CONTROL TECHNIQUES
FOR
PARTICULATE AIR POLLUTANTS
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Consumer Protection and Environmental Health Service
-------
CONTROL TECHNIQUES
FOR
PARTICULATE AIR POLLUTANTS
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Consumer Protection and Environmental Health Service
National Air Pollution Control Administration
Washington, D.C.
January 1969
-------
Notional Air Pollution Control Administration Publication No. AP-51
-------
PREFACE
Throughout the development of Federal air pollution legislation, the
Congress has consistently found that the States and local governments have the
primary responsibility for preventing and controlling air pollution at its source.
Further, the Congress has consistently declared that it is the responsibility
of the Federal government to provide technical and financial assistance to State
and local governments so that they can undertake these responsibilities.
These principles were reiterated in the Air Quality Act of 1967. A key
element of that Act directs the Secretary of Health, Education, and Welfare to
collect and make available information on all aspects of air pollution and its
control. Under the Act the issuance of control techniques information is a
vital step in a program designed to assist the States in taking responsible
technological, social, and political action to protect the public from the
adverse effects of air pollution.
Briefly, the Act calls for the Secretary of Health, Education, and Welfare
to define the broad atmospheric areas of the Nation in which climate,
meteorology, and topography, all of which influence the capacity of air to
dilute and disperse pollution, are generally homogeneous.
Further, the Act requires the Secretary to define those geographical
regions in the country where air pollution is a problemwhether interstate or
intrastate. These air quality control regions are designated on the basis of
meteorological, social, and political factors which suggest that a group of
communities should be treated as a unit for setting limitations on concentrations
of atmospheric pollutants. Concurrently, the Secretary is required to issue
air quality criteria for those pollutants he believes may be harmful to health
or welfare, and to publish related information on the techniques which can be
employed to control the sources of those pollutants.
in
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Once these steps have been taken for any region, and for any pollutant
or combination of pollutants, then the State or States responsible for the
designated region are on notice to develop ambient air quality standards ap-
plicable to the region for the pollutants involved, and to develop plans of action
for meeting the standards.
The Department of Health, Education, and Welfare will review, evaluate,
and approve these standards and plans and, once they are approved, the States
will be expected to take action to control pollution sources in the manner
outlined in their plans.
At the direction of the Secretary, the National Air Pollution Control
Administration has established appropriate programs to carry out the several
Federal responsibilities specified in the legislation.
Control Techniques for Particulate Air Pollutants is the first of a series
of documents to be produced under the program established to carry out the
responsibility for developing and distributing control technology information.
The document is the culmination of intensive and dedicated effort on the part
of many persons.
In accordance with the Air Quality Act, a National Air Pollution Control
Techniques Advisory Committee was established, having a membership
broadly representative of industry, universities, and all levels of government.
The committee, whose members are listed following this discussion, provided
invaluable advice in identifying the best possible methods for controlling the
sources of particulate air pollution, assisted in determining the costs involved,
and gave major assistance in drafting this document.
As further required by the Air Quality Act, appropriate Federal
departments and agencies, also listed on the following pages, were consulted
prior to issuance of this document. A Federal consultation committee,
comprising members designated by the heads of 17 departments and agencies,
reviewed the document, and met with staff personnel of the National Air
Pollution Control Administration to discuss its contents.
IV
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During 1967, at the initiation of the Secretary of Health, Education, and
Welfare, several government-industry task groups were formed to explore
mutual problems relating to air pollution control. One of these, a task group
on control technology research and development, looked into ways that industry
representatives could participate in the review of the control techniques reports.
Accordingly, several industrial representatives, listed on the following pages,
reviewed this document and provided helpful comments and suggestions. In
addition, certain consultants to the National Air Pollution Control Administration
also reviewed and assisted in preparing portions of this document. (These
also are listed on the following pages.)
The Administration is pleased to acknowledge the efforts of each of the
persons specifically named, as well as those of the many not so listed who
contributed to the publication of this volume. In the last analysis, however,
the National Air Pollution Control Administration is responsible for its content.
The control of air pollutant emissions is a complex problem because of
the variety of sources and source characteristics. Technical factors
frequently make necessary the use of different control procedures for different
types of sources. Many techniques are still in the developmental stage, and
prudent control strategy may call for the use of interim methods until these
techniques are perfected. Thus, we can expect that we will continue to
improve, refine, and periodically revise the control technique information so
that it will continue to reflect the most up-to-date knowledge available.
John T. Middleton
Commissioner
National Air Pollution Control
Administration
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NATIONAL AIR POLLUTION CONTROL TECHNIQUES ADVISORY COMMITTEE
Mr. Louis D. Alpert
General Manager
Midwestern Department of the
Federated Metals Division
American Smelting & Refining Company
Whiting, Indiana
Professor James H. Black*
Department of Chemical Engineering
University of Alabama
University, Alabama
Mr. Robert L. Chass
Chief Deputy Air Pollution
Control Officer
Los Angeles County Air Pollution
Control District
Los Angeles, California
Mr. W. Donham Crawford
Administrative Vice President
Consolidated Edison Company
of New York, Inc.
New York, New York
Mr. Herbert J. Dunsmore
Assistant to Administrative
Vice President of Engineering
U. S. Steel Corporation
Pittsburgh, Pennsylvania
Mr. John L. Gilliland
Technical Director
Ideal Cement Company
Denver, Colorado
Mr. James L. Parsons
Consultant Manager
Environmental Engineering
Engineering Department
E. I. duPont de Nemours & Co. , Inc.
Wilmington, Delaware
Professor August T. Rossano
Department of Civil Engineering
Air Resource Program
University of Washington
Seattle, Washington
Mr. Jack A. Simon
Principal Geologist
Illinois State Geological Survey
Natural Resources Building
Urbana, Illinois
Mr. Victor H. Sussman
Director
Division of Air Pollution Control
Pennsylvania Department of
Health
Harrisburg, Pennsylvania
Mr. Earl L. Wilson, Jr.
Manager
Industrial Gas Cleaning Department
Koppers Company, Inc.
Metal Products Division
Baltimore, Maryland
Dr. Harry J. White
Head
Department of Applied Science
Portland State College
Portland, Oregon
Resigned September 16, 1968.
VI
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FEDERAL AGENCY LIAISON REPRESENTATIVES
Department of Agriculture
Kenneth E. Grant
Associate Administrator
Soil Conservation Service
Department of Commerce
Paul T. O'Day
Staff Assistant to the Secretary
Department of Defense
Colonel Alvin F. Meyer, Jr.
Chairman
Environmental Pollution Control Committee
Department of Housing and Urban Development
Charles M. Haar
Assistant Secretary for Metropolitan Development
Department of the Interior
Harry Perry
Mineral Resources Research Advisor
Department of Justice
Walter Kiechel, Jr.
Assistant Chief
General Litigation Section
Land and Natural Resources Division
Department of Labor
Dr. Leonard R. Linsenmayer
Deputy Director
Bureau of Labor Standards
Department of Transportation
William H. Close
Assistant Director for Environmental Research
Office of Noise Abatement
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Department of the Treasury
Gerard M. Brannon
Director
Office of Tax Analysis
Federal Power Commission
F. Stewart Brown
Chief
Bureau of Power
General Services Administration
Thomas E. Crocker
Director
Repair and Improvement Division
Public Buildings Service
National Aeronautics and Space Administration
Major General R. H. Curtin, USAF (Ret.)
Director of Facilities
National Science Foundation
Dr. Eugene W. Bierly
Program Director for Meteorology
Division of Environmental Sciences
Post Office Department
Louis B. Feldman
Chief
Transportation Equipment Branch
Bureau of Research and Engineering
Tennessee Valley Authority
Dr. F. E. Gartrell
Assistant Director of Health
U. S. Atomic Energy Commission
Dr. Martin B. Biles
Director
Division of Operational Safety
viu
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Veterans Administration
Gerald M. Hollander
Director of Architecture and Engineering
Office of Construction
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CONTRIBUTORS
Mr. L. P. Augenbright
Assistant Sales Manager
Western Knapp Engineering Division
Arthur G. McKee and Company
San Francisco, California
Dr. Allen D. Brandt
Manager
Industrial Health Engineering
Bethlehem Steel Company
Bethlehem, Pennsylvania
Mr. William Bodle
Senior Advisor
Institute of Gas Technology
Chicago, Illinois
Dr. Donald A. Borum
Consulting Chemical Engineer
New York, New York
Mr. John D. Cap Ian
Technical Director
Basic and Applied Sciences
Research Laboratories
General Motors Corporation
Warren, Michigan
Mr. R. R. Chambers
Vice President
Sinclair Oil Corporation
New York, New York
Mr. John M. Depp
Director
Central Engineering Department
Monsanto Company
St. Louis, Missouri
Mr. Harold F. Elkin
Sun Oil Company
Philadelphia, Pennsylvania
Mr. B. R. Gebhart
Vice President
Freeman Coal Mining Corporation
Chicago, Illinois
Mr. James R. Jones
Chief Combustion Engineer
Peabody Coal Company
Chicago, Illinois
Mr. Olaf Kayser
Vice President-Manufacturing
Lone Star Cement Corporation
New York, New York
Mr. David Lurie
Consultant
Wyckoff, New Jersey
Mr. Glenn A. Nesty
Vice President
Senior Technical Officer
Allied Chemical Corporation
New York, New York
Dr. Arthur L. Plumley
Senior Project Engineer
Kresinger Development
Laboratory
Combustion Engineering, Inc.
Windsor, Connecticut
Mr. James H. Rook
Director of Environmental
Control Systems
American Cyanamid Company
Wayne, New Jersey
Mr. T. W. Schroeder
Manager of Power Supply
Illinois Power Company
Decatur, Illinois
x
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Dr. Seymour C. Schuman
Private Consultant
Princeton, New Jersey
Mr. R. W. Scott
Coordinator for Conservation
Technology
Esso Research and Engineering
Company
Linden, New Jersey
Mr. David Swan
Vice President-Technology
Kennecott Copper Corporation
New York, New York
Mr. R. A. Walters
Project Director of Smelter Studies
Western Knapp Engineering Division
Arthur G. McKee and Company
San Francisco, California
XI
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CONTENTS
Page
PREFACE iu
LIST OF FIGURES
LIST OF TABLES xxxi
SUMMARY 1
1. INTRODUCTION 1-1
2. BACKGROUND INFORMATION 2-1
2.1 DEFINITIONS 2-1
2.2 MAJOR SOURCES OF PARTICULATE MATTER 2-3
2.2.1 Combustion Sources 2-3
2.2.2 Industrial Sources 2-4
2.2.3 Mobile Sources 2-4
3. PARTICULATE SOURCES AND CONTROLS 3-1
3.1 INTRODUCTION 3-1
3.2 INTERNAL COMBUSTION ENGINES 3-3
3.2.1 Gasoline- Fueled Vehicles 3-3
3.2.2 Diesel-Powered Vehicles 3-7
3.3 CONTROL OF PARTICULATE EMISSIONS FROM
STATIONARY COMBUSTION SOURCES 3-10
3.3.1 Introduction 3-10
3.3.1.1 General 3_10
3.3.1.2 Sources 3-10
xn
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Page
3.3.1.3 Emissions 3-10
3.3.2 Control Techniques 3-15
3.3.2.1 Gas Cleaning 3-16
3.3.2.2 Source Relocation 3-20
3.3.2.3 Energy Substitution 3-20
3.3.2.4 Energy Conservation 3-25
3.3.2.5 Good Practice 3-27
3.3.2.6 Source Shutdown 3-30
3.3.2.7 Dispersion 3-30
3.4 INDUSTRIAL PROCESSES 3-31
3.4.1 Introduction 3-31
3.4.2 Iron and Steel Mills 3-34
3.4.2.1 Sintering Plants 3-34
3.4.2.2 Blast Furnaces 3-34
3.4.2.3 Steel Furnaces 3-35
3.4.3 Gray Iron Foundries 3-37
3.4.4 Petroleum Refineries 3-39
3.4.5 Portland Cement 3-41
3.4.6 Kraft Pulp Mills 3-42
3.4.7 Asphalt Batching Plants 3-43
3.4.8 Acid Manufacture 3-44
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Page
3.4.8.1 Sulfuric Acid 3-44
3.4.8.2 Phosphoric Acid 3-45
3.4.9 Coke Manufacture 3-45
3.4.10 Primary and Secondary Recovery of Copper, Lead,
Zinc, and Aluminum 3-49
3.4.11 Soap and Synthetic Detergent Manufacture 3-50
3.4.12 Glass Furnaces and Glass Fiber Manufacture 3-51
3.4.13 Carbon Black 3-53
3.4.14 Gypsum Processing 3-53
3.4.15 Coffee Processing 3-54
3.4.16 Cotton Ginning 3-56
3.5 CONSTRUCTION AND DEMOLITION 3-57
3.5.1 Introduction 3-57
3.5.2 Demolition of Masonry 3-58
3.5.3 Open Burning 3-58
3.5.4 Road Dust 3-59
3.5.5 Grading Roads and Other Surfaces 3-59
3.5.6 Handling Dusty Materials 3-59
3.5.7 Sandblasting 3-59
3.6 SOLID WASTE DISPOSAL 3_61
3.6.1 Introduction 3-61
3.6.2 Definition of Solid Waste 3_62
xiv
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Page
3.6.3 Amounts of Solid Waste Generated 3-63
3.6.3.1 Disposal Methods to Minimize Air Pollution 3-65
3.6.3.2 Disposal Methods Without Incineration 3-67
3.6.3.3 Disposal Methods With Incineration 3-73
3.6.4 Air Pollution Potential From Solid Waste Disposal
Methods 3-86
3.6.5 Public Health Service Programs and Assistance
in Solid Waste Disposal 3-86
4. GAS CLEANING DEVICES 4-1
4.1 INTRODUCTION 4-1
4.1.1 Preliminary Selection of Equipment 4-3
4.2 SETTLING CHAMBERS 4-10
4.2.1 Introduction 4-10
4.2.2 Definition of Terms 4-10
4.2.3 Design Considerations 4-12
4.2.4 Typical Applications 4-13
4.3 DRY CENTRIFUGAL COLLECTORS 4-15
4.3.1 Introduction 4-15
4.3.2 Types of Centrifugal Collectors 4-16
4.3.3 Design 4-19
4.3.3.1 Operating Pressure Drop 4-26
4.3.3.2 Dust Loading 4-27
4.3.3.3 Other Design Considerations 4-28
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Page
4.3.4 Typical Applications 4-29
4.4 WET COLLECTORS AND MIST ELIMINATORS 4~32
4.4.1 Introduction 4-32
4.4.1.1 Collection Theory 4-32
4.4.1.2 Efficiency 4-34
4.4.2 Equipment Description and Design 4-35
4.4.2.1 Spray Chamber 4-35
4.4.2.2 Gravity Spray Towers 4-39
4.4.2.3 Centrifugal Spray Scrubbers 4-40
4.4.2.4 Impingement Plate Scrubbers 4-43
4.4.2.5 Venturi Scrubbers 4-44
4.4.2.6 Packed Bed Scrubbers 4-51
4.4.2.7 Self-Induced Spray Scrubbers 4-59
4.4.2.8 Mechanically Induced Spray Scrubbers 4-59
4.4.2.9 Disintegrator Scrubbers 4-61
4.4.2.10 Centrifugal Fan Wet Scrubbers 4-63
4.4.2.11 Inline Wet Scrubber 4-63
r
4.4.2.12 Irrigated Wet Filters 4-66
4.4.2.13 Wet Fiber Mist Eliminators 4-66
4.4.2.14 Impingement Baffle Mist Eliminators 4-73
4.4.2.15 Vane-Type Mist Eliminators 4.74
4.4.2.16 Packed Bed Mist Eliminators 4-76
xvi
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Page
4.4.2.17 Mist and Vapor Suppression 4-76
4.4.2.18 Liquid Distribution 4-77
4.4.2.19 Spray Nozzles 4-78
i
4.4.3 Typical Applications of Wet Scrubbers 4-83
4.4.4 Water Disposal 4-83
4.4.4.1 Settling Tanks and Ponds 4-83
4.4.4.2 Continuous Filtration 4-85
4.4.4.3 Liquid Cyclones 4-85
4.4.4.4 Continuous Centrifuge 4-85
4.4.4.5 Chemical Treatment 4-86
4.5 HIGH-VOLTAGE ELECTROSTATIC PRECIPITATORS 4-87
4.5.1 Introduction 4-87
4.5.2 Operating Principles 4-87
4.5.3 Equipment Description 4-91
4.5.3.1 Voltage Control and Electrical Equipment 4-91
4.5.3.2 Discharge Electrodes 4-95
4.5.3.3 Collecting Surfaces 4-95
4.5.3.4 Removal of Collected Particulate Matter 4-95
4.5.4 High-Voltage Electrostatic Precipitator
Equipment Design 4-99
4.5.4.1 Conditioning Systems 4-101
4.5.4.2 Voltage, Electrical Energy, and Sectionalization
Requirements 4-101
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331-716 O - 69 - 2
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Page
4.5.4.3 Gas Velocity, Treatment Time, and Flow
Distribution 4-102
4.5.4.4 Collecting Surfaces and Discharge Electrodes 4-103
4. 5. 4. 5 Materials of Construction 4-104
4.5.4.6 Collected Particulate Matter Handling Systems 4-104
4.5.4.7 Controls and Instruments 4-104
4.5.4.8 Layout 4-105
4.5.5 Specifications and Guarantees 4-105
4.5.6 Maintaining Collection Efficiency 4-107
4.5.7 Improvement of Collection Efficiency 4-108
4.5.8 Typical Applications 4-109
4.5.8.1 Pulverized Coal-Fired Power Plants 4-109
4.5.8.2 Integrated Steel Making Operations 4-111
4.5.8.3 Cement Industry 4-111
4.5.8.4 Kraft Pulp Mills 4-112
4.5.8.5 Sulfuric Acid 4-112
4.6 LOW-VOLTAGE ELECTROSTATIC PRECIPITATORS 4-113
4.6.1 Introduction 4-113
4.6.2 Major Components of Low-Voltage Electrostatic
Precipitators 4-114
4.6.3 Auxiliary Equipment 4-116
4.6.4 Design Parameters 4-116
xvi 11
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.Page
4.6.5 Materials of Construction 4-123
4.6.6 Typical Applications of Low-Voltage Electrostatic
Precipitators 4-123
4.6.6.1 Machining Operations 4-123
4.6.6.2 Asphalt Saturators 4-124
4.6.6.3 Meat Smokehouses 4-124
4.6.6.4 Other Applications 4-125
4.6.7 Air Distribution 4-125
4.6.8 Maintenance 4-126
4.7 FABRIC FILTRATION 4_127
4.7.1 Introduction 4-127
4.7.1.1 Range of Application 4-127
4.7.2 Mechanisms of Fabric Filtration 4-129
4.7.2.1 Direct Interception 4-130
4.7.2.2 Inertial Impaction 4-130
4.7.2.3 Diffusion 4-131
4.7.2.4 Electrostatic Attraction 4-132
4.7.2.5 Gravitational Settling 4-132
4.7.3 Filter Resistance 4-132
4.7.3.1 Clean Cloth Resistance 4-132
4.7.3.2 Dust Mat Resistance 4-134
4.7.3.3 Effect of Resistance on Design 4-137
xix
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Page
4.7.4 Equipment Description and Design 4-138
4.7.4.1 Baghouse Design 4-149
4.7.4.2 Fabric Filter Shape 4-155
4.7.4.3 Cloth Type 4-158
4.7.4.4 Fabric Cleaning 4-164
4.7.4.5 Fabric Selection 4-171
4.7.4.6 Auxiliary Equipment 4-173
4.7.4.7 Individual Collectors Versus Large Collecting
Systems 4-174
4.7.5 Typical Applications 4-175
4.7.5.1 Cement Kilns 4-175
4.7.5.2 Foundry Cupolas 4-176
4.7.5.3 Electric Arc Steel Furnaces 4-176
4.7.5.4 Open Hearth Furnaces 4-177
4.7.5.5 Nonferrous Metal Furnaces 4-178
4.7.5.6 Carbon Black Plants 4-179
4.7.5.7 Grain Handling Operations 4-179
4.7.6 Operational Practices 4-180
4.7.7 Maintenance Procedures 4-181
4.7.8 Safety 4-183
4.8 AFTERBURNERS 4-184
4.8.1 Introduction 4-184
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Page
4.8.1.1 Definition of Terms 4-184
4.8.1.2 Advantages and Disadvantages of Afterburners 4-185
4.8.1.3 Combustion Theory 4-186
4.8.2 Afterburner Design Criteria 4-189
4.8.2.1 General 4-189
4.8.2.2 Heat Transfer 4-189
4.8.2.3 Reaction Temperature 4-189
4.8.2.4 Retention Time 4-191
4.8.2.5 Heat Recovery 4-196
4.8.2.6 Fuel Requirements 4-200
4.8.2.7 Modified Furnace Afterburners 4-202
4.8.2.8 Hood and Duct Considerations 4-203
4.8.2.9 Gas Burners 4-204
4.8.2.10 Construction Materials 4-211
4.8.2.11 Typical Applications 4-213
5. EMISSION FACTORS FOR PARTICULATE AIR POLLUTANTS 5-1
6. ECONOMIC CONSIDERATIONS IN AIR POLLUTION
CONTROL 6-1
6.1 SELECTION OF CONTROL SYSTEM 6-1
6.2 COST-EFFECTIVENESS RELATIONSHIPS 6-5
6.3 COST DATA 6-8
6.4 UNCERTAINTIES IN DEVELOPING COST
RELATIONSHIPS
xxi
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Page
6. 5 DESCRIPTION OF CONTROL COST ELEMENTS 6-10
6.5.1 General 6"~10
6.5.2 Capital Investment 6~14
6.5.3 Maintenance and Operation
6.5.3.1 General 6~15
6.5.3.2 Gravitational and Centrifugal Mechanical Collectors 6-22
6.5.3.3 Wet Collectors 6~23
6.5.3.4 Electrostatic Precipitators 6-25
6.5.3.5 Fabric Filter 6~26
6.5.3.6 Afterburners 6-27
6.5.4 Capital Charge 6-27
6. 5. 5 Annualization of Costs 6-28
6. 5. 6 Assumptions in Annualized Control Cost Elements 6-28
6. 5. 6.1 Annualized Capital Cost Assumptions 6-29
6. 5. 6.2 Operating Cost Assumptions 6-30
6. 5. 6. 3 Maintenance Cost Assumption 6-30
6. 6 METHOD FOR ESTIMATING ANNUAL COST OF
CONTROL FOR A SPECIFIC SOURCE 6-30
6.6.1 General 6-30
6.6.2 Procedure 6-30
6.6.3 Sample Calculations 6-33
6.6.4 Annualized Cost Variation 6-36
xxn
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Page
6.7 COST CURVES BY EQUIPMENT TYPE 6-36
6.7.1 General 6-36
6.7.2 Gravitational Collectors 6-38
6.7.3 Dry Centrifugal Collectors 6-39
6.7.4 Wet Collectors 6-39
6.7.5 High-Voltage Electrostatic Precipitators 6-44
6.7.6 Low-Voltage Electrostatic Precipitators 6-47
6.7.7 Fabric Filters 6_47
6.7.8 Afterburners 6-50
6.8 DISPOSAL OF COLLECTED PARTICULATE EMISSIONS 6-54
6.8.1 General 6-54
6.8.2 Elements of Disposal Systems 6-55
6.8.3 Disposal Cost for Discarded Material 6-59
6.8.4 Return of Collected Material to Process 6-61
6.8.5 Recovery of Material for Sale 6-63
7. CURRENT RESEARCH IN CONTROL OF PARTICULATE
MATTER 7-1
8. BIBLIOGRAPHY 8-1
AUTHOR INDEX A-l
SUBJECT INDEX A-27
XXlll
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LIST OF FIGURES
Figure
2-1 Sources of particulate matter and quantities
produced in tons per year.
3-6
3-1 Motor vehicle crankcase control system.
3-2 Costs of incinerator at three levels of control of
381
particulate emissions.
4-1 Composite grade (fractional) efficiency curves
based on test silica dust:,
4-2 Terminal velocities of spherical particles in air. 4-11
4-3 Balloon dust. 4~12
4-4 Baffled expansion chamber with dust hopper. 4-13
4-5 Dust settling chamber. 4-14
4-6 Multiple-tray dust collector. 4-14
4-7 Conventional reverse-flow cyclone. 4-18
4-8 Axial inlet cyclone. 4-18
4-9 Straight-through-flow cyclone. 4-20
4-10 Dynamic cyclone showing method by which dust is dynami-
cally precipitated and delivered to the storage hopper. 4-21
4-11 Various types of cyclone dust discharge. 4-25
4-12 Cyclones arranged in parallel. 4-28
4-13 Cyclones arranged in parallel. 4-29
4-14 Arrangement of nozzles in smoke stack spray system. 4-38
4-15 Typical layout for spray tower. 4-41
4-16 Centrifugal spray scrubbers. 4-42
4-17 Impingement plate scrubber. 4-45
xxiv
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Figure Page
4-18 Venturi scrubber may feed liquid through jets (a), over
a weir (b), or swirl them on a shelf (c). 4-47
4-19 Flooded disk (variable throat orifice) scrubber. 4-48
4-20 Multiple-venturi jet scrubber. 4-50
4-21 Vertical venturi scrubber, 4-51
4-22 Wet scrubber packings. 4-52
4-23 Packed-bed scrubbers. 4-53
4-24 Flooded-bed scrubber. 4-57
4-25 Floating-ball (fluid-bed) packed scrubber. 4-58
4-26 Self-induced-spray scrubbers. 4-60
4-27 Mechanically induced spray scrubbers. 4-62
4-28 Centrifugal fan wet scrubber. 4-64
4-29 Inline wet scrubber. 4-65
4-30 Wetted and impingement plate filters. 4-67
4-31 Low-velocity filtering elements. 4-70
4-32 High-velocity filtering elements. 4-71
4-33 Wire mesh mist eliminators. 4-72
4-34 Coke quench mist elimination baffle system. 4-74
4-35 Details of baffle design. 4-74
4-36 Streamline mist eliminator baffles. 4-75
4-37 Screen and mist eliminator details. 4-75
4-38 Bed of Berl saddles added to discharge stack. 4-77
4-39 Spray nozzles commonly used in wet scrubbers. 4-79
xxv
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Figure
4-40 Weir and sieve plate liquid distributors commonly
, . , , , 4-82
used m packed towers.
4-41 Multiple precipitator installation in basic oxygen
furnace plant.
4-42 Detarrer precipitators installed in steel mill. 4-89
4-43 Schematic view of a flat surface-type electrostatic
4_oo
precipitator.
4-44 Schematic view of tubular surface-type electrostatic
precipitator. 4-92
4-45 Cutaway view of a flat surface-type electrostatic
precipitator. 4-93
4-46 Cross-sectional view of irrigated tubular blast
furnace precipitator. 4-94
4-47 Typical double half wave silicon rectifier with
twin output bushings. 4-96
4-48 Internal view of one type of rectifier control
console showing component parts. 4-97
4-49 Electrostatic precipitator collecting plates and
discharge electrodes. 4-98
4-50 Hopper discharge valves, (a) Rotary valve and
(b) swing valve . 4-99
4-51 Electrostatic precipitator rapper mechanisms.
(a) Pneumatic impulse rapper, (b) Magnetic impulse
rapper, and (c) Pneumatic reciprocating rapper. 4-100
4-52 Variation of precipitator efficiency with sparking
rate for a given fly ash precipitator. 4-103
4-53 Electrostatic precipitator installed after air heater
in power plant steam generator system. 4-110
xxvi
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Figure Page
4-54 Operating principle of two-stage electrostatic
precipitator. 4-115
4-55 Two-stage precipitator used to control oil mist from
machining operations. 4-117
4-56 Two-stage electrostatic precipitator with auxiliary
scrubbers, mist eliminator, tempering coil, and
gas distribution plate (top view). 4-118
4-57 Efficiency of two-stage precipitator as function
of velocity for several industrial operations . 4-121
4-58 Typical simple fabric filter baghouse design. 4-128
4-59 Streamlines and particle trajectories approaching
filter elements . 4-131
4-60 System analysis for fabric filter collector design. 4-139
4-61 Pressure drop versus filter ratio for fabrics on
60-minute cleaning cycle for electric furnace dust. 4-149
4-62 Typical performance of reverse-jet baghouses using
felted fabrics on a variety of dusts (dust load versus
filtering ratio at 3.5 in.w.c. pressure drop). 4-150
4-63 Open pressure baghouse . 4-151
4-64 Open pressure baghouse unit showing installation
without a separate clean gas housing . 4-152
4-65 Closed pressure baghouse. 4-153
4-66 Closed pressure baghouse unit . 4-154
4-67 Closed suction baghouse. 4-155
4-68 Closed suction concrete baghouse unit. 4-155
4-69 Typical flat or envelope dust collector bag . 4-156
xxvn
-------
Figure P§ge_
4-70 Typical round or tubular dust collector bag. 4-157
4-71 Typical multi-bag dust collection system. 4-157
4-72 Bottom entry design uni-bag. 4-158
4-73 Top entry design uni-bag. 4-158
4-74 Basic fabric weaves used for woven filter bags . 4-162
4-75 Mechanical shaking of bottom entry design uni-bag
dust collector. 4-166
4-76 Air shaking wind-whip cleans dust collector bags. 4-166
4-77 Bubble cleaning of dust collector bags. 4-168
4-78 Jet pulse dust collector bag cleaning. 4-168
4-79 Reverse air flexing to clean dust collector bags by
repressuring . 4-168
4-80 Sonic cleaning of dust collector bags . 4-169
4-81 Repressuring cleaning of dust collector bags. 4-169
4-82 Cloth cleaning by reverse flow of ambient air. 4-170
4-83 Reverse jet cleaning of dust collector bags . 4-171
4-84 Effect of cleaning frequency on filter resistance in
reverse-jet baghouse. 4-182
4-85 Effect of air velocity and particle diameter on the
combustion rate of carbon. 4-190
4-86 Combustion efficiency of catalytic afterburner. 4-191
4-87 Effect of temperature and velocity on abatement
effectiveness: spiral-wound metal foils catalyst support. 4-192
xxviu
-------
Figure Page
4-88 Typical direct-fired afterburner with tangential entries
for both fuel and contaminated gases . 4-196
4-89 Portable canopy hood with stack afterburner. 4-197
4-90 Afterburner energy requirements with fume energy
content and temperature parameters . 4-198
4-91 Counter-flow type. 4-199
4-92 Parallel-flow type. 4-199
4-93 Cross-flow type. 4-199
4-94 Fixed-bed, pebble-stone, regenerative destencher. 4-199
4-95 Direct recirculation of combustion gases to recover heat. 4-201
4-96 Heat exchanger to recover heat from combustion gases. 4-201
4-97 Integration of fume disposal from a kettle cooking
operation with factory make-up air heating. 4-205
4-98 Packed bed flame arrester. 4-206
4-99 Corrugated metal flame arrester with cone removed
and tube bank pulled partly out of body . 4-206
4-100 Dip leg flame arrester . 4-206
4-101 Cross-sectional view of open-type inspirational
premix burner. 4-208
4-102 Cross-sectional view of forced air, premix, multiple-
port burner. 4-208
4-103 Multiple-port high-intensity premix burner. 4-210
4-104 Service temperature ranges for refractories. 4-214
xxix
-------
Figure
4-105 Degree of refraction for alumina-silica system
products.
62
Criteria for selection of gas cleaning equipment.
f* £J
Cost of control.
fiV
6-3 Expected new cost of control.
6-4 Diagram of cost evaluation for a gas cleaning system. 6-12
6-5 Purchase cost of gravitational collectors. 6-40
6-6 Installed cost of gravitational collectors. 6-40
6-7 Purchase cost of dry centrifugal collectors. 6-41
6-8 Installed cost of dry centrifugal collectors. 6-41
6-9 Annualized cost of operation of dry centrifugal
collectors. 6-42
6-10 Purchase cost of wet collectors. 6-42
6-11 Installed cost of wet collectors. 6-43
6-12 Annualized cost of operation of wet collectors. 6-43
6-13 Purchase cost of high-voltage electrostatic
precipitators. 6-45
6-14 Installed cost of high-voltage electrostatic
precipitators. 6-45
6-15 Annualized cost of operation of high-voltage
electrostatic precipitators. 6-46
6-16 Purchase cost of low-voltage electrostatic
precipitators. 6-46
xxx
-------
Figure Page
6-17 Installed cost of low-voltage electrostatic
precipitators. 6-48
6-18 Annualized cost of operation of low-voltage
electrostatic precipitators. 6-48
6-19 Purchase cost of fabric filters. 6-49
6-20 Installed cost of fabric filters. 6-49
6-21 Annualized cost of operation of fabric filters. 6-51
6-22 Purchase cost of afterburners. 6-51
6-23 Installed cost of afterburners. 6-52
6-24 Annualized cost of operation of afterburners. 6-52
6-25 Flow diagram for disposal of collected particulate
material from air pollution control equipment. 6-58
6-26 Economic cost of dust control with valuable material
recovered: industrial viewpoint. 6-62
xxxi
-------
Table
LIST OF TABLES
Page
1 Typical pressure drops and efficiency ranges for gas
cleaning devices used for stationary combustion
sources
2 Industrial process control summary
3 Advantages and disadvantages of collection devices 8
4 Examples of particulate emission factors 11
5 Installed costs of control equipment 13
6 Generalized annual operating and maintenance
cost equations for control equipment 14
3-1 Comparison of motor vehicle particulate emissions with
total particulate emissions for selected areas 3-4
3-2 Estimated 1966 United States energy consumption by
selected consumer (10 Btu) 3-11
3-3 Common uses of various fuel-burning equipment 3-12
3-4 Estimated amount and control status for particulate
emissions from stationary combustion sources in 1966 3-14
3-5 Optimum expected performance of various types of gas
cleaning systems for stationary combustion sources 3-17
3-6 Comparison of energy substitution alternatives for
electric power generation 3-22
3-7 Comparison of energy substitution alternatives for
stationary combustion sources of less than 10 million
Btu/hr input 3-23
Comparison of energy substitution alternatives for
stationary combustion sources of 10 million to 100
million Btu/hr input 3-24
xxxii
-------
Table Page
3-9 Trends in efficiency of coal, oil, and gas use in
United States 3-26
3-10 Industrial process summary 3-32
3-11 Steel production, percentage by process 3-36
3-12 Average solid waste collected 3-64
3-13 Maximum demonstrated collection efficiency of incinera-
tor control equipment 3-75
4-1 Manufacturers' shipments of industrial gas cleaning
equipment by end use in 1967 4-2
4-2 Use of particulate collectors by industry 4-7
4-3 Relationship between particle size range and cyclone
efficiency range 4-24
4-4 Representative performance of centrifugal collectors 4-30
4-5 Applications of centrifugal collectors 4-31
4-6 Typical industrial application of wet scrubbers 4-84
4-7 Industrial operation of two-stage precipitators 4-122
4-8 Control mechanism for particle size collection 4-133
4-9 Filter resistance coefficients (K) for industrial dusts
on woven fabric filters 4-136
4-10 Physical characteristics of bag fabrics tested in
pilot plant 4-141
4-11 Recommended maximum filtering ratios and dust
conveying velocities for various dusts and fumes in
conventional baghouses with woven fabrics 4-142
xxxi 11
331-716 O - 69 - 3
-------
Table
4-12 Recommended maximum filtering ratios and fabric for
4-172
dust and fume collection in reverse-jet baghouses l 6
4-13 Filter fabric characteristics
4-209
4-14 Gas burner classifications
4-15 ASTM classification of fire clay refractories 4-212
4-16 Commonly used castable fire clay refractories 4-212
4-17 General physical and chemical characteristics of
classes of refractory brick 4-216
4-18 Summary of afterburner applications and literature
references 4-217
5-1 Particulate emission factors 5-3
6-1 Air pollution control equipment collection efficiencies 6-4
6-2 Approximate cost of wet collectors in 1965 6-11
6-3 Total installation cost for various types of control
devices expressed as a percentage of purchase costs 6-16
6-4 Conditions affecting installed cost of control devices 6-17
6-5 Annual maintenance costs for all generic types of
control devices 6-18
6-6 Miscellaneous cost and engineering factors 6-19
6-7 Hourly fuel costs 6-28
6-8 Illustrative presentation of annual costs of control for
60,000 acfm wet scrubber (dollars) 6-37
6-9 Costs of specific disposal systems 6-60
6-10 Cost of ash disposal by electric utilities 6_gl
xxxiv
-------
SUMMARY
PARTICULATE SOURCES
Particulate material found in ambient air originates from both stationary
and mobile sources. Of the 11. 5 million tons of particulate pollution produced
in 1966, 6 million tons were emitted from industrial sources, including in-
dustrial fuel burning; 5 million tons from power generation, incineration, and
space heating; and 0. 5 million ton from mobile sources.
The following techniques are in use for controlling the source or reducing
the effects of particulate pollution:
1. Gas cleaning
2. Source relocation
3. Fuel substitution
4. Process changes
5. Good operating practice
6. Source shutdown
7. Dispersion
Internal Combustion Engines
Although particulate emissions from internal combustion engines are
estimated to contribute only 4 percent of the total particulate emissions on a
nationwide basis, they do contribute as much as 38 percent in certain urban
areas. The relative percentages of particulate emissions for this and other
source categories differ from one area to another depending on automobile
density, degree of stationary source control, and types of sources present in
the area.
1
-------
For each 1000 gallons of fuel consumed, diesel-fueled engines produce
about 110 pounds of particulate matter. Gasoline-fueled engines produce about
12 pounds per 1000 gallons of fuel consumed.
Gasoline engine-produced particulate matter emanates from the crank-
case and exhaust gases. It consists of carbon, metallic ash, aerosol hydro-
carbons, and metallic particles.
The particulate matter emitted from a diesel engine comprises
carbon and hydrocarbon aerosols. Control of diesel engine emissions effects
reduction in smoke.
Stationary Combustion Sources
In the United States more than 29 million stationary combustion sources
are currently in operation. About 2 percent are fired with coal, 61 percent
are fired with gas, and 37 percent are fired with fuel oil. The relative usage
of fuels on a Btu basis shows coal to be 31 percent, natural gas 48 percent, and
fuel oil 21 percent.
Types of gas cleaning devices currently being used for stationary com-
bustion sources are listed in Table 1. Newer control systems are now being
installed which will be used to control both particulate matter and sulfur oxides.
Industrial Sources
Industrial processes, including industrial fuel burning, discharged an
estimated 6. 0 million tons of particulate materials in 1966. This amounts to
more than 50 percent of the total particulate pollution on a nationwide basis.
Major pollutants are dusts, fumes, oils, smoke, and mists.
-------
Table 1. TYPICAL PRESSURE DROPS AND EFFICIENCY RANGES FOR GAS CLEANING
DEVICES USED FOR STATIONARY COMBUSTION SOURCES
Unit
Pressure drop, in. HO
£t
Efficiency, percent
Settling chambers
Large-diameter cyclones
Small-diameter cyclones
Electrostatic precipitator
0.5
0.5-4.0
2-8
0.1-0.5
20 - 60
30 - 65
70 - 90
75 - 99.5
CO
-------
Table 2 presents a summary of important industries, their pollutant
sources, particulate pollutants, and air cleaning techniques (equipment)
presently in use.
Construction and Demolition
The principal demolition, construction, and related operations that gen-
erate particulate air pollution are:
1. Demolition of masonry
2. Open burning
3. Movement of vehicles on unpaved roads
4. Grading of earth
5. Paving of roads and parking lots
6. Handling and batching of paving materials
7. Sandblasting of buildings
8. Spray painting
Control of the above operations is accomplished by various means which
include hooding and venting to air pollution control equipment, wetting down
working surfaces with water or oil, and using sanitary landfill.
Solid Waste Disposal
Although solid waste disposal by incineration accounts for less than 10
percent of the total particulate pollution (1 million tons in 1966), it does, how-
ever, inspire many complaints about air pollution. Of the 190 million tons of
solid wastes collected in 1967, 86 percent went into land disposal sites, 8 per-
cent was burned in municipal incinerators, and 6 percent was disposed of in
sanitary landfills. Since open burning is practiced at three-fourths of the land
-------
Table 2. INDUSTRIAL PROCESS AND CONTROL SUMMARY
Industry or process
01
Iron and steel mills
Gray iron foundries
Metallurgical
(non-ferrous)
Petroleum refineries
Portland cement
Kraft paper mills
Acid manufacture-
phosphoric, sulfuric
Coke manufacturing
Glass and glass fiber
Coffee processing
Source of emissions
Blast furnaces, steel making
furnaces, sintering machines
Cupolas, shake out systems,
core making
Smelters and furnaces
Catalyst regenerators, sludge
incinerators
Kilns, dryers, material
handling systems
Chemical recovery furnaces,
smelt tanks, lime kilns
Thermal processes, phosphate
rock acidulating, grinding
and handling systems
Charging and discharging
oven cells, quenching,
materials handling
Raw materials handling, glass
furnaces, fiberglass forming
and curing
Roasters, spray dryers, waste
heat boilers, coolers,
conveying equipment
Particulate matter
Iron oxide, dust,
smoke
Iron oxide, dust,
smoke, oil, grease,
metal fumes
Smoke, metal fumes,
oil, grease
Catalyst dust, ash
from sludge
Alkali and process
dusts
Chemical dusts
Acid mist, dust
Coal and coke dusts,
coal tars
Sulfuric acid mist,
raw materials dusts,
alkaline oxides,
resin aerosols
Chaff, oil aerosols,
ash from chaff burning,
dehydrated coffee dusts
Method of control
Cyclones, baghouses, electro-
static precipitators, wet
collectors
Scrubbers, dry centrifugal
collectors
Electrostatic precipitators,
fabric filters
High-efficiency cyclones, electro-
static precipitators, scrubbing
towers, baghouses
Fabric filters, electrostatic
precipitator, mechanical collectors
Electrostatic precipitators, ven-
turi scrubbers
Electrostatic precipitators, mesh
mist eliminators
Meticulous design, operation,
and maintenance
Glass fabric filters, afterburners
Cyclones, afterburners, fabric filters
-------
disposal sites, particulate emissions from these sites contribute significantly
to air pollution arising from the disposal of solid waste.
Over 70 percent of existing municipal incinerators were installed before
1960, and lack adequate provisions for eliminating particulate emissions.
An obvious means of reducing the air pollution resulting from solid waste
disposal is to use such non-incineration methods for disposal as follows:
1. Sanitary landfill
2. Composting
3. Shredding and grinding
4. Dispersion (hauling to another locale)
These methods contribute little to air pollution problems.
It is estimated that measures to upgrade existing land disposal sites, and thus
do away with openburning, will cost as much as $230 million peryearfor 5 years.
Where incineration is used for solid waste disposal, the principal partic-
ulate pollutant emitted is fly ash. Its removal from effluent gas streams is
accomplished by low pressure drop (0. 5 inch H2O) scrubbers, or settling
chambers.
The estimated cost of upgrading or replacing existing inadequate in-
cinerators is $225 million, of which $75 million would be for air pollution
control equipment.
GAS CLEANING DEVICES
It has been estimated that total expenditures in 1966 on industrial air
pollution control equipment in the United States were about $235 million.
-------
Value of shipments of the industrial gas cleaning equipment industry in 1967
was double the 1963 figure, and the backlog of orders recently nearly equalled
a year's productive output. Undoubtedly legislative pressure and local pollu-
tion control regulations have supplied the impetus for such rapid growth in this
industry.
The selection of gas cleaning equipment is far from an exact science and
must be based on characteristics of particle and carrier gas, and process,
operation, construction, and economic factors. Information on particle size
gradation in the inlet gas stream is important in the proper selection of gas
cleaning equipment. Particles larger than 50 microns may be removed satis-
factorily in inertial and cyclone separators and simple, low-energy wet
scrubbers. Particles smaller than 1 micron can be arrested effectively by
electrostatic precipitators, high-energy scrubbers, and fabric filters.
Table 3 lists advantages and disadvantages in applicability of each of
the general types of air cleaners to given situations.
EMISSION FACTORS
Emission factors may be used to estimate emissions from sources for
which accurate stack test results are unavailable. Process emission factors
for some selected source types are presented in Table 4.
ECONOMICS
Air pollution control is viewed not only from the standpoint of available
technology but also with respect to the economic feasibility of control methods
and/or equipment.
-------
Table 3. ADVANTAGES AND DISADVANTAGES OF COLLECTION DEVICES
Collector
Advantages
Disadvantages
Gravitational
Cyclone
Wet collectors
Low Pressure loss, simplicity
of design and maintainance
Simplicity of design and
maintainance
Little floor space required
Dry continuous disposal
of collected dusts
Low to moderate pressure
loss
Handles large particles
Handles high dust
loadings
Temperature independent
Simultaneous gas
absorption and particle
removal
Ability to cool and clean
high-temperature, moisture-
laden gases
Corrosive gases and mists
can be recovered and
neutralized
Reduced dust explosion
risk
Efficiency can be varied
Much space required
Low collection efficiency
Much head room required
Low collection efficiency
of small particles
Sensitive to variable dust
loadings and flow rates
Corrosion, erosion problems
Added cost of wastewater
treatment and reclamation
Low efficiency on submicron
particles
Contamination of effluent
stream by liquid
entrainment
Freezing problems in cold
weather
Reduction in buoyancy and
plume rise
Water vapor contributes to
visible plume under some
atmospheric conditions.
-------
Table 3 (continued). ADVANTAGES AND DISADVANTAGES
OF COLLECTION DEVICES
Collector
Advantages
Disadvantages
Electrostatic
precipitator
Fabric
filtration
Afterburner,
direct flame
99+ percent efficiency
obtainable
Very small particles
can be collected
Particles may be collected
wet or dry
Pressure drops and power
requirements are small
compared to other high-
efficiency collectors
Maintenance is
nominal unless corrosive
or adhesive materials
are handled
Few moving parts
Can be operated at high
temperatures (550° to 850° F)
Dry collection possible
Decrease of performance
is noticeable
Collection of small
particles possible
High efficiencies
possible
High removal efficiency
of submicron odor-causing
particulate matter
Relatively high initial
cost
Precipitators are sensi-
tive to variable dust
loadings or flow rates
Resistivity causes some
material to be economi-
cally uncollectable
Precautions are required
to safeguard personnel
from high voltage
Collection efficiencies
can deteriorate gradually
and imperceptibly
Sensitivity to filtering
velocity
High-temperature gases must
be cooled to 200° to 550° F
Affected by relative
humidity (condensation)
Susceptibility of fabric
to chemical attack
High operational cost
Fire hazard
-------
Table 3 (continued). ADVANTAGES AND DISADVANTAGES
OF COLLECTION DEVICES
Collector
Advantages
Disadvantages
Afterburner,
direct flame
(continued)
Afterburner,
catalytic
Simultaneous disposal of
combustible gaseous and
particulate matter
Direct disposal of non-
toxic gases and wastes
to the atmosphere after
combustion
Possible heat recovery
Relatively small
space requirement
Simple construction
Low maintenance
Same as direct flame
afterburner
Compared to direct flame:
reduced fuel require-
ments, reduced temperature,
insulation requirements,
and fire hazard
Removes only combustibles
High initial cost
Catalysts subject to
poisoning
Catalysts require
reactivation
10
-------
Table 4. EXAMPLES OF PARTICULATE EMISSION FACTORS
Source
Specific process
Particulate
emission rate,
uncontrolled
Aircraft
Solid waste
disposal
Phosphoric acid
manufacturing
Sulfuric acid
manufacturing
Food and
agricultural
Feed and
grain mills
Primary metal
industry
Secondary metal
industry
Four engine fan jet
Open burning
dump
Thermal process
Contact process
Coffee roasting,
direct fired
Cotton ginning and incin-
eration of trash
General operation
Iron and steel manufacturing
furnace, open hearth (oxygen
lance)
Aluminum smelting,
chlorination-lancing
Brass and bronze
smelting rever-
beratory furnace
Gray iron foundry
cupola
7.4 lb/flight
16 Ib/ton of refuse
0.2-10.8 Ib/ton of phos-
phorus burned
0.3-7.5 Ib/ton of acid
produced
7. 6 Ib/ton of green
beans
11.7 Ib/bale of cotton
6 Ib/ton of product
22 Ib/ton of steel
1000 Ib/ton of chlorine
26.3 Ib/ton of metal
charged
17.4 Ib/ton of metal
charged
11
-------
Among the cost elements relevant to an air pollution control problem
are:
1. Capital costs of control equipment.
2. Depreciation of all control equipment.
3. Overhead costs including taxes, insurance, and interest
for control equipment.
4. Operation and maintenance costs.
5. Collected waste material disposal costs.
6. Other capital expenditures for research and development,
land, and engineering studies to determine and design optimum
control system.
Many of these elements differ from one installation to another. Table
5 lists major collector types and their approximate installed costs for opera-
tional air flow rates. The installed costs (purchase cost, transportation, and
preparation for on line operation) are average costs for typical control equip-
ment.
Table 6 presents generalized operating and maintenance cost equations
for various types of control equipment.
BIBLIOGRAPHY
A list of references follows each section of this document. Other ref-
erences relating to control technology for generic sources of particulate air
pollutants are cited in the bibliography, which comprises the final section.
12
-------
Table 5. INSTALLED COSTS OF CONTROL EQUIPMENT
Collector
type
Gravity
Mechanical
Wet
High-voltage
electrostatic
precipitator
Low-voltage
electrostatic
precipitator
Fabric filter,
high temperature (550° F)
medium temperature (250° F)
Afterburner,
direct flame
catalytic
Approximate installed cost, in thousands
of dollars
Gas flow rates
(1000 actual cubic feet per minute)
2
0.5
-
-
-
-
-
8.2
16
5
.1.2
-
7.5
-
13
:
12
20
10
2.6
4
10
-
24
30
15
18
29
15
15
13
30
85
105
88
45
-
100
28
23
55
120
200
155
82
-
300
-
80
150
265
-
430
225
-
500
-
-
-
415
-
720
375
-
13
-------
Table 6. GENERALIZED ANNUAL OPERATING AND MAINTENANCE COST
EQUATIONS FOR CONTROL EQUIPMENT
Collector
Mechanical centrifugal
collector
Wet collector
Electrostatic
precipitator
Fabric
filter
Afterburner
Generalized
G=S TO. 7457 PHK +
L 6356 E
G=S 1 0.7457 HK (z -.
G=S [(JHK + M)]
G=S |"0. 7 457 PHK +
L 6356 E
G=S To. 7457 PHK +
L 6356 E
equation
M]
- Qh \ + WHL
19807
MJ
FH + MJ
+ M]
Where:
G = annual costs, dollars, for operating and maintenance
S = design capacity of the unit, actual cubic feet per minute (acfm)
P = pressure drop, inches of water
H = hours of operation annually
K = cost of electricity; dollars per kilowatt-hour
E = fan efficiency expressed as decimal
M = maintenance cost per acfm, dollars per cfm
F = fuel costs, dollars per acfm per hour
W = make-up liquid rate in gallons per hour per acfm
L = cost of liquid in dollars per gallon
Z = total power input required for a specified scrubbing efficiency,
horsepower per acfm
J = kilowatts of electricity per acfm
h = elevation for pumping of liquor in circulation system for
collector, feet
Q = water circulation, gallons per acfm
14
-------
Although all of the articles cited in the bibliography do not necessarily reflect
the most modern control practices, they do provide useful background material
on the control technology for particulate air pollutants.
15
331-716 O - 69 - 4
-------
I. INTRODUCTION
Pursuant to authority delegated to the Commissioner of the National Air
Pollution Control Administration, Control Techniques for Particulate Air
Pollutants is issued in accordance with Section 107c of the Clean Air Act
(42 U. S.C. 1857c-2bl).
Particulate matter in the atmosphere is known to have many adverse
effects upon health and welfare, and reduction of emissions of this pollutant
is of prime importance to any effective air pollution abatement program.
Particulate pollutants originate from a variety of sources, and the emissions
vary widely in physical and chemical characteristics. Similarly, the available
control techniques vary in type, application, effectiveness, and cost.
The control techniques described herein represent a broad spectrum of
information from many engineering and other technical fields. The devices,
methods, and principles have been developed and used over many years, and
much experience has been gained in their application. They are recommended
as the techniques generally applicable to the broad range of particulate emission
control problems.
The proper choice of a method, or combination of methods, to be applied
to any specific source depends on many factors other than the characteristics
of the source itself. While a certain percentage of control, for example, may
be acceptable for a single source, a much higher degree may be required for the
same source when its emissions blend with those of others. This document
provides a comprehensive review of the approaches commonly recommended
for controlling the sources of particulate air pollution. It does not review all
1-1
-------
possible combinations of control techniques that might bring about more stringent
control of each individual source.
The many agricultural, commercial, domestic, industrial, and municipal
processes and activities that generate particulate air pollutants are described
individually in this document. The various techniques that can be applied to
control emissions of particulate matter from these sources are reviewed and
compared. A technical consideration of the most important types of gas clean-
ing devices forms a major segment, while sections on source evaluation,
equipment costs and cost-effectiveness analysis, and current research and
development also are included. The bibliography contains important reference
articles, arranged according to applicable processes.
While some data are presented on quantities of particulate matter emitted
to the atmosphere, the effects of particulate matter on health and welfare are
considered in a companion document, Air Quality Criteria for Particulate
Matter.
The National Air Pollution Control Administration also is publishing a
document which discusses the philosophy underlying the issuance of air quality
criteria, and which suggests some general guidelines for utilizing the criteria
to develop air quality standards. This latter publication also describes the
factors that the Department of Health, Education, and Welfare will consider
in evaluating the air quality standards and the implementation plans proposed
by the States.
1-2
-------
2. BACKGROUND INFORMATION
2. 1 DEFINITIONS
This section contains general definitions of the terms used throughout
this document.
Pollutant or Contaminantany solid, liquid, or gaseous matter in the
outdoor atmosphere which is not normally persent in natural air.
Particulate Matteras related to control technology, any material, ex-
cept uncombined water, that exists as a solid or liquid in the atmosphere or in
a gas stream at standard conditions.
It is important that standard conditions for the measurement of particu-
late matter be included with its definition. Some compounds are not solids or
liquids at stack conditions but condense in the ambient atmosphere. Unless
standard conditions for measurement of particulate matter are defined, these
materials would not be considered particulate and subject to control.
Aerosola dispersion in gaseous media of solid or liquid particles of
microscopic size, such as smoke, fog, or mist.
Dustsolid particles predominantly larger than colloidal size and capa-
ble of temporary suspension in air and other gases. Derivation from larger
masses through the application of physical force is usually implied.
2-1
-------
Fly Ash finely divided particles of ash entrained in flue gases arising
from the combustion of fuel. The particles of ash may contain unburned fuel
and minerals.
Fog visible aerosols in which the dispersed phase is liquid. In meteor-
ology, fog is a dispersion of water or ice.
Fumeparticles formed by condensation, sublimation, or chemical re-
action, of which the predominant part, by weight, consists of particles smaller
than 1 micron. Tobacco smoke and condensed metal oxides are examples of
fume.
Mistlow-concentration dispersion of relatively small liquid droplets.
In meteorology, the term mist applies to a light dispersion of water droplets
of sufficient size to fall from the air.
Particle small, discrete mass of solid or liquid matter.
Smoke small gasborne particles resulting from incomplete combustion.
Such particles consist predominantly of carbon and other combustible material,
and are present in sufficient quantity to be observable independently of other
solids.
Soot an agglomeration of carbon particles impregnated with "tar, "
formed in the incomplete combustion of carbonaceous material.
Sprays liquid droplets formed by mechanical action.
2-2
-------
2.2 MAJOR SOURCES OF PARTICULATE MATTER
An estimated 11. 5 million tons of particulate matter, about 10 percent of
all pollutants emitted annually, was emitted in the United States during 1966.
Figure 2-1, which is based on Reference 1 and gasoline and fuel consumption
figures, shows that industrial sources of particulate matter, including indus-
trial fuel burning, emit 6 million tons of particulate matter annually. About
5 million tons result annually from power generation, incineration,* and
space heating. Mobile (transportation) sources emit the remaining 0. 5 million
tons.
POWER
GENERATION
3 MILLION
INCINERATION
1 MILLION
2.2.1 Combustion Sources
Combustion of coal and oil re-
sults in an annual emission of 4. 5
HEATING
i MILLION miiiion tons of particulate matter that
MOBILE
0.5 MILLION iy asn from coai Com-
Figure 2-1. Sources of particulate matter
and quantities produced in
tons per year.
bustion. Emission sources are dis-
cussed in Section 3.3 of this report.
Refuse burning, both in inciner-
ators and in dumps, produces approxi-
mately 1 million tons of particulate matter annually. Much of this particulate
matter is dust, fume, smoke, fly ash, and large pieces of partially burned
refuse. Although refuse burning creates less than 15 percent of the total par-
ticulate matter emitted in the United States, such emissions are usually
*Does not include agricultural burning and forest fires.
2-3
-------
concentrated in heavily populated areas and have a more significant impact on
the population than these statistics may suggest.
2.2.2 Industrial Sources
Particulate emissions from industrial processes consist of dust, fume,
smoke, and mist arising largely from combustion and loss of process materi-
als or products to the atmosphere. Such emissions totaled 6 million tons in
1966. Major industrial sources are listed and discussed in Section 3.4 of
this report.
In some industrial processes, efficient collection of particulate matter
increases overall plant operating efficiency by recovering a portion of the
product that would otherwise be lost to the atmosphere. Dust collectors used
in cement plants, grain handling operations, and carbon black plants can re-
cover valuable products.
2.2.3 Mobile Sources
Emissions from mobile sources, which total approximately 0. 5 million
tons of particulate matter per year, are largely caused by the burning of
fuels in motor vehicles. Automobile exhaust is the largest source of particu-
late matter in this category. It is characterized by an extremely large num-
ber of fine particles consisting of organic and inorganic materials, including
lead. Particulate emissions from diesel engines are more concentrated
and may cause a visible plume. Aircraft, especially jet-powered planes, also
produce visible particulate emissions. The emission rate is greatest during
2-4
-------
takeoff and landing operations when the engines operate under conditions of a
high ratio of fuel to air.
2-5
-------
REFERENCE FOR SECTION 2
1. "The Sources of Air Pollution and Their Control. " U.S. Dept. of
Health, Education, and Welfare, Div. of Air Pollution, Washington,
D.C. , PHS-Pub-1548, 1966.
2-6
-------
3. PARTICULATE SOURCES AND CONTROLS
3.1 INTRODUCTION
The earliest approaches to air pollution control, used in England
over 200 years ago, were the restriction of smoke releases and re-
location of sources to "offensive trades zones. " The latter was used
particularly when the odor of the source was offensive. Relocation
is still used, or at least considered, by operators of some pollution
sources as an alternate to emissions control. In most instances, however,
relocating a pollution source to a remote area may only postpone the
adoption of emissions control.
Many sources such as transportation, space heating, and solid
wastes disposal are inherent to population centers. All generate partic-
ulate air pollution in urban areas. Although remote power generation and
long distance hauling of solid wastes are possible, automobiles, busses,
incinerators, and home furnaces and manufacturing and commercial
operations that require workers will, in all likelihood, continue to operate
in our cities.
To appreciate the air pollution problem facing the United States,
it is necessary to have some understanding of the sources of air pollution
3-1
-------
and the means of controlling them. The multitude of small sources closest
to the average citizen - automobiles, home furnaces, on-site incinerators -
are often the least effectively controlled. High-efficiency control equip-
ment use is limited almost entirely to certain steam-electric generating
stations and industrial operations, particularly the large installations. Most
of the high-efficiency emissions controls are being developed for such
sources as steel mills, steam-electric generating stations, petroleum
refineries, and chemical plants. The most promising areas of improve-
ment for small sources involve basic changes in source operation - cleaner
fuels, automobile engine modifications, and improved means of solid
wastes disposal.
3-2
-------
3.2 INTERNAL COMBUSTION ENGINES
Although stationary sources are the major contributors of particulate
matter, the motor vehicle contributes a significant amount of particulate
matter to the atmosphere. The ranking of the motor vehicle emissions in
an urban community is a function of the relative magnitude of the vehicular
and industrial activities; the extent to which coal, residual fuels, and refuse
are burned; and the extent and effectiveness of the air pollution control
measures used. Each 1, 000 gallons of fuel consumed by diesel engines
produces about 110 pounds of particulate matter and gasoline engines produce
about 12 pounds of particulate for every 1, 000 gallons consumed. Of the total
annual emission of 11. 5 million tons of particulate matter, motor vehicles
contribute approximately 4 percent or about 500, 000 tons.
Table 3-1 presents examples of contribution by motor vehicles to
particulate emissions in different communities.
3.2.1 Gasoline-Fueled Vehicles
Particulate matter is emitted in the exhaust and crankcase blowby
gases of gasoline-fueled engines. Carbon, metallic ash, hydrocarbons in
aerosol form, and metallic materials present in engine systems are emitted.
Metal-based particles result almost entirely from the use of lead
antiknock compounds in the fuel; however, metallic lubricating oil additives
and engine wear particles are also present. Carbon and some of the hydro-
carbon aerosols result from incomplete combustion of fuel. The rest of
3-3
-------
Table 3-1. COMPARISON OF MOTOR VEHICLE PARTICULATE EMISSIONS
WITH TOTAL PARTICULATE EMISSIONS FOR
SELECTED AREAS2"7
Metropolitan
area
Washington, D. C.
New York- Northern
New Jersey
Kansas City
Jacksonville, Florida
St. Louis
Los Angeles County
Particulate matter, tons/yr
Total
35,000
231,000
60,000
14,000
147,000
43,000
Motor
vehicle
5,700
33,800
5,000
600
4,700
16,400
Percent of
total from
motor vehicles
16
15
8
4
3
38
3-4
-------
the aerosols are emitted to the atmosphere from engines with vented crank-
cases or are produced by crankcase oil that leaks past the piston rings
into the combustion chamber and is emitted unburned with the exhaust gases.
Particulate matter in automobile exhaust amounts to approximately
5 percent by weight of the amount of gaseous hydrocarbon emitted. It
consists of lead compounds, carbon particles, motor oil, and nonvolatile
reaction products formed from motor oil in the combustion zone. It is
suspected that these reactions involve the formation of high-molecular-
weight olefins, and carbonyl compounds.
Particles in blowby gases consist almost entirely of unchanged
lubricating oil. As a very rough approximation, the amount of material
emitted in blowby gases is one-third to one-half the amount emitted in
the exhaust. The same approximate ratio applies to either particulate
emission or gaseous hydrocarbon emission. Blowby emissions are
influenced to a greater extent than exhaust emissions by mechanical con-
g
dition of the engine.
Partial control of vehicle particulate emissions has been in effect
nationally since 1963. Beginning with the 1968 automobile models, the particu-
lates in crankcase gases were completely controlled (Fig. 3-1). It is possible
the exhaust emission control measures employed in the 1968 model passenger
cars reduce the emissions of some particulates.
3-5
-------
FILTERED AIR
AIR INTAKE
CONTROL VALVE
CRANKCASE
BLOWBY GASES
C> FILTERED AIR
t BLOWBY GASES
FILTERED AIR + BLOWBY GASES
Hll> COMBUSTIBLE MIXTURE
Figure 3-1. Motor vehicle emission control system.
-------
Technology for the control of lead in exhaust emissions is in the devel-
opmental stage. The National Air Pollution Control Administration is present-
ly evaluating two prototype electrogasdynamic precipitators for gasoline and
9
diesel motor vehicle exhausts.
Lead emissions may also be controlled by restricting the concentration
of lead antiknock compounds that are permitted in the fuel. The American
Petroleum Institute indicates that the additional cost of unleaded fuel would
be 1. 8 to 4. 7 cents per gallon. Petroleum processing equipment is available
for producing unleaded gasoline, but an estimated 5 to 10 years is necessary
for its installation at a capital investment of over $4 billion. '
3.2.2 Dies el-Powered Vehicles
Particulate matter emitted by diesel engines consists primarily of
carbon and hydrocarbon aerosols resulting from incomplete combustion of the
fuel. Aerosols in the vent gases of the two-stroke-cycle diesel engine (from
air box drains) and in the exhaust, as a result of crankcase oil going through
the combustion process unburned, produce a small amount of additional
particulate emissions.
Federal regulations scheduled for implementation in 1970 will limit
smoke from new diesel engines. The regulations establish a maximum in-
tensity of smoke emission (measured by reduction in light transmission) under
conditions of severe engine loading at (1) full-throttle acceleration from a
prolonged idle and (2) "lugdown" from maximum governed speed, also at full
3-7
331-716 O - 69 - 5
-------
throttle. No new information or control devices are believed to be needed to
reduce the smoke emissions from diesel engines to meet the established stand-
ards. As vehicle mileage increases, proper fuel system adjustment, mainte-
nance at appropriate intervals, the use of the specified type of fuel, and good
operating techniques can maintain low levels of visible emissions, particularly
with respect to particulate carbon.
New engines, which will comply with the 1970 smoke standards, will be
adjusted by the engine manufacturer to a conservative fuel rate and power output.
Increases in fuel rate above the manufacturer's setting will increase engine
power, but also will raise the level of black smoke. Even in a properly ad-
justed engine, injector deterioration (such as nozzle erosion) can effect a sub-
stantial increase in the emission of black smoke.
Investigations have been conducted to evaluate methods of reducing
diesel smoke. Methods consist primarily of exhaust gas dilution and the use
of smoke-suppressing fuel additives. Neither of these methods can be recom-
mended for general application at this time. The dilution technique at best,
merely reduces the opacity of the smoke plume without reducing the quantity of
particles emitted. Smoke suppressants have been reported to be effective in
overfueled engines in good mechanical condition. One type of suppressant re-
12
ported to show promise contains barium. Use of the organic barium additive
could, however, result in the emission of toxic, water-soluble, barium
3-8
-------
compounds. Further study of additives is needed before this technology can
be broadly adopted.
3-9
-------
3. 3 CONTROL OF PARTICULATE EMISSIONS FROM STATIONARY
COMBUSTION SOURCES
3.3.1 Introduction
3.3.1.1 General - Of the many techniques used to control participate air
pollution from stationary combustion sources, none has emerged as an all-
inclusive answer to the control problem.
3.3.1.2 Sources - More than 29 million stationary combustion sources are
13
currently in operation in the United States. About 2 percent are fired
with coal, 61 percent are fired with gas, and 37 percent are fired with
liquid fuels. Table 3-2 shows the consumption of energy by type of consumer.
Coal, gas, and oil are burned in a wide variety of equipment. The more
common types of equipment are shown in Table 3-3.
3.3.L3 Emissions - Participate emissions from stationary combustion
sources in the United States are estimated at 4.5 million tons (see Table
3-4) of the total particulate emissions of almost 12 million tons per year
1 £!
from all sources. Local patterns of emissions will usually differ from
the national pattern because of differences in fuel and equipment use patterns.
The rate of uncontrolled particulate emissions varies widely from
unit to unit because processes, practices, and fuels all affect emission
levels. For each fuel, several different processes are used for stationary
combustion. Steam, hot water, and warm air furnaces are in common use
for domestic heating and many specialized heaters are used by industry.
3-10
-------
Table 3-2. ESTIMATED 1966 UNITED STATES ENERGY CONSUMPTION
19 14
BY SELECTED CONSUMER (10 Btu)
Energy
source
Anthracite coal
Bituminous and
lignite coal
Natural gas
Petroleum
Hydroelectric
Nuclear
Total
Consumer
Household
and
commercial
143
575
5,945
2,247a
0
0
8,910
Industrial
41a
2,206a
5,674a
2,512a
0
0
10,433
Power
generation
56
6,341
2, 692
905
2,060
58
12,112
Total
240
9,122
14,311
5,664
2,060
58
31,455
aExchides non-combustion consumption.
"Excludes naphtha, kerosene, and liquified petroleum gases.
3-11
-------
Table 3-3. COMMON USES OF VARIOUS FUEL-BURNING EQUIPMENT
Equipment
Common use
Coal-fired
Hand-stoked equipment
Single-retort underfeed
stokers
Multiple-retort underfeed
stokers
Spreader stokers
Traveling grate stokers
Chain grate stokers
Vibrating grate stokers
Pulverized-fuel-fired
equipment (dry bottom
or wet bottom)
Oil-fired
High-pressure gun-type
burners
Low-pressure air-atomizing
burners
Rotary cup burners
Steam atomizing burners
High-pressure air-
atomizing burners
Residential, institutional, and commercial
warm-air and boiler applications at
capacities up to 5 million Btu per hour input.
(Used primarily in coal-producing areas.)
Residential, institutional, and commercial
warm-air and boiler applications at
capacities up to 40 million Btu per hour
input.
Water tube and fire tube boiler applications
for institutional, commercial, and industrial
heating at capacities in range of 5 million
to 200 million Btu per hour input.
Water tube boiler applications for power
generation at capacities greater than 100
million Btu per hour input.
Residential warm air furnace or boiler
applications at capacities up to 3 gallons
per hour distillate oil.
Water tube and fire tube boiler applications
for institutional, commercial, and industrial
process heating with distillate or residual
oil.
Water tube and fire tube boiler applications
for institutional, commercial, and industrial
heating and power generation with residual
oil.
3-12
-------
Table 3-3 (continued). COMMON USES OF VARIOUS
FUEL-BURNING EQUIPMENT
Equipment
Common use
Gas-fired
Premixing burners
Nozzle mixing burners
Residential warm-air furnace or boiler
applications and low-temperature industrial
applications.
Water tube and fire tube boiler applications
for institutional, commercial, industrial,
and power-generation applications. (May
be combination type to permit fuel oil
firing when gas supply is interrupted.)
3-13
-------
Table 3-4. ESTIMATED AMOUNT AND CONTROL STATUS FOR PARTICULATE
EMISSIONS FROM STATIONARY COMBUSTION SOURCES IN 1966
Fuel and source
Anthracite coal
Household and
commercial
Industrial
Power
Sub total
Bituminous and
lignite coal
Household and
commercial
Industrial
Power
Sub total
Petroleum0
Household and
commercial
Industrial
Power
Sub total
Natural gas
Household and
commercial
Industrial
Power
Sub total
Grand total
Uncontrolled
emissions
10 tonsa
0.05
0.04
0.17
0.26
0.24
2.29
21.14
23.67
0.08
0.17
0.03
0.28
0.06
0.05
0.02
0.13
24.34
Estimated
control status
in 1966, b
percent
Negligible
62.0
86.5
-
Negligible
62.0
86.5
-
Negligible
Negligible
Negligible
-
Negligible
Negligible
Negligible
-
Estimated emissions
in 1966
106 tons
0.05
0.02
0.02
0.09
0.24
0.87
2.85
3.96
0.08
0.17
0.03
0.28
0.06
0.05
0.02
0.13
4.46
Percent
of total
1.1
0.4
0.4
1.9
5.4
19.5
64.1
89.0
1.8
3.8
0.7
6.3
1.3
1.1
0.4
2.8
100.0
Basis for estimates:
1. Emission factors Table 5-1.
2. Energy consumption Table 3-2.
3. Fuel properties
Anthracite coal - 13,000 Btu/lb., 10 percent ash.
Bituminous coal 12,000 Btu/lb., 10 percent ash.
Distillate oil 140, 000 Btu/gal.
Residual oil - 150,000 Btu/gal.
Natural gas - 1000 Btu/ft3.
Reference 15.
"Excludes naphtha, kerosene, range oil, and LP gas.
3-14
-------
Burners, combustion chambers, heat transfer characteristics, draft systems,
and combustion controls of industrial heating units may vary widely. The
practices of those responsible for selecting, installing, operating, and
maintaining stationary combustion sources can also have significant effects
on particulate emissions.
Because the rate of particulate emissions varies widely from unit
to unit, the amount of particulate emissions that may be expected from a
given source has not been established with accuracy. Data that are useful
for estimating emissions from groups of units have been compiled and are
reported as emission factors in Section 5.
3.3.2 Control Techniques
Techniques that will control particulate air pollution from stationary
combustion sources may be broadly categorized as follows:
1. Gas cleaning
2. Energy substitution
3. Energy conservation
4. Good practice
5. Source shutdown
Although source relocation and dispersion techniques will not reduce
particulate emissions from stationary combustion sources, they may effect
some measure of improvement in ambient air quality in selected areas.
3-15
-------
3.3.2.1 Gas CleaningGas cleaning is the most common technique used
for control of particulate emissions from stationary combustion sources.
As shown in Table 3-4, 20 million tons of an estimated total of 24.5 million
tons of particulate matter from stationary combustion was recovered by
gas cleaning devices in 1966.
A wide variety of gas cleaning equipment is available for control of
particulate emissions from stationary combustion sources. The cost of
gas cleaning equipment is usually greater for devices of high efficiency;
however, the performance of competitively priced gas cleaning equipment
may differ considerably. Table 3-5 shows the optimum performance that
may be expected from the various types of gas cleaning equipment that
might be used for removing particulate matter from flue gases of stationary
combustion sources. The efficiencies shown in Table 3-5 are estimates
based on an analysis of information on particle size distribution, equipment
efficiency, reports of experience from the field, and actual source tests.
More detailed information on the special application of these devices
to stationary combustion sources is given in Section 4, Gas Cleaning Devices.
Settling chambers - The settling chamber is a low efficiency, low
cost, low pressure drop gas cleaning device. Settling chambers are applied
primarily to natural-draft, stoker-fired, coal-burning units. Collection
efficiencies for this application are estimated to be 50 to 60 percent. Only
a few oil-fired, gas-fired, and other coal-fired combustion sources are
equipped with settling chambers.
3-16
-------
Table 3-5. OPTIMUM EXPECTED PERFORMANCE OF VARIOUS TYPES OF
GAS CLEANING SYSTEMS FOR STATIONARY COMBUSTION SOURCES
Sources
Coal-fired
Spreader, chain grate, and
vibrating stokers
Other stokers
Cyclone furnaces
Other pulverized coal units
Oil-fired
Removal of uncontrolled particulate emissions, %
Systems in operation
Settling
chambers
50a
60"
ioa
20"
5b
Large
diameter
cyclones
60a
65"
15a
30a
iob
Small
diameter
cyclones
85a
90a
70a
a
80
30b
Electrostatic
precipitators
99.5°
99.5°
99.5°
99. 5C
75.0
Stack
sprays
GO6
806
f
f
f
Systems under development
8-in.
pressure
drop
scrubbers
99+g
99+g
f
99+g
f
Fabric
filters
99. 5h
99.5
f
h
99.5
f
CO
I
Estimate based on references 17 and 18.
'Reference 19.
Efficiency estimated - not commonly used.
f.
Insufficient data for estimate.
'Estimate based on reference 15.
or
Estimate based on reference 20.
Estimate based on private reports of field experience.
Estimate based on reference 21.
-------
Large-diameter cyclonesLarge-diameter cyclones are more
efficient than settling chambers, but have higher pressure drops. Effi-
ciencies of large-diameter cyclones range from a high of 65 percent for some
types of stoker-fired coal-burning units to a low of 15 percent for coal-fired
cyclone furnaces.
Multiple small-diameter cyclones - Multiple small-diameter cyclones
are used on mechanical draft combustion units either as precleaners for
electrostatic precipitators or as final cleaners. Efficiencies of well
designed units range from 90 percent for some stoker-fired units to
70 percent for coal-fired cyclone furnaces.
Wet scrubbers - Sprays are used to a limited extent in the stacks of
coal-fired units to control particulate emissions during soot blowing. The
problems that limit the use of wet scrubbers include high corrosion rates,
high or fluctuating pressure drops, adverse effects on stack gas dispersion,
and waste disposal. Technically, these problems can be overcome, but
the feasibility of wet scrubber systems for stationary combustion source
particle control has not yet been demonstrated.
Wet scrubbers have been used experimentally for the removal of
sulfur oxides from the flue gases of coal-fired sources. These scrubbers
also removed combustion particulate matter with efficiencies of up to
20
99.5 percent. A recently completed full-scale system connected to a
pulverized coal-fired power plant boiler in Missouri is similar to the
3-18
-------
experimental installation. Evaluation of the economic feasibility and
effectiveness of this system must be deferred until after shakedown runs
are complete.
Electrostatic precipitators - Electrostatic precipitators are the most
common gas cleaning devices used to remove particulates from the flue
gases of large stationary combustion sources. Such devices are capable
of collection efficiencies of at least 99.5 percent, and it is quite possible
that even more efficient systems can be provided if necessary. Electro-
static precipitator systems are usually applied to large pulverized coal-
fired power boilers. The cost of these systems has limited their use on
smaller combustion sources.
Electrostatic precipitators are highly sensitive, and if not properly
designed, small changes in the properties of the particles and the gas
22
stream can significantly affect their collection efficiencies. Allowance
should be made for possible changes in fuels, in fuel composition, and in
gas temperature when consideration is given to the use of electrostatic
precipitators. It has been established that low-sulfur fuels adversely
affect the particulate collection efficiency of electrostatic precipitators
23
designed for high-sulfur fuels.
Fabric Filters - Fabric filters are not commonly applied to stationary
combustion sources. Factors which limit the use of these devices are
uncertainty of performance and reliability, and availability of other
effective gas cleaning devices.
3-19
-------
3.3.2.2 Source Relocation - Source relocation will not eliminate participate
emissions from stationary combustion sources, but it will eliminate emissions
from the original location of the source. Due consideration should be given,
however, to possible air pollution effects on other areas.
Source relocation is ordinarily considered when new stationary com-
bustion sources are to be built, particularly when a new plant is to be built
to replace one that has created air pollution problems.
3.3.2.3 Energy Substitution - The emission characteristics of fuels used
in stationary combustion processes may differ widely. Therefore, some
measure of control may be effected by substituting among the various fuels.
Control of emissions may also be effected through the substitution of non-
combustion energy for combustion energy. The substitutions considered
in this section are limited to the more commonly used types of energy
hydraulic, electric, and nuclearand fossil fuels. Fuels that might
be considered as substitutes are LPGgas, coke oven gas, blast furnace
gas, pipeline gas from coal, kerosene, range oil, coke oven tar, liquified
coal, and low-ash coal. Although chemical, solar, and geothermal energies
have long-range potential as substitutes that would reduce particulate
emissions, these sources are not sufficiently developed to warrant current
consideration.
Information on cost and availability of energy substitution is given in
Control Techniques for Sulfur Oxide Air Pollutants, U. S. Department of
Health, Education, and Welfare, 1969.
3-20
-------
Power generation by stationary combustion is a principal source of
participate emissions in the United States (see Table 3-4). Energy sources
used to generate power are water, nuclear fuel, gas, oil, and coal as shown
in Table 3-6. Particulate emissions from gas- and oil-fired power plants
total less than 0. 1 pound per million Btu input. Coal-fired power plants
equipped with gas cleaning devices that are 99.5 percent efficient compare
favorably with oil- and gas-fired plants. Hydroelectric and nuclear power
plants are particulate pollution free.
Substitutions commonly available for commercial, industrial, and
domestic stationary combustion sources are electric power, coal, gas,
and oil. Fossil fuels may be burned directly at the site where energy is
used, or the fuels may be used to produce electrical energy for transmission
to the site of use. Tables 3-7 and 3-8 compare the effectiveness of various
substitution alternatives on the basis of particulate emissions per unit of
useful heat.
When comparing substitution alternatives, allowance should be made
for differences in heat requirements between seemingly identical applications.
The differences that might be found between fossil fuel and electrical heat
f
requirements for space heating may be used as an example. Because
electrically heated buildings are often insulated better than fossil fuel
heated buildings, heat requirements may not be the same. It is recom-
mended that individual studies be made to determine these differences by
3-21
-------
Table 3-6. COMPARISON OF ENERGY SUBSTITUTION
ALTERNATIVES FOR ELECTRIC POWER GENERATION
Energy substitution
alternative
Particulate emissions,
lb/106 Btu inputa
Hydroelectric
Nuclear
Gas (no control)
Oil (no control)
Coal - 90 percent fly ash
removal
Coal - 99. 5 percent fly
ash removal
0
0
0.02
0.07
0.67
0.03
aBased on emission factors from Table 5-1 and the following gross
heating values:
Coal - 12, 000 Btu/lb at 10 percent ash.
Oil - 150,000 Btu/gal.
Gas - 1,000 Btu/ft3.
3-22
-------
Table 3-7. COMPARISON OF ENERGY SUBSTITUTION ALTERNATIVES FOR
STATIONARY COMBUSTION SOURCES OF LESS THAN
10 MILLION Btu/hr INPUT
Energy substitution alternative
Particulate emission
o
equivalent
lb/106 Btu useful heat
Electric heat (hydroelectric or nuclear power
plant originated)
Electric heat (gas-fired power plant originated)
Electric heat (oil-fired power plant originated)
Electric heat (coal-fired power plant originated
90% fly ash removal)
Electric heat (coal-fired power plant originated
99. 5% fly ash removal)
Gas-fired furnace on site (no control)
Oil-fired furnace on site (no control)
Coal-fired furnace on site (no control)
0
0.05
0.22
2.00
0.10
0.03
0.08
1.11
Based on:
1. Emission factors - Table 5-1.
2. Fuel properties.
Heating value, coal - 12,000 Btu/lb at 10% ash
Heating value, oil - 140,000 Btu/gal
Heating value, gas - 1,000 Btu/ft3
3. Estimated thermal efficiency of on-site heating systems.
Electric - 100%
Coal, gas, oil - 75%
4. National average efficiency of power generation -(Btu equivalent of
generated power per unit of heat input).
Coal - 33.42%
Gas - 31.42%
Oil - 30.77%
3-23
331-716 O - 69 - b
-------
Table 3-8. COMPARISON OF ENERGY SUBSTITUTION ALTERNATIVES
FOR STATIONARY COMBUSTION SOURCES OF
10 MILLION TO 100 MILLION Btu/hr INPUT
Energy substitution alternative
Particulate emission
equivalent,a
lbs/106 Btu useful heat
Electric heat (hydroelectric or nuclear power
plant originated)
Electric heat (gas-fired power plant originated)
Electric heat (oil-fired power plant originated)
Electric heat (coal-fired power plant originated -
90% fly ash removal)
Electric heat (coal-fired power plant originated -
99. 5% fly ash removal)
Gas-fired furnace on site (no control)
Distillate oil-fired furnace on site (no control)
Residual oil-fired furnace on site (no control)
Stoker-fired furnace on site (no control)
Stoker-fired furnace on site (90% fly ash removal)
Stoker-fired furnace on site (99. 5% fly ash removal)
0
0.05
0.22
2.00
0.10
0.03
0.14
0.20
2.78
0.28
0.01
Based on:
1. Emission factors - Table 5-1.
2. Fuel properties.
Heating value, coal - 12,000 Btu/lb at 10% ash
Heating value, distillate oil - 140,000 Btu/gal
Heating value, residual oil - 150,000 Btu/gal
Heating value, gas - 1,000 Btu/ft3
3. Estimated thermal efficiency of on-site heating systems.
Electric - 100%
Coal, gas, oil - 75%
4. National average efficiency of power generation24-(Btu equivalent
generated power per unit of heat input).
Coal - 33.42%
Gas - 31.42%
Oil - 30.77%
3-24
-------
consulting with representatives of the fossil fuel, electrical, and building indus-
tries and by using information such as that published by the American Society
25
of Heating, Refrigerating, and Air Conditioning Engineers.
To make comparisons for a given area, it is recommended that Tables
3-6, 3-7, and 3-8 be revised to reflect local conditions before substitution
alternatives are compared.
Energy substitution can be an effective and useful technique for control
of particulate emissions from stationary combustion sources. This technique
has special value for control of many small sources when the cost of effective
gas cleaning equipment would be excessive. When use of this technique is con-
sidered, attention should also be given to the effect of substitution on national
security, foreign relations, industry, labor, commerce, conservation, and the
public.
3.3.2.4 Energy Conservation
Energy conservation limits particulate emissions from stationary combus-
tion sources by reducing fuel consumption. Energy conservation that is econom-
ical should be encouraged per se. Energy conservation that is not economical
from the standpoint of individual process costs may actually be economical
when compared with other techniques available for air pollution control.
Improvement of power generation efficiency through use of high-tempera-
ture, high-pressure steam electric power generating processes reduces fuel
consumption. Table 3-9 shows average national trends in efficiency improvement
3-25
-------
Table 3-9. TRENDS IN EFFICIENCY OF COAL, OIL,
AND GAS USE IN UNITED STATES24
Year
1956
1963
1964
1965
Average Btu required to generate
1 (net) kw-hr
Coal
11,257
10,258
10,241
10,218
Oil
12,828
11,278
11,138
11,097
Gas
12,245
11,066
10,962
10,868
3-26
-------
for steam electric power generating plants. Large, modern power plants
with efficiencies near 8, 000 Btu per kw-hr reduce energy consumption sub-
stantially to below the national average of 10, 000 to 11,000 Btu per kw-hr, and
processes now under development, such as the magnetohydrodynamic, electro-
2628
gasdynamic, and fuel cell, have promise of improving efficiency even more.
3.3.2.5 Good Practice - Equipment must be properly applied, installed, oper-
ated, and maintained to minimize emissions of participate matter. Guidelines
for good practice are published by the fuel industry, equipment manufacturers,
good practice are published by the fuel industry, equipment manufacturers,
engineering associations, and government agencies. Although improper prac-
tices are frequently the cause of visible particulate emissions, insufficient
information exists to permit numerical evaluation of the effect of good practice
on emission levels. Some sources of information on good practice are:
L Air Pollution Control Association
2. American Boiler Manufacturers Association
3. American Gas Association
4. American Petroleum Institute
5. American Society of Heating, Refrigerating, and Air
Conditioning Engineers
6. American Society of Mechanical Engineers
7. Edison Electrical Institute
8. Industrial Gas Cleaning Institute
3-27
-------
9. The Institute of Boiler and Radiator Manufacturers
10. Mechanical Contractors Association of America
11. National Academy of Sciences - National Research Council
V2. National Air Pollution Control Administration
l;>. National Coal Association
11. National Fire Protection Association
15. National Oil Fuel Institute
16. National Warm Air Heating and Air Conditioning Association
17. U. S. Bureau of Mines
18. Various State and local air pollution control agencies
Proper design and application Combustion systems must be properly
selected to meet load requirements. Components of the system should be com-
patible to avoid excessive emission of particulate matter.
Stationary combustion units are designed to operate within a specific
range of load conditions. If such a unit is operated outside design limits,
excessive discharge of particulate matter is possible. It is therefore neces-
sary that the load be accurately estimated before stationary combustion systems
are selected and applied. The total design capacity of the system should be
sufficient to carry the maximum load, and consideration should be given to
future increases in load requirements. The minimum design capacity of one
unit of the combustion system should be sufficient to carry the minimum load
3-28
-------
requirements of the facility, and the total combustion system should be selected
to carry, within design limits, any load between maximum and minimum.
Consideration must also be given to load characteristics when selecting
a combustion system. The combustion system should be able to supply energy
at a change in rate consistent with the demands of the facility without deviation
from design limits.
Each component of the combustion system, such as the fuel handling sys-
tem, the draft system, the fuel burning system, the flues and stacks, the ash
handling system, and the controls related to these systems, must be properly
selected and integrated to handle the load and the fuel to be burned.
Proper installation Properly installed equipment will promote clean,
efficient operation of stationary combustion sources. Comprehensive instal-
lation instructions and plans are a prerequisite for proper installation. The
designer of the entire combustion system and the manufacturers of the system's
components are responsible for providing such plans and instructions. Equip-
ment should be installed only by qualified personnel, and all work should be
inspected for quality.
Proper operation and maintenance Proper operation and maintenance
of stationary combustion equipment will promote the reduction of particulate air
pollution. Stationary combustion units should be operated within their design
limits at all times and according to the recommendations of either the manu-
facturer or another authority on proper operational practices. Combustion
3-29
-------
units and system components should be kept in good repair to conform with
design specifications. Sensitive monitoring systems are helpful in indicating
needed combustion system repair.
Proper operation also involves the reduction of emissions from fuel- and
ash-handling systems. Storage pile fires and fuel- and ash-handling operations
can become significant sources of particulate air pollution if good practice is
disregarded.
3.3.2.6 Source Shutdown - Source shutdown is a drastic control technique,
but it should not be completely disregarded. Source shutdown is useful for
control of particulate emissions when air pollution levels threaten the public
health in emergency episode situations and for control of emissions when law-
ful orders to abate are ignored.
3.3.2.7 Dispersion - Dispersion is discussed in detail in Section 6 of the
report Control Techniques for Sulfur Oxide Air Pollutants.
3-30
-------
3.4 INDUSTRIAL PROCESSES
3.4.1 Introduction
Approximately 6 million tons of dust, fume, and mist, roughly 50 per-
cent of the total particulate matter emitted in the United States, were dis-
charged from industrial processes and industrial fuels fired in 1966. This
quantity would be considerably greater if high-efficiency collectors were not
used by many industries. However, the total would be drastically lower if
existing control technology were employed to the fullest.
Some industries inherently create more particulate air pollution than
others, and for such industries one or two specific operations dominate the
emission picture. In a given industry, particulate releases to the atmosphere
are generally proportional to production rates. Often these discharges can be
reduced dramatically through process changes or by the use of collection devices.
.Table 3-10 lists many of the industries that release large quantities of
particulate matter. As discharged, these particles include dry dusts, com-
bustible oil and tar mists, inorganic acid mists, and combinations of these
and other pollutants. The same processes frequently release gaseous pollu-
tants, some of which may be more objectionable than the particulate matter.
Although this discussion is limited to particulate matter, some remedial
measures also affect sulfur oxides, odors, or other gaseous contaminants.
The industries which are cited in the following pages commonly use
several types of fired heaters and boilers. Particulate emissions associated
3-31
-------
Table 3-10. INDUSTRIAL PROCESS SUMMARY
Industry or process
Iron and steel mills
Gray iron foundries
Non-ferrous smelters
Petroleum refineries
and asphalt blowing
Portland cement
Kraft pulp mills
Asphalt batch plants
Acid manufacture
Phosphoric
Sulfuric
Annual
capacity,
1000 tons
(except
as noted)
149.000
17, 350
2,721
6
3,650 x 10
bbls.a
500 x 106
bbls.b
300,000
-
2,300
20,513
Number
of
plants
184
1,400
2, 500
318
ISO
40
-
66
223
Particulatc emissions
Nature
Iron oxide dust,
smoke
Iron oxide dust,
smoke, oil and
grease, metal
fumes
Smoke, metal
fumes, oil and
grease
Catalyst dust,
ash, sulfuric
acid mist,
liquid aerosols
Alkali and
product dusts
Chemical dusts,
mists
Aggregate dusts
Acid mist, dust
Acid mist
Principal sources
Blast furnaces, steel making
furnaces, sintering machines
Cupolas, shakeout systems,
core making
Smelting and melting furnaces
Catalyst regenerator, sludge
incineration, air blowing
of asphalt
Kilns, coolers, dryers,
material handling
systems
Chemical reclaiming furnaces,
smelt tanks lime kilns
Dryers, material handling
systems
Thermal processes - phosphate
rock acidulating, grinding and
handling system
Other
emissions
CO, combustion
products
Odors, combustion
products, hydro-
carbons from con-
taminated scrap
SOX combustion
products
Hydrocarbons, SOX,
Ho.S, odors
Combustion
products
Odors, SOX
Odors, combustion
products
HF, SOX, odors
Reference
29, 30
31, 32
31, 33
31, 34
31, 35
36
37
CO
I
to
-------
Table 3-10 (continued). INDUSTRIAL PROCESS SUMMARY
Industry or process
Coke manufacturing
Glass furnaces and
glass fiber manufacture
Coffee processing
Cotton ginning
Carbon black
Soap and detergent
manufacturing
Gypsum processing
Coal cleaning
Annual
capacity,
1000 tons
(except
as noted)
54,278
-
1,496
"
-
-
Number
of
plants
60
-
37
"
-
-
Particulate emissions
Nature
Coal and coke
dusts, coal tars
Sulfuric acid mist,
raw material dusts,
alkaline oxides,
resin aerosols
Chaff, oil aerosols,
ash dehydrated
coffee dusts
Cotton fiber,
dust and smoke
Carbon black
Detergent dusts
Product dusts
Coal dusts
Principal sources
Charging and discharging oven
cells, quenching, material
handling
Raw material handling, glass
furnaces, glass fiber forming
and curing
Roasters, spray dryers,
waste heat boilers, coolers,
stoners, conveying equipment,
chaff burning
Gins, trash incineration
Carbon black generators
Spray dryers, product and
raw material handling
systems
Calciners, dryers, grinding
and material handling systems
Washed coal dryers
Other
emissions
Phenols, H2S
Combustion
products
Defoliants and
insecticides
Combustion
products,
odors
Combustion
products
Combustion
products
Reference
29
38
39
CO
I
CO
CO
aBarrel = 42 gallons.
bBarrel = 376 pounds.
-------
with this equipment, for the most part, are functions of the fuel burned. Com-
bustion principles developed in Section 3.3 generally apply, and the combustion
processes are not cited unless specific problems are associated with them.
3.4.2 Iron and Steel Mills
The major sources of participate matter in iron and steel mills are blast
furnaces, steel-making furnaces, and sintering plants. Coke ovens, which are
operated as adjuncts to steel mills, are discussed in Section 3.4.9.
3.4.2.1 Sintering plants Major sources of dust in sintering plants are the
combustion gases drawn through the bed and the exhaust gases from sinter
40
grinding, screening, and cooling operations. Exhaust temperatures of the
combustion gases range from 160° to 390° F. One 6000-ton-per-day plant oper-
ates at 350° F. About 50 percent by weight of the particles discharged from a
29
sintering machine are larger than 100 microns. Because dust generated in
the sintering operation can be returned to the process, most plants are equipped
with cyclones, which, because of the large particle size, usually operate at
over 90 percent efficiency by weight. However, cyclone exit loadings range from
0.2 to 0.6 grains per cubic foot. High-efficiency baghouses and electrostatic
precipitators, therefore, offer promise of much better collection. However,
few have been applied to sintering machines.
3.4.2.2 Blastfurnaces Iron ore, coke, and limestone are charged into a
blast furnace to make iron. Under normal conditions the untreated gases from
a blast furnace contain from 7 to 30 grains of dust per standard cubic foot(scf)
3-34
-------
41
of gas. Most of the particles are larger than 50 microns in diameter. The
dust contains about 30 percent iron, 15 percent carbon, 10 percent silicon
dioxide, and small amounts of aluminum oxide, manganese oxide, calcium
oxide, and other materials. Blast furnace gas cleaning systems normally re-
duce particulate loading to less than 0.01 grain per standard cubic feet to pre-
vent fouling of the stoves where the gas is burned. These systems are com-
posed of settling chambers, low efficiency wet scrubbers, and high efficiency
wet scrubbers or electrostatic precipitators connected in series.
3.4.2.3 Steel Furnaces The three most important types of steel-making
furnaces are open hearth furnaces, basic oxygen furnaces, and electric fur-
naces. Relative usage as a percent of total production of each of these furnaces
in 1958, 1966, and 1967 is shown in Table 3-11.
Average emission rate from a hot-metal open-hearth furnace is about
0.4 grain per scf for a conventional furnace and 1. 0 for an oxygen-lanced fur-
43 44
nace. ' Up to 90 percent of the particles are iron oxide, predominantly
FE 0 A composite of particles collected throughout a heat show that about
^ o
50 percent were less than 5 microns in size. Control of iron oxide requires
high-efficiency collection equipment such as venturi scrubbers and electro-
static precipitators. Because of the cost involved and the growing obsolescence
of open hearth furnaces, industry has been reluctant to invest money in the
44
required control equipment. Often these furnaces have been replaced by
controlled basic oxygen furnaces and electric furnaces.
3-35
-------
Table 3-11. STEEL PRODUCTION, PERCENTAGE BY PROCESS42
Furnace type
Open hearth
Basic oxygen
Electric
Percent of total
1958
90.7
1.5
7.8
1966
72.1
17.4
10.5
1967
55.6
32.6
11.8
3-36
-------
More emissions are created by the basic oxygen furnace than by the open-
hearth furnace. The principal portion of the increase in emissions is caused
from furnace oxygen blowing. Emissions of about 5 grains per scf are reported
45
as typical. Particle size is small; 85 percent are smaller than one micron
46
in diameter. All basic oxygen furnaces in the United States are equipped
with high-efficiency electrostatic precipitators or venturi scrubbers.
Electric furnaces are usually used for alloy production, and because of
their flexibility, are becoming popular for most metal melting operations.
Emissions from electric furnaces often reach particulate matter concentrations
of 3 grains per scf. Only 40 to 50 percent of the dust is iron oxide, an amount
considerably smaller than that emitted by other furnaces. The particles are
difficult to collect because of a strong tendency to adhere to fabric surfaces, a
high angle of repose, and a high electrical resistivity, and because they are
difficult to wet. Approximately 70 percent by weight of the particles are
smaller than five microns and 95 percent by number are smaller than 0. 5
47
micron in diameter. Nevertheless, except for difficulties inherent in the
charging operation, over 95 percent effective collection can be achieved with ap-
propriate hooding and high-efficiency collection equipment. Baghouses are
especially suited for such collection.
3.4.3 Gray Iron Foundries
Melting cupolas are the principal sources of particulate matter at iron
foundries. Casting shake-out systems, sand handling systems, grinding and
deburring operations, and coke-baking ovens are other sources.
3-37
-------
Cupola exhaust gases are hot and voluminous, and contain significant
portions of combustible matter and inorganic ash. The most effective control
system incorporates an afterburner to eliminate combustibles and a fabric
filter to collect the inorganic dust and fume. Coolers must be used ahead of
the baghouse to protect fabric filters from the heat of the exhaust gas. Most
such systems use glass fabrics, but some synthetic cloths have been found to
be satisfactory. Even though baghouse control systems provide excellent par-
ticle collection, they have not met with wide acceptance, principally because of
48
cost. Dry centrifugal collectors and scrubbers with various efficiencies are
used in many instances. High-efficiency scrubbers are reported to provide
about the same performance as fabric filters, but visible emissions are more
pronounced.
Casting shake-out and sand cleaning are dusty operations that are nor-
mally well controlled. The gas stream baghouses are commonly used; medium-
efficiency scrubbers and dry centrifugal collectors are also used.
Core ovens create relatively smaller quantities of participate matter,
much of which is in the form of finely divided liquid aerosols. Emissions from
core ovens are similar to those discharged from paint baking and resin curing
operations with odors being more objectionable than the particulates. A pro-
perly designed afterburner will eliminate most of the particulates and malodors.
3-38
-------
3.4.4 Petroleum Refineries
Major sources of particulate matter at refineries are catalyst regen-
erators, airblown asphalt stills, and sludge burners. Lesser sources include
fired heaters, boilers, and emergency flares.
In modern fluidized catalytic crackers, fine catalysts are circulated
through the reactor and regenerator vessels. From 100, 000 to 150, 000 cfm
of hot, dusty gases are vented from a large regenerator. Dust collectors as
well as carbon monoxide waste heat boilers are often used to control air pol-
lution. It is common practice to install a carbon monoxide boiler to use the
fuel value of the clean gas stream exiting from the particulate collector.
In typical installations 2-stage or 3-stage cyclones are located in the
regenerator vessels of FCC units for catalyst recovery and reutilization. In
some cases external cyclones are installed to reduce the particulate content of
the flue gases leaving the regenerators of these units. Catalyst dust losses
from the regenerator equipped with internal cyclones and in some cases sup-
plemented by external cyclone equipment can range in the order of 100 to 350
pounds per hour depending on the size, age, and basis of design of the unit.
Electrostatic precipitators may also be used to collect the fine particles
from the regenerator exit gases and some refiners have reported catalyst dust
losses as low as 40-60 pounds per hour although typical current installations
have higher emission rates. The percent efficiency of the precipitators is a
function of the inlet dust loading from the regenerator and the desired
emission rate to the atmosphere.
3-39
331-716 O - 69 - 7
-------
Airblowing of asphalts generates oil and tar mists and malodorous gaseous
pollutants. It is common practice to scrub the oils and tars from the hot (300
to 400° F) gas stream. Sea water is sometimes used for this purpose. In any
case, separators are necessary to reclaim the oil and prevent contamination
of effluent water. Afterburners are used to incinerate the uncondensed gases
and vapors, which can constitute an odor nuisance.
At petroleum refineries, the open burning or incineration of sludges can
be a major source of participate matter and sulfur dioxide emissions. These
sludges are a mixture of heavy petroleum residues and such inorganic materials
as clay, sand, and acids. Because the materials cannot be separated readily,
sludge is usually atomized in much the same way as heavy fuel oil. The or-
ganic fraction can be burned effectively in such an incinerator, but any inorganic >
matter is entrained in exhaust gases. High-efficiency precipitators, baghouses,
and high-energy scrubbers are among the stack cleaning devices that are avail-
able to collect the fine dusts; the final choice of control unit would be based
upon the nature of the sludge. Sulfur dioxide collection would not be effected.
However, if there is an accessible sulfuric acid plant, sludge may be condi-
ioned and used as part of the acid plant's feed material. Very low grade
sludges may be dumped at sea. It must be emphasized that incineration alone
is not the solution for the disposal of all forms of refinery waste sludges.
Solvent extraction is another method for recovering the organic fraction and
the separated "clean" solids are acceptable to normal landfill sites.
3-40
-------
3.4.5 Portland Cement
Both mining of raw materials and manufacture of cement create dust.
Dust is generated at the blasthole drilling operation at the quarry, during
blasting at the rock face, and during loading of trucks. At primary and sec-
ondary crushing plants, in the grinding mills, at blending and transfer points,
and in the final bagfilling and bulk truck or railroad car loading operations,
where the particulate-laden air is at ambient temperatures, bag filters are
49
usually the best means of control.
Rotary dryers used in dry process cement plants may be a major source
of dust generation and require collecting systems designed for higher temp-
eratures. Dust concentrations of 5 to 10 grains per scf entering the collector
are normal. Baghouses or combinations of multiple cyclones and baghouses
are frequently used. Newer dry process cement plants incorporate the drying
operation into the raw grinding circuit. In such a "dry-in-the-mill" combination
drying and grinding circuit dusts are normally vented to a baghouse.
The largest sources of emissions at cement plants are direct-fired kilns
for burning Portland cement clinker. Exit gas participate loadings are usually
5 to 10 grains per scf for wet kilns and 10 to 20 grains per scf for dry-process
kilns. Exhaust gases from wet-process kilns contain considerably more mois-
ture than gases from dry process kilns. The volume of the hot (500 to 600° F)
kiln gases may exceed 250, 000 cubic feet per minute. Over 85 percent by
weight of gasborne particles are smaller than 20 microns in diameter. The
3-41
-------
most prevalent chemical constituents are calcium oxide (CaO), about 41 per-
cent; silicon dioxide (SiO ), 19 percent; and aluminum and iron oxides (Al 0 +
£ Z 0
50
Fe O ), 9 percent. The balance would be predominately CO .
Li O
Electrostatic precipitators are widely used to control particulate emissions
from kilns. Fabric filters of siliconized glass bags have been installed on both
wet and dry process kilns. Each control device has been successful when ade-
quately designed and properly maintained.
3.4.6 Kraft Pulp Mills
The major source of particulate emissions in kraft pulping is the recovery
furnace in which spent cooking liquors are burned to remove the organic mate-
rials dissolved from the wood to recover the inorganic cooking chemicals. So-
dium sulfate is the major chemical released as particulate matter. Small amounts
of sodium carbonate, salt, and silica, and traces of lime, iron oxide, alumina,
and potash also are emitted. Because 95 to 98 percent of the total alkali charged
to the digester finds its way to the spent liquor, it is economically imperative
that it be recovered.
Electrostatic precipitators of about 90 percent efficiency are used to
recover particles emitted from recovery furnaces. New installations call for
design efficiencies of about 97. 5 percent, and at least one such unit has a de-
sign efficiency of over 99. 9 percent.
Other sources of particulate matter are smelt tanks and lime kilns.
Stack dust from lime kilns can be collected in 85 to 90 percent efficient venturi
3-42
-------
scrubbers. Water sprays of 20 to 30 percent efficiency and mesh demisters of
80 to 90 percent efficiency are usually used on smelt tanks.
3.4.7 Asphalt Batching Plants
Hot asphalt batching plants are potential sources of heavy dust emissions.
Asphalt batching involves the mixing of hot, dry sand, aggregate, and
mineral dust with hot asphalt. Although conveyors and elevators generate some
dust, the major source is the direct-fired dryer used to dry and heat aggregates.
Exit gases range from 250° to 350- at volume rates of 15, 000 to 60, 000 standard
cubic feet per minute (scfm). Most dryers employ simple cyclone separators
which collect 70 to 90 percent of the dust entrained in the exit gases. Never-
theless, the remaining dust in the gas stream usually totals more than 1000
pounds per hour and further dust controls are needed in most areas.
Centrifugal and baffled scrubbers have been used with success in many
areas to control the fine dust which escapes the primary cyclone. High effi-
ciencies are reportedsome exceed 99.0 percentwith losses from most
tested plants ranging from 20 to 40 pounds per hour. It is common to vent
51
elevators and major conveyor transfer points to the scrubber.
As high temperature fabrics were developed, fabric filters found greater
acceptance at asphalt batch plants. Such filters have been used successfully
at asphalt batch plants since 1950. Recently, several were installed in Chicago,
Illinois, in an effort to obtain better dust control than had been afforded with
scrubbers. They are reported to provide excellent collection of fine particles
-------
with little or no visible emissions from the baghouse. Although fabric filters
frequently are more expensive than scrubbers, they collect dry "fines" which
may be useable in high-grade asphaltic concrete mixes. In addition, they
obviate the need for holding ponds and preclude water problems.
3.4.8 Acid Manufacture
Most of the particulate matter attributed to acid manufacture is created
in the production of sulfuric and phosphoric acids. Manufacture of the other
two major industrial acidsnitric and hydrochloricdoes not generate large
amounts of acid mist.
3.4.8.1 Sulfuric Acid Over 90 percent of the sulfuric acid in the United
37
States is manufactured by the contact process. In the process sulfur or
other sulfur bearing materials are burned to sulfur dioxide (SO ) and catalyt-
Zj
ically converted to sulfur trioxide (SO ). Uncontrolled emissions range from
O
0. 05 to 0. 23 grain per scf of exit gas. Concentrations depend to a large degree
on plant design and proper operation of the acid absorber. Most modern plants
are equipped with high-efficiency electrostatic precipitators or mesh eliminators
in which 99 percent of the acid mist is recovered. Acid mists are usually
controlled to a far greater extent than gaseous SO releases.
Li
The primary source of emissions in the chamber process is the final Gay
Lussac tower. Combined sulfuric acid mist and spray in the exit gas ranges
from 0. 08 to 0. 46 grains per scf.
3-44
-------
3.4.8.2 Phosphoric Acid Two processes are used to manufacture phosphoric
acid. High-purity acid for the food and detergent industries is produced by
burning elemental phosphorous. The process is similar to the contact sulfuric
acid process. The oxidation product, phosphorous pentoxide (P O ), is hydrated
2 5
and absorbed in phosphoric acid. Mist is collected from exhaust gases with
electrostatic precipitators or high pressure drop mesh entrainment separators.
Acid mists escaping collection are extremely hygroscopic so that visible emis-
sions are pronounced unless high collection efficiencies are achieved. High-
purity phosphorous for this process is manufactured in electric furnaces, which
create gaseous fluorine compounds and solid particulates.
The wet process is used to produce less pure phosphoric acid for the
fertilizer industry. During the manufacturing process, sulfuric acid is reacted
with phosphate rock. Except for material handling and grinding operations few
particulates are generated. However, the acidulation reaction liberates large
quantities of gaseous silicon tetrafluoride (SiF ), and scrubbers are required.
3.4.9 Coke Manufacture
Metallurgical coke is the solid material remaining after distillation of
certain coals. About 90 percent of the United States coke output is used for
production of blast furnace iron.
Conventional coking is done in long rows of slot-type coke ovens into
which coal is charged through holes in the top of the ovens. Coke oven gas or
other suitable fuel is burned in the flues surrounding the ovens, to furnish
3-45
-------
heat for coking. Flue temperature is about 2600° F and the coking period aver-
ages 17 to 18 hours. At the end of the coking period, incandescent coke is
pushed out of the furnace into quenching cars and carried to a quenching station,
where it is cooled with water sprays.
The beehive oven is a simpler type of coking oven. Distillation products
from this oven are not recovered. Its use has diminished with the development
of the by-product oven. The process persists because of an economic advan-
tage during peak production periods. Capital investment is lower and inoper-
ative periods can be tolerated. About 1.5 percent of the total coal coked in
1967 was produced in these ovens. A very large part, i. e. , 25 to 30 percent
of the coal charged to these ovens is emitted to the atmosphere as gases and
participate matter. Ducting these emissions to an afterburner appears to be
a feasible method of control.
Coal and coke dust emissions result from coal car unloading, coal stor-
age, crushing and screening, the coking process (where the largest releases
of particulate dust occur during larry car coal charging of the by-product oven
and pushing of the product coke to quench cars), quenching, and final dumping
from the quench car.
Slot type coke ovens currently being designed include the following fea-
tures that speed operations and minimize leaks:
1. Better designed and thinner-walled heating flues to improve heat
transfer and minimize cool spots and undercoking. This results in
a cleaner pushing operation.
3-46
-------
2. Improved refractories, with less spalling and cracking. These
refractory defects cause warping of metal furnace parts, gas leaks
into flue systems and chimneys, and voids which fill with undercoked
coal and cause smoke during pushing.
3. Gas-tight, self-sealing oven doors, that minimize manual sealing
with clay.
4. Mechanical cleaners or self-sealers for doors and for top-charging
hole covers. A few grains of sand on a metal seat can cause appre-
ciable leakage of hot gases.
5. Sealing sleeves for levelling bars. Levelling bars are used to
even out the oven charge to allow free passage of gas over the charge
into the gas collector main.
6. Mechanical removal of top coal-charging lids and means to charge
all three holes of an individual -oven rapidly and simultaneously, with
gas recovery mains in operation.
7. Steam jet aspirators in byproduct header ducts.
8. An intercell header to normalize the cell pressure throughout the
battery.
9. Charging car volumetric sleeves and dust entrainment chutes.
10. Wooden baffling to separate particulate matter from quench tower
effluent gases.
3-47
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A breakthrough in coke manufacturing technology is needed to improve
operations.52 Improvements have been slow. Installations exist that have
employed supposedly superior charging and discharging equipment, but satis-
factory operations have not been achieved. A joint research effort by several
steel companies has been under way for 5 years to develop new coke manu-
facturing technology, but potential commercial applications appear to be five
53
years away.
Another form of coke, used in blast furnace refractories and in the manu-
facturing of electrodes for large steel and aluminum reduction furnaces, is
calcined petroleum coke. Petroleum coke is a refinery product, but is seldom
calcined by the refinery. Calcining occurs in a rotary kiln at 1700° F removing
absorbed water and heavy oil and forming a marble-size product. Volatilized
hydrocarbons are usually passed to a 2200° F combustion chamber before being
released to the atmosphere. Subsequent conveyance of the dusty product to
the storage requires hooding and enclosed ducting. The dust is abrasive and
causes heavy wear on bucket elevators and other transfer equipment. Control
of particulate matter can be accomplished during loading of the coke. One
system uses concentric tubing; the inner filling tube carries the coke and the
outer tube exhausts entrained dust from the enclosed railroad car, truck or
ship hold. Baghouses are used to capture dust from loading as well as dust
generated at other handling and transfer points.
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3.4.10 Primary and Secondary Recovery of Copper, Lead, Zinc, and Aluminum
Primary smelting of lead and zinc involves converting the sulfide of the
ore to an oxide through roasting, and subsequent reduction of the metal oxide to
its metallic state in a separate vessel. Copper, however, requires a preliminary
smelting step, during which the naturally occurring complex sulfide is reduced
to the cuprous sulfide, CuS , by mixing the charge with limestone. The cuprous
^
sulfide is then converted to blister copper in a converter where the sulfur is
removed by oxidation. Sulfur dioxide gas is released from these operations,
along with particulate matter which is largely sublimed oxides, dust, and acid
mists. When sulfur dioxide emissions exceed 3 percent of these furnace ex-
haust volumes, a sulfuric acid manufacturing plant is feasible. Pretreatment
of the smelter gases going to the acid is required to remove particulate matter.
If sulfur dioxide recovery is not practiced, fiberglass demisters or precipitators
are usually used to remove particulate material from smelter exhaust gases.
For a more detailed discussion of smelting, refer to the report Control Tech-
niques for Sulfur Oxide Air Pollutants.
Most materials fed to secondary recovery furnaces are alloys of copper,
zinc, tin, or lead in the form of solid scrap and drosses. Gases from the fur-
naces may contain as fumes oxides of the low boiling metals. Particularly
bothersome are submicron lead and zinc fume. Zinc oxide fume particle size
ranges from a high of 0. 5 micron to a low of 0. 03 micron. Baghouses are
usually used to control these oxide fumes; where the fumes are corrosive ,
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electrostatic precipitators are used. Soiled scrap metal melting may evolve
grease or oil fumes as smoke during the heatup phase. Incineration of the
smoke with a control afterburner is necessary if the metal cannot be cleaned
before melting.
Metallic aluminum is produced by the electrolytic reduction of alumina
(Al O0, in a bath of fused cryolite by the Hall-Heroult process. Cell operating
L± O
temperatures range from 1700° to 1800° F. The gases generated in the cells are
corrosive and toxic, and consist of hydrogen fluoride and volatilized fluorides.
Some fine particulate matter is entrained in the exit gases. Water scrubbers
have long been used for collection of both the particulates and corrosive gases.
54
Some installations have used baghouses with alumina coated cloth filter bags.
Secondary aluminum recovery operations produce particulate matter from
the fluxes used, from impurities in the scrap, and from chlorination of the
molten aluminum. Oily or greasy scrap gives off smoke. When chlorine gas
is used to degas the melt or remove magnesium, hydrogen chloride gas and
aluminum chloride fume are evolved. The fume is difficult to collect because
of its small particle size and hygroscopic nature. Water scrubbers are used
to collect the gaseous contaminants.
3.4.11 Soap and Synthetic Detergent Manufacture
Principal sources of particulate matter in the making of soap and syn-
thetic detergents are the spray drying of products and the handling of dry raw
materials. The wet chemical processes used to make soaps and detergents
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are relatively innocuous from the particulate standpoint, although malodorous
gases and vapors are generated in some instances.
Gases from the spray dryers, discharged at approximately 200° F, con-
tain large amounts of moisture. In addition, the product is sticky at these
temperatures so that dry collection in fabric filters or electrostatic precip-
itators is difficult. Multiple cyclones may be employed as precleaners, but
scrubbers are used almost exclusively to collect fine dust. Moderate pressure
venturi units or baffled scrubbers provide adequate control in many instances.
These scrubbers usually use slurries rather than merely water and product is
recovered from the slurries. Residual fine particles, together with high mois-
ture levels, frequently impart marked opaqueness to the stack gases. It is
sometimes possible to avoid this problem by adding some of the less stable
ingredients to the product after the spray drying operation.
Fabric filters are widely used in soap and detergent plants to control
dusts generated from the handling of products and raw materials and from
packaging operations.
3.4.12 Glass Furnaces and Glass Fiber Manufacture
Reverberatory furnaces are used to produce nearly all glass products.
The furnaces and raw materials generate significant quantities of particulate
matter.
Glass furnaces are usually heated with oil or natural gas, which is fired
directly over the melt. Heat is reclaimed in checkerwork regenerators used
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to preheat combustion air. Raw materials are charged at one end of the fur-
nace and molten glass is pulled from the other end. Cullet (scrap glass), lime-
stone, soda ash, and sand are the main ingredients fed to the furnace melter
section. Glass temperatures are as high as 2700° F in the furnace, but are
usually near 2200° F at the point of discharge. Participate matter in exhaust
gases is traceable to two principal sources: (I) Fine raw materials that are
entrained in combustion gases before they are melted; and (2) Materials from
the melt, such as sulfur trioxide created by sulfate decomposition and other
solids picked up by escaping carbon dioxide gases. Sulfur trioxide and the
oxides of potassium, sodium, and calcium are the main constituents of partic-
ulate emissions. Losses from large furnaces range from less than 10 pounds
per hour to as high as 100 pounds per hour. Most units release less than 40
pounds per hour. Particulate releases tend to be affected by feeder designs
and the makeup of raw materials.
Operators control emissions through furnace design, electric heating,
and raw material control rather than with stack cleaning devices. Control of
emissions with fiberglass filters is feasible, but the particulate matter is
extremely difficult to handle.
In the manufacture of glass fiber, the emissions from the forming pro-
cesses are considered unacceptable both from the standpoint of odor and visible
particles. Although suitable control methods are not at hand, it appears that
a combination of process changes and stack controls will be required to render
3-52
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exit gases acceptable in many communities. These methods are being developed
and prospects are good that satisfactory techniques will be found. Afterburners
have been employed with success at curing ovens where volumes are low in
comparison to forming lines.
3.4.13 Carbon Black
Because of the extremely fine size (0. 01 to 0. 4 micron) and fluffy nature
of carbon black particles, they are readily emitted from improper handling and
transferring operations and during separation of them from the process gases.
Emissions have been particularly heavy from channel black process plants.
The furnace black process (oil and gas) accounts for 94 percent of the total
production and technology is available to control emissions from these plants.
Furnace temperature is kept at about 2500° F and the black-laden gases
are cooled to 450° and 550° F before entering the dust collecting equipment. The
39
preferred system consists of an agglomerator followed by a baghouse. Coated
fiberglass bags last about 12 months. The over-all particulate collection ef-
ficiency of such a system is about 99 percent. The combination of cyclone
and electrostatic precipitator is no longer satisfactory because it collects
only about 60 percent of the particulate matter.
3.4.14 Gypsum Processing
Gypsum, the basic ingredient of plaster and wallboard, is manufactured
by grinding, drying, and calcining gypsum rock. At most plants much of the
gypsum is processed into wallboard in highly mechanized systems. Grinding,
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drying, and calcining processes are principal sources of dust. Handling,
packaging, and wallboard manufacture are of secondary potential.
Most grinding operations are controlled with fabric filters. Fine grinders
often are equipped with built-in pneumatic conveyors that allow the product to
be collected in the filter.
Gypsum is dried in direct-fired dryers to remove free moisture before
calcining. Exit gases of about 220° F contain a large amount of fine dust.
Electrostatic precipitators, baghouses, or scrubbers are almost always used
to remove this dust from exit gases.
The calcining operation is conducted at 400° to 450° F in externally heated
kettles or conveyors. In general, exit gases from the calcining operation are
less voluminous than those from dryers. Historically, electrostatic precipita-
tors have been used to control calciners. Dust collection has not always been
adequate, and baghouses now find better acceptance. Most new gypsum plants
have been equipped with fabric filters. High-temperature fabrics are required
and heaters have to be installed to prevent moisture from condensing in duct
work.
Baghouses are used extensively in modern gypsum plants to collect dust
from various conveying and processing points. In most instances a salable
product is reclaimed.
3.4.15 Coffee Processing
The processing of green coffee beans and the production of dehydrated
instant coffee generate dust and liquid aerosols as well as odorous gases. The
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most prominent sources are roasters, spray dryers, waste heat boilers,
and green coffee cleaners.
Roasters are the predominant sources of oil aerosols and odors but also
create significant amounts of solid particulate matter. Chaff, a flaky membrane
from the bean, and other solids are collected in simple cyclones at tempera-
tures of 400° to 500° F. Remaining aerosols and odorous gases may be inciner-
ated in afterburners at temperatures ranging from 1200° to 1400° F.
Coolers and stoners create additional solid particulate matter, but few
aerosols or malodors. Cyclones normally provide adequate dust control. With
some continuous systems, the exit of roaster gases through close coupled coolers
requires the use of afterburners on the cooler exhaust stream.
Spray dryers not unlike those used in other industries are used to produce
instant coffee. If the dryer is operated properly, very little fine particulate
matter is generated and satisfactory dust control can be achieved with dry
multiple-cyclone collectors. Periodic excursions can be expected with resultant
discharges of fine dust. Many plants operate scrubbers or baghouses down-
stream of mechanical collectors. Collected fines are blended with the main
product stream. Dust recovered in dry collectors is of sufficient value to make
it attractive to maintain collector efficiencies.
At instant coffee plants, large quantities of leached coffee grounds are
produced. Many operators burn the spent grounds in waste heat boilers similar
to coal-fired boilers. Particulate emissions are dependent on the type of firing
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and the ash content (usually about 4 percent by weight of dry grounds). A
common design incorporates an underfeed stoker and auxiliary gas burners.
Green coffee cleaning and handling creates dust and chaff which nor-
mally can be handled well in simple cyclones.
3.4.16 Cotton Ginning
The major sources of particulate matter in cotton ginning are the gin
itself and the subsequent incineration of the trash. Relatively coarse materials
are emitted from the ginning operation and relatively fine materials escape the
associated lint cleaner. High-efficiency multiple-cyclones successfully collect
the coarse particles, and the recently developed stainless steel in-line filter
is effective on the fine particles.
Disposal of the cotton trash by composting, rather than incineration,
is being practiced in some parts of the country. Incineration of trash generates
a large portion of the particulate matter released from uncontrolled ginning
plants.
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3. 5 CO NSTRUC TIO N AND DE MO LITIO N
3.5.1 Introduction
The demolition and construction of buildings and roads creates particulate
air pollution with periodic emissions characteristically dependent on the specific
operations. The handling of dusty materials, movement of trucks on temporary
roads, and breaking of masonry walls are a few of the more prominent dust
generating operations. None is continuous and the dust from almost all can be
reduced if suitable procedures are used.
Principal demolition, construction, and related operations that generate
particulate air pollution are:
1. Demolition of masonry.
2. Open burning of wooden structures, trees, shrubbery, and construc-
tion lumber.
3. Movement of vehicles on unpaved .roads.
4. Grading of earth.
5. Paving of roads and parking lots..
6. Handling and batching of Portland cement, plaster, and similar
materials at the site.
7. Sandblasting of buildings.
8. Spray painting of exposed surfaces.
Essentially all of these processes generate particulates that create local
nuisances. Techniques have been developed to minimize dust releases from
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most offending operations; however, none of these are entirely satisfactory.
Furthermore, all of the control measures require some expense and attention
and offer little, if any, monetary return.
3. 5. 2 Demolition of Masonry
When a brick, plaster or concrete wall is demolished, most of the parti-
culate matter is released when the broken wall hits the ground or floor. In
urban areas, water sprays are used to keep exposed surfaces as wet as pos-
sible. Before walls are torn down they are sprayed with water, and as the
debris crashes to the ground more water is sprayed onto the pile. The pro-
cedure at best is inefficient and as it is ordinarily practiced may reduce
particulate matter by only 10 to 20 percent. In cold or freezing weather,
water spraying systems become almost completely inoperable.
One concept of dust collection at demolition sites calls for enclosing the
four sides of the building by means of plastic sheets attached to the scaffolding
55
by removable clips. The top of the building is left open and air is sucked
in by a large exhaust fan into bag filters for collection. As yet this concept
has not been applied. Nevertheless, it offers one of the few possibilities for
adequate collection of demolition dust in congested metropolitan areas.
3. 5. 3 Open Burning
Because open burning cannot be controlled adequately, the only solution is
to stop the practice and remove wood and other combustibles to an incinerator
or sanitary landfill or to handle it in some other acceptable manner.
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3_. 5.4 Road Dust
Trucks moving across dry, unpaved roads are a prime dust source at
construction projects. Dust can be held to a tolerable level by blacktopping or
at least oiling such surfaces. For very temporary roads, frequent spraying
with water may be satisfactory.
3. 5. 5 Grading Roads and Other Surfaces
There are few satisfactory remedies for dust created by earth-moving
equipment. It is best to conduct such operations when winds are light and
materials are sufficiently moist to minimize entrainment of dust in ambient
air currents. Sand, rock, gravel, and the roadbed can be sprayed with water.
3. 5. 6 Handling Dusty Materials
Portland cement, plaster, and similar items are easily rendered airborne
during handling and batching. If the materials are mixed at the site, greater
possibilities are presented for the evolution of dust. The best approach is to
mix such materials in a central location, hooding all major points and venting
the dust to a fabric filter.
3.5.7 Sandblasting
The cleaning of stone and concrete surfaces by sandblasting creates
particles that are difficult to control by common techniques. When access is
possible, hooding and ductwork can be provided from the point of sandblasting
to a baghouse or similar high-efficiency dust collection device. A more
common practice has been to shroud the operator and the area being cleaned.
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Most of the resultant dust is contained within the canvas shroud and drops to
the ground below. A clean air supply has to be piped by hose to the operator.
The arrangement is successful when winds are light. Under strong wind
velocities much of the particulate matter remains airborne. Sandblasting of
buildings has been replaced in many areas by steam cleaning and acid washing.
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3.6 SOLID WASTE DISPOSAL
3.6.1 Introduction
Disposal of solid wastes contributes to air and water pollution and threatens
to pollute the land (through improper disposal methods). In 1967, 190 million
tons of solid wastes were collected excluding some industrial and agricultural
£- f-t
sources. Of this quantity, 86 percent was disposed of at land disposal sites,
8 percent was burned in municipal incinerators, and only 6 percent was dis-
56
posed of in what could truly be called a sanitary landfill. Much of the
waste in disposal sites is ultimately burned in the open. Although emissions
from the burning of solid wastes represent less than 10 percent of the 1 million
tons of particulate matter emitted in this country, these emissions represent
57
the most frequent cause of local air pollution complaints by citizens.
Particulate emissions from incineration cause soiling, visibility reduction,
and a generally unsanitary appearance of the air.
Better engineering and planning are required to cope with the problem of
disposing of solid wastes in a manner that will least affect our environment.
One survey indicates that if present trends continue and long-range plans are
not made and implemented, this country will not have the capability to handle
58
the increased amount of solid wastes generated in the year 1975. Planning,
perhaps on a regional basis, and proper use of existing technology, specifically
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in the fields of incineration and sanitary landfill operation, are the key to
mastering the problem of air pollution from solid waste disposal.
3. 6. 2 Definition of Solid Waste
As defined in the Solid Waste Disposal Act of 1965, "The term 'solid waste'
means garbage, refuse, and other discarded solid materials, including solid-
waste materials resulting from industrial, commerical, and agricultural
operations, and from community activities, but does not include solids or
dissolved material in domestic sewage or other significant pollutants in water
resources. . ." It includes both combustibles and non-combustibles, such as
garbage, rubbish, ashes, street refuse, dead animals, and abandoned auto-
59
mobiles. Solid waste is grouped into the following five categories:
1. Residential and commercial solid waste. Food waste, paper,
plastics, metals, cloth, wood, and numerous other materials are
included in residential and commercial solid waste. Heating value
is approximately 4500 Btu per pound. Uncompacted density is
approximately 250 pounds per cubic yard - compacted density is
approximately 500 pounds per cubic yard.
2. Construction and demolition waste. This category includes building
materials such as wood, steel, plaster, brick, and concrete.
3. Institutional solid waste. Wastes from hospitals, nursing homes, and
other institutions are included in institutional solid waste. Such
wastes are similar to residential and commercial solid wastes, but
may contain pathogenic materials.
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4. Industrial solid waste. Waste products as produced by industry include
a variety of combustible and non-combustible materials.
5. Agricultural waste. Agricultural waste includes animal droppings and
crop residue, but does not include stands of timber or brush burned
as a result of accidential forest fires. Reference articles on agri-
cultural waste disposal may be found in Section 8, Bibliography,
under the heading of Food and Agricultural Sources.
3. 6. 3 Amounts of Solid Waste Generated
The amount of solid waste generated in this country is truly astronomical.
Altogether, 190 million tons per year or 5. 3 pounds per person per day are
collected. A breakdown of this latter figure is shown in Table 3-12. These
figures however, are only for that amount of waste actually collected. Other
amounts are also generated beyond that collected and these amounts are best
described in the following quotation from Reference 56.
'It must be recalled that 10 to 15 percent of household and com-
mercial wastes are collected or transported by the individual generating
the waste. Approximately 30 to 40 percent of the industrial wastes are
self-collected and transported. Additionally, local regulations or lack
of thempermit over 50 percent of our population to burn some type of
household waste in their backyards. About 45 percent of commercial and
other establishments are also allowed to practice controlled open burning
of some type. Thus, although the amount of waste material that has to be
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Table 3-12. AVERAGE SOLID WASTE COLLECTED
(Pounds per person per day)
56
Solid wastes
Household
Commercial
Combined
Industrial
Demolition, construction
Street and alley
Miscellaneous
TOTALS
Urban
1.26
0.46
2.63
0.65
0.23
0.11
0.38
5.72
Rural
0.72
0.11
2.60
0.37
0.02
0.03
0.08
3.93
National
1.14
0.38
2.63
0.59
0.18
0.09
0.31
5.32
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collected is staggering in itself, the amount of material that is actually
generated and could pose potential collection problems is even more im-
pressive. Conservative estimates indicate that 7 pounds of household,
commercial, and municipal wastes are presently generated per person;
this totals over 250 million tons per year. To this must be added our es-
timate of over 3 pounds per person per day for industrial wastes, amount-
ing to an additional 110 million tons per year. Thus, estimates for 1967
indicate that over 10 pounds of household, commercial, and industrial
wastes are being generated in this country for every man, woman, and
child, totalling over 360 million tons per year.
"To these figures we must add over 550 million tons per year of
agricultural waste and crop residues, approximately 1. 5 billion tons per
year of animal wastes, and over 1. 1 billion tons of mineral wastes.
Altogether, over 3. 5 billion tons of solid wastes are generated in this
56
nation every year.
3.6.3.1 Disposal Methods to Minimize Air Pollution Many areas of the
country have adequate land available for sanitary landfills. A properly oper-
ated sanitary landfill in which solid waste is buried daily without burning can
turn a worthless piece of property into a valuable recreation area. The cost of
a landfill operation, in most cases, is less than incineration, not considering
fin
hauling costs in either case. Expanded use of landfills, of course, may re-
quire an efficient municipal pick-up system. At present, only about 6 percent
of municipal solid waste, not including industrial and agricultural waste, is dis-
posed of in a sanitary landfill.
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Some solid wastes such as automobile bodies, paper and wood chips have
a salvage value or reclamation potential. If a market exists in an area for part
of all of the waste currently being burned, it can be developed and used to re-
duce or eliminate air pollution. Frequent collection of municipal refuse and the
pickup of leaves in the fall will deter the citizen from open burning. Disposal
methods other than combustion are, in many cases, economical. These meth-
ods can be put to use, however, only with the execution of adequate planning.
In metropolitan areas in which land is becoming scarce for landfill opera-
tions, combustion processes are being used to reduce refuse volume by as much
as 90 percent before disposal in a landfill, increasing the life expectancy of
the landfill site. Incineration is often used to sterilize pathogenic or con-
taminated waste and reduce its volume before burial. Our expanding society
may have to resort to more extensive incineration in many areas as an alterna-
62
tive to landfill.
Of the total amount of municipal solid waste produced, not counting agri-
cultural or industrial solid waste, 86 percent is ultimately disposed of in open
p~ /?
dumps where open burning is frequently practiced. Such methods of volume
reduction normally do not meet health and esthetic standards that usually are
/-> f)
desired by a progressive community, because of the large amount of particu-
late matter (as much as 16 pounds per ton of solid waste burned) released to the
atmosphere with virtually no possibility of controlling emissions.1 Open burn-
ing has been banned in at least six states. 65
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Even today many apartment house, commercial, and municipal incinerators
being built do not meet requirements of good air pollution control standards.
Some incinerators can operate with a minimum of air pollution; however, these
units are costly to operate and maintain, and if poorly operated will create
noticeable air pollution. The trend today is toward multiple-chamber incinerators
of adequate design that are equipped with efficient control devices and full instru-
mentation, and well as towards controlled municipal size units. Municipal units
now proposed in this country are of the water-wall type that produce steam as a
saleable product and collect more than 99 percent of the particulate matter emit-
ted from the incinerator itself by means of electrostatic precipitators.
3.6.3.2 Disposal Methods Without Incineration Disposal and volume-reduction
methods that do not use incineration are most desirable from an air pollution
standpoint. In many cases they may be more economical and may prove to be
more acceptable to a community than methods using incineration.
Sanitary landfillThe sanitary landfill, which should not be confused with
d G.
an open dump, is an acceptable means of solid waste disposal. Almost any
kind of material can be disposed of by this method of systematically dumping
solid waste on the ground or in trenches, compacting the waste by driving a
bulldozer or other heavy equipment over it, and covering the waste at the end of
each day with a layer of compacted earth to prevent rodent and insect infestation
and to confine odors. When completely filled, land so used may be made into
parks and recreation areas. A properly operated sanitary landfill is operated
without open burning. Air pollution emissions are limited to material entrained
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in the air by earth-moving equipment. Even these emissions, however, can be
kept to a minimum by wetting the fill material.
Choice of a site and method of operation of a sanitary landfill is essen-
tially dependent on the topography and availability of land. In addition, other
factors such as length of haul, land drainage, source of cover material, and
quantity of land needed to handle future waste generation must be considered
before choosing a final site. Some factors that must be considered are:
1. Land requirements. About 1 acre-foot of land is required for each
1000 persons for one year operation when the production of waste
67
is 4. 5 pounds per day per capita. In addition, cover material
totaling at least 20 percent by volume of the compacted waste
is required. Such material may be supplied from the site or trans-
ported from nearby areas. Normally, sites are designed for 10-
to 20-year service periods.
2. Topography. Depressed areas such as ravines and abandoned pits
where the grade must be raised are usually considered desirable
for sanitary landfill sites. Flat land can be used by applying
r> /»
progressive excavation or the cut and cover method of operation.
3. Operation. Proper operation of a sanitary landfill requires contin-
uous use of heavy earthmoving equipment to compact and cover
the waste with fill material. It is essential that waste be
covered by no less than a 6-inch layer of material at least
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once a day. An intermediate layer of cover material (about 1
foot deep) is usually spread over completed sections of the site.
An additional 2 feet of final cover is required as a minimum for
the entire site on completion of the operation.
4. Cost. Costs of site, site preparation, and operation must be
computed to judge the true cost of sanitary landfill operation.
In addition, the final value of the land when reclaimed must be
balanced against the initial cost of the land. Sanitary landfill
equipment and operating costs usually range from $0. 80 to $1. 50
/? o
per ton of solid waste placed in the landfill. (Transportation of
waste to the site is not included in this figure.)
Composting - Composting, as applied to waste disposal, is the biological
decomposition of the organic component of waste. Stable organic residue is the
ultimate product. The residue is usable as a low-grade soil conditioner. The
market for compost, however, has not been very good, because equivalent
commercial products are available at less cost.
Composting requires separation of non-organic material from the waste.
To be economical, a market for such scrap is necessary.
Composting costs are the same or higher than those of incineration.
69
Consequently, only a few plants are operating in the United States today.
Actually, however, in the case of a composting plant operated by a municipality,
there is no more reason to expect such a plant to be profitable than an
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incinerator, as both perform essentially the same service for the citizens of
the municipality: that of getting rid of solid wastes. In areas where commercial
fertilizer is not readily available and the scrap market is good, composting
could be a suitable method for handling organic wastes with little or no
particulate air pollution. However, some compost plants have odor problems.
Shredding - Disposal of bulky waste can be facilitated by shredding. Auto
tires, for instance, can be shredded and placed in a sanitary landfill instead
of being burned. Bulky wood waste, such as driftwood and combustible
demolition waste, which has heretofore been burned openly because of the
difficulty of incinerating it, can be shredded and incinerated in a conventional
incinerator provided it is mixed with conventional refuse so that it does not
blind the grates. It can also be disposed of in a landfill site.
Each year more than six million automobiles are junked in the United
States. Automobile body disposal, therefore, is one of the growing solid waste
problems. The most promising solution to the problem appears to be to step
up the reuse for autobody metal scrap in the domestic steel and foundry
industry, so that the large portion of the available supply now being discarded
each year can be remelted.
Air pollution arising from disposal of automobile bodies results, how-
ever, when they are burned to remove upholstery, grease, and paint. Such
burning is apparently required to produce a useable scrap that is competitive
with other available material. Open burning of automobile bodies has proven
3-70
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entirely unacceptable from an air pollution standpoint. Large quantities of
particulate matter are generated by such burning. Metallic particles con-
taining cadmium, nickel, and lead may also be released by this method of
disposal.
Open burning of junk automobiles has been replaced by controlled
70
incineration in enclosures. Emissions from such practices have been
successfully controlled by afterburners, wet scrubbers, and electrostatic
precipitators. Unfortunately, however, because of the low market price paid
for automobile scrap, the cost of purchasing, operating, and maintaining such
control equipment is prohibitive in many areas. It would appear therefore,
that these control techniques need to be reapplied, perhaps in conjunction with
process changes, to lower operating and maintenance costs, and allow the
higher installation costs resulting from more sophisticated designs to be
amortized over the life of the installation. Such designs might attempt to
minimize inlet air flow so that the control devices could be made as small and
71
inexpensive as possible. Also, where afterburners are used, heat recovery
might be considered.
A possible solution to the air pollution problem is the expanded use of
mechanical devices which can disintegrate and shred a whole car (minus the
block, rear axle, and seats), remove contaminants by a series of mechanical
separations, and produce a relatively useable scrap with little or no
72
incineration. Such processes can be used by most larger cities. Cost of
3-71
331-716 O - 69 - 9
-------
equipment for a unit capable of handling from 200 to 300 cars per day is
$500, 000. Cost for a unit capable of handling 1200 cars per day ranges from
73
$1 million to $3 million.
In many locations, however, the low market price paid for shredded
scrap has restricted the area from which shredders can draw junk auto-bodies.
Although it, too, is restricted by low scrap prices, the practice of flattening
junk autos and delivering them from outlying areas to a centralized shredder
results in some cars being processed without generating as much air pollution
as if they were burned in the open.
Compaction - Compaction, although not a disposal method, has the
potential of reducing on-site refuse volume to a point that large storage areas
are not required and transfer to final disposal at landfills or municipal
incinerators is easier. Compaction devices are now being marketed for
installation in larger apartment complexes. In some instances, these units
have replaced chute-fed incinerators.
Compaction installations are similar to chute-fed incinerator installations.
Normally, refuse is charged by tenants through a door located on each floor of
the building. Refuse builds up to a predetermined level in a receiving hopper,
usually in the basement, then is forced by hydraulic ram into a storage con-
tainer or bag. Compaction of refuse in the storage container is claimed to
be accomplished up to 3 to 1. Recent investigations indicate, however, that
much higher compaction ratios may be obtained.
3-72
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Metal containers with capacities up to two cubic yards have been used.
It has been reported that one container is required for every fifty apartments,
with removal two to fives times per week.
Installed cost of a compactor is reported to be $3500, plus $175 per floor
for the metal chute. Hauling cost of the compacted refuse for a 100-unit
apartment building in one area of the country is $85 per month. Incineration of
the same refuse would cost $50.
Widespread use of compaction units could place a heavy burden on pick-
up and disposal facilities of a municipality and could cause an accumulation of
refuse should scheduled pick up be prevented. Another disadvantage of such a
disposal method is the high cost of installing such units in older buildings.
3.6.3.3 Disposal Methods With Incineration - Incineration, as a means of
volume reduction, may be justified in areas where land for sanitary land-
fill is scarce or hauling costs are prohibitive. That well designed and well
operated equipment be used to minimize the discharge of particulate matter to
the atmosphere is of utmost importance in the use of incinerators.
Emissions of particulate air pollutants from combustion of solid waste,
including open burning, can range from 3 to 28 pounds per ton of refuse,
depending on the degree of combustion and control of emissions. Reduction
of these emissions to the desired level requires either that the incinerator
be designed for control of fly ash or that a separate control system be used.
Table 3-13 summarizes the collection efficiency of various control devices
when applied to incinerators.
3-73
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Open burningThe results of the National Solid Wastes Survey show that
open burning is widespread. Eighty-six percent of the 190 million tons of solid
waste collected in 1967 went into land disposal sites, 75 percent of which re-
j- r*
suited in some form of open burning. The Bureau of Solid Waste Management
of the Environmental Control Administration sees even a higher percentage of
the sites as undesirable as indicated by the following quotation:
"This country has over 12,000 land disposal sites being utilized by
collection services, control of 94 percent of which is unacceptable and
represents disease potential, threat of pollution, and land blight. By no
stretch of the imagination do these sites resemble a sanitary landfill. The
waste management field must face the challenge of studying and evaluating
these sites to determine their suitability for conversion to sanitary landfills
We must develop the necessary plans, finances, and action programs to
convert those sites that can function as a sanitary landfill. In many in-
stances it will be necessary to close and abandon many of these sites.
Local government then must locate and develop new sites for immediate
now and to provide necessary capacities for the increase of the future.
"To eliminate open dumps, and the air pollution that results from
open burning in them, as well as other environmental pollution, may cost
Cf*
as much as $230 million per year for 5 years. This represents about
use
56
3-74
-------
Table 3-13. MAXIMUM DEMONSTRATED COLLECTION EFFICIENCY
OF INCINERATOR CONTROL EQUIPMENT74'75
Collection device
Collection efficiency, percent
Settling chamber
Wetted baffles
Cyclones
Impaction scrubbers (with
pressure drop less than
ten inches of water)
Electrostatic precipitators
Bag filters
35
53
75 to 80
94 to 96
99+
99+
3-75
-------
5 percent more than is currently being spent annually for solid
4. U56
waste management.
Open Top Incinerators A refractory-lined rectangular chamber with a
full, open top and forced overfire air has been used to incinerate a variety of
76
wastes including liquids, solids with high caloric value, general trash, and
municipal refuse. This design, because of its relatively low cost, has been ap-
plied to waste disposal by both municipalities and industries. Tests of a pilot
unit conducted by the National Air Pollution Control Administration have shown
excessive particulate emissions for high-ash materials and for low-ash materi-
als under certain operating conditions. Low emissions were realized for a low-
ash (0. 5 percent by weight) material incinerated under carefully controlled con-
77
ditions. Operation of full-scale units on certain high-Btu low-ash wastes are
being conducted without visible emissions of smoke, but no quantitative test data
are yet available. Before applying this technique, careful consideration should
be given to the ash content and physical characteristics of the waste, and tests
should be conducted on the specific waste. As with all combustion sources,
this type of unit requires control of charging and air flow to prevent the emission
of smoke and excessive fly ash. All installations should be equipped with ap-
propriate instrumentation to ensure operation within allowable air pollution limits.
Additional tests are contemplated to further define significant parameters which
can be used to estimate performance on any waste material.
Conical metal burners Conical metal waste burners are used in the lum-
ber industry to incinerate wood wastes. This single-chamber incinerator
3-76
-------
is not properly designed to minimize atmospheric emissions, and is usually
not operated or maintained properly. Consequently, large amounts of particulate
matter are emitted from such units. Some areas of the country, in fact, have
banned all new construction of these burners. Conical metal burners are not
n n
satisfactory for other types of refuse either.
Domestic IncineratorsDomestic incinerators may include such units as
single-chamber backyard units with no auxiliary fuel to dual chamber incinerators
having a primary burner section followed by an afterburner section.
Many air pollution control agencies have banned installation and use of
backyard incinerators. A few air pollution agencies have in the past prohibited
the installation of some or all types of domestic incinerators because of the
inability to meet various local standards pertaining to emissions of particulates,
organic compounds, or odors. Such action may be due in part to excessive
emissions caused by negligent operation of such units and the fact they can
be operated without using the gas burners.
Commercial and industrial incinerators - Commercial and industrial
incinerators for burning general refuse range in capacity from 50 to several
thousand pounds of refuse per hour. These units may be classified into two
general designs, single- and multiple-chamber incinerators. A single-
chamber unit is so designed that admission, combustion, and exhaust to a stack
take place in one chamber. The multiple-chamber incinerator has separate
chambers for admission and combustion of the solid refuse, mixing and
3-77
-------
further combustion of the fly ash and gaseous emissions, and settling and
collecting of the fly ash. Industrial wastes other than general refuse require
special designs based on characteristics of the particular waste.
Single-chamber incinerators have generally proven inadequate to meet
most emission regulations. Emissions from such units have been reported to
64
be as much as 25 pounds of particulate matter per ton of refuse burned.
Multiple-chamber incinerators, however, when designed, operated, and main-
tained properly, reduce the volume of refuse sufficiently and produce a minimum
of particulate emission. Emissions from such units have been reported to be
as little as 3 pounds per ton of refuse burned. Even well-designed multiple-
chamber incinerators may require a good gas washer to meet more stringent
regulations. The National Air Pollution Control Administration has tentatively
found that scrubbers having at least 1/2 inch HO pressure drop and a water rate
Zj
of 4 gallons per 1, 000 scfm are required for Federal incinerators to meet emis-
79
sion standards for Federal facilities.
To keep particulate emissions to a minimum, design standards for any
QA
incinerator must include means to satisfy the following criteria:
1. Air and fuel must be in proper proportion.
2. Air and fuel must be mixed adequately.
3. Temperature must be sufficient for combustion for both the solid fuel
and gaseous products.
4. Furnace volume must be large enough to provide the retention time
needed for complete combustion.
3-78
-------
5. Furnace proportions must be such that ignition temperatures are
maintained and fly ash entrainment is minimized.
Even an incinerator of proper design must be operated and maintained
properly to minimize particulate emissions. Where charging and operation
cannot be closely supervised, scrubbers and auxiliary burners can minimize
emissions. Periodic cleaning and adjustment of burners can minimize emis-
sions. Periodic cleaning and adjustment of burners, spray nozzles, fans,
and other appurtenant devices are also necessary to minimize emissions.
Initial incinerator cost depends mainly on the capacity of the unit and
01
the degree of air pollution control desired. Figure 3-2 shows typical costs
for incinerators without scrubbers, with low-efficiency scrubbers, and with
high-efficiency scrubbers. Presumably, these costs data are for the approxi-
mate time the information was presented, December 1966. To meet the most
stringent emission standards and to minimize visible emissions and fly ash,
most incinerators must be equipped with scrubbers.
Design criteria and operating practices previously described for general
refuse incinerators should also apply to units burning pathological waste.
Primary factors that affect particulate emissions from pathological incinerators
include:
1. Gas burner rates should be sufficient to maintain at least 1400°F in
secondary chamber.
3-79
-------
2. Burner placement should be such that all waste in primary chamber
is covered by flame from burner.
3. Preheating should be accomplished with secondary burners prior
to charging of waste.
Many air pollution control agencies review on a routine basis all plans
for future incinerator installations to ensure that these units meet emission
standards. Details that are usually checked in such a review include:
1. Plot plans to see if unit is located in a suitable area.
2. Unit capacity to see if it is adequate for the expected daily waste
generation.
3. Gas burner placement and fuel rates.
4. Scrubber water flow rate.
5. Materials of construction for resistance to heat, stress, and
corrosion.
6. Air port sizes.
Recognizing the fact that emissions from incinerators are, to a great
extent, a function of operation, some air pollution control agencies conduct
training courses and publish literature to be used by incinerator operators or
their supervisors. Once aware of the factors influencing atmospheric emis-
sions, it is possible for operators to contribute greatly to the reduction of
particulate emissions by such simple practices as regularly cleaning out the
ash pit or preheating the unit prior to operation.
3-80
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Apartment house incinerators -
Apartment house incinerators are an
important pollutant source in urban
areas of the country. Smoke and fly
ash from these units cause many
complaints.
Emissions are usually higher
than other incineration systems be-
cause of low combustion temperatures
100 500 1000 isoo 2000 and improper air regulation. Adequate
CAPACITY OF INCINERATOR, Ib/hr
igure 3-2. Costs of incinerator at three levels
of control of paniculate emissions.
control of this source in most cases
has not been achieved, although
stricter air pollution regulations are inspiring the application of new control
measures.
The most common apartment house incinerator is the flue-fed or single-
flue, single-chamber model. In this unit refuse is charged down the same
passage that the products of combustion use to leave the unit. Refuse dropped
onto the fuel bed during burning smothers the fire and causes incomplete com-
bustion. Improvements in design have been made to the single-flue, single-
chamber unit. There are now chute fed units that are multiple-chamber
incinerators with separate passages for the refuse and products of combustion.
This design provides improved combustion and air regulation but emissions would
3-81
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still exceed most emission standards. Inherent in the design of flue or chute-
fed models is the high natural draft in the flues of a tall apartment building
which is a major cause of high particulate emissions.
Air pollution agencies have approached the control of these units in
different ways. New York has prohibited the installation of new apartment
house incinerators and has issued specific criteria for upgrading existing units,
Washington, D. C., and Atlanta do not allow flue or chute-fed units to be in-
stalled. Detroit and Philadelphia have set emission standards at a level that
requires efficient collection equipment, usually water scrubbers, on apartment
house incinerators.
In upgrading existing units and designing new units, several techniques
are used to overcome the problems of excessive emissions from apartment
house incinerators. A gate at the base of the charging chute is used to prevent
refuse from entering the incinerator during burning and to prevent the products
of combustion from leaving through the charging flue. This approach is prefer-
able to locking the hopper doors because these locks eventually either fail on
their own or are broken by occupants of the building. For single-flue units, a
bypass or separate flue must be constructed for the products of combustion.
Auxiliary burners are placed in the primary and/or secondary chambers of the
Q O
incinerator to increase burning temperature and improve combustion.
Draft control has been used in New York to reduce entrainment of fuel
bed material in the effluent gas stream. A sensor is placed in the primary
3-82
-------
chamber to monitor draft. When a preset draft level is exceeded a damper
located in the breeching at the incinerator outlet is activated and decreases
the amount of air entering the incinerator.
An important step is the addition of efficient gas scrubbers to the in-
cineration system. Scrubbers designed to increase the velocity of the gases
and contact them with low-velocity water appear to be preferable to spray
nozzle units because plugged nozzles reduce collection efficiency. A final
improvement is the establishment of definite burning periods. Burning cycles
depend on the relative size of the apartment house and incinerator, and are
quite variable. The intent of such cycles is to systematically destroy the
refuse without overloading the incinerator, and to minimize smoldering refuse
by destroying all waste charged during any one cycle. Employment of the
above techniques should reduce emissions to a level of 2 to 6 pounds per ton
of refuse burned.
Municipal incinerators - In 1966, 254 municipal-size incinerators were
in operation in the United States. The average capacity of these units is 300
tons per day. Most installations are old (70 percent were installed before 1960)
and not designed to minimize air pollution.
"It is estimated that approximately $150 million is required to construct
lew incinerators for replacement of existing inadequate incinerators and conical
turners. An additional $75 million is required for air pollution control equip-
56
nent to upgrade or replace existing inadequate incinerators."
3-83
-------
Approximately 8 percent of all municipal solid waste, not including
56
agricultural and industrial waste, is burned in municipal incinerators.
Design criteria for municipal incinerators - Municipal incinerators may
be classified as either batch-fed or continuously fed units. Continuously fed
units are preferable because operating parameters, such as combustion
chamber temperatures that affect particulate emissions, can be closely con-
trolled. Grates must be of proper design to ensure complete burnout of
material. At the same time, however, grates should mix or tumble the refuse
as gently as possible to minimize entrainment of material in the exhaust gas.
Most municipal incinerators in this country are of the refractory-lined
furnace type. Water-wall furnaces are more common in Europe. This type
of unit offers the advantage of steam generation. As a consequence of heat
recovery in the steam generation process, flue gas temperatures are lower
than those of refractory-lined units. Lower flue gas temperatures cause
smaller flue gas volumes, which in turn require smaller, less costly air
pollution control equipment. In addition, water-wall units can be operated with
less excess air, which further reduces stack gas volume.
Air pollution control equipment - Most municipal incinerators in the
United States are equipped with some form of fly ash control system. Generally,
this system consists of a simple baffle-type spray chamber. These spray
chambers prevent hot cinders and large particles from being emitted to the
atmosphere, but they do not effectively control finer material.
3-84
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More efficient collection devices will be required for municipal incinera-
tors to meet reasonable air pollution control codes. The medium pressure drop
(6 inches of water) scrubber and the electrostatic precipitator are two control
devices capable of effective particulate control. No precipitator has yet been
installed on any American municipal incinerator, but several have been in-
stalled and successfully operated in Europe. Several devices with collection
84
efficiencies of over 95 percent are scheduled for new and existing units.
High efficiency scrubbers, in contrast to precipitators, might also control
emissions of potentially odorous and toxic gas.
Cost of municipal incineration and control devices Current costs of
constructing municipal incinerators may range from $6,000 - $13,000 per ton
85
of rated 24 hour capacity. Costs in the low end of the range represent in-
cinerators of relatively simple design with minimal controls, such as a
settling chamber. Costs for incinerators of complex design, equipped with
sophisticated controls such as electrostatic precipitators, would be near the
high end of the range. Between 30 and 40 percent of this cost is usually spent
on operating equipment and the remainder is spent on building and land. Oper-
ating costs (not including plant amortization) range from $4 to $8 per ton of
84
refuse incinerated. Precipitator (95 percent efficiency) cost for two 250-
86
ton-per-day incinerators is reported at approximately $430,000.
3-85
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3. 6.4 Air Pollution Potential From Solid Waste Disposal Methods
r/?
There are approximately 12,000 land disposal sites in this country.
Such sites may be defined as locations, either privately or publicly owned,
on which there is dumping of solid wastes by public or private contractors.
Only 6 percent of these sites may be termed sanitary landfills, in that they
have daily cover, no open burning, and no water pollution problems. On
three-quarters of the remaining 94 percent of the land disposal sites, some
form of open burning is practiced. This type of ultimate disposal accounts
for a large share of the particulate emissions estimated to arise from the
burning of solid wastes.
Some amounts of construction, institutional, industrial and agricultural
waste are also burned. Emissions from field burning to remove weeds or
residue, incineration of wood waste, and burning of car bodies for salvage
can contribute significantly to local and even regional air pollution problems.
In some areas of the country these sources may, in fact, be the greatest cause
of particulate air pollution.
_3. 6. 5 Public Health Service Programs and Assistance in Solid Waste Disposal
With passage of the Solid Waste Act of 1965, the Federal Government
made a commitment to support and assist in a coordinated national effort to
87
solve solid waste problems. The Solid Wastes Program of the Environmental
Control Administration presently supplies technical and financial assistance re-
lating to methods for handling solid wastes. The National Air Pollution Control
3-86
-------
Administration also provides technical assistance on air pollution emissions
and control techniques for solid waste disposal methods. Public Health Service
regional office directors should be contacted in regard to specific services
available. In addition, where problems of solid waste disposal arise in connec-
tion with mining industries, the Solid Waste Research Group of the Bureau of
Mines may also be consulted.
3-87
331-716 0-69-10
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35. Kreichelt, T. E. , Kemnitz, D. A. , and Cuffe, S. T. "Atmospheric
Emissions from the Manufacture of Portland Cement. " U. S. Dept. of
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Control, Cincinnati, Ohio, PHS-Pub-999-AP-17, 1967, 47 pp.
36. Kenline, P. A. and Hales, J. M. "Air Pollution and the Kraft Pulping
Industry. An Annotated Bibliography. " U.S. Dept. of Health, Education,
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1963, 122 pp.
37. "Atmospheric Emissions from Sulfuric Acid Manufacturing Processes."
U.S. Dept. of Health, Education, and Welfare, Div. of Air Pollution,
Cincinnati, Ohio, PHS-Pub-999-AP-13, 1965, 127 pp.
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Education, and Welfare, National Center for Air Pollution Control,
Cincinnati, Ohio, PHS-Pub-999-AP-31, 1967, 103pp.
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pp. 216-228, April 1968.
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on Air Pollution, Washington, D. C. , 1966, pp. 236-241.
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U. S. Steel Corporation, 8th edition, 1964, p. 404.
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Aspects of the Iron and Steel Industry. " U.S. Dept. of Health, Education,
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1963, p. 45.
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Air Pollution Control. " In: Proceedings of the 3rd National Conference
on Air Pollution, Washington, D. C. , 1966, pp. 236-241.
45. Schueneman, J. J. , High, M. D. , and Bye, W. E. "Air Pollution
Aspects of the Iron and Steel Industry. " U.S. Dept. of Health, Education,
and Welfare, Div. of Air Pollution, Cincinnati, Ohio, PHS-Pub-999-AP-l,
1963, p. 67.
3-91
-------
46. Schueneman, J. J. , High, M. D. , and Bye, W. E. "Air Pollution
Aspects of the Iron and Steel Industry. " U.S. Dept. of Health, Education,
and Welfare, Div. of Air Pollution, Cincinnati, Ohio, PHS-Pub-999-AP-l,
1963, p. 68.
47. Schueneman, J. J. , High, M. D. , and Bye, W. E. "Air Pollution
Aspects of the Iron and Steel Industry. " U. S. Dept. of Health, Education,
and Welfare, Div. of Air Pollution, Cincinnati, Ohio, PHS-Pub-999-AP-l,
1963, p. 61.
48. Sterling, M. "Current Status and Future Prospects - Foundry Air
Pollution Control. " In: Proceedings of the 3rd National Conference on
Air Pollution, Washington, D. C. , Dec. 1966, pp. 254-259.
49. Doherty, R. E. "Current Status and Future Prospects - Cement Mill
Air Pollution Control. " In: Proceedings of the 3rd National Conference
on Air Pollution, Washington, D. C. , 1966, pp. 242-249.
50. Doherty, R. E. "Current Status and Future Prospects - Cement Mill
Air Pollution Control. " In: Proceedings of the 3rd National Conference
on Air Pollution, Washington, D. C. , 1966, pp. 242-249.
51. Ingels, R. M. , Shaffer, N. R. , and Daniel son, J. A. "Control of
Asphaltic Concrete Plants in Los Angeles County. " J. Air Pollution
Control Assoc. , H)(l):29-33, Feb. 1960.
52. Brandt, A. D. "Current Status and Future Prospects - Steel Industry
Air Pollution Control. " In: Proceedings of the 3rd National Conference
on Air Pollution, Washington, D. C. , 1966, pp. 236-241.
53. Brandt, A. D. Private communication, June 11, 1968.
54. "Impregnated Fabrics Collect Fluoride Fumes. " Engineering and
Mining, J. , Vol. 160, No. 5, May 1959.
55. "New York City Officials Considering Cocoon for Demolition Dust
Control." Clean Air News, 2_(8): 12-13, March 12, 1968.
56. Black, R. J. , Muhich, A. T. , Klee, A. J. , Hickman, H. L. , Jr., and
Vaughn, R. D. "The National Solid Wastes Survey, an Interim Report."
(Presented at the 1968 Annual Meeting of the Institute of Solid Wastes of
the American Public Works Association, Miami Beach, Florida,
Oct. 24, 1968.)
3-92
-------
57. Prindle, Richard A. "Health Aspects of Solid Waste Disposal. " In:
Proceedings, the Surgeon General's Conference on Solid Waste Manage-
ment, Washington, B.C., Public Health Service, PHS-Pub-1729, 1967,
pp. 15-20.
58. Copp, W. R. "Municipal Inventory. Combustion Engineering, Technical-
Economic Study of Solid Waste Disposal Needs and Practices. " Vol. I,
Nov. 1967, pp. 1-69.
59. Schueller, H. M. "Quantities and Characteristics of Solid Waste. " In:
Elements of Solid Waste Management Training Course Manual, Public
Health Service, Cincinnati, Ohio, March 1968, pp. 1-5.
60. Bremser, L. W. "Solid Waste Disposal Study for the Washington Metro-
politan Area. " In: Proceedings, the Surgeon General's Conference on
Solid Waste Management, Washington, D. C. , Public Health Service,
PHS-Pub-1729, 1967, pp. 25-33.
61. Kaiser, E. R. , Halitsky, J. , Jacobs, M. B. , and McCabe, L. C.
"Performance of a Flue Fed Incinerator. " J. Air Pollution Control
Assoc. , 9_(2):85-91, Aug. 1959.
62. Weston, R. F. "Future Alternatives to Incineration and their Air
Pollution Potential. " In: Proceedings of the 3rd National Conference on
Air Pollution, Washington, D. C. , 1967, pp. 306-308.
63. Seely, R. J. and Loquercio, P. A. "Solid Waste Report for the City of
Chicago. " City of Chicago Dept. of Air Pollution Control, Chicago,
111. , 1966.
64. Mayer, M. "A Compilation of Air Pollutant Emission Factors for
Combustion Processes, Gasoline Evaporation and Selected Industrial
Processes." U.S. Dept. of Health, Education, and Welfare, Div. of
Air Pollution, Cincinnati, Ohio, May 1965, 53 pp.
65. Kaiser, Elmer R. "Refuse Reduction Processes." In: Proceedings,
the Surgeon General's Conference on Solid Waste Management, Washington,
D. C. , U.S. Dept. of Health, Education, and Welfare, National Center for
Occupational and Industrial Health, 1967, pp. 93-104.
66. Sorg, T. J. and Hickman, H. L. "Sanitary Landfill Facts." U.S. Dept.
of Health, Education, and Welfare, National Center for Occupational and
Industrial Health, Washington, D. C. , PHS-Pub-1729, 1968.
3-93
-------
67. Kirsh, J. B. "Sanitary Landfill. " In: Elements of Solid Waste Manage-
ment Training Course Manual, Public Health Service, Cincinnati, Ohio,
1968, pp. 1-4.
68. Sibel, J. T. "Landfill Operations. Combustion Engineering, Technical-
Economic Study of Solid Waste Disposal Needs and Practices. " Vol. 4,
1967, pp. 1-17.
69. Goluecke, C. G. and McGaughey, P. H. "Future Alternatives to In-
cineration and their Air Pollution Potential. " In: Proceedings of the
3rd National Conference on Air Pollution, Washington, D. C. , 1967,
pp. 296-305.
70. Alpiser, Francis M. "Air Pollution from Disposal of Junk Autos. "
Preprint. (Presented at the Annual Meeting of the Air Pollution Control
Association, St. Paul, Minnesota, June 1968).
71. Lieberman, C. "Recovering Scrap Steel for Melting from Automobile
Bodies." U.S. Patent No. 3,320,051, May 16, 1967, 3pp.
72. "An In-Depth Look at Ferrous Scrap. " Magazine of Metals Producing,
March 1966. (Published by Institute of Scrap Iron & Steel).
73. Bennett, K. W. "Scrap Processing Goes Big Time. " The Iron Age,
Aug. 26, 1965, pp. 29-30.
74. Kaiser, Elmer R. "Incinerators to Meet New Air Pollution Standards."
(Presented at Mid-Atlantic Section Meeting of the Air Pollution Control
Association, New York, April 20, 1967).
75. O'Conner, C. and Swinehart, G. "Baghouse Cures Stack Effluent. "
Power Eng. , Vol. 65, pp. 58-59, May 1961.
76. Monroe, E. S. , Jr. "New Developments in Industrial Incineration."
In: Proceedings of 1966 National Incinerator Conference, American
Society of Mechanical Engineers, New York, 1966, pp. 226-230.
77. Burckle, J. O. , Dorsey, J. A., and Riley, B. T. "The Effects of the
Operating Variables and Refuse Types on the Emissions from a Pilot-
Scale Trench Incinerator. " In: Proceedings of 1968 National In-
cinerator Conference, American Society of Mechanical Engineers, New
York, May 5-8, 1968, pp. 34-41.
3-94
-------
78. Kreichelt, Thomas E. "Air Pollution Aspects of Tepee Burners Used
for Disposal of Municipal Refuse. " U.S. Dept. of Health, Education,
and Welfare, Div. of Air Pollution, PHS-Pub-999-AP-2S, 1966, 39pp.
79. Sable ski, J. J. , Knudson, J. C. , Cote, W. A., and Kowalczyk, J. F.
"Development of Incineration Guidelines for Federal Facilities. "
(Presented at the Annual Meeting of the Air Pollution Control Association,
St. Paul, Minnesota, June 23-27, 1968).
80. Williamson, J. E. , Me Knight, R. J. , and Chass, R. L. " Multiple -
Chamber Incinerator Design Standards for Los Angeles County. " Los
Angeles County Air Pollution Control District, Los Angeles, California,
Oct. 1960.
81. Voelker, E. M. "Control of Air Pollution from Industrial and Household
Incinerators. " In: Proceedings of the 3rd National Conference on Air
Pollution, Washington, D. C. , 1967, pp. 332-338.
82. Feuss, James V. and Flower, Franklin B. "The Design of Apartment
House Incinerators - the State of Art. " (Presented at the Annual Meeting
of the Air Pollution Control Association, June 23-27, 1968.)
83. Duprey, R. L. "Compilation of Air Pollutant Emission Factors. " U.S.
Dept. of Health, Education, and Welfare, National Center for Air
Pollution Control, Durham, North Carolina, PHS-Pub-999-AP-42, 1968,
67pp.
84. Bogue, M. DeVon "Municipal Incinerators. " U.S. Public Health Service,
Office of Solid Wastes, 1965.
85. Hickman, H. L. Private communication, Technical Services, Bureau of
Solid Waste Management, Rockville, Maryland, Nov. 1, 1968.
86. Fife, James A. and Boyer, Robert H. , Jr. "What Price Incineration
Air Pollution Control ?" In: Proceedings of 1966 National Incinerator
Conference, American Society of Mechanical Engineers, New York,
1966, pp. 89-96.
87. Vaughan, R. D. "Assistance Available under the Solid Waste Disposal
Act. " In: Proceedings of the Surgeon General's Conference on Solid
Waste Management, Washington, D. C. U.S. Dept. of Health, Education,
and Welfare, National Center for Urban and Industrial Health, 1967,
pp. 155-162.
3-95
-------
4. GAS CLEANING DEVICES
4.1 INTRODUCTION
Gas streams contaminated with particulate matter may be cleaned
before the gas is discharged to the atmosphere. Gas cleaning devices take
advantage of certain physical, chemical, and/or electrical properties of the
particulate matter and gas stream. Selection of a gas cleaning device will
be influenced by the efficiency required, nature of the process gas to be
cleaned, characteristics of the particulate and gas stream, cost of the
device's use, availability of space, and power and water requirements.
Other basic considerations include maintenance, dependability, and waste
disposal. It has been estimated that total expenditures in 1966 of industrial
air pollution control equipment in the United States were about $235 million.
Value of shipments of the industrial gas cleaning equipment industry in 1967
was double the 1963 figure, and the backlog of orders recently nearly equalled
a year's productive output. Undoubtedly legislative pressure and local
pollution control regulations have supplied the impetus for such rapid growth
2
in this industry. Table 4-1 shows an up-to-date list of the types and values
2
of control equipment being sold to various industries.
This chapter discusses the wide array of commercially available gas
cleaning devices and summarizes published operating characteristics, including
4-1
-------
Table 4-1. MANUFACTURERS' SHIPMENTS OF INDUSTRIAL GAS
CLEANING EQUIPMENT BY END USE IN 1967
(thousands of dollars)
Iron and steel
Utilities
Chemicals
c
Rock products
Pulp and paper
Mining and metallurgical
Refinery
All otherd
Exports
Total shipments
Electrostatic
precipitators
5,783
15,506
1,207
2,760
a
a
a
687
a
36,509
Fabric
filters
4,536
a
5,344
3,602
122
1,855
a
4,959
1,081
21,730
Mechanical
collectors
2,300
2,476
3,130
1,038
802
389
a
8,408
a
22,381
Scrubbers
particulate
7,423
a
3,709
1,142
989
825
a
3,901
651
19,229
Scrubbers
gaseous
4,275
a
1,479
a
193
394
a
114
72
6,770
Gas incinerators
and adsorbers
b
a
1,001
a
a
a
282
2,137
79
3,976
Total
shipments
b
24,317
18,481
15,870
8,966
6,753
6,160
4,098
20,206
5,744
110,595
I
to
Not published to avoid disclosure.
Ga-s incinerators and adsorbers purchased by iron and steel companies are included in "all others" category to avoid disclosure.
' "Rock products" includes cement and asbestos plants.
"All other" includes shipments to distributors where end use cannot be identified.
-------
efficiencies, and information that will help determine the gas cleaning devices
suited for a specific application. Information presented includes:
1. Introductory material (definitions and theoretical principles).
2. Equipment description and design (variations, arrangements, and
performance).
3. Typical applications (including efficiency data).
4. Operational factors (power requirements, pressure drops,
temperature limitations, corrosion and maintenance problems,
and waste disposal).
Cost factors for each major type of control device are discussed in Section
6 of this report. Capital, installation, and operating costs are provided for
settling chambers, cyclones, scrubbers, electrostatic precipitators, fabric
filters,and afterburners.
4. 1.1 Preliminary Selection of Equipment
The selection of gas cleaning equipment is far from an exact science and
must be based on particle and carrier gas characteristics, and process,
operating, construction, and economic factors.
Important particle characteristics consist of size distribution, shape,
density, and such physio-chemical properties as hygroscopicity, agglomerating
tendency, corrosiveness, "stickiness", flowability, electrical conductivity,
o
flammability, and toxicity. °
-------
Test methods for determining some of the properties of fine particulate
matter cited above are outlined in the American Society of Mechanical Engineers'
Power Test Code Number 28.
The process factors affecting selection of a gas cleaner are volumetric
flow rate, variability of gas flow, particle concentration, allowable pressure
drop, product quality requirements, and the required collection efficiency.
Required collection efficiency is based on the value of the material being
collected, the nuisance or damage potential of the material, the physical
location of the exhaust, the geographical location (i.e. , the air pollution
susceptibility of the area), and present and future local codes and ordinances.
Ease of maintenance and the need for continuity of operation are
operating factors which should be considered. Important construction factors
include available floor space and headroom and construction material
limitations imposed by the temperature, pressure, and/or corrosiveness of
the exhaust stream. Economic factors consist of installation, operating,
and maintenance costs.
Information on the particle size gradation in the inlet gas stream is
very important in the proper selection of gas cleaning equipment. Particles
larger than 50 microns may be removed in inertial and cyclone separators
and simple, low-energy wet scrubbers. Particles smaller than 50 microns
require either high-efficiency (high-energy) wet scrubbers, fabric filters,
or electrostatic precipitators.
4-4
-------
Wet collectors operate at variable efficiencies directly proportional to the
energy expended and can handle changing effluent flow rates and characteristics.
Disadvantages of wet scrubbers are (I1) scrubber liquor may require treatment.
^2) power cost is high,and (3) a visible plume may be emitted. Fabric filters
more readily permit reuse of the collected material and can collect combustible
and explosive dusts. They do. however, have temperature limitations and are
sensitive to process conditions. Electrostatic precipitators can operate at
relatively high temperatures, have low pressure drop, low power requirements.
and few moving parts. They are. however, sensitive to variable dust loadings
or flow rates and. in some cases, require special safety precautions.
The performance of various gas cleaning devices may differ widely
depending upon the particular application. Grade efficiency curves for selected
gas cleaning devices are shown in Figure -i-1 as an illustration of a method for
5 6
describing collection equipment performance for one application. ' The per-
formance of the various gas cleaning devices shown could differ significantly
lor other applications.
4-5
-------
100
BAG FILTERHOU5E
A ' VENTURI SCRUBBER (6-INCH THROAT, 30-INCH WATER GAIICF)
SPRAY TOWER (22-FOOT DIAMETER) E>
'DRY ELECTROSTATIC PRECIPITATOR (3-SECOND CONTACT TlMF'
/MULTIPLE CYCLONES (12 INCH DIAMETER TUBES)
B < SIMPLE CYCLONE (4-FOOT DIAMETER)
INERTIAL COLLECTOR
10
30 40 50
PARTICLE SIZE, microns
Figure 4-1. Composite grade (fractional) efficiency curves based on test silica dust.
As a further aid in the selection of particulate matter collection equip-
ment, the areas of application of the various cleaning devices are given in
Table 4-2.1 Other areas of application have been summarized at the end of
each equipment section. The reader should refer to those sections and to the
material referenced therein.
-------
Table 4-2. USE OF PARTICULATE COLLECTORS BY INDUSTRY
Industrial
Classification
Utilities and industrial
power plants
Pulp and paper
Rock products
Steel
Process
Coal
Oil
Natural gas
Lignite
Wood and bark
Bagasse
Fluid coke
Kraft
Soda
Lime kiln
Chemical
Dissolver tank vents
Cement
Phosphate
Gypsum
Alumina
Lime
Bauxite
Magnesium oxide
Blast furnace
Open hearth
Basic oxygen
furnace
Electric furnace
Sintering
Coke ovens
Ore roasters
Cupola
Pyrites roaster
Taconite
Hot scarfing
EP
0
0
-
0
+
-
0
0
0
-
-
-
0
0
0
0
0
0
-i-
0
0
0
4~
0
0
0
T
0
-i-
0
MC
0
0
-
0
0
0
T
-
-
-
-
0
0
0
0
0
0
0
+
-
-
-
-
0
-
0
-
0
0
-
FF
_
-
-
-
-
-
-
-
-
-
-
-
0
0
0
0
+
-
-
-
-
-
0
-
-
-
~r
-
-
-
\YS
_
-
-
-
+
-
-
0
0
0
0
-
+
0
0
+
-
-
-
0
+
0
0
-
-
T
0
0
-
+
Other
_
-
-
-
-
-
+
-
-
-
-
+
-
-
-
-
-
-
-
+
+
-
-
-
~r
-
-
-
-
-
4-7
331-716 0-69-11
-------
Table 4-2. USE OF PARTICULATE COLLECTORS BY INDUSTRY (Continued)
Industrial
Classification
Mining and
metallurgical
Miscellaneous
Process
Zinc roaster
Zinc smelter
Copper roaster
Copper reverb.
Copper converter
Lead furnace
Aluminum
Elemental phos.
Ilmenite
Titanium dioxide
Molybdenum
Sulfuric acid
Phosphoric acid
Nitric acid
Ore beneficiation
Refinery catalyst
Coal drying
Coal mill vents
Municipal incin-
erators
Carbon black
Apartment incin-
erators
Spray drying
Machining opera-
tion
Hot coating
Precious metal
Feed and flour
milling
Lumber mills
Wood working
EP
0
0
0
0
0
-
0
0
0
+
+
0
-
-
+
0
-
-
+
+
-
-
-
-
0
-
_
-
MC
0
-
0
-
-
-
-
-
0
-
-
-
-
-
+
0
0
+
0
+
-
0
0
-
-
0
0
0
FF
-
-
-
-
-
0
-
-
-
0
-
-
-
-
+
-
-
0
-
+
-
0
0
-
0
0
_
0
ws
-
-
-
-
-
0
0
-
-
-
-
0
0
0
+
_
-
-
0
-
0
+
+
0
-
_
-
-
Other
_
-
-
-
-
-
+
-
-
-
-
0
o !
0
+
-
-
+
-
-
-
+
0
-
-
-
1
4-J
-------
Table 4-2. USE OF PARTICULATE COLLECTORS BY INDUSTRY (Continued)
KEY
0 = Most common Other -
+ = Not normally used Packed towers
EP = Electrostatic Mist pads
Precipitator Slag filter
MC = Mechanical Centrifugal
Collector exhausters
FF = Fabric Filter Flame incineration
WS = Wet Scrubber Settling chamber
4-9
-------
4.2 SETTLING CHAMBERS
4. 2.1 Introduction
Gravitational settling chambers use the force of gravity to separate dusts
and mists from gas streams. Such collectors are simple in design and opera-
tion, but have low collection efficiency. The principal disadvantages are low
collection efficiency for small particles and large space requirements.
4.2.2 Discussion of Terms
To assist in understanding the operation of settling chambers, the
following terms are discussed:
1. Terminal Settling Velocity. A dust particle falling under the influ-
ence of gravity attains a constant terminal velocity, which is dependent on the
physical properties of the gas through which the particle is falling, as well as
7
the physical properties of the particle, including its size and shape. Terminal
settling velocities in air of spheres of different particle densities were calcu-
7
lated and are presented graphically in Figure 4-2.
2. Pick-Up Velocity. Gas flow velocities in a settling chamber must be
8 9
kept below velocities at which reentrainment or "pick-up" occurs, ' or
collection efficiency will be decreased.
3. Collection Efficiency. Collection efficiency is represented by the
weight fraction of the dust retained in the collector. Theoretical collection
efficiency may be represented by the ratio of particle retention time to theoret-
ical settling time and cannot exceed unity.
4-10
-------
THEORETICAL
SCREEN MESH
EQUIVALENT STANDARD
TYLER SCREEN MESH
u
o
o
z
Z
i
UJ
I-
102
10°
10-1
10-2
in-3
in-*
n C
io-6
§ § S
0 m 1M
1 1
1
/.
\n
m
Jj
f/<
*+
P
-J
^
/
7
?
-i
ft
/
r
F
t
i_
//
r ''
j j
/'(
f/
/!'
^"
r^
--
i
'A
in
iO 'T r\j
<^
<~
f
/
w
f/ A
' r /
1' //
- i -/-
17=
1
J
cV
#
ulk or apparent) specific gravity of partic es-'
e ative to water at 4° C. "
?. Stokes Cunning ham correction factor s
ncluded for fine partic es settling in air.
3. Physica properties used:
luid Temp. Viscosity Density :
°F centipoise Ibmass/rt^
Mr 70 0.0181 0.0749
10
100
1,000 10,0
PARTICLE DIAMETER, microns
Figure 4-2. Terminal velocities of spherical
in air. (Adopted from reference 7)
4-11
-------
4. 2. 3 Design Considerations
A gravitational settling chamber consists essentially of a chamber in
which the velocity of the carrier gas is decreased so that particles in the gas
settle out by gravity. Velocity of a gas is reduced by expanding the ducting
into a chamber of suitable dimensions so that a low gas velocity is obtained.
The settling chamber may consist of a simple balloon duct (Figure 4-3),
an expansion chamber with dust hopper (Figure 4-4), or dust settling chamber
(Figure 4-5).
The multiple-tray settling chamber
(Figure 4-6) represents one of the
first attempts to increase collection
efficiency by reducing the vertical
Figure 4-3. Balloon duct.
settling distance (time) by using
multiple shelving. Vertical distance between shelves may be as little as 1 inch.
The gas must be uniformly distributed laterally upon entering the chamber;
verticle distribution is not critical. Uniform distribution is achieved by the
use of gradual transitions, guide vanes, distributor screens, or perforated
plates.
Because the settling rate of dust decreases with increasing turbulence of
the gas, the velocity of the gas stream is usually kept as low as possible. For
practical purposes, the velocity must not be so great that settled particles are
reentrained, or so low that equipment size becomes excessive. Gas velocities
are normally from 1 to 10 feet per second.
4-12
-------
Figure 4-4. Baffled expansion chamber with dust hopper.
In practice, gravitational settling velocities used in design must be based
on experience or on tests conducted under actual conditions, because terminal
settling velocity may be influenced by such factors as agglomeration and
electrostatic charge.
4.2.4 Typical Applications
Settling chambers are usually installed as pre-cleaners to remove large
particles and agglomerated particles, which can clog small-diameter cyclones
4-13
-------
INLET
AIR PIPE
BAFFLE
Figure 4-5. Dust settling chamber.
-. C
3-
£
Figure 4-6. Multiple-tray dust collector.
and other dust cleaning equipment. Because of space considerations, dust
H
chambers are usually limited to particles larger than 43 microns (325 mesh).
Dust settling chambers are most frequently used on natural draft exhaus-
from kilns and furnaces because of their low pressure drop and simplicity of
design. Other areas of application are in cotton gin operations and alfalfa
feed mills.
4-14
-------
4.3 DRY CENTRIFUGAL COLLECTORS
4.3.1 Introduction
Dry centrifugal collectors are gas cleaning devices that utilize the
centrifugal force created by a spinning gas stream to separate particulate
matter from the carrier gas. Spinning motion is imparted to the carrier gas
by a tangential gas inlet, vanes, or a fan. The dust particles, by virtue of
their inertia, move outward to the separator wall, from which they travel to
12
a receiver.
Three important forces that act on individual dust particles during the
separation process are gravitational, centrifugal, and frictional drag. The
force of gravity (F ), which causes the particulate matter to settle, is equal
&
to the product of the particulate mass (M ) and acceleration caused by gravity
(G).
F = M X G
g P
The major force causing the separation of particulate matter in a
cyclone separator is the centrifugal (radial) force caused by a uniform change
in linear velocity caused by rotation. The centrifugal force (F ) is equal to
the product of the particulate mass (M ) and centrifugal acceleration
(V2/R).13'14
P
F = M x V 2/R
c p p
Where V is the particle velocitj^ and R is the radius of motion (curvature).
P
4-15
-------
The ratio of centrifugal force to the force of gravity is often called the
15
separation factor (S):
S = F /F = V 2/RG
eg p
In practice, S varies from 5 for large-diameter, low-resistance cyclones to
16
2500 for small-diameter, high-resistance units.
The frictional drag on a dust particle is caused by the relative motion
of the particle and gas, and acts to oppose the centrifugal force on the particle.
The frictional drag (F ) is directly proportional to the product of (C ), a drag
coefficient, the projected cross-sectional area of the particle (A ), particle
density (p), the square of the particle velocity relative to the gas stream
o
(V ), and an inverse function of the acceleration due to gravity G.
Ff - (Cf)(A )(p)(Vr2)/2G
P
The gravitational, radial, and frictional forces combine to determine the
path of the particle and collection efficiency.
4.3.2 Types of Centrifugal Collectors
Centrifugal collectors, commonly called cyclones, are made in a wide
variety of designs, which generally fall in the following categories:
1. Conventional reverse-flow cyclones
a. Tangential inlet.
b. Axial inlet.
2. Straight-through-How cyclones.
3. Impeller collectors.
4-16
-------
Figure 4-7 shows a typical cyclone of conventional reverse-flow design with a
tangential inlet. Dust laden gas enters the tangential inlet and flows in a
helical vortex path that reverses at the base of the cyclone to form an inner
cone. Dust particles are forced to the wall by centrifugal action and drop to
the bottom of the cyclone. There, dust must be removed without disturbing
the vortex of gas flow in the cyclone. Any disruption of the gas stream reduces
collection efficiency and causes particle reentrainment in the gas stream.
Tangential inlet cyclones are categorized as either high-efficiency or
high-throughput collectors. The high-efficiency design features a narrow gas
inlet which enhances collection because of the shorter radial settling distance
and large cross-sectional area between the wall and the dust-laden vortex.
These features are typical of many small diameter cyclones. The high-
throughput cyclone sacrifices efficiency for volume flow rate and is typical of
larger-diameter cyclones.
Although most cyclones use a cone to reverse the gas direction and
to deliver the collected dust to a central point for removal, a simple cylinder
can be used. Because the cylinder requires a greater axial distance than the
cone and thereby adds height and weight to the collector, it is not commonly
used.
The axial inlet cyclone is shown in Figure 4-8. Like the tangential
inlet cyclone, both the efficiency and pressure drop of axial inlet units are
affected by the dimensions of the gas inlet.
4-17
-------
CLEANED GAS
I
I1
00
ZONE OF INLET
INTERFERENCE
TOP VIEW
INNER
VORTEX
GAS
INLET
SIDE VIEW
OUTER
VORTEX
GAS OUTLET
BODY
INNER
CYLINDER
(TUBULAR
GUARD)
OUTER
VORTEX
INNER
VORTEX
CORE
DUST OUTLET
-DUST-LADEN GAS
Figure 4-7. Conventional reverse-flow cyclone.
Figure 4-8. Axial inlet cyclone.
-------
In cyclones with straight-through flow (Figure 4-9), particulate matter is
collected around the periphery of the base and is bled off to a secondary collec-
tor that may be a cyclone or dust settling chamber. This type of cyclone is
used frequently as a fly ash collector and as a precleaner (skimmer) for other
types of dust cleaning equipment. The chief advantages of this design are low
pressure drop and high gas handling capacity.
In the impeller collector (Figure 4-10), the particulate-laden gas enters
the throat of the impeller and passes through a specially shaped fan blade where
the dust is thrown into an annular slot leading to the collection hopper.
The principal advantage of this unit is its compactness, which may be
of concern in a plant requiring a large number of collectors. The major
limitation is a tendency toward plugging and rotor imbalance from the buildup
of solids on the rotating impeller. Temperature limitations also exist because
of the use of bearings and seals in the device.
4.3.3 Design
High-efficiency, dry centrifugal collectors require that the separation
factor be high, and the number of gas revolutions large, and that collected dust
be removed to avoid reentrainment. Cyclone dimensional factors, gas
15
characteristics, and dust properties affect dust collection.
Collection efficiency increases with:
1. dust particle size,
2. particle density,
4-19
-------
TOP VIEW
SWIRL VANES
SIDE VIEW
PURGE
DEFLECTOR RING
Figure 4-9. Straight-through-flow cyclone.
(Courtesy of the Americon Petroleum In-
stitute)
4-20
-------
Figure 4-10. Dynamic cyclone showing method by which dust is dynamically
precipitated and delivered to the storage hopper.
(Courfesy of American' Air Filter Company)
3. inlet gas velocity,
4, cyclone body length,
5. number of gas revolutions,
6. smoothness of cyclone wall.
Collection efficiency decreases with increased:
1. gas viscosity,
2. cyclone diameter,
3. gas outlet duct diameter,
4. gas inlet area.
4-21
-------
Cyclone efficiencies are commonly classified as low, medium, and high,
corresponding to weight collection efficiency ranges of 50 to 80, 80 to 95, and
14
95 to 99 percent, respectively. A given cyclone design can fall into more
than one class, depending upon the mode of operation and the particle size being
collected. For example, a cyclone nominally considered a high-efficiency
cyclone could operate in the low collection efficiency range if it were used on a
gas stream containing a significant quantity of submicron particles.
In addition to the overall collection efficiency, based on the weight of
entrained particulate entering and leaving the collector, performance is also
related to cut size. Generally, cut size is defined as the particle diameter
collected with 50 percent efficiency on a weight basis.
Particle cut size may be estimated from the Rozin, Rammler, and
Intelmann formula:
Dpc
where:
D = diameter of particle collected with 50 percent efficiency,
pc
- gas viscosity,
b - width of cyclone inlet,
N --- number of effective turns within the cyclone,
4-22
-------
V = inlet gas velocity,
i
p = density of the particulate matter, and
g = density of the gas.
Well-designed, large-diameter, conventional cyclones may be expected
to provide high collection efficiency for particles from 40 to 50 microns and
typically have cut sizes of S microns. High-efficiency cyclones having
diameters of less than 1 foot operate efficiently on particles of 15 to 20 microns
in size and have cut sizes of 3 microns. Typical efficiencies for various
particle size ranges are shown in Table 4-3.
Collection efficiency of small-diameter cyclones will be low if much of
the suspended material is smaller than 5 microns. In special cases in which
the dust shows a high degree of agglomeration or high dust concentrations are
involved (over 100 grains per cubic foot), cyclones will remove dust particles
smaller than 5 microns in diameter. The size of the agglomerates is many
times larger than the original particles. Efficiencies of as high as 9S percent
have been attained on agglomerated dusts having original particle sizes of
from 0.1 to 2.0 microns.
Factors that commonly cause a reduction in cyclone collection efficiency
include infiltration of air at the bottom of the cyclone and the buildup of dust
on the cyclone walls. A variety of dust removal methods is available (Figure
4-11). The buildup of dust may be reduced by means of vibrators and flexible
IS
rubber cones. Special valves may be used to discharge dust without
admitting air.
-------
Table 4-3. RELATIONSHIP BETWEEN PARTICLE SIZE RANGE
AND CYCLONE EFFICIENCY RANGE14
Particle size range,
microns
Conventional
cyclone efficiency
High
cyclone efficiency
Less than 5
5 to 20
15 to 50
Greater than 40
Low
Medium
High
Low
Medium
High
High
4-24
-------
REMOVABLE
CONNECTION
DOWNSPOUT
FROM
CYCLONE
MANUAL
SLIDE GATE
CLOSED
DRUM
SIMPLE CLOSED DRUM
PERIODIC DUMP
DOWNSPOUT
FROM
CYCLONE
,_, MOTOR-
ED OPERATED
VALVE
MOTOR-OPERATED
VALVE
DOWNSPOUT
FROM
CYCLONE
DUST COVER
\
DUST
BIN '
>*SCOUNTER
WEIGHT
AUTOMATIC
FLAP
VALVES
DOWNSPOUT
FROM
CYCLONE
MECHANICALLY
OPERATED
SPHERICAL
SEGMENT
VALVES
OUT OF PHASE
TO DUST
SPHERICAL SEGMENT VALVES
FOR HIGH-PRESSURE DIFFERENTIAL
AUTOMATIC FLAP VALVES
DOWNSPOUT
* FROM
" CYCLONE
TO DUST BIN'
I
CHOKE DISCHARGE SCREW FEEDER
SPRING-LOADED
CHOKE ON
SCREW
DISCHARGE
Figure 4-11. Various types of cyclone dust discharge.
(Courtesy of the American Petroleum Institute)
4-25
-------
4.3.3. 1 Operating Pressure Drop - The pressure drop across a cyclone
depends on a number of variables, but usually ranges from 1 to 8 inches of
14
water. Efficiency increases with increasing inlet velocity, but at a lower
rate than that at which the pressure drop increases. For a given cyclone and
dust combination, an optimum velocity exists, beyond which turbulence increases
more rapidly than separation efficiency, and efficiency decreases.
Pressure drop in a cyclone is due to both frictional and dynamic energy
losses, which are interdependent. Frictional losses are determined by cyclone
surface roughness, gas velocity, and the physical properties of the gas and
aerosol. Dynamic energy loss, on the other hand, is caused by the energy
stored in the high-velocity rotating centrifugal gas stream. Part of this energy
is lost in the rotating gas leaving the cyclone.
Internal surface roughness can cause an increase in frictional pressure
drop, and result in a decrease in overall pressure drop by causing a decrease
in rotational gas velocity (dynamic pressure loss) along the outer circumference
of the cyclone, with a resultant decrease in collection efficiency.
To lower the pressure drop through a given collector, either a reduction
of the rotational velocity (dynamic pressure loss) of the clean exit gas or re-
duction of internal rotational energy (dynamic pressure gain) is used. Pressure
recovery from the exit gas may be accomplished by the use of deflection cones,
baffles, inverted cones, vanes, or drums and scrolls, but usually at the ex-
pense of reduced collection efficiency. Pressure reduction values reported in
4-26
-------
the literature vary from 10 to 25 percent of the total pressure drop across
14
the cyclone.
Pressure reduction may also lie accomplished by the use of inlet vanes
which reduce pressure drop and rotational velocity, and hence collection
efficiency. Vanes arc used when gas handling capacity is to he increased and/
or when normal collection efficiency is so high that loss in efficiency is
insignificant.
In the impeller collector, pressure drop and collection efficiency may be
increased by restricting the gas outlet. Pressure drop may be as low as 1/2
inch of water, and pressure gains may even be realized with some units because
of the pumping action of the motor-driven impeller.
4.:i.o.2 Dust Loading - A cyclone can lie designed to handle practically any
amount of material that can be moved by gas flow In general, cyclone
efficiency increases with increasing dust load. Since these characteristics
are not possessed by other types of collectors with inherently higher efficiencies
cyclones are frequently used as preclcaners where dust loadings are too high
for the final collector.
Because cyclone efficiencies decrease with decreasing dust load and
other types of collectors can operate efficiently at lower dust loadings, cyclones
are usually used (1) for dust loadings of more than 10 grains per cubic foot,
(2) for coarse or easily flocculated dust loadings of less than 10 grains per
cubic foot, or (3) if such factors as high temperature and corrosion exert an
overriding influence.
4-27
-------
4.
Other Design Considerations - Cyclones may be operated in parallel
as shown in Figures 4-12 and 4-13. In both configurations, gas distribution
becomes critical and collection efficiency is usually lower than the corresponding
single-unit efficiency, even in well-designed systems.
Figure 4-12. Cyclones arranged in parallel.
Series operation is sometimes justified if the dust is subjected to
fragmentation and deflocculation as a result of bouncing within the cyclone, if
large particles must be removed to prevent clogging, if abrasion is a problem,
or if the primary cyclone loses efficiency. In these cases, the primary cyclone
is usually of large-diameter, low-pressure-drop design followed by progres-
sively smaller-diameter cyclones, each with increased efficiency and pressure
drop.
Erosion effects increase exponentially with increasing gas velocity.
Maximum erosion occurs at an impingement angle of from 20 to 30 degrees,
and is approximately twice the erosion occurring at 90 degrees.1 The effects of
4-28
-------
erosion may be minimized by the use
of special alloys, abrasion-resistant
refractories, thicker walls, rubber
lining, and by reducing gas velocity.
4. 3.4 Typical Applications
Cyclones are frequently used
in both primary and secondary gas
cleaning operations. They are used in
feed and grain mills, cotton gins, ferti-
lizer plants, petroleum refineries,
asphalt mixing plants, metallurgical
operations, and chemicals, plastics,
20, 21
and metals manufacture.
Cyclones designed for the collec-
Figure 4-13. Cyclones arranged in parallel, tion of mist are sometimes modified by
(Courtesy of Western Pre c I p itot i on Division)
placing an outer skirt on the gas outlet to prevent liquid carryover. Repre-
sentative performance and applications of centrifugal collectors are listed in
99
Tables 4-4 and 4-5.
4-29
-------
Table 4-4. REPRESENTATIVE PERFORMANCE OF CENTRIFUGAL COLLECTORS
20
Collector
type
Series cyclone
Cyclone
Cyclone
Cyclone
Cyclone
Impeller
collectors
Impeller
collectors
Process
Fluid- catalytic
cracking
Abrasive Cleaning
Drying
Grinding
Planing mill
Grinding
Rubber dusting
Material
Catalyst
Talc
Sand and Gravel
Aluminum
Wood
Iron scale
Zinc stearate
Airflow,
ft3/min
40,000
2,300
12,300
2,400
3,100
11,800
3,300
Pressure drop,
in. H20
High
0.33
1.9
1.2
3.7
4.7
9.0
Efficiency,
wt %
99.98
93.0
86.9
89.0
97.0
56.3
88. 0
Inlet load,
gr/ft3
2800
2.2
38.0
0.7
0.1
0.15
0.6
Inlet mass
median size, |j.
37.0
8.2a
3.2b
0.7
I
CO
o
Outlet mass median size = 3.2 microns
Outlet mass median size = 2.5 microns
-------
Table 4-5. APPLICATIONS OF CENTRIFUGAL COLLECTORS
Operation or process
Crushing, pulverizing, mixing,
screening
Alfalfa feed mill
Barley feed mill
Wheat air cleaner
Drying, baking
Catalyst regenerator (petroleum)
Detergent powder spray drier
Orange pulp feed drier
Sand drying kiln
Sand and gravel drying
Stone drying kiln
Mixing fluids
Asphalt mixing
Bituminous concrete mixing
Polishing, buffing, grinding,
chipping
Grinding (aluminum)
Grinding (iron)
Grinding (machine shop)
Surface coating
Rubber dusting
Surface treatment - physical
Abrasive cleaning
Abrasive stick trimming and
shaping
Casting cleaning with metal
shot, sandblasting and tumbling
Foundry tumbling
Truing and shaping abrasive
products
Woodworking, including plastics
rubber, paper board
Mill planing
Air contaminant
Alfalfa dust
Barley flour dust
Chaff
Catalyst dust
Detergent powder
Pulp dust
Silica dust
Silica dust
Silica dust
Sand and gravel dust
Sand and stone dust
Aluminum dust
Iron scale and sand
Dust
Fluffy zinc stearate
Talc dust
Silicon carbide and
alumina dust
Metallic and silica dust
Dust
Silicon carbide and
alumina dust
Wood dust and chips
Type of air
cleaning
equipment
Cyclone, settling
chamber
Cyclone
Cyclone
Cyclone, ESP
Cyclone
Cyclone
Cyclone
Inertial collector
Cyclone
Cyclone
Cyclone, scrubber
Cyclone
Cyclone
Impeller collector
Impeller collector
Cyclone
2 parallel cyclones
Impeller collector
Impeller collector
Cyclone
Cyclone
Collector
efficiency,
wt %
85
85
85
95
85
85
78
50
86
50-86
95
89
56
91
78-88
93
51
97-99+
99
58
97
Reference
23
23
23
23
23
23
24
25
24
24
22
26
25
27
26
26
24
27
27
24
26
4-31
-------
4.4 WET COLLECTORS AND MIST ELIMINATORS
4.4.1 Introduction
Wet collectors use a liquid, usually water, in the separation process
either to remove particulate matter directly from the gas stream by contact
or to increase collection efficiency by preventing reentrainment.
4.4.1.1 Collection Theory - Wet collectors increase particle removal efficiency
by two mechanisms: (1) fine particles are "conditioned" so that their effective
size is increased, enabling them to be collected more easily and (2) re-
entrainment of the collected particles is minimized by trapping them in a
O O OQ
liquid film and washing them away. '
The effective size of the particle may be increased by promoting con-
densation on fine particles, which act as nuclei when the vapor passes through
its dew point. Condensation can remove only a relatively small amount of
dust because the amount of condensation required to remove high concentrations
is usually greater than can be readily achieved.
Forced conditioning or trapping of dust particles on liquid droplets is
usually accomplished by impact using inertial forces. Wetting agents do not
significantly increase collection efficiency, but they do help to prevent re-
entrainment of collected dusts that are not easily wetted by water.30 Solubility
of the particle in the droplet is usually not a factor in increasing collection
effectiveness.
4-32
-------
The principal mechanisms by which participate matter is brought into
29
contact with liquid droplets are:
1. Interception. Interception occurs when particles are carried by
a gas in streamlines around an obstacle at distances of less than the
radius of the particle.
2. Gravitational Force. Gravitational force causes a particle, as
it passes an obstacle, to fall from the streamline and settle on the
surface of the obstacle.
3. Impingement. Impingement occurs when an object, placed in
the path of a particle-laden gas stream, causes the gas to flow
around the obstacle. Larger particles, however, tend to continue
in a straight path because of inertia and may impinge on the obstacle
and be collected. (The impingement target efficiency is represented
by the ratio of the cross-sectional area of the liquid droplets to the
area of the gas stream cleared of particles.)
4. Diffusion. Diffusion results from molecular collisions and,
except for submicron particles, plays little part in separation of
particles from a gas stream.
5. Electrostatic Forces. Electrostatic forces result when particles
and liquid droplets become electrically charged. An electrical charge
may be induced by flame ionization or friction, or by the presence of
charged matter. Electrostatic forces may affect collection
efficiency significantly.
4-33
-------
6. Thermal Gradients. Thermal gradients are important to the
removal of matter from a particle-laden gas stream because parti-
culate matter will move from a hot area to a cold area. The motion
is caused by unequal gas molecular collision energy on the surfaces
of the hot and cold sides of the particle, and is directly proportional
to the temperature gradient.
4.4.1.2 Efficiency - Efficiencies of wet-scrubbing devices are compared on
31
the basis of "contacting power" and the "transfer unit. " Contacting power
is that portion of useful energy expended in producing contact of the particulate
matter with the scrubbing liquid, as well as in producing turbulence and mixing
in the scrubber device. The contacting power represents the kinetic energy or
pressure head loss across the scrubber, kinetic energy or pressure head drop
of the scrubbing liquid, and other forms of energy dissipated in the gas stream,
such as sonic energy or energy supplied by a mechanical rotor.
The transfer unit, which is expressed as the numerical value of the
natural logarithm of the reciprocal of the fraction of the dust passing through
the scrubber, is a measure of the difficulty of separation of the particulate
matter.
Dust collection efficiency is believed by some investigators to be directly
related to contacting power and the properties of the aerosol and to have litte
4-34
-------
31
relationship to scrubber design and geometry. Others believe design details
are important in the effort to achieve maximum collection efficiency for a
given pressure drop.
Gas cleaning equipment is usually selected on the basis of required col-
32
lection efficiency. There are other factors such as gas temperature and
humidity and dust stickiness and abrasiveness that may exert an overriding
influence on the final choice. In the following discussion principal design
features of the various groups of wet collectors are reviewed from the point
of view of general suitability under different operating conditions.
In general, particle size distribution and operating conditions will de-
termine collection efficiencies, which, in turn, will determine power require-
ments for a given unit.
4.4.2 Equipment Description and Design
Collection efficiencies, operating pressure drop, water requirements,
and other operating characteristics reported herein were obtained from
manufacturers' equipment bulletins and other literature sources.
4.4.2.1 Spray Chamber - The simplest type of wet scrubber is a round or
rectangular spray chamber into which water is introduced by means of spray
. 33
nozzles.
4-35
-------
When spray chambers are used to remove coarse particles from hot
gases, they perform the additional functions of gas cooling and humidification.
Spray chambers also effect preliminary conditioning of the particulate matter
by causing condensation of moisture on particles, thus increasing collection
efficiency by increasing the size of the particles.
The principal three configurations in a spray chamber are cocurrent
34
flow, countercurrent flow, and cross now .
In cocurrent flow, both the spray droplets and the gas containing par-
ticulate matter flow through the spray chamber in the same direction. The
relative velocity of the water droplet and gas stream causing effective
collision and capture of the particulate matter is at a minimum, as is col-
lection efficiency. Part of the kinetic energy of the spray droplets is expended
in inducing gas circulation and motion within the scrubber.
Countercurrent flow occurs when the liquid and gas flow in opposite
directions, as in a spray tower in which the liquid is introduced in the top of
the tower and falls against the rising gas stream. The relative velocity of the
liquid droplets and particulate matter in the gas stream is at a maximum, as
is collection efficiency.
In cross flow operation, the liquid is introduced at right angles to the
direction of gas flow and falls across the gas stream. The relative velocity
of the particulate and liquid droplet and the impaction efficiency lie between
the cross flow and countercurrent flow methods of operation.
4-36
-------
For a given spray chamber design, mixed flow usually occurs because of
turbulence, liquid droplet inertia, and gravitational force. Liquid droplets
travel in the direction of the liquid stream until inertial forces are overcome
by air resistance. Large droplets settle under the influence of gravity while
smaller droplets may be swept along with the gas stream.
Liquid droplets and particulate matter may be separated from the gas
stream by gravitational settling, impaction on baffles, filtration through
shallow packed beds, or by cyclonic action.
Spray chambers are used in exhaust systems for light dust cleaning,
electroplating fume control, and preconditioning dust from acid phosphate
34
fertilizers, as well as for providing a final cleanup of exhaust gases from
8
the recovery furnaces in the kraft pulp manufacturing process.
33
Figure 4-14 shows a spray system installed in the base of a stack.
When the system is properly adjusted and operated, 60 to 80 percent of the
Q /?
solids entering the spray zone may be collected during soot-blowing operations.
Approximately 1/2 gallon of liquid per minute per square foot of stack cross
sectional area is required.
The smokestack soot wet-out surface area may also be increased by
packing the smokestack (Figure 4-14). The pieces of packing are usually
stacked and of large diameter to minimize pressure drop and fouling of the bed.
Extra draft fan capacity must be available to make up for the decrease in draft
caused by lower flue gas temperature and by packing. The bed must be cleaned
periodically by flooding with water.
4-37
-------
FULLJET NOZZLE
CO
00
16 FULLJET NOZZLES.
13 REQUIRED IN TWOBANKS.
MATERIAL TYPE 303 STAIN-
LESS STEEL. PRESSURE
DROP 58 TO 62 p s i
rNOTE: NOZZLES TO PITCH
10° TOWARDCENTER
OF STACK
8 FULLJET NOZZLES.
26 REQUIRED IN FOUR
BANKS. MATERIAL TYPE
303 STAINLESS STEEL.
PRESSURE DROP 55 TO
65 p s i
NOTE: NOZZLES TO PITCH
TOWARDCENTER
OF STACK
I
SECTION A-A
FULLJET NOZZLE
INLET PIPE
SECTION B-B
EXPECTED VARIATION OF LIQUID LOAD
PER SQUARE FEET A PPROX IMATEL Y 10%
PACKED STACK
UNPACKED STACK
Figure 4-14. Arrangement of nozzles in smoke stack spray system.
(Courtesy of Sproying Systems Company)
-------
4 4.2.2 Gravity Spray Towers - One of the simplest types of wet scrubbers
is the gravity spray tower. Liquid droplets, produced by either spray nozzles
or atomizers, fall downward through a countercurrent rising gas stream con-
taining dust particles. To avoid spray droplet entrainment and carryover, the
terminal settling velocity of the spray droplets must be greater than the velocity
of the rising gas stream. In practice, the vertical gas velocity usually ranges
from 2 to 5 feet per second. For higher velocities, a mist eliminator must be
used in the top of the tower.
Collection impingement target efficiency in a gravity spray tower is in-
fluenced by the difference between the free-falling velocity of these particles
and the velocity of the rising gas stream. Droplet collection efficiency increases
with decreasing droplet size and increasing relative velocity. In a gravitational
settling chamber these two conditions are mutually exclusive. Hence, there is
37
an optimum droplet size for a maximum collection efficiency. In practice,
this optimum size is from 500 to 1000 microns.
Spray towers are often used as precoolers where large quantities of gas
are involved. Operating characteristics include low pressure drop (usually
less than 1 inch of water, exclusive of mist eliminator section and gas dis-
tribution plate), ability to handle spray liquid having a high solid content (us-
ing water recirculation because of large spray nozzle clearance and spray drop-
let size), and moderate liquid requirements (from 5 to 20 gallons per 1000 cfm).
Their chief disadvantages are low scrubbing efficiencies for dust particles in
4-39
331-716 0-69-13
-------
the 1- to 2-micron range and large space requirements. Spray towers are
usually limited to the collection of particles of 10 microns or larger.
33
Figure 4-15 shows a typical spray tower layout. Gas entering the
base of the spray tower passes through inlet conditioning sprays, through a
distribution plate, through one or more banks of spray nozzles, and through a
mist eliminator section. The mist eliminator is usually necessary in a tower
operating at gas velocities of over 6 feet per second.
The base gas distributor plate may consist of a perforated plate with
uniform hole distribution or a support plate covered with from 6 to 12 inches of
tower packing.
4.4.2.3 Centrifugal Spray Scrubbers - The efficiency of collection of
particles smaller than those recovered in a gravitational spray tower can be
improved by increasing the relative velocity of the droplets and gas stream.
This may be achieved by using the centrifugal force of a spinning gas stream.
Centrifugal spray scrubbers are of two types. In the first type the
spinning motion is imparted to the gas stream by a tangential entry such as
shown in Figure 4-16a. The principal benefit is derived from the wetted walls,
which prevent reentrainment of separated material. Best collection is obtained
by spraying countercurrently to gas flow in the inlet duct at water rates of from
5 to 15 gallons per 1000 cubic feet of gas and at pressure drops in excess of
37
3 inches of water. Figure 4-16b shows this principle employed with a
tangential base gas inlet. The liquid spray is directed outward from sprays
4-40
-------
GAS IN
/ \/\
/v\
/\ \
Figure 4-15. Typical layout for spray tower.
(Courtesy of Spraying Systems Company)
-MIST ELIMINATOR
GAS DISTRIBUTOR PLATE
4-41
-------
DUSTY
GAS "
CLEANED GAS
f ANTI-CARRYOVER BAFFLE
SPRAY RING
"WATER SUPPLY
CLEAN GAS OUT
a. LARGE-DIAMETER IRRIGATED CYCLONE
CLEAN GAS
OUT
TOWER NOZZLES,
DIRECTED
.CROSS FLOW
RECTANGULAR
-INLET
FRESH WATER
SUPPLY
FLUSHING JETS
DIRECTED
DOWNWARD
WASTE OUT
c. CYCLONIC SPRAY SCRUBBER.
(Courtesy of Buffolo Forge Compony)
GAS IN
CORE BUSTER DISK
SPRAY MANIFOLD
DAMPER
WATER WATER
OUT IN
b. PEASE ANTHONY CYCLONIC SCRUBBER
{Courtesy of Chemicol Construction Corporotion)
SEPARATOR
WATER OUT
d. MULTI-WASH SCRUBBER.
(Courtesy of Cloude B. Schneibl* Compony)
Figure 4-16. Centrifugal spray scrubbers.
4-42
-------
set in a central pipe. An unsprayed section above the nozzles is provided so
that the liquid droplets containing the collected particles will have time to reach
the walls of the chamber before coming into contact with the gas stream.
In the scrubber design illustrated in Figure 4-16c water is sprayed
tangentially inward from the wall as an aid in imparting centrifugal motion to
the gas stream. The scrubbing liquid is introduced through nozzles at a pres-
sure of 400 pounds per square inch (gauge).
Water requirements are approximately 5 gallons per 1000 cubic feet
of gas. Operating pressure drop ranges from 1.3 to 2.3 inches of water with
O Q
removal efficiencies as high as 96 percent for 2- to 3-micron particles.
In the second design, (Figure 4-16d) the rotating motion is given to the
gas stream by fixed vanes and impellers, and the scrubbing liquid is introduced
39
centrally either as a spray or liquid stream.
This type of scrubber is used as a final cleanup after spray dryers,
calciners, coolers, crushers, classifiers, and cupolas.
4.4.2.4 Impingement Plate Scrubbers - Impingement plate scrubbers,
shown in Figure 4-17a, consist of a tower equipped with one or more impinge-
37
ment stages, mist removal baffles, and spray chambers. The impingement
stage (Figure 4-17b) consists of a perforated plate that has from 600 to 3000
holes per square foot and a set of impingement baffles so arranged that a baf-
fle is located directly above each hole. The perforated plate is equipped with
a weir to control the level of scrubbing liquid on the plate. The liquid flows
over the plate and through a downcomer to either a sump or the lower stage.
4-43
-------
The dust-laden gas enters the lower section of the scrubber and passes
up through a spray zone created by a group of low-pressure sprays. As the
dust-laden gas passes through the impingement stage, the high gas and particle
velocity (from 75 to 100 feet per second) effectively atomizes the liquid at the
edges of the perforations. The spray droplets, about 10 microns in size,
enhance collection of fine dust.
Overall efficiency for a single plate may range from 90 to 98 percent
for 1-micron particles or larger, with pressure drops of from 1 to 8 inches of
water and water requirements of from 3 to 5 gallons per 1000 cubic feet of
37
gas.
4.4.2.5 Venturi Scrubbers - Obtaining high collection efficiency of fine
particles by impingement requires a small obstacle diameter and high relative
velocity of the particle as it impinges on the obstacle. In a venturi scrubber
this is achieved by introducing the scrubbing liquid at right angles to a high
velocity gas flow in the throat (vena contracta) of the venturi. Very small
water droplets are formed by the gas flow, and high relative velocities are
maintained until the droplets are accelerated to their full speed.
In the venturi scrubber the velocity of the gases alone causes the dis-
integration of the liquid. The energy expended in the scrubber is accounted
for by the gas stream pressure drop through the scrubber, except for the
small amount used in the sprays and mist separation chamber.
A second factor which plays a part in the effectiveness of the venturi
scrubber is the conditioning of dust particles by condensation. If the gas in
4-44
-------
TARGET .
PLATE \
IMPINGEMENT
BAFFLE STAGE
ORIFICE
PLATE
GAS FLOW
ApG.Sr°^E.l;lA_TING ARRANGEMENT OF "TARGET PLATES'
iLUlilAbb IN IMPINGEMENT SCRUBBER
WATER DROPLETS ATOMIZED
AT EDGES OF ORIFICES
DOWNSPOUT TO
LOWER STAGE
IMPINGEMENT SCRUBBER b. IMPINGEMENT PLATE DETAILS
Figure 4-17. Impingement plate scrubber.
4-45
-------
the reduced-pressure region in the throat is fully saturated, or (preferably)
supersaturated, some condensation will occur on the particles in the throat due to
the Joule-Thompson effect. Condensation will be more pronounced if the gas is
hot, due to the cooling effect of the scrubbing liquid. This helps the particle to
grow, and the wetness of the particle surface helps agglomeration and separation,
Gas velocities of from 200 to 600 feet per second are attained in the
venturi throat. Water is either injected into the throat of the venturi as a
spray (Figure 4-18a) or by means of a weir box (Figures 4-18b and 4-18c) in
quantities of from 5 to 7 gallons per 1000 cubic feet of gas.
Figures 4-18b and 4-18c show a scrubber that uses an overflow weir on
the walls upstream of the venturi. This method of water injection has the ad-
vantage of allowing the scrubbing water to be recirculated to much greater
extent than is possible with systems using small jets.
Recent developments have taken the form of finding methods of injecting
water to reduce nozzle wear and pump requirements, and in maintaining pres-
sure drop with varying gas flows. Methods of maintaining pressure drop and
scrubbing efficiency with varying gas flow rates have been centered in the
development of variable venturi throats.
The flooded disk (variable-throat-orifice scrubber) illustrated in Figure
41
4-19 is a relatively new development. Scrubbing liquid is fed to the center
of the orifice plate, which serves to distribute the liquid across the orifice
throat. The pressure drop and efficiency performance is comparable to other
4-46
-------
Figure 4-18. Venturi scrubber may feed liquid through jets (a),
over a weir (b), or swirl them on a shelf (c).
(Courtesy of UOP Air Corroction Division)
4-47
-------
venturi scrubbers. The scrubbing efficiency and pressure drop may be ad-
justed by changing the position of the disk.
CLEAN GAS OUTLET
DUSTY GAS
INLET
CYCLONE MIST
SEPARATOR
ADJUSTABLE DISK
STUFFING BOX
SCRUBBING WATER INLET-
TANGENTIAL
INLET
DISK-POSITIONING ROD
SCRUBBING WATER OUTLET
Figure 4-19. Flooded disk (variable throat orifice) scrubber.
(Courtesy of Research Cottrell Incorporated)
The operating pressure drop across the unit ranges from 6 to 70 inches
of water. Water recirculation rate is about 5 gallons per 1000 cubic feet of
gas; make-up water required is about a gallon per 1000 cubic feet.
4-48
-------
In the venturi jet scrubber the scrubbing liquid may be supplied in the
form of a high-velocity jet directed along the axis of a venturi throat. The
ejector venturi scrubber uses the velocity of the contacting liquid to pump, scrub,
and/or absorb the entrained gas.
The mechanical efficiency of the venturi jet stream in pumping the gas
may range as high as 16 to 17 percent of the total energy input. The energy
requirements range from 1 to 5 horsepower per 1000 cubic feet per minute.
Corresponding liquid requirements range from 20 to 50 gallons per 1000 cubic
feet of gas. Increased collection efficiency requires increased energy ex-
42,43
penditure.
In the multiple-venturi jet scrubber (Figure 4-20), a nozzle sprays
a hollow cone of water into the belled venturi entrance so that the spray strikes
the throat wall and rebounds in the form of a fine spray at right angles to the
gas stream. The water passes through the gas stream twice before passing
through the venturi diffuser section. Features of the design are low water
44
usage and low pressure drop.
The vertical venturi differs from the conventional venturi scrubber in
that the gas flow is directed upward to produce a turbulent mixing action of the
gas stream and suspended scrubbing liquid in the diffuser section of the venturi
(Figure 4-21). Liquid recirculation occurs both internally by eddy mixing
action in the diffuser and externally by return of the scrubbing liquid, after
partial solids separation, to the venturi throat. The carryover slurry, when
4-49
-------
Figure 4-20. Multiple-venturi jet scrubber.
(Courtesy of B ue 11 Corporation)
4-50
-------
MIST ELIMINATOR
SECTION
CUTAWAY VIEW OF
AEROMIX SHOWING
FLOW PATTERN. NOTE
RECIRCULATION ZONE.
Figure 4-21. Vertical venturi scrubber,
(Courtesy of UOP Air Correction
Division)
separated by the centrifugal action
of the gas stream caused by the sta-
tionary impeller, returns by gravity
to the solids concentrator. The
principal advantages of this design
are high solids content of slurry, low
water usage (1 to 3 gallons per f 000
cubic feet of gas), elimination of a
recirculation pump, relatively low
pressure drop, and low operating
45
costs.
4. 4. 2. 6 Packed Bed Scrubbers - A
tower or box packed with such pack-
ing as Raschig rings, saddles, tile,
and marbles may be used for dust
and mist collection as well as for gas
absorption (Figure 4-22). Two basic
packed bed designs, cross-flow
(Figure 4-23a) and countercurrent
flow (Figure 4-23b) exist. The
packed bed may be held in place
(fixed), free to move (fluid), or
4-51
-------
PALL RING
TELLERETTE
MASPAC
PLASTIC INTALOX
SADDLE
RASCHIG
RING
LESSING
RING
CROSS-PARTITION
RING
SINGLE SPIRAL DOUBLE SPIRAL TRIPLE SPIRAL
RING RING RING
BERL
SADDLE
INTALOX
SADDLE
CERAMIC PACKINGS
Figure 4-22. Wet scrubber packings.
4-52
-------
GAS OUTLET
f
CJl
CO
LIQUID
DISTRIBUTION UNWETTED
PACKING HEADERS , SECTION FOR
SUPPORT-, / ,-' MIST ELIMINATION
C" t? i r^
-PACKING SUPPORT
GRID
DIRTY
GAS IN
CLEAN GAS
FRONT /
CLEANING "
SPRAYS
GAS INLET
"SUMP
MIST
ELIMINATOR
SECTION
LIQUID
INLET
'V WEIR
DISTRIBUTOR
PACKED
SCRUBBING
SECTION
. PACKING
SUPPORT
LIQUID
OUTLET
a. CROSS-FLOW SCRUBBER
b. COUNTERCURRENT-FLOW SCRUBBER
Figure 4-23. Packed-bed scrubbers.
(Courtasy of Chemical Engineering Magazine)
-------
covered with water (flooded). The irrigating liquid serves to wet, dissolve,
and/or wash the entrained particulate matter from the bed. Dry beds may be
used for the elimination of mists. In general, smaller-diameter tower packing
gives a higher particle target efficiency than larger-sized packing for a given
gas velocity.
The cross flow, fixed bed, packed scrubber (Figure 4-23a) operates
with the gas stream moving horizontally through the packing while the irriga-
ting liquid flows by gravity vertically through the packing. This type of scrub-
ber operates with a very low pressure drop and water requirements, both of
which are about 40 percent of that required for counter flow operation. The
leading face of the packed bed is usually slanted from 7 to 10 degrees (depend-
ing on gas velocity) in the direction of the oncoming gas stream to ensure com-
plete wetting and washing of the face of the bed by the falling irrigation liquid.
Inlet sprays are usually included in this design to condition the inlet gas and
scrub the face of the packed bed. The first few inches of the bed may be irri-
gated more heavily to prevent build-up of solids. The back of the bed is usually
46
operated dry to act as a demisting section.
Liquid requirements range from 1 to 4 gallons per 1000 cubic feet of
gas, with pressure drops of from 0. 2 to 0. 5 inch of water per foot of bed.
Collection efficiency in excess of 90 percent may be achieved when collecting
particles of 2 microns or larger, with dust loadings as high as 5 grains
47
per cubic foot. Higher dust loadings may be handled if the dust is readily
soluble.
4-54
-------
Countercurrent flow (Figure 4-23b) is the most common design used in
packed beds. Gas is forced upward through the packing against gravity flow of
the liquid.
Countercurrent flow works best at a pressure drop and gas velocity
that cause the buildup of water in and on top of the bed, usually 0.5 to 1.0
4ft
inch of pressure drop per foot of packing depth. Pressure drop in excess
of this amount will usually result in excessive liquid entrainment and reduced
efficiency. Liquid flow rates of from 10 to 20 gallons per 1000 cubic feet of
gas are common. Water efficiency will then be at a maximum and bed clogging
at a minimum.
In cocurrent, or parallel flow, the gas stream and liquid pass through
the bed in the same direction. In this type of operation the irrigation liquid
keeps the packed bed from being clogged, and the gas and liquid both assist in
washing solids through the bed. The advantage of this type of operation is the
small liquid requirement, 7 to 15 gallons per 1000 cubic feet of gas. The
operating pressure drop is on the order of 1 to 4 inches of water per foot of
packed bed.
The flooded-bed packed scrubber is operated as a counterflow packed tower
(Figure 4-24). The packing consists of a 6-inch thick bed of spherical packing.
Dust- and fume-laden air enters below the bed of glass marbles and passes through
a spray section and up through the flooded bed of spheres. Bubbles formed in
the bed create a turbulent layer approximately 6 inches in depth. The marbles
4-55
331-716 0-69-14
-------
have a constant, gentle rubbing action which makes them self-cleaning. En-
trained moisture is removed by impaction or inertial separation in a mist
elimination section. The scrubber is reported to be 99 percent efficient in re-
moving particles 2 microns and larger with a pressure drop of from 4 to 6
49 /
inches of water. Scrubbing liquid requirements are from 2 to 2-1/2 gallons
per 1000 cubic feet of gas. Liquid with a high solid content can be recirculated.
The scrubber is capable of handling dust loads of up to 40 grains per standard
cubic foot. Flooded bed packed scrubbers may be used to control emissions
of acid vapors, carbon black, ceramic frit, chlorine tail gas, cupola gas, and
ferrite dusts.
Fluid bed packed scrubber (Figure 4-25) packing consists of low density
polyethylene or polypropylene spheres about 1-1/2 inches in diameter that are
45
continually in motion between the upper and lower retaining grid.
The scrubbing liquid is sprayed downward over the balls in a counter-
current flow of dirty gas. Gas and liquid are brought into contact on the sur-
face of the wetted spheres and in the spray between them.
The spheres are continually cleaned by constant motion, and the bed is
not readily plugged.
Pressure drop ranges from 6 to 8 inches of water, and collection
efficiencies are in excess of 99 percent for particles of 2 microns and larger.49
Liquid and dust handling capacities are comparable to the flooded bed packed
uu 45
scrubber.
4-56
-------
GLASS SPHERES
SPRAY
WATER INLET
MIST
ELIMINATOR
TURBULENT
LAYER
Figure 4-24. Flooded-bed scrubber.
(Courtesy of National Dust Collector Corporation)
4-57
-------
CLEAN GAS
MIST ELIMINATOR
FROM
RECIRCULATION
PUMP
SCRUBBING LIQUOR
RETAINING GRID
FLOATING BED OF LOW
DENSITY SPHERES
RETAINING GRID
MAKEUP LIQUOR
TO
RECIRCULATION
PUMP
c> O~u u
oo \poooooo
O. OlONO O, O O O
TO DRAIN
OR RECOVEF
Figure 4-25. Floating-ball (fluid-bed) packed scrubber.
(Courtesy of UOP Air Correction Division)
4-58
-------
4.4. 2.7 Self-Induced Spray Scrubbers - The particle collection zone of the
self-induced spray scrubber is a spray curtain that is induced by gas flow through
a partially submerged orifice or streamlined baffle. Mist carryover is minimized
by baffles or swirl chambers. In the submerged orifice scrubber (Figure 4-26a)
the impingement gas velocity of about 50 feet per second creates droplets in the
50
300- to 400-micron range. Blaw Knox (Figure 4-26b) and Doyle (Figure
4-26c) scrubbers operate with impingement velocities of from 120 to 180 feet
A 51
per second.
Pressure drop ranges from 2 to 15 inches, and water requirement is
about 1 gallon per 1000 cubic feet of gas when water is recycled.
The chief advantages of the self-induced spray scrubber design are
its ability to handle high dust concentration and concentrated slurries.
Sludge removal may be accomplished by drag chains or by sluicing the
sludge to suitable separators.
4.4.2.8 Mechanically Induced Spray Scrubbers - In the mechanically induced
spray scrubber (Figures 4-27a and 4-27b) high-velocity sprays are generated
at right angles to the direction of gas flow by a partially submerged rotor.
Scrubbing is achieved by impaction because of both high radial droplet velocity
and vertical gas velocity. Liquid atomization occurs at the rotor and at the
52
outer wall.
4-59
-------
GAS OUTLET
I
OJ
o
a. SCHMIEG SWIRL-ORIFICE DUST COLLECTOR
(Courtesy of United Sheet Metal Co., Inc.)
SEPARATOR
PLATES
PRIMARY
-' SEPARATOR
b. LIQUID VORTEX CONTRACTOR
(Courtcfly of Blow Kno> Co.)
DIRTY GAS
RECYCLE TO
PROCESS
DOYLE SCRUBBER
(Court.,y at W..r.,n Pr,
Figure 4-26. S©l f- inducedspray scrubbers.
-------
Power and liquid requirements range from 3 to 10 horsepower and from
4 to 5 gallons per 1000 cubic feet of gas for the high-velocity design (Figure
53
4-27b), depending on particle size and the desired level of scrubbing efficiency.
Advantages of this type of scrubber are relatively low liquid requirements,
small space requirements, high scrubbing efficiency, and high dust load capac-
ity. The rotor, however, is susceptible to erosion from large particles
and abrasive dusts, and high-energy scrubbing applications may require
the use of additional mist elimination equipment.
4.4.2.9 Disintegrator Scrubbers - A disintegrator scrubber consists of a
barred rotor within a barred stator. Water is injected axially through the rotor
shaft and is separated into fine droplets by the high relative velocity of rotor and
stator bars. Dust particles are impacted by the high velocity liquid droplets.
Water and power requirements range from 4 to 9 gallons per minute
and from 7 to 11 horsepower, respectively, for each 1000 cubic feet per minute of
gas handling capacity. Scrubbing efficiency is about 95 percent for 1-micron
particles and may be improved by increasing either the water rate or the num-
ber of stator and rotor bars. Scrubbing efficiency is independent of dust load-
ing, and exit dust concentrations range as low as 0. 004 grain per standard cubic
* 4. 54
foot.
Advantages of this scrubber are high collection efficiency for submicron
particles and low space requirements. The principal disadvantage is its large
power requirement.
4-61
-------
4-
-
L:
a. SCHMIEG VERTICAL-ROTOR DUST COLLECTOR
(Courtesy of United Sheet Metal Co., Inc.)
b. CENTER SPRAY HIGH-VELOCITY SCRUBBER
(Courtesy of Air Engi neer i ng Mag a z i ne)
Figure 4-27. Mechanically induced spray scrubbers.
-------
4.4.2.10 Centrifugal Fan Wet ScrubbersThis type of scrubber, (Figure
4-28) consists essentially of a multiple-blade centrifugal blower.
Design pressure drop is about 6-1/2 inches with a maximum pressure
drop of 9 inches. Water requirements range from 3/4 to 1. 5 gallons per 1000
cubic feet of gas and power requirements range from 1 to 2 horsepower per
55
1000 cubic feet per minute.
The chief advantages are low space requirements, moderate power
requirements, low water consumption, and a relatively high scrubbing effici-
ency.
4.4. 2.11 Inline Wet ScrubbersIn this axial-fan-powered gas scrubber
(Figure 4-29), a water spray and baffle screen wet the particles, and centrifugal
fan action eliminates the wetted particles through concentric louvers.
Pressure drop is about 5 inches of water, and water consumption is
about 1 gallon per 1000 cubic feet of gas. The moisture removal capacity of
the eliminator section is sensitive to changes in gas flow rate. Average re-
moval efficiency is in excess of 99 percent for particles ranging in size from
5 to 10 microns.
Advantages of the inline wet scrubber are low installation space re-
quirements and low installation costs. Coal and metal mining industries use
inline scrubbers.
4-63
-------
DIRT AND WATER
DISCHARGED AT
BLADE TIPS
DIRTY GAS
INLET
CLEAN GAS
OUTLET
WATER AND
SLUDGE OUTLET
Figure 4-28. Centrifugal fan wet scrubber.
(Courtesy of American Air Filter Company^
4-64
-------
Figure 4-29. Inline wet scrubber.
(Courtesy of Joy Manufacturing Company)
4-65
-------
4.4. 2.12 Irrigated Wet Filters - Irrigated wet filters (Figure 4-30a) con-
sist of an upper chamber, containing wet filters and spray nozzles for clean-
ing the gas, and a lower chamber for storing scrubbing liquid. Liquid is re-
circulated and sprayed onto the surface of the filters on the upstream side of the
bed. Two or more filter stages constructed in series are used. A dry bed
containing small diameter fibers may be added as a final cleanup stage to re-
r.f7 IT Q
move spray mist. ' A wetted impingement plate may be used in the first com-
rq /?A
partment to reduce the particle load on the following stage (Figure 4-30b). '
The number of cleaning stages to be used is determined by the character-
istics of the gas stream and cleaning requirements. Gas velocities range from
200 to 300 feet per minute with a liquid requirement of approximately three
gallons per minute per square foot of filter area (8 to 10 gallons per 1000 cubic
feet of gas). Pressure drop, which ranges from 0. 2 to 3 inches of water per
4-inch bed depth, is dependent on the gas loading, liquid loading, and fiber bed
density. Normal bed thickness may range from 1 to 4 inches, based on
scrubbing requirements.
The chief mechanism of irrigated wet filters involved in the capture of
particulate matter is interception by individual filaments in the filter. Both
particle removal and gas absorption can be accomplished, and the irrigation
feature aids in removal of solid particulate matter.
4. 4. 2.13 Wet Fiber Mist Eliminators - Two mechanisms, Brownian diffu-
sion and inertial impaction, are involved in the separation of mist and dust
particles in wet fiber mist eliminators.
4-66
-------
SPRAY HEADER CONNECTION
FLOAT VALVE
QUICK FILL
OVERFLOW
LIQUIDLEVELINDICATORS
SUCTION CONNECTION
a. WETTED FILTER
IMPACTION
DUST-LADEN GAS
WATER FILM
VENA CONTRACTA
WATER FILM
WATER DROPLETS
b. IMPINGEMENT PLATE FILTER
Figure 4-30. Wetted and impingement plate filters.
(Courtesy of Buffalo Forge Company)
4-67
-------
Brownian diffusion dominates in mist collection in which fiber beds with
large specific surface areas are used, gas velocities range between 5 and 30
feet per minute, and the mist consists largely of submicron particles. A char-
acteristic of Brownian diffusion control is that collection efficiency increases
with decreasing gas velocity because of increased filter bed retention time.
This collection mechanism has some effect on the collection of 3-micron parti-
cles and a major effect on the collection of 0. 5 micron particles. Brownian
motion is an important factor in particle capture by direct interception.
Inertial impaction dominates in particle collection above 3 microns in
size at gas velocities in excess of 30 feet per second in coarse filter beds.
Inertial impaction efficiency increases with increasing gas velocity.
Fiber diameter and the distance between adjacent fibers are important
in determining collection efficiency and pressure drop. Because high mechani-
cal bed stability is necessary for operation in the high pressure drop range,
design of mounting and support structures becomes critical.
Wetted filters are available in two designs, low-velocity (5 to 30 feet
per minute), illustrated in Figure 4-31, and high-velocity (30 to 90 feet per
minute), illustrated in Figure 4-32. The low-velocity design consists of a
packed bed of fibers retained between two concentric screens. Mist particles
collect on the surface of the fibers, coalesce to form a liquid film that wets
the fibers, and are moved horizontally and downward by gravity and the drag
-------
of the gases. The liquid flows down the inner screen to the bottom of the
element and through a liquid seal to a collection reservoir. Collection effi-
ciencies are reported to be in excess of 99 percent on particles smaller than
3 microns at operating pressure drops of from 5 to 15 inches of water. Effi-
ciencies increase when the scrubber is operated below design capacity.
The high-velocity filtering element (Figure 4-32a) consists of a packed
fiber bed between two parallel screens. A multiple mounting is shown in
Figure 4-32b. Liquid flow patterns are similar to those of the low-velocity
filter, and removal efficiencies range from 85 to 90 percent for 1- to 3-micron
62
particles and pressure drops of from 5 to 10 inches of water.
This type of wet filter finds application in the collection of sulfuric,
phosphoric, and nitric acid mists and in the separation of moisture and oil
from compressed gases. Disposable filters are used in the recovery of
platinum catalysts used in nitric acid manufacture and in the collection of
63
viruses and bacteria, and radioactive and toxic dusts.
The wire mesh filter consists of an evenly spaced knitted wire mesh
and is usually mounted in horizontal beds (Figure 4-33). The principal
collection mechanism is inertial impaction. Rising mist droplets strike the
wire surface, flow down the wire to a wire junction, coalesce, and flow to the
4-69
-------
CLEAN
GAS OUT
SUPPORT PLATE
SCREENS
FIBER PACKING
f
LIQUID DRAINAGE
LIQUID
SEAL
POT
LIQUID BACK TO PROCESS
a. LOW-VELOCITY FILTERING ELEMENT
CLEAN GASES
TO STACK
i?=xl
ACID-LADEN
GASES
TUBE SHEET
BRINK MIST
ELIMINATOR
ELEMENTS
RECOVERED
H2S04
b. MULTIPLE MOUNTING OF LOW-VELOCITY FILTER-
ING ELEMENTS
Figure 4-31. Low-velocity filtering elements.
(Courtesy of Monsanto Company)
-------
MANHOLES
X
DIRTY GAS
IN
CLEAN
GAS
OUT
FIBER
ELEMENTS
LIQUID
LEVEL
__ACID
OUT
a. HIGH-VELOCITY FILTERING ELEMENT
b. MULTIPLE MOUNTING OF HIGH-VELOCITY FILTER-
ING ELEMENTS
Figure 4-32. High-velocity filtering elements.
(Courtesy of Monsanto Company)
-------
-q
to
STACK
WIRE MESH
WIRE MESH
ACID DRAIN
EFFLUENT FROM
ABSORBER
a. MIST ELIMINATOR ARRANGEMENT IN VESSEL
ABOVE ACID PLANT ABSORBER
(Courtesy of Chemical Engineering Progress Magazine)
fa. ONE-PIECE DEMISTER(RJ
(Courtesy of Otto H. York Co., Inc.)
Figure 4-33. Wire mesh mist eliminators.
-------
bottom surface of the bed, where the liquid disengages in the form of large
droplets and returns by gravity to the process equipment.
Operating pressure drop is usually less than 1 inch of water with gas
velocities of from 10 to 15 feet per second. Recent development has centered
on the area of high energy filtration in which pressure drops of from 35 to 40
inches of water gauge have been used.
Factors governing maximum allowable gas velocities include gas and
liquid density, surface tension, viscosity, bed specific surface area, liquid
f1"1 I
loading, and suspended solids content.
Advantages in the use of fiber filters and wire mesh mist collectors
are high removal efficiency, simplicity of operation, low maintenance in dust-
free service, low initial cost, and recovery of valuable products without dilu-
tion.
4.4.2.14 Impingement Baffle Mist Eliminators - Baffle mist eliminators
offer one of the simplest methods of controlling large-diameter solid and
liquid particulate emissions. A variety of designs are in use. Figures 4-34,
4-35, 4-36, and 4-37 show the arrangement of baffles successfully used in the
reduction of emissions from coke quenching operations. An S5 to 90 per-
cent reduction of emissions was achieved on particulate matter which ranged
from 16 to 200 mesh at gas velocities ranging to a high of 36 feet per second.
A significant reduction in water droplet fallout was also achieved. The baffles
were operated dry with short spray periods to prevent the buildup of solids.
4-73
-------
A
4_
WATER SPRAY
MANIFOLD
HANGER >.=
BAFFLES^--
SECTION A-A-*.
1 ^f"
l~^^
.Y ~^y\ x a-
»*)jj.* \ , ' . * V l ' \ % * / ' 1 \ '
^^^~~
A
_J
TOP VIEW
TOP OF
=? TOWER
.- SPRAY
NOZZLES
SIDE VIEW
b. MIST ELIMINATOR BAFFLES
a. DIAGRAM OF BAFFLE SYSTEM SHOWING CLEAN-
ING WATER SPRAYS AND BAFFLE ARRANGEMENT
LIP
FLOW
Figure 4-34. Coke quench mist elimination baffle system.
(Courtesy of U. 5. Steel Corp.)
Figures 4-35, 4-36, and 4-37 show the common lay-
outs of mist eliminator baffles used in spray chamber
35,66
scrubbers.
Mist removal efficiencies of as
60° BENT PLATE UNIT
high as 95 percent may be achieved for the removal
of 40-micron spray droplets up to a maximum gas
velocity of 25 feet per second and pressure drops of
from 1 to 2 inches of water. Velocities in excess of
25 feet per second result in the re-entrainment of
liquid droplets.
Figure 4-35. Details of baffle
design.
(Cou,,.sy Of chemicoi Engineering 4. 4. 2.15 Vane-Type Mist Eliminators - Vane-
Progress Magozine)
type mist eliminators (Figure 4-36) have a range
of operation of from 10 to 50 feet per second, with
4-74
-------
AAAAAAA
AAAAAAAA
AAAAAAA
AAAAAAAA
AAAAAAA
AAAAtAAAA
GAS
FLOW
Figure 4-36. Streamline mist eliminator baffles.
FLUE
GAS
\
16 GAUGE PLATE
317 STAINLESS /40C
WIRE MESH ~ '
Figure 4-37. Screen and mist eliminator details.
(Courtesy of Paper Trade Journal)
4-75
-------
collection efficiencies reported to be as high as 99 percent for 11-micron par-
ticles and with pressure drops from 0.1 to 2 inches of water. The prin-
cipal advantage of vane type over baffle mist eliminators is the wider range of
67
operation at comparable collection efficiencies.
4. 4. 2.16 Packed Bed Mist Eliminators - Figure 4-38 shows a packed bed
stack mist eliminator. Removal efficiencies of such devices may range to as
high as 65 percent at gas velocities of from 7 to 10 feet per second. Mist re-
entrainment occurs at higher gas velocities because of the turbulent nature of
gas flow in packed beds. This type of mist eliminator is often used for tail
gas cleanup in sulfuric and phosphoric acid manufacture.
4. 4. 2.17 Mist and Vapor Suppression - Mist formation from bubbling
solutions, such as plating baths and acid pickling baths, may be reduced by the
addition of wetting agents. Foaming and non-foaming types are presently used
71-74
to reduce both surface tension and bubble size. Smaller bubbles escape
the treated bath with less violence and with a corresponding reduction in the
formation of mist particles. Foaming agents reduce mist formation by reduc-
ing bubble escape energy and by trapping the mist particles in a dense foam.
The use of surfactants in chrome plating baths can reduce chromic acid losses
by as much as 45 percent with a corresponding reduction in air and water pol-
lution.
Foam, which has the disadvantage of trapping hydrogen gas, can create
a fire hazard and must be continually replaced. Floating plastic objects such
4-76
-------
BERL SADDLES
Figure 4-38. Bed of Berl saddles added to
discharge stack.
(Courtesy of Chemicol Engineering Progress Magazine)
as polyethylene balls, hollow rods,
75
and cylinders are also used.
The floating plastic used to
cover the surface serves as a
tank top and mist eliminator and
reduces heat losses and ventila-
tion requirements.
In one case the use of 3/4-
inch balls to cover 90 percent of
the surface area of sulfuric acid
solutions used in the electro-re-
75
fining of copper resulted in a 90 percent reduction in evaporation losses and a
70 percent reduction in heat loss. The savings from the reduction in loss
of methylated spirits (an addition agent) over a 2- week period paid for the
balls. In addition to a 90 percent reduction in air pollution from sulfuric acid
mist, there was a noticeable reduction in corrosion rates. The approximate
cost of the ball cover is $1. 50 to $2. 00 per square foot of tank surface area.
4. 4. 2. 18 Liquid Distribution - Wet scrubbers require a uniform and con-
sistent liquid distribution pattern for the maintenance of high scrubbing effici-
encies at minimum water rates. Liquid distribution in wet scrubbers is ac-
complished by spray nozzles or spinning disk atomizers. Weir box or sieve
plate distributors may be used for packed towers.
4-77
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4.4.£.19 Spray Nozzles - Spray scrubbers require liquid droplets that are
closely sized in order to avoid liquid entrainment at maximum gas flow rates.
Since the scrubbing liquid is often recirculated, the spray nozzles must be
capable of handling liquids with fairly high solids content.
The basic functions of liquid spray nozzles and atomizers are to
create small droplets with large surface areas, to distribute the liquid in a
specific pattern, to control liquid-flow metering, and to generate high-velocity
76-79
droplets. At least one of the above functions is involved in every industrial
spraying process, and spray nozzle selection depends on the specific function
to be performed. The spray devices used in wet scrubbers may be classified
as pressure nozzles (hollow and solid cone and impingement and impact),
rotating nozzles (spinning atomizers), and miscellaneous nozzles.
In hollow-cone spray nozzles, the fluid is fed to a whirl chamber
a tangential inlet (Figure 4-39a) or a fixed spiral (Figure 39b) so that the
fluid acquires rapid rotation. The orifice is on the axis of the chamber, and
the fluid exits as a hollow conical sheet and then breaks up into droplets.
The angle of the spray is determined by the dimensions of the swirl chamber
and the pitch of the nozzle. A spiral with a short pitch produces a wide-
angle spray; conversely, a long pitch produces a narrow-angle spray.
The spray angle may range from 15 to 135 degrees.
4-78
-------
j. HOLLOW CONE SPRAY
NOZZLE
Courtssy of Spray Systems
Company)
d. SOLID CONE SPRAY
NOZZLE
(Courtesy of Spray Engineer-
ing Company)
h. SPINNING DISK SPRAY
NOZZLE
(Courtesy of Schutte &
Koerting)
b. HOLLOW CONE SPRAY
NOZZLE
(Courtesy of Schutte &
K oert i ng )
B. SOLID CONE SPRAY
NOZZLE
(Courtes y of Bete Company)
i. MONOFAN NOZZLE
(Courtes y of Spray Engmeer-
i ng Company)
*-. HOLLOW CONE SPRAY
NOZZLE
(Courtesy of Schutte &
K oert i ng)
f. CLUSTER SPRAY NOZZLE
(Courtes y of Spray Eng ineer-
i ng 'Company)
g. PINJET IMPINGEMENT
SPRAY NOZZLE
(Courtes y of Spray E ng ineer-
ing Company)
Figure 4-39. Spray nozzles commonly used in wet scrubbers.
4-79
-------
Hollow cone spray nozzles with cone angles of from 15 to 20 degrees
(Figures 4-39b and 4-39c) are used in venturi jet scrubbers for maximum
turbulence and mixing in the throat and diffuser section. Larger nozzle angles
are used in air washers and humidifiers.
The solid cone nozzle (Figure 4-39d) is a modification of the hollow cone
nozzle used when complete coverage of fixed area is desired. The nozzle is
essentially a hollow-cone nozzle with the addition of a central axial jet. The
jet strikes the outer rotating fluid inside the nozzle orifice and is broken into
droplets. The angle of the spray is a function of nozzle design and is nearly
independent of pressure. A second type of solid cone spray nozzle (Figure 4-39el
consists of an orifice and external helical spiral. The nozzle is essentially non-
clogging and finds use in packed column distributor design. Commercial solid
cone nozzles are available with included angles of from 30 to 100 degrees.
Wet scrubbers nearly always use nozzles with large angle sprays. Solid-cone
spray nozzles are frequently mounted in clusters (Figure 4-39f). Liquid dis-
tribution is enhanced by using several small sprays instead of one large spray
of the same capacity. Liquid distribution is also improved by the proper sel-
78
ection of pipe manifold size.
In the impingement-type nozzle (Figure 4-39g), a high-velocity liquid
jet is directed at a solid target or a liquid stream. Proper orientation and
shape of the target or control of the size and shape of the two fluid streams
produces a hollow cone, fan, or dish-shaped spray pattern. The nozzles are
4-80
-------
robust and simple in shape, and despite higher cost, they are frequently used
in wet scrubbing towers because of their more uniform distribution of droplet
size.
Rotating nozzles (spinning atomizers) are a type of liquid distributer
(Figure 4-39h) less frequently used in gas scrubbing than either hollow cone
or solid cone nozzles. The droplets produced by rotating nozzles are uniform
in size and can be controlled without regard to liquid feed rate by changing the
disk speed. Spinning atomizers are used in some wet scrubbers and have the
advantage of being able to handle slurries that could clog conventional nozzles.
Among miscellaneous atomizers, the fan jet (Figure 4-391) is used in wetting
and light humidification operations.
In packed tower and cross flow scrubber liquid distributor design, spray
nozzles and drilled pipe headers may be used to distribute liquid. Most packed
tower liquid distributors are of the weir box V-notch type (Figure 4-40a). For
low rates of gas flow, weir risers (Figure 4-40b) may be used. Submerged
orifice plate distributors (Figure 4-40c) are also used. Liquid distribution
79
is critical in determining scrubber performance.
Because spray nozzles frequently wear or clog and produce an uneven
liquid pattern, they require frequent replacement and maintenance. Weir box
distribution, on the other hand, is dependable and requires little maintenance
after initial leveling. Pumping heads are also lower and result in lower power
requirements and less maintenance.
4-81
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o. PACKED TOWER WEIR BOX LIQUID DISTRIBUTOR
(Courtesy of Koch Engineering Compony)
b. PACKED TOWER "WEIR RISER" LIQUID DISTRIBUTOR
(Courtesy of U. S. Stonawore Compony}
I
00
to
c. "SUBMERGED ORIFICE" PLATE DISTRIBUTOR
-------
Liquid distribution within a packed bed is also very important. Initial
distribution of liquid onto the top of the bed is often enhanced by the use of
small sized packing in the top of the bed.
Normal drip point requirements for weir box distribution range from 8
to 10 points per square foot for vertical packed beds and from 15 to 30 points
for cross flow scrubbers.
Cross flow scrubbers normally contain baffles or corrugated walls
around the periphery of the packed bed to prevent gas channeling. Packed beds
above 15 feet in height frequently require liquid redistribution.
4.4.3 Typical Applications of Wet Scrubbers
Typical applications of wet scrubbers are tabulated in Table 4-6.
4.4.4 Water Disposal
Water usage and waste disposal may become critical factors in the final
selection of a wet scrubber. Waste quantity, particle size distribution in the
slurry, recovery value, corrosiveness of the solutions, and materials of con-
struction are important factors. The final selection of a water treatment or
disposal system should not result in water, soil, or air pollution. Refer to
references 80 through 92 for additional information.
4.4.4.1 Settling Tanks and Ponds - This method of disposal may be applied
to scrubber discharges containing solid particulate matter that readily settles
or is easily flocculated by chemical treatment. Tank or pond size may be
Q rj
easily determined by laboratory sedimentation tests. Separation by
4-83
-------
Table 4-6. TYPICAL INDUSTRIAL APPLICATION OF WET SCRUBBERS
Scrubber type
Typical application
Spray chambers
Spray tower
Centrifugal
Impingement plate
Venturi
Venturl throat
Flooded disk
Multiple jet
Venturi jet
Vertical venturi
Packed bed
Fixed
Flooded
Fluid (floating) ball
Self-induced spray
Mechanically-induced spray
Disintegrator
Centrifugal fan
Inline fan
Wetted filters
Dust, mist eliminators
Fiber filters
Wire mesh
Baffles
Packed beds
Dust cleaning, electroplating, phosphate fertilizer, kraft paper, smoke
abatement
Precooler, blast furnace gas
Spray dryers, calclners, crushers, classifiers, fluid bed processes, kraft
paper, fly ash
Cupolas, driers, kilns, fertilizer, flue gas
Pulverized coal, abrasives, rotary kilns, foundries, flue gas, cupola gas,
fertilizers, lime kilns, roasting, titanium dioxide processing, odor
control, oxygen steel making, coke oven gas, fly ash
Fertilizer manufacture, odor control, smoke control
Pulverized coal, abrasive manufacture
Fertilizer manufacturing, plating, add pickling
Acid vapors, aluminum inoculation, foundries, asphalt plants, atomic
wastes, carbon black, ceramic frit, chlorine tall gas, pigment manufac-
ture, cupola gas, driers, ferrlte, fertilizer
Kraft paper, basic oxygen steel, fertilizer, aluminum ore reduction,
aluminum foundries, fly ash, asphalt manufacturing
Coal mining, ore mining, explosive dusts, air conditioning, Incinerators
Iron foundry, cupolas, smoke, chemical fume control, paint spray
Blast furnace gas
Metal mining, coal processing, foundry, food, Pharmaceuticals
Electroplating, acid pickling, air conditioning, light dust
Sulfurlc, phosphoric, and nitric acid mists; moisture separators; house-
hold ventilation; radioactive and toxic dusts, oil mists
Sulfuric, phosphoric, and nitric acid mists; distillation and absorption
Coke quenching, kraft paper manufacture, plating
Sulfurlc and phosphoric acid manufacture, electroplating spray towers
4-84
-------
sedimentation is usually limited to particles larger than 1 micron or to particles
that readily flocculate. Advantages are that waste products to be disposed of
may be sluiced to a burial pit, waste water may be chemically treated and re-
used, operational costs are low, and abrasive solids can be handled. Disadvan-
tages are that a large area is required for the settling of small particles, ground
water contamination from ponds is possible, and natural evaporation to the
atmosphere occurs.
4.4.4.2 Continuous Filtration - This method of slurry treatment is usually
applied where the solids have some recovery value or are porous or incom-
es 1
pressible. Advantages are a dewatered waste product and moderate space
requirements. Disadvantages are high initial cost and relatively high mainten-
ance and operational costs.
4.4.4.3 Liquid Cyclones - The wet cyclone has come into prominence in the
last few years as a method for concentrating solids. The advantages are low
initial cost, low maintenance, ability to handle abrasive solids, and low space
requirements. Disadvantages are the production of high solids filtrate or over-
82
flow and relatively high power requirements.
4.4.4.4 Continuous Centrifuge - This method of solids separation can some-
Q O
times be applied to submicron slurries at fairly high collection efficiencies.
The advantages are low space requirements and a large variety of designs for
special requirements. Disadvantages are high capital and operating costs and
susceptibility to abrasion and corrosion.
4-85
-------
4.4.4.5 Chemical Treatment - Chemical treatment of liquid wastes includes
treatment with chlorine, lime, soda ash, carbon dioxide, ammonia, corrosion
84-93
inhibitors, coagulants, and/or limestone soak pits.
4-86
-------
4.5 HIGH-VOLTAGE ELECTROSTATIC PRECIPITATORS
4. 5.1 Introduction
The high-voltage electrostatic precipitator (ESP) is used at more large
installations than any other type of high-efficiency particulate matter collector.
For many operations, such as coal-fired utility boilers, the high-voltage elec-
trostatic precipitator is the only proven high-efficiency control device available
today. High-voltage single-stage precipitators have been used successfully to
collect both solid and liquid particulate matter from smelters, steel furnaces,
petroleum refineries, cement kilns, acid plants, and many other operations.
Figures 4-41 and 4-42 show typical electrostatic precipitator installations.
Electrostatic precipitators are normally used when the larger portion of
the particulate matter to be collected is smaller than 20 microns in mean diam-
eter. When particles are large, centrifugal collectors are sometimes employed
as precleaners. Gas volumes handled normally range from 50, 000 to 2, 000, 000
cubic feet per minute. Operating pressures range from slightly below atmos-
pheric pressure to 150 pounds per square inch gauge and operating tempera-
tures normally range from ambient air temperatures to 750" F.
4.5.2 Operating Principles
Separation of suspended particulate matter from a gas stream by high-
voltage electrostatic precipitation requires three basic steps:
1. Electrical charging of the suspended particulate matter.
2. Collection of the charged particulate matter on a grounded surface.
3. Removal of the particulate matter to an external receptacle.
4-87
331-716 0-68-16 ° '
-------
Figure 4-41. Multiple precipitator installation in basic oxygen furnace plant.
(Courtesy of Koppers Co. Inc.)
4-88
-------
Figure 4-42. Detarrer precipitators installed in steel mill.
(Courtesy of Koppers Co. Inc.)
4-89
-------
A charge may be imparted to particulate matter prior to the electrostatic
precipitator by flame ionization or friction; however, the bulk of the charge is
applied by passing the suspended particles through a high-voltage, direct-cur-
94
rent corona. The corona is established between an electrode maintained at
*
high voltage and a grounded collecting surface. Particulate matter passing
through the corona is subjected to an intense bombardment of negative ions
that flow from the high-voltage electrode to the grounded collecting surface.
The particles thereby become highly charged within a fraction of a second and
migrate toward the grounded collecting surfaces. This attraction is opposed
by inertial and friction forces.
After the particulate matter deposits on the grounded collecting surface,
adhesive, cohesive, and primary electrical forces must be sufficient to resist
any gas stream action and counter electrical forces that would cause reen-
trainment of the particulate matter. Free flowing liquids are removed from
the collecting surface by natural gravity forces. Successful removal of other
particulate matter depends on a complex interrelationship of particle size,
density, and shape and electrical, cohesive, adhesive, aerodynamic, and rap-
ping forces. This particulate matter is dislodged from the collecting surfaces
by mechanical means such as by vibrating with rappers or by flushing with
liquids. The collected material falls to a hopper, from which it is removed.
* The terms "collecting electrode" and "grounded collecting surface" are often
used synonymously.
4-90
-------
4. 5.3 Equipment Description
Two major high-voltage electrostatic precipitator configurations are
used: the flat surface and tube types. In the first, particles are collected on
flat, parallel collecting surfaces spaced from 6 inches to 12 inches apart with
wire or rod discharge electrodes equidistant between the surfaces. In tube-
type high-voltage electrostatic precipitators, the grounded collecting surfaces
are cylindrical instead of flat with the discharge electrode centered along the
longitudinal axis. Figures 4-43 and 4-44 show typical electrode and collecting
surface layouts for both types of high-voltage electrostatic precipitators. A
complete precipitator consists of many of these units as shown in Figures 4-45
and 4-46.
4.5.3.1 Voltage Control and Electrical Equipment High-voltage electro-
static precipitators operate with unidirectional current and with voltages of
from 30 to 100 peak kilovolts. Transformers are used to provide high-voltage
current. Rectifiers convert the alternating current to unidirectional current.
In addition, precipitators are usually equipped for automatic power control.
Electrical power energization and control equipment is usually furnished in
the form of several packaged units complete with instrumentation.
Transformers are usually oil cooled and are integrally connected to
silicon rectifiers. The transformer single-phase output may be rectified to
either double-half-wave or full-wave direct current. Earlier types of high-
voltage sets consisted of separate transformers using either vacuum tube or
4-91
-------
CHARGING FIELD
CHARGED ( - ) PARTICLES
HIGH-VOLTAGE DISCHARGE ELECTRODE).
COLLECTING BAFFLE
GROUNDED (+) COLLECTING SURFACE
DISCHARGE ELECTRODE TENSION WEIGHT
PARTICLE PATH
Figure 4-43. Schematic view of a flat surface-type electrostatic precipitator.
GROUNDED
COLLECTING SURFACE
CHARGED PARTICLES
DISCHARGE
ELECTRODE
HIGH-VOLTAGE
DISCHARGE ELECTRODE
(NEGATIVE )
. GROUNDED COLLECTING SURFACE
Figure 4-44. Schematic view of tubular surface-type electrostatic precipitator.
4-92
-------
I
CO
CO
SAFETY RAILING
HIGH VOLTAGE TRANSFORMER/RECTIFIER
RAPPER - H. V. ELECTRODE
RAPPER - COLLECTING SURFACE
PENTHOUSE ENCLOSING INSULATORS AND GAS SEALS
ACCESS PANEL
INSULATOR
H. V. WIRE SUPPORT
H. V. DISCHARGE ELECTRODE
PERFORATED DISTRIBUTION BAFFLE
GROUNDED COLLECTING SURFACE
SUPPORT COLUMNS
QUICK OPENING DOOR
(INSPECTION PASSAGE BETWEEN STAGES)
WIRE WEIGHTS
HOPPERS
Figure 4-45. Cutaway view of a flat surface-type electrostatic precipitator.
it-- t i >r\r> A :. r- _*:__r\- :-_\
(Courtesy of UOP Air Correction Division)
-------
GAS INLET
GAS OUTLET
HIGH-VOLTAGE
CONDUCTOR
DIFFUSER
VANES
INSULATOR COMPARTMENT
HIGH-VOLTAGE SYSTEM
SUPPORT INSULATOR
ELECTRIC HEATER
WATER SPRAYS
DISCHARGE ELECTRODE
SUPPORT FRAME
WEIR PONDS
DISCHARGE ELECTRODES
TUBULAR COLLECTING
SURFACES
CASING
WEIGHTS
DISCHARGE SEAL
Figure 4-46. Cross-sectional view of irrigated tubular blast furnace precipitator.
(Courtesy of Koppers Co. Inc.)
4-94
-------
mechanical rectifiers. Silicon rectifier conversion equipment is available for
modernizing existing vacuum tube or mechanical rectifiers.
Figure 4-47 shows one type of transformer-rectifier unit, and Figure 4-48
shows one type of power control unit.
4.5.3.2 Discharge ElectrodesThe discharge electrodes, which are almost
always negatively energized, provide the corona. Although round wires about
1/8-inch in diameter are usually used, discharge electrodes can be twisted
rods, ribbons, barbed wire, and many other configurations. Steel alloys are
commonly used; other materials include stainless steel, silver, nichromey'
aluminum, copper, Hastelloy^, lead-covered iron wire, and titanium alloy.
Any conducting material with the requisite tensile strength that is of the proper
configuration is a feasible discharge electrode. Figure 4-49 shows some com-
mon discharge electrode configurations.
4.5.3.3 Collecting Surfaces A variety of flat collecting surfaces is available.
The use of smooth plates, with fins to strengthen them and to produce quiescent
zones, has become common in recent years. Special shapes are designed pri-
marily to prevent reentrainment of dust. Figure 4-49 shows some types of
collecting surfaces. Essentially all tubular collecting surfaces are standard pipe.
4.5.3.4 Removal of Collected Particulate Matter Collected particulate mat-
ter must be dislodged from the collecting surfaces and discharge electrodes and
moved from the electrostatic precipitator hopper to a storage area.
4-95
-------
\
Figure 4-47. Typical double half wave silicon
rectifier with twin output bushings.
4-96
-------
Ui
Figure 4-48. Internal view of one type of recti-
fier control console showing com-
ponent parts.
(Courtesy of Koppers Co. Inc.)
4-97
-------
EXPANDED METAL
ROD CURTAIN
VEE POCKET
a. COLLECTING PLATES
if
r/
I/
17
SQUARE
ROUND BARBED
b. DISCHARGE ELECTRODES
STAR
PUNCHED
RIBBON
Figure 4-49. Electrostatic precipitator collecting plates and discharge electrodes.
4-98
-------
Liquid collected participate matter flows down the collecting surfaces and
discharge electrodes naturally and is pumped to storage.
Solid collected particulate matter is usually dislodged from collecting
surfaces by pneumatic or electromagnetic vibrators or rappers. At times,
motor driven hammers are used for this purpose or sprays are used to flush
materials from collecting surfaces. Solid materials are transferred from the
hopper to storage by air, vacuum, or screw conveyors. Swing valves, slide
gates, or rotary vane-type valves are installed at the hopper outlet. Figures
4-50 and 4-51 show some types of hopper valves and rapper mechanisms.
ROTARY VALVE
b. SWING VALVE
Figure 4-50. Hopper discharge valves, (a) Rotary valve and (b) swing valve.
4.5.4 High-Voltage Electrostatic Precipitator Equipment Design
Design of high-voltage electrostatic precipitator equipment is a highly
complex and specialized field. It is therefore important that design decisions
be made only by those qualified by extensive knowledge and experience.
4-99
-------
t
l->
o
o
Figure 4-51. Electrostatic precipitator rapper mechanisms, (a) Pneumatic impulse rapper,
(b) Magnetic impulse rapper, and (c) pneumatic reciprocating rapper.
(Courtesy of Koppers Co. Inc.)
-------
The basic elements of design of electrostatic precipitators involve both
performance requirements and physical requirements. Voltage, electrical
energy, gas velocity, flow distribution, sectionalization, collecting surface
area, treatment time, number and type of discharge electrodes, number and
type of collecting surfaces, collecting surface and discharge electrode spacing,
and number and type of rappers are some performance requirement factors to
consider. Layout, structure, materials handling, and construction material
requirements are some physical factors to consider.
Information on the design of high-voltage ESP is reported by Ramsdell,
, . ., 94-96
White, and Archbold.
4.5.4.1 Conditioning Systems Conditioning systems that change the pro-
perties of the gas stream or the particulate matter are sometimes installed
ahead of the electrostatic precipitator. The need for such a system depends
on the application. Conditioning may involve gas cooling, gas humidification,
air dilution, or the injection of agents such as sulfur trioxide and ammonia.
4.5.4.2 Voltage, Electrical Energy, and Sectionalization Requirements
Voltage, electrical energy, and sectionalization are interrelated. The design
4-101
-------
of the high-voltage electrostatic precipitator should provide for a peak voltage
sufficient for consistent operation of the unit within required performance limits.
The design should also provide for automatic power control and sufficient elec-
trical power to handle all load conditions. When necessary, the design should
provide for sectionalization so that voltage may be adjusted to compensate for
different conditions in different sections of the electrostatic precipitator.
The peak voltage requirements of a high-voltage electrostatic precipita-
tor depend on the application and design, and usually range from 30 to 100 kilo-
volts. Peak voltage requirements depend largely on the spacing of
electrodes and collecting surfaces. The composition, pressure, and tempera-
ture of the gas stream and the concentration of particulate matter in the gas
stream also influence peak voltage design requirements.
For continuous high-efficiency performance, sectionalization usually is
required. The power supply and controls for each precipitator section are
energized separately to prevent power fluctuations from spreading from section
to section. The power controls regulate current, voltage, and sparking. The
number of sections required depends on performance requirements and the
application. For some applications sparking is not desirable. Where sparking
is desirable, there is often an optimum spark rate that will give the best per-
qn
formance. An example of this effect is shown in Figure 4-52.
4.5.4.3 Gas Velocity, Treatment Time, and Flow Distribution Gas veloci-
ties range from 3 to 15 feet per second. Low linear gas velocities promote
4-102
-------
85
z u
Jli UU 75
on
y^
u- z
u-070
65
50 100 150
SPARKS PER MINUTE
Figure 4-52. Variation of precipitator efficiency
with sparking rate for a given fly-
ash precipitator.
deposition and help minimize re-entrainment of particulate matter. The cross-
sectional area of the electrostatic precipitator determines the linear gas
velocity for a given gas volume. Longer treatment time promotes more ef-
fective deposition of particulate matter. The length of the treatment section of
the electrostatic precipitator determines the treatment time for a given linear
gas velocity.
Uniform flow distribution is an important design factor. Perforated
plates are installed at the inlet and sometimes at the outlet of the electrostatic
installed in the inlet and outlet ductwork to
. When it is necessary to install bends or
helpful. Experimental gas
precipitator, and vanes are often
distribute the flow of the gas stream
elbows near the inlet or outlet, turning vanes are
flew models are most useful as an aid to flow distributor design.
4.5.4.4 Collecting Surfaces and Discharge ElectrodesThe number, type,
size, and spacing of collecting surfaces and discharge electrodes required is
331-716 0-69-17
4-103
-------
dependent on the application and desired performance. For a given application,
an increase in the total collecting surface area will usually improve perform-
ance provided adequate corona power is supplied.
4.5.4.5 Materials of Construction Choice of materials for shells, collecting
surfaces, electrodes, hoppers, and other surfaces is governed by cost and
serviceability. Corrosion and temperature resistance are the two most im-
portant factors to consider. Steel construction is used wherever possible;
however, aluminum, lead, concrete, wood, ceramics, plastics, plastic
coated metals, and many other materials can be employed.
4.5.4.6 Collected Particulate Matter Handling SystemsElectrostatic pre-
cipitator hopper walls should be sloped to promote free flow of collected
material. When materials stick or bridge in the hopper, vibrators or rap-
pers should be attached to the outside of the hopper walls at strategic locations.
Hopper outlet valves should be designed to operate freely under all con-
ditions. The hopper discharge system should also be designed to minimize gas
leakage into or cut of the electrostatic precipitator to prevent re-entrainment of
the collected particulate matter.
4.5.4.7 Controls and Instruments Useful controls and instruments are:
1. Individual electrical set controls and indicators.
2. Spark rate indicators.
3. Rapping cycle, frequency, intensity, and duration controls and in-
dicators.
4-104
-------
4. Outlet opacity indicator.
5. Line voltage indicators.
Recorders are useful for providing a permanent record of performance.
Alarms are used to signal when control variables deviate from normal and when
control valves, gates, or conveyors fail to function properly.
4.5.4.8 LayoutAn electrostatic precipitator system should be designed to
conserve space and to minimize costs. Other factors to consider are provision
for future additions of equipment and the effect of the layout on gas flow distribu-
tion.
4.5.5 Specifications and Guarantees
Little published information is available on design criteria for electro-
static precipitators. It is therefore advisable for persons without extensive
knowledge of and experience with the application of electrostatic precipitators
to rely on several different vendors or consultants to furnish specifications.
Forms used by members of the Industrial Gas Cleaning Institute are helpful
for reporting and tabulating necessary information. These forms specify the
information that the vendor needs to make a comprehensive proposal. This
form includes information on:
1. The purchasing company.
2. The proposal.
3. The application.
4. Operating and design conditions.
4-105
-------
5. Properties of the particulate matter and the gas stream.
6. Inlet particulate matter loadings.
7. Desired outlet loadings.
8. Desired efficiency.
When the purchaser lacks sufficient information to complete the form,
the vendor can often draw on his knowledge and experience to supply missing
information or can advise the purchaser on further action. The purchaser may
also retain consultants for guidance.
Industrial Gas Cleaning Institute publication No. EP-4 is useful for bid
evaluation. Major sections of this form relate to:
1. Operating and performance data.
2. Precipitator arrangement.
3. Collecting system.
4. Electrical systems.
5. Other auxiliary equipment and services.
The purchaser should select specifications from the information sub-
mitted by the several vendors. Any differences in equipment or services
proposals should be reconciled by consultation with the vendors or other ex-
perts. The specifications selected should be used to solicit final bids.
4-106
-------
The purchase agreement should include a performance guarantee (when
deisrable), conditions for measuring performance, and specifications. In-
formation that may be used for guidance in the preparation of purchase agree-
ments is published by the Industrial Gas Cleaning Institute.
4.5.6 Maintaining Collection Efficiency
A well designed precipitator properly maintained and operated within
design limits will perform consistently at or above design efficiencies through-
out its serviceable life.
Loss of efficiency is commonly caused by overloading, process changes,
or inadequate maintenance. Increasing output or process gas flows
without adding precipitator sections usually reduces electrostatic precipitator
efficiency. Changes in raw materials, products, fuels, and gas stream con-
ditions can also lead to poor performance. If these factors are anticipated in
the original design, loss of efficiency can often be avoided.
It is not always possible to anticipate changes in the properties of
particulate matter and the gas stream. It is therefore important that collec-
: tor performance be monitored frequently by sampling the outlet gas stream.
When inspection and maintenance fail to bring performance to within design
.limits and overloading is not a factor, the cause of poor performance is usually
traceable to changes in properties of the particulate matter or the gas stream.
Should this occur, consultation with the manufacturer of the equipment or with
other experts is in order.
4-107
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4.5.7. Improvement of Collection Efficiency
Process changes or changes in air pollution control requirements may
make it necessary to improve the efficiency of an electrostatic precipitator.
When no provision has been made for future additions, it may be less costly to
scrap the older unit and to install a modern, more efficient unit. If provision
has been made originally for layout and installation of additional units to
increase capacity, the changes may be made at nominal cost.
Before action is taken to improve efficiency, all of the elements of design
mentioned in Section 4. 5.4 should be considered and compared with process re-
quirements. The modifications required will depend on the degree of improve-
ment required and the application.
When process conditions have changed, changing the voltage or power
supply of the unit may improve the performance. Increasing the number of
high-tension bus sections may at times improve performance. The installation
of automatic power controls alone seldom results in significant improvement;
however, use of this technique in conjunction with other techniques such as in-
creased sectionalization is often effective.
Installing additional high-voltage electrostatic precipitator sections is
the most common technique for improving collection efficiency. At times ef-
ficiency may be improved sufficiently by distributing the flow more uniformly
within the unit or in the ductwork leading to the unit. In exceptional cases,
modification of material handling systems may bring about the necessary
improvement.
4-108
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Changing the temperature of the gas stream or injecting other materials
,,. . 101, 102
into the gas stream may improve efficiency. Whenever
foreign materials are injected the air pollution aspects of these materials
should be considered.
4.5.8 Typical Applications
High-voltage electrostatic precipitators have been used sucessfully to
collect a wide variety of solid and liquid particles. Various applications for
high-voltage electrostatic precipitators are included in Table 4-2.
4.5.8.1 Pulverized Coal-Fired Power PlantsThe arrangement in Figure 4-53
depicts a pulverized coal unit. Typical of older systems, the mechanical
precleaner (multiple cyclone) and the electrostatic precipitator are located
downstream of the air heater. Gases range in temperature from 220° to
350° F. The best precleaners seldom exceed 80 percent efficiency. Assuming
an 80 percent cleanup, the electrostatic precipitator would have to collect 95
percent of the remaining particulate matter to achieve an overall efficiency
of 99 percent. When soot is blown,particulate matter concentrations are well
in excess of average emission levels.
A recently installed collection system locates the electrostatic preci-
pitator before, instead of behind, the air heater on a large steam generator.
4-109
-------
STEEL SUPPORT LEVEL
FAN
ASH CONVEYOR
ROOF LEVEL
Figure 4-53. Electrostatic precipitator installed after air heater in power plant steam generator system.
4-110
-------
The collector is rated at 99 percent efficiency and handles gases at from
600° to 700° F. In this temperature range resistivity of particles is favorable
for collection; particularly for fly ash generated from low sulfur coals and
residual fuel oil. Installations of this type must handle greater volumes of gases
and, therefore, are more expensive. Long-term evaluations are necessary to
compare the performance of this unit with cold-side electrostatic precipitators
of the same rating.
4.5.8.2 Integrated Steelmaking Operations High-voltage electrostatic pre-
cipitators are frequently used in integrated steel plants. A common application
is the detarring of coke oven gas. Wet-type electrostatic precipitators are
used for final cleaning of blast furnace gases. Exit loadings as low as 0. 005
"1 (~\ Q 1 n C
grain per standard cubic foot have been reported for this application.
High-voltage electrostatic precipitators applied to sintering strands reportedly
reduce particulate emission concentrations to less than 0.04 grain per standard
, . , . 107-109
cubic foot.
Precipitator equipment applied to oxygen-lanced open hearths, basic
oxygen furnaces, and electric arc furnaces reduces particulate emission levels
io less than 0. 05 grain per standard cubic foot. '
j, 5.8. 3 Cement Industry Electrostatic precipitator system efficiencies in
excess of 98 percent have been reported for dry-process rotary cement kiln
1 1 £
Applications. Efficiencies exceeding 99 percent have been reported for
electrostatic precipitator systems applied to wet-process rotary cement
.ilns.116
4-111
-------
4.5.8.4 Kraft Pulp Mills The electrostatic precipitator is a common gas
cleaning device used on kraft mill recovery furnaces. A survey of 50 plants
indicated that the rated efficiency of electrostatic precipitators installed
117
ranged from 90 to 98 percent. In some applications efficiencies of at least
1 I Q
99 percent have been reported. Electrostatic precipitators have been ap-
plied to emissions from kraft mill lime kilns.
4. 5. 8. 5 Sulfuric Acid The efficiency of electrostatic precipitators in re-
moving acid mist from contact-type sulfuric acid manufacturing processes
119
ranges from 92 to 99. 9 percent.
4-112
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4.6 LOW-VOLTAGE ELECTROSTATIC PRECIPITATORS
The low-voltage, two-stage, electrostatic precipitator is a device
.originally designed to purify air, and is used in conjunction with air-
conditioning systems. Cleaning of incoming air at hospitals and industrial
and commercial installations is also a major use for the low-voltage
precipitator, and it is sometimes called an air conditioning precipitator or
120
electronic air filter. As an industrial particulate matter collector, the
device is used for the control of finely divided liquid particles
discharged from such sources as meat smokehouses, asphalt paper saturators.
pipe coating machines, and high-speed grinding machines.
Low-voltage precipitators are limited almost entirely to the collection
of liquid particles, which will drain readily from collector plates. Two-
stage precipitators cannot control solid or sticky materials, and become
ineffective if concentrations exceed 0.4 grain per standard cubic foot.
There is a limited number of ways of removing collected materials
from the two-stage precipitator. This limitation causes the primary use of
the equipment to be restricted to systems with low grain loadings in which
the collector plates need to be cleaned only at infrequent intervals. This has
been a deterrent to widespread use of two-stage precipitators in air pollution
control. Also, electrostatic precipitators do not collect or remove gases
or vapors responsible for objectionable odors and eye irritation.
4-113
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4. 6.2 Major Components of Low-Voltage Electrostatic Precipitators
The feature of the low-voltage precipitator (Figure 4-54) that distin-
guishes it from the high-voltage electrostatic precipitator is the
121
separate ionizing zone located ahead of the collection plates. The ionizing stags
consists of a series of fine ( 0. 007-inch diameter) positively charged wires
equally spaced at distances of from 1 to 2 inches from parallel grounded
tubes or rods. A corona discharge between each wire and a corresponding
tube charges the particles suspended in the air flowing through the ionizer.
The direct-current potential applied to the wires amounts to 12 or 13 kilovolts.
Positive polarity is regularly used to minimize the formation of ozone.
The second stage consists of parallel metal plates usually less than an
inch apart. In some designs, alternate plates are charged positively and
negatively, each to a potential of 6 or 6-1/2 kilovolts direct current, so that
the potential difference between adjacent plates is 12 or 13 kilovolts.
In other cases, plates are alternately charged to a positive potential
of 6 to 13 kilovolts and grounded. (The lower voltages are used with closely
spaced plates.) This arrangement is shown in Figure 4-54. The illustration
shows particles entering at the left,receiving a positive charge in the ionizer,
and being collected at the negative plates in the second stage. Liquids drain
by gravity to a pan located beneath the plates. Rapping or shaking is not
employed, primarily because of the close spacing of plates.
4-114
-------
GAS
FLOW-
FIELD
RECEIVER
ELECTRODE
IONIZER
STAGE
DUST
PARTICLE
PATH
COLLECTOR
STAGE
1st STAGE
EMITTER WIRES AND
ELECTROSTATIC FIELDN
10,000-12,000 VOLTS
2nd STAGE
EMITTER PLATES (+)
6,000-8,000 VOLTS
GROUNDED
COLLECTOR PLATES (-)
ITTER WIRE (+)
GAS
FLOW
DUST-
DUST
PATH
O
EMITTER PLATE
6,000-8,000 VOLTS (+)
FIELD RECEIVER
ELECTRODES (-)
GROUNDED
COLLECTOR PLATES (-)
Figure 4-54. Operating principle of two-stage electrostatic preclpitator.
4-115
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The package unit shown in Figure 4-55 is used to collect oil mist from
122
grinding machines. Oil droplets agglomerate on the plates and drain to
the bottom. Because solids or viscous liquids will not drain freely,
systems removing such materials have to be shut down occasionally for
cleaning of the plates to prevent arcing.
Semiviscous materials can be collected by the low-voltage precipitator
if an adequate washing system is provided. The frequency of washing will
depend on the inlet loading and the characteristics of the collected participate
matter.
4. 6. 3 Auxiliary Equipment
Pretreatment of particles may be required to improve their electrical
properties before they enter the precipitator. The system shown in Figure 4-56
includes a low-pressure scrubber, mist eliminator, and tempering coil to
control temperature and humidity. Removal of large particles by the scrubber
allows longer operating periods without shutdown for cleaning of the electrostatic
precipitator. Mist eliminators remove water droplets and prevent excessive
sparkover. Heating coils allow flexibility in setting optimum conditions. For
many materials, a relative humidity greater than 50 percent in the gas stream
is beneficial.
4.6.4 Design Parameters
When a low-voltage electrostatic precipitator is used in conjunction with
air conditioning, velocities range between 5 and 10 feet per second (fps).
However, for pollution control purposes, where the particulate loadings are
4-116
-------
I
I'
II
-
-------
MIST
ELIMINATOR
l
i-*
ii
oo
DIRTY
GAS
FLOW
LOW
PRESSURE
SCRUBBER
JK
/
^
PERFORATED
PLATE /
A°
/ ;
A A ".
v
;\
\ G \
TEMPERING \
C01L IONIZER\
STAGE
\ .
COLLECTOR _\
STAGE
CLEAN
GAS -
FLOW
COLLECTED
OILS OUT
Figure 4-56. Two-stage electrostatic precipitator with auxiliary scrubber, mist eliminator, tempering
coil, and gas distribution plate (top view).
-------
much higher, the superficial gas velocity through the plate collector section
should not exceed 1. 7 fps. The relationship between air velocity and collection
efficiency is illustrated by the Penney equation which assumes streamline flow.
The Penney (1937) equation for two-stage precipitators is:
wL
vd
where:
F = efficiency expressed as a decimal.
w = drift velocity, feet per second.
L = collector length, feet.
v = gas velocity through collector, feet per second.
d= distance between collector plates, feet.
The upper limit for streamline flow through these two-stage precipitators is
600 feet per minute (fpm). Mechanical irregularities in units now manufactured
may reduce this upper limit.
4-11 Q
331-716 O - 69 - IB
-------
The effect of gas velocity on collection efficiency for several industrial opera-
tions is shown in Figure 4-57. Efficiencies of 80 percent and greater are
shown for the collection of oil mist at asphalt paper saturators and for air
conditioning applications. Collection efficiencies ranging from 60 to 80
percent are possible for meat smokehouses at a velocity of I. 5 fps. For
smokehouses, collection decreases rapidly at higher velocities. Test data for
typical installations are shown in Table 4-7.
The practical voltage limit for low-voltage precipitators is 18 kilovolts.
Most units operate at 10 to 13 kilovolts. Current flow under these conditions
is small (4 to 10 milliamperes). The collecting plates are usually energized
at 5. 5 to 6. 5 kilovolts, but potentials up to 13 kilovolts are possible. Actual
current flow is small because no corona exists between the plates.
The degree of ionization may be increased by increasing the number of
ionizing electrodes, either by decreasing spacing or by installing a second
set of ionizing wires in series. Because decreased spacing requires reduced
voltage to prevent sparkover, there appears to be an advantage in
the series arrangement. Decreased spacing, however, lowers first cost and
space requirements.
Low-voltage precipitators of standard design for capacities up to
20, 000 cfm are supplied by manufacturers in preassembled units requiring
only external wiring and duct connections. The installed weight of the
precipitator is approximately 80 pounds per square foot of cross-sectional
4-120
-------
I
H1
(S3
100
90
- 80
c
(J
u
70
60
50
O 40
H
U
O
U
30
20
10
0
A. SMOKEHOUSES, EXTRAPOLATED WITH PENNEY EQUATION (OPERATING TEST DATA
FOLLOW CLOSELY).
B. ASPHALT SATURATOR, OPERATING TEST DATA.
C,D. AIR CONDITIONING, MANUFACTURER'S RECOMMENDATION.
I I I I I I _L
1.5
GAS VELOCITY, ft/sec
Figure 4-57. Efficiency of two-stage precipitator as function of velocity for several industrial
operations.
-------
Table 4-7. INDUSTRIAL OPERATION OF TWO-STAGE PRECIPITATORS
121
Contaminant
source
Tool grinding
Meat smokehouse
Meat smokehouse
Deep fat cooking
Asphalt saturator
(roofing paper)
Muller-type mixer
Contaminant
type
Oil aerosol
Wood smoke,
vaporized fats
Wood smoke,
vaporized fats
Bacon fat aerosol
Oil aerosol
Phenol-formal-
dehyde resin
Ionizing
voltage
13,000
13,000
10,000
13,000
12,000
13,000
Number of
ionizer
banks
1
2
1
2
1
1
Collector
voltage
6,500
6,500
5,000
6,500
6,000
6,500
Efficiency,
wt %
90
90
50
(75% opacity
reduction)
85
87
Velocity,
fpm
333
60
50
68
145
75
Inlet
concentration
gr/scf
0.103
0.181
0.384
0.049
to
to
-------
area measured perpendicular to the gas flow. These standard units are
usually sized so that the air flow for air pollution applications is about 100 fpm.
4.6.5 Materials of Construction
The standard material used in the construction of low-voltage precipita-
te r collector cells is aluminum. The precipitator housing is usually made of
galvanized steel and frames are of aluminum. Where washing is to be frequent
and even mildly corrosive conditions exist, ionizer wires should be made of
stainless steel.
4. 6. 6 Typical Applications of Low-Voltage Electrostatic Precipitators
Applications of low-voltage precipitators to air pollution control have
developed slowly since 1937 when the first installation was successfully used
to collect ceramic overspray from pottery glazing operations. Other applica-
tions have been the collection of oil mist from high-speed grinding machines and
the cleaning of gases from deep fat fryers, asphalt saturators, rubber curing
ovens, and carpet mill dryers. See Table 4-7 for operational data.
4. 6. 6.1 Machining Operations High speed grinding machines generate mist
from cutting oils, which must be vented from the working area. Package
units of the type shown in Figure 4-55 are used to collect the mist. A filter
is provided ahead of the precipitator to remove metal chips and any other
large particles. Concentrations of solids and tars are usually low enough to
be flushed from the plates with the collected oil droplets.
4-123
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4.6.6.2 Asphalt SaturatorsIn the manufacture of roofing paper, low-voltage
electrostatic precipitators are used to remove the steam-distilled organic
materials from hot liquid asphalt. Moisture evolved from the paper carries
oil from the process. Oils that are collected flow readily from the plates of the
electrostatic precipitator; only occasional cleaning is required.
4.6.6.3 Meat SmokehousesSmokehouses are used by meat packing houses to
cook and smoke a variety of products. During the cooking cycle, exhaust
products are reasonably innocuous and exhaust gases can be discharged directly
to the atmosphere. Smoke generated from hardwood sawdust contains liquid
aerosols, most of which are partially oxidized organics. In addition to aerosols,
odorous, eye-irritating gases and vapors are discharged in exhaust products.
Two-stage precipitators have been used with limited success to control
visible aerosols from smokehouses. All such operations use the design of
Figure 4-56 with a scrubber, mist eliminator, and tempering coil. Under
optimum operation, these units have reduced visible emissions to about 10
percent opacity. Maintenance is a problem, however and the exhaust gases
have a strong odor and a lachrymose character.
The collected particles are principally tars and gums. When the unit is
warm (120 to 180° F), at least some of these tars drain from the plates.
4-124
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When the plates are not cleaned regularly, arcing occurs in the collector
section, particularly near the lower edges of the plates.
4. 6. 6.4 Other Applications Two-stage precipitators offer the promise of a
low-cost control device for such operations as rubber curing and carpet mill
drying, where oil mists are generated. Conceivably, these devices can be used
wherever the liquid separates easily from the plates and wherever other
considerations such as odors and eye irritants are not a problem.
4. 6. 7 Air Distribution
Proper air distribution through the precipitator is essential for efficient
collection. Precipitators are usually installed with horizontal air flow and
frequently in positions requiring abrupt changes in gas flow preceding the
unit. Installations of this type can result in turbulent and uneven flow with
high local velocities, leading to low overall efficiencies.
Where a straight section of at least 8 duct diameters is not available
ahead of the precipitator, mechanical means for balancing the air flow must
be used. Several types of distribution baffles and turning vanes have been
devised. The most effective device has been found to be one or more perfor-
ated sheet metal plates fully covering the cross section of the plenum preced-
ing the ionizers. The optimum open area for the plate is about 40 percent of
the cross-section.
4-125
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4. 6. 8 Maintenance
To assure optimum performance, the internal parts of the precipitator
must be kept clean enough to prevent arcing. In addition, voltages have to be
held within proper ranges, and plate and wire spacings have to be maintained
within reasonably small tolerances.
The frequency of internal washing will depend on the application.
High particulate loadings in the gas stream and sticky materials
present the greatest problems. On the other hand, two-stage precipitators
can be operated indefinitely where relatively clean, free-flowing oils are
collected.
4-126
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4.7 FABRIC FILTRATION
4.7.1 Introduction
One of the oldest and most positive methods for removing solid particulate
123
Contaminants from gas streams is by filtration through fabric media. The
fabric filter is capable of providing a high collection efficiency for particles as
small as 0. 5 micron and will remove a substantial quantity of particles as
124
small as 0.01 micron.
With a fabric filter, the dust-bearing gas is passed through a fabric in
such a manner that dust particles are retained on the upstream or dirty-gas
side of the fabric while the gas passes through the fabric to the downstream or
clean-gas side. Dust is removed from the fabric by gravity and/or mechanical
125
means. The fabric filters or bags are usually tubular or flat.
The structure in which the bags hang is known as a baghouse. The number
of bags may vary from one to several thousand. The baghouse may have one
compartment or many so that one may be cleaned while others are still in
service. Figure 4-58 illustrates one type of baghouse.
4.7.1.1 Range of ApplicationApproximately 80 percent of all manufacturing
plants contain operations that produce dust and particles of such a small size
123
that use of a highly efficient collection device such as a baghouse is desirable.
In many cases, a fabric collector is an integral component of the plant operation.
4-127
-------
CLEAN AIR
OUTLET
* CELL PLATE
s
Figure 4-58. Typical simple fabric filter bag-
house design.
4-128
-------
For example, filters are used to collect metal oxides, carbon black, and
dehydrated milk, and to recover reusable materials such as nonferrous
i 126
grinding dusts.
In other cases, fabric collectors are used to reduce equipment maintenance.
to improve product quality, to filter ventilation air entering a clean room, to
prevent physical damage to the plant or equipment, and usually to collect mists,
1 O/"*
fumes or particulate matter that contribute to atmospheric pollution.
The initial selection of gas cleaning equipment for a given plant frequently
is made on the basis of past performance of the equipment. However, in making
a choice, the ability of the equipment to continue satisfactory operation under
anticipated conditions must also be considered. In short, design collection
efficiency is not the sole criterion of performance. The ability of the equip-
ment to continue high collection efficiency throughout its lifetime is also
important. Other parameters considered in the selection are the costs of
purchase, operation, and maintenance (detailed in Section 6), as well as a
variety of technical factors (listed in Section 4. 7. 4).
4.7.2 Mechanisms of Fabric Filtration
The particulate matter is removed from the air or gas stream by
1 9V
impinging on or adhering to the fibers. ' The filter fibers are usually
woven with relatively large open spaces, sometimes 100 microns or larger.
The filtering process is not simple fabric sieving, as can be seen by the fact that
4-129
-------
high collection efficiency for dust particles 1 micron or less in diameter has
been achieved. Small particles are initially captured and retained on the
fiber of the fabric by direct interception, inertial impaction, diffusion,
electrostatic attraction, and gravitational settling. Once a mat or cake of
dust is accumulated, further collection is accomplished by mat or cake
sieving as well as the above mechanisms. Periodically the accumulated
dust is removed, but some residual dust remains and serves as an aid to
further filtering.
4. 7.2.1 Direct Interception Air flow in fabric filtration is usually laminar.
Direct interception occurs whenever the fluid streamline, along which a particle
approaches a filter element, passes within a distance from the element equal
to or less than one half the particle diameter. If the particle has a very
small mass it will not deviate from the streamline as the streamline curves
around the obstacle, but because of van der Waal forces it will be attracted
to and adhere to the obstacle if the streamline passes sufficiently close to
130
the obstacle. (See path A in Figure 4-59 for illustration.)
4. 7. 2. 2 Inertial Impaction Inertial impaction occurs when the mass of the
particle is so great that it is unable to follow the streamline rapidly curving
1 OA
around the obstacle and continues along a path of less curvature, so that the
particle comes closer to the filter element than it would have come if it had
approached along the streamline. Collision occurs because of this inertia
4-130
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A DIRECT
INTERCEPTION
B INERTIAL IMPACTION
c ELECTROSTATIC ATTRACTION effect even when flow line intercep-
tion would not take place. (See path
B in Figure 4-59). Impaction is not
a significant factor in collecting par-
ticles of 1 micron diameter or less.
Impaction is considered significant
for the collection of particles of two
Figure 4-59. Streamlines and particle trajectories
approaching filter elements. (Df repre- microns diameter and becomes the
sents the filter element diameter; Dp
the diameter of the particles; Vo is the
velocity of the gas stream.) predominant factor as particle size
131
increases.
4.7.2.3 DiffusionFor particles ranging in size from less than 0.01 to
0.05 micron diameter, diffusion is the predominant mechanism of deposi-
tion. Such small particles do not follow the streamline because collision
with gas molecules occurs, resulting in a random Brownian motion that
increases the chance of contact between the particles and the collection
surfaces. A concentration gradient is established after the collection of a
few particles, and acts as a driving force to increase the rate of deposition.
Lower air velocity increases efficiency by increasing the time available for
131
collision and therefore the chance of contacting a collecting surface.
4-131
-------
4.7.2.4 Electrostatic Attraction Electrostatic precipitation will result from
electrostatic forces drawing particles and filter element together whenever either
or both possess a static charge. (See path C in Figure 4-59.) These forces
may be either direct, when both particle and filter are charged; or induced,
when only one of them is charged. Such charges are usually not present un-
less deliberately introduced during the manufacture of the fiber. Electrostatics
assists filtration by providing an attraction between the dust and fabric, but it
also affects particle agglomeration, fabric cleanability, and collection efficiency.
A triboelectric series of filter fabrics may be useful in selecting fabric with
132
desirable electrostatic properties.
4.7.2.5 Gravitational Settling Settling of particles by gravity onto the filter
surface may result from particle weight as the particle passes through the
filter. A simple method of judging the usefulness of a mechanism, based on
133
particle size, is shown in Table 4-8.
4.7.3 Filter Eesistance
Two forms of resistance, clean cloth resistance and dust mat resistance,
affect the design of baghouses containing fabric filters.
4.7.3.1 Clean Cloth Resistance The resistance to air flow offered by clean
filter cloth is determined by the fiber of the cloth and the manner in which the
fibers are woven together. A tight weave offers more resistance than a loose
weave at the same air flow rate and, because the air flow is laminar, resistance
varies directly with air now. One of the characteristics of filter fabrics
4-132
-------
Table 4-8. CONTROL MECHANISM FOR PARTICLE SIZE COLLECTION
133
Primary collection mechanism
Direct interception
Impingement
; Diffusion
Electrostatic
Gravity
Diameter of particle, microns
0.001 to 0.5
0.01 to 5
4-133
-------
frequently specified is the American Society for Testing and Materials (ASTM)
permeability, which expresses the air volume in cubic feet per minute passing
through a square foot of clean new cloth with a pressure differential of 0.50 inch
water gauge. The usual range of values is from 10 to 110 cfm per square foot.134
With normal design conditions, the resistance of the clean cloth does not exceed
0. 10 inch of water gauge and is often less. The average flow rate in use for an
operating cloth is 1. 5 to 3.0 cubic feet per minute per square foot of woven cloth.
This is known as the air-to-cloth ratio or the filtering velocity in feet per
134
minute.
4.7.3.2 Dust Mat Resistance The pressure drop of the dust mat at the end of
any elapsed time is related to the concentration of dust in the gas stream, the
mass density of the gas, and the face velocity of the gas through the fabric by
the equation:
where:
(Ap ) , = pressure drop of the dust mat, inches of water
t Ulclt
t - elapsed time, seconds
G = dust concentration in gas stream, Ib/ft
P = mass density of gas, slugs /ft3
g = acceleration of gravity, ft/sec
v = face velocity of gas through the fabric, ft/sec.
K = resistance coefficient
C = dimensional constant
The values of K, the resistance coefficient modified to include a factor for con-
version of dust cake thickness to mass with constant viscosity, must be deter-
mined experimentally. C is a dimensional constant adjusted as required for the
101 1 QR
actual units used. '
K values are usually determined by means of a scale model unit either in
the laboratory or in the field. Care must be exercised in applying such
4-134
-------
1 O C*
results to a full-scale unit. If a vertical bag is used, elutriation of par-
ticles may occur so that the true value of K varies with time and position on
-I o/2
the bag. The measured value of K is an average value that may not be the
same when the scale or the configuration is changed. This is borne out by failure
of some full-scale units to function as anticipated on the basis of pilot studies.
135
Table 4-9 gives K values for a number of dusts. These data were
obtained by laboratory experiments using an air flow of 2 cubic feet per
minute through 0. 2 square foot of cloth area (equivalent to a filtering velocity
of 10 ft/mm). The tests were terminated at a maximum pressure differen-
tial of 8 inches of water column.
Investigators have found that K varies as a power function of the filter
137
velocity, and velocities greater than 2. 3 ft./min. seriously affect the K
I O Q
value of the fly ash being studied. ° These recent studies indicate that K
values listed in Table 4-9 should be used only for estimates. Further research
is needed to define more precisely the factors affecting the resistance
coefficients of filter cakes. The values in Table 4-9 may be used when such
limitations are considered.
The pressure drop across the collected dust increases uniformly with
time, indicating a linear relationship between resistance and the thickness of
the accumulated dust mat. The data clearly show a trend of increasing resist-
ance with decreasing particle size. In a full-scale baghouse, particularly if
relatively long vertical bags are used, a substantial amount of elutriation can
331-716 0-69-1
4-135
-------
Table 4-9. FILTER RESISTANCE COEFFICIENTS (K) FOR
INDUSTRIAL DUSTS ON WOVEN FABRIC FILTERS135
Dusts
Granite
Foundry
Gypsum
Feldspar
Stone
Lampblack
Zinc oxide
Wood
Resin (cold)
Oats
Corn
Filter resistance coefficients (K)
for particle size smaller than
20 meshb> c
1.58
0.62
0.96
1.58
0.62
140 meshb> c
2.20
1.58
0.62
375 meshb'd
3.78
6.30
6.30
1.58
90 nd'e
6.30
6.30
9.60
3.78
45/nd'e
11.0
8.80
20 £
19.8
18.9
27.3
25.2
2Mf
-
47.2
15. 7g
a
K = inches water gauge per pound of dust per square foot per foot per minute of
filtering velocity.
b
U. S. standard sieve.
Coarse, smaller than 20 mesh or 140 mesh.
Medium, smaller than 350 mesh, 90 \± or 45 p..
Theoretical size of silica; no correction made for materials having different
densities.
Fine, smaller than 20 (j. or 2 (i.
Flocculated material, not dispersed, size actually larger.
4-136
-------
139
be expected. The dust-laden gas usually enters the filter bag at the bottom
and travels upward. As the gas filters through the cloth, its upward velocity
decreases so that only very fine dust remains airborne to be deposited on the
upper portion of the bag. Because the actual pressure loss through the bag
must be the same through all areas, the volume and filtering velocity through
1 Q C
some portions of the bag reach high values. Investigators found that local
filtering velocities vary by a factor of 4 or more throughout a single filter
139
bag. This, in turn, may lead to collapse or puncture of the filter cake.
Punctures (small holes in the dust mat) are usually self-repairing because the
increased air flow through the small area of low resistance brings more dust
with it. Collapse of the filter cake, on the other hand, is a shift in cake
structure to a more compacted condition with a greater resistance.
Collapse and puncture of the filter cake are phenomena caused by
excessive filtering velocities. Some dust is embedded and remains in the
interstices of the cloth when puncture or collapse occurs so that normal
cleaning does not completely remove this dust. The embedded dust "blinds"
or plugs the fabric pores to such an extent that the fabric resistance becomes
permanently excessively high. Once begun, blinding becomes worse rapidly.
For example, transient local filtering velocities of 100 ft/min through areas of
139
puncture were found when the average filtering velocity was only 0. 75 ft/min.
jj.3.3 Effect of Resistance on Design Resistance of the cloth filter and
dust cake cannot be divorced from the total exhaust system. The operating
4-137
-------
characteristics of the exhaust blower and the duct resistance determine the
ways in which increases in the baghouse resistance affect the gas rate. If the
blower performance curve is steep, the gas flow rate may be reduced only
131
slightly when the resistance of the filter bags changes markedly. Some varia-
tion in resistance and air volume occurs normally in all baghouses. Proper
design requires that the volume be sufficient to capture the emissions at the
source when the system resistance is maximum and the gas volume minimum.
To prevent blinding of fabric from particle impaction, the filter ratio must
not be excessive immediately after cleaning when the pressure drop is at a
minimum and the air volume at a maximum.
4.7.4 Equipment Description and Design
The selection or design of industrial dust collection equipment requires
consideration of many factors. Figure 4-60 illustrates the complex nature of
the final selection of a fabric collector. Exhaust system design considerations
include:
1. Determination of the minimum volume to be vented from the basic
equipment.
2. Estimation of the maximum desirable resistance.
3. Selection of the blower operating point that will provide the
minimum required volume at the maximum system resistance.
4. Estimation of the minimum resistance for the condition immediately
after a thorough cleaning of the filter bags.
41 OQ
-loo
-------
BAG ECONOMICS
I
ii
to
DUST AND GAS CHEMISTRY-
DUST AND GAS TEMPERATURE-»J
PHYSICAL CHARACTERISTICS
OF DUST AND GAS STREAM
DUST PARTICLE
SIZE DISTRIBUTION"
DESIRED COLLECTION
EFFICIENCY
GAS DEW POINT
GAS TEMPERATURE
EQUIPMENT
MAINTAINABILITY'
ECONOMICS
FABRIC SELECTION-
PROCESS FACTORS-
.AIR TO CLOTH.
RATIO
. FILTER SURFACE
AREA
BAGHOUSE
HOUSING
FILTRATION CYCLE
FABRIC FILTER
"COLLECTOR DESIGN
-PRECLEANERS
VOLUME
INLET DUST
LOADING
PRODUCT
"REQUIREMENTS
DESIRED
COLLECTION
EFFICIENCY
CLEANING.
ENERGY ECONOMICS-
BAG ECONOMICS
PRODUCT HANDLING-
Figure 4-60. System analysis for fabric filter collector design.
-------
5. Determination of a second operating point on the blower character-
istic curve for the clean bag condition.
6. Determination of the minimum filtering area required by the
maximum filtering velocity permissible for the particular dust or
fume being collected.
7. Rechecking of the calculations, with the filtering area thus
determined, to assure compatibility.
The rule of thumb for air-to-cloth ratios for conventional baghouses
with woven-cloth, fabric filters is 1.5 to 3. 0 cubic feet per minute per
square foot for dusts and 1. 0 to 2. 0 cubic feet per minute per square foot for
fumes. The pressure drop for the woven cloths normally ranges from 2 to 8
inches of water. Physical characteristics of bag fabrics tested in a pilot
plant are given in Table 4-10. Typical relationships between filter ratio and
140
pressure drop across bags for the three fabrics in Table 4-10 are shown
140
in Figure 4-61.
Typical filter ratios and dust conveying velocities for various dusts and
fumes collected in woven cloth bags are shown in Table 4-11.
The rule of thumb for air-to-cloth ratios for reverse jet baghouses with
felted or napped woven fabric filters is 10 to 16 cubic feet per minute per
square foot of cloth for dust, and 6 to 10 cubic feet per square foot of cloth
for fumes. Table 4-12 shows typical filter ratios of fabrics used for various
dusts and fumes being collected in reverse jet bag-houses.
4-140
-------
Table 4-10. PHYSICAL CHARACTERISTICS OF BAG FABRICS
TESTED IN PILOT PLANT140
Material
Thread count
Yarn type
Warp
Fill
Weave
Weight, oz/sq yd
ASTM permeability
Fabric
A
Silicon! zed glass
54 X 52
Filament
Filament
Crowfoot
9.36
15-20
B
Siliconized Dacron
73 X 68
Filament
Filament
Twill
4.59
25-35
C
Siliconized glass
65 X 35
Filament
Staple
Twill
9.00
60-80
4-141
-------
Table 4-11. RECOMMENDED MAXIMUM FILTERING RATIOS AND DUST
CONVEYING VELOCITIES FOR VARIOUS DUSTS AND FUMES IN
CONVENTIONAL BAGHOUSES WITH WOVEN FABRICS141
Dusts or fumes
Abrasives
Alumina
Aluminum oxide
Asbestos
Baking powder
Batch spouts for grains
Bauxite
Bronze powder
Brunswick clay
Buffing wheel operations
Carbon
Cement crushing and grinding
Cement kiln (wet process)
Ceramics
Charcoal
Chocolate
Chrome ore
Clay
Cleanser
Coca
Maximum filtering
ratios,
cfm/ft" cloth area
3.0
2.25
2.0
2. 75
2.25 - 2. 50
3.0
2.5
2.0
2.25
3.0 - 3.25
2. 0
1. 5
1.5
2.5
2.25
2.25
2. 5
2.25
2.25
2.25
Branch pipe
velocity,
fpm
4500
4500
4500
3500 - 4000
4000 - 4500
4000
4500
5000
4000 - 4500
3500 - 4000
4000 - 4500
4500
4000 - 4500
4000 - 4500
4500
4000
5000
4000 - 4500
4000
4000
4-142
-------
Table 4-11. RECOMMENDED MAXIMUM FILTERING RATIOS AND DUST
CONVEYING VELOCITIES FOR VARIOUS DUSTS AND FUMES IN
CONVENTIONAL BAGHOUSES WITH WOVEN FABRICS (Continued)
Dusts or fumes
Coke
Conveying
Cork
Cosmetics
Cotton
Feeds and grain
Feldspar
Fertilizer (bagging)
Fertilizer (cooler, dryer)
Flint
Flour
Glass
Granite
Graphite
Grinding and separating
Gypsum
Iron ore
Iron oxide
Maximum filtering
ratios,
cfm/ft^ cloth area
2.25
2.5
3.0
2.0
3. 5
3.25
2. 5
2.4
2. 0
2.5
2. 5
2. 5
2.5
2. 0
2.25
2. 5
2. 0
2.0
Branch pipe
velocity,
fpm
4000-4500
4000
3000-3500
4000
3500
3500
4000-4500
4000
4500
4500
3500
4000-4500
4500
4500
4000
4000
4500-5000
4500
4-143
-------
Table 4-11. RECOMMENDED MAXIMUM FILTERING RATIOS AND DUST
CONVEYING VELOCITIES FOR VARIOUS DUSTS AND FUMES IN
CONVENTIONAL BAGHOUSES WITH WOVEN FABRICS (Continued)
Dusts or fumes
Lampblack
Lead oxide
Leather
Lime
Limestone
Manganese
Marble
Mica
Oyster shell
Packing machines
Paint pigments
Paper
Plastics
Quartz
Rock
Sanding Machines
Silica
Soap
Maximum filtering
ratios,
cfm/ft cloth area
2.0
2.25
3.5
2.0
2.75
2.25
3.0
2.25
3.0
2.75
2.0
3.5
2.5
2.75
3.25
3.25
2.75
2.25
Branch pipe
velocity,
fpm
4500
4500
3500
4000
4500
5000
4500
4000
4500
4000
4000
3500
4500
4500
4500
4500
4500
3500
4-144
-------
Table 4-11. RECOMMENDED MAXIMUM FILTERING RATIOS AND DUST
CONVEYING VELOCITIES FOR VARIOUS DUSTS AND FUMES IN
CONVENTIONAL BAGHOUSES WITH WOVEN FABRICS (Continued)
Dusts or fumes
Soapstone
Starch
Sugar
Talc
Tobacco
Wood
Maximum filtering
ratio,
cfm/ft^ cloth area
2.25
2. 25
2.25
2.25
3.5
3.5
Branch pipe
velocity,
fpm
4000
3500
4000
4000
3500
3500
4-145
-------
Table 4-12. RECOMMENDED MAXIMUM FILTERING RATIOS AND FABRIC
FOR DUST AND FUME COLLECTION IN REVERSE-JET BAGHOUSES142
Material or operation
Aluminum oxide
Bauxite
Carbon, calcined
Carbon, green
Carbon, banbury mixer
Cement, raw
Cement, finished
Cement, milling
Chrome, (ferro) crushing
Clay, green
Clay, vitrified silicious
Enamel, (porcelain)
Flour
Grain
Graphite
Gypsum
Lead oxide fume
Lime
Fabric
Napped cotton
Cotton sateen
Napped cotton, wool felt
Orion felt
Wool felt
Cotton sateen
Cotton sateen
Cotton sateen
Cotton sateen
Cotton sateen
Cotton sateen
Napped cotton
Cotton sateen
Wool felt, cotton sateen
Wool felt
Cotton sateen, orlon felt
Orion felt, wool felt
Napped cotton
Filtering
ratios, cfm/ft2
11
10
8a
7
8
9
10
8
10
10
12
12
14a
16
7a
10
8a
10
4-146
-------
Table 4-12. RECOMMENDED MAXIMUM FILTERING RATIOS AND FABRIC
FOR DUST AND FUME COLLECTION IN REVERSE-JET BAGHOUSES
(Continued)
Material or operation
Limestone (crushing)
Metallurgical fumes
Mica
Paint pigments
Phenolic molding powders
Poly vinyl chloride (PVC)
Refractory brick sizing
(after firing)
Sandblasting
Silicon carbide
Soap and detergent powder
Soy bean
Starch
Sugar
Talc
Tantalum fluoride
Tobacco
Wood flour
Wood sawing operations
Fabric
Cotton sateen
Orion felt, wool felt
Napped cotton
Cotton sateen
Cotton sateen
Wool felt
Napped cotton
Napped cotton, wool felt
Cotton sateen
Dacron felt, orlon felt
Cotton sateen
Cotton sateen
Cotton sateen, wool felt
Cotton sateen
Orion felt
Cotton sateen
Cotton sateen
Cotton sateen
Filtering
ratios , cf m/ft
10
ioa
11
10
10
ioa
12
6-8a
9-11
12a
14
10
ioa
11
6a
12
10
12
4-147
-------
Table 4-12. RECOMMENDED MAXIMUM FILTERING RATIOS AND FABRIC
FOR DUST AND FUME COLLECTION IN REVERSE-JET BAGHOUSES
(Continued)
Material or operation
Fabric
Filtering
ratios,
Zinc, metallic
Zinc oxide
Zirconium oxide
Orion felt, dacron felt
Orion felt
Orion felt
11
a 2
Decrease 1 cfm/ft if dust concentration is high or particle size is small.
4-148
-------
123456
FILTERING RATIO, ft3/ff2 . mjn
Note: A and C are siliconized glass fabrics, B is a
siliconized Docron fabric.
A typical range of dust
loading for woven bag filters is
from 0.1 to 10 grains per cubic
foot of gas. Higher concentrations
of particulate matter in some
industries are removed by a pre-
cleaning device, such as a low
efficiency cyclone. Maximum dust
loading reported for felted bag
Figure 4-61. Pressure drop versus filter ratio filters with reverse jet or pulse
for fabrics on 60-minute cleaning
cycle for electric furnace dust.
(Courtesy of the Journol of the Air Pollution
Control Associotion)
jet cleaning is 80 grains per cubic
foot. Figure 4-62 presents dust
143
loading versus filter ratio data for typical products.
4.7.4.1 Baghouse DesignMany design considerations for handling waste gases
from various operations are the same regardless of the process involved. How-
ever, this is not necessarily true of baghouse type - a most important design
decision - which ranges from the open-pressure type to the closed, welded,
fully insulated baghouse. Generally the type of baghouse required is dictated
by the moisture in the waste gas. The higher the dew point, the greater the
precaution that must be taken to prevent condensation which can moisten the
filter cake, plug the cloth, and corrode the housing and hoppers. Three
designs, open pressure, closed pressure, and closed suction are used in
fabric filter baghouse construction. The cost of the open pressure system
is the least of the three; that of the closed suction system is the greatest.
4-149
-------
5 10 IS 20 25
FILTERING RATIO, ft3/ft2 - min
30
KEY
6. KAOLIN
7. CEMENT OR
LIMESTONE DUST
8. COAL DUST
Open pressure An open
pressure baghouse, in which the
fan is located on the dirty gas
side of the system, can be oper-
ated with open sides as long as
protection from the weather is
provided. Under some circum-
stances, a completely open bag-
1. MAGNESIUM
TRISILICATE
2. CARBON BLACK
3. STARCH DUST
4. RESINOX 9. LEATHER BUFFING
5. DIATOMACEOUS EARTH DUST
FOR NUMBERS i THROUGH 6, 99.94 99.99 PER- allows hotter inlet gas tempera-
CENT PASSING 325 MESH. FOR NUMBERS 7 AND
8, 95 PERCENT PASSING 200 MESH. NUMBER 9,60
MESH AVERAGE.
Figure 4-62. Typical performance of reverse-jet
baghouses using felted fabrics on cooling is better in an open bag-
a variety of dusts (dust load versus
filtering ratio at 3.5 in. w.c.
pressure drop).
(Courtesy of the Industrial Chemist Magazine)
144
house is satisfactory, and
tures to be used because the
house. Better cooling allows
lower temperature filter media to
1 Q1
be used with higher inlet gas temperatures than might otherwise be possible.
In an open pressure system, the blower must handle the entire dust load, which
causes the blower to wear substantially. Thus, maintenance cost is higher than
that for a blower on the clean gas side of a baghouse. Because air flows from
the inside of the filter bags, bag replacement is facilitated because a leaky bag
is easier to locate. The open pressure unit is normally constructed with cor-
rugated steel or asbestos cement walls. It may have open gratings at the cell
plate level and may not require hopper insulation. Figures 4-63 and 4-64
illustrate the open pressure baghouse.144'145
4-150
-------
CLEANED GAS
OUTLET
/
>
>
>
(I.
i
V
'-/
y
'-
V
t'
^
f
A
\:
/
^
r
^
,
'
V
f
1
n
\
t
\
\
A
'
\
/
P
^
<
fit
CORRUGATED
HOUSING
OPEN
"GRATING
OUTSIDE AIR
SIDE VIEW
Figure 4-63. Open pressure baghouse.
Closed pressure A closed
pressure baghouse is also constructed
with the fan on the dirty gas side of
the system, but the structure is
closed.
The closed pressure unit is
used for gases with high dew points
and for toxic gases, that cannot be
released at low elevations. Blower
maintenance problems are identical
to those of the open pressure baghouse. Asbestos cement walls without insula-
tion are sometimes used to construct closed pressure baghouses. The floor of
such a unit is closed and the hoppers are insulated. Figures 4-65 and 4-66
144 145
illustrate the closed pressure baghouse.
Closed suction A closed suction baghouse is one in which the fan is
located on the clean gas side of the closed, all-welded, air tight structure. The
closed suction unit is used for gases with dew points between 165 F and 180 F.
The floor of such a unit is closed and the structure walls and hopper are
insulated, particularly for dew points in the upper range. Blower maintenance
is cheaper because the blower is on the clean gas side of the system. The
inspection for holes in the bag is difficult.
331-716 0-69-20
4-151
-------
Figure 4-64. Open pressure baghouse unit showing installation without a separate clean gas
housing.
(Courtesy of the Wheelobrotor Corporation)
4-152
-------
CLEANED GAS
OUTLET
Figures 4-67 and 4-68 illustrate
+u i i K u 144,145
the closed suction baghouse.
Structural considerations
CORRUGATED
HOUSING Metal used to construct the baghouse
CLOSED
SIDE VIEW
Figure 4-65. Closed pressure baghouse.
walls and hoppers must be strong
enough to withstand the pressure
differentials involved. A pressure
differential of 8 inches water
column represents approximately
42 pounds per square foot. The total air pressure exerted on a side panel of
131
a closed suction baghouse may be in excess of 2 tons.
Easy access to the baghouse interior must be provided to change bags
and to perform maintenance. The open pressure unit has easy access to the
cell plate at the bottom of the baghouse, even when the unit is operating. How-
ever, at the bag top level, the hot and possibly toxic gases prevent bag changing
without taking the unit off stream. To overcome this difficulty, many units are
furnished with internal partitions between compartments so an individual
compartment can be isolated. Thus, the remaining compartments continue to
filter while the one removed from service is maintained.
Hoppers are sized to hold the collected dust while or until it is removed
for disposal. The slope of the sides of the hopper must be steep enough to
4-153
-------
Figure 4-66. Closed pressure baghouse unit.
(Courtesy of the Wheelobrator Corporation)
4-154
-------
CLEAN GAS
TO FAN
-7T r~n ST3T '
AaL .aL/jL jfeAviA
>
*
/
\
\
y
f
\
^
'
\
f
\
1
\
\
^
\
/
\
r \
DIRTY
GAS
FRO
PROCESS
CLOSED
ALL WELDED
HOUSING
SIDE VIEW
permit the dust to slide or flow
freely. The designer must also
consider the possibility of bridging.
Continuous removal of dust will help
to prevent bridging of material, and
will prevent operating difficulties
with materials that become less
fluid with time.
4.7.4.2 Fabric Filter Shape -
Figure 4-67. Closed suction baqhouse. ,-,.,,, , , i. ...... .u
Filter shape is dependant on the use
to which the filter will be put. Two major bag shapes, the envelope (flat) and
the tube, are used.
The envelope bag is illustrated
145
in Figure 4-69. Dust is collected
on the outside of the bag, which is
J
prevented from collapsing by the use
of internal screens or frames. How-
ever, the internal screen complicates
bag changing and the contact of the
screen and fabric reduces cloth life.
The envelope bag has the advantage
igure4-68. Closed suction concrete baghouse of providing more filtering surface
unit.
{Courtesy of the Wheelobrotor Corporation)
4-155
-------
TOP VIEW
SIDE VIEW
Figure 4-69. Typical flat or envelope dust
collector bag.
per volume than the tubular bag
because of the close spacing of
the envelopes. If the dust has a
tendency to bridge, every other
bag may be removed to prevent
plugging.
The tubular bag, illustrated
in Figure 4-70, is open at one
145
end and closed at the other.
Tubular bag design is more varied than flat bag design. Multi-bag and bottom
or top entry uni-bag filters are in widespread use. Air flow may be either
from the outside or inside.
A multi-bag is a group of either three or six tubular bags sewn together
145
as shown in Figure 4-71. Multi-bag suspension is limited to a top loop
suspension. A disadvantage of the top loop suspension is the difficult adjustment
required occasionally because of the multi-bag dimensional instability.
The uni-bag is a single tubular bag, not attached to other bags, into
which gas may enter from the top or bottom. Bottom entry allows gas to
enter from the hopper section and flow upwards into the filtering area as shown
145
in Figure 4-72.
Bottom entry allows pre-separation of the coarse particles in the hopper,
and the fabric handles the suspended dust. Gas flows down in a top entry unit
4-156
-------
\
\
__,
^
\
»
f
\
H
\
t
^
^
H
,
f
^
H
x
f
SIDE VIEW
into the filtering area as shown in
TOP VIEW Figure 4-73.145 The entire dust
load passes through the entire tube
of the top entry design before dust
reaches the hopper. A cell plate
ceiling, as well as a cell plate
floor, increases the difficulty of
adjusting top entry bags. The top
Figure 4-70. Typical round or tubular dust col- , , ,
lector bag. entry baghouse creates a dead gas
pocket in the hopper that can be a
source of trouble because of con-
densation of water vapor in mois-
ture-laden gases.
The direction of gas flow in
tubular bags can be either inside
out or outside in. If the direction
is outside in, then a frame is
inserted in the bag to prevent
the bag from collapsing. Collecting
the dust on the outside of the bag
requires that the unit be inspected on
the dirty gas side and increases
TOP VIEW
\
l\
f
' i
' i
' I
i i '
1 i
. 1
1 |
1 1
. ' 1 t
X
SIDE VIEW
Figure 4-71. Typical multi-bag dust collection
system.
4-157
-------
1
b/
^
rr
'
\
\
V
'
1 '
\
'
N
r-
H
*
INSIDE OUT
FILTERING
^r
INSIDE OUT
FILTERING
SIDE VIEW
SIDE VIEW
Figure 4-72. Bottom entry design uni-bag. Figure 4-73. Top entry design uni-bag.
the difficulty of bag replacement. Also, shorter bag life is experienced because
of bag and frame contact.
4.7.4. 3 Cloth Type Two basic types of cloth are used in fabric filters. They
are woven cloth or "cake" filter media, and felted cloth or "fiber" filter
146,147
media.
Woven fabric acts as a support on which a layer of dust is deposited to
form a microporous layer capable of removing additional particles by sieving
123
and other basic filtration mechanisms. " Cake filtration is the most important removal
mechanism when new filter cloth becomes thoroughly impregnated with dust. A
wide variety of woven and felted fabrics are used in fabric filters. Clean felted
fabrics are more efficient dust collectors than clean woven fabrics, but woven materials
are capable of giving equal filtration efficiency after a dust layer accumulates on
the surface. When new woven fabric is placed in service, visible penetration of
dust may occur until the cake builds up. This takes a period of a few hours to a few days
4-158
-------
for industrial applications, depending on the dust loading and the nature of the
particles. When dealing with extremely low grain loadings and fine dusts, fabrics
may be precoated with asbestos floats or similar materials to form an artificial
filter cake to prevent dust leakage.
Another method of reducing dust leakage in fabrics is based on the use of
electrostatics. Electrostatic forces used in dust collecting mechanisms are
explained in Section 4.7.2.4. Electrostatics not only assists filtration by pro-
viding an attraction between the dust and fabric but also may affect particle
agglomeration, fabric cleanability and collection efficiency.
Electrostatic charges are induced in both fabrics and dusts by friction.
The maximum charge and the charge dissipation rate are measured for each
fabric and dust. Fabrics are arranged in relation to each other in a triboelectric
132
series. Attempts to develop such a series for dusts have not been successful.
Agglomeration of some charged dusts may be aided by selection of a fabric
with an opposite charge. For example, a negatively charged dust would agglom-
erate with a positively charged fabric.
Dust leakage through a fabric may be reduced by maximizing the electro-
static differential between dust and fabric, thus maximizing the electrostatic
attraction forces. Leakage may also be reduced by selecting a fabric with a
low dissipation of electrostatic charge. A fast dissipation of charge reduces too
quickly the electrostatic attraction between fabric and dust. When this occurs,
fabric overcleaning during the cleaning cycle is possible with no residual dust
remaining on fabric to act as a precoat.
4-159
-------
Electrostatic charging has been introduced in some bonded fiberglass
fabrics used for air conditioning installations. However, until more informa-
tion is available for large industrial fabric filters, the relative importance of
electrostatics in determining the best filter fabric for a specific installation
cannot be evaluated. Certainly, if one fabric does not work effectively, other
fabrics should be tried. Both the physical characteristics and the electrostatic
properties of the fabrics may serve as guides.
Woven fabrics Woven fabric filters in conventional baghouses usually
126 130
have air-to-cloth ratios of 1:1 to 5:1. ' Woven fabric permeability can be
varied, which, in turn, varies the operating air-to-cloth ratio. Permeability
and air-to-cloth ratio have been discussed in Section 4.7.3.1.
Woven fabric permeability or porosity is varied by using different yarns,
fabric count, cloth weights (expressed as ounces per square yard), and weave
patterns. The three basic forms of yarn used for woven fabrics are monofila-
147
ment, multifilament, and spun-staple. Monofilament yarn is a synthetic
fiber made in a single, continuous filament. Multifilament yarn is made by
twisting two or more monofilaments together. Spun-staple yarn is made by
twisting short lengths of natural or synthetic fiber into a continuous strand.
Warp is the yarn that runs lengthwise in a cloth and fill (pick) is the yarn that
147
interlaces with warp yarn to form a woven fabric. The count of a fabric is
the number of warp and fill yarns per square inch in a woven fabric.
Another method for decreasing woven fabric porosity is to weave cloth
from napped yarn or plied yarn. The napped yarn is made by abrading the
4-160
-------
148
surface of the filament yarn to produce a fuzzy, fibrous condition. The
plied yarn is made by twisting lighter weight yarns together in a single, con-
149
tinuous strand of yarn. For example, a fabric made from 800 denier yarn
(weight in grams of a single continuous strand of yarn, 9000 meters long) may
be made from plied yarn by using four strands of 200 denier yarn. These four
200 denier strands of yarn may be twisted together to give the plied strand of
yarn which may be used to weave the 800 denier cloth. The weight of the cloth
remains unchanged while its dust retentivity is improved.
The basic weaves usually used for fabric filters are plain, twill,and
149
sateen. These are illustrated in Figure 4-74. The plain weave has a simple
"one up and one down" construction. This construction permits maximum yarn
interlacing per square inch, and, if woven tightly, allows high impermeability.
If the count is lowered, this weave can be as open as desired. The plain weave
149
is common in certain cotton ducks and many synthetic fabrics.
The twill weave is recognized by the sharp diagonal "twill" line formed by
the passage of a warp yarn over two or more fill or pick yarns with the inter-
lacing advancing one pick with each warp. In equivalent construction, twills
have fewer interlacings than the plain weave and, hence, greater porosity,
although this naturally depends on the count. Cotton and synthetic filter twills
149
are commonly used.
The sateen weave with even fewer pick interlacings, spaced widely and
regularly, provides a smooth surface with increased porosity. These qualities
4-161
-------
make them particularly valuable in dust collection. Cotton fabrics in this
weave are commonly known as sateens. Cotton sateen is probably more com-
monly used than any other fabric in fabric filters operated at ambient tempera-
tures.
m
PLAIN
TWILL
SATEEN
Figure4-74. Basic fabric weaves used for woven filter bags.
(Courtesy of West Point Pepperell, Industrial Fabrics Division)
Dimensional stability is an important factor in filter fabric. Cotton and
wool fabrics must be preshrunk, and synthetics are usually given a corre-
131
spending treatment known as "heat-setting". This process contributes to a
more even balance of warp and filling yarn tension, controls porosity, and
virtually eliminates shrinkage. Dimensional stability may be lost if the fabric
is subjected to temperatures near that used in the original heat-setting process.
Excessive temperatures in operation can cause a shrinkage of 3 or 4
percent. Shrinkage may cause a bag to pull loose from its connection to the
floor plate or the upper support structure.
4-162
-------
Woven natural fabrics may be treated with flameproofing, moldproofing,
shrinkproofing, and/or dust-releasing coatings, such as silicone to increase
131
service life. Woven synthetic fibers are often treated with flameproofing
and dust-releasing coatings.
Woven fabric bags are made from cotton, wool, Dacron, Nylon, Orion,
Nomex, polypropylene, Teflon, and fiberglass.
Fiberglass fabric bags are treated with silicone, mixtures of silicone
and collodial graphite, and Teflon lubricants to provide protection against
abrasion and flex failures caused by fiber-to-fiber rubbing. These lubri-
cants are effective at temperatures of from 100U F to 550° F.
Felted fabrics Felted fabrics serve as filter media and are used in
126
reverse jet and pulse jet baghouses with air-to-cloth ratios of 6:1 to 16:1,
131
or ratios 5 to 6 times those woven fabric filters.
Felted bags are more expensive than woven bags. Wool is the only
fiber that will produce a true felt. However, synthetic fibers can be needled
to function as a felt filter fabric. Hence, felt is limited to wool and such
synthetic fibers as Dacron, Nylon, Nomex, polypropylene, and Teflon. Cotton
and fiberglass fibers do not make felted fabrics.
Felted fabrics are complex, labyrinthine masses of randomly oriented
fine fibers. The relative thickness provides the advantages of maximum dust
impingement and changes of direction of flow to entrap small dust and fume
particles. Felted fabric filters operate with extremely high collection efficiencies.
4-163
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In some cases, felted bags do not function well in the collection of
extremely fine fumes because the fine particles are embedded in the felt and are
very difficult to remove in the cleaning cycle. In general, felted bags are cleaned
by high-pressure reverse jet and jet pulse devices that operate at frequent inter-
vals. In one unit, each felted bag is cleaned individually by reverse air flow
from a pressure blower and a burst of compressed air released when the bag has
U J J 151
been expanded.
Principal considerations for proper selection of the most economical felt
.. . . ... 150
for a particulate process include:
1. Necessary characteristics of the fiber to meet chemical and
thermal resistance needs.
2. Type of construction.
3. Such physical properties of the felt as density, breaking strength,
elongation, bursting strengh, air permeability, and particle size
retention.
4.7.4.4 Fabric Cleaning Fabric flexing and reverse air flow through the
cloth are two methods of cleaning collected particulate matter from fabric filters.
Fabric flexing Manual shaking, mechanical shaking, and air shaking are
three methods of fabric flexing used in cleaning filters. Air shaking is further
broken into four methods: air bubbling, jet pulsing, reverse air flexing and sonic
vibration.
4-164
-------
Manual shaking is used in baghouses of about 500 to 600 square feet of
cloth. A rap is transmitted to the framework from which the filtering bags are
suspended. Vibration from the rap shakes the dust loose. Thorough cleaning
is rarely achieved because the shaking action is dependent on the operator's
131
vigor. This method is the least expensive and least desirable.
Mechanical shaking (Figure 4-75) removes dust from woven fabrics in a
126
manner similar to that achieved by hand shaking a rug. The shaker mecha-
nism provides a gentle but effective cleaning action on the bags without exerting
undue stresses on the fabric.
The shaker design must allow for easy installation, alignment, and main-
tenance. Shaking is usually used for inside out filtering and is considered too
vigorous for fiberglass bags unless special provisions are made for reducing
145
the intensity of shaking.
Air shaking (Figure 4-76) is done by flowing air between rows of bags,
139
windwhipping the bags to make a dancing, cleaning action. Bags are over-
cleaned near the orifice or jet and undercleaned in blind areas out of the wind-
whipping action. This method requires a minimum of hardware but is usually
too vigorous for fiberglass bags.
Air bubbling is done by releasing a traveling air bubble at the top of the
bag during the cleaning cycle,as shown in Figure 4-77. The bubble travels down
the bag during repressuring and causes it to ripple, thus cleaning the bag by
shaking. The compressed air requirements are high and cleaning at higher
4-165
-------
air-to-cloth ratios has not been fully proven. This method is used for inside
out filtering and sometimes for fiberglass bags.
The jet pulse method employs a jet action of compressed air through a
venturi section at the top of the bag
(Figure 4-78). Smaller diameter
tubular bags are held in place
over a supporting screen, and
dust is collected on the outside of
INSIDE OUT
FILTERING
SIDE VIEW
an open-end-up tubular bag. Com-
pressed air released at frequent
Figure 4-75. Mechanical shaking of bottom entry intervals to a row of bags causes
design uni-bag dust collector.
the bags to pulse outward, thus
vibrating the fabric, and removing
the dust. The dust is cleaned off by
a flicking action on the collection
surfaces rather than a reverse
flow through the fabric. Felted
fabrics usually are used with out-
side in filtering. The jet pulse
provides uniform pressure drop
and continuous and automatic
cleaning with no moving parts and
O) PRESSURE BLOWER
TOP VIEW
AIR JETS
FOR SHAKING
SIDE VIEW
Figure 4-76. Air shaking wind-whip cleans dust
collector bags.
4-166
-------
permits higher air-to-cloth ratios, resulting in smaller units for equivalent
capacity. The cost of a supporting frame and higher replacement costs of
145
felted fabrics over woven fabrics are disadvantages of this method.
Reverse air flexing is achieved by a double or triple cycle deflation of the
bags followed by gentle inflating through low-pressure reverse flow, as shown in
Figure 4-79. The cloth cleaning is not exclusively shaking, because some back-
washing occurs. This method is used for inside out filtering with fiberglass
bags.
Occasionally, sonic generators are used to provide additional fabric vibra-
145
tions for cleaning action. Sonic generators vibrate the dust loose from the
collecting fabrics as shown in Figure 4-80. They are sometimes used to
supplement repressuring and reverse flow cleaning. Some carbon black and
zinc oxide installations are using repressuring and sonic horns to clean fiber-
i u 145
glass bags.
The second cleaning category, reverse air flow, is divided into three
methods: repressuring cleaning, atmospheric cleaning, and reverse jet
cleaning.
Repressuring cleaning is a low-pressure, high-volume, reverse flow of
air through the bags as shown in Figure 4-81. It is used for woven or felted
bags.
Atmospheric cleaning is used in closed suction baghouses. An atmos-
pheric vent is placed into the damper of the fan so that when the compartment
damper valve closes, the vent opens to the atmosphere allowing a backwash of
331-716 0 - 69 - 21
4-167
-------
JET
UNI-BAG
INSIDE OUT
FILTERING
SIDE VIEW
Figure 4-77. Bubble cleaning of dust collector
bags.
COMPRESSED AIR
OUTSIDE IN
FILTERING
SIDE VIEW
Figure 4-78. Jet pulse dust collector bag cleaning.
I
I>
00
\
\
#
REPRESSURING
VALVE
EXHAUST
r1
I
[
^
SIDE VIEW
FILTERING
SIDE VIEW
COLLAPSING
INLET
VALVE
SIDE VIEW
CLEANING
Figure 4-79. Reverse air flexing to clean dust collector bags by repressuring.
-------
AIR HORN
FILTER BAG
SOUND WAVES
SIDE VIEW
Figure 4-80. Sonic cleaning of dust collector bags.
S7A
1
4
4
1
r
\
n
*
4
M
\
,
rt
^
k
*
ui
n
^
*
u
\
\
\
<
_
A
^
i
1
INSIDE OUT
FILTERING
SIDE VIEW
Figure 4-81. Repressuring cleaning of dust collector bags.
air to clean the cloth,as shown in Figure 4-82. This action is gentle and is only
used with fiberglass cloth and easily removed dust. Sonic horns may be used to
supplement the cleaning action. The amount of backwash air is dependent on
doth resistance. If the resistance is high the amount of backwash air is
diminished, thus reducing the cleaning action.
4-169
-------
TO FAN
VENT OPEN
SIDE VIEW
EXHAUST CLOSED
TO NEXT
COMPARTMENT
SIDE VIEW
OPERATING
CLEANING
Figure 4-82. Cloth cleaning by reverse flow of ambient air.
Reverse jet cleaning uses a traveling compressed air ring which moves up
and down the outside of a tubular filter bag, thus blowing the dust back through
the cloth and off the inside of the bag with compressed air as shown in Figure
4-83. Re-entrainment of fine dust during cloth cleaning has caused high pressun
drops across some baghouses collecting fine fumes. The design is used success'
fully with felted bags with high air-to-cloth ratios collecting relatively coarse,
nonabrasive dusts. The replacement costs of bags is somewhat high. The unit
145
allows a compact installation.
The volume of air blown through the slot of the blow ring usually ranges
-I O 1
from 1.0 to 1.5 cubic feet per minute per linear inch of slot. ° Slot widths
152
range from 0. 03 to 0.25 inch.
4-170
-------
Jf
\
4
-4
r
.*
TOP ENTRY
^-A /-^
,/ \
r "(
_ x
X"^ ^^S;
^
HIGH PRESSURE
' *-AIR BLOW
RING
P
INSIDE OUT
FILTERING
CROSS-SECTION
Figure 4-83. Reverse jet cleaning of dust collector bags.
4.7.4.5 Fabric Selection Fabrics that are presently applied in commercially
123 147 153
available baghouses are shown in Table 4-13. ' ' The finish applied to
these fabrics is described in Section 4.7.4.3.
When comparing fabric cost ranks given in Table 4-13, other factors also
should be considered. Use of a high-temperature fabric reduces the amount of
dilution cooling required. A high-temperature fabric requires less filtering
area. For example, when cooling gases from 400° F to 250° F with ambient air
at 90° F, the final gas volume is increased by 60 percent. The filter operating
at 400° F requires only 62. 5 percent as much cloth area as at 250° F. These
154
reductions will also lower power costs for operating the filter.
Fabric materials less commonly used are carbon, metals and ceramic
fibers that will filter gases at temperatures up to 1600° F. Beta fiberglass,
4-171
-------
Table 4-13. FILTER FABRIC CHARACTERISTICS
123, 147, 153
Fiber
Cotton
Wool
Nylond
Orlond
Dacrorid
Polypropylene
Nomexd
Fiberglass
Teflond
Operating
exposure
F
Long
180
200
200
240
275
200
425
550
450
Short
225
250
250
275
325
250
500
600
500
Supports
combustion
yes
, no
yes
yes
yes
yes
no
yes
no
Air
permeabilitya
cfm/ft2
10-20
20-60
15-30
20-45
10-60
7-30
25-54
10-70
15-65
Composition
Cellulose
Protein
Polyamide
Polyacrylonitrile
Polyester
Olefin
Polyamide
Glass
Polyfluoroethylene
Resistance
Abrasion
G
G
E
G
E
E
E
P-F
F
Mineral
acids
P
F
P
G
G
E
F
E
E
Organic
acids
G
F
F
G
G
E
E
E
E
Alkali
G
P
G
F
G
E
G
P
E
Costc
rank
1
7
2
3
4
6
8
5
9
Win/ft2 @ 0.5 in. W. G.
bP= Poor, F = Fair, G = Good, E = Excellent.
cCost rank, 1 = lowest cost, 9 = highest cost.
Dupont registered trademark.
-------
a relatively new product, is more flexible than regular fiberglass and abrades
149
less in service.
4.7.4.6 Auxiliary EquipmentAuxiliary equipment that is selected during
the original design includes dust handling equipment and precooling equipment.
Dust handling equipment For collectors that are regularly cleaned and
re-used, such dust handling equipment as hoppers must be provided for the
collected dust. Hoppers empty through a dust gate, rotary lock or trickle
130
valve into a screw or belt conveyor, a truck body, or a tote bin. The dust
is then conveyed to the final disposal point.
Careful consideration must be given to the dust handling system at the
130
time the fabric collector is originally designed. Failure to do so may result
in leakage in the system that will redisperse the collected dust and create air
pollution problems. Inaccessability of the handling equipment for servicing will
make maintenance difficult. Undersizing of the dust disposal mechanism may
block the upstream flow of process materials.
Precooling equipment The application of cloth filtration to the cleaning
of furnace gases in most cases requires that the gases be cooled in order to
protect the filter fabric and to ensure economical bag life. The following three
1 R G.
cooling methods are employed singly or in various combinations:
1. Radiation and convection cooling, this requires a relatively large
investment in U-tube coolers, or heat exchangers.
4-173
-------
2. Admission of outside air for cooling, this results in relatively
large filtration volumes with a resultant increase in the size of the
gas cleaning equipment.
3. Spray cooling, this is the most economical with respect to
capital investment, but requires careful control of cooling water
sprays in order to keep the temperature of gases high enough (75° F
above dew point) to prevent condensation, which causes plugged filters.
Radiation and convection cooling,and spray cooling cannot be used for a
gas of high moisture content. Only the tempering air method can be used to
avoid condensation of the moisture. Regulation of temperature is accomplished
easily by this method, however, the outside air used for cooling also mustpass
through the filter, so the filter must be considerably larger than a filter used
with U-tubes or spray cooling methods.
Spray cooling of hot gases is the least expensive method because the
initial cost is reasonable, the maintenance is relatively easy, and the increase
in gas volume to be filtered is nominal. However, careful control of cooling is
145
needed to hold the temperature of hot gases 50° F to 75° F above the dew point.
4.7.4.7 Individual Collectors Versus Large Collecting Systems The individual
fabric collector has several advantages over a large central collecting system
157
in manufacturing plants where relatively few dust sources must be controlled.
The unit collector is self-contained, and has a lower erection cost because the
unit is shipped erected, or nearly so, and because it can be installed at the
point of need with minimum duct work. The unit collector's mobility is often
4-174
-------
economically important in a plant with idle batch processes where idle unit
collectors maybe moved to sites requiring dust control. The large central
collecting system requires considerable floor space and is often erected outdoors.
Outdoor erection of a central system may require insulation and even supple-
mentary heat input to avoid chilling the gas to the dew point. The large central
system is preferred in large manufacturing plants where many dust sources of
continuous processes must be controlled.
4.7.5 Typical Applications
The following examples of fabric collector application are presented to
show how the}' may be applied to control particulate matter from various sources.
The use of fabric filters has been extended by the introduction of fiberglass
bags capable of operations at temperatures up to 550" F. The use of synthetic
fabric bags has resolved many problems associated with corrosive or moderate
temperature dust emissions.
4.7.5.1 Cement Kilns The collection of the dust from rotary cement kilns has
long been a difficult problem. The difficulty arises from the large volumes of
gas involved, the heavy loading of very fine particles, the high gas temperatures,
and in the case of wet-process kilns, the presence of a large amount of water
158
vapor.
The conventional cyclone will collect a high percentage of the dust, but
beyond this point the electrostratic precipitator is the only device besides the
fabric collector capable of final and complete cleanup. ' Efficiencies as
4-175
-------
high as 99. 5 percent, outlet loadings below . 02 grains per standard cubic foot,
and plume opacities less than 10 percent have been reported for fabric filter
i , 16°
applications to cement kilns.
4. 7. 5. 2 Foundry CupolasEmissions from a gray iron cupola are a prime
example of particulate matter than can be controlled with high temperature
fabric filtration. Cupola exhaust temperatures range from 1000 F to 2200° F
162
with an average effluent loading of about 1 grain per cubic foot. Much of
the emission is fine metal oxide fume less than 0. 5 micron in diameter. Gas
cooling and high-temperature fabric filters are required. Evaporation cooling
by water sprays is the most common technique used in gas cooling. Off-gas
temperatures are reduced to about 450" F before filtration through fiberglass
bags. In a typical installation the gas is filtered at rates of about 2. 5 feet
2
cfm/ft through tubular bags that are 11-1/2 inches in diameter and 15-1/2
feet long. A bag life of one or two years can be expected if bags are used
continuously. In noncontinuous service, averaging 20 to 40 on-stream hours
1 62
per week, bags have been reported to last four or five years.
4.7.5.3 Electric Arc Steel FurnacesThe electric arc steel furnace presents
an emission control problem that is characterized by fine particulate matter
containing a high percentage of oxides of iron, dispersed in a gas stream that
is highly variable in temperature, loading, and volume during the different
process cycles. Effluent volume is dependent on the type of hooding arrange-
ment employed because the dilution air flow is adjusted to provide for gas
4-176
-------
cooling and in-plant dust control. Stack temperatures may reach 750° F or
1 C* *3
higher with closed, hooded units.
The first large-scale fiberglass filter in the steel industry was installed
1 C* O
in 1959 at a Seattle steel mill. This unit handles 105, 000 cfm at tempera-
tures up to 500° F using fiberglass bags 11-1/2 inches in diameter and 25 feet
long that operate at an air-to-cloth ratio of 1.4. The fiberglass bags are
cleaned by collapsing.
Another example is a furnace melting 45 tons of steel scrap in four hours
and using an Orion fabric filter to handle a volume of 60, 000 cfm at 200° F.
The bag replacement costs are approximately $1400 per year with a five year
, ... 163
bag life.
4.7.5.4 Open Hearth FurnacesA major steel company conducted a study
which found that iron oxide fumes generated by an oxygen-lanced open hearth
164
furnace could be collected efficiently by fiberglass bags.
The 10-compartment baghouse used in the study handles 145, 000 cfm at
2
500° F, based on a filter ratio of 2 cfm/ft when nine of the ten compartments
are in operation. Each of the ten compartments contains 80 fiberglass bags,
11-1/2 inches in diameter and 34 feet long (or 8070 square feet of filter surface
per compartment). Reverse air flex cleaning, supplemented by sonic horns,
is used. The efficiency of the baghouse is well over 99 percent under all con-
ditions of inlet gas volume and dust loading. Inlet particulate loading has been
as high as 20 grains per cubic foot during periodic cleaning of heat regenerative
4-177
-------
surfaces. The outlet dust loading has been measured at 0. 007 grains per
u- t . 165
cubic toot.
4.7.5.5 Nonferi-ous Metal FurnacesOne of the largest secondary lead smelters
in the country has converted from synthetic fiber to fiberglass bags to permit
fume collection at temperatures higher than 400° F. This installation cleans the
combined effluent from a reverberatory furnace and a lead blast furnace. Higher
filtering temperatures were desired in order to eliminate the deposition of
organic tars on the bags. After 16 months' experience with fiberglass bags,
2
operated at 1.2 cfm/ft and cleaned by shaking, results are reported as
* t + 162
satisfactory.
After completion of pilot-scale studies with both synthetic and fiberglass
media at an integrated smelter producing primary copper and zinc, a baghouse
equipped with 222, 000 square feet of fiberglass bags was constructed to clean
162
the effluent streams from a reverberatory furnace and copper converters.
Fiberglass fabric was selected because of its corrosion resistance and because
operation at 450' F reduced by 50 percent the radiation-convection heat trans-
fer area that would have been required for cooling to temperatures safe for
2
organic media. The average filter ratio is 1.6 cfm/ft . Bags 5 inches in
diameter and 10 feet long are vised. Bag cleaning involves collapse every half
hour supplemented by mechanical shaking every eight hours. Sonic cleaning
equipment has been tried experimentally. Based on present knowledge, an
average bag life in excess of two years is anticipated.
4-178
-------
A. 7.5.6 Carbon Black PlantsBaghouses equipped with fiberglass bags are
reported to be in use for the final cleaning in 35 of the 37 carbon black plants
~\ f C*
in the United States. Earlier baghouses used synthetic bags and kept the
filtration temperature below 2503 F to protect the media. However, the
temperature was regulated by evaporative cooling, which brought the gas stream
close to the acid dewpoint and caused serious corrosion of fabric. The intro-
duction of fiberglass in 1953 minimized this problem by allowing operation at
temperatures of 400° F to 500° F. Bag collapse, with some supplementary vibra-
tion from sonic horns or other gentle means is the most common technique
used for cleaning the fiberglass filters. Air-to-cloth ratios are usually 1. 5:1.
The average baghouse capacity is around 50, 000 cfm, and bag life is 12 to 18
«. 166
months.
4.7.5.7 Grain Handling OperationsThe important sources of grain dust
emissions are cleaning, rolling, grinding, blending, and the loading of trucks,
rail cars, and ships. Conveying and storing grains also cause dust emissions.
Low- and medium-efficiency cyclones only have been used because of the
increased operating costs and maintenance problems associated with high-
efficiency multiple cyclones. For grain dusts larger than 10 microns in
diameter, medium-efficiency cyclones are satisfactory. For grain dusts
smaller than 10 microns, the fabric filter is preferred. Often, air streams
containing large amounts of dust are passed through a cyclone to remove coarse
Particles before being directed to a fabric filter. This technique relieves the
4-179
-------
fabric filter from handling a high volume of large particles. Receiving,
handling, and storing operations require hooding the emission source and
conveying the dust-laden air to dust collection equipment. For receiving
hoppers used in unloading rail cars and trucks, a method of control is to
exhaust air from below the grating. The indraft velocity required will range
from 100 to 300 feet per minute depending on whether the hopper is in a building
or outside and exposed to winds.
The fabric filters with the open pressure or closed pressure baghouse
with mechanically shaken woven cotton bags are reported to remove 99. 9 per-
123
cent of grain particles in the size range of 1 to 5 microns. The air-to-cloth
ratios are about 5:1.
Reverse jet filters which use felted fabrics are reported to remove 99,9
percent of grain particles in the size range of 1 to 5 microns with an air-to-
i fis
cloth ratio as high as 15:1, although ratios of 12:1 are more common.
4.7.6 Operational Practices
Operational practices are somewhat different for woven fabrics and
felted fabrics. The bag life of woven fabrics is related to cleaning frequency.
The more often a fabric, especially fiberglass, is cleaned, the shorter the
bag life; this assumes that cleaning is conducted often enough to avoid fabric
blinding by a dust overload. Fabric cleaning may be done when the pressure
drop across the baghouse, or one of its compartments, increases to 6 inches of
131
water. In large baghouses, fabric cleaning is scheduled by compartment
based on previous operating experience.
4-180
-------
To avoid plugging of woven fabrics because of condensation, the gas tem-
perature in the baghouse should be 50° F to 75° F higher than the dew point of
the gas. In some cases, insulated duct work and baghouses are needed to
maintain gas temperatures. In some installations, a small auxiliary heater is
used to prevent condensation in a baghouse when it is shut down.
131
The bag life of felted fabrics is prolonged by reducing the frequency of
cleaning. The cleaning cycle may be scheduled to hold the pressure drop across
169
a reverse jet baghouse with felted bags to 3-5 inches of water. Figure 4-84
illustrates the effect of pressure control on filter resistance in a reverse jet
152
filter for dusts and fumes.
To avoid plugging of felted fabrics when handling gases with high moisture
131
content, the use of preheated air for reverse jet cleaning may be necessary.
4.7.7 Maintenance Procedures
Maintenance of a fabric collector is often related to adequacy of the
original design. The installation of filters with high air-to-cloth ratios is often
responsible for rapid replacement of bags. The replacement may be needed
because of blinding of fabric or excessive bag wear.
An unusually heavy grain loading may cause excessive wear or blinding
of a woven fabric. As a rule of thumb, particulate loadings above 10 grains per
cubic foot are often handled by a precleaner such as a medium- or low-efficiency
130
cyclone. The cyclone will remove a large amount of particulate matter
4-181
-------
greater than 10 microns in diameter. Reverse jet and pulse jet collectors
can
handle, without a precleaner, dust loadings up to 80 grains per cubic foot for
131
particulates larger than 60 microns.
UJ
OL
70
60
50
30
UJ
>s> 20
<
LU
a:
u
10
DUST AT 5 TO 10 gr/ft3
OR METALLURGICAL FUME
AT \ gr/ft3
TYPICAL DUST AT
0.5 gr/ft3
0 20 40 60 80 100
REVERSE JET OPERATION, percent
Figure 4-84. Effect of cleaning frequency on
filter resistance in reverse-jet
baghouse.
(Courtesy of Air Conditioning, Heating, and
Ventilating Magazine)
Many baghouses are designed with compartments so that one compart-
ment can be shut down while the rest of the dust collector continues operating.
Means for easy access to the bags should be included in the original design.
Leakage through the filter is perhaps the most important service problem.
Each bag must be regularly inspected for holes or tears. Regular measurement
4-182
-------
of down-stream dust concentration should be made either manually or with an
141
electronic-eye,to warn of an increase in dust content of the stream.
Bag spacing is important. Sufficient clearance must be provided so that
one bag does not rub another. A minimum clearance of 2 inches is needed
131
between bags 10 or 12 feet long, while longer bags require greater clearance
distances.
The fan motor and bearings, shaking device, reverse jet blow rings, valves,
130
and dampers must be lubricated regularly and checked for wear. To avoid
extended downtime, worn parts should be replaced before they fail in service.
Regular inspection of ducts, hoods, framework, and housing for signs of
wear from corrosion, erosion, excessive heat, and excessive moisture should
A 13°
be made.
Pressure gauges, thermocouples, flow meters, and all other instruments
130
must be checked regularly to ensure that they are functioning accurately.
A preventive maintenance program should be established and followed.
Regular routine inspection of major lubricant locations is needed. The schedule
130
maybe altered to fit specific installations of dust collectors.
1.7.8 Safety
Whenever dust is a combustible material, the principal hazard in the
operation of fabric collectors is that of explosion and fire. Other hazards may
arise in special cases, depending upon the toxicity or abrasiveness of the dust,
331-7160-69-22 4-183
-------
i.e., human health hazards such as metal poisoning and silicosis.
Continuous monitoring of discharge effluents is needed to avoid any mishaps. 30
4.8 AFTERBURNERS
4.8.1 Introduction
Afterburners are gas cleaning devices which use a furnace for the combus-
tion of gaseous and particulate matter. Combustion is accomplished either by
direct flame incineration or by catalytic combustion.
The disposal of particulate matter by combustion is limited to residue-free
vapors, mists, smoke, and particulate matter which is readily combustible,
as well as to particle sizes which require short furnace retention time and small
furnace size. Afterburners are usually used to dispose of fumes, vapors, and
odors when relatively small volumes of gases and low concentrations of partic-
ulate matter are involved.
4.8.1.1 Definition of Terms-
Direct flame combustionThe use of a separately-fired burner in direct
flame contact with the particle-laden gas to sustain rapid oxidation. Heat
transfer occurs by conduction, convection, and radiation.
Catalytic combustionA method of oxidizing combustible gases and
vapors on the surface of a catalyst, without flame and at a lower temperature
than corresponding flame temperatures.
CatalystA substance which increases the combustion rate and theoret-
ically is unchanged by the combustion process.
4-184
-------
Flash point temperatureThe lowest temperature at which the vapors
above a volatile combustible substance ignite momentarily in air, tested
usually by applying a small flame under specific test conditions. Flash point
temperatures are dependent on the geometry of the vapor-filled space, and differ
from open and closed containers.
Auto-ignition temperatureThe lowest temperature at which a volatile
170
flammable substance will ignite and sustain combustion.
4.8.1.2 Advantages and Disadvantages of AfterburnersThe advantages and
disadvantages of direct flame and catalytic afterburners are cited to allow
a comparison to be made of the two types of gas cleaning devices.
Direct flameAdvantages of the direct flame incineration afterburner
include: (1) High removal efficiency of submicron odor-causing particulate
matter, (2) simultaneous disposal of combustible gaseous and particulate
matter, (3) compatibility with existing combustion equipment, (4) relatively
small space requirements, (5) simple construction, (6) and low maintenance.
Disadvantages include: (1) high operational costs including fuel and
instrumentation, (2) fire hazards, and (3) excessive weight.
CatalyticAdvantages of the catalytic afterburner include: (1) reduced
fuel requirements, (2) and reduced temperature, insulation requirements, and
fire hazards.
4-185
-------
Disadvantages include: (I) high initial cost, (2) sensitivity to catalytic
poisoning, (3) inorganic particles must be removed and organic droplets must
be vaporized before combustion to prevent damage and plugging of the catalyst,
(4) catalysts may require frequent reactivation, and (5) lower efficiency at
the usual catalytic afterburner operation temperature.
Catalytic afterburners frequently require a direct flame air preheater
to initiate and sustain catalytic combustion, thereby further reducing the relative
advantage of the catalytic afterburner. Methane from the incomplete combustion
of the direct flame preheater fuel is not oxidized at low temperature in the
catalyst bed. Incomplete combustion and the formation of oxygenated com-
pounds may be prevented by operating the catalyst bed at elevated temperatures
with a consequent reduction in the thermal advantage and fuel savings over
direct flame combustion.
Catalytic afterburners frequently are unable to meet local code
requirements as to combustion efficiency at the usual catalytic afterburner
operating temperature. *
4.8.1.3 Combustion Theory Combustion is the chemical reaction of a fuel
with an oxidant, involving the disappearance of the original reactants and the
*Los Angeles County Rule No. 66: 90 percent or more of the carbon in the
organic material being incinerated must be oxidized to carbon dioxide.
4-186
-------
production of heat and oxides. Combustion usually takes place in a thin
reaction zone.
When solid fuels burn, the reaction zone is confined to the surface of the
particle. At low temperatures the combustion rate is limited by the chemical
reaction rate, whereas at higher temperatures the chemical-reaction rate is so
171 172
rapid that the rate of air supply controls the combustion rate. '
Combustion of liquid droplets and volatile solids occurs away from the
surface of the particle and combustion rate may be dependent on the rate of
heat transfer to the surface, which causes evaporation and thermal decom-
position of the solid. Combustion is influenced by the gas velocity, the rate
of mixing, and the supply of oxygen. '
The temperature in the combustion zone surrounding the particulate
matter may exceed the temperature at the interior of the particle and in the
surrounding gas by several hundred degrees. Heat transfer is largely by
radiation from the incandescent surface of the particle, or from the incan-
175
descent carbon formed as an intermediate step in the combustion process.
Catalytic combustionThe mechanism of surface catalysis is very
complex. The catalytic combustion process occuring on the surface of the
catalyst involves diffusion of the reacting molecules to the surface of the
catalyst through a stagnant gas film which surrounds the surface of the
catalyst, adsorption of the reactants on the surface, chemical combination of
the reactants, desorption of the combustion products, and diffusion of the
4-187
-------
combustion products from the surface of the catalyst to the main gas stream.
The rate of catalytic oxidation is usually controlled by adsorption, chemical
combination, desorption, or a combination of these.
Catalytic combustion occurs at a lower temperature than direct flame
oxidation by substituting catalytic adsorption energy for thermal energy of
activation (energy necessary for chemical combination) and by increasing the
concentration of the reactants on the surface of the catalyst.
The chemical union of the oxygen with the organic compounds occurs
without flame on the surface of the catalyst, with the transfer of the heat of
combustion from the catalytic bed to the gas stream.
Many substances exhibit catalytic properties, but metals in the platinum
family are recognized for their ability to produce combustion at minimum tem-
peratures. Because catalysis is a surface phenomenon, relatively small
amounts of metal are used and supported to expose a maximum of surface area.
Other catalysts include copper chromite,and the oxides of copper, chromium,
176 177
vanadium, manganese, nickel, and cobalt. '
Catalysts may be subject to poisoning from such materials
as zinc, arsenic, lead, mercury, copper, iron, antimony, and phosphates.
Other materials which commonly suppress catalysis include halogen, and
178 179
sulfur compounds. ' Poisoned catalysts may be reactivated by
periodically washing the catalyst with acid solutions.
4-188
-------
4 «_2 Afterburner Design Criteria
/t.8.2.1 General Variables which must be considered in the selection and/or
design of afterburners for particle-containing gaseous wastes are heat transfer,
reaction temperature, particulate size, mixing, flame contact, residence time,
inlet gas temperatures, and composition. The variables are interdependent and,
as a consequence, design criteria are semi-empirical because of the large
range of materials dealt with, the lack of design data, and the relatively loose
control of operating conditions.
4.8.2.2 Heat Transfer The transfer of heat from burner flame to gaseous
and particulate matter is an important factor in determining the furnace size,
operating temperatures, and fuel requirements of direct flame contact incin-
erators. Heat transfer is best achieved by mixing when gases are burned,
180,181
and best achieved by radiant heat transfer when particulate matter is burned.
For purposes of burning particulate matter, radiant heat transfer and
furnace temperature uniformity may be increased by increasing the emissivity
of the burner flame. This can be accomplished by limiting the air supply to
produce a sooty flame, by using high carbon-to-hydrogen ratio (C/H) fuels,
by adding soot or fuel oil (by carburetion) to gas flames, by using low-velocity
, 182-184
burners, through poor mixing of air and fuel, and by altering furnace design.
18.2.3 Reaction Temperature Most direct flame burners operate in the
1200 F to 1500° F temperature range in order to obtain maximum combustion
185
within the limits of flame contact, mixing, and residence time in the furnace.
4-189
-------
186-1
O 11
1000 1200 1400 1600 1800 2000 2200
TEMPERATURE (° K)
Figure 4-85 illustrates
the effect of air velocity and
particle diameter on the
combustion rate of carbon.
The effects of particle size,
reaction temperature, combus-
tion gas composition, and gas
velocity on the combustion rate
of carbon, coal, and a number of
other compounds have been in-
, 171-174, 189-191
vestigated.
Adsorption catalysts are
used in fume burners operated
Figure 4-85. Effect of air velocity and particle in the 800 °F to 1200 °F tempera-
diameter on the combustion rate of
carbon. (Dn = particle diameter) L _ , , , ,
v D ture range. Furnace and catalyst
temperatures, space, velocity, and bed depth are used to achieve the desired
192-194
level of combustion efficiency (Figures 4-86 and 4-87).
Compounds such as methane, which are difficult to oxidize, require a
catalytic bed temperature approximately 200°F higher than ethane, propane,
butane, and other members of the paraffin series. Carbon monoxide, which
is difficult to oxidize by direct flame combustion at low temperatures, is easily
4-190
-------
100
90
80
70
60
i 50
I
!40
30
20
10
FI 1 1 nr-^q
oxidized by platinum at a temperature of approximately 300 °F and by hopcalite
176, 196
catalysts at room temperature.
4 8.2.4 Retention Time Pre-heat (induction) and combustion times will
dictate the overall residence time
of the particulate matter in the
afterburner. Residence time
requirement will determine both
combustion chamber dimensions
and efficiency.
The time required to heat
the waste gas to peak furnace
temperature is dependent on the
1
700 800 900 1000 1100 1200
TEMPERATURE, ° F
Figure 4-86. Combustion efficiency of catalytic burner combustion chamber
afterburner.
dimensions and efficiency.
The time required to heat the waste gas to peak furnace temperature is
dependent on the burner combustion intensity and inlet gas temperature and may
be computed as follows:
2
!,, ,. , , heat capacity of gas (Btu/ft -°F) x temperature rise (°F) n.
heat up time seconds) = . .. . . ., '. /£* : (l>
' combustion intensity (Btu/ft'J-sec)
Values of combustion intensity will vary from 1 Btu per cubic foot per
second for low-pressure gas jet mixers to 500 Btu per cubic foot per second for
4-191
-------
100
is 80
H o
3 a
to uj 60
§1
UH
_|Q- 40
o u-
HO 20
I II
SPIRAL-WOUND
METAL FOILS
'4 in. DEEP
BED
O1
212
30,000 SV
70,000
100,000
I I I I I
premix mechanical burners. A
typical value is 140 Btu per
cubic foot per second for premix
high-pressure gas jet multiple-
port burners.
The time required to heat
392 572 752
REACTOR INLET TEMPERATURE, ° F
a gas with a heat capacity of
Figure 4-87. Effect of temperature and velocity
on abatement effectiveness: spiral- 0. 0182 Btu/ft - °F from
wound metal foils catalyst support. '
(Courtesy of the Journal of the Air Pollution
Control Association) 200° F to 1800° F in a. furnace
with a combustion intensity of 140 Btu per cubic foot per second would be:
Time (seconds) = 0.0182 x (1800 - 200)/140 = 0.208 seconds
Combustion time required is dependent on particle size, oxygen content
of the furnace atmosphere, furnace temperature, particle composition, gas
velocity, and mixing of combustibles. Combustion times for a number of
different materials have been determined and correlated on the basis of
the following equations:
196
2
id = PR'Tm X0/ (960D pj for diffusion-controlled combustion rate (2)
ic = PX0/ <2KsPg) for chemical reaction-controlled cumbustion rate (3)
Where: td - diffusion-controlled combustion time (seconds);
tc = chemical reaction rate-controlled combustion time (seconds):
4-192
-------
3
p = density of carbon residue or coke (gm/cm );
3
R' = universal gas law constant (82.06 atm cm /mole/°K);
T = mean temperature of stagnant gas film (°K);
x = original diameter of particle (cm);
0 = combustion mechanism = 1 for CO and 2 for CO formation;
Lj
2
D = diffusion coefficient of oxygen at temperature T (gm/cm );
p = partial pressure of oxygen in combustion air (atm); and
o
2
K = surface reaction rate coefficient (gm/cm sec atm).
S
K may be calculated by means of the following equations:
S
K ^L.085xl04xT-1/2xe-39'30°/RTs(forsoot) (4)
S S
-35 700/RT
K = 8710 x e ' s (for coke and carbon residue) (5)
S
Where: T = surface temperature of the carbon.
Equation 2 holds at high temperature, zero gas velocity, and large particle
sizes. The equation can be corrected for the effects of gas velocity and turbu-
lence by use of the dimensionless Nusselt conventional heat transfer relationship
t i. i 181
tor spherical particles:
1 /2
N = 2 + 0. 68 N x N
Nu Pr Re
Where: N = Nusselt Number;
Nu
N = Prandtl Number, a function of the physical properties of
the gas; and
N = Reynolds Number, a function of the physical properties of
XX C
the gas, particle diameter, and gas velocity.
4-193
-------
The Nusselt Number N - h x/k = 2 at zero gas velocity where: h = con-
2
vectional heat transfer coefficient (cal/cm °C sec); x = particle diameter (cm).
h is an inverse function of the stagnant gas film thickness, x/2, surrounding the
particle and directly proportional to the thermal conductivity of the furnace at-
2
mosphere, k (cal/cm °C cm sec).
The film thickness decreases with increasing velocity and decreasing particle
size to such an extent that the combustion rate for particles smaller than 100
microns is limited only by chemical kinetics at normal afterburner temperatures.
Equation 2 is of limited value in afterburner design because particles
larger than 100 microns are easily collected by other gas cleaning devices and
would require excessive retention time and furnace volume.
Equation 3 holds for particle sizes smaller than 100 microns and for tem-
peratures at which the combustion rate is determined by chemical kinetics.
Total combustion time for a carbon residue-forming particle then becomes:
t = t. + t K + t (7)
r i d v c
where: t = total residence time (sec);
t. = induction time (sec); and
K^ = volatile matter correction factor determined by the equation:
KV = (1 + E/100) / (1 + E/100 - V/100) (8)
where: E - percent excess air and
V = percent volatile matter.
4-194
-------
The combustion time for hydrocarbon liquid droplets larger than 30 microns
-| O Q
at zero gas velocity may be computed using the following equation:
t = (29,800/p ) M T~1-75 .x2 (9)
where- M = molecular weight and
w
T = furnace temperature (°K)
The combustion time of particles smaller than 30 microns is dependent on
the combustion rate of the hydrocarbon vapors.
r*
The time required to burn a 5 x 10 cm soot particle of 2 grams/cubic
centimeter density in a furnace atmosphere containing 0. 20 atmosphere of oxygen
at 1800 °F can be computed using equations 3 and 4. The time required would be
0.51 second.
Total residence time in the furnace, including heat up time from 200 °F,
would be induction time + combustion time = total time, or:
t = 0.208 + 0. 510 = 0. 718 second
r
In practice, minimum gas furnace retention time is about 0. 30 second at
a temperature of 1200 °F. Particle retention time may be increased by design-
ing the combustion chamber in the shape of a cyclone using a small tangential
-| n p-
inlet, and by introducing the gases at a high velocity (Figure 4-88).
Cyclone furnace dimensions are chosen using a gas velocity of from 15 to
30 feet per second. ' Good mixing is attained by using appropriate design
parameters to provide turbulent flow in the afterburner.
A tangentially fired, portable hood, smoke afterburner is shown in
Figure 4-89.
4-195
-------
REFRACTORY
LINED
STEEL SHELL
REFRACTORY
RING BAFFLE
GAS BURNER
PIPING
GA5 STREAM
The combustion constants
for a number of organic compound!
are presented in references 171
through 175, 186 through 191, and
195 through 197.
4. 8. 2. 5 Heat Recovery Inlet
waste gas temperatures should
be as high as possible to mini-
mize additional fuel and preheat
198-201 ,
requirements. The
maximum recoverable energy
CONTAMINATED in afterburner stack gases as a
Figure 4-88. Typical direct-fired afterburner
with tangential entries for both
fuel and contaminated gases.
function of exhaust gas tempera-
ture is shown in Figure 4-90,
with waste gas energy content and temperature as parameters.
Heat recovery equipment used to recover heat from the flue gas may be
grouped under two classifications: recuperative and regenerative. Recuperative
(recovery) heat exchangers recover heat on a continuous basis and include cross
flow, countercurrent flow, and cocurrent flow heat exchangers (Figures 4-91
through 4-93). For a given heat flow and temperature drop, heat exchanger sur-
face requirements will be at a minimum in the counterflow heat exchanger (Figure
4-91). 2°2
Cocurrent flow heat exchangers are often used where a moderate level of
heat recovery is required. Countercurrent flow heat exchanger construction
4-196
-------
Figure 4-89. Portable canopy hood with stack afterburner.
(Courtesy of Eclipse Fuel Engineering Company)
maybe more costly than that for cocurrent flow, because of operation at lower
temperatures (near the clewpoint), which may require use of special alloys or
alloy steels.
Regenerative heat exchangers recover heat by intermittent heat exchange
by the alternate heating and cooling of a solid. Heat flows alternately into and
out of the same exchanger, as air and flue gas flow are periodically reversed.
Regenerative heat exchangers are of fixed and moving bed types.
4-197
-------
z ^
u
LL 10
o \
O 2
00
" o
>- H
O "°
UJ <
5 x
ZUJ
ill t-
H £
O <
CL
.AFTERBURNER TEMPERATURE
1350 "F
A fixed bed, pebble-stove,
regenerative afterburner is
shown in Figure 4-94. When
gas is passed through the pair
of pebble-type regenerators
]3500 connected back to back, the gas
is heated on the upstream side
242
1135
028 and cooled on the downstream
927
8i4 side. When the upstream bed
100 200 300 400 500
PROCESS EXHAUST TEMPERATURE, °F
707
600
and gas temperature drop, gas
flow is reversed and the heat
Figure 4-90. Afterburner energy requirements transfer process is repeated.
with fume energy content and tem-
perature parameters. Particulate matter is effectively
retained and incinerated. Heat recovery efficiencies in excess of 95 percent
, , . , 203
can be achieved.
A commonly used rotary regenerative heat exchanger consists of a
partitioned rotating cylinder containing heat sink and heat transfer surface area.
The cylinder is partitioned along its axis by appropriate gas seals so that hot
flue gas and cold waste gas may be passed through the heat exchanger on opposite
sides of the cylinder. Heat is absorbed from the hot flue gas by the heat
exchanger surface and transferred by the continuous rotation of the heat exchange
4-198
-------
STACK GASES
STACK GASES
7
r~\
JJ
AIR
AIR
AIR
Figure 4-91. Counter-flow type.
Figure 4-92. Parallel-flow type.
STACK GASES
AIR
Figure 4-93. Cross-flow type.
NATURAL GAS
'/?/v'.'';':" ' "A 'iv.-V.'>
7*.-;.Y '-'.': ~;'
'/'-' ':' '
h| PEBBLE BED Q
V -'v.
-.--..-.. .-./-
TO CHIMNEY
BLOWER
FROM KILN
Figure 4-94. Fixed-bed, pebble-stone, regenerative destencher.
(Courtesy of Research Cottrell)
331-716 0-69-23
4-199
-------
surface to the cold waste gas side where the heat is absorbed by the incoming
203
cold gases. Heat recovery efficiency ranges from 85 to 95 percent.
4.8.2.6 Fuel Requirements Maximum fuel consumption for one-pass catalytic
afterburners may be as high as 10 Btu per standard cubic foot of waste gas flow,
while systems with heat exchangers can economically reduce heat requirements
199
to about 4 Btu per standard cubic foot. The heating value of the waste gas
stream is usually limited by insurance underwriters to combustible vapor con-
centrations of less than one-fourth of the lower explosive limits of the gas mix-
ture. For organics, this is equivalent to about 13 Btu per standard cubic foot
and represents a total temperature rise of approximately 675° F, equivalent to
52° F to 55° F per Btu per standard cubic foot. Catalytic combustors are usually
equipped with automatic safety controls when treating high organic concentrations.
The heat generated by the combustion of solvent and paint fumes may be
directly recovered by recirculating the combustion gases to the oven (Figure
4-95), or indirectly recovered by means of heat exchangers (Figure 4-96).
Direct heat recovery may be advantageous in the case of catalytic combustion
because of lower oxygen requirements in the catalytic combustion zone. '
This can be advantageous with materials having a low explosive limit.
Fuel savings from the use of the heats of combustion of paint bake-oven
solvent vapors may be large enough to provide a 50 percent return on invest-
ment in the case of catalytic combustion.204
4-200
-------
ALL-METAL
CATALYST ELEMENTS
FRESH MAKE-UP AIR
PREHEAT
BURNER
SUPPLY
FAN
FROM SOLVENT
EVAPORATION ZONE
HEATED DECONTAMINATED
AIR RETURN TO OVEN
PAINT BAKE OVEN
Figure 4-95. Direct recirculation of combustion gases to recover heat.
CLEAN GASES
COLD
FRESH
AIR
/////A////////////////
SUPPLY FAN
HEATED MAKE-UP AIR
PAINT BAKE OVEN
Figure 4-96. Heat exchanger to recover heat from combustion gases.
(Courtesy of Universal Oil Products Co.)
4-201
-------
Fuel requirements and burner capacity may be determined by means of
a heat balance, using the heat of combustion of the fuel and the sensible heat
needed to raise the temperature of the waste gas and the products of combustion
up to the desired combustion temperature. The heating value of the contaminant
. , . . 185,205-208
must be deducted to determine net fuel requirements.
4.8.2.7 Modified Furnace Afterburners Existing boilers, rotary kilns, and
furnaces have been successfully modified and used for direct flame incineration.
Requirements for successful operation are:
I.. Contaminants must be combustible and non-corrosive.
2. The oxygen content of the contaminated gas must be high, or of such
volume that it does not upset or reduce furnace capacity.
3. The furnace must be operated continuously or modulated to ensure
adequate furnace temperatures.
4. The furnace must be large enough to ensure adequate residence time.
5. Conditions must be such that there is little or no deposition of par-
ticulate matter on the burner or furnace walls.
Furnace modifications, design calculations, and proven methods for
-i o (-
introducing waste fumes are given in the literature.
Odors from kraft pulp manufacture have been successfully disposed of by
introduction into a modified furnace kiln with fuel savings of over $450 per
., 209,210
month.
4-202
-------
A.8.2. 8 Hood and Duct Design Considerations Furnace inlet gases, and vapors
from paint and varnish cooking kettles, as well as from other sources, must be
maintained at temperatures above condensation to avoid exhaust duct fouling.
Collection ductwork is usually insulated and may be heated by means of an ex-
ternal duct which serves to recover heat from the flue gas, effecting a reduction
208
in combustor fuel requirements (Figure 4-97).
Duct gas velocities are usually high, ranging from 4000 to 5000 feet per
minute, to prevent the settling of particulate matter, to effect a high heat re-
covery rate between the flue gas and furnace feed gas, and to minimize the
211 212
danger of flashback and fire hazards. '
Other safety devices to minimize fire hazards may include diluting
vapors to below the lower explosive limits, using flame arresters, and
including a wet scrubber between the direct flame combustor and the vapor
source. Dilution of the vapors may be accomplished by recirculation of a por-
tion of the flue gas, with a substantial reduction in fuel requirements, as shown
. ._ 208-213
in Figure 4-97.
Flame arresters may consist of a packed bed of pebbles, metal tower
packing, aluminum rings (Figure 4-98), or corrugated metal gridwork (Figure
4-99), in conjunction with a blast gate or other pressure release device. Flash-
back through the bed is prevented by bed gas velocities in excess of flame pro-
pagation velocities, by pressure drop, as well as by cooling the flame to below
o 1 q 914
combustion temperatures. '
4-203
-------
Other types of flame arresters include spray chambers, wet seals, and
dip legs (Figure 4-100). Wet flame arresters have the disadvantage of cooling
and humidifying the exhaust gas, with a consequent increase in fuel requirements.
Wet sprays are capable of removing up to 80 percent of the solids involved in
185
paint making; there is no noticeable reduction in odor level.
Other safety devices include high- and low-temperature combustion and
flame-out control instruments.
Exhaust hoods should be close fitting to minimize ventilation requirements.
Guidance on hood design and ventilation rates is offered by the American Con-
215
ference of Governmental Industrial Hygienists.
4.8.2.9 Gas Burners Figure 4-101 shows a crossectional view of an open-
type inspiration (venturi mixer) premix burner. This mixer uses the energy
of the gas to induce primary air in proportion to the gas flow and is limited to
cases in which high pressure gas (5 to 10 pounds per square inch) is available.
Luminous flames may be produced by conventional burners by operation
at low capacity and by restricting air supply. Minimum burner capacity is
212 216 217
determined by the burner throat velocity at which flashback can occur. ' '
The turndown ratio (ratio of maximum to minimum flow rate for satisfactory
burner operation) will range from 3:1 to 5:1.
Pressure-type burners, illustrated in Figure 4-102, permit a higher rate
of heat release within a relatively small space and are available in a multitude
of designs for special applications. They are characterized by a single mixing
4-204
-------
I
to
o
Ul
1 EXHAUSTER
2 PREHEAT BURNER
3 CATALYST
4 RECYCLING DAMPER
5 HEAT EXCHANGER
STACK
DISCHARGE
COLD OUTSIDE
AIR
PREHEATED
FACTORY
SUPPLY AIR
\utt\\\u\\\\\\\
COOLING
STATION
COOKING
STATION
Figure 4-97. Integration of fume disposal from a kettle cooking operation with factory make-up air
heating. (Courtesy of Cotolytic Combustion Co.)
-------
////////S'A
PACKING
rrrrrrrrrr/
//////
'/// /t /
WASTE GAS
BLAST GATE
TO
COMBUSTOR
Figure 4-98. Packed bed flame arrester.
a:
O
03
O
(J
t
BODY
TUBE BANK
TUBE BANK
SHELL
HANDLE
Figure 4-99. Corrugated metal flame arrester
with cone removed and tube bank
pulled partly out of body.
(Courtesy of Generol Precision Systems, Inc.)
OIL
OR
WATER
WASTE GAS
Figure 4-100. Dip leg flame arrester.
4-206
-------
port or nozzle which produces a short hot flame. Gas premixing is accomplished
by use of forced inlet combustion air, usually supplied by a fan. This type of
burner has a high turndown ratio and is capable of producing an accurate control
of the gas combustion mixture.
Waste gas may be used as a source of primary and secondary air, with a
consequent reduction in fuel requirements, if the oxygen content is high and the
gas is free from deposit-forming solids.
Burners of the cyclone design, shown in Figure 4-88, are usually mounted
to fire tangentially into the combustion chamber and to assist in the cyclonic
motion and mixing of the furnace atmosphere. Burners must be capable of con-
IR1") /* O/* PI'S
tinuous modulation to accommodate changes in waste gas flow rates. ' ' '
To prevent the emission of smoke when the flame is operated to produce
a luminous flame, secondary air or waste gas may be introduced above the burner
Combustion intensity may be further increased by the use of forced air,
premixing, multiple-port burners of the type shown in Figure 4-103. Combus-
tion intensities as high as 500 Btu per cubic foot per second have been obtained
using a combination of multiple port burners and flame impingement on the sur-
-109
face of refractory brick which acts as a catalytic surface. Typical uses and
combustion characteristics for a number of burners are listed in Table 4-14.
The combustion intensity of a given burner is related to the furnace tem-
198
perature and fuel composition as indicated in the equation:
4-207
-------
NUT AND STUD
DISC
BODY
GAS INLET
SPIDER LOCK~\ SPUD
NUT AIR INLET
Figure 4-101. Cross-sectional view of open-type
inspirational premix burner.
RATIO DIAL COMBUSTION
MS INLET AIR INLET
RATIO VALVE
HOLE FOR PILOT TIP (.-MOUNTING PLATE
Figure 4-102.Cross-sectional view of forced air,
premix, multiple-port burner.
4-208
-------
Table 4-14. GAS BURNER CLASSIFICATIONS
Classification
Atmospheric
or low-pressure
burner system
Blast or high-
pressure burner
system
Extent of mixture
of air and gas
Partial, usually
less than 50%
of air required
for combustion
Air and gas not
mixed; low-veloc-
ity stratified or
diffused in com-
bustion chamber
Air and gas not
mixed; turbulent
mixing close to
nozzle but in com-
bustion chamber
Completely mixed
or nearly so before
reaching nozzle
Velocity
of
mixture
through
nozzle.
ft/min
50
to
1,200
400
to
10,000
400
to
36,000
1,200
to
36,000
Mixing
method
Gas jet mixer
or injector using
low-pressure gas
Not mixed until
in combustion
zone
Not mixed until
in combustion
zone
Premixed by air
jet mixer
Gas jet mixer
HP gas
Mechanical
mixer
Combination
of the above
Required
gas
pressure
Under
1 Ib.
Under
4 oz.
4
to
16 oz.
4 oz.
1
to
25 Ib.
4 oz.
Required
air
pressure
0
Under
4 oz.
4
to
32 oz.
4
to
32 oz.
0
0
Temperature
range, °F
100°
to
1200°
600°
to
2400°
1000°
to
2800°
1200°
to
3000°
Combustion
speed
Very
slow
Slow
Fast
Very
fast
Combustion inten-
sity, approximate
maximum heat re-
lease per cubic foot
of combustion
chamber space
10 Btu/ft3/sec
28 Btu/ft3/sec
70 Btu/ft3/sec
70 Btu/ft3/sec
555
to
1400
Btu/ft3/sec
Typical burner
assemblies
Ring burners
Pipe burners
Torch burners
Box burners
Immersion burners
Wheel burners
Diffusion burners
Radiant flame burners
Variflame burners
Radiant tube burners
Static pressure burners
Nozzle mixing
burner
Open burners
Tunnel burners
I
to
o
ID
-------
2 -3/2 -A/RT
CI = k p T C C e "" """ a (10)
3
Where: CI = combustion intensity (Btu/ft sec atm);
k is a constant;
p = atmospheric pressure;
T = furnace atmosphere temperature "absolute;
a
C , C = fuel and oxygen concentration,
e = natural log base;
A - energy of activation (approximately 42, 000 calories/gm atom);
and
R = universal gas law constant.
A heat loss of approximately 5 percent from the combustion gas can re-
duce combustion gas temperature and reduce combustion intensity by as much
as 20 percent, with a consequent reduction in afterburner combustion efficiency.
Hence it is important that combustion zone heat losses be kept at a minimum.
Heat losses can be reduced by proper insulation and by shielding the burner
from cold objects, such as ironwork, heat exchangers, masonry, or even the
sky.
ma^salfiimmtmtiiumgKggm^
Combustion efficiency is
improved if combustion takes
place at the base of the furnace
and the waste gases pass upward,
This minimizes opportunity for
channeling and bypassing.
Figure 4-103. Multiple-port high-intensity prernix
burner.
(Courtesy of Maxon Premix Burner Company)
4-210
-------
4,8.2.10_ Construction Materials Afterburner surfaces exposed to high tem-
peratures and erosive or corrosive conditions must be constructed of alloys
capable of withstanding high temperatures or must be lined with refractory
materials.
Metals Temperatures at which alloy steels are used are limited by
Underwriters' Laboratories, Inc. to approximately 200° F below the temperature
atwhich scale formation occurs. Martensitic and ferritic stainless steels are
recommended for use in areas that are exposed to wide ranges of temperature
218
and to corrosive conditions. Temperature limitations for other metals and
207
alloys are determined by design stress and safety requirements.
RefractoriesRefractories used in direct flame afterburners increase
radiant heat transfer, insulate, act as a support structure, and resist abrasion
and corrosion. In so doing, they must be capable of withstanding thermal shock.
Fire clay refractories are commonly used in incinerator and afterburner con-
struction because of low cost, spall resistance, and long service life. Fire
clay refractory bricks are classified (Table 4-15) into maximum service classes
202
according to American Society for Testing and Materials standards (ASTM).
Their softening points, as determined by pyrometric cone equivalent (PCE) help
O 1 Q
determine their maximum service class. Other requirements include limits
on shrinkage, spalling loss, and deformation under load. Castable fire clay
/M 7
refractories commonly used (Table 4-16) are of two ASTM classes.
4-211
-------
Table 4-15. ASTM CLASSIFICATION OF FIRE CLAY REFRACTORIES
Refractory type
Low heat duty
Intermediate heat duty
High heat duty
Super duty
PCE
19
29
21-32
33
Temperature, °F
2768
2984
3056-3092
3173
Table 4-16. COMMONLY USED CASTABLE FIRE CLAY REFRACTORIES
ASTM No.
24
27
Temperature, °F
2400
2700
Density,
lb/ft3
70-85
110-125
Special properties
Insulating light weight
General purpose
-------
Service temperature range and physical properties of various refractories
for corrosive conditions are shown in Figures 4-104 and 4-105 and in Table 4-17.
202 203 219
The literature contains further information. ' '
4.8.2.11 Typical Applications A summary of the afterburner applications is
presented in Table 4-18. The information was taken from published literature
and manufacturers' bulletins.
4-213
-------
I
to
5000
4500
4000
3500
3000
_ ACIDIC
Q.
2500
2000 -
1500
NEUTRAL
FIRECLAY
BASIC
GRAPHITE, 6400° F
m.
1000
SILICA CASTABLES, INSULATING HIGH CHROME, ZIRCONIA, GRAPHITE
MORTARS, BRICK ALUMINA MAGNESITE ZIRCON CARBIDES,
PLASTICS BORIDES,
NITRIDES
Figure 4-104. Service temperature ranges for refractories.
(Courtesy of McGraw-Hill Book Co.)
-------
I
to
cc
UJ
CL
UJ
I-
z.
UJ
t-
u_
o
x
O
2000
1900
1800
1700
1600
SILICA i SILICIOUS | i
"T" *T~ FIREBR!CK---4«-
BRICK BRICK
ALUMINOUS BRICK --
%A1203
%Si02 TOO
10
90
20
80
30
70
40
60
50
50
60
40
70
30
80
20
, ALUMINA
BRICK"'
90
10
100
0
COMPOSITION BY WEIGHT
Figure 4-105. Degree of refraction for alumina-silica system products.
(C ourte s y of C hem tea I Engineering Magozi ne }
-------
Table 4-17. GENERAL PHYSICAL AND CHEMICAL CHARACTERISTICS
OF CLASSES OF REFRACTORY BRICK
Type of b.-lck
Silica
Hlgh-dut>
fireclay
Super-duty
fireclay
Acid- resistant
(lype HJ
Insulating
brick
High-alumina
Extra-high
alumina
Mulllte
Chrome- fired
Magneslte-
ohrome bonded6
Magnesl te-
ch rome fired
Magneslte-
chrome
high-fired
Magneslte-
bondedb
Magneslte- fired
Zircon
Zlrconla
(stabilized)
Silicon-carbide
Graphite
Typical
chemical
composition
SltVj, 05%
3102. 54%
AI^O;,, 40%
SI02, 52%
AlsOj, 42%
81O2. 69%
A1203, 34%
Varies
Al20g,
A1203,
90-99%
AI2O3. 71%
Chrome ore.
100%
MgO, 60-«0%
8IO2. 1.2-5%
MgO, 95%,
ZK>2. 67%
Si O2, 3.1%
ZrOs, 94%
CaO, 4%
SIC, 80-907
C, 97%
bulk
density,
u./rt3
115
1.14
140
142
30-75
170
186
153
195
190
180
180
181
178
200
245
160
105
point,
*!
3100
3128
3170
3040
Varies
3200-
3400
3000-
3C50
3290
Varies
Varies
3900
3100"
4800
4175
6400
Chemical
nnture
Acid
Acid
Acid
Acid
Slightly
acid
Neutral
Slightly
acid
Neutral
Bas'c
Basic
Acid
Sltghtlv
acid
Slightly
acfd
Neutral
Defor-
mation
under
hot
loading
Excellent
Fair
Good
Poor
Poor
Good
Excellent
Excellent
Fair
Good
Excellent
Excellent
Good
Good
Excellent
Excellent
Excellent
Excellent
Apparent
poroiilly,
21
18
16
7
35-85
20
23
20
20
12
20
18
11
19
26
23
15
16
Perme-
ability
High
Moderate
High
Low
High
Low
Low
Low
Low
Very Low
High
High
Low
Moderate
Very low
Low
Very low
Low
Hot
strength
Excellent
Fair
Fair
Poor
Poor
Good
Excellent
Good
Good
Good
Good
Excellent
Good
Good
Excellent
Excellent
Excellent
Excellent
Thermal
shock
resistance
Poor3
Fair
Good
Good
Excellent
Good
Good
Good
Poor
Excellent
Excellent
Excellent
Good
Good
Good
Excellent
Excellent
Excellent
Chem ual resistance
to acid
Good
Good
Good
Insoluble In acids
except HF and
boiling phosphoric
Poor
Good except for
HF and aqua regla
Insoluble In
most acids
Fair to good
Fair except
to utrong acids
Soluble In
most acids
Very alight
Very slight
Slight re-
action with HF
Insoluble
t° alkali
Good al low lemjwraturBi
Good al low lemperalurei
Good at low temperaturw
Very resistant In
moderate concen-
trations
Poor
Very slight attack
with hot solutions
Blight reaction
Poor
Fair resistance it
low temperatures
Good resistance at
low temperatures
Very slight
Very Slight
Attacked at high
temperatures
Insoluble
Good above 1200°F.
Chemically bonded.
Dissociates above 3100'F.
4-216
-------
Table 4-18. SUMMARY OF AFTERBURNER APPLICATIONS AND LITERATURE REFERENCES
I
to
Applications
Aery late
polymerization
Asphalt blowing and
saturating
Automotive paint
baking
Bakellte manufacturing
Bonding and burn-off
Burnoff ovensa
Carbon furnacesa
Chemical processing
Coffee roastinga
Coil and strip coating
Corn popping4
Cupola gasa
Deep fat frying2
Fabric curing
Fish and vegetable
oil processing3
Food processing
Foundry core baking2
Fungicide manufacture2
Grinding wheel
sintering
Hardboard coating
and curing
Incinerators2
Kraft paper manufacture
Metal decorating2
Metal chip drying
References
Catalytic
204
204
227b. 204, 195
204, 225
204
204, 223
194
204, 224
204
204
204
185
204
204
185, 204
204
124
204
185, 204
204
Flame
178
225
178
178
192. 201
209. 224
179
209
185
228
209. 222
178
Applications
Nut roasting
Oil hydrogenationa
Oil quenching2
Oil sulfurizatlon
Paint and varnish
cocking2
Paper coating
Pharmaceutical
manufacture
Phthalic and maleic anhy-
dride manufacture3
Potato chip cooking3
Printing2
Rendering3
Resin manufacturing
and aery late
polymerization3
Rice browning3
Sewage treatment
Smoke abatement3
Smoke houses3
Stationary diesel engines
Synthetic rubber
manufacture
Tar coating
Textile finishing
Vitamin manufacture
Wax burnout,
investment casting3
Wire enameling2
References
Catalytic
204
204
204
204
204, 227
204
204
185, 204. 227
204
204. 221
204
204
204
204
194, 227
204
204
204
185, 204
194. 204, 227
Flame
178, 195, 220
209, 220, 225, 226
178. 220
178
178
178, 185
178. 220
203, 229
228, 230
185, 209
200
198
178. 226
alnvolves discharge of particulate matter.
^Underscored references contain quantitative data.
-------
REFERENCES FOR SECTION 4
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-------
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4-219
-------
25. Dennis, R., Johnson, G. A., First, M. W., and Silverman, L. "How
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35. Blosser, R. O. and Cooper, H. B. H., Jr. "Trends in Reduction of
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March 13, 1967.
4-220
-------
36. "Stack Sprays to Reduce Dust Emissions During Soot Blowing. "
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37. Stairmand, C. J. "The Design and Performance of Modern Gas
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38. "Hydraulic Scrubbing Towers." Bulletin AP525A, Buffalo Forge Co.,
Buffalo, N.Y., 1957.
39. Montross, C. F. "Entrainment Separation. " Chem. Eng., Vol. 60,
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40. "Pease-Anthony Gas Scrubbers." Bulletin M 102, Chemical Construction
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41. Walker, A. B. and Hall, R. M. "Operating Experience with a Flooded
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42. Harris, L. S. "Fume Scrubbing with the Ejector Venturi System. "
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44, Pallinger, J. "A New Wet Process for Separation of Very Fine Dust. "
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4-221
-------
48o Eckert, J. S. "Use of Packed Beds for Separation of Entrained
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50. "Schmieg Swirl - Orifice Dust Collectors." Schmieg Industries
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51. Doyle, H., and Brooks, A. F. "The Doyle Scrubber. " Ind. Eng.
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52. "Schmieg Vertical - Rotor Dust Collector." Schmieg Industries
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54, Rice, O. R., and Bigelow, C. G. "Disintegrators for Fine Cleaning
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63. Blasewitz, A. G. and Judson, B. F. "Filtration of Radioactive
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68. Massey, O. D. "How Well do Filters Trap Stray Stack Mist?"
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-------
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227. Moody, R. A. "Examples of Catalytic Afterburning in Stationary Installa-
tions and Motor Vehicles. " Staub, 2J5(11):26-30, Nov. 1965.
228. Truitt, S. M. "The Application of Gas Burner Equipment for Elimination
of Smoke and Odors from Flue-Fed Incinerators. " North American
Manufacturing Co., Cleveland, Ohio, Reprint CB-552-44-D, 4 pp.
229. McKenzie, D. "Burn Up Those Lift-Station Odors." North American
Manufacturing Co., Cleveland, Ohio.
230. Bailey, J. M. and Reed, R. J. "Fume Disposal by Direct Flame Incinera-
tion." North American Manufacturing Co. , Cleveland, Ohio.
4-237
-------
5. EMISSION FACTORS FOR PARTICULATE AIR POLLUTANTS
An emission factor is a statistical average of the rate at which pollutants
are emitted from the burning or processing of a given quantity of material.
Emission factors can also be established on the basis of some other meaningful
parameter, such as the number of miles traveled in a vehicle. To determine
emission factors, available reliable data on emissions from a particular source
or group of sources are gathered and correlated with information on process
use. The individual emission factors derived are tabulated, and either an
average or a range of values is selected for use.
Some emission factors are based on very limited data; others are based
on extensive data that are highly variable; and still others are based on ex-
tensive, consistent data. It is, therefore, important that the accuracy of the
data on which an emission factor is based be evaluated before the factor is
used for estimating emissions.
In general, the emission factors for particulate air pollutants are not
precise indicators of what particulate emissions might be from any single
process even though all the details of the process are known. Emission fac-
tors are more valid when applied to a number of processes.
5-1
-------
Emission factors listed in Table 5-1 are taken from Compilation of Air
Pollutant Emission Factors, Public Health Service publication No. 999-AP-42,
except where noted. The factors are for uncontrolled sources except as qualified
in the table. Examples of how emission factors are used follow.
Coal Combustion
Given: Source burns 10, 000 tons per year in a spreader stoker without fly
ash reinjection.
85 percent efficient multiple cyclones
Ash content 10 percent (Note: Expressed as the number 10 in making
the computation)
From Table 5-1:
Emission factor = ISA pounds per ton of coal, where A equals ash content.
Therefore:
Particulate emissions = (Process weight) (Emission factor) (Collection
efficiency factor)
Particulate emissions = L, 000 tpnS °f C°al1 ["(13) (10) pcunds °f Particulate
L year J Lv ' ^ ' tons of coal
year
Solid Waste Disposal
Given: Commercial operation burning 2, 000 tons per year of refuse
in multiple- chamber incinerator.
5-2
-------
From Table 5-1:
Emission factor3 pound per ton of refuse
Therefore:
, , . r0 nAA tons of refuse] f pounds of particulate
Particulate emissions =2, 000 3 r
year 1 I ton of refuse
year 1 I ton of refuse
pounds of particulate
= 6,000
year
Process Industries
Given: Secondary brass and bronze smelting operation with
fabric filter 99 percent efficient.
Furnace typeelectric.
Metal charged into furnace20, 000 tons per year
From Table 5-1:
Emission factor - 3 pounds per ton of metal charged
Therefore:
Particulate emissions =
tons of metal charged] f pounds of particulate]
iU, 000 I I o 0 ~«'. \ n i
year J I ton of metal charged J
pounds of particulate
= 600
year
5-3
-------
Table 5-1. PARTICUIATE EMISSION FACTORS1
Source
Particulate emission ratea
Fuel combustion - stationary sources
Coal
Pulverized
General (anthracite and bituminous)
Dry bottom (anthracite and bituminous)
Wet bottom (anthracite and bituminous)
Without fly ash reinjection
With fly ash reinjection
Cyclone (anthracite and bituminous)
Spreader stoker (anthracite and
bituminous)
Without fly ash reinjection
With fly ash reinjection
All other stokers (anthracite and
bituminous)
Greater than 10 X 106 Btu/hr
Less than 10 X 106 Btu/hr
Hand-fired equipment
(Bituminous coal only)
Residual oil
Greater than 100 X 106 Btu/hr
/-»
Less than 100 X 10 Btu/hr
Distillate oil
10 to 100 x 106 Btu/hr
Less than 10 X 106 Btu/hr
16Ablb/ton of coal burned
17A Ib/ton of coal burned
ISA Ib/ton of coal burned
24Aclb/ton of coal burned
2A Ib/ton of coal burned
ISA Ib/ton of coal burned
20AC Ib/ton of coal burned
5A Ib/ton of coal burned
2Ad Ib/ton of coal burned
20 Ib/ton of coal burned
10 lb/1000 gallons of oil burned
23 lb/1000 gallons of oil burned
15 lb/1000 gallons of oil burned
8 lb/1000 gallons of oil burned
5-4
-------
Table 5-1 (continued). PARTICULATE EMISSION FACTORS
Source
Natural gas
Greater than 100 X 106 Btu/hr
10 to 100 X 106 Btu/hr
Less than 10 X 106 Btu/hr
Wood2
Fuel combustion - mobile sources
Gasoline-powered motor vehicle
Diesel-powered vehicle
Aircraft
Jet (fan-type)
4 engine
3 engine
2 engine
1 engine
Jet (conventional)
4 engine
3 engine
2 engine
1 engine
Turboprop
4 engine
2 engine
Piston
4 engine
2 engine
1 engine
Particulate emission ratea
15 Ib/million ft3 of gas burned
18 Ib/million ft3 of gas burned
19 Ib/million ft3 of gas burned
10 Ib/ton of wood burned
12 lb/1000 gallons consumed
110 lb/1000 gallons consumed
7. 4 Ib/f light
5.6 Ib/f light
3.8 Ib/f light
1.9 Ib/f light
34.0 Ib/flight
25.5 Ib/flight
17.0 Ib/flight
8.5 Ib/flight
2.5 Ib/f light6
0. 6 Ib/flight
1.4 lb/flighte
0. 6 Ib/flight
0.3 Ib/flight
5-5
-------
Table 5-1 (continued). PARTICULATE EMISSION FACTORS
Source
Particulate emission rate
Solid waste disposal
Open burning of leaves and brush
Open-burning dump
Municipal incinerator
On-site commercial and industrial
multiple-chamber incinerator
(Los Angeles design)
Single-chamber incinerator
Domestic gas-fired incinerator
On-site residential flue-fed incinerator
Process industries - (specific examples)
Chemical industry
Paint and varnish manufacture
Varnish cooker
Alkylresin production - total
operation
Cooking and blowing of oils
Heat polymerization acrylic resins
Phosphoric acid manufacture
Thermal process absorber tail
gas with control (acid mist)
Sulfuric acid manufacture - contact
process (acid mist)
Food and agriculture industries
Coffee roasting
Direct fired roaster
Indirect fired roaster
Stoner and cooler
Instant coffee spray dryer - always
controlled with cyclone and wet
scrubber
17 Ib/ton of refuse burned
16 Ib/ton of refuse burned
17 Ib/ton of refuse burned
3 Ib/ton of refuse burned
10 Ib/ton of refuse burned
15 Ib/ton of refuse burned
28 Ib/ton of refuse burned
60-120 Ib/ton of feed
80-120 Ib/ton of feed
20-60 Ib/ton of feed
20 Ib/ton of feed
0.2-10.8 Ib/ton of phosphorus
burned
0.3-7.5 Ib/ton of acid produced
7. 6 Ib/ton of green beans
4.2 Ib/ton of green beans
1.4 Ib/ton of green beans
1.4 Ib/ton of green beans
5-6
-------
Table 5-1 (continued). PARTICULATE EMISSION FACTORS
Source
Particulate emission ratea
Cotton ginning operation (includes cotton
gin and incineration of cotton trash)
Feed and grain mills
General with 90% efficient cyclones
Wheat air cleaner with cyclone
Barley flour mill with cyclone
Alfalfa meal mill with settling chamber
and cyclone
Orange pulp dryer with cyclone
Starch manufacture - natural gas direct-
fired flash drier
Primary metal industry
Iron and steel manufacture
Sintering machine gases
Sinter machine discharge
Open hearth furnace
Oxygen lance^
No oxygen lance
Basic oxygen furnace^
Electric arc furnace
Oxygen lance&
No oxygen lance&
Blast furnace
Ore charging^
Agglomerate charging^
Scarfing
Coking operations - charging, pushing,
quenching
11. 7 Ib/bale of cotton
(500 Ib)
6 Ib/ton of product
0. 2 Ib/ton of product
3.1 Ib/ton of product
4. 0 Ib/ton of product
11. 3 Ib/ton of product
8 Ib/ton of starch
20 Ib/ton of sinter
22 Ib/ton of sinter
22 Ib/ton of steel
14 Ib/ton of steel
46 Ib/ton of steel
11 Ib/ton of steel
7 Ib/ton of steel
110 Ib/ton of iron
40 Ib/ton of iron
3 Ib/ton of steel processed
2 Ib/ton of coal
5-7
-------
Table 5-1 (continued). PARTICULATE EMISSION FACTORS
Source
Particulate emission ratea
Secondary metal industry
Aluminum smelting
Chlorination - lancing of chlorine gas
into molten metal bath
Crucible furnace
Reverberatory furnace
Sweating furnace
Brass and bronze smelting
Crucible furnace
Electric furnace
Reverberatory furnace
Rotary furnace
Gray iron foundry
Cupola
Electric induction furnace
Reverberatory furnace
Lead smelting
Cupola
Pot furnace
Reverberatory and sweating furnace
Magnesium smelting
Pot furnace
Steel foundry
Electric arc furnace
Electric induction furnace
Open hearth furnace
1000 Ib/ton of chlorine used
1.9 Ib/ton of metal processed
4. 3 Ib/ton of metal processed
32. 2 Ib/ton of metal charged
3. 9 Ib/ton of metal charged
3. 0 Ib/ton of metal charged
26. 3 Ib/ton of metal charged
20. 9 Ib/ton of metal charged
17.4 Ib/ton of metal charged
2. 0 Ib/ton of metal charged
2. 0 Ib/ton of metal charged
300 Ib/ton of metal charged
0.1 Ib/ton of metal charged
154 Ib/ton of metal charged
4.4 Ib/ton of metal charged
15.0 Ib/ton of metal charged
0.1 Ib/ton of metal charged
10. 6 Ib/ton of metal charged
5-8
-------
Table 5-1 (continued). PARTICULATE EMISSION FACTORS
Source
Particulate emission ratea
Zinc smelting
Galvanizing kettles
Calcine kilns
Pot furnaces
Sweating furnace
Mineral product industry
Asphalt saturators
Asphalt batch plant - rotary drier
Calcium carbide plant
Coke dryer
Electric furnace hood
Furnace room vents
Main stack - vents to atmosphere -
exhaust from furnace hoods always
passes through impingement scrubbers
Cement manufacture
Dry process - kiln
Wet process - kiln
Ceramic and clay processes
Ceramic clay - spray drier with cyclone
Bisque with scrubber
Catalytic material - drier, kiln and
cooler with cyclone and scrubber
Concrete batch plant - total operation
Frit manufacture - frit smelters
Glass manufacture - soda-lime process
with direct fired continuous melting
5. 3 Ib/ton of metal charged
88. 8 Ib/ton of metal charged
0.1 Ib/ton of metal charged
10.8 Ib/ton of metal charged
3.9h Ib/ton of asphalt
5. 0 Ib/ton of mix
0. 2 Ib/ton of product
1. 7 Ib/ton of product
2. 6 Ib/ton of product
2. 0 Ib/ton of product
46 Ib/barrel of cement
38 Ib/barrel of cement
15 Ib/ton of charge
2 Ib/ton of charge
6 Ib/ton of charge
0. 2 Ib/yard of concrete
16.5 Ib/ton of charge
2. 0 Ib/ton of glass
331-7180-69 - 26
5-9
-------
Table 5-1 (continued). PARTICULATE EMISSION FACTORS
Source
Particulate emission rate3
Lime production
Rotary kiln
Vertical kiln
Perlite manufacture - expanding furnace
Rock wool manufacture
Cupola
Reverberatory furnace
Blow chamber
Curing oven
Cooler
Rock, gravel and sand production
Crushing
Conveying, screening, shaking
Storage piles - wind erosion
Petroleum industry
Fluid catalytic crackers
Moving bed catalytic crackers
TCC-type unit
HCC-type unit
Kraft pulp industry
Smelt tank
Uncontrolled
Water spray
Mesh demister
Lime kiln
Recovery furnace with primary
stack gas scrubber
5-10
200 Ib/ton of lime
20 Ib/ton of lime
21 Ib/ton of charge
21. 6 Ib/ton of charge
4. 8 Ib/ton of charge
21. 6 Ib/ton of charge
3. 6 Ib/ton of charge
2.4 Ib/ton of charge
20 Ib/ton of product
1. 7 Ib/ton of product
20 Ib/ton of product
0.1 to 0. 21 Ib/ton of catalyst
circulated
0. 05 to 0. 15J Ib/ton of catalyst
circulated
0. 15 to 0. 25J Ib/ton of catalyst
circulated
20 Ib/ton of dry pulp produced
5 Ib/ton of dry pulp produced
1-2 Ib/ton of dry pulp produced
94 Ib/ton of dry pulp produced
150 Ib/ton of dry pulp produced
-------
Table 5-1 (continued). PARTICULATE EMISSION FACTORS
aEmission rates are those from uncontrolled sources, unless otherwise noted.
Vhere letter A is shown, multiply number given by the percent ash in the
coal.
cValue should not be used as emission factor. Values represent the loading
reaching the control equipment always used on this type of furnace.
Revised from 5 A.
6Flight is defined as a combination of a landing and a takeofl.
Depends on type of control.
gBased on data from NAPCA Contract No. PH 22-68-65.
Includes only solid particulate matter. In addition, about 65 Ib/hr of oil
mist may be evolved from asphalt saturators.
Revised from 0.1.
Revised from 0. 04.
5-11
-------
REFERENCES FOR SECTION 5
1. Duprey, R. L. "Compilation of Air Pollutant Emissions Factors. " U.S.
Dept. of Health, Education, and Welfare, National Center for Air Pollution
Control, Durham, N.C., PHS-Pub-999-AP-42, 1968.
2. "Procedure for Conducting Comprehensive Air Pollution Surveys." New
York State Dept. of Health, Bureau of Air Pollution Control Services,
Albany, New York, Aug. 18, 1965.
5-12
-------
6. ECONOMIC CONSIDERATIONS IN AIR POLLUTION CONTROL
6.1 SELECTION OF CONTROL SYSTEM
Most air pollution emission control problems can be solved in several
ways. In order to select the best method of reducing pollutant emissions,
each solution should be thoroughly evaluated prior to implementation. Steps
such as substitution of fuels and raw materials and modification or replace-
ment of processes should not be overlooked as possible solutions. Such
emission reduction procedures often can improve more than one pollution
problem. For example, particulate matter and sulfur oxides emissions both
may be reduced by switching from high-sulfur coal to natural gas or low-
sulfur oil. Such steps also may have the benefit of reducing or eliminating
solid waste disposal and water pollution problems. Often it is cheaper to
attack two air problems together than to approach each problem individually.
If steps such as process alterations and substitution of fuels are not feasible,
it may be necessary to use gas cleaning equipment
Figure 6-1 shows the factors to be considered in selecting of gas clean-
ing system. The first consideration is the degree of reduction of emis-
sions which may be required to meet emission standards. The degree of
6-1
-------
EMISSIONS AND EMISSIONS
STANDARDS
DETERMINES COLLECTION EFFICIENCY
CONTROL EQUIPMENT ALTERNATIVES
1
FABRIC
FILTER
u_
1
ELECTROSTATIC
PRECIPITATOR
WET
COLLECTOR
'
MECHANICAL
COLLECTOR
AFTER-
BURNER
y VOLUME
SJ- TEMPERATURE
,5s MOISTURE CONTENT
<* uj CORROSIVENESS
££ ODOR
£ < EXPLOSIVENESS
0< VISCOSITY
X
u
PROCESS
u
IGNITION POINT
SIZE DISTRIBUTION
ABRASIVENESS
HYGROSCOPIC NATURE
ELECTRICAL PROPERTIES
GRAIN LOADING «
DENSITY AND SHAPE **
PHYSICAL PROPERTIES i
O
WASTE TREATMENT
SPACE RESTRICTION
PRODUCT RECOVERY
PLANT
FACILITY
i
ENGINEERING STUDIES
HARDWARE
AUXILIARY EQUIPMENT
LAND
STRUCTURES
INSTALLATION
START-UP
WATER AVAILABILITY
FORM OF HEAT RECOVERY
(GAS OR LIQUID)
t
COST OF
CONTROL
\
POWER
WASTE DISPOSAL
WATER
MATERIALS
GAS CONDITIONING
LABOR
TAXES
INSURANCE
RETURN ON INVESTMENT
t
SELECTED
GAS CLEANING SYSTEM
DFSIRED EMISSION RATE
Figure 6-1. Criteria for selection of gas cleaning equipment.
6-2
-------
emission reduction or the collection efficiency required is dependent upon the
relationship between emissions and emission standards as shown at the top of
the figure. This is an important factor in making the choice among control
equipment alternatives. Although a control system may include two or more
pieces of control equipment, collection efficiency, as used in this chapter,
applies to individual pieces of control equipment. The usual ranges of collec-
tion efficiency for various equipment alternatives are shown in Table 6-1. The
important factors to be considered next are the gas stream and particle char-
acteristics of the process itself, as shown in the center of Figure 6-1. High
gas temperatures without cooling, for example, preclude the use of fabric
filters; explosive gas streams prohibit the use of electrostatic precipitators;
and submicron particles cannot generally be efficiently collected with
mechanical collectors. A number of factors that relate to the plant facility
should also be considered, some of which are listed in Figure 6-1. Each al-
ternative will have a specific cost associated with it, and the components of
this cost should be carefully examined. Those alternatives which meet the
requirements of both the process and the plant facility can then be evaluated
in terms of cost; on this basis, the gas cleaning system may be selected.
6-3
-------
Table 6-1. AIR POLLUTION CONTROL EQUIPMENT
COLLECTION EFFICIENCIES1'2'3
Equipment type
Efficiency Range
(on a total weight basis)
percent
Electrostatic precipitator
Fabric filters
Mechanical collector
Wet collector
Afterburner:
c
Catalytic
Direct flame
80 to 99.5+
95 to 99.9
50 to 95
75 to 99+
50 to 80
95 to 99
b
Most electrostatic precipitators sold today are designed for 98 to 99. 5 per-
cent collection efficiency.
Fabric filter collection efficiency is normally above 99.5 percent.
->
"Not normally applied in particulate control; has limited use because most
particulates poison or desensitize the catalyst.
6-4
-------
6.2 COST-EFFECTIVENESS RELATIONSHIPS
Meaningful quantitative relationships between control costs and pollutant
reductions are useful in assessing the impact of control on product prices,
profits, investments, and value added to the product. * With such relationships
at hand the alternates for solution of an air pollution problem can be evaluated
for more effective program implementation by the user of the control equip-
ment and by the enforcement agency. These cost-effectiveness relationships
sometimes are applied collectively to a meteorological or air quality control
region, where they describe the total cost impact on polluters as a result of
controlling sources; the discussion here, however, centers around cost-
effectiveness as applied to an individual source. Cost-effectiveness is a meas-
ure of all costs to the firm associated with a given reduction in pollutant emis-
sions. For computing the costs for a given system, one should consider (1) raw
materials and fuels used in the process, (2) alterations in process equipment,
(3) control hardware and auxiliary equipment, and (4) disposal of collected
emissions.
Figure 6-2 shows an example of a theoretical cost-effectiveness relation-
ship. The actual total costs of control may depart from this curve because
some cost elements, such as research and development expenditures and fixed
*Value added is generally considered to be the economic worth added to a prod-
uct by a particular process, operation, or function. "*
6-5
-------
QUANTITY OF POLLUTANTS
Figure 6-2. Cost of control.
charges (taxes, insurance, deprecia-
tion) are not directly related to the
operation of the equipment and to the
level of emissions in a given year.
The cost of control is represented on
the vertical axis and the quantity of
pollutants emitted on the horizontal
axis. Point P indicates the uncontrolled state, in which there are no control
costs. As control efficiency improves, the quantity of emissions is reduced
and the cost of control increases. In most cases, the marginal cost of control
is smaller at the lower levels of efficiency, near point P of the curve. The
curve also illustrates that as the cost of control increases, greater increments
of cost usually are required for corresponding increments of emission reduc-
tion. Process changes sometimes may result in emission reduction without
increased costs. Research and development expenditures resulting in new or
improved equipment design, improved process operations, or more efficient
equipment operations will improve the economics of control. All these factors
may substantially reduce control costs at most emission levels and shift the
cost of the control curve (CC) as illustrated by CC in Figure 6-3. Note that
as control technology develops, the cost of attaining a desired emission level
will be reduced from C to C .
a b
6-6
-------
cc
QUANTITY OF POLLUTANTS
Figure 6-3. Expected new cost of control.
Cost-effectiveness information is use-
ful in emission control decision-
making. Several feasible systems
usually are available for controlling
each source of emissions. In most
cases, the least-cost solution for
each source can be calculated at
various levels of control. After
evaluating each alternative and after considering future process expansions and
more rigid control restrictions, sufficient information should be available on
which to base an intelligent control decision.
Cost-effectiveness relationships vary from industry to industry and from
plant to plant within an industry. The cost for a given control system is signif-
icantly dependent on the complexity of the installation and the characteristics
of the gas stream and pollutant. Geographical location is another significant
factor that influences the total annual cost; for example, the components of
annual cost, such as utilities, labor, and the availability of desired sites for
waste material, vary from place to place.
6-7
-------
6.3 COST DATA
It is the purpose of this chapter to develop basic information and tech-
niques for estimating the costs of installing and operating control equipment.
Such information can be useful in developing cost-effectiveness relationships
for application of various control systems.
The control cost information included in this chapter is based on experi-
ence, a careful study of the literature, and a survey of more than 250 sup-
pliers, users, installers, and operators of air pollution control equipment.
The cost information was reviewed by a panel from the gas cleaning equip-
ment industry for reasonableness of data and methodology. The cost data
reported reflects 1968 prices, except as noted.
6.4 UNCERTAINTIES IN DEVELOPING COST RELATIONSHIPS
Cost information for control devices is indicated in Section 6.7 where,
for various types of equipment, operating capacity is plotted against cost.
The upper and lower curves indicate the expected range of costs, with the
expected average cost falling approximately in the middle. Although quanti-
tative values for collection efficiency and gas volume capacity are not listed,
higher collection efficiency, which involves more intricate engineering de-
sign, results in higher costs. Control equipment is designed for a nominal
gas volume capacity, but under actual operating conditions the volume may
vary. Similarly, the efficiency of control equipment will vary from application
6-8
-------
to application as particle characteristics, such as wettability, density, shape,
and size distribution, differ. For example, a control device designed to oper-
ate on 50,000 acfm of gas with a nominal collection of 95 percent may have an
effective operating range of from 45,000 to 55,000 acfm, and its collection
efficiency may range from 90 to 97 percent.
The effect of these independent variations is to make single point esti-
mates of cost versus size and efficiency difficult to determine. Based on the
data available, all estimates must be constructed over an interval of uncer-
tainty for each of the three variables. To make the cost estimation problem
manageable in this report, nominal high, medium, and low collection efficien-
cies have been selected for each type of control equipment, except fabric
filters. For fabric filters, the nominal high, medium, and low curves reflect
construction variations. The purchase, installed, and total annualized costs
of operation are plotted for each of the three efficiency levels over the gas
volume range indicated. Purchase, installed, and total annualized costs for
fabric filters are plotted for variations in filter construction and cleaning
methods.
Generalized categories of control equipment are discussed rather than
specific designs because of uncertainties in size, efficiency, and cost. If
required, more detailed information on the cost of various engineering innova-
tions (e.g. , packed towers of specific design to accommodate a corrosive gas
stream) should be requested from the manufacturers of the specific equipment.
6-9
-------
Cost variations associated with wet collectors are reported in Table
6-2. 3
Other difficulties exist in developing cost information for existing control
devices, especially cost estimates on the maintenance and operation of control
equipment. Individual firms may remember what a control device cost origi-
nally, but they may forget what it costs to install and operate. In addition,
internal bookkeeping and auditing systems often bury these expenditures in
total plant operating costs. For example, water and electricity used by a
control operation are not always separately metered and accountable as a
specific air pollution control cost item. Some of these costs can be identified
and assessed on the basis of industrial experience or engineering estimates.
6. 5 DESCRIPTION OF CONTROL COST ELEMENTS
6.5.1 General
The actual cost of installing and operating air pollution control equipment
is a function of many direct and indirect cost factors. An analysis of the con-
trol costs for a specific source should include an evaluation of all relevant
factors, as outlined in Figure 6-4. The control system must be designed and
operated as an integral part of the process; this will minimize the cost of con-
trol for a given emission level. The definable control costs are those that are
directly associated with the installation and operation of control systems.
These expenditure items from the control equipment user's point of view have
a breakdown for accounting purposes as follows:
6-10
-------
Table 6-2. APPROXIMATE COST OF WET COLLECTORS IN 1965"
,
o
Tvpe of collector
b,c
Cyclonic:
Small diameter multiples
Single chamber, constant
water level
Single chamber, multiple
stage, overhead line
pressure water feed
Single chamber, internal
nozzle spray
Self-induced spray ' '
b, c
Wet impingement
c,d
Venturi
Variable pressure drop
inertialc>d
c d
Mechanical '
Cost, dollars/cfm
Capacity, cfm
1,000
0.50
1.40
0.95
3.00
0.80
1.00
3.00
1.00
1.75
5,000
0.30
0.45
0.40
1. 50
0.40
0.50
1. 50
-
0.75
20,000
0.20
0.35
0.25
1.00
0.25
0.25
1.20
-
0.35
40,000
0.20
0.25
0.20
0.75
0.25
0.25
0.50
0.30
-
Basic designs, mild steel construction.
Add 30 to 40 percent to base price for fan, drive, and motor (standard
construction materials).
Q
Special materials construction costs for 1000- to 40,000-cfm range units
are approximately as follows:
Rubber lining - base increase of 65 to 115 percent.
Type 304 stainless steel - base increase of 30 to 60 percent.
Type 316 stainless steel - base increase of 45 to 100 percent.
d
Add from 10 to 40 percent to base price per additional stage as in some
cyclonic and wet impingement designs.
6-11
-------
OPERATIONAL
VARIABLES INFLUENCING
CONTROL COSTS
GAS CLEANING SYSTEM
FACTORS INFLUENCING
CONTROL COSTS
COST AREAS DETERMINING
THE NET COST OF CONTROL
to
VOLUME
POLLUTANT
GAS CLEANING
SYSTEM
TYPE
SIZE
CONSTRUCTION
MATERIAL
EFFICIENCY
PRESSURE DROP
POWER AND FUEL
WASTE
MATERIAL
UTILIZATION
ENGINEERING
STUDIES
LAND
SITE
PREPARATION
CONTROL
HARDWARE
AUXILIARY
EQUIPMENT
INSTALLATION
MATERIALS AND
SUPPLIES
MAINTENANCE
AND OPERATION
CAPITAL
CHARGES
Figure 6-4. Diagram of cost evaluation for a gas cleaning system.
-------
Capital Investment
Engineering studies
Land
Control hardware*
Auxiliary equipment*
Operating supply inventory
Installation*
Startup
Structure modification
Maintenance and Operation
Utilities*
Labor*
Supplies and materials*
Treatment and disposal of collected material
Capital Charges
Taxes*
Insurance*
Interest*
Of the expenditure items shown above, only those denoted by an asterisk
were considered in developing the cost estimates used in this chapter. Other
*Denotes cost items considered in this report
£* -I o
331-716 0 - 69 - 27
-------
factors, such as engineering studies, land acquisition, operating supply inven-
tory, and structural modification, vary in cost from place to place and there-
fore were not included. Costs for the treatment and disposal of collected
material, while also not included, are discussed in some detail in Section 6-8.
6.5.2 Capital Investment
The "installed cost" quoted by a manufacturer of air pollution equipment
usually is based on his engineering study of the actual emission source. This
cost includes three of the eight capital investment itemscontrol hardware
costs, auxiliary equipment costs, and costs for field installation.
The purchase cost curves that are shown in Section 6.7 illustrate the
control hardware costs for various types of control equipment. These purchase
costs are the amounts charged by manufacturer for equipment of standard con-
struction materials. Basic control hardware includes built-in instrumentation
and pumps. Purchase cost usually varies with the size and collection efficiency
of the control device. The purchase costs plotted on the curves are typical
for the efficiencies indicated, but these costs may vary ±20 percent from
the values shown. Of course, equipment fabricated with special materials
(e.g., stainless steel or ceramic coatings) for extremely high temperatures
or corrosive gas streams may cost much more.
The remaining capital investment items, auxiliary equipment and installa-
tion costs, are aggregated together and referred to as "total installation costs."
6-14
-------
These costs are shown in Table 6-3, expressed as percentages of the purchase
costs. These costs include a reasonable increment for the following items:
(1) erection, (2) insulation material, (3) transportation of equipment, (4) site
preparation, (5) clarifiers and liquid treatment systems (for wet collectors), and
(6) auxiliary equipment such as fans, ductwork, motors, and control instru-
mentation. The low values listed in the table are for minimal transportation
and simple layout and installation of control devices. High values are for
higher transportation cost and for difficult layout and installation problems.
The extreme high values are for unusually complex installations on existing
process equipment. Table 6-4 lists the major cost categories and related
conditions that establish the installation cost range from low to high. The
"installed cost" estimates reported in Section 6-7 are the sum of the purchase
costs and the total installation costs.
6.5.3 Maintenance and Operation
The following sections describe the working equations for the operation
and maintenance costs of various control devices. Numerical values for the
variables expressed in these equations are found in Tables 6-5 and 6-6.
6.5.3.1 General
The costs of operation and maintenance will vary widely because of dif-
ferent policies of control equipment users. This variance will depend on such
factors as the quality and suitability of the control equipment, the user's under-
standing of its operation, and his vigilance in maintaining it. Maintenance
6-15
-------
Table 6-3. TOTAL INSTALLATION COST FOR VARIOUS TYPES OF CONTROL
DEVICES EXPRESSED AS A PERCENTAGE OF PURCHASE COSTS
Equipment type
Gravitational
Dry centrifugal
Wet collector:
Low, medium energy
o
High energy
Electrostatic
precipitators
Fabric filters
Afterburners
Cost, percent
Low
33
35
50
100
40
50
10
Typical
67
50
100
200
70
75
25
High
100
100
200
400
100
100
100
Extreme high
-
400
400
500
400
400
400
High-energy wet collectors usually require more expensive fans and motors.
6-16
-------
Table 6-4. CONDITIONS AFFECTING INSTALLED COST OF CONTROL DEVICES
Cost category
Low cost
High cost
Equipment transportation
Minimum distance; simple
loading and unloading
procedures
Long distance; complex procedure for
loading and unloading
Plant age
Hardware designed as an
integral part of new plant
Hardware installed into confines of old
plant requiring structural or process
modification or alteration
Available space
Vacant area for location of
control system
Little vacant space requires extensive
steel support construction and site pre-
paration
Corrosiveness of gas
Noncorrosive gas
Acidic emissions requiring high alloy
accessory equipment using special han-
dling and construction techniques
Complexity of startup
Simple startup, no exten-
sive adjustment required
Requires extensive adjustments; testing;
considerable down time
Instrumentation
Little required
Complex instrumentation required to assure
reliability of control or constant monitoring
of gas stream
Guarantee on
performance
None needed
Required to assure designed control effi-
ciency
Degree of assembly
Control hardware shipped
completely assembled
Control hardware to be assembled and
erected in the field
Degree of engineering
design
Autonomous "package"
control system
Control system requiring extensive in-
tegration into process, insulation to
correct temperature problem, noise
abatement
Utilities
Electricity, water,
waste disposal facilities
readily available
Electrical and waste treatment facilities
must be expanded, water supply must be
developed or expanded
Collected waste material
handling
No special treatment
facilities or handling re-
quired
Special treatment facilities and/or han-
dling required
Labor
Low wages in geographical
area
Overtime and/or high wages in geographical
area
6-17
-------
Table 6-5. ANNUAL MAINTENANCE COSTS FOR ALL
GENERIC TYPES OF CONTROL DEVICES
Generic type
Gravitational and dry
centrifugal collectors
Wet collectors
Electrostatic precipi-
tators:
High voltage
Low voltage
Fabric filters
Afterburners :
Direct flame
Catalytic
Dollars per acfm
Low
0.005
0.02
0.01
0.005
0.02
0.03a
0.07
Typical
0.015
0.04
0.02
0.014
0.05
0.06b
0.20
High
0.025
0.06
0.03
0.02
0.08
o.iob
0.35
Metal liner with outside insulation.
b
Refractory lined.
6-18
-------
Table 6-6. MISCELLANEOUS COST AND ENGINEERING FACTORS
Fan efficiency = 60 percent
Pump efficiency = 50 percent
Power cost, dollars/kw-hra
All devices
Low
0.005
Typical
0.011
High
0.020
Hours of operation
8760 hours per year
24 hr/day x 365 days/yr = 8760
Power requirements vs efficiency for high-
voltage electrostatic precipitators, 10~3 kw/acfm
Low
0.19
Medium
0.26
High
0.40
Power requirements vs efficiency for low-
voltage electrostatic precipitators (10 kw/acfm)
Low
0.015
High
0.040
Liquor cost in 10 3 dollars per gallon per hour (for wet system)
Wet scrubber
Low
0.35
Typical
0.50
High
1.00
Make up liquor requirements, 0.0005 gal/hr - acfm
Based on national average of large consumers.
6-19
-------
Table 6-6 (continued). MISCELLANEOUS COST AND ENGINEERING FACTORS
Power requirements
Low efficiency
"Scrubbing" (contact) 0.0013
power, horsepower/acfm
Medium efficiency
0.0035
Scrubber liquor data
Low
Liquor circulation rate, 0.001
gal/acfm
Minimum head require-
ments, feet water *1
Typical
0.008
30
High efficiency
0.015
High
0.020
60
Pressure drop through equipment, inches of water
Generic type
Dry centrifugal collector
Fabric filter
Afterburners
Electrostatic precipitators
and gravitational
collectors
Low
-
2-3
0.5
0.1
Typical
2-3
4-5
1.0
0.5
High
4
6-8
2
1
* 1 psig = 2.3 ft water
6-20
-------
and operation usually are very difficult to define and assess, but often may
be a significant portion of the overall cost of controlling air pollutant emis-
sions. Although the combined operating and maintenance costs may be as
low as 10 percent of the annualized total cost for a gravitational settling
chamber, for example, they may be as high as 90 percent of the total an-
nualized cost for a high-efficiency wet collector.
Maintenance cost is the expenditure required to sustain the operation of
a control device at its designed efficiency with a scheduled maintenance pro-
gram and necessary replacement of any defective parts. On an annual basis,
maintenance cost in the following equations is assumed proportional to the
capacity of the device in acfm. Table 6-5 shows annual maintenance cost
factors for all types of particulate control devices. Simple, low-efficiency
control devices have low maintenance costs; complex, high-efficiency devices
have high maintenance costs.
Annual operating cost is the expense of operating a control device at
its designed collection efficiency. This cost depends on the following factors:
(1) the gas volume cleaned, (2) the pressure drop across the system, (3) the
operating time, (4) the consumption and cost of electricity, (5) the mechan-
ical efficiency of the fan, and (6) the scrubbing liquor consumption and costs
(where applicable).
6-21
-------
6. 5. 3. 2 Gravitational and Centrifugal Mechanical Collectors
In general, the only significant cost for operating mechanical collectors
is the electric power cost, which varies with the unit size and the pressure
drop. Since pressure drop in gravitational collectors is low, operational costs
associated with these units are considered to be insignificant. Maintenance
cost includes the costs of servicing the fan motor, replacing any lining worn
by abrasion, and, for multiclone collectors, flushing the clogged small dia-
meter tubes.
Cost equation - The theoretical annual cost (G) of operation and main-
tenance for centrifugal collectors can be expressed as follows:
0.7457 PHK
6356E
(1)
where:
S = design capacity of the collector, acfm
P = pressure drop inches of water (see Table 6-6)
E = fan efficiency, assumed to be 60 percent (expressed as 0. 6)
0. 7457 = a constant (1 horsepower = 0. 7457 kilowatt)
H = annual operating time (assumed 8760 hours)
K = power cost, dollars per kilowatt-hour (see Table 6-6)
M = maintenance cost, dollars per acfm (see Table 6-5)
For computational purposes the cost formula can be simplified as follows:
r fi i
G = S 195. 5 x 10 PHK + M (2)
6-22
-------
fi.R.3.3 Wet Collectors - The operating costs for a wet collector power and
scrubbing liquor costs. Power costs vary with equipment size, liquor circula-
tion rate, and pressure drop. Liquor consumption varies with equipment size
and stack gas temperature. Maintenance includes servicing the fan or com-
pressor motor, servicing the pump, replacing worn linings, cleaning piping,
and any necessary chemical treatment of the liquor in the circulation system.
Cost equation - the theoretical annual cost (G) of operation and mainten-
ance for wet collectors can be expressed as follows:
(3)
where:
S = design capacity of the wet collector, acfm
0.7457 - a constant (1 horsepower = 0.7457 kilowatts)
H = annual operating time (assumed 8760 hours)
K = power costs, dollars per kilowatt-hour
P = pressure drop across fan, inches of water (see Table 6-6)
Q = liquor circulation, gallons per acfm (see Table 6-6)
g = liquor pressure at the collector, psig (see Table 6-6)
h = physical height liquor is pumped in circulation system, feet (see
Table 6-6)
W = make-up liquor consumption, gallons per acfm (see Table 6-6)
6-23
-------
L = liquor cost, dollars per gallon (see Table 6-6)
M = maintenance cost, dollars per acfm (see Table 6-5)
E = fan efficiency, assumed to be 60 percent (expressed as 0. 60)
F = pump efficiency, assumed to be 50 percent (expressed as 0. 50)
The above equation can be simplified according to Semrau's total "con-
tacting power" concept. 6 Semrau shows that efficiency is proportional to the
total energy input to meet fan and nozzle power requirements. The scrubbing
(contact) power factors in Table 6-6 were calculated from typical performance
data listed in manufacturers' brochures. These factors are in general agreement
with data reported by Semrau. Using Semrau's concept the equation for operating
cost can be simplified as follows:
G=S fo.7457HK /Z + Qh \ + WHL + M]
L ( 1980 j J
where Z = contact power (i.e. , total power input required for collection
efficiency), horsepower per acfm (see Table 6-6). It is a combi-
nation of:
/ P \
1. fan horsepower per acfm = , and
\ 6356 E /
Oi ,. I Qg the power to atomize water\
2. pump horsepower per acfm = ., ^ f
\ 1722F through a nozzle /
The pump horsepower, Qh/1980, required to provide pressure head
is not included in the contact power requirements.
6-24
-------
fi.5.3.4. Electrostatic Precipitators - The only operating cost considered in
the operation of electrostatic precipitators is the power cost for ionizing
the gas and operating the fan. As the pressure drop across the equipment is
usually less than 1/2 inch of water, the cost of operating the fan is assumed
to be negligible. The power cost varies with the efficiency and the size of the
equipment.
Maintenance usually requires the services of an engineer or highly-
trained operator, in addition to regular maintenance personnel. Maintenance
includes servicing fans and replacing damaged wires and rectifiers.
Cost equation - The theoretical annual cost (G) for operation and
maintenance of electrostatic precipitators is as follows:
G = S [JHK + M] (4)
where
S = design capacity of the electrostatic precipitator, acfm
J = power requirements, kilowatts per acfm (see Table 6-6)
H= annual operating time (assumed 8760 hours)
K= power cost, dollars per kilowatt-hour (see Table 6-6)
M= maintenance cost, dollars per acfm (see Table 6-5)
6^5.3.5 Fabric Filters - Operating costs for fabric filters include power costs
for operating the fan and the bag cleaning device. These costs vary directly
with size of equipment and the pressure drop. Maintenance costs include costs
for servicing the fan and shaking mechanism, emptying the hoppers, and
replacing the worn bags.
6-25
-------
Cost equation - The theoretical annual cost (G) for operation and maintenance
of fabric filters is as follows:
G = S
(5)
where:
S = design capacity of the fabric filter, acfm
P= pressure drop, inches of water (see Table 6-6)
E = fan efficiency, which is assumed to be 60 percent
(expressed as 0. 60)
0.7457 = a constant (1 horsepower = 0.7457 kilowatt)
H = annual operating time (assumed 8760 hours)
K = power cost, dollars per kilowatt-hour (see Table 6-6)
M= maintenance cost, dollars per acfm (see Table 6-5)
For computational purposes, the cost formula can be simplified as follows:
G = S
195. 5 x 10 PHK + M (6)
6.5.3.6 Afterburners - The major operating cost item for afterburners is
fuel. Fuel requirements are a direct function of the gas volume, the
enthalpy of the gas, and the difference between inlet and outlet gas temperatures.
For most applications, the inlet gas temperature at the source ranges from
300° to 400° F. Outlet temperatures may vary from 1200° to 1500° F for
2
direct flame afterburners and from 730° to 1200° F for catalytic afterburners.
The use of heat exchangers may bring about a 50 percent reduction in the
7 8
temperature difference. ' Table 6-7 lists hourly fuel costs based on a
natural gas cost of $0. 60 per million Btu. No credit was given for heat
of combustion of particulate or other matter. These costs were developed
9
from enthalpies (heat content) of the process gas at given temperatures.
6-26
-------
Maintenance includes servicing the fan, repairing the refractory lining,
washing and rinsing the catalyst, and rejuvenating the catalyst.
The equation for calculating the operation and maintenance costs (G)
is as follows:
(7)
I UO
-------
Table 6-7. HOURLY FUEL COSTS
Device
Direct flame (DF)
DF with heat exchanger
Catalytic afterburner (CAB)
CAB with heat exchanger
Temperature, "F
Inlet
380
1000
380
650
Outlet
1400
1400
900
900
A
Temperature,
°F
1020
400
520
250
Fuel cost, a
dollars/acfm-hr
$0.00057
0.00023
0.00028
0.00014
&These figures include the cost of heating an additional 50 percent excess air.
It is assumed there is no heat content in the material or pollutant being consumed.
Adding the recurring maintenance and operation costs to this figure gives
a total annualized cost of control. Total annualized cost estimates are shown
in Section 6.7.
6. 5. 6 Assumptions in Annualized Control Cost Elements
Annualized control costs will differ from installation to installation
and from region to region, and certain simplifying assumptions have been
necessary to develop the cost figures of this section. If more information
for a given location is available, it is desirable to substitute this for the
assumptions used here.
6.5.6.1 Annualized Capital Cost Assumptions
The simplifying assumptions for computing the total annualized
capital cost are as follows:
1. Purchase and installation costs are depreciated over 15 years, a
period assumed to be a feasible economic life for control devices.
6-28
-------
2. The straight line method of depreciation (6-2/3 percent per year)
is used because it is the most common method used in accounting
practices. This method has the simplicity of a constant annual
writeoff.
3. Other costs called capital chargeswhich include interest, taxes,
insurance, and other miscellaneous costsare assumed to be
equal to the amount of depreciation, or 6-2/3 percent of the
initial capital cost of the control equipment installed. Therefore,
depreciation plus these other annual charges amount to 13-1/3
percent of the initial capital cost of the equipment.
6,5.6.2 Operating Cost Assumptions The following assumptions were taken
into account for computing operation and maintenance costs.
1. Power costs included in annual operating expense reflect electricity
used by all systems directly associated with the control equipment.
Electrical power requirements are computed on a constant usage
basis at a specified gas volume.
2. For wet collectors, it is assumed that the liquor is recirculated
in a closed system. Liquor consumption consists of the makeup
liquor which must be added from time to time. Stack gas tempera-
ture influences the rate of liquor loss; this influence is partially
accounted for by assuming a constant loss per cubic foot of stack
gas volume. This assumption is necessary because of the ex-
tremely wide range of stack gas temperatures.
3. The costs for electricity and water are computed on the marginal
rate classes for each size user, which assumes that any additional
consumption will be priced at the lowest rate-highest volume class
available. Except where specifically indicated, the typical values
for the pressure drop and cost of electricity (see Table 6-7) were
assumed in all control cost calculations and illustrations.
4. The disposal cost and/or recovered value of collected effluents
are not included in the operating cost calculations because of
cost differences from process to process. Disposal cost fig-
ures for several major industrial categories are reported in
Section 6.8.
331-7160-69-28
-------
6.5.6.3 Maintenance Cost Assumption It is assumed that a user of control
equipment establishes a preventive (scheduled) maintenance program and
carries it out to maintain equipment at its designed collection efficiency.
Further, it is assumed that unscheduled maintenance, such as replacement
of defective parts, is undertaken as required. The cost incurred for equip-
ment modification or repair due to an operational accident is not included.
6. 6 METHOD FOR ESTIMATING ANNUAL COST OF CONTROL FOR A
SPECIFIC SOURCE
6.6.1 General
As previously indicated, it is beyond the scope of this report to
identify and assess the cost of control for a specific source. Such assess-
ments can, however, be calculated by applying the steps outlined below.
6.6.2 Procedure
The following procedure can be used to determine the expected cost
of control for any source.
Step 1. Describe the source (including characteristics of the process),
the characteristics and consumption of fuel for combustion, and the total
number of hours in operation annually. Emissions can be determined by
making stack gas tests or can be estimated by making calculations using the
emission factors.
Step 2. Select the applicable types of control equipment. Figure 6-1
illustrates what must be considered in selecting the optimum type of control
equipment.
StepS. Specify pressure drops, efficiencies, construction material,
energy and fuel requirements, and size limitations for the selected control
equipment, taking into account any existing equipment.
Step 4. Determine the gas flow in acfm at the point of collector loca-
tion. For wet collectors, this would be the water saturated gas volume. This
should be done by taking measurements at maximum operating conditions.
6-30
-------
Step 5. Determine the estimated total purchase cost for the specific
selected device (curves found in Section 6. 7) at the required gas volume and
control efficiency. For fabric filters, select the proper filter medium for
the process.
Step 6. Multiply the cost found in step 5 by the low, typical, and
high installation cost factors (Table 6-3), and add the result to the estimated
total purchase cost to obtain the corresponding low, typical, and high total
installed costs. Conditions affecting the cost of installation are listed in
Table 6-4.
Step 7. Calculate the total annual capital cost as follows:
annualized capital cost = depreciation + capital charges
= 0.133 X total investment cost*
Step 8. Compute the cost of electricity, maintenance, and liquor
consumption.
Step 9. Compute low, medium, and high operating and maintenance
costs from the appropriate formulas:
Dry centrifugal collectors
G =S [195.5 XlO~6 PHK + M]
G = S 10.7457 HK(Z+-.+WHL + M
/ j
Wet scrubbers
[0
Electrostatic precipitator
G = S [JHK + M]
Fabric filters
ft
G = S [195. 5 X 10~ PHK + M]
Afterburners
«
G = S [195. 5 X 10~ PHK + M + HF]
*Based on the assumptions in Section 6. 5. 6.1
6-31
-------
where:
G = theoretical value for operating and maintenance costs
S = the design capacity of the collection device, acfm
P = pressure drop of the gas, inches of water
H = annual operating time
K = power costs, dollars per kilowatt-hour
Q = liquor circulation, gallons per acfm
h = physical height that liquor is pumped in circulation system, feet
Z = total power input required for scrubbing efficiency, horsepower
per acfm
M = maintenance cost, dollars per acfm
W - liquor consumption, gallons per hour per acfm
L = cost of liquor, dollars per gallon
j = power requirement, kilowatts per acfm based on efficiency
F = fuel cost, dollars per hour per acfm
Step 10. Add the typical annualized capital cost to the typical
operating and maintenance cost to yield the estimated total annualized cost
of control.
Step 11. Because the above calculation is a point estimate, the range
of costs should be investigated. For this, a variance is calculated and applied
to the total estimated annual cost. The low cost variance (V ) and high cost
variance (V ) of an equipment combination can be computed by using the square
root of the sum of the squares. The formulas for these variances are as
follows:
V. = \/(C - C)2 + (G - G)2
1 V m 1 ml
V^ = \/(C^ - C )2 + (G, - G )2
h V h m h m
6-32
-------
where:
p c and C are the low, typical, and high annual capital cost estimates,
T m h
respectively, and G , and G , and G are the low, typical, and high operation
and maintenance cost estimates. These formulas are taken from the usual
definition of the standard error of a linear combination of statistically
independent variables. They permit computation of the most probable, rather
than the extreme, range of costs.
Step 12. The high cost variance (V ) is added to the total estimated annual
cost to yield the high cost limit.
Step 13. The low cost variance (V ) is subtracted from this total esti-
mated annual cost to yield the low cost limit.
6.6.3 Sample Calculations
The following calculations illustrate the method used to determine the
total estimated annual cost of control. The following example shows the
estimation of annualized cost for a 60, 000 cfm, 90 percent (medium efficiency)
wet collector.
Step 1. Annual operating time = 8760 hours (H)
Step 2. Wet collector (given)
Step 3. 90 percent efficiency (given)
Scrubbing power required - 0. 0035 horsepower per acfm (Z)
Step 4. Actual gas flow = 60, 000 acfm (given)
Step 5. Purchase cost = $17, 000 (from Section 6.7.4 for wet collectors)
Step 6. Installation factors from Table 6-3 are 50 percent, 100 percent,
and 200 percent
Installation factor 50% 100% 200%
Installation cost 8,500 17.000 34,000
Purchase cost 17,000 17.000 17,000
Total capital cost $25,500 $34,000 $51,000
Step 7. 0.133 X Total capital cost = annual capital cost (C)
6-33
-------
C = 0.133 x $25,500 = $3400
C = 0.133 x $34,000 = $4530
m
C = 0.133 x $51, 000 = $6800
h
Step 8. Power cost, dollars/kw-hr (K)
Low Typical High
0.005 0.011 0.020
Maintenance cost, dollars/acfm, (M)
Low Typical High
0.02 0.04 0.06
_3
Liquor cost, 10 dollars/gal, (L)
Low Typical High
0.35 0.50 1.00
Head required for circulation in system, feet, (h)
Low Typical High
1 30 60
Liquor circulation, gallons per acfm, (Q)
Low Typical High
0.001 0.008 0.020
_3
Makeup liquor rate, 10 gal/hr-acfm, (W) = 0.5
Step 9. Using the following formula to determine annual operating cost
(G),
G = S Z + -TTTT:- (0.7457 HK) + WHL + M
the low, typical, and high operating and maintenance costs are as
follows:
Gl - $8200 G = $18,100 G, - $35,900
1 m h
6-34
-------
Step 10. From the steps 7 and 9,
C = $4530 G = $18,100
m m
Then, the total estimated annual cost is as follows:
C + G -$22,600
m m
Step 11. Using the square root of the sum of the squares of the
differences, the high and low cost variances are as follows:
Vl T(Cm -
/ 2
V =/(4530 - 3400) + (18,100-8200)'
V = $10,000
V, = (C, - C ) + (G, - G )
h V h m h m
/ 2 2
V =1(6800 - 4530) + (35,900 - 18,100)
V, = $17,900
h
Step 12. From Step 10, the total estimated annual cost = $22,600
From Step 11, V = $10,000
Low cost limit = $22, 600-$10, 000 = $12, 600
Step 13. Total estimated annual cost = $22, 600
From Step 11, V = $17, 900
High cost limit - $22, 600 + $17, 900 = $40, 500
Step 14. The amount of particulate matter emitted may be calculated
if the inlet conditions are known.
6-35
-------
6.6.4 Annualized Cost Variation
The previous section illustrated the probable high and low cost limits
for a single installation, taking into account the variation in costs for installa-
tion, maintenance, and operation. To compute the annualized cost for a given
emission reduction system, one must take into account four variables: (1)
collection efficiency of the system, (2) cost of installing the system, (3) cost of
operation, and (4) maintenance cost. A more complete summary of the range
of total annualized costs is shown in Table 6-8 for a 60, 000 acfm wet collector.
This table illustrates cost figures for 81 possible combinations of each of
the four variables, with each variable taking on three independent values-
low, typical, and high. It is constructed by the procedure outlined in Steps
1 through 10 in the previous section. The constants for computing these
values are taken from Tables 6-5 and 6-6. Table 6-8 shows that a low-
efficiency 60, 000 acfm wet collector with low installation, maintenance, and
operation costs will cost approximately $6100 per year to operate (extreme
upper left hand corner). The most efficient (99 percent efficiency) wet
collector, according to the table, will cost as high as $137,400 per year
to operate. The most likely costs for efficiencies of 75 percent, 90 percent,
and 99 percent are $11, 300; $22, 700; and $74, 500, respectively. The type of
data shown in Table 6-8 is useful in developing cost-effectiveness relation-
ships. Note that this table does not show the variances, V and V ; these
should be used only when the probable cost limits are desired.
6. 7 COST CURVES BY EQUIPMENT TYPE
6.7.1 General
For the convenience of those who may use the cost information described
in this chapter, the following sections contain a series of control cost curves
(see Figures 6-5 through 6-24). For each type of control equipment, a series
of curves is presented: (1) purchase cost curves, (2) installed cost curves,
and (3) annualized cost curves.
6-36
-------
Table 6-8. ILLUSTRATIVE PRESENTATION OF ANNUAL COSTS OF CONTROL
FOR 60,000 acfm WET SCRUBBER (dollars)
e
o
O
m
°h
MI
Mm
Mh
MI
MHI
Mh
MX
Mm
Mh
E =75%a'b
1
j c
1
6,100
7,300
8,500
9,500
10,700
11,900
18,300
19,500
20,700
I
m
6,800
8,000
9,200
10,100
11,300
12,500
18,900
20,100
21,300
T
n
8,100
9,300
10,500
11,500
12,700
13,900
20,300
21,500
22,700
E = 90%
m
:
1
11,800
13,000
14,200
20,300
21,500
22,700
36,900
38,100
39,300
I
m
13,000
14,200
15,400
21,500
22,700
23,900
38,100
39,300
40,500
T
n
15,200
16,400
17,600
23,700
24,900
26,100
40,300
41,500
42,700
E, = 99%
ti
j
1
35,500
36,700
37,900
71,100
72,300
73,500
128,200
129,400
130,600
I
m
37,800
39,000
40,200
73,300
74,500
75,700
130,500
131,700
132,900
T
n
42,300
43,500
44,700
77,900
79,100
80,300
135,000
136,200
137,400
CO
-q
d
E = efficiency factor.
Subscripts 1, m, and h indicate low, medium, and high ranges, respectively.
-»
"I = installation factor.
M = maintenance factor.
O = operating factor.
Note: A similar table can be generated to show the various control costs for any type of control equipment
by specifying operating conditions and calculating each entry. This procedure provides complete information
to aid in the assessment of existing controls or other control alternatives.
-------
The estimated purchase cost curves show the dollar amounts charged by
manufacturers for basic control equipment, exclusive of transportation
charges to the installation site. This basic control equipment includes
built-in auxiliary parts of the control unit, such as instrumentation and
solution pumps. The installed cost curves include the purchase costs,
additional auxiliary equipment costs, and installation costs, as described in
Section 6. 5. 2. The annualized cost curves include elements discussed in
Section 6.5.3 through 6.5.6. The assumptions, sources of data, and the
limitations used to develop this information are discussed in Sections
6.3 and 6.4.
6.7.2 Gravitational Collectors
In computing the cost of gravity collectors, three collection efficiencies
were considered. These efficiencies were based on the assumption of essentially
complete removal of 87-micron, 50-micron, and 25-micron particles, and
are designated as low, medium, and high efficiencies, respectively. The low
and medium efficiency collectors are simple expansion chambers, and the
high efficiency collector is a multiple-tray settling chamber, commonly called
a Howard separator.
In actual operation, the collection efficiency for a gravitational collector
depends on the particle size distribution. In cleaning the flue gas from a
stoker-fired coal furnace, for example, low-, medium-, and high-efficiency
collectors would have particle removal efficiencies of approximately 64 per-
cent, 75 percent, and 88 percent, respectively. In cleaning the flue gas from
a pulverized coal furnace, these same collectors, because of the smaller-
sized particles emitted by the combustion unit, would have approximate
efficiencies of 21 percent, 34 percent, and 56 percent, respectively.
The purchase costs of gravitational collectors are shown for three
difference efficiences in Figure 6-5. These are approximate costs for typical
6-38
-------
installations. If it were necessary to include insulation or a corrosion-
resistant lining, the costs would be higher. The total installed cost was also
calculated for each efficiency and is shown in Figure 6-6. The total installed
cost is the sum of the purchase and installation costs. The installation costs
were assumed to range from 33 percent to 100 percent of the purchase cost
(see Table 6-3), and this range results in a cost band for each efficiency, as
shown in the figure. No annualized cost curves are presented for these col-
lectors because operation and maintenance costs, other than for removal and
disposal of collected material, usually are negligible, except where corrosion
maybe a problem. Section 6.8 provides specific information on the disposal
of collected material.
6.7.3 Dry Centrifugal Collectors
The costs of purchasing, installing, and operating mechanical centri-
fugal collectors are given in Figures 6-7, 6-8, and 6-9 respectively. The
curves in these figures show costs for collectors that operate at nominal
efficiencies of 50 percent, 70 percent, and 95 percent (see Section 6.4).
Costs are plotted for equipment sizes ranging from 10, 000 to 1, 000, 000 acfm.
The assumptions used in calculating annual operation and maintenance costs
for dry centrifugal collectors are as follows:
1. Annual operating time = 8760 hours
2. Collector pressure drop = 3 inches of water
3. Power cost = $0. 011/kw-hr
4. Maintenance cost = $0.015/acfm
6.7.4 Wet Collectors
The costs of purchasing, installing, and operating wet collectors are
given in Figures 6-10, 6-11, and 6-12, respectively, as a function of equip-
ment size. The curves in these figures show costs for collectors that operate
at nominal efficiencies of 75 percent, 90 percent, and 99 percent (see Section
6-39
-------
100
O5
h^
o
_S 10
"o
2 5.0
o
(J
I
-------
100
Costs may vary by - 20 percent.
i i i i i i 111 i i i i i i 11
10 50 100 500 1000
GAS VOLUME THROUGH COLLECTOR, 103 acfm
Figure 6-7. Purchase cost of dry centrifugal
collectors.
'10 50 100 500 1000
GAS VOLUME THROUGH COLLECTOR, 103 acfm
Figure 6-8. Installed cost of dry centrifugal
collectors.
6-41
-------
HIGH EFFICIENCY
MEDIUM EFFICIENCY
LOW EFFICIENCY
300 500
I I I I I I II
10 50 100 500 1000
GAS VOLUME THROUGH COLLECTOR, 103 acfm
Figure 6-9. Annualized cost of operation of
dry centrifugal collectors.
1000
500
100
o
u
X
(J
o:
13
Q.
50
10
Costs may vary by ~ 20 percent.
LLLL
1 5 10 50 100 500 1000
GAS VOLUME THROUGH COLLECTOR, 103 acfm
Figure 6-10. Purchase cost of wet col lectors.
6-42
-------
1/1
o
u
o
UJ
1000
500
100
50
19
5
1
E I I I Mllll I | I | HIM I | | I I Ili
HIGH
- X
1 5 10 50 100 500 1000
GAS VOLUME THROUGH COLLECTOR, 103acfm
Figure 6-11. Installed cost of wet col lectors.
1000,=
1 5 10 50 100 500 1000
GAS VOLUME THROUGH COLLECTOR, 103 ocfm
Figure 6-12. Annualized cost of operation
of wet collectors.
-------
6.4). The basic hardware costs for medium and high collection efficiency
equipment are reported by manufacturers to lie in the same cost range and
both appear on the same curve in Figure 6-10. The higher installed cost of
a high collection efficiency system in Figure 6-11 results from the need for
larger, more expensive auxiliary equipment (based on Table 6-3). The
assumptions used in calculating annual operating and maintenance costs for
wet collectors are as follows:
1. Annual operating time = 8760 hours
2. Contact power requirements:
0. 0013 horsepower/acfm for 75 percent efficiency
0. 0035 horsepower/acfm for 90 percent efficiency
0. 015 horsepower/acfm for 99 percent efficiency
3. Power cost = $0. 011/kw-hr
4. Maintenance cost = $0. 04/acfm
5. Head required for liquor circulation in collection system =
30 feet
6. Liquor circulation = 0. 008 gallon/acfm
7. Liquor consumption = 0. 0005 gallon/hour-acfm
8. Liquor cost = $0. 0005/gallon
6.7.5 High-Voltage Electrostatic Precipitators
The costs of purchasing, installing, and operating high-voltage electro-
static precipitators are given in Figures 6-13, 6-14, and 6-15, respectively.
The curves in these figures show costs for collectors that operate at nominal
efficiencies of 90 percent, 95 percent, and 99. 5 percent. These costs are
plotted for equipment sizes ranging from 20, 000 to 1, 000, 000 acfm. The
assumptions used in calculating annual operation and maintenance costs for
high-voltage electrostatic precipitators are as follows:
1. Annual operating time = 8760 hours
2. Electrical power requirements:
6-44
-------
1000
500
O 100
U
UJ
I
U
ct
50
10
Costs may vary by - 20 percent.
10 50 100 500 1000
GAS VOLUME THROUGH COLLECTOR, 1Q3 acfm
Figure 6-13. Purchase cost of high-voltage
electrostatic precipitators.
1000
10 50 100 500 1000
GAS VOLUME THROUGH COLLECTOR, 103 acfm
Figure 6-14. Installed cost of high-voltage
electrostatic precipitators.
331-716 O - 69 - 29
6-45
-------
100
10 50 100 500 1000
GAS VOLUME THROUGH COLLECTOR, 103 acfm
Figure 6-15. Annualized cost of operation
of high-voltage electrostatic
precipitators.
Costs moy vary by - 20 percent
1 5 10 50 100
GAS VOLUME THROUGH COLLECTOR, 103 acfm
Figure 6-16. Purchase cost of low-voltage
electrostatic precipitators.
6-46
-------
0. 00019 kw/acfm for low efficiency
0. 00026 kw/acfm for medium efficiency
0. 00034 kw/acfm for high efficiency
3. Power cost = $0. 011/kw-hr
4. Maintenance cost = $0. 02/acfm
6.7.6 Low-Voltage Electrostatic Precipitators
The curves in Figures 6-16, 6-17, and 6-18 indicate purchase cost,
installed cost, and operation cost of low-voltage electrostatic precipitators
for low and high collection efficiencies based on design gas velocities of
150 and 125 feet per minute, respectively. Packaged modular low-voltage
precipitators with flow rates of less than 1500 acfm are used to collect
oil mist from machining operations. Purchase cost of such a unit usually
is less than $1200. The assumptions used in calculating annual operation
and maintenance costs for low-voltage electrostatic precipitators are as
follows:
1. Annual operating time = 8760 hours
2. Electrical power requirements:
0. 000015 kw/acfm for low efficiency
01 000040 kw/acfm for high efficiency
3. Power cost = $0. 011/kw-hr
4. Maintenance cost = $0. 02/acfm
6.7.7 Fabric Filters
Figures 6-19, 6-20, and 6-21 show purchase cost, installed cost, and
annualized cost of control for three different types of filters. Each of the
three filters is designed with about the same efficiency99. 9 percent. Costs
are plotted for equipment sizes ranging from 10,000 to 1,000,000 acfm.
The control cost curves represent the following different types of filter
installations:
6-47
-------
1000
1 5 10 50 100
GAS VOLUME THROUGH COLLECTOR, 103 acfm
Figure 6-17. Installed cost of low-voltage
electrostatic precipitators.
100
1 5 10 50 100
GAS VOLUME THROUGH COLLECTOR, 103 acfm
Figure 6-18. Annualized cost of operation
of low-voltage electrostatic
precipitators.
6-48
-------
100
o
-a
O
U
X
-------
1. Curve A represents a fabric filter installation with high-temperature
synthetic woven fibers (including fiberglass) and felted fibers cleaned
continuously and automatically.
2. Curve B represents an installation using medium-temperature synthetic
woven and felted fibers, such as Orion or Dacron, cleaned contin-
uously and automatically.
3. Curve C is the least expensive installation. Woven natural fibers are
used in a single compartment. Filters are intermittently cleaned.
This equipment is rarely designed for processes handling over 150,000
acfm.
These control cost curves do not include data for furnace hoods, ventilation
ductwork and pre-coolers that may appear only in certain installations. The
assumptions for calculating operating and maintenance costs are as follows:
I. Annual operating time = 8760 hours
2. Pressure drop of the gas through the three types of fabric filters = 4
inches of water
3. Power cost = $0. 05/acfm
4. Maintenance cost = $0. 05/acfm
6. 7. 8 Afterburners
Afterburners are separated into four categories: (1) direct flame, (2)
catalytic, (3) direct flame with heat recovery, and (4) catalytic with heat
recovery. Equipment and installation costs were obtained from both the litera-
ture and manufacturers of afterburners. Sufficient data was received on
catalytic afterburners to define the narrow purchase cost range shown in
Figure 6-22. The figure shows that purchase costs of direct flame after-
burners have a wider range than those of catalytic afterburners.
Figure 6-23 shows the installation costs for afterburners. Heat ex-
changers are considered accessory equipment and appear as part of the
installation cost. Installation costs may range from 10 percent to 100 percent
of the purchase costs, although in some situations they may be as high as 400
percent.
6-50
-------
O
U
O
LJJ
N
13
Z
10 50 100 500 1000
GAS VOLUME THROUGH COLLECTOR, 103 acfm
A HIGH-TEMPERATURE SYNTHETICS, WOVEN AND
FELT. CONTINUOUS AUTOMATIC CLEANING.
B - MEDIUM-TEMPERATURE SYNTHETICS, WOVEN AND
FELT. CONTINUOUS AUTOMATIC CLEANING.
C-WOVEN NATURAL FIBERS. INTERMITTENTLY
CLEANED - SINGLE COMPARTMENT.
Figure 6-21. Annualized cost of operation
of fabric filters.
100
50
O 10
CJ
X
(J
IT
I I I HIM
I I I Ml
1 5 10 100
GAS VOLUME THROUGH COLLECTOR, 103 Ocfm
Figure 6-22. Purchase cost of afterburners.
6-51
-------
100
OS
I
Ol
to
O 10
u
<
h-
z
FI f
1 5 10 50 100
GAS VOLUME THROUGH COLLECTOR, 103 ocfm
CABHE - CATALYTIC AFTERBURNER WITH HEAT
EXCHANGER
DFHE - DIRECT FLAME AFTERBURNER WITH HEAT
EXCHANGER
CAB - CATALYTIC AFTERBURNER
DF - DIRECT FLAME AFTERBURNER
Figure 6-23. Installed cost of afterburners.
100
50
E f
Q
UJ
Z
Z
10
1 5 10 50 100
GAS VOLUME THROUGH COLLECTOR, 1Q3 ocfm
CABHE - CATALYTIC AFTERBURNER WITH HEAT
EXCHANGER
DFHE -DIRECT FLAME AFTERBURNER WITH HEAT
EXCHANGER
CAB -CATALYTIC AFTERBURNER
DF - DIRECT FLAME AFTERBURNER
Figure 6-24. Annualized cost of operation
of afterburners.
-------
Differences in installation costs are due to the differences in burner lo-
cations relative to the emission source, and differences in structural sup-
ports, ductwork, and foundations. Installation costs for the addition of
equipment to existing plant facilities will be higher than similar costs for
new plants. Other factors accounting for different installation fees are
the degree of instrumentation required, engineering fees in manufacturers'
bids, startup tests and adjustments, heat exchangers, auxiliary fans, and
utilities. The assumptions for calculating operation and maintenance costs
are as follows:
1. Annual operating time = 8760 hours
2. Fuel cost:
$0. 57/1000 acfm-hour for direct flame afterburner with no heat
recovery
$0. 23/1000 acfm-hour for direct flame afterburner with heat
recovery
$0. 28/1000 acfm-hour for catalytic afterburner with no heat
recovery
$0. 14/1000 acfm-hour for catalytic afterburner with heat
recovery
3. Maintenance cost:
$0. 06/acfm for direct flame afterburner
$0. 20/acfm for catalytic afterburner
4. Pressure drop through all afterburner types = I inch of water
5. Power cost = $0. 011/kw-hr
Cost comparisons presented in Figure 6-24 show that the direct flame
afterburner without a heat exchanger is the most expensive. The lower
curve in Figure 6-24 shows that the annualized cost of a direct flame after-
burner with heat recovery is lower than the cost of a catalytic afterburner
without heat recovery.
6-53
-------
6. 8 DISPOSAL OF COLLECTED PARTICULATE EMISSIONS
6.8.1 General
The installation of any pollution control system designed to collect par-
ticulate matter demands a decision regarding the disposal of the collected
particulate material. This section discusses the relevant factors and illustrates
the economic consequences of disposal of the collected material.
In the past, pollution control equipment often was installed either to
reduce a severe nuisance or to recover valuable material. Such equipment not
only prevented valuable material from escaping to the atmosphere but also
reduced costly cleaning of the plant grounds and facilities.
As industrial plants become more crowded together and as the public
desires a higher quality of air, more emphasis will be placed on intensive
control activities. This emphasis will increase the demand for more effective
air pollution control. Generally, most air pollution control systems collect
material that has little economic worth.
Basically, the alternatives for handling collected particulate material
are as follows:
1. Return the material to the process.
2. Sell the material directly as collected.
3. Convert the material to a saleable product.
4. Discard the material in the most economical manner.
The process of selecting an alternative should take into account the following
questions:
1. Can the material be used within the company?
2. Is there a profitable market for the material?
3. What is the most economical method of disposal ?
4. Is there land available for a landfill ?
6-54
-------
5. Is there a source of water available for:
a. a wet pipeline system
b. disposal at sea
c. transportation by barge
6. Is there space available for a settling basin or filtering system?
7. Is there process-related equipment presently available for trans-
porting or treating the collected material ?
8. Is there access to a municipal waste treatment system?
9. Can technology and/or markets be developed for utilization of the
waste material ?
6.8.2 Elements of Disposal Systems
After examining feasible solutions to the disposal problem, the least
costly alternative that is most compatible with other operating factors in the
plant should be chosen. The decision should result from consideration of
each of the four functional elements of the disposal system described below
and their relationships to the manufacturing process.
1. Temporary storage, which allows gathering sufficient quantities
of the collected material to make final disposal more economical.
The unit cost of disposal usually is lower for greater quantities.
Temporary storage may be convenient at many points in the overall
disposal scheme, such as in the hopper or settling chamber of a
pollution control device, or in a silo some distance from the plant.
2. Transportation that moves the collected material from the particulate
control device to some location where disposal is relatively econom-
ical. In most cases, transportation displaces the material to a
location where accumulation minimizes any potential interference
with plant activities. Any single disposal system may require more
than one method of transporting the material. For example, a con-
veyor system may be used at the control device, a truck may be
used to transport the material to a landfill area, and a bulldozer
may be used to push it to its final disposal location.
3. Treatment that changes physical and/or chemical characteristics
for easier disposal. Such treatment may simplify operations and
reduce costs for handling and disposal of wastes. Frequently, for
easier transport, particulate matter is made into a slurry by adding
6-55
-------
water to it. This permits the use of a pipeline, which is often the
most economical method for transporting wastes over long distances.
Slurries from wet scrubbing pollution control systems frequently
are treated in an opposite manner: the water is removed and the
particulate matter is concentrated by filtration or sedimentation
This permits the ultimate disposal of a solid waste, rather than a
sludge or a slurry. The method of treatment should be selected
with a view to minimizing contamination of the environment. Examples
of such treatment methods are the wetting of fine dust to prevent air
pollution, the neutralization and filtration of slurries to prevent con-
tamination of receiving waters, and the proper burial of solid
material in a sanitary landfill.
4. Final disposition, which pertains to discarding the unusable material.
Material which cannot be sold, converted, or re-used ultimately
can be discarded in landfills; or sometimes it can be disposed of in
lagoons or the sea.
The following list shows some examples of the four functional elements
for both wet and dry disposal systems:
A. Storage
(1) Slurry of suspended particulate matter in water
(a) Settling basin
(b) Lagoon
(c) Tank
(2) Dry collected particulates
(a) Mound
(b) Rail car
(c) Bin
(d) Silo
B. Transportation
(I) Slurry of suspended particulates in water
(a) Barge
(b) Pipeline
(c) Truck
(d) Rail
6-56
-------
(2) Dry collected particulates
(a) Truck
(b) Rail
(c) Front-end loader
(d) Conveying system
(e) Barge
C. Treatment
(1) Slurry of suspended particulate in water
(a) Sedimentation
(b) Filtration
(c) Flotation
(d) Thickening; wet combustion
(e) Lagoons and drying beds
(f) Vacuum filtration
(g) Centrifugation; incineration
(h) Neutralization
(2) Dry collected material
(a) Compressing
(b) Wetting
D. Final Disposition
(1) Landfill
(a) Public or private disposal sites
(b) Quarry
(c) Evacuated coal mine
(2) Lagoon
(3) Dump at sea
The arrangement of these elements in an overall disposal scheme is
shown in Figure 6-25. This flow diagram shows the movement of the collected
material through various stages toward final disposal.
6-57
-------
en
oo
PROCESS
H20
H2O-
PRODUCT-
COLLECTION
EQUIPMENT
STORAGE
H20-
TRANSPORT
METHOD
STORAGE
TREATMENT
OPERATION
STORAGE
CONVERSION
TO
SALEABLE
PRODUCT
DISPOSITION OF UNUSABLE MATERIAL
Figure 6-25. Flow diagram for disposal of collected participate material from air pollution control equipment.
-------
Environmental factors such as space, utilities, disposal facilities,
and the desired form of collected waste material usually have an important
bearing on the selection of a disposal system compatible with a specific type
of particulate pollution control equipment. Therefore, a specific type of
particulate pollution control equipment may not always call for the same waste
disposal system.
fi. 8.3 Disposal Cost for Discarded Material
Table 6-9 describes various disposal systems and the related costs
within specific industries. Each system listed is specifically designed to cope
with the disposal problem and available facilities of the individual plant shown.
Therefore, drawing general conclusions about the relative costs of systems
listed in the table would be erroneous. The disposal costs shown include
capital charges and costs for labor and material. The disposal cost per ton
will be higher the smaller the quantity of material, because capital charges
for investment in facilities will remain the same regardless of quantity.
Fly ash, a residue from the combustion of coal and residual oil, probably
is the most common material collected in emission control systems. An
estimated 20 million tons of fly ash was produced in the United States in 1965.
12
Only 3 percent of this total was sold as a marketable product. If the cost for
discarding the remaining 97 percent of the fly ash as unusable waste were $1. 00
per ton or more, this would represent a total cost of $20 million or more. Based
on the data in Table 6-9, a cost of $1. 00 per ton is a typical unit cost.
In certain situations, the disposal cost of fly ash can be a major portion
of the total annualized cost for a complete pollution control system (including
disposal facilities). For example, the disposal costs can be as high as 80
percent of the total annualized cost for an emission control system with older
electrostatic precipitators which are no longer depreciated. The disposal cost
still can be as high as 50 percent for similar systems with newly installed
electrostatic precipitators, which usually have high depreciation charges.
6-59
-------
Table 6-9. COSTS OF SPECIFIC DISPOSAL SYSTEMS
Industry
Power generation
Power generation
Power generation
Power generation
Power generation
Power generation
Power generation
for chemical plant
Power generation
for chemical plant
Chemical
Chemical
Power generation
for pulp and paper
Gray iron
foundry
Petroleum
refining
Petroleum
refining
Petroleum
refining
Petroleum
refining
Petroleum
refining
Portland
cement
Soaps and de-
tergents
Collected material
Fly ash
Fly ash
Fly ash
Fly ash
Fly ash
Fly ash
Fly ash
Fly ash
Weak acid {large
volume)
Fly ash
Cupola dust
Non-dewatered
sludge
Dewatered
sludge
Sludge, filter cake,
oily solids
Oily solids
Catalyst fines
Waste dust
Suspended solids
Treatment
Sedimentation
Form pellets
Form slurry
Wetted
Sedimentation
Slurry (100,000
gal /day)
Sedimentation
Water
clarification
Slight Wetting
Transport
Pipeline
Truck
Truck
Vacuum sys-
tem, truck,
barge
Pipeline
Pneumatic
pipeline
truck
Pipeline
Truck
Barge
Barge
Pipeline
Sediment
by truck
Contract
hauling
Contract
hauling
Truck
Barge
Contract
hauling
Conveyor,
truck
Pipeline
Storage
Settling
pond
Mound
Mound
Transfer
bins, stor-
age silo
Settling
pond
Storage
silo
Silos
Tank
Tank
Dempster
dump
Bins
Final
Disposal
Landfill
(Sediment)
Landfill
City dump
Landfill
or dump
at sea
Landfill
(Sediment)
Landfill
Lagoon
Landfill
Dump at
sea
Dump at
sea
Lagoon
Landfill
Landfill
Landfill
In-plant
landfill
Dump at
sea
Landfill
Landfill
Municipal
treatment
plant
Cost estimate,
dollars/ton
0.75
0.55
1.10
2.00
2.00
2.00
1.60
0.90
3.00
1.00
2.30
1.40
4.75
2.50
20.00
7.50
2.75
1.05
2.50
6-60
-------
Table 6-10 shows a summary of fly ash disposal costs for material col-
lected from electrostatic precipitators and mechanical collectors installed in
electric utilities and is taken from a recent survey. 13 This survey analyzed
the costs of disposal, the sales, and the uses of fly ash collected by 54 electric
utilities and reported an average disposal cost of $0.74 per ton. Analysis of
the data for individual utilities revealed that disposal cost is partly a function
of geographical location. The average disposal cost per ton in the heavily-
populated East is higher than that reported elsewhere.
Table 6-10. COST OF ASH DISPOSAL BY ELECTRIC UTILITIES
Type and collection method
Fly ash (mechanical collector)
Fly ash (electrostatic precipitator)
Bottom ash
Disposal costs, dollars/ton
Low
$0.15
0.12
0.15
Medium
$0.59
0.77
1.04
High
$1.67
1.74
4.76
6.8.4 Return of Collected Material to the Process
In some process operations, collected material is sufficiently valuable to
warrant its return to the process. In these situations, the value of the recovered
material can partially or wholly pay for the collection equipment. In many ap-
plications, however, the cost for the high efficiency control systems necessary
to achieve desired ambient air quality will be greater than the revenue returned
for recovery of the material collected. This is illustrated by the hypothetical
example in Figure 6-26.
The figure shows a linear relationship between collection efficiency and
value of material recovered. It also shows a curvilinear relationship between
collection efficiency and related equipment costs. Up to the break-even point D
(which corresponds to an efficiency of about 97 percent), the recovery value
°f material collected is greater than the cost to achieve the recovery.
Ml-716 0-69-30
6-61
-------
O5
ASSUME: CFM, GRAIN LOADING CONSTANT
O
O
PROFIT MAXIMUM
VALUE OF MATERIAL
RECOVERED
BREAK EVEN F
POINT
COST OF EQUIPMENT
/ /I / / / /I/ /
70
75 80 85
EFFICIENCY, %
90
95
100
Figure 6-26.Theoretical effect of dust value on control cost.
-------
Equipment designed for efficiencies greater than 97 percent, according to the
curve, would have a higher cost than the potential recovery value.
If profit were the only control incentive, 85 percent collection efficiency
would achieve the maximum profit, as illustrated by the profit line AB. If
however, emission standards made 97 percent collection efficiency necessary,
no profit would be achieved at the break-even point D. For collection efficiency
greater than 97 percent, equipment costs would exceed recovery costs. At
99 percent efficiency, for example, control equipment would cost the amount
shown by FH, and the value recovered would be the amount GH. The difference
FG would represent an expense and can be considered as the net control cost.
The cement industry is one example where return of the collected
material to the process is commonly practiced. A survey conducted in 1956
shows that, out of 383 kilns, a total of 349 return collected dust to the pro-
14
cess. Not only does recovered dust, in such situations, have value as a
raw material, but its recovery also reduces disposal costs and decreases
other related costs for the preparation of raw materials used in the process.
6.8.5 Recovery of Material for Sale
Although material collected by air pollution control equipment may be
unsuitable for return to a process within the plant, it may be suitable for
another manufacturing activity. Hence, it may be treated and sold to another
firm that can use the material. Untreated pulverized fly ash, for example,
which cannot be reused in a furnace, can be sold as a raw material to a
cement manufacturer. It also can be used as a soil conditioner, or as an
asphalt filler, or as landfill material. For such uses, pulverized fly ash
requires no treatment and can be sold for as much as $1. 00 per ton. Pul-
verized fly ash which is treated can yield an even more valuable product.
A limited number of utilities, for example, sinter pulverized fly ash to
Produce a lightweight aggregate which can be used to manufacture bricks and
lightweight building blocks.
6-63
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At the present time, however, the sale of raw or treated collected
process material usually does not offer an opportunity to offset control costs
to a significant extent.
6-64
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REFERENCES FOR SECTION 6
1, Wilson, E. L. "Statement Presented at Hearings before the Subcommittee
on Air and Water Pollution of the Committee on Public Works, U.S.
Senate, 90th Congress, First Session on S. 780, Part4." U.S. Govern-
ment Printing Office, Washington, B.C., 1967, p. 2632.
2. Danielson, John A. (ed.) "Air Pollution Engineering Manual. " U.S.
Dept. of Health, Education, and Welfare, National Center for Air Pollution
Control, Cincinnati, Ohio, PHS-Pub-999-AP-40, 1967.
3. "Air Pollution Manual - Part II - Control Equipment." American Industrial
Hygiene Association, Detroit, Michigan, 1968.
4. "Census of Manufacture 1963." Volumes 1, 2, and 3, U.S. Bureau of
Census.
5. Ridker, Ronald G. "Economic Costs of Air Pollution. " Frederick A.
Praeger Publishers, New York, 1967.
6. Semrau, Konrad T. "Dust Scrubber Design - A Critique on the State of
the Art." J. Air Pollution Control Assoc. , Vol. 13, pp. 587-594,
Dec. 1963.
7. Sandomirsky, Alex G. , Benforado, D. M., Grames, L. D., and Pauletta,
C. E. "Fume Control in Rubber Processing by Direct-Flame Incinera-
tion." J. Air Pollution Control Assoc. , Vol. 16, pp. 673-676, Dec. 1966.
8. Hein, Glen M. "Odor Control by Catalytic and High-Temperature Oxida-
tion." Annals, New York Academy of Science, 116(2):656-662, July 1964.
9. "North American Combustion Handbook. " 1st edition, North American
Manufacturing Co. , Cleveland, Ohio.
10. Decker, L. D. "Odor Control by Incineration. " (Presented at the
Meeting of the Middle States Air Pollution Control Association Section,
Nov. 1965.)
U. Eckenfelder, W. Wesley. "Industrial Water Pollution Control. " McGraw-
Hill, New York, 1966, p. 4.
6-65
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12. Gambs, Gerard C. "Report on Flyash in England, Europe, and Soviet
Union." Research Div. Library, Consolidated Coal Co. , July 1,
1966, p. 1.
13. "53 Utilities Give Data on Flyash Sales and Uses. " Electrical World,
Vol. 168, pp. 61-63, Aug. 21, 1967.
14. Kannewurt, A. S. and Clausen, C. F. "1956 Survey, Portland Cement
Association." Report MP-54, Chicago, May 1958, p. 37.
15. Gale, W. M. "Technical Aspects of a Modern Cement Plant. " Clean
Air, 1(2):7-13, 1967.
6-66
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7. CURRENT RESEARCH IN CONTROL OF PARTICULATE MATTER
A total of 501 identified projects relating to air pollution research were
active in 1966. Of these projects, only 16 related directly to research on the
control of particulate matter. Five of the 16 projects were financed by the
Federal Government (both as in-house and contract projects), and the rest
were performed by control equipment manufacturers, public utilities, and
some of the larger basic industries.
To provide the research and development necessary to keep pace with
the particulate pollution problem and the increasing requirements for improved
control, the National Air Pollution Control Administration (NAPCA) has under-
taken a series of pollution device development system studies. These studies
will be conducted by industrial organizations under contract to NAPCA. Their
purpose is to systematically identify and carry out research needed to improve
the performance and extend the application of major pollution control equip-
ment.
These studies include research on high-temperature bag filtration directed
toward increasing bag life and determining the mechanisms that cause bags to
7-1
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2
rupture. Additional studies are under way to determine performance under
various dust inlet feed modes and the effects on filtration of particle size
distribution along the filter bag. In another study, the potential of fabric
filters for controlling fly ash emissions from power plants burning pulverized
3
coal was investigated.
Combustion research at the NAPCA includes an evaluation of emissions
4
from a pilot trench incinerator. Laboratory investigations into the effects
of fuel additives, burner operation, and burner modifications on particulate
5
emissions from oil combustion are being conducted.
Five basic types of wet scrubbers are being studied in an attempt to re-
late collection efficiency to cost of operation, to improve scrubber effectiveness
in the control of incinerator emissions, and to evaluate the scrubber as a gas-
liquid contactor. A 100-to 500-cfm test unit was constructed to carry out
£
these investigations.
Contract studies currently being conducted by NAPCA pertain to systems
analysis studies covering both theory and application of the various modes of
control of particulate matter.
A research program in the field of high-temperature electrostatic pre-
cipitation is being conducted by the U. S. Bureau of Mines. Data from a pilot
plant at which fly ash is collected show collection efficiencies in the 90 to 98
7
percent range at a temperature of 1460°F and a pressure of 80 psig.
7-2
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Research by universities and manufacturers is under way to determine
the effects of sparking rates and gas and dust flow on collection efficiencies
8,9
of electrostatic precipitators.
Wet scrubber research includes a study of the parameters affecting
particle collection in a venturi scrubber and removal of particles by foam
in a sieve plate column. Investigations into the performance parameters of
12 13
the flooded disc scrubber have been reported. '
Cloth filtration application studies by private companies are under way
enlarge oil- and coal-fired steam generators ' and sinter plants.
Additional research is being conducted by equipment manufacturers in an
effort to improve technology on the collection of particulate matter.
The October 1968 issue of the Journal of the Air Pollution Control
Association is devoted entirely to current aerosol research progress reports.
7-3
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REFERENCES FOR SECTION 7
1. "Guide to Research in Air Pollution. " U. S. Dept. of Health, Education,
and Welfare, National Center for Air Pollution Control, Washington, D. C,
PHS-Pub-981, 1966.
2. Spaite, P. W. and Harrington, R. E. "Endurance of Fiberglass Filter
Fabrics." J. Air Pollution Control Assoc. , 1/7(5):310-313, May 1967.
3. Borgwardt, R. H., Harrington, R. E., and Spaite, P. W. "Filtration
Characteristics of Fly Ash from a Pulverized Coal Fired Power Plant."
J. Air Pollution Control Assoc. , 1_8(6):387-390, June 1960. (Presented
at the 60th Annual Meeting of the Air Pollution Control Association,
Cleveland, Ohio, June 1967, Paper No. 67-35.)
4. Burckle, J. O. , Dorsey, J. A. , and Riley, B. T. "The Effects of the
Operating Variables and the Refuse Types on the Emissions from a
Pilot Scale Trench Incinerator." In: Proceedings of the 1968 National
Incinerator Conference, American Society of Mechanical Engineers,
New York, pp. 34-41.
5. Wasser, J. H., Hangebrauck, R. P., and Schwartz, A. J. "Effect of
Air-Fuel Stoichiometry on Air Pollutant Emissions from an Oil Fired
Test Furnace." J. Air Pollution Control Assoc. , 3L8(5):332-337, May
1968.
6. Private communication from Chief, Control Equipment Research Unit,
Process Control Engineering Program, National Center for Air Pollution
Control, 1968.
7. Shale, C. C. "Progress in High Temperature Electrostatic Precipita-
tion." J. Air Pollution Control Assoc. , 1.7(3):159-160, March 1967.
8. Penney, G. W. "Electrostatic Precipitation Studies at Carnegie Institute
of Technology." J. Air Pollution Control Assoc. , Vol. 17, pp. 588-589,
Sept. 1967.
9. Robinson, M. "Electric Wind Turbulence in Electrostatic Precipitation. "
J. Air Pollution Control Assoc. , Vol. 17, pp. 605-606, Sept. 1967.
10. Theodore, L. "A Study of Venturi Scrubbers." J. Air Pollution Control
Assoc., r7(9):598-599, Sept. 1967.
7-4
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11. Taheri, M. and Calvert, S. "Removal of Small Particles from Air by
Foam in a Sieve-Plate Column." J. Air Pollution Control Assoc., 18(4):
240-245, April 1968.
12. Walker, A. B. and Hall, R. M. "Operating Experience with a Flooded
Disc ScrubberA New Variable Throat Orifice Contactor." J. Air
Pollution Control Assoc. , JL8(5):319-323, May 1968.
13. Orr, C., Burson, J. H., and Keng, E. Y. H. "Aerosol Research in
Chemical Engineering at Georgia Tech. " J. Air Pollution Control
Assoc., 1/7(9):590-592, Sept. 1967.
14. Felgar, D. N. and Ballard, W. E. "First Years Experience with Full-
Scale Filterhouse at Alamitos Bag Filterhouse." Southern California
Edison Company, Los Angeles, 1965.
15. Smith, R. I. "Baghouse Collectors on Oil and Coal Fired Steam Genera-
ting Plants." Public Electric and Gas Company, Newark, New Jersey.
(Unpublished.)
16. Smith, J. H. "Testing Feasibility of Baghouse on Windbox End of
Sinter Plant. " Kaiser Steel Corp. , Fontana, California. (Unpublished.)
7-5
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8. BIBLIOGRAPHY
The following bibliography contains a broad listing of articles pertaining to
particulate air pollution control. The articles are arranged according to spe-
cific source categories. The following arrangement of categories is intended
to aid the reader in locating articles in specific areas.
INTERNAL COMBUSTION ENGINES
Piston Engines - Gasoline - Automotive Type 8-3
Piston Engines - Diesel 8-6
HEAT AND POWER SOURCES
Coal Combustion 8-8
Oil Combustion 8-14
Gas Combustion 8-17
Nuclear Power 8-18
REFUSE DISPOSAL SOURCES
Open Burning 8-18
Municipal Incinerators 8-19
On-Site Incinerators 8-21
Other Disposal Methods 8-24
METALLURGICAL PROCESS SOURCES
Aluminum 8-26
Copper 8-26
Iron and Steel 8-27
Lead 8-32
Zinc 8-32
CHEMICAL PROCESS SOURCES
Mineral Acids 8-33
Pulp and Paper 8-35
Oil Refineries 8-36
Paint and Varnish 8-37
Plastics and Resins 8-37
Other Chemicals 8-38
5-1
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8. BIBLIOGRAPHY (Continued)
MINERAL PROCESS SOURCES
Bituminous Concrete Manufacturing 8-39
Calcium Carbide 8-40
Cement 8-40
Concrete Batch Plants 8-41
Ceramic, Clay, and Refractories 8-41
Glass and Frit 8-41
Gypsum 8-42
Lime 8-42
Pits and Quarries 8-42
Other 8-43
FOOD AND AGRICULTURAL SOURCES
Coffee Roasting 8-44
Cotton Ginning 8-44
Feed and Grain 8-44
Fish Meal Processing 8-45
Other 8-45
3-2
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INTERNAL COMBUSTION ENGINES
PISTON ENGINES - GASOLINE - AUTOMOTIVE TYPE
Beckman, E. W. , Fagley, W. S. , and Sarto, J. O. "The Cleaner Air Package -
Exhaust Emission Control by Chrysler. " In: Hearings before the Subcommittee
on Air and Water Pollution of the Committee on Public Works, U.S. Senate,
90th Congress, 1st Session, Feb. 13-14 and 20-21, 1967, pp. 411-424.
Bush, A. F. , Glater, R. A. , Dyer, J. , and Richards, G. "The Effects of
Engine Exhaust on the Atmosphere When Automobiles Are Equipped with
Afterburners." Univ. of Calif. Report 62-63, Dept. of Engineering, Los
Angeles, Dec. 1962, 38 pp.
Derndinger, Hans-Otto. "Motor Vehicle Engines." [Kraftfahrzeugmotoren. ]
VDI (Ver. Deut. Ingr.) Z. (Duesseldorf), 108(19):842-845, July 1966. (Text
in German.)
Ebersole, G. D. and McReynolds, L. A. "An Evaluation of Automobile Total
Hydrocarbon Emissions." In: Vehicle Emissions, Part II, SAE Progress in
Technology Series, Society of Automotive Engineers, New York, 1966, Vol. 12,
pp. 413-428. (Presented at Mid-Year Meeting, Society of Automotive Engineers,
Detroit, Michigan, June 6-10, 1966, Paper 66048.)
Eldib, I. A. "Problems in Air Pollution and Their Solutions with New Tech-
nology." In: Technical and Social Problems of Air Pollution, Symposium of
Metropolitan Engineers Council on Air Resources, New York, 1966, pp. 7-28.
Fiala, E. and Zeschmann, E. G. "The Exhaust Gas Problem of Motor Vehicles,
Parti." [Zum Abgasproblem der Strassenfahrzeuge, Teil 1. ] Automobiltech.
Z. (Stuttgart), 67(9):302-308, Sept. 1965.
Fiala, E. and Zeschmann, E. G. "The Exhaust Gas Problem of Motor Vehicles,
Part II. " [Zum Abgasproblem der Strassenfahrzeuge, Teil 2.] Automobiltech.
Z. (Stuttgart), 67_(12):419-422, Dec. 1965.
"The Control of Automobile Emissions (Ford Crankcase Emissions Control
System, Ford Thermactor System for Exhaust Control). " Ford Motor Co. ,
Dearborn, Michigan, 1966, 6 pp.
Gardner, J. W. "Automotive Air Pollution. " 3rd Report of the Secretary of
Health, Education, and Welfare to the U. S. Congress Pursuant to Public Law
88-206, The Clean Air Act, 89th Congress, 2nd Session, Document No. 83,
March 25, 1966, 17 pp.
3-3
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Grant, E. P. and Nissen, W. E. "California's Program for Motor Vehicle
Emission Control." In: Proceedings, International Clean Air Congress,
Parti, London, 1966, Paper VI/19, pp. 210-212.
Heinen, C. M. "The Development and Manufacture of Control Equipment. "
Arch. Environ. Health, 16(1):98-104, Jan. 1968.
Hirao, O. "Problems of Air Pollution Due to Vehicle Emission Gases. "
J. Japan Soc. of Mechanical Engineers (Tokyo), 69(575): 1568-1572, 1966.
Hunigen, E. , Jaskulla, N. , and Wettig, K. "The Reduction of Carcinogenic
Contaminants in Exhaust Gases of Petrol Engines through Fuel Additives and
Choice of Lubricants." In: Proceedings, International Clean Air Congress,
Part I, London, 1966, Paper VI/12, pp. 191-193.
Jackson, M. W. "Effects of Some Engine Variables and Control Systems on
Composition and Reactivity of Exhaust Hydrocarbons. " In: Vehicle Emissions,
Part II, SAE Progress in Technology Series, Vol. 12, Society of Automotive
Engineers, New York, 1966, pp. 241-247.
Jackson, W. E. "Air Pollution from Automobiles in Philadelphia. " Preprint.
(Presented at the 58th Annual Meeting of the Air Pollution Control Association,
Toronto, Canada, June 20-24, 1965, Paper 65-137.)
Jensen, D. A. "Sources and Kinds of Contaminants from Motor Vehicles -
Informative Report No. 4. " J. Air Pollution Control Assoc. , _14(8):327-328,
Aug. 1964.
Jensen, D. A. "Separating Fact from Fiction in Auto Smog Control. " Arch.
Environ. Health, M(l):150-154, Jan. 1967. (Presented at the American
Medical Association Air Pollution Medical Research Conference, Los Angeles,
March 2-4, 1966.)
Kopa, R. D. , Tribus, M. , Scope, S. , and Treat, R. "Exhaust Control
Devices: An Investigation of Exhaust 'Scrubbing' Devices. " In: 1st Report
of Air Pollution Studies, Univ. of Calif, at Los Angeles, Dept. of Engineering,
July 1955, 22 pp.
Larsen, R. I. "Motor Vehicle Emissions and Their Effects. " Public Health
Rept. , 77(ll):963-969, Nov. 1962.
Lohner, Kurt, Muller, Herbert, and Zender, W. "About the Process Tech-
nique for the Combustion of Exhaust Gases in Gasoline Engines in Stationary
8-4
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Operations." [Uber die Verfahrenstechnik der Nachverbrennung der Abgase von
Ottomotoren bei stationarem Betrieb. ] VDI (Ver. Deut. Ingr.) Z. (Duesseldorf),
109/31): 1488, Nov. 1967. (Text in German.)
Ludwig, J. H. "The Vehicle Pollution Problem." Preprint. (Presented at the
American Public Power Association Conference, Denver, Colo., May 8-11,
1967.)
Ludwig, J. H. "Progress in Control of Vehicle Emissions." J. Sanit. Eng.
Div., Am. Soc. Civil Engrs. , 93(SA-4):73-79, Aug. 1967.
Meurer, S. "Change in the Concept of Mixture Formation and Combustion in
Diesel Engine. " [Der Wan del in der Vorstellung von Ablauf der Gemisch-
bildung und Verbrennung im Dieselmotor. ] Motortech. Z. , 27(3):131-139,
March 1966.
Morris, J. P. and Calonge, A. B. "Contamination Generation of Internal
Combustion Engines. " Preprint. (Presented at the 4th Annual Technical
Meeting and Exhibit, American Association for Contamination Control, Miami
Beach, Florida, May 25-28, 1965.)
Ridgway, Stuart L. and Lair, John C. "Automotive Air Pollution: A System
Approach." J. Air Pollution Control Assoc. , 1_0(4):336-340, Aug. 1960.
Rispler, L. and Ross, C. R. "Ventilation for Engine Exhaust Gases. "
Occupational Health Rev. , 17(4): 19-22, 1965.
Rose, A. H. "Summary Report of Vehicular Emissions and Their Control. "
Preprint. (Presented at the Winter Annual Meeting, American Society of
Mechanical Engineers, Chicago, Illinois, Nov. 1965.)
Schenk, Rudolf, Flory, Fritz, and Hofmann, Hans. "Reduction of Harmful
Exhaust Gas Emissions in Gasoline Motors by Means of Suction-Tube Gasoline
Injection. " [Herabsetzung der schadlichen Abgasemissionen bei Ottomotoren
durch Saugrohr-Benzineinspritzung. ] Motortech. Z. (Stuttgart), _28(10):399-
402, Oct. 1967. (Text in German.)
Starkman, E. S. "Engine Generated Air Pollution - A Study of Source and
Severity." Preprint. (Presented at Federal International Des Societes
Ingenieures Techniques de 1'Automobile, Germany, June 15, 1966.)
Varchavski, I. L. "Some Theoretical Problems of Providing Less Toxic
Operation of Automobile Engines. " Proceedings of the International Clean Air
Egress, Parti, London, 1966, p. 212. (Unpublished.)
3-5
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Yamaki, N. "Several Problems on Control of Motor Vehicle Exhaust Pollution.
J. Japan Petroleum Inst. (Tokyo), 1(9):682-696, Sept. 1965. (Text in Japanese.
PISTON ENGINES - DIESEL
Braubacher, M. L. "Reduction of Diesel Smoke in California. " Preprint.
(Presented at the West Coast Meeting, Society of Automotive Engineers, Los
Angeles, California, Aug. 8-11, 1966, Paper 660548.)
Chittawadgi, B. S. and Dave, N. R. "Reducing Smoke in Diesel Exhaust
Gases." Indian Eastern Engr. (Bombay), l£9(5):221-225, May 1967.
Fawell, H. D. "Road Vehicle Pollution - Black Smoke - Some Causes and
Possible Method of Control. " In: Proceedings, Clean Air Conference,
Harrogate, England, 1964, pp. 117-126.
Glover, I. "The Fuel Additive Approach Towards the Alleviation of the
Nuisance of Diesel Smoke. " J. Inst. Petrol., 52(509): 137-160, May 1966.
Golothan, D. W. "The Use of a Fuel Additive to Control Diesel Exhaust
Smoke: Service Performance and Marketing Experience. " Proceedings,
International Clean Air Congress, Parti, London, 1966, pp. 163-167,
Paper VI/13.
Grant, E. P. and Nissen, W. E. "California's Program for Motor Vehicle
Emission Control. " Proceedings, International Clean Air Congress, London,
1966, pp. 210-212, Paper VI/9.
Groebler, H. "Exhaust Gas Washing and Noise Absorbing Device for Diesel
Motors." [Auspuffgaswasch- und Larmschluckgerat fuer Dieselmotoren. ]
Hedlund, Folke, Ekberg, Gustav, Mortstedt, Sten-Erik, and As lander, Alle.
"Diesel Exhaust Gases. Investigation with Proposals for Action. " Communica-
tions Department, Stockholm, Sweden, Guidance Group Concerning Develop-
ment Work in the Field of Motor Vehicle Exhaust Gas, Sept. 1967.
Jensen, D. A. "Separating Fact from Fiction in Auto Smog Control. " Arch.
Env. Health, 14(1):150-154, Jan. 1967. (Presented at the American Medical
Association, Air Pollution Medical Research Conference, Los Angeles,
March 2-4, 1966.)
Jensen, D. A. "Sources and Kinds of Contaminants from Motor Vehicles,
Informative Report No. 4. " J. Air Pollution Control Assoc. , _14(8):327-328,
Aug. 1964.
-------
Johnson, K. R. "The Control of Smoke Emission from Diesel Engine Vehicles."
lv The Implications of Air Pollution Control, Vol. 1. National Physical
Research Laboratory, Council for Scientific and Industrial Research, Surban,
South Africa, 1964, pp. 2-1 - 2-16.
Ludwig, J. H. "Seminar on Air Pollution by Motor Vehicles. " Preprint.
U.S. Public Health Service, Cincinnati, Ohio, 1967, 54 pp.
McConnell, G. and Howells, H. E. "Diesel Fuel Properties and Exhaust Gas-
Distant Relations ?" Preprint. (Presented at the Automotive Engineering
Congress, Society of Automotive Engineers, Detroit, Michigan, Jan. 9-13,
1967, Paper 670091.)
Meyer, W. E. "Controlling Odor and Smoke from Diesel Exhaust. " In:
Proceedings, Sanitary Engineering Conference on Air Resources Planning and
Engineering, Pittsburgh, Pa. , 1965, pp. 41-54.
Rao, T. V. L. "Diesel Smoke. " J. Inst. Engrs. , 46(1):5-19, Sept. 1965.
Reed, L. E. arid Wallin, S. C. "Methods of Removing Smoke from the Exhaust
Gases of Diesel Engines. " In: Proceedings, Harrogate Conference, National
Society for Clean Air, London, England, 1960, pp. 3-7.
Rispler, L. and Ross, C. R. "Ventilation for Engine Exhaust Gases. "
Occupational Health Rev. , 17_(4): 19-22, 1965.
Rose, A. H. "Summary Report of Vehicular Emissions and Their Control. "
Preprint. (Presented at the Winter Annual Meeting, American Society of
Mechanical Engineers, Chicago, 111., Nov. 1965.)
Springer, K. J. , Lepisto, P. , and Wood, C. "Investigation of Diesel Powered
Vehicle Odor and Smoke." Southwest Research Institute, San Antonio, Texas,
Proposal 10-4336A, Nov. 19, 1965, 46pp.
Springer, K. J. "Investigation of Diesel Powered Vehicle Odor and Smoke. "
Southwest Research Institute, San Antonio, Texas, March 26, 1967, 16pp.
(Monthly Progress Report 2, Feb. 15-March 15, 1967.)
Springer, K. J. "Investigation of Diesel Powered Vehicle Odor and Smoke
Part 2." Southwest Research Institute, San Antonio, Texas, May 3, 1967,
12PP. (Monthly Progress Report 3, March 15-April 15, 1967.)
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Springer, K. J. "Investigation of Diesel Powered Vehicle Odor and Smoke-
Part 2. " Southwest Research Institute, San Antonio, Texas, May 26, 1967,
12 pp. (Monthly Progress Report 4, April 15-May 15, 1967.)
Springer, K. J. "Investigation of Diesel Powered Vehicle Odor and Smoke-
Part 2." Southwest Research Institute, San Antonio, Texas, July 1, 1967,
102 pp. (Monthly Progress Report 5, May 15-June 15, 1967.)
Springer, K. J. "Investigation of Diesel Powered Vehicle Odor and Smoke
Part 2." Southwest Research Institute, San Antonio, Texas, Aug. 1, 1967,
17 pp. (Monthly Progress Report 6, June 15 - July 15, 1967.)
Springer, K. J. "Investigation of Diesel Powered Vehicle Odor and Smoke
Part 2." Southwest Research Institute, San Antonio, Texas, Sept. 1, 1967,
184 pp. (Monthly Progress Report 7.)
HEAT AND POWER SOURCES
COAL COMBUSTION
Barker, K. and MacFarlane, W. A. "Fuel Selection and Utilization. " World
Health Organization Monograph Ser. 46 (Air Pollution), 1961, pp. 345-363.
Bins, R. V. "Air Pollution Control System at Bay Shore Generating Plant of
the Toledo Edison Company." Air Eng. , 8_(5):20-22, 24, May 1966.
Borgwardt, R. H. , Harrington, R. E. , and Spaite, P. W. "Filtration
Characteristics of Fly Ash from a Pulverized Coal-Fired Power Plant. " J.
Air Pollution Control Assoc. , 18(6):387-390, June 1968. (Presented at the
60th Annual Meeting, Air Pollution Control Association, Cleveland, Ohio,
June 11-16, 1967, Paper 67-35.)
Bovier, R. F. "Sulfur-Smoke Removal System. " Preprint. (Presented at
the 26th Annual American Power Conference, Chicago, 111. , April 16, 1964.)
Bovier, R. F. , Tigges, A. J. , Verrochi, W. A. , and Lambert, W. H.
"Solving a Valley Air Pollution Problem. " Preprint. (Presented at the 54th
Annual Meeting, Air Pollution Control Association, New York, June 15, 1961.
"Sonic Smoke CollectingBackground Information. " Braxton Corporation,
Medfield, Mass. , April 1965, 86 pp.
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Burke, S. A. and Collins, K. E. "The Performance of the B. C. U. R. A.
Fully-Automatic Smokeless Stoker for Central Heating. " J. Inst. Heating
Ventilating Engrs. (London), Vol. 34, pp. 114-128, July 1966.
Cahill, William J. , Jr. "Control of Participate Emissions on Electric
Utilities Boilers. " In: Proceedings, Metropolitan Engineers Council on Air
Resources Symposium on New Developments in Air Pollution Control, New
York, Oct. 23, 1967, pp. 74-84.
Chamberlin, R. L. and Moodie, G. "What Price Industrial Gas Cleaning?"
In: Proceedings of International Clean Air Congress, Parti, London, 1966,
pp. 133-135. (Paper V/7.)
Cuffe, S. T. and Gerstle, R. W. "Emissions from Coal-Fired Power Plants:
A Comprehensive Summary. " Dept. of Health, Education, and Welfare,
National Center for Air Pollution Control, Cincinnati, Ohio, PHS-Pub-999-
AP-35, 1967, 26 pp.
Cuffe, S. T. , Gerstle, R. W. , Orning, A. A., and Schwartz, C. H. "Air
Pollutant Emissions from Coal-Fired Power Plants, Report No. 1." J. Air
Pollution Control Assoc. , _14(9):353-362, Sept. 1964.
Danielson, J. A. "Air Pollution Engineering Manual. " Dept. of Health,
Education, and Welfare, National Center for Air Pollution Control, Cincinnati,
Ohio, PHS-Pub-999-AP-40, 1967, 892pp.
Debrun, G. "The Continuous Measurement of the Dust Content of the Com-
bustion Gases, at the Exit of the Dust Collectors in the Large Central Power
Stations of Electricite de France. " [La mesure en continu de 1'empoussiere-
ment des gaz de combustion a la sortie des depoussiereurs des grandes
centrales thermiques E. D. F. ] Pollut. Atmos. (Paris), _9(34):84-90, April -
June 1967. (Text in French.)
"Dust Control Methods. " Coal Age, 7_2(8):56-62, Aug. 1967.
Engelbrecht, H. L. "Electrostatic Precipitators in Thermal Power Stations
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Fernandas, J. H. , Sensenbaugh, J. D. , and Peterson, D. G. "Boiler
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-------
Flodin, C. R. and Haaland, H. H. "Some Factors Affecting Fly-Ash Collector
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Gartrell, F. E. "Control of Air Pollution from Large Thermal Power
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Hangebrauck, R. P. , von Lehmden, D. J. , and Meeker, J. E. "Sources of
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"Restricting Dust Emission from Forced-Draft Boiler Installations, Capacity
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begrenzung Dampfkessel liber 10 t/h Leistung Steinkohlenfeuerungen mit
Unterwind-Zonenwanderrost. ] VDI (Verein Deutscher Ingenieure) Kommission
Reinhaltung der Luft, Duesseldorf, Germany, VDI No. 2091, Nov. 1961, 22 pp.
(Translated from German.)
"Restricting Dust Emission from Forced-Draft Boiler Installations, Capacity
30 ton/hr and Over, Hard Coal-Dust Fired with Dry Ash Removal. "
[Staubauswurfbegrenzung Dampferzeuger liber 10 t/h Leistung Steinkohlen-
Staubfeuerungen mit trockenem Ascheabzug.J VDI (Verein Deutscher Ingenieure)
Kommission Reinhaltung der Luft, Duesseldorf, Germany, VDI No. 2092,
Nov. 1961, 22pp. (Translated from German.)
"Restricting Dust Emission from Forced-Draft Boiler Installations, Capacity
30-600 ton/hr and Over, Hard Coal-Dust Fired with Liquid Ash Removal. "
(Staubauswurfbegrenzung Dampferzeuger liber 10 t/h Leistung Steinkohlen-
Staubfeuerungen mit flussigem Ascheabzug.] VDI (Verein Deutscher Ingenieure)
Kommission Reinhaltung der Luft, Duesseldorf, Germany, VDI No. 2039,
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"Restricting Dust Emission from Natural-Draft Steam Generators, Capacity
25 ton/hr and Less, Lignite-Fired with Stationary or Mechanical Grates. "
[Staubauswurf Dampferzeuger uber 10 t/h Leistung Braunkohlen-Rostfeuerungen
feststehende Roste oder mechanische Roste ohne Unterwind.] VDI (Verein
Deutscher Ingenieure) Kommission Reinhaltung der Luft, Duesseldorf, Germany,
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Schueneman, J. J. "Air Pollution from Use of Fuel - Current Status and Future
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Schueneman, J. J. "Some Aspects of Marine Air Pollution Problems on the
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Smith, W. S. and Gruber, C. W. "Atmospheric Emissions from Coal Combus-
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OIL COMBUSTION
Alliot, L. , Auclair, M. , Labardin, A., Mauss, F. , Four, R. , and lehle, F.
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8-14
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Hangebrauck, R. P. , von Lehmden, D. J. , and Meeker, J. E. "Sources of
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"Pollution of the Atmosphere in the Detroit River Area. " International Joint
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Reminiczky, K. "High Soot Emission by Small Oil Stoves. " [Kis olajtuzelesek
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"Report on Smoke Performance of Vessels Plying the Detroit River During
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Schueneman, J. J. "Some Aspects of Marine Air Pollution Problems on the
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Smith, W. S. "Atmospheric Emissions from Fuel Oil Combustion - An Inven-
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Wentink, G. "Measurements of Soot Concentration in the Combustion Gases of
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GAS COMBUSTION
Barker, K. and MacFarlane, W. A. "Fuel Selection and Utilization. " In:
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NUCLEAR POWER
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"Techniques for Controlling Air Pollution from the Operation of Nuclear
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REFUSE DISPOSAL SOURCES
OPEN BURNING
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MUNICIPAL INCINERATORS
Bender, R. J. "Incinerator Plant- Plus." Power, _lll(l):62-64, Jan. 1967.
Beorse, B. , Kurtz, P., Mizushima, J. , Chipman, R. D. , and Bush, A. F.
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Bump, R. L- "The Use of Electrostatic Precipitators for Incinerator Gas
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Corey, R. C. "Some Fundamental Considerations in the Design and Use of
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Fife, J. A. and Boyer, R. A., Jr. "What Price Incineration Air Pollution
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Greeley, S. A., Clarke, S. M. , and Gould, R. H. "Design and Performance
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Kaiser, E. R. "Prospects for Reducing Particulate Emissions from Large
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Kreichelt, T. E. "Air Pollution Aspects of Tepee Burners Used for Disposal
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Pascual, S. J. and Pieratti, A. "Fly Ash Control Equipment for Municipal
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"Air Pollution Problems from Refuse Disposal Operations in Philadelphia and
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Rogus, C. A. "An Appraisal of Refuse Incineration in Western Europe. " In:
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Stenburg, R. L. , Hangebrauck, R. P. , von Lehmden, D. J. , and Rose, A. H. ,
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and Trends." In: Proceedings of the National Incinerator Conference, New
York, May 1-4, 1966, pp. 1-38.
Sterling, M. "Bush and Trunk Burning Plant in the City of Detroit. " J. Air
Pollution Control Assoc. , l_5(12):580-582, Dec. 1965.
Syrovatka, Z. "New Incineration System for Town Refuse. " Czech. Heavy
fold., Vol. 11, pp. 15-18, 1966.
Walker, A. B. "Electrostatic Fly Ash Precipitation for Municipal Incinerators -
A Pilot Plant Study. " In: Proceedings of the National Incinerator Conference,
New York, 1964, pp. 13-19.
Wegman, L. S. "An Incinerator with Refractory Furnaces and Advanced Stack
Gas Cleaning Systems. " In: Proceedings of Metropolitan Engineers Council
on Air Resources, Symposium on Incineration of Solid Wastes, New York, 1967,
pp. 34-42.
Williamson, J. E. and MacKnight, R. J. "Incineration." In: Air Pollution
Engineering Manual, Public Health Service, Cincinnati, Ohio, PHS-Pub-
999-AP-40, 1967, pp. 413-428.
ON-SITE INCINERATORS
Albinus, G. "Reducing the Emission of Small Waste Incinerators by Structural
and Control Measures." Staub, 25(11):17-20, Nov. 1965.
331-7160-69-32 "
-------
"How to Control Participate Emissions to Abate Air Pollution. " Heating, Piping,
and Air Conditioning, pp. 137-152, June 1959.
"Apartment House Incinerators (Flue-Fed). " National Academy of Sciences,
Building Research Advisory Board, Washington, D. C. , Pub. 1280, 1965, 38pp.
Calaceto, R. R. "Sludge Incinerator Fly Ash Controlled by Cyclonic Scrubber. "
Public Works, 94(2): 113, Feb. 1963.
Challis, J. A. "Three Industrial Incineration Problems. " In: Proceedings of
the National Incinerator Conference, American Society of Mechanical Engineers,
New York, May 1-4, 1966, pp. 208-218.
Fernandes, J. H. "Incinerator Air Pollution Control Equipment. " In: Econom-
ic Study of Solid Waste Disposal Needs and Practices, Vol. 4, Technical-Eco-
nomic Overview, Combustion Engineering, Inc., Windsor, Conn., Nov. 1, 1967.
Fife, J. A. "Refuse Disposal and the Mechanical Engineer. " (Compounding
Problems Promise a Major Role for the Mechanical Engineer.) Heating, Piping,
Air Conditioning, 3^(11):93-100, Nov. 1966.
Flood, L. P. "Air Pollution from Incinerators - Causes and Cures." Civil
Eng. , pp. 44-48, Dec. 1965.
Haedike, E. W. , Zavodny, S. , and Mowbray, K. D. "Auxiliary Gas Burners
for Commercial and Industrial Incinerators." In: Proceedings of the National
Incinerator Conference, American Society of Mechanical Engineers, New York,
May 1-4, 1966, pp. 235-240.
Houry, E. and Koin, H. W. "Principles of Design of Smokeless, Odorless
Incinerators for Maximum Performance. " American Gas Assoc. , Cleveland,
Ohio, Research Bulletin 93, Dec. 1962, 41 pp.
Kaiser, E. R. and Tolciss, J. "Control of Air Pollution from the Burning of
Insulated Copper Wire. " J. Air Pollution Control Assoc. , J13(l):5-ll, Jan.
1963.
Kaiser, E. R. and Tolciss, J. "Smokeless Burning of Automobile Bodies."
J. Air Pollution Control Assoc. , l_2(2):64-73, Feb. 1962.
Lieb, H. "Dust Separation and Flue Gas Composition of the Industrial Refuse
Incineration Plant of the Base. " Mitt, der Grosskesselbesitzer, Vol. 93,
pp. 434-437, Dec. 1964.
8-22
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MacKnight, R. J., Williamson, J. E. , Sableski, J. J. , Jr. , and Dealy, J. O.
"Controlling the Flue-Fed Incinerator. " J. Air Pollution Control Assoc. ,
10(2):103-109, 125, April 1960.
"Apartment House Incinerator Criteria. " New York City Dept. of Air Pollution
Control, March 1966.
"Criteria Used for Upgrading Existing Apartment House Incinerators in the
City of New York. " New York City Dept. of Air Pollution Control, Jan. 1967,
21pp.
"Criteria for Incinerator Design and Operation. " Dept. of Health, Air Pollu-
tion Control Service, Ontario, Canada, May 1966, 20pp.
"Air Pollution Control Section. " In: Domestic Incinerator Report, Phila-
delphia, Pa., Feb. 1963.
Papovich, M. , Northcraft, M. , Boabel, R. W., and Thomburgh, G. E.
"Wood Waste Incineration." Oregon State College, Engineering Experiment
Station, Corvallis, 1961, 8 pp.
Smith, S. "New Way to Scrub Incinerator Gases. " Air Eng. , _2(5):40-42,
May 1960.
Stenburg, R. L. "Modern Incineration of Combustible Material - Industrial
and Commercial. " Preprint. U.S. Dept. of Health, Education, and Welfare,
Div. of Air Pollution. (Presented at the East Central Section, Air Pollution
Control Association Meeting, Columbus, Ohio, Sept. 20, 1962.)
Stenburg, R. L. "Modern Methods of Incineration. " Air Eng. , Vol. 6,
pp. 20-21, 34, March 1964.
Stenburg, R. L. "Status of the Flue-Fed Incinerator as a Source of Air
Pollution." Am. Ind. Hyg. Assoc. J. , Vol. 24, pp. 505-516, Oct. 1963.
Sterling, M. "Air Pollution Control and the Gas Industry. " J. Air Pollution
Control Assoc. , 11 (8):354-361, Aug. 1961.
Vickerson, G. L. "Fly Ash Control Equipment for Industrial Incinerators. "
In: Proceedings of the National Incinerator Conference, New York, May 1-4,
1966, pp. 241-245.
8-23
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Voelker, E. M. "Control of Air Pollution from Industrial and Household
Incinerators." In: Proceedings of the 3rd National Conference on Air Pollu-
tion, Washington, D. C., 1966, pp. 332-338.
Voelker, E. M. "Essentials of Good Planning." In: Proceedings of the National
Incinerator Conference, New York, 1964, pp. 148-152.
Williams, R. E. "Incineration Practice and Design Standards. " In: Proceed-
ings of Clean Air Conference, Univ. of New South Wales, Vol. 2, Paper 27,
p. 26.
Williamson, J. E. , Netzley, A. B. , Sableski, J. J. , Talens, P. G. , Walters,
D. F., and Brown, R. S. "Incineration." In: Air Pollution Engineering
Manual, U.S. Dept. of Health, Education, and Welfare, Public Health Service,
Cincinnati, Ohio, PHS-Pub-999-AP-40, 1967, pp. 428-506.
Williamson, J. E. , MacKnight, R. J. , and Chass, R. L. "Multiple-Chamber
Incinerator Design Standards for Los Angeles County. " Los Angeles County
Air Pollution Control District, Calif., Oct. 1960, 32pp.
Woodland, R. G. , Hall, M. C. , and Russell, R. R. "Process for Disposal of
Chlorinated Organic Residues." J. Air Pollution Control Assoc. , 15(2):56-58,
Feb. 1965.
Woodruff, P. H. and Wene, A. W. "General Overall Approach to Industrial
Incineration. " In: Proceedings of the National Incinerator Conference,
American Society of Mechanical Engineers, New York, May 1-4, 1966, pp.
219-225.
OTHER DISPOSAL METHODS
Bowerman, F. R. "Transfer Operations." In: Proceedings of the National
Conference on Solid Waste Research, American Public Works Association,
Chicago, Feb. 1964, 75 pp.
Bugher, R. D. "Transportation Systems." In: Proceedings Surgeon General's
Conference on Solid Waste Management, U.S. Public Health Service, National
Center for Urban and Industrial Health, Cincinnati, Ohio, PHS-Pub-1729, 1967,
pp. 73-86.
"Car Junkyards Try Sophistication. " BusinessWeek, No. 1904, pp. 108-112,
Feb. 26, 1966.
8-24
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"Compositing - Is it Economically Sound?" Refuse Removal J. , Summer 1965.
"Do You Need a Sanitary Landfill ?" U. S. Dept. of Health, Education, and
Welfare, Public Health Service, Washington, D. C. , PHS-Pub-1012, 1963,
5pp.
Golueke, C. G. and McGaughey, P. H. "Future Alternatives to Incineration
and their Air Pollution Potential. " In: Proceedings of the 3rd National Con-
ference on Air Pollution, Washington, D. C. , Public Health Service,
PHS-Pub-1649, 1967, pp. 296-305.
Harding, C. I. "Recycling and Utilization. " In: Proceedings of the Surgeon
General's Conference on Solid Waste Management, Cincinnati, Ohio, U. S.
Public Health Service, PHS-Pub-1729, 1967, pp. 105-119.
Haug, L. "When Does Transfer Pay Off. " Refuse Removal J. , Aug. 1966.
"How to Build a Fill. " 1963 Sanitation Industry Yearbook, p. 20.
"Scrap and Salvage. " 1963 Sanitation Industry Yearbook, p. 24.
Seely, R. J. "Solid Waste Report for the City of Chicago. " Chicago, Illinois,
1966, 33 pp.
Vogely, W. A. "Abandoned and Scrap Automobiles. " In: Proceedings of the
Surgeon General's Conference on Solid Waste Management, Cincinnati, Ohio,
PHS-Pub-1729, 1967, pp. 51-60.
Weaver, L. "The Sanitary Landfill. " Preprint. U. S. Dept. of Health,
Education, and Welfare, Public Health Service, March 1956.
Weston, R. F. "Future Alternatives to Incineration and their Air Pollution
Potential. " In: Proceedings of the 3rd National Conference on Air Pollution,
Washington, D. C. , U. S. Public Health Service, PHS-Pub-1649, 1967,
pp. 306-308.
Wiley, J. S. and Krochtitzky, O. W. "Composting Developments in the United
States." Compost Science, _6(2):5-9, Summer 1965.
8-25
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METALLURGICAL PROCESS SOURCES
ALUMINUM
Barenstein, M. "Air Pollution Control in Non-Ferrous Metallurgical Industry -
The Use of Wet Scrubbers." Ind. Heating, 43(10): 1866-1868, 1870, Oct. 1967.
Junker, E. "Electrostatic Filters for Exhaust Gas Cleaning at Pressure Die
Casting Machines. " [Electrofliter zur Abluftreinigung an Druckgiessmaschinen.;
Giesserei (Dusseldorf), 54(6): 152-154, March 16, 1967.
Ott, R. R. and Hatchard, R. E. "Control of Fluoride Emissions at Harvey
Aluminum, Inc. - Soderberg Process Aluminum Reduction Mill. " J. Air
Pollution Control Assoc. , _13 (9): 437-443, Sept. 1963.
Rothman, S. C. "Engineering Control of Industrial Air Pollution: State of the
Art, 1966." Heating, Piping, Air Conditioning, pp. 141-148, March 1966.
Schnitt, H. and Moser, E. "Further Developments of the Fluorine Problems
in the Aluminum Industry. " [Weitere Entwicklungen zum Fluorproblem in der
Aluminum Industrie. ] Z. fuer Erzbergau Metallhuettenwesen, 18(3):111-115,
March 1965.
Teller, A. J. "Control of Gaseous Fluoride Emissions. " Chem. Eng. Progr. ,
63(3):75-79, March 1967.
Wagner, K. "Possibilities for Exhaust Air Cleaning in Pressure Die Casting
Foundries." [Moglichkeiten fur Abluftreinigung in Druckgiessereien. ]
Giesserei (Dusseldorf), 54(6): 150-152, March 16, 1967.
COPPER
Hausberg, G. and Kleeberg, U. "Installation for Purification of Waste Gases
Generated during Chlorine Treatment of Light Metal Foundry Melts."
[Abgasreinigungsanlagen fur die Chlorbehandlung von Leichtmetallschmelzen. ]
Giesserei (Duesseldorf), 53(5):137-141, March 3, 1966.
Jackson, N. H. "Fume Emissions from the Melting of Copper and its Alloys. "
In: Parti, Proceedings of the Clean Air Congress, London, 1966, Paper VI/7,
pp. 177-178.
8-26
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Johnson, R. K. "The New Hayden Smelter - Its Unique Design Features."
J. Metals, pp. 376-381, June 1959.
"Restricting Dust Emission from Copper - Ore Smelters. " [Staubauswurf-
begrenzung, Kupfererzhutten. ] VDI, Kommission Reinhaltung der Luft, Dussel-
dorf, VDI No. 2101, Jan. 1960, 24pp.
IRON AND STEEL
Adams, R. L. "Application of Baghouses to Electric Furnace Fume Control."
J. Air Pollution Control Assoc. , 1£(8):299-302, Aug. 1964.
Archer, A. "Clean Air and the Iron Foundry. " In: Part I, Proceedings of the
International Clean Air Congress, London, 1966, Paper IV/8, pp. 99-102.
Basse, B. "Gases Cleaned by the Use of Scrubbers. " Blast Furnace Steel
Plant, pp. 1307-1312, Nov. 1956.
Bloomfield, B. D. "Costs, Efficiencies, and Unsolved Problems of Air
Pollution Control Equipment. " J. Air Pollution Control Assoc. , 17(l):28-32,
Jan. 1967.
Brandt, A. D. "Current Status and Future Prospects - Steel Industry Air
Pollution Control. " In: Proceedings of the 3rd National Conference on Air
Pollution, Washington, D. C. , 1966, pp. 236-241.
Broman, C. "Scrubbing for Clean Air. " Preprint. (Presented at the 59th
Annual Meeting, Air Pollution Control Association, San Francisco, Calif. ,
June 20-24, 1966.)
Campbell, W. W. and Fullerton, R. W. "Development of an Electric Furnace
Dust-Control System. " J. Air Pollution Control Assoc. , _12(12) :574-577, 590,
Dec. 1962.
Chamberlin, R. L. and Moodie, G. "What Price Industrial Gas Cleaning?"
In: Part I, Proceedings of the International Clean Air Congress, London,
Paper V/7, 1966, pp. 133-135.
Cooper, R. L. and Lee, G. W. "Alleviation of Air Pollution in the Coking
Industry. " In: Part I, Proceedings of the International Clean Air Congress,
London, 1966, Paper V/l, pp. 117-119.
8-27
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Cosby, W. T. "The Impact of Oxygen on Gas Cleaning in the Steel Industry. "
Iron & Steel, 36(14):632-637, Dec. 18, 1963.
Davies, E. and Cosby, W. T. "The Control of Fumes from Arc Furnaces. "
In: Fume Arrestment, Spec. Report 83, William Lea and Co. , Ltd. , London,
1964, pp. 133-143.
Douglas, I. H. "Direct Fume Extraction and Collection Applied to a Fifteen
Ton Arc Furnace. " In: Fume Arrestment, Spec. Report 83, William Lea and
Co. , Ltd. , London, 1964, pp. 144-149.
Dublinskaya, F. E. , Zaitsev, M. M. , and Zhigalina, I. S. "Purification of
Gases Originating from Melting Steel in Oxygen Converters when Removed
with the Combustion of the Carbon Monoxide. " Steel (English translation),
Vol. 6, pp. 500-501, June 1966. (From Russian.)
"Dust Out of Foundries. " Metal (London), 1_(1):55, June 1966.
Elliott, A. C. and Lafreniere, A. J. "Collection of Metallurgical Fumes from
Oxygen Lanced Open Hearth Furnaces. " J. Metals (Japan), jU3(6):743-747,
June 1966. Also: J. Air Pollution Control Assoc. , 1_4(10) :401-406, Oct. 1966.
Ellison, W. and Wechselblatt, P. M. "Cupola Emission Cleaning Systems-
Utilizing High Energy Venturi Scrubbing. " Modern Casting, 50(2):76-82,
Aug. 1966.
Engelberg, F. "Dust Generation and Removal in Shot-Blasting Chambers. "
[Staubentwicklung in Schleuderradputzraumen und Entstaubung. ] Giesserei
(Dusseldorf), 54(6): 144-148, March 16, 1967.
Engels, L. H. "Feed Gas Cleaning in Coke Oven Larry Cars. " (A Contribu-
tion to the Wet Separation of Dusts.) Staub (English Translation), 26(11):23-31,
Nov. 1966.
"Foundry Fume Disappears - Gas Cleaning at Ford's Leamington Plant. " Iron
and Steel (London), 40(l):8-9, Jan. 1967.
Frame, C. P. and Elson, R. J. "The Effects of Mechanical Equipment on
Controlling Air Pollution at No. 3 Sintering Plant, Indiana Harbor Works,
Inland Steel Company. " J. Air Pollution Control Assoc. , 13^(12) :600-603,
Dec. 1963.
8-28
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Fullerton, R. w. "Impingement Baffles to Reduce Emissions from Coke
Quenching." j. Air Pollution Control Assoc. , 17(12) :807-809, Dec. 1967.
"Gas Scrubber Installation Successfully Controls Foundry Cupola Emissions. "
Air Eng. , JJ(3):8, 11, March 1966.
Greaves, M. J. "The Effect of Modern Burdens on Blast Furnace Design. "
J. Metals (Japan), _18(3):378-384, March 1966.
Harris, E. R. and Beiser, F. R. "Cleaning Sinter Plant Gas with Venturi
Scrubber." J. Air Pollution Control Assoc. , lj^(2) :46-49, Feb 1965.
Hemon, W. C. L. (ed. ) (Tech. Committee TI-6) "Air Pollution Problems of
the Steel Industry. " Informative Report TI-6, Technical Committee, J. Air
Pollution Control Assoc. , _10(3):208-218, 253, June 1960.
Henschen, H. C. "Wet Vs Dry Gas Cleaning in the Steel Industry. " J. Air
Pollution Control Assoc. , 1_8(5) :338-342, May 1968. (Presented at the 60th
Annual Meeting, Air Pollution Control Association, Cleveland, Ohio, June 11-16,
1967, Paper 67-149.)
Herrick, R. A. , Olsen, J. W. , and Ray, F. A. "Oxygen- Lanced Open Hearth
Furnace Fume Cleaning with a Glass Fabric Baghouse. " J. Air Pollution
Control Assoc. , 1.6(1): 7- 11, Jan. 1966.
Hoff, H. and Maatsch, J. "Converter Waste Gas Cleaning by the 'Minimum
Gas' Method at Fried-Krupp. " In: Fume Arrestment, Special Report 83,
W. Lea and Co. , London, 1964, pp. 104-108.
Holland, M. andWhitwam, K. B. "Direct Fume Extraction for Large Arc
Furnaces. " In: Fume Arrestment, Special Report 83, William Lea and Co. ,
London, 1964, pp. 150-159.
Hoy, D. "Dust Control in the Foundry. " Foundry Trade J. (London), 122
(2631):545-548, May 11, 1967.
Jackson, A. "Fume Cleaning in Ajax Furnaces. " In: Fume Arrestment,
Special Report 83, William Lea and Co. , London, 1964, pp. 61-64.
Johnson, J. E. "Wet Washing of Open Hearth Gases. " Iron Steel Eng. ,
44(2):96-98, Feb. 1967.
Kapitulskiil, V. B. and Kogan L. A. "A Comparison of the Hygiene Character-
istics of the' Smokeless and Ordinary Methods of Charging Coke Ovens. " Coke
Chem. (USSR), No. 8, pp. 29-31, 1966.
8-29
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Krikau, F. G. "Effective Solids Removal for Basic Oxygen Furnace Flue Dust
Pollution Control. " (Presented at the 28th Annual Meeting, American Power
Conference, April 26-28, 1966.)
Lemke, E. E. , Hammond, W. F. , and Thomas, G. "Air Pollution Control
Measures for Hot Dip Galvanizing Kettles. " J. Air Pollution Control Assoc.,
10(l):70-77, Feb. 1960.
Lloyd, H. B. and Bacon, N. P. "Operating Experience with Oxygen-Assisted
Open-Hearth Furnaces. " In: Fume Arrestment, Special Report 83, William
Lea and Co. , London, 1964, pp. 65-70.
Loszek, W. "The Problem of Maintaining Clean Air in a Zone Polluted by
Waste Gases from Metallurgical Works. " In: Part I, Proceedings of the
International Clean Air Congress, London, 1966, Paper IV/10, pp. 105-111.
Mitchell, R. T. "Dry Electrostatic Precipitators and Waagner-Biro Wet
Washing Systems. " In: Fume Arrestment, Special Report 83, William Lea
and Co., London, 1964, pp. 80-85.
Namy, G. , Dumont-Fillon, J. , and Young, P. A. "Gas Recovery Without
Combustion from Oxygen Converters: The IRSID-CAFL Pressure Regulation
Process. " In: Fume Arrestment, Special Report 83, William Lea and Co. ,
London, 1964, pp. 98-103.
Ochs, H. J. "Purification of Air in Rolling Mills. " [Umluftreinigung in Walz-
Betrieben. ] Metall. (Germany), 1_9(4):348-351, April 1965.
Pallinger, J. "A New Wet Method for Separation of Very Fine Dust. " Staub
(Diisseldorf), _22(7): 270-275, 1962.
Parker, C. M. "BOP Air Cleaning Experiences. " J. Air Pollution Control
Assoc., _16 (8): 446-448, Aug. 1966.
Pottinger, J. F. "The Collection of Difficult Materials by Electrostatic
Precipitation." Australian Chem. Process Eng. (Sidney), 20(2):17-23,
Feb. 1967.
Punch, G. "LD and Kaldo Fume Cleaning - CONSETT Developments. " Iron
and Steel (London), 3£(2):75-80, 86, Feb. 1965.
Rabel, G. , Neuhaus, H. , and Vettebrodt, K. "The Wetting of Dusts and Fine
Ores for the Purpose of Reducing Dust Formation. » Staub (English transla-
tion), _25(6):4-8, June 1965.
8-30
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Restricting Emission of Dust, Tar Mist and Gas when Charging Coke Oven"
[Auswurfbegrenzung fur Staub, Teernebel und Case beim Fullen von Koksofen;
Kokereien und Gaswerke. ] VDI (Verein Deutscher Ingenieure) , Kommission
Reinhaltung der Luft, Dusseldorf, VDI 2302, June 1962, 26 pp.
Sem, M. O. and Collins, F. C. "Fume Problems in Electric Smelting and
Contributions to their Solution. " J. Air Pollution Control Assoc. , 5(3):157-158,
187, Nov. 1955.
Schneider, R. L. "Engineering, Operation and Maintenance of Electrostatic
Precipitators in Open Hearth Furnaces. " J. Air Pollution Control Assoc. ,
: 348-353, Aug. 1963.
Schueneman, J. J. , High, M. D. and Bye, W. E. "Air Pollution Aspects of
the Iron and Steel Industry. " U. S. Dept. Health, Education and Welfare, Div.
of Air Pollution, Cincinnati, Ohio, PHS-Pub-999-AP-l, June 1963, 129pp.
Smith, J. H. "Air Pollution Control in Oxygen Steelmaking. " J. of Metals,
13(9): 632-634, Sept. 1961.
Smith, W. M. and Coy, D. W. "Fume Collection in a Steel Plant. " Chem.
Eng. Progr. , 62(7):119-123, July 1966.
Spenceley, G. D. and Williams, D. I. T. "Fumeless Refining with Oxy- Fuel
Burners." Steel Times (London), 1_93(5115) :150-158, July 29, 1966.
Storch, O. "Experiences with the Application of Wet Collectors in the Iron and
Steel Industry. " [Erfahrungen mit der Anwendung von Nassabscheidern in Eisen
and Stahlhutten-Werken. ] In: Part I, Proceedings of the International Clean
Air Congress, London, 1966, Paper V/2, pp. 119-122.
Storch, O. "A New Venturi Scrubber to Separate Dust Particles less than
1 Micron, Especially of Brown Smoke." Staub (English translation) , _26(11) :32-34,
Nov. 1966.
Sullivan, J. L. and Murphy, R. P. "The Control of Fume from a Hot Blast
Cupola by High Energy Scrubbing without Appreciable Thermal Buoyancy Loss. "
In: Parti, Proceedings of the International Clean Air Congress, London, 1966,
Paper V/10, pp. 144-146.
Thorn, G. W. and Schuldt, A. F. "The Collection of Open Hearth Dust and its
Reclamation Using the SL/RN Process. " Can. Mining and Met. Bull. , 59
(654):1229-1233, Oct. 1966.
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Tulcinsky, S. and Lemaire, A. "Cooling and Scrubbing of Smoke Emitted by
LD Steel Converters in Sidmar Ironworks." Rev. de Metallurgie (France),
63(9):659-665, Sept. 1966.
Underwood, G. "Removal of Sub-Micron Particles from Industrial Gases,
Particularly in the Steel and Electricity Industries. " International J. of Air &
Water Pollution, Vol. 6, pp. 229-263, 1962.
Wheeler, D. H. "Fume Control in L-D Plant. " Preprint. (Presented at the
60th Annual Meeting, Air Pollution Control Association, Cleveland, Ohio,
June 11-16, 1967, Paper 67-96.)
Wheeler, D. H. and Pearse, D. J. "Fume Control Instrumentation in Steel-
making Processes. " Blast Furnace Steel Plant, .53(12) :1125-1130, Dec. 1965.
Willett, H. P. "Cutting Air Pollution Control Costs." Chem. Eng. Progr. ,
£3(3):80-83, March 1967.
Yokomiyo, K. "Air Pollution Prevention Equipment Installed in Muroran Steel
and Iron Works, Ltd. " Clean Air Heat Management (Tokyo), 1.5(7-8): 19-28,
Aug. 1966.
LEAD
Danielson, J. A. (ed.) "Air Pollution Engineering Manual. " U. S. Dept. of
Health, Education, and Welfare, National Center for Air Pollution Control,
Cincinnati, Ohio, PHS-Pub-999-AP-40, 1967, 892 pp.
Snowball, A. F. "Development of an Air Pollution Control Program at
Cominco's Kimberley Operation. " J. Air Pollution Control Assoc. , 16(2):59-62,
Feb. 1966.
"Restricting Dust and Sulfur-Dioxide Emission from Lead Smelters. "
[Auswurfbegrenzung Bleihutten. ] VDI (Verein Deutscher Ingenieure),
Kommission Reinhaltung der Luft, Duesseldorf, (English translation), VDI
2285, Sept. 1961.
ZINC
Allen, G. L. , Viets, F. H. , and McCabe, L. C. "Control of Metallurgical and
Mineral Dusts and Fumes in Los Angeles County, Calif. " Bureau of Mines,
Washington, D. C. , Information Circular 7527, April 1952, 79 pp.
8-32
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Damelson, j. A. (ed.) "Air Pollution Engineering Manual. " U. S. Dept. of
Health, Education, and Welfare, National Center for Air Pollution Control,
Cincinnati, Ohio, PHS-Pub-999-AP-40, 1967, 892 pp.
"Restricting Emission of Dust and Sulfur-Dioxide in Zinc Smelters. "
[Auswurfbegrenzung Zinkhutten. ] VDI (Verein Deutscher Ingenieure), Kommis-
sion Reinhaltung der Luft, Duesseldorf, VDI 2284, Sept. 1961, 27 pp.
CHEMICAL PROCESS SOURCES
MINERAL ACIDS
Nitric Acid
"Atmospheric Emission from Nitric Acid Manufacturing Processes. " U. S.
Dept. of Health, Education, and Welfare, Div. of Air Pollution, Cincinnati,
Ohio, PHS-Pub-999-AP-27, 1966, 89 pp.
"Nitric Acid Manufacture - Informative Report No. 5. " J. Air Pollution Con-
trol Assoc. , ^4(3):91-93, March 1964.
Toyama, T. "Air Pollution and Health Impediment. " Japan J. Ind. Health
(Tokyo), _8(3):45-48, March 1966.
Zanon, D. and Sordelli, D. "Practical Solutions of Air Pollution Problems
from Chemical Processes. " [Realizzazioni nel campo della prevenzione
dell'inquinamento atmosferico di origine industriale. ] Chim. Ind. (Milan),
(English translation), 48(2):251-261, March 1966.
Phosphoric Acid
Brink, J. A. , Jr. , Burggrabe, W. F. , and Greenwell, L. E.. "Mist Removal
from Compressed Gases. " Chem. Eng. Prog. , 6^(4)-.60-65, April 1966.
Danielson, J. A. (ed.) "Air Pollution Engineering Manual." U. S. Dept. of
Health, Education and Welfare, National Center for Air Pollution Control,
Cincinnati, Ohio, PHS-Pub-999-AP-40, 1967, 892 pp.
Sulfuric Acid
Arkhipov, A. S. and Boystsov, A. N. "Toxic Air Pollution from Sulfuric Acid
Production." Gigiena Sanit. (English translation), Vol. 31, pp. 12-17
Sept. 1962.
8-33
-------
"Atmospheric Emissions from Sulfuric Acid Manufacturing Processes. " U. S.
Dept. of Health, Education, and Welfare, Div. of Air Pollution, Cincinnati, Ohio
PHS-Pub-999-AP-13, 1965, 127 pp.
"Blocks Air Pollution. Snares 1700 Ib. of H2SO4 per Day. " Chemical Proc.,
Feb. 1962.
Brink, J. A. , Jr. , Burggrabe, W. F. , and Rauscher, J. A. "Fiber Mist
Eliminators for Higher Velocities. " Chem. Eng. Prog. , j30(ll):68-73,
Nov. 1964.
Brink, J. A., Jr. "Air Pollution Control with Fibre Mist Eliminators. "
Canadian J. of Chem. Eng., Vol. 41, pp. 134-138, June 1963.
Brink, J. A. , Jr. , Burggrabe, W. F. , and Greenwell, L. E. "Mist Removal
from Compressed Gases." Chem. Eng. Prog. , 6£(4):60-65, April 1966.
Danielson, J. A. (ed.) "Air Pollution Engineering Manual." U. S. Dept. of
Health, Education, and Welfare, National Center for Air Pollution Control,
Cincinnati, Ohio, PHS-Pub-999-AP-40, 1967, 892 pp.
Meinhold, T. F. "Three-Way Payout for H SO Gas Cleaner. " Chem. Proc.,
_29(3):63-64, March 1966.
Stastny, E. P. "Electrostatic Precipitation. " Chem. Prog. , £2(4) :47-50,
April 1966.
Stopperka, K. "Electroprecipitation of Sulfuric Acid Mists from the Waste
Gas of a Sulfuric Acid Production Plant. " Staub (English translation), 25(11):
70-74, Nov. 1965.
"Teflon Monofilament Cleans Up Acid Stack Gases. " Chem. Eng. , 72(22): 112-
114, Oct. 25, 1965.
Toyama, T. "Air Pollution and Health Impediment. " Japan J. Ind. Health
(Tokyo), _8(3):45-48, March 1966.
Willett, H. P. "Cutting Air Pollution Control Costs. " Chem. Eng. Prog.,
_63(3):80-83, March 1967.
Zanon, D. and Sordelli, D. "Practical Solutions of Air Pollution Problems
from Chemical Processes. " [Realizzazioni nel campo della prevenzione dell'
inquinamento atmosferico di origine industriale. ] Chim. Ind. (Milan)
(English translation), 48(2):251-261, March 1966.
8-34
-------
PULP AND PAPER
Blosser, R. Q. and Cooper H. B. H. "Particulate Matter Reduction Trends in
the Kraft Industry. " National Council for Stream Improvement, Atmospheric
Pollution Technical Bulletin 32, New York, April 4, 1967, 26 pp.
Boyer, R. Q. "The Western Precipitation Recovery System. " Tappi,
43(8):688-698, Aug. 1960.
Collins, T. T. , Jr. "The Venturi Scrubber on Lime Kiln Stack Gases. "
Tappi, 42(1):9-13, Jan. 1959.
Cooper, S. R. and Haskell, C. F. "Cutting Chemical Ash Losses in a Kraft
Recovery System. " Paper Trade J. , _L51_(13):5S, March 27, 1967.
Gehm, H. W. Statement Presented at the Hearings before Subcommittee on
Air and Water Pollution of the Committee on Public Works, U. S. Senate,
90th Congress, 1st session on S. 780, May 15-18, 1967, Part IV, pp. 2361-
2382.
Harding, C. I. and Landry, J. E. "Future Trends in Air Pollution Control in
the Kraft Pulping Industry." Tappi, 49(8):61A-67A, Aug. 1966.
Landry, J. E. and Longwell, D. H. "Advances in Air Pollution Control in the
Pulp and Paper Industry. " Tappi, 48_(6):66A-70A, June 1965.
Owens, V. P. "Considerations for Future Recovery Units in Mexican and Latin
American Alkaline Pulping Mills." Combustion, 38_(5):38-44, Nov. 1966.
Saha, I. S. "New Flue-Gas Scrubbing System Reduces Air Pollution. " Chem.
Eng. , _24(7):84-86, March 27, 1967.
Stuart, H. H. and Bailey, R. E. "Performance Study of Lime Kiln and
Scrubber Installation. " Tappi, 48(5): 104A-108A, May 1965.
Walker, A. B. "Enhanced Scrubbing of Black Liquor Boiler Fume by
Electrostatic Pre-agglomeration: A Pilot Plant Study. " J. Air Pollution
Control Assoc. , l^(12):622-627, 1963.
8-35
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OIL REFINERIES
"Atmospheric Emissions from Petroleum Refineries - A Guide for Measurement
and Control. " U. S. Public Health Service, Div. of Air Pollution, Cincinnati,
Ohio, 1960, 64 pp.
Danielson, J. A. (ed.) "Air Pollution Engineering Manual. " U. S. Dept. of
Health, Education, and Welfare, National Center for Air Pollution Control,
Cincinnati, Ohio, PHS-Pub-999-AP-40, 1967, 892 pp.
Gammelgard, P. N. "Current Status and Future Prospects - Refinery Air
Pollution Control. " Proc. of the National Conference on Air Pollution,
Washington, D. C. , Dec. 13, 1966, pp. 260-263.
Harrison, A. F. , Louden, W. L. , and Jones, G. "The Disposal of Chemical
Effluents from Refineries Utilizing Acid Treatment Processes. " [Die
Aufbereitung von Raffinerieabwassern aus der Saure-Raffination. ] Erdol Kohle
(Hamburg), _19(8): 587-591, Aug. 1966.
Hess, K. and Stickel, R. "Soot-Free Combustion of Petrochemical Waste
Gases." [Zur russfreien Verbrennung petrochemischer Abgase, ] Chem. Ing.
Tech. (Weinheim), _39(5-6):334-340, March 20, 1967.
Kropp, E. P. and Simonsen, R. N. "Scrubbing Devices for Air Pollution
Control." Paint Oil Chem. Rev., _115(14):11, 12, 16, July 3, 1952.
London, D. E. "Requirements for Safe Discharge of Hydrocarbons to Atmo-
sphere. " In: Proceedings of Midyear Meeting, American Petroleum Institute,
Div. of Refining, Philadelphia, Pa., May 15, 1963, Section III. 43, 1963, pp.
418, 433.
Miller, P. D. , Jr. , Hibshman, H. J. , and Connel, J. R. "The Design of
Smokeless Nonluminous Flares. " In: Proceedings of the 23rd Midyear Meeting,
American Petroleum Institute, Div. of Refining,Los Angeles, Calif. ,
May 14, 1958, Section III, pp. 276-281.
"The Petroleum Refining Industry - Air Pollution Problems and Control
Methods, Informative Report No. 1. " J. Air Pollution Control Assoc. ,
14(l):30-33, Jan. 1964.
Rose, A. H. , Jr. , Black, H. H. , and Wanta, R. C. "Air and Water Pollution
Studies Related to Proposed Petroleum Refinery for Sand Island - Oahu,
Territory of Hawaii (Report to Board of Health, Territory of Hawaii). " Public
Health Service, Div. of Air Pollution, Cincinnati, Ohio, Dec. 1965, 60pp.
B-36
-------
Termeulen, M. A. "Air Pollution Control by Oil Refineries. " In: Parti,
Proceedings of international Clean Air Congress, London, 1966, Paper IV/5,
pp. 92-95.
Wilson, J. G. and Miller, D. W. "The Removal of Particulate Matter from
Fluid Bed Catalytic Cracking Unit Stack Gases. " J. Air Pollution Control
Assoc., r7(10):6S2-6S5, Oct. 1967.
PAINT AND A^ARNISH
Boulde, M. J. , Severs, R. K. , and Brewer, G. L. "Test Procedures for
Evaluation of Industrial Fume Converters (Sampling and Analytical Techniques
Reviewed for)." Air Eng. , 8_(2)-.20-23, Feb. 1966.
Danielson, J. A. "Air Pollution Engineering Manual. " U. S. Dept. of Health,
Education, and Welfare, National Center for Air Pollution Control, Cincinnati,
Ohio, PHS-Pub-999-AP-40, 1967, 892pp.
Morash, N. , Krouse, M. , and Vosseller, W. P. "Removing Solid and Mist
Particles from Exhaust Gases. " Chem. Eng. Progr. , 63(3):70-74,
March 1967.
Stenburg, R. L. "Control of Atmospheric Emissions from Paint and Varnish
Manufacturing Operations. " Public Health Service, Div. of Air Pollution,
Cincinnati, Ohio, Technical Report A58-4, June 1958, 30 pp.
PLASTICS AND RESINS
Danielson, J. A. "Air Pollution Engineering Manual. " U. S. Dept. of Health,
Education, and Welfare, PHS-Pub-999-AP-40, 1967, 892pp.
First, M. W. "Control of Haze and Odours from Curing of Plastics. " In:
Parti, Proceedings of International Clean Air Congress, London, 1966,
Paper VI/11, pp. 188-191.
Kenagy, J. A. "Designing a 'Clean Room'for Plastic Processing." Mod.
Plastics, 44(3):98-99, Nov. 1966.
Parker, C. H. "Plastics and Air Pollution. " Soc. Plastics Engrs. J. ,
23_(12):26-30, Dec. 1967.
331-716 0-69-33
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OTHER CHEMICALS
Ammonia
Kaylor, F. B. "Air Pollution Abatement Program of a Chemical Processing
Industry." J. Air Pollution Control Assoc. , 15(2):65-67, Feb. 1965.
Fertilizer
Grant, H. O. "Pollution Control in a Phosphoric Acid Plant. " Chem. Engr.
Prog. , 60_(l):53-55, 1964.
Sachsel, G. F. , Yocum, J. E. , and Retzke, R. A. "Fume Control in a
Fertilizer Plant - A Case History. " J. Air Pollution Control Assoc. ,
_6(4):214-218, Feb. 1957.
Sauchelli, V. "Chemistry and Technology of Fertilizers. " ACS Monograph
148, Reinhold, 1960.
Miscellaneous Chemicals
"Air Pollution Control in Connection with DDT Production - Informative
Report No. 6. " J. Air Pollution Control Assoc. , 14(3):94-95, March 1964.
Boldue, M. J. , Severes, R. K. , and Brewer, G. L. "Test Procedures for
Evaluation of Industrial Fume Converters (Sampling and Analytical Techniques
Reviewed For). " Air Eng. , _8(2):20-23, Feb. 1966.
Kaylor, F. B. "Air Pollution Abatement Program of a Chemical Processing
Industry. " J. Air Pollution Control Assoc. , _15(2):65-67, Feb. 1965.
Massiello, F. "Air Pollution Control at Drew Chemical Corporation."
In: Proceedings of Technical Conference, Mid-Atlantic States Section, Air
Pollution Control Association, Newark, N. J. , 1962, pp. 8-12.
Sandomirsky, A. G. , Benforado, D. M. , Grames, L. D. , and Pauletta, C. E
"Fume Control in Rubber Processing by Direct-Flame Incineration. " J. Air
Pollution Control Assoc., l_6(12):673-676, Dec. 1966.
Storch, H. C. "Product Losses Cut with a Centrifugal Gas Scrubber. " Chem.
Engr. Prog. , 62_(4):51-54, 1966.
-------
MINERAL PROCESS SOURCES
BITUMINOUS CONCRETE MANUFACTURING
Danielson, J. A. (ed.) "Air Pollution Engineering Manual. " U. S. Dept. of
Health, Education, and Welfare, National Center for Air Pollution Control,
Cincinnati, Ohio, PHS-Pub-999-AP-iO, 1967, 892 pp.
Gallaer, C. A. "Fine Aggregate Recovery and Dust Collection. " Roads and
Streets, pp. 112-117, Oct. 1956.
Hankin, M. , Jr. "Is Dust the Stone Industry's Next Major Problem?" Rock
Prod., 70(4):80-84, 110, April 1967.
Hayes, S. C. , McGrane, N. M. , and Perils, D. B. "Visual Clarity in Kiln
Discharge Gases. " J. Air Pollution Control Assoc. , _5(3):171-172, 186,
Nov. 1955. (Presented at the Annual Meeting of the Air Pollution Control
Association, Detroit, Mich., May 22-26, 1955, Paper 55-33.)
"Low Dust Despite Heavy Fines, High Production. " Roads and Streets,
Aug. 1960.
Lundberg, G. R. "Summary of Dust Collection Systems in Asphalt Plants. "
(Presented at the 10th Annual Convention of the National Bituminous Concrete
Association, Miami Beach, Fla. , Feb. 3, 1965, 14pp.)
McKin, W. A. "Dust Control Check on an Urban Asphalt Plant. " Roads and
Streets, pp. 173-175, Aug. 1959.
Mitchell, R. D. "Primary Dust Collectors. " (Presented at the 10th Annual
Convention of the National Bituminous Concrete Association, Miami Beach,
Fla. , Feb. 1965, 8 pp.)
Mundy, L. W. "Multiple Tube Dust Collectors as Applied to Asphalt Plant
Operation. " (Presented at the 10th Annual Convention of the National
Bituminous Concrete Association, Miami Beach, Fla., Feb. 1965, 4pp.)
Von Lehmden, D. J. , Hangebrauck, R. P., and Meeker, J. E. "Polynuclear
Hydrocarbon Emissions from Selected Industrial Processes. " J. Air Pollution
Control Assoc. , 15(7):306-312, July 1965.
8-39
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Walter, E. "The Dust Situation at Mixing Plants Used in Bituminous Road
Construction in Western Germany. " Staub (English translation), 26(11):34-40,
Nov. 1966.
Weatherly, D. "Controlling Dust from Road Building Material Plants. " In:
Proceedings of the Technical Conference, Mid-Atlantic States Section, Air
Pollution Control Association, Newark, N. J. , 1962, pp. 13-18.
Wiemer. "Dust Removal from the Waste Gases of Preparation Plants for
Bituminous Road-Building Materials. " Staub (English translation), 27_(7):9-22,
July 1967.
CALCIUM CARBIDE
Sem, M. O. and Collins, F. C. "Fume Problems in Electric Smelting and
Contributions to Their Solution. " J. Air Pollution Control Assoc. ,
5(3)-.157-158, 187, Nov. 1955.
CEMENT
Aleksynowa, K. "Chemical Characteristics of Waste Cement Dust on Their
Value for Agriculture. " [Charakterystyka chemicza cemetowych pytow
odotowuch i ich wastose dla solnict. ] Cement, Wopno, Gips, 11/20(3):62-64,
1955.
Kreichelt, T. E. , Kemnitz, D. A., and Cuffe, S. T. "Atmospheric Emission
from the Manufacture of Portland Cement. " U. S. Dept. of Health, Education,
and Welfare, National Center for Air Pollution Control, Cincinnati, Ohio,
PHS-Pub-999-AP-17, 1967, 47 pp.
Chamberlin, R. L. and Moodie, G. "What Price Industrial Gas Cleaning?"
In: Part I, Proceedings of the International Clean Air Congress, London,
1966, Paper No. V/7, pp. 133-135.
"Control at Santee Cement." Southern Eng. , pp. 50-51,March 1967.
Danielson, J. A. "Air Pollution Engineering Manual. " U. S. Dept. of Health,
Education, and Welfare, National Center for Air Pollution Control, Cincinnati,
Ohio, PHS-Pub-999-AP-40, 1967, 892pp.
Doherty, R. E. "Current Status and Future Prospects - Cement Mill Air
Pollution Control. " In: Proceedings of 3rd National Conference on Air
Pollution, Washington, D. C. , 1966, pp. 242-249.
5-40
-------
revention - Cement Industry. " [Staubauswurfbegrenzung Zement-
e-J VDI (Verein Deutscher Ingenieure) Kommission Reinhaltung der
Luft, Duesseldorf, VDI 2094, June 1961, 51 pp.
Kohler, W. "Method for the Abatement of Air Pollution Caused by Cement
Plants. [Verfahren zur Verminderung der durch die Zementindustrie
verursachten Luftverunreinigungen. ] In: Part I, Proceedings of the Inter-
national Clean Air Congress, London, 1966, Paper IV/12, pp. 114-116.
Rayher, W. and Middleton, J. T. "The Case for Clean Air. " (Federal
Government Plans for Nationwide Control.) Mill Factory, 80(4):41-56,
April 1967.
Tomaider, M. "Dust Collection in the Cement Industry. " In: Part I, Pro-
ceedings of the Clean Air Congress, London, 1966, Paper V/4, pp. 125-128.
CONCRETE BATCH PLANTS
Danielson, J. A. (ed.) "Air Pollution Engineering Manual. " U. S. Dept. of
Health, Education, and Welfare, National Center for Air Pollution Control,
Cincinnati, Ohio, PHS-Pub-999-AP-40, 1967, 892pp.
Hankin, M. , Jr. "Is Dust the Stone Industry's Next Major Problem?" Rock
Prod., 7_0(4):80-84, 110, April 1967.
CERAMIC, CLAY, AND REFRACTORIES
Aizenshtadt, B. M. "Extensive Introduction of Advanced Experience with Dust
Extraction in the Refractories Industry. " Refractories, No. 10, pp. 425-426,
Oct. 1965.
Luxon, S. G. "Atmospheric Fluoride Contamination in the Pottery Industry. "
Ann. Occupational Hyg. (London), _6(3): 127-130, July 1963.
Mori, H. "Hanshin Wet Type Dust Collectors." Clean Air and Heat Manage-
ment (Tokyo), _15(5):5-11, May 1966.
Rutman, Z. M. "Purification of Waste Gases from Heat Units in Refractory
Factories." Refractories, No. 10, pp. 429-432, Oct. 1966.
GLASS AND FRIT
Danielson, J. A. "Air Pollution Engineering Manual. " U. S. Dept. of Health,
Education,' and Welfare, National Center for Air Pollution Control, Cincinnati,
Ohio, PHS-Pub-999-AP-40, 1967, 892 pp.
-------
Elliott, J. H., Kayne, N. , and LeDuc, M. F "Experimental Program for the
Control of Organic Emissions from Protective Coating Operations. " Los
Angeles County Air Pollution Control District, Calif., Interim Report 7, Jan.
1961, 23 pp.
GYPSUM
Hankin, M., Jr. "Is Dust the Stone Industry's Next Major Problem?" Rock
Prod., ^70(4):80-84, 110, April 1967.
LIME
Kaylor, F. B. "Air Pollution Abatement Program of a Chemical Processing
Industry." J. Air Pollution Control Assoc. , 15_(2):65-67, Feb. 1965.
Pottinger, J. F. "The Collection of Difficult Materials by Electrostatic
Precipitation." Australian Chem. Process Eng. (Sidney), _20(2): 17-23,
Feb. 1967.
PITS AND QUARRIES
Danielson, J. A. "Air Pollution Engineering Manual. " U. S. Dept of Health,
Education, and Welfare, National Center for Air Pollution Control, Cincinnati,
Ohio, PHS-Pub-999-AP-40, 1967, 892 pp.
Davydov, S. A. , Aksel'rod, M. B. , Mar'Yash, L. R. , and Klimenko, E. I.
"Contamination of the Atmospheric Air with the Waste of Ore-Concentrating
Works. " [Zagryaznenie atmosfernogo vozdukha vybrosami gornoobogatitel'nykh
kombinatov.] Hyg. and Sanit. , 2_9(2): 115-118, Feb. 1965.
Hankin, M. , Jr. "Is Dust the Stone Industry's Next Major Problem?" Rock
Prod. , 7_0(4):80-84, 110, April 1967.
Renninger, F. A. "A Monitoring System for the Detection and Control of
Airborne Dust." Dust Topics Mag., _3(4):6-8, Oct. 1966.
Schrauf, R. E. "Dust Suppression at St. Mary's Quarry. " Mining Minerals
Eng. (London), _3(l):32-33, Jan. 1967.
Walter, E. "Dust Control in Quarrying and Rock Processing by Means of
Suction Devices. " Staub (English translation), 25(6):l-4, June 1965.
8-42
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OTHER
Gabmova, Zh. L. , Vasil'eva, A. A. , Sklyarskaya, N. Kh. , and Manita, M. D.
Gigiena i Sanit. (English translation), _28(6):65-69, June 19G3.
Mori, H. "Hanshin Wet Type Dust Collectors. " Clean Air and Heat Management
(Tokyo), ^5(5):5-11, May 1966.
AGRICULTURAL OPERATIONS
"Wastes in Relation to Agriculture and Forestry. " U. S. Dept. of Agriculture,
Miscellaneous Rib. 1065, March 196S, 112 pp.
Pathark, V. K. and Pady, S. M. "Numbers and Viability of Certain Airborne
Fungus Spores. " Mycologia, Vol. 57, pp. 301-310, March-April 1965.
Hewson, E. W. "Air Pollution by Ragweed Pollen, 1. Ragweed Pollen as Air
Pollution." J. Air Pollution Control Assoc. , JLTJIO): 651-652, Oct. 1967.
Went, F. W. "Formation of Aerosol Particulates Derived from Natural
Occurring Hydrocarbons Produced by Plants. " J. Air Pollution Control Assoc. ,
p. 579, 1967.
Went, F. W. "Blue Hazes." Nature, 187_(4738):641-G43, 1960.
"Soil Erosion by Wind, and Measures for its Control on Agricultural Lands. "
Food and Agriculture Organization, 1960.
"Shelterbelt Influence on Great Plains Fields, Environment, and Crops." U. S.
Forest Service, Production Research Report 62, Oct. 1962.
"How to Control Soil Blowing. " U. S. Dept. of Agriculture, Farmers Bulletin
2169, 1961.
"Soil Conditions Influence Wind Erosion. " U. S. Dept. of Agriculture, Technical
Bulletin 1185, June 1958.
"Suggested Guide for Use of Insecticides to Control Insects Affecting Crops,
Livestock, Households, Stored Products, Forests, and Forest Products."
Agriculture Handbook 331, 1968.
8-43
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COFFEE ROASTING
Danielson, J. A. "Air Pollution Engineering Manual. " U. S. Dept. of Health,
Education, and Welfare, National Center for Air Pollution Control, Cincinnati,
Ohio, PHS-Pub-999-AP-40, 1967, 892 pp.
Partee, F. "Air Pollution in the Coffee Roasting Industry. " U. S. Dept. of
Health, Education, and Welfare, Div. of Air Pollution, Cincinnati, Ohio,
PHS-Pub-999-AP-9, 1964, 15 pp.
Sullivan, J. L. , Kafka, F. L., and Ferrari, L. M. "An Evaluation of Catalytic
and Direct Fired Afterburners for Coffee and Chicory Roasting Odors. " J. Air
Pollution Control Assoc. , _15(12):5S3-586, Dec. 1965.
COTTON GINNING
"Airborne Particulate Emissions from Cotton Ginning Operations." U. S. Dept.
of Health, Education, and Welfare, Div. of Air Pollution, Cincinnati, Ohio,
Technical Report A60-5, 1960, 20pp.
"Control and Disposal of Cotton Ginning Wastes. " U. S. Dept. of Health,
Education, and Welfare, National Center for Air Pollution Control, Cincinnati,
Ohio, PHS-Pub-999-AP-40, 1967, 103 pp.
Paganini, O. "Control of Cotton Gin Waste in Texas. " Preprint. (Presented
at the 57th Annual Meeting of the Air Pollution Control Association, Houston,
Tex. , June 24, 1964, Paper 64-94.)
"What We Know About Air Pollution Control. " Texas Cotton Ginners1 Association
(Dallas), Special Bulletin 1, March 1965, 43 pp.
FEED AND GRAIN
Barfield, S. "Harbor Bulk-Loading Grain Terminals. " J. Environ. Health,
_2S(2);151-155, Sept.-Oct. 1965.
Danielson, J. A. (ed.) "Air Pollution Engineering Manual. " U. S. Dept. of
Health, Education, and Welfare, National Center for Air Pollution Control,
Cincinnati, Ohio, PHS-Pub-999-AP-40, 1967, 892 pp.
"Proceedings of the National Symposium on Air Pollution. " Grain and Feed
Dealers National Association, Jan. 11-12, 1967, 103pp.
3-44
-------
McLouth, M. E. and Paulus, H. J. "Air Pollution from the Grain Industry. "
J. Air Pollution Control Assoc. , 11(7):313-317, July 1961.
FISH MEAL PROCESSING
Danielson, J. A. (ed.) "Air Pollution Engineering Manual. " U. S. Dept. of
Health, Education, and Welfare, National Center for Air Pollution Control,
Cincinnati, Ohio, PHS-Pub-999-AP-40, 1967, 892pp.
Mandell, L. C. "Air Pollution Control for the Fish Dehydration Industry."
(Presented at the 54th Annual Meeting of the Air Pollution Control Association,
New York, June 11-15, 1961.)
OTHER
Danielson, J. A. "Air Pollution Engineering Manual. " U. S. Dept. of Health,
Education, and Welfare, National Center for Air Pollution Control, Cincinnati,
Ohio, PHS-Pub-999-AP-40, 1967, 892pp.
Storch, H. L. "Product Losses Cut with a Centrifugal Gas Scrubber." Chem.
Eng. Prog., _62(4):51-54, April 1966.
8-45
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AUTHOR INDEX
Ackley, c. 4_113
Adams, R. L. 4-149, 4-150, 4-151, 4-153, 4-171,
4-177, 8-27
Adrian, R. C. 4-190, 4-196, 4-217
Aizenshtadt, B. M 8-41
Aksel'rod, M. B. 8-42
Albinus, G. 8-21
Aleksynowa, K. 8-40
Allen, G. L. 8-32
Alliot, L. 8-15
Alpiser, F. M. 3-71
Archbold, M. J. 4-101
Archer, A. 8-27
Arkhipov, A. S. 8-33
Arnold, O. M. 4-61
Aslander, A. 8-6
Auclair, M. 8-15
Axtman, W. H. 8-15
Bacon, N. P. 4-111, 8-30
Bailey, J. M. 4-217
Bailey, R. E. 8-35
Ballard, W. E. 7-3
Banner, A. P. 4-217
Barber, J. C. 8~w
Barenstein, M. 8~26
Barfield, S. 8~44
Barker, K. 8'8' 8~15' 8~17
A-l
-------
Barr, J. 4-204
Basse, B. 8-27
Baxter, W. A. 4-109
Beckman, E. W. 8-3
Beiser, F. R. 8-29
Belyea, H. A. 8-15
Bender, R. J. 8-19
Benforado, D. M. 4-196, 4-200, 4-217, 8-38
Bennett, K. W. 3-72
Beorse, B. 8-19
Berly, E. 4-66
Betz, L. D. 4-86
Betz, W. H. 4-86
Bigelow, C. G. 4-61
Billings, C. 4-31
Bins, R. V. 8-8
Black, H. H. 8-36
Black, R. J. 3-61, 3-63, 3-64, 3-65, 3-66, 3-74,
3-76, 3-83, 3-84, 3-86
Blasewitz, A. G. 4-69
Blecher, K. J. 8-14
Bloomfield, B. D. 8-27
Blosser, R. O. 4-74, 8-35
Boabel, R. W. 8-19, 8-23
Bogue, M. D. 3-85
Boldue, M. J. 8-37, 8-38
Borgwardt, R. H. 4-135, 7-2, 8-8
Bovier, R. F. 8-8
Bowerman, F. R. 8-24
A-2
-------
Boyer, R. H > Jr_ 3_85) g_19
Boyer, R. Q- 8_35
Boystsov, A. N 8-33
Brandt, A. D. 3-34, 3-35, 3-48, 4-111, 8-27
Braubacher, M. L. 8-6
Bremser, L. W. 3-65
Brewer, G. L. 8-37, 8-38
Brief, R. S. 8-16
Brink, J. A. , Jr. 4-69, 8-33, 8-34
Brogan, T. R. 3-27
Broman, C. 8-27
Brooke, M. 4-86
Brooks, A. F. 4-59
Brooks, R. M. 4-86
Brown, R. S. 8-24
Browning, J. A. 4-190, 4-196
Bugher, R. D. 8-24
Bull, W. C. 8-11
Bump, R. L. 8-19
Burckle, J. O. 3-76, 7-2
Burggrabe, W. F. 4-69, 8-33, 8-34
Burke, S. A. 8-9
Burson, J. H. 7-3
Burst, J. F. 4-211, 4-213
Busch, A. W. 4-85
Busey, H. 8-18
Bush, A. F. 8-3, 8-19
Bye w E 3-32, 3-33, 3-34, 3-35, 3-37, 8-31
A-3
-------
Cafiero, A. S. 8-21
Cahill, W. J. , Jr. 8-9
Calaceto, R. R. 8-19, 8-22
Calcote, H. F. 4-190, 4-196
Calonge, A. B. 8-5
Calvert, S. 7-3
Campbell, W. W. 4-140, 4-141, 8-27
Caplan, K. J. 4-170, 4-181, 4-202, 4-203, 4-217
Cederholm, C. 8-19
Challis, J. A. 8-22
Chamberlin, R. L. 8-9, 8-27, 8-40
Chase, F. R. 4-174
Chass, R. L. 3-78, 8-10, 8-17, 8-24
Chilton, C. H. 4-23, 4-76, 4-198, 4-200, 4-213, 4-217
Chipman, R. D. 8-19
Chittawadgi, B. S. 8-6, 8-15
Clarke, S. M. 8-20
Clement, R. L. 4-140, 4-142, 4-143, 4-144, 4-145,
4-183
Collins, F. C. 8-31, 8-40
Collins, K. E. 8-9
Collins, T. T. , Jr. 8-35
Connel, J. R. 8-36
Conners, E. 4-31
Conway, R. A. 4-83
Cooper, G. 4-217
Cooper, H. B. H. 8-35
Cooper, H. B. H. , Jr. 4-74
Cooper, R. L. 8-27
A-4
-------
Cooper, S. R. 8_35
Copp, W. R. 3_61
Corey, R. C. 8-19
Cosby, W. T. 8-28
Cote, W. A. 3-78, 4-179
Coy, D. W. 4-111, 8-31
Cuffe, S. T. 3-32, 4-111, 4-175, 4-176, 8-9, 8-10,
8-40
Culhane, F. R. 4-150, 4-151, 4-153, 4-155, 4-156,
4-157, 4-165, 4-166, 4-167, 4-169,
4-170, 4-174, 4-181
Danielson, J. A. 3-43, 4-16, 4-19, 4-23, 4-114, 4-122,
4-189, 4-195, 4-202, 4-204, 4-207,
4-217, 6-4, 6-26, 8-9, 8-15, 8-17,
8-32, 8-33, 8-34, 8-36, 8-37, 8-39,
8-40, 8-41, 8-42, 8-44, 8-45
Dave, N. R. 8-6
Davies, E. 8-28
Davis, A. L. 3-4
Davydov, S. A. 8-42
Dealy, J. O. 8-23
Debrun, G. 8-9
Decker, L. D. 4-188, 4-217, 6-26
DeHaas, G. G. 4-202, 4-203
Dennis, R. 4-31, 4-49
Derndinger, H. O. 8-3
Dickerson, B. W. 4-86
Doherty, R. E. 3-41, 3-42, 8-40
Dorsey, J. A. 3-76, 7-2
Douglas, I. H. 8-28
Doyle, H. 4~59
A-5
-------
Dragoumis, P. 3-27
Drake, R. M. , Jr. 4-189, 4-193
Drinker, P. 4-31
Drogin, I. 3-33, 3-53, 4-179
Dubinskaya, F. E. 8-28
Duffy, R. 4-188
Dumont-Fillon, J. 8-30
Dunn, C. W. 4-111
Duprey, R. L. 3-4, 3-83, 4-5, 5-3, 5-4, 5-5, 5-6.
5-7, 5-8, 5-9, 5-10
Durham, J. F. 4-135
Dyer, J. 8-3
Ebersole, G. D. 8-3
Eckenfelder, W. W. 6-57
Eckert, E. R. G. 4-189, 4-193
Eckert, J. S. 4-55, 4-78, 4-81
Edwards, V. H. 4-83
Ekberg, G. 8-6
Eldib, I. A. 8-3
Elliott, A. C. 4-111, 8-28
Elliott, J. H. 8-42
Ellison, W. 8-28
Elson, R. J. 8-28
Engelberg, F. 8-28
Engelbrecht, H. L. 8-9
Engels, L. H. 8-14, 8-28
Etoc, P. 8-15
Ettinger, H. J. 8-18
A-6
-------
Fagley, W. S. 8-3
Fauth, U. 8-15
Fawell, H. D. 8-6
Felgar, D. N. 7-3
Fenforado, D. M. 6-26
Fernandas, J. H. 8-9, 8-19, 8-22
Ferrari, L. M. 4-227, 4-253, 8-44
Feuss, J. V. 3-82
Fiala, E. 8-3
Field, M. A. 4-191, 4-192, 4-196
Fife, J. A. 3-85, 8-19, 8-22
Finfer, E. Z. 8-15
First, M. W. 4-31, 4-66, 8-37
Fischer, G. I. 4-31
Flodin, C. R. 8-10
Flood, L. P. 8-19, 8-22
Flory, F. 8-5
Flower, F. B. 3-82
Foote, E. H. 4-78, 4-81
Four, R. 8-14, 8-15
Fournier, M. 8-10
Frame, C. P. 4-111, 8-28
Frederick, E. R. 4-132, 4-159
French, R. C. 4-158, 4-160, 4-171, 4-172
Friedlander, S. K. 4-31
Friedrick, H. E. 4-127, 4-158, 4-171, 4-172, 4-180
Frieling, G. 3-17, 3-18, 8-12
Fullerton, R. W. 4-73, 4-140, 4-141, 8-27, 8-29
A-7
331-716 O - 69 - 34
-------
Gabinova, Zh. L. 8-43
Gallaer, C. A. 8-39
Gamble, B. L. 4-196, 4-217
Gambs, G. C. 6-59
Gamxnelgard, P. N. 8-36
Gardner, J. W. 8-3
Gartrell, F. E. 8-10
Gehm, H. W. 8-35
George, R. E. 8-10, 8-17
Gerstle, R. W. 8-9, 8-10
Gilbert, N. 4-32, 4-33
Gill, D. W. 4-191, 4-192, 4-196
Glasgow, J. A. 4-111
Glater, R. A. 8-3
Glensy, N. 8-10
Glover, I. 8-6
Godsave, G. A. E. 4-190, 4-195, 4-196
Goldberger, W. M. 8-10
Golothan, D. W. 8-6
Golueke, C. G. 3-69, 8-25
Goodel, P. H. 4-200, 4-202
Gosselin, A. E. , Jr. 8-10
Gould, R. H. 8-20
Gourdine, M. C. 3-27
Grames, L. D. 4-196, 4-217, 6-26, 8-38
Grant, E. P 8-4, 8-6
Grant, H. O. 8-38
Greaves, M. J. 8-29
A-J
-------
Greco, J. 3_19> 4_109
Greeley, S. A. 8-20
Greenburg, L. 4-134, 4-135, 4-136
Greenwell, L. E. 8-33
Gregory, C. A., Jr. 4-190, 4-196
Griffiths, J. C. 4-188, 4-191, 4-204, 4-211
Griswold, S. S. 8-10, 8-15, 8-17
Groebler, H. 8-6
Gruber, C. W. 8-14
Gudmundsen, A. 4-190, 4-196
Gusman, I. J. 4-161
Haaland, H. H. 8-10
Haedike, E. W. 8-22
Hagan, J. E. 4-163, 4-164
Hagiwara, I. 8-16
Hales, J. M. 3-33, 4-112
Halitsky, J. 3-66
Hall, M. C. 8-24
Hall, R. M. 4-46, 7-3
Hamming, W. J. 4-31
Hammond, W. F. 4-196, 8-30
Hangebrauck, R. P. 7-2, 8-11, 8-16, 8-17, 8-21, 8-39
Hankin, M. , Jr. 8-39, 8-41, 8-42
Hansen, G. A. 4-202, 4-203
Hanson, V. W. 4-61
Harding, C. I. 3-4, 8-25, 8-35
Harrington, R. E. 4-135, 7-2, 8-8
Harris, E. R. 8~29
A-9
-------
Harris, L. S. 4-49
Harrison, A. F. 8-36
Harrison, B. P., Jr. 4-175
Haskell, C. F. 8-35
Hatch, T. 4-134, 4-135, 4-136
Hatchard, R. E. 8-26
Hattori, I. 8-16
Haug, L. 8-25
Hausberg, G. 8-26
Hawksley, P G. W. 4-191, 4-192, 4-196
Hayes, S. C. 8-39
Hazzard, N. D. 4-196, 4-200
Hedlund, F. 8-6
Hein, G. M. 6-26
Heinen, C. M. 8-4
Hem on, W. C. L. 8-29
Henderson, J. J. 3-4
Henschen, H. C. 8-29
Herrick, R. A. 4-137, 4-177, 4-178, 8-29
Hersey, H. J. , Jr. 4-149
Hess, K. 8-36
Hewson, E. W. 8-43
Hibshman, H. J. 8-36
Hickman, H. L. 3-67, 3-68, 3-85
Hickman, H. L. , Jr. 3-61, 3-63, 3-64, 3-65, 3-66, 3-74,
3-76, 3-83, 3-84, 3-86
High, M. D. 3-32, 3-33, 3-34, 3-35, 3-37, 8-31
Hirao, O. 8-4
Hoff, H. 8-29
A-10
-------
Hofmann, H. 8-5
Holden, F. R. 4-113
Holland, M. 8-29
Holland, W. J. 8-15
Horton, R. C. 4-161
Hottel, H. C. 4-187, 4-190, 4-196
Houghton, H. G. 4-74
Houry, E. 8-22
Howell, G. A. 4-111
Howells, H. E. 8-7
Hoy, D. 8-29
Hughson, R. V. 4-23
Hunigen, E. 8-4
Huntington, R. L. 4-78, 4-81
lehle, F. 8-14, 8-15
Ilgenfritz, E. M. 4-217
Ingels, R. M. 3-43, 4-190, 4-202, 4-211, 4-217
Innes, W. B. 4-188
Intelmann, W. 4-16, 4-22
Jackson, A. 8-29
Jackson, J. 4-76
Jackson, M. W. 8-4
Jackson, N. H. 8-26
Jackson, R. 4-14, 4-86
Jackson, W. E. 8-4
Jacobs, H. L. 4"86
Jacobs, M. B. 3~66
Jacquinot, P. 8~10
A-ll
331-716 O - 69 - 35
-------
Jamison, R. M. 4-61
Jares, J. 4-217
Jaskulla, N. 8-4
Jens, W. 8-20
Jensen, D. A. 8-4, 8-6
Johnson, G. A. 4-31
Johnson, J. E. 8-29
Johnson, K. R. 8-7
Johnson, R. K. 8-27
Jonakin, J. 8-12
Jones, A. H. 4-175
Jones, G. 8-36
Judson, B. F. 4-69
Junker, E. 8-26
Kafka, F. L. 8-44
Kaiser, E. R. 3-66, 3-75, 8-20, 8-22
Kapitulskii, V. B. 8-29
Katz, J. 3-19, 8-11
Kaylor, F. B. 8-38, 8-42
Kayne, N. 8-42
Keller, J. D. 4-189, 4-207
Kemnitz, D. A. 3-32, 4-111, 4-175, 4-176, 8-40
Kenagy, J. A. 8-37
Keng, E. Y. H. 7-3
Kenline, P. A. 3-33, 4-112
King, D. T. 8-11
Kirkpatrick, S. D. 4-23, 4-76, 4-198, 4-200, 4-213, 4-217
A-12
-------
Kirov, N. Y. 8_n> 8_16> 8_20
Kirsh, J. B. 3_68
Kitani, S. 8_18
Klee, A. J. 3-61, 3-63, 3-64, 3-65, 3-66, 3-74,
3-76, 3-83, 3-84, 3-86
Kleeberg, U. 8-26
Klimenko, E. I. 8-42
Kloepper, D. L. 8-11
Knudson, J. C. 3-78
Kobayashi, K. 4-187, 4-190, 4-196
Kogan, L. A. 8-29
Kohler, W. 8-41
Koin, H. W. 8-22
Kopa, R. D. 8-4
Kowalczyk, J. F. 3-78
Kran, W. G. 4-190, 4-196
Kreichelt, T. E. 3-32, 3-77, 4-111, 4-175, 4-176,
8-20, 8-40
Krenz, W. B. 4-190, 4-217
Krikau, F. G. 8-30
Kristal, E. 4-49
Krochtitzky, O. W. 8-25
Kropp, E. P. 8-36
Krouse, M. 4-66, 8-37
Kunii, D. 4-190, 4-196
Kurtz, P. 8-19
Labardin, A. g-16
Lafreniere, A. J. 4-111, 8-28
Lair, J. C. 8~5
A-13
-------
Lambert, W. H. 8-8
Landry, J. E. 8-35
Lapple, C. E. 4-10, 4-11, 4-14, 4-15
Laroche, M. 8-11
Larsen, R. I. 8-4
Larson, G. P. 4-31
Lawson, S. O. 3-7
Leavitt, J. M. 8-11
LeDuc, M. F. 8-42
Lee, G. W. 8-27
Lemaire, A. 8-32
Lemke, E. E. 8-30
Lemon, L. W. 8-10
Lenehan, J. W. 8-20
Lepisto, P. 8-7
Licht, W. 4-130, 4-160, 4-173, 4-181, 4-183
4-184
Lieb, H. 8-22
Lieberman, C. 3-71
Lloyd, H. B. 4-111, 8-30
Lock, A. E. 8-11, 8-16
Lohner, K. 8-4
London, D. E. 8-36
Longwell, D. H. 8-35
Loquercio, P. A. 3-66
Loszek, W. 8-30
Louden, W. L. 8-36
Ludwig, J. H. 8-5, 8-7
Lundberg, G. R. 8-39
Luxon, S. G. 8-41
A-14
-------
Maatsch, J. 8-29
MacFarlaue, W. A. 8-8, 8-15, 8-17
MacKnight, R. J. 3-78, 8-21, 8-23, 8-24
Magill, P. L. 4-113
Magnus, M. N. 8-12
Mandell, L. C. 8-45
Manito, M. D. 8-43
Martin, R. 8-12
Mar'Yash, L. R. 8-42
Masciello, F. 8-38
Massey, O. D. 4-76
Mauss, F. 8-14, 8-16
Mawhinney, M. H. 4-196, 4-207, 4-211, 4-213
Mayer, M. 3-66, 3-73, 3-78
McCabe, L. C. 3-66, 8-32
McConnell, G. 8-7
McGannon, H. E. 3-35
McGaughey, P. H. 3-69, 8-25
McGrane, N. M. 8-39
McKee, H. E. 3-5
McKenzie, D. 4-217
McKim, W. A. 8-39
McLouth, M. E. 8-45
McMahon, W. A. , Jr. 3-5
McReynolds, L. A. 8-3
Meeker, J. E. 8-11, 8-16, 8-39
Meinhold, T. F. 8-34
o o r\
Meissner, H. G. 8~^u
Q 1 Q
Meland, B. R. 8~ib
A-15
-------
Meurer, S. 8-5
Meyer, W. E. 8-7
Meyers, F. D. 4-196, 4-217
Middleton, J. T. 8-41
Miller, D. W. 8-37
Miller, M. R. 4-190
Miller, P. D. , Jr. 8-36
Mills, J. L. 4-196
Mitchell, R. D. 8-39
Mitchell, R. T. 4-111, 8-30
Mizushima, J. 8-19
Monroe, E. S. , Jr. 3-76
Montross, C. F. 4-43
Moodie, G. 8-9, 8-27, 8-40
Moody, R. A. 4-217
Moore, J. F. 3-7
Moore, W. W. 3-14, 3-17, 8-12
Morash, N. 4-66, 8-37
Morgan, B. B. 4-191, 4-192, 4-196
Morgenthaler, A. C. 8-18
Mori, H. 8-41, 8-43
Morris, J. P. 8-5
Mortstedt, S. E. 8-6
Moschella, R. 4-31, 4-66
Moser, E. 8-26
Moss, W. D. 8-18
Mowbray, K. D. 8-22
Muhich, A. T. 3-61, 3-63, 3-64, 3-65, 3-66, 3-74,
3-76, 3-83, 3-84, 3-86
A-16
-------
Mukai, M. g 4
Mukhlenov, I. p. 4_76
Muller, H. g_4
Mundy, L. W. 8_39
Murphy, R. P. 8_31
Namy, G. 8_30
Netzley, A. B. 8-24
Neuhaus, H. 8-30
Nishiwaki, N. 4-187, 4-190, 4-196
Nissen, W. E. 8-4, 8-6
Noland, R. 4-180
Norman, G. R. 3_8
Northcraft, M. 8-23
Ochs, H. J. 8-30
O'Conner, C. 3.75, 8-20
Oiestad, A. 8-16
Olsen, J. W. 4-178, 8-29
O'Mara, R. F. 4-111
Orning, A. A. 4-187, 4-196, 8-9, 8-10
Orr, C. 7-3
Ott, R. R. 8-26
Owens, V. P. 8-35
Ozolins, G. 3-4
Pady, S. M. 8-43
Paganini, O. 8-44
Pallinger, J. 4-49, 8-30
Papovich, M. 8-23
Parker, A. S. 4-190, 4-196
A-17
-------
Parker, C. H. 8-37
Parker, C. M. 8-30
Partee, F. 8-44
Pascual, S. J. 8-20
Pathak, V. K. 8-43
Pauletta, C. E. 4-196, 4-200, 4-217, 6-26, 8-38
Paulus, H. J. 8-45
Pearse, D. J. 8-32
Penney, G. W. 7-3
Perils, D. B. 8-39
Perry, J. H. 4-32
Perry, R. H. 4-23, 4-76, 4-198, 4-200, 4-213,
4-217
Pesterfield, C. H. 8-16
Peterson, D. G. 8-9
Pieratti, A. 8-20
Plumley, A. L. 8-12
Pollock, W. A. 3-17, 3-18, 8-12
Poppele, E. W. 4-73
Pottinger, J. F. 8-12, 8-30, 8-42
Powers, E. D. 4-76
Pozin, M. E. 4-76
Prindle, R. A. 3-61
Pring, R. T. 4-173
Punch, G. 4-111, 8-30
Pursglove, J. , Jr. 8-12
Quack, R. 8-12
A-18
-------
Rabel, G. 8_30
Radford, W. H. 4-74
Radier, H. H. 4-203
Rammler, E. 4-16, 4-22
Ramsdell, R. G. , Jr. 4-101
Rao, T. V. L. 8-7
Rather, J. B. , Jr. 3-7
Rauscher, J. A. 4-69, 8-34
Ray, F. A. 4-178, 8-29
Rayher, W. 8-41
Reed, L. E. 8-7
Reed, R. J. 4-217
Reese, J. T. 3-19, 4-109
Rehm, F. R. 8-20
Reichenbach, G. S. , Jr. 4-31
Reminiczky, K. 8-16
Renninger, F. A. 8-42
Retzke, R. A. 8-38
Rice, O. R. 4-61
Richards, G. 8-3
Rickles, R. N. 4-85
Ridgway, S. L. 8-5
Ridker, R. G. 6-5
Riley, B. T. 3-76, 7-2
Rispler, L. 8-5, 8-7
Robinson, M. 7-3
Rodebush, W. H. 4-13°
Rogers, T. F. 8~1:L
Rogus, C. A. 8-21
A-19
-------
Rose, A. H. 8-5, 8-7
Rose, A. H. , Jr. 4-129, 4-176, 4-178, 8-21, 8-36
Rosin, P. 4-16, 4-22
Ross, C. R. 8-5, 8-7
Rossano, A. T. 4-31
Rothman, S. C. 8-26
Ruff, R. J. 4-202, 4-203
Russell, R. R. 8-24
Rutman, Z. M. 8-41
Sableski, J. J. 3-78
Sableski, J. J., Jr. 8-23, 8-24
Sachsel, G. F. 8-38
Sana, I. S. 8-35
Sandomirsky, A. G. 4-196, 4-217, 6-27, 8-38
Sarto, J. O. 8-3
Sauchelli, V. 8-38
Scheldhammer, A. 4-77
Schenk, R. 8-5
Schneider, R. L. 8-31
Schnitt, H. 8-26
Schrauf, R. E. 8-42
Schueller, H. M. 3-62
Schueneman, J. J. 3-32, 3-33, 3-34, 3-35, 3-37, 8-13
8-17, 8-18, 8-31
Schuldt, A. F. 8-31
Schule, W. 8-15
Schwartz, A. J. 7-2, 8-17
Schwartz, C. H. 8-9, 8-10
Schwarz, K. 8-13
A-20
-------
Schwendinian, L. C.
Scope, S.
Sedeler, C. G.
Seely, R. J.
Sem, M. O.
Semrau, K. T.
Senecal, J. E.
Sensenbaugh, J. D.
Severs, R. K.
Shaffer, N. R.
Shale, C. C.
Sheehy, J. P.
Sheppard, S. V.
Sherman, R. A.
Shutko, F. W.
Sibel, J. T.
Silverman, L.
Simon, H.
Simonsen, R. N.
Simpson, H. C.
Sklyarskaya, N. K.
Smith, D. F.
Smith, J. H.
Smith, R. I.
Smith, S.
Smith, W. M.
Smith, W. S.
8-18
8-4
4-202
3-66, 8-25
8-31, 8-40
4-34, 4-35, 6-24
4-78, 4-80
8-9
8-37, 8-38
3-43
7-2
3-4
4-54
4-189
8-12
3-69
4-31, 4-49, 4-66, 4-127, 4-132,
4-133, 8-18
4-131, 4-134, 4-138, 4-150, 4-153,
4-162, 4-163, 4-165, 4-170, 4-180, 4-181,
4-182, 4-183
8-36
4-187, 4-190, 4-196
8-43
4-190, 4-196
7-3, 8-31
7-3
4-
23
111, 8-31
14, 8-17
A-21
-------
Snowball, A. F.
Sommerlad, R. E.
Sordelli, D.
Sorg, T. J.
Spaite, P. W.
Spaulding, D. B.
Spenceley, G. D.
Spencer, J. D.
Spieckerman, J. A.
Springer, K. J.
Stahenow, G.
Stairmand, C. J.
Starkman, E. S.
Stastny, E. P.
Stenburg, R. L.
Stephan, D. G.
Stephens on, J. W.
Sterling, M.
Stern, A. C.
Stickel, R.
Stoker, R. L.
Stopperka, K.
Storch, H. L.
Storch, O.
Strauss, W.
Strewe, W.
Stuart, H. H.
8-32
3-17, 4-171, 4-172
8-33, 8-34
3-67, 3-68
4-129, 4-135, 4-163, 4-164, 4-176;
4-178, 7-2, 8-8
4-187, 4-190, 4-196
8-31
8-14
4-211, 4-213
8-7, 8-8
8-21
4-4, 4-5, 4-39, 4-40, 4-43, 4-44
8-5
8-34
8-21, 8-23, 8-37
4-3, 4-129, 4-135, 4-137, 4-160,
4-163, 4-165, 4-176, 4-178
8-21
3-38, 8-21
4-29, 4-30
8-36
4-28
8-34
4-76, 8-38, 8-45
8-31
4-10, 4-15, 4-37, 4-134
8-14
8-35
A-22
-------
Sullivan, J. L. 4-217, 8-31, 8-44
Swinehart, G. 3_75> 8-20
Syrovatka, Z. 8-21
Taheri, M. 7_3
Talens, P. G. 8-24
Tarat, E. Y. 4-76
Tate, R. W. 4-78
Tebbens, B. D. 8-14
Teller, A. J. 4-36, 4-37, 4-54, 8-26
Termeulen, M. A. 8-37
Theodore, L. 7-3
Thieme, W. 8-14
Thorn, G. W. 8-31
Thomas, G. 8-30
Thomas, J. F. 8-14
Thomas, N. J. 4-185
Thomburgh, G. E. 8-23
Thompson, C. W. 4-188, 4-191
Thring, M. W. 4-189, 4-196, 4-207, 4-217
Tigges, A. J. 8-8
Todd, W. F. 4-163, 4-164
Tolciss, J. 8-22
Tomaides, M. 8-41
Tomany, J. P. 3-17, 3-18, 8-12
Topper, L. 4-189
Toyama, T. 8-33, 8-34
Treat, R. 8-4
Trenck, H. M. 8-14
A-23
-------
Tribus, M. 8-4
Trinks, W. 4-189, 4-196, 4-207, 4-211, 4-213
Truitt, S. M. 4-217
Tulcinsky, S. 8-32
Tyler, T. L. 4-190, 4-196
Underwood, G. 8-32
Vandaveer, F. E. 4-202
Van Doornum, G. A. W. 8-14
Varchavski, I. L. 8-5
Vasil'eva, A. A. 8-43
Vasseller, W. P. 4-66
Vaughn, R. D. 3-61, 3-63, 3-64, 3-65, 3-66, 3-74,
3-76, 3-83, 3-84, 3-86
Venezia, R. 3-4
Verrochi, W. A. 8-8
Vettebrodt, K. 8-30
Vickerson, G. L. 8-23
Viets, F. H. 8-32
Voelker, E. M. 3-79, 8-24
Vogely, W. A. 8-25
Voinov, A. N. 8-15
Vollheim, G. 4-190, 4-195, 4-217
VonBergen, J. M. 3-32
VonLehmden, D. J. 8-11, 8-16, 8-21, 8-39
Vosseller, W. P. 8-37
Wagner, K. 8-26
Waitkus, J. 4-196, 4-217
Walker, A. B. 4-46, 7-3, 8-21, 8-35
A-24
-------
Wallach, A. 4_217
Wallin, S. c. 8_7
Walsh, G. W. 4_135> 4_137
Walter, E. 8_40> g_42
Walters, D. F. 8_24
Wanta, R. C. 8_36
Waple, E. R. 4_86
Warner, D. L. 4_86
Wasser, J. H. 7_2, 8-17
Watson, K. S. 8-14
Weatherley, D. 8-40
Weaver, L. 8-25
Weber, E. J. 4-188, 4-191
Weber, E. V. 4-204, 4-211
Wechselblatt, P. M. 8-28
Wegman, L. S. 8-21
Weil, S. A. 4-203, 4-204
Wene, A. W. 8-24
Went, F. W. 8-43
Wentink, G. 8-17
Weston, R. F. 3-66, 8-25
Wettig, K. 8-4
Weyers, W. 8-14
Wheeler, D. H. 8-32
Whiddon, O. D. 8-12
White, H. J. 4-90, 4-101, 4-102
Whitwam, K. B. 8-29
Wiemer, P. 8-40
Wiley, J. S. 8~25
A-25
-------
Wilhoyte, H. J. 4-190
Willett, H. P. 8-32, 8-34
Williams, C. E. 4-134, 4-135, 4-136
Williams, D. I. T. 8-31
Williams, G. C. 4-187, 4-190, 4-196
Williams, R. E. 8-24
Williamson, J. E. 8-21, 8-23, 8-24
Williamson, J. T. 3-78
Wilson, E. L. 4-1, 4-6, 4-7, 4-8, 4-9, 4-35, 4-112,
6-4
Wilson, J. G. 8-37
Wood, C. 8-7
Woodland, R. G. 8-24
Woodruff, P. H. 8-24
Wright, C. H. 8-11
Yagi, S. 4-190, 4-196
Yamaki, N. 8-6
Yocum, J. E. 8-38
Yokomiyo, K. 8-32
York, O. H. 4-73
Young, P. A. 4-111, 8-30
Zaitsev, M. M. 8-28
Zanon, D. 8-33, 8-34
Zavodny, S. 8-22
Zender, W. 8-4
Zeschmann, E. G. 8-3
Zhevnovatyi, A. N. 4-85
Zhigalina, I. S. 8-28
A-26
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CONTROL TECHNOLOGY FOR PARTICULATE AIR POLLUTANTS
SUBJECT INDEX
A
Acid manufacturing (see specific acid)
Aerosol
definition of 2-1
Afterburners
discussion of 4-1844-213
typical applications of 4-213, 4-217
Aircraft
particulate emission sources 2-42-5
Apartment house incinerators
general discussion of 3-813-83
Asphalt batch plants
emissions from 3-433-44
control device used in 3-433-44
Automobile disposal 3-703-72
Automobiles
emission sources 2-4, 3-33-7
Automotive emission control systems 3-33-7
B
Baffles (impingement) 4-734-74
Baghouse filters (see Fabric filtration)
Blast furnaces
control devices used in 3-343-35
A-27
-------
Carbon black manufacturing
emissions from 3-53
control devices used in 3-53
Cement manufacturing
emissions from 3-413-42, 4-175
control devices used in 3-41-3-42, 4-111, 4-175-4-176
Centrifugal collectors (dry)
discussion of 3-163-18, 4-154-29
applications of 4-29
Cleaning of fabric filters 4-1644-170
Coffee processing
emissions from 3-543-56
control devices used in 3-553-56
Coke manufacturing
emissions from 3-453-48
control devices used in 3-463-48
Collection efficiency of control equipment 4-10, 4-194-24, 4-344-35,
4-1074-109, 6-4
Combustion sources 2-32-4
Commercial and industrial incinerators
description of 3-773-80
Composting
description of 3-693-70
Contaminant (see Pollutant)
Costs of control equipment
general 6-16-64
maintenance and operating 6-15, 6-18, 6-19
gravitational collectors 6-22
A-28
-------
centrifugal collectors (dry) 6-22
wet collectors 6-23
electrostatic precipitators 6-25
filtration 6-256-26
afterburners 6-266-27
Cotton ginning
emissions from 3-56
control methods in 3-56
Cyclone collectors (see Centrifugal
collectors)
D
Demolition of masonry
emissions from 3-58
Design of combustion systems 3-33-9
Diesel-powered vehicles
emissions of 3-73-9
Disposal of collected particulate
material 6-546-64
Domestic incinerators 3-77
Dust
definition of 2-1
E
Electrostatic precipitators
(high voltage)
discussion of 3-19, 4-87-4-112
applications of 4-7-4-9, 4-109
Electrostatic precipitators (low voltage)
discussion of 3-19> 4-113-4-126
applications of ^^ 4~123
A-29
-------
Emission factors
general 5-15-11
coal combustion 5-2
process industries 5-11
Energy conservation 3-25, 3-27
Energy source fuels 3-11
Energy substitution 3-203-25
Fabric filtration
discussion of 3-19, 4-1274-184
application of 4-1274-128, 4-1754-180
Fabrics (filter) 4-1464-148, 4-1584-164
Federal assistance for solid waste
programs 3-863-87
Filters (irrigated wet) 4-66
Flue fed incinerators (see Apartment
house incinerators)
Fly ash
definition of 2-2
Fog
definition of 2-2
Foundries (gray iron)
emissions from 3-373-38, 4-176
control devices used in 3-38, 4-176
Fume
definition of 2-2
A-30
-------
G
Gas cleaning devices 3-163-19, 4-14-3
Gasoline-fueled vehicles
emissions of 2-4 3-3 3-7
Glass manufacturing
emissions from 3_51_3_53
process description of 3_si_3_53
Gypsum processing
emissions from 3-533-54
control devices used in 3-533-54
I
Incineration of solid wastes 3-733-85
Incinerator control equipment
efficiency of 3-733-85
Incinerators (see specific type)
Industrial sources of particulates 2-4
Iron and steel mills
emissions from 3-343-37
control devices used in 3-343-37
K
Kraft pulp mills
emissions from 3-423-43
control devices used in 3-423-43, 4-112
Landfills
general description of 3-653-67
A-31
-------
M
Mist
definition of 2-2
Mist eliminators 4-664-76
Motor vehicles
emission sources 2-4, 3-33-7
Municipal incinerators
general discussion of 3-833-85
control devices for 3-833-85
O
Open burning 3-58, 3-74
Open top incinerators 3-76
Particle
definition of 2-2
Particulate matter
definition of 2-1
Petroleum refineries
emissions from 3-393-40
control devices used in 3-393-40
Phosphoric acid manufacturing
emissions from 3-45
control device used in 3-45
Pollutant
definition of 2-1
R
Research (current) in control methods 7-17-3
Road dust
control of 3-59
A-32
-------
Road grading
dust generation from 3-59
Sandblasting
control of particulates from 3-593-60
Scrubbers
centrifugal spray 4-404-43
disintegrator 4-61
impingement plate 4-434-45
in-line wet 4-63, 4-65
mechanically induced spray 4_59_4_60, 4-62
packed bed 4-51,4-534-56
performance of 3-183-19, 4-324-65
self-induced spray 4-59, 4-60
venturi 4-44, 4-464-51
Settling chambers
discussion of 3-16, 4-104-14
applications of 4-134-14
Shutdown of emission sources 3-30
Sintering plants
control devices used in 3-34
Smelters
emissions from 3-32, 3-493-50
Smoke
definition of 2-2
Soap and detergent manufacturing
emissions from 3-50 3-51
control devices used in 3-503-51
A-33
-------
Solid waste
definition of 3-623-63
quantity produced 3-633-65
Soot
definition of 2-2
Source relocation 3-20
Sources of particulate matter 2-3
Spray chambers 4-354-38
Spray nozzles
types of 4-784-81, 4-83
Sprays
definitions of 2-2
Spray towers 4-394-41
Stationary combustion sources 3-103-15
Steel furnaces
control devices used in 3-353-36
emissions from 3-353-36
Sulfuric acid manufacturing
emissions from 3-44
control devices used in 3-44, 4-112
W
Wet collectors
discussion of 4-324-86
Wood waste incinerators
emissions from 3-763-77
A-34
U. S. GOVERNMENT PRINTING OFFICE : 1869 O - 331-716
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