APTD-1102
    FIELD  OPERATIONS
    AND ENFORCEMENT
    MANUAL  FOR
    AIR  POLLUTION
    CONTROL
    VOLUME III:
    INSPECTION PROCEDURES FOR
    SPECIFIC INDUSTRIES
~
        US. ENVIRONMENTAL PROTECTION AGENCY
               Office of Air Programs
          Stationary Source Pollution Control Programs
         Research Triangle Park, North Carolina  27711

-------
                                            APTD-1102
             FIELD OPERATIONS
      AND  ENFORCEMENT  MANUAL
     FOR AIR POLLUTION  CONTROL

VOLUME III:  INSPECTION  PROCEDURES
         FOR SPECIFIC  INDUSTRIES
                  Prepared by
                Melvin I. Weisburd
        Pacific Environmental Services, Inc.
             2932 Wilshire Boulevard
           Santa Monica, California 90403

                       for

           System Development Corporation
               2500 Colorado Avenue
           Santa Honica, California 90406
             Contract No. CPA 70-122
                  Prepared for

          ENVIRONMENTAL PROTECTION AGENCY
             Office of Air Programs
     Stationary Source Pollution Control Programs
     Research Triangle Park, North Carolina 27711

                  August  1972

-------
                                     ii
The APTD (Air Pollution Technical Data) series of reports is issued by the
Office of Air Programs, Environmental Protection Agency, to report technical
data of interest to a limited number of readers.  Copies of APTD reports are
available free of charge to Federal employees, current contractors and
grantees, and non-profit organizations - as supplies permit - from the Air
Pollution Technical Information Center, Environmental Protection Agency,
Research Triangle Park, North Carolina 27711 or -may be obtained, for a
nominal cost, from the National Technical Information Service, 5285 Port
Royal Road, Springfield, Virginia 22151.
This report was furnished to the Environmental Protection Agency by Pacific
Environmental Services, Inc. of Santa Monica, California  (pursuant to a
subcontract with System Development Corporation) in fulfillment of prime
Contract No. CPA 70-122.  The contents of this report are reproduced herein
as received from Pacific Environmental Services, Inc.  The opinions,
findings, and conclusions expressed are those of the author and not neces-
sarily those of the Environmental Protection Agency.
              Office of Air Programs Publication No. APTD-1102

-------
                                     ill
The Field Operations and Enforcement Manual for Air Pollution Control is
divided into three separate volumes.

Volume I, Organization and Basic Procedures, contains Chapters 1 through 4,

Volume II, Control Technology and General Source Inspection, contains
Chapters 5 and 6.

Volume III, Inspection Procedures for Specific Industries, contains
Chapter 7.

-------
                                   ABSTRACT









     The Field Operations and Enforcement Manual for Air Pollution Control,




Volume III explains in detail the following:  inspection procedures for




specific sources, kraft pulp mills, animal rendering, steel mill furnaces,




coking operations, petroleum refineries, chemical plants, non-ferrous




smelting and refining, foundries, cement plants, aluminum reduction plants,




mining, coal preparation, fertilizer industry, paint and varnish manufactur-




ing, galvanizing operations, roofing plants, and asphalt batch operations.

-------
                       TABLE OF  CONTENTS FOR VOLUME III



LIST OF FIGURES	    xiii

LIST OF TABLES	    xvi

CHAPTER 7.  INSPECTION PROCEDURES FOR SPECIFIC SOURCES  	   7.1.1

   I.  INTRODUCTION	7.1.1
  II.  KRAFT PULP MILLS	   7.2.1
       A.  Nature of Source Problem	7.2.1
       B.  Process Description   	   7.2.1
           1.  Pulp Cooking	7.2.5
               a.  Controls	7.2.5
           2.  Initial Chemical Recovery  	   7.2.6
               a.  Controls	7.2.8
           3.  Final Chemical Recovery  	   7.2.13
               a.  Controls 	   7.2.13
           4.  Other Mill Sources 	   7.2.14
       C.  Inspection Points	7.2.14
           1.  Environmental Observations 	   7.2.17
           2.  Observation of Exterior of Mill	7.2.20
           3.  Inspection of the Plant Interior  	   7.2.21
               a.  The Interview	7.2.21
               b.  The Physical Inspection  	   7.2.23
                   (1)  Black Liquor System 	   7.2.23
                   (2)  TRS Monitors	7.2.24
                   (3)  Recovery Furnace  	   7.2.26
                   (4)  Lime Kiln System	7.2.27

REFERENCES  	   7.2.29

 III.  ANIMAL RENDERING	7.3.1
       A.  Description of Source	7.3.1
       B.  Process Description   	   7.3.1
           1.  Dry Rendering Processes	7.3.7
           2.  Wet Processes	7.3.9
           3.  Feather Cookers	7.3.9
           4.  Blood Drying 	   7.3.11
       C.  Air Pollution Controls 	   7.3.11
       D.  Inspection Points	7.3.12
           1.  Environmental Observations 	   7.3.13
           2.  Observation of the Exterior of Plant 	   7.3.16
           3.  Inspection of the Interior of the Plant	7.3.17
               a.  Interview with Plant Management  	   7.3.17
                   (1)  Inventory of Feedstocks  	   7.3.17
                   (2)  Plant Sanitation Practices  	   7.3.18

-------
                                       vl
                b.   The Physical Inspection  	   7.3.18
                    (1)  Dead Stock Skinning Room	7.3.18
                    (2)  Cookers 	   7.3.18
                    (3)  Vent Lines	7.3.19
                    (4)  Other Sources 	   7.3.19
                    (5)  Air Pollution Control System  	   7.3.20

 REFERENCES  	   7.3.22
   IV.   STEEL MILLS-FURNACES 	   7.4.1

        A.   Description of Sources	7.4.1
        B.   Process Description  	   7.4.1
            1.  Blast Furnaces	7.4.3
            2.  Electric Steel Furnaces  	   7.4.6
            3.  Open Hearth Furnaces	7.4.9
            4.  Basic Oxygen Furnace 	   7.4.12
        C.   Emissions and Inspection Points  	   7.4.15
            1.  Blast Furnaces 	   7.4.15
            2.  Electric Steel Furnaces  	   7.4.17
            3.  Open Hearth Furnaces 	   7.4.17
            4.  Basic Oxygen Furnaces  	   7.4.18

 REFERENCES  	   7.4.20

   V.  COKING OPERATIONS 	   7.5.1

       A.   Description of Source	7.5.1
       B.   Process  Description 	   7.5.1
       C.   Contaminants Emitted  	   7.5.6
           1.  Coke Preparation and Oven Operations	7.5.6
           2.  By-Product Processing Emissions 	   7.5.7
       D.   Inspection Points 	   7.5.10
           1.  Dust from Material Transfer 	   7.5.11
           2.  Charging Operations 	   7.5.13
           3.  Condition and Operation of Oven	7.5.15
           4.  Coke Transfer and Quench Operations 	   7.5.18
           5.  Screening and Sizing  	   7.5.18
           6.  Gas  and Vapor Losses	7.5.19

REFERENCES  	   7.5.20

  VI.  PETROLEUM INDUSTRY  	   7.6.1

       A.   Description of Source	7.6.1
       B.   Process  Description 	   7.6.1
           1.  Crude Oil Production	7.6.1
           2.  Oil  Refining	7.6.2
               a.  Separation	7.6.6
               b.  Treating	7.6.7
               c.  Conversion	7.6.7
               d.  Blending	7.6.8
               e.  Types of Contaminants	7.6.9
           3.  Marketing 	   7.6.10

-------
                                      vii
      C.  Air Pollution Potential of Petroleum Equipment  	   7.6.13
          1.  Refining Equipment  	   7.6.13
              a.  Flares and Slowdown Systems 	   7.6.13
              b.  Pressure Relief Valves  	   7.6.13
              c.  Storage Vessels 	   7.6.14
              d.  Bulk-Loading Facilities 	   7.6.14
              e.  Catalyst Regenerators 	   7.6.14
              f.  Effluent-Waste Disposal 	   7.6.15
              g.  Pumps and Compressors 	   7.6.15
              h.  Air-Blowing Operations  	   7.6.16
              i.  Pipeline Valves and Flanges, Blind Changing,
                    Process Drains  	   7.6.16
              j.  Cooling Towers  	   7.6.17
              k.  Vacuum Jets and Barometric Condensers 	   7.6.17
              1.  Effective Air Pollution Control Measures  	   7.6.17
          2.  Waste-Gas Disposal Systems  	   7.6.19
          3.  Storage Vessels 	   7.6.22
              a.  Types of Storage Vessels  	   7.6.22
          4.  Loading Facilities  	   7.6.23
          5.  Catalyst Regeneration 	   7.6.28
              a.  Types of Catalysts  	   7.6.28
              b.  Regeneration Processes  	   7.6.31
              c.  Air Pollution Control Equipment 	   7.6.33
           6.  Oil-Water Effluent Systems 	   7.6.33
               a.  The Air Pollution Problem  	   7.6.36
               b.  Asphalt from Crude Oil	7.6.37
           7.  Valves 	   7.6.38
               a.  Types of Valves  	   7.6.38
               b.  The Air Pollution Problem  	   7.6.39
           8.  Cooling Towers 	   7.6.41
           9.  Miscellaneous Sources  	   7.6.43
               a.  Airblowing	7.6.43
               b.  Blind Changing 	   7.6.43
               c.  Equipment Turnarounds  	   7.6.44
               d.  Tank Cleaning	7.6.45
               e.  Use of Vacuum Jets	7.6.45
               f.  Use of Compressor Engine Exhausts	7.6.46
       D.  Inspection Points and Process Inventories	7.6.46
           1.  Initial Inspection Procedures  	   7.6.46
               a.  Bulk Plant Data	7.6.51
               b.  Truck Loading Inspection Data Sheet  	   7.6.51
               c.  Oil-Effluent Water Separator Inspection  	   7.6.57
               d.  Tank Inspection Report 	   7.6.57
               e.  Data Sheet for Natural Gasoline,  Gas, and Cycle
                     Plants 	   7.6.57
           2.  Inspection Points and Reinspection Procedures  	   7.6.60
           3.  Environmental Observations 	   7.6.60
           4.  The Physical Inspection  	   7.6.62

REFERENCES   	   7.6.67

-------
                                     viii
 VII.  CHEMICAL PLANTS	7.7.1

       A.  Nature of Source Problem - Unit Processes and Unit
             Operations	7.7.1
       B.  Process Description - Unit Processes and Unit Operations . .  .   7.7.2
           1.  Unit Processes	7.7.3
               a.  Nitration	7.7.3
               b.  Sulfonation and Sulfation	7.7.3
               c.  Halogenation	7.7.6
               d.  Amination by Airanonolysis	   7.7.6
               e.  Hydrolysis	7.7.6
               f.  Oxidation	7.7.6
               g.  Hydrogenation	7.7.6
               h.  Friedel-Crafts Reactions 	   7.7.7
           2.  Unit Operations	7.7.7
           3.  Control Methods	7.7.7
       C.  Inspection Points - Unit Processes and Unit Operations  . . .  .   7.7.9
       D.  Nature of Source Problem - Sulfuric Acid Manufacturing  ....   7.7.10
       E.  Process Description - Sulfuric Acid Manufacturing  	   7.7.12
           1.  Chamber Process	   7.7.12
           2.  Contact Process	7.7.15
       F.  Control Methods - Sulfuric Acid Manufacturing  	   7.7.18
           1.  Sulfur Dioxide Control 	   7.7.18
           2.  Sulfuric Acid Mist Control 	   7.7.21
       G.  Inspection Points - Sulfuric Acid Manufacturing  	   7.7.23
           1.  Environmental Surveillance 	   7.7.25
           2.  Inspection of the Premises 	   7.7.26
               a.  Interview  	   7.7.26
               b.  Physical Inspection  	   7.7.27
       H.  Nature of Source Problem - Vinyl Chloride Manufacturing  .  .  .   7.7.30
           1.  Nature of Air Pollution Problems 	   7.7.30
       I.  Process Description - Vinyl Chloride Manufacturing 	   7.7.31
           1.  Basic Reactions  	   7.7.31
           2.  Current Manufacturing Practice 	   7.7.32
           3.  Control Methods  	   7.7.35
       J.  Inspection Points - Vinyl Chloride Manufacturing 	   7.7.37
           1.  Environmental Surveillance 	   7.7.37
           2.  Plant Inspection 	   7.7.38
               a.  Interview  	   7.7.38
               b.  Physical Inspection  	   7.7.39
REFERENCES   	   7.7.40
VIII.  PRIMARY AND SECONDARY NON-FERROUS SMELTING AND REFINING  	   7.8.1
       A.  Introduction	7.8.1
       B.  Description of Source—Primary Smelting  	   7.8.2
           1.  Process Description  	   7.8.3
               a.  Copper	7.8.3
                   (1)  Roasting	7.8.4
                   (2)  Reverberatory Furnaces  	   7.8.6
                   (3)  Converters	   7.8.8
                   (4)  Contaminants Emitted  	   7.8.10

-------
                                     ix
               b.  Lead	7.8.11
                   (1)  Sintering 	   7.8.11
                   (2)  Blast Furnaces  	   7.8.15
                   (3)  Lead Refining	7.8.17
                   (4)  Additional Equipment and Operations 	   7.8.19
                   (5)  Contaminants Emitted  	   7.8.19
               c.  Zinc	7.8.20
                   (1)  Roasting  	   7.8.20
                   (2)  Sintering	%	7.8.23
                   (3)  Zinc Extraction 	   7.8.24
                   (4)  Contaminants Emitted  	   7.8.24
           2.  Inspection Points—Primary Smelting and Refining 	   7.8.25
               a.  Environmental Observations 	   7.8.25
               b.  Observations of the Exterior of Smelters 	   7.8.26
               c.  In-Plant Observations  	   7.8.26
       C.  Nature of Source-Secondary Smelters  	   7.8.27
           1.  Process Description—General 	   7.8.28
               a.  Brass and Bronze 	   7.8.28
                   (1)  Blast Furnaces and Cupolas  	   7.8.30
                   (2)  Ingot Production—Reverberatory Furnaces  ....   7.8.33
               b.  Lead	7.8.36
                   (1)  Reverberatory Furnaces  	   7.8.36
                   (2)  Blast and Cupola Furnaces 	   7.8.38
                   (3)  Pot Furnaces	7.8.40
               c.  Zinc	   7.8.40
               d.  Aluminum 	   7.8.44
           2.  Inspection Points—Secondary Smelting and Refining .  .  .  .   7.8.46
               a.  Environmental Observations 	   7.8.46
               b.  Observation of the Exterior of the Secondary Smelter .   7.8.47
               c.  The Physical Inspection  	   7.8.47

REFERENCES   	   7.8.50
  IX.  FERROUS AND NON-FERROUS FOUNDRIES  	   7.9.1

       A.  Description of Sources	7.9.1
       B.  Grey Iron Foundries	   7.9.1
           1.  Process Description  	   7.9.1
           2.  Inspection Points	7.9.6
       C.  Non-Ferrous Foundries	7.9.8
           1.  Process Description—Copper-Base Alloys  	   7.9.8
           2.  Inspection Points—Copper-Base Alloys	7.9.16
               a.  Charging 	   7.9.16
               b.  Melting  	   7.9.17
               c.  Pouring  	   7.9.17
           3.  Process Description—Aluminum Melting  	   7.9.19
           4.  Process Description—Zinc Melting  	   7.9.20
           5.  Inspection Points—Aluminum and Zinc 	   7.9.21
           6.  Process Description—Core Making 	   7.9.21

-------
           7.  Inspection Points—Core Making 	  7.9.27
           8.  Process Description—Sand Handling 	  7.9.27
           9.  Inspection Points—Sand Handling 	  7.9.28
          10.  Environmental Observations .	  7.9.30

REFERENCES   	  7.9.31

   X.  CEMENT PLANTS  	  7.10.1
       A.  Description of Source  	  7.10.1
       B.  Process Description  	  7.10.1
       C.  Emissions and Controls 	  7.10.3
       D.  Inspection Points  	  7.10.6
REFERENCES   	  7.10.10

  XI.  ALUMINUM REDUCTION PLANTS  	  7.11.1
       A.  Description of Source  	  7.11.1
       B.  Process Description  	  7.11.2
           1.  Material Handling  	  7.11.2
           2.  Electrode Preparation  	  7.11.4
               a.  Cathode Preparation  	  7.11.4
               b.  Anode Preparation  	  7.11.6
           3.  Potroom Operations 	  7.11.10
               a.  Prebake  	  7.11.10
               b.  Soderberg  	  7.11.13
       C.  Contaminants Emitted 	  7.11.15
       D.  Inspection Points  	  7.11.20
           1.  Environmental Observations 	  7.11.24
           2.  Exterior of Plant  	  7.11.25
           3.  Interior of Plant  	  7.11.26
REFERENCES   	  7.11.28

 XII.  MINING 	  7.12.1

       A.  Nature of Source Problem 	  7.12.1
       B.  Process Description	7.12.1
           1.  Surface Mining 	  7.12.2
               a.  Strip Mining 	  7.12.3
               b.  Open-Pit Mining  	  7.12.5
           2.  Underground Mining 	  7.12.8
       C.  Inspection Points  	  7.12.10
REFERENCES   	  7.12.12

XIII.  COAL PREPARATION PLANTS  	  7.13.1
       A.  Description of Source  	  7.13.1

-------
B. Process Description 	 ,


b. Jigs 	 ,
c. Dense-media 	
d. Classifiers 	 ,
2. Sizing 	 ,
a. Breakers and Crusher 	
b. Screening 	
3 . Drying 	
a. Rotary Dryers 	

c. Cascade Dryers 	 ,

e. Fluid Bed Dryers 	
4. Refuse 	
5. Coal Storage 	
C. Emissions and Controls 	
D. Inspection Points 	
1. Screening, Crushing and Breaking 	
2. Conveyors and Elevators 	
3. Pneumatic Classifying and Dedusting 	


REFERENCES 	
XIV. FERTILIZER INDUSTRY 	
A. Nature of Source Problem 	

2 . Ammonium Nitrate 	

1. Phosphate Fertilizers 	
2. Ammonium Nitrate 	

C. Inspection Points 	
1. General 	

3. Plant Inspection 	
a. Interview 	

REFERENCES 	
XV. PAINT AND VARNISH MANUFACTURING 	
A. Nature of Source Problem 	
	 7.13.1
	 7.13.1
	 7.13.4
	 7.13.4
	 7.13.5
	 7.13.5
	 7.13.6
	 7.13.8
	 7.13.11
	 7.13.11
	 7.13.12
	 7.13.12
	 7.13.13
	 7.13.14
	 7.13.15
	 7.13.16
	 7.13.17
	 7.13.17
	 7.13.18
	 7.13.18
	 7.13.18
	 7.13.18
	 7.13.19
	 7.13.19
	 7.13.20
	 7.14.1
	 7.14.1
	 7.14.2
	 7.14.3
	 7.14.3
	 7.14.3
	 7.14.9
	 7.14.11
	 7.14.13
	 7.14.13
	 7.14.14
	 7.14.14
	 7.14.14
	 7.14.15
	 7.14.17
	 7.15.1
	 7.15.1

-------
         B.  Process Description  	   7.15.1
            1.  Alkyd Resin Manufacturing  	   7.15.2
            2.  Varnish Cooking  	   7.15.3
            3.  Air Pollution Control Techniques   	   7.15.7
         C.  Inspection Points 	   7.15.12
            1.  Environmental Observations   	   7.15.13
            2.  Observations of Plant Exterior  	   7.15.14
            3.  Interior Plant Inspection  	   7.15.15
                a.  The Interview  	   7.15.15
                b.  The Physical Inspection  	   7.15.16

 REFERENCES 	   7.15.18

  XVI.   GALVANIZING OPERATIONS   	   7.16.1

         A.  Description of Source  	   7.16.1
         B.  Process Description  	   7.16.1
         C.  Inspection Points 	   7.16.6
            1.  Environmental Observation  	   7.16.10
            2.  Observations of the Exterior of the Plant  	   7.16.10
            3.  Inspection of the  Interior of the Plant	7.16.11
 REFERENCE  	   7.16.14

 XVII.   ROOFING PLANTS—ASPHALT SATURATORS	7.17.1
         A.  Description of Source  	   7.17.1
         B.  Process Description  	   7.17.1
         C.  Emissions and Controls  	   7.17.1
         D.  Inspection Points 	   7.17.5
 REFERENCE  	   7.17.7

XVIII.  ASPHALTIC CONCRETE BATCHING OPERATIONS

        A.  Description of Source  	   7.18.1
        B.  Process Description 	   7.18.1
        C.  Contaminants Emitted   	   7.18.8
        D.  Inspection Points 	   7.18.13

 REFERENCES 	   7.18.15

 GLOSSARY ..... 	   G.I

-------
                                      xiii
Figure 7.2.1.
Figure
Figure
Figure
Figure
Figure
Figure
7.2.2.
7.2.3.
7.2.4.
7.2.5.
7.2.6.
7.3.1.
Figure 7.3.2.

Figure 7.3.3.
Figure 7.4.1.

Figure 7.4.2.
Figure 7.4.3.
Figure 7.4.4.
Figure 7.4.5.
Figure
Figure
Figure
Figure
Figure
7.4.6.
7.4.7.
7.4.8.
7.5.1.
7.5.2.
Figure 7.5.3.


Figure 7.5.4.

Figure 7.5.5.

Figure 7.5.6.

Figure 7.6.1.
Figure 7.6.2.
Figure 7.6.3.
Figure 7.6.4.
Figure 7.6.5.

Figure 7.6.6.

Figure 7.6.6.
Figure 7.6.7.
Figure 7.6.8.
Figure 7.6.9.
Figure 7.6.10.
Figure 7.6.11.
               LIST OF FIGURES

Flow Diagram of a Kraft Pulping Process Showing
  Principal Emissions at Different Points
A Typical Multiple Effect Evaporator System
Weak Black Liquor Oxidation
Strong Black Liquor Oxidation
Multiple Effect Evaporator System
Continuous Stack Sampler for TRS Compounds
An Integrated Dry Rendering Plant
A Continuous, Vacuum Rendering System Employing
  Tallow Recycling (Carver-Greenfield Process)
A Condenser-Afterburner Control System
Production of Carbon Raw Steel in the United States
  by Various Processes
A Typical Blast Furnace
A Typical Blast Furnace Stove
Direct Arc-Electric Furnace
Relationship Between Electric-Arc Furnace Capacity
  and Transformer Rating
Cross-Section of a Basic Open-Hearth Furnace
Basic Oxygen Furnace
Stora-Kaldo Rotary Oxygen Converter
Process Flow Diagram of Coking Operation
Representative By-Product Plant Flow Sheet
Transverse and Longitudinal Sections Through
  Koppers-Becker Underjet-Fired Low-Differential
  Combination By-Product Coke Ovens
Schematic Representation of Charging and Leveling
  Operations for a By-Product Coke Oven
Approximate Curve Illustrating the Decline in Gas and
  Vapor Evolution at the End of the Coking Cycle
Schematic Representation of Pushing Operations  for a
  By-Product Coke Oven
Representation of Gasoline Distribution System in
  Los Angeles County, Showing Flow of Gasoline  from
  Refinery to Consumer
An Overhead-Controlled Loading Rack
Simplified Flow Diagram of Platforming Process
A Modern Oil-Water Separator
Process Flow Diagram of a Sour Water Oxidizing Unit from
  a Field Drawing
Activity Status Report from an Inspection Made  of a
  Sour Water Oxidizing Unit at an Oil Refinery
Continued
Symbols Used in Petroleum Flow Diagrams
Bulk Plant Data Sheet
Truck Loading Inspection Data Sheet
Oil-Water Separator Inspection Sheet
Natural Gasoline, Gas, and Cycle Plant Survey Summary
7.2.2
7.2.7
7.2.9
7.2.10
7.2.12
7.2.25
7.3.6
                                                                    7.3.10
                                                                    7.3.14

                                                                    7.4.2
                                                                    7.4.4
                                                                    7.4.5
                                                                    7.4.7
7.4.8
7.4.10
7.4.13
7.4.14
7.5.2
7.5.5
                                                                    7.5.12

                                                                    7.5.14

                                                                    7.5.17

                                                                    7.5.18
                                                                    7
                                                                    7
                                                                    7
                                                                    7.6
  6.24
  6.26
  6.30
    35
                                                                    7.6.50
                                                                     ,6.52
                                                                     ,6.53
                                                                     ,6.54
                                                                     .6.55
                                                                      6.56
                                                                      6.58
                                                                    7.6.59

-------
Figure 7.7.1.
Figure 7.7.2.

Figure 7.7.3.

Figure 7.7.4.

Figure 7.7.5.

Figure 7.7.6.
7.7.7.
7.8.1.
7.8.2.
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure 7.8.8.
Figure 7.8.9.
    3.
    4.
    5.
    6.
  8.7.
Figure 7.8.10.

Figure 7.9.1.
Figure 7.9.2.
Figure 7.9.3.

Figure 7.9.4.
Figure 7.9.5.
Figure 7.9.6.
Figure 7.9.7.
Figure 7.9.8.
Figure 7.9.9.
Figure 7.10.1.
Figure 7.10.2.
Figure 7.10.3.
Figure 7.10.4.

Figure 7.11.1.
Figure 7.11.2.

Figure 7.11.3.
Figure 7.11.4.
Figure 7.11.5.
Figure 7.11.6.
Figure 7.11.7.
Flow Diagram for Nitration of Methane
Simplified Flow Diagram of Typical Lead-Chamber Process
  for Sulfuric Acid Manufacture
Schematic Flow Diagram of Sulfur Burning Plant with
  Four-Stage Conversion
Schematic Flow Diagram Wet Gas Plant with 4-Stage
  Conversion
Manufacture of Vinyl Chloride from Acetylene and
  Hydrogen Chloride
Balanced Process for Vinyl Chloride Using Acetylene
  and Ethylene
Oxychlorination Process for Manufacture of Vinyl Chloride
Flow Diagram of a Typical Copper Smelter
Flow Chart for a Lead Smelting Operation
Typical Lead Sintering Plant Major Material Distribution
Usual Treatment of a Sulfide Lead Ore
Typical Zinc Retort Plant Flow Diagram
Diagram Showing One Bank of a Belgian Retort Furnace
Diagram of a Distillation-Type Retort Furnace
Diagram of a Muffle Furnace and Condenser
A 20-Ton Aluminum-Melting Reverbatory Furnace with
  Charging Well Hood
Boiling, Pouring, and Melting Points of Metals and
  Alloys
The Cupola in Detail
Tilting Crucible Furnace
Rotary-Tilting-Type Reverberatory Furnace Venting to
  Canopy Hood and Stack Vent
Rotary-Tilting-Type Brass-Melting Furnace
Shelf Oven
Drawer Oven
Rack Oven
Horizontal, Continuous Oven
Typical Foundry Sand-Handling System
Process Steps—Portland Cement Production
Example of Characteristics of Kiln Dust
Flow Diagram of Cement Plant Operations
Variation of Apparent Resistivity with Temperature and
  Moisture for Some Typical Dusts and Fumes
Aluminum Reduction Plant Flow Diagram
Charging Aluminum Reduction Cell with Ground Dispensing
  Vehicle
Prebaked Carbon Anode Production Process
Soderberg Anode Paste Production Process
Carbon Anodes Ready for Use in Aluminum Pots
Potline, Showing Anodes Suspended in Pots
Details of Prebaked and Soderberg Aluminum Reduction
  Cells
                                                                           7.7.5

                                                                           7.7.14

                                                                           7.7.16

                                                                           7.7.19

                                                                           7.7.33
                                                                           7.7.34
                                                                           7.7.36
                                                                           7.8.5
                                                                           7.8.12
                                                                           7.8.13
                                                                           7.8.18
                                                                           7.8.21
                                                                           7.8.41
                                                                           7.8.42
                                                                           7.8.43
                                                                           7.8.45

                                                                           7.8.49
                                                                           7.9.2
                                                                           7.9.12
                                                                           7.9.14
                                                                           7.9.15
                                                                           7.9.23
                                                                           7.9.24
                                                                           7.9.24
                                                                           7.9.25
                                                                           7.9.29
                                                                           7.10.2
                                                                           7.10.4
                                                                           7.10.6
                                                                            ,10.9
                                                                            ,11.3
                                                                             11.5
                                                                             11.7
                                                                             11.8
                                                                             11.9
                                                                             11.12
                                                                           7.11.14

-------
Figure 7.11.8.  Schematic of Electrolytic Cell as Used in Alcoa A-398      7.11.21
                  Process
Figure 7.11.9.  Schematic of Alcoa Gas Cleaning Process                    7.11.22
Figure 7.11.10. Cross-Section of Roof Scrubber                             7.11.23
Figure 7.13.1.  Rejection of Flat Refuse by Slot Shaker                    7.13.3
Figure 7.13.2.  Diagram of Rheolaveur Coal Launder with Two Rheoboxes      7.13.4
Figure 7.13.3.  McNally Norton Standard Washer                             7.13.5
Figure 7.13.4.  Cross Section McNally Tromp Bath                           7.13.6
Figure 7.13.5.  Bradford Breaker, for Use at Mine and Plant                7.13.8
Figure 7.13.6.  Single-Roll Coal Crusher—Diagrammatic Section             7.13.9
Figure 7.13.7.  Double-Roll Coal Crusher—Diagrammatic Section             7.13.9
Figure 7.13.8.  Hammer-Mill Coal Crusher—Diagrammatic Section             7.13.10
Figure 7.13.9.  Ring Coal Crusher—Diagrammatic Section                    7.13.10
Figure 7.13.10. McNally Fine Coal Cascade Dryer                            7.13.13
Figure 7.13.11. Suspension-Type Flush Drying System (Thermal Dryer)         7.13.14
Figure 7.13.12. McNally Flowdryer                                          7.13.15
Figure 7.14.1.  Production of Normal Superphosphate                        7.14.6
Figure 7.14.2.  Phosphoric Acid Acidulation Process                        7.14.8
Figure 7.14.3.  Flow Diagram for the Manufacture of Ammonium Nitrate       7.14.10
Figure 7.15.1.  Uncontrolled Open Kettle for Varnish Cooking               7.15.6
Figure 7.15.2.  Typical Direct-Fired Afterburner with Tangential Entries
                  for Both the Fuel and Contaminated Gases                 7.15.9
Figure 7.15.3.  Diagram of Combustifume Burner in Vertical Stack           7.15.10
Figure 7.15.4.  Schematic Plan for Varnish-Cooking Control System          7.15.11
Figure 7.16.1.  Simplified Flow Chart of Galvanizing Process               7.16.2
Figure 7.16.2.  Removing Work Through a Clean Zinc Surface                 7.16.4
Figure 7.16.3.  Open to a Room-Type Hood Over a Galvanizing Kettle         7.16.5
Figure 7.16.4.  Slot-Type Hood Serving a Chain Link Fence-Galvanizing
                  Flux Box                                                 7.16.7
Figure 7.16.5.  Photomicrograph of Fumes Discharged from a Galvanizing
                  Kettle                                                   7.16.8
Figure 7.17.1.  Schematic Drawing of an Asphalt Roofing Felt Saturator     7.17.2
Figure 7.17.2.  Asphalt Saturator Hood at Felt Feed                        7.17.3
Figure 7.18.1.  Asphalt Batch Plant with a Cyclone Type Dust Collector     7.18.3
Figure 7.18.2.  Flow Diagram of a Typical Hot-Mix Asphalt Paving Batch
                  Plant                                                    7.18.4
Figure 7.18.3.  Composite Asphalt Plant Dust Particle Size Distribution    7.18.10

-------
xvi
                               LIST OF TABLES

Table 7.2.1.    Average Kraft Pulp Mill Potential Emissions
Table 7.2.2.    Average Kraft Pulp Mill Air Emissions with Control
Table 7.2.3.    Summary of Kraft Mill Emission Standards for
                  Washington State
Table 7.2.4.    Odor Thresholds of Kraft Mill Gaseous Sulfur Compounds
                  in Air
Table 7.2.5.    Characteristics of Kraft Mill Gaseous Sulfur Compounds
Table 7.3.1.    Inedible Reduction Process Raw Materials Originating
                  from Slaughterhouses
Table 7.3.2.    Odor Concentrations and Emission Rates from Inedible
                  Reduction Processes
Table 7.3.3.    Odor Threshold Concentrations of Selected Rendering
                  Compounds
Table 7.3.4.    Composition of Typical Inedible Raw Materials Charged
                  to Reduction Processes
Table 7.3.5.    Odor Removal Efficiencies of Condensers or Afterburners,
                  or Both, Venting a Typical Dry Rendering Cooker
Table 7.5.1.    Sequence of Charging Operations
Table 7.6.1.    Sources and Control of Air Contaminants from Crude-Oil
                  Production Facilities
Table 7.6.2.    Potential Sources of Emissions from Oil Refining
Table 7.6.3.    Hydrocarbon Emission Factors for Refinery Sources
Table 7.6.4.    Sources and Control of Hydrocarbon Losses from
                  Petroleum Marketing
Table 7.6.5.    Suggested Control Measures for Reduction of Air
                  Contaminants from Petroleum Refining
Table 7.6.6.    Leakage of Hydrocarbons from Valves of Refineries in
                  Los Angeles County (1958)
Table 7.7.1.    Commonly Used Unit Processes
Table 7.7.2.    Examples of Mass Transfer Operations and Air Pollutant
                  Potential
Table 7.7.3.    Expected Performance of Acid Mist Collection Systems
Table 7.8.1.    Typical High Quality Concentrate Analysis
Table 7.8.2.    Emissions From Copper Roasters, Reverberatory Furnaces,
                  and Converters
Table 7.8.3.    Typical Reverberatory Furnace Operating Conditions
Table 7.8.4.    Reverberatory Furnace Off-Gas Composition
Table 7.8.5.    Composition of Reverberatory Furnace Molten Products
Table 7.8.6.    Emissions from Lead Sintering, Blast Furnaces,  and
                  Reverberatory Furnaces
Table 7.8.7.    Typical Zinc Roasting Operations
Table 7.8.8.    Typical Zinc Sintering Operations
Table 7.8.9.    Nominal Chemical Specifications for BBII Standard Alloys
Table 7.8.10.   Types of Copper-Bearing Scrap
Table 7.8.11.   Rotary Furnace Particulate Emissions—Test A
Table 7.8.12.   Reverberatory Furnace Particulate Emissions—Test C
Table 7.8.13.   Cupola Particulate Emissions—Test E
Table 7.8.14.   Chemical Requirements for Lead
                                      7.2.3
                                      7.2.4

                                      7.2.16

                                      7.2.18
                                      7.2.19

                                      7.3.2

                                      7.3.4

                                      7.3.5

                                      7.3.8

                                      7.3.15
                                      7.5.16

                                      7.6.3
                                      7.6.4
                                      7.6.11

                                      7.6.12

                                      7.6.18

                                      7.6.40
                                      7.7.4

                                      7.7.8
                                      7.7.24
                                      7.8.3

                                      7.8.6
                                      7.8.7
                                      7.8.7
                                      7.8.8
                                       ,8.18
                                        8.22
                                       ,8.23
                                       ,8.30
                                        8.31
                                        8.34
                                        8.35
                                        8.36
                                      7.8.37

-------
                            xvii
11.3.
11.4.
11.5.
13.1.
Table 7.8.15.   Dust and Fume Emissions from a Secondary Lead-Smelting
                  Furnace                                                  7.8.39
Table 7.9.1.    General Recommendations for Operating Whiting Cupolas      7.9.4
Table 7.9.2.    Dust and Fume Emissions from Gray Iron Cupolas             7.9.5
Table 7.9.3.    Some Collection Efficiencies of Experimental Small-Scale
                  Control Devices Tested on Gray Iron Cupolas              7.9.7
Table 7.9.4.    Dust and Fume Discharge from Brass Furnaces                7.9.9
Table 7.9.5.    Relative Volatilities and Melting Temperatures for
                  Non-Ferrous Metals                                       7.9.11
Table 7.9.6.    Air Contaminant Emissions from Core Ovens                  7.9.26
Table 7.11.1.   Raw Materials for the Production of One Ton of
                  Aluminum                                                 7.11.11
Table 7.11.2.   Comparison of Requirements for Prebaked and Soderberg
                  Systems                                                  7.11.11
                Emission Sources and Contaminants                          7.11.16
                Total F  Emission - Daily Rate and Control Efficiency      7.11.17
                Total SO  Emission - Daily Rate and Control Efficiency     7.11.18
                Specific Gravities of Coal and Impurities                  7.13.3
        13.2.   Commercial Sizes of Anthracite                             7.13.7
        14.1.   Control of Emissions from Fertilizer Manufacturing         7.14.12

Table 7.16.1.   Chemical Analyses of the Fumes Collected by a Baghouse
                  and by an Electric Precipitator from Zinc-Galvanizing
                  Kettles                                                  7.16.9
Table 7.17.1.   Emissions from a Water Scrubber and Low-Voltage,
                  Two-Stage Electrical Precipitator Venting an
                  Asphalt Saturator                                        7.17.4
Table 7.17.2.   Emissions from a Bag Filter and Cyclone Separator
                  Venting an Asphalt Saturator                             7.17.4
Table 7.17.3.   Emissions from a Water Scrubber Venting an Asphalt
                  Saturator                                                7.17.5
Table 7.18.1.   Standard U.S. and Tyler Screen Scales                      7.18.5
Table 7.18.2.   Mix Compositions                                           7.18.6
Table 7.18.3.   Asphalt Test Specifications                                7.18.7
Table 7.18.4.   Dust and Fume Discharge from Asphalt Batch Plants          7.18.9
Table 7.18.5.   Test Data from Hot-Mix Asphalt Paving Plants Controlled
                  by Scrubbers                                             7.18.12
Table
Table
Table
Table
Table
Table

-------
                                     7.1.1
                                    CHAPTER 7
                   INSPECTION PROCEDURES FOR SPECIFIC SOURCES

I.  INTRODUCTION
    Specific sources of air pollution, described in this chapter,  are comprised
    of industrial facilities which may be major targets of air pollution control,
    are significant contributors to air pollution as stationary point sources
    and are of such complexity that training and familiarization on the part of
    the enforcement officer is required before he can assume complete responsi-
    bility for the inspection of these plants.

    Major metallurgical, chemical processing, mining and other industries which
    contribute to the full range of air pollution,  including smoke, fumes, dust,
    odor, gases and vapors, are described in this chapter.  Although not all
    industries of possible interest are treated, the operations described are
    typical of stationary sources in general and should help to prepare
    enforcement officers in entering and inspecting other facilities that may
    be unfamiliar to them.

    In general, each stationary source section of this chapter is  broken down
    as follows:
              •  Nature of Source
              •  Process Description
              •  Emissions
              •  Controls
              •  Inspection Points

-------
                                    7.2.1
                            II.  KRAFT PULP MILLS

A.  NATURE OF SOURCE PROBLEM
    Of the major pulping processes—Kraft, sulfite and neutral sulfite semi-
    chemical (NSSC)—Kraft is most significant from the standpoint of air
    pollution.  As of 1968, Kraft mills produced 75% of the domestic pulp
    in 116 mills with a total production capacity of 32 million short tons.
    They will produce 85% of the total pulp or 60 million short tons by
    1985.(1)

    Kraft mills present a complex air pollution problem in terms of the
    variety and volumes of contaminants emitted.  The major problems are
    odors and particulates.  The malodorous contaminants are inherently
    objectionable and persistent at low concentrations (1 to 10 parts per
    billion); are non-condensible and hence difficult to control; and are
    emitted in large quantities.

B.  PROCESS DESCRIPTION
    The major sources of pollution in a Kraft mill are concentrated in the
    cooking of the pulp and recovery of the process chemicals.  An overview
    of the cooking and recovery cycle and contaminants emitted from specific
    process points is illustrated in Figure 7.2.1.  Average uncontrolled
    emissions from Kraft mills are shown in Table 7.2.1.  Table 7.2.2 lists
    typical control equipment and emission rates.  Emission rates and pro-
    duction capacities, as well as the details of process system design and
    operation will vary considerably among Kraft mills.

-------
                                      (18)
CHIPS
                RELIEF
                                  HEAT EXCHANGER
CH3SH,CH3SCH3,H2S
MOM CONDENSABLES
                     CH3SH,CH3SCH3,H2S
                     NON. CONDENSABLES

                           I




-
- UJ
• ° ^
o
HAV.
QCCUM.
(3)
                                      STEAM, CONTAMINATED WATER,H2S, 6 CH3SH
          PULP
         SPENT AIR , CHjSCHj I*—
         CH3SSCH3
                                                                                        Particulates
                                                                                 (12)
                                            (15)
          Figure 7.2.1.   FLOW  DIAGRAM OF A  KRAFT PULPING  PROCESS
                           SHOWING PRINCIPAL  EMISSIONS AT DIFFERENT POINTS
                           (SOURCE:  WASHINGTON STATE AND DOUGLASS,
                                      References 2 and 3)

-------
                                       7.2.3
             Table 7.2.1.   AVERAGE KRAFT PULP MILL POTENTIAL EMISSIONS
  Department                      '
                                  c

  Digester  (1, 2, 3)
    Batch
    Continuous

  Washers  (4)

  Bleach Plant

  Evaporators  (6, 7)

  Recovery Furnace  (8)

  Dissolving Tank (12)

  Lime Kiln (15,  16)

  Power Boiler*
   (Hog Fuel)

  Paper Machine *

  (Numbers reference Figure 7.2.1)


  (1)  SCF - Cubic feet at standard conditions of 1 atmosphere and 68 F

  (2)  Does not include S02

  (3)  Six-stage bleach plant

  (A)  Chlorine as Ib/T


  *Not shown on drawing.

 **Total reduced  sulfur (see definition in text).

***A11 cooking and chemical recovery operations are in terms of amount of emission
   per air dried  ton of unbleached pulp produced.
'otal Vol.
;CF (I)/T**
300
150
70,000
80,000
300
330,000
30,000
45,000
300,000
430,000
Water Vapor
lb/T**
2,500
1,500
250
220
-
4,300
700
850
3,000
2,700
Total
Particulate
lb/T**
0
0
0
0
0
170
5
45
35
0
255
TRS***
lb/T(2)
2.5
1.5
0.5
2.4
3.5
10.0
0.15
1.0
0.01
0
21.6
                  (SOURCE:  WASHINGTON STATE AND HOUGH AND GROSS,
                            References 2 and 3.)

-------
                 Table 7.2.2.  AVERAGE KRAFT PULP MILL AIR  EMISSIONS WITH  CONTROL
Source
(See Figure 7.2.1)
Digesters (1,2,3)
Batch
Continuous
Washers (4)
Bleach Plant
B. L. Oxidation (5)
Evaporators (6,7)
Recovery Furnace (8)
Dissolving Tank (12)
Lime Kiln (15,16)
Power Boiler
(Hog Fuel)
Air Pollution Controls

Thermal oxidation of
non-condensibles in
lime kiln, steam or air
stripping of condensates

Thermal oxidation
N. S.(2)
None
Caustic scrubbing plus
thermal oxidation of
non-condensibles
(3)
Packed tower (4)
Venturi scrubber
Cyclones
(2)
Paper Machine N. S.
(numbers reference Figure 7.2.1)
Total Vol.
SCF/T3

-
-
80,000
35,000

330,000
30,000
45,000
300,000
400,000
Total
Water Vapor Particulate
Ib/T Ib/T

-
-
220
700

4,300 3.5
700 0.5
1,350 1.0
3,000 5.0
1,600
11,870 10.0
Sulfur
lb/T(l

-
-
-
0.3

1.0
0.1
0.2
0.01
-
1.6
  (1)  Does not include sulfur as S02
  (2)  Not specified
  (3)  No direct contact evaporators; electrostatic precipitators employed  for  particulate removal
  (4)  Employs weak wash as scrubbing medium
a.  Probably wet, judging from figure given for recovery furnace volume, 330,000  scf/ton.
                             (SOURCE:  WASHINGTON  STATE AND  HOUGH AND  GROSS,
                                                                                                        tx>
                                                                                                        .p-

-------
                             7.2.5
Pulp Cooking
Wood chips or  saw dust  together with  the cooking chemicals or white  liquor
are fed  to the digesters  ((1)  in Figure 7.2.1).  The digesters are tall
cylindrical vessels  of  10-20 ton capacity.  Cooking is  typically conducted
at temperatures  around  350°F and 110  Ibs. per square inch gauge pressure
for 3  to 4 hours on  either  a batch or a continuous basis.

The cooking solution consists of approximately 1/3 sodium sulfide and
2/3 caustic soda (sodium hydroxide).   The caustic soda  serves to
dissolve the intercellular material (lignin) which naturally binds the
wood fibers together.  Sodium sulfide reacts with the cellulose to
impart strength  to the ultimate product and with the waste wood products
to produce the air pollution problems characteristic of the Kraft
process.

At the completion of the cooking cycle the contents are blown into the
blow tank.  The pulp stock is screened to remove knots  and undissolved
wood chips and is washed.   The stock then enters the bleaching and
paper production sequence.

The digester is a major source of odorous contaminants, particularly
mercaptans and other gases such as  methanol, which are  released with
steam from digester pop valves, the blow tank, feeder vents,  and
accumulator vents ((2)  in  Figure  7.2.1).

a.  Controls
   Non-condensible  vapors can be vented  to  the  lime kiln,  hog fuel
   boilers, or to  specially constructed  gas fired  furnaces.   In
   many operations  of  this  type, condensers (surface or barometric)
   must be  applied  to  remove water and other  condensible vapors  prior
   to  burning  ((3) in Figure 7.2.1).  Non-condensible  vapors may  be
   stored in a gas holder or surge tank such as the Vaporsphere to
   provide continuous fuel  flow to the combustion equipment.  Non-

-------
                            7.2.6

    condensible gases from certain operations at some facilities can be vented
    to the recovery furnace for firing, as long as these are low volume sources.
    For example, gases from brown stock washers can possibly be burned in
    the recovery furnace without creating an explosion hazard.

Initial Chemical Recovery
The spent black liquor is separated from the pulp at the stock washer.
The weak black liquor is first concentrated in steam-heated multiple-
effect evaporators (6) which increases the solid content from about 15
percent to 55 to 60 percent in the strong black liquor leaving the
evaporators, as shown in Figure 7.2.2.  The solid content is further in-
creased to 60 to 70 percent in the direct contact evaporator where the
liquor is dehydrated by direct contact with the flue gases from the
recovery furnace.  Substantial emissions of hydrogen sulfide and other
malodors are released from the condenser following the multiple-effect
evaporators, from hot wells or seal tanks and from the stack of the
recovery furnace, in the case of the direct contact evaporator.  Emissions
from the furnace are largely due to stripping of hydrogen sulfide by
carbon dioxide contained in the flue gases.  The amount of the emission
depends on how the recovery furnace is operated.

The black liquor is now sufficiently concentrated to support combustion
and is sprayed into the recovery furnace (8) through vertically
oscillating nozzles.  The inorganic constituents, sodium sulfide and
sodium carbonate, are reduced in the  lower reduction zone of
the furnace and settle out in a molten state or smelt on the
furnace grates.  The sulfur organics are oxidized in the upper
zone of the furnace.

The operation of the recovery furnace must be optimized or balanced
to recover the cooking chemicals, to dispose of the sulfur organics
and to satisfy the demand for process steam as well as to control air
pollution.  Increased demand for steam, increased or fluctuating firing

-------
                                                                                 non-condensibles
Steam_
45 psi

vaoors
f— -, f~— | f— n f— n
Vapor Hd.
250° F
16 psig




Heating
Element












L k.
1
1
,i
'i
Vapor Hd.
216° F
1 psig




Heating
Element




l
t
1
1
1
1
1
1
L_
1



Vapor Hd.
132° F
10" Hg.vac




Heating
Element













L-
1

1

Vapor Hd
168° F
18" Hg.vac




Heating
r; lament












L_
1

1
1
A :

1 1


r "n
Vapor Hd
145° F
23" Hg.vac








Heating
» Element




i


•steam
condensate












L_
T
1
1
1
i
T
1
water_I_

- -*-

Vaoor Hd.
115
° F
27" Hg.vac








Heating
» Element




i








1








1
! i
1
i
.
. _±. J"

feed

                                                                                     condtnsates
                                                                  	 . 	 CONDENSATE
                                                                  	 VAPORS
             Figure  7.2.2.  A TYPICAL MULTIPLE EFFECT  EVAPORATOR  SYSTEM
                             (SOURCE:   DOUGLASS,  Reference 4).

-------
                           7.2.!
rates, or inadequate supply of primary and secondary air can cause
large-scale releases of products of partial combustion.  Odorants
include hydrogen sulfide, mercaptans (especially methyl mercaptan),
dimethyl sulfide and other organic sulfides and dimethyl disulfide
and other disulfides.  Particulates include sodium sulfate, sodium
carbonate and carbon and may be emitted at about 170 pounds
per ton of air dried pulp produced by the mill.  These are
particles one micron in diameter or less.

a.  Controls
    Black Liquor Oxidation processes (5) are applied to prevent H S
    and other malodorous emissions from the evaporators.  In this
    process, sodium sulfide is oxidized to thiosulfates, which are
    relatively unreactive to the carbon dioxide produced in the recovery
    furnace.

    The Weak Black Liquor Oxidation Process (14 to 18 percent solids)
    reduces malodorous emission in the direct contact evaporator
    and in the multiple evaporators (Figure 7.2.3), and produces cleaner
    condensates.  A bubble tray or packed tower provides counter-current
    contact between the black liquor and air.  Entrained droplets are
    subsequently collected by cyclone.  The oxidized liquor is collected
    in a foam tank (retention time 5 minutes), where foam is dissipated at
    the surface by mechanical agitators or foam breakers.  The liquor is then
    pumped to the multiple-effect evaporators for further concentration.

    Strong Black Liquor Oxidation, a more recent development,    is
    applied after the multiple-effect evaporators.  The system, shown
    in Figure 7.2.4,  introduces compressed air by means of a sparger or
    airheader.  To reduce foaming, strong black liquor is sprayed into
    the top of the tank.  Cyclones are used to collect entrained

-------
             t
 A I  R

LOWER
OXIDIZE DHL I Q U O R
                                                         COURTESY  A. n.  IUNDBERC.IKC.
                Figure 7.2.3.   WEAK BLACK LIQUOR OXIDATION
                               (SOURCE:   KNUDSON, Reference 6.)

-------
STRONG
LIQUOR
                     Y C L 0 N E
                                          FOAM
                                        BREAKER
                                          t
                                                  I
                                                  I
                                              AIR    SPARGER
OXIDATION     TANK
                                                    A I R

                                             COMPRESSOR
                                                                    COURTESY: CHEMI CO
                      Figure 7.2.4.   STRONG BLACK LIQUOR OXIDATION
                                      (SOURCE:  KNUDSON,  Reference  6.)

-------
                        7.2.11
droplets.  A retention time of over 2 hours is required.  Effective-
ness depends, in part, on proper recovery furnace operation to avoid
excess hydrogen sulfide formation.

Polishing oxidation, instituted recently at a number of Northwest
mills, is a final oxidation stage immediately before the liquor is
fired.  It usually is conducted in comparatively small units, like
eductors or a small tank, for counteracting reversion of previously
oxidized liquor.

New recovery furnaces designed to minimize emission of malodors
evaporate the black liquor prior to burning in the recovery furnace
by use of combustion air rather than flue gas.  The hot flue
gases are used in a special heat exchanger to heat the combustion
air to 600°F.  The heated air is then used in a direct contact
evaporator to concentrate the black liquor prior to firing.  The
combustion air then carries any malodorous gases that are released
into the furnace when they are burned.

Another design modification is the direct-firing furnace.  The
direct-contact evaporator is replaced by a multiple-effect evaporator
system augmented with a forced circulation concentration evaporator
(Figure 7.2.5).  This system is capable of concentrating the black
liquor to about 64 percent solids.

Chemical oxidation, although not used on recovery furnaces but on
other sources indirectly helps to reduce recovery furnace emissions.
A sodium carbonate-bicarbonate scrubbing medium is used to
selectively remove hydrogen sulfide from flue gas and to recover
the sulfur.  Reduced furnace firing rates to prevent overloading
of the recovery furnace and utilization of black liquor oxidation
to reduce emissions from the direct-contact evaporator are also
desirable.  A corresponding loss of pulping production capacity
may result.

-------
  ADDITIONAL


  EVAPORATION
CONVENTIONAL
                                         EVAPORATOR
          SYSTEM
  Steam 50 PSIG
Product
 Tank
To Strong
                 Forced
              Circulation
              Concentrator









ng
or








^
ag




6




e




4%



, 5C
_G




A;

,

n
\—




F









C





1 	

rr u
Thv^pp
Pass
' 'Section
39%

/-N C9C/


G
                                   Two
                                   Pass
                                       35%
                                                       _o-
                                                 Soap
                                               Skimming
                                                 Tank
_G-
                               J
                            ,,  Weak
                              Black
                             Liquor
                              13%
                             Solids
                Figure 7.2.5.  MULTIPLE EFFECT EVAPORATOR SYSTEM
                               (SOURCE:  HENDRICKSON AND KOOGLER,  Reference  1.)

-------
                                7.2.13


        Electrostatic precipitators are applied to recovery furnaces.
        Precipitators operate at 97+ to 99+ percent control efficiency and
        emit in the range of a tenth of a grain per cubic foot.  Scrubbers
        are often additionally required to prevent precipitator snowing
        (discharge of agglomerated fumes not collected by the precipitator).
        The particle sizes emitted are easily collected by low efficiency
        scrubbers.

3.  Final Chemical Recovery
    The smelt flows in bulk from the recovery furnace to the smelt
    dissolving tank where it is dissolved in water and weak liquor to form
    green liquor, resulting in a violent release of large volumes of steam
    and particulates in mist or dust form (12 in Figure 7.2.1)..  These
    emissions contain highly caustic materials, particularly sodium
    hydroxide and sodium hydrosulfide.  Uncontrolled emissions may run about
    20 pounds/ton of pulp.

    The green liquor is pumped to a causticizer (13 in Figure 7.2.1) where it is
    treated with slaked lime (calcium hydroxide), clarified and returned to the
    digester.  Calcium carbonate precipitates from the causticizer solution
    as mud which is then filtered, washed and recycled to the lime
    kiln where it is calcined to produce lime (calcium oxide).  The
    uncontrolled lime kiln is a major source of particulates, and can emit
    more than 10 tons/day from some plants.   Hydrogen sulfide odors also
    may form from stripping of residual quantities of sodium sulfide carried
    over from the smelt by the carbon dioxide from the lime mud and kiln fuel.

    a.  Controls
        Fine mesh pads and fans are used to  improve performance of
        demisters and water showers.  Venturi, packed tower, and impingement
        type scrubbers are also used to control smelt tank emissions.

-------
                                   7.2.14
           Lime kiln emissions can be controlled by means  of Venturi
           Scrubbers.  Entrained dust particles are collected  in  cyclone
           collectors following the Venturi.   Impingement  scrubbers may
           also be used, but plugging of nozzles and orifices  is  frequently
           encountered.  New fluidized bed  lime kilns utilizing Venturi
           scrubbers for control of particulates are planned.

    4.   Other Mill Sources
        Steam and electricity required to operate the mill  are  supplied
        from  power boilers,  combination boilers, and hog  burners.

        Power plant boilers  may be fired by  coal, oil or  gas and the operation
        and pollution problems are similar to  other power plant operations,
        described in Chapter 6, Section II of  this manual.  Fly ash and
        sulfur dioxide emissions are the primary contaminants of interest.
        A combination boiler is usually used to burn bark and at least
        one other fuel.  The bark boiler or  hog fuel burner is  used  to burn
        waste wood materials, including saw  dust.  These  are usually of  the
        Dutch Oven type equipped with low set  spreader stokers. The charge is
        fed through  chutes.  Secondary air is  used  to control combustion,  and
        multiclones  are used to collect dust and fly ash  (see Chapter  6,  Section II)

C.   INSPECTION POINTS
    The control of Kraft emissions may be currently characterized  as a
    best technology  effort,  i.e., the air pollution problem is  inherent  in
    the Kraft process, is industry-wide, and control technology continues
    to  undergo research, development and testing.   In some  states, emission
    standards are set and compliance plans are negotiated specifically
    geared to the control of Kraft Mills.  Emission standards are  set  in  terms

-------
                                7.2.15
of pounds of pollutants allowed, for each specific equipment or process
unit, per ton of air dried unbleached pulp (Ib/ADT) processed by
the plant.  Malodorous gases are termed Total Reduced Sulfur or TRS,
and are distinguished from sulfur oxides.  Examples of emission standards
in effect for the State of Washington are shown in Table 7.2.3.

Specific inspection procedures, especially the citation of(violations,
will depend on the control program and policies of the air pollution
control agency involved.  In general, the inspector performs the following
functions:

     •  Reporting or verifying progress made by the mill in meeting
        compliance plan schedules.

     •  Assuring that day-to-day operation and maintenance practices
        serve to minimize pollution wherever possible.

     •  Reporting breakdown, shutdown or by-passing of process equipment
        and changes in pulp production schedules or cooking and chemical
        recovery procedures.

     •  Citing violations that are clearly flagrant in nature.

     •  Correlating public complaints with air quality measurements,
        emission rates and control practices.

The ability to distinguish between odors by character and process (e.g.,
direct contact evaporator, stock washer, terpentine recovery, etc.) is
particularly important in view of the variability in the emission constituents.
The inspector should be trained in the conduct of an odor survey (see
Chapter 6, Section V).

-------
                  Table  7.2.3.  SUMMARY OF KRAFT MILL EMISSION STANDARDS
                                FOR WASHINGTON STATE
SOURCE
Recovery furnace (s)
Recovery furnace (s)
Digesters and
multi-effect
evaporators
Lime kiln(s)
Smelt tank(s)
POLLUTANT
Total reduced sulfur
(TRS)
Particulates
Total reduced sulfur
Particulates
Particulates
EMISSION STANDARD
ppm, dry Ib/ton
70 and 2C
17.5 and 0.5°
A
Equivalent to reduction
achieved by thermal oxi-
dation in a lime kiln
1
1/2
COMPLIANCE DATE
d
July, 1975
July, 1975
July, 1972
July, 1975
July, 1972
a.  As defined in WAC 18-36:  for mills less than 200 ton/day, daily emissions equalling
    a 200 ton/day are allowed

b.  Includes hydrogen sulfide, mercaptans, and disulfides

c.  Whichever is the most restrictive

d.  Compliance date adjusted by the Board to meet individual mill requirements

                           (SOURCE:   WASHINGTON STATE,  Reference 2)

-------
                                7.2.17
1.  Environmental Observations
    The environment in the vicinity of Kraft mills should be periodically
    surveyed for odors and damage to vegetation and materials, and these
    findings correlated with public reactions in neighboring communities
    and with specific mill operations wherever possible.  Damage to
    residences, other structures, automobile surfaces, and other materials
    habitually located near the mill should also be investigated.

    The principal odors from a Kraft mill are characteristic in terms
    of their quality and pervasiveness.  Tables 7.2.4 and 7.2.5 illustrate odor
    thresholds and qualities by sulfur compound.     Other odors, such as
    terpenes and methanol, sufficiently differ from hydrogen sulfide and
    mercaptans, and are easily recognized.  These have the odor of terpentine
    or are "medicinal" in character, and tend to be localized around
    process equipment particularly stock washers and oxidation towers.
    The sulfides and mercaptans, in contrast, can be detected many miles
    from the plant.

    The inspector should note wherever possible wind direction, wind
    speed, humidity and atmospheric stability in his observations and
    he should develop a systematic procedure for patrolling and noting
    the location, quality and intensity of the odor.  Odors may be noted
    on an intensity scale or a scentometer may be used.  The inspector may
    organize a community odor panel consisting of carefully selected citizens
    who may help to establish the significance of day-to-day ground level
    variations within the normal odor intensity range.  An expert odor panel
    working under controlled, closed room conditions may also help to isolate
    the effect of posi
    Chapter 6, Odors.
the effect of possible changes in mill operations.      See Section V,
    Sulfur compounds (particularly tLS) can discolor and damage
    lead based paints and paints containing mercury-based fungi-
    cides and may accelerate tarnishing of silver and copper.  Dis-

-------
                                   7.2.18
             Table 7.2.4.  ODOR THRESHOLDS  OF  KRAFT  MILL
                           GASEOUS  SULFUR COMPOUNDS  IN AIR

                              ppm  (by  volume)
      Sulfur Dioxide     1.0-5.0   (a)

      Hydrogen  Sulfide   0.0085    (b_) ,   0.0047   (a).    0.0009   (d.)

      Methyl Mercaptan   0.0021    (a.),   0.040    (c) ,    0.0006   (d)

      Dimethyl  Sulfide   0.0001    (a.),   0.0036   (c_) ,    0.0003   (d.)


(a)   Leonardis, G., Kendall, D.,  Barnard,  N.,  "Odor  Threshold Determinators
     of  53 Odorant Chemicals," J.A.P.C.A.  (2),  91-5,  1969.

(b)   Lederlof,  R., Edfor, M. L.,  Friberg,  L.,  Lindvall,  T. , Nordisk Hygenish
     Tidskrfit  46, 51,  1965.

(c)   Young, F.  A., Adams, D. R.,  Sullivan,  Dobbs,  "The Relationship between
     Environmental-Demographic Variables and Olfactory Detection and Objection-
     ability Thresholds" to be published in Perception and  Psychophysics.

(d)   "Handbook  of Air Pollution," U.S.DHEW, PHS,  Bureau of  State Services,
     Division of Air Pollution, Cincinnati, Ohio.

               (SOURCE: HENDRICKSON AND KOOGLER,  Reference 1.)

-------
                     7.2.19
      Table 7.2.5.  CHARACTERISTICS OF KRAFT MILL
                    GASEOUS SULFUR COMPOUNDS
Compound
Sulfur Dioxide
Hydrogen Sulfide
Methyl Mercaptan
Dimethyl Sulfide
Characteristic
Odor
strong,
suffocating
rotten eggs
rotten cabbage
vegetable
sulfide
(SOURCE:   HENDRICKSON AND KOOGLER,  Reference 1.)

-------
                               7.2.20
    coloration usually  takes  the form of browning  or blackening  of  materials
    and  is  enhanced  if  the  surfaces have been moistened  or weathered,
    depending on  the lead content.  Fungi will  also darken unprotected  paints,
    so the  inspector should,  in doubtful cases, have the cause of damage
    verified by experts.  Vegetation damage also may result  from sulfur
    dioxide emitted  from boiler equipment, as well as  from hydrogen sulfide.

    Deposits of particulates  may result from the fallout of  saltcake particles,
    fly  ash, soot, burned particles and lime, which are  usually  confined to
    within  1/4 to 2  miles from the plant.  Some of the fallout is of a
    comparatively caustic nature and can damage vegetation,  materials and
    painted surfaces particularly on vehicles located  near the plant.   Particles
    may  be  sampled and  taken  to the laboratory  for analysis  to help identify
    the  process sources responsible.  Particles high in  calcium  are generally
    emitted from  the lime kiln; particles high  in  sodium may originate  from
    the  recovery  furnace and  smelt tank; charred or insoluble material
    originates from  hog burning equipment.  Sodium salts, which  tend to be more
    volatile than other particulates, may be the principal offender.  Particulates
    which fall out as snow  may be due to flocculation  of particles  in the
    electrostatic  precipitator.  These consist of fluffy aggregates  up  to  1
    millimeter in  diameter.     The  larger aggregates are  largely  responsibl
    for damage to  paint  and vegetation.

2.   Observation of Exterior of Mill
    Points of  emissions  in a Kraft mill  include  stacks and vents at  roof
    level, the recesses  between plant structures, inside the  structures
    and ground level.  The obvious emissions are the steam plumes  and
    mists, particularly  from the recovery furnace.  These  can be voluminous
    and may travel over  great distances  and altitudes.  The steam  and
    vapor  emissions make it difficult to isolate and read  the dry  portions
    of the plumes.  Long plumes, however, are always suspect  in view of
    the relatively rapid dissipation of  steam.   Reading visible emissions,
    while  taking into  account the dry and liquid contaminants'is tenable,

-------
                               7.2.21
    but the practice will depend on the policy of the air pollution
    control agency involved.

    The inspector should become familiar with the quality and intensities
    of odors and the visual character of mill emissions as they vary
    through the day and with weather conditions.   Where abnormal conditions
    occur, source testing should be requested.  Where an unusual number  of
    public complaints are reported, the possibility of odors bfeing released
    with intermittent emissions from starting up and shutting down of
    equipment, opening of digesters, condenser or heat recovery system
    failures, overloading of recovery furnace, faulty oxidation tower
    operations, etc., should be investigated.  Vents on bleaching and  other
    mill operations, also, should not be ignored, as highly toxic chlorine
    gas can be accidentially released.

3.  Inspection of the Plant Interior
    a.  The Interview
        In Kraft Mills, the interview is usually conducted with staff  that
        has been permanently assigned to the air pollution problems of the
        plant.  The interview should be primarily directed at ascertaining
        factors which affect process emissions, control progress and
        changes in operating procedures which cannot be noted during the
        physical inspection.   Recording charts, logs and charts relating to
        process performance and emissions can be examined in the office
        with the air pollution staff of the mill.  The inspector should
        clearly establish normal operating procedures in order to be
        able to identify abnormal or changing conditions.  A procedure
        should be adopted and practiced by which the mill reports upsets and
        outages to the enforcement agency.  Scheduled maintenance,
        especially if it involves taking control equipment out of operation,
        should be announced in advance.

-------
                       7.2.22
Information obtained by interview should include:
•   Type of Wood Used:   resinous content,  softwood,  hardwood
    extent of use of saw dust,  etc.   The methyl group contained
    in certain sulfur based emissions derive from the methoxyl
    content of woods.  Hardwoods contain more methoxyls than
    softwoods, and have greater process odor material.
    Resinous woods can cause foaming in oxidation systems.
•   Sulfidity.  Malodor from the major sources of pollution in the
    recovery operation is generally  in direct proportion to the
    sulfide content of the white liquor, other conditions being
    equal.  The sulfidity may vary from 12 to 35 percent.
•   Cooking Variables.   Malodorous emissions can be  increased when
    cooks are shortened and pressure and temperatures are increased.
•   Pulping capacity of the mill should be determined in terms of
    tons of unbleached air dried pulp.  The inspector should become
    familiar with variations in pulping capacity.  Substantial
    increases in pulping output may  cause  the capacities of existing
    process equipment to be exceeded, including overloading of the
    recovery furnace, and excessive  emissions from power plant and
    other supporting equipment.
•   Plant program for monitoring emissions.  The inspector should
    be familiar with the mill schedule for conducting source
    testing and maintenance of  continuous  monitors,  such as the
    titrator, discussed later.   It is extremely important that the
    equipment be kept in good working order.  The inspector should
    clearly establish any modifications made by the  plant to the
    instrumentation, and should assure that a formal procedure for
    maintaining the accuracy of continuous monitors be adopted.

-------
                           7.2.23
    •   Emission inventories, negotiated compliance plans and permits.
        The inspector should have available with him information
        concerning the equipment and emission inventories of the plant
        to determine if significant changes have been made in any of
        the major sources that will affect emissions and odors.  It is
        desirable to compare inventories, process flow diagrams, and
        plot plans on file with existing conditions.  This can be
        accomplished either before or after the tour through the plant.
        The black liquor flow, the exact points of emission and firing
        rates to the recovery furnace, the lime kiln and the power
        boilers and hog burners, in particular, should be noted.

b.  The Physical Inspection
    The inspection should be organized around two closed systems:  (1)
    the black liquor system, including the digesters, relief valves,
    accumulators, oxidation towers, direct contact evaporator, recovery
    furnace, and smelt tank, and (2) the lime kiln and the lime recycling
    system.  The bleaching plant should also be inspected, particularly
    the brown stock washer where water vapor and malodorous contaminants
    may be collected by hood and discharged to the atmosphere.

    (1)  Black Liquor System
         In the black liquor system, the inspector should become
         familiar with the vents, valves and condensers, the types of
         condensers, and associated odors and emissions.  The design,
         condition and operation of the oxidation towers should be
         noted, as these bear on the release of odors from the furnace
         and the evaporators.  If the foam produced in the towers is
         excessive, the foam breakers may become overloaded, causing
         them to kickout and allow foam to spill out of the tower.
         Systems in which air and black liquor flow concurrently
         generally cause less foaming than countercurrent systems.

-------
                       7.2.24
     Spills,  indications  of poor maintenance and  low  level  odors
     should be noted at this point.  The  foaming  action  in
     oxidation towers can cause operational and maintenance
     problems especially  from  the use of  certain  softwoods  such
     as  pine  and  from silt.  Problems include corrosion  of  the
     aluminum alloy tank  construction due to the  alkaline
     atmosphere.  Also an increase in overall plant pulping
     capacity can cause a decrease in the oxidation rate and
     hence reformation of sulfides.

(2)   TRS Monitors
     The operation of the instrument used to monitor  total  reduced
     sulfur should be inspected.  A recommended procedure for TRS
     measurement  is the use of an electrolytic titrator  monitor.
     This instrument is based  on coulometric principles.  '  '  '
     Readout  is based on  cell voltage which varies with  the
     consumption  of bromine in the electrolyte as it  reacts with
     the reduced  sulfur compounds (see Figure 7.2.6).

     Sources  to which the titrator are applied typically include
     recovery furnaces and the lime kiln  or a gas-fired  furnace
     if  used  for  disposal of noncondensibles.  Particulates are
     typically measured at the recovery furnace and lime kiln and
     smelt tank,  by means of filtration followed  by adsorption in
     a water  bubbler on a batch basis, or by use  of other approved
     continuous methods.

     The recorder is usually located in the instrument room
     adjacent to  the furnace.  The location of the probe in the
     duct work should be  checked; it is usually located  after
     the direct contact evaporator.  Titrators are temperamental

-------
                                  Recorder
                                 Instrument
Flue
Gas
                                                               Pump
                                                         Micro _L
                                                       Metering V
                                                        Valve  V
                                              N>


                                              Ui
         PRE
       SCRUBBER
Titration  Dessicant  Flow
  Cell                Meter
 Figure 7.2.6.  CONTINUOUS STACK SAMPLER FOR TRS COMPOUNDS
                (SOURCE:  KNUDSON, Reference 10).

-------
                       7.2.26
     instruments, and are usually modified at the plant to
     improve sturdiness and reliability.  Empirical readings on
     these recorders measure up to about 1200 ppm, with a
     10 percent  loss of accuracy around the 1000 ppm point.  Peaks
     on strip  charts may be due to soot blowing, which may occur
     on a  two-hour  cycle, or to upsets in air ratios.  The
     inspector should check for tight sampling points to assure
     absence of  sample dilution.

(3)   Recovery  Furnace
     The inspector  should become familiar with the specific design
     and operation  of the recovery furnace in the plants to which
     he is assigned.  Many factors enter into achieving optimum
     combustion  in  the furnace from an air pollution standpoint
     including the  firing rate, secondary air, percent excess
     oxygen in the  flue gas, black liquor spray droplet size and
     time  and  turbulence.  Factors which may be noted on inspection
     are excess  air and secondary air, and liquor firing rates.  In
     the recovery furnace control room the following items should
     be checked  on  the operator's log sheet or by instrument
     readings:
          •  Sulfidity of white liquor.
          •  Percent solids of black liquor.
          •  Sodium sulfide content of black liquor in and out of
            black  liquor oxidation unit.
          •  Voltage and amperage readings of the electrostatic
            precipitator.
     The following  lime kiln operational data should be obtained
     from  the  log sheet:

-------
                       7.2.27
          •   Sodium content  of washed  cake,  taken once per  day or
             shift.
          •   Scrubber water  flow  rate  and  source, by  flow meter
             reading, once an hour.
          •   Scrubber pressure drop, by manometer.

     The direct  reading  oxygen recording instrument should  also be
     checked.  Readings  below 3 percent may  indicate  furnace over-
     loading.  Oxygen recording instruments  will usually be located
     near the titrator recorder.

     A furnace operating log may  also  be noted  in the recovery
     furnace area which  records the  black  liquor firing rates as
     well as steam output, usually every hour.  This  information
     should  be correlated with recovery furnace emissions so that
     overloads can clearly be recognized from this performance data.

     The inspector should check to see whether  the air ports in
     the recovery furnace are regularly routed  to prevent plugging
     and that excess oxygen  and proper operating temperature
     (usually around 1100°F) are  maintained  in  the upper oxidation
     zone of the furnace.  The shutting down of secondary air for
     any reason  can cause an increase  in emissions.   The inspector
     should  recognize, however, that steps may  have to be taken
     on occasion to prevent  dangerous  situations, such as furnace
     or digester explosions.

(4)   Lime Kiln System
     The lime kiln system should  be  checked  for both  particulates
     and odors.   The make-up rate for  saltcake  (Ibs./saltcake
     added per ton pulp  produced) indicates  how much  of the

-------
                   7.2.28
sodium and saltcake is being lost to the atmosphere and to
waste water reuse and/or treatment.   A loss of 100 Ibs.
saltcake/ton pulp may be reasonable, but the proper figure
must be established with each plant.  This information will
be found on the recovery furnace log sheet.  Hydrogen sulfide
can form> particularly in long kilns, due to reactions.of carbon
dioxide with sodium sulfide in the carbonate sludge, and to
the introduction of carbonate at the cooler end of the kiln.
In some plants noncondensibles from the hot water accumulators
are carried to the lime kiln for incineration.

-------
                                      7.2.29
                                   REFERENCES


 1.  Hendrickson, E. R.,  J.  E.  Roberson,  and J.  B.  Koogler.   Control of
     Atmospheric Emissions in the Wood Pulping Industry,  Vol.  1-3,  Final Report,
     Contract No. CPA 22-69-18.  March 15,  1970.

 2.  A Report to the Washington Air Pollution  Control Board  Prepared in
     Conjunction with Rules  and Regulations for Kraft Pulp Mills  in Washington
     Office of Air Quality Control.  Washington State Department  of Health,
     Seattle, Washington.  May, 1969.  [Figure 7.2.1 based on Figure 1 of
     reference 4, p. 42.]

 3.  Hough, G. W., and L. V. Gross.  Air Emission Control in a Modern Pulp  and
     Paper Mill.  Portland,  Oregon, Fall Pacific Coast Division Meeting.
     Paper Industry Management Association.  December 5-7, 1968.

 4.  Douglass, I. B.  The Chemistry of Pollutant Formation in Kraft Pulping.
     In:  Proceedings of the International Conference on  Atmospheric Emissions
     from Sulfate Pulping, E. R. Hendrickson (ed.).  PHS, National  Council
     for Stream Improvement.  University of Florida, April 28,  1966.

 5.  Kenline, P. A., and J.  M.  Hales.  Air Pollution and  the Kraft  Pulping
     Industry, an Annotated Bibliography.  Environmental  Health Series.
     DREW, PHS, November 1963.

 6.  Knudson, J. C.  Air Pollution Controls to Meet Washington State Kraft Mill
     Standards.  Department of Ecology, Redmond,  State of Washington.  Spokane,
     Washington, International Section, Air Pollution Control Association,
     November 16-18, 1970.

 7.  Major, W. D.  Variations in Pulping Practices  which  may Affect Emissions.
     In:  Proceedings of the International Conference on  Atmospheric Emissions
     from Sulfate Pulping, E. R. Hendrickson (ed.).  PHS, National  Council  for
     Stream Improvement.   University of Florida.  April 28,  1966.

 8.  Pulp and Paper Titrator, Model 400,  Installation and Operation Manual.
     Barton ITT, Process  Instruments and Controls.   Monterey Park,  California.

 9.  Barton Xitrators, Training Manual, Model  400,  Installation and Operation
     Manual.  Barton ITT, Process Instrument and Controls.   Monterey Park,
     California.

10.  Knudson, J. C.  Air  Pollution Controls to Meet Washington State Kraft  Mill
     Standards.  Department of Ecology, Redmond,  State of Washington.  Spokane,
     Washington, International Section, Air Pollution Control Association,
     November 16-18, 1970.

-------
                                       7.2.30
11.   Ayer,  C.   A Report  on the  Kraft  Pulping  Industry's  Progress  in Complying
     with the  Emission Regulations  of April,  1969.   Oregon Department of
     Environmental Quality (unpublished).

-------
                                    7.3.1
                           III.  ANIMAL RENDERING

A.  DESCRIPTION OF SOURCE
    The rendering of animal matter falls into two categories:   the salvaging
    of edible products and the reclamation of inedible products.   Similar
    types of processing equipment and air pollution problems are  involved
    in both activities.  This section is primarily concerned with inedible
    product recovery.

    As unpleasant as rendering operations are, they serve a necessary as well
    as a beneficial community function.  They provide a method for disposing
    of dead animals, meat cutting scraps and poultry dressing  scraps which
    would otherwise present a health hazard.

    Carcasses, meat bone scraps and offal are delivered to the rendering plant.
    Preparation of this matter usually consists of skinning and dissecting the
    dead animal into segments small enough to be fed to a hogger.   Blood and
    feathers can also be fed to the process.

    Depending on the feedstock, the processing will yield tallow  from meat
    scraps and offal, and high protein meal for poultry feed from blood  and
    feathers.  Table 7.3.1 describes typical yields of feedstock  from
    slaughterhouse operations.      The table demonstrates the  potential  quantities
    of materials that must be treated in communities where these  operations
    are located.

B.  PROCESS DESCRIPTION
    Odors present the principal air pollution problem from rendering, drying
    and refining of animal matter.  Dust from blood drying, meal  grinding and

-------
                           7.3.2
Table 7.3.1.  INEDIBLE REDUCTION PROCESS RAW MATERIALS
             ORIGINATING FROM SLAUGHTERHOUSES
Source, Ib live wt
Steers, 1,000
Cows
Calves , 200
Sheep , 80
Hogs, 200
Inedible offal and bone,
Ib/head
90 to 100
110 to 125
15 to 20
8 to 10
10 to 15
Blood,
Ib/head
55
55
5
4
7
   (SOURCE:   AIR POLLUTION ENGINEERING MANUAL,  Reference 1.)

-------
                                 7.3.3
handling are secondary problems.  Malodors emanate from most animal matter
operations, especially from rendering cookers.  Table 7.3.2 describes
emission rates from the various equipment units and systems found in
rendering operations.  Table 7.3.3 quantifies odor threshold values for the
substances associated with the breakdown of animal fat.,  Some odor threshold
concentrations are in the range of 10 parts per billion.

The reduction of animal matter is carried out in captive plants as an
integral part of the meat packing industry or in separate scavenger plants.
A typical operation is shown in Figure 7.3.1 where skinned carcasses, bone and
meat scraps are loaded into a dump pit, ground in a hogger and screw
conveyed to a steam-heated cooker.  Digestion takes place over a 2 to 4
hour cooking cycle on a batch or a continuous basis.  The water vapor is
released to the vent system and the residual hot solids are dumped into a
percolator which allows the free tallow to drain to the settling tank.  The
cracklings, which still contain a significant quantity of tallow, are
conveyed to a steam-heated press where the remaining tallow is expelled and
drained to a settling tank.  The remaining solids are conveyed to a surge
bin or holding vessel and then ground into meal.  Final tallow extraction
processes can be aided by the use of soda ash or sulfuric acid to enhance
phase separation.  Solvent extraction techniques using hexane in a vapor
tight system, with venting of the solvent vapors to condensers, can be
used for extremely high quality control.  Air blowing of the tallow
provides for additional removal of remaining water.

Equipment configurations differ considerably among plants.  Modern plants
consist of continuous flow systems.  The design of these systems will be
largely based on capacities, types and specifications of products, and the
cooking and drying processes employed.  Typical processes include the following:

-------
           Table 7.3.2.     ODOR CONCENTRATIONS AND  EMISSION RATES
                            FROM INEDIBLE REDUCTION  PROCESSES
Source
Rendering cooker,
dry-batch type
Blood cooker,
dry-batch type
Feather drier,
steamtubec
Blood spray
drierc'd
Grease-drying tank,
air blowing
156T
170°F
225°F
Odor concentration,
odor unite/scf
Range
5, 000 to
500, 000
10, 000 to
1 million
600 to
35, 000
600 to
1, 000





Typical average
50, 000

100, 000

2,000

800



4,500
15,000
60, 000
Typical moisture
content of
feeding stocks, %
50

90

50

60

< 5




Exhaust products,
scf/ton of feeda
20, 000

38, 000

77, 000

100, 000

100 scfm
per tank



Odor emission
rate, odor unit/
ton of feed
1, 000 x 106

3, 800 x 106

153 x 106

80 x 106






aAssuming 5 percent moisture in solid products of system.
''Noncondensable gases are neglected in determining emission rates.
cExhaust gases are assumed to contain 25 percent moisture.
dBlood handled in spray drier before any appreciable decomposition occurs.
     Definition see Odor  Detection and  Evaluation,  Chapter 6, Section 7.
                (SOURCE:  AIR POLLUTION  ENGINEERING MANUAL, Reference 1.)

-------
                                    7.3.5
Table  7.3.3.   ODOR THRESHOLD CONCENTRATIONS OF SELECTED RENDERING COMPOUNDS
Substance
Acrolcln
Ally! amine
Ally) mercaptan3
Ammonia
Dibutyl sulf.de
Ethyl mercapldna
Hydrogen sulfide
Oxidized oiU
Skatole
Sulfur dioxide
Foi mula
CH2:CI-1 CHO
CH2:CIi- CH2- NH2
CI12:CH- CH2-SH
(C4H,,)2S
C2II5 SH
II2S
C.H.NH
so2
Threshold concentration,
me/liter
0.038
0. 067
0. 00005
0. 037
0. 0011
0. 00019
0. 0011
0. 0011
0.0012
0. 009
ppm by volume
16
28
0.016
52
0. 180
0. 072
0.770
0.220
3. 3
                            obtained with material of varying purity.
         (SOURCE:  AIR POLLUTION ENGINEERING MANUAL   Reference 1.)

-------
                                  7.3.6
                   EXHAUST VAPORS TO CONTROL EQUIPMENT



HOGGER

A
COOKER
NO. 1

*
PERCOLATOR
HO. 1


1
COOKER
NO. 2

t
PERCOLATOR
NO. 2


1
COOKER
NO. 3

t
PERCOLATOR
NO. 3
                                                              FINISH
                                                              TALLOW
                                                          SETTLING
                                                          TANK
                                                                          MEAL
                                                                       GRINDER
                                                                        SURGE
                                                                        SIN
                                                              TALLOW
                 CRACKLINGS TROUGH KITH SCRE* CONVEYOR
                                                                     EXPELLER
                                                                     PRESS
                                                    DRAINED CRACKLINGS
Figure 7.3.1.   AN INTEGRATED  DRY RENDERING  PLANT  EQUIPPED WITH
                 BATCH  COOKERS, PERCOLATORS,  A CRACKLINGS  PRESS,
                 AND A  TALLOW-SETTLING TANK.   (SOURCE:  AIR POLLUTION
                 ENGINEERING MANUAL,  Reference 1.)

-------
                                 7.3.7
1.  Dry Rendering Processes
    In dry process rendering,  animal matter is fed into steam
    jacketed cookers to separate the tallow and solids by removing the
    moisture from the pulpy mass formed during cooking.  Cookers are
    operated at, above, or below atmospheric pressure.  Cooking under
    pressure is conducted at 50 psig and 300°F for 3/4 to 4 hours,
    depending on the type of material to be digested.   Refractory stocks
    such as bones, hooves, hide and hair require relatively greater
    temperatures and pressures than organs and tissues.

    After pressures are reduced the batch is further cooked at atmospheric
    pressure or dried to remove additional moisture and to complete
    separation of tallow from solids.  Emission rates  of odorous contaminants
    are a function of the rate of moisture evaporation.  The maximum
    emissions from atmospheric cookers occur in the initial portion of the
    cook, while in pressure cookers the moisture evaporation rate and
    emissions proceeds as the temperature builds up.
    When cooking is performed under vacuum,  moisture is removed at
    comparatively lower temperatures to reduce product degradation.   A
    precondenser, steam ejector and aftercondenser are used to produce
    high quality tallow, but incomplete cooking of bones,  hair and other
    refractory materials may occur.  Moisture evaporation and emission
    rates are a function of the rate at which the steam generated can be
    removed.

    The composition of the material usually  charged and the tallow (or
    grease),  solid-, and moisture content are shown in Table 7.3,4.  The
    moisture  content which carries the malodorous contaminants must be
    taken into account in the design of air  pollution control equipment
    which should include surge tanks, condensers and hot wells.

-------
                             7.3.8
Table 7.3.4.  COMPOSITION OF TYPICAL INEDIBLE RAW MATERIALS
             CHARGED TO REDUCTION PROCESSES
Source
Packing house offal and bone
Steers
Cows
Calves
Sheep
Hogs
Dead stock (whole animals)
Cattle
Cows
Sheep
Hogs
Blood
Feathers (from poultry houses)
Butcher shop scrap
Tallow or grease,
wt %

15 to 20
10 to 20
8 to 12
25 to 35
15 to 20

12
8 to 10
22
30


37
Solids ,
wt %

30 to 35
20 to 30
20 to 25
20 to 25
18 to 25

25
23
25
25 to 30
12 to 13
20 to 30
25
Moisture,
wt %

45 to 55
50 to 70
60 to 70
45 to 55
55 to 67

63
67 to 69
53
40 to 45
87 to 88
70 to 80
38
   (SOURCE:  AIR POLLUTION ENGINEERING MANUAL. Reference 1.)

-------
                                7.3.9
    An example of a completely mechanized system using steam jacketed screw
    conveyors to facilitate handling in an almost completely enclosed system
    is shown in Figure 7.3.2.   This is a continuous cooking system in which
    the tallow and steam are continuously tapped from the charge at various
    points.   The charge is slurried with recycled hot tallow prior to
    cooking.

2.   Wet Processes
    In the wet process, the oldest of the animal reduction methods, live
    steam is introduced into a closed vessel at pressures of about 60 psig
    and 300°F.  After separation of the materials to water, tallow and
    solids, the pressure is released causing some flashing of steam.   Cooking
    continues at atmospheric pressure until the phase separation is completed.
    Since the resulting water contains a relatively high percentage of
    solids, 6 to 7 percent, further evaporation to recover these solids may
    be desirable.  This process finds application in the rendering of whole
    animals but its use is being superceded by dry processing wherever
    possible.  Vapor emission rates are lower than from dry cookers, as the
    bulk of the moisture is removed in the form of water.

3.   Feather Cookers
    Blood and feather dryers are the same type of equipment as meat and
    bone cookers.  The charging procedures  are different, however.  Feathers
    must be charged wet and loose.   The charging opening should be maintained
    under a slight vacuum and vented to the afterburner by-passing the condenser.

    Feathers contain mostly protein and virtually no fat and are
    processed to produce meal only.  This is accomplished by pressure
    in a dry cooker.  Moisture is removed at ambient pressure in the cooker or

-------
                                           7.3.10
                                 S7EAB SUPPU  -
                          IAIER SUPPLY


                   BAROMETRIC CONDENSER .

                        DISINTEGRATOR
 STEAM SUPPLY


-AIR AND NON CONDEHSIBIE EIECTOR
                                                                     SLUDGE HOPPER
IRAdP «Et»l OISCHASGE
              »AIE» OISCHAUCE
          Figure 7.3.2.   A CONTINUOUS, VACUUM RENDERING SYSTEM EMPLOYING
                           TALLOW RECYCLING  (CARVER-GREENFIELD PROCESS)
                           (SOURCE:  AIR POLLUTION ENGINEERING MANUAL,
                            Reference  1.)

-------
                                    7.3.11
       drier.   If an air drier is used, the material is transferred to it in
       a wet condition.  Odor concentrations are generally less and more
       variable than from rendering cookers and will depend on freshness of
       the feedstock and completeness of previous cooking.

   4.  Blood Drying
       Blood also contains essentially no fat and is used primarily to produce
       meal and glue.  Packing houses, where blood drying is mostly performed,
       usually utilize a continuous process starting at the killing room which
       is constructed to drain the blood to holding tanks and to the cookers.
       Most processing is accomplished in dry rendering cookers.  Dust
       emissions can occur during the final portions of the drying cycle.
       Tubular evaporators are sometimes used to reduce initial water content
       to about 65% prior to transfer of material to the dry rendering cooker.
       Spray drying is sometimes used to produce plywood glue.  In this air
       drying process high quantities of dust-entrained exhaust gases are
       produced.  Blood can be concentrated in evaporators prior to spray
       drying.  Blood drying can be very odorous if the blood has insufficiently
       aged before processing.

C.  AIR POLLUTION CONTROLS
    Controls for the reduction or elimination of odors from inedible animal
    matter processing are usually condensation, high temperature incinera-
    tion, scrubbing, carbon adsorption, or a combination of these methods.
    The principal odor-causing constitutents in the steam exhausted from
    reduction operations are noncondensible.

-------
                                7.3.12
    The residuals  from condensing the  large volumes  of steam should
    either be incinerated,  preferably  in a waste heat recovery device at
    1200°F for no  less than 0.3 seconds  or adsorbed  in an activated carbon
    filter.   The use of carbon filters presents  a problem of regeneration.
    The adsorbed material must be stripped from  the  carbon.   This process
    cannot be vented directly to the atmosphere  since it woul,d have the same
    effect as venting the cooking steam  to the atmosphere.   Therefore,  high
    temperature incineration is necessary to burn the material stripped
    from the carbon.   This  can be as costly as incineration  directly after
    condensation.

    An operating hazard for vapor collection systems  occurs  when the vapor
    exhaust line becomes plugged with  solid material  which  can be carried
    over from the  cooking operation (Figure 7.3.3).   The system pressure
    will build until the material causing the blockage is set free.  Unless
    there is a surge tank or interceptor in the  system, the  solid matter
    could carry over into the condenser  or even  the  incinerator causing
    malfunctions of the odor control equipment.   Therefore,  a good design
    calls for the  inclusion of an interceptor vessel  in the  system.
    Table 7.3.5 describes efficiencies of various odor removal systems.

    Because of these difficulties, afterburners  and  condensers should be used
    instead of boiler fireboxes to dispose of vapors.

D.  INSPECTION POINTS
    Due to the severity of  the odor problem, rendering plants usually are
    covered by public nuisance and permit system regulations.  The degree
    of control and types of control systems used will depend on whether the
    objective is to materially alleviate the odor problem,  or to
    virtually eliminate it  altogether.  If the objective is  to alleviate
    the odor problem, then  the use of  scrubbers  as the ultimate control
    device may be  acceptable in some regions. If the objective is to

-------
                                 7.3.13
eliminate the odor, then the use of an afterburner, or combination after-
burner and scrubber will be mandatory.

The inspector's primary function with respect to controlled plants will be
to assure that (1) hooding and ventilation systems and control systems are
operated and maintained to meet intended control objectives, (2) feedstocks
are rapidly processed, and (3) effective plant sanitation is practiced.
Control objectives may be stated in terms of design performance
standards, or odor concentration units.  The latter may be defined as any
odor or mixture of odors that, when dispersed in one cubic foot of odor-free-
air, produces a median threshold odor detection response as measured by
ASTM D 1391-57 (see Section V, Chapter 6).  Table 7.3.2 shows odor
concentrations and emission rates from typical process sources.

1.  Environmental Observations
    Objectionable odors from rendering plants travel long distances and
    are readily reported by citizens.  For any rendering source a complaint
    pattern defined by prevailing weather conditions and air flow will
    emerge.  This pattern will serve as a baseline for "monitoring" the
    emissions of the plant which can be correlated with attempts to control
    the odors, and with operational and maintenance problems and practices
    at the plant.  If the number of complaints increase above normal, if new
    complaints are identified, or odors are reported at new or more distant
    locations, then breakdown, negligence or other unusual conditions
    should be suspected.  The inspector's objective will be to
    reduce or eliminate the incidence of complaints by the corresponding
    degree of odor reduction at the plant.

-------
                              7.3.14
Figure 7.3.3.   A CONDENSER-AFTERBURNER CONTROL SYSTEM WITH
               AN INTERCEPTOR LOCATED  BETWEEN THE RENDERING
               COOKER AND CONDENSER (95% CONDENSIBLE)
               (SOURCE:   AIR POLLUTION ENGINEERING MANUAL,
                Reference 1.)

-------
   Table 7.3,5.  ODOR REMOVAL EFFICIENCIES OF  CONDENSERS OR AFTERBURNERS,
                 OR BOTH,  VENTING A TYPICAL DRY RENDERING COOKER3
Odors Irom cookers
Concentration,
odor units/scf
50, 000











Emission rate,
odor units /min
25, 000, 000












Condenser
type
None

Surface


Surface

Contact


Contact


Condensate
•F
__

80


140

80


140


Afterburner
•F
1.200

None


1, 200

None


1,200


Concentration,
odors
units /scf
100 to 150
(Mode 120)
100, 000 to
1 0 million
(Mode 500, 000)
50 to 100
(Mode 75)
2, 000 to
20,000
(Mode 10. 000)
20 to 50
(Mode 25)
Modal emission
rate, odor
units/mm
90,000

12, 500, 000


6,000

250, 000


2,000


Odor removal
efficiency,
%
99.40

50


99.93

99


99. 99
	 .
                                                                                                    U)

                                                                                                    M
                                                                                                    Ln
Based on a hypothetical cooker that emits 500 scfm of vapor containing 5 percent noncondens able gases.
             (SOURCE:  AIR POLLUTION ENGINEERING MANUAL, Reference  2.)

-------
                                7.3.16
    Knowledge of  the citizen  response pattern  and  the  specific  operations
    of rendering  plants  is  very  important  in tracking  down  the  specific
    plant sources responsible, particularly where  many rendering  plants
    are concentrated in  a given  area.  Procedures  for  tracking  odors  and
    sampling  malodorous  gases are described in Chapter 6, Section V.

2.   Observation of the Exterior  of Plant
    The structure and layout  of  individual facilities  will  differ.  Older
    plants may tend to be less efficient and more  improvisational, with
    many of the transfer and  storage operations conducted outdoors
    or in partially open buildings.  The ground surfaces may  be unpaved
    or cracked and hence difficult to clean and to maintain.  Newer plants
    should include enclosable structures,  washable surfaces,  the  use  of
    stainless steel materials, and plant and work  layout features which
    minimize  open storage,  treatment and transfer  of feedstocks.  All
    grounds should be paved with Portland  cement concrete (not  asphalt)
    for easier and more  complete cleaning.  Pit areas  should  be kept  clean
    and covered.

    Observation of the exterior  of the plant will  provide much  information
    on the operation of  the possible emissions from scrubbers,  afterburners,
    and roof  vents should be  checked.  Steam emissions may be noted,  as  well
    as misting of scrubbers.  Dry visible  emissions are uncommon, except for
    possible  dusts emitted  from  grinding and other dry material handling procedures
    which do  not  as a rule  extend beyond the plant boundaries.  The plant
    should be observed periodically, with  observations made  during evenings,
    as well as days, to  establish whether  abnormal practices  are  occurring.
    The practice  of using 55  gallon drums  for  storage  of waste  materials
    outdoors  which have  not been properly  cleaned  should be  discouraged.

-------
                               7.3.17
3.   Inspection of the Interior of the Plant
    As in all processes which emit odors, gases,  and vapors it is important
    that a complete source inventory be made and  that the inspector become
    familiar with the processes and operations that produce the most odors,
    so that a baseline of pollution control performance can be established.
    The inspector should attempt to distinguish between housekeeping and
    process odors and odors which may result from improperly controlled
    rendering equipment.  The latter are generally dryer and mustier in
    quality than the former.

    a.  Interview with Plant Management
        The inspector should attempt to obtain information on the following:

         (1)   Inventory of  feedstocks.   Records should  be  examined or
              estimates made of the quantity and.  type of  feedstocks  re-
              ceived especially with respect to bone, meat  scraps,
              carcasses,  blood,  feathers,  stomachs  and  intestines.
              Some feedstocks such  as  intestines  and blood  are more  odorous
              than others.   Bone and meat  scraps  from slaughterhouses and
              butcher  shops  tend to  be  less  odorous.  Captive rendering
              operations, because they  are close  to fresh  supplies of
              animal wastes,  usually present less of an odor  problem than
              do  independent Tenderers.

              It  is  important to establish periods when feedstocks are
              backlogged.  This  can be  determined from  the plant  operating
              schedule.   Odors  will substantially increase when backlogs
              remain over weekends  and  holiday  shutdown periods,
              particularly  in warm  weather.   Plants should  be observed  on
              Monday mornings.

-------
                           7.3.18
    (2)  Plant Sanitation Practices.   The inspector should determine
         if clean-up procedures are regularly practiced as part of
         the work schedule.   It is important that work tables,  drums,
         bins, ground surfaces, and sidings be hosed,  scrubbed  or
         otherwise cleaned and that contaminated water not be allowed
         to stagnate.

b.  The Physical Inspection
    The inspector should inspect all  facilities and equipment and
    should observe the complete operating cycles, including material
    handling procedures and storage areas.   Special attention should
    be given to sources which have high odor potentials,  and the
    effectiveness of the operation of the control equipment. The
    inspector should note the following:
    (1)  Dead Stock Skinning Room:  Relative quantities of carcasses
         skinned, in process of skinning, and backlogged;  ventilation
         rates of the work area;  and  chemical counteractants used to
         relieve employee discomfort.

    (2)  Cookers!  Type and capacities of cookers, temperatures and
         pressures on recording equipment,  steam and vapor emissions
         from equipment doors during  loading and unloading, length of
         cooking cycle, rotational speed  of agitator,  and  addition
         of chemicals  such as soda ash to control acidity.
         The type and condition of packings and mechanical seals on
         doors, hatches and valves should be checked.
         The rate of noncondensible emissions is related to the
         ventilation and moisture evaporation from the cookers.
         Emission rates from dry cookers  are generally greater  than
         from wet cookers.  Emissions from continuous  operations will

-------
                      7.3.19
     tend  to  be  lower  than  from batch  systems.   Emissions  from
     blood and feather cookers  will  be comparatively  lower.   In
     the vacuum  cooking procedure,  the cooking  cycle  is  adjusted
     to the rate of  steam removal by condensation.  Emission
     rates tend  to increase with pressure cookers.  Steam  and
     vapors must be  relieved  through by-pass  lines.

(3)   Vent  Lines; Design and  condition;  leaks in ductwork; type
     of condensers  (contact,  air-cooled, water  cooled, surface);
     condensate  temperatures;  quantity of cooling water  used5
     condition of cooling equipment; handling of condensates; use
     of interceptors to prevent fouling of  condensers and  control
     devices'; and type of corrosion  resistant materials, such as
     stainless steel,  used  in the construction of the vent lines
     and  condensers.  Where interceptors are  not used the
     incidence of "wild blows"  should  be noted,  particularly  in
     dry rendering operations.   Wild blows  are releases of large
     amounts  of  animal matter  at high  velocity  due  to increasing
     line  pressure.   They occur whenever cooker  vents become
     blocked.

(4)   Other Sources.'   The inspector  should  note dumping  of  cooker
     contents into percolators, and collection of offgases by
     hoods; the  type and operation  of  the  air driers  (which are
     usually  continuous) including  moisture content,  temperatures
     and capacities; and odors  from  the expeller presses.   Emissions
     from  the percolator pans  should be vented  to the control
     system.  The occurrence  of visible emissions from the expellers
     should be noted.

-------
                        7.3.20
     The  grinders,  conveyers  and handling  of  pressed  solids
     should  also be noted  for possible  dust emissions.   Particles
     are  coarse and dust emissions problems are  not likely  to  be
     significant.

(5)   Air  Pollution  Control System; The  control system may  consist
     of afterburners,  condenser-afterburner combinations,  scrubbers
     and  scrubber afterburner combinations, depending on the
     degree  of control required.  In most  cases  any
     control device which  is  as effective  as  incineration  at
     1200°F  is acceptable  for use.  Minimum required  retention
     time is 0.3 seconds.   A  temperature and  pressure recording instru-
     ment can be furnished to the inspector.  Measurement of time
     interval should be taken from the  inlet  to  the point where tem-
     perature is measured.  Removal of  exhaust moisture  by use of
     condensers or  scrubbers  is required.  Hot wells  should be
     covered and vented to the afterburner.   The hot  well  dis-
     charge  should not exceed 140°F.  Cyclone collectors are
     required on the control  system if  dust emissions are  involved.

     The  inspector  should  determine the amount of  gas available in
     relation to the amount required to provide  the minimum re-
     quired  temperature.   The combustion zone of the  fire box  and
     calibration of the pyrometers should  be  checked  to  assure that
     they have not been altered.  The inspector  may verify the
     temperature by using  a pyrometer furnished  to him by his  agency.

     Scrubber designs  based on packed towers, mobile
     beds, meshes, woven  clothes, etc.  may result  in  clogging
     with resultant releases  of odorous emissions.  Scrubbers
     based on high  velocity eliminators (both air  and circulating

-------
                    7.3.21
water) with countercurrent spraying to achieve high saturation
                                                        (2)
efficiency may be effective in reducing odor complaints.
Addition of soda ash solution to the scrubber water may also
help to reduce odors, although this must be determined
empirically in each installation.  Strong oxidizing solutions
such as chlorine dioxide also may be used.  The inspector
                                               t
should note these operational details as well as the capacity
of the water storage tank, the number of water changes, and
the amount of makeup water added to the scrubber. Misting of
the scrubber should also be noted.

Carbon adsorbers may also be as effective as afterburners,
but are largely limited to drier exhaust, or to systems
which cool and dry the gases prior to treatment by control
equipment.  Where adsorbers are used, the inspector should
check temperature and moisture contents of exhausts before
and after, carbon life and capacity, frequency of replacement,
and the quality and quantity of carbon used.  The desorbed
gases must be contained or destroyed by incineration during
regeneration of the carbon elements.

-------
                                    7.3.22
                                 REFERENCES

1.  Walsh,  R.  T.,  and P.  G.  Talens.   Reduction  of  Inedible Animal Matter.
    In:   Air Pollution Engineering Manual, J. A. Danielson  (ed.).
    Cincinnati,  DHEW,  PHS, National  Center for  Air Pollution  Control  and  the
    Los  Angeles  County Air Pollution Control District.  PHS No.  999-AP-40.
    1967.

2.  Anderson,  L. W.   Odor Control in Rendering  by  Wet Scrubbing  - A Case  History.
    Greensboro,  North Carolina.

-------
                                     7.4.1
                           IV.  STEEL MILLS-FURNACES

A.  DESCRIPTION OF SOURCES
    The production of ferrous metals may generally be divided into (1) pig
    iron and steel production and (2) secondary metals or product production.
    Pig iron production consists of the reduction of iron ore in blast
    furnaces.  Steel production consists of the reduction of carbon in the
    iron and the addition of alloys to specifications usually performed in
    electric steel furnaces, open hearth furnaces, and Basic Oxygen Furnaces
    (EOF).   Secondary ferrous metal production is based on the charging of
    either  scrap metal, pig iron (ingot) or both, and is treated in Section IX,
    Ferrous and Non-Ferrous Foundries.

    Emissions from steel mills occur primarilly from charging, oxygen blowing
    and tapping operations and take the form of smoke, fumes, dust, and carbon
    monoxide.  Particulates include, principally, iron oxide, silicon, and
    manganese and phosphorous oxides.

    Figure 7.4.1 shows the trends in carbon steel production in the United
    States by furnace type indicating virtually no production from Bessemer
    converters after 1966 and a decline in the use of open hearth furnaces.
    Small gains in electric steel operations and a sharp increase in the use
    of basic oxygen furnaces  (EOF)  may be noted.     Production of iron and
    steel once concentrated in the east and midwest has expanded to the south,
    far west and northwestern regions of the United States.

B.  PROCESS DESCRIPTION
    Steel production begins with the mining of iron ore, coal and limestone.
    Iron ore is sintered or pellitized; limestone is crushed and graded, and
    coal is processed into coke.  These materials are then fed to a blast
    furnace and are transferred in the molten state to an open hearth or basic

-------
                   7.4.2
          Process
Open hearth furnace

Basic Oxygen furnace (EOF)

Electric furnace

Total
                      Production of Raw Steel in 1968
                                               Percent
                                               of Total
Millions of Net Tons
        66. 1

        48. 6

        16.4
                             133. 1
                                                 50.4

                                                 37. 1

                                                 12.5
                                                100
               130
               120
               I 10
             ||00
             ~ 90
             o
             £ 80
             £ 70
             I 60
             .1 50
             ~ 40
               30
               eo
               10
                o'
       -  Open Hearth
       "Carbon - Steel  Ingots
        1955    I960    1965    1970    1975
                       Year
Figure 7.4.1.  PRODUCTION  OF  CARBON RAW STEEL IN TH:
               UNITED  STATES  BY VARIOUS PROCESSES
               (SOURCE:  BATTELLE,  Reference 1)

-------
                                 7.4.3
oxygen furnaces for processing into steel, or in the form of solid pigs
to electric steel furnaces.  Some scrap steel is used in all of the steel
making processes.  After alloying and reducing carbon, the steel is poured
into ingots for transport to the rolling mill.  The furnaces described
below are utilized in steel production.

1.  Blast Furnaces
    Pig iron or molten iron for steel producing furnaces is produced from
    the reduction of iron ore FE 0, (hematite) or Fe 0,  (magnetite) to
    iron in the blast furnace.   Production ranges from 400 to 2400 tons/
                    (2)
    day per furnace.     Physically the furnace appears  cylindrical but
    the diameter increases near the base where a Bustle  Pipe or hot blast
    air manifold circumscribes  the furnace and introduces blast air to
    the tuyeres as shown in Figure 7.4.2.

    Blast furnace operations are continuous and are only interrupted for
    repairs or production cutbacks.  The furnace charge  or burden consists
    of alternate layers of iron ore, coke and limestone.   At furnace
    startup, wood or other readily ignitable material is used to initiate
    combustion of the coke.  Blast air, used to support  combustion and force
    the gases through the burden, is preheated in stoves which are 28' x 100'
    cylinders lined with refractory brick.  The refractory houses checkerwork
    which serves to store heat  to increase the temperature of the incoming
    air (Figure 7.4.3).

    Two or three stoves are used per blast furnace depending on the air
    requirements.   Since air is the largest single ingredient in the
    production of  pig iron—4 to 4 1/2 tons of air per ton of iron
    produced—the  air handling  and preheating equipment  becomes very
    important.

-------
                     7.4.4
Figure 7.4.2.  A TYPICAL BLAST FURNACE
               (SOURCE;  BATTELLE, Reference 1)

-------
                  7.4.5
Figure 7.4.3.  A TYPICAL BLAST FURNACE STOVE
               (SOURCE;  BATTELLE, Reference 1)

-------
                             7.4.6
The typical solid constituents of the burden, 1.7 tons of iron ore, 0.9
ton of coke, 0.4 ton of limestone and 0.2 ton of sinter, scale and
scrap are charged through the top of the furnace by a mechanical
loader.  As the melt progresses (the iron ore is reduced by the CO
and hydrogen rising through the burden) a pool of molten iron covered
by slag forms at the bottom of the furnace.  Removal of metal and
slag occurs every 4 to 5 hours with the slag usually removed more.
frequently.  The molten iron runs into either a ladle or a ladle car
for transport to the steel furnace while still in the molten state,
completing the reduction process.

Electric Steel Furnaces                                v
Electric steel furnaces are used for the refining and alloying of steel,
especially stainless and specialty steels.  The charge consists of
steel scrap and pig iron.  It is not common practice to use molten
iron as a part of the charge in electric steel furnaces as it is in
open hearth and EOF operations.  Figure 7.4.4 shows a cutaway view
of an electric furnace.  Furnace capacities range from 2 to 250 tons
with a melting time of 4 to 5 hours.  Most electric steel furnaces
used in production mills in the United States have a basic refractory
lining.  The few furnaces that are acid lined are Used  for special
steels in foundries.

Physical dimensions of the furnace will, of course, vary with
its capacity but the shape is usually similar to the circular
cross-section and three carbon electrodes projecting from the top of
the furnace, as shown in Figure 7.4.4.  The production rate of the
furnace is dependent upon the electrical energy supplied to the
electrodes.  Figure 7.4.5 shows the relationship between furnace
capacity and energy input (KVA rating of transformers).

-------
                   7.4.7
                               Carbon electrodes

                                        Port fur tlnrd electrode
Figure 7.4.4.   DIRECT ARC-ELECTRIC  FURNACE
                 (SOURCE:   BATTELLE,  Reference 1)

-------
                           7.4.8


in
e;

E
o
in
c
e




OVJ


70


60

50
40

30


20


10


O
1 1 I 1
0

- —
©

-

* t •
-
e« ® .. *
e e
CC»
w
- f*^-^®o —
€^''*- ^ w
s*^
- 
-------
                                 7.4.9
    Use of thin sheet iron scrap is generally avoided in electric
    furnaces since it tends to burn rather than melt.  Care is also
    taken not to charge large quantities of dirty scrap which will cause
    excessive emissions by its nature.   Operating procedures may include
    oxygen lancing to shorten the refining cycle, which causes dense
    emissions from the boiling of the molten metal.

3.   Open Hearth Furnaces
    Open hearth furnaces are the major steel producers in the United States.
    During the last 5 years production from the basic oxygen process has
    more than doubled and there is speculation that  by 1990 open hearth
    furnaces will be completely replaced by EOF.  Open hearths,  however,
    will remain a factor in air pollution control for many years.

    This method of producing steel uses either molten or solid pig iron,
    scrap iron and steel, iron ore and limestone and the furnace can be
    either acid or basic lined.  The open hearth furance (Figure 7.4.6)
    is regenerative, i.e., uses the heat removed from the exhaust gases
    to preheat the combustion air in two regenerator or checkerwork
    sections.  Each section serves alternately as the exhaust passage for
    the hot products of combustion and the inlet passage for combustion
    air and fuel (coke oven gas, natural gas, etc.).  Every 15 to 20
    minutes dampers are mechanically actuated to change the direction of
    flow of the gases, thus the term regenerative furnace.

-------
                          7.4.10
      Furnace Hearth
Figure 7.4.6.
CROSS-SECTION OF A  BASIC OPEN-HEARTH FURNACE
(SOURCE:  BATTELLE,  Reference 1)

-------
                                     7.4.11
                                                           PERCENT OF TIME IN
          PHASE OF OPERATION                               INDICATED PHASE
Tap to start (completion of one heat to                             6
start of another)
Charging                                                           12

Meltdown                                                           12

Hot-metal addition                                                  3

Ore and lime boil                                                  38

Working-refining                                                   19

Tapping                                                             2

Delay                                                               8

        Open hearth furnaces usually produce 100 to 200 tons of steel per
        heat which require 12 hours of  furnace time without  the use  of
        oxygen, 8 hours with "light" oxygen lancing and 4 hours with "heavy"
        oxygen lancing.  The process starts after the tap of the previous
        heat.  This "tap to start" time is used for repairs  to the hearth or
        other refractory material.

        The next step or ore and lime boil, involves the generation of
        carbon monoxide from the oxidation of carbon.  Gentle bubbling  occurs
        initially followed by violent bubbling from the release of carbon
        dioxide from the calcining of limestone.

-------
                                 7.4.12
    During  the working  or  refining phase,  the  phosphorus  and  sulfur
    are  reduced  to  specification  limits,  the carbon  content is  lowered,
    proper  slag  formation  is  attained  and  the  oxygen is introduced by a
    lance immersed  in the  bath.   This  final step will consume 900 to
    1667 standard cubic feet  per  minute of oxygen  during  the  injection
    period  totaling 600 to 1000 cubic  feet per ton of metal.   The heat is
    tapped  to a  ladle at approximately 3000°F  and  then either poured into
    an ingot mold or conveyed to  the foundry to be poured into  castings.

4.   Basic Oxygen Furnace
    This process for making steel is coming into increasing use in the
    United States due to the large reduction in the time required to
    produce
    hearth.
                                            (1   2)
produce a heat,  33 minutes vs.  8 to  12  hours   '     for  the open
    Two principal furnace designs  are  the  upright  and  the  rotary
    (Figures 7.4.7 and 7.4.8,  respectively).   The  process  in both designs
    uses a hot metal charge of scrap steel and flux.   The  upright furnace
    uses a ratio of 70% hot metal  to 30% scrap.  Rotary furnaces can use
    more scrap but require longer  heat time.   External application of
    heat is not required.  The hot metal and  the exothermic  reaction (heat
    release) from the oxygen and the carbon and silicon provide the
    necessary heat.

    In the EOF process a water cooled  lance blows  oxygen at  high velocity
    below the surface of the bath  causing  a violent  reaction.  The lance
    serves to agitate the metal, add heat  to  the process and to reduce,
    by oxidation, the carbon and other elements that are required to
    meet the specification of the  steel being produced. Furnaces range
    from 75 to 325 tons per heat.   There are  60 existing upright furnaces

-------
                     7.4.13
                 TYPICAL B4SIC OXYGEN FCE
                      (B.OFJ
Figure  7.4.7.  BASIC OXYGEN FURNACE
                 (SOURCE:  BATTELLE, Reference 1)

-------
                      7.4.14
Figure 7.4.8.   STORA-KALDO ROTARY OXYGEN CONVERTER
               (SOURCE:   BATTELLE, Reference 1)

-------
                                   7.4.15
        in the United States    and 2 rotary furnaces (1969)  which have
        a total capacity of approximately 57 million tons/year.   The follow-
        ing represents a typical 150-ton EOF operation:
             Charge Scrap                         1 minute
             Charge Hot Metal                     2 minutes
             Oxygen Blow                         20 minutes
             Chemical Tests                       5 minutes
             Tapping Time                         5 minutes
                TOTAL TIME                       33 minutes

C.  EMISSIONS AND INSPECTION POINTS
    Inspection points relative to emissions from iron and steel processes
    have certain fundamental characteristics which are the same for all of
    the furnace types used.   These include furnace charging operations,
    melting, working and pouring.  In addition,  the maintenance of the
    furnaces, ductwork and dust/fume collectors  must be continually
    inspected to determine the effectiveness of  the air pollution control
    equipment.

    1.  Blast Furnaces
        Most blast furnaces  are charged by skip  loader from the stock house
        for lime and ore and from the coke pile  for coke.  This operation will
        emit dust (iron ore, limestone, coke) when the skips are loaded and
        when the load is dumped into the top of  the furnace.  Since this is
        a continuous process some of the dust from the burden will be
        entrained in the exhaust gases, which have a high CO content, and will
        enter the dust/fume  collector.   On almost all blast furnaces leaks
        around seals and the top of the furnaces are prevalent.

-------
                             7.4.16
The condition of the material charged to make up the burden can have
a significant effect on the dust emissions.  For example, the greater
the ratio of sinter to ore the lower the dust loading in the effluent
gas stream (top gas).   As in most systems where there are high
temperature or high pressure gases a by-pass or relief valve (bleeder)
is required for short periods of time to relieve excess pressure
caused by a buildup in the furnace.

Slips, sudden movements or shifts in the burden, create  high
pressures in the furnace causing the bleeders to open.  Depending on
the make-up of the burden, i.e., ratio of sinter and pellets to
screened ore, large quantities of dust can be emitted at this time.
Because slips cause the bleeder to open, the inspector should record
the frequency and duration of this occurrence and the opacity of the
resultant emissions.

Since the top gas is rich in CO, it is valuable as a fuel for other
steel mill operations which include heating coke ovens, stoves and
for waste heat boilers.  This is the major economic factor in the
use of dust/fume removal equipment for blast furnace top gas since
the entrained dust would clog checkerwork in the coke ovens and
stoves.  It is anticipated that technology advances in blast furnace
operations involving higher temperatures will require the top gas
to be "cleaned" to 0.001 grams/SCF.     The gas cleaning train usually
consists of a cyclone for large particle removal, a wet scrubber
(which also serves as a gas conditioner) and an electrical precipitator,
or venturi scrubber.

To complete the inspection of the furnace cycle the inspector should
also observe the slag and iron tapping operations and record the
opacity and duration of emissions.

-------
                                7.4.17

2.  Electric Steel Furnaces
    Air contaminants emitted include smoke from dirty scrap and dust and
    fumes from melting.  The operation of these furnaces requires the
    furnace roof to be removed during charging which poses a control
    problem in loading the furnaces.  The Bethlehem Steel Corporation in
    its Los Angeles plant has abandoned conventional hooding in favor of
    using the entire building as a hood and collecting the emissions
                              (3)
    through the roof monitors.     Most electric furnaces are controlle
    with baghouses, although scrubbers and precipitators are also used.
    During the melting period fumes are generated but pose no  particular
    collection problem.  The oxygen blow produces large quantities  of
    brownish smoke and fumes and is probably the major source  of air
    pollution in terms of opacity and duration of emissions and the most
    difficult to control with conventional hooding.   The inspection report
    should include the quantity of oxygen used during lancing.   This data
    is available from the operator's log.

    Other observations which must be recorded include the adequacy  of the
    dust and fume pick up system during pouring; the condition of the
    material charged and the charging time; a check  of the air pollution
    control equipment to determine its operating condition and state of
    maintenance (see Chapter 2 for details); the condition of  the entire
    exhaust system including the state of repair of  hoods and  ductwork,
    exhaust fan and drive belt condition; and opacity of emissions  from
    the air pollution control equipment exhaust duct.

3.   Open Hearth Furnaces
    Most open hearth furnaces use hot metal directly from the  blast furnace.
    The hot metal comprises about 60 percent of the  metal charge.  The
    remainder is scrap steel.  Limestone and iron ore are added to  provide
    a source of oxygen and to form slag.  The sources of contaminants from
    this process include charging; products of combustion of fuel which

-------
                                7.4.18
    may have a high sulfur content; iron oxide fume from oxygen blowing;
    and fumes from tapping and pouring operations.  Oxygen lance blowing
    also causes large volumes of smoke and fumes.   The furnace gases take
    a long path through the inside of the furnace, the checkerwork, and
    the slag pocket and frequently are passed through a waste heat boiler
    which serves to eliminate the larger size particles from the gas stream.
    The conventional control equipment applied to this process is an
    electrical precipitator; however, venturi scrubbers and baghouses have
    also been used.

    The inspector should observe emissions from the scrap charged, oxygen
    blow, and pour that may escape the dust/fume collection train.  The
    collection train usually includes an electrostatic precipitator.

    Excessive emissions from a stack usually mean either (1) poor condition
    of the control equipment because of inadequate maintenance, or (2) a
    change in the furnace process, such as use of oxygen lancing where not
    previously used, or a considerable increase over the previous lancing
    rate.

4.  Basic Oxygen Furnaces
    Emissions from this process center around the oxygen blowing phase of
    the process.  The emissions range from iron oxide from the initial
    burning of iron when the oxygen blow starts, to silicon, manganese
    and phosphorous oxides, and carbon monoxide.  In this process, the
    hood design for collection of the effluent is critical to (1) capture
    of the large volumes of emission from the oxygen blow and (2) to dilute
    the concentration of the carbon monoxide to prevent an explosion
    hazard.  CO combustion to C0_ may also be considered.

    Air pollution control equipment predominantly  consist  of water scrubbers
    and electrical precipitators.

-------
                           7.4.19
The inspector can, by visual observation, determine the effectiveness
of the ventilation system for the collection of emissions from this
furnace.  His observations during the oxygen blow and the pour can
help to determine the efficiency of the hood design since most
emissions from this operation are in the visible range.  The inspector
should also record the oxygen flow rate and total amount used.

Many of the older EOF's have undersized ventilating and collection
systems because oxygen lancing rates have been increased considerably
beyond what was practiced when these furnaces and control systems
were designed and built.  The efficiency of the control equipment,
however, may call for stack testing,

-------
                                    7.4.20
                                  REFERENCES


1.  Varga, Jr.,  J.,  and H.  W.  Lownie,  Jr.  A  Systems Analysis  Study  of  the
    Integrated Iron  and Steel  Industry.  Columbus, Ohio,  Battelle Memorial
    Institute.  May  15, 1969.

2.  Schueneman,  J. J.,  H. D. High,  and W.  E.  Bye.  Air Pollution Aspects  of
    the Iron and Steel  Industry.   DREW, PHS,  DAP. Cincinnati,  Ohio.  June 1963.

3.  Venturini, J. L.  Operation Experiences with a Large  Baghouse in an
    Electric Air Furnace Steelmaking Shop.  J. Air Pollution Control Association,
    Vol. 20, No. 12.

-------
                                     7.5.1
                             V.  COKING OPERATIONS

A.  DESCRIPTION OF SOURCE
    The primary use for coke in the United States is in blast furnace pro-
    duction of iron and steel.  Two types of coking processes are employed:
    by-product ovens, which recover volatiles, and beehive ovens which emit
    volatiles directly to the atmosphere.

    Since 98.5% of the total U.S. coke output, as of 1967,    came from by-
    product ovens, beehive ovens are not treated in this discussion.   The
    use of beehive ovens is economically feasible only during periods of high
    steel production.  Increasingly stringent air pollution regulations should
    all but eliminate their use.

    The location of coke plants is dictated by the largest user of its product,
    the iron and steel producing industry (See Section IV).  Many steel mills
    conduct their own coking operations, while many coke plants are in-
                                                                       /
    dependent operations.  The national distribution of coke plants by
    location follows very closely the distribution of major steel producing
    facilities although some plants are located near major coal producing
    areas.  Approximately 60 coke manufacturing plants with an annual capacity
    of 60,000,000 tons per year are operated in the United States.

B.  PROCESS DESCRIPTION
    In coke manufacturing high rank bituminous coals with low ash and sulfur
    content are blended, reduced in size, and mechanically conveyed to coke
    ovens for carbonizing.  Five basic steps are involved (see Figure 7.5.1):

-------
                                       Products of Combustion
                                            From Heating
                Storage
  Coal
  Preparation
  and
  Blending
Ovens
85 to 90% 1/8"
	2— By-products  to
 control equipment &
 chemical recovery
 plant.

 Hot coke to
       quench  cars
                                           Quench

                                            Tower
 Screening
and Sizing
                                                                                                               Storage
                                                                                                                          Ol
                                                                                                                          ro
                                      Fuel to heat ovens;
                                      blast furnace gas,
                                      coke gas or a mixture
                                      of both.
                              Figure 7.5.1.  PROCESS FLOW DIAGRAM OF COKING OPERATION

-------
                                 7.5.3
1.  Coal blending and preparation to provide the coal properties re-
    quired for the physical and chemical characteristics of the coke
    desired.
2.  Carbonizing in retort ovens to drive off the volatiles from the coal.
3.  A pushing sequence in which coke is removed from the ovens and pushed
    into gondola quench cars in an incandescent state.
4.  Quenching of the coke in quench towers by applying large quantities
    of water.
5.  Size reduction of the coke to a prescribed specification.

A sixth step, while not a processing operation, is the storage of the coke
in huge piles usually at an area adjacent to the oven.  This storage
results in large quantities of dust being blown several miles distant
from the storage piles.

The by-product coke oven is a retort which is externally heated by either
blast furnace gas or coke oven gas to an inner wall temperature of from
2000°F to 2200°F.  Coal is formed into coke in the retort oven in the
absence of air.  The oven is rectangularly shaped, 39 to 42 feet long,
between 10 and 20 feet high and 14 to 20 inches wide with a 1-1/2 to
4-inch taper from push to discharge end.  The oven is charged from a larry
car (hopper car) into three or four ports on its top side.  The ovens are
arranged in banks with the larry car riding on rails on the top of the
ovens.

Coal charging rates vary from 16 to 20 tons per oven per charge with a
carbonizing period of 17 to 18 hours.  A battery of ovens can consist of
up to 100 slots (individual retort type rectangular cross-section ovens)
operating as a continuous process with alternate charges and "pushes" of
the distillation residue (fused coke) at about 2000 F.

-------
                                 7.5.4
The by-products generated from the coking operation are ducted to ascension
pipes at either or both ends of the retort ovens and are transported under
negative pressure by means of exhaust fans in collector mains to a
conventional chemical treatment plant.  The by-products include mixtures of
organic (usually aromatic) compounds, combustible gases (carbon monoxide,
hydrogen,  methane, hydrogen sulfide, ammonia, and nitrogen).  The organics
include tarry compounds (e.g., anthracene), benzene, toluene, xylene, naththa-
lene, phenols, and pitch.  The processing system, shown in Figure 7.5.2,
serves to condense, separate, absorb, distill, clarify, segment and recover
the valuable substances contained in the raw gas.

The coal tar is either sold to refiners or used as fuel in the open hearth
furnaces.   The ammonia and pyridine materials can be removed by absorption
in sulfuric acid.  The ammonium sulfate which forms in the sulfuric acid
solution is removed and sold to the fertilizer industry while the pyridines
are sold in a crude state to chemical plants where they are further
refined.  The coal and gas from the coke ovens yields crude naphthalene  >
and various light oils such as benzol, toluol, xylol, etc., which can be
removed by absorption.  These are stripped and refined.  A prime
product is the recoverable coke oven gas with a gross heating value of
between 500 and 550 Btu per cubic foot.  This gas is generated at about
11,000 cubic feet per ton of coal charged to the process.  The gas can
be used in various operations, to fire boilers or to provide a source of
energy for other heating needs of the coke plant or its adjacent steel
plants/2^

Serious consideration has been given to technological changes in the
production and manufacture of coke, such as pipeline charging.  Any maior
change in operation or control is about two years away, though new pushing and
quenching  changes are available now.  Since blast furnaces are the
largest consumer of coke, the rate of growth of coke production will
stabilize  due to improved technology in blast furnace operations which

-------
                          7.5.5

i t
Raw Gas and | Coke |
Condensate
|


' n
Gas and Flushing Liquor
Condensate and Tar
*
PRIMARY COOLER [
t *
\ Gas r Condensate
^ I
EXHAUSTER HOT TAR DRAIN TANKS
1 1 1
PRECIPITATOR DECANTER Flushing -»
Liquor
,
REHEATER Tar 1 Ammonia and
Phenols
I
Gas AMMONIA STILL •* 	
| Acid | * *

'
| 	 Ammonia Weak Ammonia Liquor |
*
SATURATOR PHENOL TOWER | ^
* t * *
Pyridines | Gas | Ammonia Sodium Phenolate |
* Sulfate 1
PYRIDINE ' "

PLANT ACID Further Processing
SEPARATOR
I
FINAL 	 *• SCRUBBER -• 	
COOLER


GAS Benzolized
HOLDER Wash Oil
i 1
BOOSTER BENZENE
STATION PLANT
| V




Steel Plant Use Debenzolized «.
Wash Oil
Figure 7.5.2.  REPRESENTATIVE BY-PRODUCT PLANT FLOW SHEET
               (SOURCE:  BATTELLE MEMORIAL INSTITUTE,
                Reference 3)

-------
                                    7.5.6
    will serve to reduce the quantity of  coke per ton of steel produced.   This
    source of smoke and dust is  receiving very serious attention from the iron
    and steel industry.   Extensive  investigation leading to newer more self-
    contained methods of producing  coke are required.   Development toward this
    end is now underway in Europe but turnaround methods may be 15 years  away,
    based on the long life of the ovens used in the  United States.

C.   CONTAMINANTS EMITTED
    1.   Coke Preparation and Oven Operations
        Emissions from coking operations  cover a large spectrum from smoke and
        particulate matter to carbon  monoxide,  carbon  dioxide,  hydrocarbons,
        hydrogen sulfide,  and phenols occurring mainly during charging and
        pushing and from "leaks" around the furnace  doors,  charging parts,
        chuck doors,  and any other  openings.   Charging of  the ovens and pushing
        are usually the most serious  air  pollution control  problems in coking
        operations.

        Emission rates  are  estimated  at approximately  two pounds per hour  of
        particulate emissions for every ton  of  coal processed.^   Gaseous
        emission rates,  coal preparation losses  (directly attributable  to  coke
        operations) and  airborne dust from storage piles have not been
        conclusively established.  The latter frequently results in numerous
        complaints from  areas adjacent to coke  storage locations.  The
        regulations most commonly violated by this process are opacity or
        Ringelmann number, particulate grain loading and nuisance.

        In the coke preparation and  blending areas the generation and emission
        of dust is the principal problem.   The operations found here are
        size reduction and mechanical conveying.  Dust is generated from the
       size reduction equipment,  transfer points, loading and unloading
       points.

-------
                             7.5.7
By-Product Processing Emissions
Emissions from the primary end of the by-product processing system
usually are minor in amount due to the negative pressure in the trans-
port system.  Some odor indicative of free vapor at the tar collectors
and decanters or wherever the liquor runs in lines that are not fully
enclosed may be noted.  Ammonia and organic fumes are strong at the
sumps where decanted liquor and other flush liquor is collected for
recycling to the collector-mains sprays.  To minimize local nuisance,
the flushing liquor sewers are usually fairly well capped and covered,
but there often is no sealing because these ducts become fouled with
tar and other "goop."  Access for stream cleaning is essential, but
is not always frequently used.

Downstream of the exhausters, the detarred gas is still quite rich
in ammonia, both free and in combination.  The liquor decanted from
the tar at primary cooling is also quite rich, and because of the
moisture vaporized from wet coal this liquor exceeds the requirements
of the flushing-liquor system.  Both the excess liquor and the gas can
be stripped of ammonia, which is recovered usually as ammonium sulfate.
(America's largest coke plant is big enough to recover the ammonia
on a commercial basis as anhydrous ammonia.)  In the conventional
sulfate process, the gas is reheated (to hold its moisture in the vapor
phase) and passed through sulfuric acid where ammonium sulfate is
precipitated.  Ammonia vapor distilled from the surplus flushing liquor
is also passed through this precipitator.  The residue after distillation,
known as weak liquor, may be processed further or disposed of via
sewers or to the coke quench.  The residue still contains ammonia
plus a number of soluble organics such as phenols.

Emission to the air from the ammonia system generally is quite minor,
because the ducts are closed piping for the most part, and leaks usually

-------
                             7.5.8
are promptly detected and repaired.  One activity that can cause
trouble in the older plants is the addition of strong sulfuric acid
to the precipitator tank, an operation usually accompanied by
considerable fuming of the acid.

In large coke plants, the ammonia-recovery system may be augmented
by systems for recovery of phenol (carbolic acid) from the weak
liquor after ammonia distillation and for recovery of pyridine bases
which dissolve in the ammonium sulfate precipitator tank from the gas.
In smaller coke plants, one or both of these activities may be by-
passed where volume does not justify capital investment for a recovery
system.  Phenol and pyridine systems are closed except for tank vents,
and usually have no substantial problems with regard to emission
to the atmosphere.

The crude tar collected in the collector mains and in the tar
decanters is augmented by minor amounts of tar precipitating at the
secondary coolers or other points in the gas system.  From this crude
tar, pitch sludge settles to the bottom of the decanter and is
mechanically raked out for disposal.  Settled crude tar is sent to a
separate plant for secondary processing by distillation.

Conventional tar processing yields pitch tar, creosote, and two or
more weights of tar oil that may be used in roadbuilding.  Crystals
of naphthalene are a by-product (often discarded), and in larger plants
the tar oils may be further refined to yield salable fractions.

Tars are heavily loaded with polycyclic aromatic hydrocarbons (PAH),
and are generally considered hazardous.  Steelmakers have recently
taken steps to lead tar-processing tank vents and storage tank vents
through scrubbers that absorb or destroy the fumes.  The work has not

-------
                             7.5.9
met with great success yet because tars tend to condense upon and foul
the equipment.  When the scrubbers get fouled, they will discharge
unscrubbed vent vapor.

Gas leaving the ammonia precipitation tank is still warm and contains
a number of light aromatics boiling between 200 and 400 F.  These
light oils are condensed from vapor by cooling the gas to about
ambient temperature in a final cooler.  The condensate is then
scrubbed with a high-boiling wash oil (derived from petroleum) to
dissolve the aromatics, and the wash oil may be steam distilled to
recover the principal aromatics benzene, toluene, and xylene in
commercial form.  The gas is now completely stripped and enters the
plant fuel system.  It contains 3.5 to 4.5 grains of H9S per CF,  which
                                         (3)
is emitted as SO. when the gas is burned.

The vapors of the light oils are considered hazardous both because
of toxicity and because of flammability.  Nevertheless, the condensers
in the distilling system and some of the process tanks are vented.
The vapors issuing from these vents often pervade a large area with
the sweet, almost pleasant smell characteristic of aromatic vapors.

Abnormalities (such as fire or major leakage) are rare in by-product
systems because the high hazard level prompts strong preventative
measures.  However, in the ordinary course of pumping, straining,
dewatering, and otherwise treating coke-oven by-products, leakage
and vapor loss is inevitable.  There may be as many as 40 pumps in the
liquor and still systems; usually some of these have imperfect seals.
Forced ventilation in the pumphouse is a necessity.

Identification of particulate emissions from coke-plant operations has
been limited in the past, but as a result of research carried out by
the integrated iron and steel industry since 1950, methods have

-------
                                    7.5.10
        been developed that  permit  the identification of  particulate emissions
        generated in coke-plant  operation.   While this research has  been
        directed primarily toward obtaining  a better  understanding of the
        coking process,  and  toward  improvements  in the properties  of coke
        required by the advancing blast-furnace  technology,  it  has also
        provided a means of  identifying air-borne particulates.

D.  INSPECTION POINTS
    The inspector should conduct a  complete  inventory of  the plant,  including
    the by-product processing system.   Charging  of the coking ovens  is probably
    the most important single air pollution  problem with  which  the inspector
    will be concerned.  The  inspector  should become familiar with  the
    equipment employed and the variety of  situations  that may be encountered
    in charging operations.

    In the interview of plant management,  and subsequent  inventory of equipment,
    the inspector should determine  with respect  to charging  operations:

    1.  Is the suction in the header or headers  employed  sufficient  to evacuate
        the emissions from the ovens with  all ports and doors open?   It  may be
        necessary to charge  only through two ports at a time or one  port with
        the chuck door open.
    2.  Are sealed dust sleeves  between hoppers  and oven  charging  ports  employed?
        Use of good dust sleeves should choke emissions until hoppers are emptied,
        greatly  Educing emissions.
    3.  What type of feeders are employed?   Use  of screw  feeders in  place of
        gravity type feeders will give better coal flow control and  prevent
        header stoppage thus lessening emissions.
    4.  How are charging port lids  handled?   Use of mechanical  opening and
        closing devices are  more positive  and quick acting  than manual procedures
        thereby reducing emissions.

-------
                               7.5.11
5.  What operating procedures are followed to reduce emissions?  Sealing of
    ports and good mechanical maintenance are necessary factors in reducing
    emissions.
6.  What types  of mechanical controls are employed, e.g., scrubbers, bag-
    houses, etc., and their effectiveness.

1.  Dust from Material Transfer
    Inspections should be made to assure that hoods covering transfer points
    are close fitting and provide sufficient draft to accommodate the dust
    emitted as  the coal drops from one belt to another, is dumped into a
    hopper, or  is transferred to other types of mechanical conveyors.  Duct-
    work must be visually checked to determine dust losses from belts, bucket
    conveyors,  screws, and other equipment.  After all dust pickup points
    have been observed, the inspector should check the dust collection equip-
    ment to determine if the collection efficiency has degraded since the
    initial installation.  Dust collectors are usually located on the roof
    or outside of the building housing the operation.

    In the case of bag type collectors, the inspector can determine if the
    bags are torn by noting the opacity or density of the discharge from the
    bag house exhaust.  He can also determine if the bags are not being pro-
    perly shaken or cleaned by the reduced air intake at the hood due to back
    pressure in the system from insufficient cleaning of the bags.  Other
    types of mechanical devices may be more difficult to troubleshoot; however,
    the two points, pickup at the dust generating source and discharge from
    the collector will give the inspector an overall idea of the effectiveness
    of the control system.

    The blended and sized coal is conveyed to storage bins above the ovens
    and then to the oven charging device, the larry car (Figure 7.5.3).
    This is another transfer point which can produce a sizeable dust

-------
          [	 .	„._ __ j _ rtlV^v'ii.u^v-i-^j;;!;'':^";^:-!'!

          L      TF/ffsvitfz secr/OF   	
          I^Tti'fftJ HtAflNG FLUCS AHO UKDLPJET GAS-DUCTS
Figure  7.5.3.   TRANSVERSE  AND LONGITUDINAL SECTIONS THROUGH KOPPERS-BECKER  UNDERJET-

                 FIRED LOW-DIFFERENTIAL COMBINATION BY-PRODUCT COKE  OVENS

                 (SOURCE:  BATTELLE MEMORIAL INSTITUTE, Reference 3).

-------
                                7.5.13
    emission.   An observation of this phase of the operation should
    provide the inspector with the information necessary to determine
    the effectiveness of the chute enclosure which is designed to contain
    dust emitted during coal transfer.

2.   Charging Operations
    After the larry car has received its load of coal,  it will proceed to
    the oven for charging.  Ports on the top of the oven are either manually
    or mechanically removed allowing the larry car to be placed in a position
    to discharge the fresh charge into the coking oven.   Highly significant
    smoke and dust emissions may occur at this point in the operation.
    Charging smoke is usually brown in color, in which case opacity
    regulations apply.

    Consideration is being given to providing quick responding mechanical
    controls to open the door, insert a chute, charge the coal and re-
    place the door lid as quickly as possible.  Currently, however, most
    of the operations still use manual labor to open and close the loading
    port.

    In order to reduce emissions, it is necessary that a conscientious
    effort be made by the workmen to replace the doors as soon as possible
    after the charge is dumped.  During the operation a leveling bar is
    inserted at the pushing end of the oven to level the charge (Figure
    7.5.4).  This causes significant smoke and dust emissions from the
    push end of the oven.  During the coking operation there can be
    emission from the slot doors and charging ports (one at each end of the
    oven) unless they are properly sealed.  (Modern plants use mechanical
    seals in preference to the old luting practices for door sealing.)  Also,
    where extensive leakage occurs from self-sealing slot oven doors, the
    inspector should inspect the doors to see if they are warped, investigate
    possible malfunctions in mechanical cleaners, such as blade defects and

-------
                                7.5.14
      THf CHARGING LARRY, WITH HOOPERS CONTAINING MEASURED AMOUNTS Or C-OAL, (S IN POSI-
      TION  OVCP OfiA^GiNC HOi PS f-ROW WHICH COVf.RS HAVE BEEN REMGVtO. THE PUOHKR MAS
      fcCTN  ^'OVc.0 INTO POSITION.
                                                   15.	
   P.  TH£ 00AC TROW THS I.A1SY HOPPERS HAS DROPPED IMTO THE OVEN OHAMHCI1. fORUIHC
      PEAKED PILES.
   0. T>: I.CVCLIMC- DOC'I! AT THE TOP OF THE OVf N OOOH ON THE pb'SHEn SIDE K'.C BEtH
     AKD THE LEVEL INS 6iR  OK THE PUSHER HAS OtEN MOVED BACK AND TOftTH ACROSS THC
     PtAr.EO OO^L P'LES  TO LrvCIL THLW.  TKc 6AR NEXT 13 WITHL^/-WN FROM THEC OVtN.THE
     U1VELINO  DOOM  /.NO CHARGING HOLES ARE CLOStO, AND THE CODING OPERATION BF.GIKS.
Figure 7.5.4.    SCHEMATIC  REPRESENTATION  OF  CHARGING AND
                    LEVELING OPERATIONS  FOR A BY-PRODUCT COKE
                    OVEN   (SOURCE:    BATTELLE  MEMORIAL  INSTITUTE,
                    Reference  3.)

-------
                                7.5.15
    make sure that maintenance crews are properly trained in manual cleaning
    procedures.  Table 7.5.1 shows the results of methods studied for
                                    (3)
    charging and pushing operations.
3.   Condition and Operation of Oven
    The condition of the oven is best indicated by emissions from doors and
    ports and by green pushes.  For example:

    1.  Green pushes - maintenance needed on oven leaks and flue, oven and
        flue temperature, normal range (2000-2200°F for oven and 2800 to
        3000°F for flue), proper cooking time, overfilling of ovens.
    2.  Excessive charging emissions - header maintenance required.
    3.  Emissions around doors - door leaks need correction.

    A period of downtime when the ovens are open and being repaired  is a
    good opportunity for the inspector to examine the internal construction
    of the oven.  He can determine if there are cracks in the refractory
    wall which would allow the products of distillation to excape through
    the heating flue; he can see if the ascension pipes and headers  have an
    excessive accumulation of tars which would prevent the proper seating
    of valves and doors, and he can see if there is a build up at the top
    of the oven walls which indicates poor heating which causes green coke.

    An operational point which must be considered by the operator is the
    fact that some "green coal" (uncarbonized) remains near the door at the
    end of the coking period.  This may account for the large volumes of
    smoke and dust arising from the dumped load of coke as the hot green
    coal hits the air and bursts into flames.  Maintenance of the right flue
    temperature, oven tenperature, and proper coking time are operational
    variables which can reduce green pushes.   Figure 7.5.5 illustrates the
    need for good control of coking time.  A sharp drop in the evolution of

-------
                                     7.5.16
                Table 7.5.1.  SEQUENCE OF CHARGING OPERATIONS
               (SOURCE:  BATTELLE MEMORIAL INSTITUTE, Reference 3)
(a)
Elapsed time ,
minutes
Operations
Potential
Emissions
       0.0
       2.0
       2.7
       2.8
       4.0
       5.0
Larry car is filled at blended-coal
bunker and weighed.  Oven doors are
replaced.  If lids of charging ports
are removed by hand, this is done now.

Larry car moves to position over the
charging ports.  (Automatic lid lifters,
if provided, lift lids.)  Drop sleeves
are lowered into ports.

Steam ejector in standpipe is turned on
to draft oven.  Coal begins to flow
from hoppers on larry car and first
rush of gases ignites within the oven.
Dust at bunker
discharge.
Generally none.
Smoke emission
begins slowly
at ports.
Heavy rush of smoke, dust, and gas emerges  Brown to black
around charging ports as steam formation    smoke, with some
increases oven pressures rapidly.           flashes of
Hoppers continue to discharge.              flame.
Hoppers discharge more slowly as coal in
oven rises to bases of the charging
sleeves.  Pusher operator goes to open
the chuck door for leveling.

Coal discharge completed, drop sleeves
raised.  On signal from larryman,
leveler bar is pushed all the way across
oven, then cycled back and forth 3 to
5 feet to level the coal.
Continued smoke.
                                                              Smoke continues
                                                              from ports and
                                                              from the chuck
                                                              door.
       5.7
       6.5
After 5 to 7 strokes of the leveler bar,
it is withdrawn.  Larryman operates lid-
replacement system, or if none, he moves
the larry car and crew begins to re-
place the lids by hand.  Chuck door is
closed and ejector is turned off.

Charging completed.
                                                              Smoke  continues
                                                              until  chuck door
                                                              and port lids
                                                              are well seated.
                                                               Smoke via  leakage
                                                               only.	
(a)   Attainable with mainly hand operations  if coordination between  larryman,  top
     crew,  and pusherman  is good.  Charging  of tall ovens or with  sequenced  dis-
     charge of hoppers may take longer, and  some  time is generally wasted  between
     steps.

-------
                                 7.5.17
Maximum
 I

 T3
 O
 en
 O
 O
 a:
.1
                                                            Time
       14
     Figure  7.5.5.
       15                   16
Elapsed  Coking Time (for Example),  hours
                                                                     17
 APPROXIMATE CURVE ILLUSTRATING THE DECLINE  IN
 GAS AND VAPOR EVOLUTION AT THE END OF THE COKING
 CYCLE  (SOURCE:  BATTELLE MEMORIAL INSTITUTE,
 Reference 3.)

-------
                                   7.5.18
    volatiles occur  in the last  two  hours of coking indicating  that early
    pushing will cause higher emissions.

    Coke Transfer and  Quench Operations
    After the coke has been pushed  (Figure 7.5.6)  into the quench cars,
    resulting in substantial smoke and dust emissions, the cars  are
    transferred to the quench towers where large quantities of water are
    used to cool the coke.   The resulting emissions are covered  by a water
    vapor plume; however,  the plume  may mask heavy grain loadings of
    dust.  Droplets  of corrosive materials (ammonia, phenols) may be found
                                                                             (2)
    in  the steam plumes which can cause property damage and complaints.

             A. COKiWG Or TH5 COA' ORIGINALLY CrtAi^OF.M INTO THE OVSti HAS PEEK' Gf'VH PTEO (IN ASCOT
               19 HOURS) AND ThC O'VTN IS Rli/Dt 10 3E "PUSHED." 1 Hi Os'fN (X>0^ Aiiri fit.'a 5VLO f-ROM
               EACH END, AM) THE PLfSHtH, COKE GUIDE AND QUENGIvh'G OVf( ARf f/iOVEO IHTO PG'jIVlON.
                                        RAM OF PUSHCR
             B. tHE RAM OF THE PUSHER ADVANCES TO PUSH THE INCAMDLSCENT COKE OUT Of THIT OVEN,
               THROUGH THE COKE GUIDE AND INTO THE OUENCHING CAR.
     figure 7.5.6.  SCHEMATIC REPRESENTATION OF PUSHING OPERATIONS
                     FOR A BY-PRODUCT COKE OVEN
5.  Screening and Sizing
    After  quench, the coke is transported to the screening and sizing
    plant  where the unit  operations are  not unlike  those in the  coal
    preparation operation and requires the same observation techniques.

-------
                                 7.5.19
    A problem which is common to all material usually stored in the open
    in large piles is the dust which becomes airborne from these piles.
    Heavy materials handling equipment is used to move the product,
    agitating the pile and abrading the individual pieces of coke and
    creating dust which can remain airborne and be transported over long
    distances.  This problem must be faced in all industrial activities
    where material with some percentage of small particles are stored in
    the open.  Covering the piles, wetting and spraying with a plastic
    material are some of the methods that can be used to control the dust
    from storage piles.

6.  Gas and Vapor Losses
    The gases and vapors resulting from the distillation of the coal are
    ducted to the chemical recovery plant by either a single header or a
    dual header system.  A steam injector in the ascension pipe provides
    added energy to convey the gases to the relatively long distance to
    the recovery plant.  The inspector should check these headers and
    the ascension pipe for leaks and check any doors or ports for
    proper sealing or seating.   Proper maintenance of these systems is
    essential.  The inspector should make sure that the frequency of cleaning
    is adequate and that there is good access to all elements of the systems
    that must be cleaned.

-------
                                    7.5.20
                                 REFERENCES


1.  Control Techniques  for  Particulate Air Pollutants.  Washington,  B.C.,
    DHEW,  PHS,  NAPCA, January  1969.

2.  Schueneman,  J.  J.,  J. D. High,  and W. E. Bye.  Air Pollution Aspects of
    the Iron and Steel  Industry.  DHEW, PHS, DAP.  1963.

3.  Barnes, T.  M. ,  A. D. Hoffman, and H. W. Lownie, Jr.  Evaluation  of  Process
    Alternatives to Improve Control of Air Pollution from Production of Coke.
    Battelle Memorial Institute.  Contract No. PH 22-68-65.  January 31, 1970.

-------
                                    7.6.1
                            VI.  PETROLEUM INDUSTRY
A.  DESCRIPTION OF SOURCE
    Operations of the petroleum industry can logically be divided into
    production, refining, and marketing.  Production includes locating and
    drilling oil wells, pumping and pretreating the crude oil, recovering gas
    condensate, and shipping these raw products to the refinery or, in the
    case of gas, to commercial sales outlets.  Refining, which extends to the
    conversion of crude to a finished salable product, includes oil refining
    and the manufacture of various chemicals derived from petroleum.  This
    chemical manufacture is often referred to as the petrochemical industry.
    Marketing involves the distribution and the actual sale of the finished
    products.

    As of January 1967,    there were 261 United States refineries capable
    of processing nearly 10 million barrels of crude oil daily
    representing an investment of roughly 11.4 billion dollars and supplying
    approximately 72% of the nation's fuel energy and organic chemical
    requirements.  Energy consumption in the United States is expected to
    double between 1960 and 1975, with petroleum supplying a large share of
    the increase.  A domestic demand of nearly 14 million barrels per day
    is projected by 1975.  Nuclear power is not expected to represent a
    major energy contributor until the 1980's.

B.  PROCESS DESCRIPTION
    1.  Crude Oil Production
        The air contaminants emitted from crude oil production consist chiefly
        of the lighter saturated hydrocarbons.  The main sources are process
        equipment and storage vessels.   Hydrogen sulfide gas may be an
        additional contaminant in some production areas.  Internal combustion
        equipment, mostly natural gas-fired compressors, contributes relatively

-------
                                7.6.2
    negligible quantities of sulfur dioxide,  nitrogen oxides, and
    particulate matter.   Potential individual sources of air contaminants
    are shown in Table 7.6.1.

    Contribution of air contaminants from crude-oil production varies
    widely with location and concentration of producing facilities.
    Control and pretreatment facilities  such  as  natural gasoline plants
    are likely to be located in developed or  highly productive areas.
    Control equipment for the various air pollution sources associated
    with crude-oil production are listed in Table 7.6.1.

2.   Oil Refining
    The oil refining process consists of rearranging hydrocarbon
    molecules obtained from crude oil to produce a variety of petroleum
    products, including aviation and automobile  gasolines,  Diesel and
    industrial fuel oils,  domestic heating oils, lubrication oils
    and greases,  kerosene,  asphalt and coke,  hydrocarbon gases,  solvents,
    and a variety of specialty products.

    The air contaminants emitted from equipment  associated with oil-refining
    include hydrocarbons,  carbon monoxide,  sulfur and nitrogen compounds,
    malodorous materials,  particulate matter,  aldehydes,  organic acids,
    and ammonia.   The potential sources  of these pollutants are of several
    types,  as listed in Table 7.6.2.

-------
Table 7.6.1.  SOURCES AND CONTROL OF AIR CONTAMINANTS FROM CRUDE-OIL PRODUCTION FACILITIES
              (SOURCE:  Air Pollution Engineering Manual, Reference 2)
Phase of operation
Well drilling, pumping
Storage , shipment
Compression, absorption,
dehydrating, water treating
Source
Gas venting for production
rate test
Oil well pumping
Effluent sumps
Gas-oil separators
Storage tanks
Dehydrating tanks
Tank truck loading
Effluent sumps
Heaters, boilers
Compressors, pumps
Scrubbers, KO pots
strippers
Tank truck loading
Gas odorizing
Waste-effluent treating
Storage ves sels
Heaters , boilers
Contaminant
Methane
Light hydrocarbon vapors
Hydrocarbon vapors, H^S
Light hydrocarbon vapors
Light hydrocarbon vapors,
H2S
Hydrocarbon vapors, H^S
Hydrocarbon vapors
Hydrocarbon vapors
H2S, HC, SO2, NOX,
particulate matter
Hydrocarbon vapors, H^S
Hydrocarbon vapors, ^S
Hydrocarbon vapors
Hydrocarbon vapors, H2S
H^S mercaptans
Hydrocarbon vapors
Hydrocarbon vapors, H2$
Hydrocarbon, SO2, NOX,
particulate matter
Acceptable control
Smokeless flares, wet-gas-
gathering system
Proper maintenance
Replacement with closed vessels

Relief to wet-gas-gathering
system
Vapor recovery, floating roofs,
pressure tanks, white paint
Closed vessels, connected to
vapor recovery
vapor incineration, bottom loading
Replacement with closed vessels
connected to vapor recovery
Proper operation, use of gas fuel
Mechanical seals, packing glands
vented to vapor recovery
P Y
Vapor return, vapor recovery,
vapor incineration, bottom loading
Positive pumping, adsorption
Enclosed separators, vapor re-
Y
floating roofs
Proper operation, substitute gas
as fuel

-------
               Table  7.6.2.   POTENTIAL  SOURCES  OF EMISSIONS  FROM  OIL REFINING
                               (SOURCE:   Air Pollution  Engineering  Manual,  Reference  2)
 Type of emission
Hydrocarbons
Sulfur oxides


Carbon monoxide

Nitrogen oxides

Particulate matter

Odors


Aldehydes

Ammonia
                                                 Potential source
Air blowing,  barometric condensers, blind changing, blowdown systems, boilers,
catalyst regenerators, compressors, cooling towers, decoking operations,  flares,
heaters,  incinerators, loading facilities,  processing vessels, pumps, sampling
operations, tanks, turnaround operations, vacuum jets,  waste-effluent-handling
equipment

Boilers,  catalyst regenerators, decoking operations, flares, heaters, incinerators,
treaters, acid sludge disposal

Catalyst regenerators, compressor  engines, coking operations, incinerators

Boilers,  catalyst regenerators, compressor engines, flares

Boilers,  catalyst regenerators, coking operations, heaters, incinerators

Air blowing,  barometric condensers, drains, process vessels,  steam blowing,
tanks,  treaters, waste-effluent-handling equipment

Catalyst regenerators, compressor  engines

Catalyst regenerators
a\
•e-

-------
                                 7.6.5
Refinery operations can be classified into four basic procedures:
separation, treating, conversion, and blending.

Crude oil is initially separated into its various components or fractions,
e.g., gas, gasoline, kerosine, middle distillates such as diesel fuel and
fuel oil, and heavy bottoms.  Since these initial fractions seldom conform
to either the relative demand for each product or to its qualitative
requirements, the less desirable fractions are subsequently converted to
more salable products by splitting, uniting, or rearranging the original
molecular structure.  Separation and conversion products are subsequently
treated for removal or inhibition of undesirable components.  The refined
base stocks may then be blended with each other and with various additives
to develop the most useful products.

Individual refineries differ widely, not only as to crude oil capacity,
but also as to the degree of processing sophistication employed.

The rearrangement and modification of hydrocarbons is accomplished by
the following processes singly or in combination:
•   Distillation—separation of hydrocarbon molecules according to
    boiling range and type in stills and fractional distillation columns.
•   Cracking—breaking down of large complicated molecules into different
    compounds in catalytic cracking and hydrocracking units.
•   Polymerization—joining together smaller hydrocarbon molecules to
    form larger molecules in polymerization units.
•   Alkylation—substituting or adding an alkyl group such as methyl or
    ethyl.
•   Hydrogenation and dehydrogenation—altering the hydrocarbon structure
    by adding or removing hydrogen in hydrogenation and dehydrogenation
    units.

-------
                                 7.6.6
•   Isomerization—rearranging molecular structure of hydrocarbon
    molecules without changing chemical formula to develop new properties
    in compounds.
•   Reforming—cracking of hydrocarbon to increase octane rating or to
    produce aromatics and paraffins from olefins in reforming.   Hydroforming
    or Platforming units.

Virtually all of these processes are conducted catalytically at high
temperatures and pressures in suitably designed equipment, or by thermal
processes as in distillation and some cracking processes.   Petroleum
stocks are also expensively handled, treated,  blended,  stored and marketed.

Simple refineries may be confined to crude separation and limited
treating.  Intermediate refineries may add catalytic or thermal cracking,
additional treating, and manufacture of such heavier products as lube oils
and asphalts, waxes, and gasoline upgrading processes such as catalytic
reforming, alkylation, or isomerization.
a.  Separation
    Crude oil is a mixture of many different hydrocarbon compounds,  with
    also small quantities of compounds containing sulfur, oxygen,  nitrogen,
    or other elements.   Prior to any other processing,  it is usually
    separated by distillation into fractions of  differing volatility.   In
    order of decreasing volatility (or increasing boiling point,  or
    increasing carbon number), resulting fractions may  be known as wet gas,
    gasoline, kerosene, fuel oil,  middle distillate,  lube distillate,
    heavy bottoms.  The relative quantity of such "straight-run"  products
    is determined by the composition of the particular  crude being handled.
    The products may be treated and sold as finished  products, or further
    processed and blended into more marketable fuels.

-------
                                7.6.7
    Light hydrocarbons may be further fractionated by absorption processes
    or other types of superfractionation.   Heavy fractions may be further
    fractionated by distillation with steam or in vacuum.   Solvent
    extraction and crystallization are other separation processes applied
    to the recovery of heavier constituents such as waxes  and asphalts.

b.  Treating
    Sulfur, in the form of compounds such as organic sulfides, mercaptans,
    polysulfides and thiophenes, is the principal undesirable constituent
    of most crude oil.  A substantial portion of the domestic crude in
    the United States contains over 0.5% sulfur, with some crudes
    exceeding 2% sulfur.

    Both physical and chemical procedures are available for treating
    products and feedstocks for the removal of sulfur.   Physical methods
    include electrical coalescence, filtration, absorption, and air
    blowing.  Chemical methods include acid treatment,  "sweetening" by
    oxidation, solvent extraction, and other means.  Hydrodesulfurization
    processes are extensively used for treating gasolines, middle
    distillates, and lubricating oils.  Hydrogenation converts organic
    sulfur compounds to hydrogen sulfide,  which may be converted to
    elemental sulfur in sulfur recovery plants.

c.  Conversion
    Conversion processes are employed to increase the yield of the more
    desirable products such as gasoline, relative to that  of less useful
    fractions such as middle distillates,  and also to improve the quality
    of marketed products in terms of engine performance.

-------
                                7.6.8
    Depending on refinery operations  and  location,  between 5 and 10% of
    the crude entering the refinery is  consumed  in  processing.   Refineries
    producing mostly light fuels  and  having  access  to  low-cost  supplies
    of natural gas consume less of  the  crude in  this manner.  Demands for
    unleaded gasolines having  adequate  antiknock performance may be
    expected to increase  the fraction of  crude that must  be processed,
    as well as the amount of oil  and  gas  that must  be  consumed  to provide
    the energy for processing.

    Conversion processes  belong to  three  main categories,  depending on
    whether the carbon number  of  the  product is  smaller,  greater, or
    about the same as that of  the feedstock.  Processes of the  first type
    are referred to as cracking;  the  main types  are thermal cracking
    (which includes visbreaking and coking), catalytic cracking,  and
    hydrocracking.  Hydrocracking is  done in the presence  of  a  high
    partial pressure of hydrogen.   It complements ordinary catalytic
    cracking and adds flexibility in  meeting seasonal  products  demand
    fluctuations.   In the second  category, converting  lighter hydrocarbons
    to gasoline-range products, are alkylation and  polymerization.
    Finally, processes which improve  the  character  of  the  product without
    major effects on the  boiling  range  include a variety  of catalytic
    reforming processes,  as well  as isomerization,  cyclization,
    hydrogenation and dehydrogenation.

d.   Blending
    The relative few refinery  base  and  intermediate stocks are  blended
    in innumerable combinations to  produce over  2,000  finished  products
    including liquefied gases, motor  and  aviation fuels,  lubricating oils,
    greases, waxes,  and heating fuels.  Rigid specifications as to vapor
    pressure,  viscosity,  specific gravity, sulfur content, octane number,
    initial boiling point,  and other  characteristics may  be required,
    depending upon the intended use of  the product.

-------
                             7.6.9
The composition of gasoline, for example, is adjusted to be suitable
to the climate and altitude of various marketing areas.  In winter,
refiners add more light hydrocarbons to increase vapor pressure and
facilitate engine starting at lower temperatures.  In both winter and
summer, however, vapor pressure must be adjusted to minimize the
problem of vapor lock.  Such compromises lead to constant shifting of
hydrocarbon mixtures to produce acceptable performance.

Refiners add to gasoline various chemicals such as antiknock agents
(including tetraethyl lead), detergents, polymerization inhibitors,
and others.

Types of Contaminants
Individual refineries vary greatly as to the character and quantity
of emissions.  Controlling factors include crude oil capacity, type
of crude processed, type and complexity of the processing employed,
air pollution control measures in use, and the degree of maintenance
and good housekeeping procedures in force.

The major refining operations offer a guide as to the type of
releases that are likely to be encountered.  In crude separation the
use of barometric condensers in vacuum distillation can release
noncondensable hydrocarbons to the atmosphere.  Regeneration of
catalyst in cracking by controlled combustion can release unburned
hydrocarbons, carbon monoxide, ammonia, and sulfur oxides.  Catalyst
handling systems can also be the source of discharge of catalyst
fines.  The conversion processes—alkylation, reforming, polymerization,
isomerization, and their variants—are significant in that they handle
volatile hydrocarbons, and leakage from such equipment as valves and
pumps is of greater importance than in the processing of heavier
fractions.

-------
                                    7.6.10
        Air contaminants  released from regeneration operations involving
        combustion may include catalyst dust and other particulate matter,
        oil mists, hydrocarbons,  ammonia,  sulfur oxides,  chlorides, cyanides,
        nitrogen oxides,  carbon monoxide,  and aerosols.   The contaminants
        evolved by any one type of regenerator depend on  the compositions of
        the catalyst and  reactant,  and upon operating conditions.

                                                (3)
        Table 7.6.3 presents  results  of a  survey    of hydrocarbon emissions
        from refinery sources in  the  Los Angeles area,  interpreted in terms
        of emission factors related to throughput.   Although these estimates
        may serve to indicate the possible order of magnitude of such
        emissions from various operations,  they can be regarded as suggestive
        only.   More recent and more detailed methods of estimating effluent
                                                                   (2)
        rates can be found in the Air Pollution Engineering Manual.

3.  Marke ting
    An extensive network  of pipelines, terminals,  truck fleets,  marine
    tankers, and storage  and  loading  equipment must be used to deliver the
    finished petroleum product to the user.   Hydrocarbon  emissions from
    the distribution of products  derive principally from  storage vessels
    and filling operations.   Additional hydrocarbon emissions may occur
    from pump seals,  spillage, and effluent-water separators.  Table 7.6.4
    lists practical methods of minimizing  these emissions from this
    section of the industry.

-------
               Table  7.6.3.   HYDROCARBON  EMISSION FACTORS  FOR  REFINERY  SOURCES
                                   (SOURCE:   Chambers,  Reference  3)
SOURCE OF EMISSION
Fluid cntalv'ir cracking unit
Therniofor c.italyiic cracking unit
Crude oil storage tanks
Petroleum disiillat*1 storage tanks
Oil-water separators
Oil-water separators
Loading tank trucks & trailers (avg.)
Motor gasoline, 8-12 ibs. RVP
Aviation -,-isolnie, 4-8 Ibs. RVP
Other -Mediates, 1-4 Ibs. 1WP
Pump seals
Mechanical seals
Packed seals
Compressor seals
Compressor seals
Valves (How)
Valves (fiovv)
Relief valves
Relief valves ion process vessels'!
Cooling towers
Cooling tcweis
Treating units
Compressor exhausts
Slowdowns, turnarounds, ves;el & tank
EMISSION FACTOR
NO CUNTUOL
200
50
500
670
-100
300
150
375
170
90
125
	
5.0
G
8.5
23
0.5
80
2.9
10
ij
8
1
25
CONTROL
10

75(b'i
100(b)
8
I
2
5
2
1
20(c)
3.2
—
—
—
—
—
5
—
—
—
o
—
5
, ,
UNITS(a)
Lbs. per 1 .000 bbls. feed
Lbs per- 1,000 bbh feed
Lbs. per 1 000 bbls. ren'ncry crude
Lbs. per 1,000 bbls. rchriery cilldrt
Lbs. per' 1.000 hbls. refiners' crude
Lbs. pei- 1.000 bbls. waste water
Lbs. per hOi.O bbls. loaded "
Lbs. per 1.000 bbls. loaded'
Lbs. per 1 .000 bbls. loaded
f.bs. pei 1,000 bbls loaded
Lhs per 1.000 bbls. refinery crude
Lbs. per seal per day
Lbs. per seal tier day
Lbs. per 1,000 bbls. refinery crude
Lbs. pr--- s.v! per d,:y
l.bv pe; i.UOO bbls. refinery crude
Lbs. p<>r valve per day
Lbs. v>er i.0(;0 bbls. refinerv crude
Lbs. per \',dvo ]ier day
Lbs. per 1.000 bbls. refinerv crude
Lbs. per 1.000.000 pals, cooling wa
Lbs. pi'r LUi'O bbls. rcfinciv crn<'e
i -i'.s per 1 ,'!00 cubic feet gas burner
Lbs pnr 1,000 bi.ls. refinery crude


throughput
thi oughput
throughput
!
noug.ipu



throughput


t'nroughput

throughput

throughput

throughput
or
throughput
.
throughout
(a)  Factor^ are e.vpt essed in uiiit-. of poucds MP:  t .000 barrels of rermery  cruJe  throu^lipnt ^herr, in the  opinion of ihc;  r.Mthors,  the
    magnitude oi  the same r-ource  in dirfeicnt  icli'ienc's is rc'atCLl  approximate!1,' to tlvir throughputs. In some  cases the factois  are
    expressed in a second unit  which rtu^ht prove more convenient.
(b)  Floating roof controls. The Lie tor  uouU!  theoreticr be zero  for vapor recovei-y controls.
(c)  Control consists of using mechanical seals in place of packed seaK for light hydn.carbon  servuf.

-------
             Table  7.6.4.   SOURCES AND CONTROL OF HYDROCARBON
                             LOSSES FROM PETROLEUM MARKETING
                             (SOURCE:   Air Pollution  Engineering Manual, Reference  2)
       Source
                                                Control method
Storage vessels


Bulk-loading facilities


Service station delivery

Automotive fueling

Pumps

Separators

Spills, leaks
Floating-roof tanks; vapor recovery; vapor disposal; vapor balance;
pressure tanks; painting tanks "white

Vapor collection with recovery or incineration; submerged loading,
bottom loading

Vapor return; vapor incineration

Vapor return

Mechanical seals; maintenance

Covers; use of fixed-roof tanks

Maintenance; proper housekeeping

-------
                                    7.6.13
C.   AIR POLLUTION POTENTIAL OF PETROLEUM EQUIPMENT
    Presented here are abbreviated discussions of the functions and potential
    emissions associated with various types of equipment used in the petroleum
    industry, especially in refining.  For further detail,  the reader is
    referred to the Air Pollution Engineering Manual.

    1.   Refining Equipment

        a.   Flares and Slowdown Systems
            Refinery process units and equipment are periodically shut  down
            for maintenance and repair.  Losses from this source are sporadic,
            occuring perhaps once in six months to two years,  in most cases.
            Hydrocarbons purged during shutdowns and startups  may be manifolded
            to blowdown systems for recovery or flaring.   Vapors can be
            recovered in a gas holder or compressor and discharged to the
            refinery fuel gas system, or they may be vented to flares or
            venturi burners.  Good instrumentation and properly balanced
            steam-to-hydrocarbon ratios are needed to insure smokeless  flares.

        b.   Pressure Relief Valves
            In refinery operations, process vessels are protected from
            overpressure by relief valves.   Corrosion or  improper reseating
            of the valve seat results in leakage.  Proper maintenance through
            routine inspections, or use of  rupture discs, or manifolding the
            discharge side to vapor recovery or to a flare minimizes air
            contamination from this source.

-------
                            7.6.14
c.  Storage Vessels
    Tanks used to store crude oil and volatile petroleum distillates
    are a large potential source of hydrocarbon emissions.
    Hydrocarbons can be discharged to the atmosphere from a storage
    tank as a result of diurnal temperature changes, filling
    operations, and volatilization.  Control efficiencies of 85 to
    100 percent can be realized by vapor recovery or disposal systems,
    floating-roof tanks, or  pressure tanks.

d.  Bulk-Loading Facilities
    The filling of vessels used for transport of petroleum products
    is potentially a large source of hydrocarbon emissions.   As the
    product is loaded, it displaces gases containing hydrocarbons to
    the atmosphere.  An adequate method  of preventing these emissions
    consists of collecting the vapors by enclosing the filling hatch
    and piping the captured  vapors to recovery or disposal equipment.
    Submerged filling and bottom loading also reduces the amount of
    displaced hydrocarbon vapors.

e.  Catalyst Regenerators
    In various refining processes, catalysts become contaminated with
    coke during operation and must be regenerated or discarded.  Thus,
    for example, in catalytic cracking,  regeneration of the catalyst
    is a necessity and is achieved by burning off the coke under
    controlled combustion conditions. The resulting flue gases may
    contain catalyst dust, hydrocarbons, and other impurities
    originating in the charging stock, as well as the products of
    combustion.

-------
                            7.6.15
    The dust problem encountered in regeneration of moving bed type
    catalysts requires control by water scrubbers and cyclones,
    cyclones and precipitators, or high-efficiency cyclones,  depending
    upon the type of catalyst, the process, and the regenerator
    conditions.  Hydrocarbons, carbon monoxide, ammonia,  and  organic
    acids can be controlled effectively by incineration in carbon
    monoxide waste-heat boilers.  The waste-heat boiler offers a
    secondary control feature for gases from fluid catalytic  cracking
    units.

f.   Effluent-Waste Disposal
    Waste water, spent acids, spent caustic and other waste liquid
    materials are generated by refining operations and present
    disposal problems.  The waste water is processed through
    clarification units or gravity separators.  Unless adequate  control
    measures are taken, hydrocarbons contained in the waste water are
    emitted to the atmosphere.  Control may be achieved by venting the
    clarifier to vapor recovery and enclosing the separator with a
    floating roof or a vapor-tight cover.   Spent waste materials can
    be recovered or hauled to an acceptable disposal site.

g.   Pumps and Compressors
    Pumps and compressors required to move liquids and gases  in the
    refinery can leak product at the point of contact between the
    moving shaft and stationary casing.  Properly maintained  packing
    glands or mechanical seals minimize the emissions from pumps.
    Compressor glands can be vented to a vapor recovery system or
    smokeless flare.

-------
                            7.6.16
    The internal combustion engines normally used to drive the
    compressors are fueled by natural or refinery process gas.  Even
    with relatively high combustion efficiency and steady load conditions,
    some fuel can pass through the engine unburned.   Nitrogen oxides,
    aldehydes, and sulfur oxides can also be found in the exhaust
    gases.

h.  Air-Blowing Operations
    Venting the air used for "brightening" and agitation of petroleum
    products or oxidation of asphalt results in a discharge of
    entrained hydrocarbon vapors and mists,  and malodorous compounds.
    Mechanical agitators that replace air agitation  can reduce the
    volumes of these emissions.   For the effluent fumes from asphalt
    oxidation, incineration gives effective  control  of the hydrocarbons
    and malodors.

i.  Pipeline Valves and Flanges, Blind Changing, Process Drains
    Liquid and vapor leaks can develop at valve stems as a result of
    heat, pressure, corrosion, and vibration.   Regular equipment
    inspections followed by adequate maintenance can keep losses at a
    minimum.  Leaks at flange connections are  negligible if the
    connections are properly installed and maintained.  Installation or
    removal of pipeline blinds can result in spillage of some product.
    A certain amount of this spilled product evaporates regardless of
    drainage and flushing facilities.  Special pipeline blinds have,
    however, been developed to reduce the amount of  spillage.

    In refinery operation, condensate water  and flushing water must be
    drained from process equipment.  These drains also remove liquid
    leakage or spills and water  used to cool pump glands.  Modern

-------
                            7.6.17
    designs provide waste-water-effluent systems with running-liquid-
    sealed traps and liquid-sealed and covered junction boxes.   These
    seals keep the amount of liquid hydrocarbons exposed to the air
    at a minimum and thereby reduce hydrocarbon losses.

j•   Cooling Towers
    The large amounts of water used for cooling are conserved by
    recooling the water in wooden towers.  Cooling is accomplished by
    evaporating part of this water.  Any hydrocarbons that might be
    entrained or dissolved in the water as a result of leaking heat
    exchange equipment are discharged to the atmosphere.  Proper
    design and maintenance of heat exchange equipment minimizes this
    loss.  Process water contaminated with odorous material should
    not be piped to a cooling tower.

k.   Vacuum Jets and Barometric Condensers
    Some process equipment is operated at less than atmospheric
    pressure.  Steam-driven vacuum jets and barometric condensers are
    used to obtain the desired vacuum.  The lighter hydrocarbons that
    are not condensed are discharged to the atmosphere unless
    controlled.  These hydrocarbons can be completely controlled by
    incinerating the discharge.  The barometric hot well can also be
    enclosed and vented to a vapor disposal system.  The water of the
    hot well should not be turned to a cooling tower.

 1.  Effective Air  Pollution  Control Measures
    Control  of  air contaminants  can be  accomplished  by process  change,
    installation of  control  equipment,  improved  housekeeping,  and better
    equipment maintenance.   Some  combination  of  these  often  proves  the
    most  effective solution.   Table 7.6.5  indicates  various  methods  of

-------
                Table 7.6.5.  SUGGESTED CONTROL MEASURES  FOR REDUCTION OF
                                AIR CONTAMINANTS FROM PETROLEUM REFINING
                                (SOURCE:   Mr  Pollution Enginee~ing Manual, .Reference 2)
        Source
                                                      Control method
 Storage vessels


 Catalyst regenerators

 Accumulator vents

 Slowdown systems

 Pumps and compressors
 Vacuum jets

 Equipment valves

 Pressure relief valves

 Effluent-waste disposal


 Bulk-loading facilities

 Acid treating


 Acid sludge storage and
 shipping

 Spent-caustic  handling

 Doctor treating


 Sour-water treating


 Mercaptan disposal


Asphalt blowing

Shutdowns, turnarounds
Vapor recovery systems; floating-roof tanks; pressure tanks; vapor balance;
painting tanks white

Cyclones - precipitator - CO boiler; cyclones - water scrubber; multiple cyclones

Vapor recovery; vapor incineration

Smokeless flares - gas  recovery

Mechanical seals; vapor recovery; sealing glands by oil pressure; maintenance

Vapor incineration

Inspection  and maintenance

Vapor recovery; vapor incineration; rupture discs; inspection and maintenance

Enclosing separators; covering sewer  boxes and using liquid seal; liquid seals
on drains

Vapor collection with recovery or incineration; submerged or bottom loading

Continuous-type agitators with mechanical mixing;  replace "with catalytic
hydrogenation units; incinerate all vented cases; stop sludge burning
Caustic scrubbing; incineration; vapor return system; disposal at sea


Incineration; scrubbing

Steam strip spent  doctor solution to hydrocarbon recovery before air regen-
eration; replace treating unit with other,  less objectionable units (Merox)

Use sour-water oxidizers and gas incineration; conversion to ammonium
sulfate

Conversion to disulfides;   adding to catalytic cracking charge stock; incin-
eration; using material  in organic synthesis

Incineration; water scrubbing  (nonrecirculating type)

Depressure and purge to vapor recovery

-------
                                 7.6.19
        controlling most  air pollution sources  encountered  in  the  oil
        refinery.   These  techniques  are also  applicable  to  petrochemical
        operations.   Most of these  controls result  in  some  form  of economic
        saving.

2.   Waste-Gas Disposal Systems
    Large volumes  of hydrocarbon gases are produced in modern  refinery and
    petrochemical  plants.  Generally,  these gases are  used  as  fuel or  as
    raw material for further processing.  In  some instances, these gases
    have been considered  waste gases and burned,  producing  large volumes  of
    black smoke.  With modernization of processing  units, this method  of
    waste-gas disposal, even for emergency gas  releases, has become less
    acceptable to  the industry.

    Nevertheless,  refineries are still faced  with the  problem  of safe
    disposal of  volatile  liquids and gases resulting from scheduled
    shutdowns and  sudden  or unexpected upsets in  process units.  Emergencies
    that can cause the sudden venting of excessive  amounts  of  gases and
    vapors include fires, compressor failures,  overpressures in  process
    vessels, line  breaks, leaks, and power failures.

-------
                            7.6.20
A system for disposal of waste gases consists of a manifolded
pressure-relieving or blowdown system, and a blowdown recovery
system of flares for the combustion of the excess gases, or both.

Refinery pressure-relieving systems, commonly called blowdown systems,
are used primarily to ensure the safety of personnel and,protect
equipment in the event of emergencies.  In addition, a properly
designed pressure relief system permits substantial reduction of
hydrocarbon emissions to the atmosphere.

The preferred method of disposing of the waste gases that cannot be
recovered in a blowdown recovery system is by burning in a smokeless
flare.

A blowdown or pressure-relieving system consists of relief valves,
safety valves, manual bypass valves, blowdown headers, knockout
vessels, and holding tanks.  A blowdown recovery system also includes
compressors and vapor surge vessels such as gas holders or vapor
spheres.

The air pollution problem associated with the uncontrolled disposal
of waste gases is the venting of large volumes of hydrocarbons and
other odorous gases and aerosols.  The preferred control method for
excess gases and vapors is to recover them in a blowdown recovery
system and, failing that, to incinerate them in an elevated-type
flare.  Such flares introduce the possibility of smoke and other
objectionable gases such as carbon monoxide, sulfur dioxide, and
nitrogen oxides.  Flares have been further developed to ensure that
this combustion is smokeless and in some cases nonluminous.

-------
                             7.6.21
Smoke is the result of incomplete combustion.  Smokeless combustion
can be achieved by:   (1) adequate heat values to obtain the minimum
theoretical combustion temperatures,  (2) adequate combustion air,
and (3) adequate mixing of the air and fuel.

Combustion of hydrocarbons in the steam-inspirated-type elevated
flare appears to be complete.  Nevertheless, the results of a field
    (4)
test    on a flare unit such as this  indicate that the hydrocarbon
and carbon monoxide emissions from a  flare can be much greater than
those from a properly operated refinery boiler or furnace.

Other combustion contaminants from a  flare include nitrogen oxides.
The importance of these compounds depends upon the particular
conditions in a particular locality.

Other air contaminants that can be emitted from flares depend upon
the composition of the gases burned.  The most commonly detected
emission is sulfur dioxide, resulting from the combustion of various
sulfur compounds (usually hydrogen sulfide) in the flared gas.  Toxicity,
combined with low odor threshold, make venting of hydrogen sulfide to
a flare an unsuitable and sometimes dangerous method of disposal.  In
addition, burning relatively small amounts of hydrogen sulfide can
create enough sulfur dioxide to cause crop damage or local nuisance.

Materials that tend to cause health hazards or nuisances should not be
disposed of in flares.  Compounds such as mercaptans or chlorinated
hydrocarbons require special combustion devices with chemical
treatment of the gas or its products of combustion.

-------
                            7.6.22
Storage Vessels
a.  Types of Storage Vessels
    Storage facilities can be classified as closed-storage vessels
    including fixed-roof tanks,  pressure tanks,  floating-roof tanks
    and conservation tanks, and  open-storage vessels including open
    tanks, reservoirs, pits, and ponds.

    Closed-storage vessels are constructed in a  variety of shapes,
    but most commonly as cylinders,  spheres, or  spheroids of steel
    plate.  Capacities of storage vessels range  from a few gallons
    up to 500,000 barrels.

    Open tanks generally have cylindrical or rectangular shells of
    steel, wood, or concrete.  Reservoirs, pits, ponds, and sumps
    are usually oval, circular,  or rectangular depressions in the
    ground.  Any roofs or covers are usually of  wood with asphalt or
    tar protection.  Capacities  of the larger reservoirs may be as
    much as 3 million barrels.

    Some pressure tanks are designed to  operate  at pressures as high
    as 200 pounds per square inch, while others  may have pressure
    limits of only 2 pounds per  square inch.  Fixed-roof tanks operate
    within only a few ounces per square  inch gauge pressure.  The
    term "gastight," often applied to welded fixed-roof tanks, is
    misleading, as many such tanks have  free vents open to the
    atmosphere.  Others are equipped with "conservation" vents opening
    at very slight positive pressures.  Also, such appurtenances as
    hatches, relief vents and foam mixers may fail in service,
    resulting in vapor leaks.

-------
                            7.6.23
    Floating roof tanks are used for storing volatile materials, to
    minimize fire and explosion hazards.  Vaporization losses from
    older types of such tanks may be high.  Modern designs usually
    incorporate compartmented dead-air spaces and vapor traps which
    reduce this problem.

    Conservation tanks are vessels of variable volume provided by
    lifter-rooves, flexible diaphragms or floating blankets.  Open-top
    tanks and reservoirs can and should be covered, but vapor losses
    remain appreciable if any volatilizable material is stored.

Loading Facilities
Gasoline and other petroleum products are distributed from the
manufacturing facility to the consumer by a network of pipelines,
tank vehicle routes, railroad tank cars, and ocean-going tankers, as
shown in Figure 7.6.1.

As integral parts of the network, intermediate storage and loading
stations receive products from refineries by either pipelines or tank
vehicles.  If the intermediate station is supplied by pipeline, it
is called a bulk terminal, to distinguish it from the station supplied
by tank vehicle, which is called a bulk plant.  Retail service
stations fueling motor vehicles for the public are, as a general rule,
supplied by tank vehicle from bulk terminals or bulk plants.  Consumer
accounts, which are privately owned facilities operated, for example,
to fuel vehicles of a company fleet, are supplied by tank vehicles
from intermediate bulk installations or directly from refineries.

Gasoline and other petroleum products are loaded into tank trucks,
trailers, or tank cars at bulk installations and refineries by means
of loading racks.   Bulk products are also delivered into tankers at
bulk marine terminals.

-------
                             7.6.24
Figure 7.6.1.   REPRESENTATION OF GASOLINE DISTRIBUTION SYSTEM IN
               LOS ANGELES COUNTY, SHOWING FLOW OF GASOLINE FROM
               REFINERY TO CONSUMER
               (SOURCE:   Air Pollution Engineering Manual,
                         Reference 2)

-------
                            7.6.25
Loading racks  (Figure 7.6.2) are facilities containing equipment to
meter and deliver the various products into tank vehicles from
storage.

Marine terminals have storage facilities for crude oil, gasoline, and
other petroleum products, and facilities for loading and unloading
these products to and from oceangoing tankers or barges.  The loading
equipment is on the dock and, in modern terminals, is similar to
elevated-tank vehicle-loading facilities except for size.  A pipeline
manifold with flexible hoses is used for loading at older terminals.
Marine installations are considerably larger and operate at much
greater loading rates than inland loading installations.

When a compartment of a tank vehicle or tanker is filled through
an open overhead hatch or bottom connection, the incoming liquid
displaces the vapors in the compartment to the atmosphere.  Ordinarily,
but not always, when gasoline is loaded, the hydrocarbon concentration
of the vapors is from 30 to 50 percent by volume.

The volume of vapors produced during the loading operation, as well
as their composition, is greatly influenced by the type of loading
or filling employed.  The types in use throughout the industry may
be classified under two general headings, overhead loading and
bottom loading.

Overhead loading, presently the most widely used method, may be
further divided into splash and submerged filling.  In splash filling,
the outlet of the delivery tube is above the liquid surface during
all or most of the loading.  In submerged filling the outlet of the
delivery tube is extended to within 6 inches of the bottom and is
submerged beneath the liquid during most of the loading.  Splash filling
generates more turbulence and therefore more hydrocarbon vapors

-------
                       7.6.26
Figure 7.6.2.   AN OVERHEAD-CONTROLLED LOADING RACK
               (PHILLIPS PETROLEUM, LOS ANGELES, CA.)
               (SOURCE:  Air Pollution Engineering Manual,
                         Reference 2)

-------
                            7.6.27
than submerged filling does, other conditions being equal.  On
the basis of a typical 50 percent splash filling operation, vapor
losses from the overhead filling of tank vehicles with gasoline
have been determined empirically to amount to 0.1 to 0.3% of the
volume loaded.

Bottom loading equipment is simpler than that used for overhead
loading.  Loading by this method is accomplished by connecting a
swing-type loading arm or hose at ground level, to a matching fitting
on the underside of the tank vehicles.  All the loading is submerged
and under a slight pressure; thus, turbulence and resultant production
of vapors are minimized.

The method employed for loading marine tankers is essentially a
bottom-loading operation.  Liquid is delivered to the various
compartments through lines that discharge at the bottom of each
compartment.  The vapors displaced during loading are vented through
a manifold line to the top of the ship's mast for discharge to the
atmosphere.

In addition to the emissions resulting from the displacement of
hydrocarbon vapors from the tank vehicles, additional emissions
during loading result from evaporation of spillage,  drainage, and
leakage of product.

An effective system for control of vapor emissions from loading must
include a device to collect the vapors at the tank vehicle hatch
and a means for disposal of these vapors.

-------
                                7.6.28
5.  Catalyst Regeneration
    Modern petroleum processes  of  cracking,  reforming,  hydrotreating,
    alkylation,  polymerization,  isomerization,  and  hydrocracking are
    commercially feasible because  of  catalysts,  which accelerate specific
    reactions.   Different catalysts vary in  their effects.   One might,
    for example, increase oxidation rates while another might change the
    rate of dehydrogenation or  alkylation.

    Contact between the catalyst and  reactants  is achieved  in some
    processes by passing the reactants  through  fixed beds or layers  of
    catalysts contained in a reactor  vessel.  Contact in other processes
    involves simultaneous charging of catalyst  and  reactants to a
    reactor vessel and withdrawal  of  used catalyst  in one stream, and
    products and unreacted materials  in another stream.  The first
    process may be termed a fixed-bed system and the latter a moving-bed
    system.  Moving-bed systems may be  further  subclassified by the  type of
    catalyst and method of transporting it through  the  process.  Examples
    are the use of vaporized charge material to fluidize powdered catalyst,
    as in fluid catalytic cracking units (FCC),  and the use of bucket
    elevators,  screws, airlifts, and  so forth,  to move  the  catalyst
    pellets or beads, as in Thermofor catalytic cracking units (TCC).

    a.  Types of Catalysts
        Generally, the catalysts used are solids at process temperatures,
        though some are liquids.  Cracking catalysts are usually
        synthetic silica-alumina compositions,  including acid-treated
        bentonite clay, Fuller's earth, aluminum hydrosilicates, and
        bauxite.  Bead or pelleted catalyst  is  used in  TCC  units while
        powdered catalyst is used  in  FCC units.

-------
                        7.6.29
Catalysts employed in catalytic reforming include platinum-
containing catalysts used in fixed-bed reformers, and molybdena-
alumina catalysts used for fluid hydroforming.  These catalysts
contain less than 1% platinum supported on a base of either
alumina or silica-alumina.  Acid-type catalyst required for
reforming processes may be provided by one of the oxides as the
catalyst base.  The acid may be a halogen compound added to the
catalyst, or may be directly added to the reformer charge.  The
flow diagram of a platforming process is shown in Figure 7.6.3.

Commercial alkylation processes employ as catalysts either sulfuric
acid, hydrogen fluoride, or aluminum chloride with a hydrogen
chloride promoter.

Commercial polymerization catalysts consist of a thin film or
phosphoric acid on fine-mesh quartz, copper pyrophosphate, or a
calcined mixture of phosphoric acid.

Isomerization processes employ a noble metal, usually platinum,
as the catalyst in a hydrogen atmosphere.   Liquid-phase
isomerization is accomplished with aluminum chloride in molten
antimony chloride with a hydrogen chloride activator.

The activity of a catalyst decreases with on-stream time.   The rate
of decrease is related to composition of reactants contacted,
throughput rate, and operating conditions.   Loss of activity
results from metal contamination and poisoning or from deposits
that coat the catalyst surfaces and thus reduce the catalytic
area available for contact with the reactants.  Frequently carbon
from the coking of organic materials is the main deposit.   The
procedure of treating the spent catalyst for removal of

-------
                          7.6.30
p« 	
CHAftQ





E IHIEBHE«IEB|
" 1
CHARGE
PREHEAT ^

-------
                            7.6.31
    contaminants, called catalyst regeneration, is significant
    from the standpoint of air pollution, since combustion is
    frequently the method of regeneration.

    In fixed-bed systems, catalysts are regenerated periodically in
    the reactor or removed and returned to the manufacturer for
    regeneration.  In moving-bed systems, catalysts are continuously
    removed from the reactor, regenerated in a special regenerator
    vessel, and returned to the reactor.

b.   Regeneration Processes
    Catalysts for the catalytic cracking and reforming processes are
    regenerated to restore activity by burning off the carbon (coke)
    and other deposits from the catalyst surface at controlled
    temperature and regeneration air rates.   FCC units, all of which
    have continuous catalyst regeneration, have a coke burnoff rate
    of 5 to 10 times higher than TCC unit regenerators have.
    Fixed-bed reformer units and desulfurizer reactors may require
    regeneration only once or twice in a year.

    Flue gases from catalyst regenerators for FCC units pass  through
    cyclone separators for removal of most of the catalyst more than
    10 microns in size, through a steam generator, where process
    steam is made, through a pressure-reducing chamber to air pollution
    control units, and then to the atmosphere.  Final dust cleanup is
    accomplished by passing the effluent gases from the cyclone
    separators through an electric precipitator.  The gases from the
    precipitator are introduced into a carbon monoxide boiler where the
    sensible heat and the heat content of the CO is used to produce
    steam

-------
                        7.6.32
In a TCC unit, spent catalyst  (beads) from the base of the reactor
is steam purged for removal of hydrocarbons and lifted to a
hopper above the regeneration kiln.  Catalyst fines at this point
in the process are separated from catalyst beads and are collected
in a cyclone separator.  Spent catalyst beads drop through a
series of combustion zones, each of which contains flue gas
collectors, combustion air distributors, and cooling coils.
Regenerated catalyst from the bottom of the kiln is then
transferred to the catalyst bin for reuse in the reactor.

The largest quantities of air pollution from catalyst-regenerating
operations are experienced in fluidized cracking units.  The
pollutants include carbon monoxide, hydrocarbons, catalyst fines,
dust, oxides of nitrogen and sulfur, ammonia, aldehydes,  and
cyanide.  Typical losses from fluid catalytic cracking regenerators,
are given by Sussman.  '

An improvement made in FCC units in recent vears is a trend
toward the use of zeolite or "molecular sieve" type catalysts
replacing the older amorphous (high aluminum) catalysts.   As a
result of using this type catalyst, less particulate emissions
occur from the FCC regenerator.  Also,  refineries are tending to
make more use of hydrogen where it is now possible to build a
"hydrogen plant."  TCC units are beginning to phase out.

-------
                                7.6.33
        Thermofor catalyst regeneration produces air contaminants
        similar to those from fluid catalyst regeneration.  Quantities
        produced, however, are considerably less.  The bead-type catalyst
        used in TCC units does not result in the large amount of catalyst
        fines that are encountered in FCC units.

        Air pollution problems are not as severe from catalyst regeneration
        of reforming and desulfurization reactors as those from cracking
        units.  These reactors are regenerated only once or twice a year
        for a period of about 24 hours.  The burning of the coke and
        sulfur deposits yields hydrocarbons, carbon monoxide, and sulfur
        dioxide.

    c.  Air Pollution Control Equipment
        Dust from fluid cracking catalyst regenerators is collected by
        centrifugal collectors and electrical precipitators.   Carbon
        monoxide waste-heat boilers eliminate carbon monoxide and
        hydrocarbon emissions in regeneration gases.  Centrifugal dust
        collectors are used to collect the catalyst fines from Thermofor
        regeneration gas.

        The carbon monoxide and hydrocarbons in reforming and desulfuriza-
        tion catalyst regeneration gases can be efficiently incinerated
        by passing the regeneration gases through a heater firebox.  In
        some installations the sulfur dioxide is scrubbed by passing the
        regeneration gases through a packed water or caustic tower.

6.   Oil-Water Effluent Systems
    Oil-water effluent systems are found in the three phases of the
    petroleum industry—production, refining, and marketing.   The systems
    vary in size and complexity though their basic function remains the

-------
                            7.6.34
same, that is, to collect and separate wastes, to recover valuable
oils, and to remove undesirable contaminants before discharge of
the water to ocean, rivers, or channels.

In the production of crude oil, wastes such as oily brine, drilling
muds, tank bottoms, and free oil are generated.  Of these, the oilfield
brines present the most difficult disposal problem because of the
large volume encountered.

A typical collection system includes a number of small gathering lines
or channels transmitting waste water to a pit, a sump, or a steel tank.
A pump decants waste water from these containers to water-treating
facilities.  Any oil accumulating on the surface of the water is
skimmed off to storage tanks.

The effluent disposal systems found in refineries are larger and more
elaborate than those in the production phase.  A typical modern
refinery gathering system usually includes gathering lines, drain
seals, junction boxes, and channels of vitrified clay or concrete for
transmitting waste water from processing units to large basins or
ponds used as oil-water separators.  These may be earthen pits,
concrete-lined basins, or steel tanks.

A drawing of a typical separator is shown in Figure 7.6.4.

Factors affecting the efficiency of separation include temperature of
water, particle size, density, and amounts and characteristics of
suspended matter.  Stable emulsions are not affected by gravity-type
separators and must be treated separately.

-------
                       7.6.35
                              TRANSVERSE OPENINGS

                                 ELEVATION
Figure  7.6.4.   A MODERN  OIL-WATER SEPARATOR
                (SOURCE:   Air Pollution Engineering Manual,
                           Reference 2)

-------
                           7.6.36
The oil-water separator design must provide for efficient inlet and
outlet construction,  sediment collection mechanisms,  and oil skimmers.
Reinforced concrete construction has been found most  desirable for
reasons of economy, maintenance, and efficiency.

The effluent water from the oil-water separator may require further
treatment before final discharge to municipal sewer systems, channels,
rivers, or streams.  The methods include (1) filtration, (2) chemical
flocculation, and (3) biological treatment.

Biological treating units such as trickling filters,  activated-sludge
basins, and stabilization basins are capable of reducing oil,
biological oxygen demand, and phenolic content from effluent water
streams.  To prevent the release of air pollutants to the atmosphere,
certain pieces of equipment, such as clarifiers,  digesters, and
filters, used in biological treatment should be covered and vented
to recovery facilities or incinerated.

In the marketing and transportation phase of the industry,  waste water
containing oil may be discharged during the cleaning  of ballast tanks
of ships, tank trucks, and tank cars.  Leaky valves and connections and
flushing of pipelines are other sources of effluents.  The methods used
for treatment and disposal of these waters are similar to those used
in the other phases of the industry.

a.  The Air Pollution Problem
    Among contaminants emitted from liquid waste streams are hydrocarbons,
    sulfur compounds, and other malodorous materials.

-------
                            7.6.37
    These contaminants can escape to the atmosphere from openings in
    the sewer system, open channels, open vessels, and open oil-water
    separators.  The large exposed surface area of these separators
    requires that effective means of control be instituted to
    minimize hydrocarbon losses to the atmosphere from this source.

b.  Asphalt from Crude Oil
    Over 90% of all asphalt used in the United States is recovered
    from crude oil.  Distillation of topped crude under a high vacuum
    removes oils and wax as distillate products, leaving the asphalt
    as a residue.  Residual asphalt can be used as paving material or it
    can be further refined by airblowing.  Asphalt is also produced
    as a secondary product in solvent extraction processes.  The
    solvent, usually a light hydrocarbon such as propane or butane,
    is used to remove selectively a gas-oil fraction from the asphalt
    residue.

    Economical removal of the gas-oil fraction from topped crude,
    leaving an asphaltic product, is occasionally feasible only by
    airblowing the crude residue at elevated temperatures.  Excellent
    paving-grade asphalts are produced by this method.  Another
    important application of airblowing is in the production of high-
    quality specialty asphalts for roofing, pipe coating, and
    similar uses.  These asphalts require certain plastic properties
    imparted by reacting with air.

    Airblowing is mainly a dehydrogenation process.  Oxygen in the
    air combines with hydrogen in the oil molecules to form water
    vapor.   The progressive loss of hydrogen results in polymerization

-------
                               7.6.38
        or  condensation of  the asphalt to the desired consistency.
        Blowing  is  usually  carried out batch-wise in horizontal  or
        vertical stills equipped to blanket the charge with  steam,  but
        it  may also be done continuously.

        Effluents from the  asphast airblowing stills include sulfur
        compounds,  gases, odors, and aerosols.  Control of effluent
        vapors from asphalt airblowing stills has been accomplished by
        scrubbing and incineration.  Where removal of air pollutants  is
        not feasible by scrubbing alone, the noncondensables must be
        incinerated.
7.   Valves
    a.   Types of  Valves
        Valves are employed  in  every phase of the petroleum industry where
        petroleum or  petroleum  product is transferred by piping from one
        point to  another.  There  is a great variety of valve designs, but,
        generally,  valves may be  classified by their application as flow
        control or pressure  relief.

        Flow control  valves  are used to regulate the flow of fluids.
        These valves  are subject  to product leakage from the valve stem as
        a result  of the action  of vibration, heat, pressure, corrosion, or
        improper  maintenance of valve stem packing.

        Pressure  relief and  safety valves are used to prevent excessive
        pressures from developing in process vessels and lines.  The
        relief valve  designates liquid flow while the safety valve
        designates  vapor or  gas flow.  These valves may develop leaks
        because of  the corrosive  action of the product or because of

-------
                            7.6.39
    failure of the valve to reseat properly after blowoff.   Rupture
    discs are sometimes used in place of pressure relief valves.
    Their use is restricted to equipment in batch-type processes.   The
    maintenance and operational difficulties caused by the  inaccessi-
    bility of many pressure relief valves may allow leakage to become
    substantial.

b.  The Air Pollution Problem
    Quantitative data as to actual extent of emissions to  the
    atmosphere from this leakage are somewhat limited, but  available
    data indicate that emissions vary over a wide range. The results
    of a test program    conducted to establish the magnitude of
    hydrocarbon emissions from valves are presented in Table 7.6.6.
    In this program, valves in a group of 11 Los Angeles County
    refineries were surveyed.

    An example of low leakage rate was observed in one refinery where
    over 3,500 valves handling a wide variety of products under all
    conditions of temperature and pressure were inspected.   The
    average leak rate was 0.038 pound per day per valve.

    Examples of high leakage rates were found in two refineries where
    all 440 valves inspected in gas service had an average  leak rate
    of 1.6 pounds per day per valve, and in one other refinery where
    all 1,335 valves inspected in liquid service had an average leak
    rate of 0.32 pound per day per valve.

    These examples illustrate the wide divergence from the  average
    valve leak rate that can exist among refineries in a single area,
    all subject to the same obligations to restrict their  emissions
    to the greatest possible extent.  These results could  not be
    applied, even approximately, to refineries in other areas.

-------
                               7.6.40
      Table 7.6.6.  LEAKAGE OF HYDROCARBONS FROM VALVES OF
                     REFINERIES IN LOS  ANGELES COUNTY (1958)
                     (SOURCE:   Air Pollution Engineering Manual, Reference 2)


Total number of valves
Number of valves inspected
Small leaksa
Large leaks
Leaks measured
Total measured leakage, Ib /day
Average leak rate—large
leaks, Ib/day
Total from all large leaks,
Ib/day
Estimated total from small
leaks, lb/dayb
Total estimated leakage from
all inspected valves, Ib/day
Average leakage per inspected
valve, Ib/day
Valves in
gaseous service
31,000
2, 258
256
118
24
218

9. 1

1, 072

26

1,098

0.486
Valves in
liquid service
101, 000
7, 263
768
79
76
670

8.8

708

77

785

0. 108
All valves

132, 000
9, 521
1, 024
197
100
888

8.9

1, 780

103

1,883

0. 198
 Small leaks are defined as leaks too small to be measured—those estimated to
 be less than 0. 2 pound per day.
"Leaks too small to be measured were estimated to have an average rate of 0. 1
 pound per day.  This is one-half the smallest measured rate.

-------
                                7.6.41
        These testing programs were also conducted on pressure relief
        valves in the same oil refineries.   Relief valves on operational
        units have a slightly lower leak incidence but a much higher
        average leakage rate than valves on pressure storage vessels  do.
        Moreover, dual-type valves (two  single relief valves connected  in
        parallel to ensure effective release of abnormal pressures) on
        pressure storage vessels have a  greater leak incidence and  a
        larger average leakage rate than single-type valves  on similar
        service do.  For valves on operational vessels,  the  average for
        all refineries was 2.9 pounds of hydrocarbons per day per valve.
        Average losses from specific refineries,  however, varied from
        0 to 9.1 pounds per day per valve.   Under diverse conditions  of
        operation and maintenance, emissions can vary greatly from  one
        refinery to another.

8.   Cooling Towers
    Cooling towers are designed to cool, by air,  the water used to  cool
    industrial processes.  In one style  the prevailing wind  is used for
    the required ventilation.  It has become known as the natural draft
    or atmospheric type of cooling tower.   In contrast,  the  mechanical
    draft cooling tower employs fans to  move the air.  Spray ponds, once
    used extensively for cooling, have now  been abandoned in favor  of
    towers.

    The performance of an individual cooling tower is governed by the
    ratio of weights of air to water and the time of contact between  the
    air and water.  The required tower size is dependent upon:  (1) cooling
    range (hot water minus cold water temperature);  (2)  approach  (cold
    water minus wet bulb temperature); (3)  amount of liquid  to be cooled;
    (4) wet bulb temperature; (5) air velocity through cell;  and
    (6) tower height.

-------
                            7.6.42
Cooling towers used in conjunction with equipment processing
hydrocarbons and their derivatives are potential sources of air
pollution because of possible contamination of the water.  The cooling
water may be contaminated by leaks from the process side of heat-
exchange equipment, direct and intentional contact with process streams,
or improper process unit operation.  As this water is passed over a
cooling tower, volatile hydrocarbons and other materials accumulated
in the water evaporate into the atmosphere.  When odorous materials
are contained in the water, a nuisance is easily created.
        /o \
A survey    of the oil refineries operating in Los Angeles County
indicated emissions varied from 4 to 1,500 pounds per cooling tower
per day.  Apparently the amount of hydrocarbon present in the water
depends upon the state of maintenance of the process equipment,
particularly the heat-exchange equipment, condensers, and coolers
through which the water is circulated.  The quantity and type of
emissions should be determined by observing and testing each tower
individually.

The control of hydrocarbon discharges or of release of odoriferous
compounds at the cooling tower is not practical.  Instead, the
control must be at the point where the contaminant enters the cooling
water.  Hence, systems of detection of contamination in water, proper
maintenance, speedy repair of leakage from process equipment and piping,
and good housekeeping programs in general are necessary to minimize
the air pollution occurring at the cooling tower.  Water that has
been used in contact with process streams, as in direct-contact
or barometric-type condensers, should be eliminated from the cooling
tower if this air pollution source is to be completely controlled.
Greater use of fin-fan coolers can also control the emissions
indirectly by reducing or eliminating the volume of cooling water to be
aerated in a cooling tower.

-------
                                7.6.43
9.  Miscellaneous Sources
    A number of relatively minor sources of air pollution contribute
    approximately 10% of the total hydrocarbon emissions to the atmosphere
    from refineries    including airblowing, blind changing,  equipment
    turnaround, tank cleaning, use of vacuum jets, and use of compressor
    engine exhausts.
    a.  Airblowing
        In certain refining operations,  air is blown through heavier
        petroleum fractions for the purpose of removing moisture or
        agitating the product.  The exhaust air is laden with hydrocarbon
        vapors and aerosols, and, if discharged directly to the atmosphere,
        is a source of air pollution.  Results of a survey    show emissions
        of less than 1/2 ton per day.  These refineries operated a total
        of seven airblowing units with a combined capacity of 25,000
        barrels per day and a total airflow rate of 3,300 cfm.   (This does
        not include airblowing of asphalt, which has been disucssed
        elsewhere in this chapter.)  Emissions may be minimized by replacing
        the airblowing equipment with mechanical agitators and incinerating
        the exhaust vapors.

    b.  Blind Changing
        Refinery operations frequently require that a pipeline be used for
        more than one product.  To prevent leakage and contamination of
        a particular product, other product-connecting and product-feeding
        lines are customarily "blinded off."  "Blinding a line" is the
        term commonly used for the inserting of a flat, solid plate between
        two flanges of a pipe connection.  In opening, or breaking, the
        flanged connection to insert the blind, spillage of product in
        that portion of the pipeline can occur.

-------
                        7.6.44
Emissions to the atmosphere from the changing of blinds can be
minimized by pumping out the pipeline and then flushing the line
with water before breaking the flange.   In the case of highly
volatile hydrocarbons,  a slight vacuum may be maintained in the
line.  Spillage resulting from blind changing can also be
minimized by use of "line" blinds which do not require a complete
break of the flange connection during the changing operation.

Equipment Turnarounds
Periodic maintenance and repair of process equipment are essential
to refinery operations.  A major phase  of the maintenance is the
shutting down and starting up of the various units, usually
called a turnaround.

In general, shutdowns are effected by first shutting off the heat
supply to the unit and circulating the  feed stock through the
unit as it cools.  Gas oil may be blended into the feedstock to
prevent its solidification as the temperature drops.  The cooled
liquid is then pumped out to storage facilities, leaving hydro-
carbon vapors in the unit.  The pressure of the hydrocarbon vapors
in the unit is reduced by evacuating the various items of
equipment to a disposal facility such as a fuel gas system, a
vapor recovery system,  a flare, or in some cases, to the
atmosphere.  Discharging vapors to the  atmosphere is undesirable
from the standpoint of air pollution control.  The residual
hydrocarbons remaining in the unit after depressuring are purged
out with steam, nitrogen, or water.   Any purged gases should be
discharged to disposal facilities.  Condensed steam and water
effluent that may be contaminated with hydrocarbons or malodorous
compounds during purging should be handled by closed water-treating
systems.

-------
                             7.6.45
d.  Tank Cleaning
    Storage tanks in a refinery require periodic cleaning and repair.
    For this purpose, the contents of a tank are removed and residual
    vapors are purged until the tank is considered safe for entry by
    maintenance crews.  Purging can result in the release of
    hydrocarbon or odorous material in the form of vapors to the
    atmosphere.  These vapors should be discharged to a vapor recovery
    system or flare.

    Steam cleaning of railroad tank cars used for transporting
    petroleum products can similarly be a source of emissions if the
    injected steam and entrained hydrocarbons are vented directly to
    the atmosphere.  Some measure of control of these emissions may
    be effected by condensing the effluent steam and vapors.  The
    condensate can then be separated into hydrocarbon and water
    phases for recovery.  Noncondensable vapors should be incinerated.

e.  Use of Vacuum Jets
    Certain refinery processes are conducted under vacuum conditions.
    The most practical way to create and maintain the necessary
    vacuum is to use steam-actuated vacuum jets, singly or in series.
    Barometric condensers are often used after each vacuum jet to
    remove steam and condensable hydrocarbons.

    The effluent stream from the last stage of the vacuum jet system
    should be controlled by condensing as much of the effluent as is
    practical and incinerating the noncondensables in an afterburner
    or heater firebox.   Condensate should be handled by a closed
    treating system for recovery of hydrocarbons.  The hot well that
    receives water from the barometric condensers may also have to
    be enclosed and any off gases incinerated.

-------
                                    7.6.46
        f.   Use of Compressor Engine Exhausts
            Gas compressors  are often driven by internal combustion engines
            that exhaust contaminants to  the atmosphere.   Although these
            engines are normally fired with natural gas  and operate at
            essentially constant loads, some unburned  fuel passes through the
            engine.  Oxides  of nitrogen are also found in the exhaust gases
            as a result of nitrogen fixation in the combustion cylinders.

D.  INSPECTION POINTS AND PROCESS INVENTORIES
    1.  Initial Inspection Procedures
        Due to the operational complexity of petroleum refineries,  petrochemical
        and chemical plants  and other allied activities,  a degree of specializa-
        tion,  training, and  considerable  experience is required on the part of
        an  effective refinery inspector.   For such  industries it is necessary
        to  prepare technical reports of processes in terms of both written and
        graphic presentation to describe  and determine the air pollution
        potentials of the process units being inspected.   Special inventory
        forms  for various types of equipment,  operations,  processes,  or plants
        are helpful at inspections to ensure coverage  of  specific points.   This
        procedure is required for these reasons:
        •    Because similar  process  vessels  are used in various  source  activities
            and are grouped  in interdependent  relationships,  attempts  to individually
            itemize pieces of equipment often lead  to  confusion and
            disorientation.

        •    Air pollution potentials can  be  better  determined from  an  inventory
            of  functions  of  process  vessels,  than from itemization  of  equipment
            units.   Process  inventories may  also require  field surveys  of
            product flows, throughput  capacities, and  emission factors.

-------
                            7.6.47
•   Refinery and chemical plant inventories thus categorize,
    itemize, and present data as will directly determine not  only
    compliance with permit regulations, but also with equipment
    regulations.

To collect such information, a special inventory system is adapted to
each refinery.  In order to adequately cover each of the multiple
operations of a refinery or large petrochemical plant, a system of
unitization is used in which the plant area is subdivided into
process units.  (Those units with the greatest air pollution  potentials
are subsequently given added emphasis by assigning higher rates of
inspection.)

Plant ownership data is recorded separately on a Plant Card.   It is
most important to know who the responsible officials are and  how they
can be quickly contacted either by a field inspector or by telephone.
Where accurate field data exists in the inventory files, it is
possible to make a preliminary investigation of refinery problems by
telephone.

To insure that the other refineries in the area continue to receive
surveillance when the inspector is busy at one refinery, the  areas in
which the refineries are situated are sectioned and carefully checked
by patrols using a Refinery Check Sheet.  On this sheet each  refinery
to be checked is listed.  The time of observation is noted, along with
any pertinent remarks concerning significant observations of  each
refinery.  Such remarks include notations of odor, visible emissions,
wind direction, etc.

-------
                            7.6.48
The inventory records for each refinery or petrochemical plant
consist of a group of file folders,  each folder dealing with one of
the process units.  One or more process units may constitute what has
been defined as the Source Activity.  Hence,  one inspection or
inventory is made of one or more process units programmed as a unit
for reinspection.  At the head of each refinery file group is a
numbered index of all distinct source activities within the refinery.
Each number is cross-referenced to the location of the folder
containing the appropriate source activity.

Within the folder for a given source activity, the following types of
records should appear.

•   A general description of the process including an analysis of its
    purpose and function in the order of the  flow or processing
    sequence.  Generally, the analysis traces the flow of materials
    from introduction through various sidestreams to final effluents.
•   A list of the various pieces of  equipment contained in the process
    unit and their function.
•   The air pollution potentials of  the process or the equipment
    should include an analysis of any important problems.  This
    discussion should include, if possible,  estimates of the
    contaminants emitted and their chemical designations, odor quality
    and intensity, opacities, or physiological effects, as well as
    the potential hazards of the stocks or products released should
    equipment failure occur.

•   Throughput of volatile materials and estimates of emissions from
    known sources.  This may be determined from results of "material
    balances," e.g., estimates of sulfur derivatives lost as
    calculated from the differences  between input and final output.

-------
                            7.6.49
•   Results of any tests made of effluents or samples taken of fuels
    or other materials.
•   A process flow chart and plot plan, which can be used for reference
    and verification on followup inspections and which indicate the
    flow rates, pressures, temperatures, etc., in process vessels and
    lines, where necessary, to estimate air pollution potentials and
    to locate points of emission.

Flow charts and plot plans are systematically drawn according to
conventional engineering rules.  All pertinent liquid or gas feed
lines are shown and all gas or liquid effluents indicated.  Overhead
discharge and drainage from columns or vessels are generally shown by
vectors indicating method of disposal.  All features not essential to
the understanding of the air pollution problem are omitted.

The flow lines are clearly labeled and vectored as to direction and
content.  For example:  "Refinery Gas in," "To Fuel Gas System," "To
Oil-Water Separator," etc.  The process lines indicate whether the
flow originated in, or entered at the top, side, or bottom of columns
or equipment.  Equipment or columns should be clearly labeled as to
function unless they can be depicted by symbols (such as heat
exchangers, condensers, etc., and by plant number as shown in
Figure 7.6.5).  It is of utmost importance in a flow diagram to
clearly illustrate all sources of air pollution, including stacks,
flares, pressure relief valves, etc., and to identify the problem
areas and the contaminants which might be emitted.  Process vessel and
line operating conditions recorded on pressure and temperature gauges,
manometers, continuous recorders, and relief valve pressure settings,
should be indicated wherever pertinent.

-------
                      PRESSURE
                      VACUUM VALVE
                               flASTE
                               H,0 TANK
                               10006
                                         90%HZS04	J
\u
PRV

f) L.LA.

NEUTRALIZING COLUMN
C-130

SOUR WATER PUMP








to.5 TON/DAY H?S


I

111

u

FOUL AIR

IT1 RINGS
STEAM
*—
SWEET
^GAS FROM
ZDDEA
WB1IRHFB
JL





U

r/A
f\/ /
5t_X


. PLANT AIR
                     1950 B'D FROM
                     VARIOUS ACCUM.
                                                  	>• FLARE

                                               —PQ	» L-P H?S ABSORBER
                                                                               ]so.no
                                                                               TO 500,000
                                                                               CF/D.
IDEGASIEIER DRUM
                                                             WASTE WATER
                                                             STRIPPER C-13!
                                                             3'. 35'H
                                  OXIDIZING
                                  COLUMN C-13t
                                                                                                          -» VAPOR RECOVERY
                                                                                                             SYSTEM


                                                                                                             TO'Reforming
                                                                                                           -  UNIT
                                                                                                             ABSORBER
                                                                                                          * VAC. HEATER
                                                                                                                TO COVERED
                                                                                                               » WASTE WATER
                                                                                                                SEPARATOR
                                                                                                        COOLER
                                                                                                        E-«9
NAME OF REFINERY _

NAME OF UNIT 	

DATE INSPECTED 	
                                         FLOW DIAGRAM

                                     Oil Comply, Inc.    tnnRFSS   »25 Court StM.t
                                   w&ter oxidizing
                               10/15/59
                                                       INSPECTOR J'R
                                                 REVISIONS

                                     DATE OF REVISION       PERMIT NO - MODIFICATIONS
                                     V3/60	  031)97	
C^

o
Figure  7.6.5.    PROCESS  FLOW DIAGRAM OF  A  SOUR WATER OXIDIZING UNIT  FROM A FIELD DRAWING
                       (PAGE  4  OF  THE ACTIVITY  STATUS REPORT)

-------
                            7.6.51
A sample of an Activity Status Report covering a sour water treatment
and disposal plant, and accompanying flow charts, is shown in
Figures 7.6.5 and 7.6.6.  To assist the inspector both in evaluating
and illustrating the process, symbols may be employed in chart
preparation as shown in Figure 7.6.7.

Some types of source activities are so standard that routine inventory
forms are used in describing them.  Such activities include bulk
plants, truck loading facilities, oil-effluent water separators,
tanks, natural gasoline plants, and some other types of plants
operated at production facilities.  Examples follow.

a.  Bulk Plant Data
    This inventory form (Figure 7.6.8) is used to record data obtained
    from inspection of loading racks, storage tanks, pumps, vapor
    controls, and associated equipment located at bulk plants.  Bulk
    plants are used to store and distribute various petroleum products
    and may be found at airport facilities, distributing centers,
    marine terminals, etc.  The form is used to emphasize compliance
    of equipment and operation with the applicable rules.  This Bulk
    Plant Data Sheet, presents a master inventory for each bulk plant.

    Notice (in the sample shown in Figure 7.6.8) that by increasing
    the number of spouts observed during the 7-8-57 reinspection the
    permit status changed.  A Permit Request was appropriately
    written ("P.R.").

b.  Truck Loading Inspection Data Sheet
    This inspection sheet (Figure 7.6.9)  is made for each truck
    loading facility.  It lists the number of racks and spouts, the
    permit status of each rack, and throughputs of tank truck loading
    racks.

-------
         ACTIVITY STATUS REPORT

FIRM NAVE; Sunrise Chi Company.  Inc., Unit II
ADDRESS OF  PREVISFS:  1325 Court Street
RESPONSIBLE  PERSCN rnMTVTFn-  J. B.  Hickeaon
NATURE OF BUSINESS:   Petroleum refining
                                                       M.R.Ko.  | 01  |  1
                                                       CITY;  Onyx
                                                       TITLE;PI»
          ASSIGNED  INSPECTION D     NEW ACTIVITY Q     CHANGE OF STATUsD
       DESCRIPTION  - GENERAL USAGE •  NAfcE OF EQUIPKENT - SYSTEM OR PROCESS
       INSPECTED; Sour water oxidizing unit - Unit II
       INSPECTOR'S NAIVE:   J, B,  Hardy
                                                      naTF-  10-15-59
       INSPECTOR'S CONCLUSIONS AND RECOVMENDATIONSi The odors detected at this
       time  were not great enough to  result in a public nuisance. This unit
       remains, however,  one of the greatest potential  sources of odor problems
       in  this refinery since it comprises the processing area for sour waste
       water containing malodorous components formed during the cracking
       operation.
            Modifications made for compliance with Rule 62 have reduced the
       possibility of excessive S02 emissions from the  vacuum heater. Since the
       materials processed are both highly malodorous and corrosive, the
       present inspection frequency of three times per  year should be continued
       to  insure adequate maintenance.
       INSPECTOR'S  FINDINGS: The purpose of this unit is to deodorize the
       sour  water pumped from the accumulators at the crude, thermal, and cat-
       alytic cracking units. This consists of the following equipment:
        (1) a 10,000 barrel cone-roof tank, (2) a neutralizing column tower,


                                                                PAGE 1 OF  4
  (3)  a waste-water stripper,  (4) an aeration column, (5) a waste-water
  cooler,  (6) a sour water degasifier drum, and (7)  necessary pumps,
  piping,  and instrumentation. These are shown in the attached flow
  diagram.
     The  sour water is pumped  from the accumulators  to  the degasifier
drum.  The gas removed from this drum flows through a back pressure reg-
ulator valve to a low pressure f>2S removal plant.
     The  sour water and waste  caustic are collected  in  the 10,000 bbl.
capacity  tank venting to the vapor recovery system.
     The  sour water is pumped  from the tank to the neutralizing column
where it  contacts 9856 sulfuric acid. The mereaptans  released  from the
water by  the sulfuric acid, along with other waste gases in the over-
head line from the caustic regeneration unit, are condensed and fed
into the  cracking unit for conversion to H2S and recovery. This ac-
counts for the disposal of roost  of the mercaptans in the system.
     The  neutralized water is then pumped  to the waste-water  stripper,
and live  steam is introduced in  the  column to strip out H2S and mer-
captans.  Sweet gas with 7 or less grains of H2S per 100 CF from the
secondary scrubber at the H2S removal plant is introduced into the bot-
tom of the stripper at the rate  of 350,000 to 500,000 CF/D- to sweep  the
released  gases from the water. This  sour gas  from the stripper goes  to
the H2S absorption plant. A pressure relief valve on the stripper  vents
to the flare.
     The  stripped water then flows to an aeration column where it  is
contacted counter-currently with an  air stream and caustic and is  oxi-
dized to  non-odorous thiosulfate. The resulting  foul air from this
vessel is sent to the firebox of the vacuum unit heater for deodorizing.

                                                         PAGE 2 OF 4
                                                                                                                                                                   
-------
                                       Inr  wnier flo«s  from t lie  bottom of the  aerater through a cooler to the




                                       the  principle sources of  air  pollution  at this unit  resulted  from the

                                       introduction uf  (1) mercaptans  from the neutralising tnnfc to  the burn-

                                       ers  of the vacuum unit heater,  and (2)  the HjS from  the waste-water

                                       stripper column  to the refinery fupl gas system.  The APOD test  team

                                       determined that  previously 0,S  ton/day  of f^S was contributed by this

                                       unit to the refinery fuel g«B system. This is, equivalent to a losa of.

                                       2f/j'". ibs dav ol  SC»2 to the atmosphere.  After studying data disclosed by


                                       • aste (Tds streams throughout  the  refinery. Rule 62 *aa introduced to




                                       Cfiis refinery adopted the following solutions to meet the problems


                                         a. Enlarged ita HjS absorption  facility.

                                         b. Made provision for  introduction of condensable  iiercaptana into

                                         th«! cracking plant  for conversion of  H2-S and its eventual recovery.


                                       found to comply with Rule 62  during a test conducted by the APCD test


                                            Vglieiole T*rcaptan odors **re noted in the vicinity of equip-

                                       -*:. t at tnis  '.ine. Equipment  was  in good condition and operating under

                                       f-t fTi i cofiaitLons and rerjuirefnents. No  visible emissions were observed

                                       at  trus tiT.e  from the vacuum  heater. A  sample of treated water  taken

                                       fror the cooler (after oxidation)  was free of noxious odors.
Figure  7.6.6.    ACTIVITY  STATUS  REPORT FROM AN  INSPECTION MADE OF  A SOUR  WATER  OXIDIZING UNIT
                        AT  AN OIL  REFINERY  (Continued)

-------
SYMBOLS USED IN PETROLEUM FLOW DIAGRAMS

Chart Number One
CENTRIFUGAL
PUIP
»/WCH SEAL Ofl
PACKED GLANDS
HEAT EXCHAKGER
STEAM 00 HOT OIL
UEQHM
VALVES


SHALL VALVES
RESSUREVACUUBVm
          NATION
        VEWT AND GAUGE
        HATCH
        HEAT EXCHANGERS
                                          Cdinn
                                          KcdEicUnta
                                          Vnscl
                      KEOOG HEATER   BORN HEATER     PETROCHEH
                                                            TYPES OF FLOATING ROOFS
                                                            Chart Number Two
                                                     10
                                                             11
                                                                  ft>
                                                                  (b-
                                                                                        cfl
                                                                                                  PAN TYPE
                                                                                                  TRUSSED
                                                                                                          PAN TYPE
                                                                                                          TRUSSED WITH
                                                                                                          SHADE OVER 50%
                                                                                                          8 VAPOR 0AM.
                                                                                                          DOUBLE DECK
                                                                                                          HIGH DECK
                                                                                                          PONTOON WITH
                                                                                                          CENTER PONTOON
                                                                                                          HIGH DECK
                                                                                                          PONTOON WITHOUT
                                                                                                          CENTER PONTOON
LOW DECK
PONTOON WITH
CENTER PONTOON
                                                                                                          LOW DECK
                                                                                                          PONTOON WITH
                                                                                                          CENTER WEIGHT
                                                                                                  PONTOON "DAY"
                                                                                                  TYPE WITHOUT
                                                                                                  CENTER PONTOON
                                                                                                          CLEAR DECK
                                                                                                          VENTILATED
                                                                                                          PAN WITHOUT
                                                                                                          SEAL
                                                                                                  VENTILATED
                                                                                                  PAN WITH
                                                                                                  WIPER SEAL
                 Figure  7.6.7.   SYMBOLS  USED IN  PETROLEUM  FLOW DIAGRAMS

-------
                         7.6.55
                        SULK PLANT DATA
                            ,  WO STCRIWG GASOLINE .
       00 GASOLIt   U lb».
UllTS LC*DtD %Ci    ISO	 wi Cf LADING RAOS


LENGTH OT RACKS    20 ft.	
                 LOSS    Fillin. nd brt.diiB. ol .
                            . NO 0* A f CONTROLS  	Flo.tia. roof.
              TOTAL MYOftOCABaON L053S
                                        y..  ,/t   jfefVlVt^C/,
                                       ^            J
 Figure  7.6.8.    BULK PLANT DATA SHEET

-------
TRUCK LOADING INSPECTION DATA SHEET
COMPANY
Sunrise Oil
Company
"
••
••
-vX^X_
LOCATION
1325 Court St.
Ohyx, Calif.
* i
1 1
1 1
^~^J
RACK
NO. OR
NAME
1
2
1
2
	 -^
GAL/DAY GASOLINE
TO TRUCKS
AVERAGE
23,000
26,000
24,500
26,000
-"^
MAXIMUM
28,500
30,000
47,000
30,000
—~^
SPOUTS
TOTAL
5
6
5
7
-•^
OVER
4#
RVP
2
2
2
2
	 -1
UNDER
4#
RVP
3
4
3
5
~- 	 ^
RULE
61
2
2
2
2
^~-_
PERMIT
STATUS
A-7432
A-4733
A- 473 2
P.R.
^
RECHECK


7-8-59
7-8-59
^^ 	
DATE
CONTROLS
FIRST
USED
12-1-56
••


^^
INSPECTED
BY
J.R.H.
J.R.H.
J.R.H.
J.R.H.
^ 	 ^_
Figure 7.6.9.   TRUCK LOADING INSPECTION DATA  SHEET

-------
                            7.6.57
    From this form, the total losses of hydrocarbons are determined
    using the following emission factors:
    •   Emission of hydrocarbons in gallons from uncontrolled
        equipment—Approximately 1/10 of 1 percent of the average
        gallon throughput per day.
    •   Emission of hydrocarbons in gallons from controlled equipment—
        8 percent of the above.

c.  Oil-Effluent Water Separator Inspection
    The example shown in Figure 7.6.10 is of a single refinery
    oil-effluent water separator which derives its influent from
    treating vessels, south tank farm, thermal and catalytic cracking
    units, and alkylation plants in the general cracking area of the
    refinery.  The influent waste water is traced on the flow diagram
    by the inspector.  The description of the controls, (i.e.,
    "floating roof on primary compartments") and other information
    indicates whether the equipment is in compliance with pertinent
    rules.

d.  Tank Inspection Report (Figure 7.6.11)
    This inventory form records the type of tank, vapor control,
    function, dimensions, products stored, Reid vapor pressure, storage
    temperature, etc., of each tank to determine compliance with
    rules.

e.  Data Sheet for Natural Gasoline, Gas, and Cycle Plants
    This form, illustrated in Figure 7.6.11, provides for inventory
    of plants such as those named, which may be located apart from
    refinery facilities, but in proximity to crude oil production
    facilities.   Information to be recorded includes the status of
    tanks and separators subject to emission control regulations.

-------
                                           7.6.58
                               OIL-EFFLUENT  WATER  SEPARATOR  INSPECTION



             OWANY   Sunriii! Oii.Coapm-r	DATE
                      1325 Court. Strwn,  OnyK.Caiif.
             DESIGNATION Of SEPARATOR   Oil-el




             D€SCRIPTtOU   A_remforced cmcrcl
                                                         _ CONVERSATION WIT
             iCTHOO Of SKIWING  * - 2" «»m mp« Mil folded to *' '
             SIZE OF  INLET ft OUTLET 	12" dl>.  inlet md pud




             LOCATION Or SEPARATOR —At »3 tretter  »r«.  in  i
             SIZE' LENGTH 	*7'-ll"	 •inn.   20'-10"
                                         . TOff-EBATUHE—
             QUANTITY ft DISPOSITION OF OIL  300 hhl./dm to oil  recoTtrY ftciiltY
             OISPOSITION OF WATER t ESTIMATE OF QUANTITY   15.000 bbliy
-------
                                                         7.6.59
                           ADDRESS  HOP BU». St.
                                                                                   Qiv«. Califom
                            INFORMATION BY  L. M. Black
                            TYPE OF PLANT: NATURAL GAaoLi


                           SOURCE OF MATERIAL PROCESSED WeL QB from e
                           THROUGHPUT: WET GAS   20   »*, sCFVi  DRY_
                                                                           _ TOTAL HO.  OF WELLS .
                                                                  _M4 SCFO
                                                                  PAHE(BBL) -
                           BOILERS: NUMBER
                                                          _ HEATERS:  NUMER .
                            IS FLOW DIAGRAM AVAILABLE „
                            STORAGE a HANDLING:
                                                        CAN IT BE OBTAINED1
                                  OTHER (SPECIFY)
                                  NO. CONTROLLED
                                 OTHEHISPECIFY)
                                                                      OIL_-_EFFLUENT WATER SEPARATORS
                                                                   NO. OF SEPARATORS.——!	
                                                                   NO. QUESTIONABLE —Kant.
                                                                   TYPE OF CONTROL _ Hone
                                                                   FLOATING ROOF   Hone	
NO. UNDER RULE 59  ™°q	
NO. CONTROLLED UNDER RULE 59 _
TOTALLY ENCLOSED _Mone	
                                                                   VAPOR RECOVERY SYSTEM
                            INSPECTOR'S REMARKS RE EQUIPMENT a PLANT CONDITIONS: —No lc«k»gea. Ma.1 oases noted.
Figure  7.6.11.     NATURAL  GASOLINE,   GAS,  AND  CYCLE  PLANT   SURVEY  SUMMARY

-------
                               7.6.60
2.  Inspection Points and Reinspection Procedures
    In order to maintain current information on the full extent and status
    of refinery air pollution problems and potential problems,  it is
    desirable to conduct major resurveys on a periodic basis.   Occasionally
    major surveys may appropriately be conducted in cooperation with
    other agencies, for joint objectives.  However, for routine surveillance,
    scheduled inspections of individual refinery units serve adequately.
    Frequency of the inspections scheduled for any given unit will be
    consistent with the expected potential of that type of unit for the
    development of problems.

    Most inspections of process units in refineries are arranged in
    advance, as a part of the systematic programming of inspections.  Such
    arrangements are necessary in order to assure that the process unit is
    in operation, that the appointed specialist in the plant is available,
    and for safety precautions and guidance.   When the process  unit is
    ready for reinspection, the inspector checks out the field  file and
    reviews the previous reports, and then proceeds to the inspection.

3.  Environmental Observations
    The environment in the vicinity of refineries and other petroleum
    operations should be periodically surveyed for odors and for damage
    to vegetation and materials.  Findings should be compared with
    observations of residents in neighboring  communities.   Soiling of
    surfaces of automobiles, residences and other structures should be
    noted and, where found to be severe, should be investigated.  In
    particular, any pattern of increasing intensity of soiling  or
    staining in the immediate vicinity of the subject facility  should
    be studied, to aid in the possible detection of previously  unrecognized
    emissions.

-------
                            7.6.61
Odors of hydrocarbon vapors and gases are likely to be particularly
prevalent near petroleum production and refining facilities.  When
intense, they indicate the occurrence of high emission levels, since
odor thresholds for these compounds are relatively high and their
quality not especially offensive.

Sulfur compounds associated with crude oil production and with some
refinery operations are more readily detectable by odor.  Sulfur
dioxide may be produced by combustion of fuels or waste gases, for
example in boilers, catalyst regenerators, incinerators and flares.
This gas has an acrid, suffocating odor with a threshold of about
1 ppm.  Reduced sulfur compounds, including hydrogen sulfide, various
mercaptans and other sulfur-bearing organics, have characteristically
highly offensive odors and very low threshold levels, which have been
                                                            (9)
estimated at less than 1 ppb.  (See, for example, Douglass.   )

In reporting on occurrences of odors allegedly caused by petroleum
facilities, the inspector should note wind conditions (speed as well
as direction) at the time of his observations, and he should develop
a systematic procedure for patrolling and for characterizing odors.

Odors may be described on an intensity scale in terms of subjective
evaluation, or standardized procedure may be established, using a
scentometer or other comparison device.  A community odor pannel can
help to establish the significance of day-to-day variations in odor
intensity and quality of the ambient atmosphere, as well as to alert
the inspector to the occurrence of unusual conditions.

Sulfur compounds, particularly hydrogen sulfide, can discolor and
damage lead-based paints sometimes found in residential areas.  They
also accelerate tarnishing of silver and copper surfaces.

-------
                                7.6.62
    Sulfur dioxide and trioxide may also be responsible for certain
    types of damage to vegetation,  causing yellow to brown blotchy spots
    on many varieties, and occasionally a sort of pock-marking injury
    which may be associated with sulfuric acid mist formed from the
    trioxide.  Diagnosis of plant damage due to air pollutants is
    difficult, however, and should be confirmed by a consultant
    experienced in the field.

4.   The Physical Inspection
    The objectives of the air  pollution inspector are not only to
    determine which elements of the operation are affected by the Rules and
    Regulations but to determine as well the degree of compliance to them.
    His inspection procedures  are adapted to the specific air pollution
    requirements governing the type of unit being inspected.

    Safety is a prime consideration and all refineries have standard safety
    procedures for employees and visitors.  Accordingly,  the inspector is
    equipped with a hard hat,  goggles, safety flash light; l^S indicator;
    any other safety device the specific type of unit being inspected
    calls for.

    The inspector is accompanied to the unit or units to  be inspected, by
    the air pollution representative within the plant or  by such other
    informed refinery personnel as he might indicate.

    General unit or plant compliance is determined through sensory
    evidence, examination of current and past records, plans, recorder
    charts and gauges, obtaining samples for laboratory analysis,
    on-the-spot testing or calling for a mobile field test unit for more
    extensive determination of suspected sources of noncompliance.

-------
                           7.6.63
a.  Investigation of the Methods Used and the General Efficiency
    Achieved in Controlling the Release of Pollutants to the Atmosphere
    from Process (Basic Equipment) Units
    The inspector determines plant procedures employed during start-ups,
    shut-downs and equipment malfunctions, to control or eliminate
    the discharge to atmosphere of noxious or malodorous emissions
    through the purging or depressuring of tanks or vessels.  These
    include the installation of special instrumentation, e.g., high
    level or high pressure alarms, liquid knock-out drums on fuel gas
    systems, pressure relief or manually controlled discharge from
    process equipment to blow-down vessels of either variable or fixed
    capacity which are served by vapor recovery compressors, flare
    systems or both, and, where emissions are a factor,  fixed roof
    tankage tie-in to properly sized vapor recovery or fume disposal
    systems.  Loading racks should be tied to vapor control systems
    when the product being loaded has a significant vapor pressure.

b.  Determination of Quality of Maintenance on Such Points as Manual,
    Pressure Vacuum Valves, Flanges, Pump Glands, Gauge Hatches, etc.,
    which May be a Source of Leakage
    Such emissions are primarily recognized by sensory evidence and
    their detection depends on the ability of the inspector to
    recognize the odor and to trace it to its point of origin.

    The inspector must also note any visible air turbulence caused by
    light hydrocarbon leakage, frosting of valves or pump glands
    caused by light hydrocarbon evaporation, liquid leakage, local
    area discolorations caused by vapor condensate, visible emissions
    or changes in flow (surging) of an emission, extinguished flare
    pilot lights or detection of audible gas leaks.  These may disclose
    a violation or a potentially critical situation that could be
    corrected in time.

-------
                             7.6.64
c.  Procedures Used in Controlling Air Contaminants and Odors Resulting
    from Disposal of Process Waste Effluents
    The refinery inspector should thoroughly survey the sour water,
    waste water, sour gas, spent caustic and acid sludge gathering and
    processing and fume disposal systems.

    Even though in a modern refinery most of these streams are "treated,"
    their extremely noxious and malodorous characteristics make even
    the most isolated uncontrolled streams a potential source of air
    pollution problems.

    Wherever possible, the inspector should point out conditions having
    a high air pollution potential so that the refinery technical
    staff may have the opportunity to assess the problem and arrive at
    a solution.  More effective use of existing control equipment is
    achieved by extending its service to as many uncontrolled sources
    as is possible without overloading its capacity.

    The inspector may find (1) isolated streams of sour gas fuel
    untreated for H-S removal and recovery; (2) sour  water discharged
    to open drains with live steam which has not been first
    deodorized by processing in sour water oxidation  or H-S stripping
    facilities; (3) odors and hydrocarbons emitted to the atmosphere
    from oil-water separators; (4) malodorous or noxious acid sludge,
    stored in uncontrolled tanks which release fumes  and odors due to
    breathing and filling losses, or loaded into tank cars and trucks
    with similar results.

e.  Investigation of Efficiency, Operating Load and Maintenance of
    Control Equipment
    The effective operation of various control systems in a refinery
    is of basic importance to efficient air pollution control.  Such
    equipment as cyclones, electrostatic precipitators, vapor recovery

-------
                        7.6.65
plants are subject to severe corrosion and other destructive
forces which reduce air pollution control efficiency.  In addition,
a change in process feed or feed rates due to altered product
requirements may also result in overloaded or otherwise upset
operating conditions in the air pollution control system.

In the case of a vapor recovery system serving tankage, peak loads
develop in the morning hours when the heat of the sun produces
maximum volumes of hydrocarbon vapors in the space above the
liquid.  Uneven loading schedules at tank truck loading facilities
tend to create a similar situation.

Since a gradual reduction in control efficiency does not always
alter the effective operation of the process unit, it may not be
noted by operating personnel until a major breakdown occurs
accompanied by a serious air pollution situation such as a public
nuisance.  It is therefore essential for adequate air pollution
control that such areas be inspected regularly and frequently.

This type of inspection is sometimes more complex.  Sensory
evidence such as visible discharge and odors may be disclosed by
thorough physical inspection and may be sufficient in some
situations to determine noncompliance or abnormal operation
(breakdown), i.e., Ringelmann number readings, excess hydrocarbon
vapor discharge from vapor controlled tankage, etc.  However, in
other cases, sensory evidence may only be a preliminary or
corroborating step to the investigation, either because the
regulations affected call for evidence not obtainable in this
manner, (e.g., percentage sulfur in the fuel oil, H_S grain loading
in gaseous products burned and its btu value, weight of particulate

-------
                        7.6.66
discharge, concentration of SO- in discharge of flue gas) or
because the control equipment does not discharge a waste effluent
directly to the atmosphere.  In such cases the inspector must
either rely on data indicating temperature, density, pressure,
vacuum or throughput recorded on gauges, continuous recorders,
high level or density alarms, voltmeters and ammeters, or he
must provide for special testing.

Another aid to the inspector is the information incorporated in
applications to operate the equipment.  The permit status of
equipment should be routinely checked, in order to detect any
changes in equipment or process that might invalidate an existing
permit, or conflict with variance conditions.

-------
                                     7.6.67
                                   REFERENCES


 1.  Elkin, H. F.  Petroleum Refinery Emissions.   In:   Air Pollution,
     A. C. Stern (ed.).   Vol. 3, New York City, Academic Press,  1968.

 2.  Danielson, J.  A., (ed.).  Air Pollution Engineering Manual,  DREW,
     PHS 999-AP-40, 1967.  Chapter 10, Petroleum  Equipment,  pp.  561-677.

 3.  Chambers, L. A.  Technical Developments Pertaining to Smog.   Presented at
     the Fourth Annual Waste Disposal and Stream  Pollution Conference  of  the
     Western Petroleum Refiners Association.  Wichita,  Kansas.   October  7-8,
     1959.

 4.  Sussman, V. H., R.  K. Palmer, F. Bonamassa,  B.  J.  Steigerwald,  and
     R. G. Lunche.   Emissions to the Atmosphere from Eight Miscellaneous
     Sources in Oil Refineries.  Joint District,  Federal and State Project for
     the Evaluation of Refinery Emissions.  Los Angeles County Air Pollution
     Control District.  Report No. 8.  June 1958.

 5.  Deckert, I. S., R.  G. Lunche, and R. C. Murray.  Control of Vapors  from
     Bulk Gasoline Loading.  J. Air Pollution Control Association,
     8:223-233, 1958.

 6.  Sussman, V. H.  Atmospheric Emissions from Catalytic Cracking Unit
     Regenerator Stacks.  Joint District, Federal and State Project  for  the
     Evaluation of Refinery Emissions.  Los Angeles  County Air Pollution
     Control District.  Report No. 4.  June 1957.

 7.  Kanter, C. V., R. G. Lunche, F. Bonamassa, B.  J.  Steigerwald, and
     R. K. Palmer.   Emissions to the Atmosphere from Petroleum Refineries in
     Los Angeles County.  Joint District, Federal and State Project  for  the
     Evaluation of Refinery Emissions.  Los Angeles  County Air Pollution
     Control District.  Report No. 9.  1958.

 8.  Bonamassa, F., and Y. S. Yee.  Emissions of  Hydrocarbons to the Atmosphere
     from Cooling Towers.  Joint District, Federal and State Project for  the
     Evaluation of Refinery Emissions.  Los Angeles  County Air Pollution  Control
     District.  Report No. 5.  August 1957.

 9.  Douglass, I. B.  The Chemistry of Pollutant  Formation in Kraft  Pulping.
     In:  Proceedings of the International Conference on Atmospheric Emissions
     from Sulfate Pulping, E. R. Hendrickson (ed.).   PHS, National Council for
     Stream Improvement.  University of Florida,  April 28, 1966.

10.  Brandt, C. S., and W. W. Heck.  Effects of Air Pollutants on Vegetation.
     In:  Air Pollution, Vol. I, A. C. Stern (ed.).   New York City,  Academic
     Press, 1968.

-------
                                     7.7.1
                             VII.   CHEMICAL PLANTS

A.  NATURE OF SOURCE PROBLEM - UNIT PROCESSES AND UNIT OPERATIONS
    The definition of what constitutes a chemical industry rests more on
    accepted practice than on clearly distinguishing features.   The processing
    of metal ores, the manufacture of synthetic rubber and Pharmaceuticals,
    and the production of synthetic fertilizers all involve significant chem-
    ical reaction steps.   However, in each case the industries  are so large
    and the end use of the products so clearly visualized that  they have come
    to be separately classified.

    Nevertheless, the chemical industry can be broadly classified as one in
    which a basic, intermediate,  or end use chemical compound is produced
    through one or more chemical  reactions, followed by a series of separation
    and purification steps.  A few examples of some of the chemical products
    are chlorine, sulfuric acid,  nitric acid, phosphoric acid,  caustic soda,
    ammonia, soda ash, and synthetic organic chemicals including elastomers,
    fibers, resins, plastics, pesticides, dyes, adhesives and solvents.

    Both gas phase and particulate air contaminants may result  from chemical
    plant processes.  Gaseous contaminants may be either true gases or vapors
    arising from volatile liquids and solids.  Contaminants may be unreacted
    starting materials, unwanted  by-products, or non-recovered  product.

    In many cases contaminants arise from the purging of inert  gases that are
    deliberately or inadvertantly introduced by a process.  For example, if
    air is used as a source of oxygen for an oxidation step in  a chemical
    process, the nitrogen remaining must be vented to the atmosphere.  Unless
    adequate controls are utilized some air contaminants may be released along
    with the vented gases.

-------
                                     7.7.2
    In many cases, gaseous products of a reaction are absorbed in water (for
    example, mineral acids).   A small amount of gaseous material may not be
    absorbed and thus lost to the atmosphere unless otherwise controlled in
    what are known as tail gases.

    Volatile organic liquids  are a problem mainly during their storage and
    transfer.  Vapors of these materials may be lost as a result of filling
    and breathing losses (see Section VI, Petroleum Refineries).

    Liquid and solid particulates may be formed from gaseous reactions, gas-
    liquid reactions, gas-solid reactions,  drying operations (powders), cal-
    cining, attrition losses, materials handling, and from fluidized catalyst
    beds, to give only a partial list of sources.

B.  PROCESS DESCRIPTION - UNIT PROCESSES AND UNIT OPERATIONS
    Chemical engineers involved in the design of chemical plants have for many
    years classified commonly used reactions and manufacturing steps into two
    broad groups known as (1) unit processes, and (2) unit operations.   Unit
    processes are those procedures which involve a chemical change in one or
    more reactants.   Unit operations generally involve only physical changes.

    The utility of the above  concepts lies  in the ability to use unified
    design theories  for most  of the manufacturing steps required for even a
    very complex manufacturing process.  For the purposes of this section the
    use of these classifications is intended to allow a broad look at the
    industry without undue detail.  Relatively complete individual treatment
    is provided in Parts D and H of this section in the case of two large
    chemical industries—sulfuric acid manufacturing and vinyl chloride produc-
    tion.

-------
                                7.7.3
1.  Unit Processes
    The fundamental reactions that may be involved in a chemical manufac-
    turing industry would include decomposition, double decomposition,
    addition, substitution, isomerization, coupling, oxidation,  reduction,
    and polymerization.  Specific examples of these general reactions,
    which are in rather widespread use, are shown in Table 7.7.1.
    Groggins    presents a detailed review of most of these processes.   A
    brief discussion of the air pollution emission potential of  several of
    these processes follows.

    a.  Nitration
        Nitration involves the formation of organic nitro compounds and is
        usually accomplished by a mixture of nitric and sulfuric acids.  One of
        the principal potential sources of air pollution would be the
        recovery by concentration of spent nitric acid.  Nitrogen oxides
        may be released unless specific control measures are utilized.
        Figure 7.7.1 is a schematic flow diagram of a methane nitration
        process for the production of nitromethane.  In this process the
        product nitromethane and unreacted nitric acid are condensed
        following the reaction and the nitromethane recovered by distilla-
        tion.  The dilute (spent) nitric acid is fed to an absorption
        tower through which non-condensible reaction gases containing
        nitrogen oxides are passed.  Following the absorber some of the
        inert gases, mostly nitrogen, must be purged.  Small quantities
        of nitrogen oxides may also be lost.

    b.  Sulfonation and Sulfation
        These processes use oleum and sulfuric acid to produce a great
        variety of organic sulfonates and sulfates.  Sulfur oxides may  be
        lost in small quantities.

-------
                            7.7.4
          Table 7.7.1  COMMONLY USED UNIT PROCESSES
      Unit Process
           Product  Examples
Nitration






Amination by Ammonolysis






Diazotization and Coupling







Halogenation






Sulfonation and Sulfation







Hydrolysis







Oxidation







Hydrogenation







Friedel-Crafts Reactions







Polymerization







Calcining
Nitromethane







Aniline







Benzenediazonium chloride






Vinyl chloride







Naphthalene sulfonic acid






Glycerol







Quinone







Methanol







Ethyl benzene







Polyethylene






Silica gel

-------
    Nitric
     Acid
Methane
                                                                    Purge Point
                                                                  For Inert Gases
                           Figure 7.7.1  FLOW  DIAGRAM FOR NITRATION OF METHANE

-------
                            7.7.6
c.   Halogenation
    Halogens,  i.e.,  chlorine,  bromine and iodine are added to organic
    compounds  by this process.  Either the halogen or the hydrohalogen
    may be lost to the atmosphere.   (See the vinyl chloride process
    described  later  in this section.)

d.   Amination  by Ammonolysis
    Amination by Ammonolysis describes the process of amine production
    using ammonia.  Tail gases may contain ammonia after the condenser
    serving the purification rectifier.

e.   Hydrolysis
    In this process  a portion of the water molecule is made to replace
    another substituent.  For example, phenol is produced by the hydro-
    lysis of chlorobenzene.  Acid vapors (hydrogen chloride in the
    case of phenol production) may be lost without proper control.

f.   Oxidation
    Describes  the process by which the oxidation state of a substance
    is increased.  For example, air may be used to oxidize acetaldehyde
    to acetic  acid.   The nitrogen remaining after this process must be
    vented (purged)  and may contain traces of reactants or products.
    A great number of oxidizing agents, including chlorine sodium
    chlorite,  permanganates, chlorates, chromic acid, nitric acid,
    and nitrogen tetroxide may be used under this general heading.

g.   Hydrogenation
    Hydrogenation involves the addition of hydrogen.  Examples would include
    hydrogenation of vegetable oils and the production of methanol from
    carbon monoxide and hydrogen.  Again the purging of inert gases

-------
                                7.7.7
        may contain reaction by-products.  In the future this process may
        be used on a large scale for coal gasification.

    h.  Friedel-Crafts Reactions
        Friedel-Crafts includes a large group of reactions in which
        aluminum chloride is used as a catalyst.  Hydrogen chloride may
        be released as a by-product.

2.  Unit Operations
    That sub-group of unit operations which has in common the transfer of
    material from one homogeneous phase to another is described by the
                       (2)
    term mass transfer.     Except for the transfer and size classification
    of dry materials in particle form, the mass transfer operations are,
    from the point of view of air pollution control, the most important of
    the unit operations.

    That group of operations grouped under the mass transfer term is
    differentiated from purely mechanical separation techniques by the
    fact that they utilize differences in vapor pressure and solubility
    rather than variations in particle size and density as the basis for
    separation.  Several of the more important mass transfer operations
    together with examples of possible atmospheric emissions are given in
    Table 7.7.2.

3.  Control Methods
    Air pollution control methods used in chemical process plants do not
    differ inherently from those used in other industries.  Those differ-
    ences which do exist  are largely a matter of degree.  In general there
    are probably more air pollution problems in chemical plants related to
    fixed gases, volatile vapors, and liquid mists than there are those
    related to solid aerosols and combustion contaminants.

-------
                                    7.7.8
              Table 7.7.2  EXAMPLES OF MASS  TRANSFER OPERATIONS
                           AND AIR POLLUTANT POTENTIAL
 Mass Transfer
   Operation
         Principle
        Air Pollutant
           Example
Absorption
Soluble gas removed from an
inert gas by absorption in
a liquid.
Residual ammonia lost along
with vented air after absorp-
tion by water.
Evaporation and
  Drying
Volatile liquid removed from
non-volatile liquid or
solid by application of
heat.
Removal of solvent from
desired by-product by passage
of heated air or spray drying
of powders and flake material.
Distillation
Separates by volatilization
a mixture of miscible and
volatile substances.   Vapor
must differ in composition
from boiling liquid.
Loss of alcohol vapors after
separation of alcohol and
water by distillation.
Condensation
Removal of condensible vapor
from inert gas by cooling.
                                                Loss  of odorous  materials  to
                                                water used  in contact (baro-
                                                metric)  condenser,  and subse-
                                                quent loss  from  water.

-------
                                    7.7.9
        The techniques most commonly used for air pollution control  are  listed
        below and described more completely in Chapter 2.

              Control Methods Common to the Chemical Industry
                              Absorption
                              Adsorption
                              Condensation
                              Vapor Recovery
                              Fume Incineration

C.  INSPECTION POINTS - UNIT PROCESSES AND UNIT OPERATIONS
    Perhaps the single most important factor in the inspection of a  chemical
    plant is the degree to which the inspector is familiar with the  process(es)
    involved.  One of the best means of preparation is to  examine a  detailed
    process flow diagram and accompanying descriptive text, identifying  all
    possible sources of pollution and the location of all  vents to the atmo-
    sphere.  At the time of inspection this flow sheet can be much more  easily
    related to the plant layout plan and the equipment itself.  It is nearly
    inevitable to the uninitiated that continuous flow chemical plants
    (as well as petroleum refineries) will resemble a jungle of vessels, pumps,
    and piping.

    Once on the plant site, all vents, regular and emergency, should be  located
    on the plot plan indicating approximate size and height.  Where  relatively
    small quantities of inert gases (such as air) are involved the vents may
    actually be quite small and easily overlooked.

    The inspector should obtain an up-to-date description of all processes,
    including feed rates and composition and the variations that occur in these
    items.  Should pollutant emissions be unusually sensitive to production
    rates, this data on production should be obtained.

-------
                                    7.7.10
    The inspector should become familiar with both internal and external con-
    ditions during normal operations,  i.e.,  control instrumentation readout,
    presence of visible emissions,  and detectability of  odors in the surround-
    ing area.

    One useful approach is to make  inquiry as to  the nature and probability of
    occurrence of conditions  which  would necessitate the instigation of
    emergency  venting procedures.   Of  similar importance is the determination
    of the effect of a rapid  shut-down of all operations.

    Non-routine operations,  such as start-up, catalyst regeneration, scheduled
    maintenance, etc., should be studied as  to their effect on air pollutant
    emissions.

    Finally, regular surveillance of the surrounding area should be conducted
    to examine for evidence of possible effects related  to emissions from the
    plant in question.  Should complaints be received, it will be extremely
    important  to make a timely determination of the plant operating conditions
    associated with the time  of the detected effects.  Meteorological data
    related to the transport  and diffusion of contaminants, and detectability
    of effects should be obtained.   These include wind speed and direction,
    atmospheric stability, and relative humidity.   In most cases the inspector
    should make independent estimates  of these parameters even though he
    suspects such data may be available from weather instrumentation.

D.  NATURE OF  SOURCE PROBLEM - SULFURIC ACID MANUFACTURING
    The manufacture of sulfuric acid,  regardless  of the  process, results, to
    some degree, in the emission of unconverted sulfur dioxide and unabsorbed
    sulfuric acid mist.  In plants  using the lead chamber process, nitrogen
    oxides may be discharged  in concentrations nearly as high as the sulfur

-------
                                7.7.11
dioxide emitted.  Of these nitrogen oxides, usually 50-60% is nitrogen
        (3)
dioxide.     Only traces of nitrogen oxides are normally emitted from the
contact process sulfuric acid plants, which account for over 90% of the
sulfuric acid produced in the United States.

Variable amounts of a variety of mineral dusts may be lost from plants
using smelter or ore roasting gases as a source of sulfur.  Sulfuric acid
vapor as opposed to sulfuric acid mist, will be in equilibrium with the
sulfuric acid produced and will be lost in small quantities.

Other small, but possibly nuisance forming losses from sulfuric acid plants
could include wind blown raw sulfur from storage piles, odors from spent or
sludge acid storage tanks, leaks of sulfur dioxide or acid mist from
process vessels under pressure, sulfur trioxide vapor from oleum storage
and transfer.

Unless considerable care is taken there is great potential for increased
emission rates of sulfur dioxide during start-up operations.

Although sulfuric acid manufacturing accounts for only about 2% of the
total sulfur oxides emitted to the atmosphere in the United States
(approximately 600,000 tons of S09 per year out of a 28,600,000 tons per
                   (4)           /
year total in 1966)    any given sulfuric acid plant can be a significant
local source.  As compared to fuel burning sources of sulfur oxides,
sulfuric acid plants are distinguished by several features which can add
to the local nuisance potential—(1) low tail gas temperatures and some-
times short stacks which in combination result in poor stack gas dispersion
and occasionally high ground level concentrations of sulfur dioxide and
acid mist, (2) presence of sulfuric acid mist as well as sulfur dioxide,
and (3) odors from raw materials and the finished product.

-------
                                   7.7.12


E.  PROCESS DESCRIPTION - SULFURIC ACID MANUFACTURING
    The basic reaction in the manufacture of sulfuric acid is:


    This reaction is exothermic with the higher equilibrium concentration of
    SO  being favored by lower temperatures.  Slower reaction rates,  however,
    accompany the lower temperatures necessitating a careful heat balance to
    achieve high SO  to SO  conversion at practical reaction rates.   It is
    obvious from the equation above that S0_ conversion is also favored by
    high 0  to SO  ratios.

    Two processes are in use in the United States  for the manufacture of sul-
    furic acid.   The older chamber process produces a relatively weak 60°Be
    (77.7%) acid and accounts for less than 10% of the production in  the
    United States.  Nitrogen oxides are used as a  catalyst for  the conversion
    of sulfur dioxide to sulfur trioxide.  The contact process  involves the
    direct conversion of sulfur dioxide to sulfur  trioxide over a vanadium
    pentoxide catalyst and produces concentrated sulfuric acid  (98-100%) and
    various strengths of oleum (concentrated sulfuric acid having additional
    absorbed sulfur trioxide).  All new sulfuric acid plants are of  this type.

    In both chamber and contact processes hydration of the sulfur trioxide
    takes place during absorption operations producing the sulfuric acid.  The
    tail gases issuing from the final absorption tower contains excess air and
    any unreacted sulfur dioxide sulfuric acid mist, sulfur trioxide, sulfuric
    acid vapor,  nitrogen oxides and other contaminants that might be  present.

    1.  Chamber Process
        Presently operating chamber plants in the  United States use  sulfur as
        the raw material for the production of sulfur dioxide used in the acid
                              (3)
        manufacturing process.  '  In the chamber  process, as shown in

-------
                           7.7.13
Figure 7.7.2, sulfur is burned to sulfur dioxide which is introduced
together with nitrogen oxides (approximately equal proportions of
nitric oxide and nitrogen dioxide) to the Glover tower.  Here a
series of complex intermediate reactions are initiated between the
nitrogen oxides and the sulfur dioxide which culminate in the oxida-
tion of sulfur dioxide to sulfur trioxide and the release of the
nitrogen oxides.  The nitrogen oxides which are recovered in the Gay-
Lussac towers by absorption in chamber acid are also fed to the
Glover tower for recycling in the process.  Approximately 50% of the
sulfuric acid is formed in the Glover tower with the remaining con-
version taking place in large lead-lined chambers (thus the "Chamber"
process).
The range of emissions of air contaminants from chamber sulfuric acid
plants is approximately as shown below:
     S02            1500-4000 ppm
     Acid Mist      5-50 mg/ft3
     NO             ~1000 ppm
     NO             -500 ppm
Emission levels are affected by the concentration of sulfur dioxide
in the burner gas entering the Glover tower, the amount of nitrogen
oxides in circulation, the ratio of nitrogen dioxide to nitric oxide,
the throughput rate, and the temperature and concentration of acid
entering the final Gay-Lussac tower.  All other factors being equal,
lower atmospheric temperatures generally result in somewhat reduced
sulfur dioxide emissions because of the additional cooling of the lead
chambers by ambient air.

-------
                                                                        EXIT GAS AIR. SO... ACID MIST,

                                                                                  NO, AND NO,
                                                            78% TO ACID STORAGE
AMMONIA
OXIDATION
UNIT

OXIDES OF NITROGEN

SECONDARY AIR .
MOLTEN V"sn—

^
i
b
t'l
i
-k

1

                               //I'N
                                         GAS
                                         FAN


.


/ft. ,fi\
(One to twenty of
5,000 to 500.000
cu ft capacity each
in piants of various
capacities)




,
,fa /T-N A




                                                 ACID COLLECTING PAN
                                                                 ACID COLLECTING PAN
                                 I '
                                 i i
                              78%
                              ACID
                             (60'BE)
                   COOLING WATER

                          I	

                         i
                                              60 - 70%
                                              CHAMBER
                                               ACID
                                                                                          TO
                                                                                         STACK
MUTROUS
CHAMBER


1 1
VITRIOL
A£'l 	 	 _T"_
__^(__
1
•ill!


i :
AA
vm
                       78%
                      NITROUS
                      VITRIOL
    SULFUR
    BURNER
COMBUSTION
 CHAMBER
SUPPLY
 TANK
SUPPLY  PUMP
 TANK
Figure 7.7.2.   SIMPLIFIED  FLOW  DIAGRAM OF  TYPICAL LEAD-CHAMBER PROCESS  FOR
                  SULFURIC ACID MANUFACTURE  (BASED  ON USE OF  ELEMENTAL SULFUR
                  AS THE RAW  MATERIAL).   (SOURCE:   P.H.S., DIVISION OF AIR
                  POLLUTION,  Reference  3).

-------
                                7.7.15
2.   Contact Process
    A variety of contact processes are used in the manufacture of  sulfuric
    acid, differing principally in the source of sulfur and in the number
    of conversion stages used in the catalytic reactor.  Differences  in
    heat exchange equipment may occur, depending upon sources  and  demands
    for heat in the plant complex, but these differences should have
    relatively little impact on the air pollution potential of the plant.
    One likely future difference in new plants is the use of the double
    absorption process (see Chapter 2).

    Contact plants burning elemental sulfur are sometimes known as "hot
    gas" plants and utilize a drying tower for the combustion air  so  as
    to minimize the amount of moisture entering the converter along with
    the sulfur dioxide and excess air.  The presence of moisture in the
    converter results in the formation of sulfuric acid mist which must
    be removed from the tail gas.  Plants using hydrogen sulfide from
    refinery operations, acid sludge,  copper converter gases,  and  roaster
    gases from other sulfide ore smelters are often described as "wet gas"
    plants.  In these plants reactor gases are dried and cleaned just
    prior to entering the converter.  Combustion air for plants burning
    acid sludge and hydrogen sulfide is not dried as additional water is
    formed in the burner.

    Figure 7.7.3 shows a schematic flow diagram for a modern 4-stage  sulfur
    burning contact acid plant.  In this plant atmospheric air is  discharged
    from a pressure type blower into a drying tower through which  93-99%
    sulfuric acid is circulated as a drying agent.  The dry air together
    with molten sulfur is charged to the sulfur burner in such a ratio as
    to produce a feed gas containing 7.5-8.5 mol% sulfur dioxide,  about
    13% oxygen, and a nitrogen balance.  Should any hydrocarbon be present
    it will be burned to carbon dioxide and water.

-------
SULFUR*
BOILER
 FEED •
WATER
AIR
                                                                                     ••STEAM
                                                                               * OLEUM         .
                                                                                 TOWER (OPTIONAL)
                                                                                —
CONVERTER
   WITH
INTERCOOLERS
                                                                                                  OLEUM
                                                                                                r PRODljCT
                                              TAIL
                                              GAS
                                                                                                  ACID
                                                                                                 PRODUCTS
                             Figure 7.7.3.  SCHEMATIC FLOW DIAGRAM OF SULFUR BURNING PLANT
                                           WITH FOUR-STAGE CONVERSION.  (SOURCE:   CHEMICO.
                                           Reference 5.)

-------
                            7.7.17
The feed gases are cooled in a waste heat boiler to a temperature of
820°-840°F and then fed to the converter.  Interstage cooling is
necessary to remove the heat of reaction and to allow a satisfactory
degree of reaction to take place.  Conversion of sulfur dioxide to
sulfur trioxide in this type of plant can range up to 96-98%.

The converter gas is cooled in an economizer used for heating boiler
feedwater or in some other type of heat exchanger.  The converted
gases leave the economizer at about 450°F and enter the absorption .
tower where the sulfur trioxide is absorbed in a circulating stream
of 98-99% sulfuric acid.  In the event that oleum is to be produced,
the converter gases first pass through the oleum tower where acid from
the 98% absorber is circulated.  The gases must be cooled to a lower
temperature before entering the oleum tower than if only 98% acid were
to be produced.

Unless additional control equipment is used, the tail gases leaving
the absorption tower are discharged to the atmosphere at this point.
Typical tail gas concentrations from a 4-stage sulfur burning contact
acid plant are shown below:
so2
Acid Mist
SO,
1500-4000 ppm
2-20 mg./SCF
0.1-1.3 ppm
The "wet gas" type of contact plant using waste gases from metallurgical
operations, or acid sludge and hydrogen sulfide from refinery processing
is considerably more elaborate than the sulfur burning contact plant.
Sulfur dioxide containing gas from smelters may be contaminated by
metal fumes, dusts, acid mists, other gaseous impurities and water
vapor.  These must be removed by various dust collectors, mist

-------
                                    7.7.18
        precipitators and drying towers before the feed gases enter the con-
        verter.   Plants based upon the use of acid sludge,  spent acid or
        hydrogen sulfide are usually somewhat simpler than  those using waste
        smelter  gases in that there is less of a dust and fume contamination
        problem.   Figure 7.7.4 shows a simplified flow diagram of a "wet gas"
        contact  plant.   Although the heat balance may be substantially differ-
        ent for  this type of plant as compared to a sulfur  burning plant, the
        process  is essentially the same from the converter  forward.

        Some additional problems are encountered in plants  utilizing waste
        gases from metallurgical operations due to the possible variations in
        sulfur dioxide content.

F.  CONTROL METHODS - SULFURIC ACID MANUFACTURING
    Emissions from sulfuric acid plants are in the main unconverted sulfur
    dioxide (gaseous) and sulfuric acid mist (liquid aerosol).   Some nitrogen
    oxides may be lost from chamber plants and a small amount of unabsorbed
    sulfur trioxide may reach the final discharge stack. Any sulfur trioxide
    released will hydrate rapidly with atmospheric moisture and form additional
    sulfuric acid aerosol.
    Control methods are usually considered separately for sulfur dioxide and
    acid mist but in one approach to SO  tail gas  scrubbing a venturi scrubbe
    is proposed which would also remove some acid  mist.

    1.  Sulfur Dioxide Control
        Most existing sulfuric acid plants can reduce SO  emissions to
                                                              C3\
        approximately 2000 ppm by operational control methods.     Reduction
        to levels of 500 ppm or lower would require process changes such as
        the installation of a dual absorption system, or would necessitate
        tail gas treatment.

-------
BOILER
 FEED
WATER

SULFUR
SOURCE
                                                                                           STEAM (A)
                                                                                     OLEUM
                                                                                     TOWER (OPTIONAL)
                                                              CONVERTER
                                                                WITH      |
                                                             INTERCOOLERS
                                                                                               I  qLEUM_
                                                                                                 PRODUCT
                                                                                                TAIL
                                                                                                GAS
                                                                                                   ACID
                                                                                                  PRODUCTS
         ©INCLUDES COMBUSTION  UNIT  WHEN  USING  SLUDGE, PYRITE OR  H2 S.

            STEAM  IS GENERATED ONLY WHEN BURNING  SLUDGE OR H2 S  OR
            WHEN ROASTING  PYRITE.  NONE  IS GENERATED  WHEN  USING A
            PURIFICATION  UNIT  ONLY, AS  WITH  SMELTER  GAS.
                                   Figure 7.7.4.  SCHEMATIC  FLOW DIAGRAM WET GAS PLANT
                                                WITH 4-STAGE CONVERSION.  (SOURCE:
                                                CHEMICO, Reference 5.)

-------
                            7.7.20
Operational methods of sulfur dioxide control basically involve
enhancement of the sulfur dioxide conversion to sulfur trioxide.
Any one or a number of the following methods might be used.
     •  Reduce the initial sulfur dioxide concentrations
        entering the converter.
     •  Reduce the ratio of SO  to 0 .
     •  Increase the number of converter stages.
     •  Increase the volume of catalyst.
     •  Change catalyst more frequently and improve
        distribution.
     •  Improve uniformity of feed conditions.
     •  Reduce feed gas impurities.
     •  Provide additional interstage cooling in converter
        and improve temperature control throughout the plant.
     •  Reduce throughput rate.
     •  Exercise additional care during plant start up.

Reductions in sulfur dioxide emissions from contact acid plants may
also be achieved by incorporating the double absorption technique in
the process.  In this approach, which is mainly applicable to new
plants, conversion of SO  to SO. is interrupted after two or three
stages and the gas stream is fed to the first absorption tower.
Effluent gas from this tower now having a very high 0_/SO_ ratio
is returned to the converter where the new equilibrium conditions
favor an extremely efficient conversion of SO  to SO  .  Following an
additional one or two stages of conversion the converter gas is intro-
duced to the final absorption tower.  Overall conversion of  S0_ to SO

-------
                                7.7.21
    of +99.5% is achievable with this process.   Tail gas concentrations
    of 500 ppm SO- are readily attainable with the double absorption modi-
    fication of the contact process.   For existing plants,  another absorp-
    tion tower and probably some additional heat exchange equipment would
    be necessary.
    To attain sulfur dioxide concentrations of very much less than 500 ppm,
    some sort of tail gas treatment would probably be necessary.   In a
    recent report, prepared for the Air Pollution Control Office,
    nearly 50 possible tail gas treatment schemes were listed with nine
    being selected for a more detailed review.  Little use of tail gas
    treatment, however, is made in current practice.   Two plants  in the
    United States have used an ammonia scrubbing process on a full scale
    basis and one is engaged in pilot scale studies of the potassium
    sulfite-bisulfite (Wellman-Ford) process at the present time.   This
    situation is likely to change over the next few years.

2.   Sulfuric Acid Mist Control
    As can be seen from earlier portions of this section, acid mist
    emissions range from 2-20 mg/SCF (70-700 mg/M ) for most of the sul-
    furic acid plants operating in the United States.  Although sulfuric
    acid mist accounts for a relatively small proportion of the total
    sulfur losses (approximately 1-10%) from a sulfuric acid plant it is
    responsible for visible plumes and is associated with material damage
    and health effects at lower concentrations than is sulfur dioxide.
    There are a variety of operational and process factors which affect
    acid mist emissions.   Among these are:
         •  Improper concentration and temperature of the
            absorbing acid.
         •  Amount and concentration of oleum produced.

-------
                            7.7.22
     •  High content of organic matter in the raw materials
        of a sulfur burning plant.
     •  High moisture content of the sulfur dioxide entering
        the converter.
     •  Stack cooling of sulfur trioxide gases leaving the
        converter, i.e., sudden cooling below the acid dew
        point, resulting in condensation of very small
        particles.
     •  Presence of nitrogen oxides, which can result from
        excessive temperatures in the sulfur combustion
        chamber, from nitrogen in raw materials, and from
        arcing in electrical precipitators.
     •  Insufficient acid circulation and lack of uniformity
        of acid distribution in the absorption tower.
     •  Improper type or dirty packing in the 98% absorber.

Many sulfuric acid plants utilize some form of collection equipment
designed specifically for acid mist.  The most common type is the two-
                            T3
stage knitted wire or Teflon  mesh pad.  Such pads operate at rela-
tively low pressure drop (2-3" H_0) and are effective for acid mist
particles greater than 3 microns in size.  For particles less than 3
microns in diameter, such as result from oleum producing plants, the
efficiency is much lower (15-30%).  These smaller particles are
responsible for visible plumes and may be carried for considerable
distances in the atmosphere.

Venturi scrubbers operating at a pressure drop of about 35-40" H?0
have been used on acid concentrators where most of the acid mist
particles are > 3|a but recently have been proposed for combined use in

-------
                                    7.7.23
        removing both S0_ and acid mist from sulfuric acid plants.      Such
        units would not be expected to be effective for mist removal from
        oleum plants.

        The only devices capable of reducing all size ranges of acid mist to
        0.1 mg/SCF are glass fiber filters and electrostatic precipitators.
        Glass fiber filters presently in use operate at about 8" HO pressure
        d'rop.  Electrostatic precipitators operate at low pressure drops
        (about 1" H_0) but are initially quite expensive.  They are also
        rather large because of the low gas velocities necessary for efficient
        operation.

        Table 7.7.3 summarizes the expected performance for the acid mist
        collectors.

G.  INSPECTION POINTS - SULFURIC ACID MANUFACTURING
    The inspection of sulfuric acid plants must take into account the inter-
    connected, continuous nature of the manufacturing process, since there is
    essentially one point of emission for the major potential air contaminants.
    Though there may be some wind blown sulfur and even small amounts of sul-
    fur dioxide and hydrogen sulfide from sulfur storage and melting, all the
    sulfur dioxide, sulfuric acid mist, and nitrogen oxides arising from the
    manufacturing process will be emitted from the final absorption tower or
    from the control equipment following the tower.

    The emission potential of any given acid plant is dependent upon the type
    of process,  age of the plant, whether or not oleum is produced, nature of
    the raw material, production rate, operating variables, and type of control
    equipment.

-------
Table 7.7.3  EXPECTED PERFORMANCE  OF ACID MIST COLLECTION SYSTEMS
System
Wire or Teflon Mesh
Glass Fiber Filter
Electrostatic Precipitator
Venturi Scrubber

Efficiency
> 3 Microns
99+%
100%
99%
98%

Efficiency
<3 Microns
15-30%
95-99%
100%
Low

Emission Level
99% Acid Plants
to 2 mg/SCF
0.1 mg/SCF
0.5 mg/SCF
3 mg/SCF

Emission Level
Oleum Plants
to 5 mg/SCF
0.1 mg/SCF
0.1 mg/SCF
Ineffective
with <. 3 micron
mist
                                                                                         fo
                                                                                         -p-

-------
                               7.7.25
The major tasks the inspector performs include the following:  determina-
tion of the nature of the process as it affects air contaminant emission;
examination of operating conditions and relevant records; surveillance for
plume appearance (if any); determination of contaminant emission rates,
and investigation of possible property damage.

1.  Environmental Surveillance
    The only visual evidence of emissions from the contact process for
    sulfuric acid manufacture is the white plume associated in controlled
    acid mist having a particle size range generally less than three
    microns.  Particles larger than this do not scatter light in the
    visual wave length range effectively and thus may be present but not
    visible.  In the case of a chamber process plant it is possible that
    nitrogen oxides may be discharged from the Gay-Lussac tower in con-
    centrations high enough so that the reddish-brown color of nitrogen
    dioxide can be seen.

    Should there be a visible plume, the inspector may use it as a guide
    to locating those locations where ground level concentrations of
    sulfur dioxide and acid mist are high enough to be detectable by
    humans or to cause visible damage to materials and vegetation.
    Regardless of whether or not there is a visible plume the behavior of
    the plant effluent will be influenced by stack height, effluent gas
    temperature, wind speed and direction, atmospheric stability, and
    surrounding terrain.  It may be desirable in some cases to utilize a
    diffusion model to estimate ground-level concentrations in the
    surrounding area by various averaging times and for differing atmo-
    spheric conditions.  The application of these diffusion models is
    described in Turner's "Workbook on Atmospheric Dispersion Estimates."

-------
                                7.7.26
    Sulfur dioxide  and  sulfuric  acid mist  can cause localized damage to
    metals through  corrosion  and may attack a wide  variety of building
    materials,  causing  discoloration and deterioration.   These contaminants
    may also  cause  dyed fabrics  of  certain types  to fade.   Sulfur dioxide
    may cause acute or  chronic leaf damage to plants.   The symptoms most
    often observed  are  bleaching, yellowing,  or chlorosis.   Expert assis-
    tance is  usually necessary to confirm  the cause of  material or vegeta-
    tion damage,  but the inspector  may  be  trained to recognize prominent
    symptoms.  The  pattern of damage in the vicinity of a suspected source
    may provide valuable circumstantial evidence  as to  the probable cause
    of the damage.

2.   Inspection of the Premises
    a.  Interview
        In the case of  a sulfuric acid  plant most of the important informa-
        tion  obtained in a plant inspection will  be from the interview
        with  the  plant  management.  The continuous  enclosed nature of the
        manufacturing process precludes obtaining extensive information
        by visual inspection  alone.

        The inspector will first wish to learn the  specific details of the
        particular  process employed in  a given plant, such as the nature
        of the sulfur source  and the range in composition and extent of
        contaminants present. Even in  a sulfur burning plant the latter
        item  can  be important.   The rated  capacity  and  normal operating
        rate  of the plant should be obtained.  Information on start-up
        procedures  and  the frequency with  which shut-downs and start-ups
        occur is  desirable.   Operating  procedures and nature of control
        procedures  and  equipment should be secured.  Some of the specific
        items of  importance are  SO  and 0   concentrations entering the

-------
                            7.7.27
    converter, temperatures at various points in the converter and
    absorption tower, and the concentration and temperature of the
    absorption tower acid.   In some cases the inspector may be given
    the opportunity of examining operating records during the inter-
    The inspector should obtain information on sulfur dioxide conver-
    sion efficiency, efficiency of any collection equipment used and
    data on the tail composition finally being discharged to the
    atmosphere.  He should inquire about maintenance procedures and
    their frequency.

b.  Physical Inspection
    The inspector should first become familiar with the physical layout
    of the plant and prepare or obtain a plot plan showing the location
    of principal items of equipment.

    He should inspect the sulfur storage area in the sulfur burning
    plant and determine the potential for wind blown sulfur dust
    losses.  He should also investigate the possibility of hydrogen
    sulfide formation from molten sulfur containing hydrocarbon
    impurities.

    Depending upon the type and age of the plant, some indicating
    and/or recording instrumentation may be employed.  Some of the
    types which the inspector may have the opportunity of examining
    include:
         •  Temperature (process gas entering and leaving the
            several converter stages and absorption towers).
         •  Acid concentration (drying tower and absorption
            towers).

-------
                        7.7.28
        SO  concentration (entering the converter, entering
        and leaving the absorption tower or tail gas
        scrubber).
        Miscellaneous flow and pressure measurements.
Tests for sulfur dioxide, oxygen, acid mist concentration, and
nitrogen oxides often can be manually performed to supplement the
above instrumentation.

The inspector should determine the capability of the plant to meet
emission control regulations.  These include limitations on the
discharge of (1) sulfur dioxide in the effluent in excess of 4 Ibs.
per ton of acid produced (2 kgm per metric ton), maximum 2-hour
average, (2) acid mist  in the effluent in excess of 0.15 Ib. per
ton of acid produced (0.075 kgm per metric ton), maximum 2-hour
average, expressed as H.SO,, and (3) a visible emission.  In
determining compliance  the inspector should:

(1) Check the number of catalyst stages - older plants that have
    only two stages of  catalyst typically have only 90-95% conver-
    sion of sulfur dioxide to sulfur trioxide.  Plants with three
    stages of catalyst  will typically have a 96-98% conversion of
    sulfur dioxide to sulfur trioxide.  These conversion efficien-
    cies are equivalent to emission rates of 26 to 52 Ibs. per ton
    of acid produced.

-------
                        7.7.29
(2)  Determine  types  of  acid mist  eliminators.  Mesh mist  elimina-
    tors with  double pads will  collect  efficiently acid spray  and
    mist from  a properly operated 98% acid  absorber, but  not acid
    mist from  an  oleum  tower.   Teflon mist  eliminators or high
    energy  scrubbers are often  used  to  collect acid mist  less  than
    three microns in size to meet  an emission limit of .15 Ib. per
    ton of  acid,  maximum 2-hour average,  expressed as H SO, or a
    visible emission.

(3)  Control room  operating log.
    (a) Check  concentration of  sulfur dioxide entering and leaving
       the converter.  Any unconverted sulfur dioxide will pass
       through the  absorber  to atmosphere.

    (b) Check  temperature of  98%  absorber tower  acid.  If the
       acid temperature is considerably  above 180°F, excess sulfur
       trioxide  and acid mist  can be discharged to atmosphere.

    (c) Determine operating rates from  log  and compare with design
       capacity  from permit  system  records.  Operation at over-
       capacity  can result in  excessive  emissions of sulfur
       dioxide and  acid mist.

(4)  Potential  of  the source to  create a nusiance problem  in terms
    of:
    (a) Possible  effects of sulfur dioxide  and acid mist  on people
       and property.

    (b) Excessive emissions of  sulfur dioxide during cold start-
       ups, upset conditions or  overload operations.

-------
                                    7.7.30
                (c)  Excessive emissions  of  acid mist  during oleum production
                    or  improper operation of  absorber.

            The inspector should attempt to relate  tail gas concentrations and
            appearance  to operating  parameters  during the time of his  inspec-
            tion.   This information  will be useful  in interpreting causes of
            upsets or off-normal conditions leading to  excessive discharge of
            air contaminants.  Finally,  it  will be  very useful for the
            inspector to be present  during  a  start-up operation to obtain
            first  hand  information on optimum procedures for minimizing losses.

H.  NATURE OF SOURCE PROBLEM - VINYL CHLORIDE MANUFACTURING
    The manufacture of  polyvinyl chloride plastics  in the United States is
                                                       /Q \
    second only to polyethylene production.  As of  1967    there were  nineteen
    vinyl chloride monomer plants having a  capacity of  2.8 billion pounds, of
    which one billion pounds was based upon the use of  acetylene.   Predictions
    at that time were that the use of acetylene as  a  starting chemical would
    be phased out  rapidly in favor of ethylene-based  oxychlorination processes
    which are at the present time more attractive economically.   Industry
    sources confirms that this indeed has occurred.

    Over 80% of the chlorine production  and 50% of  the  HC1 production  in the
    United States  is consumed in the organic  chlorination industry with a very
                                                                             (9)
    high proportion of  this quantity being  used in  vinyl chloride production.
    There are strong economic reasons to recover and recycle as much of the
    chlorine and HC1 as possible.

    1.  Nature of  Air Pollution Problems
        The manufacture of vinyl chloride monomer (CH  = CHC1) is based upon
        the chlorination and hydrochlorination  of acetylene and/or ethylene.
        Although the air pollution potential  is not great, the purging of inert

-------
                                    7. 7.31
        gases such as nitrogen from the air used in oxychlorination processes
        can result in the loss of small quantities  of unreacted chlorine,
        hydrogen chloride,  acetylene,  ethylene,  vinyl chloride, partially
        oxidized hydrocarbons, and chlorinated side-reaction products.

        These materials may be controlled by the use of caustic scrubbers,
        absorption units, and waste heat boilers.

        An intermittent problem may result from the burn-off of accumulated
        carbon from the beds used in the cracking of ethylene dichloride to
        form vinyl chloride.  Normally this operation is easily controlled
        but the discharge of products  from incomplete combustion,  including
        smoke, is at least possible.

        The transfer and storage of chlorine,  hydrogen chloride and vinyl
        chloride are usually completely closed operations,  making  any release
        of these compounds very unlikely.

I.   PROCESS DESCRIPTION - VINYL CHLORIDE MANUFACTURING
    1.   Basic Reactions
        Vinyl chloride (CH  = CHC1) is a colorless, flammable compound  having
        an ethereal odor.  It boils at -13.81°C  and is stored under slight
        pressure to maintain the liquid state.   Until recent years the  princi
        pal manufacturing process used involved  the hydrochlorination of
        acetylene     according to the following reaction:
                  CH = CH + HC1     2 CH  =  CHC1

        The reaction,  which is  exothermic, takes place  over  a mercuric chloride
        catalyst.   In addition  to  the vinyl  chloride  product,  the reactor gases
        contain small quantities of  acetylene,  HC1, and other organic addition

-------
                            7.7.32
products.   Figure 7.7.5 shows a simplified schematic flow sheet of the
process.   The vent gases from the absorber are composed of about 90%
inert gases and 10% acetylene.   The relative quantity of these gases
is very low.

The other important basic reactions leading to the production of vinyl
chloride involve (1) the chlorination of ethylene to form ethylene
dichloride  (more properly 1,2 dichloroethane) followed by (2) the
cracking of ethylene dichloride (EDO) to yield vinyl chloride and
hydrogen chloride.  These reactions are seen below:

          CH2 = CH2 + C12 -»~ CH2C1 - CH2C1

          CH Cl - CH Cl hf^t CH  = CHCL + HC1

A first step at improving the economics of the acetylene and ethylene
routes to vinyl chloride resulted in the so-called "balanced processes."
One variation of such a process is shown in Figure 7.7.6.  Although
this flow sheet is considerably simplified, vent gases are similar to
the basic acetylene process.

Current Manufacturing Practice
During the past few years there has been a rapid change in industry
practice to adopt the oxychlorination process for manufacturing vinyl
chloride.   '   '      In this process, ethylene, oxygen (almost always
from air),  and ethylene are  the starting materials.
The hydrogen chloride resulting from the cracking of ethylene dichloride
fromed by the chlorination of ethylene is fed together with oxygen and
ethylene to form additional ethylene dichloride.  Thus, no acetylene is

-------
                                 Unreacted CH=CH and CH =CHC1
                     Spent Caustic
                                         Vinyl Chloride
                                          Purification
             Heavy Ends
Purified Vinyl Chloride
                                           Heavy Ends
Figure 7.7.5  MANUFACTURE OF VINYL CHLORIDE FROM ACETYLENE AND HYDROGEN CHLORIDE

-------
CHsCH
CH=CH
 Cl.,
           Hydrochlorination
                    HC1
             Chlorination
RawCH2=CHCl
     EDC
Purification
                                                                              Vinyl Chloride
                                                                               Purification
                                                   Vinyl Chloride,
                                                     Product
                                                                                         CH =CHC1
                                                                                         HC1
   EDC
Cracking
         Figure 7.7.6  BALANCED  PROCESS  FOR VINYL CHLORIDE USING ACETYLENE AND ETHYLENE

-------
                                7.7.35
    needed to utilize the by-product hydrogen chloride.   Figure 7.7.7
    shows a schematic flowsheet of one approach to this  process.   In the
    United States pure ethylene is normally used as the  starting material,
    although in Japan at least one producer utilizes a relatively impure
    mixed stream of ethylene and acetylene prepared from the on-stream
                        (14)
    cracking of naphtha.

    In the oxychlorination process the conversion efficiency of ethylene
    to vinyl chloride is estimated to be in the range 96-98%.   By-products
    include unreacted feed materials, oxygenated compounds and carbon
    oxides.  These materials plus any inert gases must be removed from
    the reactor gases prior to the ethylene dichloride cracking step.  The
    non-condensibles may be vented directly to atmosphere or to some form
    of air pollution control equipment.

    The ethylene dichloride following purification is cracked to form
    vinyl chloride and hydrogen chloride with the latter being separated
    and returned to the oxychlorination reactor.  The cracking takes place
    at 450° - 650°C at elevated pressures, and is usually done over a
    catalyst.  Some carbonization and tar formation takes place depositing
    these materials on the catalyst.  These deposits must be burned off
    the cracking bed periodically in order to restore its effectiveness.
    Modern practice is to use a steam-moderated air oxidation process for
    the carbon burn-off.  When carried out properly only carbon dioxide
    should be vented.

3.   Control Methods
    The principal air pollution problem in the vinyl chloride manufactur-
    ing process has to do with the purge gas venting taking place after
    the reactor stages and before the ethylene dichloride cracking step.
    Inert gases, mainly nitrogen, may be accompanied by  unreacted ethylene
    and chlorine,  hydrogen chloride, oxygenated organics, and carbon oxides.

-------
 Chlorination
                     EDC
                                EDC Purification
                                                                 EDC Cracking
                       EDC
 Oxychlorination
                                     HC1
Vinyl Chloride
 Purification
                                                                                    Vinyl
                                                                                   Chloride
                                                                                    Product
Figure 7.7.7   OXYCHLORINATION PROCESS  FOR MANUFACTURE OF VINYL CHLORIDE

-------
                               7.7.37
    In a well-controlled vinyl chloride plant, these vent gases are gener-
    ally collected in a common manifold and treated by the following series
    of air pollution control measures:  (1) caustic scrubbing of reactor
    vent gases; (2) combustion of oxidizable compounds in a waste heat
    boiler; and (3) caustic scrubbing of boiler vent gases to remove
    additional acid gases formed in the boiler.

    Careful control of the waste heat boiler, usually by  metering auxiliary
    fuel through a steam output rate actuated controller, is necessary to
    avoid smoke formation during any vent gas surges.

    A lesser problem is associated with the vinyl chloride purification
    steps.  Here, vinyl chloride is usually liquified by  refrigeration to
    -20°C.  Vent gases are discharged through a caustic scrubber.

    Vinyl chloride is usually stored as a liquid in spherical pressurized
    containers.  All transfer operations are accomplished using vapor
    return lines.  The technology used is similar to that used for
    liquified petroleum gases.  Routine losses are not expected.

INSPECTION POINTS - VINYL CHLORIDE MANUFACTURING
A well operated and controlled vinyl chloride monomer plant should result
in practically no air pollution problems.  However, should vent gases not
be controlled properly, the release of smoke, odorous substances and
property damaging acid gases is possible.

1.  Environmental Surveillance
    The greatest potential problem from a vinyl chloride  plant is the
    release of acid gases, principally chlorine and hydrogen chloride.
    The hydrogen chloride particularly reacts with moisture in the air
    to form hydrochloric acid mist and vapor which has the potential for

-------
                                7.7.38
    accelerating corrosion in metals,  damaging paint,  and degrading other
    surfaces and materials.   When acid gas  losses  are  suspected,  the
    surrounding area should be examined for evidence of  the type  of damage
    just described.   Test plates  of susceptible materials may be  used if
    necessary.  The damage pattern, if any, should be  correlated  with wind
    direction.  A wind rose (see  Chapter 6, Section V, Odor Detection and
    Evaluation) obtained from a representatively located wind direction
    recorder is particularly useful.

    Odors associated with partially oxidized organic substances and
    chlorinated hydrocarbons are  possible.   They should  be evaluated and
    any complaints reviewed.

2.   Plant Inspection
    a.   Interview
        As seen from the description of the manufacturing process a wide
        variety of specific plant design features  may  be expected in vinyl
        chloride plants.   Also they may be  integrated  with the production
        of other chlorinated hydrocarbons.   Therefore, it is very impor-
        tant to obtain an exact description of the process used and the
        starting materials.

        Specific inquiry should be made as  to the  number and location of
        process vents, the nature of vent gases, the procedure for collect-
        ing vent gases,  and the specific control techniques and equipment
        used.   The design objectives for caustic scrubbers should be
        obtained.

        Plant  management should be asked to describe procedures for con-
        trolling vent gases  during upsets,  including methods for  preventing
        or minimizing smoke  from  afterburners or waste heat boilers.

-------
                           7.7.39
b.   Physical Inspection
    The inspector should verify the placement of various  items of
    equipment in the process, paying particular importance to the
    location and height of various vents.   Determination  should be
    made of the production rate as a percent of rated capacity, the
    specific materials being charged to the process,  and  whether
    operating conditions are representative of the normal situation.

    It will be useful to inspect the plant at various times to observe
    start-up operations, catalyst burn-off, and raw materials and
    product transfer.

    Should visible emissions or odors be detected as  a result of plant
    operations, a specific determination of the associated operating
    conditions should be made.

-------
                                     7.7.40
                                   REFERENCES

 1.  Groggins, P. H.  (ed.).   Unit Processes  in Organic  Synthesis, Third  ed.
     McGraw-Hill Book Co.,  Inc.   New York, 1947.

 2.  McCabe, W. L., and J.  C. Smith.   Unit Operations of  Chemical Engineering.
     McGraw-Hill Book Co.,  Inc.   New York, 1956.

 3.  Atmospheric Emissions  from Sulfuric Acid  Manufacturing Processes.
     DHEW, PHS, Division of Air Pollution.   PHS Publ. No.  999-AP-13,  1965.

 4.  Control Techniques for Sulfur Dioxide.  DHEW,  PHS, NAPCA,  Publ.  No.  AP-52,
     Jan., 1969.

 5.  Engineering Analysis of Emissions Control Technology for  Sulfuric Acid
     Manufacturing Processes, Final Report.  CHEMICO. DHEW, PHS, NAPCA.
     Contract CPA22-69-81.   March 1970.

 6.  Tucker, W. G., and J.  R. Burleigh.  S02 Emission Control  from  Acid  Plants.
     Chem. Engr. Prog.   67,  57-63.   May 1971.

 7.  Shah, I. S.  Removing  S02 and Acid Mist with Venturi Scrubbers.
     Chem. Engr. Prog., 67,  51-56.   May, 1971.

 8.  Sarvetnick, H. A.   Polyvinyl Chloride.  Reinhold Book Corp., New York.
     1969.

 9.  Gerstle, R. R.,  and T.  W. Devitt.  Chlorine  and Hydrogen  Chloride
     Emissions and Their Control.  Paper #71-25,  64th Annual Meeting  of  the
     APCA.  Atlantic City.   June 27-July 2,  1971.

10.  Albright, L. F.   Vinyl Chloride Processes.  Chem.  Engr.,  74, 123-30.
     November 27, 1967.

11.  Buckley, J. A.  Vinyl  Chloride Via Direct Chlorination  and Oxychlorination.
     Chem. Engr., 73, 102-104.  November 21, 1966.

12.  Albright, L. F.   Manufacture of Vinyl Chloride.  Chem. Engr.,  74, 219-226.
     April 10, 1967.

13.  Kling, H.  Am. Chem. Co., (pers. comm.).

14.  Vinyl Process Petrochemical, Pacesetter?   Chem. Engr.,  74, 48-49.
     March 27, 1967.

-------
                                     7.8.1
           VIII.   PRIMARY AND SECONDARY NON-FERROUS SMELTING AND REFINING

A.  INTRODUCTION
    The smelting and refining of non-ferrous metals are primarily concerned
    with the production of copper, lead, zinc and aluminum ingots and alloys.
    This activity is important from the standpoint of both the air pollutants
    emitted and the extensive production of these metals in the United States.
    Primary aluminum reduction is treated in Section XI of this chapter.

    Copper, lead and zinc occur mainly as sulfides and are mined either in
    open pits or in underground operations.

    Primary smelting refers to the extraction of the virgin metal from its
    original ore by crushing large quantities of ore-bearing rock, concen-
    tration of the resultant feed and application of pyrometallurgical
    processes such as roasting, melting and conversion.  The operation may
    also include dross recovery.   Since the percentage of the recoverable
    material is small, emissions of oxides of sulfur, fumes, dust and
    participates are likely to be very great and difficult to control.

    Secondary smelting and refining are concerned with the preparation and
    melting of scrap metal of known and unknown analysis, dross recovery and
    wire reclamation.  The major metals of interest include copper-base
    alloys (brass, bronze and black copper), zinc, lead and aluminum.
    Emissions from melting operations include smoke, dust, fumes, oxides of
    sulfur, and fluxing and degreasing agents.

    Refining refers to the removal of impurities necessary to produce an
    ingot or alloy of desired specification.  Non-ferrous foundries,
    treated in Section IX of this chapter, involve sand-casting and are oriented

-------
                                     7.8.2
    to the production of  consumer  and  industrial products.

    Primary smelters  usually  constitute,  large, difficult  to control single
    sources of air pollution,  are  usually located  outside  of urban  areas
    and can be significant sources of  visible emissions and  plant damage.
    Secondary smelters are commonly  found in industrial and  urban areas,
    close to sources  of scrap  and  other raw materials  generated by  population
    centers.   They are significant sources of pollution, as  well as local
    public nuisance problems.   Both  industries employ  similar equipment,
    although primary  smelting  involves a  larger variety of processes.

B.   DESCRIPTION OF SOURCE—PRIMARY SMELTING
    The history of controlling emissions  from non-ferrous  smelters  goes
    back to the middle of the  19th century.  Developmental projects are
    still underway to find economic  methods for further reducing sulfur
    oxide emissions from  smelters.   While SO  is the major contaminant of
                                           x          J
    interest from this source,  particulate emissions inherent in the job
    of extracting any metal from its ore, is also  a major problem although
    air pollution control techniques and  efficient equipment are currently
    available.

    National  sulfur oxide emissions  from  non-ferrous smelters  are estimated at
    almost 3,000,000  tons, based on  an annual rate for the first half of 1969
    and excluding  sulfur  oxides or byproducts from pyrite roasting  and sulfur
    burning.   Of  this  amount 852,900 tons of SO  were recovered and
                                              X   (1)
    1,924,400 tons were emitted to the atmosphere.     Other commonalities
    of non-ferrous smelting include  high  temperature gas emissions  at
    1200°F to 2400°F,  heavy dust and fume loading  and  lean sulfur oxides
    concentrations in the off-gases  all of which make  recovery difficult and
    economically  questionable.

-------
                                 7.8.3
The Air Pollution Control Inspector, although not generally involved in
the research and development projects associated with the overall problem
of recovery of sulfur oxides, must be familiar with the basic processes,
type and magnitude of emissions, state of the art of air pollution control
methods and possible future changes in this technology.

1.  Process Description
    a.  Copper
        Before any of the pyrometallurgical processes  (furnace and
        related operations) can begin, the feed must be prepared into a
        concentrate for economic recovery of copper.  After initial
        crushing, the ore is fed to wet ball or rod mills where it is
        allowed to settle and is filtered.  The resultant concentrate
        is mixed with copper precipitates obtained from leaching mine
        waste and oxidized ores.  The concentrate contains between
        70 and 85% copper and small quantities of direct smelting
        sulfides and oxide ores which also contain four to six percent
        copper.

        Table 7.8.1    shows a typical analysis of a high quality concentrate.
        The concentrate has a free moisture content of 10 to 12 percent while
        the precipitant contains 15 to 30 percent water.

           Table 7.8.1  Typical High Quality Concentrate Analysis

                   Constituent            Percent (dry basis)
                   Copper, Cu                27.5
                   Iron, Fe                  24.5
                   Sulfur, S                 31.5
                   Silica, SiO               11.0
                   Other                      5.5
              (SOURCE:   ARTHUR G.  MCKEE & CO.,  Reference 1)

-------
                         7.8.4
The typical copper smelter in the United States uses a roaster,
reverberatory furnace and converter in the sequence shown in
Figure 7.8.1.  Variations to the system shown in the flow diagram
include predrying of the feed in rotary driers or multiple
hearth dryers, or direct charging to a reverberatory furnace.

(1)  Roasting

     Wet concentrate is sprayed as a slurry or charged dry into
     a multiple hearth, or, in more modern plants, a fluid-bed
     roaster.  Depending on the size of the roaster, the charge
     can be 200 to 1500 tons/day of feed plus silica fluxes.   The
     roasting drives off the moisture and converts parts of
     the sulfur to sulfur dioxide and the iron to iron oxide.
     Roasting reduces the fuel requirements of the reverbatory
     furnace by about half.  The concentration of SO- from multiple-
     hearth type roasters is about 7% while the concentration of SO.
                                     (2)
     fluid-bed roasters is about 15%.      The operating temperatures
     for both systems is about 1200 F.  The temperature of the dust-
     laden gases leaving the furnace is reduced by dilution air,
     water spray or heat exchangers to 600 F.  Initial dust and
     fume control is achieved by use of settling chambers or
     mechanical collectors followed by electrostatic precipitators.
     The dust loading is between three and six percent of the feed,
     most of which is captured in the flues.  The roaster gas then
     either goes to the stack or the sulfuric acid plant (Table
     7.8.2   ).  The calcine from roasting is hot and dusty and

-------
CUSTOM ORE 4
, CONCENTRATES
(S TOMSI
•^ ROAS

(ACTUAL TEMP F]

GAS (OOO SCFMl
S IN GAS TONS!
OUST TONS
S IN DUST TONS
ACTUAL TEMP F]
\
t
i
SOLIDS 1 LIQUIDS 	
GASES 	
SCPM MEASURED AT 32°F
NIL -NEGLECTFDUNSIGN
-rnn r*5~i
1 a>
I
. .ueer/^c «a, 1TA MISCELLANEOUS
LIMESTONE 5h-«-* pygj j REV£RTS
3 ryi -nri n^n-
j 'i
ISiX.f--*
1
1
1 ]

Trn , C»LC*« JRFVERBFRATORY

1*tvdS
1 1 	

1 FURNACE i T SLAG BLOW | '| FIN6H BLOW | » co«TS«l o.i TO-S"
1 1
-O^] [fSJi-i
IT If i *
L. .-?s^,"-«,.L. J I ! i

! ! """"'
1 ~* RECUPERATOHf""^
I2(xr 1J 100- 1 1 ior 1 1
*U«.J «„».„
	 j
1
f
•«
<.R
rocr

[ FLUES AND 1
PUST COLLECTION

i.

*" r 10 •TMWPHEftf' "^ TDAlMOVMC*
»o" 1 ziocr 1 iKxf 4so- ioff 1 iso- 1
** *nLUT«MUI OClrtlWiMI •*
K* COMVtHTCN | 1* «fl COWCRTa)
1- 	 J
!
U^LEclU | STCK | | STCK |
J
1
L 	 «— « 	 j
•O*STf • «M> flCVt«C*5 J
OUST
NOTE
AND r.NF ATur^=uFDc °i±i' K^wf ^iXfa^e^SSf ma°^\r
F.CANT (.UANIITY NOT AFFECTING MATERIAL BALANCE) »LL FLO* QUANTITIES AOE ESTIMATED .ROASTER THE |AME OTVEBTER IS U5EO K)H SLAG
                                                                                                                  oo

                                                                                                                  On
NEC -NEGL£CTEOiMINOR CUANTITY PRESENT
N.R.-NOT R£PORIED(.CJUANTITY UNKNOWN)
                                         AND REvERBERATORT GASES ABE SHOWN ON A
                                         DAILY RATE BASIS. CONVERTER GASES APF AVEfl-
                                         AGEO FOR A BLOW TIME OF n.7HR TOTAI ELAPSED
                                         TIME. TONNAGES ARE GIVEN IN SHORT TONS FOR
                                          IME. TONNAGES ARE
                                           24 HOUR PERIOD
Figure  7.8.1.
                                              FLOW DIAGRAM OF A TYPICAL  COPPER  SMELTER
                                               (SOURCE:   ARTHUR  G.  MCKEE  &  CO.,  Reference 1)

-------
                                    7.8.6
Table 7.8.2.
            (3)
handling this material,  which is charged to the reverberatory
furnace, presents a dust control problem.   Added to this
problem is the introduction of the material captured in the
primary dust collector to the charge of the reverbatory furnace,

 EMISSIONS FROM COPPER ROASTERS, REVERBERATORY FURNACES,
              AND CONVERTERS3

Roasters
Reverberatory
furnaces
Converters
Waste Gas
(m3)
1300b
2000b
10,000°
Raw Gas
Dust Content
3
(gm/m )
15
4
12
SO Content
%
2-8
-
to 8
      Clean Air Guide 2101,  Kommission Reinhaltung der Luft,  Verein Deutscher
        Ingenieure,  VDI—Verlag GmbH,  Dusseldorf,  West Germany,  January 1960
      Per ton of concentrates
     "Including extraneous air per ton of  charge
                       (SOURCE:   NELSON, Reference 3)
           (2)   Reverberatory Furnaces
                The  function of the reverberatory  furnaces  is to melt  the
                calcine from roasting, green ore,  recycled  "flue dust"  or
                converter slag to form matte—a mixture of  cuprous  and  ferrous
                sulfides and slag.   A  slightly oxidizing atmosphere is
                maintained in the furnace  by providing excess air above the
                requirements for theoretically complete combusion.   Furnace
                sizes range  from 22 feet x 96 feet to  38 feet x  125 feet and
                hold a molten batch 24 to  48 inches deep with a  feed rate
                of 400 to 1100 tons/day.   (See Figure  6.2.16,  Fuel-Burning,
                Chapter 6,  Section II.)  The furnace operating temperature

-------
                             7.8.7
          reaches 2400 F.   This high temperature and large volume of
          the exhaust gas  lends itself to heat recovery in waste-heat
          boilers for generation of steam and electrical power.   The
          typical operating conditions from an oil or gas fired  furnace
          are shown in Table 7.8.3.

Table 7.8.3.  TYPICAL REVERBERATORY FURNACE OPERATING CONDITIONS
     Furnace bath temperature          2400 F
     Excess Air                        1-4 percent
     Furnace pressure                  +0.1 in. of water
     Dust load in offgas               2-5 grains per scf
     Sulfur dioxide in offgas          0.5 - 3.5 percent
          (SOURCE:  ARTHUR G. MCKEE & CO., Reference 1)
          Table 7.8.4 shows the off-gas composition at 2400 F based upon
          the feed (green feed or calcined feed) to the furnace;
          Table 7.8.5 gives the composition of the molten products
          from the reverberatory furnace.

    Table 7.8.4.  REVERBERATORY FURNACE OFF-GAS COMPOSITION
      Component              Green Feed           Calcine Feed
     Carbon Dioxide            8.4%                  10.2%
     Nitrogen                 69.3%                  71.0%
     Oxygen                  0.25 - 1.0%          0.25 - 1.0%
     Water                    18.8%                  17.7%
     Sulfur Dioxide          1.5-3.5%            .6-1.0%
          (SOURCE:  ARTHUR G. MCKEE & CO., Reference 1)

-------
                              7.8.8
Table 7.8.5.  COMPOSITION OF REVERBERATORY FURNACE MOLTEN PRODUCTS
         Component            Matte             Slag
         Copper              25 - 50%         0.4 - 0.7%
         Iron               29 - 35%         34 - 40%
         Silica              0.8 - 1.0%       35 - 40%
         Sulfur              22 - 29%         1.0 - 1.5%
        (SOURCE:  ARTHUR G. MCKEE & CO., Reference 1)
          Dust loading in the gases leaving the furnace is heavy.  Up
          to 25%^- '  of the dust is recovered by gravity in the balloon
          flues  upstream of the waste heat boiler.  This necessitates the use
          of feeders (screw or gravity)  from the flues and hoppers to remove
          the dust for recycling.  The smaller particle sizes are then
          exhausted to the electrical precipitator.   The particulates from
          copper smelting operations are volatalized oxides,  fumes of antimony
          arsenic,  zinc lead, bismuth, tellurium and selenium.  A by-
          product of non-volatilized metals include nickel, cobalt, and
          precious metals which can be separately refined.

     (3)  Converters
          Copper matte is transferred from the reverberatory furnaces
          to the converters in large ladles by overhead cranes.
          Converting is a batch process with three distinct phases of
          operation:  charging, slag skimming and pouring.  Air or air
          enriched with oxygen is blown into the furnace through
          tuyeres for oxidation.  A temperature of 2250°F is maintained
          by the oxidation reaction without the requirement for additional
          fuel.   Most converters in use are Fierce-Smith type
          cylindrical furnaces, 13 feet in diameter and 30 feet long
          with an average daily production of 135 tons of copper, depend-
          ing on the grade of matte charged.

-------
                    7.8.9
The process oxidizes and separates the iron and sulfur from
the copper in the matte.  The furnaces are operated in
sequence so that the air/oxygen blowing will not occur at
the same time to allow a fairly regular flow of SO- to the
acid plant.  The highest theoretical concentration of SO.
occurs after the slag has been skimmed and the "white metal"
or cuprous sulfide has been converted to copper.

Capturing the fume and off-gases from this type of furnace
requires hooding similar to the equipment used on basic
oxygen furnaces (see Section IV).  The tighter the hood fits,
the less dilute are the emissions of sulfur oxides to be
controlled.  The drawback is that temperatures at the hoods
remain high which may damage the hoods and accompanying
ductwork.  Some experiments are being conducted with water
cooled hoods in connection with waste heat boilers to reduce
the temperature to 600 F between the converters and the
electrostatic precipitators.  The product of the converter is
blister copper which is 99% pure and is either used in this
form or further refined for anode production or other shapes.

Two approaches to copper production which have received
considerable attention and which should be mentioned for
possible future interest are continuous smelting and hydro-
metallurgy.  Continuous smelting will likely replace the rever-
beratory furnace and converter with a single unit while hydro-
metallurgy will likely replace all of the conventional pyro-
metallurgical processes with electrolytic processes after the
sulfide ore has been pretreated.

-------
                         7.8.10
(4)   Contaminants  Emitted
     Emissions from roasting, reverberatory furnaces
     and  converters consist of dust, fumes and  sulfur
     oxides.

     Typical volumetric analyses of offgases are:
          Roasters                SCL/SO -12%
          Reverberatory furnaces   S02/S03-0.6%
          Converters               SC>2/S03-5.0%
     While perhaps not typical, some measured particulate  concentrations
     from these  operations are roasters 18-24 GR/SCF; reverberatory
                                                         C4")
     furnaces 0.55-6.0 GR/SCF; converters .55-3.0 GR/SCF.v '
    A common practice among plants that recover sulfur is  to
    vent  the gases released from the roaster and converter
    gases  to sulfuric acid plants and to vent the reverbera-
    tory  gases  to the atmosphere because of the low SO
    content.

    Without the imposition of air pollution control standards,
    economics would be  the only criteria for the control of
    particulates and SO .  The control of dust and fumes can be
                        X
    achieved by the use of dust control trains consisting  of a
    mechanical  separator, gravity separators and electrostatic
    precipitators.  The recovery of oxides of sulfur  is receiving
    a great deal of attention, not only in the smelter industry
    but from all processes where SO  is generated.  Acid plants
                                   X
    and elemental sulfur recovery operations will come into
    increased use.  The sulfuric acid production is discussed
    in Chemical Plants, Section VII.

-------
                            7.8.11
b.   Lead
    Lead sulflde (or galena) Is prepared similarly to copper sulfide
    concentrate.  Lead mineral galena generally contains 55 to 70 per-
    cent lead; as much as 6.5 percent zinc; 0.5 to 4.0 percent copper;
    13 to 18.5 percent sulfur; as much as 5.0 percent iron and silica,
    lime, cadmium, silver and gold; and arsenic in minor amounts.

    Existing lead producing practices in the United States involve
    fundamentally identical operations:  Sintering, reduction in blast
    furnaces and refining.  While the processes are similar, different
    types of equipment can be employed.
    chart for a lead smelting operation.
types of equipment can be employed.   Figure 7.8.2    shows  a flow
     (1)  Sintering
         Sintering is the agglomeration of fine particles by partial
         fusion due to application of heat.  Sintering is conducted
         to prepare the lead sulfide concentrate and involves a
         combination of roasting to remove the sulfur and sintering to
         form a strong porous mass suitable for reduction of the lead
         oxide in the blast furnace.  Figure 7.8.3    is a flow diagran
         showing material components of a typical sintering operation.
         Two types of sintering machines known as Dwight-Lloyd machines
         are in use.  The older downdraft machine draws in large
         quantities of excess air diluting the SO  concentration and
         requiring recirculation of the gases to bring the concentration
         up to 4-7% S0_.  The newer updraft machine draws in less out-
         side air and does not dilute the concentration of SO .  Re-
                                                             x
         circulation is also used in this machine to further enrich
         the effluent for recovery as H_SO,.

-------
             ORE AND LEAD
             CONCENTRATE
  15 TflNSl
FLUXES
~n

I
y*££
yl


SINT
IACI-
L_,



^






ERING
INES
n~
-r.tr
1 :;


( SE
r
!_ «•"
J
V
f


.. 1

l_
	 J COOLE
™ CONDI




i
AND
ONEH

I FLUE AND
JOUST COLLECTION

1
1
1



J
f
|
Las.




ZINC PLANT
RESIDUES




-C»3





FURNACE
COKE
<£f




COKE
BBEE2E


•
BL
JR
L

5T
4CES
|

es
120
N.R.
«oo-





-
c



^
1COOL
CONO



v£h
' "i*
r-
R AND
IONER

BUSTLUCEOLLEC?IC.

1
i™.

-
It*
.
J
1




^

IK-
P-
LEAD
EFINERY
! 1



us
• EC.CLE
*LEl

05D



OftOSS





TO *I«Oi
}—

J


SECOND STAGE SmTER


t-Sl i.,c



•fc i«S





600-FT

1


J'1'
ll
STACK


t ff
1 L
|



,1
1





MISCELLANEOUS
DUST t, RESIDUE
CKT>
-j io N>I us ru[L
REVERB |








i ton £«1 NSIOhS
r "™S~" "^ ~**l
LIQUID SULFUR /
DIOXIDE PLANT /
1 | .'

ACID PUNT
f | r«io»*xuci ttons

o^, s cam.! ,1. .aa
                                                                                                                                                  c»

                                                                                                                                                  H-1
                                                                                                                                                  KJ
1NSUFFCIEN1 DATA AVAILABLE
TO SHOW COMPLETE SULFUfi
BALANCE
                                               TONNAGES ARE GIVEN
                                               FOR A 84-HOUR PERlOO
                                               IN SHORT TONS
                WL- M£GLKTH)(INSlGNlFiCANT CUiNlHV NOl AFFECTING MATERIAL BALANCE}
                -ift-NOT REPQflTED (QUANTITY UNKNOWN)
                SOLIDS t LIQUIDS •  •
                GASES      — — ..
                SCFM MEASURE' VT 3?T
                AND  ONE ATfc.oc J*£R£
                ' - ESTlMAltT ' - .'ITY
                               Figure  7.8.2.
FLOW CHART  FOR A LEAD SMELTING  OPERATION
(SOURCE:   ARTHUR G.  MCKEE  &  CO.,  Reference  1)

-------
TYPICAL LEAD SINTERING  PLANT MAJOR MATERIAL  DISTRIBUTION
LEAD CONl
MISC. LEAD
FLUX DILUE
SINTER RtC
i
:ENTRATE 31.47
MAiERIAL 12.44
NT 19.85
YCLE 36.20
' • '
T

J Pb-37.0%
/\ S- 7.0% OFFGAS PRODUCTS
/s (SULFUR DIOXIDE 5.95
iCARBON DIOXIDE 1.60
L_
RE"Ui?tED * SINTER | TOTAL SIFTER 95.33 K SINTER PRO
OXYGEN 2.87 \ PLANT s
t £
j
RECYCLE •$
TO BLAST
DUCT 59.13 FURNACE
--.... p>
Pb-38.8%
S - 1.08%

                                                                                       00

                                                                                       (->
                                                                                       U)
        Figure 7.8.3.  TYPICAL LEAD SINTERING PLANT MAJOR MATERIAL DISTRIBUTION
                     (SOURCE:  ARTHUR G.  MCKEE & CO., Reference 1)

-------
                    7.8.14
Physically, the machines are conveyors made of gratebar pallets
joined together to form an endless chain.  They range in size
from 3-1/2 x 22 feet to 10 x 103 feet.  The wind box is
located under the pallets or the downdraft machine and above
the pallets on the updraft machine.

Both designs can be either single or two-stage operations.
About 85% of the sulfur in the feed is removed during
sintering, with 14% entering the slag and other solid by-
products.  The remaining one percent is released from the
blast and dross furnaces.  In a two-stage operation, 30 to 40%
of the sulfur is removed during the first stage.  The
clinker is crushed and mixed with one to two percent coke and
returned to the machine.  Even in single-stage machines
40 to 60 percent of the calcine is recycled.

Feed to the sintering equipment is usually pelletized for
ease in handling and ignition.  Natural gas is used for
ignition but the reaction of forming lead and other oxides
maintains the necessary heat.  Control to maintain temperatures
below 1400 F is essential to preclude volatilization of
metals in order to produce the proper clinker with 1 to 3-1/2%
sulfur, and to maintain the grates.  Limiting the sulfur
in the feed to between 6-12% and using sulfide-free fluxes
such as silica and limestone helps to keep the temperature
within the desired limits.

As with most smelting operations the prime target of air
pollution control is SO .  However, some of the operations
develop large quantities of dust and fumes, up to 20% of
the feed in some sintering operations, which will be of concern

-------
                        7.8.15
     to  the air  pollution control  inspector.   Economics  of
     operation dictate  that  efficient  dust  and fume  control  be
     exercised due to  the quantity of  material entrained in  the
     offgas.   The captured material is recycled.   The  inspector
     must  make sure that  capture of the dust  and  fume  is acceptable
     as  well as  cleaning  the offgas in the  air pollution control
     equipment.   The offgas  temperature varies between 250 and
     600 F depending on the  amount of  excess  air  drawn into  the
     system.   Gas volumes are 100  to 220 SCFM per sq.  ft. of bed
     area.   Since baghouses  are often  used  to collect  the dust and
     fumes, the  temperature  is critical with  regard  to the filter
     material.  Gas temperature and humidity  are  also  important
     in  electrostatic precipitator operations (see Section IV,
     Steel Mills).

(2)   Blast Furnaces
     Sinter,  iron and  coke are charged into the blast  furnace
     where the lead oxide is reduced to lead.  At the  usual
     operating temperatures  of 1000 to 1200  F (gas  temperature),
     iron  oxide  and zinc  oxide are not reduced to metals but,
     along with  most of the  sulfur present, leave the  furnace in
     the slag.  Since  some zones of the furnace reach  higher
     temperatures there is some distillation  of lead oxide and
     zinc  oxide.  These materials  along with  dust and  volatilized
     cadmium oxide are  entrained in the exhaust gases.  There is
     little S0_  reported  in  the exhaust gases.  Dust from the
     charge and  fumes  from the chemical reactions are  entrained
     in  the air  blown  through the  tuyeres up  through the charge.
     The chemical reactions  are:

-------
                    7.8.16
     PbO + CO + heat = Pb + CQ^
     C + 02 = C02 + Heat
     C + C02 + Heat = 2CO
Theoretical flue gas rates are 6000 to 14,000 SCFM varying
with the size of the furnace.  Blast air is between 5000
and 9000 SCFM.  The actual gas volume to be handled from the
furnace is 9 to 12 times the theoretical flow due primarily
to the large volume of air which leaks in at the top of the
furnace.  The furnace gas, before dilution, contains 25
to 50 percent CO and may reach temperatures of 1400 F.  The
high volume of dilution air aids in the combustion of CO to
CO. and serves to reduce the gas temperature to a resultant
temperature of 150 to 250°F before entering the air pollution
control equipment.
The blast furnace produces four liquids:  lead bullion, matte,
speiss (metallic arsenides) and slag.  The lead bullion is
separated by gravity and goes to the refining process.  The
matte and speiss go to the dross furnace for further lead
recovery.  The slag is removed separately and is either
transported to a dump or is moved hot to fuming furnaces for
recovery of lead and zinc.

Typical composition:
     Lead Bullion:  95% to 99% lead.
     Matte:         44 to 62% Copper, 10 to 20% lead and up to
                    13% sulfur; up to 2% zinc and small amounts
                    of iron and silica.

-------
                        7.8.17
          Speiss:         55  to  64%  copper;  up  to  18%  lead  and  traces
                         of  sulfur  and  aresenic;  1% zinc and 0.5%
                         iron and silica.
          Slag:           High silica 10 to  20% zinc;  up to 2%
                         lead and 3% sulfur; some iron and calcium.
(3)   Lead Refining
     Lead refining produces  high purity  bullion  (95  to  99%)  as well
     as matte,  speiss,  and dross in operations employing  reverberatory
     furnaces and refining kettles  or  pots.   The products from
     the lead blast furnace  are fed to a gas  or  oil-fired
     reverberatory furnace at  about 1400 F with  an oxidizing
     atmosphere.   Dross forms  over  the surface of the batch  which
     becomes a product  to be processed in the dross  reverberatory
     along with matte and speiss.   The remaining dross, matte and
     speiss are skimmed from the dross reverberatory after optimum
     lead removal and are shipped to copper smelters for
     reclamation  of copper,  which may  run from 44 to 62 percent.
     Figure 7.8.4    describes the  complete cycle of lead smelting.

     Refining kettles are used to bring  the bullion  to  desired
     limits of antimony, zinc, arsenic,  tin,  etc. by the  introduction
     of sodium hydroxide, sodium nitrate or sodium salts. Table
          (3)
     7.8.6    describes emission rates from a lead smelting  operation.
     It indicates an absence of S00 emissions from reverberatory
                                         (1)
     furnaces.  However, the McKee  study     indicates  that  sulfur
     can be added to both the  reverberatory furnaces and  the
     refining kettles which  can cause  the emission of as  much as
     0.2 percent  of sulfur oxide for short periods after  the
     addition of  sulfur.

-------
                                  7.8.18
                                  Ore
                                   I
                                 (1) Mine
                                   I
                                 (2) Crush

                          (3) Concentrate If low grade

                                   I
                            (4) Rough roast

                           (5)  Bins or ore beds

                                (6) Sinter

                        (7) Smelt (usually in blast furnace)
1
Slag
Waste

S
Reh
blast
" 1
Base bullion
Dressing kettle
Dross

Dross furnace
1
Base bullion
Pefinlng plant

I
ag Matte-spelsa Base bullion
rn to Ship to Return to
furnace copper smelter dressing kettle
1
Gases
Cottrell or bag house
Flue dust Cleaned
Work up
values

1
Gases
To Cottrell
or bag house
    Figure 7.8.4.   USUAL TREATMENT OF  A SULFIDE LEAD  ORE
                      (SOURCE:   NELSON, Reference  3)
Table 7.8.6.   EMISSIONS FROM LEAD SINTERING, BLAST  FURNACES,  AND

                       REVERBERATORY FURNACES3

Sintering
Blast furnaces
Reverberatory
furnaces
Waste gas
(m3)
3000'
15,000-50,000r
100-500"
Raw-
Dust content
(gm/m3)
2-15
5-15
3-20
gas
SO2 content
1.5-5
~~
          " Clean Air Guide 2285, Kommission Reinlialtung der  Luft, Verein
        Deutscher Ingenieure, VDI—Verlag GmbH, Dusseldorf, West Germany,
        September, 1961.
          * Per ton of sinter.
          ' Per ton of coke.
          d Per ton of charge.


                  (SOURCE:   NELSON, Reference 3)

-------
                         7.8.19
(4)   Additional Equipment and Operations
     Since the by-products of lead  smelting contain recoverable
     amounts of cadmium and zinc oxide some plants  also  process
     this material.   Cadmium roasters, slag fuming  furnaces  and
     deleading kilns are used in these instances.   Emissions of
     sulfur oxides from these processes are minor relative to the
     total operation but dust and fume emissions can be  significant.
     The inspector should observe these operations  to determine
     their compliance with the appropriate regulation.

(5)   Contaminants Emitted
     While lead smelting operations are responsible for  a smaller
     volume of sulfur oxide emissions than from copper smelting
     the amounts are still appreciable.  In addition, a  substantial
     quantity of dust and fumes are generated in these operations
     which may be more significant  than gases or liquid  aerosols.

     Levels of concentration of emissions vary.  Gaps in data
     exist especially for dust and  fume emissions.

     Sintering machines will emit between 0.8 to 1.8 percent sulfur
     oxides by volume and from 5 to 20 percent of  the feed as
     dust and fumes.  Blast furnace emissions of sulfur  oxides
     will range between 0.01 to 0.25 percent.  Dust and  fume
     emissions from smaller secondary smelting operation using
     cupolas,  sampled by the Los Angeles  County Air Pollution
     District,  indicate a dust loading of 12.3 gr/SCF.   '
     Reverberatory furnaces also emit relatively small quantities
     of sulfur oxides usually less  than 0.05 percent, while  dust
     loading can be about 6 gr/SCF.

-------
                         7.8.20
     As in copper smelting, dust and fume collection is achieved
     by combinations of mechanical separators with baghouses or
     precipitators.

     Control of sulfur oxide emissions is variable since some of
     the processes emit lean mixtures.  In most instances,
     emissions of SO  from sintering operations are sufficiently
     rich for use in H.SO. plants which act, in effect, as air
     pollution control systems.
Zinc
Two principal "raw" materials are used in the production of zinc.
ZnS (sphalesite) which is separated by selective flotation to a
concentrate that contains 60% Zn and the slag from lead blast
furnaces where zinc is recovered as an impurity in fuming furnaces.
In both cases it is necessary to form dense zinc oxide for
extraction of the zinc by either pyroreduction and distillation or
electrolytic precipitation.

In the pyroreduction sequence, the concentrate is either roasted
and sintered in two separate processes or in a single process in
the sintering machine.  Figure 7.8.5    shows a typical operational
sequence of a zinc retort plant.  The potential air contaminants
emitted from these operations are SO  and zinc oxide fume.  The
latter, however, is a requirement for zinc production and will
probably be well controlled.

(1)  Roasting
     Roasting oxidizes about 93 to 97% of the sulfur in the concentrate
     to produce zinc oxide calcines.  The calcines contains 2 to 3-1/2%
     sulfur as sulfide and sulfate in a completely roasted batch.

-------
MOIST CONCENTRATE
                                                                           ROASTING GAS ^ TO ACID
                                                                                           PLANT


.f siKPFN^ioN I xT WASTE HEAT""! ,J HUMIDIFYING 1 ^
V| FJOASTfR I 	 1 5 BOILER 5 " \ CKAMEE_R_J
j 	 j^l; DRYING" 1 	
j[ SECTION | 1 £, „*
J! COAL or PET. COKE
4- If i?
j ,,, i ii, 6 I MIXING ANP 1 ^1 SINTERING 1 .
| OHLL ...i^u Jrrvri"F'~<:T->4Va 1 COKE
]| MI3C-RECYCLE
•<> ^ ^
| R c 1 0 R ( C 1 1 ; \ r. o c?
| MIXP.'G |
F1IFL f V^ i
S S pj i je O A*5

i ^mi.^"T'.i.^
i co s z:;ic" 1
5 COMDENSERS S
-, LIQUID ZINC METM 1
7 13'.. SO2 P"
]
f F_LECTP,OSTATIC1_J
| PRtCiPliATOR J
1
f
I
DUST 1
! COLLECTOR j|
	 	 1

SINTER GAS h
O.K.S02 P T°




                Figure 7.8.5.   TYPICAL ZINC RETORT PLANT  FLOW DIAGRAM^1)
                                (SOURCE:   ARTHUR G. MCKEE  &  CO.,  Reference 1)

-------
                                     7.8.22
                  A number of roasting methods are in use in the United States.
                  Table 7.8.7 gives an overview of names, operating conditions
                  and expected dust and SO- concentrations in the offgas.  Dust
                  collectors usually employed in roasting operations are electro-
                  static precipitators.  However, large quantities of dust settle
                  in the flues and waste heat boilers.  The resultant dust free
                  offgas, which contains from 4.5 to 12% SO-, is usually ducted
                  to an H SO, acid plant for collection or to tall stacks.

               Table 7.8.7-  TYPICAL ZINC ROASTING OPERATIONS
OPERATING
TEMP. F
1,200-1,350
1,600-1,650
1,200
1,640
1,650
1,700
1,800
1,900
FEED
CAPACITY
TON/DAY
50-120
250
40-50
140-225
240-350
240
120-350
225
DUST IN
OFFGAS
% OF FEED
5-15
5-15
5
70-80
75-85
50
50
17-18
OFFGAS
so2%
4.5-6.5
4.5-6.5
0.7-1.0
7-8
10-12
9-10
8-12
11-12
TYPE OF ROASTER
Multihearth
Multihearth (2)
Ropp (3)
Fluid bed (4)
Fluid bed (2)
Fluid bed (Lurgi)
Suspension
Fluid column
(1)  Dead roast except where noted otherwise (complete roasting using exothermic
       heat of reaction of sulfur with 0.).
(2)  First stage is a partial roast in multihearth,  second stage is a dry-feed
       dead roast  in fluid bed.
(3)  Partial roast •
(4)  Slurry feed.

                 (SOURCE:   ARTHUR G.  MCKEE & CO.,  Reference 1)

-------
                         7.8.23
(2)   Sintering
     Where roasting is used to oxidize the sulfur in the  concentrate,
     sintering is employed  to agglomerate the calcine.  Double-pass
     sintering is used in the absence of roasting operations.
     Table 7.8.8 describes  typical sintering operations with  the
     resulting dust and  SO. content.

  Table 7.8.8.  TYPICAL  ZINC SINTERING OPERATIONS
      Case:
      New feed material
      Total charge capacity
        tons cer day
      Machine size, ft
      Fuel added to feed, %
      Total auliiir in r.ew feed, '
      Recycle, % of new feed
      Oust in cffgas, % of feed
      Offgas SO2 content, %
  (SOURCE:   ARTHUR G. MCKEE & CO.,  Reference 1)
     Downdraft machines  are used in all sintering operations  in
     the zinc industry (as  opposed to both updraft and downdraft
     in lead—see description of sintering machines in
     Part  B,2,a).  The product is a hard pourous clinker  which is
     mixed with coke breeze to reduce the oxide that may  be
     present in retorts  and condensers.
1
calcine
240-300
3.5 x45
6-7
3
35-75
5
1.5-2.0
2
calcine
400-450
6x97
10-11
2
40-70
5-7
0.1
3
concentrate
550-600
12 x 16S
0-2
31
80
5-10
1.7-2.4
     The dust from the process  ranges  from 5 to 10% of the feed
     and is collected for  recycling or treated for lead and  calcine
     recovery.  The sulfur content in the offgas is low,  0.1 to  2.0%,
     but can be enriched to 6.0 to 6.5% by recycling to make it
     economically feasible for  collection in an acid plant.   How-
     ever, these gases are usually vented through tall stacks.

-------
                        7.8.24
(3)   Zinc  Extraction
     The steps  of  roasting,  sintering  and  calcining  (when performed)
     are necessary for  the preparation of  the material  for either
     pyroreduction or electrolysis  for extraction  of  zinc from
     zinc  oxide.

     1.  In pyroreduction the  sinter is mixed with coke breeze and
        processed in vertical retorts, horizontal retorts (the
        Belgian retort process), electric arc  furnaces or blast
        furnaces.  The vapor  formed is condensed  as  either liquid
        or solid  powder.  The Imperial Smelting Process,  not  in
        use in the United States,  uses a  blast furnace to vaporize
        zinc which is  condensed by a  shower of molten  lead.
        The zinc  dissolves  in the  lead and floats to the top  of
        the container  outside of the  condenser where it overflows
        and is cooled  to produce 98%  pure zinc.
     2.  The electrolytic zinc process produces high  purity zinc
        by using  calcine in H.SO,  solution to  remove impurities
        and a  lead anode and  aluminum cathode  to  accomplish
        the electrolysis.   The zinc is hand-stripped from the
        cathode,  remelted and poured  into slabs for  treatment.

(4)   Contaminants  Emitted
     Tables 7.8.7    and 7.8.8 ' show typical  concentrations  of  dust
     and S02 from  zinc  roasting and sintering operations.   Of  the 15
     primary zinc  smelters in  the United States, nine recover
     sulfur from the offgases  and these only from  roasters. The
     sulfur is  recovered as  sulfuric acid.

     Dust  and fumes which escape  the process or are  collected
     in  inefficient or  undersized dust collectors  are also a

-------
                               7.8.25
             potentially serious problem from this industry.   Large
             quantities of dust are transmitted in the roaster and
             sintering offgases and unless capture and recovery is
             excellent, significant quantities of small particles can be
             emitted to the atmosphere since nearly all of the particulates
             are <10M-

             Most dust and fume collection is achieved in baghouses and
             electrostatic precipitators.  The problem in these areas is
             pickup of particulates at the generation points  and their
             handling systems.

2.  Inspection Points—Primary Smelting and Refining
    The emission of sulfur oxides is the major contribution to air pollution
    from non-ferrous smelters.   Particulates, especially specific
    particulates such as lead,  are receiving increasing attention.

    a.  Environmental Observations
        When economics prohibit the capture of SO  in smelters, tall
                                                 X
        stacks are used to disperse the large quantities of sulfur oxides
        emitted.  Even with tall stacks, meteorological conditions and
        topography can cause the plumes to dip into areas adjacent to the
        smelters causing the classic S0« damage to plant life and
        respiratory difficulties.  Particulates (dust, fumes  and sulfuric
        acid mist) also can cause reduced visibility when meteorological
        conditions are conducive to the accumulation of air pollution.

        Section II, Kraft Pulp  Mills, describes methods of investigating
        the results of excessive emissions of sulfur oxides.   The assistance
        of residents and workers in adjacent areas is important since, in
        effect, 24-hour surveillances can be achieved.

-------
                            7.8.26
b.  Observations of the Exterior of Smelters
    Most processes in smelters vent to one or more tall stacks which
    theoretically allow the sulfur oxides to disperse to concentrations
    below those which would cause damage to plants, animals or buildings.
    Under some weather conditions the plume which is visible from the
    stack will bend into areas adjacent to the smelter.  The inspector
    should observe the plume during as many changes in plant operation
    as possible in order to correlate changes in opacity with differing
    operations.

    Dust and fume emissions from any pyrometallurigical processes
    and materials handling can be spotted from outside of the facility
    if the inspector is familiar with the plant layout.  Specific
    operations of concern include the loading and discharging of
    sintering machines, charging working furnaces and pouring from
    furnaces.  Zinc distillation furnaces, if not properly vented
    with close fitting high inlet velocity hoods, can lose fume which
    can be detected from roof monitors and windows of the building
    housing the processes.

    Large sections of smelter property may be unpaved and material may
    be stored in large piles without cover.  These points, common to
    many industries, should be noted and reported to plant management
    as high potential dust sources.

c.  In-Plant Observations
    Non-ferrous smelters comprise sizeable operations usually spread over
    many acres of ground and are frequently the subject of many studies
    and legal actions.   The inspector must present himself to plant
    management with a clear picture of the air pollution control
    regulations he is obligated to enforce.  He must obtain cooperation

-------
                                     7.8.27
            of management in order to thoroughly understand  the operations.   He
            should devote sufficient time to  observing the basic operations  to
            learn the cycles, time periods of day when the various  phases  of the
            operations occur and sequence of  operations and  identifying the
            management personnel responsible  for the various operations.   The
            McKee report    shows a flow diagram for many of the non-ferrous
            smelting operations in the United States.  This  is  an excellent  start-
            ing point for an inspector, but it must be emphasized that it  is only
            a starting point.  Also, the inspector should become very familiar
            with the maintenance practices of the company.  Maintaining the  con-
            trol equipment is probably the most important aspect of controlling
            emissions and is visually given last priority.

            Acid processes are treated in Section VII of this chapter.  They
            currently present the principal method of controlling S02 emissions
            from smelters.  The inspector should become familiar with the  venting
            system and be able to determine when the acid plant is  by-passed and
            the sulfur oxides are vented to atmosphere.

            Dust and fume control systems are a necessary part of smelter  opera-
            tions.  In addition to air pollution control requirements, large
            quantities of dust must be separated from the process gases and
            returned to the process.  Smelter offgases must  be cleaned before
            processing in the sulfuric acid plants.  The dust removal equipment
            consists of cyclone and other mechanical separators for large  particle
            size dust, and baghouses and electrostatic precipitators for condensed
            fume and small, < 10 fj. , dust particles.

C.  NATURE OF SOURCE-SECONDARY SMELTERS
    As a class, secondary smelters and refiners reclaim metals from scrap,
    drosses and slag.   Operations and equipment for brass and br.onze, lead, zinc,
    and aluminum are described in this section.  Smoke, dust, fumes, sulfur oxides,
    fluxing and degreasing agents are typically emitted.

-------
                                7.8.28
Large copper secondary smelters employ many of the same operations used
in primary smelting with the exception of roasting.   Precious metals are
also recovered from electrolytic refining slimes at  both primary and
secondary copper smelters.

1.  Process Description—General
    A variety of metal alloys are produced in several basic types of
    furnaces.  Reverberatory furnaces are used in the secondary smelting
    and refining of copper  bearing alloys, aluminum  and lead; blast furnaces
    or cupolas are used in  copper and lead production; pot furnaces,
    crucibles and electrical induction furnaces are  used for various
    refining processes in all non-ferrous operations.  Zinc production alone
    has unique furnace requirements for secondary refining.  This process
    requires retorts and condensers and holding furnaces for some refining
    processes.

    a.  Brass and Bronze
        The basic steps in  producing brass and bronze ingot in secondary
        smelters are:
        •   Materials Preparation
            •   Mechanical  Methods
                •  Hand Sorting
                •  Stripping
                o  Shredding
                • ^Magnetizing
                •  Briquetting

-------
                        7.8.29


    •   Pyrometallurgical Methods
        •  Sweating
        •  Burning (Insulation Removal)
        •  Drying
        •  Blast furnace or Cupola (melting or oxide reduction)
    •   Hydrometallurgical Methods—flotation process
•   Ingot Production
    •  Reverberatory Furnaces
    •  Rotary Furnaces
    •  Crucible Furnaces

While not all of the steps or equipment involved in the total
process emit air contaminants, the inspector should be familiar
with the total cycle.  In all brass and bronze production the
primary air pollution control problem is the emission of zinc
oxide during melting and pouring to produce the ingot.  This
naturally is a function of the zinc in the metal to be produced
and in the metal that makes up the charge to the furnaces.
Table 7.8.9    shows the nominal specifications of copper base
alloys commonly produced in the United States.  As the zinc and
lead content increases, melting operations become more critical
relative to potential zinc oxide and lead oxide emissions.   Other
likely contaminants from these processes are dust and smoke from
fuel combustion and from grease and oil present in the scrap used
as charge material.

This industry scavenges material to be refined into ingot to meet
the specification shown previously.  The source of this material is
the scrap salvage industry.  Table 7.8.10    describes the major types
of industrial and military scrap which become the raw material
charged to the secondary brass smelter.

-------
                                7.8.30
Table 7.8.9.   NOMINAL CHEMICAL SPECIFICATIONS FOR BBII STANDARD ALLOYS
Alloy
No. Classification
1A Tin bronze
IB Tin bronze
2A Leaded tin bronze
2B Leaded tin bronze
2C Leaded tin bronze
3A High-lead tin bronze
3B High-lead tin bronze
3C High-lead tin bronze
3D High-lead tin bronze
3E High-lead tin bronze
4A Leaded red brass
4B Leaded red brass
5A Leaded semi-red brass
5B Leaded semi-red brass
6A Leaded yellow brass
6B Leaded yellow brass
6C Leaded yellow brass
7A Manganese bronze
8A Hi-strength mang. bronze
SB Hi-strength mang. bronze
8C Hi-strength mang. bronze
9A Aluminum bronze
9B Aluminum bronze
9C Aluminum bronze
9D Aluminum bronze
10A Leaded nickel brass
10B Leaded nickel brass
11A Leadeti nickel bronze
11 B Leaded nickel bronze
12A Silicon bronze
12B Silicon brass
Cu.%
88.0
88.0
88.0
87.0
87.0
80.0
83.0
85.0
78.0
71.0
85.0
83.0
81.0
76.0
72.0
67.0
61.0
59.0
57.5
64.0
64.0
88.0
89.0
85.0
81.0
57.0
60.0
64.0
66.5
88.0
82.0
Sn,r.
10.0
8.0
6.0
8.0
10.0
10.0
7.0
5.0
7.0
5.0
5.0
4.0
3.0
2-5
1.0
1.0
1.0
1.0







2.0
3.0
4.0
5.0


Pb, %


1.5
1.0
1.0
10.0
7.0
9.0
15.0
24.0
5.0
6.0
7.0
6.5
3.0
3.0
1.0
1,0







9.0
5.0
4.0
1.5


Zn.%
2.0
4.0
4.0
4.0
S.O

3.0
1.0


5.0
7.0
9.0
15.0
24.0
29.0
37.0
37.0
39.0
24.0
24.0




20.0
16.0
8.0
2.0
5.0
14.0
Fe, %

















1.0
1.0
3.0
3.0
3.0
1.0
4.0
4.0




1.5

Al.%

















0.6
1.0
5.0
5.0
9.0
10.0
11.0
11.0






Ni.%























2.0
4.0
12.0
16.0
20.0
25.0


Si,%





























4.0
4-0
Mn,%

















0.5
1.5
3.5
3.5


0.5
3.0




1.5

            (SOURCE:  CUFFE AND SCHWARTZ, Reference 5)

       (1)  Blast Furnaces and Cupolas
            The blast furnace is  an economical method of recovering copper
            from low grade scrap  and slag.   The material is charged through
            the top of  the furnace with varying amounts of coke and lime-
            stone.   Blast air is  blown through the tuyeres at the bottom of
            the furnace.
            By its  nature,  the blast furnace uses large quantities of air
            for combustion which creates a significant air pollution control

-------
                                7.8.31
Table  7.8.10.   TYPES  OF COPPER-BEARING  SCRAP
       No.
                                  Designation
        1.
        2.
        S.
        4.
        5.
        6.
        7.
        8.
        9.
       10.
       11.
       12.
       13.
       14.
       15.
       16.
       17.
       18.
       19.
       20.
       21.
       22.
       23.
       24.
       25.
       26.
       27.
       28.
       29.
       30.
       31.
       32.
       33.
       34.
       35.
       36.
       37.
       38.
       39.
       40.
       41.
       42.
       43.
       44.
       45.
       46.
       47.
       48.
       49.
       50.
       51.
       52.
       53.
       54.
No. 1 copper wire
No, 2 copper wire
No. 1 heavy copper
Mixed heavy copper
Light copper
Composition or red brass
Red  bras? composition turnings
Genuine babbitt-lined brass bushings
High-grade, low-lead bronze solids
Bronze papermill wire cloth
High-lead bronze solids and borings
Machinery or hard red brass solids
TJnHncd standard red car boxes (clean journals)
Lined standard red car boxes (lined journals)
Cocks and faucets
Mixed brass screens
Yellow brass scrap
Yellow brass castings
Old rolled brass
New brass clippings
Brass shell cases without primers
Brass shell cases with primers
Brass small arms and title  shells, clean fired
Brass small arms and rifle  shells, clean muffled (popped)
Yellow brass primer
Brass pipe
Yellow brass rod turnings
Yellow brass rod ends
Yellow brass turnings
Mixed unsweated auto radiators
Admiralty brass condenser  tubes
Aluminum brass condenser  tubes
Muntz metal tubes
Plated rolled brass
Manganese bronze solids
New cupro-nickel clippings and solids
Old cupro-nickel solids
Soldered cupro-nickel solids
Cupro-nickel turnings and borings
Miscellaneous nickel copper and nickel-copper-iron scrap
New  monel clippings and solids
Monel rods and forgings
Old monel sheet and solids
Soldered monel sheet and solids
Soldered monel wire, screen, and cloth
New  monel wire, screen, and cloth
Monel castings
Monel turnings and borings
Mixed nickel silver clippings
New  nickel silver  clippings and solids
New  segregated nickel silver clippings
Old nickel silver
Nickel silver castings
Nickel silver turnings
       (SOURCE:    CUFFE AND SCHWARTZ,  Reference  5)

-------
                    7.8.32
problem.  Depending upon local air pollution control agency
requirements, high efficiency scrubbers, baghouses and electro-
static precipitators, with primary separators for the removal
of larger size particles, are used to control emissions.  The
baghouse has proven to be an excellent control device for
cupola operations, if properly sized.  As important as the
dust removal system is, the design of the fume pick-up system
should include good indraft velocity at the furnace charging
door and hooding over the metal pouring spout.

The blast furnace or cupola is usually operated 24 hours per
day with continuous slag pouring and intermittent metal pouring.
Observation by the inspector should include furnace startup;
at least for one hour's operation to determine if excessive
smoke and fume escape during charging; inspection of the hoods
and ductwork to determine if they are in good repair and if
the efficiency of dust pickup has degraded.  The operation of
the air pollution control equipment, depending on the type used,
must also be monitored.

The physical location of the dust and fume controls relative
to the furnace may make observations of both control systems
difficult, necessitating a two-man inspection.  Efficiency
of the air pollution control equipment can only be accurately
checked by stack analysis.  The inspector can, however, note
gross changes in efficiency by comparing differences in opacities
of emissions under different operating conditions.

-------
                       7.8.33
     Other  preparational  operations which can cause emissions
     are  sweating,  drying and burning.  The removal of insulation
     by burning  is  covered in the  section on incineration.
     Sweating  to remove solder  and other low melting point alloys
     can  cause smoke  and  particulate  emissions, depending upon the
     material  being processed.  The inspector should observe the
     precleaning or other precautions taken to assure minimum
     emissions from this  operation.   He should recommend the use
     of incinerators  or scrubbers  if  a large volume operation is
     involved.

     Drying chips require the use  of  afterburners or incinerators
     since  the removal of oil by volatalization with resultant
     generation  of  opaque smoke and oil mists is involved.  It
     will be obvious  from the heavy emissions of smoke and mists
     that the  afterburner is not in use, or is defective.

(2)   Ingot  Production—Reverberatory  Furnaces
     The  basic furnace in a brass  secondary smelter is the
     reverberatory  furnace. It is usually gas or oil fired and
     can  be either  of the open  hearth or rotary type, operating
     between 2300°F to 2600°F.  In the production of brass and
     bronze ingot the inspector must  be aware of the time periods
     of the operation during which most of the fume is generated, the
     condition of the material  charged (oily or greasy) and the
     operation of the air pollution control system.  The critical
     periods are charging either "raw" material or zinc slabs, to
     reach  the desired specification, oxygen blowing if used, and
     pouring.  Dense  clouds of  condensed fume or black smoke can
     occur  due to charging of oily scrap.  These emissions may
     be of  such  magnitude that  the fume pickup system may not be

-------
                                     7.8.34
                 able  to handle  the volume.   The same is true during  air or
                 oxygen blowing.   Pouring, which can take 1  to  3  hours,  also
                 generates  large quantities of fume.  The inspector should
                 observe these operations for time and opacity.   It is doubtful
                 if any sizeable brass reverberatory furnace can  meet time
                 and opacity  standards without a well designed  air pollution
                 control system.


                 The operation of other types of furnaces that  may be found
                 in a  smelter, i.e., crucible and induction  furnaces  are
                 described  in Section IX of this chapter.
                 Quantitative  and qualitative emissions from secondary  brass
                 smelting  operations are shown in the following  tables.
          Table 7.8.11.   ROTARY FURNACE PARTICULATE EMISSIONS—TEST A
Cycle
Charge^
Refine
Pour
Total
Length, hr
6.50
6.80
1.28
14.58
Emissions, furnace2 Baghouse outletb
Ib/hr
30.05
42.75
9.54

Cycle total, Ib
195
291
12
498
Ib/hr

1.78
Total, Ib

25.9
             aFmnace emission factor: 29.9 In/ton.
             bCollection efficiency: 94.8 percent.
             cTotal charge:  33,334 Ib. Alloy produced: BBII Alloy No. 4A; 85-5-5-5.

             (SOURCE:   CUFFE  AND SCHWARTZ, Reference 5)
Test A
A heat of red brass 85-5-5-5 (copper, zinc, tin, lead) was made  in  a  17-1/2 -
ton-rated rotary furnace.  A total  of 33,334 pounds of scrap and 500  pounds of
flux were charged  to the furnace  during the 6.5-hour charging period.   Air blow-
ing, slagging, and heating were performed during the 6.8-hour refining cycle.
The pouring  cycle  lasted 1.3 hours.
During this  test,  only the 17-1/2-ton rotary furnace was operating.   Inlet samples
were collected during  each period.   A single sample was taken at the  baghouse
outlet over  the entire heat.  The exhaust system captured an estimated 90 to
95 percent of the  particulate  generated at the furnace.

-------
                                       7.8.35
Table  7.8.12.   REVERBERATORY FURNACE PARTICULATE  EMISSIONS—TEST  C
Cycle
Charge0
Refine
Pour
Total
Length. In
6.73
9.30
3.53
19.56
Emissions, furnacea
Ib/hr
194.2
159.3
12.8

Cycle total, Ib
1.308
1.482
45
2,835
Baphouse outlet^
Ib/ht

3.32
Total, Ib

64.8
         aFurnace emission factor: 53.7 Ib/ton.
         ^Collection efficiency; 97.7 percent.
         cTotal charge: 105,500 Ib. Alloy produced: BBII Alloy No. 4A; 85-5-5-5.

        Test C     (SOURCE;   CUFFE AID SCHWARTZ,  Reference 5)

            A heat of 85-5-5-5 red brass was made in <± 100-ton reverbera-
        tory furnace.  A total of 105, 000 pounds oi metal was charged to the
        furnace  over a period of 6. 7  hours.   Oxygen was supplied to the
        burners for 5. 3 of these hours  to increase the melting rate.  During
        a 9. 3-hour refining period there was intermittent air blowing, and
        500 pounds of fluxes  were added.   Pouring took 3. 5 hours.

            This air pollution control system serves three 100-ton reverber-
        atory  furnaces.   The gases pass  through  a common spray chamber
        and then through a set of U-tube radiation coolers.  From this point,
        the  450° F to 650° F gases arc mixed with bleed-in air, go through
        the baghouse and  a 75-horsepower fan,  and pass to the stack.  The
        16-compartment shaker-type baghouse is  fitted  with heat-set Orion
        bags.  The total filter area is 7, 360 square feet and the rated capac-
        ity is  19, 000 cfm at  220° F.  The design  filter ratio, with one  com-
        partment  out for  cleaning, is 2,75/1.

            Measured gas temperature at the baghouse inlet cycled between
       •200° F and 220° F.  The measured gas volume averaged 15, 000 scfm
        (70° F).  Baghoxise pressure drop varied from 4 to 5 inches of water.

            One inlet sample was taken during each of these three furnace
        period-s: charging, refining,  and pouring.   A continuous baghouse
        outlet  sample was laken over the entire heat.

-------
                         7.8.36
 Table 7.8.13.   CUPOLA PARTICULATE EMISSIONS—TEST
Sample
E-l
E-2
E-3
Average
Inlet
gr/sct
0.68
0.68
Ib/hr
216
216
Outlet
gr/scf
0.027
0.030
0.020
0.026
Ib/hr
8.38
9.25
6.38
8.00
          "Charging rate: 5900 Ib/hr. Collection efficiency: 96,4 percent.
           Furnace emission factor: 73.2 Ib/ton.
    Test E
        At the system described in Test A, samples were taken while
    only the cupola was in operation. The cupola was charging at 20-
    minute intervals at the rate of 5, 900  pounds per hour, including
    coke and flux.
        Gas temperature at the baghouse was 145° F to 200°  F and the
    volume was 44,000  scfm.  The filter  ratio was 2.11/1.
        (SOURCE:   CUFFE AND SCHWARTZ,  Reference  5)
Lead
Secondary  lead operations produce lead alloys  and oxides  employing
reverberatory furnaces, pot  furnaces, cupolas  and the Barton Process
for oxides.   Sweating operations are also used to recover lead and
other low  melting alloys.
(1)  Reverberatory Furnaces
     Battery  plates, dross and  slag are melted  in direct  gas  or
     oil fired  reverberatory  furnaces for lead  reclamation (Table
     7.8.14).   The operation  of  the furnace  is  "tight" to  allow
     admission  of as little air  as possible  in  order to maintain
     the furnace temperature  of  2300°F.  The furnace is recharged
     at regular intervals as  the mass of the charge becomes fluid.
     About 10 to 12 pounds of metal are produced per squart foot
     of hearth  area.  '  The  furnace is tapped  at regular  intervals
     and is kept in continuous  operation.

-------
                           7.8.37
     Table  7.8.14.  CHEMICAL REQUIREMENTS FOR LEAD
              (ASTM Standards,  Part 2, 1958)

Silver, max %
Silver, min. %
Copper, max %
Copper, min. %
Silver and copper together,
max %
Arsenic, antimony, and
tin together, max %
Zinc, in ax %
Iron, max %
Bismuth, max %
Lead (by difference),
min. %
Cor r oding
lead
0. 0015

0. 0015

0. 0025
0. 002
0. 001
0. 002
0. 050
99. 94
Chemical
lead
0. 020
0. 002
0. 030
0. 040

0. 002
0. 00]
0. 002
0. 005
99. 90
Acid-
roppcr
lead
0. 002

0. 080
0. 040
0. 040
0. 002
0. 001
0. 002
0. 025
99. 90
Common
desilveri/.ed
lead
0. 002

0. 0025


0. 005
0. 002
0. 002
0. 150
99. 85
aCorroding lead is a designation used in the trade for many years to
 describe lead refined to a high degree of purity.
 Chemical lead is ,i term used in the trade to describe the undesilverized
 lead produced from Southeastern Missouri ores.
 Acid-copper lead is made by adding copper to fully refined lead.
 Common desilverized lead is a designation used to describe  fully
 refined desilverized lead.
           (SOURCE:  NANCE,  et_ al_.,  Reference 6)

        The operation  of  a lead reverberatory furnace produces smoke

        and fumes by the  nature of the operation.  It is therefore

        necessary that an adequate air pollution control system be a

        part of the furnace  design.   The inspector  must observe the

        charging and pouring operation to determine the collection

        efficiency of  the fume pickup system since  these are periods

        of  heavy emission production.  During the melting phase of the

        operation some smoke and fume escaping  from the doors and

        other openings may occur due to the low negative pressure in

        the furnace.   Indrafts at the hoods over these openings

-------
                        7.8.38
     should  be  high  enough  to  prevent  the  escape of puffs or
     continuous streams  of  fume.   Baghouses  are usually used to
     collect the particulates  from lead  refining operations.
     Table 7.8.15    describes  the operating characteristics of an
     exhaust system  and  baghouse on a  lead reVerberatory furnace.
     In addition to  dust and fumes,  emissions of sulfur oxides are
     emitted.   Stack analysis  should be  requested to determine the
     extent  of  these emissions.  The requirements of the individual
     agency  will govern  the necessity  for  additional SO  controls.
                                                       X

(2)   Blast and  Cupola  Furnaces
     These furnaces  are  similar to those used in grey iron foundries
     in physical appearance.  They are used  to produce lead from
     dross,  oxide and  reverberatory  slags  using a mixture of cast
     iron and limestone  to  form slag and coke for heating and
     reduction.   The furnace is charged  through a door near its
     top and blast air is blown in through tuyeres near the bottom.
     This is a  continuous operation  with the lead being discharged
     in a continuous tap and the slag  being  tapped intermittently.
     The tuyere air, as  it  is forced through the furnace,  picks up
     dust and fumes  which are usually  vented to a baghouse.   The
     furnace operates  at between 1200°F  and  1300°F and produces
     large volumes of  CO, which must be  burned to CO ,  and
     particulates.   A  high  inlet velocity  at all openings  is re-
     quired  to  prevent the  escape  of dust  and fumes.   The
     inspector  should  observe a light  off  and at least an  hour of
     the operating cycle to determine  that the air pollution control
     system  is  functioning  properly.   In a properly controlled
     operation,  the  system  should  be tight with no appreciable
     escape  of  smoke or  fume from  the  furnace during any phase of
     its operation.

-------
                                        7.8.39
               Table 7.8.15.   DUST  AND FUME EMISSIONS  FROM A
                                 SECONDARY  LEAD-SMELTING  FURNACE
                                   (6)
Test No.
Furnace data

  Type of furnace
  Fuel used
  Material  charged
  Process v/eight,  Ib/hr
Reverberalory
Natural gas
Battery groups
          Z, 500
                                  Sectioned tubular bagbousc'
                                  D a c r on
                                           16, 000
                                                0. 98
                           Sectioned tubular baghousec
                           D a c r on
                                   16, 000
                                        0. 98
                                            3, 060
                                           10, 400

                                              951
                                              327
               b
         2, 170
        13, 000h

            500
            175
Control equipment data
  Type of control equipment
  Filler material
  Filter area, ft2
  Filler velocity, fpm at 327 °F
Dust and fume data

  Gas flow rale, scfm
   Furnace outlet
   Bagbouse  outlet
  Gas temperature, °F
   Furnace outlet
   Baghouse  outlet
  Concentration, gr/scf
   Furnace outlet
   Bagbouse  outlet
  Dust and fume emission,  Ib/hr
   Furnace outlet
   Baghouse  outlet
  Baghouse efficiency,  %
  Baghouse catch,  wt %
   Particle size       0 to  1 (a.
                      1 to  2
                      2 to  3
                      3 to  4
                      4 to 16
  Sulfur  compounds as SO^, vol %
   Baghouse  outlet.
aThe same baghouse alternately serves the  reverberatory furnace and the blast furnace.
 Dilution air  admitted to cool  gas stream.
                                                4. 98
                                                0. 013

                                              130. 5
                                                1. 2
                                               99. 1

                                               13. 3
                                               45. 2
                                               19. 1
                                               14. 0
                                                8. 4

                                                0. 104
Blast
Coke
Battery groups,  dross,  slag
         2, 670
                                       12.3
                                        0. 035

                                      229
                                        3. 9
                                       98. 3

                                       13. 3
                                       45. 2
                                       19. 1
                                       14. 0
                                        8.4

                                        0. 03
                        (SOURCE:   NANCE, j^t  al., Reference 6)

-------
                        7.8.40
(3)  Pot Furnaces
                                                     (6)
     Pot furnaces range in capacity from 1 to 50 tons    and
     are used to alloy and refine lead.  These furnaces should be
     hooded and vented to air pollution control equipment
     to meet both air pollution regulations and industrial
     hygiene requirements.  Emissions can occur when drying dross
     to remove as much lead as possible by introducing sawdust;
     adding sulfur and agitating to reduce copper; or adding
     aluminum to reduce copper, antimony and nickle.  The resultant
     slag is then skimmed from the pot.  Hooding must be properly
     designed to pickup the fume and smoke generated by these
     actions.  A special application is the production of lead
     oxide for battery lead, red lead and paint by the Barton
     Process.  Lead at 700°F to 900°F is agitated by paddles
     while air is drawn through the molten metal.  The resultant
     lead oxide is exhausted to a baghouse where the condensed
     fume is captured.  This process is "closed" and should not
     emit appreciable fume.

Zinc
The reclamation of zinc in secondary smelting operations is performed
by vaporizing or oxidation.  The products from secondary zinc
smelting are zinc, zinc oxide, and powdered zinc.  Some zinc is
also recovered in sweating operations described previously in this
section.

The processes to reduce zinc oxide to metallic zinc uses powdered
dross, collected zinc oxide condensed fume and contaminated zinc
oxide from zinc plants all mixed with powdered coke and water to
form a paste.  The material is then charged to retorts for treating
by the Belgian Retort Process.  The retorts are arranged in banks

-------
                                 7.8.41
        and  are  heated externally by either  gas  or oil fired burners.  The
        operating cycle is usually 24 hours  with 65 to 70% of the zinc in
        the  charge recovered with the remaining  charge recycled.
        Temperatures on the outside of  the retorts reach 2,550°F.  The
        temperature of the charge is slowly  brought up to 2,280°F.  A
        carbon dioxide rich atmosphere  in the  retorts actually reduces
        the  zinc where it is condensed  in the  cooler, 780° to 1,020°F
        condenser section.  Tapping of  the zinc  begins after about 8 hours.
        Figure  7.8.6
        furnace.
                     (6)
shows a cross section  of  a single Belgian retort
   GROUT JOINT
   CONDENSED METAL
   VAPORS
                                           METALLIC OXIDE CHARGE
                                           KITH REDUCING MATERIALS
    BURNER PORT
Figure 7.8.6.  DIAGRAM SHOWING ONE BANK OF A BELGIAN RETORT FURNACE
                (SOURCE:   NANCE, et al., Reference  6)

-------
                             7.8.42
     Distillation furnaces  can produce zinc,  zinc oxide or zinc powder
     using molten zinc  as the charge.   The distillation type retort
     furnace shown in Figure  7.8.7     is  charged with molten zinc from a
     pot furnace.  The  retort is  externally heated,  vaporizing the zinc.
     The condenser is under positive pressure to prevent the zinc vapors
     from being oxidized while they condense.  If zinc oxide is to be
     manufactured the zinc  vapor  goes  through an orifice where it is
     mixed with air for oxidation.   When  the  condenser is used it is
     vented through an  opening called  a speise hole.  Here the zinc
     vapor burns and must be  captured  by  a special hood provided for
     this purpose.
                                                       SPEISE HOLE .
Figure 7.8.7.   DIAGRAM OF A DISTILLATION-TYPE RETORT FURNACE
               (SOURCE:   NANCE,  et_al.,  Reference 6)

-------
                           7.8,43
  A second procedure employed to produce either pure zinc  (99.99%)
  and pure oxide (99.95%) is conducted in a muffle furnace  (Figure
  7.8.8   ).   This  system can handle scrap metal directly in its zinc
  feed well and sweating section.  The furnace is heated by gas or
  oil firing with the products of combustion passing over the  zinc
  feed well after heating the vaporizing section to 2,500 F.
  Molten zinc is formed in the condenser and maintained at about
  900 F.  When zinc oxide is to be formed, the vapors go through an
  orifice at the top of the first chamber and are mixed with air.
  The resultant zinc oxide is exhausted to a baghouse where it is
  collected.
                                                         DUCT FOB OKIOE
                                                         COLLECTION
                                                         RISER CONDENSER
                                                         UNI T
Figure 7.8.8.  DIAGRAM OF A MUFFLE FURNACE AND CONDENSER
               (SOURCE:   NANCE, et_ al_. , Reference 6)

  The inspector must become familiar with the operating procedure  of
  the particular plant and the equipment.  Every operation  can  have
  significant modifications to its equipment which  can make it
  unique.  Capture of condensed oxide fume or smoke from  any opening
  in the aforementioned systems is the primary consideration.   Air
  pollution control field personnel must physically check all phases

-------
                            7.8.44
    of operation of these types of furnaces to make certain that the
    systems are tight and have minimal leaks.

d.  Aluminum
    Aluminum refining operations encompass many of the processes
    described in brass and bronze refining.  Principal operations are
    chip drying, sweating, and pyrometallurgical refining.

    Pit and crucible furnace operations are described in the section
    on foundries.  This subsection will emphasize reverberatory
    furnaces since chip drying and sweating have been treated.

    Reverberatory furnaces for aluminum refining range in capacity
    from 3,000 pounds to 50 tons and over.  These are usually gas or
    oil fired and are continuously operated in large facilities.   As
    in most metallurgical processes the production is batch, that is
    there is a charging phase, a working and fluxing phase and
    pouring.  A heat can vary in length from 4 to 72 hours.
    The furnace is used to melt varied types of scrap and usually has
    a well where chips and other thin section scrap is charged into
    a molten bath.   Figure 7.8.9    shows  a 20-ton aluminum reverber
    tory furnace with a fume collection hood over  the well.
    In order to prevent burning of thin-walled sections that may be
    charged to the furnace,  a heel of metal is required.   This heel
    is formed by melting heavy pieces of scrap or ingot prior to the
    introduction of the lighter material.

    The major air pollution  control problem from aluminum refining
    operations arises  from the fluxing and degreasing necessary to bring
    the melt to the specification required.  Large quantities of solid

-------
Figure 7.8.9.
A 20-TON ALUMINUM-MELTING REVERBATORY FURNACE WITH CHARGING
WELL HOOD, AARON FERRER & SONS, INC., LOS ANGELES. CALIFORNIA
(SOURCE:  NANCE, et_ al., Reference 6)
                                                                                               QO

                                                                                               Ui

-------
                               7.8.46
        fluxes, as much as 1/3 the weight of  the aluminum scrap  charged,
        may be  required to prevent oxidation  and gas  absorption.  Fluxes
        that cause dense  emissions are  those  used  for degreasing and
        magnesium reduction.  Chlorine  gas  and  aluminum fluride  are
        commonly used  for magnesium  reduction and  cause the most extensive
        emissions.

        The inspector  should become  completely  familiar with the furnace
        operating cycle.  He should  observe the type  of scrap  charged  to  the
        furnace to determine if smoke and other particulates from the  melting
        of  dirty scrap are likely to occur.   He should  know the  type and
        quantity of fluxes used.  The Air Pollution Engineering  Manual can
        be  used as a' reference on fluxing operations.

2.   Inspection  Points—Secondary  Smelting and Refining
    Secondary smelters are usually located  in areas zoned for  heavy
    industry so that the  likelihood  of  nuisance complaints from  these
    operations  may not be great.  Odors also  are not  generally attributed
    to secondary smelters but there  can be  significant quantities of dust
    created by  some of the operations.  Some  copper refining operations can
    emit SO-, although usually below the odor threshold of 1.0-5.0 ppm.

    a.  Environmental  Observations
        Dust and particulate fallout from metal preparation may  be the
        most pronounced problems  in  areas adjacent to secondary  smelters.
        These include mechanical  shredding  and  size reduction, sweating
        and incineration. Relatively large dust particles and fly ash
        may be  emitted from these operations  and settle near  the company
        in  question.

-------
                            7.8.47
b.  Observation of the Exterior of the Secondary Smelter
    Most of the processes of concern in secondary smelting and refining
    require heat to complete the operation.  Usually one or more
    stacks are employed to vent the products of combustion or air
    pollution control system effluents.  The inspector can pinpoint
    the stack or roof monitor emitting excessive smoke, dust or
    fumes and work backwards to the process or equipment
    responsible for the emissions.  The color, opacity
    and length of plume can be of help in determining the source of
    the problem.  Incinerators used for copper wire reclamation will
    emit dense black smoke if overloaded or if the auxiliary fuel is
    not in use.  Sweat furnaces will do the same if the afterburner
    is not in operation.  If a baghouse has torn bags it may appear
    to be burning if it is a push-through type; if the baghouse is
    a pull-through type the opacity of emissions from the stack can
    be over 50% when they would otherwise be near 0%.

c.  The Physical Inspection
    After obtaining the necessary data from the outside of the
    plant, the inspector should contact plant management to make the
    inplant inspection.  If the inspector is completely familiar with
    the plant he can inform the operator which process caused the
    problem.  If he is not familiar with the operation he should
    describe the color and opacity of the emissions and try to determine
    their origin.  Determination of the equipment responsible for
    the emissions can present a problem in plants where many processes
    are vented to one stack.  A plant survey should be one of the first
    requirements for an inspector who is new to an area.

    During furnace inspections it is necessary to observe:

-------
                        7.8.48



•   Charging operations
    •   Type and quantity of material charges
•   Working or fluxing operations
    •   Type and quantity of flux added
•   Pouring operations
•   Fuel being used

Mechanical inspection of equipment should include:
•   Repair of furnace and doors for leaks
•   Repair of hoods and ductwork
    •   Pickup efficiency
•   Effectiveness of air pollution control equipment

The inspector can make qualitative judgments of dust and fume
emissions but he may have to rely on stack tests for quantitative
results.  These tests should not be limited to the stack.  There
are times when emissions from charging doors, hearths or from
pouring can be very significant if not properly hooded and vented
to an air pollution control system.

Figure 7.8.1CT5' is a convenient scale showing the boiling,
pouring and melting points of metals and alloys.

-------
                    7.8.49
Figure 7.8.10.  BOILING, POURING, AND MELTING POINTS
                OF METALS AND ALLOYS (SOURCE:  CUFFE
                AND SCHWARTZ, Reference 5)

-------
                                    7.8.50
                                 REFERENCES

1.   Systems Study for  Control  of Emissions, Primary  Non-Ferrous  Smelting
    Industry,  Volumes  I,  II  and  III.  Arthur  G. McKee  &  Co.   Contract  PH
    86-65-85.   DHEW, PHS,  NAPCA.  June  1969.

2.   Semrav, K. T.   Control of  Sulfur  Oxide Emissions from Primary  Copper,
    Lead and Zinc Smelters,  A  Critical  Review.  J. Air Pollution Control
    Association.   Vol.  21, No. 4.  April  1971.

3.   Nelson, K. W.   Nonferrous Metallurgical Operations.   Air  Pollution,
    Vol.  Ill,  A.  C. Stern  (ed.).  New York City, Academic Press.   1968.

4.   Konopka, A. P.  Particulate  Control Technology in  Primary Non-Ferrous
    Smelting.   Presented  at  Third Joint Meeting, American Institute  of
    Chemical Engineers  and Institute  Mexicano De Ingenieros Quimicos.
    Denver, Colorado.   September 1970.

5.   Cuffe,  S.  T.,  and  E.  S.  Schwartz.   Air Pollution Aspects  of  Brass  and
    Bronze  Smelting and Refining Industries.  DHEW, PHS,  NAPCA.  A.P.  58,
    November 1969.

6.   Nance,  J.  T.,  W. F. Hammond,  and  K. D. Luedtke.  Lead Refining.
    G. Thomas. Zinc Melting.  H. Simon.  Aluminum.  In:  Air Pollution
    Engineering Manual, J. A. Danielson (ed.).  Cincinnati, DHEW,  PHS,
    National Center for Air  Pollution Control and the  Los Angeles  County
    Air Pollution Control  District.   P.H.S. No. 999-AP-40.  1967.

-------
                                   7.9.1
                   IX.   FERROUS AND NON-FERROUS FOUNDRIES

A.  DESCRIPTION OF SOURCES
    The products of the ferrous and non-ferrous metallurgical industries are
    oriented to consumer or industrial use while smelters and refiners,  dealt
    with in other sections of this chapter, provide alloys in ingot form to
    be used by the foundries.

    While furnaces and melting practices have long been treated as 'major
    sources of air pollution from foundries, other operations also contribute.
    Among these are core making, sand handling, grinding, buffing and plating.
    Melting operations produce smoke and condensed fumes while the other
    operations produce dust, mists, organic gases and vapors.

B.  GREY IRON FOUNDRIES
    Ferrous foundries depend upon the cupola for the economical production
    of large quantities of grey iron.  Electric furnaces and small
    reverberatory furnaces are also used in some specialty shops.  Grey iron
    foundries have core making facilities, sand handling equipment and
    shakeout systems which are described under non-ferrous foundries below.
    The cupola is the oldest and still the most universally used furnace for
    the production of grey iron and a large contributor to air contaminants
    if not adequately controlled.

    1.  Process Description
        A cupola is a firebrick-lined vertical cylindrical steel shell,  approx-
        imately 27" to 108" in diameter, supported on structural steel legs.
        Air is supplied through a windbox and tuyeres (Figure 7.9.1) by either
        positive  displacement blowers, centrifugal blowers or fan type
        blowers.  As in blast furnaces, air is the largest single constituent

-------
                        7.9.2
BOTTOM DOOR
IN
POSITION
   Figure  7.9.1.   THE CUPOLA IN DETAIL (SOURCE:  AIR POLLUTION
                   ENGINEERING MANUAL)

-------
                           7.9.3
of the heat, its weight being dependent on the size of the furnace and
the metal to be melted.  Some foundries recycle waste heat from the
cupola to preheat the combustion air as an economy measure.

Preparation of a cupola for melting consists of preparing the bottom
by securing the bottom drop door, placing a layer of sand over the
door to prevent heat damage, closing the tap and slag holes and
charging coke for the bed.  The bed is ignited and allowed to burn
through.  The charges of coke, flux (limestone, fluorspar and soda
ash) and metal (pig iron, scrap and steel) are placed in alternate
layers up to the charge door which is 16' to 22' above the bottom.
The blast is then turned on and melting begins.  Charging continues
until the desired tonnage has been melted after which the air is shut
off and the furnace bottom is dropped allowing the remaining charges
to fall on to the foundry floor.  This material is recharged during
the next operating cycle.  Table 7.9.1 is a compilation of general
operating conditions for cupolas describing capacities, physical
characteristics and air/fuel requirements for all common cupola sizes.

Grey iron cupolas emit dust, fumes, smoke, gases (including about one
pound of SO,., per ton of metal melted), and oil vapors.  Combustion-
related contaminants and dust are picked up by the high velocity air
stream forced through the charge.  Considerable testing has been done
by the Los Angeles County Air Pollution Control District for dust and
fumes from cupolas.  Table 7.9.2 shows the results of some of these
tests.  Oil mist and smoke in cupola exhaust gases are due largely
to oil and grease contamination of the scrap metal charged to the
furnace.  Large volumes of CO are formed from the combustion of the
coke.  A typical analyses of exhaust gases    is CO -12.2%, CO-11.2%,
02-0.4% and N2-76.2%.

-------
         Table 7.9.1.  GENERAL RECOMMENDATIONS  FOR OPERATING WHITING  CUPOLAS
                         (SOURCE:   BUREAU  OF MINES, Reference 2)
                 (Practical Hints on Cupola Operation, No. 237-R, Whiting Corporation, Harvey, Illinois)
Cupola
llli*
0
2
Z-J/2
3
3-1/2
1
5
6
S



10

12
Shell
in.
Z7
?2
36
41
46
SI
56
63
66
76

*



108
Min.
thickness
of Ipwer
hrnr.K, in
4-1/2
4-1/2
4-1 11
7
7
f
7
9
9
9

9



12
Dum.,,,
11 • a
lining, in.
IB
23
27
27
32
37
42
45
48
60

6



84
Area
linlne. ,,,.'
2M
415
572
572
904
J.075
1, 385
1, 590
1. 809
2,827

'
A 77B !
4.778

4778
,:„
Me
6
3/4
1-3/4
1-3/4
3-J/4
4
4-1/2
5-1/2
9






Minn rat
with irn
S
1
1-1/2
2-1/1
2-1/4
4-1/4
5-1/2
6-1/4
7-1/4
1 -1/4


6 /


22-1/4
«•. tons/
10


5-1/4
7
8
9
U


2, I/,



hr.
12



10-3/4
17






B«d coke
height
9




Blono, Ib
4
7
9
9
13
17
22
26
29
4*





89
Air
through
cfm
570
940
1, 290
1.290
1, BIO
2. 420
3, 100
3,600
4, 100
6, 400


'


I2.5CO
Suggfs
sc)
cfm
640
1. 040
1. 430
1, 430
2. 000
2. 700
3.450
4.000
4, 500
1, 100

'
'


13,900
ed blower
ctionc
Discharge
g
16
16
id
16
16 to 20
20 to Z4
20 to 24
Z4 to 29
24 to 32




•
32 lo 40
bHe:gnt of bei

-------
  Table 7.9.2.  DUST AND  FUME EMISSIONS FROM GRAY IRON CUPOLAS  (SOURCE:
                COUNTY AIR POLLUTION CONTROL DISTRICT, Reference 1)
LOS ANGELES
Test No.
Cupola data
Inside diameter, in.
Tuyere air, scfm
Iron - coke ratio
Process wt, Ib/hr
Stack gas data
V o 1 um e , s c f m
Temperature, °F
co2, %
02, %
CO. %
N2, %
Dust and fume data
Type of control
equipment
Concentration, gr/scf
Inlet
Outlet
Dust emission, Ib/hr
Inlet
Outlet
Control efficiency, %
Particle size, wt %
0 to 5 ji
5 to 10 ji
10 to 20 n
20 to 44 j±
> 44 H
Specific gravity
i

60
-
7/1
8, ZOO

8, 300
1, 035
-
-
-
-

None


-
0. 913

_
65-
-

18. 1
6. 8
12.8
32. 9
29. 3
3. 34
i

37
1, 950
6. 66/1
8, 380

5, 520
1, 400
12. 3
-
-
-

None


-
1. 32

-
62.4
-

17. 2
8. 5
10. 1
17. 3
46. 9
2.78
3

63
7, 500
10. 1/1
39, 100

30, 500
213
2.8
-
_
-

None


-
0.413

_
108
-

23.6
4.5
4.8
9. 5
57.9

4

56
-
6. 5/1
24, 650

17, 700
210
4. 7
12. 7
0
67. 5

Baghouse


1. 33
0. 051

197
7. 7
96

25.8
6. 3
2. 2
10. Oa
55. 7b

5

42
-
9. 2/1
14, 000

20, 300
430
5.2
11.8
0. 1
67. 3

Elec precip
aft erburner

2.973
0. 0359

184. 7
6. 24
96.6

-
-
-
_
-

6

60
-
9.6/1
36, 900

21, 000
222
-
-
_
-

Baghous e


0. 392
0. 0456

70. 6
8.2
88.4

-
_
_
_
_

7

48
-
7. 4/1
16, 800

8,430
482
-
-
_
-

Elec Precip


1. 522
0. 186

110
13. 2
87. 7

-
_
^
_
_

 From 20 to 50 (i.
^Greater than 50 (i.

-------
                              7.9.6
    The requirements  for  controlling  the  emission of  air contaminants
    from cupolas  vary with  different  agencies.   The criteria for control
    may be emission opacity or  dust and fume  discharge (process weight,
    see Chapter 3).   Water  type collectors  can  be used if it is necessary
    to remove large particles of dust but effective dust and fume
    collection requires baghouses or  electrical precipitators including
    CO afterburners and gas coolers.   Table 7.9.3 describes  pilot test
    results of various air  pollution  control  devices  used on cupolas.

2.   Inspection Points
    Cupolas operating without air pollution control systems  emit dense
    grey brown smoke  and  fumes  when the blast air is  in use.   Furnaces
    with air pollution control  systems should be inspected during the
    start up, melting and pouring phases  of operation.   An observation
    should also be  made of  the  bottom dropping  operation to  make certain
    that time and opacity limits are  not  exceeded.

    In systems using  a baghouse it is essential that  an adequately
    designed afterburner  be in  operation  during melting to reduce the CO
    content of the  gas in order to minimize the explosion hazard and to
    burn oil mists  and vapors.   Any system  designed to handle cupola gases
    must be sized to  provide good indraft at  the charging opening.   Puffing
    can occur frequently  and the use  of charging port doors  plus a high
    indraft will  minimize losses from this  area.   Observation of the
    effluent from the control equipment can provide qualitative readings
    of the efficiency of  collection.   Stack tests are required to determine
    if the grain  loading  of the exhaust gases meets compliance standards.

-------
                                       7.9.7
Table 7.9.3.   SOME COLLECTION  EFFICIENCIES  OF EXPERIMENTAL  SMALL-SCALE CONTROL
                 DEVICES TESTED ON GRAY  IRON CUPOLASa  (SOURCE:   LOS  ANGELES
                 COUNTY AIR  POLLUTION CONTROL  DISTRICT,  Reference  1)
Equipment tested
Controls for cupolas0
High -efficiency cyclone
Dynamic water scrubber
Venturi-type scrubber
Dynamic --impingement
wet scrubber
Baghoust — one sihcone-
JO in. dia x 10 ft length
Evaporative cooler and
redwood pipe electrical
precipitator
Other basic equipment
Natural gas-fired

Inlet
gas
volume,
scfm

330
1, 410
375
605
52.7
1. 160

"
Outlet
volume,
scfm

384
1,760
432
995
52.7
1, 330

5, 160
Inlet
dust
load.
gr/scf

1.225
1.06
1. 17
0.°5
1. 32
1.263

"
Outlet
dust
load,
gr/scl

0.826
0. 522
0.291
0. 141
0. 046
0. 0289

0.00288
Collection
effic lency,
To

22. 5
38. 2
71.3
75.6
96. 5
97.7

96. 2C
Rema'rks


cooling totalled 6 gpm
Two gpm-water introduced for cooling
gas stream; 3. 5 gpm added at venturi
throat; cyclonic scrubber operated dry
Water rate in excess of 10 gpm
Average temp, 372T; average filter-
ing velocity, 3.22gpm
precipitator, 2 gpm

Melting rate. 546 Ib/hr, gas consump-
tion rale, 4,200 cfh; melting clean
scrap and pig iron
aln all cases, equipment was installed and operated according
 The six control devices were tested on the same cupola.
cThis is not an actual collection efficiency, but a percent redu
                                                to the manufacturer's recommendations.

                                                ction when compared with average cupola emissions.

-------
                                   7.9.8
C.  NON-FERROUS FOUNDRIES
    Foundries form a part of nearly all industrial complexes and are found in
    all parts of the country.   These consist of small single crucible furnace
    shops or large production die casting shops employing many banks of
    melting furnaces.  The number and types of core making equipment,
    mechanical sand mullers, sand handling, grinding, buffing and plating
    equipment will depend upon the size of the operation and the end-use of
    the product.  For example, foundries producing plumbing fixtures may have
    chrome plating facilities.

    Since the range of practices, equipment and alloys is extensive non-
    ferrous foundries will be treated as an entity describing operations
    and equipment, alloys melted, potential emissions, air pollution control
    systems and inspection practices.  Non-ferrous foundries can be classified
    according to the metals melted:   copper-base alloys (brass and bronze),
    aluminum, or zinc.

    1.  Process Description—Copper-Ease Alloys
        Brass and bronze are the common names for a group of copper base
        alloys composed of 60 to 90 percent copper,  zinc, lead, tin and fractional
        percentages of other metals.  Brasses usually contain 60-65 percent
        copper; bronzes usually contain 85-90 percent.  Particulate emissions
        from melting operations originate from condensed metallic fume; par-
        ticulates from fuel-fired furnaces originate from the products of
        combustion (see Fuel-Burning Equipment, Chapter 6, Section II).

        Table 7.9.4 illustrates uncontrolled emission rates from a variety of
        furnaces melting copper base alloys with zinc content ranging from 5
        to 38 percent.  Since high copper alloys (80 to 90 percent copper)
        have a fairly high boiling point the fuming rate will be low; however,
        when the zinc content increases, as in alloys with 20 to 40 percent

-------
Table 7.9.4.  DUST AND FUME DISCHARGE FROM BRASS FURNACES (SOURCE:
              COUNTY AIR POLLUTION CONTROL DISTRICT, Reference 1)
LOS ANGELES
Type of
1 ur na c c
R ota ry
Rotary
Rotary
Elcc ind
Elcc ind
Elec ind
Cyl reverb
Cyl reverb
Cyl reverb
Cyl reverb
Crucible
Crucible
Crucible
Composition of alloy, %
Cu
85
76
85
60
71
71
87
77
80
80
65
60
77
Zn
5
14. 7
5
38
28
28
4
-
-
2
35
37
12
Pb
5
4. 7
5
2
-
-
0
18
13
10
-
1. 5
6
Sn
5
3. 4
5
-
1
1
8. 4
5
7
8
-
0. 5
3
Other
-
0. 67 Fe
-
-
-
-
0. 6
-
-
-
-
1
2
Type of
control
None
None
Slag cover
None
None
None
None
None
Slag cover
None
None
None
Slag cover
Fuel
Oil
Oil
Oil
Elect
Elect
Elect
Oil
Oil
Oil
Oil
Gas
Gas
Gas
Pouring
temp, °F
No data
No data
No data
No data
No data
No data
No data
2, 100
2, 100
1, 900 to 2, 100
2, 100
1, 800
No data
Process wt ,
Ib/hr
1, 104
3, 607
1, 165
1, 530
1, 600
1, 500
273
1, 267
1, 500
1, 250
470
108
500

Ib/hr
22. 5
25
2.73
3. 47
0. 77
0. 54
2. 42
26. 1
22.2
10. 9
8. 67
0. 05
0. 822

-------
                           7.9.10
zinc, the boiling point will drop considerably and increased fuming
will result.  Pure zinc boils at 1663°F with the usual pouring
temperature of high zinc alloys between 1900°F and 2100°F which would
allow some zinc to form zinc oxide as it flashes from the furnace and
is released as dense white emissions.  Emissions from the melting of
                                                               (2)
high lead alloys will contain as much as 56 percent lead oxide.

Furnaces used in brass foundries are either direct fired types which
include pit and tilting crucible furnaces and cylindrical reverberatory
furnaces, or indirectly heated electric induction furnaces.   Of the two
types the indirectly heated furnaces will produce smaller amounts of
emissions per pound of metal melted than direct fired furnaces.

In pit type furnaces, the crucible is made of silicon carbide or other
refractory material, and is indirectly heated in a ceramic-lined pit
by either natural gas or oil.  The cycle consists of melting the charge
and flux (see Table 7.9.5), removing the crucible from the pit and
pouring the metal into the molds.  As in most brass melting operations
the emissions will be mostly zinc oxide or lead oxide.  Where the
alloy melted has a high copper content, 85 percent to 90 percent,
emissions can be curtailed and brought within the limits of most
opacity and process weight regulations by the use of a proper slag
cover, usually molten glass, which is punctured only during pouring.
A. slag thickness of 1/4" to 3/8" is recommended.  Considerable fuming
occurs when the molten metal is poured.  When yellow brass is melted
(alloys with less than 80 percent copper) an air pollution control
system should be required to capture the fumes emitted during melting
and pouring.

Tilt type crucible furnaces do not vary significantly in operation
from pit type furnaces.  The tilting furnace is usually larger in
capacity, is located above floor level and is fired with either gas
or oil (see Figure 7.9.2).

-------
                                7.9.11
Table  7.9.5.   RELATIVE  VOLATILITIES AND MELTING  TEMPERATURES
                  FOR NON-FERROUS METALS  (SOURCE:   LOS ANGELES  COUNTY
                  AIR POLLUTION CONTROL DISTRICT,  Reference  3)
METALS
Zinc Alloys
Lead Alloys
Magnesium
Alloys
Aluminum
Alloys
Copper Alloys
(Manganese
bronze)
APPROXIMATE
MELTING TEMPS.
650°— 700'F
600'— 650°F
800°— 900 'F
1250°— 1280"F
Around 1800°F
1650°— 2000°F
RELATIVE
VOLATILITY
1
2
3
4
5
FLUXES
USED
Ammonium
chloride
Sodium Nitrate
Sal amoniac
Lump sulphur
Dow#l and #2
Flowers of
sulphur
Chlorine gas
Aluminum
chloride
Zinc chloride
Aluminum
fluoride
Silica sand
blown with air
Soda ash
Borax
          In brass and bronze melting operations  (copper alloys),
          zinc is the first base-metal to fume because of its low melth.g
          temperatures in relation to copper. Copper alloys containing
          more than 5% zinc are likely to fume without proper con-
          trols. In particular, the following metals must be carefully
          controlled: Yellow Brass, 20% or more zinc; Manganese
          Bronze, up to 45% zinc; Brazing  Spelter, 40% zinc; Plumb-
          ing  Metals, 12%  zinc. Copper alloys of less than 5% zinc
          content, such  as Red  Brass, are not likely to fume and may
          not require controls.

-------
                     7.9.12
Figure 7.9.2.   TILTING CRUCIBLE FURNACE,  LINDBERG ENGINEERING
               CO.,  DOWNEY,  CALIF.  (SOURCE:   LOS ANGELES
               COUNTY AIR POLLUTION CONTROL  DISTRICT,  Reference 1)

-------
                           7.9.13
Induction furnaces offer by far the most rapid method of melting
metal in common use by foundries.  Temperature control can be
carefully maintained, which is a prime factor in zinc oxide and lead
oxide emissions resulting from the melting of copper base allovs.
In the operation of induction furnaces, granulated charcoal has been
found to be superior as a flux to glass and borax which are destructive
to the furnace walls.  Charging fluxes into a hot furnace and metal
pouring remain the critical periods in the overall operating cycle in
the emissions of dusts and fumes.

Cylindrical rotary furnaces present the greatest potential air
pollution problem of the group of furnaces commonly used in brass
foundries.  These are reverberatory furnaces in which the flame from
the burners impinge on the surface of the metal.  There are several
variations of this type of furnace but the operating procedures are
virtually the same (see Figure 7.9.3).  The furnace rotates on its
horizontal axis and tilts for pouring and charging (Figure 7.9.4).  Due
to the shape of the furnace and the large volume of gas exhausted from
the products of combustion, the velocity of the gases leaving the
furnace is very high.  Therefore, tight hooding and high inlet
velocities at the hoods are required to assure acceptable fume capture.

Since the products of combustion come into contact with the metal in a
cylindrical reverberatory furnace it is desirable to have a slightly
oxidizing atmosphere to avoid smoke from combustion when oil is fired
and to prevent gas entrapment in the metal resulting from unburned
fuel and water vapor.  While this is an operational problem, improper
combustion could cause smoke and fume generation which can be avoided
by good operating practice.

-------
Figure
7.9.3.  ROTARY-TILTING-TYPE REVERBERATORY FURNACE VENTING TO CANOPY HOOD AND STACK VENT.
        (Top) Furnace during meltdown, (Bottom) furnace during pour, VALLEY BRASS, INC.
        EL MONTE, CALIF.  (SOURCE: LOS ANGELES COUNTY AIR POLLUTION CONTROL DISTRICT,
        Reference 1)

-------
                               7.9.15
                                          TO BAGHOUSE
                         FURNACE
            BURNER
                                               REFRACTORY
Figure 7.9.4.
ROTARY-TILTING-TYPE BRASS-MELTING FURNACE  (SOURCE:  LOS ANGELES
COUNTY AIR POLLUTION CONTROL DISTRICT, Reference 1)

-------
                           7.9.16
The operation of these furnaces varies in melting time, method of
heating, and in the physical shape of the equipment.  There is strong
similarity, however, in the air pollution potential from the common
phases of the operating cycle:  charging, working and pouring.
Observations of these critical periods is mandatory in determining
compliance with ordinances governing non-ferrous foundry operations.

Inspection Points—Copper-Base Alloys
Foundries are usually a part of an integrated manufacturing facility
which includes machine shops, plating facilities, packaging and
shipping departments.  It is reasonable to assume, therefore, that
metal charged to the furnace for melting will be made up of scrap
parts, gates and risers, turnings and borings, as well as ingot metal.

a.  CHARGING—the condition of the metal charged should be closely
    inspected to determine if there is grease or oil present.  Usually,
    in foundry practice, the charge will consist of rejected parts,
    gates and risers, and ingot; however occasionally some other scrap
    of known analysis can be used as an economy measure.  Dirty and
    oily material can add combustion-related contaminants to the
    effluent such as smoke and particulates.  Charging metals into
    the furnace after the heel has formed, will break the slag cover
    and allow significant quantities of fume to escape.  The inspector
    should time this operation for opacity violations in uncontrolled
    operations and check the hood pickup efficiency in controlled
    operations.  Maintaining the integrity of the slag cover is essen-
    tial to good operating conditions in melting brass and bronze.  Any
    action which breaks the cover will allow the escape of dense
    emissions of metallic oxides.

-------
                           7.9.17
b.  MELTING—prior to charging the metal the flux material (crushed
    glass, borax and, in induction furnaces, granulated charcoal) is
    placed in the furnace so that as melting occurs the slag will form
    over the metal to inhibit contact or mixing with air.  The slag
    must be skimmed to remove trapped materials whenever additional
    flux or metal is to be added to the furnace.  This results in
    heavy emissions.  Properly designed air pollution control systems,
    with high indraft velocities at the hoods are required to capture
    these emissions.  Time and opacity, and process weight regulations
    are frequently violated in this phase of the operation.

c.  POURING—temperatures of the metal during pouring are important
    for the type of casting produced and are therefore carefully
    controlled.  The pouring temperature is also very important from
    an air pollution control standpoint since the higher the
    temperature of the alloy the more volatilization will occur.  For
    a given percentage of zinc an increase of 100°F increases the
    rate of loss of zinc about three times.

    As has been mentioned, breaking the slag cover for whatever reason
    causes heavy fuming to occur.  When pouring from a crucible or ladle
    it is necessary to punch two holes in the slag cover; one to allow
    air in and the other to pour.  All transfer operations will cause
    fuming by exposing the molten metal to air and allowing oxides to
    form.  In order to comply with process weight and opacity
    regulations some foundries that melt yellow brass have found it
    necessary to mechanize the pouring operation so that the molds
    pass under a hood and the ladle is stationary.  Various systems
    are in use, some employing hoods with flexible ducting to
    capture the fume produced during pouring.

-------
                        7.9.18
The Air Pollution Engineering Manual sets forth the factors

which cause extensive emissions of zinc fumes, and which form the

basis for understanding the operational causes of these emissions.
     1.  Alloy composition.  The rate of loss of zinc is
         approximately proportional to the zinc percentage
         in the alloy.

     2.  Pouring temperature.  For a given percentage of
         zinc, an increase of 100°F increases the rate of-
         loss of zinc about three times.

     3.  Type of furnace.  Direct-fired furnaces produce
         larger fume concentrations than the crucible type
         does, other conditions being constant.  The Los
         Angeles Nonferrous Foundrymen's Committee, stated,
         "It is improbable that any open-flame furnace melting
         alloys containing zinc and lead can be operated
         without creating excessive emissions.  It is conceded
         that anyone choosing to operate that type of furnace
         will be required to install control equipment."

     A.  Poor foundry practice.  Excessive emissions result
         from improper combustion, overheating of the charge,
         addition of zinc at maximum furnace temperature,
         flame impingement upon the metal charged, heating the
         metal charged, heating the metal too fast, and in-
         sufficient flux cover.  Excessive superheating of the
         molten metal is to be avoided for metallurgical and
         economic as well as pollution control reasons.  From
         an air pollution viewpoint, the early addition of
         zinc is preferable to gross additions at maximum
         furnace temperatures."
The most effective air pollution control equipment for brass

foundry melting and pouring operations are baghouses and

electrical precipitators.   Of equal importance is the collection

system which includes hoods, ductwork, gas temperature reduction
mechanisms and fans.

-------
                               7.9.19
        The design of fume pickup systems presents difficult air pollution
        control problems especially when high temperature gas is to be
        captured from a source where access by workmen is required and
        where the source may not be stationary as in operations where
        metal is poured from movable ladles.  Generally if these systems
        have been installed, prior approval from the air pollution control
        agency is needed to assure that the design characteristics have
        been thoroughly evaluated and necessary tests have been
        conducted.  The inspector must check these systems to determine
        that the operating effectiveness has not deteriorated due to poor
        maintenance or improper use; or, if prior approval was not obtained,
        to determine if the system has been properly designed for the job.

3.  Process Description—Aluminum Melting
    Aluminum foundries that melt ingots, rejects, gates and risers in
    crucible or induction furnaces are not major sources of air pollution
    if fluxes are not used for cleaning, alloying, degassing or removal
    of magnesium  (demagging).  The furnaces used in aluminum foundries are
    of the pit crucible, tilt or induction type.  Since indirect heating
    is used there is no problem from mixing the products of combustion
    with the molten aluminum.

    A flux cover can be used to prevent oxidation on the surface of the
    metal.  The flux usually consists of mixtures of sodium chloride,
    calcium chloride, calcium fluoride and borax.

    Aluminum castings are made in either sand molds or in die casting
    machines.  There is a certain amount of off-gassing from sand casting
    which is related to the type of cores used and the moisture content
    of the foundry sand.  (See Coremaking, this Section.)  Die casting
    should not be a problem if a mold release compound containing no oil
    is used.

-------
                            7.9.20


The major air pollution control problems from melting aluminum
arises from secondary smelting and refining which is discussed in
Section XIII of this chapter.

A typical melting cycle consists of charging the metal into the
furnace after a heel has formed, fluxing and pouring.  The average
fluxing temperature is 1250°F to 1280°F.  In small crucibles the
metal is poured directly from the crucible into the mold.  In the
larger tilt type furnaces the molten aluminum is poured into ladles
and transferred to the sand casting area of the plant for pouring
into sand molds or into smaller hand held ladles for pouring into
die casting machines.

Process Description—Zinc Melting
Foundries melting zinc alloys in pit crucibles, tilt crucible, pot
furnaces, or induction furnaces usually do not use fluxes.  The metal
is melted and heated to the desired pouring temperatures which may
range from 800°F to 1100°F.  At these temperatures little vaporiza-
tion and virtually no visible emissions occur.   Zinc vaporizes at
1665°F.  The necessity to heat zinc to temperatures approaching
this figure in non-ferrous foundries does not occur.

Many zinc foundries use die casting machines which require a mold
release compound.  If a non-oily compound is used there should be no
smoking or oil mist generated from the molds after pouring.

In the zinc melting operating cycle it is not necessary to form a
heel before charging except in induction furnaces.  Usually ingot and
rejects are charged before scrap and thin-walled sections to prevent
burning.  If the metal charged is dirty, dross will form on the

-------
                                7.9.21
    surface of the molten metal which must occasionally be skimmed.
    Flux may be added to help float any submerged dross to the surface.
    Dross is the common name applied to a mixture of oxide and impurities
    which form when the white metals are melted.

    If a zinc melting furnace is creating visible emissions the most
    likely causes are:  the vaporization of oil,  grease or paint from the
    metal charged; unusually high temperatures which cause the zinc  to
    flash to zinc oxide; or the use of a boiling  flux which is intended
    for melts containing less ingot in relation to scrap metal.

    These operations do not require air pollution control systems and can
    meet most opacity and process weight regulations if they are
    controlled under the conditions described above.

5.  Inspection Points—Aluminum and Zinc
    In both aluminum and zinc melting operations  it is necessary for the
    inspector to observe a complete cycle from charge to pour to become
    completely familiar with the operating procedures of the firm.   The
    critical phases of operation common to both are metal charging to
    determine if oily material is used, fluxing and dross removal.   The
    pouring of zinc into ladles or molds can also be critical if the
    temperature greatly exceeds 1100°F.

6.  Process Description—Core Making
    Core making is an integral part of foundry operations and is a
    potential source of air pollution under certain operating conditions.
    It is generally difficult to record opacity violations from core
    ovens.  The equipment can be a source of public nuisance, however.

-------
                           7.9.22
Cores are used to allow molten metal to flow around a given space to
form the desired cavity in a casting.  The core therefore must be non-
reactive, firm and easily removed after the metal has solidified.  Sand
is mixed with binders which when heated will provide the strength that
the core requires to keep it firm while the mold is being prepared and
to resist skrinking or warping when the metal is poured into the mold.
The binders when heated either change chemically, physically or both
and can emit volatiles such as aldehydes and solvent vapors.

Typical binder mixtures contain linseed oil, gum resin, cereal binder,
kerosene, and water which are proportioned according to the quantity
of sand used.  As heat is applied in the core oven the light oil
fractions distill off first.  As the temperature continues to
increase the heavier fractions are vaporized and polymerization of
the linseed oil occurs.  As the temperature in the oven continues to
rise towards its maximum of 400°F the rosin melts, coating the sand
grains with a thin film.  The remaining curing time is necessary to
reach maximum strength of the core.

A variety of ovens are used to bake cores, both gas and oil fired,
batch and continuous.  Figures 7.9.5 through 7.9.8 illustrate the
types and size of ovens that can be found in foundries.  The
operating cycle is dependent upon the type of binder used and ranges
from 1 to 4 hours.

Emissions from core baking are organic acids, aldehydes and smoke.
Examples of quantitative emissions are shown in Table 7.9.6.

-------
                              7.9.23

i
1
1
1
1
1
1
1
1
1
' ' ' '
;;;;;;'!
	
,,,,,, ,
	 '
'^r!n
	 	
'• ', ! ' "
— ., 1
• • • ' i '
	 ;
Figure 7.9.5.  SHELF OVEN, THE FOUNDRY EQUIPMENT CO.,  CLEVELAND,
               OHIO (SOURCE:  LOS ANGELES COUNTY AIR POLLUTION
               CONTROL DISTRICT, Reference 1)

-------
                             7.9.24
Figure 7.9.6.   DRAWER OVEN,  DESPATCH OVEN CO..  MINNEAPOLIS,  MINN.  (SOURCE:
               LOS ANGELES COUNTY AIR POLLUTION CONTROL DISTRICT,  Reference 1)
Figure 7.9.7.  RACK OVEN, DESPATCH OVEN CO.. MINNEAPOLIS. MINN. (SOURCE:
               LOS ANGELES COUNTY AIR POLLUTION CONTROL DISTRICT, Reference 1)

-------
                          7.9.25
Figure 7.9.8.  HORIZONTAL, CONTINUOUS OVEN, THE FOUNDRY EQUIPMENT
               CO., CLEVELAND, OHIO (SOURCE:  LOS ANGELES COUNTY
               AIR POLLUTION CONTROL DISTRICT, Reference 1)

-------
Table 7.9.6.  AIR CONTAMINANT EMISSIONS FROM CORE OVENS (SOURCE:  LOS ANGELES
              COUNTY AIR POLLUTION CONTROL DISTRICT, Reference 1)
Test No.
Oven data
Size

Type
Operating temp, °F
Core binders
Weight of cores baked, Ib
Baking time, hr
Afterburner data
Size

Type
Burner capacity, Btu/hr
Air contaminants from:
Effluent gas volume, scfm
Effluent gas temperature, °F
Particulate matter, Ib/hr
Organic acids, Ib/hr
Aldehydes, ppm
Hydrocarbons, ppm
Opacity, %
Odor
1
6 ft 2 in. W x 7 ft 11 in.
H x 1 9 f t L
Direct gas-fired
380
1 to 1/2% phenolic resin
700
11



None

Oven
100
380
0. 13
0.068
52
124
0
Slight
2
3 ft 10 in. W x 5 ft 3
in H x 18 ft L
Direct gas-fired
400
3% linseed oil
1,600
2-1/2 to 3

10 in. dia x 7 ft 6
in. H
Direct flame
200, 000
Oven
140
400
0.2
0. 008
10
-
-
-
Afterburner
260
1, 400
0.013
0.000
10
< 10
0
Slight
3
4 ft 2 in. W x 6 ft 8
in. H x 5 ft 9 in. L
Indirect electric
400
1% linseed oil
600
6

3 ft dia x 4 ft H

Direct flame
600, 000
Oven
250
400
0. 27
0. 44
377
158
-
-
Afterburner
440
1, 780
0. 02
0. 087
4
< 19
0
None
                                                                                            VO

                                                                                            N3

-------
                               7.9.27
    Ovens which operate at 400°F or less on a batch basis can usually
    meet most air pollution control regulations and should not cause a
    public nuisance.   Excessive emissions are likely to occur when large
    quantities of cores are baked or continuous operations are employed
    and curing temperatures exceed 450°F to 475°F.

    The most effective air pollution control system to reduce these
    emissions is an afterburner or vapor incinerator.   A combustion zone
    temperature of 1200°F, good mixing and at least 0.3 second retention
    time are minimums for good control.

7.   Inspection Points—Core Making
    The inspector should observe at least the last  hour of the core baking
    operation to determine if odors can be detected from the oven vent or
    an opacity violation occurs.  If the agency has specific rules
    governing the emission of organic gases and vapor  it may be necessary
    to request a stack test to make a quantitative  and qualitative
    determination of the emissions.  In either case, he should learn the
    trade name or specification of the binder used, the maximum oven
    temperature, cure time and time of day the equipment is operated.

8.   Process Description—Sand Handling
    Foundry sand handling systems are usually mechanized in production
    shops but are fundamentally the same regardless of the size of the
    foundry.  Molds are shaken to loosen the sand from the casting in the
    shakeout pit.  The sand, spent cores and small  particles of metal
    fall onto a screen which passes the proper particle size sand and
    segregates the oversized material.  A minimum reconditioning system
    includes a crusher, conveyor and muller in which the sand is mixed
    with clay and water to bring it to the proper condition to be reused

-------
                            7.9.28
in molds.  The sand at shakeout is hot and must be cooled prior to
reconditioning.  This can be accomplished by ambient air or in large
volume operations where there is a high metal-to-sand ratio in the
mold, and by mechanical air blowing equipment.  Figure 7.9.9 shows a
complete sand handling and dust control system.

In addition to dust there are some smoke and organic vapor emissions
from this phase of foundry operations.  After the pour into the mold
is complete some of the core binder material will break down creating
smoke and vapors.  This will continue to some degree during shakeout.
Ventilation systems designed to capture fines and smoke are usually a
part of the integrated system.  If a baghouse is used as control
equipment and is properly sized and maintained, emissions to the
atmosphere can be held within most emission limitations.  Scrubbers
will reduce the dust emissions but have not proven effective for
eliminating smoke.

Inspection Points—Sand Handling
A survey should be made of the sand handling and conditioning system
to determine if excessive dust and smoke are emitted.  If there is a
dust collection system the inspector must check all tranfer points,
the boot and discharge of the bucket elevator, and vibrating screens.
Hoods should have adequate indraft velocity to capture the dust
generated by the material handling equipment and air blowing, if used.
In foundries not using dust control systems, a qualitative estimate of
dust losses should be made to determine if a dust control system is
required.  Smoking molds and sand could be a cause for complaints and
may violate opacity regulations.

-------
TO BAGHOUSE
                                                                                               VO

                                                                                               Isi
      Figure 7.9.9.
TYPICAL FOUNDRY SAND-HANDLING  SYSTEM (SOURCE:  LOS ANGELES
COUNTY AIR POLLUTION CONTROL DISTRICT,  Reference 1)

-------
                                7.9.30
10.  Environmental Observations
     Emissions of aldehydes and other organic material from foundries are
     sometimes a source of  nuisance complaints and can be traced to the
     foundry core making operation or to  the vaporization of the binder
     materials after metal  has  been poured  into the mold.   These organic
     materials can cause eye, nose,  and throat irritation.   Visible
     emissions from metal melting  can be  easily observed  from outside of
     the plant and related  to a particular  phase of the operation after
     the inspector has  observed the complete melting cycle.

     Dust and fines from sand handling, storage piles and  unpaved areas
     in a foundry are also  prime causes of  complaints.  A  survey of
     nearby residents or business  establishments can usually result in
     isolating the offending company.

-------
                                    7.9.31
                                  REFERENCES

1.   Hammond,  W.,  and V.  Nance.   Metallurgical Equipment Iron  Castings.
    In:   Air  Pollution Engineering Manual,  J.  A.  Danielson  (ed.).   Cincinnati,
    DHEW, PHS,  National Center for Air Pollution  Control and  the Los Angeles
    County Air  Pollution Control District.  PHS No.  999-AP-40.  1967.

2.   Allen, G. L.,  F. H.  Viets,  and L.  C.  McCabe.   Control of  Metallurgical  and
    Mineral Dust  and Fumes in Los Angeles County,  California.   Bureau  of Mines.
    Information Circular 7627.   1952.

3.   Weisburd, M.  I.  Air Pollution Control Field  Operations Manual.  DHEW,
    PHS, DAP.  Washington, D. C., 1962.

4.   Handbook  of Cupola Operations.  American  Foundryman's Association,  1949.

-------
                                    7.10.1
                               X.  CEMENT PLANTS

A.  DESCRIPTION OF SOURCE
    Portland cement takes its name from a fine building stone it resembles
    when made into concrete, which is quarried on the isle of Portland, England.
    Portland cement is manufactured in 180 plants in the United States.  The
    raw materials—limestone, cement rock, clay and iron ore—are either
    blended dry or mixed with water to form a slurry and then burned into
    cement clinkers.  These two processes account for all of the 500,000,000
    barrels of Portland cement produced in the United States.

    Due to the increasing use of Portland cement, the anticipated annual growth
    rate of this industry is 5% per year with a trend toward larger plants

    Cement plants are located throughout the United States with the greatest
    production occuring in eastern Pennsylvania; Maryland; Alabama; Missouri;
                                                        (2)
    Central Texas; California and the Pacific Northwest.
B.  PROCESS DESCRIPTION
    The process begins with quarrying of the raw materials, transporting by
    truck, rail, or barge to primary crushers for initial size reduction, and
    transporting by conveyor to secondary crushers for further size reduction
    and storage (Figure 7.10.1).  In the wet process the raw materials are
    proportioned according to the desired cement specification, and mechanically
    conveyed to a grinding mill where water is added.  The resulting slurry is
    pumped to a vibrating screen which passes the wet mixture containing the
    specified size fines to the blending tanks and diverts the oversized
    material back to the grinder.  The slurry is mixed and blended and is then
    pumped into a final storage vessel before introduction into the kiln.

-------
                                            7.10.2A
        RAW MATERIALS CONSIST OF
        COMBINATIONS OF LIMESTONE,
        CEMENT ROCK, MARL OR OYSTER SHELLS,
        AND SHALE, CLAY, SAND, OR IRON ORE
                                         PRIMARY CRUSHER
                                                                                      EACH RAW MATERIAL
                                                                                      IS STORED SEPARATELY
                                                                  SECONDARY CRUSHER
                                                                                    RAW MATERIALS CONVEYED
                                                                                    TO GRINDING MILLS
           STONE IS FIRST REDUCED TO 5-IN. SIZE, THEN 3^-IN., AND STORED
                                                1
                                                                     DRY MIXING AND
                                                                     BLENDING SILOS
                                                                                      GROUND RAW
                                                                                      MATERIAL STORAGE
                 RAW MATERIALS ARE GROUND TO  POWDER AND BLENDED
RAW MATERIALS O
ARE PROPORTIONED
                             GRINDING MILL
                                               SLURRY    SLURRY IS MIXED AND BLENDED O   SLURRY  STORAGE BASINS
                                               PUMPS                              PUMP
RAW MATERIALS ARE  GROUND, MIXED WITH WATER TO FORM SLURRY, AND BLENDED
                                                 2
      Figure 7.10.1.   PROCESS  STEPS—PORTLAND  CEMENT  PRODUCTION

                           (SOURCE:  PORTLAND  CEMENT ASSOCIATION,  Reference  3)

-------
                                           7.10.2B
                                                                                MATERIALS ARE
                                                                              STORED SEPARATELY
                      RAW MIX IS KILN BURNED
                      TO PARTIAL FUSION AT 2700° F.
                                                           COAL, OIL, OR
                                                           GAS  FUEL

                                                               o
                                                                          CLINKER AND GYPSUM CONVEYED
                                                                          TO GRINDING MILLS


        BURNING CHANGES RAW  MIX CHEMICALLY INTO  CEMENT  CLINKER
                                                 3
                GRINDING MILL
                                       CEMENT
                                        PUMP
                                                    BULK STORAGE
 BULK   BULK   BOX   PACKAGING   TRUCK
TRUCK   CAR    CAR    MACHINE
CLINKER WITH GYPSUM ADDED IS GROUND  INTO PORTLAND CEMENT AND SHIPPED
           Figure 7.10.1.   PROCESS STEPS—PORTLAND  CEMENT  PRODUCTION (continued)

                             (SOURCE:   PORTLAND CEMENT ASSOCIATION,  Reference 3)

-------
                                    7.10.3
    In the dry process the proportioned raw materials are run through an air
    separator (where drying takes place by heated air from a furnace) which
    allows the proper size fines  to  be pneumatically pumped to the dry mixing
    and blending silos and recycles  the oversize material back to the grinder.
    The blended mix is then pneumatically conveyed to the ground raw material
    storage silos from which the  material is introduced into the kiln.  In
    both processes, the slurry or dry mix is fed into the elevated end of the
    kiln.   Firing takes place at  the opposite end of the kiln, giving a heat
    flow counter to the material  flow.   The fuel can be powdered coal, oil, or
    gas.   The raw mix is burned to partial fusion (to produce a cement clinker)
    at 2700 F, air cooled, proportioned with gypsum, ground in the same manner
    as the dry mix process and stored in bulk silos  for ultimate bagging or
    bulk shipment.

    The heart of the cement plant is the cylindrical rotary ceramic lined kiln
    which is also the largest single source of  dust  emission in the entire
    operation.  Kilns range in size  from 6 feet in diameter and 60 feet in
                                                         (2)
    length to 25 feet in diameter and 760 feet  in length.      The kilns revolve
    on huge roller bearings and slope from the  feed  end down to the discharge
    and firing end at the rate of from 1/2" to  3/4"  per lineal foot of kiln.

    Basic operations employed in  cement plants  are crushing and grinding,
    blending, materials handling, clinker production and cooling, and fuel
    preparation for coal fired plants.   Figure  7.10.1 depicts the sequence of
    operations and major differences between the wet and dry processes.

C.  EMISSIONS AND CONTROLS
    Every operation in the cement production process, by its nature, produces
    dust.   Dust fall measurements made in the Lehigh Valley in Pennsylvania,
    near plants using modern air  pollution control equipment have recorded a
    dustfall rate of 35 tons/sq.  mi./month.   This area has a high concentration
    of plants producing 31,000,000 bbl/year of  cement.   Even with collection

-------
                                7.10.4
efficiencies of 90%, as much as 10 tons/day of dust can become airborne
from a 4000 bbl/day plant attributed to the heavy grain loading of the
kiln gas.
Test data
         (4)
             of dust emissions from cement kilns are:
     •  Wet process - dust from kilns is 1 to 33% of finished cement
                      (4 to 124 Ibs/bbl).
                      Arithmetic average of dust loadings in exhaust gases is
                      10.1% of the finished product.
     •  Dry process - dust from kilns is 1 to 25% of finished cement
                      (4 to 94 Ibs/bbl).
                      Arithmetic average of dust loadings in exhaust gases is
                      11.3% of the finished product.
Technological changes for processing equipment will probably be concentrated
in recycling collected kiln dust which may affect firing rates and the shape
of the kiln.  Increased collection efficiency of air pollution control equip-
ment to 99.5% + is essential to reduce kiln dust emissions.  Figure 7.10.2
presents the representative dust loading of kiln gases from the wet and dry
                                      (2)
process in kiln dust in exhaust gases.
                     DUST LOADING CHARACTERISTICS
Kiln Type
Wet
Dry
Dust Loading
gr/ft3
1 to 13
10 to 13b
1 to 12
20 to 55b
        Before collection at stack conditions (400 to 600°F)
        New long kiln utilizing chains and/or lifters
   Figure 7.10.2.  EXAMPLE OF CHARACTERISTICS OF KILN DUST (SOURCE:
                   SUSSMAN, Reference 2)

-------
                                7.10.5
Most of the sulfur dioxide formed in cement kilns as a result of the
combustion of fuel is recovered as it combines with the alkalies.  Tests
of a coal fired kiln burning 2.8% sulfur coal showed a range of 6 to 39 ppm
SO ^.  There is no test data available on NOX production but its forma-
tion is a distinct possibility with kiln temperatures in excess of 2600°F.
Hydrogen sulfide and polysulfides may also be produced during drying of
slurry or in the dry process when marl, sea shells, shale or clay are the
materials processed.

Processing controls vary with  the age  and size of  the plant.  Kiln
temperatures, which have a bearing on  the firing rate and the raw mix feed
rate,  are indicated and usually recorded.  Combustion equipment  and con-
trols will also vary; however, plant operators may be able to provide
information even  though data recording equipment may not be available.

A variety of dust  control equipment is in use including bag type collectors,
electrical precipitators, and multiclones.  Generally electrical precipitators
are used to collect the dust entrained in the kiln effluent because of  the
high  temperature  of  the exhaust gas.   Baghouses using glass fabric bags
                                  (4)
have  shown efficiencies of 99.5%+    and should find increasing use in
this  industry.  Dusts resulting from storage  (silos are under positive
pressure due to air displacement  in loading or from pneumatic conveying),
grinding, cooling  and materials handling are usually controlled by bag
type  collectors or mechanical  collectors.

Figure 7.10.3 represents a flow diagram of a cement plant which  indicates
the points of dust emission.   The kiln which is the primary dust source
is usually vented  to an electrical precipitator or baghouse.  Screens,
mills, storage bins, and packaging facilities are  generally vented to
mechanical collectors and baghouses in series.  Transfer points, drop
points, elevator boots and loading stations should be hooded and materials

-------
                                     7.10.6
    collected.   Depending on cross drafts and physical shape, hood design inlet
    velocities  of 200 ft/min or more may be required.

    In coal fired plants, pulverizing systems are used to prepare the coal
    for burning in the kiln.  While the pulverizing system is "closed" and
    uses mechanical separators as part of the system, this ancillary process
    can also produce large quantities of dust.
                                                      © Dust collection points
            Figure 7.10.3.  FLOW DIAGRAM OF CEMENT PLANT OPERATIONS
                            (SOURCE:  SUSSMAN, Reference 2)

D.  INSPECTION POINTS
    The inspector should survey the plant to determine the adequacy of dust
    pickup at any location where dust is generated and, if necessary, request
    stack tests to determine the efficiency of the dust control equipment.
    The dust emission locations shown in Figure 7.10.3, except for the kiln,
    are at transfer points, size reduction equipment, classifying equipment
    (screens) and bulk loading facilities.  Dust pickup efficiency of the hoods

-------
                                7.10.7
serving these areas is indicative of air pollution control performance.
For example:

1.  Good dust pickup means the system is operating at or near its design
    efficiency.

2.  Poor dust pickup may mean plugged lines, air bleeding in through worn
    or damaged duct work, damaged fan, drive belt slippage or undersized
    motor.

Equipment and methods for field checking indraft velocities at hoods are
described in Chapter 5.
 The  unmistakable sign of a cement plant is the plume from the kiln  stack.
 Visible dust  can be seen in the carry-over after the steam has dissipated.
 By comparison with previous observations, when the control device is  known
 to have been  operating effectively, the inspector can make a qualitative
 judgment  as to  the efficiency of the control equipment.

 A check of the  control room may provide evidence of malfunction  of  the
 equipment if  there is a recording outlet opacity indicator instrument.
 The  inspector will find it extremely useful to make notes of the recording
 and  non-recording instrumentation which can include kiln temperature,
 fuel flow measurements and gas analyzers for combustion performance.

 Electrical precipitators, for example, are sensitive to the temperature and
 moisture  content of the inlet gases.  Resistivity  (resistance to relinquishing
 negative  charge to the collection electrode) for most particles  increases
 sharply when  the gases entering the precipitator are between 200° and 400°F

-------
                                7.10.8
and less than 5% moisture (see Figure 7,10.4 and Chapter 2).  Collection
efficiency is adversely affected by low resistivity.  The inspector thus should
become familiar with the gas conditioning requirements of the precipitator and
check the control instrumentation to see if the inlet conditions are in the
proper range.  The inspector should also check the rapping or washing cycle
for removal of dust collected on the electrodes.  Reentrainment of dust
can occur if this cleaning function is not precise.  Dust reentrainment
can result in an increase in opacity of the effluent and a rise in the
exhaust grain loading.

Baghouses using glass fabric filters are extremely efficient air pollution
control devices for cement kilns.  The major operational problem is to
maintain the temperature of the gases in the baghouse above their dew
point.  Insulation of the baghouse enclosure, fan, and ducts is helpful
in maintaining the proper temperature.  Good operational procedures also
require the exhaust fan to remain in operation during down time to prevent
moisture buildup in the bags.

Inspection fundamentals apply regarding observations of equipment repair,
non-use of dust collection equipment, and housekeeping.  These should apply
to roads and uncovered areas where dust has collected.  Since the material
is very fine, it can easily be disturbed by truck traffic and contribute to
the background count of particulates for the area, as well as creating a
public nuisance.

Dust collected from the kiln may be reinjected into the kiln, transported
dry by materials handling equipment to a waste disposal area where it is
dampened before it is dumped, or mixed with water to form a slurry and
pumped to a waste pond.

-------
                                    7.10.10
                                  REFERENCES

1.   Control Techniques  for  Particulate Air Pollutants.  Washington, D.C.,
    DHEW,  PHS,  NAPCA, January  1969.

2.   Sussman,  V.  H.   Nonmetallic Mineral  Products  Industries.  Air Pollution,
    Vol.  Ill, A.  C.  Stern (ed.).   New York City,  Academic Press, 1968.

3.   The Making of Portland  Cement.   Portland  Cement Association.  Skokie,
    Illinois.

4.   Kreichhelf,  T.  E.,  D. A. Kemnitz, and S.  T. Cuffe.  Atmospheric Emissions
    from the Manufacture of Portland Cement.   DHEW, PHS.  Cincinnati, Ohio.
    1967.

5.   Simon, H.  Single-stage Electrical Precipitators.   In:  Air Pollution
    Engineering Manual, J.  A.  Danielson  (ed.).  Cincinnati, DHEW, PHS,
    National Center for Air Pollution Control and the Los Angeles County Air
    Pollution Control District.  PHS No. 999-AP-40.   1967.

-------
                                    7.11.1
                       XI.  ALUMINUM REDUCTION PLANTS

A.  DESCRIPTION OF SOURCE
    Aluminum production consists of four major phases:  Mining of Bauxite ore;
    alumina production consisting of ore refining, extraction and calcination
    of alumina ore (Al.CL); smelting or reduction of alumina to produce aluminum
    ingot or billet; and fabrication:  processing of the ingot by casting, forging,
    extrusion, machining, rolling, drawing and other production techniques.

    Mining and refining of alumina is mostly conducted abroad.  Domestic refining
    is confined to Arkansas, Louisiana, Alabama and Texas and results in parti-
    culate pollution problems similar to the cement and lime processing industries,
    addressed in other sections of this Chapter.  Fabrication and recycling or
    reclamation of aluminum products falls under the category of secondary metals
    production, treated in Section VIII.  The aluminum smelting or reduction
    process is most significant from a domestic air pollution standpoint and
    will be treated in this section.

    Approximately 30 major aluminum reduction plants are operated in the
    United States.  These are generally located close to relatively cheap
    sources of electrical energy, particularly hydroelectric power.  Additional
    power may be supplied from oil or coal-fired power plants.  Principal
    plants are located in Alabama, Arkansas, Indiana, Kentucky, Louisiana,
    Maryland, Montana, New York, North Carolina, Oregon, Tennessee, Texas,
    Washington, West Virginia and Wisconsin.

    The basic process consists of the extraction of  (elemental) aluminum from
    the refined alumina ore.  Alumina is highly resistant to heat and chemicals
                                                                              C2 3)
    due to the strong bond holding the atoms of aluminum and oxygen together.v '
    Enormous amounts of electrical energy are required to separate these chemicals
    from each other.  For example, the six aluminum reduction plants located in
    the State of  V&shington annually consume 2,000,000 kilowatts of. electrical

-------
                                    7.11.2
    energy  (equivalent  to  the  entire  generating  capacity of  Grand Coulee Dam)
    to  produce  1,000,000 tons  of aluminum,  or  2  kilowatts for every ton of
    aluminum produced,     although  newer  plar
    consuming per  pound of  aluminum produced.
aluminum produced,     although newer plants are designed to be less power
B.  PROCESS DESCRIPTION
    From an air pollution standpoint the process of aluminum reduction can be
    seen in three phases:  (1)  handling of the alumina powders; (2) preparation
    of the carbon anode,  and (3)  aluminum reduction in pots or cells (see
    Figure 7.11.1).   Two  types  of aluminum reduction processes are employed:
    prebake and Soderberg.   These differ in the method of preparing the anodes
    required to effect electrolytic action in the pots.  Prebake refers to the
    formation, pressing and baking of the carbon blocks prior to their
    placement in the pots.   This  may be conducted in a separate plant—the
    anode plant—which is usually operated within the same facility, less
    commonly at a plant at a different location.  In the Soderberg process an
    anode paste mix of coke and pitch is added on top of the anode and is
    baked in place by the heat  of the pot.  The two processes, although they
    may be conducted at the same  facility, dictate different pot and plant
    designs.  These are discussed in greater detail in the following parts of
    this section.

    1.  Material Handling
        Material handling involves transfer of the alumina powder in bulk
        from ship or rail cars  to storage bins or silos located at the
        aluminum plant.  Transfer is accomplished by bucket and conveyor
        systems, or by the use  of vacuum lifters.  Storage and transfer
        systems are likely to be  enclosed, and in some plants exhaust systems
        and bag houses are applied to recover alumina losses.  The alumina is

-------
ANODE
PLANT
CATHODE
 PLANT
CELL  CHARGE
 MATERIALS
ELECTRIC
 POWER
                     RECEIVE
                     CATHODE
                     MATERIAL
                     & BUILD
                     CATHODE
                     POTROOMS
                ALUMINUM PRODUCTION
                  CELLS (POTS)
   Figure  7.11.1.
ALUMINUM REDUCTION PLANT FLOW  DIAGRAM
(SOURCE:   STATE  OF WASHINGTON, Reference  A.)

-------
                                7.11.4
    transferred  from the  inplant  storage  facility  to  silos  in the potroom
    area,  and hoppers are moved around  the plant by overhead cranes or
    ground dispensing vehicles  (see  Figure 7.11.2).   The dusts generated
    from the charging operation are  collected  by the  ventilation hoods
    located on the  pots or  by a system  covering the total building (called
    a secondary  control system),  although alumina  dust will usually be
    found  throughout the  potroom  floor  area.

    Alumina is a fairly dense particulate and  usually will  pass  through
    a 325  mesh screen.  Its white coloration makes leaks, emissions and
    spills easy  to  detect.  Since alumina is highly inert,  contamination
    resulting from  spillage and floor deposits generally is not  a problem
    and  the material can  be swept up and  fed to the reduction pots.

2.   Electrode Preparation
    a.   Cathode  Preparation
        The electrolytic  process  of  aluminum reduction depends on the
        preparation and placement of the  carbon anode (positive  terminal)
        and cathode (negative terminal) in the pot of the furnace.   The
        cathode  consists  of a pad of molten aluminum  which  forms over
        carbon blocks located on  the bottom of, and perpendicular to the
        width of,  the pot.  The blocks  are usually made  from calcined
        anthracite.   A carbon paste  is  rammed  between the carbon blocks
        and baked in to seal the  lining.   During operation  of the pot
        alumina  dissociates electrically  and molten aluminum deposits
        at the carbon cathode  and oxygen aggregates  at  the anode and
        combines with some  of the carbon  anode to  form oxides of carbon.
        Since the carbon  cathode  does not significantly  deteriorate, it

-------
                            7.11.5
Figure 7.11.2 not available for this publication.

-------
                           7.11-6
    may last for 2 to 4 years.   Cathode operations are not significant
    from an air pollution standpoint except when they are being baked
    or removed.  In the former,  hydrocarbon emissions from binder
    materials will be produced  and are collected by the exhaust system.
    In the latter, dust emissions may result from the process of removal
    (chipping away) of the carbon from the cold pot.

b.  Anode Preparation
    The anode is also made from petroleum coke, reclaimed anode carbon,
    and pitch or binding material.  Since the carbon in the anode reacts
    with the oxygen liberated from the dissociation of alumina into
    oxygen and aluminum, it is  gradually consumed and must be periodically
    replaced in the case of prebake, or added to in the case of the
    Soderberg pots.

    In the prebake plant, carbon usually in the form of calcined
    petroleum coke is ground, blended with melted pitch (tar) and pressed
    into anode blocks, usually  on a batch basis (see Figures 6.11.3,
    7.11.4 and 7.11.5).  Approximately 1/2 pound of carbon is required
    for each pound of aluminum produced.  Spent anodes are also crushed
    and recycled in this operation.  Wet collectors,  e.g., Rotoclones,
    and other conventional collection equipment are used to collect dusts
    generated in this operation.  Heat is supplied from a boiler plant.

    The carbon anodes are block or tapered forms approximately 2 1/2 feet
    cube.  The green anodes are conveyed by the overhead crane system and
    lowered into the ovens.  The bake oven consists of a series of
    trenches and compartments lined with refractory brick.  A number of
    trenches lie parallel to each other and run the length of the anode
    plant.  The ovens are indirectly fired by means of gas or oil.  Flue
    gas from the combustion equipment flows in chambers adjacent to the
    anode blocks.

-------
 COAL TAR PITCH
   CALCINED
PETROLEUM COKE
        BUTTS
                                        CRUSHER

                          COARSE PARTICLES

                    HAMMER MILL  VIBRATING
                                    SCREEN
                        COARSE PARTICLES
                    HAMMER  MILL

                                               BALL MILL
TO
ELECTROLYTIC •< — 	
CELL
PIT E






iAKING FURNACE
f—
1 V
ii


D V V.
~rnr \"<
q 	 cd COOLING''^
2 	 I_ CONVEYOR
                                                                     TRAM.CAR
                                                                      ra
                                                                       MIXER
_WE1GH
 SCALES
                                        MOLDING F'RESS
                     Figure 7.11. 3.  PREBAKED CARBON ANODE PRODUCTION PROCESS
                                     (SOURCE:  BLOCK AND MOMENT, Reference 1.)

-------
                         7.11.8
                     ANODE PASTE
  CALCINED
  PET.  COKE
   HAMMER
     MILL
STEAM
COAL TAR
 PITCH
   VIBRATING
    SCREEN
       STEAM
                          ANODE
                       |   PASTE
Figure 7.11.4.  SODERBERG ANODE PASTE PRODUCTION PROCESS
             (SOURCE:  BLOCK AND MOMENT, Reference 1.)

-------
Figure 7.11.5.  CARBON ANODES READY FOR USE IN ALUMINUM POTS (SOURCE:
                 INTALCO  ALUMINUM COMPANY,  FERNDALE, WASHINGTON)

-------
                                7.11.10
    The ovens  are  preheated  slowly to  a maximum temperature of around
    1400°F,  and  then cooled  very  slowly.   The  baking cycle may take
    approximately  2-3 weeks.   The heating  cycle is  intended to achieve  a
    durable  anode  with  desired electrical  properties,  e.g., minimal
    electrical resistance, in  order to maximize its service in the pot.
    Carbon monoxide,  carbon  dioxide, sulfur  dioxide and  particulates  are
    emitted  from the anode plant  stack.  After the  anodes  are baked,  they
    are removed  from the ovens, and steel  pins are  inserted and
    copper or  aluminum  connectors are  attached.   Anode assemblies  may
    consist  of 1-4 anodes.   The anodes are conveyed to the potrooms where
    they are installed  in the  pots.

    Emissions  of dust and volatiles driven off the  anodes, along with the
    products of  combustion from the firing equipment are vented through a
    single and usually  tall  stack.   Control  systems,  such  as,  high energy
    scrubbers, catalytic combustion or incineration can  be employed.
    Emissions  include sulfur dioxide contained in the coke fuel oil used,
    products of  pyrolitic decomposition, including  hydrocarbons, and  some
    fluorides.

3.  Potroom  Operations
    a.   Prebake
        The  potroom constitutes the major  source of pollution in an aluminum
        reduction  plant.  Smelting is  performed in  large rectangular  pots  or
        cells  in which  alumina, and the electrolyte are  charged.   The
        electrolyte is  usually cryolite  (sodium aluminum fluoride) and
        fluorspar  (calcium fluoride).  Raw materials required in the
        production of one ton  °f  aluminum  by both the prebake and  Soderberg
        process  are shown in Tables 7.11.1 and 7.11.2.

        The  cells  are arranged in long pot-lines, and wired together  in series
        (Figure  7.11.6).  Direct  current flows through a buss, through  the
        carbon anode, the molten  electrolyte and metal pad and out through

-------
                                7.11.11
          Table 7.11.1.  RAW MATERIALS FOR THE PRODUCTION
                         OF ONE TON OF ALUMINUM
   Material                              Amount (tons)

Sulfur                                     .01 = .05
Alumina (Al203>                           1.9
Cryolite (NasAlFe)                         .03 - .05
Aluminum Fluoride (A1F3>                   .03 - .05
Fluorspar (CaF2)                           .003
Anode
  Petroleum Coke                           .490 Prebake, .455 Soderberg
  Pitch Binder                             .123 Prebake, .167 Soderberg
Cathode (Carbon)                           .02
                 Total:  Approximately    2.6 tons raw material/ton Al

                      (SOURCE:  HANNA, Reference 6.)
          Table 7.11.2  COMPARISON OF REQUIREMENTS FOR
                        PREBAKED AND SODERBERG SYSTEMS
                              Soderberg          Prebaked

Time to produce one ton        37 hours           27 hours
KWH to produce one ton        15,400             13,600
Effluent gas treated
  per 100,000 amperes          4,000 CFM         23,500 CFM (no hoods)
                                                  4,000 CFM (hoods)
Scrubber water                3.3 - 4.4 Gal       10 Gal
                                1,000 CF          1,000 CF
                      (SOURCE:  HANNA, Reference 6.)

-------
Figure 7.11.6.  POTLINE, SHOWING ANODES SUSPENDED IN POTS, SPOKANE, WASHINGTON
                (SOURCE:  KAISER ALUMINUM AND CHEMICAL CORPORATION, OAKLAND,
                CALIFORNIA)

-------
                           7.11.13
    the carbon cathode linings of the cells.  The current is
    characterized by low voltage (around 4.5 volts) and high amperage
    (about 50,000 to 200,000 amps).  The temperature of the molten bath
    will reach 1742°-1792°F.  The molten metallic aluminum forms a layer
    above the carbon lining of the pot and below the molten bath (see
    Figure 7.11.7).  The oxygen liberated by electrolysis reacts with
    the carbon anode to form CO and CO..  Hydrogen fluoride gas from the
    cryolite and particulates are also released.  Emissions from the pots
    are collected by removable hoods or shields and vented through
    ductwork to a scrubber, an electrical precipitator, a fluidized bed,
    a baghouse or limited combinations of these devices.

    The alumina is charged by breaking the crust (the frozen alumina and
    bath material) and laying on a fresh charge of alumina.  This procedure
    is necessary to minimize thermal shock and prevent the addition of
    moisture.  Gases, fine dust and fumes escape from the molten bath and
    if not picked up by the ventilation hoods enter the workroom and
    eventually the outdoor atmosphere.

b.  Soderberg
    In the Soderberg process, briquetted coke and pitch is charged from
    hoppers on top of the anode structure by means of a crane,  which
    moves down over the pot line.  The prebake operation is thus eliminated,
    and baking emissions are captured by the ventilation hoods.  The
    design of control equipment, particularly electrical precipitators,  in
    the Soderberg process must take into account the tarry emissions,  that
    is, collection of wet particulates in the precipitator.

    Two types of Soderberg cells are in use:  side pin or horizontal stud and
    verticle stud (see Figure 7.11.7).   In the former,  alectrical connection
    is made by steel pins or studs inserted horizontally into the side of the
    anode through movable steel channels.       In the latter, electrical

-------
                                               \	
                                           ALUMINA\
                                           HOPPER
                                                                     GAS COLLECTION DUCT
                         6AS COLLECTION
                            HOOOS
                                                      SOLlOiF'ED CRUST
                                                      OF ELECTROLYTE
                                         FULLY BAKED AUOI E   AND ALUMINA
Figure 7.11.7.   DETAILS  OF PREBAKED AND  SODERBERG ALUMINUM REDUCTION CELLS

                   (SOURCE:   ROSSANO AND PILAT, Reference 5,)

-------
                                7.11.15
        connection is made by steel pins or studs inserted vertically into
        the top of the anode.  The anode is contained in a rigid casing open
        at the top and bottom.  The vertical stud has the advantage that the
        off gases from the cell can be collected on a concentrated low volume
        basis by a collecting skirt attached to the bottom of the anode
        casing.  The volume of off-gases is approximately 1/10 of that by
        prebake or horizontal pin methods.  CO and combustible gases are
        passed through burners and fumes are drawn off by ducts and fans to
        a control device, which may include low and high energy scrubbers,
        electrical precipitators and a fluidized-bed baghouse combination.

C.  CONTAMINANTS EMITTED
    The obvious sources of pollution from aluminum reduction plants are the
    stacks from both the anode plant (in prebake facilities) and potroom
    exhaust systems and the potroom air vents and roof monitors.   The tall
    stacks, which may be approximately 500 feet in height,  are intended to
    disperse pollutants and to minimize downwind concentrations of contaminants
    and resultant fluoride damage.  The plumes, however, are long and
    concentrated, and hence visible from many miles away.  Other sources
    include vents, floor operations, control equipment (particularly scrubbers
    in older plants)  and others.

    Types of emissions related to plant operations are shown in Table 7.11.3
    and fluorine and  S02 emissions corresponding to various plant capacities
    are shown in Tables 7.11.4 and 7.11.5.('8)

    The emission of hydrogen fluoride is most significant.   The fluoride ion
    exhibits strong acid properties and can act as a protoplasmic poison,   it
    can damage foliage at .1 parts per  billion, accumulate  in forage to  30-50
    ppm on the inside and outside of leaves and can be fatal to livestock con-
    suming contaminated forage.       Gaseous fluorides can  be sampled by means

-------
                             Table  7.11.3.  EMISSION SOURCES AND CONTAMINANTS
    EMISSION SOURCE
 OPERATION AND  LOCATION
 Cell  operation
    Emission treatment exhaust

              (Soderberg only

 Anode materials handling, grinding,
 classifying
    Building vents
    Dust collector exhaust

 Anode mixing
    Building vents
    Emission collector/treatment exhaust
 Anode baking (Prebake only)
    Building vents
    Emission collector/treatment exhaust


Metal casting
    Building  vents
    Emission  collector/treatment exhaust

 Cathode preparation
    Building  vents
   Dust collector exhaust
    Emission  collector exhaust


Alumina and  electrolyte materials
handling and distribution
   Building vents
   Dust collector exhaust
       CONTAMINANT
GASEOUS
co2, co,
CF.
             PARTICULATE
                    A1F
             Na.CO-,
                       3,
                     carbon dust
Hydrocarbons Tar)
             Carbon dust
             Pitch dust
Hydrocarbons Carbon dust
             Pitch dust
             Tar

C02, CO,     Carbon dust
CA   TJT7
bU_, tlf

Hydrocarbons Tars

C12, HC1     A1C13, A120,

C0?, CO      Cryolite

Hydrocarbons Carbon dust
             Pitch dust
             Tar
             Cryolite, CaF ,
     TYPICAL
 CONTROL  SYSTEMS
 High energy  scrubber
 Electrical Precipitator
 Fluidized bed
 Baghouse
(Wet  collectors
(Baghouse
                                    Wet Collectors
                                    Baghouse


                                   (High energy scrubbers
                                   I Catalytic combustion
                                   (incinerators
                                   (Operational flux
                                   \   and temperature
                                   1   controls
                                   / High energy scrubber
                                   I Electrical precipitator
                                   < Fluidized bed
                                   I Baghouse
                                   \Roof scrubber
                                    Wet collectors
                                    Baghouse
Fugitive Dust Sources
                               (SOURCE:  STATE OF WASHINGTON, Reference 8.)
                                                (Expanded)

-------
             Table 7.11.4.  TOTAL F   EMISSION -  DAILY RATE AND CONTROL EFFICIENCY
rweraoe:
ALUMINJM
PRODUCTION
-ANT TONS
i
2
3
4
5
6
per* day :
e:
480
274
575
220
720
520
:2790
465
ELECTROLYTE
CONSUMED
TONS % OF PROD.
28.5
18.0
31.6
11.5
41.9
27.6
159
26.5
5.9
6.6
5.5
5.2
5.8
5.3
5.7
5.7
POTENTIAL
F" EMISSION
TONS
14.9
9.6
16.5
5.7
22.8
14.0
83.5
13.9
% Oc PROD.
3.1
3.5
2.9
2.6
3.2
2.7
3.0
3.0
ESTIMATED
F" EMISSION
TONS
2. 16
1.82
2.94
i .52
4.56
2.Q2
15.9
2.65
% OF PROD.
0.45
0.66
0.51
0.69
0.63
0.56
0.57
0.58
F CONTROL
EFFICIENCY *
I
85
31
82
73
80
79
81
80
   *Control efficiencies currently possible are in excess of 98 percent.
                      (SOURCE:  STATE OF WASHINGTON, Reference 8.)

-------
           Table  7.11.5.   TOTAL SO  EMISSION - DAILY  RATE AND CONTROL EFFICIENCY
Average:
AlUJIINUH
PRODUCTION
.ANT TONS
1
2
3
4
5
6
>er day:

480
274
575
220
720
520
27SO
465
Af.'ODE COKE AND
PITCH CONSUMED
TONS
229
185
274
122
358
286
1454
242
% OF Pi>OD
47.7
67.6
47-5
55.5
49.8
54.9
52.2
53-8
POTENTIAL
SO., EMISSION
. lOSS
3.15
3.70
18.0*
2.44
6.72
3-56
19.6
3.92
\ OF PROD.
0.67
i-35
3.08*
1.1)
0.94
0.69
0.83
0.95
ESTIMATED
SO, EMISSION
TONS
0.88
1 .00
16.0"
0.92
1.85
0.80
5.45
1 .09
% OF PROD.
0. 18
0.36
2.8"
0.42
0.26
0.15
0.25
0.27
SO CON'iT.UL
EFFICIENCY **
-i
72
73
if
62
72
77
72
71
    ••Not  included in  total  and average values




    **Control efficiencies currently  possible  are in excess of 90 percent.
                          (SOURCE:  STATE OF WASHINGTON, Reference  8.)

-------
                                7.11.19

of sampling trains using distilled water and solutions of NaOH as a
collecting medium.  Particulates are collected by filtration.  Forage
samples can be collected in inert containers such as a one quart glass
jar or freezer bag.  Water soluble fluorine compounds collected from
ambient air are analyzed by use of ion-selective electrode methods and
others.      Ambient air values can be quite low and expertise is needed
to obtain reliable data.

The application of air pollution control methods in aluminum reduction
plants will include improved basic equipment design, such as larger pot
capacities, improved operations such as automating charging; improved
hooding and collection efficiences; addition of controls to more emission
points, such as the roof monitors.

Control methods for aluminum reduction cells include the following:
    Wet Scrubbers.  Spray towers can remove a high percentage of hydrogen
    fluoride since this contaminant is highly soluble in water.   These
    devices, however, have a poor collection efficiency for fine
    particulates.  Recent improvements include a floating-bed type of
    wet scrubber on horizontal Soderberg cells.  This type of scrubber
    tends to overcome the problem of tar fouling that occurs in scrubbers
    with stationary packings.

    Electrostatic Precipitators.  Wet electrostatic precipitators are
    beginning to be used in controlling reduction cell emissions.   These
    include vertical counterflow precipitators employing plywood collection
    plates which are irrigated with a falling film of water supplied from
    troughs at the top of the plates.  Another application utilizes
    continuous spray washing of the collection plates and discharge
    electrodes.

    Chemisorption.  This process was introduced by the Aluminum Company
    of America (ALCOA) for treating gaseous and particulate fluorides.

-------
                               7.11.20

     The method consists of the chemlsorption of hydrogen fluoride on a
     fluidized bed  of  finely divided  alumina and removal of the sorbed
     fluoride by means of a fabric collector.   Particulate fluorides are
     also removed by simple filters.   The ALCOA system (Process A-398)
     requires effective local exhaust hooding on each pot (Figures 7.11.8
     and 7.11.9). '  '   Particulate emissions as low as 3 pounds of HF per ton
     of aluminum produced are claimed.  Contamination of liquid streams and'
     solid waste disposal problems are avoided.  Spent alumina from the
     collector system is recycled to  the pots and sorbed fluoride is
     added to the cryolite make-up.

     Roof Collectors.   In this procedure gases and dust are allowed to
     enter the workroom atmosphere.  Large exhaust blowers at the ceiling
     (Figure 7.11.10)     induce an inward flow of outside air, through
     open louvres on the outside  walls of the building, across the cells
     and into an overhead exhaust system to the gas cleaning equipment,
     usually wet scrubbing.
INSPECTION POINTS
Systems and equipment for controlling aluminum reduction emissions will
require constant upgrading in the years ahead to meet increasingly
stringent emissions standards.  Emissions which may now range from 40-50
pounds/ton aluminum processed will have to be reduced to something like
15 pounds/ton and #1 Ringelmann.   Bag filters and improved electrostatic
precipitators may be the only types of control systems that will help to
realize this goal.   Such design improvements as larger pot capacities,
automated ore feeding, and roof scrubbers should also help to achieve
these goals.

Most of the inspector's function  will be to help assure that compliance
schedules are met,  that control systems are conscientously operated and
maintained, and plant facilities  are  operated and maintained in a manner
which takes into account air pollution control, and prevents environmental
damage in the vicinity of and downwind from the plant.

-------
       HOODING
REMOVABLE
  HOOD
 SECTIONS
                         ALUMINA FEED
                           HOPPER
                            PREBAKEO
                             ANODE
  SERVICE
ACCESS DOOR
    Figure 7-11.8.  SCHEMATIC OF ELECTROLYTIC  CELL AS USED IN ALCOA A-398 PROCESS
                     (SOURCE:   ROSSANO AND PILAT,  Reference 5.)

-------
            AIR JETS.
  GAS
DISCHARGE
 CONOUr
                                                   ,8AG FILTERS
              9999999999999/999
PERFORATED
  PLATE
  BED
  DEPTH
 CONTROL  -V
ELONGATED CHAMBER


             ALUMINA BED
         GAS DISTRIBUTION CHAMBERS
                                                                                    GAS
                                                                                -COLLECTING
                                                                                   HOODS
                                                                       T7TT1
                                     a  n  n  n
                                     ELECTROLYTIC CELLS
            Figure 7.11.9.  SCHEMATIC  OF  ALCOA GAS CLEANING PROCESS.  (A-398)
                            (SOURCE:   ROSSANQ  AND  PILAT,  References.)

-------
                                            Cleaned Air


                                           A   A   A    A
Air from Potroom
         >
         >~
                           Coarse sprays }
>-
>
   Mist
Eliminator
                             Coarse sprays
                                                                                               Slope
                                                                     Screen
                 Four banks of Fine Sprays
                           Figure 7.11.10.   CROSS-SECTION OF ROOT  SCRUBBER
                                              (SOURCE:   BYRNE, Reference 7.)

-------
                              7.11.24
1.    Environmental Observations
     In the conduct of  the  inspection,  the  inspector  should  patrol,  and
     tour on foot, the  exterior  of  the  plant  looking  for  possible damage
     to forage and foliage.   The type of  damage  that  may  occur  varies with
     the species  of vegetation.   Any appearance  of  damage, particularly
     on margins and tips  of  leaves  should be  suspect  and  sampled.   It may
     also be desirable  to sample foliage  that appears undamaged for
     analysis whenever  there is  reason  to suspect that damage may be
     occurring.  Samples  should  be  taken  in forage  areas  to  ascertain the
     possibility  of damage  to livestock.  Visual observations of livestock
     could also be made.  In any event, if  an inspector found something to
     suspect, a person  with  expertise in  fluoride vegetation or animal
     effects should be  consulted.
     In selecting  sampling  points,  prevailing winds  and  distances  from
     the stacks  should  be taken  into  account.   The following  procedures
     should  be used  in  forage  sampling:
          •   Cut the forage with a  sharp  knife  or shears about  2 inches
             above the  ground  to avoid contamination by  soil  particles.
             Collect about  200 grams  of sample;  cut  it into 1/4" to  1/2"
             pieces  and store  it in an appropriate container.
             Samples may  be  stored  for up  to  5  days  before  analysis,  at
             refrigerator temperatures  (5°C).   Store the  samples  at  0°C  or
             lower  if  they are  to be  kept  for longer than 5 days.

             Care must be taken to  assure  that  the sample represents  the
             intake of the animal using  the forage.   In general,  the
             sample should include  the main species  of forage  vegetation
             in about  the same  proportion  as  they grow in the  field.

-------
                           7.11.25


     •  Do not  take samples within 100 feet of any road unless it
        can be  shown  that road dust contamination is not a factor.

The following information must be included as part of the sample
identification:
     •  Date of sample

     •  Time of day

     •  Location of sample

     •  Types and approximate proportions of vegetation in the sample,

     •  Weather conditions

     •  Any abnormal  factor such as heavy traffic, construction in
        the area, harvesting nearby, etc.

     •  Original source of sample—is it stacked hay, baled hay, etc.

     •  Name of person who took the sample.

Exterior of Plant
The inspector should  observe the exterior of the plant noting all
emission points and the character of the emissions including
the tall stacks, roof monitor emissions, scrubber outlets and other
parts of the plant structure.  In some locations, reading visible
emissions from monitors may be approved procedure.  Also, in some
localities, background humidity readings, with the use of a sling
psychrometer may be required (see Chapter 4).   Scrubber outlets
may have a tendency to contain a significant portion of dry fume in
the emissions.

-------
                               7.11.26
3.    Interior of  Plant
     In the interior  of  the  plant,  the  inspection should  be organized
     around the initial  alumina  handling  procedures,  the  anode plant and
     control systems  (some plants may conduct  both prebake and Soderberg
     operations),  the potrooms,  potroom control  systems,  and cast houses
     and other secondary metal operations.   The  inspector should note the
     following:
     a.  Firing system and fuels used in  anode ovens,  such as gas or oil,
         and the  effectiveness and  status of control  systems.

     b.  General  potroom emissions.  The  inspector should view down the
         potline  for  general inplant emissions,  the degree to which
         emissions are expelled  through the  monitors  and  side vents, and
         handling  of  tapping and pot maintenance operations.   The extent
         of emissions within the potrooms will give some  idea of the
         general operational efficiency.  HF is  an eye and nose irritant,
         therefore, evidence of  HF  emissions could be detected by eye
         irritation or odor.
     c.  Collection efficiency of hooding in potrooms.  When pots are opened
         to replace anodes,  charge  materials or  to tap furnaces hooding ef-
         ficiencies can  be greatly  reduced.  The inspector should note how
         long the  pots are open, and whether the hoods are damaged due to
         handling.  Sometimes shields are pulled on 4-5 pots at a time.   Auto-
         matic ore feeding employed in  new plants may  greatly reduce oper-
         ational  emissions.

     d.  Operational  schedule of potroom. The inspector  should become
         familiar  with this  schedule.   The anode replacement schedule is
         usually  equivalent  to the  anode  baking  schedule, in prebake
         plants.   Cathodes are replaced less frequently,  every 2 to 4 years
         depending on pot life.

-------
                            7.11.27
e.  Voltage readings on guages located atop each furnace.   Voltages
    are relative to initial plant design,  production schedules,  etc.
    Generally, 4 to 6 volts is normal.

f•  Pot performance.  An anode effect is caused by the depletion of
    alumina and results in increased temperature, vapor pressure and
    fluoride and other emissions.  If caught in time, the condition
    can be corrected by adding alumina, agitating the pot and/or
    adding more air.  A sick pot results from too much alumina and
    causes a cold spot to form in the pot, a decrease in resistance,
    and an impairment of the electrolytic  process.  A light and a bell
    usually signal an anode effect and a sick pot respectively.   The
    inspector could inquire about the rate at which these malfunctions
    occur per potline per day.

§•  Performance characteristics and maintenance practices of scrubbers
    and other control equipment serving the pot ventilation system.
    The plant should also have the capability to by-pass to an
    alternative system, when it is necessary to shut down one of the
    control systems.  The inspector should note capacities of
    scrubbers, special design features, such as mist eliminators and
    straightening baffles.  The inspector should note the disposal
    of waste water from the scrubbers.  High fluoride water should not
    be sent to rivers and lakes.  United States Public Health Service
    standards require fluorine below 1 ppm if river is used for
    drinking supply.  The inspector should also determine if pH
    adjustment of water is made in the scrubber.

h.  Emissions from holding furnaces.  The inspector should physically
    inspect all plant operations including cast houses and fabrication.
    Aluminum holding furnaces (see Chapter 7.8, part Old) are used to remove
    air, organic matter and traces of metal as magnesium.  The control
    of chlorine emissions from fluxing agents is poor or nonexistent
    at most primary aluminum smelters.  Chlorine odor has a sweet,
    sickly odor and is easily noted when touring an aluminum plant.

-------
                                    7.11.28
                                  REFERENCES


 1.   Block,  I.,  and S. Moment.  Pacific Northwest Economic Base Study for Power
     Markets, Vol. II, Part 7B.  U.S. Department of the Interior, Bonneville
     Power Administration.  Portland, Oregon.  1967.

 2.   The Aluminum Association.  The Story of Aluminum.  420 Lexington Avenue,
     New York, New York  10017.

 3.   Nelson, K.  W.  Nonferrous Metallurgical Operations.  In:  Air Pollution,
     Vol. Ill, A. C. Stern (ed.).  New York City, Academic Press, 1968.

 4.   Background  Report in Support of Regulations and Standards for Primary
     Aluminum Plants.  State of Washington, Department of Ecology.  April 1970.

 5.   Rossano, A. T., and M. J. Pilat.  Recent Developments in the Control of
     Air Pollution from Primary Aluminum Smelters in the United States.
     Second  International Clean Air Congress of the International Union of the
     Air Pollution Prevention Association.  Washington, D.C.

 6.   Hanna,  T.   Air Emissions from Primary Aluminum Industry.  Term Paper,
     Air Resource Program, Department of Civil Engineering.  University of
     Washington.  March 10, 1970.

 7.   Byrne,  J. L.  Fume Control at Harvey Aluminum.  Presented at Annual
     Meeting, Pacific Northwest International Section, Air Pollution Control
     Association.  Spokane, Washington.  November 16-18, 1970.

 8.   Background  Report in Support of Regulations and Standards for Primary
     Aluminum Plants.  State of Washington, Department of Ecology.  April 1970.

 9.   Thomas, M.  D.  Effects of Air Pollution on Plants.  E. 0. Catcott.  Effects
     of Air  Pollution on Animals.  World Health Organization.  Geneva, 1961.

10.   Methods of  Sampling and Analysis for Fluoride in Ambient Air and Forage.
     Washington  State Department of Ecology, Air Quality Control Branch.
     Appendix 1  to Chapters 18-48 EAC.  September 1970.

-------
                                     7.12.1
                                 XII.  MINING

A.  NATURE OF SOURCE PROBLEM
    Mining is the process of extracting mineral wealth from the earth, sea, or
    atmosphere.  Since these mineral assets are not self-replenishing, it is
    important that they be collected in an efficient and non-wasteful manner.

    The air pollution problem from mining operations involves primarily par-
    ticulates from surface operations and combustion contaminants from fires.
    Additional pollutants are emitted into the ambient atmosphere via the
    ventilation systems of underground mines.

    Mining often results in other forms of environmental pollution as well.
    Water contamination may occur as runoff passes through surface mining
    regions and into nearby bodies of water.   This may have a very detrimental
    effect on the water supplies of downstream communities.

    The condition of the land after mining is completed is becoming a major
    issue to conservationists.  They are particularly critical of its ravaged
    appearance and apparent uselessness as a resource.

B.  PROCESS DESCRIPTION
    In order to remove natural resources from the ground, either underground
    methods and/or surface techniques may be employed.  The character of the
    mineral deposits and the state of technology have important bearing on the
    procedure selected.   In actual practice,  it is more desirable to employ
    surface procedures for the following reasons:

         •  It is possible to recover deposits which often could not
            be retrieved by underground means.

-------
                               7.12.2
        Safer and more healthful working conditions are provided
     •  A more complete retrieval of the resource is accomplished.

     •  The cost per unit of production is less than with below
        ground methods.

Generally, surface mining is only possible if the thickness of the covering
material (overburden) is small as compared to the size of the mineral
deposit.

The utilization of below ground techniques requires extensive planning and
consideration of a number of significant factors.  Some of these include
digging and supporting the mine, removing the resource, keeping the
mine atmosphere healthful and free from the possibility of explosion,
and other safety factors.  Although proper planning is necessary for
surface mining as well, the number of factors involved overall are
far fewer and less critical.

1.  Surface Mining
    The surface mining methods producing the greatest air pollution
    effects are strip mining and open-pit mining.  Strip mining is
    of primary importance in connection with coal.  Open-pit mines are
    normally constructed in order to recover copper, iron and gypsum.

    Regardless of the equipment or technique used, surface mining consists
    of the following steps:

         •  Site preparation—constructing access roads, designating
            dump sites, and clearing vegetation and other obstructions.

-------
                        7.12.3


 •  Removal and disposal of overburden.

 •  Excavation and collection of the deposit.

 •  Transportation of the mined resource for processing.

Strip Mining
Strip mining is usually applied to recover coal deposits that
are located near the surface of the earth.  It consists of
removing the overburden covering the mineral bed, and then
loading the uncovered material.

Strip mining techniques are utilized on both flat and hilly terrain.
On flat areas, a series of parallel cuts 40' to 150' wide are made
in the surface.  The overburden from the first cut is deposited in
an area where no deposit exists (if possible).  Thereafter, the
overburden from one cut is deposited in the trench made by the
previous cut.  This process may be carried on systematically
throughout the mining site.

 If  the area is hilly,  the deposit  may outcrop at  the surface.
 In  this  case,  the  first cut  is  made at  just above the exposed
 deposit  with the overburden  dumped further down  the hill.
 As  additional cuts  are made,  the overburden to be removed
 becomes  thicker.   It is piled next to the previous  overburden
 in  waste banks or  spoil piles.  These series  of  cuts continue
 until  the overburden gets too thick as  compared  to  the amount
 of  deposit to  be retrieved.   Equipment  utilized  in  strip mining
 consists  mainly of  bulldozers,  draglines,  and large power  shovels.

-------
                        7.12.4
The most serious air pollution problem in strip mining involves
the extremely high combustibility of coal spoil piles.  The spoil
is stored in an area where the useful mineral is not being
developed.  Waste from coal cleaning and washing operations (see
Section XIII) is frequently added to the piles.  They are commonly
ignited spontaneously or by burning rubbish close by or in strip
pits.  Once ignited, these waste banks may burn for decades emit-
ting smoke and gases into the atmosphere and are very difficult,
if not impossible, to extinguish.

A 1964 survey^' counted 495 burning refuse piles in the United
States.   Often the burning piles are covered with some inert
material  to try  to cutoff the oxygen supply.  This practice only
proves to be a temporary measure and the fire usually picks up
again.

In the past, many methods to control fires, such as flooding,
blanketing, slurry injection, and compacting have been attempted.
However,  a potential fire hazard will continue to exist unless the
temperature within the spoil bank is maintained below the kindling
point.  Active burning is usually visible on the sides and bottoms
of the spoil piles, where the large blocks of refuse generally tend
to accumulate during dumping.  Air is able to penetrate through the
crevices  formed by these blocks, is heated, and rises as if in a
chimney.  Changes in barometric pressure cause considerable air
flows into and out of the pile.

The  Bureau of Mines conducted a research program designed to aid
the  coal-mining industry in the control of burning refuse, and its
disposal  in a safe and economical manner.  The Bureau studied the
permeability of refuse, its spontaneous ignition tendency, and
methods of extinguishing a burning pile of coal.

-------
                              7.12.5
    In field tests,  the Bureau extinguished a five acre burning refuse
    pile in fifteen months.   The technique involved decreasing the
    slope of the flank to approximately 30° and compressing the surface
    with a bulldozer.   The pile was then covered with a three to five
    foot layer of minus 1/4-inch refuse material.  A dike was constructed
    above the flank to prevent erosion.  When the fire was determined to
    be out, the temperature of the pile three feet below the surface was
    less than 100°F.

    In other experiments it was judged that minus 1/4-inch mesh refuse has
    little tendency to ignite spontaneously.  In addition, under labora-
    tory conditions it was found that four times as much air passed through
    3 1/2-inch mesh refuse than through 1/4-inch mesh refuse.

    Field investigations have shown that reducing airflow into the pile
    decreases the possibility of spontaneous combustion.  Since most of
    the air enters the refuse pile through the flank, a dumping technique
    that reduces the flank area is preferred.

    Although this technique has proved successful in testing, there is
    at present no indication how widespread its use is in practice, or
    how successful it has been.

    Strip mining methods also often tend to liberate explosive gases such
    as methane, hydrogen sulfide, and acetylene.  However, if allowed
    to be diffused into the atmosphere, the hazards due to possible
    explosion are eliminated.  If the gases are trapped in any manner,
    the situation must be considered dangerous.  The presence of hydro-
    gen sulfide gas is easily detected by a strong odor of rotten eggs.

b.  Open-Pit Mining
    Open-pit mining is a common method used to extract consolidated ore
    deposits that are located at or near the earth's surface.  These

-------
                          7.12.6
mines are generally cut into and around a hill or mountain, or are
forged into the ground.  They necessitate the removal of large
amounts of overburden before actual deposit recovery may begin.
Loose overburden is easily done away with, but all other rock must
be excavated by combinations of the four principal operations of
mining—rock drilling, blasting, loading, and haulage.

Drilling operations are employed to form blast holes.  The type and
amount of explosives used are governed by the character of the rock.
Generally dynamite or ammonium nitrates are utilized.  Loading is
done by very large capacity power shovels and draglines.
Haulage systems may utilize railroad cars, trucks, inclined skip
hoists, or belt conveyors.

The system employed is determined by the depth of the pit, the pro-
duction required, and the distance to the crusher or waste pile.
                     \
Open-pit mines are generally structured in benches or terraces.  Each
bench must be wide enough to carry trucks or railcars on tracks and
not be buried in blasting operations.  Sufficient space must also be
available for large power shovels.  Benches are usually between 20
and 76 feet in width.  Fifty feet may be considered an average figure,
with 30 feet regarded as a practical minimum.  When the height of a
face or bank exceeds a safe and practical limit, another bench must
be created.

The general slope of the entire mine is measured by a line connecting
the outer edge of the top and bottom benches.  The height of each face
and width of each bank must be such that the general slope of the mine
considering all terraces is between 22° and 60°.  However, since
open-pit mines vary a great deal, slope criteria is extremely diffi-
cult to fix.

-------
                           7.12.7
Open-pit mining methods are used to produce iron, copper, sand and
gravel, gypsum, limestone  and marble.  The amount of overburden
removed is small as compared to the amount of product recovered.  In
many cases, deposits are very thick resulting in a continuous mining
activity for decades.

Some open-pit mines are difficult to distinguish from strip mines.
This is especially true with certain brown iron ore and clay mines.
Iron ore pits are generally quite large and quite deep.  Lean, low-
grade ore is often piled near the mine but is not responsible for
very much environmental pollution.

Copper pits consist also of large openings.  They are few in number
and located in arid or semi-arid regions.  Overburden and waste piles
occupy large surface areas as well.  Care must be taken to prevent
their location above future ore reserves, yet close to the mine to
reduce transportation costs.  The waste piles may become a source of
sedimentation and dust if preventive measures are not taken.

Frequently the waste pile contains small quantities of ore which is
recovered by leaching.  Leaching is the extraction of a mineral from
an ore by selectively dissolving it into a suitable solvent as water
or acified water.  It is therefore desirable that the ground under
the piles be impervious to leach water.  Leaching is responsible for
approximately 12% of recovered copper ore in the United States.

Sand and gravel pits are generally more disturbing to the general
public than iron and copper mines.  They are often located in or near
urban centers where blowing dust, unsightly appearance, and noise are
annoying problems, and steep banks are subject to dangerous slides.
Other sand and gravel operations may be in the vicinity of streams.
In these cases, significant amounts of sediment may be drained into
the waterways.

-------
                              7.12.8
2.  Underground Mining
    Distinctly subsurface deposits  of  minerals  and ores  are extracted by
    underground mining methods.   Metal mining practices  are similar to those
    used in coal mining except that the former  are more  diverse because of
    the more numerous variations in ore deposits.

    The primary mine plans of operation are stoping and caving.  In stop-
    ing, the ore-body is broken by drilling and blasting.  There are
    various stoping techniques but the method selected is dependent upon
    the physical characteristics of the deposit in the mine, and economic
    and safety factors.  Caving is often applied to large ore deposits
    with lower mineral content.  A void is created below the ore-body, and
    then support is withdrawn from below.  Possibly with the aid of blast-
    ing, the ore-body is collapsed allowing the ore to be drawn off.
    Another technique involves the caving-in of covering waste matter
    followed by the mining of the ore deposit from above.

    In underground mines, special attention must be paid to the maintenance
    of safe and healthful working conditions for workers.  Among the factors
    to be considered are mine support, explosives, air quality, and fires.

    Except if included under state law, normal air quality requirements
    require the absence of smoke and dust with moderate air temperatures.
    In addition, coal mines require the elimination of methane.  Good
    quality air does not contain harmful amounts of physiological or
    explosive contaminants.

    The following gases are common to underground mines  and should be
    expelled as contaminants.

    (1) Carbon dioxide is produced by the combustion and oxidation of
        organic compounds.  It is usually found in low,  poorly ventilated

-------
                           7.12.9
(2) Carbon monoxide is not normally found in mine air.  It is
    formed as a result of mine fires, or from gas or dust explosions,
    and the incomplete combustion of carbonaceous matter.

(3) Hydrogen sulfide is found near pools of stagnant water in poorly
    ventilated mine sections, and is the product of the decomposition
    of sulfur compounds.

(4) Methane is a natural constituent of all coals and may be found
    in metal mines as well.  This highly explosive gas is often
    found in high, poorly ventilated cavities.

(5) Sulfur dioxide is commonly found only in sulfur mines.  It is
    usually present after fires in rich sulfur ore mines.

(6) Black damp is a term used to describe oxygen deficient mine
    atmospheres that may contain many gases.  It is produced by
    oxidation and processes that use oxygen and give off carbon
    dioxide.

In order to maintain mine safety, equipment is available to deter-
mine the presence of these contaminants in mines.

Dust in mines may be both a physiological and an explosive hazard.
The incidence of various  forms of pneumoconiosis (dust-related
respiratory diseases) are common among miners, while coal dust
presents an extreme explosive danger.  Preventive measures include
suppressing the dust with water, sprays, foam, or other agents.

Effective ventilation systems are required in mines in order to
dilute mine gases and render them harmless, and to extract or
collect dust particles from the mine.  Various quantities of gas

-------
                                     7.12.10
          or dust  may  be  expelled  Into  the  ambient  atmosphere,  but  no data
          are presently available  that  will permit  estimations  of emission
          rates.   Investigations should be  conducted  on  this  emission source.

C.   INSPECTION POINTS
    Because mining operations  present health  hazards  to  workers and are the
    basis of conservation issues,  they  are  extensively supervised and inspected
    by other Federal and  state agencies such  as  the Bureau of Mines and state
    divisions of  mines.   The purpose of this  supervision is to  minimize hazards
    related to physical injury and to occupational  exposures  to air contaminants
    within the mines (especially from CO, C02, S02> H2S, methane, etc.).

    The field enforcement officer  is interested  in  mining activities from a
    number of standpoints:

    1.  Mines may be subject  to equipment or  activity inventory or  source
        registration inspections.   The  enforcement  officer therefore must
        become familiar with mine  operations.  All  discrete surface and
        internal  mine operations should be  inventoried and described.

    2.  Dusts, smoke and  organic emissions  will  occur from surface  operations
        such as amassing  spoil piles, loading and dumping, transportation
        activities and coal preparation (see  Section  XIII).  The emissions
        and their sources should be surveyed,  and notices written where
        indicated.  Mine  owners should  prepare and  submit source reduction
        plans.

    3.  Some mines will have  greater emission potentials than others, due to
        the type  of mine  and nature of  the  deposits (e.g., sulfur deposits).
        Mine operational  methods,  products  and capacities should be care-
        fully shown on reports.

-------
                                 7.12.11
A.  Ventilation systems should be checked and evaluated both  from the
    standpoint of mine safety and emissions  to the  atmosphere from surface
    outlets.   If necessary,  air samples  should be taken for analysis,  or
    source tests conducted.

5.  The enforcement officer  should be aware  of the  hazards  that  may be
    present to himself and others.

-------
                                      7.12.12
                                   REFERENCES

1.  Stahl, R.  W.   Survey of Burning Coal-Mine  Refuse Banks.   Bureau of Mines.
    Information Circular,  No.  8209.  1964.

2.  Myers, J.  W.,  J.  J.  Pfeiffer,  E.  M.  Murphy,  and F.  E.  Griffith.  Ignition
    and Control of Burning of  Coal Mine  Refuse.   Bureau of Mines.   Report of
    Investigations No.  6758.   1966.

-------
                                    7.13.1
                        XIII.   COAL PREPARATION PLANTS

A.  DESCRIPTION OF SOURCE
    Coal preparation plants clean, blend, size, dry and store raw coal which when
    mined contains 20 to 50% refuse material of undetermined size.  Materials
    handling, sizing, drying and storage procedures and associated air pollution
    control problems are similar to those of many industries where large
    quantities of rock-like material are processed.  Coal preparation plants
    also will play an increasing role in providing low sulfur coal in the
    future.

    Air pollution control problems from coal preparation plants are sizeable.
    Among them are dust from the many drop points, conveyors and open storage
    piles; smoke, H S, sulfur oxides and other odors from burning refuse
    piles; particulate emissions from thermal dryers,  de-dusters and other
    cmmbustion related processes.

B.  PROCESS DESCRIPTION
    The preparation of coal for use by utilities or the metallurgical industry
    divides into two major air pollution control problems:  (1) dust and
    particulate matter from the many mechanical and thermal processes in the
    plant and (2) gas, odors and particulates emitted from burning refuse piles.

    Coal preparation plants vary in capacity and preparation methods.  Common
    processes which create dust and particulates are cleaning processes, sizing,
    drying, refuse and storage.

    1.  Cleaning Processes
        The principal reason for cleaning coal is to reduce ash content and
        some amount of surface sulfur.  Sulfur, in the form of pyritic sulfur,

-------
                             7.13.2
(sulfur combined with iron), organic sulfur (sulfur combined with coal)
or sulfate (calcium sulfate)   and mineral matter are present in raw
coal.  Ash-forming mineral matter can be removed by common cleaning
methods but the inherent impurities—finely divided pyrite, organic
sulfur and inherent mineral matter—cannot be removed.

                                                             (2)
The general cleaning methods in use in the United States are:
•   Cleaning at the mine face
•   Separating impurities manually or mechanically
•   Froth flotation
•   Gravity concentration
      a.  wet
      b.  dry or pneumatic

Mechanical, strip and auger mining account for most of  the coal mined
in the United States.  Manual cutting and loading in which the
impurities in the coal are reduced at the source by selective cutting
is still performed.  This process is known as cleaning  at the mine
face.  Increasing use of mechanical devices,  however, has greatly re-
duced the need for this procedure.

The earliest method of cleaning coal, hand picking, is  still practiced
along with mechanical assistance from shake tables.  After the initial
screening operation, oversized coals, 4 inches and larger, are sent
to the picking table where the impurities are manually  removed from
the stream coal.  Picking facilities include belt and apron conveyors,
shaking tables and occasionally chain conveyers.  Since hand picking
can leave as much as 50 to 60% coal in the refuse, it is economical to
crush the refuse to reclaim the coal by mechanical means.  An example
of a mechanical device for removing flat impurities from coal such as
slate and shale, which can be installed on shaker screens, is shown in
Figure 7.13.1.

-------
                             7.13.3
                 COAL
                                SLATE AND SHALE
   Figure 7.13.1.   REJECTION OF FLAT REFUSE BY  SLOT  SHAKER
   (SOURCE:  THE BABCOCK AND WILCOX CO., Reference  2.)
Froth flotation supplements other cleaning processes by recovering
coal fines from coarse coal cleaning.  Flotation  media  may consist of
alcohols and an added frothing agent.  This process  is  most effective
for 48 mesh and smaller material.  The mixture  is agitated by air
injection with the  coal particles adhering to the bubbles and the slate
and shale sinking to the bottom of the vessel and removed as waste.

The principles of gravity concentration apply to  wet and pneumatic
systems for removal of impurities based upon differences in specific
gravity (see Table  7.13.1).  Wet systems in use in  the  United
      (2)
States    include:
•   Launders
•   Jigs
•   Classifiers
•   Dense-media method

  Table 7.13.1.  SPECIFIC GRAVITIES OF COAL AND IMPURITIES

                 Material             Specific Gravity
               Bilumiiious ^o.tl            1.12 - 1.35
               Bono coal                 1.3.3-1.7
               Carbonac'coiH ilutle          1.6  -2.2
               Shale                    2.0  -2.6
               Clay                     J.8  -2.2
               Pyritc                   4.8  -5.2
      (SOUJICE:  THE  BABCOCK AND WILCOX CO.,  Reference 2.)

-------
                                  7.13.4
a.  Launders
    In launders, shown diagramatically in Figure  7.13.2,  coal is fed
    into a trough where high velocity water  is  introduced.  The stratification
    of coal, middlings and slate occur in the steep section of the device.
    As the slope decreases the velocity  of the  mixture decreases allowing
    the heavier particles to settle  and  the  cleaned coal to be removed.
            ,-RAW.COAL FEED
                                   SLATE AND
                                  HIGH % ASH
                                   MIDDLINGS
  SOME SLATE AND MIXTURE OF
HIGH AND LOW % ASH MIDDLINGS
 (REV/ASHED OR FOR REWASHING)
 Figure 7.13.2.  DIAGRAM OF RHEOLAVEUR COAL LAUNDER WITH TWO RHEOBOXES
                 (SOURCE!  THE BABCOCK AND  WILCOX CO.,  Reference 2.)

b.  Jigs
    Coal on  screen plates  is  subjected to pulsating streams of water  in
    a device known as  a jig.   The Baum jig, which uses air and water  to
    produce  pulsation  can  operate over a wide range of coal sizes while
    some types  of jigs depend upon careful control of coal size  in  the  feed
    for good classification results.   An example of a Baum jig is shown in
    Figure 7.13.3.   This system  operates in two stages.  Primary
    separation  takes place at the feed end, while quality coal and  middlings
    go to a  second compartment where the quality coal is separated  and  the
    middlings are recycled.

-------
                            7.13.5
        Figure 7.13.3.   McNALLY NORTON STANDARD WASHER
                        (SOURCE:  MC NALLY,  Reference 3.)
    Dense-media
    The dense-media  process uses  a  mixture  of water  and sand or magnetite,
    Fe.,0, ,  proportioned  to give the desired specific gravity to float  coal
    and allow  the waste  material  to sink.   Figure  7.13.4  is a  cross-
    section of a McNally Tromp  Bath using the laminar flow principal  to
    provide strata of equal density medium  for  uniform settling.  Machines
    that provide more than one  stage of  settling,  when required,  may  also
    be used.
d.  Classifiers

    Pneumatic classification systems process coal that has already been
    screened and is preferably low in moisture.   Jigs and tables are used
    with air as the fluid instead of water.   Air, blown up through the
    table suspends the lighter coal while the heavier waste material is
    caught in grooves between the rifles on  the  table bottom.   The table
    is  tilted and agitated so that the waste settles and the coal and
    middlings remain on top.  The air used in this process is  passed
    through cyclones and baghouses for fine  dust collection.

-------
                                7.13.6
           Figure  7.13.4.   CROSS  SECTION McNALLY TROMP BATH
                           (SOURCE:  MC NALLY, Reference  3.)

        De-dusting usually  occurs after the raw coal  has  been screened.   Coal
        dust rather than  refuse is removed in  this  process.   The dust  clinging
        to the lumps falls  free as the coal drops into the de-duster.   A
        stream of  air with  a velocity high enough to  entrain the dust—48
        mesh—is forced counter to the flow of coal.  The resultant air and
        coal dust  mixture is run  through cyclones and baghouses to remove the
        fines which can be  loaded with the product  or burned in any of the
        furnaces used in  coal  drying.
2.
    Run-of-the-mine coal  must  be broken,  sized  and screened before cleaning
    or washing.   These processes,  along with handling,  loading,  storage
    and general  housekeeping,  account  for most  of  the dust emissions from
    coal cleaning plants.   Screen sizes generally  conform to ASTM Standard
    D431, designating the size of coal from its analysis, but Bituminous
    coal sizes have not been well standardized. The following are common
                 (2)
    designations.

-------
                            7.13.7
•   Run-of-Mine.  Run-of-mine is shipped without screening.  It is
    used for both domestic heating and steam production.
•   Run-of-Mine (8 in.).  This is run-of-mine with oversize lumps
    broken up.
•   Lump (5 in.).  This size will not go through a 5-in. round hole.
    It is used for hand firing and domestic purposes.
•   Egg (5 in. x 2 in.).  This size goes through 5-in. and is retained
    on 2-in. round-hole screens.  It is used for hand firing, gas
    producers, and domestic firing.
•   Nut (2 in. x 1-1/4 in.).  This size is used for small industrial
    stokers, gas producers, and hand firing.
•   Stoker Coal (1-1/4 in. x 3/4 in.).  This size is used largely for
    small industrial stokers and domestic firing.
•   Slack (3/4 in. and under).  Used for pulverizers, cyclone furnaces,
    and industrial stokers.
•   Several other sizes of bituminous coal are prepared by different
    producers, especially for domestic-stoker requirements.

Definite sizes of anthracite coal are standardized and shown in Table
7.13.2.

        Table  7.13.2.   COMMERCIAL  SIZES OF  ANTHRACITE
                        (Graded  on  Round-Hole  Screens)
         (SOURCE:  The  Babcock and  Wilcox Co., Reference  2)
                               Diameter of Holes, Inches
Trade Name
Broken
Egg
Stove
Nut
Pea
Buckwheat
No. 1
No. 2 (Rice)
No. 3 (Barley)
No. 4
Through
4^
3M to 3
2A
IK
«

A
A
A
A
Retained On
3li to 3
2A
}%
iJ
A

A
A
A
3
0 -f

-------
                            7.13.!
The broken, egg, stove, nut, and pea sizes are largely used for hand-
fired domestic units and gas producers.

Buckwheat Nos. 1 and 2 are used in domestic stokers and hand-fired
steam boilers.  Buckwheat Nos. 3 and 4 are used for traveling-grate
stokers, and No. 4 is also burned in pulverized form.

a.  Breakers and Crusher
    Size reduction is usually accomplished in two stages—breaking and
    crushing.  Breaking the run-of-the-mine coal, removing rock and
    tramp iron is accomplished by a rotary equipment, such as the
    Bradford Breaker, shown in Figure 7.13.5.  As the coal enters
    the perforated drum it is raised by the rotary motion (about 20 RPM)
    and falls breaking the lumps into smaller sizes that pass through
    the perforations.  This process does not produce large quantities
    of fines.
               RECEIVING
                RING
                          DISCHARGE
                    REMOVABIP
                              DISCHARGE
                rTf
 Figure 7.13.5.   BRADFORD BREAKER, FOR USE AT MINE AND PLANT
      (SOURCE:   The Babcock and Wilcox Co.,  Reference 2)
    The next class of equipment is crushers which, by mechanical action,
    further reduces the size of the coal.  They are:
    •   Single Roll crushers which produce large quantities of fines—
        Figure 7.13.6.
    •   Double Roll crushers which produce small quantities of fines—
        Figure 7.13.7.

-------
                            7.13.9
        Hammer-mill crushers which produce large  quantities of fines-
        Figure 7.13.8.

        Ring coal crushers which produce  large  quantities  of fines—
        Figure 7.13.9.
                                     ADJUSTABLE
                                      PLATE
Figure 7.13.6.  SINGLE-ROLL COAL  CRUSHER—DIAGRAMMATIC SECTION
      (SOURCE:  The Babcock and Wilcox Co., Reference  2)
Figure 7.13.7.  DOUBLE-ROLL COAL CRUSHER—DIAGRAMMATIC.SECTION
     (SOURCE:   The Babcock and Wilcox Co., Reference 2)

-------
                           7.13.10
Figure 7.13.8.  HAMMER-MILL COAL CRUSHER—DIAGRAMMATIC SECTION
     (SOURCE:   The Babcock and Wilcox Co., Reference 2)
                                            ACCESS
                                             DOOR
    Figure 7.13.9.  RING COAL CRUSHER—DIAGRAMMATIC SECTION
     (SOURCE:  The Babcock and Wilcox Co., Reference 2)

-------
                            7.13.11
b.  Screening
    Screens provide another method of sizing.  The bar screen or
    grizzly is used at the mines to size coal by gravity.  The bars
    are sloped to allow the larger size lumps to traverse the screen
    while the smaller sizes fall through the openings.

    Revolving screens are similar to rotating breakers except that
    they are inclined.  Since the coal has a tendency to break in this
    type of action it is not customary to use coal sizes larger than
    3 inches.

    Shaker screens are usually sloped downward from the feed end to
    the discharge end.  Again the oversize coal rides down the shaker
    and the desired size falls through the holes in the screen.  This
    process is also used for dewatering washed coal.

    Vibrating screens are also sloped from feed to discharge end.
    The high frequency vibration continually loosens the feed from
    the openings which aids in dewatering.

    These processes produce significant quantities of fine dust.  In
    addition to the use of local exhaust systems to capture dust, water
    sprays with wetting agents help to control emissions from these
    sources.
Mechanical drying or dewatering devices have been described above.  The
greatest single source impact on air pollution in coal preparation
plants is thermal drying.  Thermal drying is a process of accelerated
evaporation.  Unless the dry product can be kept below its critical

-------
                            7.13.12

ignition temperature of 130 to 150°F, fires will result in transit
from spontaneous combustion.  Coal dryers all use direct heat transfer
where the combustion gases plus tempering incoming air come in direct
contact with the material.

Five principal methods for drying coal used in the United States
include :^
•   Rotary dryers
•   Screen type dryers
•   Cascade dryers
•   Suspension type dryers
•   Fluid bed dryers

a.  Rotary Dryers
    The rotary dryers resemble kilns and may be parallel or counterflow
    (air and coal), single or double shell and louvre types.  These are
    the older kind and better known to the trade.  These cylindrical drums
    are pitched longitudinally about 3/8 inch per foot, causing the
    material to travel slowly from the feed to the discharge end.  The
    drums may be 8 to 10 feet in diameter and 65 to 80 feet long.
    Lifting vanes drop the coal through the hot gases.  The inner shell
    of  the double shell type carries the hot gases to the discharge end
    of  the dryer where they turn and reverse their direction in direct
    contact with the counter flow of the solids.

b .   Screen Type Dryers
    The  screen  type dryers  carry  the  coal on reciprocating  screens which
    accomplish  evaporation  by passing hot gases  through  the  bed.   These
    can  be  down-draft or up-draft;  the down-draft  type affords  the
    opportunity of some mechanical  drainage.   These  are  designed
    for  coal with  top sizes up  to 2 inches  and a bottom  size of  1/2  mm.
    On one  model,  an  induced draft  fan draws the hot  gases  down through

-------
                               7.13.13
    the screen decks and the flow is automatically alternated so as to
    transfer the suction from the first to the second screen sections
    every second.   This arrangement causes the full force of the gas
    pressure to squeeze the bed, thus accelerating mechanical drainage

c.   Cascade Dryers
    Cascade dryers (Figure 7.13.10) accomplish their heat transfer by
    introducing hot gases through louvers which are arranged to cause
    the coal to cascade.  The coal forms a curtain of flowing coal and
    hot gases are passed through it to impart heat for evaporation.
    This type is most widely used for fine coal (3/8 x 0) but coals up
    to 1-1/2 x 0 have been dried successfully.
  Figure 7.13.10 not available for this publication.

-------
                                7.13.14
d.  Suspension Type Dryers
    Suspension-type systems (Figure 7.13.11)  introduce the wet coal
    into a moving hot stream of gases which pneumatically convey and dry
    the material in transit to the dust collector where the coal is
    separated from the moisture-laden spent gases.  This class of dryers
    is ideal for extremely fine coal with the top size not over 3/8 inch.
                                         1
                                          10 AIMOttHtll CK
  Figure 7.13.11.   SUSPENSION-TYPE  FLUSH DRYING SYSTEM (THERMAL DRYER)
                     (SOURCE:  RAYMOND DIVISION, COMBUSTION ENGINEERING,
                               CHICAGO, ILLINOIS)

-------
                                7.13.15

e.   Fluid Bed Dryers
    In fluidized bed dryers (Figure 7.13.12)  the wet coal is fed onto
    a perforated or bar type retention plate  where hot gases are blown
    or drawn through the bed.   Fluidized beds are characterized  by a
    loose pulsating mass which is kept porous by the action of  the gas
    stream.
                  -—~
                 Figure 7.13.12.   McNALLY FLOWDRYER
                    (SOURCE:  McNally, Reference 3)
    The air pollution control problem from coal drying  does  not  differ  from
    most drying operations where  the hot products  of  combustion  pass
    through wet material which contain fine particles of  product.
    Coal is the primary fuel used to produce the hot  gases which evaporate
    the moisture from the product (see Chapter 6,  Section II).   Fuel  oil

-------
                                7.13.16


    is  used  at some installations especially during startup operations.
    Primary  dust collectors are  cyclones followed by wet collectors and
    demisters.  Conventional scrubbers have not proven effective on thermal
    dryers but high energy venturi scrubbers with demisters have reduced  the
    grain loading in several installations from a high of 5.5 grains per
    standard cubic foot to 0.04  grains per standard cubic foot.     Bag-
    houses are not used in these systems because of fire hazards.
4.   Refuse
    Coal refuse piles are a constant  source  of  combustion and dust related
    air pollution control problems.   Some of these piles  cover acres of
    ground and contain hundreds  of  tons  of material.   Spontaneous
    combustion, carelessness or  deliberate action are the general causes
    of refuse pile fires.  Often trash not resulting  from coal preparation
    contributes to the potential fire hazard at the refuse dump site.   A
    survey made in 1964    indicates  that there are approximately 500
    burning piles in 15 states;  approximately 150 in  Pennsylvania and 200
    in West Virginia.  Emissions, in  addition to blowing  dust from the
    piles are H S, S0_ and smoke.  Other noxious gases which result from
    burning piles include CO, ammonia and carbon disulfide.

    Air pollution control and safety  measures include proper construction
    of the pile by compaction and sealing to prevent  air  circulation and
    ignition.  Some methods of controlling a burning  coal refuse dump
    are:(1)
    a.  Digging out the fire or  isolating the fire area by trenching.
    b.  Pumping water onto the fire areas and immediate vicinity.
    c.  Applying a blanket or cover of incombustible  material such as
        limestone dust, shale dust, or slag  dust over the fire area.

-------
                                    7.13.17
        d.  Injecting a slurry of rock dust or other incombustible material
            into the fire area through drill holes.   Grouting with cement is
            also practiced.
        e.  Spraying water over the area.

    5.  Coal Storage
        Coal is stored in huge open piles  and in silos or underground
        facilities.  As in refuse storage  there are  two primary air pollution
        control problems, blowing dust and combustion products.  Anthracite
        coal is very safe to store in large piles.   These piles should be
                                                                      (2)
        capped with larger sizes to prevent loss of  fines due to wind.
        Bituminous coal should be packed and sealed  as a fire prevention
        technique.  Promising tests have been made using water soluble
        organic polymer as a spray on outdoor piles  of crushed coal to form a
        hard surface to reduce wind blown  dust.  Test piles have withstood
        winds as high as 60 MPH and numerous freeze  thaw cycles.

C.  EMISSIONS AND CONTROLS
    The largest single source of dust, smoke and particulates in coal
    preparation plants are the thermal dryers.   Dust loading of the effluent
    from a dryer operating at 150°F,  180 to 120,000 cfm with the feed 1/4"
    centrifugal coal and filter coke, can be in excess of 2.5 grains per  cubic
    foot with a particle size distribution of:
            0 to  2M         55% by weight
            2 to  5M         33% by weight
            5 to 10M         11% by weight
           10 +M              1% by weight
    Cyclone separators can eliminate high percentages of the larger particle
    sizes and serve as the first stage in a particulate recovery train.   Dark

-------
                                    7.13.18
    brown emissions of 100% opacity are visible from plants using cyclones
    and low resistance scrubbers.   Effective emission reduction from thermal
    drying requires, in addition to cyclones, pack towers or venturi scrubbers
    with demisters.

D.  INSPECTION POINTS
    1.  Screening,  Crushing and Breaking
        Fines escaping from ventilation systems  serving the equipment from these
        processes constitute a major air pollution control problem.   The inspector
        can readily determine the effectiveness  of sprays to suppress dust
        and hooding and local exhaust systems to pick up the dust generated.
        Exhaust systems and cyclones can become  plugged by caking of fine
        coal which will add to the system back pressure thus reducing hood
        indraft velocity and reducing the cyclone collection efficiency.

    2.  Conveyors and Elevators
        Long open conveyor belts carrying dry material or appreciable
        quantities of fines can be a significant source of dust.   All drop
        points onto or off of open belt conveyors should be evaluated for
        dust emissions.  Special attention should be paid to railroad car
        loading and dry coal storage activities.

    3.  Pneumatic Classifying and Dedusting
        These processes use high velocity air streams which entrain sizeable
        quantities of fines which are collected  by cyclones and a baghouse
        in series.   An increase in resistance to flow caused by plugging the
        exhaust lines and dust collectors will cause a decrease in pickup from
        the ventilation system resulting in dust emissions or poor pickup
        of dust at the source.  Since the material collected is a useable
        product the operator will make certain that the dust control equipment
        is properly maintained.

-------
                                     7.13.19
    4.  Thermal Drying
        In order to determine the effectiveness of air pollution control
        equipment on thermal dryers, stack tests should be required.  The
        inspector can determine if fine material, e.g., 48 mesh, is being used
        as furnace fuel which experience has shown contributes to the particulate
        emissions.  Because of this, some operators intend to go to oil-fired
        furnaces full time.

E.  ENVIRONMENTAL OBSERVATIONS
    Dust and particulate matter will be found in areas adjacent  to  coal
    preparation plants  when rigid air pollution control programs are not
    mandatory.   Meteorological conditions will determine how far and in what
    direction fine dust particles will travel.  If burning refuse is a
    problem, the probability of odor complaints will be high.

    The inspector should determine the direction of the prevailing  wind so
    that he may station himself properly to make readings from the  dryer
    exhaust stacks.   This will also help to establish a gross dust  fallout
    pattern and a probable pattern for nuisance complaints.   One method
    of making these determinations is to place dust fall jars at the plant
    property lines.   In-plant observations should focus on housekeeping since
    there usually is an abundance of fine coal particles which can  be disturbed
    and become  air borne by the large volume of truck traffic in and out of
    the plant.

-------
                                    7.13.20
                                  REFERENCES


1.  Sussman,  V.  H.   Nonmetallic  Mineral  Products  Industries.   In:  Air Pollution,
    Vol. Ill, A. C.  Stern (ed.).   New  York City,  Academic  Press,  1968.

2.  Steam its Generation and  Use.   The Babcock  and Wilcox  Co.,  37th  Edition.

3.  Coal Preparation Manual.  McNally  Pittsburg Mfg.  Corp.,  #570.

4.  Spicer,  T.  S.   Thermal Drying  Enhances Coal Value.   Coal Utilization.
    Aug. 1958.

5.  Journal  of Environmental  Health.   Vol.  33,  No. 4.  March and April,  1971.
    p.  523.

6.  Gleason,  T.   Wet Scrubbing of  Coal Dust from  Thermal Dryers with Peabody
    Scrubber.  Transactions.  Society  of Mining Engineers.  March  1963.

-------
                                     7.14.1
                           XIV.   FERTILIZER INDUSTRY

A.  NATURE OF SOURCE PROBLEM
    For the purposes of this chapter we will define the fertilizer industry as
    being limited to the chemical fertilizers.   Only very limited amounts of
    fertilizer are derived from natural waste products at the present time in
    the United States and most of this originates from activated sludge plants
    operated in connection with municipal sanitary sewage treatment plants.

    The practice of using fertilizers dates back to antiquity.   As early as
    200 B.C. the Carthaginians were said to have used bird dung on soil as a
    source of phosphatic materials.  '   Over the centuries replenishment in the
    soil of this essential element was aided by the use of bones, fish and bat
    and sea bird guano.  In the nineteenth century a number of  individuals
    experimented with methods increasing the solubility of the  phosphate sources
    and in 1842 a British patent was issued to John B. Lowes on the process of
    treating bone ash with sulfuric acid.

    The other two major constituents of fertilizers—nitrogen and potash—were
    also first used as natural waste products.   Nitrogen sources included oil
    seed meals, fish by-products, tankage, and dried blood.  Since the advent
    of chemical fertilizers these natural materials are more valuable as direct
    animal feed supplements.  Potash was probably first utilized in the form of
    wood ash.

    Present day compounds used as sources of phosphates, nitrogen, and potash
    result from the processing of minerals or from direct chemical synthesis.
    These manufacturing processes can produce a variety of gaseous and particu-
    late air contaminants generally associated with the chemical fertilizer
    industry.

-------
                                 7.14.2
Two major sub-groupings of the chemical fertilizer industry are of particu-
lar importance as air pollutant sources and will be considered in more
detail in this chapter.  These are (1) the phosphatic compounds produced
from phosphate rock and (2) ammonium nitrate produced by the reaction of
ammonia with nitric acid.

1.  Phosphate Fertilizers
    The air pollutants emanating from the phosphate fertilizer industry are
    of two distinct classes:  the first being particulates originating from
    the crushing, grinding, drying, and bulk handling of rock ore, benefici-
    ated rock and product materials;  the second being gaseous contaminants
    evolved during the acidulation and curing of phosphate rock to produce
    phosphoric acid, superphosphate and triple superphosphate.  Other
    gaseous compounds may be released from the secondary treatment of super-
    phosphates such as in the combined ammoniating and granulation operation.

    While the particulate losses may result in visible plumes and settleable
    dusts, the principal air pollution problem associated with the phosphate
    fertilizer industry is that related to the evolution of gaseous fluorine
    compounds during the acidulation of phosphate rock.  As will' be described
    in more detail later, fluorine compounds are also present in most phos-
    phate bearing mineral formations used commercially.  The gaseous com-
    pounds thought to be most predominant in the reaction products of the
    acidulation process are hydrogen fluoride (HF) and silicon tetrafluoride
    (SiF4).

    These gaseous fluoride compounds damage citrus, gladioli and truck
                                                               ( 2}
    crops, and can deposit fluorine compounds on cattle forage.     Should
    cattle ingest excessive quantities of fluorides from this feed source,
    they may develop tooth mottling and decay (fluorosis), skeletal defects
    such as lameness (exotosis), loss of appetite and emaciation.

-------
                                    7.14.3
        Gaseous sulfur oxides and nitrogen oxides may also be lost from phos-
        phate fertilizer processes particularly during the use of sulfuric and
        nitric acids where there is a significant organic content to the
        material being treated.   Ammonia and ammonium chloride may also be
                                                                (3)
        evolved during the ammoniation of phosphate fertilizers.

    2.  Ammonium Nitrate
        The possible air contaminants arising from the manufacture of ammonium
        nitrate from the reaction between ammonia and nitric acid are:   ammonia,
        nitric oxide, and ammonium nitrate fume and dust.  The principle problem
        has been the objectionable haze formed as the result of water condensing
        on finely divided ammonium nitrate fume lost during prilling operations
        (production of pellets by counter-current flow of air against falling
        spray of molten ammonium nitrate).

                        (4)
        Payne and Glikin    state that at relative humidities above 60% at a
        temperature of 30°C water will condense on ammonium nitrate nuclei,
        causing a growth in particle size so as to result in a visible  haze.
        Scorer    has also evaluated the environmental impact of a proposed
        British ammonium nitrate plant and predicted a fallout rate of  400
               2
        tons/mi /mo within 2/3 mile of the prilling operation.
B.  PRODUCTS DESCRIPTION
    1.   Phosphate Fertilizers
        The various types of phosphate fertilizers are produced commercially
        from mineral deposits of phosphate rock.   Although major deposits are
        found at numerous locations throughout the world a significant propor-
        tion of commercially recoverable rock is  found in the United States.
        At the present time the world's center of phosphate production lies in
              2                         (2  3)
        500 mi  area of central Florida.   '      The deposits are of the sedi-
        mentary pebble type and largely consist of phosphate in the form of

-------
                             7.14.4
fluorapatite—3 [Ca (PO )  ]  •  CaF2<   This form of phosphate is rather
insoluble, thus accounting for the stability of the deposits.

Commercial deposits of phosphate rock are also found in Tennessee,
North Carolina, Idaho, Montana,  Wyoming and Utah.     These deposits
are also of the sedimentary  type,  but vary in depth, phosphorous assay,
and amount of organic content.

Phosphate rock is usually  mined  using open strip-mining techniques, with
the rock being sluiced into  pipes  carrying the rock slurry to beneficia-
tion plants.  Here the ore is  upgraded by separating undesired sand,
clay and other non-phosphate minerals by a variety of physical and
flotation processes.  Up to  this point, the air pollution problems are
minor in nature.

The beneficiated rock must be  dried  and pulverized before further treat-
ment.  These operations may  result in major atmospheric losses of dust
unless adequate controls are used.  In some cases calcination is used
to reduce the content of organic mattei
largely outside of the Florida region.
to reduce the content  of  organic matter.      This  applies  to deposits
Phosphate in the form of fluorapatite is very insoluble, thus reducing
its availability to the soil if used directly.  The success of the
phosphate fertilizer industry depended upon the development of technology
to produce a form of readily available phosphate.   That process which has
been longest in use is that which involves the acidulation of phosphate
rock (fluorapatite) with sulfuric acid to produce normal superphosphate
(acid phosphate).   This process in one form or another has been in use

-------
                             7.14.5
for over a century.  The simplified reaction involved is shown below:
                                                          +2HF
The hydrogen fluoride evolved may react with silica present to form
silicon tetrafluoride:
          4HF+SiO. -»- SiF.+2H00
                 2        42

Fluosilicic acid may also be formed as a result of reactions with
water:
          3SiF.+4H_0-^2HnSiF.+Si(OH).
              42      26       4

A great deal has been written about these reactions and there is not
                                                            (1  3)
total agreement about them or the order in which they occur.  '
However, it is a fact that gaseous fluorine compounds are emitted as a
result of the acidulation process, thus giving rise to a significant air
pollution problem.  Figure 7.14.1 shows a simplified flow sheet  for the
production of normal superphosphate.

Depending upon the specific process, the reactions in the acidulation
step do not take place immediately, but are completed in the curing
operation which may take a number of weeks or months.  During the
curing operation, fluorine compounds continue to be evolved and in the
past have not been usually controlled.  In fact, in a study conducted by
Cross and Ross   , fluoride emissions \
quantities from gypsum settling ponds.
Cross and Ross   , fluoride emissions were shown to arise in significant
Under the stimulus of the demand for more concentrated forms of ferti-
lizer, a process for,the acidulation of phosphate rock with phosphoric
acid was developed.  This process results in a product known as triple

-------
                        7.14.6
Figure 7.14.1  PRODUCTION OF NORMAL SUPERPHOSPHATE
               (SOURCE:   HELLER,  etal.,  Reference 6)

-------
                             7.14.7
superphosphate.  The assay for available phosphorous is about 2-1/2
times that of normal superphosphate because the active ingredient is
not admixed with calcium sulfate.  This process is shown in Figure
7.14.2.  Many of the air pollution problems in the manufacture of triple
superphosphate are very similar to those of normal superphosphate pro-
duction, including the evolution of gaseous fluorides.

Although not discussed in this chapter the integrated production of
sulfuric acid and phosphoric acid (particularly by the wet process) are
unalterably bound up with the phosphate fertilizer industry.  Sulfuric
acid manufacturing is, however, discussed in Section VII and the wet
process for the production of phosphoric acid essentially involves the
more complete acidulation of phosphate rock with sulfuric acid with the
accompanying filtration of calcium sulfate from the phosphoric acid
formed.

A variety of product mixes are prepared following the actual production
of superphosphate or triple superphosphate.  In many cases the super-
phosphate is sold as "run of the pile" (as it will not attempt to meet
a guaranteed assay) or is ground and bogged to specifications.  Increas-
ingly, however, granulated product is produced which sometimes has been
ammoniated or had other forms of nitrogen, such as urea, added.   The
granulation processes involve the use of other mixing and drying steps
thus increasing the opportunity for dust and fume production.  On the
other hand, if combined ammoniation is used, the acidulation reaction
is terminated and gaseous fluoride emissions are not evolved after the
acidulation process itself.  On the other hand, ammonia and ammonium
chloride may be lost from the ammoniation process.

-------
                              7.14.8
                                             [AMMONIA.FLUORIDE AND PAHTICULATE)
PHOSPHORIC ACID
                                                   EXIT
                                          PflRTICUt-ATE,FL(JOR!DEjWD SULFUR OXIDE

                                                          (PflRTICULATE)
PHOSPHATE ROCK
   Figure  7.14.2   PHOSPHORIC ACID ACIDULATION PROCESS
                      (SOURCE:   HELLER,  etal.,  Reference  6)

-------
                                 7.14.9
2.  Ammonium Nitrate
    This important source of nitrogen in fertilizer is produced by the
    reaction between ammonia and nitric acid to form ammonium nitrate in
    solution:
              NH.+HNO,-*-NH.NO,
                33     43

    After concentration of this solution by heating and evaporation,  solid
    ammonium nitrate is produced by "prilling," or vacuum crystallization.
    Another process known as the Stengel process mixes preheated ammonia
    and nitric acid in a packed reactor where the heat of reaction is
    sufficient to vaporize the water in nitric acid feed, thus directly
    producing molten ammonium nitrate which is separated from the unreacted
    materials and water vapor by a centrifugal separator.  This molten
    nitrate is ultimately distributed on an endless stainless steel water
    cooled belt where it solidifies.  Vapors from the separator are recov-
    ered by condensation and scrubbing.

    The "prilling" process is the more common in the United States and is
    shown in Figure 7.14.3.  As mentioned earlier, the prilling process
    involves the spraying of concentrated ammonium nitrate solution down
    through the top of a tower through a rising stream of air.  The droplets
    solidify and harden during their fall resulting in spherical pellets
    called prills which may be bagged after drying futher on a conveyor to
    less than 0.5% moisture.  Product in this form may be kept in moisture
    proof bags for more than a year without caking.

    The loss of fines in this process is very low but some ammonium nitrate
    fume may be discharged.  If ammonia is added in excess, the possibility
    of nitric oxide loss is nearly eliminated and the ammonia may be recov-
    ered by scrubbing.

-------
                          Nitrogen Oxides, NH.NO ,  NH
  Ammonia
Nitric Acid
                   Neutralizer
Evaporator
                                                                           Off Gases
                                                                                            Water
                                                                     Scrubber
                                                                                     •Air
                                                                           Product Ammonium Nitrate
                                                                  Prilling Tower
                  Figure 7.14.3  FLOW DIAGRAM FOR THE MANUFACTURE OF AMMONIUM NITRATE

-------
                                 7.14.11
    The damages of fire or explosion can exist with ammonium nitrate so
    that great care must be taken in bulk handling.  One approach has been
    the use of urea as an admixture to inhibit oxidation of ammonium
            (4)
    nitrate.      Urea has been increasingly utilized by itself or as urea-
    forms as a fertilizer substance.  Ureaforms are reaction products of
    urea and formaldehyde which release nitrogen very slowly.

3.   Control Methods
    The control of emissions from chemical fertilizer production basically
    involves the control of soluble gases, principally fluorine compounds,
    and finely divided particulate matter.  Fluorine compounds are usually
    removed by water scrubbers which have been stated to range in efficiency
    from 92-97%.  This scrubber water may go to waste or be reclaimed for
    value of the fluorine contained.  This latter approach is  increasingly
    being used.

    Particulate matter may be recovered by cyclones, cloth filters and high
    efficiency scrubbers.  Because of great numbers of possible emission
    points from both phosphate and ammonium nitrate production, Table 7.14.1
    has been prepared which lists emission sources, types of emissions,  and
    possible means of control.

    In general, a number of principles should be applied when  considering
    control approaches for fertilizer plants.  For the proper  control of
    dusts, all conveyors, feeders, hoppers, bins, and size reduction
    equipment should be closed and properly vented to the dust abatement
    equipment.   Adequate ventilation velocities should be based upon
    accurate knowledge of the particulate size distribution involved.

    Gaseous fluoride emissions should be collected properly and a determina-
    tion made of all possible emission points.   Where curing operations  are

-------
               Table 7.14.1  CONTROL OF EMISSIONS FROM FERTILIZER MANUFACTURING
           Source
Nature of Emissions
     Control Method(s)
Phosphate Fertilizers

   Rock Drying

   Rock Crushing and Grinding

   Acidulation

   Curing (denning)

   Granulation


   Ammoniation



   Nitric Acid Acidulation

   Superphosphate Storage and
     Shipping

Ammonium Nitrate

   Reactor

   Prilling Tower
Rock Dust

Rock Dust

HF, SiF

HF, SiF

Product Dust
NH NH Cl,SiF ,HF
NO , Gaseous F Cpds.

Product Dust
NHn, NO
  3    x
NH4NO  Fume
Cyclones and Wet Scrubber

Baghouses

Water Scrubber

Water Scrubber

Cyclones and Wet Scrubbers
  or Cloth Filters

Cyclone, Elect. Precip.,
  Cloth Filters, Highest
  Scrubber

Scrubbers, Addition of Urea

Cyclones, Cloth Filters
Scrubbers

Reduce Formation by Control
  of Conditions

-------
                                     7.14.13
        used,  they should be conducted inside enclosures through which air can
        be recirculated and passed through a scrubber.   Consideration should be
        given to the reduction of losses from gypsum ponds.
C.   INSPECTION POINTS
        General
        The chemical fertilizer industry has been shown to be a variety of
        separate industries ranging greatly in complexity, types of  operations,
        and nature of potential environmental impact.   A "fertilizer plant1'  may
        range from one engaged in the relatively simple process of blending  and
        packaging bulk dry ingredients to a large scale integrated operation
        involved in mining raw materials; crushing,  grinding,  and drying these
        materials; conduct of chemical processing;  and finally blending and
        packaging of finished product.

        Because of the seasonal demand for fertilizer, plant operation often
        follows a similar cyclic pattern with maximum production just prior  to
        peak demand.  Nearly every type of air pollution control equipment may
        be found in use in the fertilizer industry,  ranging from inertial
        collectors through fabric filters, water scrubbers and electric precipi-
        tators.

        The factors listed above require a varied approach to the overall field  in-
        spection and abatement operations.  In relatively simple cases, straight-
        forward inspection procedures involving primarily an inspection of the
        source premises may be adequate.  In the case of very large  integrated
        plants where there are potential toxic emissions a team approach may be
        desirable.  In addition to the regular field abatement personnel
        specialists in chemistry, process and control engineers, meteorologists,
        and plant and animal scientists may be called upon.

-------
                                 7.14.14
2.   Environmental Surveillance
    The most significant efforts  in environmental surveillance will be con-
    cerned with the phosphate fertilizer industry as a result of the poten-
    tial for the emission of gaseous fluoride compounds and in some cases
    sulfur dioxide, hydrogen sulfide,  and nitrogen oxides.   Other candidates
    for special surveillance activities  would include the evaluation of the
    deposition of particulates from many of  the fertilizer  processes, and
    plume formation from ammonium nitrate plants.

    In the case of fluoride emissions  from phosphate fertilizer production
    two types of surveillance activities may be employed.   The first involves
    the determination of possible damage to  susceptible receptors, i.e..,
    citrus, row crops, ornamentals and grazing animals (through fluorides
    deposited on forage).   This type of  activity will require extensive
    training of field personnel and the  cooperation of land users sustaining
    damage at the minimum.   Desirably, other resource individuals such as
    farm advisors, veterinarians, and  university personnel  will be utilized
                                                                         (2)
    as well.  Techniques such as  this  have been described by Hendrickson.

    Environmental surveillance may also  be conducted by sampling for sus-
    pected emissions in the ambient atmosphere.   Most surveys for atmospheric
    fluorides have been conducted by the use of static sampling utilizing
    lime or calcium formate impregnated  papers,  but continuous analyzers have
                      (2  7)
    been used as well.  '

3.   Plant Inspection
    a.  Interview
        As in the case of any complex  pollution source, the interview of
        plant management should include  the  obtaining or verification of
        process descriptions, flow sheets, equipment lists  and management's

-------
                             7.14.15
    estimate of emission inventories.   Information on process variations
    and production scheduling should be obtained.   Should source test
    data be available it should be secured and examined.   Statements
    from plant management on plant operations, their assessment of
    pollution problems and plans for control should be requested.

b.  Physical Inspection
    The inspector should obtain and/or verify the plant layout and equip-
    ment location.  He should observe each process step.   Several  visits
    may be necessary before a representative set of operating conditions,
    production rates and meteorological conditions have been covered.
    In the case where much process and control equipment is used in the
    fertilizer industry, corrosion, erosion and other forms of mechan-
    ical wear and tear are a major problem.  It will be important, there-
    fore, to make careful observations as to the condition and maintenance
    level for important items of equipment.

    Another significant factor in terms of overall emission rates  from
    a plant, process or operation is the effectiveness of emission
    pickup and retention in the exhaust and control system.  This  is
    especially important to examine in the fertilizer industry where so
    much bulk transfer of material in particulate or granulated form
    takes place.

    The inspector should determine what design factors are used for
    control equipment such as volumetric flow rates, entrance velocities
    to centrifugal collectors, water flow rates for scrubbers, pressure
    drop across scrubbers, etc.  Adherence to design rates should  be
    evaluated.  Secondary sources of pollution such as waste water
    treatment facilities, settling ponds and fluoride recovery systems
    should be examined.

-------
                        7.14.16
An increasing use of process control instrumentation in the
fertilizer industry provides another potential source of informa-
tion useful to inspection personnel.  Of particular importance
would be any instrumentation used to control feed rates and that
used to monitor effluents.

-------
                                    7.14.17
                                  REFERENCES


1.  Waggaman,  W.  H.   Phosphoric Acid,  Phosphates,  and Phosphatic  Fertilizers,
    second ed. New  York,  Reinhold Publishing Corp.,  1952.

2.  Hendrickson,  E.  R.   Dispersion and Effects of  Air Borne  Fluorides  in
    Central Florida. Air  Pollution Control Assoc.,  11.   pp.  220-5,  232.
    May,  1961.

3.  Savchelli, V. (ed.).  Chemistry and Technology of Fertilizers.   New York,
    Reinhold Publishing Corp.,  1960.

4.  Payne, A.  J.  and P.  G. Glikin.  Ammonium  Nitrate - Process  Survey.
    Chem. & Proc. Eng.   49.   April, 1968.   pp. 65-9.

5.  Scorer, R. S. Air  Pollution Problems  at  a Proposed  Merseyside Chemical
    Fertilizer Plant:   A Case Study.   Atmos.  Env., 2.  January, 1968.  pp. 35-48

6.  Heller, A. N., S. T. Cuffe, and D. R.  Goodwin.  Inorganic Chemical
    Industry.   In:  Air Pollution, Vol. Ill,  A.  C. Stern (ed.).   New York City,
    Academic Press.   1968.

7.  Cross, Jr., F. L.,  and R. W.  Ross.  New Developments in  Fluoride Emissions
    from Phosphate Processing Plants.   J.  Air Pollution  Control Assoc., 19,
    January, 1969.  pp.  15-17.

8.  English, M.  Fluorine  Recovery from Phosphatic Fertilizer Manufacture.
    Chem. & Proc. Eng.,  48:43-7.   December, 1967.

-------
                                   7.15.1
                   XV.  PAINT AND VARNISH MANUFACTURING

A.  NATURE OF SOURCE PROBLEM
    The paint and varnish manufacturing industry in a fairly broad context
    could be said to include synthetic resin manufacturing, varnish cooking,
    and paint blending processes.  Of these, the first two present the
    greatest air pollution control problems.

    The major air pollutants from synthetic resin manufacturing would include
    emissions of monomers and other raw materials from storage and reaction
    vessels, sublimed phthalic anhydride and oil bodying odors from
    alkyd resin manufacturing, and possible solvent losses during thinning
    operations and storage of thinned resins.

    Varnish cooking presents the greater of the air pollution problems in
    this industry because of the wide variety of odorous substances released
    during the polymerization and other chemical reactions that the natural
    drying oils enter into during the cooking process.  These range from
    acrolein and other partially oxidized organic compounds to sulfur
    derivatives, some of which are detectable in the parts per billion range.
    Some varnish cooking is still carried out in open vessels which complicates
    the design and operation of control equipment.

    Solvent losses may also occur in the thinning of varnish and in paint
    blending operations.

B.  PROCESS DESCRIPTION
    Two of the principal ingredients in protective coatings are resins and
    drying oils.  When organic solvents and driers (soaps of heavy metals)
    are added to the heat processed blend of the resin and oil the product
    is known as varnish.  The addition of pigments to varnish results in
    enamel type paints.   The manufacture of water-based paints bears little

-------
                               7.15.2
relationship to oil-based paints and varnishes from an air pollution point
of view and will not be considered here.   The resins used in water-based
paints are usually produced in chemical process plants using continuous
processes.

Resins used in varnish production may be either natural or synthetic.
Natural resins include Rosin,  Congo, Batu,  Dammar and Lac.  These natural
resins in dry form are added at some point during the heat processing of
natural drying oils known as varnish cooking.  Oleoresinous (oil plus
resin) varnishes result.  This process will be described later in this
section.

A number of synthetic resins are also used in the preparation of
protective surface coatings.  A partial list would include modified
phenolic, alkyd, coal tar, urethane and petroleum-based resins.  Most of
these are produced in closed reaction vessels and are more properly
considered under the chemical process industries.  However, the alkyd
resins are sufficiently different and are in such widespread use as to
justify a description of the manufacturing process.

1.  Alkyd Resin Manufacturing
    Alkyd resins are a special class of polyesters modified by additions
    of fatty, monobasic acids.  As a general class a polyester resin is
    defined as the product of a condensation reaction between a polyhydric
    alcohol and a polybasic acid.  Thus, an alkyd resin might contain as
    base ingredients phthalic anhydride, glycerol and a fatty acid
    formed from a natural oil such as linseed.

    Other natural oils used as modifiers include cottonseed, soya, tung,
    and sometimes, fish oil.  Other base ingredients used include maleic
    and formic acids, and alcohols such as ethylene glycol, mannitol,
    pentaerythritol and sorbitol.

-------
                                7.15 . 3
    The production of alkyd resins is usually carried out in an enclosed,
    indirectly heated reaction vessel equipped with a stirring mechanism,
    a condenser, and usually a scrubber.   All ingredients may be cooked
    simultaneously, or the oil and a portion of the alcohol component
    (such as glycerol) may be added first to convert the naturally
    occurring triglycerides in the oil to a more reactive monoglyceride
    form.  The resin is formed by reacting this monoglyceride with the
    acid (such as phthalic anhydride) at a temperature slightly below
    500°F,  using agitation and sparging with inert gas.   The reaction is
    carried out until the desired viscosity is attained.

    Because of the use of natural drying oils as modifiers, a variety of
    odorous, noncondensible gases are given off during alkyd resin
    manufacturing which are similar to those emitted from the production
    of oleoresinous varnishes.  These include acrolein,  other aldehydes,
    fatty acids, etc.  This class of air contaminants is  generally
    controlled by fume burners.  Addition of phthalic anhydride to the
    heated drying oils may cause the emission of visible plumes of the
    sub1imed anhyd ride.

2.  Varnish Cooking
    Varnish cooking generally refers to the manufacture of oleoresinous
    varnishes.  Four groups of materials are used in preparation of the
    final form used for protective or decorative coating.  These include
    antioxidants, resins, drying oils, driers, and solvents.   While there
    is a good deal of variety in all four groups, an almost endless number
    of resins and drying oils are used.   To a considerable extent the nature
    of these materials influences the possible air pollution problem.

-------
                           7.15.4
The principal reactions taking place in the manufacture of varnish
involve the addition of heat.   Reactions include:
a.  Polymerization of the drying oils.  Some, such as tung oil, are
    easily polymerized and are added early in the processing while
    with a slower bodying (polymerizing)  oil such as linseed oil
    a certain amount of prebodying may be carried out before the
    resin is added.

b.  Depolymerization.  Certain natural fossil resins are of such high
    molecular weight that heat-assisted cracking (depolymerization)
    is necessary before the resin is ready soluble in the oil.

c.  Melting and solution.

d.  Esterification.  Natural rosin or tall is modified for use in
    some varnishes by esterification with a polyhydic alcohol such as
    glycerol or pentaerythritol.   The product, ester gum, is almost
    always used in conjunction with other resins.

e.  Gas checking.  Certain of  the faster reacting conjugated oils,  such as
    Chinawood oil, tend to form crystalline films giving a frosted or
    "gas checked" effect.  This effect can usually be prevented by
    heating to top temperatures of 575-585°F during the cooking.

f.  Distillation and Evaporation.  Used to remove volatile constituents,
    particularly such as those present or formed during esterification
    of tall oil or rosin.

The air pollution problem in oleoresinous varnish cooking largely is
a result of the breakdown products of resin depolymerization, the
thermal decomposition and oxidation products of oil bodying, the

-------
                            7.15.5
volatile portion of the raw materials, and the by-products of gum
running (esterification).  These might include fatty acids, formic
acids, acetic acid, glycerine, acrolein, other aldehydes, phenols, and
terpenes.*- '  In the case of tall  oil esterification, hydrogen sulfide,
alkyl sulfide, butyl mercaptan, and thiophene may also be emitted.
These sulfur compounds are present in unpurified tall oil as a result
of the sulfides used in the kraft wood pulping process from which the
tall oil by-product is produced.

A significant amount of solvent may be lost to the atmosphere if
added to hot cooked varnishes where proper solvent recovery equipment
or controls are not used.  This is most likely when the solvent
cut-back or thinning operation takes place in open varnish kettles.

The type of vessel used for varnish cooking can have a significant
effect on the air pollution problem.  The old, open movable kettle
(Figure 7.15.1) having a capacity ranging from about 150 to 500 gallons
is heated over a fire pit making close temperature control somewhat
          (2)
difficult.     Because odorous fume evolution is temperature dependent,
excessive temperatures or local hot spots can increase fume loss and
even change the nature of the effluent.  Further, the installation of
a close fitting effective fume hood and at the same time allowing the
flexibility necessary for use over a movable kettle is more difficult
than hooding a fixed fume source.

Much of the varnish cooking is now carried out by chemical companies
and large paint plants in closed reactor kettles having an external
                                                                   (3)
source of heat supplied by a heat transfer medium such as Dowtherm.
Some are directly heated with gas, oil or electric resistance heaters.
Internal cooling coils may also be provided.  Temperature can be con-
trolled much more closely than in open kettles.  Liquid raw materials
are pumped with solids being added through a scalable port.  These
closed systems are often equipped with vapor recovery condensers.  The

-------
Figure 7.15.1.  UNCONTROLLED OPEN KETTLE FOR VARNISH COOKING (SOURCE:
                AIR POLLUTION ENGINEERING MANUAL,  Reference 4)

-------
                            7.15.7
product is withdrawn by pumping and is transferred to solvent thinning
tanks usually equipped with agitators and integral reflux condensers
to reduce solvent losses.

Solvent loss control has become of more concern since the adoption of
regulations such as Rule 66 of the Los Angeles County Air Pollution
Control District and Regulation 3 of the Bay Area Air Pollution Control
District (California).   From the standpoint of total volume and
photochemical air pollution potential, the control of certain types
of solvents such as olefins, branched chain aromatics and ketones may
be of more importance in the general air pollution picture than is
the control of varnish cooking fumes.  However, the localized nuisance
and visible plume aspect of varnish cooking fumes cannot be neglected.

Air Pollution Control Techniques
The application of the best technology in the paint and varnish
industry would call for the use of fume burners wherever varnishes
are cooked or drying oils are heat processed.  In some cases pre-
collection devices such as water scrubbers for the control of
phthalic anhydride fumes are in order.  Generally speaking, other
means of control such as activated carbon adsorption units are not
satisfactory for use with odorous fumes containing tacky particulate
matter such as is contained in typical varnish cooking fume.

Solvents may be controlled by use of closed thinning vessels,
temperature control, condensers, and in some cases, fume burners.

Fume or afterburners should be designed to accomplish three objectives:
(1) eliminate visible plumes, (2) eliminate odor, and (3) oxidize
all organic substances to carbon dioxide and water.

-------
                            7.15.8
These objectives can only be met by good mixing of the plume in
the combustion zone, application of sufficient heat to reach some
acceptable minimum temperature, and provision of sufficient
residence time at these conditions to permit quantitative oxidation
of the organic material in the fume.     Both direct flame and
catalytic afterburners have been applied to varnish cooking operations.

In general, sufficient auxiliary fuel (usually gas) must be supplied
in direct flame afterburners to heat the exhaust air containing the
process effluent to a range of 1200°-1500°F.  Maximum flame contact time
is desirable.  A minimum residence time of the effluent stream in the
                                                (4)
combustion zone of 0.3-0.5 seconds is suggested,    although longer
times may be desirable in cases of materials resistant to oxidation.
Good mixing can be achieved by proper combustion chamber design.   One
type of fume burner design which has often been used successfully
involves the use of tangentially fixed burners (Figure 7.15.2).  A
number of other proprietary designs have been developed with the
objectives of maximizing flame contact and promoting good mixing.
Figure 7.15.3 is a schematic diagram of a burner in which the
process effluent is forced to travel through the flame.  An overall
schematic view of a varnish cooking fume burner control system is
shown in Figure 7.15.4.

Catalytic afterburners have also been used to control varnish cooking
fumes and odors.  The principle advantage of such an approach
according to theory is that the use of a catalyst allows the
oxidation reactions to take place at a lower temperature thus
reducing the use and cost of auxiliary fuel.  Mixed success has been
achieved in the use of catalytic afterburners for organic emissions.
Some apparently are successful while in other cases, odors not

-------
                        7.15.9
                                   ^REFRACTORY RING BAFFLE
                                    INLET FOR CONTAMINATED
                                    AIRSTREAM
Figure  7.15.2.
TYPICAL  DIRECT-FIRED AFTERBURNER WITH
TANGENTIAL ENTRIES FOR  BOTH THE FUEL
AND CONTAMINATED GASES.   (SOURCE: AIR
POLLUTION ENGINEERING MANUAL, Reference 4)

-------
                             7.15.10
               PROFILE PLATE
               COMBUSTIFUME"
                LINE BURNER
               CAS SUPPLY LIN!
                                         INSULATED SHELL
Figure  7.15.3.
DIAGRAM OF COMBUSTIFUME BURNER IN VERTICAL STACK
(SOURCE:   JOURNAL  OF THE AMERICAN INDUSTRIAL
HYGIENE ASSOCIATION, Reference 5)

-------
RECIRCULATING KftTER BASIN
   Figure 7.15.4.   SCHEMATIC PLAN FOR VARNISH-COOKING CONTROL  SYSTEM
                    (SOURCE;   AIR POLLUTION  ENGINEERING MANUAL,  Reference 4)

-------
                                  7.15.12
        originally present  in  the  effluent  can result.   Specific test
        information is  desirable before  the performance of catalytic units
        can be predicted  with  confidence.   Selheimer and Lance,     for
        example,  report that a laboratory scale test of a catalytic
        combustion process  was successful on a given varnish cooking
        effluent  at a temperature  of  700°F.
C.  INSPECTION POINTS
    With the exception of  opacity  regulations  there are relatively few
    specific prohibitory regulations  dealing with the paint and varnish
    industry.   In most cases,  prohibitions  of  odorous organic fumes such as
    those arising from uncontrolled varnish cooking are based upon nuisance
    law.  There are a few  agencies such  as  the San Francisco Bay Area Air
    Pollution Control District (Regulation  3)  which have mass or concentration
    standards for certain  organic  compounds, and  there is increasing interest
    in quantified odor measurement standards,  but these are the exception at
    the present time.  Consequently the  inspector should become familiar with
    the conduct of an odor survey  (see Chapter 6,  Section VI).

    Solvent losses from thinning operations in some cases may be governed
    by specific regulations  (see Rule 66, L.A.  County APCD),  but this class
    of regulation is far from  universal.

    Control of solvent losses  is based quite often on best technology either
    with or without the aid  of a permit  system.

    The inspector will have  several main tasks in relationship  to the
    inspection of paint and  varnish related industries.   These  would include:
        •   General surveillance for  odors  and possible visible plumes

        •   Investigation  of odor  complaints.

-------
                               7.15.13
    •   Determination of nature of processes carried out,  including the
        range of materials processed.

    •   Inspection of production and control equipment and the
        determination of operating practices.

    •   Determining whether source testing is desirable.

1.  Environmental Observations
    The major obvious environmental effects which can possibly be observed
    would include the broad spectrum of odors possible from varnish
    cooking and alkyd resin manufacturing, odors from aromatic and
    unsaturated solvents such as dicyclopentadiene,  surface contamination
    from oil mists, and visible plumes from cooking  operations or from
    the uncontrolled emission of phthalic anhydride.

    Odors originating from varnish cooking operations are  quite varied
    depending upon the raw materials and stage of the process.  Some are
    characteristic of vegetable drying oils such as  linseed, oiticica,
    and castor oils.  Fish oils would be easily recognized by their
    characteristic odor.  Other pungent and sometimes irritating odors
    are formed by the partial oxidation and polymerization reactions
    taking place during the cooking process.  Terpene or pine oil odors
    together with sulfur compound odors could possibly originate from
    the use of tall oil.  Most of these odors are rather pervasive and
    ill smelling.  Some are slightly nauseous in higher concentrations.

    The inspector must be careful to note wind speed and direction,
    relative humidity, atmospheric stability and other possible odor
    sources when tracking odors or investigating odor complaints.  Tracking

-------
                              7.15.14
    of  odors  should  be  done  systematically  noting  times,  locations,
    and odor  type  and intensity during  the  investigation.   Should
    regular complaint patterns develop,  a community  odor  panel may be
    utilized  to  obtain  more  objective evidence  on  time, location,  quality
    and intensity  of odors.

    Plume sources  should be  carefully identified and observations  should
    be  made consistent  with  good  opacity observation practices (see
    Chapter 5).  Complaints  of damage from  oil  droplets should be
    plotted on a map and identification of  materials made by  collecting
    samples of glass plates  for laboratory  examination in case of
    materials of doubtful  origin.

2.   Observations of  Plant  Exterior
    Points of emission  visible from  the exterior of  paint and varnish
    plants are process  vent  stacks serving  resin kettles  and  varnish
    cooking operations, condenser vents from  storage of heated liquid
    phthalic  anhydride  and solvent thinning tank vents.  Visible plumes
    may or may not be associated with varnish cooking operations.  In
    general there  should be no readily visible plume from a varnish
    cooking operation served by a fume burner.

    Intermittent visible emissions may result from the addition of
    resins to hot  oils  and from thinning operations when the  cooked
    varnish has not been cooled sufficiently.  Visible emissions may
    also result from filling operations in liquified phthalic anhydride
    storage tanks.

-------
                               7.15.15
3.  Interior Plant Inspection
    a.   The Interview
        The interview with plant management should be directed towards
        obtaining information about the process operations as they affect
        the air pollution potential,  to determine operating and maintenance
        procedures, and to examine applicable records such as fume burner
        temperature recorder charts (if used).   Examples of specific
        types of information to be obtained by interview are:
        •   Nature of raw materials used and finished product
            manufactured.  It is particularly important to determine the
            type of natural drying oils used in varnish cooking or in
            modifying alkyd resins as the odor potential may be quite
            different for each.  A list of solvents used should also be
            obtained.

        •   Process descriptions should be obtained such as sequence of
            materials added to cooking vessels, temperatures used, length
            of cook, technique used for solvent thinning operations, and
            equipment used for various operations.
            Operation and maintenance schedules should be determined
            particularly as to time of day that varnish cooking operations
            are carried out.  Maintenance of exhaust systems serving
            varnish cooking operations is important because of the great
            potential for lines being partially obstructed with fume
            deposits.  Obstructed lines may reduce exhaust flow rates and
            thus result in less effective fume pickup at hoods over open
            varnish cooking kettles.

-------
                           7.15.16
    •   Production data is important in determining emission inventory
        data by the application of general or specific emission
        factors.

    •   Exhaust and control system data.   Plant management should be
        asked to  provide data on exhaust  flow rates used,  amount of
        fuel used in afterburners, water  rates in any water scrubbers
        used, and on any internal guidelines or procedures used to
        determine the effectiveness of  the control equipment.

b.  The Physical  Inspection
    The physical  inspection should concentrate on equipment which is
    a potential source of air contaminants or designed to  control
    them.  It is  important that some inspections be made during the
    conduct of operations having the greatest air pollution potential.
    Safety procedures instituted by plant management particularly
    near hot and  flammable materials should be respected.   Important
    items to observe are:
    •   Specific  equipment used for each  relevant operation, where
        and how used.

    •   Condition of fume exhaust equipment including fans, drive
        belts, hooding, ducts and control equipment.  Examination
        should be made for leaks, clogged ducts and general level of
        maintenance.

    •   Functioning of exhaust and control equipment including hooding
        effectiveness, hood in-draft velocities, evidence  of fume
        burner fuel-use rates, afterburner temperatures and
        relationship of these parameters to evidence of visible plumes
        and odors.

-------
                       7,15.17
•   Data obtained in the interview should be verified wherever
    possible during the inspection.  This is particularly
    important with respect to operational procedures.

-------
                                    7.15.18
                                  REFERENCES


1.  Maltiello,  J.  J.  (ed.).   Protective  and Decorative Coatings,  Vol.  III.
    New York,  John Wiley and Sons,  Inc.,  1943.

2.  Maltiello,  J.  J.  (ed.).   Protective  and Decorative Coatings,  Vol.  I.
    New York,  John Wiley and Sons,  Inc.,  1941.

3.  Payne,  H.  F.   Organic Coating Technology, Vol.  I.   New York,  John  Wiley
    and Sons,  Inc., 1954.

4.  Danielson,  J.  A.  (ed.).   Air Pollution Engineering Manual.  Cincinnati,
    DHEW, PHS,  National Center for Air Pollution  Control  and  the  Los Angeles
    County Air Pollution Control District.  P.H.S.  No.  999-AP-40,  1967.

5.  Waid, D.  E.  Incineration of Organic  Materials  by  Direct  Gas  Flame for
    Air Pollution Control.   Am.  Ind. Hyg. Assoc.  J  30,  291-297.   1969.

6.  Selheimer,  E.  W.,  and R.  Lance.  Analysis of  Fumes  Leaving Resin Kettles
    and Fume  Abatement Equipment.   Off. Dig. Fed. Paint and Varnish Prod.
    Clubs,  27,  711-68.  August,  1954.

-------
                                    7.16.1
                       XVI.  GALVANIZING OPERATIONSv '

A.  DESCRIPTION OF SOURCE
    The coating of iron and steel materials (sheet metal, structural shapes
    and wire) with zinc to prevent oxidation is an industrial practice
    commonly found in most industrialized communities.   The primary source
    of air contaminants is the galvanizing kettle containing molten zinc.

    Galvanizing operations can be conducted on a batch basis, as in
    the coating of nuts and bolts, or as a continuously fed operation
    as in the coating of wire or chain link fencing.  This process may be
    found in job shops or as a captive operation in a large plant.

B.  PROCESS DESCRIPTION
    Since the surface of the material to be coated must be free of rust and
    oil so that the zinc can adhere to it, the product must go through
    cleaning and degreasing processes prior to the hot zinc dip.  The
    cleaning process has air pollution control impact as well as a quality
    control consideration.  If the metal to be coated is not clean, oil mists
    can be generated and an increased use of flux for proper coating action
    will be required with resultant increases in fume emissions.

    The process flow shown in Figure 7.16.1 is usually independent of batch
    or continuous operations.  Variations occur in the physical design of the
    galvanizing kettle and its ventilation system, depending upon whether
    batch or continuous operations are employed.  For example, galvanizing
    chain link fencing will require kettle configurations which differ sub-
    stantially from kettles used for structural shapes and fasteners.

-------
DUSTING WITH
SAiAfMPNIAC




CLEAR TOP N
FLUX COVER ^
GALVANIZED
,



,
k
<
DECREASING
TANK
HOT ALKALINE
SOLUTION






: 	 t It it 1 T r±i

WATER
RINSE





ACID
PICKLING
TANK




WATER
RINSE




PREFLUX
ZINC
CHLORIDE
SOLUTION




V

\\ PRODUCT
Sfl '

GALVANIZING
TANK/ KETTLE





Figure 7.16.1.   SIMPLIFIED FLOW CHART OF GALVANIZING PROCESS

-------
                               7.16.3
In the galvanizing step, zinc is maintained in the molten state at a
maximum temperature of 860°F.  The kettle is heated externally so that
the products of combustion do not enter the process and are separately
vented.  A flux cover is maintained on the surface of the molten metal
bath primarily to remove oxide formations from the metal to be coated
(some small amount of oxide may be formed between cleaning and the hot
dip) and to exclude air from the part as it enters the zinc bath.  The
secondary functions of the flux cover are to reduce heat losses from the
bath, reduce spattering of molten zinc and to keep the molten zinc surface
free of oxides thus assuring a bright coating on the product.

While a flux cover is necessary in the galvanizing process it is also the
major cause of the emission of air contaminants.  The two fluxes in
common use are ammonium chloride and zinc ammonium chloride plus a foaming
agent such as glycerine, wood flour or sawdust to provide a deeper flux
layer and to extend the life of the flux.  Visible emissions occur when
this cover is disturbed by piercing it with the product to be coated,
adding new flux, or in dusting the product with ammonium chloride as it
is removed from the bath to assure an even flow of zinc on the plated
surface.  Emissions are usually grey with the opacity varying according
to the mechanical agitation of the flux cover resulting from any of the
above conditions and especially from dusting when nearly all of the flux
is converted to dense ammonium chloride fumes.

As the configuration of the galvanizing kettle varies it is necessary to
vary the air pollution control system to capture the effluent caused by
this process.  Figure 7.16.2 shows a galvanizing batch operation.  The flux
may be noted on the surface of the bath in the foreground.   The parts are
dusted with ammonium chloride to form a bright finish.  Figure 7.16.3
shows the same tank with a room type hood covering the kettle.  This
hooding design allows for overhead materials handling equipment
to be used and gives the operators unimpaired access to the kettle.

-------
                                       7.16 . 4
Figure 7.16.2.
REMOVING WORK THROUGH A CLEAN ZINC SURFACE.  FLUX COVER IN
FOREGROUND, LOS ANGELES GALVANIZING CO., HUNTINGTON PARK,
CA. (SOURCE:  THOMAS, Reference 1)  "	~	~~'~"

-------
                                     7.16. 5
Figure 7.16.3.
OPEN TO A ROOM-TYPE HOOD OVER A GALVANIZING KETTLEf
LOS ANGELES GALVANIZING CO., HUNTINGTON PARK, CA.
(SOURCE:  THOMAS, Reference 1)    '' """"

-------
                                    7.16.6
    Figure 7.16.4 illustrates a slot hood (high inlet velocity) used
    in a continuous operation for galvanizing chain link fences.  As in most
    open processes the design of the ventilation system is critical.  Good
    engineering practices, outlined in Chapter III of the Air Pollution
    Control Engineering Manual, describe inlet velocities, materials of
    construction, fan requirements, and other factors of interest to the
    inspector.

    Fume arresting equipment commonly used to capture the effluent from this
    process include scrubbers which produce the least satisfactory results;
    precipitators, where oil mists are a significant part of the air
    contaminants to be captured, and baghouses where there is little or no
    oil mist entering the exhaust system.  Recent experience has shown that
    precipitators are more sensitive and require more maintenance than do
    baghouses for this application.  While a baghouse requires less maintenance,
    the temperature inside must be kept above the dew point, even when not
    in use, to prevent condensation on the bags.  Also consideration has been
    given to using a mechanical separator upstream of the baghouse to remove
    oil mists from the effluent in cases where oil mists present a problem.

    The requirement for high efficiency air pollution control equipment in
    galvanizing operations is necessitated by the small particle sizes of the
    fumes generated.  The average particle size is 2u as illustrated in
    Figure 7.16.5 of a photomicrograph of fume collected from a galvanizing
    kettle.  Table 7.16.1 shows the chemical analysis of materials collected
    from galvanizing kettles in a baghouse and in an electrical precipitator.

C.  INSPECTION POINTS
    Galvanizing operations, whether in large integrated plants or in job shops
    would be cited under opacity vs. time, process weight vs. allowable
    emissions, or public nuisance regulations.  Usually in job shops there

-------
                               7.16.7
Figure 7.16.4.
SLOT-TYPE HOOD SERVING A CHAIN LINK FENCE-GALVANIZING
FLUX BOX, ANCHOR POST PRODUCTS, INC., OF CALIFORNIA,
WHITTIER, CALIF. (SOURCE:  THOMAS, Reference 1)

-------
                             7.16.8
Figure 7.16.5.   PHOTOMICROGRAPH OF FUMES DISCHARGED FROM A
                GALVANIZING KETTLE (SOURCE:  THOMAS, Reference 1)

-------
                                  7.16.9
Table 7.16.1.
CHEMICAL ANALYSES OF THE FUMES COLLECTED BY A BAGHOUSE
AND BY AN ELECTRIC PRECIPITATOR FROM ZINC-GALVANIZING
KETTLES

Component

NH4C1
ZnO
ZnCl2
Zn
NH3
Oil
H2°
C
Not identified
Fumes collected
in a baghouse
(job shop kettle),
wt %
68.0
15.8
3.6
4.9
1. 0
1. 4
2.5
2.8

Fumes collected
in a precipitator
(chain link galvanizing),
wt|%
23. 5
6.5
15.2

3. 0
41. 4
1. 2

9.2
                        (SOURCE:  THOMAS, Reference 1)

-------
                               7.16.10


will be a one or at most two-shift operation (7:00 a.m. to 11 p.m.) while
three-shift operations are not uncommon in large integrated plants.  At
best, opacity readings are very difficult outside of daylight hours so
it may be necessary for the inspector to determine if there is any
difference in operating procedures during the various shifts.

The inspector will find it nececessary to observe the metal precleaning
operations, determine the type and quantity of flux and foaming agents
used, the normal hours of operation, and to isolate the location of the
galvanizing kettles within the plant relative to windows and roof
monitors, and the location of the air pollution control equipment serving
the kettles.

1.  Environmental Observation
    Due to the density and opacity of possible emissions from galvanizing
    plants public attention can be drawn to these operations.  Often
    nuisance complaints will arise from "dense white.smoke" which can
    result from galvanizing operations.  Complainants may be helpful in
    gathering information regarding excessive emissions during hours when
    the inspector is usually not in the area, allowing him to modify his
    hours of patrol to observe and record any variations in operations.

2.  Observations of the Exterior of the Plant
    An initial inspection of galvanizing operations may arise from the
    observation of dense clouds of grayish emissions from the roof
    monitors and windows of the building housing the operation or from the
    air pollution control equipment which serves the kettle.  In job shops
    this operation will be easy to pinpoint from outside the plant but in
    a large industrial complex only a systematic inventory of equipment
    and processes may spot the location of the operation.

-------
                               7.16.11
    Uncontrolled galvanizing operations are characterized by intermittent
    dense clouds of fume and oil mists and continuous light grey emissions
    Plants with air pollution control systems may still emit noticable
    quantities of fumes during dusting, as a result of adding flux or
    agitation of the bath,  depending on the ventilation system design  and
    its state of repair.

3.  Inspection of the Interior of the Plant
    Upon entering the plant the inspector should discuss with the plant
    operator the observations made outside of the plant, including a
    description of the emission and whether or not violations of any
    regulations were recorded.  The interview may continue during the
    inspection and include:
    a.   A detailed explanation of operating procedures and any
        variations from these procedures that may have occurred
        immediately preceding the inspection.

    b.   The type and quantity of flux used, frequency of addition of new
        flux and the quantities added.

    c.   Description of the  material to be galvanized and the normal
        process weight in pounds per hour.  (Material to be plated, flux,
        and quantity of zinc added as makeup).

    d.   Normal operating periods, hours of the day and days of the week.

    e.   Any experimental work done with fluxes or foaming agents.

-------
                                7.16.12


The observations should include:
1.  At initial inspection:
    a.  Overall dimensions  of the tank.
    b.  Sketch of the air pollution control system.
    c.  Make and model number of  the air pollution control equipment
        (if not a catalog item,  details of design such as water rate
        for scrubbers, filter area for baghouses  and fan capacity and
        motor horsepower should  be noted).
    d.  Make and model number of  burners, type and quantity of fuel
        used.  If oil is used there is a possibility of smoke emissions,
        especially during startup.  Depending on  the sulfur content of
        the oil, SOx emissions in excess of that  allowed may occur.

2.  After the initial inspection any changes to the  equipment and
    operating procedures should  be noted since permit action may be
    required.

3.  Observe one or more operating cycles including fluxing and dusting.
    The inspector should determine the varieties  of  materials galvanized
    to observe the worst operating conditions.

4.  Check for the condition of repair of the ventilation system and
    estimate fume-pickup efficiency during the periods of worst fuming.

5.  Check for repair of fume suppression equipment,  i.e., are there
    leaks, visible emissions from points other than  the equipment
    exhaust duct; have the  bags  been shaken or do they appear to be
    clogged; is there full  water  pressure to the  scrubber.

-------
                                7.16.13
Any items that vary from normal operating conditions should be
challenged by the inspector to determine if there has been negligence
in the operation, equipment breakdown or a change in operation.

For plants that have no air pollution control systems, suppression of
emissions will depend solely on the use of a flux cover.  At least one
hour of operation should be observed to record time and opacity of
emissions.

-------
                                     7.16.14
                                   REFERENCE


1.   Thomas,  G.   Zinc Galvanizing Equipment.   In:   Air Pollution Engineering
    Manual,  J.  A.  Danielson (ed.).   Cincinnati,  DHEW,  PHS,  National Center for
    Air Pollution  Control and the Los Angeles County Air Pollution Control
    District.   PHS No.  999-AP-40.  1967.

-------
                                   7.17.1
                  XVII.  ROOFING PLANTS — ASPHALT SATURATORS

A.  DESCRIPTION OF SOURCE ^
    Asphalt impregnated paper and felt, which is used extensively in the build-
    ing trades, is manufactured by means of asphalt roofing saturators.   These
    are high speed continuous processes using still bottoms from petroleum
    crude oil.  The saturators are a major source of vapors, liquid particulates
    and steam emissions.  Total emissions may range from 50 to 100% opacity
    where air pollution control systems are inadequate.  Unless properly
    controlled, these operations can be a major nuisance, particularly if
    located within a metropolitan area.

B.  PROCESS DESCRIPTION
    Felt used in this process is derived from vegetable fibers and contains 5 to
    10% moisture.   It is continuously fed through a machine known as a saturator
    (Figure 7.17.1) where it is impregnated with asphalt at 400 to 450°F.  The
    felt enters the machine through a series of dry loops (to preclude binding)
    where one side of the felt is sprayed with asphalt.  The spray serves to drive
    the moisture from the felt to assure smooth coating in the saturator tank.
    After leaving the tank the felt is once again looped to cool the product.
    Crushed rock or mica is applied with bituminous material to produce
    roofing shingles .

C.  EMISSIONS AND CONTROLS
    Figure 7.17.2 shows the points of emissions from asphalt saturators.  The
    emissions are a mixture of asphalt vapors, liquid particulates and water
    vapors.  The machines are large and require hoods with indraft velocities
    of 200 ft/min or more to capture the vapors and mists.  Figure 7.12.2
    illustrates the extent of hooding required to achieve positive control of
    ventilation.

    The crushed rock feeder may emit dust and should be hooded and vented to a
    cyclone or scrubber.

-------
  DRY
  LOOPER
SPRAY
SECTIONV
WET
LOOPERY
                                               TO ASPHALT
                                               	^~
                                               HEATER
                                                           TO ROLL PRODUCT
                                                           OR SHINGLE
                                                           PRODUCT OPERATIONS
                                                           T POINTS OF EMISSIONS
Figure 7.17.1.  SCHEMATIC DRAWING OF AN ASPHALT ROOFING  FELT SATURATOR
                (SOURCE:  WEISS, Reference 1).

-------
Figure 7.17.2.  ASPHALT SATURATOR HOOD AT FELT FEED
(Lloyd A.  Fry Roofing Co., Los Angeles, Calif.)
(SOURCE:   WEISS, Reference 1)

-------
                                7.17 .4
Due to the physical shape and size of the machines and high indraft
velocities at the hoods, large volumes of air are required to capture the
air contaminants.  Collection devices commonly used are spray scrubbers,
baghouses and two-stage low voltage electrical precipitators in combination
with spray scrubbers.

The Los Angeles County Air Pollution Control District in tests conducted
on three types of air pollution control systems mentioned above report
the results shown in Tables 7.17.1, 7.17.2, and 7.17.3.
    Table 7.17.1.  EMISSIONS FROM A WATER SCRUBBER AND LOW-VOLTAGE,
                   TWO-STAGE ELECTRICAL PRECIPITATOR VENTING AN
                   ASPHALT SATURATOR

Volume, scfm
Temperature, °F
Emission rate,
gr/scf
Ih/hr
Water vapor, %
Collection efficiency
Scrubber inlet
20, 000
139

0.416
71.4
3.7
Scrubber, 71%
Precipitator inlet
20, 234
85

0. 115
20
4.9
Precipitator, 50%
Precipitator outlet
20, 116
82

0. 058
10
4.8
Overall, 86%
                    (SOURCE;   WEISS, Reference 1.)
    Table 7.17-2.  EMISSIONS  FROM A BAG FILTER AND CYCLONE SEPARATOR
                   VENTING AN ASPHALT SATURATOR

Volume, scfm
Temperature, "F
Emission rate,
gr/scf
Ib/hr
Water vapor, %
Collection efficiency, %
Control equipment
inlet
10. 500
217

0.768
67.7
6.4

Control equipment
discharge
10, 300
I8S

0. 2S9
25. 5
6.8
62. 3
                    (SOURCE:   WEISS,  Reference 1.)

-------
                                  7.17.5
            Table 7.17.3.  EMISSIONS FROM A WATER  SCRUBBER VENTING
                           AN ASPHALT SATURATOR

Volume, scfm
Temperature, ' F
Emission rale,
gr/scf
Ih/hr
Water, %
Collection efficient, y, %
Scrubber
inlet
12,000
138

0. 535
55.0
2. 7

Scrubber
discharge
12, 196
82

0.0737
7.7
4.2a
86
                   aAt 3. 7 volume % of water, vapor is saturated air.
                    Other qualitative tests run simultaneously showed
                    no particulaU- water.


                         (SOURCE;  WEISS, Reference 1.)

    While electrical precipitators  show greater  collection efficiencies than bag-

    houses, critical maintenance problems must be considered.   Due to oil deposits

    on the precipitator components,  regular cleaning  is  mandatory to maintain

    collection efficiency.  Regular  checks  are also necessary  to assure timely

    replacement of cracked wires and insulators.   Oil particles may build

    up in baghouses and blind the filter bags to cause increase in pressure

    drop and decrease  in vapor pickup at the hoods.   Baghouses can be used

    in series with a  cyclone separator downstream to  collect reentrained oil

    droplets.



    The use of spray  scrubbers may  not be desirable  in areas where air pollution

    control agency regulations prohibit excessive opacities of emissions.   Due

    to greatly reduced collection efficiency in  the  one micron particle size

    range the opacity  of the effluent from  spray scrubbers can exceed 50%.

    Tests have shown fairly good efficiencies on a weight basis.
D.  INSPECTION POINTS

    Plant inspections should be  directed at  (1)  the saturator to determine

    the effectiveness of  the ventilation system  which captures the vapors and

    particulates from the application of the asphalt and (2) the collection

-------
                                7.17.6
device to determine if it is operating efficiently, as indicated
by the opacity of emissions.  Air Pollution control equipment operating
characteristics and maintenance recommendations are described in Chapter 2.
The inspector will observe poor pick up at the hood serving the saturator
if there are excessive air leakages through holes in the duct work, plugged
lines or other maintenance problems which can hinder the gas flow in the
system.  Methods of quantitatively determining hood indraft velocities
are discussed in Chapter 5.

Observations from outside the plant should be directed at windows and roof
monitors which will emit opaque vapors if the air pollution control system
is not in use.
                                             |!
Asphalt saturators can be a source of nuisance complaints as well as
violations of opacity regulations.

-------
                                    7.17.7
                                   REFERENCE

1.   Weiss, S.  M.   Asphalt Roofing Felt-Saturators.   In:   Air Pollution
    Engineering Manual,  J. A.  Danielson (ed.).   Cincinnati,  DREW,  PHS, National
    Center for Air Pollution Control and the Los Angeles County Air Pollution
    Control District.   PHS No. 999-AP-40.  1967.

-------
                                   7.18.1
               XVIII.  ASPHALTIC CONCRETE BATCHING OPERATIONS

A.  DESCRIPTION OF SOURCE
    Asphaltic concrete is produced by combining asphalt cement with sized, dry
    aggregate and fines to form a workable mixture for use in a variety of paving
    applications.  At ambient temperatures asphalt cement is a solid tarlike
    petroleum product.  It is heated to between 275° and 325°F until it flows
    sufficiently to thoroughly permeate the aggregate to form the mix
    specification desired.  Aggregate is the name applied to crushed rock, sand,
    gravel and fines which provide the properties of compressive strength and
    wear desired in concrete.  Batching plants are common to many construction
    sites and are portable to some degree.  Since large quantities of rock,
    sand and gravel are used in the batching operation, batching plants are
    found near quarries and gravel beds.

    The batching plant consists of a rotary drier, aggregate bins, materials
    handling equipment, screens, asphaltic cement storage and heating equipment,
    weigh boxes, and fuel storage.  Some form of air pollution control
    equipment is used ranging from cyclone separators and scrubbers to baghouses.

    Losses from uncontrolled rotary driers average about 5 pounds of dust per
    ton of material processed.     Tests conducted by the Los Angeles County
    Air Pollution Control District have shown dust loadings in dryer effluent
                                C2)
    as high as 6,700 pounds/hour    prior to entering the primary separator.
    Dust loadings can often reach 1,000 pounds/hour    or more from equipment
    controlled only by cyclones.

B.  PROCESS DESCRIPTION
    A typical equipment train for hot asphalt batching plants consists of sand
    and aggregate storage bins feeding into a bucket elevator or cold elevator
    which discharges into a rotary dryer, which may be either gas or oil

-------
                                7.18.2
 fired.  Depending on the proportions of  the different  sizes of  aggregate
 the  dryer  temperature will range from 250° to 350°F.   The  dried aggregate
 discharges to  the hot elevator which feeds into vibrating  screens  for  size
 classification (Figure  7.18.1) and interim storage.  Varying  amounts of rock,
 sand and fines are  then weighed and dropped into  the pug mill where the asphalt
 cement  is  added.  Finally, after thorough mixing  the batch is dropped  into
 trucks  for transport to the job site.  In a continuous-type plant  the  aggregate
 and  asphalt are introduced into the mixer and the mix  discharges continuously.
 Exhaust systems usually serve the hot and cold elevators,  the dryer and the
 weigh hopper-storage bin combination.  Figure 7.18.2 illustrates a typical
 system.

The Asphalt Institute classifies  paving mixes  according to  the relative
amounts of  coarse  aggregate,  fine  aggregate  and mineral dust  used for
various desired specifications.   By definition, coarse  aggregate is
retained on a No.  8  sieve  (up  to  2  1/2"); fine aggregate will pass a
No. 8 sieve; mineral dust will pass a No. 200  sieve.  Table 7.18.1
describes  the standard  U.S.  and Taylor  Sieve  Series.  The
difference  is that the  U.S.  Sieve  is identified by millimeters or microns
while the  Taylor Sieves are  identified  by the  nominal meshes  per linear
inch.  Table 7.18.2  is  a summary  of mixes recommended by the  Institute.  The
numbers represent  the amount  of material  that  will pass a given sieve
opening.  For example,  100 percent  of MIX Type la will  pass through a
2 1/2 inch  opening.

Asphalt cement is  a  thermoplastic material which  decreases  in viscosity
as it is heated.  A  range  of  specifications  for describing  the quality of
the asphalt is shown in Table 7.18.3.   These include:  penetration tests to
determine  relative hardness  at ambient  temperature (77°F or 25°C);
viscosity  tests, conducted at  temperatures of  275°F (135°C),  to establish
ease of flow; flash  point  to  determine  safe  heating limits; thin film test
to determine the degree of hardening which may occur during the plant

-------
                                                           GRADATION CONTROL UNIT
 ASPHALT BATCH  MIX PLANT
COLD AGGREGATE STORAGE
AND FEED
                                                                                                   00

                                                                                                   U>
               Figure  7.18.1.   ASPHALT BATCH PLANT WITH A CYCLONE
                                TYPE DUST  COLLECTOR
                                (SOURCE:   The Asphalt Institute,
                                 Reference 3)

-------
                                   7.18.4
                                         HOT AGGREGATE-
                                         BUCKET ELEVATOR
    (a)  Primary Collector
    (b)  Secondary Collector
    (c)  Mineral Filler  & Asphalt Cement Added at Mixer
     A   Emission Points
Figure 7.18.2.  FLOW DIAGRAM OF A TYPICAL HOT-MIX ASPHALT PAVING BATCH PLANT
                 (SOURCE:   Danielson, Reference  2)

-------
                                      7.18.5
               Table 7.18.1.
STANDARD  U.S.  AND TYLER SCREEN SCALES
(SOURCE:   Public Health Service, Reference 4)
Nominal
Aperture width
microns
1
2.5
5
10
20
37
43
44
53
61
62
74
88
89
104
105
124
125
147
149
175
177
208
210
246
250
295
297
350
351
417
inches*
.00004
.0001
.0002
.0004
.0008
.0014
.0017
.0017
.0021
.0024
.0024
.0029
.0035
.0035
.0041
.0041
.0049
.0049
.0058
.0059
.0069
.0070
.0082
.0083
.0097
.0098
.0116
.0117
.0138
.0138
.0164 (1/64)
U.S.
Standard
12500
5000
2500
1250
625
400

325
270

230
200
170


140

120

100

80

70

60

50
45


Tyler






325

270
250

200

170
150

115

100

80

65

60

48


42
35
Nominal
Aperture width
microns
420
495
500
589
590
701
710
833
840
991
1000
1168
1190
1397
1410
1651
1680
1981
2000
2362
2380
2794
2830
3327
3360
3962
4000
4699
4760
6680

inches*
.0165
.0195
.0197
.0232
.0232
.0276
.0280
.0328 (1/32)
.0331
.0390
.0394
.0460 (3/64)
.0469
.0550
.0555
.0650 (1/16)
.0661
.0780 (5/64)
.0787
.093 (3/32)
.0937
.110 (7/64)
. Ill
.131 (1/8)
.132
.156 (5/32)
. 157
. 185 (3/16)
. 187
.263 (1/4)

U.S.
Standard
40

35

30

25

20

18

16

14

12

10

8

7

6

5

4


Tyler

32

28

24

20

16

14

12

10

9

8

7

6

5

4

3

*NUmbers in parentheses indicate approximate fractions of an inch.

-------
                        7.18.6
(SOURCE:
   Table 7.18.2.  MIX COMPOSITIONS
Air Pollution Engineering Manual, Reference 2)

-------
                   7.18.7
Table 7.18.3.  ASPHALT TEST SPECIFICATIONS
TEST NAME
1. Penetration
2. Viscosity
3. Flash Point
4. Thin Film Test
5. Ductility Test
6. Soluability Test
7. Specific Gravity
8. Softening Point
TEST METHOD
AASHO* Test
T 49
T 201
T 48
T 179
T 51
T ff
T 43
T 53
ASTM** Test
D 5
D 2170
D 92
D 1754
D 113
D 4
D 70
D 36
* American Association of State Highway Officials
** American Society for Testing Materials

-------
                                   7.18.8
    mixing operation;  ductility tests to indicate the adhesive quality of
    asphalt and temperature susceptibility;  solubility tests to determine
    the active cementing constituents of the asphalt by establishing the
    bitumen content;  specific gravity,  the ratio of weight of a volume of
    water at the indicated temperature, to make volume corrections at
    elevated temperatures and to determine voids in asphalt paving mixes;
    softening point tests, for asphalt grades harder than those used for
    paving , to indicate the temperatures at which they reach an arbitrary
    degree of softening.

C.  CONTAMINANTS EMITTED
    As in all operations employing rotating kilns or dryers, entrainment of
    dust in the products of combustion due to product drying is the primary
    source of contaminants.  Secondary sources are materials handling equip-
    ment and sizing equipment.  In the typical plant shown in Figure 7.18.2,
    dust pickup points served by local exhaust systems are indicated.

    Table 7.18.4 shows the results of tests taken from plants with oil-fired
    dryers indicating the high dust loading in the exhaust gas and in the vent
    lines which capture dust from elevators and shakers.   The materials handling
    equipment accounts for as much as 2,000 pounds/hour exclusive of dust
    from the rotary dryer.

    Particle size distribution of the dust generated is an important factor in the
    selection of adequate air pollution control equipment.  Results of investi-
    gations made of the distribution of particle size versus percent by weight
    from drier exhaust and vent lines are shown in Figure 7.18.3.  This study
    indicated that as much as 89 percent of the particles may fall below 10
    microns.  The design of the mix which specifies the aggregate and
    fines required will affect the particle size distribution and the total
    dust loading of the exhaust.

-------
Table  7.18.4.
DUST AND  FUME DISCHARGE FROM ASPHALT BATCH  PLANTS

(SOURCE:   Sheehy et. al., Reference 4)
Test No.
Batch plant data
Mixer capacity, Ib
Process weight, Ib/hr
Drier fuel
Type of mix
Aggregate feed to drier, wt %
+10 mesh
-10 to +100 mesh
-100 to +200 mesh
-200 mesh
Dust and furne data
Gas volume, scfm
Gas temperature, °F
Dust loading, Ib/hr
Dust loading, grains/scf
Sieve analysis of dust, wt %
+100 mesh
-100 to +200 mesh
-200 mesh
Particle size of -200 rnesh
0 to 5 p., wt %
5 to 10 n, wt %
10 to 20 p., wt %
20 to 50 u, wt %
> 50 |i, wt %
C-426

6, 000
364, 000
Oil, PS300
City street, surface

70. 8
24.7
1. 7
2.8
Vent linea
2, 800
215
2, 000
81.8

4. 3
6.5
89.2

19.3
20. 4
21. 0
25. 1
14.2
Drier
21, 000
180
6, 700
37. 2

17. 0
25. 2
57.8

10. 1
11. 0
11.0
21. 4
46. 5
C-537

6, 000
346, 000
Oil, PS300




Highway, surface

68.
28.
1.
1.
Vent linea
3, 715
200
740
23. 29

0. 5
4. 6
94. 9

18. 8
27. 6
40. 4
12. 1
1. 1

1
9
4
6
Drier
22,

4,











050
430
720
24. 98

18.9
32. 2
48. 9

9.2
12.3
22. 7
49.3
6.5
                                                                                            ^J

                                                                                            M
                                                                                            00
    aVent line serves hot elevator,  screens, bin, weigh hopper, and mixer.

-------
                                  7.18.10
                  12  5 10  20 30  50  70 80  90 95  98 99.5 99 9 99.99
                         Per cent by weight less than indicated size
Figure  7.18.3.
COMPOSITE ASPHALT PLANT  DUST PARTICLE
SIZE DISTRIBUTION
(SOURCE:   JAPCA,  Reference 5)

-------
                               7.18.11
Collection and control systems for batch or continuous plants usually have
primary and secondary dust collection devices and in some instances a
tertiary device is added to the collection train.  The air pollution
control system is usually comprised of cyclone separators (singly or in
multiple units) and scrubbers or baghouses in series.  In addition to
collecting dust to meet air pollution control regulations, the dust
collected can be recycled to the process.

Cyclones have a reasonable efficiency for larger particle sizes (>20
microns) with a 2 to 3 inches water pressure drop.  Since as much
as 89 percent of the dust can be < 10 microns, additional high efficiency
collection is required.  High efficiency  mechanical collectors such as
multiclones, which can reach 90 percent efficiency in the 5 to 10 micron
particle size range with a pressure drop of 4 to 6 inches water gauge, are
available.  These devices may not meet the requirements of many agencies
having process weight or exhaust grain loading regulations.

The next higher order of efficiency of air pollution control equipment is
wet collectors.  A wide range of configurations, spray pattern designs
and gas path designs are available with efficiencies for the low particle
size range reaching greater than 99 percent (see Table 7.18.5).  Water
requirements range from 4 to 10 GPM/1,000 ft.    of gas entering the
scrubber and the water pressure varies from 50 to 100 psi.  A wide range
of pressure drops from 3 to 10  inches water may  occur..

As new regulations which decrease maximum allowable dust emissions are
enacted, baghouses will come into greater use as the final collector in
the dust removal train.  Efficiencies of overall dust collection with this
equipment is 99+ percent at a pressure drop of 4 to 5 inches water.  Air-
                                       3               2
to-cloth ratios of 2/1 to 6.25/1 (2 ft.   of air per ft.  of cloth to 6.25
   3               2
ft.  of air per ft.  of cloth) are required depending on the fabric used
as the filter media and bag cleaning procedures.

-------
Table  7.18.5.   TEST DATA  FROM HOT-MIX ASPHALT  PAVING PLANTS CONTROLLED BY  SCRUBBERS
                 (SOURCE:   Danielson,  Reference  2)
Test No.
C-357
C-82
C-379
C-355
C-372B
C-372A
C-369
C-393
C-354
C-185
C-173
1
C-379
C-337
2
C-234
C-426
C-417
C-425
3
C-385
C-433
C-422(l)
C-422(2)
C-418
Averages
Scrubber
inlet dust
loading,
Ib/hr
940
427
4, 110
2, 170
121
76
352
4, 260
--
1,640
__
.-
3, 850
305
--
372
2,620
560
485
--
212
266
--
--
3,400

Stack
emission,
Ib/hr
20.7
35.6
37. 1
47.0
19.2
10.0
24.4
26.9
27.8
21. 3
31.0
33.5
30.3
13.6
21. 1
21.2
25.5
39.9
32.9
25.5
17. 5
11.0
26.6
37.0
30.8
26.7
Aggregate
fines rate, a
Ib/hr
9, 550
4, 460
8, 350
14, 000
2, 290
2,840
4,750
4,050
6,370
5,220
8, 850
7,520
6, 500
2, 510
3, 730
2, 530
10,200
3,050
2,890
6,590
4, 890
5, 960
7, 140
3, 340
9,350
5, 900
Water-gas
ratio,
gal/1, 000 scf
6.62
3. 94
6.38
6. 81
10.99
11. 11
5.41
12. 01
6. 10
19.40
20. 40
11. 01
5.92
11. 11
7.28
5.70
7.75
2. 94
4.26
6.60
4.56
8. 12
4. 90
3.02
8. 90

Overall
scrubber
efficiency,
wt %
97.8
91.6
99. 1
97. 8
84.2
86. 8
93. 0
99.3
--
98. 7
--
--
99.2
95.5
--
94.3
99.0
92.8
93.2
--
91.7
95.8
--
--
99. 1
94.9
Type
of
scrubber
C
c
C
c
c
c
c
T
T
T
T
T
C
C
T
T
C
C
C
c
c
c
c
c
T

Type
of
drier
fuel
Oil
Oil
Oil
Oil
Oil
Gas
Oil
Oil
Oil
Oil
Oil
Oil
Gas
Oil
Gas
Gas
Oil
Oil
Oil
Gas
Oil
Gas
Oil
Oil
Oil

Production
rate,
tons/hr
183.9
96.9
174. 0
209. 1
142.9
158. 0
113. 0
92.3
118.4
137.8
184.2
144.6
191.3
114. 6
124.4
42.0
182.0
138.9
131. 4
131.7
174. 3
114.5
198.0
152.0
116.5

Gas
effluent
volume,
scfm
23, 100
19,800
26,200
25, 700
18,200
18,000
16, 100
19,500
7,720
18,700
17,000
23,700
28, 300
24, 300
15,900
17,200
22,000
24,600
18,000
18,200
20,000
19,600
21,000
22,200
17, 100

aQuantity of fines (minus 200 mesh) in dryer feed.
°C  = Multiple centrifugal-type spray chamber.
 T  = Baffled tower scrubber.

-------
                                     7.18.13
D.  INSPECTION POINTS
    Asphaltic concrete batching plants that operate in industrial or mixed
    industrial/residential areas can be the subject of nuisance complaints.   The
    large quantities of small particle size dust emitted from plants with only
    cyclones or inadequately sized wet collectors can carry relatively long
    distances under certain meteorological conditions.

    While the dust emitted from the batching plant is not toxic or potentially
    destructive to vegetation or finished surfaces, the potential health hazard
    that may occur from any finely divided material and possible soiling effects
    must be considered.  One hot asphalt plant with only a primary separator can
    emit 200 to 2,000 pounds of fine dust per hour.  Dust from asphalt plants
    settling on automobiles and other stationary items indicates that the
    air pollution control equipment is either not in use or is not operating
    properly.

    Inspection of a batching plant should determine the capability of existing
    equipment to meet emission control regulations.  The enforcement officer
    should:
         (1)  Check type of air pollution control equipment installed and
              observe emissions.
         (2)  Check basic equipment, suction points, duct work, etc., for leaks.
         (3)  Check ancillary equipment (boilers, mixers, etc.) for emissions
              and odors.
         (4)  Check plant area for potential sources of fugitive dust (storage
              areas, yard area, etc.).
         (5)  Check equipment capacity, operating schedule and plant throughput.

-------
                                 7.18.14
The enforcement officer should determine whether equipment which has been
accepted as capable of meeting an emission limit is operating properly and
complying with that limit, assuming a cyclone-scrubber control system is
used.  He should:
     (1)  Check water pressure and flow rate.
     (2)  Check for leaks in duct work.
     (3)  Check loading area for dust or odors.
     (4)  Check methods used to minimize fugitive dust emissions in the yard.
     (5)  Check type of fuel utilized in dryer and boiler.
     (6)  Check temperature of asphalt cement (assuming a cyclone-baghouse
          system is used).
     (7)  Check condition of bags for tears and blinding.
     (8)  Check pressure drop across baghouse to determine if it is higher
          than design specifications.

 The enforcement officer should determine the potential of the batching
 plant  to create a nuisance problem:

     (1)  Discuss with plant management dust and odors caused by
          overload, plugging or upset conditions.
     (2)  Discuss odors that may result from mixing operations.
     (3)  Discuss dust problems that may result from trucks in yard area,
          storage piles, etc.

Visual observation can provide a qualitative measure of the dust emitted
from a batch plant but only stack tests will give quantitative results.
Most batch plants should be tested if specific regulations regarding
process weight or allowable grain loading of exhaust gases are in effect.
The enforcement officer can. then make comparative readings of the dust
emissions to determine if the plant is in compliance.

-------
                                    7.18.15
                                  REFERENCES


1.   Control Techniques for Particulate Air Pollutants.   Washington, D.C. ,
    DREW, PHS,  NAPCA,  January 1969.

2.   Danielson,  J.  A.,  and R.  S.  Brown, Jr. Hot Asphalt-Mix Paving Batch Plants.
    In:   Air Pollution Engineering Manual, J.  A.  Danielson (ed.).  Cincinnati,
    DREW, PHS,  National Center for Air Pollution Control and the Los Angeles
    County Air  Pollution Control District.  pyg NO. 999-AP-40.  1967.
3.  The Asphalt Plant Manual.   The Asphalt Institute.   Series  No.  3  (MS-3).
    March 1967.

4.  Sheeny, J. P., W. C. Achinger, and R. A.  Simon.  Handbook  of Air Pollution,
    DHEW, PHS, NCADC No. 999-AP-44.  (No date).

5.  Air Pollution Control Practices for Hot Mix  Asphalt Paving Batch Plants.
    J. Air Pollution Control Assoc. ,  Vol. 19, No.  12,  December 1969.

-------
                                      G.I
                                   GLOSSARY
ABSORBER:  A device utilized to extract selectively cne or more elements of a
     gas stream from others by absorption in a liquid medium.  Usually the
     process is performed in cylindrical towers packed with an inert material
     thus providing a large surface area for intimate 'contact between the rising
     gas and the falling liquid.   (The process may also be carried out in a
     tower containing perforated trays in which the rising gas bubbles through
     the layer of liquid on the trays.)

ABSORPTION:  A process in which one or more constituents are removed from a
     gas stream by dissolving them in a selective liquid solvent.  This may
     or may not involve a chemical change.

ACCUMULATOR:  A vessel for the temporary storage of a gas or liquid; usually
     used for collecting sufficient material for a continuous charge to a
     refining process.

ACID SLUDGE:  The residue left after treating petroleum oil with sulfuric acid
     for the removal of impurities.  It is a black, viscous substance contain-
     ing the spent acid and impurities which have been separated from the oil.

ACID TREATMENT:  An oil-refining process in which unfinished petroleum pro-
     ducts, such as gasoline, kerosene, diesel fuel, and lubricating stocks,
     are contacted with sulfuric acid to improve color, odor, and other
     properties.

ACIDULATE:  To make acid, especially slightly acid; to treat with acid.

ADDITION REACTION:  Direct chemical combination of two or more substances to
     form a single product, such as the union of ethylene and chlorine to form
     ethylene dichloride:


               C2H4 + C12 ~* C2H4C12
ADIABATIC LAPSE RATE:  The rate at which a given mass of air lifted adiabatical-
     ly (without loss or gain of heat) cools due to the decrease of pressure
     with increasing height, 5.4°F/1000 ft C9.7°C/km).

ADIABATIC PROCESS:  A thermodynamic change of state of a system in which there
     is no transfer of heat or mass across the boundaries of the system.

-------
                                     G.2
ADIABATIC TEMPERATURE:  (Combustion)  The theoretical temperature that would
     be attained by products of combustion provided the entire chemical energy
     of the fuel, the sensible heat content of the fuel, and combustion air
     above the ambient temperature were transferred to the products of combus-
     tion.  This assumes (1) that combustion is complete, (2) that there is no
     heat loss, (3) that there is no dissociation of the gaseous compounds
     formed, and (4) that inert gases play no part in the reaction.

ADSORPTION:  A reaction in which one or more constituents (adsorbates) are re-
     moved from a gas stream by contacting and adhering to the surface of a
     solid (adsorbent).  Periodically the adsorbent must be regenerated to re-
     move the adsorbate.

AEROSOL:  A colloidal system in which particles of solid or liquid are sus-
     pended in a gas.  There is no clear-cut upper limit to the particle size
     of the dispersed phase in an aerosol, but as in all other collodial sys-
     tems, it is commonly set at 1 micro-meter.  Haze, most smoke, and some fogs
     and clouds may be regarded as aerosols.

AFTERBURNER:  A burner located so that combustion gases are made to pass through
     its flame in order to remove smoke and odors.

AGGLOMERATION:  Groups of fine particles clinging together to form a larger
     particle.

AIR ATOMIZING OIL BURNER:  A burner in which oil is atomized by compressed air
     which is forced into and through one or more streams of oil thus breaking
     it into a fine spray.

AIR CURTAIN DESTRUCTOR:  A device employing an air blower with pit incinerator.
     Excess oxygen and turbulence result in apparent complete combustion, leaving
     no residue unburned carbon (smoke) nor odorous hydrocarbons.  The device
     has been satisfactorily demonstrated for disposal of low-ash, high-Btu
     waste, such as trees, tree trunks, brush (but not leaves), and wooden
     crating material.  Excessive pollution results when materials such as
     automobile tires, cushions, and other non-wood wastes are burned.

AIR HEATER OR AIR PREHEATER:  Heat transfer apparatus through which combustion
     air is heated by a medium of higher temperature, such as the products of
     combustion or steam.

ALKYLATION:  In petroleum refining, usually the union of an olefin (ethylene
     through pentene) with isobutane to yield high-octane, branched-chain paraf-
     finic hydrocarbons.  Alkylation may be accomplished by thermal and catalytic
     reactions.  Alkylation of benzene and other aromatics with olefins yields
     alkyl aromatics.

ALUMINA:  Aluminum oxide (Al^O-), an intermediate product in the production of
     aluminum.  This oxide also occurs widely in nature as corundum.

-------
                                     G.3
AMBIENT AIR:  That portion of the atmosphere, external to buildings, to which
     the general public has access.

ANODE:  In aluminum production, the positively charged carbon terminal in the
     reduction cell or pot.  Oxygen is attracted to the anode where it combines
     with carbon plus any impurities, such as sulfur, which may be present.  The
     anode is consumed by this process and must be replaced periodically.

ANTHRACITE COAL:  A hard, black, lustrous coal containing a high percentage of
     fixed carbon and a low percentage of volatile matter.  Commonly referred
     to as "hard coal," it is mined in the United States, mainly in eastern
     Pennsylvania, as well as in small quantities in other states.

AREA SOURCE:  Any small residential, governmental, institutional, commercial,
     or industrial fuel combustion operations, as well as on-site waste disposal
     and transportation sources (see point source).

ASH:  The noncombustible solid matter in fuel.

ASH-FREE BASIS:  The method of reporting fuel analysis whereby ash is deducted
     and other constituents are recalculated to total 100 percent.

ASME:  The American Society of Mechanical Engineers.

ASPIRATING BURNER:  A burner in which the fuel in a gaseous or finely divided
     form is burned in suspension.  The air of combustion is supplied by drawing
     it through one or more openings by the lower static pressure created by
     the velocity of the fuel stream.

ASTM:  The American Society for Testing and Materials.

ATOMIZER:  A device by means of which a liquid is reduced to a very fine spray.

ATMOSPERIC PRESSURE:  The pressure due to the weight of the atmosphere.  Normal
     atmospheric pressure at sea level is approximately 14.7 p.s.i. or 29.92
     inches of mercury.

AVAILABLE HEAT:  The quantity of useful heat per unit of fuel available from
     complete combustion after deducting dry flue gas and water vapor losses.


                                      B

BAGASSE:  Sugar cane from which the juice has been essentially extracted.

BAG FILTER:  A device containing one or more cloth bags for recovering particles
     from the dust-laden gas which is blown through it.

-------
                                     G.4
BAGHOUSE:  Structures containing several bag filters (see bag filters).

BAG-TYPE COLLECTOR:   A filter wherein the cloth filtering medium is made in the
     form of cylindrical bags.

BANKING:  Burning solid fuels on a grate at rates sufficient to maintain igni-
     tion only.

BARK BOILER:  A combustion unit designed to burn mainly bark and wood residues,
     used to produce steam for process or electrical energy.

BAROMETRIC CONDENSER:  An inexpensive direct contact condenser used when con-
     densate recovery is not a factor.  In this type of condenser, steam rises
     into a rain of  cooling water, and both condensed steam and water flow out
     of the bottom of the condenser,  maintaining a partial vacuum in the con-
     denser.

BASE STOCK:  A sheet, usually produced from unbleached kraft pulp, formed into
     linerboard  on a fourdrinier machine.

BATCH FED INCINERATOR:  An incinerator that is charged with refuse periodically,
     the charge  being allowed to burn down or burn out before another charge is
     added.

BINDER:  See core binder.

BITUMINOUS COAL:  Soft coal, dark brown to black in color, having a relatively
     high proportion of gaseous constituents and usually burning with a smoky
     luminous flame.

BLACK LIQUOR:  Spent chemical solution which is formed during the cooking of
     wood pulp in the digester.  The  black liquor is burned as a fuel in the
     recovery furnace.

BLAST FURNACE:  A shaft furnace in which solid fuel is burned with an air blast
     to smelt ore.

BLEEDER:  A bypass or relief valve used to relieve excess pressure.

BLISTER COPPER:   An impure intermediate product in the refining of copper, pro-
     duced by blowing copper bearing  material in a converter; the name is
     derived from the large blisters  on the cast surface that result from the
     liberation  of SO  and other gases.

BLOWBACK:  The difference between the pressure at which a safety valve opens
     and at which it closes, usually  about three percent of the pressure at
     which the valve opens.

BLOWDOWN:  Hydrocarbons purged during refinery shutdowns and startups which are

-------
                                     G.5
     manifolded for recovery, safe venting, or flaring.

BOILER:  A closed pressure vessel in which the liquid, usually water, is vapor-
     ized by the application of heat.

BOILER HORSEPOWER:  A unit of rate of water evaporation.  One boiler horsepower
     equals the evaporation of 34.5 Ib. of water per hour from a temperature of
     212°F into dry saturated steam at the same temperature (equivalent to
     33,472 Btu per hour).

BRASSESS:  Copper-based alloy of 60-65% copper.  Alloying material is usually
     zinc.

BREAKER:  In anthracite mining, the structure in which the coal is broken, sized,
     and cleaned for market.  Also known as a coal breaker.  A machine used for
     the primary reduction of coal, ore, or rock.

BREECHING:  A sheet-iron or sheet-metal casing at the end of boilers for
     conveying the smoke from the flues to the smokestack.

BRIGHTENING:  The process of producing bright stock (see bright stock).

BRIGHT STOCK:  Refined high viscosity lubricating oils usually made from resi-
     dual stocks by suitable treatment, such as a combination of acid treatment
     or solvent extraction with dewaxing or clay finishing.

BRITISH THERMAL UNIT (Btu):  The mean British thermal unit is 1/180 of the heat
     required to raise the temperature of one pound of water from 32 °F to 212°F
     at a constant atmospheric pressure.  It is about equal to the quantity of
     heat required to raise one pound of water 1°F.  A Btu is essentially 252
     calories.

BRONZES:  Copper based alloy of 85-90% copper.  Alloying material is usually tin.

BUNKER C OIL:  Residual fuel oil of high viscosity commonly used in marine and
     stationary power plants (No. 6 fuel oil).

BURNER:  A device for the introduction of fuel and air into a furnace at the
     desired velocities, turbulence, and concentration to establish and main-
     tain proper ignition and combustion of the fuel.

BUSS (BUSBAR):  A heavy metal conductor, usually copper, for high amperage
     electricity.

BUSTLE PIPE:  In steel making, a metal tube of large diameter which surrounds
     a blast furnace at a level a little above the tuyeres; it is lined with
     refractory material and distributes the hot air from the blast stoves to
     the pipes (goosenecks)  which carry the air to the tuyeres.

-------
                                     G.6
CALCINE:  Ore or concentrate which has been treated by calcination or roasting
     and which is ready for smelting.

CALCINING:  Roasting of ore in an oxidizing atmosphere usually to expel sulfur
     or carbon dioxide.  If sulfur removal is carried to practical completion,
     the operation is termed "sweet roasting"; if all C02 is removed, the opera-
     tion is termed "dead roasting."

CALORIE:  The mean calorie is 1/1000 of the heat required to raise the tempera-
     ture of one gram of water from 0°C to 100°C at a constant atmospheric
     pressure.  It is about equal to the quantity of heat required to raise one
     gram of water 1°C.

CARBONIZATION:  The process of converting coal to carbon in the absence of air
     by using intense heat to remove volative ingredients.

CARBON LOSS:  The loss representing the unliberated thermal energy caused by
     failure to oxidize some of the carbon in the fuel.

CARCINOGENIC:  Producing or tending to produce cancer.

CARRYOVER:  The chemical solids and liquid entrained in the steam from a boiler
     or effluent from a fractionating column, absorber, or reaction vessel.

CATALYST:  A substance capable of changing the rate of a reaction without itself
     undergoing any net change.

CATALYTIC CRACKING:  The conversion of high boiling hydrocarbons into lower
     boiling substances by means of a. catalyst which may be used in a fixed
     bed, moving bed, or fluid bed.  Natural or synthetic catalysts are employed
     in bead, pellet, or powder form.   Feedstocks may range from naphtha cuts
     to reduced crude oils.

CATHODE:  In aluminum production, the negatively charged terminal of the reduc-
     tion cell to which the aluminum migrates.  The terminal consists of the
     carbon lining that makes up the bottom of the cell.

CAVING:  In metal mining, caving implies the dropping of the over-burden as
     part of the system of mining.

CHARGING:  Feeding raw material into an apparatus, for example, into a furnace,
     for treatment or conversion.

CHLOROSIS:  A diseased condition in green plants marked by yellowing or blanch-
     ing of the leaves.

-------
                                     G.7
CINDERS:  Particles not ordinarily considered as fly ash or dust because of
     their greater size; these particles consist essentially of fused ash and/
     or unburned matter.

CLEANING FIRES:  The act of removing ashes from the fuel bed or furnace.

CLINKERS, CEMENT:  The glassy, stony, lump-like product of fusing together clay
     and limestone as the first stage in the manufacture of portland cement.

COAL DESULFURIZATION:  See desulfurization.

COAL GAS:  Gas formed by the destructive distillation of coal.

COAL TAR:  A black viscous liquid formed as a by-product from the distillation
     of coal.

COKE:  Bituminous coal from which the volatile constituents have been driven
     off by heat so that the fixed carbon and the ash are fused together.

COKE BREEZE:  Fine coke particles leaving the coke quencher with the quenched
     coke by conveyor.  The particles are very fine and may be blown away.

COKE, PETROLEUM:  The solid carbonaceous residue remaining as the final product
     of the condensation processes in cracking.  It consists of highly poly-
     cyclic aromatic hydrocarbons very poor in hydrogen.  It is used extensive-
     ly in metallurgical processes.  Calcination of petroleum coke can yield
     almost pure carbon or artificial graphite suitable for production of
     electrodes, motor brushes, dry cells, etc.

COKING:  1.  Carbonization of coal by destructive distillation.  2.  In petro-
     leum refining: any cracking process in which the time of cracking is so
     long that coke is produced as the bottom product; thermal cracking for
     conversion of heavy, low-grade oils into lighter products and a residue
     of coke; or the undesirable building up of coke or carbon deposits on
     refinery equipment.

COLLECTION EFFICIENCY:  The ratio of the weight of pollutant collected to the
     total weight of pollutant entering the collector.

COLLOID:  1.  A substance composed of extremely small particles, ranging from
     0.005 micro—meters to 0.2 micro-meters, which when mixed with a liquid
     will not settle, but will remain suspended.  The colloidal suspension thus
     formed has properties that are quite different from the simple solution of
     the two substances.  2.  In fuel burning, a finely divided organic sub-
     stance which tends to inhibit the formation of dense scale and results in
     the deposition of sludge, or causes it to remain in suspension, so that it
     may be blown from the boiler.

-------
                                     G.8
COLLOIDAL FUEL:  Mixture of fuel oil and powdered solid fuel.

COMBINATION BOILER:   A combustion unit used to produce steam for process or
     electrical energy which is designed to burn bark and at least one other
     fuel.

COMBUSTION CONTAMINANTS:  Particulate matter discharged into the atmosphere from
     the burning of  any kind of material containing carbon.

COMBUSTION TOWER:  Refractory graphite-lined or water-jacketed stainless steel
     tower in which  phosphorus is burned to phosphorus pentoxide.

CONDENSED FUMES:  Minute solid particles generated by the condensation of vapors
     from solid matter after volatilization from the molten state, or generated
     by sublimation, distillation, calcination, or chemical reaction when these
     processes create airborne particles.

CONDENSER BOILER: A boiler in which steam is generated by the condensation of
     a vapor.

CONTACT CONDENSER:  A condenser in which coolant, vapors, and condensate are
     mixed.

CONTINUOUS-FEED INCINERATOR:  An incinerator into which refuse is charged in a
     nearly continuous manner in order to maintain a steady rate of burning.

CONTROL STRATEGY: A combination of measures designed to achieve the aggregate
     reduction of emissions necessary for attainment and maintenance of a
     national ambient air quality standard.

CONVECTION:  The transmission of heat by circulation of a liquid or a gas.  Con-
     vection may be  natural or forced.

CONVERTER:  1.  A furnace in which air is blown through a bath of molten metal
     or matte, oxidizing the impurities and maintaining the temperature through
     the heat produced by the oxidation reaction.  2.  In nitric acid produc-
     tion, the chamber in which ammonia is converted to nitric oxide and water
     by reacting it  with air over a platinum-rhodium catalyst.

CONVERTING:  The process of removing impurities from molten metal or metallic
     compounds by blowing air through the liquid.  The impurities are changed
     either to gaseous compounds, which are removed by volatilization, or to
     liquids or solids which are removed as slags.

CORE:  The central part of a sand mold as used in foundries.  The device placed
     in a mold to make a cavity in a casting.

CORE BINDER:  Organic material added to foundry sand to aid in formation of a

-------
                                     G.9
     strong core for casting.  Flour, linseed oil, starch, and resins are among
     materials used.

CRACKING:  Chemical reaction by which large oil molecules: are decomposed into
     smaller, lower—Boiling -molecules.  At the same time, certain of these
     molecules, which are reactive, comBine with, one another to give even larger
     molecules than those in the original stock..  The-more stable molecules
     leave the system as cracked gasoline, But the reactive ones polymerize,
     forming tar and even coke.  Cracking -may Be in either the liquid or vapor
     phase.  When a catalyst is used to Bring aBout the desired chemical reac-
     tion, this is called "catalytic cracking"; otherwise, it is assumed to Be
     "thermal cracking" Csee catalytic cracking!.

CRACKLINGS:  The crisp residue left after the fat has Been separated from the
     fiBrous tissue in rendering lard or frying or roasting the skin of pork,
     turkey, duck, or goose.

CRUSHER:  A machine for crushing rock, or other materials.  Among the various
     types of crushers are the ball mill, gyratory crusher, Hadsel mill, ham-
     mer mill, jaw crusher, red mill, rolls, and stamp mill.

CRYOLITE:  Sodium aluminum fluoride (Na A1F ) used as an electrolyte in smelting
     of alumina to provide aluminum.

CULM:  The fine refuse from anthracite coal production.

CUPOLA:  A vertical shaft furnace used for melting metals, especially grey
     iron, by having the charge come in contact with the hot fuel, usually
     metallurgical coke.  Metal, coke, and flux are charged from the top of the
     furnace onto a bed of hot coke through which air is blown.

CURTAIN WALL:  A partition wall between chambers in an incinerator under which
     combustion gases pass.

CYCLONE:  A structure without moving parts in which the velocity of an inlet
     gas stream is transformed into a confined vortex from which centrifugal
     forces tend to drive the suspended particles to the wall of the cyclone
     body.  The particles then slide down the cyclone wall and are collected
     at the bottom.

CYCLONE SCRUBBERS:  Devices ranging from simple dry cyclones with spray nozzles
     to multistage devices.  All feature a tangential inlet to a cylindrical
     body.

CYCLONIC SPRAY TOWER:  Liquid scrubbing apparatus where sprays are introduced
     countercurrent to gases for removal of contaminants.

-------
                                     G.10
                                      D

DEHYDROGENATION;   The removal of hydrogen from a chemical compound; for example,
     the removal of two hydrogen atoms from Butane to make Butylene, and the
     further removal of hydrogen to make Butadiene.

DEMISTER (COLLECTOR):  1.   A mechanical device used to eliminate finely divided
     liquid particles from process streams- by Impaction and agglomeration.
     2.  Apparatus made of wire mesh, or glass- fiBer and -used to eliminate acid
     mist as in the manufacture of sulfurlc acid.

DESTRUCTIVE DISTILLATION:   1.  A process of distillation in which an organic
     compound or mixture Is heated to a temperature high, enough to cause de-
     composition.  2.  The heating of organic matter when air is not present,
     resulting in the evolution of -volatile matter and leaving char consisting
     of fixed carbon and ash..

DESULFURIZATION:   1.  In coal processing, the removal of sulfur from the coal,
     often by mechanical cleaning processes.  2.  Hi petroleum refining, remov-
     ing sulfur or sulfur  compounds from a charge stock Coil that Is to be
     treated in a particular unit].

DIFFUSION:  The spreading  or scattering of a gaseous or liquid material.
     1.  Eddy diffusion:  diffusion caused by turbulent activity in a fluid
     system.  2.   Molecular diffusion:  a process of spontaneous intermixing
     of different substances, attributed to molecular motion and tending to
     produce uniformity of concentration.

DIRECT-FIRED BOILER:  Commonly used to denote a boiler and furnace fired by
     pulverized coal.

DISPERSION:  The dilution  of a pollutant by diffusion, or turbulent action, etc.
     Technically, a two-phase system of two substances, one of which (the dis-
     persed phase) is uniformly distributed in a finely divided state through
     the second substance  (the dispersion medium).  Either phase may be a gas,
     liquid, or solid.

DISTILLATE:  The product of distillation obtained by condensing the vapors from
     a still.

DISTILLATE FUELS:  Liquid  fuels distilled usually from crude petroleum, except
     residuals such as No. 5 and No.  6 fuel oil.

DISTILLATE OILS:   The lighter oils produced by distilling crude oil.

DISTILLATION:  The process of heating a substance to the temperature at which
     it is converted to a  vapor, then cooling the vapor, and thus restoring it
     to the liquid state.

-------
                                     G.ll
DOCTOR TREATMENT:  Treatment of gasoline with sodium-plumbite solution and sul-
     fur to improve Its odor.

DOPES FOR GASOLINES':  Materials added in small amounts to gasoline to increase
     the octane number and thus help to prevent knocking.

DOUBLE DECOMPOSITION:  A chemical reaction between two compounds in which, part
     of the first compound becomes united with the remainder of the second, as:
     AK + CD = AD + KC.

DRAFT:  A gas flow-resulting from the pressure difference between the incinera-
     tor, or any component part, and the atmoshpere, which.moves the products
     of combustion from the incinerator to the atmosphere.  1.  Natural draft:
     the negative pressure created By the difference in density Between the hot
     flue gases and the atmosphere.  2.  Induced draft:  the negative pressure
     created by the vacuum action of a fan or blower located Between the in-
     cinerator and the stack.  3.  Forced draft:  the positive pressure created
     by the action of a fan or blower, which, supplies the primary or secondary
     air.

DROP ARCH:  A refractory construction or baffle which serves to deflect gases
     in a downward direction.

DROSS:  1.  Impurity formed in melted metal.  A zinc-and-iron alloy forming in
     a bath of molten zinc, in galvanizing iron.  2.  The scum that forms on
     the surface of molten metals usually due to oxidation, But occasionally
     due to the rising of impurities to the surface.

DRUM, FLASH COR FLASH TOWER):  A drum or tower into which the heated outlet
     products of a preheater or exchanger system are conducted, often with some
     release in pressure.  The purpose of the drum is to allow vaporization and
     separation of the volatile portions for fractionation elsewhere.

DRY BOTTOM FURNACE:  A furnace designed to burn pulverized coal at temperatures
     low enough to prevent the ash from fusing or slagging.

DUST:  Generally particles from 1 to 100 micro-meters in size that become air-
     borne by natural or mechanical means.  These particles do not diffuse but
     will settle under the influence of gravity Csee also particle].

DUST COLLECTING FAN:  A centrifugal fan which concentrates dust and skims it
     into a cyclone or hopper.

DUSTLESS LOADING:  The amount of dust in a gas, usually expressed in grains per
     cubic foot or in pounds per thousand pounds of gas Csee also grain load-
     ing) .

-------
                                     G.12
ECONOMIZER:  A heat recovery device designed to transfer heat from the products
     of combustion to a fluid,  usually feedwater for a steam boiler.  The water
     flows through a bank of tubes placed across the flue gases and is heated by
     these gases prior to entering the boiler.

EFFICIENCY:  The ratio of output to input.  The efficiency of a steam generating
     unit is the ratio of the heat absorbed by the water or steam to the heat in
     the fuel fired, expressed in percent.

EFFLUENT:  Any waste material (solid,  liquid, gas) emitted by a process.

EFFLUENT WATER SEPARATOR:  A container designed to separate volatile organic
     compounds from waste water prior  to discharge or reuse.

ELECTROLYSIS:  1.  Chemical change resulting from the passage of an electric
     current through an electrolyte.   2.  Transfer or transport of matter
     through a medium by means of conducting ions (positively or negatively
     charged particles).  The medium may consist of fused salts or conducting
     solutions which permit free movement of ions toward the countercharged
     electrodes immersed in the system.

ELECTROSTATIC PRECIPITATOR:  Devices that separate particles from a gas stream
     by passing the carrier gas between two electrodes across which a unidirec-
     tional, high-voltage electrical charge is placed.  The particles pass
     through this field, become charged and migrate to the oppositely charged
     electrode.  Single-stage precipitators are those in which gas ionization
     and particulate collection are combined into a single step.  In the two-
     stage unit, ionization is achieved by one element of the unit and the col-
     lection by the other.  Electrostatic precipitators are highly efficient
     collectors for minute particles.

ELUTRIATOR:  A vertical tube through which a gas or fluid passes upward at a
     specific velocity while a solid mixture whose separation is desired is fed
     into the top of the column.  The  large particles which settle at a veloci-
     ty higher than that of the rising fluid are collected at the bottom of the
     column, and the smaller particles are carried out of the top of the column
     with the fluid.

EMISSION:  The total amount of a solid, liquid, or gaseous pollutant emitted
     into the atmosphere from a given  source in a given time, and indicated in
     grams per cubic meter of gas, pounds per hour, or other quantitative
     measurement.

ENDOTHERMIC REACTION:  A reaction which requires the addition of heat for its
     continuation.

-------
                                     G.13
ENTRAINMENT:  The process of particulates or other materials being carried
     along by a gas stream.

EVAPORATOR:  Usually a vessel which receives the hot discharge from a heating
     coil and, by a reduction in pressure, flashes off overhead the light pro-
     ducts and allows the heavy residue to collect in the bottom  (see flash
     tower) .

EXCESS AIR:  Air supplied for combustion in excess of that theoretically re-
     quired for complete combustion, usually expressed as a percentage of
     theoretical air, such as "130 percent excess air."

EXOTHERMIC REACTION:  A reaction which produces heat.
FABRIC FILTER:  See bag filter.

FIXED CARBON:  That part of the carbon which remains when coal is heated in a
     closed vessel until the volatile matter is driven off.  It is the nonvola-
     tile matter minus the ash.

FEEDSTOCK:  Starting material used in a process.  This may be raw material or
     an intermediate product that will undergo additional processing.

FLOATING ROOF:  A special tank roof which floats upon the oil in a storage tank.

FLUE:  Any duct, passage, or conduit through which the products of combustion
     are carried to a stack or chimney Csee also breeching) .

FLUE GAS:  The gaseous products of combustion passing from the furnace into the
     stack.

FLUIDIZED ROASTING:  Oxidation of finely ground pyritic minerals by means of
     upward currents of air, blown through a reaction vessel (fluid bed roaster)
     with sufficient force to cause the bed of material to expand (boil) .  Re-
     action between mineral and air is maintained at a desired exothermic level
     by control of oxygen entry, by admission of cooling water, or by addition
     of fuel .

FLUOROSIS:  A chronic poisoning resulting from the presence of 0.9 milligrams
     or more per liter of fluorine in drinking water.  Teeth became brittle and
     opaque white with a mottled enamel.
FLUOROSPAR:  A natural calcium fluoride (CaH^) used as a flux in open hearth steel
     furnaces and in gold, silver, copper, and lead smelting.

-------
                                     G.14
FLUX:  1.   In chemistry and metallurgy, a substance that promotes the fusing
     of minerals or metals or prevents the formation of oxides.  2.  A substance
     added to a solid to increase its fusibility.   3.  A substance to reduce
     melting temperature.   4.  Any chemical or rock added to an ore to assist
     in its reduction by heat, such as limestone with iron ore in a blast fur-
     nace.

FLY ASH:  In incineration, suspended incombustible particles, charred paper,
     dust, soot, or other partially incinerated matter, carried in the gaseous
     products of combustion.

FOOD-GRADE ACID:  Phosphoric acid that has been treated for removal of heavy
     metals and is suitable for -use in food products.

FORCED DRAFT:  See draft.

FRACTIONAL DISTILLATION:  The separation of the components of a liquid mixture
     by vaporizing and collecting the fractions which condense in different
     temperature ranges.

FUEL:  Any form of combustible matter—solid, liquid, vapor, or gas, excluding
     combustible refuse.

FUEL-BURNING EQUIPMENT:  Any furnace, boiler, apparatus, stack, and all appur-
     tenances thereto, used in the process of burning fuel for the primary pur-
     pose of producing heat or power by indirect heat transfer.

FUGITIVE DUST:  Solid airborne particulate matter emitted from any source other
     than a flue or stack.

FUME:  Fine solid particles predominately less than 1 micro-meter in diameter
     suspended in a gas.  Usually formed from high-temperature volatilization
     of metals, or by chemical reaction.

FUMIGATION:  Fumigation is an atmospheric phenomenon in which pollution, which
     has been retained by an inversion layer near its level of emission, is
     brought rapidly to ground level when the inversion breaks up.  High con-
     centrations of pollutant can thus be produced at ground level.

FUMING NITRIC ACID:  A mixture of 98 percent nitric acid and an equilibrium
     mixture of nitrogen tetroxide Q$20iJ and nitrogen dioxide CNO,).

FURNACE OIL:  A distillate fuel primarily intended for domestic heating use.
     No. 1 commercial standard grade is Intended for "vaporizing" burners re-
     quiring a volatile fuel, whereas No. 2 and No. 3 commercial standard
     grades are less volatile, and are thus usable in the "atomizing" type of
     burners.

-------
                                      G.15
                                       G

GAGE PRESSURE:  The pressure above  atmospheric  pressure,  expressed  as  pounds
     per square inch, gage  (psig).

GOB. PILES:  Large piles of  low-combustilble  refuse  from  coalmine  preparation
     plants.  Fires may develop  in  these waste material piles  by  liberation of
     heat through slow oxidation, until ignition temperature is reached  Csee
     also culm).

GRAIN LOADING:  Concentration of particulates in exhaust  gas,  expressed  as
     grains per standard cubic foot (7000 grains = 1 pound)  Csee  also  dust
     loading).

GRAVITATIONAL SETTLING:  Removal of material from  the atmosphere  due to  the ac-
     tion of gravity.

GREEN COKE:  Coke that has  not been fully cooked.   Green  coke  produces exces-
     sive emissions when pushed  from a coke oven.

GREEN FEED  (CALCINED FEED):  Not fully processed or treated  feed.

GROUT (GROUTING):  A pumpable slurry of portland cement or a mixture of  port-
     land cement and fine sand commonly forced  into a borehole to seal crevices
     in a rock to prevent ground water from seeping or  flowing into an excava-
     tion or for extinguishing underground  fires.


                                      H

HEAT ISLAND EFFECTS:  Meteorological characteristics of an urban area or large
     industrial complex which differentiates it from its  surroundings.   Gener-
     ally, the urban area has (1) higher temperatures,  C2) a less stable noc-
     tournal lapse rate immediately above the surface,  (3) lower relative
     humidities, (4) greater cloudiness, (5) more  frequent fogs,  (6) less in-
     coming radiation, (7)  lower wind  speeds, and  (8) greater  precipitation.

HEAT RELEASE RATE:  The amount of heat liberated during the  process of combus-
     tion and expressed in  Btu per  hour per cubic  foot  of internal furnace vol-
     ume in which the combustion takes place.

HOG FUEL BOILER:  See bark  boiler.

HOT BLAST MAIN:  A duct lined with  refractory material, through which hot air
     passes from a hot blast stove  to the bustle pipe of a blast furnace.

HOT WELL:  A reservoir for  receiving warm condensed steam drawn from a con-
     denser.

-------
                                     G.16
HYDRATOR-ABSORBER:   A single or double tower in which phosphorus pentoxide is
     hydrated to phosphoric acid and the resulting acid mist is absorbed.

HYDRAULIC FLY ASH HANDLING:  A system using water-filled pipes or troughs in
     which fly ash is conveyed by means of gravity, water jets, or centrifugal
     pumps.

HYDROCARBONS:  Organic compounds which- consist solely of carbon and hydrogen
     and occur in petroleum, natural gas and coal.

HYDROCRACKING:  A low-temperature catalytic method of converting crude oil,
     residual oil,  petroleum tar, and asphalt to high-octane gasoline, jet fuel,
     and/or high-grade fuel oil.  The process combines cracking, hydrogenation,
     and isomerization.

HYDRODESULFURIZATION:  A desulfurization process in which the oil is heated
     with hydrogen.

HYDROGENATION:  The chemical addition of hydrogen to a material at high pres-
     sure in the presence of a catalyst.

HYDROMETALLURGY:  The treatment of ores, concentrates, and other metal-bearing
     materials by wet processes, usually involving the solution of some compo-
     nent, and its subsequent recovery from the solution.

HYDROTREATING:  A treating process using hydrogen for the desulfurization of
     cracked distillates.
IMPINGEMENT:  In air sampling, impingement refers to a process for the collec-
     tion of particulate matter in which, the gas being sampled is directed
     forcibly against a surface.  1.  Dry impingement:  the process of impinge-
     ment in the gas stream where particulate matter is retained upon the sur-
     face against which the stream is directed.  The collecting surface may
     be treated with a film of adhesive.  2.  Wet impingement:  the process of
     impingement in a liquid which retains the particulate matter.

IMPINGEMENT SEPARATORS:  Devices using the principle that when a gas stream
     carrying particulate matter impinges on a body, the gas is deflected
     around the body, while the particles, because of their greater inertia,
     tend to strike the body and be collected on its surface.  The bodies may
     be in the form of plates, cylinders, ribbons, or spheres.

INCINERATION:  The process of burning solid, semi-solid, or gaseous combustible
     waste.

-------
                                     G.17
INCINERATOR:  An apparatus designed to burn solid, semi-solid, or gaseous waste
     leaving little or no combustible material  Csee multiple chamber incinera-
     tor) .

INERTIAL SEPARATOR:  The most widely used device for collecting medium and
     coarse sized particles.  Inertial separators operate by the principle of
     imparting centrifugal force to the particle to be removed from the car-
     rier gas stream.

INTERRUPTIBLE GAS:  Gas sold whereby the seller may curtail or stop delivery,
     generally at his option.  The gas customer under these conditions is ex-
     pected to have standby equipment capable of taking over 100% of his needs
     by an alternate fuel.

INVERSION:  A stratum in the atmosphere through which the temperature increases
     with height.  The layer is thermally stable and vertical motion within the
     layer is suppressed.

INVERSION BASE:  The lowest height in the atmosphere at which the temperature
     ceases to decrease with height.

ISOMERIZATION:  A reaction which alters the fundamental arrangement of the
     atoms in a molecule without adding or removing anything from the original
     material.  In the petroleum industry, straight-chain hydrocarbons are con-
     verted catalytically to branched-chain hydrocarbons of substantially high-
     er octane number by isomerization.
JIG:  A device which separates coal from foreign matter by means of their dif-
     ference in specific gravity in a water medium.  The water pulsates up and
     down causing the heavy material to work to the bottom.


                                      K

KETTLE:  1.  An open-top vessel used in carrying out metallurgical operations
     on low-melting-point metals; for example, in dressing and desilverizing
     lead.  2.  An open or (usually) closed vessel for preparing paints, var-
     nishes, and resins.

KILN:  A furnace in which the heating operations do not involve fusion.  Kilns
     are most frequently used for calcining, and free access of air is permit-
     ted.  The raw materials may be heated by the combustion of solid fuel with
     which they are mixed, but more usually they are heated by gas or the waste
     heat from other furnaces.

-------
                                     G.18
KILN GAS:  Hot effluent gases from a kiln.  Unless controlled, these gases can
     be the largest source of partlculates In a plant.

KNOCKOUT DRUM:  A drum or vessel constructed with baffles through which a mix-
     ture of gas and liquid is passed to disengage one from the other.  As the
     mixture comes in contact with the Baffles, the impact frees the gases and
     allows them to pass overhead; the heavier substance falls to the bottom of
     the drum.
LAPSE RATE:  The decrease of temperature with altitude.

LAUNDER:  A trough, channel, or gutter usually of wood, by which water is con-
     veyed.  Specifically, in mining, a chute or trough for conveying powered
     ore, or for carrying water to or from the crushing apparatus.

LEACHING:  Extracting a soluble metallic compound from an ore by selectively
     dissolving it in a suitable solvent, such as water, sulfuric acid, hydro-
     chloric acid, etc.

LIGNITE COAL (BROWN COAL):  A brownish-black variety of coal, usually high in
     moisture and low in Btu's.  Lignite is one of the earlier stages in the
     formation of bituminous coal.
                                      M

MANIFOLD:  A pipe or header for collecting a fluid or gas from, or distributing
     a fluid or gas to, a number of pipes or tubes.

MANUFACTURED GAS:  Fuel gas manufactured from coal, oil, etc., as differenti-
     ated from natural gas.

MATERIAL BALANCE:  An accounting of the weights of material entering and leav-
     ing a process.

MATTE:  A metallic sulfide mixture formed in smelting sulfide ores of copper,
     lead, and nickel.

MECHANICAL, CENTRIFUGAL SEPARATORS:  A device for separating particulates.  A
     rotating fan blade exerts a large centrifugal force on the particulates,
     ejecting them from the tips of the blades to a skimmer bypass leading into
     a dust hopper.

MECHANICAL SCRUBBER:  A scrubber in which the water spray is generated by a ro-
     tating element or disk {see also scrubber).

MECHANICAL TURBULENCE:  In meteorology, the induced eddy structure of the at-
     mosphere due to the roughness of the surface over which the air is passing
     The height and spacing of the elements causing the roughness will affect
     the turbulence.

-------
                                     G.19
MERCAPTANS:  Organic compounds having the general formula R-SH  (where R repre-
     sents any hydrocarbon radical) which are analogous to the  alcohols and
     phenols but which contain sulfur in place of oxygen.  The  simpler mercap-
     tans have strong, repulsive odors.

MESH:  The number of holes per linear unit in a sieve or gauze, or the space
     between the wires of the sieve expressed in inches or millimeters.

METRIC TON:  2204.6 pounds or 1000 kilograms.

MIST:  A suspension of any finely divided liquid in a gas.

MODIFIED COAL:  Coal of a stoker size containing a controlled percentage of
     fines.

MULTICYCLONE CALSO MULTIPLE CYCLONE OR MULTICLONE): A dust collector consisting
     of a number of cyclones, operating in parallel, through, which the volume
     and velocity of gas can be regulated by means of dampers to maintain dust-
     collector efficiency over the load range.

MULTIPLE-CHAMBER INCINERATOR:  Any incinerator consisting of a  primary combus-
     tion chamber, mixing chamber, and secondary combustion chamber in series.
     The chambers are separated by refractory walls, and interconnected by gas
     passage ports.

MULTIPLE-HEARTH TYPE ROASTER:  See roasting furnace.

MUNICIPAL INCINERATOR:  An incinerator owned or operated by government or by a
     person who provides incinerator service to government or others; a device
     designed for and used to burn waste materials of any and all types.


                                      N

NATURAL GAS:   Gaseous forms of petroleum occurring in nature and used directly
     as a fuel.  Natural gas consists of mixtures of hydrocarbon gases and va-
     pors, the more important of which are methane, ethane, propane, and butane.

NET TON:  2000 pounds (sometimes known as a "short ton").

NITROGEN OXIDES:  A general term pertaining to a mixture of nitric oxide (NO)
     and nitrogen dioxide (NO.).


                                      0

ODORANT:  A gaseous nuisance that is offensive or objectionable to the smell.

-------
                                     G.20
ODOR INTENSITY:  The numerical or verbal indication of the strength of an odor.

ODOR PERVASIVENESS:  The ability of an odor to diffuse into a large volume of
     air and still continue to possess a detectable intensity.  A pervasive odor
     is one whose odor intensity changes very little on dilution.

ODOR QUALITY:  A verbal description of an odor.  The quality -may be described
     in terms of such familiar odorants as coffee, onions, lemons, or by asso-
     ciating an unfamiliar odor with a familiar odor.

ODOR THRESHOLD:  The lowest concentration of an odor in air that can be detected
     by a human.

ODOR UNITS:  That quantity of odor necessary to contaminate one cubic foot of
     air to threshold or barely perceptible level.  The number of odor units
     is equal to the volumes C.scf) of air necessary to dilute the concentration
     of odorant in one volume Cscf) of air to the threshold concentration.

OIL BURNER:  Any device for the introduction of vaporized or atomized fuel oil
     into a furnace.

OIL-EFFLUENT WATER SEPARATOR:  Any tank, box, sump, or other container in which
     any petroleum product entrained in water is physically separated and re-
     moved prior to out-fall, drainage, or recovery of the water.

OITICICA COIL):  A drying oil obtained from the kernels of the fruit of the
     oiticica tree that is similar to tung oil in many properties and is used
     chiefly in varnishes, paints, and printing inks.

OLEORESIN:  A varnish or paint vehicle, made of plant  oils and resins, usually
     cooked.

OLEUM (FUMING SULFURIC ACID):  A heavy, oily, strongly corrosive liquid that
     consists of a solution of sulfur trioxide in anhydrous sulfuric acid.  It
     fumes in moist air and reacts violently with water.

ONSTREAM TIME:  The length of time a unit is in actual production.

OPACITY:  The degree to which emissions reduce the transmission of light and
     obscure the view of a distant object.

OPEN BURNING:  The burning of any matter in such a manner that the products of
     combustion are emitted directly into the ambient  air without passing
     through a stack, duct, or chimney.

OPEN HEARTH FURNACE:  Reverberatory furnace, containing a basin-shaped hearth,
     for melting and refining suitable types of pig iron, iron ore, and scrap
     for steel production.

-------
                                     G.21
ORE AND LIME BOIL:  Reactions which occur in an open hearth furnace when carbon
     monoxide is produced by the oxidation of carbon.  Ore boil is a violent
     agitation of the metal as it escapes during this process; lime boil occurs
     when the limestone decomposes and the carbon dioxide gas escapes.  The
     second reaction begins before the first is completed.

ORGANIC SULFUR:  The difference between the total sulfur in coal and the sum of
     the pyritic sulfur and sulfate sulfur.

ORGANOLEPTIC:  Affecting or making an impression upon one or more of the sense
     organs.

ORIFICE SCRUBBERS:  Devices for the removal of particulates from gas streams in
     which the flow of air through a restricted passage partially filled with
     water causes the dispersion of the water and consequent wetting and col-
     lection of the particulates.

ORSAT:  An apparatus used for analyzing flue gases volumetrically.

OVERBURDEN:  Material of any nature, consolidated or unconsolidated, that over-
     lies a deposit of useful material, ores, or coal, especially those deposits
     that are mined from the surface by open cuts.

OVERFIRE:  Air for combustion admitted into the furnace at a point above the
     fuel bed.

OXIDATION:  The act or process of combining oxygen with a substance, with or
     without the production of a flame.

OXYGEN LANCING:  In steel making, a procedure in which oxygen is injected into
     the bath of molten metal through a water cooled lance.  The oxygen oxidizes
     carbon, silicon, manganese, and some iron in exothermic reactions.  The
     procedure materially shortens the time needed to tap the furnace.
PACKED COLUMN (PACKED SCRUBBER OR PACKED TOWER):  A vertical column used for
     distillation, absorption, and extraction, containing packing; e.g., Raschig
     rings, Berl saddles, or crushed rock, which provide a large contacting
     surface area between phases.  Normally, gas flow is countercurrent to
     liquid flow.

PAN:  Peroxyacyl nitrates.  Secondary pollutants formed in photochemical oxida-
     tion and major eye irritants of photochemical smog.

PARTICLE CONCENTRATION:  Concentration expressed in terms of number of particles
     per unit volume of air or other gas.

-------
                                     G.22
PARTICULATE MATTER:  Any dispersed matter, solid or liquid, in which, the indi-
     vidual aggregates are larger than single small -molecules CO.0002 -micro-
     meters) but smaller than 500 micro-meters.

PERCOLATOR:  A device used in rendering plants for the separation of dry pro-
     teinaceous crackling from the clear moisture-free tallow.  They are gener-
     ally perforated pans which, allow- the tallow to drain away from the crack-
     lings.

PERFORMANCE TEST:  Measurements of emissions used for the purpose of determin-
     ing compliance with a standard of performance.

PETROCHEMICAL INDUSTRY:  A branch of the petroleum industry in which refined
     crude oil is manufactured into various chemicals.

PETROLEUM COKE:  See coke, petroleum.

PHOTOCHEMICAL REACTION:  A chemical reaction which involves either the absorp-
     tion or emission of radiation in the form of light energy.

PLUME:  The path taken by the continuous discharges of products from a chimney
     or stack.  The shape of the path and the concentration distribution of
     gas plumes is dependent on turbulence of the atmosphere.

POINT SOURCE:  Any stationary emitting point or plant/facility whose summation
     of emitting points totals 100 tons (or some other fixed amount) per year
     of any pollutant in a given region.

POLYCYCLIC MOLECULE:  A molecule containing two or more fused rings (as in
     anthracine).

POLYMERIZATION:  1.  A reaction combining two or more molecules to form a
     single molecule having the same elements in the same proportions as in the
     original molecules.  2.  The union of light olefins to form hydrocarbons
     of higher molecular weight.  The process may be thermal or catalytic.

POLYNUCLEAR AROMATIC HYDROCARBONS:  Compounds consisting of two or more aro-
     matic rings which share a pair of carbon atoms.  The simplest and most
     important is naphthalene (C  H ; also polycyclic).
                                10 o
PRECLEANERS:  Collectors of limited efficiency used ahead of the final cleaner.
     If the gas contains an appreciable amount of hard, coarse particles, a
     precleaner can materially reduce erosive wear of the more efficient final
     collector.

PRECURSORS:  Gaseous air pollutants which react with other substances in the
     atmosphere to produce different pollutants; e.g., photochemical reactions
     of NO and NO  with the oxygen of the air which produce ozone.

-------
                                     G.23
PRILLING:  A combination spray drying and crystallization technique used in the
     production of ammonium nitrate.  A hot ammonium nitrate solution is sprayed
     in the top of a tower, and air is blown in at the bottom.  The liquid is
     converted into spherical pellets.

PRIMARY AIR:  In incineration, air which is introduced with the refuse into
     the primary chamber.

PRIMARY EMISSION:  Pollutants emitted directly into the air from identifiable
     sources.

PRIMARY STANDARD:  The national primary ambient air quality standard which de-
     fines levels of air quality which, are necessary to protect public health.

PROCESS WEIGHT:  The total weight of all materials introduced into a source
     operation, including solid fuels, but excluding liquids and gases used
     solely as fuels, and excluding air introduced for purposes of combustion.

PUG MILL:  A machine for mixing water and clay which consists of a long hori-
     zontal barrel within which is a long longitudinal shaft fitted with knives
     which slice through the clay, Tailing it with water which is added by
     sprayers from the top.  The knives are canted to give some screw action,
     forcing the clay along the barrel and out one end.

PUMP, RECIPROCATING:  A positive-displacement type of pump consisting of a
     plunger or a piston moving back and forth within a cylinder.  With each
     stroke of the plunger or piston, a definite volume of liquid is pushed
     out through the discharge valves.

PYRITIC SULFUR:  Sulfur combined with iron, found in coal.

PYROLYSIS:  Chemical change brought about by the action of heat upon a sub-
     stance.

PYROMETER:  An instrument for measuring temperatures beyond the range of thermo-
     meters.
RECOVERY BOILER:  In wood pulping, a combustion unit designed to recover the
     spent chemicals from the cooking liquor and to produce steam for pulping
     and recovery operations.

REDUCTION:  1.  The addition of hydrogen or the abstraction of oxygen from a
     substance.  2.  The extraction of any metal from its ore.

REFINERY GAS:  Any form or mixture of still gas gathered in a refinery from the
     various stills.

-------
                                     G.24
REFINING:  In metallurgy,  the removal of  impurities necessary to produce an
     ingot or alloy of desired specification.   In petroleum, toe process of
     separating, combining,  or rearranging petroleum oil constituents- to pro-
     duce salable products.

REFORMING:  The thermal or catalytic conversion of naphtha into more volatile
     products of higher octane rmmBer.   It represents the total effect of nu-
     merous reactions, such as cracking,  polymerization, dehydrogenation, and
     isomerization, taking place simultaneously.

REFRACTORY:  A ceramic material of a very high melting point with properties
     that make it suitable for such uses; as furnace and kiln linings.

RERUN OIL:  Oil which has  been redistilled.

RESIDUAL:  Heavy oil left  in the still after gasoline and other distillates
     have been distilled off, or residue from the crude oil after distilling
     off all but the heaviest components.

RESISTIVITY:  The property of a body whereby it opposes and limits the passage
     of electricity through it.  Resistivity of dust is an important factor in
     the performance of electrostatic precipitators.  If the resistivity of the
     collected dust is higher than about  2 x 10   ohm-cm, excessive arcing or
     reverse corona can occur, thereby limiting precipitator performance.

REVERBERATORY FURNACE:  A  furnace with a shallow hearth; having a roof that de-
     flects the flame and  radiates heat toward the surface of the charge.  Fir-
     ing may be with coal, pulverized coal,  oil,  or gas.

RINGELMANN CHART:  A standardized chart giving shades of gray by which the
     densities of columns  of smoke rising from stacks may be compared.

ROAST:  To heat to a point somewhat short of fusing, with access to air, so as
     to expel volatile matter or effect oxidation.  In copper metallurgy, ap-
     plied specifically to the final heating which causes self-reduction to oc-
     cur by the reaction between the sulfide and the oxide.

ROASTER:  1.  A contrivance for roasting,  or a furnace for drying salt cake.
     2.  A reverberatory furnace or a muffle used in roasting ore.

ROASTING:  1.  Heating an  ore to effect some chemical change that will facili-
     tate smelting.  2. The heating of solids, frequently to promote a reac-
     tion with a gaseous constituent in the furnace atmosphere.

ROASTING FURNACE:  A furnace in which finely ground ores and concentrates are
     roasted to eliminate  sulfur; heat is provided by the burning sulfur.

RUN OF MINE COAL:  Unscreened bituminous  coal as It comes from the mine.

-------
                                     G.25
SALAMANDER:  A small portable incinerator, or a small portable heater burning
     coke or oil.

SCRUBBER:  A device used to remove entrained liquids and solids from a gas
     stream by passing the gas through, wetted "packing" or spray Csee absorber).

SECONDARY AIR:  Air introduced into a combustion chamber beyond the point of
     fuel and primary air introduction for the purpose of achieving -more com-
     plete oxidation.

SECONDARY STANDARD:  The national secondary ambient air quality which defines
     levels of air quality judged necessary to protect the public welfare from
     any known or  anticipated adverse effects of a pollutant.

SINTERING:  A heat treatment that causes adjacent particles of material to
     cohere or agglomerate at a temperature below- that of complete melting.

SKIMMING PLANT: An oil refinery designed to remove and finish only the lighter
     constituents  from the crude oil, such as gasoline and kerosene.  In such a
     plant the portion of the crude remaining after the above products are re-
     moved is usually sold as fuel oil.

SKIP HOIST, INCLINED:  A bucket or can operating up and down,  receiving, ele-
     vating, and discharging bulk materials.

SLAG:  The non-metallic top layer which separates from the metallic products in
     smelting of ores.

SLOP OR SLOP OIL:   A term rather loosely used to denote odds and ends of oil
     produced at various places in a plant, which must be rerun or further pro-
     cessed in order to get in suitable condition for use.  When good for noth-
     ing else, such oil usually goes into pressure-still charging stock, or to
     coke stills.

SMELT:  In wood pulping, the molten chemicals from the kraft recovery furnace
     consisting mostly of sodium sulfide and sodium carbonate.

SMELTING:  Any metallurgical operation in which metal is separated by fusion
     from impurities with which it may be chemically combined or physically
     mixed, such as in ores.

SMOKE:  Small gas—borne particles resulting from incomplete combustion, con-
     sisting predominantly but not exclusively of carbon, ash, and other com-
     bustible material, and present in sufficient quantity to be observable.

SMOKE CANDLE(S):  Apparatus used in collecting acid mists.  Tubes or candles

-------
                                     G.26
     made from glass or plastic fibers  are pressed into pads with thicknesses
     up to 2 inches and mounted in Banks.   Efficiency is much increased when
     the glass is  treated with silicone oil.to repel water,  or when normally
     water-repellent plastic is -used.

SMOKE UNIT:  The number of "smoke units" is obtained by multiplying the smoke
     density in Ringelmann numbers by  the time of  occurrence in minutes.  For
     the purpose of this calculation,  a Ringelmann density- reading is made at
     least once per minute during the  period of oBservation.  The sum of the
     Ringelmann density readings (made once per minutej during the period of
     observations  would equal the number of smoke  units.

SOILING:  Visible  damage to materials  by deposition of air pollutants.

SOOT:  Agglomerated particles consisting mainly of carbonaceous material.

SOUR:  Gasolines,  naphthas, and refined oils are said to be "sour" if they show
     a positive "doctor test"; i.e., if they contain hydrogen sulfide and/or
     mercaptans.  Sourness is directly connected with odor,  while a "sweet"
     gasoline has  a good odor.

SOURCE:  Any property,  real or personal, or person contributing to air pollution.

SOURCE SAMPLE:  A  sample of the emission from an air contamination source, col-
     lected for analysis from within a stack.

SPARK ARRESTOR: A screenlike device to prevent sparks, embers, and other ig-
     nited materials larger than a given size from being expelled to the atmos-
     phere.

SPEISS:  Metallic  arsenides and antimonides smelted from cobalt and lead ores.

SPRAY CHAMBER:  The simplest type of scrubber consisting of  a chamber in which
     spray nozzles are  placed.  They are used extensively as gas  coolers be-
     cause they have a  low collection  efficiency for anything but coarse particles,

STABILITY CSTATIC  STABILITY):  The state of the atmosphere when it is stable
     relative to vertical displacements.

STACK OR CHIMNEY:   Any  flue, conduit,  or duct arranged to conduct an effluent
     to the open air.

STACK SPRAY:  A nozzle  or series of nozzles installed in a stack above the
     breeching, used to inject wetting agents at high pressure to suppress the
     discharge of  particulate matter from the stack.

STANDARD CONDITIONS: For source testing, 70°F C21.1°CI and 29.22" Hg (760mm
     Hg) ; for aix  quality measurements,' 77°F C25°C) and 29^.92" Hg (760mm Hg) ;

-------
                                     G.27
     for chemistry, 273. 1°K (0°C) and one atmosphere (760ram Hg] ;  for petroleum
     refining, 60°F C15.55°C)  and 14.7 psi (760mm Hg) .

STATIONARY SOURCE:  Any non-mobile building, structure, facility, or installa-
     tion which emits or may emit any- air pollutant.

STEAM DISTILLATION:  Introduction of "open" steam into  the liquid during dis-
     tillation to assist in vaporizing the volatiles at a lower temperature.

STILL:  A closed chamber, usually cylindrical, in which heat is applied to a
     substance to change it into vapor, with or without chemical  decomposition.
     The substance, in its -vapor form, is conducted to  some cooling apparatus
     where it is condensed, liquefied, and collected in another part of the unit,

STOCK:  In general, any oil which is to receive further treatment before going
     into finished products.

STOKER:  A machine for feeding coal into a furnace, and supporting it there
     during the period of combustion.  It may also perform other  functions,
     such as supply air, control combustion, or distill volatile  matter.  Modern
     stokers may be classified as overfeed, underfeed,  and conveyor.  Any mech-
     anical device that feeds fuel uniformly onto a grate or hearth within a
     furnace may be termed a "stoker."

STOPING:  In mining, any process of excavating ore which has been made acces-
     sible by shafts and drifts.

STRAIGHT-RUN DISTILLATION:  Continuous distillation which separates the products
     of petroleum in the order of their boiling points  without cracking.

STRIPPER:  Equipment in which the lightest fractions are removed from a mixture.
     In a natural-gasoline plant, gasoline fractions are stripped from rich oil.
     In the distillation of crude petroleum, light fractions are stripped from
     the various products.

SUBSTITUTION:  A chemical reaction in which one or more atoms or  groups of a
     molecule are replaced by equivalent atoms or groups to form at least two
     products, especially the replacement of hydrogen In an organic compound by
     another element or group.

SULFIDITY:  An expression of the percentage makeup of chemical kraft cooking
     liquor obtained by the formula

                                                  , 100
                                     Na2S + NaOtt

     where the sodium compounds are expressed as
SUPERPHOSPHATE:  Products obtained by mixing phosphate rock with either sul-
     furic or phosphoric acid, or both.

-------
                                     G.28
SURFACE CONDENSERS:  A condenser in which the coolant does not contact the
     vapors or condensate.   Most are of the tube and shell type.  W/ater flows
     inside the tubes and -vapors condense on the shell side.

SURGE TANK:  A storage reservoir at the downstream end of a feeder pipe to ab-
     sorb sudden rises of pressure and to furnish, liquid quickly during a drop
     in pressure.

SWEETENING:  The process by which petroleum products are improved in odor and
     color by oxidizing or  removing the sulfur—containing and -unsaturated com-
     pounds.

SYNERGISM:  Cooperative action of discrete agents such that the total effect is
     greater than the sum of the two effects taken Independently.

SYNTHETIC CRUDE:  The total liquid, multi-component mixture resulting from a
     process involving molecular rearrangement of charge stock.  Term commonly
     applied to the product from cracking, reforming, -wisbreaklng, etc.
TAIL OIL:  That portion of an oil which vaporizes near the end of the distil-
     lation; the heavy end.

TAIL GAS:  The exhaust or waste gas from a process.

TALLOW:  The rendered fat of animals that is white and almost tasteless when
     pure, composed of glycerides of fatty acids containing a large proportion
     of palmitic acid and stearic acid, and that is used chiefly in making
     soap, glycerol, margarine, candles, and lubricants.

TAPPING:  Removing molten metal from a furnace.

TEMPERATURE INVERSION:  An atmospheric layer in which temperature increases
     with altitude.  The principal characteristic of a temperature inversion is
     its marked static stability, so that very little turbulent exchange can
     occur within it (see also Inversion).

THEORETICAL AIR:  The exact amount of air (stoichiometric air) required to sup-
     ply the oxygen necessary for the complete combustion of a given quantity
     of a specific fuel or refuse.

THERMAL TURBULENCE:  Air movement and mixing caused by temperature differences.

TOPPED CRUDE PETROLEUM:  A residual product remaining after the removal, by
     distillation, of an appreciable quantity of the more volatile components
     of crude petroleum.

-------
                                     G.29
TOPPING:  The distillation of crude oil to remove light fractions only.

TOTAL REDUCED SULFUR COMPOUNDS (TRS):  Malodorous gases produced in the wood
     pulping industry exclusive of sulfur oxides.  TRS usually includes hydro-
     gen sulfide (H S), methyl mercaptan CCtLSH), dimethyl sulfide (CH_SCH ),
     and dimethyl dlsulfide (CR-jSSCK,) .  The concentration of TRS is usually
     expressed as H^S regardless of the constituent compounds.

TURBULENCE:  Atmospheric motions which produce a thorough horizontal and verti-
     cal mixing of the air.

TURNAROUND:  The time between shutting down and starting up of process equip-
     ment for repair or maintenance.

TUYERES:  Openings or nozzles in a metallurgical furnace through which air is
     blown as part of the extraction or refining process.

TWADDELL DEGREES (°TW):  A measure of acid density and strength:

                  °TW = sp. gr. (60°/60°F)
                              0.005

     Each twaddell degree corresponds to a specific gravity interval of 0.005.
ULTIMATE ANALYSIS (OF COAL):  Contains the following, expressed in percent by
     weight:
Carbon
Hydrogen
Sulfur
Oxygen
Nitrogen
Moisture
Ash
CC) %
CH2) %
(S) %
(02) %
(N2) %
(H20) %
(H00) %
                                             100.0%

UNDERFEED STOKER:  A stoker consisting of a trough or pot-shaped report into
     which coal is forced by an endless screw or ram.  Coal is fed to the fire
     zone by being pushed up from underneath.

UNIT OPERATION:  1.  Methods by which raw materials may be altered into states,
     such as vapor, liquid, or solid without being changed into new substances
     with different properties and composition.  2.  Recognition, study, appli-
     cation and control of the principles and factors utilized in a distinct
     and self-contained process (for example, filtration).  This avoids the
     duplication of effort which attends the study of similar processes as
     though each process involved a unique set of principles.

-------
                                     G.30
UNIT PROCESS:  1. Reactions where raw materials undergo chemical change.  2.
     See unit operation C2)•

UREA FORMS:  A urea-formaldehyde reaction product that contains more than one
     molecule of urea per molecule of formaldehyde.
VACUUM JET (STEAM JET EJECTOR):   A fluid nozzle that discharges a high velocity
     jet stream across a section chamber that is connected to the equipment to
     be evacuated.  The gas in the chamber is entrained by the jet stream.

VAPOR:  The gaseous phase of a substance that generally exists as a liquid or
     solid at room temperature.

VAPOR PLUME:   The stack effluent consisting of flue gas made visible by con-
     densed water droplets or mist.

VAPOR RECOVERY SYSTEM:  System used in petroleum refining for separating a
     mixed charge of miscellaneous gases and gasolines into desired intermedi-
     ates for further processing.

VENTURI SCRUBBER:  A type of high energy scrubber in which the waste gases pass
     through a tapered restriction (venturi) and impact with low-pressure water.
     Gas velocities at the restriction are from 15,000 to 20,000 fpm and pres-
     sure drops from 10 to 70 inches water gage.

VISBREAKING:   Viscosity breaking; lowering or "breaking" the viscosity of resi-
     dual oil by cracking at relatively low temperatures.

VISIBILITY:  In United States weather observing practice, the greatest distance
     in a given direction at which it is just possible to see and identify with
     the unaided eye (a) in the daytime, a prominent dark object against the
     sky at the horizon, and (b) at night, a known, preferably unfocused,
     moderately intense light source.  After visibilities have been determined
     around the entire horizon circle, they are resolved into a single value
     of prevailing visibility for reporting purpose.

VISIBLE EMISSION:  An emission of air pollutants greater than 5 percent opacity
     or 1/4 Ringelmann.

VOLATILE OR VOLATILE MATTER:  1.  The gasoline constituents that can be driven
     off liquids and solids by the application of heat.  2.  Specifically for
     coal, that portion which is driven off in gas or vapor form when coal is
     subjected to a standardized temperature test.

VOLATILE ORGANIC COMPOUNDS:  Any compound containing carbon and hydrogen or
     containing carbon and hydrogen in combination with any other element which
     has a vapor pressure of 1.5 pounds per square inch absolute or greater
     under actual storage conditions.

-------
                                     G.31
                                    tf-X-Y-Z

WASTE HEAT BOILERS:  Boilers which utilize the heat  of  exhaust  gas  or  process
     gas to generate steam or to heat water.

WEAK WASH:  In wood pulping, a liquid stream in  the  kraft  process which results
     from washing of the lime mud.

WET COLLECTORS:  Devices which use a variety of  methods to wet  the  contaminant
     particles in order to remove them from the  gas  stream Csee scrubbers) .

WET FILTERS:  A spray chamber with filter pads composed of glass fibers,  knit-
     ted wire mesh, or other fibrous materials.  The dust  is  collected on the
     filter pads.

WHITE LIQUOR:  Cooking liquid used in the wood pulping  industry.  Kraft process:
     consists of approximately 1/3 sodium sulfide  (Na S) and  2/3 sodium hydroxide
     (NaOK) .  Sulfite process: consists of sulfurous acid  plus  one  of  the fol-
     lowing: calcium bisulfite, sodium bisulfite,  magnesium bisulfite, or
     ammonium bisulfite.
    U. S. GOVERNMENT PRINTING OFFICE: 1972	746763/^111

-------