U.S. DEPARTMENT OF COMMERCE
National Technical Information Service
PB-245 065
AIR POLLUTION CONTROL TECHNOLOGY AND COST:
SEVEN SELECTED RMISSION SOURCES
Industrial Gas Cleaning Institute
Prepared for:
Environmental Protection Agency
De ce mber 1974
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EPA-450/3-74J060
DECEMBER 1974
AIR POLLUTION CONTROL
TECHNOLOGY AND COSTS*
SEVEN SELECTED
EMISSION SOURCES
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
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TECHNICAL RFPORT DATA
(Please read f>;-tfin ti.iiiS on t/i- reverse before compiling)
EPORT NO.
EPA-450/3-74J060
3. RECIPIENT'S ACCESSION>NO.
4. TITLE AND SUBTITLE
Air Pdllution Control Technology and Costs
Seven Selected Emission Sources
5. REPORT DATE
December, 1974 ,
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO
47.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Industrial Gas Cleaning Institute
P.O. Box 1333 -
Stamford, Connecticut'/O6904 .
10. PROGRAM ELEMENT NO.
I
11. CONTRACT/GRANT NO.
68-02-1091
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Protection Agency
Office of Air and Waste Management
Office of Air Quality Planning and Standards
. No. Carolina 27711
13. T.YPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
16. ABSTRACT
Under this contract, the Industrial Gas Cleaning Institute collected
and formalized data on air pollution abatement for seven selected
industrial emission sources. These seven sources were:
Kraft Paper Mills, Ferroalloy Furnaces, Grain Cleaning
Houses, Glass Melting Furnaces, Crushed Stone and
Aggregate, Asphalt Saturation, and Surface Coating
Operation.
For each source area studied, costs of conventionally applied pollution
control systems are presented for a range of plant sizes and control
efficiencies.
17. .... i WORDS AND DOCUMENT ANALYSIS
a. ' DESCRIPTORS
Air Pollution Performance
Air P6llution Control Equipment
Cost Estimates
Cost Engineering Mechanical Collect
ors
Electrostatic Precipitators
Incinerators
Scrubbers Fahrir Filtnrs
18. DISTRIBUTION STATEMENT
kelciiso Unlimited
b. IDENTIFIERS/OPEN ENDED TERMS
Air Pollution Control
Kraft Processes
Ferroalloy
-Crushed Stone ง Aggre
gate
Glass Furnaces
Grain Cleaning
^i IT fact* Cnatina
19. SECURITY CLASS (ThisTteportf
Unclassified
20. SECURITY CLASS (This page)
Unclassified
XXX9ฎeX'X!X#J&<*$[
- Asphalt
Saturation
21. NO. OF PAGES
EPA Form 2220-1 (9-73)
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ฃPA-450/3-74f060
AIR POLLUTION CONTROL TECHNOLOGY
AND COSTS: SEVEN SELECTED
EMISSION SOURCES
KRAFT MILL RECOVERY BOILERS,
FERROALLOY FURNACES,
FEED AND GRAIN PROCESSING,
GLASS MELTING FURNACES, CRUSHED
STONE AND AGGREGATE INDUSTRY,
ASPHALT SATURATORS,
INDUSTRIAL SURFACE COATINGS
by
Industrial Gas Cleaning Institute, Inc.
P.O. Box 1333
Stamford, Connecticut 06904
Contract No. 68-02-1091
EPA Project Officer: Paul A. Boys
Prepared for
ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, N. C. 27711
December 1974
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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, for a fee, from the National Technical Information Service,
5285 Port Royal Road, Springfield, Virginia 22161.
This report was furnished to the Environmental Protection Agency by
Industrial Gas Cleaning Institute, Inc. , Stamford, Connecticut, in fulfillment
of Contract No. 68-02-1091. The contents of this report are reproduced
herein as received from Industrial Gas Cleaning Institute, Inc. The
opinions, findings, and conclusions expressed are those of the author and
not necessarily those of the Environmental Protection Agency. Mention of
company or product names is not to be considered as an endorsement by the
Environmental Protection Agency.
Publication No. EPA-450/3-74-060
11
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Contract Number 68-02-1091
Air Pollution Control
Technology And Costs
In Seven Selected Areas
including
Kraft Mill Recovery Boilers
Ferroalloy Furnaces
Feed and Grain Processing
Glass Melting Furnaces
Crushed Stone and Aggregate Industry
Asphalt Saturators
Industrial Surface Coatings
Final Report
(Completed 15 May, 1975)
by
L. R. Steenberg, Coordinating Engineer
for
Industrial Gas Cleaning Institute
Box 1333, Stamford, Connecticut 06904
Prepared For
The Environmental Protection Agency
Durham, North Carolina 27701
H a
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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.
BELCO POLLUTION CONTROL CORP.
BUFFALO FORGE COMPANY
THE CARBORUNDUM COMPANY
POLLUTION CONTROL DIVISION
C E AIR PREHEATER
THE CBLCOTE COMPANY, INC.
CHEMICAL CONSTRUCTION CORP.
AIR POLLUTION CONTROL COMPANY
THE DUCON COMPANY, INC.
SUBS. OF U. S. FILTER CORP.
DUSTEX CORPORATION
SUBS. OF AMERICAN PRECISION
INDUSTRIES, INC.
ENVIRONEERINQ, INC.
ENVIROTECH-CORPORATION
FISHER-KLOSTERMAN, INC.
FULLER COMPANY, DRACCO PRODUCTS
GALLAGHER-KAISER CORPORATION
INDUSTRIAL CLEAN AIR, INC.
JOHNS MANVILLE
THE KIRK ft 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, MC.
PRECIPITATION ASSOCIATES OF AMERICA
RESEARCH-COTTRELL, INC.
THE TORIT CORPORATION
WESTERN PRECIPITATION DIVISION
JOY MANUFACTURING COMPANY
WHEELABRATOR-FRYE, INC.
AIR POLLUTION CONTROL DIVISION
ZURN AIR SYSTEMS
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, far Correction Division, UOP
C. A. Gallaer, Envirotech Corp.
N. D. Phillips, Fuller Co., Dracco Products
E. J. Malarkey, Whoe/abrator-Frye. Inc., Air Pollution Control Division
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TABLE OF CONTENTS
Page No.
I Introduction 1
II Technical Data 1
A. General Description 1
1. Format 1
2. Selection of Applicable Equipment Types 2
3. Basis for Preparing Specifications and Bid Prices 3
4. Presentation of Data 9
B. Process Description and Costs 11
1. Kraft Pulp Mills 11
2. Ferroalloy Furnaces 49
3. Grain Cleaning Houses 83
4. Glass Melting Furnaces 99
5. Crushed Stone and Aggregate Industry 141
6. Asphalt Saturation 179
7. Surface Coating Operations 215
C. Additional Cost Data 246
1. Discussion of Cost Basis 246
2. Discussion of Utility Price Levels 248
3. Derived Capital Cost Indices 249
D. Generalized Cost Data 289
III Appendix
A. Specifications for Abatement Equipment 305
B. Instructions for Submitting Cost Data 311
C. City Cost Indices 315
D. Average Hourly Labor Rates by Trade 317
E. List of Standard Abbreviations 319
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UST OF FIGURES
Page No.
Figure 1 Process Flow Diagram Black Liquor Recovery 14
Figure 2 Row Diagram of Conventional Recovery Furnace 18
Figure 3 Relation Between hfeS Production and Furnace Loading 20
Figure 4 Black Liquor Recovery Using Oxidation Block Flow
Diagram 21
Figure 5 Flow Diagram of Air Contact Evaporation System 23
Figure 6 Flow Diagram of Laminaire Air Heater System 24
Figure 7 Flow Diagram of Large Economizer System 26
Figure 8 Capital Cost of Electrostatic Precipitators for Kraft Pulp Mill
Conventional Recovery Furnace (Medium Efficiency) 35
Figure 9 Annual Cost of Electrostatic Precipitators for Kraft Pulp Mill
Conventional Recovery Furnace (Medium Efficiency) 36
Figure 10 Capital Cost of Electrostatic Precipitators for Kraft Pulp Mill
Conventional Recovery Furnace (High Efficiency) 37
Figure 11 Annual Cost of Electrostatic Precipitators for Kraft Pulp Mill
Conventional Recovery Furnace (High Efficiency) 38
Figure 12 Capital Cost of Electrostatic Precipitators for Kraft Pulp Mill
Controlled Odor Recovery Furnace (Medium Efficiency) 43
Figure 13 Annual Cost of Electrostatic Precipitators for Kraft Pulp Mill
Controlled Odor Recovery Furnace (Medium Efficiency) 45
Figure 14 Capital Cost of Electrostatic Precipitators for Kraft Pulp Mill
Controlled Odor Recovery Furnace (High Efficiency) 46
Figure 15 Annual Cost of Electrostatic Precipitators for Kraft Pulp Mill
Controlled Odor Recovery Furnace (High Efficiency) 47
Figure 16 Electric Furnace for Ferroalloy Production 51
Figure 17 Sealed Furnace for Producing Ferroalloys 55
Figure 18 Covered Furnace for Producing Ferroalloys 56
Figure 19 Capital Cost of Fabric Filters for Ferrosilicon Furnaces 66
Figure 20 Annual Cost of Fabric Filters for Ferrosilicon Furnaces 68
Figure 21 Capital Cost of Fabric Filters for Silicon Metal Furnace
(Dilution Cooling) 72
Figure 22 Annual Cost of Fabric Filters for Silicon Metal Furnace
(Dilution Cooling) 74
Figure 23 Capital Cost of Fabric Filters for Silicon Metal Furnace
(Evaporative Cooling) 78
Figure 24 Annual Cost of Fabric Filters for Silicon Metal Furnace
(Evaporative Cooling) 80
Figure 25 Flow Diagram for Grain Cleaning House 85
Figure 26 Capital Cost of Fabric Filters for Grain Cleaning House 95
Figure 27 Annual Cost of Fabric Filters for Grain Cleaning House 97
iv
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LIST OF FIGURES (cent.)
Page No.
Figure 28 Flow Diagram for Soda-Lime Glass Manufacture 106
Figure 29 Process Flow Diagram of a Batch Plant 107
Figure 30 Log-Probability Distribution of Particle Sizes Present
in Glass Furnace Effluent 112
Figure 31 Natural Gas for Bridgewall-Type Regenerative Furnace 117
Figure 32 Capital Cost of Electrostatic Precipitators for
Glass-Melting Furnace 125
Figure 33 Annual Cost of Electrostatic Precipitators for
Glass-Melting Furnace 127
Figure 34 Capital Cost of Wet Scrubbers for Glass-Melting Furnace 131
Figure 35 Annual Cost of Wet Scrubbers for Glass-Melting Furnace 133
Figure 36 Capital Cost of Fabric Filters for Glass-Melting Furnace 137
Figure 37 Annual Cost of Fabric Filters for Glass-Melting Furnace 139
Figure 38 Simplified Flow Diagram of a Typical Rock Gravel Plant 143
Figure 39 Capital Cost of Wet Scrubbers for Secondary and
Tertiary Rock Crushers (Medium Efficiency) 154
Figure 40 Annual Cost of Wet Scrubbers for Secondary and
Tertiary Rock Crushers (Medium Efficiency) 155
Figure 41 Capital Cost of Wet Scrubbers for Secondary and
Tertiary Rock Crushers (High Efficiency) 156
Figure 42 Annual Cost of Wet Scrubbers for Secondary and
Tertiary Rock Crushers (High Efficiency) 157
Figure 43 Capital Cost of Wet Scrubbers for Crushed Stone and
Aggregate Conveyor Transfer Points (Medium
Efficiency) 162
Figure 44 Annual Cost of Wet Scrubbers for Crushed Stone and
Aggregate Conveyor Transfer Points (Medium
Efficiency) 163
Figure 45 Capital Cost of Wet Scrubbers for Crushed Stone and
Aggregate Conveyor Transfer Points (High Efficiency) 164
Figure 46 Annual Cost of Wet Scrubbers for Crushed Stone and
Aggregate Conveyor Transfer Points (High Efficiency) 165
Figure 47 Capital Cost of Fabric Filters for Secondary and Tertiary
Rock Crushers 169
Figure 48 Annual Cost of Fabric Filters for Secondary and Tertiary
Rock Crushers 171
Figure 49 Capital Cost of Fabric Filters for Crushed Stone and
Aggregate Conveyor Transfer Points 175
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UST OF RQURES (cent)
Page No.
Figure 50 Annual Cost of Fabric Filters for Crushed Stone and
Aggregate Conveyor Transfer Points 177
Figure 51 Schematic Flow Diagram of Asphalt Saturation Process 181
Figure 52 Capital Cost of Wet Scrubbers for Asphalt Saturator 191
Figure 53 Annual Cost of Wet Scrubbers for Asphalt Saturator 193
Rgure 54 Capital Cost of Thermal Incinerators (With Heat Exchange)
for Asphalt Saturator (High Efficiency) 198
Figure 55 Annual Cost of Thermal Incinerators (With Heat Exchange)
for Asphalt Saturator (High Efficiency) 200
Figure 56 Capital Cost of High Energy Air Filters for Asphalt
Saturator 204
Rgure 57 Annual Cost of High Energy Air Rlters for Asphalt
Saturator 206
Figure 58 Capital Cost of Thermal Incinerators for Asphalt Blow Still
(With Heat Exchange) 211
Figure 59 Annual Cost of Thermal Incinerators for Asphalt Blow Still
(With Heat Exchange) 213
Figure 60 Water Wash Spray Booth 222
Figure 61 Down-Draft Water Wash Spray Booth 223
Figure 62 Schematic of Carbon Adsorption and Desorption Units 229
Figure 63 Flow Diagram of Thermal Incineration System 233
Figure 64 Annual Cost for Carbon Adsorption for Surface Coating
Operations 235
Rgure 65 Annual Cost for Catalytic Incineration (Without Heat
Exchange) for Surface Coating Operations 236
Rgure 66 Annual Cost for Catalytic Incinerators (Without Heat
Exchange) for Surface Coating Operations 237
Figure 67 Annual Cost for Thermal Incineration (Without Heat
Exchange) for Surface Coating Operations 238
Figure 68 Annual Cost for Thermal Incineration (With Heat Exchange)
for Surface Coating Operations 239
Rgure 69 Annual Cost for Carbon Adsorption for Surface Coating
Operations 240
Figure 70 Annual Cost for Catalytic Incineration (Without Heat
Exchange) for Surface Coating Operations 241
Figure 71 Annual Cost for Catalytic Incineration (With Heat Exchange)
for Surface Coating Operations 242
Rgure 72 Annual Cost for Thermal Incineration (Without Heat
Exchange) for Surface Coating Operations 243
Rgure 73 Annual Cost for Thermal Incineration (With Heat Exchange)
for Surface Coating Operations 244
vt
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LIST OF FIGURES (cont.)
Page No.
Figure 74 Capital Cost of Wet Scrubbers Only 293
Figure 75 Total Installed Cost of Scrubbing Systems 294
Figure 76 Direct Operating Cost of Wet Scrubbers 295
Figure 77 Capital Costs of Fabric Filters 296
Figure 78 Installed Costs of Fabric Filters 297
Figure 79 Direct Operating Costs of Fabric Filters 298
Figure 80 Capital Costs of Thermal Incinerators 299
Figure 81 Installed Cost of Thermal Incinerators with Heat Exchange 300
Figure 82 Direct Operating Cost of Thermal Incinerators
with Heat Exchange 301
Figure 83 Capital Cost of Electrostatic Precipitators 302
Rgure 84 Installed Cost of Electrostatic Precipitators 303
Figure 85 Direct Operating Cost of Electrostatic Precipitators 304
vii
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LIST OF TABLES
Page No.
Table 1 Abatement Equipment Types Selected for the Seven
Process Areas 4
Table 2 Process Weight Table for Medium Efficiency for Paniculate
Collection Cases Only 6
Table 3 Collection Efficiencies Selected for the Seven Process Areas 7
Table 4 Odorous Chemicals Emitted from Kraft Pulp Mills 17
Table 5 Electrostatic Precipitator Process Description for Conventional
Kraft Pulp Mill Recovery Furnace Specification 30
Table 6 Electrostatic Precipitator Operating Conditions for
Conventional Kraft Pulp Mill Recovery Furnace
Specification 32
Table. 7 Estimated Capital Cost Data (Cost in Dollars) for Electrostatic
Precipitators for Kraft Pulp Mill Conventional Recovery
Furnace 33
Table 8 Annual Operating Cost Data (Cost in $/Year) for Electrostatic
Precipitators for Kraft Pulp Mill Conventional Recovery
Furnace 34
Table 9 Electrostatic Precipitator Process Description for Kraft Pulp
Mill Controlled Odor Recovery Furnace Specification 39
Table 10 Electrostatic Precipitator Operating Conditions for Kraft Pulp
Mill Controlled Odor Recovery Furnace Specification 41
Table 11 Estimated Capital Cost Data (Cost in Dollars) for Electrostatic
Precipitators for Kraft Pulp Mill Controlled Odor Recovery
Furnace 42
Table 12 Annual Operating Cost Data (Cost in $/Year) for Electrostatic
Precipitators for Kraft Pulp Mill Controlled Odor Recovery
Furnace 43
Table 13 Compositions of Typical Ferroalloys 50
Table 14 Basic Overall Reactions for Ferroalloy Production 53
Table 15 Distribution of Domestic Ferroalloy Furnaces 54
Table 16 Weight Balance for Production of 45% Ferrosilicon 58
Table 17 Comparison of Gas Flows from Open and Closed Hood 50 MW
Submerged Arc Furnaces Making 50% Ferrosilicon 59
Table 18 Properties of Paniculate Emissions from Ferroalloy Furnaces ... 60
Table 19 Fabric Filter Process Description for Ferrosilicon Furnace
Specification 63
Table 20 Fabric Filter Operating Conditions for Ferrosilicon Furnace
Specification 64
viii
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LIST OF TABLES (cont.)
Page No.
Table 21 Estimated Capital Cost Data (Cost in Dollars) for Fabric Filters
for Ferrosilicon Furnace 65
Table 22 Annual Operating Cost Data (Cost in $/Year) for Fabric Filters
for Ferrosilicon Furnace 67
Table 23 Fabric Filter Process Description for Silicon Metal Furnace
Specification 69
Table 24 Fabric Filter Operating Conditions for Silicon Metal Furnace
Specification 70
Table 25 Estimated Capital Cost Data (Cost in Dollars) for Fabric Filters
for Silicon Metal Furnace (Dilution Cooling) 71
Table 26 Annual Operating Cost Data (Cost in $/Year) for Fabric Filters
for Silicon Metal Furnace (Dilution Cooling) 73
Table 27 Fabric Filter Process Description for Silicon Metal Furnace
Specification 75
Table 28 Fabric Filter Operating Conditions for Silicon Metal Furnace
Specification 76
Table 29 Estimated Capital Cost Data (Cost in Dollars) for Fabric Filters
for Silicon Metal Furnace (Evaporative Cooling) 77
Table 30 Annual Operating Cost Data (Cost in $/Year) for Fabric Filters
for Silicon Metal Furnace (Evaporative Cooling) 79
Table 31 Annual Grain Production Statistics 84
Table 32 Contaminants Generated During Grain Cleaning 88
Table 33 Properties of Dust Emitted from Grain Cleaning Operations 89
Table 34 Relative Advantages and Disadvantages of Cyclones
and Fabric Filters 90
Table 35 Fabric Filter Process Description for Grain Cleaning House
Specification 92
Table 36 Fabric Filter Operating Conditions for Grain Cleaning House
Specification 93
Table 37 Estimated Capital Cost Data (Cost in Dollars) for Fabric Filters
for Grain Cleaning House 94
Table 38 Annual Operating Cost Data (Cost in $/Year) for Fabric Filters
for Grain Cleaning House 96
Table 39 Approximate Compositions of Commercial Glasses 100
Table 40 Useful Range of Glass Viscosities 103
ix
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LIST OF TABLES (cent)
Page No.
Table 41 Glassmaking Materials 104
Table 42 Estimated National Emissions, 1971, Glass Furnaces 109
Table 43 Source Test Data for Glass-Melting Furnaces 110
Table 44 Size Distribution of Paniculate Emissions (Micromerograph
Analyses) 111
Table 45 Flue Conditions from the Manufacture of Glass 113
Table 46 Emissions from the Manufacture of Glass 114
Table 47 Chemical Composition of Paniculate Emissions
(Quantitative Analyses) 115
Table 48 Chemical Composition of Gaseous Emissions from Gas
Fired Regenerative Furnaces 118
Table 49 Electrostatic Precipitator Process Description for
Glass-Melting Furnace Specification ... 122
Table 50 Electrostatic Precipitator Operating Conditions for
Glass-Melting Furnace Specification 123
Table 51 Estimated Capital Cost Data (Cost in Dollars) for Electrostatic
Predpitators for Glass-Melting Furnace 124
Table 52 Annual Operating Cost Data (Cost in Dollars) for Electrostatic
Predpitators for Glass-Melting Furnace 126
Table 53 Wet Scrubber Process Description for Glass-Melting
Furnace Specification 128
Table 54 Wet Scrubber Operating Conditions for Glass-Melting
Furnace Specification 129
Table 55 Estimated Capital Cost (Cost in Dollars) for Wet Scrubbers
for Glass-Melting Furnace 130
Table 56 Annual Operating Cost Data (Cost in Dollars) for Wet
Scrubbers for Glass-Melting Furnace 132
Table 57 Fabric Filter Process Description for Glass-Melting Furnace
Specification .;; 134
Table 58 Fabric Filter Operating Conditions for Glass-Melting
Furnace Specification 135
Table 59 Estimated Capital Cost Data (Cost in Dollars) for Fabric
Filters for Glass-Melting Furnace 136
Table 60 Annual Operating Cost Data (Cost in Dollars) for Fabric
Filters for Glass-Melting Furnace .. 138
Table 61 Rock and Mineral Production Unit Operations 146
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LIST OF TABLES (cont.)
Page No.
Table 62 Wet Scrubber Process Description for Secondary and
Tertiary Rock Crusher Specification 150
Table 63 Wet Scrubber Operating Conditions for Secondary and
Tertiary Rock Crusher Specification 151
Table 64 Estimated Capital Cost Data (Cost in Dollars) for Wet
Scrubbers for Secondary and Tertiary Rock Crushers 152
Table 65 Annual Operating Cost Data (Cost in Dollars) for Wet
Scrubbers for Secondary and Tertiary Rock Crushers 153
Table 66 Wet Scrubber Process Description for Crushed Stone and
Aggregate Conveyor Transfer Points Specification 158
Table 67 Wet Scrubber Operating Conditions for Crushed Stone and
Aggregate Conveyor Transfer Points Specification 159
Table 68 Estimated Capital Cost Data (Cost in Dollars) for Wet
Scrubbers for Crushed Stone and Aggregate Conveyor
Transfer Points 160
Table 69 Annual Operating Cost Data (Cost in Dollars) for Wet
Scrubbers for Crushed Stone and Aggregate Conveyor
Transfer Points 161
Table 70 Fabric Filter Process Description for Secondary and
Tertiary Rock Crusher Specification 166
Table 71 Fabric Filter Operating Conditions for Secondary and
Tertiary Rock Crusher Specification 167
Table 72 Estimated Capital Cost Data (Cost in Dollars) for Fabric
Filters for Secondary and Tertiary Rock Crushers 168
Table 73 Annual Operating Cost Data (Cost in Dollars) for Fabric
Filters for Secondary and Tertiary Rock Crushers 170
Table 74 Fabric Filter Process Description for Crushed Stone and
Aggregate Conveyor Transfer Points Specification 172
Table 75 Fabric Filter Operating Conditions for Crushed Stone and
Aggregate Conveyor Transfer Points Specification 173
Table 76 Estimated Capital Cost Data (Cost in Dollars) for Fabric
Filters for Crushed Stone and Aggregate Conveyor
Transfer Points 174
Table 77 Annual Operating Cost Data (Cost in Dollars) for Fabric Filters
for Crushed Stone and Aggregate Conveyor Transfer
Points 176
Table 78 Number of Establishments and Value of Shipments of
Asphalt Saturated Products 180
xi
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LIST OF TABLES (cont.)
Page No.
Table 79 Wet Scrubber Process Description for Asphalt Saturator
Specification 188
Table 80 Wet Scrubber Operating Conditions for Asphalt Saturator
Specification 189
Table 81 Estimated Capital Cost Data (Cost in Dollars) for Wet
Scrubbers for Asphalt Saturator 190
Table 82 Annual Operating Cost Data (Cost in Dollars) for Wet
Scrubbers for Asphalt Saturator 192
Table 83 Thermal Incinerator (With Heat Exchange) Process
Description for Asphalt Saturator Specification 194
Table 84 Thermal Incinerator (With Heat Exchange) Operating
Conditions for Asphalt Saturator Specification 196
Table 85 Estimated Capital Cost Data (Cost in Dollars) for Thermal
Incinerators (With Heat Exchange) for Asphalt Saturator 197
Table 86 Annual Operating Cost Data (Cost in Dollars) for Thermal
Incinerators (With Heat Exchange) for Asphalt Saturator 199
Table 87 High Energy Air Filter Process Description for Asphalt
Saturator Specification 201
Table 88 High Energy Air Filter Operating Conditions for Asphalt
Saturator Specification 202
Table 89 Estimated Capital Cost Data (Cost in Dollars) for H.E.A.F.
for Asphalt Saturator 203
Table 90 Annual Operating Cost Data (Cost in Dollars) for H.E.A.F.
for Asphalt Saturator 205
Table 91 Thermal Incinerator Process Description for Asphalt Blow
Still Specification (With Heat Exchange) 207
Table 92 Thermal Incinerator (With Heat Exchange) Operating
Conditions for Asphalt Blow Still Specification 209
Table 93 Estimated Capital Cost Data (Cost in Dollars) for Thermal
Incinerators (With Heat Exchange) for Asphalt Blow Still 210
Table 94 Annual Operating Cost Data (Cost in Dollars) for Thermal
Incinerators (With Heat Exchange) for Asphalt Blow Still 212
Table 95 Examples of Surface-Coating Formulas on an As-Purchased
Basis 217
Table 96 Threshold Limit Values of Typical Paint Solvents 219
Table 97 Substitution of Exempt Solvent 227
Table 98 Sizes for Solvent Recovery Systems Using Activated
Carbon 231
xii
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LIST OF TABLES (cont.)
Page No.
Table 99 Units of Plant Size for Each Process Area 252
Table 100 Derived Cost Indices for Kraft Mill Recovery Furnaces 255
Table 101 Derived Cost Indices for Kraft Mill Controlled Odor Furnaces ... 256
Table 102 Derived Cost Indices for Ferrosilicon Furnace 257
Table 103 Derived Cost Indices for Silicon Metal Furnace
(Dilution Cooling) 258
Table 104 Derived Cost Indices for Silicon Metal Furnace
(Evaporative Cooling) 259
Table 105 Derived Cost Indices for Grain Cleaning House 260
Table 106 Derived Cost Indices for Glass-Melting Furnace
(Electrostatic Precipitation) 261
Table 107 Derived Cost Indices for Glass-Melting Furnace
(Wet Scrubbing) 262
Table 108 Derived Cost Indices for Glass-Melting Furnace
(Fabric Filtration) 263
Table 109 Derived Cost Indices for Secondary and Tertiary Rock Crusher
(Wet Scrubbing) 264
Table 110 Derived Cost Indices for Crushed Stone and Aggregate
Conveyor Transfer Points (Wet Scrubbing) 265
Table 111 Derived Cost Indices for Secondary and Tertiary Rock
Crusher (Fabric Filtration) 266
Table 112 Derived Cost Indices for Crushed Stone and Aggregate
Conveyor Transfer Points (Fabric Filtration) 267
Table 113 Derived Cost Indices for Asphalt Saturator (Wet Scrubbing) 268
Table 114 Derived Cost Indices for Asphalt Saturator
(Thermal Incineration) 269
Table 115 Derived Cost Indices for Asphalt Saturator (Glass Fiber
Mat Filtration) 270
Table 116 Derived Cost Indices for Asphalt Blow Still 271
Table 117 Derived Cost per SCFM for Kraft Mill Recovery Furnaces 273
Table 118 Derived Cost per SCFM for Kraft Mill Controlled
Odor Furnaces 274
Table 119 Derived Cost per SCFM for Ferrosilicon Furnaces 275
Table 120 Derived Cost per SCFM for Silicon Metal Furnaces 276
Table 121 Derived Cost per SCFM for Grain Cleaning Houses 277
Table 122 Derived Cost per SCFM for Glass-Melting Furnaces
(Electrostatic Precipitation) 278
XIII
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UST OF TABLES (cent.)
Page No.
Table 123 Derived Cost per SCFM for Glass-Melting Furnaces
(Wet Scrubbing) 279
Table 124 Derived Cost per SCFM for Glass-Melting Furnaces
(Fabric Filtration) 280
Table 125 Derived Cost per SCFM for Secondary and Tertiary Rock
Crusher (Wet Scrubbing) 281
Table 126 Derived Cost per SCFM for Crushed Stone and Aggregate
Conveyor Transfer Points (Wet Scrubbing) 282
Table 127 Derived Cost per SCFM for Secondary and Tertiary Rock
Crusher (Fabric Filtration) 283
Table 128 Derived Cost per SCFM for Crushed Stone and Aggregate
Conveyor Transfer Points (Fabric Filtration) : 284
Table 129 Derived Cost per SCFM for Asphalt Saturator
(Wet Scrubbing) 285
Table 130 Derived Cost per SCFM for Asphalt Saturator
(Thermal Incineration) 286
Table 131 Derived Cost per SCFM for Asphalt Saturator (Glass Fiber
Mat Filtration) 287
Table 132 Derived Cost per SCFM for Asphalt Blow Still 288
Table 133 Plotting Symbol Key 290
xiv
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LIST OF APPENDICES
Appendix A Specifications for Abatement Equipment
Appendix B Instructions for Submitting Cost Data
Appendix C City Cost Indices
Appendix 0 Average Hourly Labor Rates by Trade
Appendix E List of Standard Abbreviations
xv
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I. INTRODUCTION
The Industrial Gas Cleaning Institute (IGCI) is an association of manufacturers
of gas cleaning equipment, used primarily for the abatement of air pollution.
Under this contract, the IGCI is collecting and formalizing data on air pollution
control in seven industrial areas selected by the EPA. These areas are:
1. Kraft Mill Recovery Boilers
2. Ferroalloy Furnaces Phase I
3. Feed and Grain Cleaning Houses
4. Glass-Melting Furnaces _
5. Crushed Stone and Aggregate Plants"
6. Asphalt Saturation Plants
7. Industrial Surface Coating Operations^,
This final report contains all of the technical information assembled for both
the three process areas of Phase I and the four process areas of Phase II.
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.
II. TECHNICAL DATA
This section contains all of the data collected as a 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 IGCI
member companies active in each field. The cost data, however, is entirely
the product of companies judged most qualified. In addition to IGCI member
companies, some 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.
A. GENERAL DESCRIPTION
1. Format
This study includes seven industrial areas, divided into two groups, each of
-------
which were covered by a separate earlier phase report. In this final
report, the two phases are combined and summarized.
There are seven sections in this report, 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. Others
3. Summary Comments
This material will not be presented in outline form, nor will each item
necessarily be included for each process area.
2. Selection of Applicable Equipment Types
Emissions from the industries studied under this contract fall into two
broad classes: paniculate matter, and hydrocarbons. Five of the seven
study areas, including all of those in Phase I, are concerned primarily
with emissions of particulate matter. These five include:
Kraft Mill Recovery Boilers (Conventional and Controlled Odor Types)
Ferroalloy Furnaces
Feed and Grain Cleaning Houses
Glass Melting Furnaces
Crushed Stone and Aggregate Rants
Odor problems in kraft mills are normally dealt with through process
modification. One common modification for odor control is the "controlled
odor" type of recovery boiler. While the kraft mill recovery boiler study
investigates control of particulate emissions from both kinds of boilers,
the study does not cover odor abatement techniques or performances,
per se. It includes the controlled odor type boiler only because it represents
a common boiler type, currently in use, requiring particulate emission
control.
The other two study areas are concerned primarily with hydrocarbon
-------
emissions:
Asphalt Saturation Plants
Industrial Surface Coating Operations
All of the conventional pollution abatement devices will be included in
this seven industry study, as indicated below:
Control of Paniculate Matter Control of Hydrocarbons
Electrostatic Precipitators Incinerators
Fabric Filters Adsorption Units
Wet Scrubbers Absorption Units
In general, a given process is amenable to control by more than one
type of device. 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 industrial surveys, source testing, and other programs may
furnish additional insight into the equipment types predominating in well-
controlled installations. This information was incorporated into the judg-
ments reached by the Engineering Standards Committee through a
series of technical exchange meetings with the EPA.
Selections of equipment types to be studied were made during several
Engineering Standards Committee meetings and technical exchange
meetings. Present at all of the technical exchange meetings were
representatives of the following groups:
EPA Economics Analysis Branch
EPA Industry Studies Branch
IGCI Technical Director
IGCI Engineering Standards Committee
ARI Project Coordinator
The end results of this selection process are presented in 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. The costs of 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.
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TABLE 1
ABATEMENT EQUIPMENT TYPES SELECTED
FOR THE SEVEN PROCESS AREAS
Process Area
Kraft Mill
Recovery Boilers
Ferroalloy Furnaces
Feed and Grain
Processing
Glass-Melting Furnace
Crushed Stone and
Aggregate Plant
Emission Source
Conventional Boiler
Controlled Odor Boiler
Open Furnace
Cleaning House
Soda-Lime Glass-Melting
Furnace
Equipment Type
Electrostatic Precipitator
Electrostatic Precipitator
Fabric Fitter
Fabric Filter
Electrostatic Precipitator
Wet Scrubber
Fabric Filter
Secondary and Tertiary Wet Scrubber
Rock Crushers Fabric Filter
Conveyor Transfer Points Wet Scrubber
Fabric Filter
Asphalt Saturation Plant Asphalt Saturator
Industrial Surface
Coating Operations
Asphalt Blow Still
Wet Scrubber (absorber)
Thermal Incinerator
High Energy Air Fitter
Thermal Incinerator
Spray Coating Chambers Carbon Adsorption
Thermal Incinerator
Catalytic Incinerator
-------
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. Two levels of performance were specified for most
types of equipment so that costs could be related to the degree of
emission reduction as well as to gas handling capacity. The two perform-
ance levels are called "medium efficiency" and "high efficiency." For
each of the seven process areas, numerical collection efficiencies
were specified for each performance level during the technical exchange
meetings with EPA. In those cases where fabric filters were applied,
only one performance level was specified, the "high efficiency" level.
The efficiencies were chosen on the basis of the following criteria:
High Efficiency A sufficiently low grain loading to expect a
clear stack.
Medium Efficiency The process weight table published in the
Federal Register April 7, 1971, or other
process operating emission factors re-
lated to the specific industry under study.
The process weight table used is presented in Table 2. Table 3 lists the
collection efficiencies specified for each case.
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 section of descriptive material and one section 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 A 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:
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TABLE 2
PROCESS WEIGHT TABLE FOR MEDIUM EFFICIENCY
FOR PARTICULATE MATTER COLLECTION CASES ONLY*
Process Weight Rate of
Rate (Ib/hr) Emission (Ib/hr)
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
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TABLE 3
COLLECTION EFRCIENCIES SELECTED FOR SEVEN PROCESS AREAS
Emission Source
Kraft Mill
Recovery Boilers
Emission Type
Paniculate Matter
Equipment Type
Medium Efficiency High Efficiency
Ferroalloy Furnaces Particulate Matter
Feed & Grain Particulate Matter
Processing
Glass-Melting Furnace Particulate Matter
Crushed Stone and
Aggregate Industry
Secondary and Ter- Particulate Matter
tiary Rock Crushers
Conveyor Transfer
Points
Asphalt Saturator
Asphalt Blow Still
Particulate Matter
Hydrocarbons
Hydrocarbons
(1) Only one efficiency specified
(2) Process Weight Table
(3) ADT = Air dried ton of pulp
Electrostatic Precipitator
Fabric Fitter
Fabric Fitter
Electrostatic Precipitator
Wet Scrubber
Fabric Filter
Wet Scrubber
Fabric Filter
Wet Scrubber
Fabric Filter
Wet Scrubber (absorber)
Thermal Incinerator
High Energy Air Filter
1.7lb/ADT(3)
(0.035 gr/DSCF)
(D
(1)
(1)
(1)
(D
(2)
(D
0.04 gr/ACF
(D
(D
98%
(1)
0.02 gr/DSCF
(1.0lb/ADT)
0.01 gr/ACF
0.01 gr/ACF
0.01 gr/ACF
0.01 gr/ACF
0.01 gr/ACF
0.01 gr/ACF
0.01 gr/ACF
0.01 gr/ACF
0.01 gr/ACF
8 Ib/hr
99%
98%
Thermal Incinerator
(1)
99%
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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
bidders to quote on the auxiliary equipment, such as fans, pumps, solids
handling devices, etc., and to quote on an approximate installation cost.
A complete set of instructions for quoting is given in Appendix B.
Labor costs vary from one location to another, and it was not possible
to establish the complex pattern of variations in turnkey prices which
occur as a function of local variations in hourly rates, 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 C were used. 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
participant's point of shipment with a labor index 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 D 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 the 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
quantity required, rather than cost. This was done because the operating
costs will be analyzed in terms of standard utility and labor rates.
Air pollution control costs for the Industrial Surface Coatings section
of this report were not obtained in the same fashion as costs for the
-------
other three study areas. Equipment specifications were not prepared
nor were specific bids solicited. Instead, the three firms selected as
"most expert reviewers" reviewed generalized economics for the
common types of abatement systems used for control in this industry.
These generalized economics are presented as part of the narrative
portion of the report.
4. Presentation of Data
Estimates of both capital cost and annual operating cost are presented
for each type of abatement equipment applied to each of the seven
industries covered under the program. In general, the capital cost data
are presented in one table, which shows the averaged details of the
bids submitted for each application, followed by a graph. The graph
shows the capital cost for the abatement device, the total equipment
cost, and the turnkey system cost correlated with plant size.
Operating costs are also presented in similar fashion. A table shows
averaged annual estimates of labor, maintenance, and utilities, and
an estimate of the annualized capital charge, computed as a percentage
of total system capital cost. Graphs present direct annual cost and
total annual cost correlated with plant size.
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B. PROCESS DESCRIPTION AND COSTS
1. KRAFT PULP MILLS
Paper has evolved from early man's use of bark, ivory, papyrus, and parchment
in an effort to record activities and events. In the early nineteenth century, paper
production methods employed rags as the primary raw material. Improving levels
of communication created a rapidly increasing demand for paper leading to increased
production and a subsequent scarcity of rags. Inventors, however, responded to
this scarcity by developing production methods which utilized wood. The second
half of the nineteenth century saw development of first mechanical, and then chemical
methods for pulping wood.
Since the turn of the century, wood has become the most important source of
fiber for paper pulps. Sulfate, or kraft, pulping is one of two main chemical processes
used to convert wood to papermaking fibers. Sulfite pulping, similar in many process
details to the kraft method, also employs chemical means but produces pulp with
lower physical strength and opacity. Other processes in use are mechanical pulping,
where logs are reduced to fiber by physical grinding, and "chemi-mechanical"
pulping which combines both chemical and mechanical methods of defibration.
The soda process, which is similar in many respects to the sulfite and sulfate
process accounts for only a small percentage of the pulp produced.
The kraft process, introduced to the United States in 1908, is aptly named
because kraft is the German word for strong and the kraft product is characterized
by superior physical strength. In 1966, more than 63% of the total U.S. production
of pulp was made by the kraft process. The majority of new chemical pulp manu-
facturing facilities built since then, or currently in the design stage, also use the
kraft process.
KRAFT PROCESS DESCRIPTION
In kraft or sulfate pulping, separation of fibers is accomplished by chemical
treatment to dissolve the lignin which bonds wood fibers together. The chemical
reactions responsible for this defibration involve hydrolysis of lignins in the wood
to alcohols and acids. This hydrolysis also produces mercaptans and sulfides which
are responsible for the familiar odor around sulfate-pulp mills. This reaction takes
place in the digesters. The chemicals used in kraft milling are too expensive to
discard. Consequently, much of the pulping process is devoted to recovery and
reuse of these chemicals.
It is possible to produce relatively pure cellulose fiber by the kraft process,
since almost fifty percent of the log is extracted. Papers from this pulp have high
Preceding page blank
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physical strength, bulk, and opacity; low unbleached brightness; and relatively poor
sheet formation properties. Both bleached and unbleached sulfate pulps are used
as packaging papers, container board, and a variety of printing and bond papers.
The kraft process consists of the following steps.
1. Logs are debarked. The bark is often used as a fuel in the bark power
boiler along with either coal, gas, or oil. Bark power boilers, as an emission
source, have been studied in depth under a separate EPA contract,
No. 68-02-0301, entitled "Air Pollution Control Technology and Costs in
Nine Selected Areas". In some areas the bark is prepared for a garden
mulch. However, with the increasing cost of other fuels, it must be con-
sidered as a potential source of energy.
2. The debarked logs are conveyed to chippers which are large rotating
discs holding four or more long heavy knives. The chipper reduces the
wood to small chips. The chips are screened for size to separate those
of the desired size from those that are too large and from sawdust.
Oversize chips are sent through crushers to reduce them to the proper
size. Proper sized chips are send to a chip bin or silo where they may be
joined by chips that have arrived by rail or truck from lumber, veneer,
and ply-wood mills.
3. From the chip bin the wood chips are fed to the digester. Two types of
digesters in wide use today are the continuous digester and batch digester.
There are also a few rotary digesters still in use. Continuous digesters
are tall towers that are fed chips and cooking liquor at the top, while
pulp, along with spent cooking liquor, are continuously withdrawn to the
blow tank. Batch digesters consist of a series of vertical vessels. The
individual vessels are charged with chips, and cooking liquor is added.
The vessel is closed up and pressurized with live steam. The cooking
time will vary from 2 to 5 hours at a temperature of about 350ฐF and a
pressure of 100 to 125 psig. The cooking liquor is composed primarily
of a 12.5% solution of sodium sulf ide and caustic soda. It is often referred
to as white liquor because of its color.
4. When the operator determines that the cook is finished, he will reduce
the pressure to 80 psig by opening the blow valve on the bottom of the
vessel and allowing the pulp, along with the spent liquor, to be blown
to the blow tank. Blow tanks are vented to an accumulator.
5. The pulp is separated from the cooking liquor by filtration and washing.
6. The spent liquor (black liquor), now containing about 15% solids, is
transferred to the weak black liquor storage tank prior to the recovery of
12
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its chemical constituents for reuse in the digester.
7. The washed pulp passes to the screen room where slivers of uncooked
wood, and knots which failed to disintegrate, are separated from the pulp.
Knots removed in this step are sent to waste, but screenings are refined
and returned to the process.
8. If the pulp is to be bleached (by an agent which oxidizes and destroys
dyes which were formed from tannins present in the wood and intensified
by sulfides in the cooking liquor), it is done at this time.
9. After the pulp is bleached or prepared as desired and thickened, it is
sent to storage.
10. If the end product is pulp, "lapping" is performed on an endless felt
belt which carries pulp sheets through a series of squeeze and hot press
rolls. The resulting "laps", which contain approximately 40% air-dry fiber,
are subject to pressures up to 3000 psig. This pressure, exerted by
hydraulic presses, raises the air-dry fiber content to between 50 to 60%.
If the pulp is to be made directly into paper, the pulp from storage will
go through refining before it goes to the wet end of the paper machine.
The recovery and reuse of chemicals from the weak black liquor makes kraft
pulping economically feasible. The recovery system, in general, and the recovery
furnace, in particular, are the primary subjects of this narrative.
The weak black liquor removed from the pulp in the washer (Step 5) contains
about 96% of the alkali originally charged to the digester. Alkali is present as sodium
sulfate, salt, silica, and trace quantities of other inorganic compounds.
The recovery system portion of the process is shown schematically on Figure
1. It consists of the following steps.
11. The weak black liquor is pumped from storage to the multiple-effect
evaporators. These evaporators use steam to concentrate the liquor
to about 50% solids. There is no direct contact between the steam and
black liquor in these evaporators.
12. At this point, the liquor is concentrated to a solids content of at least 63%;
necessary for it to ignite and sustain combustion when sprayed into the
recovery furnace. This concentrated black liquor is termed "strong black
liquor". Several alternative schemes are used for the concentration step.
These are discussed in detail in the section entitled "Nature of the Gaseous
Discharge".
13
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/WWWVi
STRONG BLACK
LIQUOR STORAGE
AIR
PREHEATER
STEAM TO
PLANT
GAS CLEANING
DEVICE
WEAK BLACK LIQUOR
W
RECOVERY
FURNACE
RECOVERED LIQUOR
MULTIPLE EFFECT
EVAPORATOR
Figure I. Process flow diagram-block liquor recovery
14
-------
13. Strong black liquor is burned in the recovery furnace. Heat generated by
the combustion of organic constituents is used to generate steam in a
recovery boiler. This steam is returned to the plant and can be used
directly in the process or to generate electricity.
14. The solid smelt removed from the recovery furnace is dissolved in water
to form green liquor. This liquor is subjected to a causticizing treatment
with slaked lime, to convert sodium carbonate to sodium hydroxide.
15. Following Step 14, the causticized liquor, referred to as "white liquor",
is conveyed to a settling tank. Calcium carbonate sludge settles out in the
tank and the white liquor is further clarified by filters. The clarified liquor
is now ready for reuse as cooking liquor in the digester. The calcium
carbonate sludge is burned in a lime kiln where carbon dioxide is liberated
yielding calcium oxide or lime. This lime is reused in the causticizing of
green liquor as in Step 14. The subject of these lime kilns as an emission
source is covered in depth in a separate report entitled, "Air Pollution
Control Technology and Costs in Seven Selected Areas". This report was
prepared under EPA Contract No. 68-02-0289.
It is obvious from the preceding process description and flow diagram that the
recovery system is an important part of the whole process. The recovery steps
regenerate 95% of the chemicals used in addition to producing 10,000 Ib steam2
per ton of pulp produced. It is estimated2 that in 1960, the pulp industry in the United
States internally generated about 60% of the 30 billion Kw-hr of electrical energy
that it consumed that year.
THE RECOVERY FURNACE
In the recovery furnace, combustion of black liquor is effected by spraying the
atomized liquid onto the furnace walls. Spray nozzles are located on one furnace
wall and oscillate (and/or rotate) automatically such that the sheet spray covers
the remaining walls. The extent and frequency of oscillation is manually adjustable
over a wide range in order to compensate for changes in solids content of the
liquor. The adjustability permits optimization of the operation in terms of recovering
cooking chemicals, disposing of organic sulfur compounds, satisfying process steam
demand, and minimizing the quantity of objectionable emissions. In the lower portion
of the furnace, called the reduction zone, inorganic sodium sulfate and sodium
carbonate are reduced. These settle out in a smelt on the furnace grate. Organic
sulfur compounds are oxidized in the upper, or oxidizing, zone.
15
-------
Varying firing rates and steam demand affects the nature and quantity of
pollutants emitted. An inadequate supply of primary or secondary air results in
incomplete combustion giving rise to higher emission rates for carbon monoxide
and other unburned hydrocarbons. Gaseous, malodorous components of the flue gas
are hydrogen sulfide, mercaptans (particularly methyl mercaptan), dimethyl sulfide,
dimethyl disulfide, and other organic sulfides and disulfides.
The odor problem in the vicinity of kraft pulp mills is aggravated by the fact
that olfactory responses to gases mentioned in the preceding paragraph occur at
extremely low concentrations. Hydrogen sulfide, for example, characterized by the
smell of rotten eggs, has an odor threshold value in the parts per billion range. By
contrast, the odor threshold for ammonia is over 50 parts per million. Table 4 lists
ranges of odor threshold values for some of these gases along with their character-
istic odor3.
NATURE OF THE GASEOUS DISCHARGE
The nature of the gas discharged from the black liquor recovery system strongly
depends upon which of several alternative flow schemes is used. The conventional
scheme is the one shown in Figure 2. The black liquor is concentrated from 15%
to about 50% dissolved solids in a series of multiple effect evaporators. It is
then pumped from storage through the wet bottom of the precipitator, if used,
where the salt cake collected by the precipitator is deposited and dissolved
into the liquor. From this point, it goes to the chemical ash tank where it receives
the salt cake that accumulates in the hoppers under the boiler section of the
recovery boiler. From the chemical ash tank the liquor goes to a direct contact
evaporator. This evaporator may be either a cyclone or cascade type. In either case,
the liquor is in direct contact with the flue gases from the boiler. The flue gases
enter the evaporator at about 550ฐF, leave at about 300ฐF, and pick up enough
water from the liquor to concentrate it to 63%+ solids. From the evaporator, the
liquor goes to the salt cake mix tank where make-up salt cake is added as required
before it goes to the burner nozzles in the recovery furnace.
The conventional system has two sources of odor emission: the furnace and the
direct contact evaporator. If the furnace is operated properly at its design rating,
with sufficient combustion air, it should not be a significant source of odor6. The
tendency, however, is to run these furnaces well above capacity. Under these
conditions, emissions of odorous gases occur at a much higher rate, as illustrated
in Figure 31.
Odorous emissions occur at the direct contact evaporator due to chemical
reactions between components of the black liquor and the furnace flue gases.
16
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TABLE 4s
ODOROUS CHEMICALS EMITTED FROM KRAFT PULP MILLS
Gaseous Compound
Sulfur Dioxide
Hydrogen Sulfide
Methyl Mercaptan
Dimethyl Sulfide
Odor Threshold Range
ppm by Volume Characteristic Odor
1.0 to 5.0 Sharp, pungent
0.0009 to 0.0085 Rotten eggs
0.0006 to 0.040 Rotten cabbage
0.0001 to 0.0036 Vegetable sulfide
17
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I
ELEC.
PRECIP.
50V.
BLACK
LIQUOR
5TORAGI
i
FROM
MULTIPLE
EVAPORATORS
n a a
LIQUOR BURNERS
Figure 2. Flow diagram of conventional recovery furnace.
18
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Na2 S + 2H2O -* 2NaOH + H2S
Na2S + CO2 4- H2O -ป Na2C03 + H2S
Exhaust gases from recovery boilers using direct contact evaporators have been
reported to contain 70 to 1,500 ppm of H2S9 and constitute the principal source
of odor from recovery boilers not using oxidized black liquor8.
As well as concentrating the black liquor, the direct contact evaporator
performs an efficient job as a SO2 scrubber, and a limited and rather less
efficient job as a particle collector. Paniculate loadings from recovery boilers
having direct contact evaporators, not using venturi scrubbers, will range from
1.5 gr/ACF to 3.0 gr/ACF. Exit flue gas temperatures will range from 270ฐF
to 350ฐF.
Several alternative approaches to the conventional flow scheme have been
tried in order to reduce the emissions of odorous gases. Each of these schemes
has been aimed at impeding the mechanisms by which odorous gases are formed
in the direct contact evaporator.
Three different process schemes have been put forward to alter the chemistry
in the evaporator. The first of these is to precede the evaporator step with an
oxidation step.
Oxidation
The oxidation reaction converts Na2S to Na2S2Oa and, as a result, Na2S is
not available for hydrolysis or reaction with CO2, and H2S is therefore not formed.
Black liquor oxidization to the extent of 99% and higher is commercially feasible3.
The weak or strong black liquor, or both, may be oxidized. However, reverse
reactions yielding Na2S are possible and can impede overall effectiveness. Where
a low cost source of O2 is available, weak liquor oxidation can be done very
efficiently and with a minimum of capital equipment. Since foaming of the oxidized
black liquor in the recovery furnace is a problem with weak liquor, strong
liquor oxidation is used more often.
A block flow diagram of this process is presented in Figure 4.
ACE System
Another process which alters the chemistry in the evaporator uses an air
contact evaporator and is called the ACE system. A regenerative air heater replaces
the direct contact evaporator on the flue gas end of the boiler. The heated combustion
air from the air heater is then used to evaporate the water, and thus concentrate
19
-------
1000 r
JOO
s:
CL
Q-
0
i jju re 3 .
FURNACE LOADING
Re 1.'it ion between IbS production ;mcl furnace
-------
TO ATMOSPHERE
BLACK
LIQUOR
1*
1ULTIPLE
^
OXIDATION
I
EFFECT
EVAPORATORS
ซ
DIRECT
CONTACT
EVAPORATOR
COMBUSTION AIR
-ป
BLACK
LIQUOR
RECOVERY
FURNACE
SMELT
Figure 4. Black liquor recovery using oxidation, block flow diagram.
-------
the liquor for firing into the furnace, in a cascade type contact evaporator before
the air is directed to the wind boxes of the furnace. Since the COz in the flue gases
does not come in direct contact with the Na2S in the liquor, no H2S is formed.
This process, however, does not prevent the production of hfeS by the hydrolysis
route. A flow diagram is shown in Figure 5.
Since the flue gases from the boiler also pass through the small passages
of the air heater, there is a tendency for these passages to plug, and they must
be kept clean by soot blowing and periodic washing.
During at least part of the washing period, the air heater must be isolated from
the system by means of gates, to prevent water carry-over. These boilers have two
air heaters so that it is possible for the boiler to remain in service while one heater
is being washed.
Controlling the combustion of liquor presents some problems with this system,
due to the high moisture content of the combustion air, which results from the
evaporation of water from the liquor in the air cascade evaporator. The level of
SOa emission is generally higher than with the conventional system.
This system does not require black liquor oxidation to control H2S emission,
nor does it require a black liquor concentrator following the multiple effect evaporators.
The particulate loadings from this type of recovery boiler system will range
from 2.5 gr/ACF to 4.5 gr/ACF. The salt cake collected in the precipitator appears
to be more sticky than that found in other systems. Exit flue gas temperature
will range from 325ฐF to 400ฐF.
LAH System
The Laminaire air heater (LAH) type of boiler arrangement is similar to the
ACE system since it utilizes regenerative air heaters. However, it does not have
an air contact evaporator. A flow diagram is shown in Figure 6. With the exception
of the furnace, which is designed to burn black liquor, the boiler arrangement
is very much like most utility boilers. Means are provided for washing one of the
two air heaters while the boiler remains in service.
Since a contact evaporator is not used, the liquor from the multiple effect
evaporators must be further concentrated to about 63% solids in a steam concen-
trator, before it can be fired in the furnace.
Paniculate loading will range from 3.0 to 4.5 gr/ACF. Flue gas temperatures
generally will range from 350ฐF to 400ฐF. Flue gas volumes, as with the ACE system,
will average higher than with other systems due to the leakage in the air heater.
Seals must be maintained in order to keep this leakage at a minimum.
22
-------
BLACK
LIQUOR
STORAGE
65% BLACK.IQUOR
FROM
MULTIPLE
EVAPORATORS
Figure 5. Flow diagram of air contact evaporation system.
23
-------
50%
BLACK
LIQUOR
STORAGE
ฃ8 63% BLACK LIQUOR
k.
v:
>-
LiJ
>
DISSOLVING
TANK
FROM MULTIPLE
EVAPORATORS
TO
CAUSTICIZER
Figure 6. Flow diagram of Laminaire air heater system.
-------
Large Economizer
The large economizer boiler arrangement does not utilize a contact evaporator
and therefore the liquor must be concentrated before firing, as with the LAH
arrangement. This has been achieved by designing the multiple effect evaporators
to produce 60 to 63% solids content product and recovering available furnace heat
from the flue gases with a large economizer. A flow diagram of this arrangement
is shown in Figure 7. The size and configuration of the economizer will depend
upon the desired feed water temperature and flue gas temperature requirement.
Since there is a tendency for the economizer to plug, soot-blower steam
requirements are considerable and account for the higher than expected water vapor
in the flue gas along with its volume. Paniculate loading will range from 3.0 to as
high as 6.0 gr/ACF, with exhaust temperatures from 350ฐF to 450ฐF. Grain loading,
as well as temperature, tend to cycle with the cleanliness in the economizer. As
the economizer becomes dirty, the exit gas temperature will go up. The grain
loading in the flue gas will sharply increase when the blower cycle begins.
NATURE OF THE PARTICULATE EMISSION
Particulate emissions from a kraft recovery furnace are characterized by a
high sodium content. A small percentage of these particles may be as large as
10 microns in diameter but, generally, they will be smaller than 1 micron.
t
Most of the salt cake fired into the furnace with the black liquor is reduced to
sodium sulfide and is removed from the furnace as smelt. A portion of the salt
cake volatilizes and passes through the boiler where it condenses on cooler surfaces
or in cooler gases. Particulates formed in this manner are extremely small in size,
generally below one micron.
The control of air to the furnace is very important. Excess air in the reduction
zone will oxidize carbon directly to carbon dioxide, destroying its ability to reduce
salt cake to sodium sulfide. If excess air is reduced, the concentration of sodium
carbonate in the carry-over will increase. The condition of the smelt bed and its
temperature will also have an effect on the paniculate matter as well as the gases
emitted.
Some of the salt cake will collect in the generating tube, superheater tube,
and economizer tube sections of the boiler. This is removed by automatic soot
blowers and in some cases lancing. Much of this is reentrained in the gas
stream and leaves the boiler with the flue gases. The remainder is collected
in hoppers under the economizer and returned to the chemical ash tank where it
is put back into the black liquor. Since the bulk density of the salt cake leaving
25
-------
Q
ELEC--
PREaPITATOR
50%
BLACK LIQUOR
STORAGE
DISSOLVING
TANK
FROM MULTIPLE
EVAPORATORS
TO
CAUSTICIZER
Figure 7. Flow diagram of large economizer system.
26
-------
the boiler is well below 10 Ibs/cu/ft, it is very easily reentrained.
The quantities of participates emitted, including sodium sulfate, sodium
carbonate, and unburned carbon will be in the range of 90 to 275 pounds per air
dried ton (ADT) of pulp produced by the plant. A nominal average emission rate
of 150 lb/(ADT)2.4 is used for estimating purposes. This loss of chemical is
not only an economic problem to the plant (sodium sulfate lost must be replaced
in the process) but is also an air pollution nuisance.
POLLUTION CONTROL CONSIDERATIONS
Early methods of reducing participate emission consisted of filters, using wetted
wood chips and cyclone type mechanical collectors. Later, these were replaced
with electrostatic precipitators and wet scrubbers, both capable of 90% collecting
efficiency. Precipitators were capable of still higher efficiency, but the increased
efficiency above 90% could not be economically justified. At this efficiency, and
assuming the uncontrolled plant would emit 150 Ib of salt cake per (ADT) of pulp
produced, there would be a net reclamation of 135 Ib of salt cake. Using a delivered
cost of salt cake of $0.015/lb, the reclaimed chemicals produce a savings of over
$2.00 per (ADT).
Scrubbers are no longer employed as a primary collector. The scrubbers
used were high energy venturi types using black liquor as the scrubbing media
which provided a means of heat recovery. The black liquor was concentrated by
evaporation as it cooled the flue gas to about 180ฐF. The black liquor, used as
scrubbing media, however, was in direct contact with the flue gases and became
another source for odor pick-up. Foaming is also a problem.
Scrubbing is effective in the removal of both paniculate and gaseous emissions,
particularly SO2 where black liquor is used. The overall thermal efficiency of a
furnace equipped with a venturi-evaporative scrubber is considerably higher than
a comparable furnace employing an electrostatic precipitator since the final discharge
gas temperature is 120ฐF lower in the former case. In order to obtain the 90%
collecting efficiency, the pressure drop across the venturi has to be maintained at
about 40 in.wc.
Low energy water scrubbers are being currently used following some precipita-
tors to collect agglomerates which have been re-entrained. These agglomerates are
large particles, or flakes of salt cake, which are relatively flat, presenting a high sail
area for re-entrainment after initial collection. The emission of these re-entrained
particles is known as "snowing". In some cases, where the scrubber is not actually
provided as part of a new emission control system, provisions are made for future
addition of these scrubbers.
27
-------
Today, precipitators are the sole device being purchased for the control of
participate emission from recovery boiler gases. Recently installed units and those
currently contemplated are all designed at efficiencies ranging from 99.5% to 99.9%.
Boilers without contact evaporators generally have a slightly higher inlet dust
loading and, therefore, the precipitator should be designed for a higher efficiency in
order to yield the same residual. All of the precipitators have steel shells and are
well insulated. In some instances, auxiliary heat is supplied between the insulation
and the shell. Each unit is designed with many bus sections and always has two or
more chambers. Electronic automatic controls maintain the operating level, so little
or no attention is required of the plant operators.
Although there are now no commercial kraft installations employing
fabric filters, the economics of this abatement method are becoming more attractive.
There is ongoing pilot plant work on kraft mill fabric filters and it is expected that a
prototype will be built soon.
SPECIFICATIONS AND COSTS
Equipment specifications were written for electrostatic precipitators applied to
both conventional and controlled odor (large economizer) type recovery boilers.
Each specification requested costs for both medium and high efficiency performance
precipitators applied to a small (500 ADT/day of pulp) and a large (1,500 ADT/day
pulp) recovery boiler. Medium efficiency was specified at a residual of 1.7 Ib. of
emission/ADT.* High efficiency was specified at 0.02 gr/DSCF. These specifications
are shown in Tables 5, 6, 9, 10, 11, and 12.
Two sets of specifications were written for the controlled odor boiler cases:
one specifying a roof location for the precipitator, the other specifying a ground
location. Some of the bidders reported no difference in capital cost between the two
systems. Other bidders reported differences as summarized below.
Additional Cost for Ground Location
Boiler Size Dollars % of Total Capital Cost
Small $21OM 11
Large $640 M 14
*While the paper industry and old pollution control codes quantify emissions in
terms of Ibs/ADT, equipment manufacturers use gr/ACF.
28
-------
As can be seen, the costs are greater for the ground locations. The ground
locations cost the same amount more than the roof locations for both the medium
and high efficiency precipitators since the increased cost is due solely to the
additional structural steal and ductwork required for the ground location.
Cost data are presented for the conventional boiler in Tables 7 and 8 and in
Figures 8, 9, 10, and 11. Cost data are presented for the controlled odor boiler
(ground location) in Tables 9 and 10 and in Figures 12, 13, 14, and 15. Average
drift velocities used to size the precipitators are summarized below.
Drift Velocity
cm/sec ft/sec
Conventional Boilers 7 to 8 0.23 to 0.26
Controlled Odor Boiler 5.51 to 6.5 0.18 to 0.21
The lower drift velocities in the controlled odor precipitators are due to lower particle
density and size from the controlled odor boilers. The specifications for both types of
boilers required that provision be made for a low energy "anti-snow" scrubber to be
installed potentially at a later date. One precipitator bidder was asked to supply the
cost of the scrubber that would be installed, should it be required. Those installed
scrubber costs are estimated to be:
Small Plant (Med. and High Eff.) $146,000
Large Plant (Med. and High Eff.) $498,750
29
-------
TABLE 5
ELECTROSTATIC PRECIPITATOR PROCESS DESCRIPTION
FOR CONVENTIONAL KRAFT PULP MILL RECOVERY FURNACE SPECIFICATION
A wet bottom electrostatic precipltator Is to remove solids from the effluent gas from a
new, conventional recovery furnace.
The system shall be quoted complete including all of the following:
1. Inlet ductwork and inlet plenum.
2. Wet bottom electrostatic precipitator and liquor handling equipment.
3. Outlet ductwork and 100 foot stack.
4. Dampers, slide gates and pressure control system. The draft fan will be considered
part of the boiler and will be supplied by others.
5. Other necessary auxiliary equipment.
6. Electrical installation work including only low voltage wiring.
The precipitator is to continually reduce the solids content of the flue gas to the levels
specified.
1. Inlet Ductwork and Inlet Plenum
The outlet ductwork of the boiler will be extended through the roof by the boiler manu-
facturer and be available for connection to the inlet plenum of the precipitator. The
inlet plenum will be specified.
2. Precipitator
The precipitator shall be a wet bottom, single stage, plate type unit with a minimum
of two fields in the direction of gas flow for the intermediate efficiency case and three
fields for the high efficiency case. Inlet face velocity shall not exceed 5 FPS and 4 FPS,
respectively.
The precipitator shall be divided into two gas-tight chambers. Dampers or similar flow
balancing devices shall be furnished for each chamber. Each chamber will have slide
gates at inlet and outlet, so that one chamber may be isolated for repairs while the
other chamber remains operative. A heated pressurized penthouse design should be
employed. Shell heating is not required.
The precipitator will be located on the roof of the recovery boiler building.
The wet bottom shall be capable of holding a minimum depth of one foot of black
liquor. Agitators will cover a minimum of 50% of the bottom area and will continuously
mix deposited salt cake into the black liquor. One black liquor feed connection, one
30
-------
overflow connection, one emergency overflow, three inch Instrument flanged connection,
and one drain connection will be provided. Black liquor handling to and from the
precipitator will be supplied by others. The black liquor coming to the preclpitator wet
bottom will normally contain ซs67 wt% solid.
Electrical power at 460v, 3 phase, 60 cycle; and 110v, 1 phase, 60 cycle is available
in sufficient quantity at the site. Automatic voltage controls shall be provided for each
field. A safety interlock system shall be provided so that no access to high voltage
equipment is possible without first de-energizing all fields.
Equipment shall be provided for continuous removal of the solids recovered in the liquor.
Storage equipment will have a capacity sufficient for 24 hours of continuous operation,
and will be supplied by the purchaser.
3. Outlet Ductwork and Stack
The cleaned gases will be conveyed to the atmosphere by the outlet ductwork and
stack, located on the roof. The outlet ductwork will be the equivalent of 150 linear
feet and will have provisions for the addition of a wet scrubber at a later time.
4. Fans, Dampers, and Pressure Control System
A tan of sufficient size to overcome the pressure drop of the precipitator system, including
possible future secondary wet scrubber, will be supplied by the boiler manufacturer.
Appropriate dampers shall be placed so as to control the flow of gas as described in
Section #2.
The material of construction of all parts of the system shall be mild steel.
A model study for the precipitator gas distribution system will not be required.
31
-------
TABLE 6
ELECTROSTATIC PRECIPITATOR OPERATING CONDITIONS
FOR CONVENTIONAL KRAFT PULP MILL
RECOVERY FURNACE SPECIFICATION
Plant Capacity, ADTIday
Precipitator Inlet Conditions
Gas Rate, ACFM
Temperature, ฐF
Gas Rate, SCFM
Moisture Content, vol%
Gas Rate, DSCFM
Inlet Loading
grIACF
grIDSCF
Iblhr
Precipitator Outlet Conditions
Gas Rate, ACFM
Temperature, ฐF
Gas Rate, SCFM
Moisture Content, vo/%
Gas Rate, DSCFM
Residual, Med. Eff. Case
grIACF
gr/DSCF
Iblhr
Collection Efficiency, %
Residual, High Eff. Case
grIACF
grIDSCF
Iblhr
Collection Efficiency, %
265,300
350
173,600
30
121,500
2.0
4.4
4,549
265,300
350
173,600
30
121,500
0.016
.035
36
99.2
0.009
0.02
20.8
99.6
795,900
350
520,800
30
364,500
2.0
4.4
13,647
795,900
350
520.800
30
364,500
0.016
.035
109
99.2
0.009
0.02
62.4
99.6
32
-------
TABLE 7
ESTIMATED CAPITAL COST DATA (COST IN DOLLARS)
FOR ELECTROSTATIC PRECIPITATORS FOR KRAFT PULP MILL
CONVENTIONAL RECOVERY FURNACE
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
gr/ACF
Ib/hr
Cleaning Efficiency, %
( 1 } Gas Cleaning Device Cost
(2) Auxiliaries Cost "1
(a) Fan(s)
(b) Pump(s)
(c) Damper(s) I
(d) Conditioning,/
Equipment
(e) Dust Disposal
Equipment
J
(3) Installation Cost "N
(a) Engineering
(b) Foundations
& Support
Ductwork
Stack
Electrical
Piping >
Insulation
Painting
Supervision
Startup
Performance Test
Other
(4) Total Cost
Medium Efficiency
Small
265,300
350
173,600
30
2.0
4,549
265,300
350
173,600
30
.016
36
99.2
469,367
55,973 '
677,390
1,202,730
Large
795,900
350
520,800
30
2.0
13,647
795,900
350
520,800
30
.016
109
99.2
1,097,288
112,350
1,316,453
2,526,092
High Efficiency
Small
265,300
350
173,600
30
2.0
2,549
265,300
350
173,600
30
.009
20.8
99.6
534,121
73,334
729,157
1,336,613
Large
795,900
350
520,800
30
2.0
13,647
795,900
350
520,800
30
.009
62.4
99.6
1,372,041
133,744
1,539,262
3,045,047
33
-------
TABLE 8
ANNUAL OPERATING COST DATA (COST IN S/YEAR)
FOR ELECTROSTATIC PRECIPITATORS FOR KRAFT PULP MILL
CONVENTIONAL RECOVERY FURNACE
Operating Cost Item
Operating Factor, Hr/Year-8600
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/mh
$8/mh
$6/mh
$0.011 kwh
16% of Cap
Medium Efficiency
Small
3,240
1,440
4,680
1,920
67
1,987
9,200
9,200
42,100
42,100
57,967
192,437
250,404
Large
3,240
1,440
4,680
2,580
100
2,680
14,825
14,825
113,400
113,400
135,585
404,175
539,760
High Efficiency
Small
3,240
1,440
4,680
1,920
67
1,987
9,200
9,200
45,800
45,800
61,667
213,858
275,525
Large
3,240
1,440
4,680
2,580
100
2,680
14,825
14,825
i
i
123,700
123,700
145,885
487,208
-633,093
-------
FIGURE 8
CAPITAL COST OF ELECTROSTATIC PRECIPITATORS
FOR KRAFT MILL CONVENTIONAL RECOVERY FURNACE
(MEDIUM EFFICIENCY)
6
5
A
TURNKEY SYSTEM
I06
9
8
fc" I
8 6
COLLECTOR PLUS AUXILIARIES
COLLECTOR ONLY
I05
I05
3 4 5 6 7 8 9 ICT
CLEANED GAS FLOW, ACFM
35
-------
FIGURE 9
ANNUAL COST OF ELECTROSTATIC PRECIPITATORS
FOR KRAFT PULP MILL CONVENTIONAL RECOVERY FURNACE
(MEDIUM EFFICIENCY)
\
te
o
o
t>
5
4
3
2
I05
9
8
7
6
5
4
3
Z
I04
1C
X
-.S
S
x
X
x"
x^
/
/
X
X
X
^
>
^
<
TOTAL ANNUAL COST
X
TOTAL DIRECT COS
T
i
!
)5 2 3456789 I06 2. 34
CLEANED GAS FLOW, ACFM
36
-------
FIGURE 10
6
5
4
CAPITAL COST ฉF ELECTROSTATIC PRECIPITATORS
KRAFT PULP MILL CONVENTIONAL RECOVERY FURNACE
(HIGH EFFICIENCY)
TURNKEY SYSTEM
2
X
COLLECTOR PLUS AUXILIARIES
COLLECTOR ONLY
8
7
5
4
3
S*'
I05
K)5
2 3 4 5 6789 I06
CLEANED GAS FLOW, ACFM
37
-------
FIGURE 11
ANNUAL COST OF ELECTROSTATIC PRECIPITATORS
FOR KRAFT PULP MILL CONVENTIONAL RECOVERY FURNACE
(HIGH EFFICIENCY)
6
5
4
3
2
-I I05
Q 9
" 8
Is 7
8 6
5
4
3
2
I04
K
X
a'
X^
y
S
>
r
S
r
X
>
w
*
tr
J TOTAL ANNUAL COST
-
{
'
TOTAL DIRECT CO!
T
- -
)5 2 3456789 I06 2 34
CLEANED GAS FLOW, ACFM
38
-------
TABLE 9
ELECTROSTATIC PRECIPITATOR PROCESS DESCRIPTION
FOR KRAFT PULP MILL CONTROLLED ODOR RECOVERY FURNACE SPECIFICATION
A dry bottom electrostatic precipitator is to remove solids from the effluent flue gas from
a controlled odor recovery furnace.
The system shall be quoted complete including all of the following:
1. Inlet ductwork and inlet plenum.
2. Dry bottom electrostatic precipitator.
3. Outlet ductwork and 100 foot stack.
4. Dampers, slide gates and pressure control system. The draft fan will be considered
part of the boiler and will be supplied by others.
5. Other necessary auxiliary equipment.
6. Electrical installation work including only low voltage wiring.
The precipitator is to continually reduce the solids content of the flue gas to the levels
specified.
1. Inlet Ductwork and Inlet Plenum
The outlet ductwork of the boiler will be extended through the roof by the boiler manu-
facturer and be available for connection to the inlet plenum of the precipitator. The
inlet plenum will be specified.
2. Precipitator
The precipitator shall be a wet bottom, single stage, plate type unit with a minimum
of two fields in the direction of gas flow for the intermediate efficiency case and three
fields for the high efficiency case. Inlet face velocity shall not exceed 4Vi FPS and 4 FPS,
respectively.
The precipitator shall be divided into two gas-tight chambers. Dampers or similar flow
balancing devices shall be furnished for each chamber. Each chamber will have slide
gates at inlet and outlet, so that one chamber may be isolated for repairs while the
other chamber remains operative. A heated pressurized penthouse design should be
employed. Shell heating is not required.
The precipitator will be located at ground level adjacent to the recovery boiler building.
Electrical power at 460v, 3 phase, 60 cycle; and 110v, 1 phase, 60 cycle is available
in sufficient quantity at the site. Automatic voltage controls shall be provided for each
field. A safety system shall be provided so that no access to high voltage equipment
is possible without first de-energizing all fields.
39
-------
Equipment shall be provided for continuous removal of the solids recovered in the liquor.
Storage equipment will have a capacity sufficient for 24 hours of continuous operation,
and will be supplied by the purchaser.
3. Outlet Ductwork and Stack
The cleaned gases will be conveyed to the atmosphere by the outlet ductwork and a
stack located on the ground. The ductwork shall be the equivalent of 300 linear feet
and will have provision for attachment of a secondary wet scrubber.
4. Fans, Dampers, and Pressure Control System
A fan of sufficient size to overcome the pressure drop of the precipitator system, including
possible future secondary wet scrubber, will be supplied by the boiler manufacturer.
Appropriate dampers shall be placed so as to control the flow of gas as described in
Section #2.
The material of construction of all parts of the system shall be mild steel.
A model study for the precipitator gas distribution system will not be required.
40
-------
TABLE 10
ELECTROSTATIC PRECIPITATOR OPERATING CONDITIONS
FOR KRAFT PULP MILL CONTROLLED ODOR
RECOVERY FURNACE SPECIFICATION
Plant Capacity, ADT/day
Precipitator Inlet Conditions
Gas Rate, ACFM
Temperature, ฐF
Gas Rate, SCFM
Moisture Content, vol%
Gas Rate, DSCFM
Inlet Loading
gr/ACF
gr/DSCF
Ib/hr
Precipitator Outlet Conditions
Gas Rate, ACFM
Temperature, ฐF
Gas Rate, SCFM
Moisture Content, vol%
Gas Rate, DSCFM
Residual, Med. EH. Case
gr/ACF
gr/DSCF
Ib/hr
Collection Efficiency, %
Residual, High EH. Case
gr/ACF
gr/DSCF
Ib/hr
Collection Efficiency, %
260,200
425
155,800
22
121,500
4.0
8.6
8,920
260,200
425
155,800
22
121,500
0.016
0.080
36
99.6
0.009
0.02
20.8
99.8
Large
1,500
780,600
425
467,400
22
364,500
4.0
8.6
26,760
780,600
425
467,400
22
364,500
0.016
0.080
107
99.6
0.009
0.02
62.4
99.8
41
-------
TABLE 11
ESTIMATED CAPITAL COST DATA (COST IN DOLLARS)
FOR ELECTROSTATIC PRECIPITATORS FOR KRAFT PULP MILL
CONTROLLED ODOR RECOVERY FURNACE
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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
260,000
425
155,800
22
4.0
8,920
260,200
425
155,800
22
.016
36
99.6
588,726
94,065
39,106
863,120
1,545,911
Large
780,600
425
467,400
22
4.0
26,760
780,600
425
467,400
22
.016
107
99.6
1,374,257
213,764
103,717
1,936,340
3,524,361
High Efficiency
Small
260,200
425
155,800
22
4.0
8,920
260,200
425
155,800
22
.009
20.8
99.8
704,551
98,909
39,106
943,358
1,746,818
Large
780,600
425
467,400
22
4.0
26,760
780,600
425
467,400
22
.009
62.4
99.8
1,713,660
227,347
103,717
2,172,809
4,113,816
42
-------
TABLE 12
ANNUAL OPERATING COST DATA (COST IN $/YEAR)
FOR ELECTROSTATIC PRECIPITATORS FOR KRAFT PULP MILL
CONTROLLED ODOR RECOVERY FURNACE
Operating Cost Item
Operating Factor, Hr/Year-8600
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/mh
$8/mh
$6/mh
$0.011/kwh
16% of Cap
Medium Efficiency
Small
3,240
1,440
4,680
1,920
67
1,987
9,400
9,400
45,800
45,800
61,867
247,346
309,213
Large
3,240
1,440
4,680
2,580
100
2,680
12,350
12,350
125,600
125,600
145,310
563,898
709,208
High Efficiency
Small
3,240
1,440
4,680
1,920
67
1,987
9,500
9,500
46,400
46,400
62,567
279,491
342,058
Large
3,240
1,440
4,680
2,580
100
2,680
13,250
13,250
127,900
127,900
148,510
658,211
806,721
-------
FIGURE 12
CAPITAL COST OF ELECTROSTATIC PRECIPITATORS
FOR KRAFT PULP MILL CONTROLLED ODOR RECOVERY FURNACE
(MEDIUM EFRCIENCY)
D
5
4
3
2
2 io6
O 9
8
* I
8 6
5
4
3
2
IO5
X
^
Ofs
s^
/
/
'y
r
/
/<
/
/
/
^
^
^
/
j
/
x
<<
TURNKEY SYSTEM
COLLECTOR PLUS
COLLECTOR ONLY
AUXIUARIE
S
K)5
3 4 5 6 7 8 9 I06
CLEANED GAS FLOW, ACFM
44
-------
ANNUAL COST OF ELECTROSTATIC PRECIPITATORS
FOB KRAFT PULP MILL CONTROLLED ODOR RECOVERY FURNACE
(MEDIUM EFFICIENCY)
6
5
4
3
2
-| I05
^ 1
rฐ 7
u 6
5
4
3
2
I04
^/
X*
V
j^r
X
X
s
X
X
>x
^
/
/
,
3_
TOTAL ANNUAL COST
i
&
s
/
TOTAL DIRECT CO
IT
3 4 5 6 7 8 9 10ฐ
CLEANED GAS FLOW, ACFM
45
-------
RGURE14
CAPITAL COST OF ELECTROSTATIC PRECIPITATORS
FOR KRAFT PULP MILL CONTROLLED ODOR RECOVERY FURNACE
(HIGH EFFICIENCY)
D
U Q
o
r> fi
8 6
5
I05
X
,/
jiSf
/s
^^
>
_^yr
/^
^
r
s
$
G
r
&
$
{
'
/
/
- TURNKEY SYSTEM
COLLECTOR PLUS
COLLECTOR ONLY
AUXILJARIE
S
3456789 I06
CLEANED GAS FLOW, ACFM
46
-------
FIGURE 15
ANNUAL COST OF ELECTROSTATIC PRECIPITATORS
FOR KRAFT PULP MILL CONTROLLED ODOR RECOVERY FURNACE
(HIGH EFFICIENCY)
D
5
4
3
2
-| I05
Q 9
2 8
ฃ 7
O 6
5
4
3
2
10*
rS
S
X
X
>
x
/
ซ
x
^
1^
Y
^
I
^/
ป
X
>
'
^
0
f1"
/
A
W
'
s
TOTAL DIRECT CO
TOTAL ANNUAL CO
ST
ST
I05
I06
3456789 10*
CLEANED GAS FLOW, ACFM
I05
47
-------
REFERENCES
1. Stem, Arthur C., Air Pollution, Volume III, Sources of Air Pollution and Their
Control, 2nd Edition, Academic Press, New York, 1968.
2. Steam, Its Generation and Use, 37th Edition, The Babcock and Wilcox
Company, New York, 1963.
3. Hendrickson, E. R., J. E. Robertson and J. B. Koogler, Control of Atmospheric
Emissions in the Wood Pulping Industry, Final Report. Contract No. CPA
22-69-18, March 15, 1970.
4. Shreve, Norris R., The Chemical Process Industries. Chapter 33, McGraw-Hill,
New York, 1956.
5. An Economic Comparison of Precipitators and Bag Filters for Particulate
Emission Control on Kraft Recovery Furnaces. Atmospheric Quality
Improvement Tech. Bulletin No. 57, National Council of the Paper Industry
for Air and Stream Improvement, New York, Jan. 31, 1972.
6. Field Operations and Enforcement Manual for Air Pollution Control, Vol. Ill,
Inspection Procedures for Specific Industries, U. S. Environmental Protection
Agency, OAP, August 1972.
7. Scrubber Handbook, Vol. 1, Prepared for Control Systems Div., Office of Air
Programs, Environmental Protection Agency, Contract No. CPA-70-95,
August 1972.
8. Canovali, L. L, and Suda, S., "Case History of Selection and Installation of
a Kraft Recovery Odor-Reduction System," TAPPI, Vol. 53, No. 8, August
1970. pp. 1488-1493.
9. Gommi. J. V., "Reduced-Odor Recovery Units," TAPPI. Vol. 55, No. 7, July
1972, pp. 1094-1096.
48
-------
2. FERROALLOY FURNACES
Ferroalloy is the term given to alloys of iron and non-ferrous metals such as
silicon, chromium, and phosphorus. Ferroalloys are primarily used as alloying
agents and deoxidants in the production of stainless steel, carbon steel and cast iron.
In the United States, most ferroalloys are produced in either blast or electric furnaces.
Blast furnaces have a lower operating cost but are limited to the production of
ferroalloys with high carbon and low nonferrous metal content. Typical ferroalloys
produced in blast furnaces are Spiegeleisen, ferromanganese, ferrosilicon, ferro-
chrome, and ferrophosphorus. Electric furnaces have higher operating costs but
are required for the production of low carbon, high nonferrous metal content alloys.
For example, ferrosilicon from a blast furnace is limited to 17% silicon. Its carbon
content would be approximately 1.5%. Electric furnaces can produce ferrosilicon of
over 85% silicon and less than 0.15% carbon. Typical ferroalloy compositions are
listed in Table 13.
Since more than 80% of the domestic production of ferroalloys is performed
in electric furnaces1 the remainder of the narrative will deal with this type of furnace.
Most electric furnaces used in the ferroalloy industry are of the submerged arc
type. They differ from the standard electric furnace used in steelmaking in that the
majority of the electrical energy is used to promote a chemical reaction. There are
generally three or six carbon electrodes. The electrodes are submerged into the
melt half way between the hearth and the slag at the top. Figure 16 shows a
typical submerged arc furnace. Energy requirements are high. Depending on the
type of ferroalloy being produced, energy requirements2 can vary from 1 to 6
kwh/lb. Furnace sizes range3 from a few hundred to 50,000 kw.
Most ferroalloys such as ferromanganese, high carbon ferrochrome, and
ferrosilicon are produced via a one-step process in a submerged arc electric
furnace.4i s<6 Other ferroalloys require further treatment after being tapped from
the furnace. For example, molten high carbon ferrochrome is treated with oxygen
to produce medium carbon ferrochrome.6 Low carbon ferrochrome is produced
via a multiple step process.6 This process incorporates a slag furnace, an alloy
furnace, a ladle, and two reaction vessels.
In the submerged arc electric furnace, raw materials are continuously fed
into the top of the furnace. The raw materials consist of iron and nonferrous
metal ores, reducing agents and fluxes. Typical reducing agents are coke, coal,
coke fines, wood chips, and ferrosilicon alloys. At high temperatures, up to 2000ฐC,
a reduction reaction occurs between the metal oxides and the reducing agents.
The products of the reaction are molten alloy and carbon monoxide. The molten
49
-------
Ul
o
TABLE 13
COMPOSITIONS OF TYPICAL FERROALLOYS
ALLOY TYPE
Ferromanganese (Std.)
Ferromanganese (L.C.)
Ferrosilicon
Ferrochromium (H.C.)
Ferrochromium (L.C.)
Ferrovanadium
Silicomanganese
Ferrotitanium
Spiegeleisen
Silvery Iron
wt.%
C Mn
7.5* 80
0.1-0.75 83
0.15*
6
0.03-2.0
3.5*
65
4
6.5* 17
1.5*
P
0.35*
0.35
0.05*
0.25*
0.25*
0.15*
S
0.05*
0.05
0.04*
0.40*
0.05*
0.06*
Si V Cr
1.25*
1.25
50
3* 73
1.5* 73
13* 35
20
2.5
1.0-4.0
17
Ti Al
1.5*
20 1.5
'Maximum
-------
PLAN
*"** '*.*' >ป"ซ*ซ'Vปi'.ซ'''ป.
^ " * .*?.:. ''-1'
*
SECTION
(oS ELECTRODES. (f) FLEXIBLE CONNECTORS.
(b) ELECTRODE HOLDERS (g) CABLES TO COUNTERBALANCES.
U) CAJIBON HEARTH (h) TAP HOLE
(d) CHARGE ( j) PLATFORM
() BUSBARS (Z) CAR
Figure 16..Electric furnace for ferroalloy production
51
-------
alloy settles to the hearth. Here, it is tapped at one to five hour intervals. The
carbon monoxide is the major gaseous emission from the melt. The basic overall
reactions are listed in Table 14. The nonreduced constituents of the metal ores,
known as slag, remain at the top of the melt. The slag is either discarded or is
further processed.
Submerged arc furnaces can further be classified as open or closed according
to the method of fume capture. Open hood furnaces allow the burning of carbon
monoxide over the melt. This type of capture offers the advantage of easy access
to the furnace for stoking and addition of raw material. Its chief disadvantage is
the production of large volumes of gases. Closed hood furnaces collect only the
fumes emitted directly from the melt. Their chief advantages are a low rate of gas
flow into the subsequent pollution abatement equipment, and the potential for
carbon monoxide recovery. The major disadvantages are the inaccessability of the
furnace for stoking, the problems involved in creating a good seal, and the disposal
of carbon monoxide from the abatement equipment. The numbers of closed and
open hood furnaces in the U.S.A. are listed in Table 152.
Figures 17 and 18 show two types of closed hood furnaces. The completely
' sealed furnace has been used in Europe, Canada, and Japan.* Here, a mechanical
seal is used around the electrode to prevent escape of gases. In this type of design
all the off-gases are collected. There is no leakage into the room. The major
problems are reliability of the mechanical seal and maintenance of sufficient mix
height in the raw material additions ports (mix spouts) to preserve the seal.
The covered furnace is more common in the United States. Raw materials
are fed around the electrodes thus creating the seal. This type of hood is reasonably
simple. From 65% to 98% of the gaseous emissions are captured. The major
disadvantage results from the gases which are not captured. Gases leak from
around the electrodes and burn. The flames create further pollution and maintenance
problems.
Control of emissions from open hood submerged arc electric ferroalloy furnaces7
by fabric filters and wet scrubbers was dealt with under a prior EPA contract,
No. 68-02-0301. In this narrative, additional cases of control of open hood emissions
by fabric filters will be considered.
'There is one such unit in the United States, as well.
52
-------
TABLE 14
BASIC OVERALL REACTIONS FOR FERROALLOY PRODUCTION
Ore Reducing Electrical Molten Furnace
Constituents Agents Energy Alloy Gas
Cr203 + 3C -* 2Cr + 3CO
MnO + C -ป Mn CO
Si02 + 2C -* Si 2CO
Fe203 + 2C -ป 2Fe 3CO
AI203
CaO
Mg02 Slag
Si02
53
-------
TABLE 15
DISTRIBUTION OF DOMESTIC FERROALLOY FURNACES
Furnace Type Number in Use % of Total
Submerged Arc - Open Hood 100-150 71-76
Submerged Arc - Closed Hood 30-35 21-18
Open Arc 12 8-6
54
-------
ELECTRODE
Whn./"1ป_
COVERs
TAP _.
HOLE C
M
FE
t
i
1)
IE
I
ซ
\ELE
V
^
V
.CTRC
a M
1 FE
*
-
)C
i;
.E
i
cs
<
D
-(
^
4
w
W
1)
:i
^
<
:D
^
X
FURNACE
GAS OFFTAKE
/
&
Figure 17. Sealed furnace for producing
ferroalloys.
55
-------
ELECTRODES
RAW MAT
FEED ARO
ELECTROC
COVER^
TAP .-
HOLEC
'L
UND
)ES v
m
m
1
\ซ
II
i.
rf X,
7 *
FURNAC
i
i
i
Ui
E
^
GAS OFFTAKE
Figure 18. Covered furnace for producing
ferroalloys.
56
-------
NATURE OF THE GASEOUS DISCHARGE
Carbon monoxide is the major by-product of ferroalloy production. The weight
of CO emitted from the melt can exceed the weight of alloy produced. For example,
Table 16 shows a weight balance for production of 45% ferrosilicon. The amount
of carbon monoxide emitted is 2.12 tons for every 2 tons of ferroalloy produced8.
The amount of gaseous emissions from closed and open furnaces is quite
different. The volume can be as much as 50 times greater with the open hood. For
example, Table 17 shows a comparison of open and closed furnaces for the pro-
duction of 50% ferrosilicon. In this example, the difference in gas flow rate was
a factor of 26.
Only two and one-half volumes of air are needed to convert one volume of
carbon monoxide to carbon dioxide. The remainder of the excess air used with
the open hood design is required for adequate ventilation around the hood to
prevent leakage of fumes into the room.
Other components of the gaseous discharge include hydrogen and volatile
hydrocarbon. The volatile hydrocarbon comes from the electrodes and from oil on
the surface of the steel shavings.
NATURE OF THE PARTICULATE EMISSIONS
Operation of ferroalloy furnaces produces particulate emissions at three
principal points:
1. The top of the furnace, carried out with the reaction gases.
2. The furnace tapholes. Since most furnaces are tapped cyclically rather
than continuously, the source is active only about 15% of the time.
3. The ladle after tapping, which is also a non-continuous source of particulates.
The particulates emitted are small in size and are composed of the oxides of
the metals being produced and used in the process. Examples are given in Table
18. Attention should be drawn to the submicron size of the particles. Particles of
this size are difficult to collect and usually require high expenditures of energy.
Agglomeration of the particles can make the effective particle size to the collector
much larger than that indicated in the Table. Grain loadings have been reported
in the range of 5 to 30 gr/SCF for the closed hood system and 0.1 to 2 gr/SCF
for the open hood system9.
57
-------
TABLE 16
WEIGHT BALANCE FOR PRODUCTION OF 45% FERROSIUCON
Production Rate Basis: 2 Ton/Hr of Alloy
Input, ton/hr Output, ton/hr*
Quartzite 2.02 Ferrosilicon 2.00
Coke 1.18 Slag 0.06
Steel Shavings 1.15 Gas 2.33
Electrode Mass 0.04
4.39 4.39
'Averaged over operating cycle
58
-------
TABLE 17
COMPARISON OF GAS FLOWS FROM OPEN AND CLOSED HOOD
50 MW SUBMERGED ARC FURNACES MAKING 50% FERROSILICON
Closed Hood Open Hood
Flow, ACFM 20,000 310,000
Temperature, ฐF 1,100 460
Flow, SCFM 6,600 175,000
59
-------
TABLE 18
PROPERTIES OF PARTICIPATE EMISSIONS FROM FERROALLOY FURNACES
Alloy Type
Furnace Hood Type
Particle Size, /*
Maximum
Range of Most Particles
Chemical Analysis, Wt. %*
Si02
FeO
MgO
CaO
MnO
AI203
Cr203
LOI"
50% Fe Si Si Mn
Fe Mn H.C. Fe Cr
Open
0.75
63-88
Covered
Open
Covered
0.75
0.2-0.4
15.63
6.75
1.12
31.35
5.55
0.75
0.05-0.4
25.48
5.96
1.03
2.24
33.60
1.0
0.1-0.4
20.96
10.92
15.41
2.84
7.12
29.27
23.25
8.38
"Standard metal oxides analysis compounds not necessarily found in the
chemical forms listed.
"Loss in weight on ignition.
60
-------
POLLUTION CONTROL CONSIDERATIONS
As previously mentioned, the size of the particles emitted from a ferroalloy
furnace is very small. There are five types of pollution control equipment which
could be employed to control this emission. They are:
1. Dynamic scrubber
2. Venturi scrubber
3. Ceramic tube filter
4. Electrostatic precipitator
5. Fabric filter
The dynamic scrubber has been successfully employed to collect particulate
matter from ferroalloy furnaces. Collection efficiencies of greater than 98% for
participates and 79% for organics have been reported.9 The major problems are
a design capacity limitation of 4000 ACFM (2000 ACFM is standard size sold)
per unit, high power usage, high clean water consumption, and disposal of the
liquid discharge.
The venfuri scrubber has also been used to clean gaseous emissions from
ferroalloy furnaces. Collection efficiencies of greater than 98% have been reported
with open hood furnaces.9 High pressure drops are required for successful operation.
However, power and water consumption are less than with the dynamic scrubber.
Ceramic tube filters have been used in Germany on calcium carbide
electric furnaces. This filter operates at 600ฐC which is above the combustion
temperature of the hydrocarbons in the gas stream. The capital cost is high.
Electrostatic precipitators have not been widely used to control ferroalloy furnace
emissions in this country although they have been used to some extent in Europe.
The principal problems are poor resistivity and high capital cost.
Fabric filters are widely used as control devices for emissions from open hood
ferroalloy furnaces. High collection efficiencies are obtainable but the unit must be
installed so as to avoid the operating problems which are inherent in the application
of fabric filters to furnace gases. Furnace gases must be cooled prior to entering
the fabric filter in order to avoid damaging the bags which have low design limit
temperatures. Provision must be made to minimize the condensation of hydro-
carbon on the bags which could lead to blinding. Provision must also be made to
capture sparks and burning particles before they can enter the fabric filter and
burn holes in the bags.
61
-------
SPECIFICATIONS AND COSTS
Abatement specifications for fabric filters were written for both small and
large sized operations for three types of ferroalloy furnace installations: ferrosilicon
furnaces with air dilution coolers, silicon metal furnaces with air dilution coolers,
and silicon metal furnaces with evaporative coolers.
Estimates of capital costs and annual operating costs made by the bidders
for each system were averaged and presented in the cost tables and graphs.
Reverse air or shaker type collectors with an average air to cloth ratio of about
2:1 were used in each of the cases. One of the three bidders specified a CaCOa
pre-coat required for all three systems and showed the pre-coat cost in his annual
operating cost estimate. This fact is footnoted on the operating cost tables but is
not included in the averaged cost data presented.
Specifications for fabric filter systems for ferroalloy furnaces are shown in
Tables 19 and 20. Cost data are presented in Tables 21 and 22 and Figures 19
and 20. This system uses an air dilution cooler preceding the fabric filter.
The specifications for fabric filter systems for silicon metal furnaces using air
dilution coolers are shown in Tables 23 and 24. Cost data are presented in
Tables 25 and 26 and Figures 21 and 22.
The specifications for fabric filter systems for silicon metal furnaces using
evaporative coolers are shown in Tables 27 and 28. Cost data are presented
in Tables 29 and 30 and Figures 23 and 24.
The same sized silicon metal furnaces were specified for both the air dilution
and evaporative cooled systems. This allows a comparison of the differences in
costs of the two alternative cooling methods.
62
-------
TABLE 19
FABRIC FILTER PROCESS DESCRIPTION
FOR FERROSILICON FURNACE SPECIFICATION
A fabric filter is to remove particulates from the effluent fume from a new ferrosilicon
furnace installation. The fabric filter is to be preceded by an air dilution cooler. The furnace
is of the submerged arc type. It is charged with raw material continuously and is tapped
intermittently on a two-hour cycle. The furnace is located inside the building and the air
pollution control system is located on the outside. The ductwork from the furnace hood
to the beginning of the air pollution control system is 200 ft. long and consists of 100 ft.
of vertical and 100 ft. of horizontal duct.
The abatement system shall include the following:
1. Hoods for the capture of gaseous and particulate contaminants from the tap hole and
ladle. The capture hood for the top of the furnace will be supplied by others.
2. All of the ductwork, connecting hoods, and abatement equipment.
3. Fans sized with at least 20% excess capacity on volume and 10% excess capacity
on static pressure. The location of the fans shall be on the inlet side of the abatement system.
4. A mechanical collector upstream of the fabric filter and fan to help protect the bags
from large burning particles.
5. Compartmented design of the fabric filter to permit shutdown of each section for
maintenance.
6. Sufficient capacity for operation with one compartment out of service for cleaning.
7. Bags with a temperature rating of =s500ฐF.
8. A high temperature by-pass around the fabric filter for use during operational upsets.
9. Dust hoppers and conveyors.
10. Dust storage bins with 24-hour capacity.
63
-------
TABLE 20
FABRIC FILTER OPERATING CONDITIONS
FOR FERROSILICON FURNACE SPECIFICATION
Alloy Type
Furnace Type
Furnace Size, mw
Product Rate, tonlhr
Process Weight, tonlhr
Gas to Collector
75% FeSi
Open
25
2.84
12.78
Temperature, ฐF
SCFM
Moisture Content, vo/%
So//ds Loading
grIACF
Iblhr
75% FeSi
Open
40
4.55
20.48
750,500
400
462,500
2.0
0.40
2,600
1,200,800
400
740,000
2.0
0.40
4,160
Gas from Collector
ACFM
Temperature, ฐF
SCFM
Moisture Content, vo/%
So//ds Loading
gr/ACF
Iblhr
Collection Efficiency, %
750,500
400
462,500
2.0
1,200,800
400
740,000
2.0
0.01
64
97.S2
0.01
103
97.52
'Includes 60,000 ACFM @ 150"F from taphole hood.
Performance will exceed stated efficiency. The stated efficiency represents an outlet
loading of 0.01 grIACF for guarantee purposes.
64
-------
TABLE 21
ESTIMATED CAPITAL COST DATA (COST IN DOLLARS)
FOR FABRIC FILTERS FOR FERROSILICON FURNACE
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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
Large
High Efficiency
Small
750,500
400
462,500
2.0
.40
2,600
750,500
400
462,500
2.0
.01
64
97.5
1,258,833
409,567
1,226,433
2,894,833
Large
1,200,800
400
740,000
2.0
.40
4,160
1,200,800
400
740,000
2.0
.01
103
97.5
1,957,350
624,647
1,901,700
4,483,697
65
-------
FIGURE 19
CAPITAL COST OF FABRIC FILTERS
FOR FERROSILICON FURNACES
D
5
4
3
2
-j I06
O 9
8
8 6
5
4
3
2
I05
'
A
#
0
,
'
^
y
r
/COLLECTOR
COLLECTOR
X
PLUS AUXIt
ONLY
JARIES
K)5
3 4 5 6 7 8 9 I06
CLEANED GAS FLOW, ACFM
66
-------
TABLE 22
ANNUAL OPERATING COST DATA (COST IN S/YEAR)
FOR FABRIC FILTERS FOR FERROSILICON FURNACE
Operating Cost Item
Operating Factor, Hr/Year-8600
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/mh
$8/mh
$6/mh
$0.011/kwh
$0.25
16% of Cat
Medium Efficiency
Small
Large
High Efficiency
Small
11,874
520
12,394
9,438
2,167
11,605
89,560
89,560
208,700
875
209,575
323,134
463,173
786,307
Large
13,188
648
13,836
13,656
3,250
16,906
143,361
143,361
334,400
1,190
335,590
509,693
717,392
1,227,085
One bidder recommended the use of a CaCOa precoat at a cost of $20/ton.
-------
COST, DOLLARS
ro
(*>
O>
o
r
C1 co
m
o .&.
O
ฃ ซ
>
o
-------
TABLE 23
FABRIC FILTER PROCESS DESCRIPTION
FOR SILICON METAL FURNACE SPECIFICATION
A fabric filter is to remove particulates from the effluent fume from a new silicon metal
furnace installation. The fabric filter is to be preceded by an air dilution cooler. The furnace
is of the submerged arc type. It is charged with raw material continuously and is tapped
intermittently on a two-hour cycle. The furnace is located inside the building and the air
pollution control system is located on the outside. The ductwork from the furnace hood
to the beginning of the air pollution control system is 200 ft. long and consists of WO ft.
of vertical and 100 ft. of horizontal duct.
The abatement system shall include the following:
1. Hoods for the capture of gaseous and paniculate contaminants from the tap hole and
ladle. The capture hood for the top of the furnace will be supplied by others.
2. All of the ductwork, connecting hoods, and abatement equipment.
3. Fans sized with at least 20% excess capacity on volume and 10% excess capacity
on static pressure. The location of the fans shall be on the inlet side of the abatement system.
4. A mechanical collector upstream of the fabric filter and fan to help protect the bags
from large burning particles.
5. Compartmented design of the fabric filter to permit shutdown of each section for
maintenance.
6. Sufficient capacity for operation with one compartment out of service for cleaning.
7. Bags with a temperature rating of =s500ฐF.
8. A high temperature by-pass around the fabric filter for use during operational upsets.
9. Dust hoppers and conveyors.
10. Dust storage bins with 24-hour capacity.
69
-------
TABLE 24
FABRIC FILTER OPERATING CONDITIONS
FOR SILICON METAL FURNACE SPECIFICATION
Alloy Type
Furnace Type
Furnace Size, mw
Product Rate, tonlhr
Process Weight, tonlhr
Gas to Collector
ACFM1
Temperature, ฐF
SCFM
Moisture Content, vo'%
So//ds Loading
gr/ACF
Iblhr
Gas from Collector
ACFM
Temperature. ฐF
SCFM
Moisture Content, vol%
Solids Loading
grIACF
Iblhr
Collection Efficiency, %
Silicon
Open
15
1.07
5.24
450,300
400
277,500
2.0
0.56
2,160
450.300
400
277,500
2.0
0.01
39
98.2*
Silicon
Open
25
1.79
8.77
750,500
400
462,500
2.0
0.56
3,600
750,500
400
462,500
2.0
0.01
64
98.2*
Includes 60,000 ACFM @ 150ฐF from taphole hood.
Performance will exceed stated efficiency. The stated efficiency represents an outlet
loading of 0.01 grIACF for guarantee purposes.
70
-------
TABLE 25
ESTIMATED CAPITAL COST DATA (COST IN DOLLARS)
FOR FABRIC FILTERS FOR SILICON METAL FURNACE
(DILUTION COOLING)
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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
Large
High Efficiency
Small
450,000
400
277,500
2.0
.56
2,160
450,000
400
277,500
2.0
.01
39
98.2
765,100
263,733
768,873
1,797,706
Large
750,500
400
462,500
2.0
.56
3.600
750,500
400
464,500
2.0
.01
64
98.2
1,258,633
415,200
1,231,800
2.905.633
71
-------
FIGURE 21
CAPITAL COST OF FABRIC FILTERS
FOR SILICON METAL FURNACE
(DILUTION COOLING)
O
5
4
3
2
2 io6
o 9
8
^ 7
8 6
5
4
3
2
IO5
*
^X
^
x
/
X
jrf
X3
y
r
^/
y
/^
0
.
0
,
^
^
^
'
- TURNKEY SYSTEM
COLLECTOR PLUS
COLLECTOR ONL1
AUXIUARIE
1
5
3 4 5 6 7 8 9 IO6
CLEANED GAS FLOW, ACFM
72
-------
TABLE m
ANNUAL OPERATING COST DATA (COST IN $/YEAR)
FOR FABRIC FILTERS FOR SILICON METAL FURNACE
(DILUTION COOLING)
Operating Cost Item
Operating Factor, Hr/Year -8600
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/mh
$8/mh
$6/mh
$0.011/kwh
$0.25 M/gal
16% of Cap
Medium Efficiency
Small
Large
High Efficiency
Small
7,068
312
7,380
6,408
1,383
7,791
54,363
54,363
114,100
728
114,828
184,362
287,633
471,995
Large
11,874
520
12,394
9,486
2,167
11,653
87,947
87,947
215,800
A
875
215,675
325,669
464,901
790,570
*0ne bidder recommended the use of a CaCOs precoat at a cost of $20/ton.
-------
FIGURE 22
ANNUAL COST OF FABRIC FILTERS
FOR SILICON METAL FURNACE
(DILUTION COOLING)
D
5
4
3
2
3 i<*
5 9
S 8
ฃ 7
8-6
5
4
3
2
io5
A
/
/
A
X
/
J
/
/
/
/
^
/
/
/
/
TOTAL ANNUAL CO
TOTAL DIRECT CO$
ST
JT
I05
3 4 5 6 7 8 9 106
CLEANED GAS FLOW, ACFM
74
-------
TABLE 27
FABRIC FILTER PROCESS DESCRIPTION
FOR SILICON METAL FURNACE SPECIFICATION
A fabric filter is to remove particulates from the effluent fume from a new silicon metal
furnace installation. The fabric filter is to be preceded by an evaporative cooler. The furnace
is of the submerged arc type. It is charged with raw material continuously and is tapped
intermittently on a two-hour cycle. The furnace is located inside the building and the air
pollution control system is located on the outside. The ductwork from the furnace hood
to the beginning of the air pollution control system is 200 ft. long and consists of 100 ft.
of vertical and 100 ft. of horizontal duct.
The abatement system shall include the following:
1. Hoods for the capture of gaseous and paniculate contaminants from the tap hole and
ladle. The capture hood for the top of the furnace will be supplied by others.
2. All of the ductwork, connecting hoods, and abatement,equipment.
3. Fans sized with at least 20% excess capacity on volume and 10% excess capacity
on static pressure. The location of the fans shall be on the inlet side of the abatement system.
4. A mechanical collector upstream of the fabric filter and fan to help protect the bags
from large burning particles.
5. An evaporative cooler to lower the temperature of the inlet gas to 400ฐF.
6. Compartmented design of the fabric filter to permit shutdown of each section for
maintenance.
7. Sufficient capacity for operation with one compartment out of service for cleaning.
8. Bags with a temperature rating of ^500ฐF.
' 9. A high temperature by-pass around the fabric filter for use during operational upsets.
10. Dust hoppers and conveyors.
11. Dust storage bins with 24-hour capacity.
75
-------
TABLE 28
FABRIC FILTER OPERATING CONDITIONS
FOR SILICON METAL FURNACE SPECIFICATION
Alloy Type
Furnace Type
Furnace Size, mw
Product Rate, tonlhr
Process Weight, tonlhr
Gas fo Gas Cooler
ACFM*
Temperature, ฐF
Moisture Content, vol%
Gas to Collector
ACFM1
Temperature, ฐF
SCFM
Moisture Content, vol%
Solids Loading
gr/ACF
Iblhr
Gas from Collector
ACFM
Temperature, ฐF
SCFM
Moisture Content, vol%
Solids Loading
gr/ACF
Iblhr
Collection Efficiency, %
Silicon
Open
15
1.07
5.24
261,700
1,100
2.0
176,900
400
109,000
18.5
0.01
15
99.3*
Silicon
Open
25
1.79
8.77
436,200
1,100
2.0
176,900
400
109.000
18.5
1.42
2,160
294,900
400
181,700
18.5
1.42
3,600
294,900
400
181,700
18.5
0.01
25
99.32
includes 60,000 ACFM @ 150ฐF from taphole hood.
Performance will exceed stated efficiency. The stated efficiency represents an outlet
loading of 0.01 gr/ACF for guarantee purposes.
76
-------
TABLE 29
ESTIMATED CAPITAL COST DATA (COST IN DOLLARS)
FOR FABRIC FILTERS FOR SILICON METAL FURNACE
(EVAPORATIVE COOLING)
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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
Large
High Efficiency
Small
261,700
1,100
88,900
2.0
.96
2,160
176,900
400
109,000
18.5
.01
15
99.3
326,802
203,399
394,023
924,224
Large
436,200
1,100
148,200
2.0
.96
3,600
294,900
400
181,700
18.5
.01.
25
99.3
528,163
306,217
605,170
1,439,550
77
-------
FIGURE 23
CAPITAL COST OF FABRIC FILTERS
FOR SILICON METAL FURNACE
(EVAPORATIVE COOLING)
D
5
4
3
2
5 itf
d 9
S 8
* i
8 6
5
4
3
2
I05
Of
s^
s^
'
0X
,S
' /
/
X
a
s
S
Q
f
'
'
S^
r
y
f
/
X
s
COI
_C
-------
TABLE 30
ANNUAL OPERATING COST DATA (COST IN $/YEAR)
FOR FABRIC FILTERS FOR SILICON METAL FURNACE
(EVAPORATIVE COOLING)
Operating Cost Item
Operating Factor, Hr/Year-8600
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/mh
$8/mh
$6/mh
$0.011/kwh
$0.25 M/gal
$0.05 M/gal
16% of Cap
Medium Efficiency
Small
Large
High Efficiency
Small
5,580
307
5,887
4,743
1,198
5,941
26,281
26,281
60,600
417
1,457
68,302
106,411
147,876
254,287
Large
6,606
332
6,938
6,846
1,857
8,703
40,370
40,370
100,400
583
2,209
112,030
168,041
230,328
398 , 369
-------
FIGURE 24
ANNUAL COST OF FABRIC FILTERS
FOR SILICON METAL FURNACES
(EVAPORATIVE COOLING)
D
5
4
3
2
3 io6
d 9
2 8
te" I
8 6
5
4
3
2
IO5
1C
X
of
X
r
/
/
^
/
TOTAL ANNUAL COST
TOT
ALDII
IEC
C<
81
D5 2 3456789 IO6 2 34
CLEANED GAS FLOW, ACFM
so
-------
REFERENCES
1. Annual Statistical Report 1972, American Iron and Steel Institute, 1973,
Washington, D.C., p. 48.
2. Person, R. A., "Emission Control of Ferroalloy Furnaces", Fourth Annual
North Eastern Regional Antipollution Conference, 1971.
3. Bocey, John L, Ferrous Process Metallurgy, John Wiley & Sons, Inc., NYC,
1954, pp. 149-153, 278, 351-355.
4. Rex T. Hooper, "The Production of Ferromanganese", Journal of Metals,
May, 1968.
5. Schofield, M., "Industrial Silicon and Ferrosilicon", Metallurgia, July, 1967.
6. Sully, A. H., and Brandes, E. A., Metallurgy of the Rare Metals Chromium,
Plenum Press, 1954, NYC, pp. 19-25.
7. Air Pollution Control Technology and Costs in Nine Selected Areas,
Industrial Gas Cleaning Institute, Inc., 1972, pp. 349-396.
8. Elyutun, V. P., et al., Production of Ferroalloys, Electrometallurgy, Moscow,
1957, pp. 23-69, 108-137, 158-221.
9. Person, R. A., "Control of Emissions from Ferroalloy Furnace Processing",
Journal of Metals, April, 1971.
10. Ferrari, Renzo, "Experiences in Developing an Effective Pollution Control
System for a Submerged Arc Ferroalloy Furnace Operation", Journal of Metals,
April, 1968.
81
-------
3. GRAIN CLEANING HOUSES
For centuries, grain has been an important food source for both man and
animals. This importance is still apparent today, with world-wide annual grain
production now in excess of 1.3 billion metric tons, nearly 300 million metric tons
of which are grown in North America. Table 31 shows a breakdown of this production
by grain type.1 Two factors which account for the wide use of grain as a food
source are ease of growing, and storage stability.
Milling of grain into flour and other products is an important industry throughout
the world. Originally, milling was done in the home. Millstones were highly valued
household articles, being passed on from generation to generation. Gradually, custom
milling came into existence, and it has developed into the large complex grain
milling industry of today.
The milling process involves many steps, of which the following are among the
more important. Grain is received at the mill, given a cursory cleaning to remove
large objects such as sticks, rocks, pieces of metal, and cloth, and is then sent
to storage. As needed, it is withdrawn, and given a much more thorough cleaning,
including removing small stones, sticks, bits of metal, foreign seeds, chaff, and
dirt. The grain is then "tempered" by the addition of the right amount of moisture
to enhance milling properties. Sometimes, heat is also added, in which case the
process is called "conditioning". The grain is then ground into finished product
and conveyed to storage where it awaits distribution.
Because the quality of the finished product is dependent largely upon the cleanli-
ness of the grain, grain cleaning is an important step in the milling process. However,
the cleaning of grain generates by-products which could result in environmental
problems. This report will focus on the grain cleaning process and will include a
discussion of the process, by-products, pollution control equipment, and related
capital and operating costs.
PROCESS DESCRIPTION
Figure 25 shows a typical layout configuration for a grain cleaning house2.
Grain is withdrawn from a storage bin as needed, usually on a continuous basis,
and conveyed to the grain cleaning house. Several methods of conveyance are
used, with screw, belt, bucket, and pneumatic conveyors being the most popular.
These methods are used throughout the mill. The grain is weighed and sent to a
separation device, such as an oscillating inclined sieve which is called a scalper.
Here, dirt, dust, small pebbles and sticks, and other small objects are separated
from the grain. During scalping, the grain passes over sets of air jets, called
Preceding page blank
83
-------
TABLE 31
ANNUAL GRAIN PRODUCTION
STATISTICS1
REGION
Year
All Cereals, mmt(*)
Wheat, mmt
Rice, mmt
Maize, mmt
Barley, mmt
WORLD
1969 1970 1971
1195.6 1203.5 1305.7
315.6 316.7 340.2
294.9 305.8 508.9
264.8 259.7 307.9
137.1 138.5 152.1
NORTH AMERICA
1969 1970 1971
239.8 215.4 275.6
58.4
4.1
46.5 58.5
3.8
3.8
118.3 107.0 143.6
17.5
18.0 24.5
Millions of metric tons
84
-------
CLEANED
GRAIN TO
MILLING
PROCESS
WEIGHING
JET
OSCILLATING INCLINED
SIEVE
(SCALPER)
WATER
i
, ASPIRATOR N
(ONE OF SEVERAL)
_pi^r_a |
1BEESWING ~~ WATER
A i*ซ
.
J
ROTATING
DISC
PLATE
(ONE OF
MANY)
DISC
SEPARATOR
WASTE
AIR
EXCESS WATER
CENTRIFUGE
FINAL WASH
SCOURER
PREWASH
Figure 25. Flow diagram for Grain Cleaning House
00
en
-------
aspirators, located in the scalper. These aspirators dislodge very light objects of
large surface area, i.e., wheat chaff, without disturbing the grain. These scalpers
are similar to those used at grain elevators and terminals where the grain is first
brought by farmers, but have a smaller screen size. Scalpers at elevators and
terminals are used solely for removal of large objects from the grain such as rocks,
large sticks, pieces of iron, rags, and so on. This process could be classified as
grain cleaning, but will not be the principal process studied here. Instead, this
report will focus on the grain cleaning process used just prior to grain milling.
Next, ferrous metal pieces still remaining in the grain are removed by magnets.
This metal could cause serious damage to mill rolls if it were not removed. The
grain is then conveyed through one or more aspirating devices. Like those used
in the initial scalping step, these devices utilize air jets to remove dust particles,
dirt, and chaff. Since no aspirator is 100% efficient, several are used to assure as
complete a separation as possible.
The grain then goes to a disc separator. The main feature of this machine
is its unique set of rotating discs. Each disc contains many specially designed
grooves or pockets which trap and lift away foreign seeds, such as weed seeds,
while allowing the grain to pass unhindered. Different plates are used to trap
different kinds of seeds. The discs are positioned at right angles to the flow of
grain and the machine is designed so that grain may be withdrawn at any point.
From here, the grain passes on to a scourer. This machine removes dirt
from the surface of the wheat by friction. Designs vary, but usually the wheat is
pushed against a hard emery surface by paddles, the severity of the operation
being controlled by the clearance between the paddles and the emery surface.
Scouring is often preceded by a light pre-wash to help toughen the grain and prevent
it from being broken during the scouring process. Dirt and pieces of the outer
coating of the wheat bran called beeswing generated during the scouring process
are removed by air aspiration in the same way as outlined above.
The last cleaning operation performed on the grain is a water wash. The water
removes any dirt still remaining on the grain and acts as a final separating device
for any stones or bits of metal which may have remained throughout the cleaning
process. Again, designs vary, but usually the grain is conveyed through a trough
of water. The dirt is floated away, and the metal and small stones sink. Excess
water is removed from the grain by centrifugal action and the wheat is sent to
the mill for grinding.
NATURE OF THE PARTICULATE EMISSION
The discharge from a grain cleaning house consists of dust and other particles
86
-------
developed during the cleaning process or carried in as dockage, as shown in Table
32. Dockage is defined as that material in the grain which is of no use and must
be removed. This includes chaff, dirt, sticks, stones, cloth, paper, insect debris,
foreign seeds, and so on. Any of these materials, if fine enough, will yield air-borne
dust upon agitation of the grain. Since the cleaning process, by its very nature,
agitates the grain vigorously, much dust is released in the process. Table 33 lists
some of the properties of the dust emitted during the cleaning process. The quantity
of dust generated depends, of course, upon the size of the operation and upon
such factors as grain type, quality, and the amount of dockage present. As is
to be expected, different pieces of equipment in the cleaning process emit different
concentrations of dust. However, usual practice is to duct the individual dust sources
to a common dust collector. Based on emission test measurements in about 600
grain cleaning operations, average emission estimates from various kinds of grain
cleaning equipment have been made. These emissions, measured as dust load to
the control device, range from a high of 9.9 gr/SCF from the scourer in an air
volume of 2350 ACFM to a low of 1.45 gr/SCF from the wheat cleaning separator
in an air volume of 8,000 ACFM. Other pieces of equipment tested were the scalper
and the wheat cleaning aspirator which had dust loads of 3.2 and 2.32 gr/SCF
in an average of 2,950 ACFM and 5,000 ACFM, respectively.
In addition to the common dust collector operation, some pieces of equipment,
such as the aspirator, operate on a closed system basis. The same air is used
repeatedly, cleaned and recirculated, and never escapes to the atmosphere8. This
report will focus on equipment which is not of the closed system type.
POLLUTION CONTROL CONSIDERATIONS
The two types of pollution control equipment most commonly used in conjunction
with grain cleaning operations are fabric filters and cyclones.
As mentioned above, common practice is to provide a dust collection system
common to many pieces of equipment. Therefore, the cleaning house may be served
by a single appropriately sized fabric filter or bank of cyclones. To keep dust
emissions to a minimum, machines are usually closed to the atmosphere and
under negative pressure so that dust generated in the cleaning process is kept
within the machine and carried by the ductwork to the collection system.
Both cyclones and fabric filters are in wide use in the feed and grain industry.
Table 34 shows a comparison of these two types of control devices. Where com-
pliance with relevant codes can be achieved with cyclones, economics will dictate
their use. However, cyclones have limited efficiency capability and cannot achieve
compliance in all cases. Where cyclones cannot be used, fabric filters are the most
common control device employed. Fabric filter efficiencies are, in most cases,
87
-------
TABLE 32
CONTAMINANTS GENERATED DURING GRAIN CLEANING
Operation
Inclined Sieve
Aspirator
Disc Separator
Scourer
Conveyors
Type of Contaminant Generated
Dust, dirt, chaff
Dust, dirt, chaff
Foreign seeds, dust
Dirt, beeswing
Dust
88
-------
TABLE 33
PROPERTIES OF DUST EMITTED FROM
GRAIN CLEANING OPERATIONS
Particle Size
Dust Concentration
Specific Gravity
Temperature
Moisture Content of Dust
Ranges3 from V to 1000/z
Larger particles such as chaff and insect debris
may also be present
Ranges4 from about 1 to 10 gr/SCF
1.8 for both the primary cyclone and secondary
fabric filter catch
Ambient
Moisture content of the air due to ambient relative
humidity
89
-------
TABLE 34
RELATIVE ADVANTAGES AND DISADVANTAGES OF
CYCLONES AND FABRIC FILTERS
Unit
Fabric Filters
Advantages
Disadvantages
1. High single unit efficiency. 1. High maintenance cost,
i.e., bag replacement.
2. With the right filter fabric, 2. High first cost.
efficiencies remain high
for small particles.
Cyclones
1. Low first cost.
1. Single unit efficiencies
tow especially for small
particles, requiring cas-
cading.
2. Low maintenance cost.
90
-------
more than adequate to achieve compliance with all applicable codes.
SPECIFICATIONS AND COSTS
Specifications have been written for fabric filter systems to collect the dust
emitted from the operations of both a small and a large grain cleaning house
processing wheat. The fabric filter is specified to treat a single air exhaust stream
which has been ducted from the hoods of the following grain cleaning operations:
1. Scalping
2. Aspiration
3. Disc separation
4. Scouring
Equipment specifications are shown in Tables 35 and 36 and cost data for the
systems are shown in Tables 37 and 38 and Figures 26 and 27. The bidders
specified different but standard fabric filter materials and average air to cloth
ratios of about 10/1 for both small and large sized operations, respectively.
To minimize the explosion hazard associated with grain cleaning operations,
a number of fabric filter safety features were considered. Explosion vents are
standard on all grain house fabric filters and are included in the gas cleaning device
cost. While spark proof fan wheels are sometimes used to minimize explosion
danger, they are not normally required since they are on the clean air side of the
fabric filter. Consequently, this feature was not included in the bids.
91
-------
TABLE 35
FABRIC FILTER PROCESS DESCRIPTION
FOR GRAIN CLEANING HOUSE SPECIFICATION
A fabric, filter system is to treat the dust emitted from the grain cleaning operations in a
grain cleaning house. These cleaning operations include the following:
1. Scalping
2. Aspiration
3. Disc Separation
4. Scouring
The hoods from all of these operations are to be ducted together to provide a single
common air exhaust stream which will be treated by the fabric filter.
The vendor is to furnish a pulse-type fabric filter unit, hoppers equipped with rotary air
locks, required booster fan, and all controls. The vendor is also to supply the required
hoods and ductwork in accordance with the information shown below:
A. Small (227 bulhr) plant.
Operation
Scalping
Aspiration
Disc Separation
Scouring
Ventilation Rate
ACFM
4,000
6,000
2,000
3,000
Hood Area
ft*
16
24
8
12
Duct Velocity
fpm
3,500
3,500
3,500
3,500
15,000
60
B. Large (758 bulhr) plant.
Ventilation Rate
Operation
Scalping
Aspiration
Disc Separation
Scouring
ACFM
12,000
18,000
6,000
9,000
Hood Area
ft2
48
72
24
35
Duct Velocity
fpm
3,500
3,500
3,500
3,500
45,000
180
All common ductwork will be designed for a velocity of 3,500 fpm.
92
-------
TABLE 36
FABRIC FILTER OPERATING CONDITIONS
FOR GRAIN CLEANING HOUSE SPECIFICATION
Cleaning House Capacity, bu/hr
Cleaning House Process Weight, Ib/hr
Adjacent Flour Mill Capacity, cwt/day
Inlet Gas to Fabric Filter
ACFM
Temperature, ฐF
SCFM
Solids Loading
gr/ACF
Ib/hr
Outlet Gas from Fabric Filter
ACFM
Temperature, ฐF
SCFM
Solids Loading
gr/ACF
Ib/hr
Collection Efficiency
Small
227
12,500
2,400
0.01
1.29
99.6
Large
758
41,700
9,000
15,000
75
14,900
3.02
388
15,000
75
14,900
45,000
75
44,600
3.32
1,281
45,000
75
44,600
0.01
3.86
99.7
93
-------
TABLE 37
ESTIMATED CAPITAL COST DATA (COST IN DOLLARS)
FOR FABRIC FILTERS FOR GRAIN CLEANING HOUSE
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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
Large
High Efficiency
Small
15,000
75
14,900
3.02
388
15,000
75
14,900
.01
1.29
99.6
12,364
4,537
1,821
28,825
47,547
Large
45,000
75
44,600
3.32
1,281
45,000
75
44,600
.01
3.86
99.7
29,493
12,910
3,212
62,030
107,645
94
-------
FIGURE 26
CAPITAL COST OF FABRIC FILTERS
FOR GRAIN CLEANING HOUSE
6
5
A
10*
8
V'
4
TURNKEY SYSTEM
COLLECTOR PLUS AUXILIARIES
COLLECTOR ONLY
10
3 A 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
95
-------
TABLE 38
ANNUAL OPERATING COST (COST IN S/YEAR)
FOR FABRIC FILTERS FOR GRAIN CLEANING HOUSE
Operating Cost Item
Operating Factor, Hr/Year -4000
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/mh
$8/mh
$6/mh
$0.011/kwh
16% of Cap
Medium Efficiency
Small
Large
High Efficiency
Small
None
1,068
125
1,193
775
775
1,142
1,142
3,110
7,608
10,718
Large
None
1,410
150
1,560
1,575
1,575
2,876
2,876
6,011
17,223
23,234
-------
FIGURE 27
ANNUAL COST OF FABRIC FILTERS
FOR GRAIN CLEANING HOUSE
6
5
A
TOTAL ANNUAL COST
10*
9
8
7
6
to
8
TOTAL DIRECT COST
IOJ
10*
3 A 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
97
-------
REFERENCES
1. Monthly Bulletin of Agricultural Economics and Statistics. Food and Agriculture
Organization of the United Nations - Rome, Vol. 20, Dec., 1971, p. 16.
2. Matz, Samuel A., Cereal Technology, AVI Publishing Co., Westport, Connecti-
cut, 1970, pp. 5-6.
3. Environmental Controls for Feed Manufacturing & Grain Handling. American
Feed Manufacturers Association, Chicago, III. 1972, p. 7.
4. Engineering and Cost Study of Emission Control in the Grain and Feed
Industry. EPA Contract 68-02-0213, 1973, pp. 3-45.
5. Air Pollution Engineering Manual. U. S. Department of Health, Education
and Welfare, Public Services Publication No. 999-AP-40, Cincinnati, Ohio,
1967, p. 356.
6. Stern, Arthur C., Air Pollution. Vol. Ill, Second Edition, Academic Press,
New York, 1968, p. 277.
7. Engineering and Cost Study of Emissions Control in the Grain and Feed
Industry, EPA Contract 68-02-0213, 1973, pp. 3-130.
8. Lockwood, Joseph, Flour Milling, Henry Simon Ltd., Stockport Cheshire,
England, 1960, p. 148.
98
-------
4. GLASS-MELTING FURNACES
Glass is an inorganic product of fusion which has been cooled to a rigid
condition without crystallizing. Commercial glasses are produced from inorganic
oxides, of which silica, or sand, is usually an important constituent. Glass is
made by heating a mixture of dry materials to about 2800ฐF in a refractory
container. The heating is continued until a viscous, homogeneous liquid is
formed. By varying the proportions of the raw materials, glasses can be produced
with physical and chemical properties which vary over wide ranges.
Glasses are mixtures rather than compounds of various oxides. The common
oxides in glass are classified as formers, stabilizers and fluxes. Only a limited
number of chemical compounds are capable of forming the three-dimensional
random atomic structure characteristic of glass. The common glass formers
are the oxides of silicon (SiOz), boron (8203), and phosphorous (PaOs). The
melting point and working temperature of the mixture are lowered by adding
fluxes, which decrease the viscosity of the mixture. Stabilizers are added to
improve chemical durability and/or to prevent crystallization.
About 700 different types of glasses are produced commercially each year.
Of these glasses, a small number are produced in great volume because they
have good all-around usefulness. These glasses, which comprise the bulk of
commercial production, are commonly classified in the following chemical types
of silicate glass:
1. soda-lime glass
2. lead glass
3. borosilicate glass
4. 96 percent silica glass
5. 99.8 percent silica glass, i.e., fused quartz or fused silica.1
The composition ranges of these commercial types are given in Table 39.
Soda-lime glass presently constitutes about 90 percent of the total production
of commercial glass.3
Non-silicate glass forming systems are used to a much lesser extent.
For example, phosphate glasses are used as high temperature lubricants;
iron glasses are used in heat-absorbing applications; and borate glasses are
used in sodium vapor lamps.
Other types of silicate glasses, such as colored, opal, and optical, are usually
made from the five basic types of silicate glass listed in Table 39. Colored
glasses are generally made by adding traces of metallic oxides to the batch,
plus proper heat treatment of the finished glass. Opal glasses, which are
99
-------
TABLE 39
APPROXIMATE COMPOSITIONS OF COMMERCIAL GLASSES1
Soda-lime Lead Borosilicate 96% Silica 99.8% Silica
Wt% Wt% Wt%
Si02
Na2O
K2O
CaO
PbO
B2O3
AI2O3
MgO
ป W I /W
70-75
12-18
0-1
5-14
0.5-2.5
0-4
w ป /w
53-68
5-10
1-10
0-6
15-40
0-2
73-82 96 99.8
3-10
0.4-1
0-1
0-10
5-20 3
2-3
100
-------
translucent silicas of various colors, capable of refracting light and then reflecting
it in a play of colors, are usually made by adding fluorides or phosphates to
the batch. Optical glasses are made in a variety of compositions. In general,
the chemical composition of other types of glasses does not vary significantly
from that of the five basic types.
Over 5,000,000 tons of glass sand are used in the United States each year
in order to produce all of these various glasses. To flux this silica requires
over 1,500,000 tons of soda ash, 113,000 tons of salt cake (impure sodium
sulfate, 90 to 99%), and 875,000 tons of limestone or equivalent lime.5
Sand for glass manufacture should be almost pure quartz. The location
of glass factories is frequently determined by the location of glass-sand deposits.
Soda, NazO, is supplied mainly by dense soda ash, NazCOa. Other sources
are sodium bicarbonate, sodium sulfate, and sodium nitrate. The primary sources
of lime, CaO, are limestone and burnt lime from dolomite.
The chemical reactions involved in making glass may be summarized
as follows:5
NazCOs + aSiO2 -ป Na2O aSiOz + CO2 (1)
CaCOs + bSiOz -ป CaO bSiOz + COz (2)
+ cSiOz + C -> NazO cSiOz + SOz + CO (3)
The last reaction may take place as in equations (4) or (5), and (6):
Na2SO4 + C -ป NazSOa + CO (4)
2Na2SO4 + C -ป 2Na2SO3 + COz (5)
NazSOa + cSiOz -ป NazO cSiOz + SOz (6)
The ratios NazO/SiOz and CaO/SiOz need not be 1 to 1 molecular
ratios. In ordinary window glass the molecular ratios are approximately:
2 mots NazO/5 mols SiOz and 1 mole CaO/5 moles SiOz
Other glasses vary widely.5
PROCESS DESCRIPTION
There are two basic steps in the manufacture of glass. They are:
1. The melting of sand and stabilizing oxides to form molten glass
2. The fabrication of this molten glass into useful articles
In the first step, sand and other raw materials are procured and
101
-------
stored in sufficient quantities to permit continuity of operation. These
materials are accurately weighed in correct proportions to yield glass of
the desired composition. Then they are thoroughly mixed and fed into the
melting furnace. In the melter the raw materials are heated to a higher
temperature until chemical reactions which liberate carbon dioxide, water, and
other gases are completed, and the bubbles thus formed are eliminated. The
glass is cooled, before leaving the melting unit, to bring its viscosity to a
value that is suitable for the particular forming operation to be used. Table 40
presents the useful range of glass viscosities with regard to its use in a particular
manufacturing operation.
Fabrication of the molten glass may involve such operations as pressing,
blowing, rolling or drawing. After the glass is formed to a particular
shape, the article passes through an annealing oven to reduce internal
stress.
Secondary, or finishing, operations such as grinding, polishing, cutting
and chemical treatment are frequently performed on the fabricated articles.
In most instances, such operations are separated from the primary fabrication
operations and sometimes occur in a plant of an entirely different organization.
The factors involved in the selection of sand, and other materials as well,
are purity, cost, and grain size. The principal ingredients used for manufacturing
soda-lime glass are sand, soda ash, and limestone. Other materials frequently
used in glass production are borax, boric acid, litharge, potash, fluorspar,
zinc oxide, and barium carbonate. Table 41 lists several of the raw constituents
of glass and their glassmaking equivalents.
Most glass is melted by a continuous process in tanks made of
refractory blocks and heated from above by the flames of burning fuel.
Batch or day tanks are used for small amounts of glass, having special
composition and properties. The batch type units reach sizes of a few tons
in holding capacity, while continuous tanks range from less than a ton to 1500
tons capacity, with outputs up to several hundred tons of glass per day.
Continuous tanks for melting glass are generally rectangular in
shape and are divided into two compartments by a permanent wall or
by floating refractory baffles. The batch of well-mixed raw materials is
introduced into the larger compartment known as the melting end. The
other compartment, known as the working or refining end, is where the
glass is cooled and distributed for use.
In the melting end of the tank, the batch is heated until the
102
-------
TABLE 40
USEFUL RANGE OF GLASS VISCOSITIES1
Operation Viscosity. Poises
Melting 102
At Automatic Feeder 103 -10"
For hand gathering 103-2
Gather when placed in paste mold ~\Q*'5
Ware removed from paste mold 107
Annealing 1013 -1013-5
At maximum service temperature 1014-6 -1015-5
(Temperature at which glass is substantially rigid)
103
-------
TABLE 41
GLASSMAKING MATERIALS1
Raw Material
Sand
Soda Ash
Limestone
Dolomite
Feldspar
Borax
Boric Acid
Litharge
Potash
Fluorspar
Zinc Oxide
Barium Carbonate
Chemical
Composition
SiO2
Na2CO3
CaCOa
CaCOa-MgCOa
K2(Na2)O-AI2O3-6SiO2
Na2B4O7-1OH2O
B2O3-H2O
PbO
K2CO3-1.5H2O
CaF2
ZnO
BaCO3
Glassmaking
Oxide
SiO2
Na2O
CaO
CaO
MgO
AI203
K2(Na2)O
Si02
Na2O
B203
B2O3
PbO
KizO
CaF2
ZnO
BaO
Percent
Oxide
100.0
58.5
56.0
30.4
21.8
18.0
13.0
68.0
16.3
36.5
56.3
100.0
57.0
100.0
100.0
77.7
104
-------
fluxes melt and dissolve the sand and other ingredients. Carbon dioxide
and water, as well as air trapped in the interstices of the batch, produce
many bubbles so that when first melted, the glass is a foamy mass.
Most of these bubbles are eliminated at the high temperature of the
melting end. Convection currents, which arise in the glass through the
heating of the flames and cooling by side walls and cold batch, help to
make the melt homogeneous by a stirring action. The molten glass from
the melting end passes through a hole, or throat, in the wall, or under
the floating refractory baffles. This serves to skim off foam or scum
on the surface of the molten glass.
In the refining end of the tank, the glass is cooled until its viscosity
has increased to the proper value for fabrication. In mechanized operations,
the glass flows from the refining end to the forming equipment in refractory
channels termed "forehearths." The final cooling takes place in the forehearths,
the construction of which vary depending upon the kind of forming machine to
be supplied. A flow diagram for soda-lime glass manufacture is presented in
Figure 28.
Systems for batch mixing and conveying of materials for making soda-lime
glass normally use commercial equipment of standard design. This equipment
is generally separate from the glass-melting furnace and is commonly
referred to as a "batch plant." A flow diagram of a typical batch plant
is shown in Figure 29. Major raw materials and cullet (broken scrap glass)
are conveyed to the elevated storage bins from railroad hopper cars or
hopper trucks by a combination of screw conveyors, belt conveyors, and
bucket elevators. Minor ingredients are usually delivered in cardboard
drums and transferred by hand to small bins. The ingredients for a given
batch are dropped from the storage bins into weigh hoppers and then
released into the mixer. Cullet is ground and then mixed with the other
ingredients in the mixer. These materials are blended for 3 to 5 minutes
and then transferred to a charge bin located near the melting furnace.
The blended material is fed into the furnace feeders through rotary valves
located at the bottom of the charge bin.
Glass-melting furnaces for soda-lime glass are generally direct-fired,
continuous, regenerative furnaces. They usually range in capacity from 50
to 300 tons of glass per day. The most common capacity found in the
United States is 100 tons per day.3 Regenerative firing systems consist
of dual chambers filled with brick checkerwork. Combustion air is preheated
in one chamber, while the products of combustion from the melter pass
through and heat the opposite chamber. By reversing the flow of air
and combustion products, the functions of each chamber are interchanged.
This occurs every 15 to 20 minutes in order to maximize heat conservation.
105
-------
o
O>
SILICA SAND
Si02ป99%
TO YIELD SILICA,
Si Oo .SANDSTONES
(IN PA..W. VA..ILL.,
MO.) ARE CRUSHED,
WASHED, SCREENED
TO APPROX. 20-100
MESH
Fe2 03
-------
GULLET
SFfET
MAONETC
[SEPARATOR
CRUSHER
RAW MATERIALS
RECEIVING
HOPPER
CONVEYOR
STORAGE BINS
MAJOR RAW MATERIALS
MINOR
MGREDIENT
STORAGE
\.
Y
I
BATCH
STORAGE
BW|
I
FURNACE
FEEDER
GLASS
MELTING
FURNACE
FIGURE 29
PROCESS FLOW DIAGRAM OF A BATCH PLANT3
107
-------
In order to prevent air induction and a subsequent loss in combustion efficiency,
continuous furnaces are usually operated slightly above atmospheric pressure.
Furnace draft is produced by induced-draft fans, natural-draft stacks, or ejectors.
NATURE OF THE GASEOUS DISCHARGE
Melting Furnaces
The major source of air contaminants from a glass plant is the glass-melting
furnace. An estimate of national pollutant emissions from glass furnaces based
upon production in 1971 is presented in Table 42. During the melting process,
carbon dioxide bubbles form and propel particulates from the melting batch.
These particulates are entrained by the fast-moving stream of flames and
combustion gases. Once swept from the melter, they are either collected in
the checkerwork and gas passages or exhausted to the atmosphere. Paniculate
emissions are also formed due to the condensation of certain components
which were volatized in the glass melt.
Many source tests of glass furnaces in Los Angeles County were studied to
determine the major variables which influence stack emissions, and this data is
summarized in Table 43. Paniculate samples were obtained from the catch of a
pilot fabric filter which vented part of the effluent from a large soda-lime container
furnace,3 and panicle size distributions of two typical samples are shown in
Table 44. Additional panicle size distributions from a separate study of two
side-port, regenerative, gas-fired furnaces are presented in Figure 30. Flue gas
conditions and compositions during sampling for these additional tests are shown
in Tables 45 and 46.
The chemical compositions of five separate paniculate samples, four from
a pilot fabric filter, and one from the stack of a soda-lime regenerative furnace,
are presented in Table 47. These samples were found to be composed mostly
of alkali sulfates although alkalies are reported as oxides.
Opacity of stack and paniculate emissions did not correlate very well,
based on the source test data presented in Table 43. However, some generalizations
on opacity can be made.
1. Opacity increased directly with paniculate loading
2. Furnaces burning U. S. Grade 5 fuel oil usually have plumes exceeding
40% opacity.
3. While burning natural gas or U. S. Grade 3 fuel oil, however, the plumes
from these same furnaces are only 15 to 30 percent white opacity.
108
-------
TABLE 42
ESTIMATED NATIONAL EMISSIONS, 1971 (TONS)
GLASS FURNACES4
Sulfur Oxides 1,675
Nitrogen Oxides 1,125
Carbon Monoxide 2,350
Fluorides 275
Paniculate Matter 26,250
109
-------
TABLE 43
SOURCE TEST DATA FOR GLASS-MELTING FURNACES*
Test No.
C-339b
C-339
C-382-1
C-382-2
C-536
C383
Pri-Lab
Pri Lab
PriLab
Pri Lab
PriLab
Pri Lab
Pri Lab
C-101
C-120
C-577
C-278-1
C-278-2
C-653
C-244-1
C-244-2
C-420-1
C-420-2
C-743
C-471
Type
of
Furnace*
EP
EP
EP
EP
EP
EP
EP
EP
EP
EP
EP
EP
EP
EP
EP
SP
SP
SP
SP
SP
SP
SP
SP
SP
SP
Type
of
Fuel"
0-300
G
G
G
0-200
G
G
G
G
G
G
0-300
G
G
G
0-300
G
0-300
G
G
G
G
G
G
G
Xi
(paniculate
emissions),
Ib/hr
7.00
3.00
4.60
6.40
4.70
8.40
3.86
4.76
4.26
6.84
4.62
3.96
7.16
9.54
9.90
12.70
3.97
8.44
8.90
6.30
3.00
6.30
6.60
10.20
6.70
X2
(process wt ratio),
Ib/hr ft2
of Metier Area
16.7
13.8
16.5
18.2
17.5
17.9
10.9
14.6
17.1
17.4
18.5
14.6
20.2
15.2
14.2
24.2
18.3
18.5
22.0
7.5
5.4
10.7
13.2
26.2
11.6
X3,
X4
Maximum
wt fraction (checker volume), Opacity
of cullet in
Charge*"
0.300
0.300
0.300
0.300
0.199
0.300
0.094
0.094
0.157
0.094
0.365
0.269
0.175
0.300
0.320
0.134
0.361
0.360
0.131
0.182
0.100
0.100
0.100
0.047
0.276
ftW
of Melter
5.40
5.40
5.40
5.40
5.40
6.50
8.00
8.00
8.00
8.00
9.00
9.00
9.00
5.00
5.00
6.90
6.93
6.93
8.74
7.60
7.60
7.60
7.60
8.25
5.60
of Stack
Emissions, %
50
10
10
10
10
20
25
25
25
25
45
20
20
20
35
20
20
40
25
25
10
5
25
30
*EP = end port, regenerative furnace; SP = side port, regenerative furnace.
"G = natural gas; 0-200 = U.S. Grade 3 fuel oil; 0-300 = U.S. Grade 5 fuel oil.
"Constants: Sulfate content of charge 0.18 to 0.34 wt %. Fines (-325 mesh) content of charge 0.2 to 0.3 wt%.
110
-------
TABLE 44
SIZE DISTRIBUTION OF PARTICULATE EMISSIONS3
(Mlcromerograph Analyses)
Furnace 1
Diameter (D),
M
36.60
22.0
18.30
16.50
14.60
12.80
12.20
11.60
11.00
10.40
9.80
9.20
8.50
7.30
6.10
4.88
3.66
3.05
2.44
1.83
1.52
1.22
Flint Glass
% (by wt)
Less Than D
100
99.5
98.6
97.7
94.0
84.6
80.7
76.6
72.7
67.7
62.4
58.3
51.8
43.1
34.4
28.0
21.3
18.6
14.9
11.0
8.3
4.1
Furnace 2 -
Diameter (D),
M
17.40
15.70
14.00
12.20
11.60
11.00
10.50
9.90
9.30
8.80
8.10
7.00
5.80
4.65
3.49
2.91
2.33
1.74
1.45
1.16
- Amber Glass
% (by wt)
Less Than D
100
99.8
99.4
96.8
92.5
89.5
87.2
83.4
78.7
75.0
73.4
60.3
47.6
35.6
25.4
20.5
16.4
10.9
8.9
5.3
111
-------
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r
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3
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0
hi
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v/ o/~>ซ^
h
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<<^> r\si
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\JfJ*3
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^
x
x^
^x
x^
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'
x
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^
X
^
/
'
Fl-
X
"
^x
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.
NT
^X
^
^
^x
^
GL.X
^
V
X
K_
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^
X
-AN
^
^
(BE
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'
R
k"1
^
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K
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r
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X'
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x
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x
O2 12 ฃป IO 2O 3O SO 7O SO 9O 95 9S 99 99.ฉ
PERCENT BY NUMBER EQUAL. TO OR L.ETSS THAN INDICATED SIZE
FIGURE 30. Log .-probability distribution of particle sizes present in glass furnace effluent.^2)
-------
TABLE 45
FLUE CONDITIONS
THE MANUFACTURE OF GLASS2
Flint Amber
Glass Glass
Furnace Furnace
Flue diameter, ft 56
Average gas velocity, ft/sec 16 33
Average gas temperature, ฐ F 619 1,143
Static pressure, in. H2O - 0.44 - 0.98
Gas volume, scfm 8,250 16,800
113
-------
TABLE 46
EMISSIONS
FROM THE MANUFACTURE OF GLASS2
Flint Amber
Emissions Glass Glass
Furnace Furnace
Solids, gr/scf 0.029 0.041
Solids, Ib/hr 2.1 5.4
Sulfur trioxide, ppm* 17 15
Sulfur dioxide, ppm 250 315
Fluorine, ppm 2.2 1.9
Nitrogen oxides, ppm 340 640
Carbon monoxide, ppm 375 40
*ppm by volume for all gaseous pollutants.
114
-------
TABLE 47
CHEMICAL COMPOSITION OF PARTICIPATE EMISSIONS
(Quantitative Analyses)
Metallic Ions Reported as Oxides3
Sample Source
Baghouse Baghouse Baghouse Baghouse Millipore*
Catch Catch Catch Catch Filter
Test
Type of Glass
Components
Silica (SiOz)
Calcium oxide (CaO)
Sulfuric Anhydride (SOa)
Borix Anhydride (6203)
Arsenic Oxide (AszOa)
Chloride (Cl)
Lead Oxide (PbO)
K2O + Na2O
ALzOa
Fluoride
FezOa
MgO
ZnO
Unknown metallic oxide (RzOa)
Loss on ignition
No. 1
Amber,
wt%
0.03
1.70
46.92
3.67
7.71
0.01
0.39
29.47
10.10
No. 2
Flint,
wt%
0.3
2.3
25.1
1.3
28.1
3.5
8.6
30.8
No. 3
Amber,
wt%
0.1
0.8
46.7
26.1
0.1
0.5
25.7
No. 4
Flint,
wt%
4.1
19.2
30.5
36.5
0.2
0.6
1.4
7.5
No. 5
Flint,
wt%
3.3
39.4
39.2
6.5
11.6
"Stack test of baghouse exhaust
115
-------
4. The plumes from furnaces with ejector draft systems will have lower
opacities than furnaces with natural-draft stacks or induced-draft fans.3
Exhaust volumes from glass-melting furnaces can be computed from
the fuel requirements on the basis of combustion with 40 percent excess
combustion air. Figure 31 presents the fuel requirements for bridgewall-type,
regenerative furnaces fired with natural gas. The information presented
is based on furnaces constructed before 1955, which generally require
more fuel per ton of glass than do furnaces constructed since 1955.
Forty percent excess combustion air is chosen as representing average
combustion conditions. The fuel requirements of container furnaces at
maximum pull rates should be estimated by using a melter rating parameter
of 4 square feet of melter surface area per daily ton of glass. For
estimating the fuel requirements of non-bridgewall furnaces supplying glass
for sheet, rod, and tube manufacture, a melter rating parameter of 8
should be used.
Exhaust volumes from furnaces with ejector systems are usually 30
to 40 percent greater than exhaust volumes from furnaces with natural-draft
stacks or induced-draft fan systems. This is due to the ejector air,
which is mixed in the ejector with the furnace effluent.
The temperature of exhaust gases from furnaces with natural-draft
stacks or induced-draft fan systems usually ranges from 600 to 1,200ฐF
depending upon many variables, including furnace age. Exhaust gas
temperatures from furnaces with ejector systems are lower, varying from 400
to 600ฐF.
The exhaust gases from large, regenerative, gas-fired furnaces melting
three kinds of soda-lime glass were analyzed. The results of the chemical
analyses of the gaseous components produced are presented in Table 48.3
POLLUTION CONTROL CONSIDERATIONS
With regard to paniculate emissions, it appears that most uncontrolled
glass-melting furnace emissions are in, or very close to, compliance with
federal regulations. However, when burning U. S. Grade 5 fuel oil, they
usually have plumes exceeding 40 percent opacity. While burning natural
gas or U. S. Grade 3 fuel oil, the plumes from these same furnaces
are only 15 to 30 percent opacity.
In general, opacity is directly related to the amount of small sized paniculate
matter. There are many process variables that affect the emissions from
116
-------
3D
8
(0
i
09
2
o
o
m
NATURAL GAS CONSUMED.
OF GLASS
O
3D
m
5 2
3)
m
o
m
m
3D
I
m
n
3D
I
m
<2
0)
117
-------
TABLE 48
CHEMICAL COMPOSITION OF GASEOUS EMISSIONS
FROM GAS-FIRED, REGENERATIVE FURNACES1
Gaseous Components
Nitrogen, vol %
Oxygen, vol %
Water vapor, vol %
Carbon dioxide, vol %
Carbon monoxide, vol %
Sulfur dioxide (862), ppm
Sulfur trioxide (SOa), ppm
Nitrogen oxides (NO, NOz), ppm
Organic acids, ppm
Aldehydes, ppm
Flint
Glass
71.9
9.3
12.4
6.4
0
0
0
724
NA*
NA
Amber
Glass
81.8
10.2
7.7
8.0
0.007
61
12
137
50
7
Georgia
Green
72.5
8.0
12.1
7.4
0
14
15
NA
NA
NA
*NA = not available.
118
-------
glass-melting furnaces. If these variables are changed as described below,
they will tend to decrease participate emissions:
1. Decrease the total sulfate (SOซ) content of the batch charge.
2. Decrease the quantity of <325-mesh fines in the batch charge.
3. Increase the cullet content of the batch charge.
4. Decrease the amount of fuel required to melt a ton of glass.
(This variable is largely influenced by the mechanical design of
the furnace, in particular, the checker design.)
5. Improve the combustion efficiency.
6. Improve regenerator efficiency by performing furnace reversals
in relation to checker temperatures instead of at fixed periods
of 15 to 20 minutes. This would serve to maximize the conservation
of heat, and thereby minimize fuel consumption.
There has been little work done with regard to the application of
pollution control systems to glass-melting furnace emissions. Fabric
filters, electrostatic precipitators, and high energy Venturi scrubbers have been
tested to a limited degree.
Electrostatic Precipitators
Electrostatic precipitators are suitable for collection of fine particles such
as those emitted from glass furnaces. Costs, however, tend to be high for small
gas volumes compared to other types of collectors. Electrostatic precipitators
can become more economically competitive if several small melting furnaces
in one plant are manifolded together to produce a relatively large exhaust
gas volume.
Wet Scrubbers
Low energy, wet, centrifugal scrubbers have been applied to controlling
emissions from glass-melting furnaces. The collection efficiency for these
devices was only about 50 percent.3 Experimental work is currently being
done with high energy venturi scrubbers. This type of scrubber can provide
high collection efficiency when operated at a high pressure drop.
The main disadvantages of the Venturi scrubber include the high operating
cost due to the high pressure drop across the throat section and the cost of
removal and safe disposal of slurries and sludges from the system.
119
-------
Fabric Filters
Fabric filters have an inherently high collection efficiency, provide for
dry product recovery and are relatively simple in their construction and operation.
Disadvantages of fabric filters include a temperature limitation of 550ฐF
and high bag replacement costs. Gas inlet temperatures to the filter must
be controlled above the dew point temperature, to prevent the formation of
a mud which will blind the filter, and below the temperature limitation of the
bag material. Also, at temperatures below the dew point there is rapid chemical
attack of the fabric material.
With the pilot bag filters tested to date, the furnace effluent
has been cooled below the maximum safe operating temperature for the
particular fabric under consideration. The methods used to cool the furnace
effluent have included: air dilution, radiation cooling columns, air to gas
heat exchangers, and evaporative coolers. The most trouble free method,
but one which requires the largest fabric filter, is air dilution. Heat exchangers
and radiation ductwork are subject to rapid fouling from dust in the
effluent. Evaporative coolers, if not properly designed and installed, can
also pose problems with temperature control and condensation.
SPECIFICATIONS AND COSTS
Abatement specifications were written for electrostatic precipitators, wet
scrubbers, and fabric filters to remove particulates from the exhaust gas of both
a small and a large sode-lime, glass-melting furnace. Since opacity rather than
weight rate of particulate matter is the problem requiring control, only one efficiency
level was specified for each type of equipment. That level was chosen to correspond
to an expected clear stack, although a guarantee of the result could not be specified.
Estimates of capital cost and annual operating costs made by the bidders
for each system were averaged and presented in the cost tables and graphs
which follow this section.
Specifications for electrostatic precipitators for glass-melting furnaces are
shown in Tables 49 and 50. Cost data are presented in Tables 51 and 52 and
Figures 32 and 33. Annual operating cost data was supplied by only one of the
two bidders.
Bidders for these systems submitted the collector plate areas in addition
to their cost data. The areas were averaged and are tabulated below along
120
-------
with calculated drift velocities:
Plant Size Plate Area ft2 Calculated Drift Velocity, fps
Small 6400 0.14
Large 15100 0.14
Specifications for wet scrubbers are shown in Tables 53 and 54. Average
cost data are presented in Tables 55 and 56 and Figures 34 and 35. Bidders
for these systems submitted scrubber pressure drops and L/G ratios in addition
to their cost data. Average values are tabulated below:
Plant Size Scrubber AP, in. w.c. Scrubber L/G^gprn/lOOO ACFM
Small 63 8
Large 65 7
Specifications for fabric filter systems for glass-melting furnaces are
shown in Tables 57 and 58. Cost data are presented in Tables 59 and 60 and
Figures 36 and 37.
Combination shaker, reverse air type fabric filters with an air-to-cloth
ratio of about 1Va/1 were used for both the small and the large glass melting
furnace. One of the two bidders specified a precoat additive upstream of the
filter unit. This fact is footnoted on the operating cost table, but is not included
in the averaged cost data presented. It should be noted the bidders differed
greatly on the cost of many items. The relative difference between highest and
lowest was a factor of about two.
121
-------
TABLE 49
ELECTROSTATIC PRECIPITATOR PROCESS DESCRIPTION
FOR GLASS-MELTING FURNACE SPECIFICATION
A single electrostatic precipitator Is to remove paniculate matter from the exhaust gas
of a soda-lime, glass-melting furnace. The furnace is natural gas fired with No. 2 fuel oil
standby.
The exhaust gas is to be brought from the furnace exhaust ports to a location 30 feet
outside of the furnace enclosure 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 abatement system shall continuously reduce the furnace
outlet loading to the levels specified and shall include the following:
1. Precipitator with a minimum of three independent electrical fields in the direction of
gas How.
2. Fans sized with at least 20% excess capacity when operating at the design pressure
drop and 90% of the maximum recommended operating speed.
3. A safety interlock system which prevents access to the precipitator internals unless
the electrical circuitry is disconnected or grounded.
4. Automatic voltage control.
5. Dust hoppers and conveyors.
6. Rapping system which is adjustable in terms of both intensity and rapping period.
7. Dust storage with 24-hour capacity.
8. Necessary flow controls and dampers.
9. A model study for precipitator gas distribution.
10. Materials of construction will be ASTM A242 or approved equal.
122
-------
TABLE 50
ELECTROSTATIC PRECIPITATOR OPERATING CONDITIONS
FOR GLASS-MELTING FURNACE SPECIFICATION
Small Large
Glass Output, ton/day 100 300
Inlet Gas
Flow, ACFM 25,000 60,000
Temp., ฐF* 725 725
Flow.SCFM 11,200 26,800
% Moisture (vol) 12 12
Inlet Loading
Avg. Particle Size, p 0.25 0.25
Solids Rate, Ib/hr 16.9 40.5
Solids Loading, gr/DSCF .2 .2
Gas Composition, ppm
F 2.2 1.9
Cl 4.9 4.1
NO, 340 640
CO 375 40
Outlet Gas
Outlet .Solids Loading
gr/ACF 0.01 0.01
gr/DSCF .025 .025
Outlet Solids Rate, Ib/hr 2.11 5.05
Efficiency, wt % 88 88
'Can cycle up to 850ฐF during normal operation.
123
-------
TABLE 51
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR ELECTROSTATIC PRECIPITATORS
FOR GLASS-MELTING FURNACE
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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
Model Study
(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
Large
High Efficiency
Small
25,000
725
11,200
12
.08
16.9
25,000
725
11,200
12
.01
2.14
88
94,312
4,800
1,309
3,530
5,066
249,796
358,813
Large
60,000
725
26,800
12
.08
40.5
60,000
725
26,800
12
.01
5.14
88
152,285
6,700
3,067
4,120
8,280
339,321
i
,
513,773
124
-------
FIGURE 32
CAPITAL COST OF ELECTROSTATIC PRECIPITATORS
GLASS-MELTING FURNACE
6
5
A
to
o:
-| 105
9
8
8 I
U
4
I04
10*
TURNKEY COST
COLLECTOR PLUS AUXILIARIES
I I I
COLLECTOR COST ONLY
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
125
-------
TABLE 52
ANNUAL OPERATING COST DATA
(COSTS IN S/YEAR)
FOR ELECTROSTATIC PRECIPITATORS
FOR GLASS-MELTING FURNACE
Operating Cost Item
Operating Factor, Hr/Year 8,600
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
$0.011/kwh
16% of Cap
-
Medium Efficiency
Small
Large
High Efficiency
Small
240
75
315
550
550
6,467
6,467
7,332
57,410
64,742
Large
240
125
365
550
550
11,146
11,146
12,061
82,204
94,265
-------
FIGURE 33
ANNUAL COST OF ELECTROSTATIC PRECIPITATORS
FOR GLASS-MELTING FURNACE
I05
9
8
7
6
5
4
3
2
I04
9
8
7
6
5
4
3
2
1 ft
Of^
S^
_4*
X
^
j>
X
^
^*
_. ._
>
r
r
TOTAL A
1
TC
TA
.D
raNUAL COST
. . .
IRECT COST
te
o
u
tf
3456789 I05
CLEANED GAS FLOW, ACFM
127
-------
TABLE 53
WET SCRUBBER PROCESS DESCRIPTION
FOR GLASS-MELTING FURNACE SPECIFICATION
A wet scrubber is to remove paniculate matter from the exhaust gas of a glass-melting
furnace. The furnace is fired with No. 5 fuel oil using 40 percent excess combustion air.
The exhaust gas is to be brought from the furnace exhaust ports to a fan located
30 feet outside of the furnace enclosure. The scrubber will be located before the fan
in an area free of space limitation. Fresh make-up water is available and is to be
added to the recirculation tank. The scrubber is to operate so as to continuously reduce
the furnace outlet loading to the levels specified.
The scrubbing system should include the following:
1. Venturi scrubber with a cyclonic entrapment separator constructed of carbon steel
lined with FRP or rubber with a precooler constructed of Incoloy or brick lined
carbon steel. The scrubber internals should be either Incoloy or fiberglass reinforced
polyester.
2. Recirculation tank and pumps.
3. Fifty-foot stack following scrubber.
4. Slurry settler, which will handle a portion of the recirculation pump discharge and
be capable of producing a reasonably thickened underflow product.
5. Fans sized with at least 20% excess capacity when operating at the design pressure
drop and 90% of the maximum recommended operating speed.
6. Necessary controls.
7. Packing glands flushed with fresh water to prevent binding of the seals.
128
-------
TABLE 54
WET SCRUBBER OPERATING CONDITIONS
FOR GLASS-MELTING FURNACE SPECIFICATION
Glass Output, tonlday
Inlet Gas
Flow, ACFM
Temp., ฐF
Flow, SCFM
% Moisture (vol)
Inlet Loading
Solids Rate, Ib/hr
Solids Loading, gr/DSCF
Avg. Particle Size, p
SOj Loading, ppm
SOi Loading, ppm
Fluorine Loading, ppm
Chlorine Loading, ppm
Nitrogen Oxides, ppm
Carbon Monoxide, ppm
Outlet Gas
Flow, ACFM
Temp., "F
% Moisture (vol)
Flow DSCFM
Outlet Solids Loading
gr/ACF
grIDSCF
Outlet Solid Rate, Ib/hr
Efficiency, wt %
Wet Scrubber A/>, in. w.c."
Recirculation L/G, GPMI1000 ACFM, out
"Supplied by the bidders
Small
100
25,000
725
11,200
12
15.500
152
26
9,900
0.01
0.02
1.33
92
63
8
60,000
725
26,800
12
16.9
.2
.25
250
17
2.2
4.9
340
375
40.5
.2
.25
315
15
1.9
4.1
640
40
37,200
152
26
23,800
0.01
0.02
3.19
92
65
7
129
-------
TABLE 55
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS
FOR GLASS-MELTING FURNACE
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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
Large
High Efficiency
Small
25,000
725
11,200
12
.08
16.9
15,500
152
13,400
26
.01
1.33
92
13,983
37,363
1,725
175
17,493
8,233
3,950
62,298
145,220
Large
60,000
725
26,800
12
.08
40.5
37,200
152
32,200
26
.01
3.19
92
22,418
70,455
2,698
250
30,493
8,828
3,950
82,518
221,610
130
-------
6
5
A
I05
9
8
7
6
FIGURE 34
CAPITAL COST OF WET SCRUBBERS
FOR GLASS-MELTING FURNACE
TURNKEY COST
COLLECTOR PLUS AUXILIARIES
fe
o
u
COLLECTOR COST ONLY
3 4 5 6 7 8 9 10ฐ
CLEANED GAS FLOW, ACFM
131
-------
u
to
TABLE 56
ANNUAL OPERATING COST DATA
(COSTS IN S/YEAR)
FOR WET SCRUBBERS
FOR GLASS MELTING FURNACE
Operating Cost Item
Operating Factor, Hr/Year 8,600
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
$0.011/kwh
$0.25/MGal
$0.05/MGal
16% of Cap
Medium Efficiency
Small
Large
High Efficiency
Small
6,300
1,600
7,900
1,950
750
2,700
1,250
1,250
17,683
1,506
353
19,542
31,392
23,235
54,627
Large
6,300
1,600
7,900
1,950
875
2,825
2,375
2,375
42,834
3,264
844
46,942
60.042
35,458
95,500
-------
FIGURE 35
ANNUAL COST OF WET SCRUBBERS
FOR GLASS-MELTING FURNACE
6
5
A
_J
8
9
8
7
5
4
TOTAL ANNUAL COST
10*
TOTAL
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
133
-------
TABLE 57
FABRIC FILTER PROCESS DESCRIPTION
FOR GLASS-MELTING FURNACE SPECIFICATION
A fabric filter is to remove paniculate matter from the exhaust gas of a glass-melting
furnace. The furnace is fired with No. 5 fuel oil using 40 percent excess combustion air.
The exhaust gas is to be brought from the furnace exhaust ports to a location 30 feet
outside of the furnace enclosure by means of a fan. The fabric filter will be at ground
level in an area beyond the ductwork which is free of space limitations. The fan will
precede the fabric filter. The abatement system shall continuously reduce the furnace
outlet loading to the levels specified and shall include the following:
1. Compartmented fabric filter operating with positive pressure.
2. Fan sized with at least 20% excess capacity when operating at the design pressure
drop and 90% of the maximum recommended operating speed.
3. A surface cooler to lower the temperature of the gas going to the fabric filter to
=s425T during normal operation.
4. Compartmented design of the fabric filter which permits shutdown of one section
for maintenance.
5. Bags with a temperature rating of ^500ฐF.
6. A high temperature by-pass around the fabric filter for use during operational upsets.
7. Dust hoppers and conveyors.
8. Materials of construction capable of handling furnace exhaust gas containing the
following:
Component Average Concentration, ppm
SO2 250
S03 17
F 2.2
Cl 4.9
NO, 340
134
-------
TABLE 58
FABRIC FILTER OPERATING CONDITIONS
FOR GLASS-MELTING FURNACE SPECIFICATION
Small Large
Glass Output, ton/day 100 300
Gas to Surface Cooler
Flow, ACFM 25,000 60,000
Temp., ฐF* 725 725
Flow, SCFM 11,200 26,800
% Moisture (vol) 12 12
Gas to Collector
Flow, ACFM 18,700 44,750
Temp., ฐF* 425 425
Flow, SCFM 11,200 26,800
% Moisture (vol) 12 12
Inlet Loading
Solids Rate, Iblhr 16.9 40.5
Solids Loading, gr/DSCF .2 .2
Avg. Particle Size, /^n 0.25 0.25
Outlet Loading
Solids Rate, Iblhr 1.6 3.84
Solids Loading, grIACF 0.01 0.01
Solids Loading, gr/DSCF .019 .019
Efficiency, wt % 91 91
Air to Cloth Ratio, ACFMIft2'" 1.5 1.5
'Can cycle up to 850ฐF during normal operation
"Supplied by the bidders
135
-------
TABLE 59
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR FABRIC FILTERS
FOR GLASS-MELTING FURNACE
,
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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
Large
High Efficiency
Small
25,000
725
11,200
12
.10
16.9
18,700
425
11,200
12
.01
1.6
91
78,871
7,673
8,823
21,871
3,619
17,838
10,000
8,229
2,090
7,500
500
27,375
*
7,830
1,060
3,000
57,911
264,190
Large
60,000
725
26,800
12
.10
40.5
44,750
425
26,800
12
.01
3.84
91
147,338
15,730
11,744
47,432
4,563
22,450
17,250
12,696
3,120
10,000
850
45,638
*
11,515
1,560
4,000
112,983
468,949
136
*Included in (1) above
-------
FIGURE 36
CAPITAL COST OF FABRIC FILTERS
FOR GLASS-MELTING FURNACE
6
5
4
TURNKEY COST
COLLECTOR PLUS AUXILIARIES
-J I05
Q 9
* 8
te" 7
8 6
5
4
COLLECTOR COST ONLY
I04
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
137
-------
TABLE 60
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR FABRIC FILTERS
FOR GLASS-MELTING FURNACE
Operating Cost Item
Operating Factor, Hr/Year 8,600
Operating Labor (if any)
Operator
Supervisor
Total Operating Labor
Maintenance
Labor
Materials ง Replacement Parts
Total
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.
$0.011/kwh
16% of Cap
Medium Efficiency
Small
Large
High Efficiency
Small
2,681
835
3,516
1,679
11,773
13,452
16,763
16,763
33,731
42,270
76,001
Large
3,984
' 922
4,906
2,674
22,108
24,782
30,739
30,739
60,427
75,032
135,459
*0ne bidder recommended the use of a precoat at a cost of $2,000 and $4,200 for the small and large
fabric filters.
-------
FIGURE 37
ANNUAL COST OF FABRIC FILTERS
FOR GLASS-MELTING FURNACE
D
5
4
3
2
-j 10s
Q 9
ฐ 8
, 7
r- '
(T>
8 6
5
4
3
2
I04
l(
_x
>gr
x^
xj
x
^
x
r
X
x
x
X
^
x^
^
^
7
TO
TA
.A
4NUAL COST
TOTAL DIRECT COST
)4 2 3456789 I05 2 34
CLEANED GAS FLOW, ACFM
139
-------
REFERENCES
1. Shand, E. B., Glass Engineering Handbook, McGraw-Hill Book Company,
Inc., New York, 1958.
2. Stockham, John D., "The Composition of Glass Furnace Emissions," Journal
of the Air Pollution Control Association, November, 1971, pp. 713-715,
3. Air Pollution Engineering Manual, U. S. Dept. of Health, Education, and
Welfare, Public Health Services Publication No. 999-AP-40, Cincinnati,
Ohio, 1967, pp. 720-738.
4. "A Screening Study to Develop Background Information to Determine the
Significance of Glass Manufacturing," Prepared by The Research Triangle
Institute, RTI Project No. 41U-762-Task 3, for The Environmental Protection
Agency under Contract No. 68-02-0607-Task 3, Dec., 1972.
5. Shreve, Norris R., The Chemical Process Industries, McGraw-Hill Book
Company, Inc., New York, 1956.
140
-------
5. CRUSHED STONE AND AGGREGATE INDUSTRY
The art of obtaining stone from the earth's crust is quarrying. Quarrying
is referred to as open-pit mining when applied to ore bearing stone, and strip
mining when applied to coal mining.
Rocks that are quarried for commercial use fall into three general classifications:
igneous, sedimentary, and metamorphic. Igneous rock is that formed by volcanic
action or great heat; sedimentary rock is that formed by the deposit of sediment;
and metamorphic rock is that formed from igneous or sedimentary rock which
has undergone a change in structure due to intense pressure, heat, or chemical
reaction.
Two main products of the quarrying industries are dimension stone and
crushed and broken stone. The term dimension stone is applied to blocks or
slabs of natural stone that are cut to definite shapes and sizes. Crushed and
broken stone generally consists of irregular fragments produced by passing the
stone through crushers.
In quarrying dimension stone, blocks must be removed with care to preserve
their strength and weather resistance. The principal uses of dimension stone
are exterior and interior building construction. Granites and marbles are also
used extensively for memorials ranging from headstones to elaborate mausoleums.
Slate is used for roofing, stair treads, blackboards, and many other applications.
Sandstones are used as building stone and for abrasive wheels.
Although the use of stone in fragmentary form is a comparatively recent
development (the first crushing machine was patented in 1830), the crushed
stone industry has far outstripped the dimension stone industry in tonnage.
The chief varieties of rock used are limestone, sandstone, granite, and traprock
(which includes diabase, basalt and gabbro). Since the stone is used in small
fragments, explosives are used for shattering.
The first operation in preparation for blasting is to drill a series of deep holes
in rows. A churn drill or well drill is often used to sink holes 6 inches or more in
diameter and 50 or more feet deep.2 In large quarries 40 or more holes may be
drilled for a single blast. The size of the charge in each hole is determined by the
toughness of the rock. The charges may be fired in progression or simultaneously.
A single blast may throw down 20,000 or more tons of broken stone.
The broken stone is loaded by large capacity power shovels and then
transported to primary crushers where it is reduced to an average size of about
six inches. The desired fines are separated by scalping and screening, and
the larger sizes are further reduced by smaller secondary and tertiary crushers.
141
-------
Crushed stone is used chiefly for road building, cement manufacturing, for
agricultural purposes, in metallurgical fluxes, concrete aggregate and railroad track
ballast. Limestone has special uses in many chemical applications.
PROCESS DESCRIPTION
Quarrying, or open-pit mining, is a common method used to extract
consolidated ore or rock deposits that are located at or near the earth's surface.
Open-pit mining consists of the following steps:
1. Site preparation constructing access roads, designating dump sites,
and clearing vegetation and other obstructions.
2. Removal and disposal of overburden.
3. Excavation and collection of the deposit.
4. Transportation of the mined resource for processing.
The drilling of shotholes and exploratory boreholes in hard rock is an
essential part of all quarrying operations. There has been continual progress
in the development of more efficient rock drills and drilling accessories. Two
main types of wet percussive drill have emerged; the internal or axial water
feed machines, and the external or flush-head machines. Great advances have
also been made in the development and manufacture of various types of dust
extraction and filtration devices, thus enabling the drilling to be performed
without the aid of water.
In hard-rock mining, special arrangements have to be made to protect
workers against dust and fumes. Holes are drilled, charged, and fired according
to a prearranged program. The actual firing of explosives is done near the
end of the shift when nearly all the workers are out of the mine.
After blasting, various types of mechanical equipment are used for picking up
the spoil and loading it into cars or onto a conveyor. Scraper loaders that draw
the spoil up a ramp into cars are also used. A further development of this
principle involves the use of a power shovel in conjunction with a scraper
that is mounted on a train of cars and distributes the spoil throughout the
length of the train. Although sometimes sent to large capacity bins first, the rock
in most cases is delivered directly to the primary crusher plant by rail, rope
haulage, conveyor belt, or diesel truck. Commonly, broken stone is loaded into
large-haul (20 to 75-ton capacity) trucks by front-end loaders or shovels. The rock
is then hauled via unimproved roads to the processing plant or primary crusher
142
-------
truck dump. The usual crushing plant, situated either at the mine or at the mill,
consists of jaw or gyratory crushers as the primary stage, followed by gyratory,
cone, or impact crushers for the final stages.
The processing consists of screening out the usable sizes and crushing the
oversize rock into smaller usable size ranges. A simplified flow diagram for a
typical plant is shown in Figure 38. Incoming material is routed through a primary
crusher which crushes rocks larger than six inches. The product from this crusher
is screened for further processing. The undersize goes to a final screening plant
and the oversize to the secondary crushing plant. The secondary crushers are
of the gyratory, cone, or impact type. In a few large plants, two or three primary
crushers are used in parallel, followed by any number of secondary crushers which
may or may not be in parallel.
Jaw crushers have two crushing plates (jaws), usually with one pivoted,
and moving alternately toward or away from each other. Maximum size feed
is about 80 inches in diameter and usual reduction ratios (ratio of feed size
to product size) are about 5:1 to 8:1.
Gyratory crushers have an outer stationary face which is a vertical,
truncated conical shell (concave) with the smaller diameter at the bottom.
The inner movable face is a similar shell (crushing head) mounted on a spindle,
with the smaller diameter at the top. The movement of the spindle causes
the crushing head to gyrate, alternately moving toward and away from all
the points on the circumference of the concave. Maximum size feed is about
80 inches and usual reduction ratios are about 5:1 to 8:1.
A cone crusher is a modification of the gyratory crusher, and is specially
adapted to fine crushing. Maximum feed size for cone crushers is about 17
inches. Average reduction ratios are about 6:1 to 8:1. Feed size is usually
restricted to about 80% of the feed opening.
Impact crushers such as the hammermill ordinarily consist of a frame or
housing, a central rotating shaft on which the hammers are mounted, and a set
of grates which are circumferentially arranged in the lower section of the housing.
Rotational kinetic energy is transmitted from the hammers to the rock, and the rock
is shattered into smaller fragments. By increasing the number of these shattering
stages, size reductions of 20:1 may be realized in open circuit for 3 to 6 inch
diameter rock.
NATURE OF THE GASEOUS DISCHARGE
Particulate matter produced during open-pit mining operations is usually
143
-------
OVERSIZE
FROM PIT
i.
3/4- IN,
GRAVEL
STORAGE
PRIMARY
CONE
CRUSHER
I-I/2-IN.
GRAVEL
STORAGE
PEA
GRAVEL
STORAGE
SCREEN
1
SECONDARv
CONE
C"USHER
ROCK
DUST
STORAGE
FIGURE 38
SIMPLIFIED FLOW DIAGRAM OF A TYPICAL ROCK GRAVEL PLANT
PINE
CRUSHED
ROCK
STORAGE
MEDIUM
CRUSHED
ROCK
STORAGF
LARGE
CRUSHED
POCK
STORAGE
-------
convected or permeated directly to the atmosphere, rather than being captured
by a local exhaust ventilation system. In other words, the emissions are fugitive
in nature. Since many open-pit mining operations have an indefinite operating
life, the installation of a fixed dust collecting system is economically impractical.
Therefore, fugitive dusts should be controlled at the point of operation. Drilling,
blasting, rock handling operations, and wind erosion are responsible for most
of the particulate matter emissions produced during open-pit mining.3
Water can be used in most open-pit mining operations to control the
generated dusts. In all cases, the use of rotary or percussive drills of various
types will lead to the production of some amounts of fine respirable dust.
The provision of an efficient water feed or some other method of dust control
is essential. It is also essential that all surfaces in the immediate vicinity be
watered down before drilling begins. This method is only effective at temperatures
above the freezing point of water.
The oldest method of combating dust from shotfiring is to fill a stretch of
road with a water fog. This fog assists in precipitating the dust and fumes
produced. It is delivered towards the face of the rock to be shotfired through
an air-water nozzle.
All scraping, loading and conveying operations are potential sources of
fugitive dust emissions. Oust production during scraping and loading operations
is best controlled by thorough and systematic watering when temperatures
are above the freezing point of water. The loose material should be watered
before scraping or loading begins and from time to time during operations so
that exposure of dry rock is avoided.
The transport of material from one piece of equipment to another is usually
accomplished by bucket elevators or, more frequently, by belt conveyors. A point
at which material enters or leaves a conveyor belt is called a conveyor transfer
point.
Dust emission in the rock crushing plant usually begins at the primary crusher
and continues with the conveyor transfer points and the succeeding crushers.
As the rock becomes smaller in size, dust emissions become greater. Dust
emissions exist at all conveyor transfer points, dumps, crushers and screens.
The nature and the quantity of emissions depend upon the type of rock, the
moisture content of the rock, and the kind of processing equipment that is used.
Table 61 summarizes the unit operations encountered in most rock and mineral
production operations. It also lists air pollution control techniques applicable to
these unit operations.
145
-------
TABLE 61
ROCK AND MINERAL PRODUCTION UNIT OPERATIONS'
OPERATION CONTROL TECHNIQUES*
A. Mining
Open pit and quarry roads Paving; periodic oiling, watering, CaCb cover,
and/or cleaning; covering trucks to prevent
spillage.
Blasting Controlling size of blast, using water sprays
immediately after blasting and blasting only
when wind direction and other meterological
conditions are such that "neighborhood dust-
ing" will not occur. Using "blasting mats".
Drilling . Wet drilling (not fully accepted) or local
exhaust ventilation.
B. Transportation and storage
Conveyor belts Enclosure and local exhaust ventilation.
Elevators Enclosure and local exhaust ventilation.
Discharge chutes Telescoping chutes or adjustable chute heads
to permit discharge point to be close to
surface of pile. Spray or local exhaust ventila-
tion at discharge point.
Storage piles Enclosure (silos, bins, etc.).
C. Size reduction
Crushing & grinding Enclosure and local exhaust ventilation. Wet
sprays and/or exhaust hoods at crusher inlet
and outlet.
D. Concentration, classification
& mixing Enclosures and local exhaust ventilation.
Where possible employ wet sprays.
'Watering is not effective in keeping down dust at temperatures below freezing.
146
-------
POLLUTION CONTROL CONSIDERATIONS
Dust emissions from crushed stone and aggregate production operations
originate from three main sources:
1. Fugitive emissions from drilling, blasting, and rock handling operations.
2. All elevator and belt conveyor transfer points, all crusher discharge
points and all screens.
3. Plant roads and stockpiles.
The fugitive emissions should be controlled by preventing their occurrence.
When temperatures are above freezing this is accomplished, as discussed
in the previous section, through the liberal use of water at the point at which
the emissions might otherwise be generated.
The points that require hooding and ventilation should be enclosed as
completely as possible and plant design should incorporate minimum material
falls. A minimum indraft velocity of 200 fpm should be maintained through
all open areas. The following rules are also a guide to the amount of ventilation
air required.1
1. Conveyor transfer points require between 350 and 500 cfm per foot of
belt width for belt speeds of less than 200 fpm and 500 to 600 cfm per ft of
belt width for belt speeds between 200 and 400 fpm.
2. Bucket elevators require a tight casing with a ventilation rate of 100
cfm per square foot of casing cross section.
3. Vibrating screens require a minimum of 50 cfm per square foot of screen
area, with no increase for multiple decks.
The most commonly used type of dust collection device is the fabric filter.
In large facilities that maintain continuous operation, compartmented fabric filters
capable of cleaning themselves during operation are required. Smaller facilities
can use equipment that must be cleaned while shut down. Cotton sateen or
dacron polyester bags are commonly used. The dust is collected dry by the
fabric filter and can be a saleable product.
Medium and high energy wet scrubbers have also been applied to control
dust emissions in this industry. They are often preceded by a dry mechanical
collector. The dust is collected in the scrubber as a slurry, is not saleable, and
must be disposed of in other ways.
147
-------
SPECIFICATIONS AND COSTS
Cost data were obtained for emission control systems for two typical types
of sources: rock crushers and conveyor transfer points. Both fabric filter and
high energy wet scrubber systems were studied for each type of source.
Rock Crushers
Specifications were written for fabric filters and wet scrubbers to control
the combined emissions from secondary and tertiary rock crushers. Specifications
were written for each of two model plant sizes. In the case of wet scrubbers, two
collection efficiency levels were specified for each plant size. Only one efficiency
level was specified for the fabric filters. Volumetric flow rates and other parameters
that were representative of plants in the industry were selected on the basis of
information compiled by the National Crushed Stone Association.
The specifications for wet scrubbers are shown in Tables 62 and 63. Averaged
capital and operating cost data for the systems bid from these specifications
are presented in Tables 64 and 65 and in Figures 39, 40, 41, and 42. In addition
to the cost data, bidders reported scrubber pressure drops and L/G ratios for
the systems they bid. Averaged values for these data are tabulated below.
Plant Flow Rate Collection Scrubber AP Scrubber L/G
Size ACFM Efficiency in w.c. gpm/1000 ACFM (outlet)
7 9
17 13
9 9
16 13
The specifications for fabric filters are shown in Tables 70 and 71. Averaged
capital and operating cost data for control systems bid from these specifications
are presented in Tables 72 and 73 and in Figures 47 and 48. In addition to
cost data, the bidders reported the air-to-cloth ratio for their unit. These data
were averaged and are tabulated below:
Flow Rate Filter Air-to-Cloth Ratio,
Plant Size ACFM ACFM/ft2
Small 20,000 4.5
Large 70,000 4.5
Small
Small
Large
Large
20,000
20,000
70.000
70,000
Medium
High
Medium
High
148
-------
Convenor Transfer Points
Specifications were also written for fabric filters and wet scrubbers applied
to typical conveyor transfer points. A factor of 500 ACFM per linear foot of belt
width was utilized to determine volumetric flow rates for the transfer points in
the model plants. Hoods from 54", 30" and 36"-wide belt conveyors were ducted
together for the small plant. The large plant had eight transfer points which
included four 54" and four 36"-wide conveyor belts. Wet scrubber specifications
for the transfer point applications are shown in Tables 66 and 67. Average capital
and operating cost data are presented in Tables 68 and 69 and in Figures-43,
44, 45 and 46. In addition to cost data, bidders reported the scrubber pressure
drop and L/G ratio which pertains to their bid. Averaged values are tabulated
below:
Flow Rate, Collection Scrubber AP Scrubber L/G
ACFM Efficiency in w.c. qpm/1 OOP ACFM (outlet)
5000 Medium 7 8
5000 High 12 9
15000 Medium 7 9
15000 High 12 9
The data for the high efficiency cases indicate that less severe conditions
are required, at comparable collection efficiency, for conveyor transfer point
applications than for crusher applications.
The specifications for fabric filters are shown in Tables 74 and 75. Averaged
capital and operating cost data for the systems bid from these specifications
are presented in Tables 76 and 77 and in Figures 49 and 50. Bidders reported
the air-to-cloth ratios for the fabric filters in addition to their cost data. Average
values are tabulated below:
Transfer Point Flow Rate Air-to-Cloth Ratio
ACFM ACFM/ft2
5000 5.0
15000 5.2
These values average about 10% higher than the corresponding values for the
units quoted for crusher applications.
149
-------
TABLE 62
WET SCRUBBER PROCESS DESCRIPTION
FOR SECONDARY AND TERTIARY ROCK CRUSHER SPECIFICATION
A scrubber is to remove the rock dust exhausted from the secondary and tertiary
crushers of a rock crushing plant. Hoods will be supplied by the bidder. The exhaust
points will be ducted together and brought to the inlet of the scrubber. The amount
of inlet ductwork required will be 100 ft.
The scrubber will be located in an open area. Fresh make-up water and sufficient
power are available. The scrubbing system will consist of 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 reclrculation pump discharge and
be capable of producing a reasonably thickened underflow product while returning
water treated to minimize solids content. Slurry withdrawal should be set to maintain
10% (by weight) solids when operating at design capacity.
4. Two filters (one standby) to dewater the slurry product, capable of producing a
cake with a minimum 65% (by weight) solids.
5. Fan sized with at least 20% excess capacity when operating at the design pressure
drop and not more than 90% of the maximum recommended operating speed.
6. Necessary controls.
7. Carbon steel construction.
150
-------
TABLE 63
WET SCRUBBER OPERATING CONDITIONS
FOR SECONDARY AND TERTIARY ROCK CRUSHER SPECIFICATION
Two sizes of wet scrubbers are to be quoted for each of two efficiency levels.
Vendor's quotations should consist of four separate and independent quotations.
Process Wt., ton/hr
No. of Crushers Hooded Together
Inlet Gas
Flow, ACFM
Temp., ฐF
Flow, SCFM
Solids Loading
gr/ACF
grIDSCF
Iblhr
Flow, ACFM
Scrubber, AP, in. w.c.
Solids Loading
gr/ACF
gr/DSCF
Iblhr
Collector Efficiency, wt %
Flow, ACFM
Scrubber, AP, in. w.c.
Solids Loading
gr/ACF
gr/DSCF
Iblhr
Collector Efficiency, wt %
SmaH
300
2
20,000
80
19,600
5.25
5.70
900
Medium Efficiency
Large
1,200
2
70,000
80
68,700
6.00
6.50
3,600
20,000
0.23
0.25
40
95.6
High Efficiency
20,000
0.01
0.011
1.7
99.8
70,000
0.076
0.076
40
98.9
70,000
0.01
0.011
6.0
99.8
'To be supplied by vendor as a part of his quotation. Vendor should also supply required
liquid circulation rate.
151
-------
TABLE 64
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS
FOR SECONDARY AND TERTIARY ROCK CRUSHERS
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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
20,000
80
19,600
5.25
900
20,000
80
19,600
2
.23
40
95.6
14,491
5,522
2,699
2,400
3,113
9,887
81,116
2,333
121,561
Large
70,000
80
68,700
6.00
2,600
70,000
80
68,700
2
.07
40
98.9
34,148
18,092
5,175
6,932
4,036
18,220
127,650
2,333
216,586
High Efficiency
Small
20,000
80
19,600
5.25
900
20,000
80
19,600
2
.01
1.7
99.8
14,156
14,253
5,598
5,200
4,016
9,887
86,807
2,333
142,250
Large
70,000
80
68,700
6.00
3,600
70,000
80
68,700
2
.01
6.0
99.8
34,556
28,290
5,924
6,932
5,084
18,220
138,566
2,333
239,905
152
-------
TABLE 65
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS
FOR SECONDARY AND TERTIARY ROCK CRUSHERS
Operating Factor, Hr/Year 8,500
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
s
&6/hr. \
&8/hr. ;
./
&6/hr.
ฃ0.011/kwh
$0.25/MGal
16% of Cap
Medium Efficiency
Small
6,086
6,086
4,540
850
5,390
3,992
3,992
6,409
603
7,012
22,480
19,450
41,930
Large
7,027
7,027
5,875
1,267
7,142
5,733
5,733
31,014
2,157
33,171
53,073
34,654
87,727
High Efficiency
Small
6,086
6,086
4,540
1,150
5,690
5,367
5,367
10,911
606
11,517
28,660
22,760
51,420
Large
7,027
7,027
5,875
1,600
7,475
6,400
6,400
39,180
2,159
41,339
62,241
38,385
100,626
CJl
w
-------
COST, DOLLARS
ro
n
r
rn
o
O
o
2
ro
ro
O) -4 00 CO O
in
co ^ en o
\
OH
> >
a r
-3 -< ซ
e OH
3 HO
n
Tl
5
a
m
o
-------
FIGURE 40
ANNUAL COST OF WET SCRUBBERS
FOR SECONDARY AND TERTIARY ROCK CRUSHER
(Medium Efficiency)
6
5
4
-} I05
Q 9
2 8
ฃ 7
O 6
U
4
TOTAL ANNUAL COST
TOTAL DIRECT COST
10*
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
155
-------
FIGURE 41
CAPITAL COST OF WET SCRUBBERS
FOR SECONDARY AND TERTIARY ROCK CRUSHERS
(High Efficiency)
6
5
4
TURNKEY COST
Q 9
Q 8
i-
4
3
COLLECTOR PLUS AUXILIARIES
I04
10*
COLLECTOR COST ONLY
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
-------
FIGURE 42
ANNUAL COST OF WET SCRUBBERS
FOR SECONDARY AND TERTIARY ROCK CRUSHERS
(High Efficiency)
D
i in5
i
y y
d Q
o
L* 7
f- /
0 6
U
s
in*
,i
^
s
_x
^
X
r
_xi
X
x
^
^^
x*
X
-rf
X
X
>
^
^
7
f
T<
ITA
)TA
L ANNUAL COST
10*
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
157
-------
TABLE 66
WET SCRUBBER PROCESS DESCRIPTION
FOR CRUSHED STONE AND AGGREGATE CONVEYOR
TRANSFER POINTS SPECIFICATION
A scrubber is to remove the rock dust exhausted from the conveyor transfer points
In a rock crushing plant. Hoods will be supplied by the bidder. Exhaust points
will be ducted together and brought to the inlet of the scrubber. The number of
hoods involved and their total face area is shown in the operating conditions. The
inlet ductwork required will be 50 ft/hood. Duct velocity will be 3.500 ft/min.
The scrubber will be located In an open area. Fresh make-up water and sufficient
power are available. The scrubbing system will consist of the following:
1. Venturi scrubber with a cyclonic entrainment separator.
2. Reclrculation tank and pumps.
3. Slurry settler, which will handle a portion of the recirculation pump discharge, and
be capable of producing a reasonably thickened underflow product while returning
water treated to minimize solids content. Slurry withdrawal should be set to maintain
10% (by weight) solids when operating at design capacity.
4. Two filters (one standby) to dewater the slurry product, capable of producing a cake
with a minimum 65% (by weight) solids.
5. Fan sized with at least 20% excess capacity when operating at the design pressure
and not more than 90% of the maximum recommended operating speed.
6. Necessary controls.
7. Carbon steel construction.
-------
TABLE 67
WET SCRUBBER OPERATING CONDITIONS
FOR CRUSHED STONE AND AGGREGATE CONVEYOR
TRANSFER POINTS SPECIFICATION
Two sizes of wet scrubbers are to be quoted for each of two efficiency levels. Vendor's
quotations should consist of four separate and independent quotations.
No. of Hoods Ducted Together
Total Face Area of Hoods, ft2
Inlet Gas
Flow, ACFM
Temp., "F
Flow, SCFM
Solids Loading
gr/ACF
gr/DSCF
Ib/hr
Small
3
71
5,000
80
4,900
1.0
1.08
42.7
8
234
15,000
80
14,700
1.0
1.08
128
Medium Efficiency
Flow, ACFM
Scrubber, AP, in. w.c.
Solids Loading
gr/ACF
- gr/DSCF
Ib/hr
Collector Efficiency, wt %
5,000
0.04
0.045
1.7
96
15,000
0.04
0.045
5.1
96
Flow, ACFM
Scrubber, AP, In. w.c.
Solids Loading
gr/ACF
gr/DSCF
Ib/hr
Collector Efficiency, wt %
High Efficiency
5.000
0.01
0.011
0.4
99
15,000
0.01
0.011
1.3
99
'To be supplied by vendor as a part of his quotation. Vendor should also supply
required liquid circulation rate.
159
-------
TABLE 68
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS
FOR CRUSHED STONE AND AGGREGATE CONVEYOR TRANSFER POINTS
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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 J
Performance Test
Other "\
(4) Total Cost
Medium Efficiency
Small
5,000
80
4,900
2
1.0
42.7
5,000
80
4,900
2
.04
1.7
96
7,322
2,093
1,345
1,099
2,963
6,554
56,321
2,333
80,030
Large
15,000
80
14,700
2
1.0
128
15,000
80
14,700
2
.04
5.1
96
12,472
3,991
2,087
2,798
3,063
11,554
70,136
2,333
108,434
High Efficiency
Small
5,000
80
4,900
2
1.0
42.7
5,000
80
4,900
2
.01
.4
99
7,175
4,151
1,348
1,099
3,000
6,554
58,123
2,333
83,783
Large
15,000
80
14,700
2
1.0
128
15,000
80
14,700
2
.. .01
1.3
99
12,511
7,649
2,087
2,798
3,063
11,554
71,802
2,333
113,797
160
-------
TABLE 69
ANNUAL OPERATING COST DATA
(COSTS IN S/YEAR)
FOR WET SCRUBBERS
FOR CONVEYOR TRANSFER POINTS
Operating Cost Item
Operating Factor, Hr/Year 8.500
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. J
$6/hr.
$0.011/kwh
$0.25/MGal
16% of Cap
Medium Efficiency
Small
5,212
5,212
1,200
570
1,770
1,867
1,867
1,708
8
1,716
10,565
12,805
23,370
Large
6,121
6,121
1,200
690
1,890
2,250
2,250
5,550
24
5,574
15,835
17,349
33,184
High Efficiency
Small
5,212
5,212
1,200
670
1,870
2,225
2,225
2,464
8
2,472
11,779
13,405
25,184
Large
6,121
6,121
1,200
790
1,990
2,593
2,593
7,202
25
7,227
17,931
18,208
36,139
0>
-------
FIGURE 43
CAPITAL COST OF WET SCRUBBERS
FOR CONVEYOR TRANSFER POINTS FOR CRUSHED STONE AND AGGREGATE INDUSTRY
(Medium Efficiency)
9
8
7
6
5
A
< A
-J ICT
9
8
\- 7
8 6
COLLECTOR PLUS AUXILIARIES
COLLECTOR COST ONLY
IOJ
2 3 456789ICT
CLEANED GAS FLOW, ACFM
162
-------
FIGURE 44
ANNUAL COST OF WET SCRUBBERS
CRUSHED STONE AND AGGREGATE CONVEYOR TRANSFER POINTS
(Medium Efficiency)
to
IE
-------
FIGURE 45
CAPITAL COST OF WET SCRUBBERS
FOR CONVEYOR TRANSFER POINTS FOR CRUSHED STONE AND AGGREGATE INDUSTRY
(High Efficiency)
COLLECTOR PLUS AUXILIARIES
COLLECTOR COST ONLY
10
2 3 4 5 6 7 8 9 ICT
CLEANED GAS FLOW, ACFM
164
-------
FIGURE 46
ANNUAL COST OF WET SCRUBBERS
FOR CRUSHED STONE AND AGGREGATE CONVEYOR TRANSFER POINTS
(High Efficiency)
o
u
6
5
4
J 10'
8 I
\- 7
6
5
A
ICT
TOTAL ANNUAL COST
2 3 A ' 6 7 6 9 I04
CLEANED (, FLOW, ACFM
165
-------
TABLE 70
FABRIC FILTER PROCESS DESCRIPTION
FOR SECONDARY AND TERTIARY ROCK CRUSHER SPECIFICATION
A fabric filter is to remove rock dust from the exhaust from the ventilation hoods
located over the secondary and tertiary crushers of a rock crushing plant. Hoods will
be supplied by the bidder.
The exhaust gases will be ducted together and brought to the Inlet of the fabric
filter. The amount of Inlet ductwork required will be 100 ft. The fabric filter will
be located in an area free from space limitations. A fan located at the outlet of the
fabric filter will draw the exhaust gases through the system.
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 personnel 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 at negative pressure.
2. Maximum air-to-cloth ratio, when one compartment Is down for cleaning, of 5.0/7.
3. Dacron polyester bags.
4. Pulse-Jet type cleaning mechanism.
5. Trough hoppers with a minimum side and valley angle of 55ฐ.
6. Screw conveyor system with a rotary air lock at its end.
7. Fans sized with at least 20% excess capacity when operating at the design pressure
drop and 90% of the maximum recommended operating speed.
166
-------
TABLE 71
FABRIC FILTER OPERATING CONDITIONS
FOR SECONDARY AND TERTIARY ROCK CRUSHER SPECIFICATION
Process Wt., tonlhr
No. of Crushers Hooded Together
Inlet Gas
Flow, ACFM
Temp., ฐF
Flow, SCFM
Solids Loading
gr/ACF
gr/DSCF
Ib/hr
Small
300
2
20,000
80
19,600
5.25
5.70
900
Large
1,200
2
70,000
80
68,700
6.00
6.50
3,600
High Efficiency
Flow, ACFM 20,000
Solids Loading
gr/ACF
gr/DSCF
Ib/hr
Air-to-cloth Ratio'
Collector Efficiency, wt %
"To be supplied by vendor as a part of his quotation.
0.01
0.011
1.7
99.8
70,000
0.01
0.11
6.0
99.8
167
-------
TABLE 72
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR FABRIC FILTERS
FOR SECONDARY AND TERTIARY ROCK CRUSHERS
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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
\
?
Medium Efficiency
Small
Large
High Efficiency
Small
20,000
80
19,600
2
5.25
900
20,000
80
19,600
2
.01
1.7
99.8
35,166
6,177
825
4,557
6,316
38,437
2,000
93,478
Large
70,000
80
68,700
2
6.0
3,600
70,000
80
68,700
2
0.01
6.0
99.8
106,114
24,096
1,072
8,143
15,346
112,151
2,000
268,922
168
-------
FIGURE 47
CAPITAL COST OF FABRIC FILTERS
FOR SECONDARY AND TERTIARY ROCK CRUSHERS
6
5
A
-j I05
X 9
" 8
k" I
O 6
U
5
4
TURNKEY COST
v\
COLLECTOR PLUS AUXILIARIES
.COLLECTOR COST ONLY
I04
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
169
-------
TABLE 73
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR FABRIC FILTERS
FOR SECONDARY AND TERTIARY ROCK CRUSHERS
Operating Cost Item
Operating Factor, Hr/Year 8,500
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
$0.011/kwh
16% of Cap
Medium Efficiency
Small
Large
High Efficiency
Small
453
453
504
133
637
2,142
2,142
6,203
6,203
9,435
14,956
24,391
Large
453
453
1,240
433
1,673
7,541
7,541
21,784
21,784
31,451
43,028
74,479
-------
FIGURE 48
COST OF FABRIC FILTERS
FOR SECONDARY AND TERTIARY ROCK CRUSHERS
3
7
6
5
4
9
8
7
6
4
TOTAL ANNUAL COST
TOTAL DIRECT COST
(/)
8
10*
3456789 I05
CLEANFID GAS FLOW, ACFM
171
-------
TABLE 74
FABRIC FILTER PROCESS DESCRIPTION
FOR CRUSHED STONE AND AGGREGATE CONVEYOR
TRANSFER POINTS SPECIFICATION
A fabric filter Is to remove rock dust from the exhaust from ventilation hoods
located at conveyor transfer points In a rock crushing plant. Hoods will be supplied
by the bidder. Duct velocity will be 3.500 ftlmln.
The exhaust gases will be ducted together and brought to the Inlet of the fabric
filter. The number of hoods Involved and the total face area under all of the hoods
Is shown In the table of operating conditions. The Inlet ductwork required will be
50 ftlhood. The fabric filter will be located In an area free from space limitations.
A fan located at the outlet of the fabric filter will draw the exhaust gases through
the system.
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 personnel safety during filter operation.
No more than two bags must be removed to permit access to aH of the bags. The
dust collecting process should be continuous and should Include the following:
1. Compartmented fabric filter operating at negative pressure.
2. Maximum alr-to-doth ratio, when one compartment Is down for cleaning, of 6.011.
3. Dacron polyester bags.
4. Pulse-jet type cleaning mechanism.
5. Trough hoppers with a minimum side and valley angle of 55'.
6. Screw conveyor system equipped with rotary air lock.
7. Fans sized with at least 20% excess capacity when operating at the design pressure
drop and 90% of the maximum recommended operating speed.
172
-------
TABLE 75
FABRIC FILTER OPERATING CONDITIONS
FOR CRUSHED STONE AND AGGREGATE CONVEYOR
TRANSFER POINTS SPECIFICATION
Small Large
No. of Hoods Ducted Together 3 8
Total Face Area of Hoods, ft2 71 234
Inlet Gas
Flow. ACFM 5,000 15,000
Temp., "F 80 80
Flow, SCFM 4,900 14,700
Solids Loading
gr/ACF 1.0 1.0
gr/DSCF 1.08 1.08
Ib/hr 42.7 128
High Efficiency
Flow, ACFM 5,000 15,000
Solids Loading
gr/ACF 0.01 0.01
gr/DSCF 0.011 0.011
Ib/hr 0.4 1.3
Air-to-cloth Ratio"
Collector Efficiency, wt % 99 99
To be supplied by vendor as a part of his quotation.
173
-------
TABLE 76
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR FABRIC FILTERS
FOR CRUSHED STONE AND AGGREGATE CONVEYOR TRANSFER POINTS
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
gr/ACF
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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
I ^
(4) Total Cost ,
>
>
Medium Efficiency
Small
Large
High Efficiency
Small
5,000
80
4,900
2
1.0
42.7
5,000
80
4,900
2
.01
.4
99
10,290
2,041
83
2,093
1,230
12,683
2,000
30,420
Large
15,000
80
14,700
2
1.0
128
15,000
80
14,700
2
.01
1.3
99
22,297
4,772
109
3,925
3,435
25,211
2,000
61,749
174
-------
FIGURE 49
CAPITAL COST OF FABRIC FILTERS
FOR CRUSHED STONE AND AGGREGATE CONVEYOR TRANSFER POINTS
6
5
A
.
ir
< s
-i I05
Q 9
(^ o
I- 7
8 6
U
4
3
I04
-^TURNKEY COST
ฃ0CC.
COLLECTOR PLUS AUXILIARIES
COLLECTOR COST ONLY
10'
2 3 45678910*
CLEANED GAS FLOW, ACFM
3 4
175
-------
TABLE 77
ANNUAL OPERATING COST DATA
(COSTS IN S/YEAR)
FOR FABRIC FILTERS
FOR CRUSHED STONE AND AGGREGATE CONVEYOR TRANSFER POINTS
Operating Cost Item
Operating Factor, Hr/Year 8,500
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
$0.011/kwh
16% of Cap
Medium Efficiency
Small
Large
High Efficiency
Small
453
453
304
40
344
493
493
1,911
1,911
3,201
4,867
8,068
Large
453
453
416
90
506
1,150
1,150
3,319
3,319
5,428
9,880
15,308
-------
FIGURE 50
ANNUAL COST OF FABRIC FILTERS
FOR CRUSHED STONE AND AGGREGATE CONVEYOR TRANSFER POINTS
co
O
u
10
3 4 5 6 7 8 9 10*
CLEANED GAS PLOW, ACFM
2.
177
-------
REFERENCES
1. Air Pollution Engineering Manual. U. S. Dept. of Health, Education, and
Welfare, Public Health Services Publication No. 999-AP-40, Cincinnati, 1967.
2. Guide to the Prevention and Suppression of Dust In Mining, Tunnelling
and Quarrying, International Labour Office, Printed by Atar S.A., Geneva
(Switzerland), 1965.
3.. Stern, Arthur C., Air Pollution. Volume III, Academic Press, Inc., New York,
1968.
178
-------
6. ASPHALT SATURATION
Roofing paper and roofing shingles are manufactured by a process known
as asphalt saturation. In this process a vegetable felt base is impregnated
with petroleum derived asphalt materials which are called saturants. The felt
is made from vegetable fibers and is often produced in the same facility as
the finished roofing materials.
The industry producing these products consists of firms with a wide variation
in size. The Census of Manufacturers shows 226 firms engaged in this industry
in 1967.1 The average firm employed 65 people and shipped $2.65 million
of products. The complete distribution of firm sizes and product values is
presented in Table 78. Total shipments by this industry in 1971 were 7.9
million tons and this figure was projected to grow at a rate of approximately
3% per year.
PROCESS DESCRIPTION
The asphalt saturation process involves basically the application of a controlled
amount of asphalt to both sides of a dry felt sheet. The application is often
carried out by spraying the felt with hot asphalt and then dipping the felt into a
tank holding more hot asphalt. The dipping operation is usually totally enclosed
with a hood which is vented to the atmosphere. A schematic flow diagram of the
process is shown in Figure 51.
Raw Materials
There are two main raw materials used in the production of asphalt roofing;
asphalt saturant and felt.
Asphalt is a petroleum derived product. If is produced as the residual
bottoms product from the vacuum distillation of crude oil. It is principally hydrocarbon
in nature, but also contains oxygen, sulfur, nitrogen, metals, and other trace
elements chemically bonded to the hydrocarbon molecules. It is normally solid
at room temperature, having an initial boiling point in excess of 1000ฐF.
Asphalt, as produced from a crude unit in a refinery, is not viscous enough
to be used as saturant. Viscosity is increased by means of a treatment step
called asphalt blowing. This treatment consists of bubbling air through liquid
asphalt. Oxidation reactions occur during this treatment which lead to polymerization
of the hydrocarbons and some reduction of the hydrogen content. In the roofing
179
-------
TABLE 78
NUMBER OF ESTABLISHMENTS AND VALUE OF SHIPMENTS
OF ASPHALT SATURATED PRODUCTS BY SIZE CLASS*
Value of
Number of Shipments
Establishments (million dollars)
1 to 4 Employees 33 5.6
5 to 9 Employees 22 10.2
10 to 19 Employees 33 29.6
20 to 49 Employees 46 59.0
50 to 99 Employees 44 132.0
100 to 249 Employees 42 276.0
250 to 499 Employees 4 31.6"
500 to 999 Employees 2 53.8"
Total 226 597.8
*1967 Data
"Estimate, based on output per employee
180
-------
ASPHALT HEATERS
n
FEED
HOPPER.
SAND
DRYER
SCREEN
GRANULE
STORAGE
PNEUMATIC FEED
FROM
TRUCK
DRY DRY
FELT LOOPER
00
DRIVEN PULLEY FEEDS
FELT TO HOPPER
LOOPING RUNGS
DRIVEN AT CON-
STANT SPEED
TO
SPROCKET
SATURATING TANK
FIGURE 51
SCHEMATIC FLOW DIAGRAM OF ASPHALT SATURATION PROCESS3
-------
products industry, the air-blown asphalt is called saturant (or coating asphalt) and
is characterized by its softening point which is typically 100 to 140ฐF. In the
saturating process, it is handled at 400 to 500ฐF where it is fluid enough to be
applied to the felt in controlled thicknesses.
Felt is a fibrous paper product produced from vegetable matter. It is commonly
characterized by two properties: weight .and moisture content. Weight is a term
for the thickness of the felt. Several standard felt weights are produced for use
in different products. Moisture content of the felt is an important property since
it affects the quality of the saturator product. Excessive moisture can cause
the applied asphalt to blister. Felts are generally made with 5 to 10% moisture,
an amount which can be adequately removed during saturation.
Non-Coated Products
These products are commonly referred to as 15 and 30 pound asphalt
saturated rag felt (ASRF). Fifteen pound ASRF is made from organic felt,
36 inches wide and with a felt weight of 5.6 pounds per 100 square feet.
Thirty pound ASRF is made from organic felt 36 inches wide and with a
felt weight of 10.4 pounds per 100 square feet. The organic felt is commonly
referred to as 27 weight and 50 weight. The organic felt is wound into jumbo
rolls that weigh from 2,000 to 3,000 pounds, with up to 7,000 lineal feet per roll.
During operation the felt is unrolled continuously onto a series of rollers
called a dry looper. The dry looper acts as inventory at the front of the process
so that the feed rate to the saturator can be held constant, even during
felt roll changes. Felt from the dry looper is pulled into the saturator where
it is saturated with hot asphalt at a temperature of 450ฐF. Saturation is accomplished
by spraying, dipping, or both. When spraying is employed, hot asphalt is
sprayed onto one side of the felt, driving the moisture out the other side.
When both methods are employed, spraying precedes dipping. Most modern
roofing plants are designed to use dipping only, since the dipping process
removes a sufficient amount of moisture out of the felt by boiling during
submersion in the asphalt bath.
After the felt is dipped, it travels over several rolls known as the drying-in
section. This allows the surface saturant to dry into the felt and helps coat
the sheet.
The felt is then conveyed to an accumulator before it is wound into rolls.
Roll lengths vary from 72 to 144 feet. The 27w felt generally absorbs or retains
approximately 7.8 pounds of saturant per 100 square feet. The 50w felt retains
approximately 17.4 pounds of saturant per 100 square feet.
182
-------
The process production rate is controlled by the linear speed at which
felt can be fed to the saturator and that speed, in turn, is controlled by
the properties of the felt. Maximum speeds are lower for heavier weight felts
than for lighter weight felts. Speeds as high as 1,000 fpm can be used with
light weight felts, but average speed is about 350 fpm. If 50w felt is fed to a
saturator at 350 fpm, the weight rate of felt feed is 6552 Ib/hr and the production
rate of saturated product is 17,514 Ib/hr.
Coated and Slate Surfaced Products
Asphalt shingles are generally produced using a 55w organic felt that
weighs 11.5 pounds per 100 square feet. Production of asphalt shingles begins
with the asphalt saturation process and then goes through a coating and
surfacing process. The coating process is accomplished by metering a measured
amount of filled coating to both surfaces of the saturated felt. The shingle
weight is controlled in the coating process by increasing or decreasing the
amount of surface coating.
Filled coating is made from two materials, coating and filler. There are
two types of filler that are normally used; limestone and slate. The majority
of the roofing companies use 50% filler in the coating. The filled coating is
applied to the sheet at temperatures ranging from 360 to 410ฐF.
After the coating process, the sheet travels through a surfacing section
where slate granules are applied to the top surface and a parting agent is
applied to the back surface. Different colors of granules are applied to the
sheet to get the desired blend or color of shingles. Several different parting
agents are available. Talc, sand and dolomite are the most common parting
agents used. When the sheet leaves the surfacing section, it travels through
a cooling section where water is sprayed on the back of the sheet. Then
the sheet goes into an accumulator to further cool the sheet. When the
sheet leaves the accumulator, it is cut into shingles and packaged.
The process production rate is controlled by the capabilities of the machine,
such as, saturation capacity. Machine speeds on asphalt shingle production
range from 350 to 600 fpm.
NATURE OF THE GASEOUS DISCHARGE
The saturator is totally enclosed with a hood for health reasons and that
hood is vented to the atmosphere. The amount of air exhausted from this hood
depends upon the size of the saturator and the degree of enclosure of the
183
-------
saturator. Typical saturators vent 20,000 to 30,000 ACFM. The range of rates
extends from 10,000 to 68,000 ACFM.1 The trend in modern plant design is down
since the cost of the required pollution control equipment depends strongly
upon the vent flow rate. The minimum exhaust volume is set by the quantity
of air that will allow men to work in the saturator enclosure and that will prevent
the escape of fumes into the plant.
The gases vented from the hood contain two principal classes of pollutants;
hydrocarbons and sulfur oxides. The hydrocarbons originate from the hot asphalt
bath. They enter the ventilation stream by means of vaporization from the
bath and mechanical agitation of the bath caused by the felt passing through.
Where spraying is used, the spray nozzles also contribute vaporized hydrocarbons.
The hydrocarbons are emitted in both the gas phase and the liquid phase
as an aerosol. The aerosol consists almost entirely of droplets formed by the
condensation of oil vapors driven from the asphalt saturator, with little contribution
from liquid particles entrained by mechanical agitation of the bath or at the
spray nozzle. These particles are very small with most being submicron.
The sulfur oxides are all in the vapor phase. They are formed from the
sulfur containing compounds in the asphalt and originate in the hot asphalt
bath or sprays. Sulfur oxides are emitted at lower rates than hydrocarbons.
Typical emission factors are as follows:1
Hydrocarbons 1 to 2.5 Ib/ton product
Sulfur Oxides 0.05 to 0.20 Ib/ton product
The asphalt blowing facilities represent the other major pollution source in
the typical asphalt roofing products plant. The emissions are hydrocarbon in
nature and result from the air blown through the asphalt to improve its
properties as a saturant. The rate of emission is roughly 50% of the saturator.
POLLUTION CONTROL CONSIDERATIONS
The pollution control systems which are applicable to the emissions from
asphalt saturators include some of those classically applied to control of hydro-
carbons: incineration, and absorption processes using chemical oxidants. Glass
fiber mat filters, specifically developed for use on asphalt saturators, are also
commonly used.3 Carbon adsorption is not used because the asphaltic hydro-
carbons are not easily desorbed from the surface of the carbon. Conventional
devices used for the collection of small sized particulate matter such as high
energy wet scrubbers and electrostatic precipitators have been applied to a
lesser degree.
184
-------
Incinerators
Thermal incineration is the most positive and direct control method for
hydrocarbon emissions and it has been widely applied to emissions from this
process. Conversions up to 99% can be achieved at operating temperatures
of 1,200 to 1,400ฐF and residence times of 0.3 sec. The units are built
with heat recovery when the air flow being treated is large enough to make
the economics attractive. The heat recovery scheme used takes one of two
forms.
1. Preheat of the incinerator inlet gas by heat exchange with hot outlet gas.
2. Use of the heat in the hot outlet gas in some other part of the roofing
products plant, e.g., to make steam for the felt manufacturing line.
Incineration can be quite effective. However, the operating cost can be
high due to fuel consumption.
Catalytic incineration units have not been widely applied in this industry
because of rapid deactivation of the catalysts, caused by sulfur and heavy
metals in the asphalt.
Glass Fiber Mat Filters
Glass fiber mat filters have been specifically developed to control the
emissions from asphalt saturators.3 These filters consist of mats made from
glass fibers and bonded together with phenolformaldehyde resins. The mats
are constructed so that they are compressible. As air is passed through them
they compress and effectively reduce the size of the passages through which
the gas is flowing. This compression increases the collection efficiency of
the filter. Collection efficiencies above 90% can be achieved at pressure drops
of 16 to 18 in. w.c. (see Table 88) for increasing effluent velocities.3
Absorption Processes Using Chemical Oxidants
Chemical oxidation has been applied in some locations to control hydro-
carbon emissions. The oxidation is carried out in a low energy wet scrubber,
usually of the conventional packed tower design. The circulating scrubbing liquor
is a dilute solution of oxidizing chemical such as potassium permanganate.
These systems can be effective, but require large amounts of the oxidizing
chemical to achieve an acceptable level of conversion and often produce solid
and liquid waste products which must be disposed of. The following sample
185
-------
reaction demonstrates these problems:
2 KMnOa + -(CH2)- -ป 2MnO2 + 2KOH
(aq)
(1)
(s)
+ CO2
(aq) (g)
In this example, two moles (316 Ibs) of potassium permanganate are
required to oxidize one mole (6 Ibs) of carbon and hydrogen, and the reaction
produces two moles (174 Ibs) of solid manganese dioxide waste, and one
mole (56 Ibs) of potassium hydroxide which must be neutralized prior to disposal.
SPECIFICATIONS AND COSTS
Specifications were written for systems to control emissions from each of
the two major sources in an asphalt roofing products plant: the asphalt saturator
and the asphalt blow still.
Asphalt Saturator
Specifications were written for three types of control systems: thermal
incinerators, glass fiber mat filters, and absorption using chemical oxidants.
In each case, the specification requested costs for two independent saturator
operations different from one another only in ventilation rate. The two units
represent a new, low ventilation rate design and an older, higher ventilation
rate design. Production rate, saturant and felt usage, and process operating
conditions are assumed to be identical for the two cases.
Specifications for absorption systems using chemical oxidants are shown
in Tables 79 and 80. Averaged capital and operating costs are presented in
Tables 81 and 82 and in Figures 52 and 53. The systems were bid assuming
that the scrubbing liquor would be a dilute, buffered solution of potassium
permanganate. In this example, the costs of buffering and neutralization have not
been included. The consumption rates of permanganate reflected in the operating
costs presented in Table 82 are calculated values based upon theoretical reactions
equivalent to that shown at the end of the previous section. The costs shown
on this table do not reflect field or laboratory data.
Incinerator specifications are shown in Tables 83 and 84. Averaged capital
and operating cost data are presented in Tables 85 and 86 and in Figures 54
and 55. The specifications requested costs at each of two levels of conversion;
98% and 99%. All of the bidders responded with identical capital costs and
nearly identical operating costs for these two cases. The capital costs shown
186
-------
in Table 85 represent both conversion levels. The slightly different operating
costs are reflected in Table 86 but could not be shown in Figure 54. In addition
to cost data, the specification requested combustion data from the bidders.
The averaged responses to this request are shown in the marked places in
Table 84.
Glass fiber mat filter specifications are shown in Tables 87 and 88. These
specifications were transmitted to the only available bidder who supplied the
costs presented in Tables 89 and 90 and Figures 56 and 57. The specification
requested costs and unit pressure drop at 98% (medium) collection efficiency
and the expected pressure drop at 99% (high) collection efficiency. The pressure
drop information is presented in Table 88.
187
-------
TABLE 79
SCRUBBER PROCESS DESCRIPTION
FOR ASPHALT SATURATOR SPECIFICATION
A scrubber is to control hydrocarbon emissions from an asphalt saturator.
Processing conditions and specifications are tabulated in Table 45.
The scrubbing liquor is to consist of a 3 wt % solution of potassium permanganate
buffered to 9.0 pH with borax. Materials of construction should be consistent with
the permanganate solution. Bids should include the following Items:
1. Low energy wet scrubber and mist eliminator.
2. Necessary fans and motors.
3. Twenty foot stack.
4. Recirculating tank.
5. Permanganate makeup and storage tank.
6. Interconnecting ductwork for all equipment furnished.
7. Appropriate control system.
8. Necessary provisions for periodic cleaning of manganese dioxide residue.
All of the above, except the scrubber proper, should be treated as auxiliaries.
The scrubber will be located on the roof of the existing facility. A 60 ft. square
area is available for new equipment next to the asphalt saturator vent stack.
A four inch concrete slab covers the area. All utilities are available at the site.
The sewer is available and will accept water in the 4 to 10 pH range, if it contains
less than 1 wt % solids content.
Neither the cost of borax to be used in buffering nor the cost of neutralization of
hydroxide ion prior to discharge has been included.
188
-------
TABLE @ฎ
SCRUBBER OPERATING CONDITIONS
FOR ASPHALT SATURATOR SPECIFICATION
Siza
Process Conditions
Gas Rate, ACFM
Gas Temp., ฐF
Gas Rate, SCFM
Moisture Content, vol %
Hcbn Emission Rate, Ib/hr
Gas from Scrubber
Gas Rate, ACFM
Gas Temp., ฐF"
Gas Rate, SCFM
Moisture Content, vol %'
Gas Rate, DSCFM
Hcbn Content, Ib/hr
Hcbn Removal Eff.. wt %
Small
22,600
140
20,000
4.0
50
21,300
95
20,300
5.2
19,200
8
84
Large
52,800
100
50,000
1.6
50
50.500
70
50,500
2.5
49,200
8
84
"Supplied by bidder
189
-------
TABLE 81
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR WET SCRUBBERS
FOR ASPHALT SATURATOR
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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 I
Electrical /
Piping
Insulation
Painting J
Supervision
Startup
Performance Test
Other
(4) Total Cost
Medium Efficiency
Small
Large
High Efficiency
Small
22,600
140
20,000
4.0
50
21,300
95
20,300
5.2
8
84
12,787
7,670
1,418
8,120
4,661
15,000
35,000
1,000
3,000
88,656
Large
52,800
100
50,000
1.6
50
50,500
70
50,500
2.5
8
84
26,325
17,582
1,711
8,120
6,795
20,000
40,000
1,000
3,000
124,533
190
-------
FIGURE 52
CAPITAL COST OF WET SCRUBBERS
FOR ASPHALT SATURATOR
5
4
J I0:
LJ Q
ฃ 7
8 6
4
TURNKEY COST
COLLECTOR PLUS AUXILIARIES
I04
COLLECTOR COST ONLY
10"
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
191
-------
(O
ro
TABLE 82
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR WET SCRUBBERS
FOR ASPHALT SATURATOR
Operating Cost Item
Operating Factor, Hr/Year 2,000
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- Permanganate
Total Utilities
Total Direct Cost
Annualized Capital Charges
Total Annual Cost
Unit
Cost
$6/hr.
$0.011/kwh
$0.25/MGal
$0.50/lb
16% of Cap
Medium Efficiency
Small
Large
High Efficiency
Small
1,200
1,200
100
100
1,746
6,000
1,276,000
1,283,746
1,285,046
14,185
1,299,231
Large
1,200
1,200
100
100
3,492
13,500
1,276,000
1,292,992
1,294,292
19,925
1,314,217
-------
FIGURE 53
ANNUAL COST OF WET SCRUBBERS
FOR ASPHALT SATURATOR
b
5
A
3
2
1
d loฐ
0 9
Q
1- 7
S 6
o
5
4
3
2
in5
\J
TA
Lt
NNUAL COST
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
193
-------
TABLE 83
THERMAL INCINERATOR PROCESS DESCRIPTION
FOR ASPHALT SATURATOR SPECIFICATION
(With Heat Exchange)
This specification describes the requirements of a thermal combustion system for
the abatement of hydrocarbon emissions from an asphalt saturator. Processing conditions
and specifications for small and large facilities are tabulated in Table 49.
The incinerator will be gas fired using natural gas available at a pressure of 1.0 psig,
having a specific gravity of 0.6 and an upper heating value of 1,040 BTU/SCF. The
exhaust gas from the saturator will contain sufficient oxygen 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 exchanger. The ductwork of the system will be sized for a maximum AP of
2 in. w.c. (hot).
The heat exchanger will be a counterflow shell and tube exchanger and be designed
to operate at an incinerator outlet temperature of 1500ฐF. The maximum exchanger
pressure drop (shell side and tube side) will not exceed 6.0 in. w.c. The contaminated
gas will flow through the tube side.
The incinerator will be supplied with a suitable control panel. All equipment will
be designed for outdoor operation and to meet the Factory Insurance Association's
standards.
The cost estimate 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
194
-------
All Items, with the exception of the Incinerator, burner, and heat exchanger, will
be considered auxiliaries. Vendors quotations should include both price information
and the design information requested in the operating conditions section.
The incinerator will be located on the roof of the existing facility, and no modification
of the building structure is required. The duct run from the asphalt saturator to the
incinerator will be 80 ft. All utilities are available within 30 ft. of the control cabinet,
motor, and burner.
195
-------
TABLE 84
THERMAL INCINERATOR OPERATING CONDITIONS
FOR ASPHALT SATURATOR SPECIFICATION
(With Heat Exchange)
Plant Size Small
Process Conditions
Gas Rate, ACFM 22,600
Gas Temperature, "F 140
Gas Rate, SCFM 20,000
Hcbn Emission Rate, Ib/hr 50
Heating Value of Gas, BTU/SCF 0.8
Heat of Combustion of Hcbn, BTUIIb 16,000
Incinerator Specifications
Residence Time @ Temperature, sec. 0.3
Inlet Tubeside Temperature, ฐF 140
Incinerator Outlet Temperature, ฐF" 678
Incinerator Inlet Temperature, ฐF" 991
Burner AT from Fuel Gas, ฐF* 484
Burner AF from Flame Combustion, ฐF" 3
Burner Outlet Temperature, ฐF' 1,487
Unit A7 from Thermal Combustion, ฐF' 22
Burner Duty, mm BTU/hr' 12.6
H.E. Duty mm BTU/hr' 19.4
Thermal Efficiency Counterflow H.E., % 60
Overall Heat Transfer Coef, U' 5.4
Tube Surface Area, Ft2' 7,549
Large
52,800
100
50,000
50
0.3
18,000
0.3
100
657
974
511
1.5
1,495
13.5
33.2
49.6
60
5.5
18,332
Case 1 - Medium Efficiency
Hcbn Emission Rate, Iblhr
Efficiency, wt %
1
98
Case 2 - High Efficiency
Hcbn Emission rate, Iblhr
Efficiency, wt %
0.5
99
0.5
99
'Supplied by bidder.
"Assuming 10% conversion of fume in the flame
196
-------
TABLE 85
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
TOIBEML INCINERATORS (WITH HEAT EXCHANGE)
FOR ASPHALT SATURATOR
Effluent Gas Flow
ACFM
op
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
Ib/hr
Cleaned Gas Flow
ACFM
op
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
>
Medium Efficiency
Small
22,600
140
20,000
50
678
1
98
Same As
High
Efficiency
Large
52,800
100
50,000
50
657
1
98
Same As
High
Efficiency
High Efficiency
Small
22,600
140
20,000
50
678
.5
99
120,775
9,565
5,900
88,725
224,965
Large
52,800
100
50,000
50
657
.5
99
269,850
19,845
12,600
130,435
432,730
197
-------
FIGURE 54
CAPITAL COST OF THERMAL INCINERATORS (WITH HEAT EXCHANGE)
FOR ASPHALT SATURATOR
(High Efficiency)
D
5
4
3
2
1
-] I05
Q 9
* 8
t* 7
In '
0 6
U
5
4
3
2
in*
S
S
/
/
^i
/
/
r
t
jj
/
t
ef
,,/;
gx
i
/
/
FUR
cc
-C(
4K
ILL
i
3LL
Y
EC
1
.EC
-
:OST
'OR PLUS AUXIUARI
TffeQ CrtCT OMI V
s
10"
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
4
198
-------
TABLE
ANNUAL OPERATING COST
(COSTS IN $/YEAR)
FOR THERMAL INCINERATORS (WITH HEAT EXCHANGE)
FOR ASPHALT SATURATO.
Operating Cost Item
Operating Factor, Hr/Year 2 000
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.
$0.011/kwh
$0.7232/
1000 ft3
16% of Cap
Medium Efficiency
Small
1,280
1,280
240
400
640
150
150
1,243
20,144
21,387
23,457
35,994
59,451
Large
1,920-
1,920
480
1,100
1,580
350
350
2,970
53,184
56,154
60,004
69,237
129,241
High Efficiency
Small
1,280
1,280
240
400
640
150
150
1,243
20,160
21,403
23,473
35,994
59,467
Large
1,920
1,920
480
1,100
1,580
350
350
2,970
53,200
56,170
60,020
69,237
129,257
CO
CO
-------
FIGURE 55
ANNUAL COST OF THERMAL INCINERATORS (WITH HEAT EXCHANGE)
FOR ASPHALT SATURATOR
(High Efficiency)
6
5
A
-J I05
O 9
Q 8
\-
8
O
7
6
TOTAL ANNUAL COST
. TOTAL DIRECT COST
10'
3 4 5 6789 I05
CLEANED GAS FLOW, ACFM
200
-------
TABLE 87
GMSS FIBER MAT FILTER PROCESS DESCRIPTION
FOR ASPHALT SATURATOR SPECIFICATION
A glass fiber mat filter is to control hydrocarbon emissions from an asphalt saturator.
Processing conditions and specifications are tabulated in Table 53. Bids should include
the following items:
1. Filter unit
2. Necessary fans and motors
3. Twenty foot stack
4. Interconnecting ductwork for all equipment furnished
5. Appropriate control system
All of the above, except the filter should be treated as auxiliaries.
The filter will be located on the roof of the existing facility. A 60 ft. square area
is available for new equipment next to the asphalt saturator vent stack. A four Inch
concrete slab covers the area. All necessary utilities are available at the site.
Vendor's quotation should include total price information and relevant design
information, including the expected pressure drop across the unit at the required
efficiency levels. Vendor should also specify the pressure drop which would be
required to achieve 99 wt % collection efficiency, but need not supply price
information for these extra cases.
201
-------
TABLE 88
GMSS FIBER MAT FILTER OPERATING CONDITIONS FOR
ASPHALT SATURATOR SPECIFICATION
Size
Process Conditions
Gas Rate, ACFM
Gas Temp., "F
Gas Rate, SCFM
Moisture Content, vol %
Hcbn Emission Rate, Ib/hr
Small
22,600
140
20,000
4.0
50
Large
52,800
100
50,000
1.6
50
Outlet Gas Rate, SCFM
Outlet Hcbn Rate, Ib/hr
AP Across Filter, in. w.c.'
Collection Efficiency, wt %
Medium Efficiency Case
20,000
1
26
98
50,000
1
26
98
Outlet Gas Rate, SCFM
Outlet Hcbn Rate, Ib/hr
AP Across Filter, in. w.c.'
Collection Efficiency, wt %
High Efficiency Case
20,000
0.5
28-30
99
50,000
0.5
28-30
99
'Supplied by bidder.
202
-------
TABLE 8ง
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
GLASS FIBER MAT FILTERS FOR ASPHALT SATURATOR
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Cleaned Gas Contaminant Loading
Ib/hr
Cleaning Efficiency, %
( 1 ) Gas Cleaning Device Cost
.' . Fans and Startup Incl.
(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 I
Electrical /
Piping 1
Insulation I
Painting J
Supervision
Startup
Performance Test
Other
(4) Total Cost
Medium Efficiency
Small
22,600
140
20,000
4.0
50
22,600
140
20,000
4.0
1
98
62,750
2,800
12,750
25,000
125,000
18,000
246,300
Large
52,800
100
50,000
1.6
50
52,800
100
50,000
1.6
1
98
108,650
6,900
25,500
40,000
155,000
18,000
354,050
High Efficiency
Small
Large
203
-------
FIGURE 56
CAPITAL COST OF HIGH ENERGY AIR FILTERS
FOR ASPHALT SATURATOR
6
5
4
TURNKEY COST
I05
9
8
5
4
COLLECTOR PLUS AUXILIARIES
COLLECTOR COST ONLY
*ฃ
8
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
204
-------
ANNUAL OPERATING COST DATA
(COSTS IN I/YEAR)
FOR GLASS FIBER MAT FILTERS
FOR ASPHALT SATUftATO
Operating Cost Item _
I Cost
Operating Factor, Hr/Year 2,000 !
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
$6/hr.
$6/hr.
$0.011/kwh
$0.05/MGal
16% of Cap
Medium Efficiency
Small
100
100
300
500
800
3,500
3,500
3,237
42
3,279
7,379
39,408
46,787
Large
100
100
300
500
800
7,500
7,500
7,547
168
7,715
16,115
55,648
71,763
High Efficiency
Small
Largs
-------
FIGURE 57
ANNUAL COST OF HIGH ENERGY AIR FILTERS
FOR ASPHALT SATURATOR
id3
9
8
7
6
5
4
3
2
ฃ
3 'ฐ4
p 9
Q 8
ฃ e7
u
5
4
3
2
in3
^
&
^
?S
0
,**
^
^
X
pr
.TO!
*
)TAL!
AL<
HRE
MN
CT
JA
:os
.c
IT
33T
10
2 3 4 5 6 7 8 9 IO
CLEANED GAS FLOW, ACFM
206
-------
TABLE 91
THERMAL INCINERATOR PROCESS DESCRIPTION
FOR ASPHALT BLOW STILL
(With Heat Exchange)
This specification describes the requirements of a thermal combustion system
for the abatement of hydrocarbon emissions from an asphalt blow still. Processing
conditions and specifications for small and large facilities are tabulated in Table 57.
The Incinerator will bo gas fired using natural gas available at a pressure of
1.0 pslg, having a specific gravity of 0.6 and an upper heating value of 1,040
BTUISCF. The exhaust gas from the blow still will contain sufficient oxygen to
allow firing of the burner without the addition of a combustion air system.
A fan equipped with a V-bett 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 exchanger. The ductwork of the system will be sized for a maximum
&Pof2 in. w.c. (hot).
The heat exchanger will be a counterflow shell and tube exchanger and be
designed to operate at an outlet Incinerator temperature of 1500'F. The maximum
exchanger pressure drop (shell side and tube side) will not exceed 6.0 In. w.c.
The contaminated gas will flow through the tube side.
The Incinerator will be supplied with a suitable control panel. All equipment will
be designed for outdoor operation and to meet the Factory Insurance Association's
standards.
The cost estimate 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 the exception of the incinerator, burner, and heat exchanger, will
207
-------
be considered auxiliaries. Vendors quotations should include both price information
and the design information requested in the operating conditions section.
The incinerator will be located on the roof of the existing facility, and no modification
of the building structure is required. The duct run from the asphalt blow still to the
incinerator will be 200 ft. All utilities are available within 30 ft. of the control cabinet.
motor, and burner.
208
-------
TABLE 92
THERMAL INCINERATOR OPERATING CONDITIONS
FOR ASPHALT BLOW STILL SPECIFICATION
(With Heat Exchange)
Plant Size Small Large
Process Conditions
Gas Rate, ACFM 10,600 34,100
Gas Temperature, ฐF 210 210
Gas Rate, SCFM 8.400 27,000
Hcbn Emission Rate, Ib/hr 52 168
Heating Value of Gas, BTU/SCF 1.9 1.9
Heat of Combustion of Hcbn, BTUIIb 18.000 18,000
Incinerator Specifications
Residence Time @ Temperature, sec. 0.3 0.3
Inlet Tubeslde Temperature, "F 210 210
Incinerator Outlet Temperature, ฐF' 720 723
Incinerator Inlet Temperature, ฐF' 1,016 1,013
Burner AT from Fuel Gas, ฐF' 422 426
Burner AT from Flame Combustion, ฐF" 5.5 5.5
Burner Outlet Temperature, ฐF* 1,468 1,468
Unit Af from Thermal Combustion, ฐF* 56.5 56.5
Burner Duty, mm BTU/hr' 4.6 14.9
H.E. Duty mm BTUIhr' 7.7 24.7
Thermal Efficiency Counterflow, H.E., %*" 60 (65^ 60 (64.5)
Overall Heat Transfer Coef, U" 5.4 5.8
Tube Surface Area, ft2' 3,138 9,589
Case 1 - High Efficiency
Hcbn Emission Rate, Ib/hr
Efficiency, wt %
0.5
99
0.5
99
Supplied by bidder.
"Assuming 10% conversion of fume in the flame
'"One bidder reported higher thermal efficiency counterflow percentages (shown In
parenthesis) than those specified.
209
-------
TABLE 93
ESTIMATED CAPITAL COST DATA
(COSTS IN DOLLARS)
FOR THERMAL INCINERATORS
FOR ASPHALT BLOW STILL
Effluent Gas Flow
ACFM
ฐF
SCFM
Moisture Content, Vol. %
Effluent Contaminant Loading
Ib/hr
Cleaned Gas Flow
ACFM
ฐF
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
)
Medium Efficiency
Small
Large
High Efficiency
Small
10,600
210
8,400
52
720
.5
99
67,175
4,599
4,300
61,200
137,274
Large
34,100
210
27,000
52
720
.5
99
147,350
13,250
8, .800
95,275
264,675
210
-------
FIGURE 58
COITAL COST OF THERMAL INCINERATORS
FOR ASPHALT BLOW STILL
6
5
4
TURNKEY COST
J I05
O 9
Q
5
4
3
COLLECTOR PLUS AUXILIARIES
COLLECTOR COST ONLY
^
10'
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
211
-------
to
TABLE 94
ANNUAL OPERATING COST DATA
(COSTS IN $/YEAR)
FOR THERMAL INCINERATORS
FOR ASPHALT BLOW STILL
Operating Cost Item
Operating Factor, Hr/Year 2,000
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.
$0.011/kwh
$0.7232/
1000 ft3
16% of Cap
Medium Efficiency
Small
Large
High Efficiency
Small
1,280
1,280
240
400
640
150
150
781
7,360
8,141
10,211
21,964
32,175
Large
1,280
1,280
240
600
840
200
200
2,497
23,880
26,377
28,697
42,348
71,045
-------
FIGURE 59
ANNUAL COST OF THERMAL INCINERATORS
FOR ASPHALT BLOW STILL
TOTAL ANNUAL COST.
TOTAL DIRECT COST
3 4 5 6 7 8 9 I05
CLEANED GAS FLOW, ACFM
213
-------
REFERENCES
1. "A Screening Study to Develop Background Information to Determine the
Significance of Asphalt Roofing Manufacture" EPA Contract 68-02-0607,
Task 2, Research Triangle Institute, Dec., 1972, Research Triangle Park,
North Carolina.
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. Qoldfield, J.; Gandhi, K.; "Glass Fiber Mats to Reduce Effluents from
Industrial Processes," Journal of the Air Pollution Control Association.
July, 1970, Vol. 20, No. 7, pp. 466-469.
214
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7. SURFACE COATING OPERATIONS
The term "surface coatings" applies to a great many different coating
materials, both organic and inorganic, and different application technologies.
The air pollution control problems which accompany each type of coating and
application method are correspondingly different from one another. This discussion
has been limited, by the scope of the contract under which it was prepared, to
organic coatings and application technologies which involve solvent evaporation
or other vapor phase organic emission.
The basic purpose of an organic coating is to form a film over a substrate
which will cohere to itself and adhere to the surface over which it is applied.
In current times, the usefulness of organic coatings has been widely extended
from simply a protective (weather and corrosion) function to diverse applications
which include:
1. Electrical insulation
2. Lubricity
3. Temperature control
4. Fire retardency
5. Control of marine fouling
6. Sound deadening
Currently, most organic coatings are formulated with synthetic resins
which can be tailored to solve a particular finishing problem. They can be applied
to a surface by a number of operations including dipping, spraying, flow-coating,
and roller coating. Furthermore, combinations of these operations, each designed
for a specific task, are found.
SCIENTIFIC PRINCIPLES OF COATING FORMATION
The surface coating process consists of the conversion of the solutions or
melts of film-formers to the amorphous state and the fixation of the film as it is
formed to a particular substrate.
Film-formers may be classified into those which transform during the coating
operation and those which do not transform.
Formation of Non-Transforming Coatings
The theory of the mechanism of film-forming for these materials, which include
cellulose esters, perchlorvinylic types, and many others, states that when solvent
is evaporated from solutions of compounds of low molecular weight resins, the
215
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film-formers are converted to the amorphous state. The conditions for pure
solvent evaporation must be differentiated from those for solvent evaporation
from solutions, particularly from solutions of high molecular weight compounds.
For lacquers, the evaporation rate may be given as:
g = 2g0x (grams/m2/min)1 (1)
where go is the evaporation rate for an individual constituent and x is the mole
fraction of that constituent in the original solution.
Empirical evidence indicates, for the majority of solvents, the evaporation of
the first 90 percent can be expressed by
L = cT (2)
where L is the percent of solvent lost, c and m are constants that are characteristic
of the solvent, and t is the time. The remaining 10% evaporates slowly, and
its evaporation does not obey the above equation. Pigments have different
effects on evaporation rates. Coarse-particle pigments will accelerate evaporation,
whereas finely dispersed pigments retard it.
Coatings Formed by Transformation
The transformation of monomers or linear polymers to three-dimensional
polymers usually takes place as a result of the following processes:
1. Polycondensation (in phenol-aldehyde resins, and for coatings dried by
heat).
2. Polymerization or copolymerization at the sites of unsaturated bonds,
either directly or through the agency of oxygen.
Many film-forming substances will transform as a result of both of these processes.
PROCESS DESCRIPTION
There are several common methods by which surface coatings are applied:
dipping, spraying, flow coating, and roller coating. In modern industry, these
methods are applied to a large number of different types of coating materials,
such as those listed on Table 95. Some of these processes, such as dipping
and flow coating, have become obsolete in some industries as newer, inorganic
systems are developed.
216
-------
TABLE 95
EXAMPLES OF SURFACE-COATING FORMULAS
ON AN AS-PURCHASED BASIS
Hydrocarbons
Type of
Surface Coating
Paint
Varnish
Enamel
Lacquer
Metal Primer
Glaze
Resin*
Sealer
Shellac
Stain
Zinc Chromate
Non-
Volatile
Portion
44
50
58
23
34
80
50
50
50
20
60
Aliphatic
56
45
10
7
33
40
Aromatic
5
30
30
33
20
80
40
Alcohol
2
9
50
Ketones
Esters
&
Ethers
22
10
"Contains 50% solvent of an unspecified type.
ro
-vl
-------
Paint Dip Tanks
In this method of application, an object is immersed in a simple paint
container and then removed. These containers frequently have conical bottoms.
The excess paint is drained from the object back to the dip tank, either by
simply suspending the object over the container or by using drainboards that
drain back to the dip tank. Agitation is necessary in order to keep the paint
mixture uniform. The most common agitation method consists of pumping paint
from the bottom of the tank to some point near the tank top, but still under the
liquid surface.
Flow Coating Machines
Flow coating consists of flowing paints in a steady stream over objects that
are suspended from a conveyor line. The paint is recirculated by a pump from
a drain basin back to the paint nozzles.
Roller Coating Machines
Paint roller coating machines usually have three or more power-driven
rollers and are quite similar to printing presses in their construction. Paint is
transferred from the first roll, which is partially immersed in the paint, to a second
roll which is running parallel to it. The sheet work to be coated is run between
the second and third roll and is coated by transfer of paint from the second roll.
The quantity of paint applied is determined by the distance between the rolls
through which the sheet passes.
Spraying
In spraying operations, a spray gun usually operated by compressed air,
is used to spray the paint on the object to be painted. In order to insure that an
explosive concentration of solvent vapor does not occur and to protect the
health of the spray gun operator, a booth or enclosure ventillated by a fan
provides a means of ventilating the spray area. Table 96 shows threshold
limit values of typical paint solvents. These values are average concentrations
to which workers may be safely exposed for an 8-hour day without adverse
effect on their health.
The spray booth may also be equipped to filter incoming air as well as
remove paniculate matter from the exhausted air.
218
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TABLE 96
LIMITING VALUES OF
TYPICAL PAINT SOLVENTS
Acetone
Amyl Acetate
Methyl Ethyl Ketone
Butyl Acetate
Cellosolve
Cellosolve Acetate
Ethyl Acetate
Ethanol
Naphtha (Petroleum)
Toluene
Xylene
Mineral Spirits
Lower Explosive
Limit (LEL)*
%
2.15
1.1
1.81
1.7
2.6
1.71
2.18
3.28
0.92 to 1.1
1.27
1.0
0.77
25%
LEL
ppm
5,400
2,750
4,525
4,250
6,500
4,275
5,450
8,200
2,300
3,175
2,500
1.925
Worker Threshold
Limit Values"
ppm
1,000
200
250
200
200
100
400
1,000
500
200
200
500
Adapted from: Factory Mutual Engineering Division, Handbook of Industrial
Loss Prevention, McGraw Hill Book Co., Inc. NY, 1959.
"Adapted from: American Medical Association Archives of Environmental Health,
14:186-89, 1956.
219
-------
The chief advantages of spray painting are the speed of painting and the
comparative ease of obtaining a relatively smooth finish; the chief disadvantage
is the waste of material that can occur. A considerable quantity of paniculate
matter results from the use of the common air atomization type spray gun. A
60 percent overspray of an object is quite common. Paniculate matter in paint
spray booths is controlled by baffle plates, filter pads, or water spray curtains.
The discharge from spray booth operations consists of paniculate matter
and organic-solvent vapors. The particulate matter concentration seldom exceeds
0.01 grain per SCF of unfiltered exhaust. The location of the exhaust stack is
extremely important so that paint spotting on neighboring property is avoided. The
solvent concentration in spray booth effluent varies from 100 to 200 ppm. Depending
on the extent of operation, the solvent emission out of the spray booth stack will
vary from less than 1 pound per day to 3,000 pounds per day. Solvent vapors
will take part in photochemical smog reactions leading to products that result
in eye irritation. Odors also cause local nuisances.
TYPES OF SPRAY BOOTHS
Dry Type Booths
Dry Baffle Spray Booths
This type of booth is especially suitable for spraying small objects which are
manually loaded and unloaded through the front opening. Overspray adheres to
the face of baffles or is trapped in eddies of air striking the rear surface of baffles.
The auxiliary equipment would consist of an exhaust fan with electric motor,
light fixtures and the exhaust chamber.
Paint Arrester Type
This is similar to the dry baffle type except that air-borne paint particles
from exhaust air are removed by means of disposable filters. This unit is used
mainly for intermittent spray operations; such as, refinish shops, schools, and
production lines where paint consumption is moderate.
Dispo Spray Booths
In the "dispo" type of booth, maintenance and cleaning time are reduced to a
minimum. The booth may be used for heavy or light production spray operations.
220
-------
The entire back-end of the booth is covered with a felt material that collects
over-spray and particles as the exhaust air is drawn through it. As the filtering
media becomes loaded with overspray and the differential in static pressure
rises to a preset point, fresh media is rolled down by a power drive. The usage
of filter media is directly proportional to paint load. Auxiliaries include the customary
exhaust fan, lighting, filter media, and exhaust duct components.
Water Wash Spray Booths
These are the most widely used and most versatile type of booth. One of
the primary benefits of this type of booth is that when articles being sprayed
are of convenient size (up to and including motor vehicle bodies) the booths
will permit spraying to be conducted in the same workshop as other operations
of both a mechanical and finishing nature.
The main feature of this type of booth is a powerful scrubbing action with a
deluge of water which removes paint or resin particles from the exhaust air.
The design of the nozzles and their spacing provide a curtain of coarse water
droplets that trap the particles and carry them into a tank for easy removal.
Baffles, which are positioned between the washing area and the exhaust fan,
are so positioned as to remove any free water before it reaches the stack. When
the air is discharged, it is essentially free of resin and water particles and will
contain only organic solvent vapor as a contaminant. Figure 60 shows a typical
water wash spray booth.
Water wash sprays are available in a great variety of capacities to efficiently
remove air-borne resin particles resulting from spraying operations. In general,
standard duty chambers provide sufficient washing capacity for maintenance
painting or moderate speed conveyorized jobs, while heavy duty chambers
provide extra air washing capability for high production applications involving
high coating rates.
Standard air velocities of 125 and 150 feet per minute are offered to meet
industry and code standards. Generally, 125 feet per minute meets most
requirements. One hundred and fifty feet per minute is available for heavy-duty
application or where preferred or specified by industry and codes.
Down-draft Spray Booths
Figure 61 shows a down-draft water wash spray booth. This type of booth
is particularly suited for production finishing in many industries; highly adaptable
to all kinds of production requirements and plant layouts. The salient features
of this device are:
221
-------
EXHAUST
SrfOTOR
WATER
SPRAY
RECIRCUL.ATING
WATER
FIGURE 60
WATER-WASH SPRAY BOOTH
222
-------
EXHAUST
t
FAN
|CJ^^^
_. .. . ___
PAINT \NA
GRATINO
I^u.
~| N/10TOR
_ "
'WATER
SPRAY
RECIRCUL.ATING
WATER
FIGURE 61
DOWN-DRAFT
WATER WASH SPRAY BOOTH
223
-------
1. The tank of water immediately below the grilled floor where spray particles
settle.
2. The water that cascades down the spill sheet of the chamber. This
rapidly-flowing water-curtain removes more resin particles from the air.
This type of spray booth is available without enclosure, with semi-enclosure,
and with complete enclosure where spray operators can work all around the
object being sprayed.
The Electrostatic Coating Booth
The principle of electrostatic spraying is based on the familiar physical
law that like charges repel and unlike charges attract. Atomized paint particles
are given a negative charge while the product is maintained at ground potential
and is positive in relation to the negative paint particles. If some of the charged
paint particles bounce off or miss the product, they reverse themselves back
to the product because of the attraction due to the electrostatic field. The
obvious advantage of electrostatic spraying is a much greater efficiency of
paint utilization by minimizing overspray. Spray booth and duct maintenance are
correspondingly reduced.
Other Spray Booths
Various other types of spray booths are available for particular operations.
Included in this list are:
1. Auto-truck and truck-trailer booths.
2. Automatic spray booths.
3. Degreasing booths.
4. Cleaning booths.
5. Bench and leg booths.
6. Ceramic spray booths.
7. Traveling spray booths.
Detailed descriptions of these booths are best found by referring to manufacturers'
literature.
224
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ORGANIC EMISSIONS FROM PROTECTIVE COATING OPERATIONS
The emissions from protective coating operations consist of participates
and volatile organic solvents. The Air Pollution Control District of Los Angeles
conducted a survey in 1955, supplemented in 1957, in order to determine the
quantities, types and sources of organic compounds in the Los Angeles County
atmosphere, exclusive of motor vehicle emissions. Results indicated that protective
coating operations accounted for 55 percent of the total organic emissions. This
figure accounted for 470,000 pounds of organic vapors being emitted daily into
the atmosphere.
The range of average concentration of organic vapors from protective coating
operations has been determined from a survey by the Air Pollution Control
District of Los Angeles County to be 100 to 200 parts per million. These values
are lower than those allowed by safety requirements, based on the lower
explosion limit of the individual compounds. Fire prevention regulations usually
require that organic emissions not exceed 25% of the lower explosion limit.
For toluene, which has wide use in finishes, this would be about 3,000 parts
per million. (See Table 96). Although the organic vapors exist at low concentrations,
low partial pressures, and low dew points, their presence is still significant as
far as air pollution control is concerned. Any abatement method developed for
recovery of low concentrations would probably be applicable as well as more
attractive economically in those operations where high concentrations are
encountered.
The exhaust air rate giving rise to hydrocarbon emissions from surface coating
operations is fixed by insurance standards to be not less than 100 feet per
minute per square foot of booth opening. The usual spray booth ventilation
rate is 100 to 150 feet per minute.
Paniculate matter, consisting of fine paint particles, is emitted in surface
coating operations. Their presence is quite important, from the point of view of
controlling organic solvent emissions, because they interfere with the operation
of abatement systems designed to control organic emissions. The concentration
of these particles seldom exceeds 0.01 grain per SCF of unfiltered exhaust.
POLLUTION CONTROL CONSIDERATIONS FROM SURFACE COATING
OPERATIONS
Paniculate Matter
The fraction of paint that is not deposited on an object during the use of
the common air atomization spray gun is called overspray. Overspray may
225
-------
be as high as 90 percent; however, 60 percent is more common. Particle
emissions from spray booth operations are controlled by baffle plates, filter pads,
or water spray curtains. The efficiency of baffle plates and filter pads can be
as high as 90%. Water curtains are satisfactory for removing paint particulates
with efficiencies up to 95%. A water circulation rate of 10 to 38 gallons per 1,000
cubic feet of exhaust air is customary for this use.
Control of Organic Emissions
Two techniques are available for limiting the emission of organic solvents
from surface coating operations. These include:
1. Process modification
2. Pollution control with or without solvent recovery
^
Under "process modification" there are two conventional alternatives. Emissions
can be reduced by a factor of two or three by switching to electrostatic spraying,
or the composition of the solvent system may be altered so as to make it
exempt from Rule 66.* Table 97 is an example of substitution of exempt solvent.
If none of the alternatives are possible, then add-on pollution abatement
equipment is required.
The known methods for pollution control with solvent recovery include the
following: condensation by cooling, condensation by compression, absorption and
stripping, and adsorption.
Condensation by Cooling
Scheflan and Jacobs7 indicate that solvent recovery by refrigeration is
practical only to mixtures where the hydrocarbon to be recovered is present
in greater amounts than 50,000 ppm. Since the concentration of hydrocarbon
solvent in spray booth emissions is between 100 and 200 ppm, it is quite clear
that this method is not applicable. For detailed calculation see LAAPCD
Report #86.
Condensation by Compression
In order to demonstrate the applicability of this approach to spray booth
emissions, consider toluene to be the organic pollutant of interest. The partial
pressure of toluene at 68ฐF in a surface coating operation is 0.08 mm Hg (100
Rules and Regulations, County of Los Angeles Air Pollution Control District.
226
-------
TABLE 97
SUBSTITUTION OF EXEMPT SOLVENT
Typical Solvent Formulation
Acetone
Toluene
Cellosolve Acetate
Vol. %
25
50
25
Limit Under Rule 66
Exempt
=s20% in Aggregate
Exempt
100
Exempt Solvent Formulation
Acetone
Benzene
Toluene
Paraffinic Hydrocarbon
Cellosolve Acetate
Limit Under Rule 66
Exempt
Exempt
=s20%
Exempt
227
-------
ppm toluene in air at 68ฐF). Removal of 90% of the toluene at 68ฐF by
compression would require increasing the total pressure on the system to 12,000
psi. This would require a six-stage compressor with a power requirement of
(assuming 75% efficiency) 72 hp/1000 ACFM. Both capital and operating costs
for such a system would be prohibitive for most cases.
Absorption
According to Ray,5 when the concentration of an organic vapor to be
recovered is low enough to be safe, then recovery by mineral oil absorption
is relatively inefficient and expensive. As far as absorption with water is concerned,
it is known that lower molecular weight alcohols and ketones have varying
degrees of solubility in water. However, the major portion of paint thinners
and diluents is either mineral spirits or toluene, and they do not have great
solubility in water.
In general, control of solvent emissions by means of absorption is not
practical, because the extremely low vapor concentration results in a high capital
cost for the scrubbing tower, the stripping tower, and the numerous heat
exchangers required.
Adsorption
Activated carbon appears to be the adsorbant most suitable for recovering
the organic solvent vapors emitted from spraying operations. Since activated
carbon will adsorb all the usual low boiling solvent vapors, it can be used for
recovery of any or all low boiling solvents vaporized in surface coating operations.
Various systems have been employed for carbon adsorption. Figure 62
shows a schematic layout for a paint spray application. The adsorption system
shown would require a fan or blower to remove the vapor-laden air, two drums
containing a bed of activated carbon which would be used alternately (one
adsorbing the other being regenerated), a condenser, and some sort of decanter.
Controls are also necessary to switch air flows to the adsorbers and control
the desorption stream.
There is no question that activated carbon can be used to remove organic
vapors from a gas stream by adsorption. The "rule-of-thumb" is that about 1
Ib of carbon is needed for 1 ACFM going through the recovery unit. If the
concentrations of the organic vapor are very low, this ratio can be reduced to
1/4 Ib/ACFM. Another "rule-of-thumb" is that the carbon will adsorb 10 to 20%
of its own weight, at which time desorption will be necessary.
228
-------
AIR
CLEAN AIR
DO
iWNt
SEE
BOOTH
FILTER
f I
STEAM
ง5
TT T
CAR]
N
ADSORBERS
RECOVERED
SOL-VENT
SEPARATION
CONDENSER
CONDENSATE
FIGURE 62
SCHEMATIC OF CARBON ADSORPTION & DESORPTION UNITS
ro
ro
-------
There are several factors which influence the capacity of a carbon bed
for adsorption of an organic solvent:
1. Temperature the higher the temperature, the lower a bed's capacity.
2. Concentration the higher the concentration of organic vapor in gas
stream, the higher the capacity.
3. Solvent boiling point higher solvent boiling point increases capacity.
4. Contact time other things being equal, the longer the contact time,
the greater the capacity.
5. Humidity high humidity will decrease capacity.
The Air Pollution Control District of Los Angeles conducted
an extensive pilot plant study of carbon adsorption for the removal of organic
solvents from spray booth operations. Table 98 shows the results of sizing
several adsorbing units with varying capacities. The main conclusion of their
study was that the control of organic emissions from protective coating operations
was technically feasible using adsorption on activated carbon.
There has been a significant amount of recent process development in
carbon adsorption systems in order to make them more economical. These
developments have taken two primary forms:
1. Integration of the carbon adsorption process with the surface coating
process. For example, using paint bake oven exhaust gas to desorb
the recovered solvent from the carbon bed, or using the heat in a
regeneration stream to reduce fuel costs in a surface coating oven.
2. Using the carbon adsorption process to reduce the volume of the
solvent laden exhaust gas to be treated by other pollution control
systems. For example, thermal incineration can be more economical when
applied to the desorption stream from a carbon bed rather than the
untreated process exhaust gas stream.
The details of these developments are outside the scope of this paper.
They are mentioned here to demonstrate the increasing applicability of carbon
adsorption processes to emission control in this industry.
Incineration
Thermal Combustion
Thermal incineration involves direct burning of the effluent in a gas-fired
230
-------
TABLE 98
SUES FOR SOLVENT RECOVERY SYSTEMS
USING ACTIVATED CARBON*
Spray Booth
Capacity
Adsorbing
Unit"
Carbon Bed
Diameter*"
(in.)
Total
Carbon Weight
(Ib)
Solvent
Recovered
(Ib/day)
(1)
1,000 (2)
cfm (3) 30 f 153 13
(4)
(1) 96
5,000 (2) 68
cfm (3) 68 f 755 64
(4) 48 (cone ht, 42") I
(1) 156
10,000 (2) 96
cfm (3) 96 [1,510 128
(4) 60 (cone ht, 150")]
(1) 192
20,000 (2) 156
cfm (3) 156 f 3,000 257
(4) 96 (cone ht, 192"))
(1) 302
50,000 (2) 216
cfm (3) 216 ( 7,550 642
(4) 144 (cone ht, 312")
"Operating conditions: solvent toluene at concentration of 150 ppm (=2.18 lb/hr/1000 cfm);
desorption with superheated steam for 2 hr. 45 min., using 13 Ib steam/lb solvent recovered;
carbon retentivity, 81/z Ib solvent/100 Ib carbon; work, one 6-hour shift per day, 5 days per week;
duct velocity, 2500 fpm; adsorber velocity, 100 fpm.
"Adsorbing units: (1) single unit, single flat bed; pressure drop, 2.1 in. H2O
(2) double unit, single flat bed; pressure drop, 2.1 in. HzO
(3) single uhit, two flat beds; pressure drop, 10.0 in. H2O
(4) single unit, vertical cone bed; pressure drop, 3.1 in.
'"Carbon bed depth, 5.7 in. all units.
231
-------
incinerator. Although simple in concept and operation, there is actually a great
deal of design, engineering, and manufacturing skill involved. The process of
thermal incineration is outlined by the flow diagram shown in Figure 63. The
solvent laden air from the spray booth enters the thermal system where it is
preheated to 600ฐF to 900ฐF and then incinerated in the residence chamber
at 1000ฐF to 1500ฐF. The fumes, when properly incinerated, evolve as carbon
dioxide, water, and heated air. Fuel costs can be held to a minimum through
the use of heat exchange and recirculation of heated air. Thermal combustion is
capable of achieving a high level of effectiveness for removal of organic emissions.
Systems can operate continuously at efficiencies of 90% to 100%. Combustion
temperatures vary according to the solvent and its concentration. Auto-ignition
data, which are available for many organic solvents, can serve as a rough
guide to the relative difficulty of combustion; however, having been obtained
under optimum combustion conditions, they are not a wholly adequate index.
Catalytic Incineration
An oxidation catalyst may be used to reduce the combustion temperature
required for incineration. Combustion of organic emissions in a catalytic incinerator
may be self-sustaining, given sufficiently high contaminant concentrations and
effluent temperatures. Suter4 indicates that, where heat contents are of the
ordr 10 BTU/ft3 or more, recycling part of the effluent from the catalyst for
preheating becomes practical.
Emissions from surface coating operations exist at very low concentrations
(see Table 96) due to limitations imposed by fire insurance and industrial
health regulations. Because of this fact, it is reasonable to suppose that a
preheat burner would be necessary, and this would deter from the attractiveness
of catalytic incineration.
GENERALIZED ECONOMICS FOR SURFACE COATING OPERATIONS
Figures 64 through 69 show the operating cost and total cost (operating
cost plus 10% of total installed system cost) for five pollution control systems
for surface coating operations. In each case, the concentration of solvent
(assumed to be toluene) is 100 ppm. For small systems (500 to 1000 SCFM),
catalytic incineration with heat exchange is the most economical method. This
is due to the following factors:
1. Credit for solvent recovery is too small to make carbon adsorption
attractive.
232
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FJL.TE1R
EMISSIONS
Bt-OWER
HEAT
EXCHANGER
r r
SPRAY BOOTH
-SB*
INCINERATOR
FIGURE 63
FLOW DIAGRAM OF THERMAL INCINERATION SYSTEM
-------
2. The fume concentration is low, making natural gas requirements
high, which consequently, rules out thermal incineration.
For larger systems (greater than 1000 SCFM), carbon adsorption is the
most economical method. This conclusion does not depend upon obtaining any
credit for solvent recovery. The economic advantage of carbon adsorption over
any incineration method is strictly due to its lower total cost as compared
with the other methods.
Figures 70 through 73 show the operating cost and total cost for the same
pollution control systems at a solvent concentration of 1000 ppm. If credit
for solvent recovery is not considered a factor, then for systems up to 10,000
SCFM, catalytic incineration would be the most economical method. However,
if credit for solvent recovery is considered, then carbon adsorption is the method
of choice for all systems at this fume concentration.
234
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FIGURE 64
ANNUAL COST FOR CARBON ADSORPTION
FOR SURFACE COATING OPERATIONS
500000
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235
-------
FIGURE 65
ANNUAL COSTS FOR CATALYTIC INCINERATION
(WITHOUT HEAT EXCHANGE) FOR SURFACE COATING OPERATIONS
500000
100000
K
CO
o
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' CONCENTRATION OF
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TOTAL COST _
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FIGURE 66
ANNUAL COSTS FOR CATALYTIC INCINERATION
(WITHOUT HEAT EXCHANGE) FOR SURFACE COATING OPERATIONS
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-------
FIGURE 67
ANNUAL COSTS FOR THERMAL INCINERATION
(WITHOUT HEAT EXCHANGE)
500000.
100000
to
O
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10000
1000
1000
CONCE
TOTAL (
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-------
FIGURE 68
ANNUAL COST FOR THERMAL INCINERATION
(WITH HEAT EXCHANGE) FOR SURFACE COATING OPERATIONS
500000
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239
-------
500000
FIGURE 69
ANNUAL COST FOR CARBON ADSORPTION
FOR SURFACE COATING OPERATIONS
100000
fcfl
CO
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10000
1000
1000
1 1
CONCENTRATION
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-------
FIGURE 70
ANNUAL COSTS FOR CATALYTIC INCINERATION
(WITHOUT HEAT EXCHANGE) FOR SURFACE COATING OPERATIONS
50000
10000
CO
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z
z
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ITAL CHARGES) S
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-------
FIGURE 71
ANNUAL COSTS FOR CATALYTIC INCINERATION
(HITH HEAT EXCHANGE) FOR SURFACE COATING OPERATIONS
50000
10000
O
U
z
2
<
1000
- CONCENTRATION OF SOLVENT = 1000 PPM
100
100
TOTAI
(OPERATING COST
PLUS CAPITAL CHARGES)
VL
OPERATING COST
1000
SCFM
10000
30000
242
-------
FIGURE 72
ANNUAL COSTS FOR THERMAL INCINERATION
(WITHOUT HEAT EXCHANGE)
50000
10000
V)
o
o
Z
Z
1000
100
L CONCENTRATION OF SOLVENT = 1000 PPM
TOTAL COST
(OPERATING COST
PLUS CAPITAL
ar
OPERATING COST _
100
1000
SCFM
10000
30000
243
-------
FIGURE 73
ANNUAL COST FOR THERMAL INCINERATION
(WITH HEAT EXCHANGE) FOR SURFACE COATING OPERATION
50000
CO
o
o
1000
000
100
CONCENTRATION OF SOLVENT = 1000 PP
TOTI
(OPE
PLUS
U_ COST
:RATING COST
i CAPITAL CHARGES
/
/
^
s
/
^
j
?
/
/
t
) y
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/
/
r
s
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M
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/
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ri
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/
ป%
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COST
100 1000 10000 30000
SCFM
244
-------
REFERENCES
1. Drinberg, Gurevich, and Tikhomirov, Technology of Non-Metallic Coating,
Pergamon Press, N.Y.C., 1960, p. 54.
2. Hardison, L. C., Controlling Combustible Emissions, Paint and Varnish
Production, July 1967.
3. Gadowski, R. P., David, M. P., Blahut, G.A., Evaluations of Emissions and
Control Technologies in The Graphic Arts Industries, Final Report, EPA
Contract CPA 22-69-72.
4. Suter, H. R., "Range of Applicability of Catalytic Fume Burners", LAPCA,
March, 1955, pp. 173-175.
5. Ray, Arthur B., "Recovery of Solvent Vapors", Chem and Met Eng, 47,
May 1940, pp. 329-332.
6. Experimental Program for the Control of Organic Emissions from Protective
Coating Operation, Final Report No. 8, Air Pollution Control District of Los
Angeles.
7. Schflan, L. and Jacobs, M. B., The Handbook of Solvents, New York,
Van Nostrand, 1953.
245
-------
C. ADDITIONAL COST DATA
The previous section of this report dealt with the cost of air pollution control
systems for seven specific processing applications. This section deals with the
generalized correlation of costs for each type of control system for all seven 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 coordinating
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 *
246
-------
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 of 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 automobiles.
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 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
247
-------
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 important
variable in the determination of capital charges. The rate at which money is
available varies widely from firm to firm, as well as with overall economic
considerations. The cost of capital for financing by means other than borrowing
also varies over a wide range from firm to firm. Variations in the cost of financing
can be large enough to affect the choice between alternative control systems.
For the purpose of presenting the annual operating cost data in this report,
it was decided to use the same fixed percentage of total installed cost as the
capital charge for all of the applications studied. The rate chosen was 16%. It
was based upon an estimated useful equipment life of 15 to 20 years, debt
capital availability at 9 to 11%, and a correction for the tax incentives available
to installers of pollution control hardware of 5 to 7%. Although the rate chosen
is a good general estimate, it does not purport to be the correct rate for any
specific situation. It is used only as a good estimate to assist the cost presentations
in this report.
2. 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:
Operating (operator and supervisor) Labor
Maintenance Labor and Materials
Replacement Parts
Utilities and Supplies
248
-------
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 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
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.
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)*
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
249
-------
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
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 99.
The results of these calculations for generating capital costs in dollars, are
presented in the following tables:
Process Area Table Numbers
Kraft Pulp Mills
' Conventional Recovery Furnace 100
Controlled Odor Recovery Furnace 101
Ferroalloy Furnaces
Ferrosilicon Furnace 102
Silicon Metal Furnace 103
Grain Cleaning Houses 105
Glass-Melting Furnaces 106
Crushed Stone and Aggregate
Secondary and Tertiary Rock Crusher 109, 111
Conveyor Transfer Points 110. 112
Asphalt Saturation
Asphalt Saturator 113, 114, 115
Asphalt Blow Still 116
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:
250
-------
Maximum Minimum Arithmetic
Equipment Type Value Value Average
Fabric Filters
Collector Only .967 .569 .804
Turnkey System .933 .522 .761
Glass Fiber Mat Filters
Collector Only .647
Turnkey System .728
Wet Scrubbers
Collector Only .851 .430 .589
Turnkey System .417 .276 .356
Electrostatic Precipitators
Collector Only .859 .436 .730
Turnkey System .780 .327 .656
Incinerators
Collector Only .947 .672 .810
Turnkey System .771 .562 .667
Of the five types of systems involved, fabric filters had the highest average
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 100,000 ACFM. Had more been in the 200,000-and-up
range, the cost-to-size relationship would have been even closer to linear.
The exponent for incinerators had an average value of .667 over the
10 - 50,000 ACFM size range. This was above the 0.4 exponent usually assumed,
because a number of the incinerators were of relatively larger 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 smaller incinerators. So in that size range, the cost of increasing size is relatively
small.
251
-------
TABLE 99
UNITS OF PLANT SIZE FOR EACH PROCESS AREA
Process Area Plant Size Units
Kraft Pulp Mills ADT/day Plant Capacity
Ferroalloy Furnaces Lb/hour Product
Grain Cleaning Houses Lb/hour Process Weight
Glass-Melting Furnaces Ton/day Glass Output
Crushed Stone and Aggregate
Secondary and Tertiary Rock Crusher Ton/hour Process Weight
Conveyor Transfer Points ACFM Inlet Gas Flow
Asphalt Saturation ACFM Process Gas Flow
252
-------
The average exponent derived for glass mat fiber filters was .647. The
limited amount of data on these systems precludes drawing many conclusions, but the
cost data correlations for them could be expected to resemble those for fabric filters.
Wet scrubbers had an average exponent of .589 approximately equal to
the 0.6 usually assumed for equipment. Every one of the scrubbers had an inlet gas
f tow rate below 100,000 ACFM. In this range the basic design of scrubbers is adequate
to handle these volumes of gas and the cost starts increasing gradually with size.
Exponents for electrostatic precipitators varied from .436 to .859, with
an average value of .73. In most applications the gas flow was 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 20,000 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:
253
-------
Process Area
Kraft Pulp Mills
Conventional Recovery Furnace
Controlled Odor Recovery Furnace
Ferroalloy Furnaces
Ferrosilicon Furnace
Silicon Metal Furnace
Grain Cleaning Houses
Glass-Melting Furnaces
Crushed Stone and Aggregate
Secondary and Tertiary Rock Crusher
Conveyor Transfer Points
Asphalt Saturation
Asphalt Saturator
Asphalt Blow Still
Table Numbers
117
118
119
120
121
122, 123, 124
125. 127
126, 128
129. 130. 131
132
254
-------
TABLE 100
DERIVED COST INDICES FOR KRAFT MILL RECOVERY FURNACES
COLLECTOR TYPE
ELECTROSTATIC PRECIPITATOR
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
ELECTROSTATIC PRECIPITATOR
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
3,848
4,699
18,134
_
2,570
3,583
12,723
.
X*
.773
.759
.675
_
.859
.826
.749
-
B/A
-
-
1.119
1.102
-
-
~
1.137
1.097
C/A
-
-
~
2.562
2.302
-
-
~
2.502
2.219
C/B
-
-
2.289
2.088
-
-
"
2.200
2.022
*FOR USE IN EQUATION: COST = K*(SIZE)**X
255
-------
TABLE 101
DERIVED COST INDICES FOR KRAFT MILL CONTROLLED ODOR FURNACES
COLLECTOR TYPE
ELECTROSTATIC PRECIPITATOR
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
ELECTROSTATIC PRECIPITATOR
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
4,854
5,776
14,622
-
4,617
5,471
13,739
-
_
X*
.111
.768
.750
-
.809
.803
.780
-
_
B/A
-
-
-
1.160
1.156
_
-
-
1.140
1.133
C/A
-
-
-
2.626
2.565
_
-
-
2.479
2.401
C/B ซJ
T
'' \
*Y
-
4
2.264 |
2.2l9 L
i
i
^
- 7
i
T"
...,,
2.119
T
*FOR USE IN EQUATION: COST = K*(SIZE)**X
256
-------
TABLE 102
DERIVED COST INDICES FOR FERROSIUCON FURNACE
COLLECTOR TYPE
FABRIC FILTER
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
FABRIC FILTER
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
382
554
947
_
X*
.937
.927
.928
~
B/A
-
-
1.325
1.319
C/A
-
-
~
2.300
2.291
C/B
-
-
~
1.735
1.736
*FOR USE IN EQUATION: COST = K*(SIZE)**X
257
-------
TABLE 103
DERIVED COST INDICES FOR SIUCON METAL FURNACE (DILUTION COOLING)
COLLECTOR TYPE
FABRIC FILTERS
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
459
728
1,403
_
X*
.967
.946
.933
.
B/A
-
1.345
1.330
C/A
.
2.350
2.309
C/B j
^
t
tat
<&
sad
ซwii
'*',
1.747
1.736 4;
*FOR USE IN EQUATION: COST = K*(SIZE)**X
258
-------
TABLE 104
DERIVED COST INDICES FOR SILICON METAL FURNACE (EVAPORATIVE COOLING)
COLLECTOR TYPE
FABRIC FILTERS
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
255
616
1,252
_
X*
.933
.881
.861
_
B/A
-
-
-
1.622
1.580
C/A
-
-
-
2.828
2.726
C/B
-
-
-
1.743
1.725
*FOR USE IN EQUATION: COST = K*(SIZE)**X
259
-------
TABLE 105
DERIVED COST INDICES FOR GRAIN CLEANING HOUSE
COLLECTOR TYPE
FABRIC FILTERS
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
14
18
79
_
X*
.722
.739
.678
_
B/A
-
-
~
1.514
1.547
C/A
-
-
3.846
3.650
C/B ; \
UK
\
teg
tfijfi
J
i
-
^'
2.360 (|
tetfjj
*FOR USE IN EQUATION: COST = K*(SIZE)**X
260
-------
TABLE 106
DERIVED COST INDICES FOR GLASS-MELTING FURNACE
COLLECTOR TYPE
ELECTROSTATIC PRECIPITATOR
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
ELECTROSTATIC PRECIPITATOR
f HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
, TURNKEY (C)
SMALL
LARGE
[
K*
12,656
15,192
79,681
_
X*
.436
.428
.327
_
B/A
-
, -
1.156
1.146
C/A
-
3.805
3.374
C/B
-
-
3.291
2.945
*FOR USE IN EQUATION: COST = K*(SIZE)**X
261
-------
TABLE 107
DERIVED COST INDICES FOR GLASS-MELTING FURNACE
COLLECTOR TYPE
WET SCRUBBER
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
WET SCRUBBER
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
1,933
8,307
24,693
-
X*
.430
.489
.385
-
B/A
_
-
5.648
6.028
C/A
_
-
10.385
9,885
C/B !J
*|
-i
1
f
[
- 1
" t
1.839 . '
1.640 I
1
*FOR USE IN EQUATION: COST = K*(SIZE)**X
262
-------
TABLE 108
DERIVED COST INDICES FOR GLASS-MELTING FURNACE
COLLECTOR TYPE
I FABRIC FILTER
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
FABRIC FILTER
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
5,745
8,636
23,839
_
X*
.569
.573
.522
_
B/A
-
-
.
1.532
1.539
C/A
-
-
"
3.350
3.183
C/B
-
. -
.
2.186
2.068
*FOR USE IN EQUATION: COST = K*(SIZE)**X
263
-------
TABLE 109
DERIVED COST INDICES FOR SECONDARY AND TERTIARY ROCK CRUSHER
COLLECTOR TYPE
WET SCRUBBER
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
WET SCRUBBER
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
426
1,301
11,292
_.
-
360
4,085
16,563
_
-
X*
.618
.592
.417
_
-
.644
.450
.377
-
-
B/A
-
-
2.630
2.536
-
-
~
3.752
2.867
C/A
-
-
8.389
6.343
-
-
~
10.049
6.942
C/B J
k^4
7
:. "f
!
3.190 T
2.501 1.
"i
1.
i
i
- 1
i
- j
2.678 1
2.422
1
*FOR USE IN EQUATION: COST = K*(SIZE)**X
264
-------
TABLE 110
DERIVED COST INDICES FOR CRUSHED STONE
AND AGGREGATE CONVEYOR TRANSFER POINTS
COLLECTOR TYPE
WET SCRUBBERS
LA PROCESS WEIGHT
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*
118
379
7,596
_
96
381
7,803
_
X*
.485
.474
.276
_
.506
.483
.279
.
B/A
-
-
-
2.919
2.884
-
-
-
3.251
3.170
C/A
-
-
-
10.930
8.694
-
-
11.677
9.096
C/B
-
-
-
3.744
3.015
-
-
~
3.592
2.869
ftFOR USE IN EQUATION: COST = K*CSIZE)**X
265
-------
TABLE 111
DERIVED COST INDICES FOR SECONDARY AND TERTIARY ROCK CRUSHER
COLLECTOR TYPE
FABRIC FILTERS
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
374
647
1,209
-
X*
.797
.772
.762
-
B/A
-
-
-
1.508
1.459
C/A
-
-
-
2.658
2.534
C/B ji.
"*
,
Wi
i
ซ
i
l
to*
"V
^
-
-
CSjririf
1.762
1.738 .
*FOR"USE IN EQUATION: COST = K*(SIZE)**X
266
-------
TABLE 112
DERIVED COST INDICES FOR CRUSHED STONE
AND AGGREGATE TRANSFER POINTS
COLLECTOR TYPE
FABRIC FILTER
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
26
36
126
X*
.704
.715
.644
_
B/A
-
-
-
1.529
1.549
C/A
-
-
-
2.956
2.769
C/B
-
-
-
1.933
1.788
*FOR USE IN EQUATION: COST = K*(SIZE)**X
267
-------
TABLE 113
DERIVED COST INDICES FOR ASPHALT SATURATOR
COLLECTOR TYPE
WET SCRUBBERS
LA PROCESS WEIGHT
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*
2.5
48
1,600
-
_
X*
.851
.657
.400
-
_
B/A
_
-
-
2.710
2.299
C/A
_
-
-
6.933
4.731
C/B .
T
i
.
T
i
T
.1
- 1
2!057 ta
1
*FOR USE IN EQUATION: COST = K*(SIZE)**X
268
-------
TABLE 114
DERIVED COST INDICES FOR ASPHALT SATURATOR (WITH H.E.)
COLLECTOR TYPE
THERMAL INCINERATORS
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
THERMAL INCINERATORS
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
9
10
99
_
9
10
99
_
X*
.947
.941
.771
_
.947
.941
.771
-
B/A
-
-
-
1.079
1.074
-
-
~
1.079
1.074
C/A
-
-
1.863
1.604
-
-
~
1.863
1.604
C/B
-
-
1.726
1.494
-
-
1.726
1.494
*FOR USE IN EQUATION: COST = K*(SIZE)**X
269
-------
TABLE 115
DERIVED COST INDICES FOR ASPHALT SATURATOR
COLLECTOR TYPE
GLASS FIBER MAT FILTERS
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
GLASS FIBER MAT FILTERS
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
96
75
3,384
-
X*
.647
.694
.428
_
-
B/A
-
-
-
1.248
1.298
C/A
-
-
-
3.925
3.259
C/B
~T
i
i
7
1
_
2.510
7
*FOR USE IN EQUATION: COST = K*(SIZE)**X
270
-------
TABLE 116
DERIVED COST INDICES FOR ASPHALT BLOW STILL
COLLECTOR TYPE
THERMAL INCINERATOR
LA PROCESS WEIGHT
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
THERMAL INCINERATOR
HIGH EFFICIENCY
COLLECTOR ONLY (A)
TOTAL EQUIPMENT (B)
TURNKEY (C)
SMALL
LARGE
K*
132
121
751
_
X*
.672
.689
.562
_
B/A
-
1.068
1.090
C/A
-
2.044
1.796
C/B
-
1.913
1.648
*FOR USE IN EQUATION: COST = K*(SIZE)**X
271
-------
TABLE 117
DERIVED COST PER SCFM* FOR KRAFT MILL RECOVERY FURNACES
COLLECTOR TYPE
SMALL
LARGE
ELECTROSTATIC PRECIPITATOR
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
173,600
2.70
3.03
6.93
520,800
2.11
2.32
4.85
ELECTROSTATIC PRECIPITATOR
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
173,600
3.08
3.50
7.70
520,800
2.63
2.89
5.85
*BASED ON SCFM AT 70 DEC. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
Preceding page blank
273
-------
TABLE 118
DERIVED COST PER SCFM* FOR KRAFT MILL CONTROLLED ODOR FURNACES
COLLECTOR TYPE
SMALL
LARGE
ELECTROSTATIC PRECIPITATOR
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
155,800
3.78
4.38
9.92
467,400
2.94
3.40
7.54
ELECTROSTATIC PRECIPITATOR
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
155,800
4.52
5.16
11.21
467,400
3.67
4.15
8.80
*BASED ON SCFM AT 70 DEC. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
274
-------
TABLE 119
DERIVED COST PER SCFM' FOR FERROSILICON FURNACES
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTER
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
FABRIC FILTER
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
462,500
2.72
3.61
6.26
740,000
2.65
3.49
6.06
*BASED ON SCFM AT 70 DEG. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
275
-------
TABLE 120
DERIVED COST PER SCFM* FOR SILICON METAL FURNACES
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTERS
HIGH EFFICIENCY (DILUTION COOLING)
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
277,500
2.76
3.71
6.48
462,500
2.72
3.62
6.28
FABRIC FILTERS
HIGH EFFICIENCY (EVAP. COOLING)
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
109,000
3.00
4.86
8.48
181,700
2.91
4.59
7.92
*BASED ON SCFM AT 70 DEG. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
276
-------
TABLE 121
DERIVED COST PER SCFM* FOR GRAIN CLEANING HOUSES
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTER
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
FABRIC FILTER
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
14,900
0.83
1.26
3.19
44,600
0.66
1.02
2.41
*BASED ON SCFM AT 70 DEC. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
277
-------
TABLE 122
DERIVED COST PER SCFM* FOR GLASS-MELTING FURNACES
COLLECTOR TYPE
SMALL
LARGE
ELECTROSTATIC PRECIPITATOR
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
ELECTROSTATIC PRECIPITATOR
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
11,200
8.42
9.73
32.04
26,800
5.68
6.51
19.17
*BASED ON SCFM AT 70 DEC. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
278
-------
TABLE 123
DERIVED COST PER SCFM* FOR GLASS-MELTING FURNACES
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBER
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
WET SCRUBBER
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
11,200
1.25
7.05
12.97
26,800
0.84
5.04
8.27
*BASED ON SCFM AT 70 DEG.
VAPOR.
F AT COLLECTOR INLET INCLUDING WATER
279
-------
TABLE 124
DERIVED COST PER SCFM* FOR GLASS-MELTING FURNACES
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTER
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
FABRIC FILTER
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
11,200
7.04
10.79
23.59
26,800
5.50
8.46
17.50
*BASED ON SCFM AT 70 DEG. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
280
-------
TABLE 125
DERIVED COST PER SCFM* FOR SECONDARY AND TERTIARY ROCK CRUSHER
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBER
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
19,600
0.74
1.94
6.20
68,700
0.50
1.26
3.15
WET SCRUBBER
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
19,600
0.72
2.71
7.26
68,700
0.50
1.44
3.49
*BASED ON SCFM AT 70 DEG. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
281
-------
TABLE 126
DERIVED COST PER SCFM* FOR CRUSHED STONE AND
AGGREGATE CONVEYOR TRANSFER POINTS
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBER
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
4,900
1.49
4.36
16.33
14,700
0.85
2.45
7.38
WET SCRUBBER
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
4,900
1.46
4.76
17.10
14,700
0.85
2.70
7.74
*BASED ON SCFM AT 70 DEC. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
282
-------
TABLE 127
DERIVED COST PER SCFM* FOR SECONDARY AND TERTIARY ROCK CRUSHER
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTER
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
FABRIC FILTER
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
19,600
1.79
2.71
4.77
68,700
1.54
2.25
3.91
ABASED ON SCFM AT 70 DEC. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
283
-------
TABLE 128
DERIVED COST PER SCFM* FOR CRUSHED STONE
AND AGGREGATE CONVEYOR TRANSFER POINTS
COLLECTOR TYPE
SMALL
LARGE
FABRIC FILTER
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
FABRIC FILTER
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
4,900
2.10
3.21
6.21
14,700
1.52
2.35
4.20
*BASED ON SCFM AT 70 DEG. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
284
-------
TABLE 129
DERIVED COST PER SCFM* FOR ASPHALT SATURATOR
COLLECTOR TYPE
SMALL
LARGE
WET SCRUBBER
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
WET SCRUBBER
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
20,000
0.64
1.73
4.43
50,000
0.53
1.21
2.49
*BASED ON SCFM AT 70 DEG.
VAPOR.
F AT COLLECTOR INLET INCLUDING WATER
285
-------
TABLE 130
DERIVED COST PER SCFM* FOR ASPHALT SATURATOR
COLLECTOR TYPE
SMALL
LARGE
THERMAL INCINERATOR (W/HEAT EX.)
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
20,000
6.04
6.52
11.25
50,000
5.40
5.79
8.65
THERMAL INCINERATOR (W/HEAT EX.)
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
20,000
6.04
6.52
11.25
50,000
5.40
5.79
8.65
*BASED ON SCFM AT 70 DEG. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
286
-------
TABLE 131
DERIVED COST PER SCFM* FOR ASPHALT SATURATOR
COLLECTOR TYPE
SMALL
LARGE
GLASS FIBER MAT FILTER
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFMft
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
GLASS FIBER MAT FILTER
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
20,000
3.14
3.92
12.32
50,000
2.17
2.82
7.08
*BASED ON SCFM AT 70 DEG.
VAPOR.
F AT COLLECTOR INLET INCLUDING WATER
287
-------
TABLE 132
DERIVED COST PER SCFM* FOR ASPHALT BLOW STILL
COLLECTOR TYPE
SMALL
LARGE
THERMAL INCINERATOR
MEDIUM EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
THERMAL INCINERATOR
HIGH EFFICIENCY
GAS FLOW RATE, SCFM*
COLLECTOR ONLY
TOTAL EQUIPMENT
TURNKEY SYSTEM
8,400
8.00
8.54
16.34
27,000
5.46
5.95
9.80
*BASED ON SCFM AT 70 DEC. F AT COLLECTOR INLET INCLUDING WATER
VAPOR.
288
-------
D. 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 133.
Scrubbers
Correlations were made for both the scrubber cost and for the total
installed cost of the scrubber system as a function of the inlet gas flow rate in ACFM.
Figure 74 shows the cost of the scrubber alone. The data falls fairly uniformly along a
single line. This is to be expected because all of the scrubbers that have been
considered in this section are of low to medium energy. The plotted points represent
scrubbers of similar complexity.
Figure 75 shows the relation between the cost for installed scrubber
systems and the inlet gas flow rate in ACFM. The majority of the data points fall along a
straight line. As previously mentioned, all of the scrubber systems are of similar
complexity. The only exception is the asphalt saturator application that uses a low
energy scrubber with a 3 wt% solution of potassium permanganate as the scrubber
liquor. Because of the lower operating energy which is required in this application, the
system was less expensive. The direct operating cost of the wet scrubber in this
application, however, increases because of the cost of the potassium permanganate
that is required. Direct operating costs of wet scrubbers may be found in Figure 76. This
graph 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 77,
78, and 79 illustrate, due to the wide variability in the applications involved, no true
correlation exists between the different applications 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. For inlet gas flow rates greater
289
-------
TABLE 133
PLOTTING SYMBOL KEY
Process Area Symbol
Kraft Pulp Mills
Conventional Recovery Boilers
Controlled Odor Recovery Boilers
Ferroalloy Furnaces
Ferrosilicon Furnaces with Air Dilution Coolers
Silicon Metal Furnaces with Air Dilution Coolers
Silicon Metal Furnaces with Evaporative Coolers
Grain Cleaning Houses
Glass Manufacturing
Crushed Stone and Aggregate Industry
Secondary and Tertiary Rock Crusher
Crushed Stone and Aggregate Transfer
Asphalt Saturation
Asphalt Saturator
Asphalt Blowing Still
290
-------
than 100,000 ACFM, the air-to-cloth ratio approaches a constant value, and 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. The capital costs of fabric filters are given as Figure
77, installed costs of filter systems appear in Figure 78, and direct operating costs of
fabric filter systems are presented in Figure 79. All of the costs have been correlated
with the inlet gas flow rate in ACFM. Actual costs of filters and systems for flow rates of
100,000 ACFM or less vary in this study between the dashed lines of these figures, and
single, unique correlations of cost with gas flow rate to the filter system can not be
established in this range.
Incinerators
There were only two applications in this study for which incinerator
cost information was obtained. All of these units were thermal incinerators, and heat
exchangers were specified for each unit. Inlet gas flow rates were between 10,000 and
60,000 ACFM.
The capital cost of the incinerator alone appears in Figure 80 as a
function of the inlet gas flow rate. In Figure 81, the installed cost correlation has been
plotted for these systems. In this range of inlet gas flow rates, the costs of installed
systems increase significantly with increasing size. Differences in operating costs for
medium and high efficiency incineration systems were not significant for the asphalt
saturator application.
Electrostatic Precipitators
Capital costs of electrostatic precipitator units are presented
graphically as Figure 83, and installed costs of precipitator systems are given in Figure
84. A high efficiency precipitator costs about 25 to 30 percent more than a medium
efficiency unit, and a high efficiency precipitator system has a 15 to 20 percent greater
installed cost than a medium efficiency system, for an identical inlet gas flow rate. The
cost of the installed system varied from about 2 to 3.5 times that of the precipitator
alone.
Figure 85 shows the direct operating costs of precipitators. The data
indicate that the cost of operating a high efficiency unit is roughly 10% more than that of
291
-------
operating a medium efficiency unit, for the applications that have been studied. Nearly
all of the increase is due to the increased use of electrical power.
Glass Fiber Mat Filters
Glass fiber mat filtration 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.
292
-------
FIGURE 74
COST OF WET SCRUBBERS ONLY
JO3
INLET GAS PLOW RATE, ACFM
NOT REPRODUCIBLE
293
-------
FIGURE 75
TOTAL INSTALLED COST OF SCRUBBING SYSTEMS
INLET GAS FLOW RATE, ACFM
294
-------
s
K
O.
DIRECT
FIGURE 76
COST OF WET SCRUBBERS
'to*
INLET GAS FLOW RATE, ACFM
NOT REPRODUCIBLE
295
-------
FIGURE 77
CAPITAL COSTS OF FABRIC FILTERS
8
I
INLET GAS FLOW RATE, ACFM
296
-------
FIGURE 78
INSTALLED COSTS OF FABRIC FILTERS
H-H-
t-^
H t
tHi
/
a
M
i
gs
fiii
#
v_
fir
f-u-;
10
9
6
7
T
-r'H-!
n
$
W'
LJJ
' ! I
TIT
^
-1+
a
,-H-
:UT
-, _J
"1 " "*~
T-~-*~
tpm:
i
^T
ฎ
mi
o
i
mnt
LUo.
j
10s
_ . -U
-]-ijJ-
m
-ff-
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'"
r?d
i'il
rl
Jt
-r
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iJ.I!"II. _i".j~t. r -1-r-r*- -T-J-"---
ฑtt
rtr -tr.:
ffi
ttri
1
"" "t""
it"
"
3-15
I . ,
10s
' TtT 1"
3 4 6678
107
INLET GAS FLOW RATE, ACFM
297
-------
FIGURE 79
DIRECT OPERATING COSTS OF FABRIC FILTERS
.10
10*
5 5 7 8 9 10T
INLET GAS FLOW RATE, ACFM
298
-------
FIGURE 80
CAPITAL COSTS OF THERMAL INCINERATORS
(A
&
-3
c
10ฐ
<|
f
7
s
5 ,
4
3
75
2
15
10ป
q
8
6
5-
4
1
25
?
15
10*
1
: : : ' ': ': '. '.
.:.; i liv-
"i. '..; '. ; : : '
I
.
-
ir_ -
,-
f
\
\ I
i
t . . .
: ' : ; >
. yX-
r-
..
I :
' .
4
;.:... :'::.'.
IT i
:::!: ::;
-
- "
i
...y
: i/*^ ' : :
5 2
x\/
2.
.X
i\ ::
5 3
x
. 1
X
/
4
1
X
5
'P*
V
X
6
,/
?
S
/
8
X
k'
1
1
I
L
/
X
I X
.'
0* |
X
i X
1
1
i 2
; . i . ' . '-'.
2
.
.::!:'
5 3
....
..:..
....
.'.!'
4
5
...
6
: : ::
i.z;.
- '
7
:.._
-;
~.r
-
<
. \
"
--
9
:;r:
;;r
"
11
INLET GAS FLOW RATE, ACFM
NOT REPRODUCIBLE
299
-------
INLET GAS FLOW RATE, ACFM
s 7 a e 10*' a
7 a a 10*
-------
FIGURE 82
OPERATING COST
OF THERMAL INCINERATORS WITH HEAT EXCHANGE
f-EiiUf
3-
2.5-
r_i ., i i i i. ;
ieffhttfl i
P:
E.M
tSur
ff; 'Z~.
1.5-
tit
lit
10.
t
ffi
t-
M
ฉ
O
i J:'tnr 5-
Lriu.TlTS.1-
fe
:u
1
rPrfirQ
TttuiT
i*rtWi
JiJiilL.
t i_n-*: -F-
sstti
iliii
jj;-;
),-::
If;
il!" i::;:.
If
;-ri:S3s
. .-.-.-*-,iZ
-j4-p-l t.
?iSSh^
1.5.
lili
5EI
fit
1-ri-rr
1.5
2 2.5 3
5 6789
io''
1.5
2.5 3
5 6789
INLET GAS FLOW RATE, ACFM
301
-------
FIGURE 83
CAPITAL COST OF ELECTROSTATIC PRECIPITATORS
INLET GAS FLOW RATE, ACFM
302
-------
FIGURE 84
INSTALLED COST OF ELECTROSTATIC PRECIPITATORS
107 L
if
3-
2.5-
1.5-
1!
10ฐ
x:
4 ~"
' '
il-C
_ i
?/
X
EFFICIENCY
J
3.
2.5
H
MEDIUM EFFICIENCY '<
11
10s H *-
~i&:
1.5
2 2.5 3
5 6 7 8 9
ios'
1.5
2 2.5 3
5 6 7 8 9 10*
INLET GAS FLOW RATE, ACFM
303
-------
FIGURE 85
DIRECT OPERATING COST OF ELECTROSTATIC PRECIPITATORS
INLET GAS FLOW RATE, ACFM
304
-------
APPENDIX
A. SPECIFICATIONS FOR ABATEMENT EQUIPMENT
I. 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 con-
venient access to all points requiring observation or main-
tenance.
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. Conveying Equipment
305
-------
3. A turnkey installation of the entire system including the following
installation costs:
a. Engineering
b. Foundations and Support*
c. Ductwork
d. Stack
e. Insulation
f. Electrical
g. Piping
h. Painting
i. Startup
j. Performance Test
k. Other
C. For the "pollution abatement device only" quotation, the vendor shall
furnish the equipment FOB point of manufacture, and shall furnish as a
part of this project competent supervision of the erection, which shall
be by others.
D. Vendor shall furnish* the following drawings, etc., as a minimum:
1. With his proposal:
a. Plan and elevation showing general arrangement.
b. Typical details of collector internals proposed.
c. Data relating to projected performance with respect to pressure
drop, gas absorption efficiency, and paniculate removal
efficiency to operating parameters such as gas flow.
'This is a typical request. The member companies are NOT to furnish this material
under the present project.
'Predicated on ideal soil conditions.
306
-------
When the detailed analysis method is used to estimate operating and maintenance
labor costs, a brief statement of the assumptions made will be helpful in combining
the estimates of several member companies.
The least desirable method of estimating maintenance and operating labor costs
involves the use of a fraction of total capital cost. Operating labor costs bear
little relationship to capital cost of the equipment, and it may be true that increasing
the capital cost will decrease the labor requirement (for example, where additional
instrumentation is used to minimize operator attention). The use of a fraction of
capital cost should therefore not be used as a basis for estimating operating labor
in any case.
Maintenance costs are sometimes obtained by conducting industry-wide surveys
and the results reported in terms of total dollars for labor and material or as a
fraction of the installed cost of the equipment. For example, a survey of maintenance
costs in the chemical process industries reported an annual expenditure of approxi-
mately 6% of total installed system cost for a wide variety of chemical equipment.
It might be reasonable to allocate half of this cost to labor and half to spare
parts and report a labor cost of 3% of the total installed cost. This is not recommended
and should be used only when there is no other basis available. The use of this
system and the source of the information on which the estimate is based should
be clearly indicated.
307
-------
IV. PROCESS PERFORMANCE GUARANTEE
A. The equipment will be guaranteed to reduce the paniculate and/or gas
contaminant loadings as indicated in the service description.
B. Performance test will be conducted in accordance with I.G.C.I, test
methods where applicable.
C. Testing shall be conducted at a time mutually agreeable to the customer
and the vendor.
D. The cost of the performance test is to be included in vendor's turnkey
proposal.
E. In the event the equipment fails to comply with the guarantee at the
specified design conditions, the vendor shall make every effort to correct
any defect expeditiously at his own expense. Subsequent retesting to
obtain a satisfactory result shall be at the vendor's expense.
V. 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 carry the manufacturer's guarantee.
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 specified codes.
Preceding page blank 3o9
-------
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.
b. 30 days prior to shipment:
1) Certified drawings of equipment, six sets
2) Installation instructions, six sets
c. 30 days prior to startup:
1) Starting and operating instructions, six sets
2) 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 III and to good engineering
practice.
-------
B. INSTRUCTIONS FOR SUBMITTING COST DATA
Two forms (two copies each) are enclosed with each specification. They have
been designed for the purpose of reporting the cost estimate prepared for each
specification. The forms are titled:
A. Estimated Capital Cost Data
B. Annual Operating Cost Data
These'forms will also be used to exhibit, in the final report for this study, 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 only for the convenience of those reading
the form.
You should fill in the estimated dollar amounts 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 distinction between
those items included here and those included in the "Installation" costs.
311
-------
Do NOT include any of the cost of erecting or installing auxiliaries in
this category.
3. "Installation Cost" should include the field labor required to complete
a turnkey installation as well as all of the material not in 1. or 2. 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.
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
(for each chemical used)
Air Resources will average the consumption figures reported, and convert them to
dollar values for inclusion in the final report, using standard unit prices.
Be sure that the operating factor, indicated on the form in hours per year, is
used for estimating the utility and labor requirements.
Guidelines for Operating Cost Estimates
The estimates of labor cost involved for operating and maintaining air pollution control
312
-------
systems are less likely to be based on first-hand knowledge than are the estimates
of capital cost for the gas cleaning equipment and system installation. In order
to make comparable and consistent estimates of these costs, some general rules
should be used by all of the participants in the program. This section describes
the rules which should be followed in making the estimates, and for describing the
estimating basis in the reports prepared for the EPA.
Three alternative bases may be used for estimating the labor cost for operation
and maintenance of air pollution systems:
1. Direct first-hand knowledge of similar systems.
2. Detailed analysis of incremental labor requirements.
3. Percentage of first cost.
These alternatives are listed in order of preference; that is, direct first-hand knowledge
of labor costs is the most desirable, and a percentage of the first cost of the system,
the least desirable basis for estimating. The member companies are requested to
indicate which of these bases was used in the preparation of each labor cost
estimate.
Direct first-hand knowledge comprises detailed records of the man-hours employed
by the owner of an air pollution control system for operation and/or maintenance
of the equipment.
This information should be sufficiently detailed to determine that the time was
actually spent in connection with the operating or maintenance function for the
abatement system, and not simply an arbitrary allocation of operators' or mechanics'
time between a process system and the associated abatement equipment. Such data
should be used only if it is available for a system similar to that being quoted
under this contract. A system should be considered similar only if it is used within
the subject industry and on substantially the same process as that being quoted.
If the process size is significantly different from that which is the subject of the
quotation, the labor costs may be scaled up or down on the basis of realistic
appraisals of the difference in requirements between large and small systems. It
is not realistic to scale labor costs in proportion to the size of the system.
Although first-hand information is the most desirable basis for estimating maintenance
and operating costs, it is unlikely that acceptable first-hand information will be
available often to the member companies. When it is used, the member company
should indicate the source of the data; i.e., system owned and operated by member,
feedback from customer, industry or user survey program, etc.
313
-------
A detailed analysis of probable costs is likely to be the best method available
to the member companies for estimating operating and maintenance labor. A
satisfactory detailed analysis need not be complex nor time-consuming. However,
the estimate should be made in sufficient detail that man-hour allocations are made
to specific functions, as opposed to blanket assumptions of total operating or total
maintenance labor. For example, the labor required to rebalance the fan wheel and
replace defective belts on an annual basis is a reasonable item with regard to
level of detail.
When using this method, it is important to define clearly the assumptions made
with regard to the circumstances of system operation. Some of these assumptions
are indicated in a general way below:
1. Operating labor.
a. Will the abatement system be operated by the same crew charged
with operation of the production equipment? If yes, operator time
should be allocated to the new abatement system.
b. Are regular logs of operation likely to be helpful in obtaining best
operation of the abatement equipment?
c. Is additional supervisory time required? If yes, some supervisor
time should be allocated to the abatement system.
d. Will any special operator skill be required which would limit the
ability of production equipment operators to serve as abatement
system operators?
2. Maintenance labor.
a. Will maintenance functions be performed routinely throughout the
year, or at annual or semi-annual equipment maintenance shutdown
periods?
b. Have routine maintenance and inspection procedures been
recommended?
c. Will there be any special requirements for labor to purchase or
inventory spare parts?
3. Can there be any labor credit for improvements in production equipment
operation due to the installation of the abatement system?
314
-------
C. 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
315
-------
D. AVERAGE HOURLY LABOR RATES BY TRADE
Trade
Common Building Labor
Skilled Average
Helpers Average
Foremen (usually 35d 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
Preceding page blank
317
-------
E. LIST OF STANDARD ABBREVIATIONS
feet or foot
inch or inches
ton or tons
pound or pounds
hours or hours
minute or minutes
parts per million
grain or grains
weight percent
actual cubic feet per minute
standard cubic feet per minute
dry standard cubic feet per minute
standard cubic feet
actual cubic feet
British thermal units
odor units
volume
mole
gallon
per cent
dollars
degrees Fahrenheit
pounds per square inch gauge
change of pressure (delta pressure)
water column (pressure)
change of temperature (delta temperature)
temperature
feet per minute
dry standard cubic feet
cubic feet
revolutions per minute
gallons per minute
millions (106)
atmospheres gage (pressure)
milligrams
micrograms
international unit
hundred weight (100 pounds)
hydrocarbon
United States pharmacopoeia
ft
in.
ton
Ib
hr
min
ppm
gr
wt.%
ACFM
SCFM
DSCFM
SCF
ACF
Btu
o.u.
vol
mol
gal
%
$
ฐF
psig
A P
w.c.
A T
Temp
FPM
DSCF
ft3
rpm
gpm
MM
atmg
m9
Y9
ID
cwt
Hcbn
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