USE IN EQUATION COST = K::CS I ZE)"EXP(X)
616
-------
TABLE 235
DERIVED COST INDICES FOR DAP PROCESS PLANTS
COLLECTOR TYPE
VENTURI SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT^)
TURNKEY(C)
SMALL
MEDIUM
VENTURI SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTS)
TURNKEY(C)
MEDIUM
LARGE
K"
316
179
2964
-
377
269
655
-
X"
.716
.870
.579
^
.690
.811
.798
-
B/A
-
1.542
1.641
_
1.641
1.737
C/A
_
3.848
3.641
_
3.641
3.829
C/B
-
2.495
2.218
_
2.218
2.204
:FOR USE IN EQUATION COST - K"(S I ZE)-EXP(X)
617
-------
TABLE 236
DERIVED COST INDICES FOR DAP PROCESS PLANTS
COLLECTOR TYPE
2-STAGE CYC. SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCB)
TURNKEY(C)
SMALL
MEDIUM
2-STAGE CYC. SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
MEDIUM
LARGE
K"
360
282
5399
—
—
480
424
995
«•
X"
.755
.832
.516
_
~
.714
.773
.761
_
B/A
-
-
-
1.287
1.328
-
-
-
1.328
1.365
C/A
-
-
-
3.163
2.870
-
-
—
2.870
2.934
C/B
-
-
—
2.457
2.162
-
-
—
2.162
2.150
:FOR .USE IN EQUATION COST = K"(SIZE)"EXPCX)
618
-------
TABLE 237
DERIVED COST INDICES FOR DAP PROCESS PLANTS
COLLECTOR TYPE
PACKED C-F SCRUBBERS
MED. EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
MEDIUM
PACKED C-F SCRUBBER
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEYCO
SMALL
MEDIUM
K"
295
256
1509
_
"
140
158
1151
_•
X"
.656
.735
.574
_
"
.789
.821
.623
_
B/A
-
-
-
1.452
1.499
_
_
-
1.404
1.423
C/A
-
_
-
3.000
. 2.901
—
—
• -
2.808
2.626
C/B
-
—
-
2.066
1.936
_
_
-
2.000
1.846
-FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
619
-------
TABLE 238
DERIVED COST INDICES FOR DAP PROCESS PLANTS
COLLECTOR TYPE
PACKED C-F SCRUBBER
MED. EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
MEDIUM
LARGE
PACKED C-F SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLYCA)
TOTAL EQUIPMENT(B)
TURNKEY(C)
MEDIUM
LARGE
K"
35
135
595
*~
133
325
957
-
X5:
.96?
.828
.709
-
.795
.717
.650
-
B/A
-
1.499
1.404
-
:
1.423
1.371
C/A
_
2.901
2.570
-
:
2.626
2.452
C/B
_
1.936
1.830
-
-
1.846
1.788
:FOR USE IN EQUATION COST = K::( SI ZE)"EXP(X)
620
-------
TABLE 239
DERIVED COST INDICES FOR FLOUR MILLING
COLLECTOR TYPE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCB)
TURNKEY(C)
SMALL
LARGE
K»
15
21
30
_
"
X"
.626
.628
.622
—
"
B/A
-
-
—
1.415
1.420
C/A
-
-
—
1.903
1.896
C/B
-
-
—
1.345
1.335
"FOR USE IN EQUATION COST - K"(SIZE)»EXP(X)
621
-------
TABLE 240
DERIVED COST INDICES FOR FEED GRINDING
COLLECTOR TYPE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K«
1395
1761
3553
_
^
X"
.734
.713
.692
_
"
B/A
-
-
—
1.215
1.180
C/A
(
-
-
—
2.361
2.227
C/B
-
-
—
1.9^3
1.887
-FOR USE IN EQUATION COST = K"(SIZE)-EXP(X)
622
-------
TABLE 241
DERIVED COST INDICES FOR FEED FLASH DRYERS
COLLECTOR TYPE
THERMAL INCINERATOR
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCB)
TURNKEY(C)
SMALL
LARGE
K"
18?
176
279
_
"
x»
.648
.662
.635
«-
"
B/A
-
-
-
1.065
1.09^
C/A
-
-
—
1.336
1.304
C/B
-
-
—
1.255
1.192
"FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
623
-------
TABLE 242
DERIVED COST INDICES FOR FEED FLASH DRYERS
COLLECTOR TYPE
WET SCRUBBER
MED. EFFICIENCY
COLLECTOR ONLYCA)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
WET SCRUBBER
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K::
44
77
570
._
MB
41
72 .
538
—
xj:
.611
.577
.443
_
™
.622
.587
.451
_
B/A
-
-
-
1.293
1.210
-
-
-
1.282
1.198
C/A
-
-
—
2.915
2.105
-
-
-
2.845
2.042
C/B
-
-
—
2.255
1.740
-
-
—
2.220
1.705
-FOR .USE IN EQUATION COST = K:c(SI ZE)"EXP(X)
624
-------
TABLE 243
DERIVED COST INDICES FOR OPEN KETTLES
COLLECTOR TYPE
INCINERATORS W/0 H.E.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
6473
6481
12443
*
*•
x::
.118
.142
.120
_
^
B/A
-
-
—
• 1.136
1.184
C/A
-
-
—
1.941
1.948
C/B
-
-
—
1.709
1.645
:FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
625
-------
TABLE 244
DERIVED COST INDICES FOR OPEN KETTLES
COLLECTOR TYPE
CAT. INCRS. W/0 H.E.
HIGH EFFICIENCY
COLLECTOR ONLYCA)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
1619
1978
4805
_
—
X"
.378
.372
.297
_
—
B/A
-
-
—
1.185
1.174
C/A
-
-
—
1.937
1.686
C/B
-
-
—
1.634
1.436
-FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
626
-------
TABLE 245
DERIVED COST INDICES FOR RESIN REACTOR
COLLECTOR TYPE
INCINERATORS W/0 H.E.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTS)
TURNKEY(C)
SMALL
LARGE
INCRS. WITH H.E.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTS)
TURNKEY(C)
SMALL
LARGE
K::
336
322
972
..
~
1692
1552
2432
_
X:c
.457
.482
.408
_
~*
' .345
.367
.351
_
B/A
-
-
-
1.184
1.224
-
-
—
1.100
1.132
C/A
-
-
-
1.932
1.811
-
-
—
1.508
1.520
C/B
-
-
—
1.632
1.480
-
-
—
1.371
1.342
:FOR -USE IN EQUATION COST = K::( SI ZE)"EXP(X)
627
-------
TABLE 246
DERIVED COST INDICES FOR RESIN REACTORS
COLLECTOR TYPE
CAT. INCRS. W/0 H.E.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
CAT. INCRS. WITH H.E.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
435
451
889
_
—
1134
1023
1725
—
X"
.478
.493
.454
_
••
.402
.430
.401
_
B/A
-
-
—
1.174
1.197
-
-
—
1.145
1.190
C/A
-
-
—
1.669
1.616
-
-
—
1.510
1.508
C/B
-
-
—
1.422
1.350
-
-
—
1.318
1.268
= FOR -USE IN EQUATION COST = K::(S I ZE)"EXP(X)
628
-------
TABLE 247
DERIVED COST INDICES FOR WEB-OFFSET PRINTING
COLLECTOR TYPE
INCINERATORS W/0 H.E.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT^!)
TURNKEY(C)
SMALL
LARGE
CAT. INCRS. W/0 H.E.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTS)
TURNKEY(C)
SMALL
LARGE
K"
3153
2751
6347
_
—
354
373
1137
_
X"
.214
.247
.205
_
—
' .516
.522
.427
_
B/A
-
-
—
1.116
1.163
-
-
—
1.100
1.108
C/A
-
-
—
1.871
1.848
-
-
—
1.628
1.456
C/B
-
-
—
1.676
1.590
-
-
—
1.480
1.314
{FOR "USE IN EQUATION COST = K"(S IZE )"EXP(X)
629
-------
TABLE 248
DERIVED COST INDICES FOR METAL DECORATING
COLLECTOR TYPE
INCINERATOR W/0 H.E.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEYCC)
SMALL
LARGE
INCRS. WITH H.E.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
173
191
1071
_
~
5465
3713
6488
_
X"
.551
.555'
.426
_
•••
.215
.271
.258
_
B/A
-
-
—
1.139
1.144
-
-
-
1.086
1.144
C/A
-
-
—
2.186
1.949
-
-
-
1.690
1.757
C/B
-
-
—
1.918
1.704
-
-
—
1.556
1.537
:FOR .USE IN EQUATION COST = K"(SIZE)"EXP(X)
630
-------
TABLE 249
DERIVED COST INDICES FOR METAL DECORATING
COLLECTOR TYPE
CAT. INCRS. W/0 H.E.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
CAT. INCRS. WITH H.E.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTS)
TURNKEYCC)
SMALL
LARGE
K»
302
259
542
_
~
695
570
1012
_
X"
.537
.566
.515 ,
«
"
.476
.510
.473
_
B/A
-
-
' -
1.087
1.116
-
-
-
1.084
1.119
C/A
-
-
-
1.493
1.463
• -
-
-
1.414
1.409
C/B
-
-
-
1.374
1.3H
-
-
-
1.304
1.260
-FOR -USE IN EQUATION COST = K"(S I ZE)-EXP(X)
631
-------
TABLE 250
DERIVED COST INDICES FOR GRAVURE PRINTING
COLLECTOR TYPE
INCRS. WITH H.E.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
164
114
324
_
—
X"
.604
.653
.579
_
"
'
B/A
,
-
-
-
1.108
• 1.146
C/A
-
• - •
-
1.560 '
1.533
C/B
-
-
—
1.408
1.337
"FOR USE IN EQUATION COST = K"(SIZE)"EXPCX)
632
-------
TABLE 251
DERIVED COST INDICES FOR GRAVURE PRINTING
COLLECTOR TYPE
CARBON ADSORPTION
HIGH EFFICIENCY
COLLECTOR ONLYCA)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
73398
77154
159821
_
—
x::
.776
.772
.701
—
•
B/A
-
-
—
1.046
1.042
C/A
-
-
—
1.964
1.810
C/B
-
—
1.878
1.738
"FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
633
-------
TABLE 252
DERIVED COST INDICES FOR GRAY IRON CUPOLAS
COLLECTOR TYPE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
4860
"9865
25195
_
—
X"
.738
.762
.706
—
™
B/A
-
-
—
2.142
2.233
C/A
-
-
—
4.808
4.535
C/B
-
-
—
2.245
2.031
"FOR USE IN EQUATION COST = K"CSIZE)-EXP(X)
634
-------
TABLE 253
DERIVED COST INDICES FOR GRAY IRON CUPOLAS
COLLECTOR TYPE
WET SCRUBBERS
LA PROCESS WT.
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"
4793
27663
83726
_
~
5367
32093
90839
_
X"
.600
.438
.363
_
—
.624
.469
.395
_
B/A
-
-
-
3.974
2.972
-
-
-
4.183
3.168
C/A
—
-
-
10.119
6.617
-
-
-
10.003
6.643
C/B
_
-
- .
2.546
2.226
—
—
—
2.391
2.097
:FOR USE IN EQUATION COST = K"(SIZE)-EXP(X)
635
-------
TABLE 254
DERIVED COST INDICES FOR ROTARY LIME SLUDGE KILNS
COLLECTOR TYPE
ELCSTC. PRCPTRS.
LA PROCESS WT.
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCEO
TURNKEY(C)
SMALL
LARGE
ELCSTC. PRCPTRS.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEYCO
SMALL
LARGE
K::
146
278
332
_
—
225
484
781
_
X"
.593
.562
.593
—
—
.568
.525
.529
_
B/A
-
-
—
1.386
1.336
-
-
—
1.372
1.303
C/A
-
—
2.283
2.284
-
-
—
2.305
2.198
C/B
-
-
—
1.647
1.709
-
-
—
1.679
1.687
:FOR XISE IN EQUATION COST = K::(S I ZE)-EXP(X)
636
-------
TABLE 255
DERIVED COST INDICES FOR ROTARY LIME SLUDGE KILNS
COLLECTOR TYPE
WET SCRUBBERS
LA PROCESS WT.
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::
31
17
326
-
51
26
402
-
X"
.601
.715
.524
-
' .570
.697
.522
-
B/A
_
-
1.780
2.044
-
1.915
2.231
C/A
_
-
4.695
4.280
-
4.765
4.494
C/B
-
2.637
2.094
_
2.488
2.014
"FOR USE IN EQUATION COST = K"(SIZE)"EXP(X)
637
-------
TABLE 256
DERIVED COST INDICES FOR VERTICAL LIME ROCK KILNS
COLLECTOR TYPE
ELCSTC. PRCPTRS.
LA PROCESS WT.
COLLECTOR ONLY(A)
TOTAL EQUIPMENTS)
TURNKEY(C)
SMALL
LARGE
ELCSTC. PRCPTRS.
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT^)
TURNKEY(C)
SMALL
LARGE
K»
401
311
339
_
—
315
352
742
_
X"
.-450
.508
.5^3
_
—
.496
.515
.492
—
B/A
-
-
-
1.450
1.509
-
-
-
1.381
1.400
C/A
-
-
—
2.306
2.459
-
-
-
2.268
2.262
C/B
_—
-
-
1.591
1.629
-
-
-
1.642
1.616
:FOR USE IN EQUATION COST = K"(S I ZE )::EXP(X)
638
-------
TABLE 257
DERIVED COST INDICES FOR VERTICAL LIME ROCK KILNS
COLLECTOR TYPE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENTCB;
TURNKEY(C)
SMALL
LARGE
K"
19
68
238
_
—
x:c
.770
.665
.592
_
—
B/A
-
-
-
1.340
1.179
C/A
-
-
—
2.297
1.846
C/B
-
-
—
1.713
1.566
"FOR USE IN EQUATION COST = K"( S I ZE)::EXP(X)
639
-------
TABLE 258
DERIVED COST INDICES FOR VERTICAL LIME ROCK KILN
COLLECTOR TYPE
WET SCRUBBERS
LA PROCESS WT.
COLLECTOR ONLY(A)
TOTAL EQUIPMENTS)
TURNKEY(C)
SMALL
LARGE
WET SCRUBBERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
34
42
476
_
—
34
101
800
—
x»
.551
.579
.443
—
—
.550
.508
.403
_
B/A
-
-
-
1.658
1.717
-
-
—
1.963
1.864
C/A
' -
-
-
5.056
4.435
-
-
—
5.647
4.716
C/B
-
-
—
3.050
2.583
-
-
—
2.877
2.529
:FOR USE IN EQUATION COST = K"(SIZE)"EXPCX)
640
-------
TABLE 259
DERIVED COST INDICES FOR DETERGENT SPRAY DRYING
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)
TURNKEYCC)
SMALL
LARGE
K"
50
71
485
_
—
89
126
691
.
X"
.641
.646
.532 ,
_
—
.581
.605
.519
_
B/A
-
-
—
1.482
1.492
-
-
—
1.796
1.856
C/A
-
-
—
3.318
2.854
-
-
—
4.190
3.843
C/B
-
-
—
2.238
1.913
-
-
—
2.334
2.070
:FOR USE IN EQUATION COST = K::(S I ZE)::EXP(X)
641
-------
TABLE 260
DERIVED COST INDICES FOR DETERGENT SPRAY DRYING
COLLECTOR TYPE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K::
2
5
10
__
—
X-
.985
.928
.915
__
~
B/A
-
-
—
1.328
1.226
C/A
—
-
—
2.469
2.242
C/B
-
-
—
1.860
1.828
"FOR USE IN EQUATION COST = K"CSIZE)"EXPCX)
642
-------
TABLE 261
DERIVED COST INDICES FOR SOAP & DET. PROD. HANDLING
COLLECTOR TYPE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY(A)
TOTAL EQUIPMENT(B)
TURNKEY(C)
SMALL
LARGE
K"
1
3
6
—
—
x::
.999
.942
.926
_
—
B/A
-
-
—
1.350
1.246
C/A
-
-
—
2.516
2.272
C/B
-
-
—
1.864
1.824
::FOR USE IN EQUATION COST = K::(S I ZE)"EXP(X)
643
-------
Maximum Minimum Arithmetic
Equipment Type Value Value Average
Fabric Filters
Collector Only .999 .626 .816
Turnkey System .915 .622 .772
Carbon Adsorption
Collector Only - - .776
Turnkey System — — .701
Wet Scrubbers
Collector Only .795 .248 .626
Turnkey System .798 .200 .514
Electrostatic Precipitators
Collector Only .593 , .450 .527
Turnkey System .598 .492 .539
Incinerators
Collector Only .648 .118 .402
Turnkey System .635 .120 .396
Of the five types of equipment involved, fabric filters had the highest
exponent. This was to be expected since fabric filtering equipment tends to be
additive. That is, to increase the capacity of a fabric filter system one can many
times add another unit. This becomes more practicable with larger air flows.
Many of the fabric filter systems were under 25,000 ACFM. Had more been in
the 50,000-and-up range, the cost-to-size relationship would have been even
closer to linear.
The exponent for incinerators had values from .120 in the 500 ACFM
range to .635 in the 100,000 ACFM range. The average was 0.4 — the lowest
for all the types of control systems considered in this report. This was below
the 0.6 exponent usually assumed, because a number of the incinerators were
of relatively small size. Every incinerator, regardless of size, requires an
extensive system of safety control devices to prevent explosions. This system is
a significant part of the cost of incinerators. So in the small size range the cost
of increasing size is relatively small.
The average exponent derived for carbon adsorption collectors was .776.
The limited amount of data on these systems precludes drawing many
644
-------
conclusions, but the cost data presented in this report could be safely
extrapolatable down to one gravure press, or 12,450 ACFM.
Wet scrubbers had an average exponent of .626 — somewhat higher than
the 0.6 usually assumed for equipment. A number of the scrubbers had an inlet
gas flow rate above 100,000 ACFM. In this range the basic design of scrubbers
must be changed to handle the high volumes of gas, and the cost starts
increasing more rapidly with size.
Exponents for electrostatic precipitators varied from .450 to .593, with
an average value of .527. In only one application was the gas flow above
100,000 ACFM. Precipitator flow rates from 300,000 to 600,000 ACFM are
not unusual. A major capital expense of precipitators is the power supply that
is required. This costs nearly as much for small precipitators as for large ones.
Therefore, the cost of small precipitators does not increase as rapidly with size
as would be expected in larger designs.
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
equipment installations tend to have relatively high capital costs which do not
correlate well with size. Small systems cost roughly the same regardless 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.
Consequently, the derived cost indices 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 very large
Precipitators 50,000 very large
Incinerators 2,000 50,000
The basic capital cost data collected were also used to calculate the cost
per SCFM of inlet gas for each application. Results of these calculations are
presented in the following tables:
645
-------
Process Area Table Numbers
Phosphates
- WPPA 262
- SPA 263
- GTSP 264
- DAP 265, 266, 267, 268
Feed and Grain 269,270,271,272
Paint and Varnish 273, 274, 275, 276
Graphic Arts 277, 278, 279, 280, 281
Gray Iron Foundries 282, 283
Lime Kilns 284, 285, 286, 287, 288
Soap and Detergent 289, 290, 291
646
-------
TABLE 262
DERIVED COST PER SCFM" FOR WPPA PROCESS PLANTS
COLLECTOR TYPE
SMALL
LARGE
PACKED C-F SCRUBBERS
ONE-THIRD GAS FLOW
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
. TURNKEY SYSTEM
8332
1.00
1.53
4.63
.81
1.25
3.63
WET SCRUBBERS
NORMAL GAS FLOW
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
8332
2.12
3.15
7.50
11954
1.80
2.60
6.02
:BASED ON SCFM AT 70- DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
647
-------
TABLE 263
DERIVED COST PER SCFM" FOR SPA PROCESS PLANTS
COLLECTOR TYPE
VENTURI SCRUBBERS
NOMINAL EFFICIENCY
GAS FLOW, SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
VENTURI-PACKED SCRUBBER '
NOMINAL EFFICIENCY
GAS FLOW, SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
SMALL
1252
5.10
5.10
7.33
1252
5.02
8.35
19.21 '
LARGE
2506
3.43
•• 3.43
4.73
2506
3.09
4.96
11.41
-BASED ON SCFM AT 70.DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
648
-------
TABLE 264
DERIVED COST PER SCFM" FOR GTSP PROCESS PLANTS
COLLECTOR TYPE
VENTUR I -PACKED SCRUBBER
MOD. EFFICIENCY
GAS FLOW, SCFM .
COLLECTOR ONLY
TOTAL EQUIPMENT
. TURNKEY SYSTEM
VENTURI-PAC.KED SCRUBBER '
HIGH EFFICIENCY
GAS FLOW, SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
SMALL
33870
1.09
1.76
4.31
33870
1.20
1.91
4.58
LARGE
54077
.90
1.60
3.76
54077
1.09
1.72
3.99
'BASED ON SCFM AT 70-DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
649
-------
TABLE 265
DERIVED COST PER SCFM FOR DAP PROCESS PLANTS
COLLECTOR TYPE
VENTURI SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
(SMALL)
30641
1.09
1.67
4.18
(MEDIUM)
46127
.96
1.58
3.51
VENTURI SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
(MEDIUM)
46127
. .96
1.58
3.51
(LARGE)
73703
.83
1.45
3.19
"BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
650
-------
TABLE 266
DERIVED COST PER SCFM FOR DAP PROCESS PLANTS
COLLECTOR TYPE
CYCLONIC SCRUBBERS
LA PROCESS WT.
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
(SMALL)
30641
1.60
2.05
5.05
(MEDIUM)
46127
1.44
1.91
4.13
CYCLONIC SCRUBBERS
LA PROCESS WT.
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
(MEDIUM)
46127
1.44
1,91
4.13
(LARGE)
73703
1.26
1.72
3.70
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
651
-------
TABLE 267
DERIVED COST PER SCFM FOR DAP PROCESS PLANTS
COLLECTOR TYPE
SMALL
MEDIUM
PACKED C-F SCRUBBERS
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
3022?
.70
1.01
2.09
44305
.62
.93
1.80
PACKED C-F SCRUBBER
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
30227
. .78
1.09
2.19
44305
.73
1.04
1.92
::BASED ON SCFM AT 70 DEG.. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
652
-------
TABLE 268
DERIVED COST PER SCFM FOR DAP PROCESS PLANTS
COLLECTOR TYPE
MEDIUM
LARGE
PACKED C-F SCRUBBER
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
44305
.62
.93
1.80
70805
.61
.86
1.57
PACKED C-F SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
44305
.73
1.04
1.92
70805
.66
.91
1.63
-BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
653
-------
TABLE 269
DERIVED COST PER SCFM FOR FLOUR MILLING
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
6000
.92
1.31
1.76
20000
.59
.83
1.12
"BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
654
-------
TABLE 270
DERIVED COST PER SCFM FOR FEED GRINDING
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
1.17
1.H2
2.76
17982
.80
• 9V
1.78
-BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
655
-------
TABLE 271
DERIVED COST PER SCFM FOR FEED FLASH DRYERS
COLLECTOR TYPE
SMALL
LARGE
THERMAL INCINERATOR
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY 'SYSTEM
8*113
7.12
7.58
9.51
58889
3.58
3.91
4.67
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
656
-------
TABLE 272
DERIVED COST PER SCFM FOR FEED FLASH DRYERS
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBER
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
8413
1.20
1.55
3.50
58889
.56
.68
1.18
WET SCRUBBER
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY 'SYSTEM
8413
1.25
1.60
3.54
58889
.60
.71
1.22
:BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
657
-------
TABLE 273
DERIVED COST PER SCFM FOR OPEN KETTLES
COLLECTOR TYPE
SMALL
LARGE
INCINERATORS W/0 H.E,
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
500
24.18
27.47
46.95
2999
4.94
5.84
9.61
-BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
658
-------
TABLE 274
DERIVED COST PER SCFM FOR OPEN KETTLES
COLLECTOR TYPE
SMALL
LARGE
CAT. INCRS. W/0 H.E.
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
500
23.97
28.41
2999
7.66
8.99
12.92
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
659
-------
TABLE 275
DERIVED COST PER SCFM FOR RESIN REACTORS
COLLECTOR TYPE
SMALL
LARGE
INCINERATORS W/0 H.E,
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
2999
4.94
5.84
9.54
9996
2.71
3.31
4.90
INCRS. WITH H.E.
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
2999
9.90
10.88
14.92
9996
4.69
5.31
7.12
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
660
-------
TABLE 276
DERIVED COST PER SCFM FOR RESIN REACTORS
COLLECTOR TYPE
SMALL
LARGE
CAT. INCRS. W/0 H.E.
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
2999
•7.67
9.00
12.79
9996
4.33
5.18
6.99
CAT. INCRS. WITH H.E.
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
2999
10.57
12.11
15.96
9996
5.39
6.41
8.13
:BASED ON SCFM AT 70 DEC, F AT COLLECTOR
INLET INCLUDING WATER VAPOR
661
-------
TABLE 277
DERIVED COST PER SCFM FOR WEB-OFFSET PRINTING
COLLECTOR TYPE
SMALL
LARGE
INCINERATORS W/0 H.E,
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
2002
8.03
8.96
15.02
7001
3.00
3.^9
5-55
CAT. INCRS. W/0 H.E.
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
2002
8.97
9.86
14.60
7001
4.90
5.43
7.13
"BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
662
-------
TABLE 278
DERIVED COST PER SCFM FOR METAL DECORATING
COLLECTOR TYPE
SMALL
LARGE
INCINERATOR W/0 H.E.
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
3991
4.20
4.79
9.19
9978
2.79
3.19
5.43
INCRS. WITH H.E.
HIGH EFFICIENCY
GAS FLOW, SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
3991
8.14
8.84
13.76
9978
3-97
4.54
6.97
:BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
663
-------
TABLE 279
DERIVED COST PER SCFM FOR METAL DECORATING
COLLECTOR TYPE
SMALL
LARGE
CAT. INCRS. W/0 H.E.
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
3991
6.52
7.09
9.73
9978
4.27
4.76
6.24
CAT. INCRS. WITH H.E.
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
3991
9.06
9.82
12.81
9978
5.61
6.27
7.90
•"BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
664
-------
TABLE 280
DERIVED COST PER. SCFM FOR GRAVURE PRINTING
COLLECTOR TYPE
SMALL
LARGE
INCRS. WITH H.E.
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
12045
3.95
4.38
6.16
24091
3.00
3.44
4.60
"BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
665
-------
TABLE 281
DERIVED COST PER SCFM FOR GRAVURE PRINTING
COLLECTOR TYPE
SMALL
LARGE
CARBON ADSORPTION
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
47989
4.48
4.69
8.81
143967
3.50
3.65
6.34
"BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
666
-------
TABLE 282
DERIVED COST PER SCFM FOR GRAY IRON CUPOLAS
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
8998
2.96
6.33
14.22
^7515
2.10
4.69
9.53
"BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
667
-------
TABLE 283
DERIVED COST PER SCFM FOR GRAY IRON CUPOLAS
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBERS
LA PROCESS WT.
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
9006
2.12
8.41
21.42
47398
1.18
3.50
7.79
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
9006
2.51
10.48
25.07
47398
1.46
4.61
9.67
-BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
668
-------
TABLE 284
DERIVED COST PER SCFM FOR VERTICAL LIME ROCK KILNS
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBERS
LA PROCESS WT.
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
5264
1.27
2.11
6.43
18388
.71
1.23
3-17
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
5264
1.29
2.54
7.31
18388
.73
1.35
3.^3
:BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
669
-------
TABLE 285
DERIVED COST PER SCFM FOR VERTICAL LIME ROCK KILNS
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
5264
5.81
7.78
13.3^
18388
4.27
5.03
7.88
"BASED ON
INLET
SCFM AT 70 DEG.
INCLUDING WATER
F AT COLLECTOR
VAPOR
670
-------
TABLE 286
DERIVED COST PER SCFM FOR VERTICAL LIME ROCK KILNS
COLLECTOR TYPE
SMALL
LARGE
ELCSTC. PRCPTRS.
LA PROCESS WT.
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
18388
2.87
4.16
6.61
36703
1.96
2.96
4.82
ELCSTC. PRCPTRS.
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
18388
3.68
5.09
8.36
36703
2.60
3.64
5.89
:BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
671
-------
TABLE 287
DERIVED COST PER SCFM FOR ROTARY LIME SLUDGE KILNS
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBERS
LA PROCESS WT.
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY 'SYSTEM
22247
.70
1.25
3.30
78518
.41
.84
1.76
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
22247
.84
1.60
3.99
78518
.47
1.05
2.12
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
672
-------
TABLE 288
DERIVED COST PER SCFM FOR ROTARY LIME SLUDGE KILNS
COLLECTOR TYPE
SMALL
LARGE
ELCSTC. PRCPTRS.
LA PROCESS WT.
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
22247
3.02
4.19
6.90
78518
1.75
2.34
4.00
ELCSTC. PRCPTRS.
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
22247
3.60
4.95
8.31
785lb
2.02
2.64
4.45
'BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
673
-------
TABLE 289
DERIVED COST PER SCFM FOR DETERGENT SPRAY DRYING
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBERS
MED. EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
23961
1.19
1.76
3.95
95835
.72
1.08
2.06
WET SCRUBBERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
23961
1.17
2.10
4.90
95835
.65
1.21
2.51
"BASED ON SCFM AT 70 DEG. F AT COLLECTOR
INLET INCLUDING WATER VAPOR ,
674
-------
TABLE 290
DERIVED COST PER SCFM FOR DETERGENT SPRAY DRYING
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
23961
1.47
1.95
3.64
95835
1.44
1.77
3.23
"BASED ON
INLET
SCFM AT 70 DEC.
INCLUDING WATER
F AT COLLECTOR
VAPOR
675
-------
TABLE 291
DERIVED COST PER SCFM FOR SOAP g DET. PROD. HANDLING
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
GAS FLOW,SCFM
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
18929
1.31
1.77
3.29
75714
1.31
1.63
2.97
-BASED ON SCFM AT 70 DEC. F AT COLLECTOR
INLET INCLUDING WATER VAPOR
676
-------
4. GENERALIZED COST DATA
A series of correlations were made to investigate the general relationship
of the cost of equipment to the gas flow rate for the types of control systems
discussed in this report. These correlations were made using the data presented
in the previous section of this report. The points plotted on each graphical
correlation are coded so that the process application which they represent can
be identified. The same point symbol code was used in all of the graphs and it
is fully explained in Table 292.
Scrubbers
Correlations were made for both the scrubber cost and for the total
installed cost of the scrubber system. Figure 180 shows the cost of the
scrubber alone. Although there is a wide scatter in the data, the results
correlate fairly well when the complexity of the scrubber is considered. Those
scrubbers that fall along the "High Complexity" line are units employing a
combination of scrubbing methods, such as venturi scrubbers with a packed
section, to remove gaseous contaminants in a highly corrosive environment.
Those falling along the "Low Complexity" line are mostly for removing
particulates in a relatively non-corrosive environment. Many of the scrubbers
in the "Medium" area were of the packed cross-flow type.
Figure 181 shows the cost for installed scrubbing systems. The wide
variability in the applications of the scrubbing systems has caused a very wide
scatter in the data. The only generalizations that can be made are that those
scrubbers having a high complexity and using high energy would fall along the
top edge of the plot area. Those of low complexity and using low energy would
fall along the bottom. Scrubbers having a pressure drop of 30 or more inches of
water have been defined here as being of high energy. Scrubbers defined here
as being of low energy have a pressure drop of 8 inches of water or less. The
intermediate area contains systems of high energy and low complexity, or high
complexity but low energy.
In both Figure 180 and Figure 181 the bottom part of the curves are
fairly straight, because the basis of the scrubber and the system remains
essentially the same from very small scrubbers to moderately large ones; and
therefore, a good cost-to-size relationship exists. But over 50,000 ACFM the
basic design must be changed to handle the increasing gas flows; and the cost
starts increasing more rapidly with size, causing the lines to curve upward.
677
-------
TABLE 292
PLOTTING SYMBOL KEY
Process Area Symbol
Phosphates
- WPPA n
-SPA O
- GTSP X
-DAP O
Feed and Grain A
Paint and Varnish Q
Graphic Arts Q
Soap and Detergent t^
Lime Kilns 0
Gray Iron Foundries Q
678
-------
APPENDIX
-------
5 67891
4 567891
(PARAMETERS REPRESENT
DEGREE OF COMPLEXITY)
hTTfrd ±rr±
FIGURE 180 '
CAPITAL COST OF
WET SCRUBBERS ONLY
:j±r
INLET GAS FLOW RATE, ACFM
i ! i i • ; i i i i 11 i I: i i' r i" I;
10
-------
5 67891
67891
5 67891
HIGH ENERGY
AND
HIGH COMPLEXITY
LOW ENERGY
AND
LOW COMPLEXITY
FIGURE 181
TOTAL INSTALLED COST
OF SCRUBBING SYSTEMS
INLET GAS FLOW RATE, ACFM
i i i i 111111111 n
5 6789
10'
103
-------
The operating cost of scrubbers are shown in Figure 182. The results
correlate well with the pressure drop across the system. The top line is for
scrubbers with a pressure drop of 30 inches of water or greater, the middle for
10 to 16 inches, and the bottom for eight inches of water or less. At the top
end of the top curve nearly all the operating costs are from the power for
pushing the large volumes of gas through the scrubber, and the increase in
operating cost is nearly linear with increasing gas flow rate. Each line starts
curving up near its bottom end as the more fixed operating costs, such as
operating and maintenance labor, become a more significant part of the total
which, therefore, increases less rapidly with size.
Fabric Filters
Similar correlations were made for fabric filters. However, as Figure 183
illustrates, due to the wide variability in the applications involved, no true
correlation exists between the different application on a gas flow rate basis.
This is caused by the fact that the characteristics of the different particulates
being collected require a different air-to-cloth ratio for each application. When
the actual flow rate is divided by the air-to-cloth ratio, the result is the area, in
square feet, of the fabric used. This area determines the physical size of the
unit. As Figure 184 shows, when plotted against the fabric area, both the cost
of the filter only and the installed system cost can be well represented by
straight lines.
Figure 185 shows that when operating costs are plotted against the fabric
area the results can be well represented by one line. As the size increases, the
relationship between size and cost becomes nearly linear. This can be expected;
for as the size increases, the cost of labor and material for replacing the bags
become the major part of the operating cost. And these bag replacement
costs are directly proportional to the size of the unit.
Incinerators
Basically, four types of incinerators were discussed in the previous section
of this report. They are thermal incinerators with and without heat exchangers,
and catalytic incinerators with and without heat exchangers.
Figure 186 shows the capital cost of incinerators without heat exchangers.
In this, as well as in subsequent plots of capital costs, the curves are concave
upward. Near the lower end of the curve, the cost does not increase with size
(Text continued on page 686)
681
-------
10
9
8
7
6
5
10
9
8
1.0
0.1
FIGURE 182 -f-
DlRECT OPERATING COST OF
WET SCRUBBERS =g
6 7 8 9 10
682
-------
891.
GRAY IRON
CUPOLAS
SOAP & DETERGENT
FIGURE 183
INSTALLED COST OF
Et=FABRIC FILTER SYSTEMS
LIME KILNS
FEED &
GRAIN
RATE, ACFM
I I I I I I I I I I I I 1111 11 III
INLET GAS FLOW
56789
-------
j.M.I ' „! i_i. 1 _t J,'
FIGURE 184
CAPITAL COST OF
FABRIC FILTERS
ri±L INSTALLED
FILTER
ONLY
FILTER ONLY
INSTALLED SYSTEM
FABRIC AREA, Ft2 (ACFM + A/C RATIO)
10*
2 3 4 66789 10
684
-------
5 67891.
FIGURE 185
DIRECT OPERATING COST OF
FABRIC FILTER SYSTEMS
FABRIC AREA, Ft* (ACFM -^ A/C RATIO)
5678 9in4
5 6789
-------
nearly as rapidly as it does toward the curve's upper end. This is due mainly to
the extensive system of safety and control devices that every incinerator
requires, regardless of size. This system is a significant part of the cost of
incinerators and keeps the cost of increasing size relatively small in the small
size range.
Figures 186 and 187 show that, as expected, the installed system cost as
well as the incinerator cost for catalytic units are greater than for the same size
thermal units.
However, when heat exchangers are added, this relationship is not
apparent. Figures 188 and 189 show that catalytic units with heat exchange
may tend to be slightly more expensive than a similar thermal unit; but there
is not enough data to show a definite separation, and one curve can represent
both types of units.
The savings in operating cost realized by heat recovery are illustrated in
Figures 190 and 191. In each case, the cost of operating without heat recovery
is two to three times that of operating with heat recovery. But it is apparent
that the lines converge as the flow rate decreases, and that at some point heat
recovery will not be advantageous.
Figures 192 and 193 show this same basic relationship when the annual
capital charges are considered along with the direct operating costs. Due to the
higher capital charges of units with heat exchange, the curves are closer and
will converge at a higher flow rate than in Figures 190 and 191. Where these
curves converge, heat recovery loses its economic advantage.
The economic relationship of catalytic incinerators and thermal units is
illustrated by Figure 194. Even when the catalytic units' higher capital charges
are considered, the savings in fuel keep the total cost of catalytic units lower
than that of similar thermal units.
Electrostatic Precipitators
Electrostatic precipitators were used in only two applications in this
report: vertical lime rock kilns and rotary lime sludge kilns. Figure 195 shows
that the precipitator and installed system costs correlate well for both
applications. The high efficiency unit costs 20 to 30% more than the medium
efficiency unit, for the precipitator alone as well as for the installed system.
The cost of the installed system was from about 2 to 2.5 times that of the
precipitator alone.
(Text continued on page 696)
686
-------
7891.
FIGURE 186
CAPITAL COST OF INCINERATORS ONLY,
WITHOUT H. E.
THERMAL
CATALYTIC
F CATALYTIC
AS FLOW RATE, ACFM
6 7 8 .9 I
-------
6 7891
FIG_UREJ87_
TOTAL INSTALLED COST OF
INCINERATORS WITHOUT H. E.
THERMAL
CATALYTIC
CATALYTIC
HERMALj,
INLET GAS FLOW RATE, ACFM
I I I I I I I I I I I I I I I I I I I I I I II I III I I I I I I M
6 7 8 9 1Q4
67891
-------
789
5 67891
6 7891.
FIGURE 188
CAPITAL COST OF INCINERATORS ONLY,
WITH H. E.
INLET GAS FLOW RATE, ACFM
-------
THERMAL
CATALYTIC
FIGURE 189
INLET GAS FLOW RATE, ACFM
I I 10
690
-------
it 1 ±: ± ± ±h±±±± ±H
i-H- -M--r -Hi- -H-H- l-Hi iirt H
FIGURE 190
1DIRECT OPERATING COSTS OF
THERMAL INCINERATORS
E3i WITHOUT H.E.
WITHOUT HEAT EXCHANGE
WITH HEAT EXCHANGE
JNLET
GAS FLOW RATE, ACFM Cl
! : ! i i I * ; ! ! I ' • , il ! i I I 1 I M 11 I I' 11 1 lit
B 6 7 8 9 10
691
-------
FIGURE 191
rDIRECT OPERATING COST OF
CATALYTIC INCINERATORS
T HEAT EXCHANGE
WITH HEAT EXCHANGE
LET GAS FLO
7 8 9 10
692
-------
FIGURE 192
TOTAL OPERATING COST OF
THERMAL INCINERATORS
INCLUDING ANNUALIZED CAPITAL CHARGES)
WITHOUT HEAT EXCHANGE
WITH HEAT EXCHANGE
6 6 7 8 9 10
693
-------
10
o
8
7
6
5
4
-mt
±±
±h
.inj_
iiii
-H-H-H-H
m
-HI4
ifci
FIGURE 193 .ILL
TOTAL OPERATING COST _
OF CATALYTIC INCINERATORS _L|
(INCLUDING ANNUALIZED CAPITAL CHARGES)^ i
_ i.» ..I -_;_ . L ! :_ L ..:li • . . I ' I : : ! ... L. - - .1 • . : • i : : i_ :. _i. . . . *, ... .~j
r-TT
-ItH
Hit
ii
10
WITHOUT H.E.
WITH H.E.
INLET GAS FLOW RATE,
1.0
10
5 6 7 8 9 10
694
-------
10
9
8
7
6
5
iimi 1
-H-
FIGURE 194
TOTAL OPERATING COST OF
INCINERATORS WITHOUT H. E.
(INCLUDING ANNUALIZED CAPITAL CHARGES)
THERMAL
CATALYTIC
INLET GAS FLOW RATE, ACFM
7 8 9104
3 4 6 6789 10
695
-------
Figure 196 shows the direct operating costs of precipitators. These, too,
correlated well. The data shows that the cost of operating a high efficiency unit
is about 25 to 35% more than that of operating a medium efficiency unit.
Nearly all of the increase is due to the increased use of electrical power.
Carbon Adsorption
Carbon adsorption was used in only one application in this report. The
only correlations necessary were made when the costs were presented in the
previous section of this report.
696
-------
JO~_.
INSTALLED
HIGH EFFICIENCY
MEDIUM EFFICIENCY
i COST OF PRECIPITATOR ONLY
EFFICIENCY
MEDIUM EFFICIENCY
VERTICAL LIME ROCK K LIV
ROTARY LIME SLUDGE KILN
FIGURE 195
CAPITAL COST OF
ELECTROSTATIC PRECIPITATORS
INLET GAS FLOW RATE, ACFM
- . . 4 . . - -1 . - - -UI- . .f- -
"TIT F TT " T!l" " t
^ilHHIitHIH-iH^hii'jHt^1 '
2.5
9 10
697
-------
EFFICIENCY
MEDIUM
EFFICIENCY
VERTICAL ROCK LIME KILN
ROTARY LIME SLUDGE KIL
FIGURE 196
DIRECT OPERATING COST OF
ELECTROSTATIC PRECIPITATORS
•jlT! I
:B:d::±ffrffl;riii
-H rt-H-l Wffitl- i-
1.5
2.5
INLET GAS FLOW RATE, ACFM Ij]
•I'r'l-'.'' ' • ' ' i • i • i i i rrn ---
8 9 1Q5
1.5
2.5
6 7 I 9 10
698
-------
APPENDIX I
SPECIFICATIONS FOR ABATEMENT EQUIPMENT
/. 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
-------
(ft Piping
(g) Insulation
(h) Painting
(i) Startup
(k) Performance Test
(I) Other (including general tradework such as erection, rigging, etc.)
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 sho wing general arrangemen t.
b. Typical details of collector internals proposed.
c. Data relating projected performance with respect to pressure drop, gas
absorption efficiency and paniculate removal efficiency to operating
parameters such as gas flow.
2. Upon receipt of order:
a. Proposed schedule of design and delivery.
3. Within 60 days of order:
a. Complete drawings of equipment for approval by customer.
4. 30 days prior to shipmen t:
a. Certified drawings of equipment, six sets
b. Installation instructions, six sets
c. Starting and operating instructions, six sets
d. 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.
-------
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 IGCI 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 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. General tradework, including rigging, erection, etc. should be included in
the "Other" category.
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 in the units indicated below.
Please include the unit price.
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.
Be sure that the operating factor, in hours per year, supplied by ARI, is used
for estimating the utility and labor requirements.
-------
APPENDIX III
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
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APPENDIX Ill-a
AVERAGE HOURLY LABOR RATES BY TRADE
Trade
Common Building Labor
Skilled Average
Helpers Average
Foremen (usually 35^ over 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
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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 ***COIMLIM are based
on the following formulas:
Confidence limits = X ± stn i . .,
ii- 1 , ~f
where
X = the sample mean, based on three bids in most cases
s = the sample standard deviation
" tlie ^Y* ^^ percentage point of the student-t distribution
n-1 • v
with n-1 degrees of freedom
Size of sample - n, usually three
Sample mean value =-
Variance of sample = ~ 5"? (X-, -
i= 1
/£(XrX)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:
vs2
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APPENDIX V
LIST OF STANDARD ABBREVIATIONS
feet or foot ft
inch or inches in.
ton or tons ton
pound or pounds Ib
hours or hours hr
minute or minutes min
parts per million ppm
grain or grains gr
weight percent wt.%
actual cubic feet per minute ACFM
standard cubic feet per minute SCFM
dry standard cubic feet per minute DSCFM
standard cubic feet SCF
actual cubic feet ACF
British thermal units Btu
odor units o.u.
volume vol
mole mol
gallon gal
per cent %
dollars $
degrees Fahrenheit °F
pounds per square inch gauge psig
change of pressure (delta pressure) A P
water column (pressure) w.c.
change of temperature (delta temperature) A T
temperature Temp
feet per minute FPM
dry standard cubic feet DSCF
cubic feet ft3
revolutions per minute rpm
gallons per minute gpm
millions (106) MM
atmospheres gage (pressure) atmg
milligrams m9
micrograms yg
international unit ID
hundred weight (100 pounds) cwt
hydrocarbon Hcbn
United States pharmacopoeia ygp
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BIBLIOGRAPHIC DATA
SHEET
1. Report No.
2.
3. Recipient's Accession No.
4. Title and Subtitle
Air Pollution Control Technology and Costs in Eight
Selected Industries
5. Report Date
(Date of issire)
^ igj ^
6.
7. Author(s)
8. Performing Organization Kept.
No'47.173
9. Performing Organization Name and Address
Industrial Gas Cleaning Institute
P.O. Box 1333
Stamford, Connecticut 06904
10. Project/Task/Work Unit No.
11. Contract/Grant No.
68-02-0289
12. Sponsoring Organization Name and Address
Environmental Protection Agency
Durham Contract Operations
Research Triangle Park
North Carolina, 27711
13. Type of Report & Period
Covered
Final
14.
15. Supplementary Notes
16. Abstracts
Under this contract, the Industrial Gas Cleaning Institute collected and formalized
date on air pollution abatement in eight selected industrial areas. Those eight
areas were: Phosphate Fertilizer Manufacture, Feed and Grain Milling, Soap and
Detergent Manufacture, Paint and Varnish Production, The Graphic Arts Industry, Lime
Kiln Operation, and Gray Iron Foundry Cupola Operation. For each area studied, costs
of conventionally applied pollution control systems are presented for a range of
plant sizes and control efficiencies.
17. Key Words and Document Analysis. 17a. Descriptors
Air Pollution
Performance
Air Pollution Control Equipment
Cost Estimates
Cost Engineering
Expenses
Electrostatic Precipitators
Scrubbers
Incinerators
Fabric Filters
17b. Identifiers/Open-Ended Terms
Air Pollution Control
Graphic Arts
Phosphate Fertilizer
Paint and Varnish
Lime Kilns
17c. COSATI Field/Group 13.b
Feed and Grain
Soap and Detergent
Gray Iron Foundries
18. Availability Statement
Release Unlimited
19. Security Class (This
Report)
UNCLASSIFIED
20. Security Class (This
Page
UNCLASSIFIED
21. No. of Pages
724
22. Price
FORM NTIS-35 (REV. 3-72)
USCOMM-DC I4852-P72
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INSTRUCTIONS FOR COMPLETING FORM NTIS-35 (10-70) (Bibliographic Data Sheet based on COSATI
Guidelines to Format Standards for Scientific and Technical Reports Prepared by or for' the Federal Government,
PB-180 600).
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2. Leave blank.
3. Recipient's Accession Number. . Reserved for use by each report recipient.
4- Title and Subtitle. Title should indicate clearly and briefly the subject coverage of the report, and be displayed promi-
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6. Performing Organization Code. Leave blank.
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from the performing organization.
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If the report contains a significant bibliography or literature survey, mention it here.
17. Key Words and Document Analysis, (a). Descriptors. Select from the Thesaurus of Knginecring and Scientific Term* the
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FORM NTIS-35 (REV. 3-72) USCOMM-DC 14M2-P72
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