EXHAUST GASES FROM COMBUSTION AND INDUSTRIAL PROCESSES
Engineering-Science, Incorporated
Washington, D. C.
2 October 1971
NATIONAL TECHNICAL INFORMATION SERVICE
Distribute!. • •'to foster, serve and promote the
nation's economic development
and technological advancement.'
U.S. DEPARTMENT OF COMMERCE
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204 SGI!
EXHAUST GASES FrIC"
icHVICE i
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EXHAUST GASES FROM
COMBUSTION AND INDUSTRIAL PROCESSES
A Report Prepared For The
Diviaion of Compliance
Bureau of Stationary Source Pollution Central
Office of Air Programs
U.S. Environmental Protection Agency
Technical Center
Durham, North Carolina
Contract No. EHSD 71-36
Engineering Science, Inc.
Washington, D.C.
October 2. 1971
>?
*
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BIBLIOGRAPHIC DATA )• Report No. 2. 3.
SHEET APTD- 0805
4. Title and Subtitle 5.
EXHAUST GASES FROM COMBUSTION AND INDUSTRIAL
PROCESSES 6.
7. Amhor(s) 8.
9. Performing Organization Name and Address 1C
Engineering Science, Inc.
Washington, D. C. 1
12. Sponsoring Organization Name and Address 1
Division of Compliance
Bureau of Stationary Source Pollution Control
Office of Air Programs
Technical Center li
Durha«, North Carolina 27701
15. Supplementary Notes DISCLAIMER - This report was turnisnea c
Programs by Engineering Science, Inc., Washington, D.
fillment of Contract No. EHSD 71-36
Recipient's Accession No.
Report Date
Ictober 2, 1971
Performing Organization Rept.
No.
. Pro|ect/Task/Work Unit No.
. Contract/Grant No.
EHSD 71-36
i Type of Report * Period
Covered
Final
u
C. 20201 in ful-
16. Abstracts
A report is presented of a project which proposed to assemble infornation on exhaust
gas flow rates from selected air pollution sources. The objectives of the project
were: 1) to determine the extent to which operating variables and process through
put rates affect exhaust gas conditions and enission rates, and 2) to recommend
exhaust gas conversion factors to be used in the develop-er.t of irnplerrentation plans
for air quality control regions. The sccpe of the project required conversion factors
to be developed for 76 major corhbustior. and industrial processes, "or each source
category, four parameters were evaluated: gas flow rate, gas temperature, gas velocity
and stack height .*\ The source categories are as follows: stationary fuel combustion ;
refuse incineration; chemical process industry ; food and agricultural industry; metal-
lurgical industry; mineral products industry; petroleum refinerv; pulp and paper in-
dustry;- and solvent evaporation and gasoline marketing.
Air pollution Incinerators
Emission Chemical industry
Sources Food industry
Exhaust gases Metal industry
Flow rate Minerals
Temperature Petroleum industry-
Velocity Paper industry
Stacks (exhaust) Solvents
Fuels Gasoline
Combustion Marketing
17b. Identider./Opio-Ended Terns
Stationary sources
17e- COSATI Field/Group ^jg
18. Availability Statement IT". Security Class
Report)
1 1 i - - i V •• UHC1.ASSII
Ulillllll Led A JO. Security Class
\ Pace
_ tacLASStl
(Tbis 21- No. of Pages
-IED U3fi
(This 22. Ptice
•JED
PREFACE
This report was prepared under contract for the Office of Air Programs,
Environmental Protection Agency (EPA) by Engineering-Science, Inc. to assist
the federal government in carrying out its responsibilities under the Clean
Air Act of 1970. Specifically, the purpose of this project was to assemble
into one report information on exhaust gas flow rates from selected air
pollution sources. The intention of the report was to help the EPA evaluate
specific details of state implementation plans and to estimate the impact of
large sources on local air quality even when details of the source were lack-
ing. However, it is obvious to the investigators that state and local agencies
also will be able to use this document as support for their emission inventory
and enforcement activities.
U5COW»M-OC 4O32»-P
-------
ACKNOWLEDGMENTS
TABLE of CONTENTS
In completing this investigation, there were many people, other than
the principal authors, who made significant contributions.
We wish to acknowledge the guidance and direction provided by the
OAF project officers and their assistants, Messers Anthony Cortege,
Ted Creekmore and Mark Harris. They were able to provide data which
was not readily available from other sources and they provided help in
polishing up the many draft reports.
Throughout the project, help was obtained and data was secured from
several of the trade associations. The State air pollution control agencies
in New Jersey, New York, Maryland, and Missouri also provided valuable
data which helped make this project a success.
In Engineering-Science, Inc., M. Dean High was the principal investi-
gator and Michael E. Lukey was project Manager. Other staff members, who
worked part-time on this project, included John M. Craig, Ph.D., Gary Thorn,
J.K. Allison, Terrence A, LiFuma, and Franklin Meadows.
The typing of this report was completed by Mrs. Linda Arrasmith,
whose diligence was especially appreciated.
I. INTRODUCTION AND SUMMARY
II. STATIONARY FUEL COMBUSTION
1. Anthracite Coal Combustion
2. Bituminous Coal Combustion
3. Residual Fuel Oil Combustion
4. Distillate Fuel Oil Combustion
5. Natural Gas Combustion
6. Liquefied Petroleum Gas Combustion
7. Wood Waste Combustion in Boilers
References
III. REFUSE INCINERATION
1. Municipal Incineration
2. Industrial-Commercial Incineration
3. Domestic Incineration
4. Pathalogical Incineration
5. Auto Body Incineration
6. Conical Burners
7. Open Burning
References
IV. CHEMICAL PROCESS INDUSTRY
1. Ammonia Plant
2. Carbon Black Plant
3. Charcoal Plant
it. Chlorine Plant
5. Hydrofluoric Acid Plant
6. Sitric Acid Plant
7. Paint and Varnish Plant
8. Phosphoric Acid Plant
9. Phthalic Anhydride Plant
10. Plastics Plant
11. Printing Ink Plant
12. Soap and Detergents Plant
13. Sulfuric Acid Plant
14. Synthetic Fibers Plant
15. Synthetic Rubber Plant
Reference
Page
1-1
II-l
11-13
11-32
11-44
11-50
11-58
11-60
11-67
III-l
111-12
111-19
111-31
111-34
111-36
111-40
111-45
IV-1
IV-5
IV-10
IV-14
IV-19
IV-22
IV-29
IV-34
IV-48
IV-56
IV-60
IV-62
IV-67
IV-73
IV-76
IV-80
11
-------
V. FOOD AND AGRICULTURAL INDUSTRY
1. Alfalfa Dehydrating Plant
2. Coffee Roasting Plant
3. Cotton Ginning Process
4. Feed and Grain Mills
5. Fish Meal Processing
6. Fermentation Processes
7. Meat Smokehouse
8. Starch Manufacturing Plant
Reference
VI. METALLURGICAL INDUSTRY
1. Primary Aluminum Smelters
2. Primary Copper Smelters
3. Iron and Steel Mills
4. Primary Lead Smelters
5. Primary Zinc Smelters
6. Metallurgical Coke Manufacture
7. Secondary Aluminum Smelting
8. Secondary Brass and Bronze Smelting
9. Gray Iron Foundry
10. Secondary Lead Smelting
11. Magnesium Melting
12. Steel Foundry
13. Secondary Zinc Processes
Reference
VII. MINERAL PRODUCTS INDUSTRY
1. Asphalt Roofing Manufacture
2. Asphaltic Concrete Batch Plant
3. Bricks and Related Clay Products Mfg.
4. Calcium Carbide Plant
5. Castable Refractures Manufacture
6. Cement Manufacturing Plant
7. Ceramic and Clay Processes
8. Clay and Fly Ash Sintering Plants
9. Concrete Batching Plant
10. Fiber Glass Manufacturing Plant
11. Gypsum Manufacturing Plant
12. Ltme Production Plant
13. Perlite Manufacturing Plant
14. Rock Wool Manufacturing Plant
IS. Rock, Gravel and Sand Processing
16. Glass Manufacturing Plant
17. Frit Manufacturing Plant
Reference
VIII.
PETROLEUM REFINERY
Reference
Page
V-l
V-4
V-12
V-16
V-21
V-25
V-27
V-29
V-30
VI-1
VI-3
VI-12
VI-32
VI-38
Vi-44
VI-48
VI-51
VI-53
VI-59
vr-61
VI-63
VI-66
VI-68
VII-1
VII-5
VII-10
VII-12
VII-16
VII-20
VII-28
VII-32
VII-33
VII-37
VII-41
VII-43
VII-49
VII-53
VII-59
VII-63
VII-65
VII-69
VIII-1
VIII-9
IX. PULP AND PAPER INDUSTRY
1. Kraft Pulp Mills
2. Sulfite Pulp Mills
3. N5SC Pulp Mills
Reference
X. SOLVENT EVAPORATION AND GASOLINE MARKETING
1. Dry Cleaning Plant
2, Surface-Coating Operations
3. Gasoline Marketing
Reference
APPENDIX A
Page
IX-1
IX-14
IX-19
IX-25
X-l
X-10
X-13
A-l
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CHAPTER I
INTRODUCTION AND SUMMARY
The objectives of this project were:
1. To determine the extent to which operating
variables and process throughput rates affect
exhaust gas conditions and emission rates.
2. To recommend exhaust gas conversion factors
to be used in the development of implementation
plans for air quality control regions.
The scope of the project required conversion factors to be developed for 76
major combustion and industrial processes suggested by the Office of Air
Programs. For each source category, four parameters were evaluated: gas flow
rate, gas temperature, gas velocity, and stack height. In addition, a brief
description of the industry, its operating characteristics, including an
input - output relation, and a process description were provided.
A linear regression and the statistical confidence of the conversion factors
were included where sufficient data existed (more than 6 points) Also, the
reliability or credibility of the conversion factors for each source category
was rated from A to E with "A" considered good, "C" average, and "E" poor.
To be considered good a source category had to have numerous exhaust gas field
measurements covering all Important operating variables.
The project did not involve any field measurements. Nor did it include
review or update of air contaminant emission factors, i.e., the emission rate
of dusts, sulfur oxides, etc. Also, the use of control equipment by each
source category was indicated in the discussion. However, collection efficiencies
of the devices for each process within the categories were not reviewed or
tabulated. An earlier document of GAP entitled "Air Pollutant Emission Factors"
(August 1970) does contain both types of information. If such information
is not available, however, the following general collection efficiencies might
be assumed: Particulates
Baghouse 99%
Electrostatic precipitators 90%
High energy scrubbers 90%
Low energy scrubbers 75%
Mechanical collectors
(cyclones & dry collectors) 50%
1-1
-------
Organtc Gases
Afterburners 997.
Adsorption 907.
Inorganic Gases
Scrubbers 757.
Information presented.in this report was obtained primarily from published
technical literature, from Federal, state and local air pollution control
agency files, from conferences with trade association, and from the experience
of the Engineering-Science, Inc. staff members.
Several abbreviations and equations were shortened specifically for the
summary table. A brief discussion of each of the factors follows to facilitate
their usage. The flow rate is always given in terms of scfm (70°F and 1 atm.)
and is. given as a function of an input or an output rate. In the case for
anthracite coal combustion the flow rate is based on the coal feed rate, in
pounds per hour. For bitusiinous coal fired power plants the flow rate is also
based on the megawatts of power generated,an output parameter. In several
instances a functional relationship for the flow rate could not be established,
therefore a mean and range are offered for those sources. (This is mainly
due to the scatter in the data when the flow rate was plotted with the input/
output factor.) For example, under the source category "Domestic Incineration"
the flow rate is listed as 35 scfm. The range for these units is 4 to 51 scfm.
The exhaust gas temperature is the temperature of the gases at the exit point.
Temperature is given in Farenheit and Centigrade units. The velocity indicated
in the summary table is th* actual exit velocity given in feet per second and
meters per second. The stack height is given in feet and meters. Under
the column Common Control Device, we have listed abatement equipment commonly
used for the specific category. (A list of their collection efficiencies has
been discussed above.) In several instances more than one control device was
coeaon. In those cases we have given two flow rates, termperatures, velocities,
etc,, but only where these different control devices changed the conversion
factors. "None" means that no control equipment is commonly used. In the
column tabled other Data, additional information was listed about a specific
source. Excess air rates are given for combustion and incineration catagories
because they are important parameters which effect exhaust gas flows. For
industrial catagories process weight ranges and operating times are included
in the "Other Data" Column.
Throughout this report the flow rates are given in standard cubic feet
per minute. An attempt was aade initially to report both actual and standard
flow rate equations. However there was a general lack of correlation of actual
flows with the input-output parameter because of the fluctuation in gas
temperature for the data. To correct the flow from standard conditions
to actual conditions, the following equation is used:
Q actual = (460 + T ) Q std.
530°
Q actual = Flow Rate at actual conditions
T = Actual stack gas temperature (°F)
Q std
Flow Rate at Standard Conditions
(70° and 1 atm )
(The equation assumes no change in pressure
for standard to actural conditions)
The bulk of the time spent on this project was utilized in obtaining
the data. A prodigious amount of data is available for these categories on
emission rates: however, many literature sources did not include flow rates,
gas temperatures, velocities, stack heights, or input-output characteristics.
In those instances estimates were made for these parameters. The estimates
were based on our prior experience, theoretical calculations, safety factors
(for aerodynamic fatigue velocities) and other consultants experience.
Caution should be exercised in applying the conversion factors to
a specific plant or process. The factors should be used as a first pass
or rough approximation of exhaust gased but detailed source data should be
used to verify and refine the estimate whenever possibe. Furthermore, for
a few industrial processes, no data were found to even begin to estimate
exhaust emissions. It is suggested that investigators in the field con-
sistently report gas flow rates and conditions. Finally, this type of in-
vestigation should be updated and expanded at some later date to improve
upon the value of such conversion factors
A summary table of all conversion factors and exhaust gas conditions
is presented for easy and quick reference by the reader. For backup or
explanation, please refer to the appropriate chapter in the discussion.
1-2
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1
CHAPTER II-l
ANTHRACITE COAL COMBUSTION8
Anthracite coal production and use is centered in Pennsylvania
where this "hard" coal is burned primarily in space heaters and small
industrial/cormercial boilers, such as apartment houses, schools,
municipal buildings, small office and commercial structures and snail
industries requiring process steam. The most numerous anthracite users
are small domestic units which burn from 15 to SO pounds per hour.
Small industrial/commercial units, with ratings up to 10 million
BTU/hr, burn 100 to 1,000 pounds per hour. Pennsylvania Power and
Light Company reportedly is the only electric utility in the Nation
that has anthracite coal-fired generating units.
Anthracite heat values range from 11,500 to 14,000 BTU/lb.
with a mean of about 12,500 BTU/lb. Typical analyses for anthracite
(Table II-l.l) will show it to have lower sulfur, volatile matter, and
ash but higher fixed carbon than bituminous coal.
Anthracite furnace use and operation follow the degree-day
curve since demand for space heat has wide variations caused primarily
by variations in the ambient air temperature. When no degree day-curve
is available, assume 12 hours per day operating time. On the average,
most units run at about 607, of their designed capacity with peak load
periods running up to 1307, of design capacity. An abundance of data
were available for analyzing boiler output and fuel feed rates3'*
(Figure II-l.l). The data were plotted at the actual operating loads
which ranged from 20 to 136% of the manufacturers' design capacities.
From this curve, the efficiency of the operating units appears to aver-
age about 70^ (output-BTU/hr./input-BTO/hr.); this efficiency should
be used in calculations unless more specific Information is available.
Over 30 data points provided an average heat efficiency of 70%; the
complete list is shown in Table II-l.2. Mechanical collector* are
sometimes used to control fly ash emissions, but they have no influence
II-l
-------
on exhaust flow rates and very little on temperature or velocity of
the combustion gases.
GAS FLOW RATE
Excess air rates ranged from 18 to 2007. , but most furnaces operate
between 50 and 100% excess air (Table II-1.2). Such wide variations
in excess air rates are typical among small domestic and industrial
fired boilers. From this data, larger units appear to operate with
somewhat less excess air than smaller units. Generally though, exhaust
gas flow rates will total between 300 scfin and 450 scfm per 100
pounds/hour of coal burned (Figure II-1.2).
GAS TEMPERATURE
The exhaust gas temperatures are fairly constant,and boilers and
furnaces operate with stack gas temperatures of 285 to 590°F with a
mean of 450°F (Table II-1.2). There is some indication that larger
boiler units have hotter exhaust temperatures than small units.
GAS VELOCITY
No information was available to determine stack gas velocities.
Because of the adverse effects of high velocities a maximum velocity
of 20 to 30 feet per second (fps) is probably common to these furnace
stacks. Domestic and industrial/commercial buildings using anthracite
will use natural draft so the most economical stack diameter can be
calculated from Appendix A.
STACK HEIGHT
Domestic and industrial/commercial buildings using anthracite
will range in height from 20 to 100 feet. Where specific stack height
is not available, use 60 feet.
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Coal Feed Rate - 131.3 x Boiler Output - 31.75
(Ib./hr.) (million BTU/hr.)
12 345
Boiler Output (Million BTU/hr.)
Figure H-1.1 Anthracite coal requirements for various heat production
rates
n-7
-------
4 -
§
I 2
25%
r * i i i
200 400 600 800 1000
Feed Rate Ob./hr.)
Figure II-l. 2 Calculated exhaust flow rate* at several excess
air percentages for anthracite coal production.
H-8
CHAPTER 11-2
BITUMINOUS COAL COMBUSTION*
"Power Plants"
Bituminous coal Is commonly used as a boiler fuel throughout the United
States because of its wide availability and low price. Over 50 percent of
the U.S. bituminous coal production is consumed by one category, the electric
power utilities.6 Except in the southwest (Texas, Oklahoma, Louisiana) where
natural gas is abundant, coal supplies the majority of the energy for the
generation of electricity. Residual oil has made recent inroads because of
sulfur-in-fuel regulations,but bituminous coal still accounts for 61 percent
of the total heat energy used by power plants.
While most bituminous coal is produced in the Appalachian Mountain
region, coal and lignite fields elsewhere supply fuel for local consumption.
Information on heat value of coals from various fields shows a wide range
(10,000 - 14,000),but most coals average about 12,000 BTU/lb. (Table II-2.1)7.
Specific heat values and other analyses may be obtained in the U. S. Bureau
of Mines annual publication, "Analysis of Tipple and Delivered Samples of
Coal" (Table 11-2.2)5.
Generating stations commonly pulverize coal before firing to increase
boiler efficiency and ensure complete combustion. The best large steam -
electric power plants reportedly have heat requirements of about 8500 BTU/kw-hr
with a plant thermal efficiency of 0.40 (Table II-2.3)8. The data from Federal
Power Conmission records (Table II-2.4) confirm this value; the data were
9
taken from the largest power stations in the U.S.
Power output for large coal fired boiler units is generally given in
megawatts and is usually displayed by power plants on information plaques at
the plants. Such information also is published by the Federal Power Comnis-
sion' and National Coal Association7.
In 1970 the Federal Power Commission began collecting air and water
pollution emission data from all public utility power generating stations
in the U. S. The information is made available for public inspection
through the Office of Public Inspector, Federal Power Comnission,
Washington D. C. Available data includes air and water emissions, fuel
quality and quantity, effluent flow rates, power generated, and several
other items of economic and engineering benefit regarding air and water
II-9
-------
pollution control. Data from over 50 power plants located In 15 states
were randomly selected to provide input-output, gas flow rate, temperature,
velocity, and stack height information (Table II-2.4) .9>U»14>15
The major pollutants emitted from combustion of bituminous coal are
particulates, sulfur oxides and nitrogen oxides. Abatement equipment
presently is used only for particulates. In the present state-of-the-art,
no means have shown success in the control of oxides of nitrogen or sulfur.
The most common device used to control particulate emissions is the electro-
static precipitator. (Precipatators are often preceded in the flue gas
effluent stream by a cyclone or other similar type of mechanical collector
to remove large particles.) There is no significant temperature drop (less
than a 5% drop) across the precipitator, since most are well built and in-
. 12,13
sulated.
Coal input rate for generating a unit of electricity is most directly a
function of the coal heat value (Equation II-2.1); however, boiler efficiency
and chemical analyses of the coal also affect coal usage. On the average,
8.8 million BTU of energy are required to generate 1 megawatt-hour of power.
Data from several different generating stations Illustrate the relationship
provided by Equation II-2.1 (Figure II-2.1).
(Equation II-2.1 was based on 12,000 BTU/lb. heat value and an average boiler
efficiency of 85%.)
Coal Firing Rate
(tons/hr.)
Power Production (aw.)
Coal Beat Value (BTU/lb)
8.8 (BIO) 1 (ton)
(mw.-hr.) 2000 (Ib.)
The operating loads of electrical generating units vary according to
time of day, day of the week and season of the year. Highest combustion
efficiency is attained when operating at 100% of design capacity, so most
pulverized boiler units, when running, tend to operate at that loading. It
is nore practical to run fewer units at full load than to run all units at
partial loads. Peak demands occur for suomer air conditioning and winter
heating loads.
GAS FLOW RATE
Exhaust flow rate is governed by the quantity of coal burned, excess
11-10
air rate and chemical analysis of the coal. Excess air is added to enhance
complete oxidation/combustion of all carbon in the coal. It is common
practice for pulverized coal boiler units above 100 Mtf capacity to use
between 12 and 25% excess air, while smaller boiler units require 40 to 50%
excess air. The trend today is toward lower excess air which results in
higher combustion efficiency and less NOX. One large power plant uses only
10% excess air for its pulverized coal furnaces. Most power plants have
charts and records available on air flow rates, fuel usage, and combustion
efficiency. Where specific data is not available Figure II-2.2 can be used
to estimate exhaust flow rates at standard conditions (70° F and 760 ma Hg).
Exhaust gas flow ranges from 1,750 - 2,000 seta/megawatt. For calculations,
assume 2,000 scftn/megawatt,
GAS TEMPERATURE
Flue gas temperatures depend on efficiency of combustion, whether air
preheaters are used, excess air rates, firing rate and type of firing unit.
However, one important consideration in determing the minimum exit temper-
ature is the sulfuric acid dew point which is about 250°F. Sulfuric acid
corrodes combustion chamber walls and results in costly repairs. By making
sure that the stack gases are always above the sulfuric acid dew point,
formation of sulfuric acid mist can be minimized. Flue gas exit temperatures
for 55 randomly selected pulverized units ranged from 235 to 370°F with
a mean of 280°F (Figure 11-2.3). For calculations, assume 280°F.
GAS VELOCITY
The only emission point for power plants is a tall stack. Stack diameters
are used to control velocity and these diameters usually range from 12 to 25
feet depending on exhaust gas throughput. Stacks are usually made of concrete.
It is desirable to have exit velocities below 60 fps to prevent aerodynamic
vibrations within the stack. Otherwise, added strain may lead to rapid
deterioration of the stacks. Appendix A is offered to facilitate calculation
of ideal velocities.
From Federal Power Commission data, exit velocities were calculated from
maximum exhaust flow and stack diameters (Figure II-2.4). Most velocities
ranged from about 40 to 60 fps with an average of about 50 fps. Where specific
data are not available SO fpa should be used in calculations.
11-11
-------
STACK HEIGHT
The trend today is toward taller stacks to enhance gas dispersion and
lower ground level concentrations of pollutants. However, in rough complex
terrain tall stacks (even those 500 feet above the surface) are not always
effective. Data from the Federal Power Commission records were plotted
as a histogram to show the range of stack heights (Figure 11-2.5). The range
was 124 to 600 ft. with a typical height of 300. Where specific data are not
available 300 feet should be used for calculations.
It-12
CHAPTER II-2
BITUMINOUS COAL COMBUSTION
"Industrial/Commercial Plants"
Stoker fired boiler units are used mainly for generating industrial
process steam., commercial space heating and commercial refrigeration (air
conditioning). They are commonly found in many central heating plants for
government buildings, institutions, hospitals, universities, apartment
complexes and factory power houses. Their use is declining as gas and oil-
fired units require less space and less labor. Pulverized coal-fired boilers
would be considerably more efficient, but they can not be used economically
for small and medium scale steam production below 300,000 Ib./hr. Small
boilers often have wide variations in operating loads, and stoker fired
furnaces are uniquely suited to this fluctuating demand.16 stoker units,
both underfeed and spreader, use a "nut" coal.
Efficiencies of these furnaces and boilers vary considerably, but data
available from several Federal government installations showed a typical
boiler efficiency of 75 percent.15 In other words, 250,000
Ib./hr. of steam (250 million BTU/hr. output) will require 330 million BTU/hr.
of heat input (Table II-2.5).
Cyclones or other dry collectors are commonly used to reduce solid
17 1 R
particulate emissions.*''10 Because the fly ash has some heat value, fly
ash reinjection may increase boiler thermal efficiency yet, at the same
time, increase particulate emissions to the atmosphere.
GAS FLOW RATE
Exhaust gas flow rates are dependent on excess air rates which commonly
range from 50 to 200 percent in stoker fired boilers to prevent smoking.
For new Federal boilers, the National Academy of Sciences (MAS) recommends
that specifications require the boiler to be able to operate at 25 percent
excess air down to 33 percent of maximum load.1' the HAS also specifies
capabilities of the combustion controls on changing loads. It is safe to
assume that operating practices will generally show less efficient operations
than required by specifications. Also, in practice, where steam demand is
fluctuating, the combustion air flow rate is held fairly constant and the
11-13
-------
TABLE II-2.1
coal feed rate is increased or decreased to meet the load demand. By such
operation, excess air may go from 50 percent at maximum load to 200 percent
at 20 percent of maximum steam load. Where specific information is not
available, it is recommended that 50 percent be used (Figure II-2.6 and II-2.7)
in calculations. From the curves one can observe that an average exhaust flow
rate of 200 scfm can be expected for each 1 million BTU/hr. heat input.
GAS TEMPERATURE
Most stoker fired boilers or furnaces in industrial or commercial appli-
cations will be outfitted with a mechanical collector to reduce particulate
emissions but little change in temperature will be noted. Data obtained for
25 plants showed actual stack gas temperatures to range from 292 to 906°F with
an average value of 527°F. For calculations use 500°F for exhaust gas temperatures.
GAS VELQCm
No empirical data on stack gas exit velocity was found for stoker fired
units. It is recommended that Appendix A be used to estimate stack diameters
and exit velocities. Otherwise assume about 30 fps.
STACK HEIGHT
The stacks for stoker fired units are usually made of metal and are
about 2-3 feet in diameter. Often they extend through the tops of buildings
and protrude about 10 feet. Since industrial/coanercial buildings range
from 20 to 100 feet in height, assume 60 feet for calculations.
TYPICAL HEAT VALUES OF FUELS USED BY POWER PLANTS (1968)
Region and State
NEW ENGLAND
Connecticut
Maine
Massachusetts
New Hampshire
Rhode Island
Vermont
MIDDLE ATLANTIC
New Jersey
New York State
New York City
New York State (Excl. NYC)
Pennsylvania
Philadelphia
Pennsylvania (Excl. Phil)
EAST NORTH CENTRAL
Illinois
Indiana
Michigan
Ohio
Wisconsin
WEST NORTH CENTRAL
Iowa
Kansas
Minnesota
Missouri
Nebraska
North Dakota
South Dakota
SOUTH ATLANTIC
Delaware
District of Columbia
Florida
Georgia
Maryland
North Carolina
South Carolina
Virginia
West Virginia
Number
of
Power Plants
13
5
28
5
4
1
18
34
17
17
41
9
32
42
33
37
50
26
40
34
' 40
35
18
15
10
5
2
37
11
11
16
12
12
11
Average B.
Coal
(lb.)
12,679
-
12,637
13,769
13,614
13,744
13,127
13,124
13,517
12,909
12,220
13,434
11,974
10,684
11,154
12,463
11.661
11,888
10,734
12,037
11,162
10,845
12.216
6.909
8.371
13,055
13,139
11,513
12.285
12,976
12,627
12,659
12,964
11,889
T.U. Content
Oil
(gal.)
149,054
149,611
148,911
149,767
149,888
-
148,255
148,320
148,321
146,128
149,006
149,314
138,300
148,895
138,050
138,810
140,195
134,647
141,880
150,110
145,083
145,250
150,914
144,369
149,425
150,125
147,516
149,574
147,227
148,559
140,873
148,013
140,939
137,402
as Burned
Gas
(Cu.ft.)
~T,033
-
999
-
1,040
-
1,037
1,036
1,035
1,038
989
979
1,040
1,043
1,013
1,042
1,039
1,020
1,020
1,003
1,012
971
1,006
1,054
1,007
1,037
-
1,014
1,040
1,025
1,049
1,044
1,040
1,100
11-14
11-15
-------
" TAB!*" 11-2.1
lYPICAL HEAT VALUES OF FUELS USED BY POWER PLANTS (1968) (Continued)
Region aad State
EAST, SOOTH
Alabama
Kentucky
Mississippi
Tennessee
WSST SOUTH CENTRAL
Arkarjsas
Louisiana
Texas
Arizona
Colorado
Montana
Nevada
Sew ^xic
CalifcrTiia
Oregon
Washington
UNITED STATES TOTAL
Number
of
Power giants
11
16
12
7
8
21
18
77
11
22
5
5
16
10
8
39
2
6
940
Average B.T.U. Content aa Burned
Coal Oil Gas
(gal.) (Cu.ft.)
11,869
11,281
12,582
11,682
_
-
12,975
-
10,528
10,667
7,030
12,665
8,944
12,663
7,965
_
-
-
11,769
138,393
146,754
—
148,793
148,589
148,105
143,619
149,677
151,121
153,042
146,818
150,009
155,105
136,905
149,899
153,571
156,553
148,971
1,046"
1,035
1,048
1,048
1,019
1,070
1,039 '
1,040
1,072
893
1,178
1,069
1,062
931
1,050
1,075
1,053
•
1,043
i
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Moisture,
as-received coal
Volatile Matter
Fixed Carbon
Ash
Sulfur
Hydrogen
Carbon
Nitrogen
Oxygen
a
c-.
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re
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Btu, £. ^
dry basis £ £
n
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11-16
-------
TABUS II-2.3
Thermal Efficiencies for Different Size Boiler Units
Type of Heat
All stationary steam plants, average
Central-station steam plants, average
Best large central-station steam plant
Small non-condensing industrial steam plant
Small condensing industrial steam plant
"By-product" steam power plant
Diesel plant
Natural-gas-engine plant
Gasoline-engine plane
Producer-gas-engine plant
8
Plant
heat rate
B.t.u./Vw.-hr.
25,000
11,500
8,500
35,000
20,000
4,500-5,000
11,500
14,000
16,000
18,000
Plant
thermal
efficiency
0.14
0.30
0.40
0.10
0.17
0.70-0.75
0.30
0.24
0.21
0.19
11-18
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100
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Coal Firing Rate * 0.31 x meqawatts + 15.4
(tons/hri)
100 200 300 400 500
Electrical Generating Capacity (Meaawatts)
Figure I1-2.1 Pulverized coal firing rate vs. electrical qeneratinq
capacity.
-------
750.
500
250
R=.950
O
Exhaust Flow = 2.43 x Megawatts * 81.9
(1,000 scfm)
100 200 300 400 500
Electrical Generating Capacity (Megawatts)
Figure II-2.2 Exhaust gas flow rate vs. electrical generating capacity
for coal fired power plants
11-26
30-
20-
10-
100 200 300 400
Teirperature (F°)
500
Figure II-2.3 Histogram of stack gas temperatures for bituminous
coal fired power plants.
11-27
-------
80 _
~ 60 -
40 -
20 -
O
o
O
0 100 200 300 400 500
Electrical Generating Capacity (MM.)
Figure 11-2A Gas exit velocity vs. electrical generating capacity
for bituminous coal fired power stations.
n-28
20-
-------
60
01
4-»
£
40
25%
20
100%
Excess Air
Based on 12,000 BTU/lb. coal
C/H ratio • 10
50
100
150
200
250
Heat Input (million RTU/hr.)
Figure II-2.6 Calculated exhaust flow rate for stoker fired combustion
units
11-30
Exhaust Flow » 3.15 x Coal Input + 0.21
(1,000 scfm) (1,000 Ib./hr.)
5 •
1 2345
Coal Input (1,000 Ib./hr.)
Figure II-2.7 Bituminous coal feed rate vs. exhaust flow for stoker
fired combustion units (SOS excess air)
n-31
-------
CHAPTER II-3
RESIDUAL FUEL OIL COMBUSTION *
"Power Plants"
As its name indicates, "residual oil" is the heavy residue that is
left during the refining process when lighter oils, such as kerosene and
gasoline, are removed.
Typical analyses of fuel oils for the U.S. are available from an annual
government publication, "Burner Fuel Oils," U. S. Department of Interior."
For sane time, investigators thought that oil additives played a
significant role in Increasing fuel oil combustion efficiency and reducing
total fuel oil air pollution. A status report of tests on oil additives
conducted by EPA indicates that only minimal gains are attained in com-
bustion efficiency and reduction of air pollution.^ Unless otherwise
indicated, the data offered here were assumed to contain no oil additives.
Most residual oil fired power plants will have no sophisticated air
pollution control equipment; however, some plants use mechanical collectors
(cyclones and multiple cyclones) during soot-blowing operations. The overall
efficiency of the mechanical collectors is about 60 percent, collecting
mainly particles larger than 10 microns. * The current trend in new air
pollution regulations to reduce visible emissions nay require use of electro-
static precipltators in the future. Presently, there are 2 or 3 generating plants
which are installing electrostatic precipitators. As mentioned earlier,
there is no significant change in the gas conditions when precipitators or
mechanical collectors are used.
The fuel oil consumption rate is directly related to power production
rate as described earlier for pulverized coal. Equation 11-3.1 gives the
approximate relationship.
11-3.1
Fuel Oil Input (gal./hr.) - Power Production Rate (mw.) x 8.8 (BTU
Heat Value (BTU/lb.)
(mw.-hr.) 8.212(lb./gal.)
Another common way of designating boiler capacity Is the steam generated
(Ib. steam per hour). Since 1 Ib. of oil burned per hour will generate
13.8 Ib. of steam p«r hour, baaed on the plot of the empirical data in
11-32
Figure II-3.1, Eq. II-3.2 provides another important relationship when the
boiler capacity is known.
Fuel Oil Input (gal./hr.)
Boiler Capacity (Ib.steam/hr.)
110 (Ib. steam/gal.)
II-3.2
Specific power plant data can be obtained from the Federal Power Commission.'
A plot of the data from randomly selected power plants (Table II-3.1) shows
fuel input as a function of output in steam capacity and power production
rate (Figure II-3.1).9'14
GAS_FLOW RATE
Exhaust flow rates for large fuel oil combustion units follow
a linear relationship as can be seen from Figure II-3.2. Larger
units may be operated more carefully than smaller units because of the
efficiency.
Power plants tend to use about 20" excess air while industrial furnaces
average near 90%.2^ The theoretical air flow closely approximates the
actual flow rate with an accuracy of + 15". As can be seen from Figure II-3.2,
approximately 27,200 standard cubic feet of exhaust gases can be expected
for every 1000 gallons of residual oil fired.
GAS TEMPERATURE
The sacie temperature considerations which are necessary in coal furnaces
are also valid for oil fired units. The sulfuric acid dew point temperature
is an important operating temperature factor. As in the case of coal fur-
naces, the exhaust temperature is related to the arount of excess air used
in the system. Since the boiler efficiencies of larger units approaches
stoichiometric conditions, there is little variation in air fuel requirements
and,thus, little variation in exhaust gas temperatures. Table II-3.1 shows
exit gas temperature ranges for residual fuel oil ccmbustion with most
data falling in the 250 - 350°F range. Where specific information is not
available 300°F should be assumed.
GAS VELOCITY
Using data provided on stack diameters and exhaust gas flow rates from
the Federal Power Commission, velocities were calculated. Velocities ranged
11-33
-------
from 20 to 100 fps; where specific data are unavailable 40 fps should be assumed.
STACK HEIGHT
Stack heights typically ranged from 110 to 450 feet with an average
of about 190 feet. When specific information is not available use 200
feet for dispersion calculations.
11-34
CHAPTER II-3
RESIDUAL FUEL OIL COMBUSTION
"Industrial/Commercial Plants"
Small boilers consuming less than 2,500 pounds of oil per hour (315
gallons) are principally used for producing industrial process steam and
space heat. These units usually are less efficient in combustion
than the power plants and are given less attention by the operators. For
this reason, one can expect to find wider fluctuations in fuel input, air
requirements, excess air and exhaust gas temperatures for these units. The
scaliest size boiler that will use residual fuel oil is about 2.5 million
3TU/hr, capacity; smaller units generally will use No. 1 oil.
The fuel oil input and steam capacity are shown in Figure II-3.3. The
figure shows that 1 pound of oil will generate 12 pounds of steam, compared
to 13.8 for power plants.
GAS FLOW RATE .
Some of the data plotted in Figure II-3.4 were from boilers which used
extreme amounts of excess air (43 to 180%) in the combustion processes.
Although these are actual data being reported, they tend to show poor com-
bustion efficiencies because of the high quantities of air used. Optimum
efficiency for small units can be attained with 20 - 30% excess air. Based
on available data, the average excess air rate for units burning less than
2,500 Ib./hr. was 60S. The figure shows that about 50 standard cubic feet
of exhaust gases can be expected for each gallon of residual fuel oil burned.
An earlier reference used 213 cubic feet per pound (1700 cubic feet per
gallon) which agrees with the data in Figure II-3.4; in general, the
theoretical exhaust rates are less than actually measured in the field.
GAS TEMPERATURE
Excess air affects exhaust gas temperatures. Some of the data which
appear in Table II-3.2 are from boilers with excess air ranging from 70 to
180 percent. Temperatures ranged from 220 to 710°F. Where
specific data are unavailable assume SOO°F.
11-35
-------
GAS VELOCITY
Maximum exhaust gaa velocity would be on the order of 25 to 30 feet per
second based on design considerations. Although no data were available for
analysis, use 30 fps for calculations.
SIACK_HEIGtg
Most industrial/commercial buildings have stacks slightly higher than
the roof. Typical stack heights, therefore.would range fron 20 to 100 feet
with 60 feet being typical.
11-36
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Fuel input rate = 0.055 x megawatts +1.5
(l.OOOjal./br.)
3 100 200 300 400 500
Electrical Generating Capacity (Megawatts)
Figure II-3.1 Relationship of residual fuel oil requirements to
electrical generating capacity.
11-60
700
600
-=• 500 .
8
400
300
200 '
100 -
R=.971
Exhaust flow rate = 27.2 x Input rate - 5.7
(1,000 scfm) (1,000 gal./hr.)
10 20
Fuel Input Rate (1,000 qal./hr.)
Figure II-3.2 Power plant exhaust gas flow rate vs. residual
fuel oil input
11-41
-------
300
ZOO .
100
0
R.«576
© Fuel Input Rate * 5.24 x Steam Production Rate + 37.6
O (gal./hr.) . (1,000 Ib./hr.)
5 10 15 20 25
Steam Production Rate (1,000 Ib./hr.)
Figure II-3.3 Steam production rate vs. fuel oil input rate
II-4Z
15 -
10 •
§
5 •
50
R=.975
Exhaust flow rate = 0.05 x Input rate
(1,000 scfm) (gal./hr.)
250
100 150 200
Input Rate (gal./hr.)
Figure II-3.4 Exhaust flow rates for small residual fuel oil units
11-43
-------
CHAPTER II-4
DISTILLATE FUEL OIL COMBUSTION8
Distillate fuel oil is a light petroleum fraction, like kerosene or
gas oil, resulting from the distillation, or topping, of crude oil. To
provide standardization, specifications have been established for various
grades of fuel oil. Grades No. 1 and No. 2 are sometimes designated as
light and medium domestic fuel oils. Table II-4.1 shows a typical analysis
of distillate fuel oil.
Distillate fuel oil has several unique properties which enhance its
use as a fuel for small combustion sources. Its viscosity,as compared to
residual fuel oil, is low which results in smooth feed flow to the furnace
without heat being added to the storage vessel or input lines. Also, it
is lower in water, ash and other impurities.
The heat value per pound of distillate oil is somewhat greater than residual
oil (20,000 BTU/lb. for No. 1 versus 18,300 BTU/lb. for No. 6). Distillate
fuel oil is more volatile than residual oil so combustion is simpler. Host
furnaces using distillate oil have few combustion variables. The exhaust gas
from these furnaces should not show wide variations because furnace manu-
facturers have preset most operating conditions.
Use of distillate oil shows an ejected seasonal variation following
the heating demand closely. Daily fluctuations also would be expected.
No air pollution control device* are used with distillate fuel oil
fired furnaces or boilers. There seems to be wide variations in feed rates
when data from Table 11-4.2 «*«plotted with stem production (Figure II-4.1).
The reason given for the wide deviations is that these units are of a small
capacity, are operated inefficiently (as can be noted by the high excess air
rates of near 300%) and are intermittently fired.
26
GAS FLOW RATE
Exhaust gas flow rates for these units also showed wide variations when
plotted (Figure II-4.2). An excess air rate of 651 would be considered
typical.
11-44
GAS TEMPERATURE
Stack gas temperatures for 8 furnaces ranged from 240 to 500°F.
For distillate oil fired units an average temperature of about 350°F
should be used.
GAS VELOCITY
Based on discussions with two furnace manufacturers, a maximum velocity
of 20 feet per second is anticipated.
STACK HEIGHT
Since most distillate oil is consumed in domestic or commercial
furnaces, stack heights are expected to be on the order of 20 to 50 feet.
An average of about 35 feet is expected.
11-45
-------
TAB1£ II-4.1
Analysis of Grade No. 1 and Grade No. 2 Fuel Oils
Grade
Type
Color
API gravity, 60 F
Specific gravity, 60/60 F
Lb per U.S. gallon, 60 F
Viscos., Centistokes, 100 F
Viscos., Saybolt Univ., 100 F
Viscos, Saybolt Furol, 122 F
Pour point, F
Temp, for pumping, F
Temp, for atomizing, F
Carbon residue, per cent
Sulfur, per cent
Oxygen and nitrogen, per cent
Hydrogen, per cent
Carbon, per cent
Sediment and water, per cent
Ash, per cent
Btu per gallon
11-46
No. 1
Fuel Oil
Distillate
(Kerosene)
Light
40
0.8251
6.870
1.6
31
Below zero
Atmospheric
Atmospheric
Trace
0.1
0.2
13.2
86.5
Trace
Trace
137,000
No. 2
Fuel Oil
Distillate
Amber
32
0.8654
7.206
2.68
35
Below zero
Atmospheric
Atmospheric
Trace
0.4-0.7
0.2
12.7
86.4
Trace
Trace
141,000
C r*
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1-1 m 3
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Exhaus
Flow
000 sc
O
H-
t-*
o
-------
75 '
50
25
G
0
R=.815
O
Feed Rate = 5.84 x Steam Production - 16.1
(qal./hr.) (1,000 Ib./hr.)
6 9 12
Steam Production (1,000 Ib./hr.)
15
10
BTU/hr. output
15
20
Figure II-4.1 Distillate fuel oil feed rate vs. steam production and
heat output
3-
O
R.=925
Exhaust flow rate
(1,000 scfm)
0.043 x oil feed rate
(gal./hr. )
0.59
O
20
—i—
40
T~
60
—r—
SO
100
Oil Feed Rate (gal./hr.)
Figure II-4.2 Exhaust flow vs. feed rate in distillate fuel oil
combustion
-------
CHAPTER II-5
NATURAL GAS COMBUSTION*
Natural gas is perhaps the closest approach to an ideal fuel because
It is practically free from non-combustible matter or solid residue. About
one fourth of the electrical energy consumed in 1965 was produced by natural
gas.^ The trend today is for increased use of natural gas as an energy fuel
because of its relative cleanliness. It is used predominately in the southwest
and Pacific states where it is abundant and In large metropolitan areas where
strict air pollution control regulations make other fossil fuels less attrac-
tive. — -
Natural gas is used for electrical power generation, industrial process
vj
steam and heat and domestic space heatlog. Table II-5.1 illustrates the
type of analyses available for various gas fields in the U. S. The mean heat
value of natural gas is about 1050 BTu/cu. ft., and it does not deviate
substantially from field to field. Because this fuel in Its original state
is a gas, it is homogeneous, thus making combustion operations simple. Fine
tuning, utilizing low excess air rates, is possible-because of these pro-
perties (Figure II-S.l).31'33'3*
There are two types of gas burners: one which requires forced air and one
which relies on atmospheric air for its combustion. A gas cooking stove is an
example of an atmospheric air burner unit. Larger units require forced air.
GAS FLOW KATE
As mentioned earlier, natural gas is a homogeneous fluid thus making
fine tuning possible. Common excess air'rates range from 5 to IS percent
Q
with a mean of 8 percent.7 Because low excess air rates tend to reduce KOX
emissions, the trend today is to operate with low (less than 81) excess air.19
From the data (Table 11-5.4) it is evident that operating variables are con-
sistent from plant to plant (Figure II-5.2). In general lowest excess air
rates would be expected with very large combustion units, such as power plants.
GAS TEMPERATURE
From the data collected, exhaust gas temperature ranged from 282 to
372°F with a mean of about 310°F which is slightly higher than coal or oil
11-30
oil fired units. Table II-5.3 is offered to show variations in temperature
for large power plants.
GAS VELOCITY
The gas exit velocity ranged from 36 to 90 fps at the stack exit point.
These velocities are typical of velocities from other large com-
bustion facilities. The recommended velocity is 50 fps for these units
when specific data is not available.
STACK HEIGHT
Typical stack heights and diameters are reported in Table II-5.2 for
natural gas-fired power plants. Of course, different diameter stacks will
result in different stack velocities; the diameter is apparently independent
of plant size. For power plants, a stack height of 300 feet should be
assumed. For industrial/commercial heating plants burning natural gas, a
stack height of about 60 feet should be used. For residential users a
stack height of 20 feet should be used.
11-51
-------
TABLE H-5.1
Typical Composition of Natural Gas From Various Fields
(Monroe, Louisiana)
Methane
Ethane
Propane
Butane
Pentane
Hexane plus
C02
02
N2
Higher heating value,
BTU per cu ft, dry
Sp gr
91.28
1.52
0.70
0.41
0.19
0.15
0.30
5.45
997
0.6075
11-52
TABIE II-5.2
Plant Size, Stack Diameter and Stack Height
For Natural Gas Fired Power Plants
Plant Size
1000 Ib. steam/hr.
600
850
1,170
2,000
2.160
Avg. 1,356
Stack Diameter
ft.
11
13
12
22
18
15
Stack Height
ft.
225
225
250
450
450
320
-------
TAB1E II-5.3
Selected Exhaust Gas Temperatures
For Natural Gas-Fired Units
Plant Capacity
1000 Ib. ateam/hr.
600
850
5,300
2,000
2,160
3,316
Temperature
_ OF
358
340
249
269
253
282
11-54
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R=.988
Feed rate = 1.16 x Steam Production rate + 0.17
(million scfh) (million Ib./hr.)
12345
Steam Production Rate (million lb./hr.)
Figure II-5.1 Natural gas feed rate vs. different steam production rates
1,500
c i .000 -
500 -
R=.996
Exhaust flow rate = 201.6 x natural aas feed rate - 8.6
(1,000 scfm) (million cfh)
1234
Natural Gas Feed Rate (million cfh)
Figure II-5.2 Exhaust flow rates for natural oas combustion
11-56
11-57
-------
CHAPTER II-6
LIQUIFIED PETROLEUM GAS COMBUSTIfflf
The term liquified petroleum gas, LPG, is applied to certain hydrocarbons
which are gaseous under normal atmospheric conditions, but which can be liquified
under moderate pressure at normal temperatures. 32 LPG is produced by oil
refineries and is made up of_the paraffinic series which includes propane,
isobutane and normal butane. There are about 50 to 60 different types of
LPG having different compositions of propane and butane. Table II-6.1 from
the California Natural Gas Association (CHGA), illustrates the standard grades
of LPG.32
The principle use for LPG is domestic heating in faro and mobile
homes, curing tobacco and flame weeding. It is used as petrochemical feed
stock in the manufacture of synthetic fibers (not as a combustion material).
LPG also is used as an auxiliary fuel with the less expensive natural gas
during peak demand periods with connected conraercial systems. The emission
factors for LPG are the same as for natural gas described in Chapter II-5.
11-58
TABLE II-6.1
CNGA Standard Grade for LPG
CNGA
Standard
Grade
Ma*. Vapor
pressure
Psig at 100 F
80
100
125
150
175
200
Range of
Allowable Sp. Gr.
60/60 F
H,0 = 1.0
0.585-0.555
0.560-0.545
0.550-0.535
0.540-0.525
0.530-0.510
0.520-0.504
Composition
Predominantly butanes
Butane-propane mixture,
largely butanes
Butane-propane mixture,
proportions approx.
equal
Butane-propane mixture,
propane exceeds butane
Propane-butane mixture,
largely propane
Predominantly propane
TT-'iP
-------
CHASTER II-7
WOOD WASTE COMBUSTION IN BOILERS0
Wood waste is mainly associated with the pulp and paper industry where
refuse results from the separation of bark from the logs and the lumber
industry where it appears mainly as shavings, sawdust and bark. One power
plant in the state of Washington is reported to use it as a secondary (free)
fuel with oil and natural gas.
Its value as a fuel is dependent on moisture content. The moisture
content of freshly removed bark is high and may reach 75 to 80 percent.3^ when-
ever bark exceeds 55 percent moisture, it is either pressed to remove the excess
water or is mixed with drier material to give a product which can be burned.
The analyses of wood refuse burned as a fuelare shown in Table II-7.1.3^
In comparison to coal, oil and gas, the more common boiler fuels, the carbon
content of wood is low averaging only 55 percent.
Generally, wood waste boilers will need auxiliary fuels to provide a
uniform steam output rate. A typical approach, therefore, is to use a
spreader stoker type furnace with auxiliary fuels consisting of natural gas,
coal or oil.
Larger boiler units operate on a continuous basis to supply steam while
space heating applications would operate intermittently. Both tend to
use whatever wood is available. When waste wood is plentiful one would expect
the fuel mix to be about SOT wood and 207. oil.35'36 Figure II-7.1 is a plot
of the data listed in Table n-?^.35'36'37.38'39 Dry mechanical collectors
including baghouses are the common type of collector used; however, most
plants will not have any control devices.37
GAS FLOW RATE
The exhaust gas flow rate is plotted with heat input to the furnace
since most units use auxiliary fuel (Figure II-7.2)- No conclusion regard-
ing excess air rates could be drawn from the data; however, 1001 excess air
can be considered typical. A flow rate of about 500 scfm can be expected
for every million BTU/hr. of heat input.
11-60
GAS TEMPERATURE
The exhaust gas temperatures for 8 wood fired boilers ranged from 410
to 738°F, (Table II-7.2). An exit temperature of about 500°F would be con-
sidered average.
Mechanical collectors are the most common type of air pollution control
device used for wood waste boiler systems. The temperature drop across
these units varies with the collection system (e.g. 1 cyclone vs. 3 cyclones
in series). An average temperature drop through each unit is about 10°F.
GAS VEMCIIY
Not enough stack configuration data were available to calculate velocities
for these units. However, an average gas velocity of 30 fps is typical for
installationsof similar BTU output capacity and excess air rates.
STACK HEIGHT
A review of the data for 15 boiler stacks at 6 pulp mills showed stacks
to vary in height from steel stubs to 400 feet above ground.3^,37 ^ typical
boiler stack height would be 250 feet.
11-61
-------
TABIE II-7.X
Analyses of Wood Refuse Burned as Fuel
Jack Pine
Proximate analysis, per cent
Ash
. Volatile
Fixed Carbon
Ultimate analysis, per cent
Carbon
Hydrogen
Sulfur
Nitrogen
Ash
Oxygen (by difference)
Btu per Ib (dry)
Ash analysis
Si02
A1203
Fe203
CaO
CaCOj
MgO
MnO
PZ05
K20
Ti02
S03
Fusion point of ash, F
Initial
Softening
Fluid
Weight, Ib per cu ft, bone dry
29
Birch
37-44
Maple
2.1
74.3
23.6
53.4
5.9
0.0
0.1
2.0
38.6
8930
16.0
6.3
5.0
51.6
4.9
5.5
1.6
2.8
4.1
3.1
0.2
2.6
2450
2750
2760
2.0
78.5
19.2
57.4
6.7
0.0
0.3
1.8
33.8
8870
3.0
0.0
2.9
58.2
13.0
4.2
4.6
2.9
6.6
1.3
Trace
3.2
2710
2720
2730
4.3
76.1
19.6
50.4
5.9
0.0
0.5
4.1
39.1
8190
9.9
3.8
1.7
55.5
1.4
19.4
1.0
1.1
5.8
2.2
Trace
1.4
2650
2820
2830
31-42
8885
10.0
2.1
1.3
53.6
9.7
13.1
1.2
2.1
4.6
1.1
Trace
1.4
2760
2770
2780
26-29
11-62
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300.
n
a-
200 .
100
R=.995
Steam Production Rate = 0.67 x Heat Input - 2.7
(1,000 Ib./hr.)
(10b BTU/hr.)
100
I
200
—r-
500
300 400
Heat Input (million BTU/hr.)
Figure II-7.1 Input vs. output for wood waste combustion units
11-65
-------
150 -
&
1
TOO •
50
Exhaust flow rate = 0.21 x heat input + 36.4
(106 BTu/hr.)
100
200
300
400
500
Heat Input (106 BTU/hr.)
Figure 11-7.2 Exhaust gas flow rates for wood waste combustion units
H-66
CHAPTER II REFERENCES
1. Jillison, J.D., Communication with Anthracite, Institute, Harrisburgh,
Pa., March, 1971.
2. "Physical and Chemical Properties of Pennsylvania Anthracite", Anthracite
Institute, WIlkes-Barre, Pa.
3. Tenney, R.F., and J.W. Eckerd, "Performance o£ a Losch Anthracite Stoker
in Building-Heating Service", U.S. Department of Interior, Bureau of
Mines Report of Investigations 6144, Washington, 1963.
4. Tenney, R.F., and J.W. Eckerd, "Performance of Small Industrial-Type
Anthracite-Burning Stokers: ASME Code Tests", U.S. Department of the
Interior, Bureau of Mines Report of Investigations 5607, Washington, 1960.
5. Aresco, S.J., and J.B. Tanus, "Analysis of Tipple and Delivered Samples
of Coal",'u.S. Department of the Interior, Bureau of Mines Report of
Investigations 6904, Washington, 1967.
(,. Bituminous Coal Facts - 1970, National Coal Association, Washington, D.C.
1970.
7< steam-Electric Plant Factors - 1968, National Coal Association, Washington,
D.C., 1968.
S. Perry, J.H., Editor, Chemical Engineers Handbook, McGraw-Hill Book
Company, Hew York, N.Y., 1963.
9 Steam-Electric Plant Air and Water Quality Control Data for the Year
Ended December 31, . (FPC form 67), Federal Power Comission,
Washington, D.C., February 1971.
10. Lukey, M.E., "Air Pollution Measurements and Models in Rough Terrain",
West Virginia University, Morgantown, West Virginia, 1970.
11 Cuffe, S T and Gerstle, R.W. "Air Pollution Emissions from Coal Fired
Power Plants, Report No. 1", Journal of APCA, Vol. 14, No. 9, September,
1969, Report No. 2, Vol. 15, No. 2, February, 1965.
12 "Atmospheric Emissions from Coal Combustion - An Inventory Guide", U.S.
Department of Health, Education, and Welfare, Public Health Service
Publication No. 999-AP-24, Cincinnati, Ohio, 1967.
13 "Emissions from Coal-Fired Power Plants: A Comprehensive Summary",
U.S. Department of Health, Education, and Welfare, Public Health Service
Publication So. 999-AP-35, Cincinnati, Ohio, 1967.
14 Bartok W , et al, "Systems Study of Nitrogen Oxide Control Methods for
Stationary Sources - Final Report", Esso Research and Engineering Company,
Government Research Laboratory, November, 1969.
11-67
-------
15. "Full-Scale Study of Dispersion of Stack Gases - A Summary Report",
Tennessee Valley Authority, Chattanooga, Tennessee, 1964.
16. Communication with W.C, Kelt, National Coal Association, Washington, B.C.,
March 1971.
17. Kelt, Wilbur C., "Fundamentals of Dust Collection", National Coal
Association, Washington, D.C., 1968.
18. "Modern Dust Collection", Fu«l Engineering Data, AIA No. 34-C, National
Coal Association, Washington, D.C., 1968.
19. "Impact of Air Pollution Regulations on Design Criteria for Boiler Plants
at Federal Facilities", National Academy of Sciences, Technical Report,
Washington, D.C., June 1971.
20. Zurn Air Systems Source Test Files, Birmingham, Alabama
21. Private Communication with Reuben Wassar, New Jersey, April 1971.
22. Blade, O.C., "Burner Fuel Oils, 1968", U.S. Department of the Interior,
Bureau of Mines, Bartlesville Petroleum Research Center, Bartlesville,
Oklahoma, 1968.
23. Martin, G.B., J.H. Wasser and R.P. Hangbrauch, "Status Report on Study
of Effects of Fuel Oil Additives on Emissions from an Oil-Fired Test
Furnace", U.S. Department of Health, Education, and Welfare, Public
Health Service, National Air Pollution Control Administration, APCA No.
70-150, Cincinnati, Ohio, 1970.
24. Schwartz, C.H., and R.B. Snedden, "Efficiency, Capacity, and Dust Collection
of Oil-Fired Boiler No. 4", U.S. Department of the Interior, Bureau of Mines,
Pittsburgh Coal Research Center, Pittsburgh, Pa., 1969.
25. "Application Data for Commercial and Industrial Oil and Gas Burners",
Space Conditioning, Inc., Harrisonburg, Va., 1967.
26. Smith, Walter S., "Atmospheric Emissions from Fuel Oil Combustion",
U.S. Department of Health, Education, and Welfare, Public Health Service
Publication So. 999-AP-2, Cincinnati, Ohio, 1962.
27. Clay, C.W., G.G. Poe and J.M. Craig, "Wet Scrubbing of Sulphur Dioxide
from Power Plant Flue Gases", Presented at the 63rd Annual Meeting of
the Air Pollution Control Association, St. Louis, Missouri, 1970.
28. Browne, J.F., and Z.G. Tomaras, "Tests of a High Pressure Gun Atomizer
Burner-Boiler Unit Using No. 6 Oil", prepared for the U.S. Public Health
Service, National Center for Air Pollution Control, Publication No.
PH-22-68-125, by Scott Research Laboratories, Inc., Perkasie, Pa., 1968.
29. Tomaras, Z.G. and L. Reckner, "Tests of an Air Atomiser Burner-Boiler
Unit Using No. 6 Oil", prepared for the U.S. Public Health Service,
National Center for Air Pollution Control, Publication No. PH27-00154,
by Scott Research Laboratories, Inc., Perkasie, Pa., 1968.
11-68
30. Tomaras, Z.G. and L. Reckner, "Tests of a Steam Atomized Burner-Boiler
Unit Using No. 6 Oil", prepared for the U.S. Public Health Service,
National Center for Air Pollution Control, Publication No. PH27-00154,
by Scott Research Laboratories, Perkasie, Pa., 1968.
31. "Control Techniques for Nitrogen Oxide Emissions from Stationary Sources",
U.S. Department of Health, Education, and Welfare, National Air Pollution
Control Administration Publication No. AP-67, Washington, D.C., 1970.
32. Fryling, Glenn R., Combustion Engineering, Combustion Engineering, Inc.,
New York, N.Y., 1967.
33. Harris, M.E., et al, "Reduction of Air Pollutants from Gas Burner Flames,
Including Related Reaction Kenetics", U.S. Department of the Interior,
Bureau of Mines, Washington, 1970.
34. "Air Pollution and The Regulated Electric Power and Natural Gas Industries
Federal Power Commission Staff Report, Washington, D.C., September, 1968.
35. Unpublished data, Zurn Environmental Engineers, Washington, D.C.
36. "Reduction of Sulfur rioxide Emissions in the Vancouver Island Area",
Seversky Environmental Dynamics Research Associates, Washington, D.C.,
1969.
37. Barren, Alvah V., "Studies on the Collection on Bagosse and Bark Char
Throughout the Sugar and Paper Industry", Fly Ash Arrester Corporation,
Birmingham, Ala., 1969.
38. 'Performance Test Report on a Bark Fired Power Boiler", Fly Ash Arrester
Corporation, Birmingham, Ala., 1969.
39. "Air Pollution Engineering Manual", U.S. Department of Health, Education,
and Welfare, Public Health Service Publication No. 999-AP-40, Cincinnati,
Ohio, 1967.
-------
CHAPTER III-l
MUNICIPAL INCINERATION*
Municipal incineration la frequently termed "central incineration"
since burning of refuse is carried out at one or perhaps a few strategic
locations in a community. Municipal incinerator capacities typically
range from 50 to 500 tons per day (4,000 - 40,000 lb./hr.)- Small cities
may have oversized incinerators to allow for growth and so may operate
only 8 hours a day; shifts are added as the amount of refuse increases.
Incinerators in larger cities commonly operate around the clock for 5 or 6
days a week. Chicago, Miami, Louisville, and Atlanta operate incinerators
continuously 7 days a week. A survey of 64 plants disclosed that 85 percent
were designed to operate for two or three shifts per day and for 5 to 6 days
per week.'
A typical refuse composition analysis is provided in Table III-l.1.
For a given community the largest variations in refuse composition are
noted in the increased paper around Christmas tiJne and the increased yard
wastes during the summer and fall months.
Because most municipal incinerators are located in densely populated
areas which have air pollution ordinances, almost all municipal incinerators
will have pollution abatement equipment. Large units, greater than 20 tph ,
are built with water spray chambers and wet baffles to control particulates.
The trend today is toward larger furnaces, with total capacities of 1000 tpd,
having the best available control equipment. This includes wet scrubbers and
electrostatic precipitators most of which have only recently been installed
on these incinerators in North America.
GAS FLOW RATE
Three important variables affecting incinerator exhaust gas flow are
refuse heating value, excess air (Z of stoichionetric air), and quantity of
water evaporated in conditioning and cooling exhaust gases.
As heating value of refuse increases, so does incineration efficiency
and exhaust gas flow rate. The higher heating value (dry basis) of several
substances commonly found in municipal refuse and of typical refuse itself
is presented in Table III-l.2. The heat contents (dry) of municipal refuse
taw**..-
-------
from several cities (Table III-1.3) show relatively consistent values because
of the averaging effects of the large population served. Non-combustible
materials such as bottles, cans, ash, etc. serve to reduce the average heating
value of mixed refuse below the values shown in Table 111-1.3. Where heating
values are not known for a specific incinerator, it is suggested that 4,450
BTU/lb, refuse (vet) be used since this fig-jre was derived from a recent
comprehensive field survey.
Organic materials, the principal group of combustible components of
municipal refuse, theoretically require about 0.7 Ib. of combustion air per
1,000 BTU under stoichiometric conditions. The data of reference 3 yield
a value of 0.72 Ib. of stoichiometric air per 1,000 BTU. These sane data
indicate that flue gas volume exceeds combustion air volume by about 30% for
stoichiometric combustion. Making use of these two approximations, a series
of curves was prepared to show stack gas flow as a function of refuse heating
value at various excess air levels. (Figure I1I-1.1)
Excess air values range from 100 to 400% with most refractory lined
municipal incinerators operating at about 200% (<:5% CO.) . On the other hand,
water-walled municipal incinerators operate at about 507. excess air. The
Incinerator Institute of American standards require a design minimum of 150%
excess air for refractory lined municipal incinerators so lower excess air rates
are very unlikely. If the excess air level is not available directly from
the Individual sources, a value of 200"", should be used ior estimating Elue
gas flow rates. ' '
Water sprays, scrubbers, or wetted baffles are frequently used for cooling
and cleaning incinerator exhaust gas. The effect of evaporated water on stack
gas flew is shown in Figure III-1.2, based on data from reference 3 for 4,450
BTU/lb. refuse. With 200% excess air being utilized, and 2.0 Ib. of water
being evaporated per pound of refuse, the stack gas flow of 2.3 scfm/ (Ib.
refuse/hr.) is increased to 3.0 scfm/ (Ib. refuse/hr.) under these conditions.
Exhaust flow rates of several municipal incinerators are shown in Table
III-1.4 and plotted in Figure III-1.3. Figure III-l.l may be used when specific
data, such as refuse heating value, excess air rate, and refuse input rate are
available for the municipal incinerator.
III-2
GAS TEMPERATURE
Histogram plots of stack gas temperature data £or 10 municipal Incinera-
tors without evaporative gas cooling and 16 with evaporative gas cooling
are shown as Figure III-1.4. Based on these observations, stack gas tempera-
tures from non-water-cooled incinerators are chiefly in the range, 700 -
950°F. Temperatures of gases from water cooled systems lie predominately
in the range, 400 - 600°F. For dispersion calculations, investigators
should use 500°F for incinerators with evaporative cooling and 800°F for
incinerators without evaporative cooling.
GAS VELOCITY
Stack dimensions are commonly set by design to provide an exhaust velocity
less than 30 fps at the emission point when the incinerator is operating at
design rate.' A velocity of 25 fps has been used by some designers and should
be used for dispersion calculations where actual values are unavailable. If
che top stack cross-sectional area is known, the exhaust gas velocity can be
calculated from the actual gas volume flow rate.
STACK HEIGHT
?4inicipal incinerator stack heights range from 50 to 250 feet. When
specific point source data Is unavailable, use 150 feet.
III-3
-------
TABLE III-1.1
Typical Composition of Municipal Refuse
TABLE III-1.2
Typical Heating Value of Various Substances ''
CATEGORY
Glass
Metal
Paper
Plastics
Leather, Rubber
Textiles
Wood
Food Wastes
Miscellaneous
Yard Wastes
PERCENT BY WEIGHT
8.4
8.2
35.8
1.3
1.4
1.9
2.3
18.7
1.6 _
20.4
100.0
SUBSTANCE
Vood Sawdust (oak)
Vood Sawdust (pine)
•tegs (.wool)
Sags (cotton)
Cardboard
Newspaper
Lard
Garbage
Refuse
Refuse
HEATING VALUE
(BTU/dry Ib.)
8,493
9,512
8,876
7,165
5,970
,7,883
16,740
7,300
6,250
6,195
III-4
III-5
-------
i-III .
TABLE III-1.3
Typical Heating Value of Municipal Refuse14'16
LOCATION
Washington, D. C.
Norfolk, Va.
Chicago, Illinois
Typical
HEATING VALUE
(BTU/dry Ib.)
6,336
5,000
5,000
5,395
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III-6
-------
6.0 •
1.0
2000 4000 6000 8000 10000
Heatina Value of Refuse (BTU/lb. as fired)
Figure III-l.l Effect of refuse heatinq value on exhaust flow rate for
different excess air levels.
III-8
50
100
200
250
150
Excess Air (%)
Figure III-1.2 Effect of excess air on exhaust flow rate at various
evaporative coolinq rates.
III-9
-------
T
O 3
OC
R=.824
Exhaust flow rate = 3.07 x Input rate * 16.2
O
"Tr-
io
25
15 20
Refuse Input Rate (tph)
Figure III-1.3 Exhaust flow rates for municipal incinerators
111-10
10 .
5 .
Without Evaporative Cooling
20
15
10
5 .
With Evaporative Coolinq
1
250
500 750
1,000 1,250
TEMPERATURE (°F)
Figure III-1.4 Frequency distribution of exhaust aas temperatures for
municipal incinerators
Ill-ll
-------
CHAPTER III-2
INDUSTRIAL/COMMERCIAL INCINERATION*
In contrast to central incineration where refuse is carried from remote
sites to the incinerator, industrial and commercial refuse is generally in-
cinerated at or near its point of origin. For this reason, it is called
on-site incineration. Typical sizes range from 50 to 2,000 Ib./hr. capacity.
Operating times for industrial/coomercial incinerators vary widely,
but the Incinerator Institute of America suggests that maximum operating
times should be no more than 7 hours of operation per shift for industrial
units and 6 hours of operation per day for commercial buildings, insti-
tutions and hotels.^
GAS FLOW RATE
Industrial/coranercial refuse is generally very specific to a partic-
ular location, and quite large differences in the heating values may be
observed. In addition, use of auxiliary fuel with refuse of low heating
value can further complicate the situation. Because of these factors,
it is generally core straightforward to treat such waste on a BTU/hr.
basis rather than a Ib./hr. basis.
If auxiliary fuel firing rates are unavailable, the Incinerator
Institute of America standards recommend that auxiliary fuel-inputs
tabulated below be used in combustion gas volume calculations:
Refuse as Fired Auxiliary Fuel
BTD/lb.
4300
2500
1000
BTU/lb. of Refuse
0
1500
3000
Exhaust flow rates per 1000 BTU/hr. of total firing were calculated
from several sets of incinerator test data 6 (Table III-2.1). These
observed data were plotted in Figure III-2.1 to provide comparison with pre-
dicted values shown by the straight line.
The approximations made in the presentation of exhaust flow rate as
a function of refuse heating value for municipal incineration (Figure III-l.l)
111-12
are valid for other refuse as well if the burnable part of such refuse is
largely organic matter. Figure III-2.1 shows the predicted relationship
of stack gas flow (scfm/(1000 BTU/hr.) to excess air based on a cross-plot
of the data from Figure III-l.l. The stack gas flow per unit of heating
value is seen to be a function only of the excess air utilized.
From Table III-2.1, the refuse heating value ranged from 5,270 BTU/lb.
to 7,660 BTU/lb. and use of auxiliary fuel ranged from 0 to over 3 million
BTU/hr. heat input. Heating values may be determined if the waste analysis
is known. Otherwise assume 7,000 BTU/lb. for the waste and 1 million BTU/hr.
for auxiliary fuel input. Figure III-l.l also may be used for industrial/
commercial incinerators.
The Incinerator Institute of America standard for Class III
multiple-chamber incinerators suggests the use of 100 percent of excess air
for gas velocity calculations.' The average reported value for excess
air levels from Table III-2.1 was 113 percent which shows good agreement.
If actual values are not available, assume 100 percent excess air and stack
gas flow rates of 0.31 scfm/(1000 BTU/hr.) heat input.
GAS TEMPERATURE
The temperature data of Table III-2.1, for incinerators without water
cooling of the exhaust gases, have an average value of 1210°F. This is
considerably higher than the usual temperature range of 700 - 950°F for
municiple incinerators, but the higher the B7l"/lb. content of the refuse, the use
of auxiliary fuel, and the higher heat release rates probably account for much-of
this difference. For design purposes, the Incinerator Institute of America
suggests the use of 1400°F for calculating exhaust gas velocities, but this
figure is deliberately chosen higher than the expected values to allow a
margin of safety In the sizing of gas ducts. When temperature data are not
available, 1200°F should be used for calculations.
GAS VELOCITY
If the stack cross-sectional area and the exhaust flow (acfm) are
known, exit gas velocity can be calculated. Most industrial/conmercial
incinerators use natural draft stacks between 12" and 36" in diameter.
With 100 percent excess air, exhaust temperature of 1200°F, stack
diameters reconoended by 1IA and gas flow rates from Figure III-l.l, stack
111-13
-------
gas velocities can be calculated as a function of refuse firing rate for
different types of refuse. The results of such calculations are shown in
Figure III-2.2. If velocity cannot otherwise be obtained or calculated,
20 fps should be used for dispersion calculations.
STACK HEIGHT
Recommended stack heights shown in Table III-2.2 may be used In the
absence of specific data. In many cases height of other buildings, etc.
will set the stack height. When no information can be obtained, 40 feet
should be used for stack height in dispersion calculations.
111-14
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-------
TABLE IJI-2.2
Recommended Stack Heights and Internal Diameters
for Class III Natural Draft Incinerators
Capacity
(Ib/hr)
100
150
200
300
400
500
600
700
800
900
1000
Type 0
Diameter
(in.)
16
18
20
22
24
26
28
30
32
34
36
Refuse1'
Height
(ft.)
30
30
35
35
40
40
40
45
45
45
45
Type 1
Diameter
(in.)
14
16
18
20
22
24
26
28
30
32
34
Refuse
Height
(ft.)
30
30
35
35
40
40
40
45
45
45
45
_a. Trash. As fired higher heating value = 8500 Btu/lb.
b. Rubbish. As fired higher heading value^ - 6500 5tu/lb.
c. "Refuse. As fired higher heating value = 4300 Btu/lb,
2 Refuse
Diameter
(in.)
12
14
16
18
20
22
24
26
28
30
32
(c)
Height
(ft.)
25
30
30
35
40
40
40
45
45
45
45
0.6 '
0.2
o
Gas flow = 0.0009 x Excess a." * 0.25
(scfm/1,000 BTU/hr.)
50 100 150
Excess Air (%)
200
250
III-16
Figure IIJ-2.) Comparison of measured stack qas flow with predicted
stack gas flow for industrial/commercial incinerators
IH-17
-------
' 22 '
20
IS
16 .
10
Class "0 Refuse
(8500 BTU/lb.)
Class "V Refuse
{6500 6TU/lb.)
Class "2 Refuse
(4300 BTU/lb.)
Based on 100" excess air and an
exhaust temperature of 1200 F
100
300 500 700 900
Refuse Firing Rate (lb,/hr.)
Figure III-2.2 Design stack velocities for Class III (multiple chamber)
refuse incinerators with natural draft exhaust
CHAPTER III-3
DOMESTIC INCINERATIOHA
As used here, the term "domestic incineration" refers to the on-site
combustion of refuse from both single dwellings (homes) and multiple
dwellings (apartments). Hotels are considered to be commercial buildings
rather than dwellings.
Refuse from single or multiple dwelling units is very similar in
composition and heat content to municipal refuse, the source is the same;
only the location of the point for volume reduction is changed. Therefore!
lacking Specific data, one should use 4,450 BTU/lb. for domestic refuse.
Apartment or multiple dwelling incinerators are usually one of the fol-
lowing types: (a) flue-fed units, (b) "controlled (starved) air" type units
with forced draft fans for combustion air control, or (c) multiple chamber
units. In flue-fed incinerators, refuse is charged directly into the
exhaust flue, the bottom of which opens into the top of the furnace. Much
work has been done to reduce the air pollution problems of flue-fed incin-
erators by means of draft controls and/or afterburners, but many uncontrolled
units remain in use. A newer type of dooestic incinerator is the "controlled"
air furnace which has forced draft fans and daapers for draft control. ^
Private home incinerators have decreased greatly over the past decade
due to voluntary use of municipal disposal systens or restrictions on small
incinerators by local ordinances. Three basic types of home incinerators
have been used: (a) the dehydrating types, (b) high ETC input units, and (c)
after-burner types. The first two types are no longer recooxoended, but some
units may remain in use. The after-burner units can be quite effective and
are sometimes the only home units not prohibited by local laws."
"Flue-Fed Incinerators"
GAS FLOH RATE
Exhaust flow data for flue-fed incinerators are given in Table III-3.1.
The actual gas flow rates (acfm) vary widely because of the lack of draft
control but typically are between 850 - 2,500 acfm with an average of about
1,600 acfm.7
Exhaust flow data for flue-fed incinerators modified with a draft
control damper and roof afterburner also are given in Table III-3.1
111-18
111-19
-------
and plotted in Figure III-3.1. The average stack flow per unit of refuse
burned is 10 scfm per lb./hr. of refuse burned with a range of 7.6 - 12.0
scfm per Ib/hr. refuse. These sane values in acfm at 1268°F are 34 and 25.2
39.8 respectively.
GAS TEMPERATURE
Exhaust gas temperatures for uncontrolled units are not well documented,
but based on stack flow rates and firing rates they should average about
700°F. Temperature data for modified installations with afterburners average
about 1200°F,(Table III-3.1).
GAS VELOCITY
Gas velocities of uncontrolled flue-fed incinerators show extreme var-
iations because of the lack of draft control. Velocities ranging from 8.0 -
24.0 fps were observed for one unit.7 The average velocity was about 16 fps.
Stacks for flue-fed incinerators are generally 16" x 16" in cross-
section (flue liners are commonly sold in 12", 16" and 24" sizes). Using
the 16" dimensions and the flow rates from Table III-3.1 velocities for
modified units can be calculated. These calculations yield an average
velocity of 21 fps. Therefore, where specific data are unavailable, 20 fps
may be.assumed.
STACK IffilGm - ~
Stacks for flue-fed incinerators are generally only a few feet higher
than the apartment house they serve. Garden apartments would normally be
about 3 stories whereas high-rise apartments would be 10 or more. A typical
range in stack height would be 25-80 feet (Table III-3.1). When specific
data is not available, assume 35 feet.
"Controlled^ir Incinerators"
GAS FLOW RATE
Using a standard refuse with an "as fired" heating value of 6,030 BTU/lb.
and operating data from Table III-3.2, a plot of stack gas flow rate (scfm/
(1,000 BTU/hr.))versus percent excess air was made (Figure III-3.2). The actual
gas flow rate (acfm) at several representative temperatures is shown in
Figure III-3.3.10
111-20
GAS TEMPERATURE
The average temperature of stack gases from the 6 tested incinerators
was 983°F with a range of 464 - 165Q°F. Common temperatures were in the
range of 800 - 1100°F. When specific information is not available 1000°F
should be assumed.
GAS VELOCITY
The average velocity of the exhaust gases for the "controlled" air units
was 30.5 fps with a range of 16.9 - 41.1 fps. Where specific data is unavail-
able, 30 fps should be assumed.
STACK HEIGHT
The stack height of the 6 tested units ranged from 20-33 feet; 25 feet
should be assumed.
"Home-Incinerators"
GAS FLOW RATE
Test data for home incinerators including each of the three model types
described earlier are presented (Table III-3.3 and III-3.4)? These data
were used with Figure III-3.1 to estimate the average stack gas flow during
burning of a full charge of garbage or rubbish in home incinerators (Table
III-3.5). The gas flow rates are summarized below;
Incineration
Type
Dehydrating
High Input
After Burner
Since only the afterburner type is still recommended for use in homes,
most emphasis should be placed on this data for that. When specific data
are unavailable use 35 scfm.
GAS TEMPERATURE
The only temperatures available for home units were peak flue gas tempera-
tures which ranged from 250 - 1,180°F (Table III-3.4). These temperatures are
not reached immediately and they are transient even when reached. There is
Exhaust Flow Rate
scfm acfm
3-4
33-51
31-41
7-9
89-137
82-109
Temperature
618
877
805
- 845°F
- 883°T
- 914°F
111-21
-------
generally little cooling of the gases between the furnace and outlet. The
average temperature for home incinerator exhaust should be assumed to be about
500°F.
GAS VELOCITY
By assuming the stack to be a 6 in. round duct, as it usually is, the
gas volume flow rates discussed previously can be used to calculate typical
stack gas exit velocities. The values are as follows: (a) dehydrating units:
0.6 - 0.8 fps, (b) high input units: 7.6 - 11.6 fps, (c) after-burner units:
7.0 - 9.3 fps. Where specific data are unavailable, 9 fps should be used.
STACK HEIGHT
The stack from a home incinerator will discharge about 3 feet above the
roof line which ranges from 10 - 20 feet. Where specific data are unavailable,
15 feet should be used.
Avg.
TAB1£ 111-3.1
Exhaust Gases from Flue-Fed Incinerators
Avg.
Range
Firing Rate Exhaust Flow scfin per Stack Outlet
(Ib./hr.) (scfra) Ib. refuse/hr. height (ft.) Temp. °F
Uncontrolled
63
162
2k.U
76.0
98.5
61.7
S3. 5
123
124
1.28
_liC
101
24.4-162
Modified wit!
100
30
68
49
74.3
49-100
458
1190
326
820
930
500
1120
860
530
441
817
725
326-1190
i draft control <
760
690
710
590
688
590-760
7.3
7.3
13.4
10,8
9.5
8.1
13.4
6.7
4.3
3.4
5.1
8.1
3.4-13.4
lamper and roof after
25
35
68
80
80
54
56
80
25
56
46
55
25-80
urner.
1130
1240
1130
1560
1265
1130-156C
IH-22
111-23
-------
*A O O O
§
O O O u*l O
*J 3 t)
3 *w fli
G, a> g
c ^ ?
in o o
1 OO CO
Q p Q X X X X
a"*--
££~
*fr
;t
43
*3
8i!~
«**.
ir
41 M --v
sse
u
ssl .
Ill
'•£
h*
!-£
Fuel
Input
(1OB BTU/hr.)
l|4
si "
s
•g .
.0
£^
vi tfi m
sssj3sss3wN8S888
*
tnSo»cO*oe5r-«w.tA.£-»«0»
KSSSSSSSSSiSSSSS
SP*<*r-.*oowoo*«
r*«A»ir-irt-»-»>or^r*Oi-'**
^-« ** PI (•* PI •*«•* »«* p«« CM
fOQOoeoooopopOM
^rtr^f^go^ci*1^-*^^**^^
m««^oj2j;2;«
Km,**«rt ^^t^S^S010*
flOW"'^'*' »firt^H^*i-<^H
inmOOOOOQ^O{^®^®®
SSSSnSSSe^MSjN^vc
" ^\o<^O<*l*8on^(*1(n<^~"
x<««ffluoocawMuw^ci'
-------
9S-III
1-3
P
Type
Charge
Type
Table III-3.5
Calculated data for home incinerators
(Based on Tables III-3.3 and 1II-3.4)
Charge
(Ib)
Excess
Air
Exhaust
Flow
(scfm)
Flue Gas
Temperature
or i-1 cc
ooo
COCO™
--co
Garbage
Rubbish
Garbage
Rubbish
Garbage
Rubbish
61.5
17.0
62.6
17.4
63.2
17.5
623
482
441
331
309
249
4
3
51
33
41
31
618
845
877
883
805
914
a. D—dehydrating, H—high input, A—after burner.
b. Estimated value during burning of charge.
c. Peak temperatures.
Ln co cn
B o -o
(5 t-Ti C
p. C rr
W I—1 W
ro ro ** _
rowfo-OrowroN) ro
LJFOLnWh-'i-'l-'vO'O
t-<*-O(->O*J-^JO
111-27
-------
1,500 -
1,000
500
o
o
Exhaust flow = 3.22 x firing rate * 414.0
(scfm) (Ib./hr.)
Uncontrolled
Controlled
r 1 1 1—
50 100 150 200
Refuse Flrinq Rate (Ib./hr.)
250
Figure III-3.1 Stack gas flow rate vs. firing rate for controlled
and uncontrolled flue fed Incinerators
100 200 300 400
Excess Air (%)
500
Figure III-3.2 Stack qas flow for "controlled air" domestic
Incinerators
111-28
111-29
-------
0.5.
100 200 300 400
Excess Air (%)
500
Figure II1-3.3 Stack qas flow for "controlled air" domestic incinerators
at typical exhaust temperatures
111-30
CHAPTER III-4
PATHOLOGICAL INCINERATION8
Pathological waste is defined to include all, or parts of, organs,
bones, muscles, other tissues and organic wastes of human or animal origin.^
These wastes have a very low heating value, typically about 1000 BUT/lb.
To ensure complete destruction of these wastes very high fuel firing rates
are recommended, about 8000 BTU/lb. of waste (5000 BTU in the primary
chamber and 3000 BTU in the secondary chamber).5 Because of the hazards
involved in storing and handling pathological wastes, recoranended design
standards are likely to be followed for operation of these incinerators.
They are generally operated once or twice per day for 1.5-2.5 hours.1''
GAS FLOW RATE
Excess air requirements for pathological incineration are generally
about 100 percent for the waste itself and 20 percent for the natural gas
fuel for the burners. If natural gas consumption is set at 10 scf/lb. of
waste, the exhaust volume will be about 5.0 scfm per Ib. of waste/hr.
Figure III-4.1 shows calculated stack gas flow as a function of disposal
rate both at standard temperature and at several typical temperatures.
GAS TEMPERATURE
High gas temperatures arc essential for incineration of pathological
wastes. The secondary chamber of the incinerators is normally operated at
1600°F, and stack gas temperatures are usually in the range of 800 to 1200°F. ' *
These high temperatures result in relatively clean exhaust gases in most
conditions, and water scrubbers have rarely been used in the past. In such
instances, a gas temperature of 1000°F should be used where specific data are
unavailable.
GAS VELOCITY
Pathological incinerator stacks are frequently sized to give exit
velocities of 20 fps at design firing rates and an exhaust temperature
of 1400°F.2>5>7 With the usual stack temperatures, velocities should be in the
range of 13.5 - 15.7 fps. Assume 15 fps when data are unavailable.
111-31
-------
STACK HEIGHT
Since pathological incinerators will often be associated with com-
mercial buildings or hospitals, stack heights will range from 25 feet
upward to 80 or more. Assume 50 feet when specific data are unavailable.
111-32
3.
2.0 •
1.0
Standard Conditions
100 200 300 400 500
Refuse Incineration Rate (Ib./hr.)
Figure III-4.1 Stack gas flow for patholoaical incinerators
111-33
-------
CHAPTER III-5
AUTO BODY INCINERATION8
The auto body incinerator has two main parts: (a) a primary furnace
which surrounds the automobile body and prevents excessive heat loss by
convection and radiation, and (b) a secondary chamber in which auxiliary
fuel, typically No. 4 fuel oil, is burned to complete combustion of any
residue present in the gases from the primary chamber.^ The units may be
either continuous in operation or batch processes, but the principles of
operation are similar.
Because auto incinerators are usually privately owned and represent
a considerable capital expenditure, they would likely operate 8 hours per
day for 5 or 6 days a week.
GAS FLOW RATE
Test results for a 2-car batch unit with a 5 million BTU/hr. oil
burner indicate that about 166,400 scf of flue gas is produced in an
average burn lasting 38 min. This results in an average stack flow
of 4,380 scfm during the burn. Because most of the flue gas results from
the oil burner operation, this figure would probably not change much when
only one car body is burned. Tor a continuous operation with better over-
all control of the process, the stack flow would probably be 2000 - 3000 scfm.
The actual gas flow rate of the tested unit was 12,900 acfm at an
estimated exhaust temperature of 1075°F. In a continuous unit, flow rates
in the range 6000 - 9000 acfm might be expected at the same temperature.
GAS TEMPERATURE
The average stack temperature of a batch unit was 1075°F. The expected
temperature range during a burn is 800 - 1800°F. Because the temperature re-
quired for smokeless operation of a continuous process is the same as for
a batch process, the average exhaust temperatures would not be expected to
differ much, and 1100°F should be assumed.
111-34
GAS VELOCITY
With a stack of 47-inch i.d. (internal diameter), the gas velocity
would be 25 fps. With the more usual 39-inch i.d, stack, the velocity
would be about 36 fps. Where specific data are not available 30 fps should
be assumed.
STACK HEIGHT
The manufacturer's suggested stack height is 55-60 feet to create adequate
draft for the incinerator. Where no data are available 50 feet should be
assumed.
111-35
-------
CHAPTER III-6
CONICAL BUHNERS B
The conical burner (tepee burner) has traditionally been used for the
disposal-of wood waste, cotton gin waste, peanut hulls and other agricultural
waste. In addition, some smaller cities (100,000 population) use them for
municipal refuse disposal. Typical rated capacities range from 5,000 to
10,000 Ib./hr. They generally operate 10 hours per day, 6 days per week.*^
GAS FLOW RATE
Tepee burners with adequate underfire air systems should be operated
at excess air levels of 300 - 500 percent which is less than natural draft
units use.^ in very poorly controlled conical burners, excess air levels
could approach those for open burning which may be 5000 percent or nore.^
When data are unavailable, assume 1000 percent excess air.
Figure III-6.1 shows the exhaust gas volumes expected from disposal of
municipal waste in tepee burners utilizing 1000 percent excess air. The
refuse is assumed to have a heating value of 4,450 BTU/lb. as fired.
GAS TEMPERATURE
In a properly operated conical burner temperatures near.the exhaust
dome should be 750 - 900°F. However, a survey of tepee-burner installations
found that less than % of the burners even had usable doors; this results in
essentially no control over excess air, and as a result, no control over
temperatures.12 An approximate heat balance using data from reference 13 and
assuming 5000 percent excess air indicates that, in the worst case (open
burning) temperatures could fall as low as 140°F. When data are not available,
400°F may be used as an approximate temperature. (Figure III-6.2)
GAS VELOCITY
The usual tepee has a 15 to 20 foot diameter dome (stack opening),
equipped with 1\ mesh steel wire for collection of large fly ash particles.
Exhaust velocities for a tepee burner burning municipal waste with a 17.5 foot
diameter exhaust dome, an exhaust temperature of 825°F, and 400 percent excess
air, would be between 5 and 25 fps. when no data are available, 15 fps should
be assumed.
111-36
STACK HEIGHT
Tepees vary from 10 feet in diameter by 12 feet high to 90 feet in
diameter by 97 feet high. One survey found the typical size for tepees
to be 52 feet in diameter by 57 feet high.12 Where specific data are
unavailable, 60 feet should be assumed for stack height.
111-37
-------
150 -
100 •
50
246 8 10
Refuse Firing Rate (1,000 Ib./hr.)
Figure III-6.1 Exhaust flow rates from conical burners
111-38
500 1000 1500 2000 2500
Excess Air (%)
Figure III-6.2 Correlation between tenperature and excess air
111-39
-------
'CHAPTER III-7
OPEN BURNING0
Virtually any combustible refuse may be disposed of by open burning,
but three common types of this refuse are (a) municipal refuse, (b) landscape
(yard or garden) refuse, and (c) combustible automobile components such as
tires, seats and floor mats. Open burning in dumps normally occurs for
about 8 hours, 6 days per week.
GAS FLOW RATE
A very rough estimate of the entrained air volume in the smoke plume
from open burning can be made from emission data. This was done for
three types of refuse (Table 111-7.1).^ Gas flow at various burning rates
is depicted graphically in Figure III-7.1 for the three types of refuse.
GAS TEMPERATURE
Gas temperatures from open burning show considerable variation both
with the height above the refuse and with ambient temperature. In addition,
the temperature varies throughout the course of the burn. In general, the
temperature rises after ignition to a maximum within 2 to 5 minutes, falls
rapidly for 10 to 15 minutes, and then drops very slowly for several hours.
Peak temperatures, the time after ignition at which the peak occurs, and the
approximate average temperature over the first hour of burning are tabulated
(Table III-7.2). For dispersion calculations 150°F should be assumed for
exhaust gas temperatures.
GAS VELOCITY
An order of magnitude estimate of gas velocity was calculated from
simulated open-burning experiments on an 8-ft. diameter table. In the
tests the smoke plume maintained one diameter to the 24-ft. level.
14
By assuming temperature and air entrainment of a free plume to be the same
as measured in the experimental work, we calculated velocities, of the data
in Table III-7.2.
111-40
Refuse Type
Municipal
Landscape
Automobile
Gas Velocity
0.7 fps
0.6 fps
1.0 fps
A velocity of 50 fpm is about the lowest velocity that can be felt in
comfort air conditioning; the exit velocity of combustion gases from burning
refuse has to be somewhat higher. For calculations, assume 2 fps.
STACK HEIGHT
For dispersion calculations, use area formulas for a ground level source.
111-41
-------
TABLE III-7.1
Exhaust Gases From Open Burning
14
Refuse
TIES
Municipal
Landscape
Automobile
Excess a
Air X7J
5100
6500
4900
scfm per
Ib . /hi.
20
17
25
Avg.b
Temp.
150°F (66°C)
150°F (66°C)
200°F (93°C)
acfm per
Ib./hr.
23
20
32
a. In the true sense, this is dilution (or entrained) air.
b. Measured 24-ft. above the burning refuse in a duct connected to
large inverted cone above the burning rope.
111-42
TABLE III-7.2
Peak Gas Temperatures for Open Burning
Refuse
Type
Municipal
Landscape
Automobile
Time of
Peak (min)
2
3
4
Peak
Temperature
°F
375
230
485
Appro*. Avg.
Temperature
°F
150
150
200
111-43
-------
30.0
20.0
10.0
200 400 600 800
Refuse Burnina Rate (Ib./hr.)
1000
Figure III-7.1 Exhaust flow from open burm'na of: A. landscape refuse,
8. municipal refuse, and C. automobile components
111-44
CHAPTER III REFERENCES
1. Municipal Refuse Disposal, Institute for Solid Wastes of American
Public Works Association, Public Administration Service, Chicago, 1970.
2. DeMarco, Jack, et al, "Incinerator Guidelines - 1969", Bureau of Solid
Waste Management, Public Health Service, U.S. Department of Health,
Education, and Welfare, 1969.
3. "Systems Study of Air Pollution From Municipal Incineration", Volume
II, Document PB-192-379, Division of Process Control Engineering,
National Air Pollution Control Administration, U.S. Department of
Health, Education, and Welfare, March 1970.
4. "Power", from Kent's Mechanical Engineers' Handbook, Volume II.
J.K. Salisbury, editor. John Wiley and Sons, Inc., New York, 1950.
5. "Incinerator Standards", Incinerator Institute of America, New York,
March, 1970.
6. Corey, R.C., editor, Principles and Practices of Incineration. Wiley-
interscience, John Wiley and Sons, Sew York, 1969.
7. Danielson, J.A., "Air Pollution Engineering Manual", Air Pollution
Control District, County of Los Angeles, National Center for Air
Pollution Control, U.S. Department of Health, Education, and Welfare,
Publication No. 999-AP-40, 1967.
8. Stickley, J.D., and H.B. Orths, "Instrumentation of an Incinerator,
Two Case Studies", from Proceedings of 1964 National Incinerator Con-
ference, ASME, New York, 1964.
9. Sterling, Morton, "Air Pollution and the Gas Industry", J. Air Poll.
Contr. Assn., 11, No. 8, 354 (1961).
10. Private Communication, Carl E. Edlund, Staff Engineer, Compliance and
Evaluation Section, Air Pollution Control Office, Environmental
Protection Agency, Rockville, Md., March, 1971.
11. Kaiser, E.R., and J. Tolclss, "Smokeless Burning of Automobile Bodies",
J. Air Poll. Contr. Assoc., 12 (2), 64 (1962).
12. Kreichelt, T.E., "Air Pollution Aspects of Tepee Burners", Division of
Air Pollution Public Health Service, U.S. Department of Health, Education,
and Welfare, Publication No. 999-AP-28, September, 1966.
13. Franklin, D.M., "Those Terrible Tepees Can Be Effective", Pollution
Engineering, January, February, 1971.
14. Gerstle, R.W., and D.A. Kemnltz, "Atmospheric Emissions from Open
Burning", J. Air Poll. Contr. Assoc., 1J (No. 5), 324-327 (1967).
111-45
-------
15. Stephenson, J.W., "Incineration - Fast, Present, and Future", ASME
Publication 69-WA/Inc-l, New York, N.Y., 1969.
16. "Special Studies for Incinerators for the Government of the District
of Columbia", U.S. Department of Health, Education and Welfare, Public
Health Service Publication 1748, Washington, D.C., 1968.
17 "Interim Guide of Good Practice for Incineration at Federal Facilities,
U.S. Department of Health, Education and Welfare, Public Health
Service Publication No AP-46, Raleigh, S.r., 1969
111-46
CHAPTER IV-1
AMMONIA PLANT C
Amnonla (NH3) is an Interim chemical product used chiefly in the
manufacture of fertilizer. There are about 100 plants in the U. S.
which have a total annual production rate of 20 million short tons.
Demand for aononia has been increasing for several decades and is ex-
pected to continue. Since 90 percent of the ammonia manufactured in
the U, S. uses natural gas as feedstock, many plants are located near
gas fields in the Louisiana and Texas area. Typical plant capacities
are 400 to 600 tons per day with newer plants having capacities as high
as 1500 tons per day. Ammonia plants operate continously.
Coomercial production of ammonia is accomplished by reacting hydrogen
and nitrogen at high temperatures and pressures over a catalyst. In the
typical plant (Figure IV-1.1), the hydrocarbon (usually natural gas) is
mixed with steam in the reformer to yield carbon nonoxide and hydrogen.
These gases are then scrubbed to remove the carbon monoxide and carbon
dioxide inpurities. The process gases, which now consist mainly of
nitrogen and hydrogen, are compressed and fed to the converter where the
gases react to form ammonia. Each plant will operate at different
pressures and temperatures depending on feedstock quality, type of equip-
ment being used and the specific process. Reference 1 lists 11 different
processes with typical operating pressures, temperatures and percent
conversion. Figure IV-1.2 shows the consumption of natural gas as
2
feedstock and as fuel as a function of plant capacity.
GAS FIXV RATE
To attain the required high temperatures, some natural gas is burned to
supply direct heat to the primary gas reformer. Exhaust from the combustion
of this fuel represents the major volume flow emission point. Control
equipment is not normally used. Equation IV-1.1 can be used to calculate
the flow rate from this source, assuming 25% excess air, 1050 BTU/scf of
natural gas and .0750 Ib/scf air.
Exhaust flow rate (scfm) * Natural gas use (1000 scfh) x 222. IV-1.1
IV-1
-------
£-AI
GAS TEMPERATURE
Exhaust temperature from fuel combustion ranges from 700 to 1100°F
with an average of 950°F.
GAS VELOCITY
No data were available. Assume 50 fps if the velocity cannot be
calculated from specific source data.
STACK HEIGHT
The stack used to exhaust this source is usually less than 2% feet in
diameter and is about 75 to 100 feet high. Other emission points within
the perimeter of the plant include flash gas vents, bleed off vents, and
storage vents.
IV-2
-------
1.6
S
o.a j
0.4 J
-f
400
800 1,200 1,600
Capacity of Plant (tons/day)
2,000
Figure IV-1.2 Gas feed rate vs. plant capacities for amnonia
production
IV-4
CHAPTER IV-2
CARBON BLACK PLANT C
Carbon black is an ultrafine soot manufactured by the burning of hydro-
carbon fuels in a limited supply of air. The finely divided material (10 to 400
microns in diameter) is of industrial importance as a reinforcing agent for
rubber (94 percent) and as a colorant for printing ink, paint, paper, and
plastics (6 percent). The 1969 annual production rate was 2.96 billion pounds.
Carbon black is produced by burning oil and/or natural gas with a limited
supply of air at temperatures of 2500 to 3000°F. Part of the fuel is burned
to CO., CO and water vapor thus generating heat for the combustion of fresh
feed. The unburned carbon is collected as black fluffy particles. There are
three basic processes for producing this compound: the furnace process which
uses gas and/or oil, accounting for about 83 percent of the U.S. production, the
older channel process which accounts for about 6 percent of the production and the
newer thermal process which produces the remaining 11 percent.
The furnace process, using natural gas both as the source of heat and feed,
is commonly employed for making the finer grades of carbon black. About 40 per-
cent of the natural gas is used for heat and sixty percent is converted to
carbon black. The amount of feed necessary to make carbon black, however, will
vary with the size of particle produced (Figure IV-2.U. Condon yields (carbon
collected as carbo'i black/carbon in the fuel) are 25 to 30 percent for the
larger particle size and 10 to 15 percent for the smaller particle size black.
The most popular method of making carbon black is the oil furnace process
which uses oil as the raw material. The feed stock is a specially refined oil
which contains about 90 percent carbon. Yields from the oil furnace are
greater than those of gas process and range from 35 to 65 percent depending on
the grade of black produced. Figure IV-2.2 shows the yields for the oil furnace
process. Oil furnace grades of carbon black are identified as follows:
SRF Semireinforcing furnace
HMF High-modulus furnace
GPF General-purpose furnace
FEF Fast-extrusion furnace
HAF High-abrasion furnace
SAP Superabrasion furnace
1SAF Intermediate-abrasion furnace
TV-5
-------
The yield of carbon black process also depends on efficiency of the
carbon black collection system. It Is coomon to find several types of air
pollution control devices used in series to collect the carbon particles like
cyclones and electrostatic precipitators.
CASHFLOW RATE
For all practical purposes the exhaust flow rate is 5 set of exhaust gas
for 7 acf of natural gas used in-the furnace process. The different grades
of carbon black are produced by varying the air fuel mixture and using different
types of gas (having different methane analysis). More air will result in
finer particles.
In order to get SAF grade of carton black, 50 percent of stoichiometric air
is required. To get HAF 80 percent of stoichiometric air is used (Figure IV-2.3)5
In the channel process natural gas Is burned with a limited air supply in
long low buildings. The flame contacts long steel channel sections depositing
the soot (carbon black) which is scrapped off later. The yields of this process
are low, 1 to 1.5 pounds of carbon black per 1000 ft.3 of natural gas. Exhaust
air flow is 100 scfm/1000 cfh of natural gas.
GAS TEMPERATTOE
Stack gas temperature ranges from 400 to 1000°F depending mainly on the
finished product; for modeling assume 500°F.
GAS VELOCITY
Gas velocity from the furnace black plants was not available. Based on
natural gas or oil combustion operations, velocities of 30 - 60 fps night be
expected. Observations of emissions from channel black plants suggest exit
velocities on the order of 10 fps.
STACK HEIGHT
Stack heights for the furnace bl.ck plants are expected to be consistently
in the range of 150 to 200 feet, channel black plants have no specific stacks,
so emissions would be generated as a line or area source at heights of no more
than 20 feet.
12 •
s:
.e
6 .
4
2
Carbon Black Produced = 0.57 x Natural Gas Input
(1000 Ib./hr.) " (million cfh)
5 10 15 20 25
Natural Gas Input (million cfh)
Figure IV-2.1 Average yield of carbon black from natural gas process
W-7
rv-6
•to----
-------
5 J
Carbon Black Produced = 5.0 x Liquid Hydrocarbon Input
Ob./hr.) (gal./hr/)
250 500 750 1,000
Liquid Hydrocarbon Input (gal./hr.)
Figure IV-2.2 Average yield of carbon black from fuel oil process
1V-8
10 •
1,000 1,250
Liquid Hydrocarbon Input (gal./hr.)
Figure IV-2.3 Exhaust rates for oil fired carbon black plants
IV-9
-------
TABLE IV- 3.1
Typical Analyses of
Per cent by weight
SOFTWOODS
Cedar, White
Cypress
Ft r , Douglas
Hemlock, Western
Pine , pitch
while
yellow
Redwood
HARDWOODS
Ash, white
Beech
Birch, white
Elm
Hickory
Maple
Oak, black
red
white
Poplar
c
o
n
•fi
id
U
48.80
54.98
52.3
50.4
59.00
52.55
52.60
53.5
49.73
51.64
49.77
50.35
49.67
50.64
48.78
49.49
50.44
51.64
g
s
•0
£
6.32-
6.54
6.3
5.8
7.19
6.08
7.02
5.9
6.93
6.26
6.49
6.57
6.59
6.02
6.09
6.62
6.59
6.26
g
60
fe,
K
O
44.46
38.08
40.5
41.4
32.68
41.25
40.07
40.3
43.04
41.45
43.45
42.34
43.11
41.74
44.98
43.74
42.73
41.45
JG
3
0.37
0.40
0.8
2.2
1.13
0.12
1.31
0.2
0.30
0.65
0.29
0.74
0.73
1.35
0.15
0.15
3.24
0.65
Dry Wood
Heating value
BTU per Ib.
w
01
JS
to
•rt
X
8400*
9870*
9050
8620
11320*
8900*
9610*
8840
8920*
8760*
8650*
8810*
8670*
8580
8180*
8690*
8810*
8920*
V4
3
7780
9234
8438
8056
10620
8308
8927
• 8266
8246
8151
8019
8171
8039
7995
7587
8037
8169
8311
3
u
CQ
8-8,
S^
4J &
4 rH
14 ^
•a -a
• (0
at m
O 01
M °
Is
709
712
719
705
702
722
709
707
709
728
714
717
712
719
713
711
713
715
zero excess
er cent
-*
CMn"
83
20.2
19.5
19.9
20.4
18.7
20.2
19.2
20.2
19.5
20.1
20.0
19.8
19.9
20.3
20.5
19.9
19.8
20.0
FIGURE IV-3.1 Missouri Type Charcoal Kiln
* Calculated from reported higher heating value of kiln-dried wood assumed to
contain eight per cent moisture.
IV-12
IV-13
•(•MM.
-------
CHAJTER IV-3
CHARCOAL PLANT
Charcoal is produced by heating various kinds of wood in air tight ovens
with controlled amounts of air. The high temperature breaks the wood down into
gases, tar, and the familiar carbon residue commonly known as charcoal. The
greatest use is home and outdoor recreational cooking. Annual production of
charcoal is about 500,000 tons with Missouri manufacturing about 125,000 tons/year.
The most popular production unit is the concrete Missouri-Type Kiln which
has a capacity of about 50 cords (128 ft. ). The average kiln size is about
20 ft. wide, 30 ft. long and 10 ft. high holding between 45 and 50 cords.
Operation of a typical kiln shows about 12 burns/year with each burn on a
23-25 day cycle? The typical cycle is shown below:
2 days to load
7 days to burn
12-14 days to cool
2 days to unload
The yield of charcoal from a given amount of wood is dependent upon the
amount of carbon in the wood and the coking process employed. However, the
yield is approximately 190 Ib. charcoal per cord of wood burned (Table IV-3.1).
Since charcoal ovens are ccunonly located in remote areas, sir
pollution control devices have not been used to date. The use of an
afterburner, following condensation of water vapor, to control organics
from the kiln has been suggested.
GAS FLOU RATE
The production of charcoal is by a slow burning process similar to coking
of coal. Emissions will occur about 7 days out of every 25. The total gaseous
emission rate is 1200 cfm from the 8 ports of a 50 cord kiln.
6,7
GAS TEMPERATURE
So data were available but temperatures should be on the order of 500 F.
8
IV-10
GAS VELOCITY
The exhaust gas velocity for charcoal plants is only slightly higher
o
than natural convection, about 10 fps.
STACK HEIGHT
Figure IV-3.1 is a sketch of a typical charcoal kiln. Stacks from this
kiln are tile ducts (6-8 inches in diameter) and extending 15 feet above the
top of the kiln
8
ivr-li
-------
CHAPTER IV-4
CHLORINE PLANT
B
Chlorine and caustic (NaOH) are produced concurrently by the electroly-
sis of aqueous sodium chloride. The production of chlorine in 1969 was
g
9.4 million tons from 70 plants scattered throughout the United States.
About .98 percent of the chlorine is produced by either the diaphragm or
the mercury cell process (Figure IV-4.1), The remainder is produced as
a by-product of other inorganic chemical industries. There are no major
operating differences in the input-output relationship of the mercury and
diaphragm cells, and hence they will be treated together.
Sodium chloride is obtained from brine wells, underground deposits of
solid salt, or ocean water. The salt is usually 95 percent pure, but in
most cases, it is chemically treated before being used in the electrolytic
cells to prevent adverse build up of impurities in the cells. For
practical purposes, the net conversion efficiency of brine to chlorine
is about SO percent for both types of cells, which means that the chlorine
production rate depends on the NaCl content of the brine. In most mercury
cell plants 10 percent of the NaCl is decomposed as it passes through the
cell each time (Figure IV-4.2). After chlorine leaves the cell it is
cooled, then dried with H.SO, and refrigerated into a liquid state. The
production rates of chlorine plants is quoted as tons of chlorine per day.
Atmospheric emissions from both mercury and dlaphram cell chlorine
plants include chlorine gas, carbon dioxide, carbon monoxide, and hydrogen.
Gaseous chlorine is discharged in the blow gas from the liquification
step and from vents in tank cars and storage tank containers during loading
and unloading. The major emission point from the chlorine plant is the
liquification process. However, most plants utilize an absorption tower to
catch free chlorine gas thus preventing its emission into the atmosphere.
Auxiliary air pollution control equipment is rarely used. Sometimes, hoods
are used to ventilate storage tanks, loading areas and liquification process
areas to be channeled through the absorption tower.
Chlorine plants are run continuously. Since chlorine is highly corrosive,
equipment lasts only for short periods and must be repaired frequently. A
plant will usually have more cells, more pumps, tanks, lines, etc., than
W-1A
theoretically required in order that repairs can be made without shutting
down the entire production process.
GAS FLOW RATE
The liqueficationprocess vent releases and total gas flow rates are small.
From the data obtained, it would seem that plant size has little to do with
volumetric flow rates (Table IV-4.1), Where no specific data is available,
use an exhaust flow rate of 600 scfm.
GAS TEMPERATURE
The temperatures of the exhaust gases are ambient (Table IV-4.1). Where
specific data are unavailable 60°F should be assumed.
GAS VELOCITY
Since flow rates are small, stack diameters also are small. Vent stacks
are usually less thar. 1 foot in diameter. Where specific information is un-
available, 6" diameter should be assumed and a velocity of 5-10 fps should be
used for modeling calculations.
STACK HEIGHT
The stack vents generally extend above the roof line about 10 feet making
a total stack height of about 50 feet.
IV-15
-------
TABLE IV-4.1
Exhaust Gases from Chlorine Plants
10
Production
Rate
tons/day
240
50
65
60
230 -
260'
130
112
262
180
458
Exhaust
Flow
scfm
1078
8
14.5
180
390
600
120
370
-
510
202
Exhaust
Temp.
•F
70
14
68
-
77
90
104
90
86
68
90
IV-16
il-AI
-------
30 -i
20.
10.
10% Conversion Rate
Feed Rate » 0.054 x Production Rate
(1000 gal. brine/hr.) (tons Cl2/day)
100 200 300 400 500
Production Rate (tons Cl2/day)
Figure IV-4.2 Feed rate as a function of chlorine plant size
IV-18
CHAPTER IV-5
HYDROFLUORIC ACID PLANTE
The 1966 production rate for hydrofluoric acid was 244,000 tons produced
by 15 plants in 10 states. Typical plant capacities range between 275 and
1,000 tons per day. Hydrofluoric acid is used mainly by the aluminum, fluoro-
carbon and petroleum industries. All hydrofluoric acid is manufactured by the
fluorspar-sulfuric acid process (Equation IV-5.1 and Figure IV-5.1).
CaF,
fluorspar
sulfuric acid
2 HF
(gas)
CaSO,.
IV-5.1
From Equation IV-5.1 it can be seen that about 2 pounds of fluorspar and 2^
pounds of sulfuric acid are necessary to make 1 pound of hydrofluoric acid
gas. Since the product, HF, is liberated as a gas, the entire process is
closed and good air pollution control serves as an economic benefit, in pre-
venting product loss. All plants, therefore, have good air pollution control
equipment. The eaic enission point is from the scrubber which collects water
vapor and dusts, liberated from heated rotary kilns (kilns are about 55 feet
long and 8 feet i^ diaoeter). Another emission point is the exit tail gases
(Figure IV-5.1) where limited amounts of HF, S02 and C02 are emitted after
passing through several absorption towers. Operational times for hydrofluoric
acid plants are continuous.
GAS FLOW RATE
The exhaust flow data from one plant was 15 scfm. Flow rates from
hydroflouric acid plants are not expected to exceed 1000 scfm.
The exhaust flow rate from the kiln is expected to be about 5,000 scfm.
No data vere available.
CAS
No data vere available, but exit temperatures are expected to be between
80 and 180°F. One plant reported 85°F. For calculation purposes use 120 F.
GAS VELOCITY
Low velocities are expected at the tail gas outlet. Assume 10 fps for
calculation purposes .
IV-19
-------
1Z-AI
STACK HEIGHT
So data vere available on hydrofluoric acid stack heights. A typical
range for other chemical processes is 100 - 200 feet. Use 150 feet for modeling.
3 »
IV-20
-------
CHAPTER IV-6
NITRIC ACID PLANT *
There are about 75 working plants in the United States which produce
over 5 million tons of nitric acid annually. The government owns emergency
plants which are operated only when needed. The plants are Scattered about
the country since the chief raw material is ammonia which is widely avail-
able. Nitric acid is principally used in the production of fertilizer. Other
uses include commercial explosives, rocket fuels and industrial applications.
There are three processes used to manufacture nitric acid: pressure
process, intermediate pressure process and atmospheric pressure process. The
chemistry behind each of these processes is identical. Although the emission
rates may vary from process to process, the input output function and exit
flow rates are about the same for the three processes. Approximately 90% of
the nitric acid is made by the pressure process. Older plants built before
1910 generally used the atmospheric process.
Anhydrous ammonia gas is mixed with hot air in the presence of a
platinum catalyst to form nitrogen oxide and then further oxidized to nitrogen
dioxide. NO reacts with water in an absorption tower to produce HNO, with
concentrations normally between 50 and 60 percent. Figure IV-6.1 shows the
flow diagram of a 120 ton-per-day nitric acid plant utilizing the pressure
process. These plants operate 24 hours per day.
The principal air pollutant emissions are the unconverted nitrogen
oxides. Almost all nitric acid plants have, in addition to the absorber
tower, catalytic fume abatement equipment (15% of the plants) or an alkaline
scrubbing system (857.) .
The three processes require about the same amount of raw material,
100 percent ammonia and preheated air, to produce the sane amount of nitric
acid (Figure IV-6.2). New plants will tend to have a more efficient
absorption tower and hence require not as much of the raw materials. In
general 1 pound of ammonia feed rate input will generate 8 pounds of 50 per-
cent HNO, output. Figure IV-6.2 indicates that nitric acid plants adhere
closely to design specifications and the recommended operating procedures since
little variation is evident.
IV-22
GAS FLOW RATE
Since air requirements are the same for all three processes, the exhaust
flow rates are also proportional even though some plants have gas treatment
equipment. Figure IV-6.3 indicates that nitric acid manufacturers adhere •
closely to the engineered operating procedures which have few operating
variables. In general the gas flow rate will be about 80 scfm per ton/day HNO-.
See Table IV-6.1.13'14
GAS TEMERAIURE
Exit gas temperatures are independent of the manufacturing processes.
The major factor affecting stack temperature is the abatement equipment being
used. The catalytic oxidizers create slightly higher exhaust temperatures.
The stack exit temperature from the catalytic oxidizer control systems is
about 450 F. When no abatement equipment is used, the temperature will range
from 75 to 120 F and a temperature of 80 F should be assumed as average.
GAS VELOCITY
Most nitric acid plants are designed to diffuse the stack emissions as
much as possible. The trenc today is toward tall sticks co aid in the dis-
persion of the nitrogen oxide gases. Increased temperature and velocity of
the gases increase effective stack height and further aid dispersion. One
plant in the United States uses a venturi device on top of a tall stack to
increase exit velocity and bring about greater dilution. The stack diameters
range from 3 to 8 feet and velocities range from 40 to 60 fps.
STACK HEIGHT
Most nitric acid plar.ts have stack heights between 150 and 250 feet.
New plants tend to have taller stacks for added dilution, which r,m about
350 feet.
IV-23
-------
TABLE IV-6.1
Exhaust Gases from Nitric Acid Plants
13,14
Production Ammonia
Rate Input Rate
tons/day 1000 Ib./hr.
No Waste Gas Treatment
60
120
120
120
120
180
200
265
750
700
Catalytic Haste Gas
110
120
140
150
170
185
230
350
1.454
2,750
2,750
2.750
2.750
4.000
4.740
6.670
18.750
17.500
Treatment
3.346
2.880
3.500
3.675
4.100
4.471
6,670
8.460
Exhaust
Flow
lOOOscfn
5.3
10.5
10.5
10.0
10.0
15.5
16.5
21.8
57.6
59.0
10.9
9.3
11.3
11.7
13.7
14.5
20.5
28.6
Exhaust
Temp.
"F
before after
450
450
450
450
450
450
450
450
450
-
840 1250
375 915
1500
502 1120
250 900
660 1190
570 930
1250
IV-24
Production
Rate
tons/day
TABLE IV-6.1 (Continued)
Exhaust Gases from Nitric Acid Plants
Ammonia
Input Rate
1000 Ib./hr.
Catalytic Waste Gas Treatment (cent.)
140 3.500
220 6.150
280 6.800
340 8.600
Alkaline Scrubbers
50 1.200
LIO 2.900
Exhaust
Flow
1000 scfm
11.3
20.0
21.2
27.1
3.5
8.9
Exhaust
Temp.
°F
before after
IV-25
-------
9Z-A1
I I t I I I I I I I ' I I Jl 3
i I i i i i i i i i i i i j i.
i
2
O
m
•30
rn
CO
30
Feet1 Rate = 0.025 x Production Rate
- No Waste Gas Treatment
g Waste Gas Treatment
(acid strenoth 55")
600 800
Production Rate (tons/day)
Figure IV-6.2 Nitric Acid Plant Capacity as a Function of Ammonia
Feed Rate.
W-27
-------
60-
40
30-.
10 H
O
R=.997
Exhaust Flow Sate * 3.16 x Feed Rate + 0,7
3 No Waste rias Treatment
® Haste Gas Treatment
(acid strength 55%)
200
400
600
800
1000
NH3 Feed Rate (1,000 Ib./hr.)
Figure IV-6.3 Exhaust flow rates at various feed rates in the production
of Nitric acid.
IV-28
CHAPTER IV-7
PAINT AND VARNISH PLANT B
In 1963 there were 1,800 paint and varnish manufacturers in the U. S.
consuming as many as 2000 different raw materials. Because of the variety
of raw material input to these plants and wide commercial distribution of
finished products, paint and varnish plants are scattered throughout the U. S.
The manufacturing processes of paint and varnish are closely related since
paint is, with some modifications, a pigmented resinless varnish. With the
exception of paint pigment and varnish resin, the raw materials for paints and
varnishes are the same: oils and/or thinner*, antlskinming agents to prevent
gelling, additives to increase the drying rate and plasticizers to minimize
cracking of the dried film. Paint pigments may be either organic or inorganic
dyes; varnish resins may be natural or synthetic. The production process for
paint (Figure IV-7.1) includes the assembling, weighing and mixing of pigments
and oils which are fed into a grinding mill to produce a smooth product. The
paint is then thinned and filtered to remove nondispersed pigments. Varnish
production differs from paint production in that a resin depolyraerization step
replaces the mixing step in paint production. Depolyoerization is accomplished
by heating resin to 550 - 650 F until the desired viscosity is obtained. The
product is cooled and transferred to the thinning tank where final ingredients
(dryers, plasticizers, etc.) are added. '
Air pollution emissions from paint production are of two types: particulates,
from handling the pigments and fillers prior to mixing, and organic vapors from
the oils and thinners used in the mixer and thinning tanks. These emissions are
controlled with either scrubbers or afterburners. Emissions from varnish production
are greater because of the heat required in the depolymerization reaction. This
reaction takes place in either open or closed varnish cooking kettles, varying in
capacity from 100 to several thousand gallons. Closed kettles generate few
emissions, but open kettles emit significant quantities of acrolein and other
odorous compounds and particulates. These emissions may be efficiently con-
trolled through use of wet scrubbers or afterburners.
GAS FLOW BATE
Exhaust flow rates (Table IV-7.1) ranged from 600 to 3050 scfm with a mean
of 1200 scfia for 200 gal./hr. mixers and 320 to 950 scfm and a mean of 650 scfm
IV-29
-------
17 IR
for Settles. *As flow rates may vary from plant to plant, actual data should be
used when available for caluclations. The above air flows equate to 6 scfm per
gal./hr. of paint produced and 0.5 scfm per gal./hr. of varnish produced.
GAS TEMPERATURE
If no control equipment is employed, stack gas temperature will be essen-
tially the ambient temperature for mixers and 140 F for kettles. When an
afterburner type control is used, stack gas temperatures will be about 1150 F.
GAS VELOCITY
The exit velocity for mixers and kettles was about 15 fps. Because
of the low flow rates, velocities would not usually exceed 20 fps,
therefore, use 15 fps.
STACK HEIGHT
From available data all stack heights were below 50 feet. If no actual
data are available, use a 40 ft. stack height for calculations.
IV-30
TE-AI
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x n -"^ n ^ o "^^ o '•^ OT xo xx *•
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X ^
3 I
§.
H-
3-
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rf
00
-------
FIGURE IV-7.1
I
Operating
Tine
14
.*s
4> 8
« s
«£«
at >i-i >w
W B
X
w
w •§ ^*
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-------
CHAPTER IV-8
PHOSPHORIC ACID PLANT B
Production of phosphoric acid approaches a rate of 5 million tons per
year. Phosphoric acid is a raw material to the fertilizer Industry and to
the food, drug and detergent users. Each user requires different concentrations
of H PO, for its particular application which almost mandates a "custom house"
product. Instead of new plants being built, existing plants have been modified
to meet increasing demands. There are about 80 phosphoric acid plants in the
United States with no particular significance to geographic locations.
Phosphoric acid is produced in one of two ways: wet process manufacture
or thermal process manufacture. The wet process manufacture is oldest and
cheapest. Since the processes operate differently, each will be presented
independently to provide a comprehensive analysis.
"Wet Process"19
Phosphoric acid obtained through the wet process is used in the manufacture
of phosphate fertilizer. Figure IV-8.1 shows a diagram of the wet process
manufacturing plant. In this process phosphate rock containing fluorapatite,
Ca (PO.).F , is ground and mixed with concentrated sulfuric acid to produce
phosphoric acid. A 32 percent available P^O, fluorapatite will make a final
solution of 54 percent phosphoric acid. Capacity of phosphoric acid plants is
usually given in tons/day of PjO.. Equation IV-8.1 may be used to calculate
the amount of raw fluorapatite used to make phosphoric acid assuming that the
fluorapatite contains 32 percent f^Q, (narrow range between 31-35.5 percent)
and the phosphoric acid is concentrated to 54 percent in the final stage.
Fluorapatite Input (Ib./hr.) - Ib. HjPO^/hr. x ?.33 IV-8.1
Principal air pollutants from phosphoric acid plants are gaseous fluoride
and fluoride particulates from the digester, evaporator and the filter
(Figure IV-8.1). The evaporator in a sense is an air pollution control device;
however, additional scrubbers are used on most plants. Emissions from the
digester and filter are collected with the use of hoods and vented to collectors.
Commonly used venturi scrubbers have collection efficiency ranges from 85 to
95 percent for the gaseous fluoride emissions and almost 100 percent efficiency
for particulates.
The production of phosphoric acid is a continuous process and therefore
runs 24 hours a day.
IV-34
GAS FLOW RATE
Exhaust flow rates depend entirely on air pollution control ducting and
ventilation configuration (Figure IV-8.2). Some plants only control emissions
from the digester while others control emissions from all three sources,
digester, filter and evaporator. The plants often combine gases from the
digesters, filters, hoods and send them to a common collection device like the
scrubber. The figure and Tables IV-8.1,8.2, and 8.3 show flow rates coming
from the digester between 10 and 50 scfm per ton/day of acid produced and 60
19
scfm per ton/day for the filter hood. Gas flow from the evaporator generally
represents a very small portion of the total plant exhaust. Combined exhaust
flows showed 8,500 scfm for a 150 ton/day plant or 57 scfm per ton/day of acid
production.
GAS TEMPERATURE
Since most of the gas entering the scrubber systems comes from hoods over
the filter and digester ir. the plant, exhaust gas temperature will be near
ambient conditions. Data for 12 digesters showed temperatures between 75 and
160°F; for the scrubber exhausts, 85° to 95°F was reported; filter hoods, towers
and cor.bined exhausts ranged from 80 - 102°F; 100°F should be assuraed as typical.
GAS VELOCm
Since the diameter of the stacks was not known for any of the plants where
other data were obtained, no gas velocities could be calculated. Where specific
data are unavailable 30 fps should be assumed.
STACK HEIGHT
The stacks on phosphoric acid plants are usually less than 3 feet in
diameter, brick or rubber lined to prohibit corrosion, and short (between
5 and 20 feet above the roof of the plant). Therefore total stack height
would be expected to range from 30 - 60 feet averaging about 50 feet.
"Thermal Process"
The thermal process accounts for about one third of the Ration's phosphoric
acid production. This acid is used to produce high quality phosphates for the food,
drug, and detergent Industries. The cost is nearly twice the cost of H^PO^
produced by the wet process. Host plants produce 75 to 80 percent phosphoric
acid but some can produce 115 percent H.PO. (Figure IV 8.5).
-------
Figure IV-8.3 shows a schematic diagram for manufacture of phosphoric
acid by the thermal process method. Raw materials for this method Include
elemental (yellow) phosphorous, air and water. Phosphorous is usually handled
in the molten state at the plant site. It is mined from the ground and
processed into a molten state by electric furnaces. The phosphorous is burned
and water is added to the combustion gases and later collected in the
hydrator-absorber.
Air pollution emissions are principally the H-PO, mist, since the
hydrator absorber is not a perfect collector of the acid mist. Depending on
end use, other chemicals may be added which may or may not give additional
emissions. For example, sodium hydrosulfide is often added to the phosphoric
acid that is used in the food industry. All thermal process phosphoric acid
plants have abatement equipment. Venturi scrubbers, packed scrubbers, glass
fiber mist eliminators, wire mesh mist eliminators and electrostatic pre-
cipatators are commonly used as control equipment.
The production of phosphoric acid is a continuous process and operates
at all times of the day and year with no particular fluctuation in the process.
The chemical reactions necessary to produce H^PO, are:
P4+5°2
VlO
<
P4°10+H2° ^>
One pound of phosphorous will make about 3.2 pounds of phosphoric acid. The con-
centration of H PO, is always expressed as percent P 0_. Assuming that raw
phosphorous is in a near pure (1007, P^) molten state. Equation TV-8.2 can be
used to determine the amount of phosphorous input.
production rate (Ib./hr.) x 0.725
Raw phosphorous input (Ib./hr.) • 4 x (~,H-PO ) rv-8 2
GAS FLOW RATE
Exhaust gases are derived from the combustion of phosphorous and the
addition of steam into an enclosed system. Figure IV-8.4 shows a linear
relationship with little variation which is attributed to the closed system.
Exhaust flow will be a little over 2.0 scfm for every 1 Ib./hr. of phosphorous
feed. Typical flow rates are 5,000 - 20,000 sera for these plants.
GAS TEMPERATURE
Table IV-8.4 indicates exhaust temperatures and plant capacities for
twenty-five plants. Where specific data are unavailable, 170°F should be
assumed as average since the temperature is consistently between 117 and
201°F,
GAS VELOCITY
No data were available, but since flow rates from the thermal process
are relatively small (5,000 - 20,000 scfm), the velocities are not expected
to be high. Where data are unavailable 30 fps may be assumed.
STACK HEIGHT
No data were available but stack heights are determined by the air
pollution control system configuration. When specific data from phosphoric
acid plants is not available a stack height of 50 feet should be used for
nodeling purposes.
IV-37
IV-36
-------
TABLE IV-8.1
Exhaust Gases from Wet Process
Phosphoric Acid Plant Digesters
19
Production
Rate
tpd P205
107.5
107.5
107.5
156
156
156
130
130
130
639
639
639
Exhaust
Flow
1000 «cfm
3.8
3.9
4.0
7.7
7.7
7.5
1.8
2.1
1.8
5.4
5.4
5.4
Exhai
T
160
160
160
75
75
75
130
130
135
84
84
84
IV-38
TABLE IV-8.2
Exhaust Gases from Wet Process
19
Phosphoric Acid Plants
Scrubbers
Production
Rate
tpd P2C5
1080
1080
1080
400
400
400
745
745
745
Exhaust
Flow
1000 scrm
17.0
17.0
17.0
40.8
40.8
40.8
30.2
30.2
30.2
Exhaust
Temp.
85
85
85
95
95
95
IV-39
-------
TABLE IV-8.3
Exhaust Gases from Wet Process
Phosphoric Acid Plant Sources
19
All (Digester, Scrubber
Filter hood)
TABLE IV-8.4
Exhaust Gases from Thermal Process Phosphoric Acid Plants
20
Based on 85% Acid
Production
Rate
tpd P2Dj
Filter Hood:
107.5
107.5
107.5
Exhaust
Flow
1000 scfrn
6.1
6.7
6.6
Exh<
80
80
80
150
150
150
Tower
103
103
103
8.7
8.7
8.7
15.6
15.6
15.6
102
102
102
90
90
90
Production
Bate
tons /day
116
116
116
359
127
166
179
178
97
268
88
170
268
238
309
Input
Rate
1000 Ib/hr
2.59
2.60
2.60
8.64
2.87
3.75
4.00
4.00
2.25
5.70
2.00
3.95
6.00
5.30
7.00
Exhaust
Flow
1000 scfn
7,0
7.9
7.0
22.0
9.9
12.9
10. 0
13.9
6.4
13.2
5.0
-.5
7.0
6.7
15.8
Exhaust
Temp.
°F.
176
189
175
180
176
170
184
176
150
150
175
175
142
201
168
OT-40
-------
TABLE IV-8.4
Exhaust Gasea fron Thermal Process Phosphoric Acid Plants, Continued
Based on 85% Acid
Production Input Exhaust Exhaust
RatC Rate Flw Tent,
tons/day 1000 Ib/hr 1000 scfa °?
178 4 00 18 0
106 " 2-60 5'1 185
177 / nt *. *
177 4.03 6.2 J80
53 1.50 3.5 136
456 11.00 30.7 165
NA 11.10 19.8 182
358 8.00 12.4 m
106 2,27 8.8 175
"2 3.00 3.7 m
Average 191 4-63 9.9 lfi^
~n
ri>
OD
~n
o
o.
OJ
3
trt
3
r*
3
CW
CD
T3
3
n
fD
-o
o
r>
o»
Q.
TO 1
3
rt-
to ~n
rt-
S1 2
3 rt-
C
3
CO
c
-I ^> z
«< ^" a.
r* n' 0
0 -• -h ^
o o* o
3 0 I
d. -J-
d.
Ground Phosphate
Rock
Sulfuric
Acid
fl
O fD
1
1 '
-rj
rt-
1 '
O)
c?
s
< '
Concentrated
Phosphoric
Acid
n
E, g
a C
^ n
S 5
3 — '
r*-
1
l/l
rf
n
-------
30.
x All and Filter Hood
® Scrubber
O Digestion
« I
250 500 750 1000 1250
Capacity Rating (tons/day)
Figure IV-8.2 Exhaust flow rate vs. production for wet process phosphoric
acid plant
IV-44
-------
30
20
10
0
0 O
©
e
Exhaust flow rate = 2.16 x feed rate +1.19
2468
Phosphorus Feed Rate (1,000 Ib./hr.)
10
Figure IV-8.4 Exhaust flow rate vs. Feed rate for phosphoric acid
thermal process
rv-46
12-
10-
6 -
2 -
R=.996
Incut Sat? = 0.323 x Deduction Rate
(1,000 Ib. 'h».; (tons/day)
100 200 300 400
Production Rate (.tons/day)
500
Figure IV-8.5 Input rates for the thermal process production of
phosphoric acid.
IV-47
-------
CHAPTER IV-9
PHIHALIC ANHYDRIDE PLANT
Phthalic anhydride was produced by twelve manufactures at sixteen plants In
the continental U. S. and one In Puerto Rico in 1970 (Table IV-9.1). Annual pro-
duction rates are about 1.2 billion pounds with Individual plant capacities
ranging from 30 million to 130 million pounds per year. Over ninety percent of
U.S. phthalic anhydride is used for paints, plastics and synthetic resins.
Fhthalic anhydride is produced conmercially from catalytic oxidation of
naphthalene (or, more recently, o-xylene) with excess air In fixed or fluid
bed converters. Figure IV-9.1 is the flow diagram for the fixed bed process.
Only a few plants use the older fixed bed process since fluid bed processing
has been demonstrated to be more economical. 0-Xylene has slightly higher
yields (pounds of phthalic anhydride per pound of raw material) with ranges
from 70 to 95 percent while naphthalene has typical yield ranges from 70 to 85
percent (Figure IV-9.2). There are few operating variables in the phthalic
anhydride plant thus variations from plant to plant are minimal. Plants
operate continuously 3 shifts per day and 7 days a week.
The principal air pollution problem of a phthalic anhydride plant is off
gas leaving the phthalic anhydride condensers. Major air contaminants include
strong odors, phthalic anhydride (40-200 ppm), maleic anhydride (100-600 ppm),
aldehydes (LO-100) ppm and carbon monoxide (6,000 - 50,000 ppm). Some fixed bed
plants have air pollution scrubbers as a control measure for the off gas. Other
plants use catalytic burners to oxidize contaminants. Control system exhaust
flow rate depends on the size of the process unit and plant size. Minor problems
Include fumes from beed and products storage tanks, venting during refining,
flaking and bagging and leaks from the heat transfer fluid, Dowtherm. Whenever
the minor points of emission are vented with the off gas, a larger unit is required.
GAS FLOW RATE
Gas flow rates for the fluid bed process are lower than fixed bed process
and may be estimated with the aid of Table IV-9.2 and Figure FV-9.3.17
IV-48
GA3 TEMPERATURE
Exhaust gas temperatures from dry recovery condensers (commonly used with
the fluid bed processes) range from 120 to 140°F. For the wet recovery systems
(found with a fixed bed process) temperatures are 150 to 160°F. The wet recovery
system is saturated with water and emits a large white plume as the moisture
condenses in the stack and ambient air. For calculations, assume 140°F.
GAS VELOCITY.
Gas exit velocity for plants having air pollution controls averaged 35 fps.
Other plants had a stack exit velocity of 0.1 - 6.3 fps.
STACK HEIGHT
Stack heights for phthalic anhydride plants ranged from 12 to 110 feet with
a mean of about 70 feet. Most plants not having any controls had stack heights
of less than 30 feet.
W-49
-------
1S-AI
TA31E IV-^.l
Phthalic anhydride manufacturers
and locations
Manufacturer
Allied Chemical Corp.
Allied Chemical Corp.
Allied Chemical Corp.
BASF Corp.
W. R. Grace & Co.
(Hatco)
Stoppers Company, Inc.
Koppers Company, Inc.
Monsanto Company
Monsanto Company
Chevron Chemical Co.
(Oronite)
Hooker Chemical Corp.
Reichhold Chemicals, Inc.
Reichhold Chemicals, Inc.
The Sherwin-Williams C.
Stephan Chemical Company
Union Carbide Corp.
United States Steel Corp.
Location
El Segundo, California
Ironton, Ohio
Philadelphia, Pennsylvania
So, Kearney, N. J.
Fords, K. J.
Bridgevtlle, Pa.
Chicago, 111.
Texas City, Texas
Glouster Co., N. J.
Richmond, California
Puerto Rico
Elizabeth, N. J.
Chicago, 111.
Chicago, Illinois
Millsdale, Illinois
Institute, W. Va.
Neville Island, Pa.
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IV-53
§
u
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-------
15 -
10 -
5 -
Naphthalene
(80% yield)
Ortho-Xylene
(80"= yield)
25
50
75
TOO
125
Phthalic Anhydride Plant Capacity (tons/day)
Figure IV-9.2 Plant capacity vs. feed rate for Phthalic Anhydride
production
W-54
150
— 100 -
50 -
Fluid Bed
5 10 15 20
Raw Material Feed Rate (1,000 Ib./hr.)
Figure IV-9.3 Exhaust flow rates for various feed rates
in production of Phthalic Anhydride
W-55
-------
CHAPTER IV-10
PLASTICS PLANT B
The manufacture of synthetic resins or plastics is mainly a polymerization
process. Various raw materials, gas and liquid, are processed to provide long
chain-like molecules which are the pith of plastic production. The 1964 annual
production rate was 10 billion pounds. As in the case with other polymerization
type industries, there are a large number of finished products (plastics) which
are made from a variety of raw materials. By varying monomers, different products
are manufactured. Raw materials used in manufacturing plastics include for-
maldehyde, phenol, phthalic anhydride, butadiene, ethylene, propylene and styrene.
processing is entirely closed within stainless steel vessels and transport lines.
Most pla=ts run continuously for 24 hours per day and 7 days a week with
virtually no shut down.
Plastic plants may or may not generate air contaminants. In all cases,
emissions will be highly variable. For example, holding tanks for the monomers
or other input materials often are vented to the atmosphere, but, depending on
volatility and vapor pressure,little or no hydrocarbons may be discharged unless
the tank is filled. Likewise, holding or weighing tanks will only produce emissions
when being filled. The reactors themselves will generate a continuous small
volume of hydrocarbons during polymerization. The only control equipment would
be catalytic afterourners in the sire range of 2-10,000 scfra for combinations of
vents or reactor exhausts.
Tvpical process weights from various plants run froin 800 to 40,000 Ib./hr.
(Table IV-10.11 ' Plant capacity is determined by the number of polymerization
units When more production capacity is needed, another "line" or series of
polymerization units are added.
GAS FLOW RATE
Based on available data from five plants, exhaust flows ranged from SO
to 8,000 scfm (Table IV-10.1). Figure IV-10.1 provides a display of the
data which shows that no apparent relationship exists between exhaust flow and
process weight. Some flow rates (it is not known which ones) probably vent an
entire area including the polymerization vessel while others represent only the
off gases from one reactor vessel. For modeling purposes, the exhaust flow of
rv-56
the control device/stack should be used, if known. When no information is
available use 5,000 scfm for the total plant.
GAS TEMPERATURE
Gas temperatures for the plants available ranged from ambient to 1400 F.
However, 10 of the 11 data points were 150°F or lower. It is speculated that
the one plant which exited flue gases at 1400 F probably had an afterburner in
operation. A mean temperature of 100 F can be assumed when no control equipment
is used.
GAS VELOCITY
A stack velocity of 35 fps should be used for modeling. The range was
from 1 to 67 fps. It is apparent from the data that velocity is independent
of the size of the operation but depends on the particular plastic being
produced or design of the process equipment itself.
STACK HEIGHT
Table IV-10.1 shows vent and reactor stacks to range in height from 8 to
105 feet, with about 60 feet being the cean.
IV-57
-------
TABLE IV-10.1
Input
Rate
1000 Ib./hr.
0.8
40.0
40.0
1.2
1.5
5.0
1.5
31.2
5.0 ~
- 1,0 . -
275
11.8
Exhaust
Exhaust
Flow
1000 scfm
7.98
1.20
0.74
0.05
0.50
2.74
6.00
4.78
0.54
0.45
1.70
3.43
Gases from Plastics
Exhaust
Temp.
°F
1400
Ambient
150
Ambient
Ambient
120
Ambient
150
Ambient
i-K
70
211
Plants17
Exit
Velocity
1000 fps
120.0
36.0
255.0
36.0
120.0
138.0
123.6
150.0
394.8
Ii7.0
3.0
138.5
Stack
Height
ft.
8
91
10
80
40
103
40
105
32
40
98
58.8
6
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u
o
o
~ 4 .
O)
ITS
1
L-
J5
_c
X
2 •
o
G
Z
3
O
^
«*
IV-58
13 20 30 40 50
Input Rate (1,000 Ib./hr.)
Figure IV-10.1 Exhaust flow rate vs. process weioht for plastic plants
IV-59
Bfcv,
-------
CHAPTER IV-ll
PRINTING INK PLANT E
Printing inks consist of a fine dispersion of pigments or dyes In a
vehicle which may be drying oils with or without natural or synthetic resins
and added driers or thiners. The composition of printing inks vaiiea as to
specific application or end use, with some containing a higher percentage of
driers i.as chose used for newspaper ink), while others contain high percentages
of r«si^s for high gloss applications.
There are two basic types of inks; 80 percent of the ink is of an oil
tyye which is used for offset and letter press and 20 percent is of a sol-
vent tvp* vhich is used for flexographic and gravure operations. There are
about 530 - 600 ink manufacturers scattered through the U. S.,and they manu-
facture about 1 billion pounds per year.
The jianufacture of printing ink is a mixing operation which is carried
24
out in steel tubs. Most all manufacturers buy the base resins from paint
suppliers. There is no heat associated with the process. The principle air
pollutant is dry color pigments. All plants will control pigment particulates
with either portable or permanent scrubbers (and baghouses) to prevent
contamination of other inks. The solvent type inks are mixed in tanks and are
24
in an entirely closed system. Few plants have solvent vapor control equipment,
Plar.ts typically operate 1 or 2 shifts a day lor 5 to 6 days a week.
is about 20 - 40 fps.
STACK HEIGHT
Stack heights are expected to be about 30 feet since most plants are
one story buildings.
GAS FUV RATE
So data were available to analyze flow rates. It is estimated that
between 2,000 and 10,000 scftn are used to control pigment dusts from each
24
tub during the loading of the raw pigment into the tubs. For solvent type
operations there is no flow rate.
GAS
Since no combustion is taking place within the process, the gas exit
temperature will be ambient.
SAS VELOCITY
So specific data were obtained. The exit velocity from controlled plant*
IV-60
IV-61
-------
CHAPTER IV-12
SOAP AND DETERGENTS PLANT C
"Detergents"
The use of detergents as a cleansing agent for domestic and industrial use
has risen rapidly since 1945 to an annual production of about 3 million pounds-
Synthetic detergents are manufactured continuously from a number of sur-
factant naterials, builders and additives. A typical example of the raw
materials follows for producing 1000 Ibs. of finished product:
Ingredient Pounds
Surfactant materials
Alkylbenzene
Fatty Alcohol
Oleum
NaOH solution
Corrosive inhibitor
Sodiun silicate
Builder
Sodium tripolyphosphate
Miscellaneous additives
Vater
75
75
150
200
125
500
30
500
Tr.e rav cateriais are mixed and passed through a crusher to a drop tanK.
The vet slurry is then spray dried in a vertical countercurrent tower with the
dried detergent leaving at the bottom and exhaust gases exiting the top
(Figure IV-12.1).
The ratios of the various raw materials will depend upon which end use is
sought. However, no simple relationship exists between input and output.
The najor source of emission is the spray drying tower (Figure IV-12.1).
The drying normally occurs in large towers 20 feet in diameter and about 100
feet high. Cyclones are used to remove the detergent particles from the con-
veying air stream and these fines are returned to the process. Additional
controls such as spray chambers, packed scrubbers or venturi scrubbers may
follow the cyclone.
25
IV-62
GAS FLOW RATE
From available data drying tower flow rates ranged from 14,000 to 66,000
scfm. However, concurrent production data were not available for this one
plant. Where specific information if unknown 40,000 scfm may be assumed.
GAS TEMPERATURE
Temperature of gases from the spray dryer is relatively constant ranging
from 120 to 129°F for all types of detergents. Where data is unavailable 12C°F
should be used. Exit temperatures from handling and airveying operations would
be ambient.
GAS VELOCITY
Gas velocity from six drier stacks ranged from 33 to 156 fps with about
100 fps the average velocity. Data from one plant showed stack diameters of
3 feet.
STACK HEIGHT
Stacks from the drier are generally located on the roof of the manufacturing
plant and extend above roof line. Since the drying towers are 100 or so feet in
height, stack height can be expected to range from 100 to 125 feet with 125 feet
about average. However, the data from one plant with five driers showed stack
heights of 15.5 to 45 feet; it is speculated that these heights are above the
roof. For calculations assune at least 50 feet for s-tack height.
Soap is manufactured on a large scale with most plants having a capacity of
about 300 tons/day. Tallow is the principal material used in soap making. Soap
plants are scattered about the country since the raw materials are abundant.
The soap making process is simple: raw materials are heated, mixed with
chemical additives, then chilled, dried and pressed into bars. The principal
air pollution problem from a soap plant is odors. Originally, odors fron the
centrifuge room were exhausted directly to the atmosphere, but today most soap
plants have control equipment installed. Some plants reportedly use venturi
scrubbers to attain an odor elimination efficiency of up to 90 percent. Catalytic
oxidizers also are used to control odors.
IV-63
-------
UAS glow RATE
No data were available, but, since the size of the air pollution control
device is dependent on the volume of the room or plant being ventilated, most
planfs would keep the volume to a minimum to increase efficiencies and de-
crease costs. It is suggested that 5,000 acfm be used in estimates.
GAS IEMPERAHJRE
No data were available but for all practical purposes, the gas temperatures
would have to be ambient since room ventilation air is being exhausted. Therefore,
use 60 in calculations.
CAS VELOCITY
No data were available but maximum velocities above 50 fps would not
likely be exceeded due to increased friction losses.
STACK HEIGHT
No data were available but assuming soap and detergent would be manufactured
in the same plant, stack heights certainly would not exceed detergent drier
stacks and most likely would be less than 50 feet high. Table IV-12.1 provides
information for both detergents and soap.
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IV-64
-------
99-AI
•MtV.
CHAPTER IV-13
A
SULFURIC ACID PLANT
Sulfuric acid is largely used as a raw material in an extremely wide
range of industrial process and manufacturing operations with one-third of
it being used for the production of phosphate fertilizer. Sulfuric acid plants
are scattered throughout the U.S. There are about 215 contact H2SO^ plants which
account for 90 percent of the 20,500,000 tons produced annually. The remaining
10 percent is produced by the older lead chamber process. The chamber process
is tending to become a very small factor in Sulfuric acid manufacture because
of the weak solution and initial construction costs. Chamber plants in
general are captive, are of low capacity, and are considered a small air
pollution potential for the U.S.
The yellow sulfur mineral itself (appearing mainly in the molten state)
accounts for about 75 percent of the raw material used for Sulfuric acid
production. In either the contact or chamber process one pound of raw
27
sulfur is needed to make 3 pounds of Sulfuric acid (100 percent concentration).
1 ton/day raw sulfur input « 3 ton/day H,50^ outPut IV-13.1
The major source of emission from the contact Sulfuric acid plant is the
exit gas from the absorber. Minor amounts of sulfur oxides may be emitted to
the atmosphere from tank car and drum loading operations and from storage
tank vents. Other pollutants like nitrogen oxides may be emitted from the
process acid tanks in the chamber process.
Sulfuric acid plants usually have no air pollution control devices per se.
The absorber could be considered as an air pollution device sints its function
is to absorb the SO, gases produced earlier in the processes. The greater the
absorption efficiency, the less SO- emissions will result. Thus.it is the
efficiency of the absorbtion system which determines the emission factors.
Single and two stage absorber systems reduce SO, concentrations in tail gases
28
to 1000-5000 ppm and 500 ppm, respectively. Further reduction may be ob-
tained with wet scrubbing units using soda ash, sodium sulfite, bisulfite and
plain water. Electrostatic precipltators may also be used in conjunction with
the wet purification systems. These devices do not change flue gas flow rates
but nay produce a temperature drop. Tables IV-13.1 and IV-13.2 list operational
for plants with and without mist elimination.
W-67
-------
GAS ''LOW RATE
Figures IV-13.1 and 13.2 indicate chat the exhaust gas flow rate Is a near
linear function of the daily production rate. There does not seam to be a
significant difference whether solid or molten dark raw sulfur is used or
whether air dilutation or no air dilution is used and only a small differ-
ence whether or not mist eliminators are used. Thus, by knowing only the
production rate of sulfuric acid the exhaust flow rate can be determined
accurately.
GAS TEMPERATURE
There does not seem to be a general relationship about flue gas tempera-
tures. Based on the collected data the temperatures ranged from 76 to 212°F
with an average of about 160 F. No conclusions could be made regarding the
effect on temperature of mist eliminators, type processes, molten or solid
raw sulfur or plant efficiency.
GAS VELOCITY
Of the 6 plants where gas velocity data were available, the velocity
ranged from 775 to 2,820 fpm with an average of near 1,800 fpm or 30 fps.
STACK
The stacks from sulfuric acid plants mostly range from 100 to 200 feet
in height and are about 2 to 3 feet in diameter. The stacks are usually metal
ar.d for sooe reason painted with red and white stripes . Where such data are
unavailable 150 feet should be used.
IV-68
TABLE TV-13.1
Exhaust Gases from Sulfuric Acid Plants Without Mist Eliminators
27
Production
Kate
tons /day
735
650
650
120
422
130
100
100
325
325
162
115
210
500
310
265
285
650
302
900
Exhaus t
Flow
1000 scfci
48
52
52
8.2
27.0
8.0
7
7
18.0
17.9
11.8
6.4
12.9
32.3
18.3
15.0
21.1
63.0
21.2
66.8
Exhaust
Tgmp.
212
175
175
115
123
175
173
163
148
148
140
94
-
170
105
170
190
136
163
145
Conversii
(%)
97.8
96.0
96.0
97.5
97.5
97.2
97.8
97.8
95.7
95.6
98.5
98.1
97. r
96.7
97.6
96.5
97.5
96.3
98.7
97.8
rv-69
-------
TAB1E IV-13.2
Exhaust Gases from Sulfuric Acid Plants With Mist Eliminators
27
Production
Rate
tons /day
961
150
150
240
240
219
133
300
265
300
429
272
429
422
272
302
Exhaust
Flow
1000 scfm
62
. 8.0
8.0
• -
-
13.0
8
18
15
23
30.2
20.8
30.2
27.0
20.8
21.2
Exhaust
186
165
166
180
180
76
76
175
160
180
176
150
176
123
150
163
33.2
27.0
18.0
12.9
Conversion
(%)
98.5
97.6
97.5
97.2
98.2
98.2
96.9
98.0
97.8
98.0
96.7
98.0
97.5
97.6
97.8
rv-70
60 .
R=.973
40 .
G
20 .
Exhaust flow rate = 0.074 x production rate - 3.0
200 400 600 800
Production Rate (tons/day)
1000
Figure IV-13.1 Exhaust gas flow rate as a function of production rates
for the sulfuric acid contact process without mist
eliminators.
rv-71
-------
60 "
2
40
20
R=.990
Exhaust flow rate
(1,000 scfm)
0.062 x production rate
(tons H2S04/day)
200 400 600 800 1000
Production Rate (tons H2S04/day)
Figure IV-13.2 Exhaust gas flow rate as a function of production
rates for the sulfuric acid contact process with
mist eliminators.
iv-72
CHAPTER IV-14
SYNTHETIC FIBERS PLANT D
Synthetic fiber production includes nylon, orlon, dacron, rayon and
acrylic, although nylon alone constitutes about 25 percent of the total
synthetic fiber production in the U. S. The annual production rate of non-
cellulosics (true synthetic) fibers was about 1.2 billion pounds in 1965
processed from about 25 plants scattered around the V. S. Typical plant
size is about 50 - 150 million pounds per year.
Basic raw materials for non-eellulosic fibers are mainly carbon-hydrogen
chains originating from natural gas and petroleum fractions. The flow
diagran for & synthetic fiber manufacturing process is shown in Figure IV-14.I.
Ingredients used in the manufacture of three synthetic fibers include:
nylon 66 - adipic acid, hexamethylene diaoine
dacron - dinethyl terephthalate and ethylene glycol
acrylon and orlon - acroylonitrile
the chemical manufacturing process is alnost entirely an enclosed system
acd co by-products are formed; thus, for every pound of raw naterials used
the yield is a pound of fiber, large nylon plants are located in Seaford,
Delaware; Martinsville and Richmond, Virginia; and Chattanooga , Tennessee.
The plants operate continuously 24 hours a day and 365 days a year.
Ihe polymerization process is a batch process. Each autoclave reactor
or blender has a capacity of about 1 ton. Plant capacity,however, depends
pricarily on the number of evaporators available. Potential air pollution
problens are aainly attributed to the evaporators vnere vrater vapor and
hydrocarbons are emitted. The evaporators are under pressure and "trickle
off" during this phase. Usually a small 2" vent pipe is used. At the end
29
of this phase the evaporator is vented directly to the atmosphere.
Very few synthetic fiber plants use any air pollution control devices
to abate process emissions. One nylon plane has just begun to abate emissions
fron the evaporator and uses catalytic oxidizers. Heat requirements of the
units are not by direct flame but by indirect heating with the process heat
fluid Owthent.
16
JV-73
-------
GAS FLOW BATE,
Based on observations of the evaporator operation, it is estimated that
about 200 scf of exhaust gas is emitted in 5 seconds. The complete cycle on
the evaporator is about 2 hours.
GAS VELOCITY
Exit velocity, based on observations of the operation, indicate inter-
mittent (every 2 hours) velocities of about 200 fps. No data were available.
GAS TEMPERATURE
Stack gas temperatures are estimated to be 500 F although no data were
available.
STACK HEIGHT
Stacks from the evaporators are 6" diameter pipe extending through the
roof of the plant about 4 feet. Every evaporator will have a stack. When no
other information is available, a stack height of 75 feet should be used.
nr-74
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-------
CHAPTER IV-15
SYNTHETIC RUBBER PLANT B
The manufacture of synthetic rubber is carried out by many processes with
each rubber class having various ratios of raw materials utilized. Some of the
commercial monomers, the intermediate material for synthetic rubber production,
are listed in Table IV-15.1. Each of the monomers requires extremely different
feed ratios from a variety of raw ingredients like butane, ethylene, propylene,
acetylene, benzene, carbon black, sulfuric acid and oil. Tires for example may
have 5 different synthetic rubbers used in the same tire; casing rubber, inner
wall of the tubeless tire, ply build-up rubber and tread rubber. Each of these
synthetic rubbers originates from different processes and sometimes different
plants.
Synthetic rubber plants are scattered throughout the country and have a
total production rate of 2.2 million long tons/year. Most plants operate 24
hours per day and 7 days tt week like other chemical process industries. In
general, the prc:ess is entirely closed with just a few points for venting off
gases. Data from three New Jersey plants, all producing the same kind of tire
rubber, indicated that the polymerization process had the greatest exhaust flow
rates. Pollutants of importance are hydrocarbons and particulates. Controls
for hydrocarbon ?re incinerators; controls for particulates from mixing and
ball ini-lls are scrubbers. The extent of v;se of controls in the industry is
unknown.
GAS FLOW RATE
The exhaust flow rates from 3 plants are shown in Table IV-15.2 and may be
considered typical for one kind of tire rubber. Ihe exhaust flow rates averaged
about 1,800 sc&n for a 5,600 Ib./batch polymerization unit. Fluidiiing poly-
vinyl chloride powder in 200,000 Ib. batches also gave rise to 1,600 scfm. The
vent on a polyvinyl chloride holding tank was exhausting at 2,850 scfm.
GAS TEMPERATURE
Gas temperatures from the three plants shoved temperatures of 60 - 100 F.
The data from the three plants is not all inclusive since it represents only a
few plants and processes of the synthetic rubber spectrum. However, discussion!
with knowledgeable industrial representatives and stack testing at other
TV-76
polymerization plants suggests that most exhaust stack gases will be near
ambient unless afterburners are in use. Unless data are otherwise available
100°F should be used in calculations.
GAS VELOCITY
Gas velocity ranged fro? 30 to 53 fps for the various rubber making
processes. Fifty feet per second would seem a reasonable average.
STACK HEIGHT
Most of the stacks are located on the roof of the manufacturing building.
One plant had stack heights (ground to top of stacks) of about 75 - 80 feet
with stack diameters of 5 - 9 inches.
IV-77
-------
TABLE IV-15.1
Monomers And Major Chemicals Used For
Manufacture Of Synthetic Rubber, 1970
Million Ib.
2,273
435
192
270
180
240
37
205
18
1,131
40
195
110
47
2,100
69
76
60
TABLE IV-15.2
Exhaust Gases From Synthetic Rubber Plants
17
Process
Fluidizing polyvinyl
chloride powder
Fluidizing polyvinyl
chloride powder
Fluidizing polyvinyl
chloride powder
Fluidizing polyvinyl
chloride powder
Polymerization of
vinyl chloride
Venting PVC vessel
Production
Capacity
(Ib. /batch)
200,000
200,000
200,000
:oo,ooo
5,600
..
Exhaust
Flow
scfm
1600
1600
1600
1600
1800
2850
Stack
Velocity
fps
50
53
53
53
47
30
Stack
Temperature
(6F)
100
100
100
100
75
60
W-78
IV-79
-------
CHAPTER IV REFERENCES
1. Axelrod, L-, and T.E. O'Hare, "Production of Synthetic Aranonia",
Fertilizer Nitrogen - Its Chemistry and Technology, Reinhold
Publishing Co., New York, N.Y., 1964,
2. Sweeney, Neal, "Here's What Users Pay for Ammonia", Hydrocarbon
Processing. Vol. 47, No. 9, September 1968.
3. "Carbon Black", Preprint from the 1969 Bureau of Mines Minerals
Yearbook, U.S. Department of the Interior, Bureau of Mines, Washington
B.C., 1970.
4. Cox, J.T., "High Quality - High Yield Carbon Black", Chemical
Engineering, June 1950, pp. 116-117.
5. "Carbon Black", Journal of the Air Pollution Control Assn.. Vol.18,
No. 4, April 1968, pp. 216-228.
6. "Air Pollution Control for Missouri Charcoal Kilns", Prepared for the
Missouri Air Conservation Commission by Swrdrup and Pared and
Associates, Inc., St. Louis, Missouri, February 1971.
7. Fryling, Glenn R., Combustion Engineering. Conbusting Engineering Inc.,
New York, X.Y., 1967.
8. Private communication industry official, April 1971.
9. "Uorth American Chlor-Alkali Industry Plants and Production Data Book",
Chlorine Institute, Inc., Pamphlet No. 10, Nev York, K.Y., January 1971.
10. "Atmospheric Emissions from Chlor-Alkali Manufacture", Environmental
Protection Agency, Air Pollution Control Office Publication No.
AP-80, Research Triangle Park, North Carolina, January 1971.
11. Rodgers, W.R., and K. Muller, "Hydrofluoric Acid Manufacture",
Chemical Engineering Progress. Vol. 59, So. 5, Hay 1963, pp. 85-88.
12. Muller, Kurt, Private communication, August 1971.
13. "Atmospheric Emissions from Nitric Acid Manufacturing Processes",
U.S. Department of Health, Education, and Welfare, Public Health
Service Publication No. 999-AP-27, Cincinnati, Ohio, 1966.
14. "Nitric Acid Manufacture", Journal of the Air Pollution Control Assn..
Vol. 14, No. 3, March 1964, pp. 91-93.
15. Stenburg, R.L., "Atmospheric Emissions from Paint and Varnish Operations
Parts 1 and II", Paint and Varnish Production. September/October 1959,
pp. 61-65/111-114.
16. Shreve, R. Norris, Cheajcal Process Industrie*. HcGtav Hill Publishing
Co., New York, N.Y., 1967. ' ~
IV-80
17. State Air Pollution Permit Data, June 1971,
18. "Air Pollution Engineering Manual", U.S. Dept. of Health, Education,
and Welfare, Public Health Service, Publication No. 999-AP-40, 1967.
19. "Atmospheric Emissions from Wet-Process Phospheric Acid Manufacture",
U.S. Dept. of Health, Education, and Welfare, National Air Pollution
Control Administration Publication No. AP-57, Raleigh, North Carolina,
April 1970.
20. "Atmospheric Emissions from Thermal-Process Phosphoric Acid Manufacture",
U.S. Dept. of Health, Education, and Welfare, National Air Pollution
Control Administration Publication No. AP-48, Durham, North Carolina,
October, 1968.
21, Favcett, R.L., "Air Pollution Potential of Fhthalic Anhydride Manufacture"
Journal of the Air Pollution Control Association, Vol. 20, No. 7,
July 1970, pp. 461-465.
22. Bolduc, M.J., R.K. Seras, and G.L. Brewer, "Test procedures for Eval-
uation of Industrial Fume Converters", Air Engineering, February 1966,
pp. 20-23.
23. Parker, C.H., "Plastics and Air Pollution", Society of Plastics
Engineers Journal, December 1967, pp. 26-30.
24. Private communications with industry official, August 1971.
25. Fhelps, A.H., "Air Pollution Aspects of Soap and Detergent Manufacture",
Journal of the Air Pollution Control Assn., Vol. 17, No. 8, August 1967,
pp. 505-50;.
26. Molos, J.E., "Control of Odors from a Continuous Soap Making Process1',
Journal of the Air Pollution Control Assn., Vol. 11, So. 1, January 1961.
27. "Atmospheric Emissions from Sulfuric Acid Manufacturing Processes",
U.S. Dept. of Health, Education, and Welfare, Public Health Service
Publication No. 999-AP-13, Cincinnati, Ohio, 1965.
28. "Sulfuric Acid Manufacture, Report So. 2", Journal of the Air follution
Control Association, Vol. 13, No. 10, October 1963, pp. 499-502.
29. Unpublished data, Zurn Environmental Engineers.
IV-81
-------
CHAPTER V-l
AUALFA DEHYDRATING PLANT C
The Nation's dehydrated alfalfa is produced primarily in the middle-west
2
with Nebraska and Kansas accounting for 50 percent of total production. A
typical dehydrating unix. requires the yield from 1,000 acres of alfalfa for
economic operation. Operation is restricted to the growing season, approxi-
mately May through October depending on latitude. A typical plant will pro-
duce 2,000 to 5,000 Ib./hr. of alfalfa meal and vitl operate 24 hours per day,
7 days per week during the season.
The alfalfa is finely chopped and fed into a gas- or oil-fired horizontal
rotary drum where the moisture in the alfalfa is reduced to about 8 percent,
The hot moist combustion gases and the dried alfalfa then are separated by a
primary cooling cyclone. Sometimes a secondary cooling cyclone will be used
to further cool the dried alfalfa before discharging the raw material to a
lanmermill for grinding.
The alfalfa neal is conveyed by air to a cyclone; the neal goes to
storage, and the air goes to the atmosphere. Auxiliary processes include
pelletizing and pellet regrinding. Pollutants are limited to fine alfalfa
particles. Baghouses are occasionally used on the effluents from processes
ether than the primary cyclone.
GAS FLOW RATE
Exhaust gases from the primary cooling cyclone are the greatest in
volume of all sources in an alfalfa dehydrating plant. These are also the
r.ost difficult to control because of high moisture content. Gas flow rate
iron the primary cooling cyclone (the rotary dryerl was 15,320 scfm for a
3,000 Ib./hr. alfalfa meal production rate and 8,090 scfm for a 2,100 Ib./hr.
production rate. Based on these two plants, one could estimate 4,500 scfm of
exhaust gases per 1,000 Ib./hr. of product produced. Secondary cooling
cyclones for the two plants exhausted only about 600 scfm per 1,000 Ib./hr.
of production rate, and the hammermill exhaust (air/meal separator) averaged
about 1,700 scfm per 1,000 Ib./hr. Considering these three unit operations
as one basic process, the total exhaust flow would be 6,800 scfm per 1,000
Ib./hr. meal production rate (Figure V-l.l). processes such as pelletizing average
V-l
-------
about 900 scfm per 1,000 Ib./hr. of pellets produced, and one plant which
reground pellets (14,000 Ib./hr.) produced only 1,000 scfm total.
GAS TEMPERATURE
The gas temperature of the drier exhaust as it exits from the primary
cooling cyclone will be about 340°F, from the secondary cooling cyclone
about 130°F and from the air/meal separator about 100°F. Auxiliary
palletizing or grinding processes can be expected to exhaust at about 120 F.
GAS VELOCITY
Gas velocity from cyclones is generally low to prevent re-entrainment
of solids. For light dusts, 10 fps or less is often used. For the two
plants which provided stack diameters,velocities ranged from 3 to 14 fps
with both primary cooling cyclones running 10 fps. Stack diameters varied
from 25 to 44 inches.
STACK HEIGHT
Stack heights for the two plants which provided data showed a range of
20 to 39 feet. One plant exhausted a portion of the effluent up an 85 foot
stack, but this probably is unconmon. Thirty feet would seem more typical
for dispersion work and calculations.
V-2
20-
12345
Production Rate (1,000 Ib./hr.)
Fioure V-1.1 Exhaust flow rates from alfalfa meal production
V-3
-------
CHAPTER V-2
COFFEE ROASTING PLANT8
Coffee beans, primarily from Central and South America, are roasted
in most major cities throughout the United States. The industry processes
coffee beans throughout the year, but individual plants may operate certain
equipment only a few hours per day depending on market demand.
Coffee beans are cleaned of dust and chaff, roasted, cooled and destoned,
A
ground, and packaged. (Figure V-2.1) A small percent, 307., will later be
processed into instant coffee and an even smaller percent, 57a, will
have been decaffeinated with trichlorethylene prior to roasting.
Principal air contaminants are dust and chaff from cleaning, cooling
and destoning operations. These contaminants, although small in concen-
tration, are generally collected with cyclones. From the roaster smoke,
odor, steam, and larger quantities of particulates are generated. The
comnon control procedure is to use a cyclone to trap course particulates
followed by an afterburner to oxidize the odorous hydrocarbons, fine
particles, and visible blue scoke. Several plants in New Jersey use wet
scrubbers to abate roaster emissions.
Solvent loss (trichlorethylene) is the additional emission discharged in
the production of decaffeinated coffee; no controls are utilized. For in-
stant coffee production, the roasted beans are ground and extracted with
water (300 F, 10 to 12 atoospheresi, and the solution is filtered to remove
4
the spent solids. The filtrate is spray dried. The instant coffee is
removed with cool dry air at the bottoo of the tower, and ttie hot, moist drier
gases are exhausted to a scrubber.
GAS FLOW RATE
Roasting is the most important step in coffee making; it is also
the most productive of air contaminants. Most roasters are gas-fired
and recirculate exhaust gases; about 370 BTU of heat energy is required
per pound of coffee. Batch type roasters without recirculation handle
about 500 pounds of beans per batch (1,500 Ibs./hr.) and discharge
exhaust gases at about 1,000 scfm. If exhaust gas recirculation is employed
the exhaust gas discharge will be reduced about 40 percent. On & common
unit basis of 1000 Ibs./hr. of beans processed, batch roasters wituout
V-4
recirculation would discharge 660 scfm; with recirculation, 400 scfm per
1,000 Ibs./hr. processed, likewise, a 10,000 Ib./hr. continuous roaster,
with a recirculation system, exhausts about 4,000 scfm or 400 scfm per
1,000 Ib./hr. processed (Table V-2.1).
Continuous type stoners exhaust about 40 scf per pound of finished
coffee, while batch type stoners vary between SO and 200 scf per pound
of coffee. The operation of stoners requires a constant gas velocity so
air volume would vary with plant capacity but probably not with production
rate (percent of capacity).
Continuous type coolers exhaust approximateLy 120 scf per pound of
finished coffee. Batch coolers generally use about 200 scf per pound.
Cooler air flow would probably not vary much with production rate (percent
of capacity) as was the case with stoners.
Effluent from a 2,000 Ib./hr. instant coffee spray drier would be
about 8,000 scfm. The stack gas flow rates for roasters, coolers, and
stoners are shown in Figures V-2.2, V-2.3 and V-2.4 respectively.
'AS TEMPERATURE
Recirculation type roasters typically exhaust to the cyclones at
1,000°F. There should not be more than 100-200°? of tecperature loss
by the gases before they exit the stack at about 800 F. Units with
afterburners will have outlet temperatures to the stack of about 1,200°F.
Temperatures of cooler off gases are not well documented, but the
beans are discharged from the quenching step at an estimated 250 to 300°F,
and the cooler exhaust gases would be somewhat less than this, possibly
150 to 200 F. The temperature would decrease to ambient in batch coolers.
Stoner exhaust gases are at approximately ar.bient temperature, because
this is essentially an airveying step. The tenperat-re of the effluent from
the spray drier for making instant coffee ranges from -00 Co 400 F,
GAS VELOCITY
No data were available on stack diameters or exit velocities. Induced
draft fans are used for draft control of coffee roasting operations.
Recommended design velocities for ducts and stacks with fan-powered draft
are about 25 fps for economical operation. Assume 20 fps.
V-5
-------
STACK_ljEIGgr
No dapa were available. However, one plant which was tested had
stacks about 5 feet higher than the roof which topped a 3-story facility.
Total height for the roaster and cooling stacks would therefore be 35 feet.
The drier for instant coffee may be 20 feet in diameter and up to 80 feet
high. Therefore, assume a stack height of 100 feet for it.
7-6
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8
Continuous ard batch
with reclrcutation
10
2468
Production Rate (1,000 Ib./hr.)
Figure V-2.2 Exhaust flow rates for coffee roasters
V-9
-------
30 .
_" 20 •
10
Rated Cauai.it.- (','T. l!-.,'hr.)
Figure V-2.3 Exhaust flow rates for coffee coolers
V-19
15 -
2 4 6 8 10
Rated Capacity (1,000 Ih./hr.)
Figure V-2.4 Exhaust flow rates for coffee stoners
v-il
-------
CHAPTER V-3
COTTON GINNING PROCESS C
Cotton is grown in 15 or 20 of the southern states from California to
Florida with Texas accounting for about 25 percent of the Nation's total
production. The cotton is picked primarily by machine and delivered to a
local gin for processing. At the present time, there are close to 5,000
cotton gins in the U. S. Each operates only from 4-8 weeks out of the year
when the cotton is harvested (usually between June and October). During the
harvest owners try to operate the gin 7 days per week and 24 hours per day.
A survey of Texas gins in 1965 showed that the average gin handled
3,233 bales per year and that the break even point for a marginal gin was
2,108 bales per year. Arizona and California, which are considered high-
yield cotton growing areas, had average ginning rates of 5,300 and 6,000
bales per year, respectively. A typical cotton gin will have the capacity
to process and produce about 12-15 bales of cleaned cotton per hour.
Ginning cotton consists essentially of cleaning the cotton and separating
cotton lint and seeds from the trash. The lint is compacted into 500 Ib. bales
for shipping to textile mills, and the seed is shipped to oil mills.
The amount of trash which must be removed from the cotton depends to a
great extent on the way the cotton is harvested. In 1966, T8 percent of the
cotton crop was harvested by machine, 58 percent with pickers and 19 percent
with strippers. One percent was machine scrapped. Of the remaining 22 percent
of the crop, 16 percent is hand- picked and 6 percent hand- snapped.' The trash
consists of hulls, sticks, stems, leaves, and dirt (Table V-3.1)•
The principal emission from the gins consists of dust and cotton lint.
Control equipment is generally small diameter cyclones which are used for air-
conveying and air separation operations. A secondary source of air pollution at
many gins is the jug (tepee) type incinerator which may be used to burn cotton
gin trash.
GAS FLOW RATE
Exhaust volumes from cotton gins are quite high, because air-conveying
and air-separationare used extensively. Table V-3.2 shows typical gas
volumes for the components of a cotton gin. Note that not all gins have a
second drying operation. The volumes are given in acfm,but ordinary ex-
V-12
haust temperatures differ little from ambient temperatures so that correction
to scfni is unnecessary. In spite of the heat-input from the burner on the
drier(s), the very large amounts of air from other operations and system
leaks lower the temperature considerably.
It is comnon practice to place all but one of the cyclones in a battery
beside the gin building so that all can discharge to a conmon conveyor.
Collected trash is in turn blown into a bur house or incinerator. The lint
cleaner trash fan effluent is preferable for such use since fine lint tends
to clog the conveyor.
Assuming the gas flow rates of Table V-3.2 are appropriate for an
average gin, then the design exhaust flow vs. capacity would be 43,500
scfm for processing 12 bales per hour or about 3,000 scfm per bale/hr.
GAS TEMPERATURE
With the exception of the drying system, all operations in the cotton
gin are conducted at ambient temperature. Dryer temperature is set to
maintain 6.5 to 8 percent noisture in the dry cotton fibers and it, there-
fore, varies depending or. the moisture content of the raw cotton. However,
cellulose, the principal component of cotton, shows marked decomposition at
284°F or higher.* Because of this, temperatures out of the dryers are
not expected to exceed 200°F. For dispersion calculations total exhaust
temperatures of 100°F should be assumed.
GAS VELOCITY
To prevent re-entrainment of particulate matter collected in the
cyclones, the cyclone stack velocity should not exceed 8.3 t.-> 10 fps
according to the V. S. Cotton Ginning Research Laboratory. This
suggests that a design gas flow rate of about 10 fps would probably
be maintained, even when ginning at reduced load, (to retain particle
removal efficiency).
STACK HEIGHT
No data were available on stack height. However, since the cyclones
are located beside the gin building (most operations are at ground level)
a total stack height of 30 feet is probably equal to 01 higher than most
cotton gin stacks.
V-13
-------
TABLE V-3.1
Average Amount and Type of Trash In
Seed Cotton Harvested By Various Methods (Ib./bale)
Hulls
Sticks and stems
Leaf and dirt
Total
29
9
43
81
397
50
78
5:5
329
143
398
670
v-u
TABLE V-3.2
Air Volumes Utilized In Various Seed Cotton
Trash-Handling Systems (Based on 12 to 15 bales/hr.)'
System
Trailer unloading
No, 1 drying and cleaning system
No. 2 drying and cleaning system
Live overflow
Trash fan
Lint cleaner trash fan
Total (1 dryer)
Total {,2 dryers'!
Air Volume
(scfm)
8,500
9,000
9,000
4,000
3,000
10.000
34,500
43,500
V-15
-------
CHAPTER V-4
FEED AND GRAIN MILLS
The Nation's supply of feed and grain for both human and livestock
consumption is grown throughout the U. S. but is centered in various belts.
Corn is the roost important agricultural crop in the U, S. The corn belt is
centered in the Mississippi River Valley, Iowa and Illinois primarily.
Wheat, which constitutes the second most important food crop in the U. S., is
grown primarily in the west central states from North Dakota to the Texas
panhandle. Other domestic grains include oats, barley, flax and rye, each
of which is grown in those areas where climate and soil conditions are most
favorable. The largest concentrations of feed and grain mills (elevators)
are found in such cities as Chicago, Minneapolis and Duluth, but there are
literally thousands of feed and grain mills located throughout the U. S.
Because of the different grains handled, the type of dust emission will
vary somewhat. Corn cleaning or processing will discharge small particles
of cob fiber called "bees wings"f wheat processing vill release "chaff", etc.
Dust emissions are the sole contaminant free feed and grain mills. This
dust is generated by feed manufacturing processes as well as unloading,
conveying, and storing the feed and grain. Manufacturing processes include
cleaning, grinding, rolling, pelletizing, regrinding, and blending.
Pelletizing and regrinding of alfalfa meal are discussed in Chapter V-l,
Alfalfa Dehydrating Plants, and the results in that section should be some-
what applicable to other feeds as well. Dust laden air from grinders, rollers,
hammer mills and cleaners is usually cleaned by a cyclone. At times, filter
baghouses may be used to further purify the cyclone exhuast. See Figure V-4.1.
A model grain elevator chosen to represent a typical operation of a
flour or animal feed operation processes 12,600 Ib./hr. of material and is
operated 6800 hr./yr. This is equivalent to operating 24 hr./day for
between 5 and 6 days per week during "the year. Small elevators generally
operate 24 hr./per day, 7-days a week only during the harvest season and
revert to 8 hr./day operations the rest of the year.
GAS FLOW RATE
Unloading of grains is usually done in one of three ways: (a) the
V-16
choked-feed method (which produces little or no dust or exhaust flew),
(b) deep receiver dumping, or (c) pneumatic conveying. Emissions from
deep receiver dumping are sometijnes controlled by an exhaust hood, and
the air used in the pneumatic conveyer is commonly cleaned by use of a
3
cyclone separator.
An exhaust hood proposed for one deep receiver unloading area ex-
n
hausted 12,000 scfo of air from a 600,000 Ib./hr. grain dumping operation.
Recocnended transport velocities for common grains conveyed pneu-
-aticslly are in the range 4000 to 7000 fpm. With the commonly used
5-in. duct, this would be an air flow range of 545 to 9b3 scfm. Typically,
a valje of about 750 scfm could be used.
Table V-4.1 and Figure V-4.1 show exhaust gas volume flow rates for
irain cleaners and a hammer mill versus grain throughput capacity. Air
r'low in these operations would be set by equipment design capacity rathei
tnan operating rate. In general, the flows range from 50 - 5000 scfm per
1000 Ib./hr. of grain processed in each operation.
OAS TEJ-gERAIURE
All equipment ir. feed and grain mills usually exhausts at or very near
,ir:rient tenperature; therefore, 70 F should be used where actua.1 conditions
are unknown.
.-x; y; LOT IT Y
C\clones are coranonly used for dust removal in feed and grain rills. To
vrexent re-entrainment of dust, the exhaust velocity of these units is typically
r.o nore than 8.0 to 10.0 fps . No actual operating data were available.
STAC.< HEIGHT
Grair elevators utilize tall silos for storage of grain and feeds. As
a result, cyclones used for conveying the products are also located at high
elevations. So data were available, but 150 feet is probably typical.
V-17
-------
TABLE V-4.1
Exhaust Gases from Feed and Grain Mills^
Operation
Cleaning
Cleaning
Cleaning
Milling
(Hammennill)
Grain
Malted Barley
Malted Barley
Milo
Feed Barley-
Process Weigh!
ib./hr.
53,000
50,000
11,250
in, 350
Exhaust Volume
scfm
2,970
2,970
6,290
3,790
V-18
6t-A
-------
30 .
25 •
20
o
r is
10
-0 23 " iC 50
Capacity ('100 If.'nr.)
Fioure V-4.2 Exhaust volumes for orain cleanino and minim operations.
V-20
CHAPTER V- 5
FISH I«AL PROCESSING °
Fish canneries generally are located near the U. S. coasts or other
large bodies of water. Fish scraps from the canning lines, including any
rejected whole fish, are taken to by-product planes located nearby and pro-
cessed into fish meal. Fish oil and fish solubles are of lesser economic
importance as by-products. The fish meal subsequently is used for fertilizer
or animal food.
The chief processes in the manufacture of fish meal are: (a) cooking
solid fish wastes at 2 to 5 psig with live steam, (b) pressing the cooked
waste to remove liquids, (c) grinding the press-cake, (d) drying the coarse
solids in a rotary drier, and (e) regrinding the dried fish meal before
conveying it to storage.-'
Emission points for air contaminants include each of the processes,
the cooker exhaust, the presses and grinders, the rotary drier exhaust, and
exit gases from the air-conveying system used for transporting the finished
meal. Cooker off gases usually are passed through a contact condenser for
removal of water vapor and oils before exiting to the atmosphere. Emissions,
primarily odors, are generated by the presses and grinders, but such operations may
or may not be controlled. Tremendous volumes of steam plus small quantities oi.'
fish meal and significant amounts of odors are discharged from the
rotary drier. Emissions iron the conveyers are chiefly fish meal
dusts which are removed effectively by cyclone separators.
Operating times for fish meal plants obviously depend on the seasonal
availability of raw materials, and the availability varies greatly. However,
one such operation was found to operate for two 8-hour shifts per day and 5
days per week.
GAS FLOW RATE
The largest contaminated gas stream is exhausted from fish meal driers.
Volume emission rates are greater by 70% from direct-fired units as compared to
steam-tube driers (Table V-5.1). Also, the exhaust is cooler and the moisture
content of the gases is greater from the steam-tube drier. From the one set of
available test data, the dry exhaust gases from a steam-tube drier can be
expected to total 500 scfm per 1,000 Ib./hr. of feed to the drier (Figure V-5.1).
With a 5 ton/hr. input the direct-fired unit would discharge 10,000 scfm
¥-21
-------
dry and produce 2.5 tons/hr. of dried meal.
Fish meal pneumatic conveyor systems are designed to provide 45-70
cubic feet of air per pound of meal conveyed. Thus, for a 5 ton/Hr. con-
veyor the exhaust would be about 10,000 scfm.
Total from the plant will be about 2,000 or 3,000 scfm per 1000 Ib./hr.
dried fish meal processed and handled by the steam-tube and direct-fired
drier plant, respectively.
From the cooker, the pop-off gases (mostly steam),-total from 100-1000
scfm depending on design. These gases are invariably exhausted to a con-
denser where steam and all other condensables are removed. Non-condensable
gases seldom exhaust more than 50 scfm and are ignored in this report.
GAS TEMPERATURE
The temperature of the exit gases from the driers will be about 200°F,
while that from the conveyor will be near ambient 65°. The average axhaust
gas temperature, therefore, will be about 150°F,
GAS VELOCm
The use of cyclones on both the drier exhaust and the conveying system
suggests that the exit velocity would be on the order of 10 fps. No data
were available.
STACK HEIGHT
No data were available; however, stack height is expected to be on the
order of 30 feet from observations at one similar plant.
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V-22
-------
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Dried Fish Meal "reduced or Handled (1000 Ib./hr.)
Fiaure V-5.1 Exhaust volumes for fish mea! operations
V-24
CHAPTER V-6
FERMENTATION PROCESSES D
Fermentation process industries are similar to the chemical process
industries with the exception that the emphasis is on the reaction created
by microorganisms instead of chemicals. Fermentation processes include the
manufacture of beer, wine and liquors, the manufacture of yeast, and the
production of pharmaceutical drugs like penicillin. It is imperative that
the fermenter (main reaction chamber) be immaculate to prevent bacterical
contamination. Fermentation processes are entirely closed with the major
emission point being small vent lines which operate intermittently and at
very low flow rates.16 The fermenters determine plant capacity and have
typical sizes which range from 50,000 to 100,000 gallons.
The major air pollutants from fermentation processes are odorous gases
which originate from the fermentor where controlled volumes of air are passed
over the media and microorganism bed. Plants operate 24 hours a day and 7
days a week. No information was available, but control equipment would Hkely
be limited to filters on ventilation air which are changed and burned daily
and afterburners on some vent lines.
GAS FLOH RATE
Gas flow rate from these plants is very low and will be less than
1 scfm for a 50,000 gallon fermenter. If a plant had 20 termenters running
continuously, the total exit flow rate would only be 20 scfm.
GAS....TEMPERATURE
The gas exit temperature for these plants is ambient for all practical
purposes since the temperature in the fermenter is usually about 85 F.
GAS VELOCITY
One process has a gas velocity from the fermentor which ranges from
1 to 4 fpm.16 Since gas velocity from these plants is so small.no plume
rise can be expected.
V-2S
-------
STACK HEIGHT
Plants will not normally have a stack for the fermenter gases but will
usually have roof top vent pipes 4 to 6 inches in diameter. The stack
height will be the height of the plant building. Most breweries have a
plant height of about 80 ft., while pharmaceutical plants have a height
of about 35 feet. For calculations assurae 50 feet.
V-26
CHAPTER V-7
MEAT SMOKEHOUSES0
The technique of smoking to preserve meat and fish products has been
used for centuries. It was originally developed as a method for preserving
food products, but curing and storage processes have improved to the point
where smoking is now used only to impart flavor and color to the food
products.
The two most common types of smokehouses are: (a) atmospheric smoke-
houses, and (b) recirculating smokehouses which are operated intermittently
anywhere from 1 hr./day to 24 hr./day. The major air contaminant from meat
smokehouses is smoke, fine particulates which are rarely controlled. The
older atmospheric type is a boxlike structure heated directly by natural gas
or wot?d, equipped with a natural draft circulation system. Newer smokehouses
are usually of the recirculating type in which smoke is circulated at fairly
high velocities over the curing products; sir.oke is piped to the house from
generators outside. These operations would be few in number and would be
associated with meat packing or fish processing plants.
GAS FLOW RATE
Exhaust flow rates from smokehouses are related to the floor area of
the units rather than the weight of product being cured. Typically, this
is about 2.5 scfm per sq. ft. for atmospheric smokehouses. Exhaust flows
of recirculation smokehouses are 1 to 4 scfjn per sq. ft. during smoking
and cooking, and 4 to 9 scfm per sq. ft. during the drying cycle. For
multiple-story units, total floor area can be used to obtain a rough
estimate of exhaust flow rates.
GAS TEMPERATURE
Exhaust temperatures for atmospheric smokehouses vary from 120 to
150°F. Because the temperature requirement within the unit is the same
for recirculating smokehouses, the exhaust temperature would be in the same
o
range. For calculations assume ISO F.
V-27
-------
GAS VELOCITY
No data were available for meat smokehouse gas flow emissions or gas
velocity. However, other food process categories have low flow rates and
low exit velocities. For dispersion calculations 5 fps is recommended.
STACK HEIGHT
No specific stack data were available. Since smokehouses are commonly
found around meat packing plants, the expected stack height would be 20 to
50 feet. Assume 30 ft. for calculations.
CHAPTER V-8
STARCH MANUFACTURING PLANT0
In 1964, 977. of the 5.8 billion Ib. of starch produced in the United
States was cornstarch. The only significant air pollutant emission point
of a cornstarch plant is exhaust from the drying operation. The dryer is
usually a natural gas direct-fired flash unit or a continuous-tunnel counter-
current type. The emitted pollutant is cornstarch particles. It is common
to find cyclones used but mainly to entrain dust from transport conveying
systems. Large plants of this type typically operate 6 to 7 days per week,
22 hours per day.
GAS FLOW RATE
One large starch manufacturing plant (18,200 Ib./hr.) had an exhaust
flow of 35,000 scfm prior to installation of a gas scrubbing system. After
installation of an effective scrubber, the exhaust flow decreased to 32,000 scfro.
Since no other data were available, use 2 scfn per Ib./hr. of cornstarch pro-
cessed as the exhaust flow rate.
13
GAS TEMPERATURE
Exhaust temperature for the one installation was 140 F.
GAS VELOCITY
The gas exit velocity prior to scrubber installation was 97 fps fron a
36 in. i.d. stack. With the scrubber, velocity dropped to 89 fps in the same
duct. These are very high velocities, but they might have been necessary to
maintain the efficiency of twin cyclone separators which were located ahead
of the scrubber in this particular system. For calculations 60 fps is
recommended.
STACK HEIGHT
No specific data was available for stack height. For modeling purposes
use 75 feet.
V-28
V-29
-------
CHAPTER V REFERENCES
1. "Process Flow Sheets and Air Pollution Controls", American Conference
of Governmental Industrial Hygienists, Cincinnati, Ohio, 1961.
2. "Air Pollution from Alfalfa Dehydrating Mills", Technical Report No.
A60-4, Robert A. Taft Sanitary Engineering Center, Public Health
Service, U.S. Department of Health, Education, and Welfare, Cincinnati,
Ohio, 1960.
3. Danielson, J.A., "Air Pollution Engineering Manual", Air Pollution
Control District, County of Los Angeles, National Center for Air
Pollution Control, U.S. Department of Health, Education, and Welfare,
Publication No. 999-AP-40, 1967.
i. Partee, Frank, "Air Pollution in the Coffee Roasting Industry", Public
Health Service, U.S. Department of Health, Education, and Welfare,
Publication No. 999-AP-9, September, 1964.
5. Duprey, R.L., "Compilation of Air Pollutant Emission Factors", Public
Health Service, l.S. Department of Health, Education, and Welfare,
"ublication So. 999-AP-42, 1968.
6. Jorgenson, R., Fan Engineering, Buffalo Forge Cor.pany, Buffalo, X.Y.,
6th ed., 1961.
7. "Control and Disposal of Cotton-Ginnir.g "..'astes", Public Health Service,
U.S. Department of Health, Education, ar.d Welfare, publication No. AP-31,
1967.
8. Frank, Herman F., Encyclopedia of Polycer Science, Volumes 3 and 4,
Interscience Publishers, Tew York, N.V., 1965.
9. Thimsen, D.J., and Aften, Paul V., "A Proposed Design for Grain Elevator
Dust Collection", J. Air Poll. Contr. Assoc^, Ijj (11), 738-742, 1968.
10. "National Emission Standards Study", A Report to the Congress of the
United States by the Secretary, Department of Health, Education, and
Welfare, Public Health Service, National Air Pollution Control
Administration, March 1970.
11. Shreve, R.H., Chenical Process Industries. 3rd ed., >!cGraw-Hill Book Co.,
New York, N.Y., 1967.
12. McGraw, M.C., "Compilation of Air Pollutant Scission Factors", Draft
copy, Air Pollution Control Office, Department of Health, Education and
Welfare, August, 1970.
13. Storch, H.L., "Product Losses Cut with a Centrifugal Gas Scrubber",
Chan. Eng. Prog., 62, (4), 51-4, 1966.
14. State Air Pollution Permit Data, June, 1971.
V-30
15. Private conversation with industry official, July 29, 1971.
16. Gaden. Elmer Jr., "Fermentation", Chenical Engineering -McGraw Hill
Publishing Co., New York, N.Y., April, 1956.
V-31
-------
CHAPTER VI-1
Aluminum use in the U. S. is rapidly growing; 1968 production of aluminum
totalled 3.4 million tons, an increase of 10 percent over 1967. There are 27
primary aluminum smelters in the United States with plant capacities ranging
from 80,000 to 275,000 tons per year, with an average plant capacity of
150,000 tons per year.
Bauxite, a hydrated oxide of aluminum, is the base ore for primary
aluminum production. It contains 30 - 70% Al-0- and lesser amounts of iron,
silicon, and titanium. Most ore is purified by the Bayer process. It is dried,
ground in ball mills and mixed with sodium hydroxide solution in an autoclave to
react with Al-0, to form sodium aluminate. Impurities are removed by settling and
filtration,and aluminum hydroxide is precipitated. The precipitate then is
calcined to produce pure alumina, Al.O..
Recovery of aluminum metal from the oxide is accomplished by the Hall-Heroult
electrolytic process. Alumina is dissolved in a fused mixture of fluoride salts
in carbon lined pots and dissociated electrically into metallic aluminum and
oxygen. Aluminum is drawn off at intervals and alumina is steadily fed onto the
top of the molten electrolyte.
Calcining of aluminum hydroxide to alucir.a generates dust which is generally
controlled by cyclones and precipitators.
Electrolytic reduction generates carbon particles and alumina dust (300 Ib./day)
and both particulate and gaseous fluorides (75 Ib./ton). Use of chlorine gas
for fluxing and degassing the molten metal generates aluminum chloride which
reacts with moist air to form aluminum oxide and hydrogen chloride. Controls
include precipitators, baghouses and high energy scrubbers. Primary aluminum
smelters operate continuously, 24 hours a day and 7 days a week.
GAS FLOW RATE
Typical exhaust flow rates for vertical cells range from 300 - 600
scfm/pot; for prebaked and horizontal cells the range is 1800 - 3500 scfWpot.
GAS TEMPERATURE
Cases leave the electrolytic pots at temperatures between 1700 - 1800 F
and are nixed with ventilation air prior to gas treatment. If these gases are
VI-1
-------
vented to the atmosphere or if dry air pollution control equipment is utilized,
exit gas temperatures will be about 30C°T.l This temperature is primarily a
result of the dilution air. A typical gas treatment system consists of dry
dust collectors to remove particulates, water spray scrubbers for removal of
gaseous fluorides and stacks for final dispersion of scrubbed gases. When
vater sprays are used, the temperature of the exit gases will be about 150 F.
GAS VELOCITY
No data were available.but exit velocities in the range of 25 to 50 fps
would be expected.
STACK HEIGHT
No data were available, but stack heights can range from 100 - 500 feet
depending upon the design criteria established for each plant site.
VI-2
CHAPTER VI-2
PRIMARY COPPER SMELTER A
Primary copper smelting is currently practiced in 16 plants within the
United States, all but two of which are west of the Mississippi River.
Arizona alone contains 8 of the 16 copper smelters. Primary copper smelters
are generally operated seven days a week, 24 hours per day, except for
occasional scheduled and unscheduled shutdowns. The capacity and operating
data for each of the 16 primary smelters in the United States are available,
but such detail was not appropriate for this report.
Copper is smelted from sulfide ores which account for 94 percent of the
copper mined domestically. Smelting is comprised of three pyrometallurgical
steps (Figure VI-2.1):
Roasting
Reverberatory furnace smelting to produce a
copper matte.
Conversion of the matte to blister copper.
Nearly half of the smelters roast a charge of mixed concentrate and
flux in a fluidized bed. Capacities vary from 700 - 1500 tons (dry weight)
of feed per day. Roasting is required when the feed material is low in
copper and high in iron and sulfur. Roasting is done at about 1200°F. The
reverbatory furnace operates at 2400°F with feed rates of 400 - 1100 tons/day
forming the matte and slag. Molten matte is transferred by ladles to the
cylindrical converters which have a capacity of about 135 tons/day of copper
from average matte. Generally, two converters are required for each rever-
beratory furnace.
Emissions from smelters consist of fumes (oxides of the metals being
smelted) and sulfur oxides. Control equipment at present is limited to
electrostatic precipitators (efficiencies 95-997.) for reducing particulates.
Five sulfuric acid units for recovery of SO. have been added in recent years,
and more are planned.
GAS FLOW RATE
As seen in Table VI-2.1 it is coonon for one stack to handle the exhaust
gases from more than one furnace. This situation is representative of 6 of'
the 16 currently operating smelting facilities. Because of this practice it
VI-3
-------
would be difficult to relate total stack gas flow rates directly with plant
capacity. Therefore, the volume of gases emitted directly from each type of
furnace is correlated with plant copper production capacity (Figure VI-2.2).
Also, since dilution air is used in all instances to cool these furnace gases,
Figure VI-2.3 estimates the quantity of dilution air required to provide
specific stack temperatures. The sum of this dilution atr and furnace
gases will then give the estijnated total stack gas flow rate as a function of
plant production capacity.
Volumetric flow rate of exhaust gases from each of the pyrometallurgical
smelting operations varies considerably with plant capacity. Examination of
the figure shows variations in both the quantity and scatter of the data.
However, data were only available for three (of the seven) plants having
roasting facilities. The reverbatory furnace gas flow rates showed some
wide scattering, with variations from the estimated least-squares line up
to ± 100%. The converters showed less scatter to the exhaust rates than the
reverbs , however, since several "blow cycles11 comprise the operation of con-
verters during a 24 hour day, the data in this figure represent daily average
values. Typical undiluted gas flow rates are: roaster - 16.000 scfm;
reverberatory - 50,000 scfm; converter - 16,000 scfm.
As stated earlier, dilution air is almost always used to cool the furnace
exhaust gases in copper smelters. Figure VI-2.3 presents the volumetric flow
rate of this dilution air per scfm of furnace gas versus final outlet or
stack temperature. The curves in this figure were developed from heat
balances utilizing reported values for furnace gas temperatures prior to
air dilution. The average temperature of gases from roasters is approximately
1200° whereas converter gas temperature average 2200°F. Gases from re-
verberatory furnaces almost always pass through waste heat boilers prior
to being diluted with air. The average temperature of the these gases after
leaving the waste heat boiler and just prior to air dilution is approximately
700°F.
In order to estimate the total volumetric flow rate of exhaust gases
from primary copper smelters, the following information must be known:
Plant copper production capacity in Ib /hr.
whether a roasting operation exists.
The percentage, if any, of the roaster and/or
converter furnace gases that are sent to an
associated acid plant
VI-4
Assume for the purposes of illustration a smelter with an estimated
daily copper production capacity of 200 tons (16,743 lb./hr.}. Assume the
facility has a roaster but does not have an associated sulfuric acid plant.
Using plant No. 3 (Table VI-2.1) as an example, one can estimate the
following flow rates of furnace gases from Figure VI-2.2:
Roaster:
Reverberatory:
Converter:
Sub Total
15,100 scfm
43,600 scfm
45.300 scfm
104,000 scfm
(3 x 15,100)
Using a stack temperature of 550°F, the following quantities of dilution
air can be obtained from Figure VI-2.3.
Roaster:
Reverberatory:
Converter:
Sub Total:
1.56 x 15,100 = 23,400 scfm
0.28 x 43,600 - 12,200 scfm
3.62 x 45,300 "164.000 scfm
199,600 scfm
Adding this value to the volume of furnace gases gives a total
volumetric flow rate of stack gases from this plant of 303,600 scfm. The
actual measured scfm from plant No. 3 was 371,000 scfm.
GAS TEMPERATURE
Roaster and/or converter gases in some smelters may be in part or
totally directed to sulfuric acid plants. Also, there may be a stack for
the roasting and/or reverberatory furnace exhausts and an additional stack
solely for converter exhausts. It is also very common to use a waste heat
boiler with the reverbatory furnace gases. Temperatures of the 3 furnace
gases prior to air dilution would be on the order of: roastet - 1200°F,
reverbatory - 700°F and converter - 2200°F. The representative exhaust gas
temperatures at these stacks are summarized for each of the 16 plants in
Table VI-2.1. The data were obtained from the recent systems study of emissions
from the nonferrous metals industry.2 Although there is some scattering
of the data presented in this table, 651 of the data (13 points) fall
within the range of 300 to 400°F and 907, of the data (16 points) fall
within 250 - 450°F. For dispersion calculations, 350°F should be used.
VI-5
-------
GAS VELOCITY
Stack gas velocities vary from plant to plant, but no data were
found. Unless specific parameters are known, a velocity of 35 feet per
second should be assumed.
STACK HEIGHT
It is common for one stack to handle the combined exhaust gases from
more than one furnace, with stack heights usually in the range from 200
to 500 feet. This height would vary from plant to plant and unless an
accurate, estimate of height is available from the installation under
investigation, an estimate of 300 feet should be used for this parameter.
VI-6
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75 •
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Reverberatory ®
Roaster or Converter O
Reverberatory
R=.577
Exhaust Flow = 1.4lxProd. Cap.+20.
(1,000 scfm) (1,000 Ib./hr.)
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(1,000 scfm) (1,000 Ib./hr.)
0
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50
20 30 40
Production Capacity (1,000 Ib./hr.)
Figure VI-2.2 Exhaust flow rate of qases from copper smelter furnaces
vs. production capacity.
VI-10
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- 5 -
400
600
300
1000
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Fioure VI-2.3 Volumetric flow rate of dilution air per scfm of
furnace aas vs. stack temperature.
VI-11
-------
CHAPTER VI-3
IRON AND STEEL MILL A
Because of the complexity of an integrated steel mill, no attempt will
be made to describe in detail the numerous process steps comprising the total
facilities. However, each of the major iron or steeimaking stages will be
considered individually in relation to the characteristics of the off gases
exhausted into the atmosphere. The discussion will include sintering plants,
blast furnaces, open hearth furnaces, basic oxygen furnaces, and electric
furnaces. Exhaust gases from the manufacture of coke are discussed in a
subsequent chapter.
Annual production of. raw steel in the United States totals over 125
million tons. Major steel complexes are located around the Great Lakes with
Pennsylvania, Ohio, Indiana, and Illinois accounting for over one-half of
the Nation's steel production. Steel is produced in open hearth furnaces -
56 percent, basic oxygen furnaces - 34 percent, and electric arc furnaces -
10 percent.
Iron and steel mills are operated 7 days per week, 24 hours per day.
Emissions are primarily iron oxide fumes. Control equipment includes cyclones,
baghouses, pxecipitators, and scrubbers.
VI-12
"Sintering Plant"
Originally, sintering was used as a means of recovering fines (flue dust)
produced during the making of pig iron in blast furnaces. However, it is now
recognized that low cost ore when combined with flux and sintered, can be
converted into a useful and economical burden material for blast furnaces.
Sintering machines accept and process a wide variety of feeds, differing from
plant to plant and sometimes from week to week in each plant (Figure VI-3.1).
The sintering machine is a long (100 feet) metal belt with oil or gas-fired
burners underneath to heat the mix to t-he kindling temperature. Plants range
from 2,000 to 6,000 tons/day capacity (150,000 to 500,000 lb./hr.).
It: has been reported that a typical sintering machine produces approxi-
cately 1.5 - 2 scfm of gases per lb./hr. of sinter (130 - 170 scfm at 70° F
per ton/day of sinter).* Since these gases leave the sintering machine at
recperatures generally at or below 400 F, additional cooling with dilution
air and''or water sprays is not required.
13 addition to the gases from the sintering machine, the hot sinter is
fee to a sinter cooler where additional gases are exhausted. Reported data
indicate that an additional 0.2 - 0.25 scfn per lb./hr. of sinter capacity
is exhausted at this stage.* The total stack gas flow rate from sinter plants
can. therefore, be expected to range from 1.7 - 2.3 scfm per lb./hr. of sinter
produced.
OA3 TEMPERATURE
The temperature of exhaust gases entering the control systems has been
reported to range from 100 to 400 F. Scrubbing systems will cool gases to
13: co 150°F, whereas temperature of gases from sintering machines to mechanical
separators, baghouses and electrostatic precipitators is somewhat higher, 175 to
GAS YELOCm-
No data were available,but gas exit velocities are expected to range from
25 - 50 feet per second depending upon plant operating conditions.
STACK HEIGHT
Stack height* for sintering operations range between 150 and 200 feet.
VI-13
-------
"Blast Furnaces"
The first step in the conversion of iron ore into steel takes place in
the blast furnace. It is a large steel cylindrical structure approximately
100 feet high lined with fire brick. Iron ore, coke, and limestone are fed
in the top and heated air is blasted in through the bottom. Between 100 and
300 tons of molten iron and slag are drawn off every few hours and taken to
open hearth or other steel making furnaces. (Figure VI-3.2)
Exhaust gases which are rich In carbon monoxide are burned to heat
stoves, coke ovens, or generate gteam; such gases are not normally vented
directly to the atmosphere.
GAS FLOW RATE
Gases leave the blast furnace at temperatures of 350 - 540°F and at
flow rates of about 0.5 - 0.8 scfm per Ib./hr. of pig iron produced (110,000 -
150,000 actual cubic feet per ton of pig iron). In other units, about 6 tons
of gases are produced per ton of pig iron produced. Actual flow rate is a
function of the coke rate as shown in Tigure VI-3.3. Gases emitted from blast
furnaces are cleaned in the.following three steps with the first two used
almost universally throughout the Indus try:
• Preliminary cleaning - settling chambers or
dry type cyclones.
• Primary cleaning - gas washers or wet scrubbers.
• Secondary washing - electrostatic precipitators
or high energy scrubbers.
Approximately 25% of the blast furnace gases are used as a fuel for the
blast stoves which preheat the air to the blast furnaces. The resulting com-
bustion products of the blast stoves range from 1.2 - 2.8 Ibs. of combustion
gas per Ib. of pig iron. Assuming a density of 0.08 Ib./cu. ft. at 60°F,
the volumetric flow rate of combustion products will range from 0.25 - 0.58
scfm per Ib./hr. of pig iron.
GAS TEMPERATURE
Combustion gases from the blast stoves are ducted to a common chimney
although separate chimney installations still exist. The temperature of
these blast stove combustion gases prior to mixing with other gases is un-
known, but 500 F may be assumed. The same exit temperature would be expected
for the blast furnace gas used to heat coke or generate steam.
VI-14
GAS VELOCITY
No data were available.but stack effluent exit velocities will vary from
stack to stack on any given plant site. Normal design criteria would place
this parameter in the 25 - 50 fps range.
STACK HEIGHT
No data were available, but stack heights for blast furnace operations will
undoubtedly be as high or higher than the blast furnaces themselves. Therefore,
assume 150 feet when no data are available.
VI-15
-------
"OPEN HEARTH FURNACE"
Ten years ago open hearth furnaces produced 9070 of the Nation's steel.
Today only about one-half of the total is produced by open hearth furnaces
since basic oxygen furnaces can now produce more steel more quickly and more
economically. The open hearth furnace typically holds between 100 and 200
tons of steel and completes one heat cycle in about 12 hours. A flow diagram
from a typical open hearth and electric furnace shop is shown in Figure VI-3.4.
Flame from combustion of oil, gas, tar, coke, oven gas, etc. travels
the length of the furnace above the molten metal. Upon leaving the furnace
exhaust gases pass through a checkerwork then possibly through a waste heat
boiler to control equipment.
Ox>gen lanciug is utilized to shorten the heat time, and partlculate
emission rates and gas volumes are both increased considerably. Oxygen con-
sumption ranges from 600 to 1000 cubic feet per ton (900 to 1,667 scfm during
the oxygen lancing).
GAS FLOW RATE
For the open hearth furnaces installations surveyed, exhaust gas flow
rates ranged from 10,000 to 73,500 scfin (Table VI-3.1). These data were
plotted in Figure VI-3.5 to give an equation which may be used in estimating
exhaust flow rates from various sice installations. If the installation
utilized oxygen lancing, an additonal 1000 scfm should be added to the value
obtained from Figure Vl-3.5.
GAS TEMPERATURE
The temperature of the combustion gases leaving the furnace range from
460 - 1800"F (Table VI-3.1). These gases must be cooled before entering air
pollution control equipment. This is usually accomplished through the use of
waste heat boilers which cool the gases to 500 - 600°F. Exit temperatures
from control equipment are expected to be about 200°F.
VI-16
GAS VELOCITY
No data were available, but 25 - 50 feet per second may be assumed in
detailed calculations.
STACK HEIGHT
Stack height will vary from plant to plant, but observations at
several steel mills indicate a range between 150 and 200 feet in height.
Assume 200 feet when no data are available.
VI-17
-------
"Basic Oxygen Furnace"
The basic oxygen furnace (EOF) is a top blown converter with a capacity
of 50 to 325 tons of steel. Oxygen is blown at rates of 20,000 scfm onto the
surface of the molten metal resulting in violent agitation and nixing of the
molten pig iron and oxygen. The heat cycle for a basic oxygen furnace will
be about 1 hour or less. All basic oxygen furnaces in this country have been
built within the past 15 years,and all are equipped with control equipment,
either high energy scrubbers or electrostatic precipitators.
Combustion gases leave the furnace mouth at approximately 2900°F with
the following gas composition:
CO : 74.0 - 90.57,
CCL :
!>„
5.0 - 16.0%
3.0 - 8.0%
At the interface of the furnace mouth and ventilation hood, controlled
quantities of dilution air combine with the furnace gases. In the conven-
tional BOF process, 100-150 percent excess air is utilized to oxidize all but
trace quantities of carbon monoxide.
GAS FLOW RATE
Figure VI-3.6 a«/ be used to estimate exhaust flow rates from
BOF furnaces. If water sprays are used to cool the gases after passing
through a waste heat boiler, Figure VI-3.7 may be used to estimate the
volume of water vapor added to the stack before exiting to the atmosphere.
GAS TEMPERATURE
The temperature of exhaust gases from the basic oxygen furnace range
from 2700 - 3100°F. The gases are then cooled by air dilution or water
sprays, and in some instances, waste heat boilers, prior to passing
through electrostatic precipitators and/or high energy scrubbers and out
the stack. The final temperature of the gases at the stack outlet
are generally around 300°F.
VI-18
GAS VELOCITY
No data were available, but stack gas exit velocity from the BOF
process is estimated at 25 - 50 fps,
STACK HEIGHT
No data were available, but stack heights normally associated with
the BOF steelmaking process are expected to range from 150 - 250 feet
with an average of approximately 200 feet.
VI-19
-------
"Electric Arc Furnace"
Electric furnaces are used primarily for production of special alloy
steels. The furnaces are refractory lined cylindrical vessels with large
carbon electrodes passing through the furnace roof. They produce from 2 to
200 tons of steel per heat. Oxygen may be used to increase the production
rate.
The off gases from electric arc furnace are generally collected by one
of three techniques: use of hoods over and around the furnace points of
emission, direct extraction of gases from the furnace interior, or extraction
of gases from the building roof. Baghouses and wet scrubbers are the primary
techniques for dust control. Cooling of the exhaust gases is accomplished
by radiation-convection cooling columns, by water-spray nozzles or by dilution
air,
GAS FLOW RATE
Table VI-3.2 presents furnace data on exhaust gas characteristics from
electric arc steel furnaces. These data were plotted in Figure VI-3.8
which may be used to estimate exhaust flow rates from electric are furnaces.
GAS TEMPERATURE
The temperature data from Table VI-3.2 indicate that stack temperatures
following cooling and dust collection will range from about 75 to 150°F.
An average temperature of about 150OF should be assumed when no data are
available.
GAS VELOCITY
No data were abailable, but stack gas velocities in the range of 25
- 50 feet per second are expected.
STACK HEIGHT
As in other steelnaking processes, the stack height will vary from
plant to plant; however, a range of 150 - 250 feet is normally found
with this process.
TABLE Vl-3.1
Exhaust Gases From Open Hearth Furnaces
Tons /heat
300
550
600
350
63
60
110
:os
:25
250
,75
330
4-220
175
Sv|: 175
Capacity
tons/hr.
37.5
50.0
55.0
45.0
6.0
5.5
10.0
25.5
19.0
21.0
23.0
41.0
27.5
14.5
17.5
Exhaust Flow
1000 scfm
60.0
66.5
73.5
70.0
14.9
14.4
20.0
40.0
33.0
10.0 - 32.0
18.0 - 33.0
37.7
71.0
35.0
35.0
Exhaust
Temp.
1400-1800
550
550
600-1500
460
550
550
600
Reference
19
20
20
21
22
23
23
23
23
23
23
23
24
25
23
VI-20
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VI-25
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Figure VI-3.3 Effects of coke feed rate on volume of blast furnace oas
VI-26
O. 3
A n
•8
-------
75 -
~ 50 •
Exhaust Flow Rate « 1.13 x Furnace Capacity +f|.4
(1,000 scfm) (tons/hr.)
10
50
20 30 40
Furnace Capacity (tons/hr.)
Figure Vl-3.5 Exhaust Flow rates for various size open hearth furnace
vi-28
G
150 .
100
S
I
50
Exhaust Flow Rate = 0.875 x Furnace Capacity
(1.000 scfm) (tons/heat)
50 100 150 200
Furnace Capacity (tons/heat)
Figure VI-3.6 Exhaust flow rates from BOF furnaces.
250
-------
0.6-
0.4.
0.2
Furnace qas temperature
just prior to water
sprays.
Inlet air temp.=60 F.
Inlet water temp.=60F
400 600
Stack Temperature (°F)
iobo
Figure V1-3.-7 Volumetric flow rate of water vapor per scfm of furnace
oases vs. stack tenperatures.
vi-30
75 .
R=.881
50 .
0
0
Exhaust Flow Rate = 0.63 x Furnace Capacity + 10.7
(1,000 scfm) - (tons/heat)
25
125
50 75 100
Furnace Capacity (tons/heat)
Figure Vl-3.8 Exhaust Flow rates for various size electric arc furnaces
vi-31
-------
CHAPTER VI-4
PRIMARY LEAD SMELTER B
Currently there are only 8 primary lead smelters in the U. S. with a
combined annual production capacity of about 830,000 tons. Three are lo-
cated in Missouri and one each in Texas, Utah, California, Idaho, and
Montana. Primary lead smelters are generally operated seven days a week,
24 hours a day except for occasional repairs or closings due to market
conditions. Five of the eight plants in recent years operated 365 days/year,
while one operated only 260. Average production for these plants is about
100,000 tons/yr. which is equivalent to about 25,000 Ib./hr. Primary lead
smelters all employ essentially the same processing steps; sintering,
reduction in a blast furnace and refining. Refining also includes operation
of a dross reverberatory furnace. In addition lead smelter operations include
cadmium recovery and slag fuming for zinc recovery (Figure VI-4.1).
Lead sulfide ores are converted to oxides of lead and sulfur in the
sintering step at a relatively low temperature. The oxidized solids are
then reduced with coke in the blast furnace at a high temperature to form
impure metal and slag. A refining operation is then performed on the impure
metal to produce lead bullion, 95-99% pure, which is the principal product
of lead smelting operations. Secondary products such as zinc oxide and
cadmium" dusts may be refined for market or shipped to other plants for further
extraction of other metals. These auxiliary processes are not considered
in this chapter.
Sintering off gases include large quantities of sulfur dioxide, up to 5
percent, and trace amounts of other gases. Organic vapors from flotation
reagents in the concentrates are also present in the off gases. Fumes con-
tained in the off gas include oxides of arsenic, cadmium, lead, zinc, selenium,
tellurium, and traces of other substances.
Blast furnace off gases include small amounts of sulfur dioxide and
large amounts of dust and metal fumes. Dilution of the flue gas at the
top of the furnace burns the carbon monoxide (25-507.) to carbon dioxide
and cools the exhaust gases from about 1200°F to about 4QO°F prior to en-
tering control equipment. In the refinery step, the refinery kettle and
dross furnace generate metal fume*. The dross furnace operates 20 to 70
percent of the time the refinery furnace operates.
VI-32
Sinter gases at two or three of the eight plants are sent to a sulfuric
acid recovery plant. Electrostatic precipitators or baghouses are used to
collect dust and fumes from the entire plant's exhaust gases.
GAS FLOW RATE
Actual plant data from 5 plants indicate that total stack exhaust gases
from the sintering, blast furnace and refining steps range from 4.^3 - 16.92
scfm per Ib./hr, of plant production capacity with an average of about 10
scfm per Ib./hr.
The volume of gases emitted from each of the major sources (i.e.
sintering machines, blast furnaces, refinery kettles and dross reverber-
atory furnaces) obviously is dependent primarily on machine or furnace
size and material throughput. However, such data were not available, so
correlations of gas flow rates were made with total plant production. In
general gas volumes from the sintering machine run about 100 - 200 scfm
per sq. ft. of bed area. Temperatures normally range between 250 - 600°F.
Blast furnace gas is related to size but generally runs 5,000 - 9,000 scfra.
Off gases from the dross reverb run from 1,000 - 3,000 scfm and exit at a
temperature of about 1,400 - 1,800°F.
Only three data points were available showing volume of exhausts
emitted from sintering machines at different plant capacities (Table VI-4.1).
Flow rates ranged from 0.80 - 1.40 scfm per Ib./hr. of lead production for
plant capacities of 27,000 to 46,000 Ibs./hr. (Figure VI-4.2). As a rule
of thumb, gas volumes run about 100 - 200 scfm per sq. ft.
Significant quantities of dilution air enter the blast furnace exhausts
either through charging ports or at the top of the furnace. As mentioned
earlier, this air is necessary to burn the CO present in the furnace gases.
Five data points were available (Figure VI-4.2) with which to draw a
least-squares line. The average flow of gases from blast furnaces at the stack
would be 0.6 scfm per Ib./hr. of plant capacity. Since the data were quite
scattered the deviations between the data and the least squares line are
significant.
Volumetric flow rates of gases from dross reverberatory furnaces are
significantly less (slope of least squares line is 0.3 scfm per Ib./hr.) than
the gases from blast furnaces for the sane plavt capacity (Figure VI-4.2).
VI-33
-------
No data were reported for exhaust gas volumes from the refining
kettles, but some idea of the volume could be estimated by subtracting the
other stack gases, after dilution, from the total given in Table VI-4.1.
Assume 500°F for the sinter gases and 1800°F each for the blast furnace
and dross reverberatory gases.
GAS TEMPERATURE
Limited stack gas temperature data were available for the 8 primary
lead smelters. Temperatures of the cooled gases at the stack ranged from
110 to 300°F, with sintering stack temperatures somewhat lower (135°F)
than stack gases from the furnace and refining operations (225 F) . For dis-
persion calculations 200 F should be assumed for all effluents.
GAS VELOCITY
No data were available, but stack gas exit velocity will vary from
plant to plant and within a plant. It is expected to range from 25 - 50
feet per second. If exit velocity information is not available, a velocity
of 35 feet per second can be assumed.
STACK HEIGHT
No data were available,but the major stack at one plant was
observed to be about 200 feet in height. Stack heights will vary
from plant to plant, however vhen actual stack information is not
available, a height of 200 feet may be assumed.
VI-34
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O Sinterinq Machine
O Blast Furnace
® Dross Reverb. Furnace
10 20 30 40 50
Production Capacity (1,000 Ib./hr.)
Figure VI-4.2 Exhaust flow rates from the lead sintering machine, blast
furnace and dross reverberatory furnace as a function of plant
production capability
l-T-3-'
-------
CHAPTER VI-5
PRIMARY ZINC SKELTER
There are currently 14 primary zinc smelters in the United States,
located in seven states: Pennsylvania-2; West Virginia-1; Illinois-2;
Oklahoma-3; Texas-3; Montana-2; and Idaho-l. Typical plant size, is about
90,000 tons/year or 25,000 Ib./hr, but the range is from 44,000 tons/year
to 252,000 tons/year.
Primary zinc smelters are generally operated seven days a week, 24 hours
a day, except for occasional scheduled or unscheduled shutdown!. Extraction
of zinc requires chat the raw material first be processed to convert the
zinc content to a dense zinc oxide. Roasting, sintering and calcining are
the three extraction operations that are used to accomplish this. Some
plants roast (12 plants); some roast and sinter; one only sinters. Calcining
is performed only on oxide ores or on material previously oxidized by a
roaster. The zinc metal is extracted from the preprocessed material either
by heat reduction with fuel followed by distillation (9 plants) or by dis-
solving the zinc oxide in acid and precipitating the metal electrolytically
(5 plants). A flow diagram appears as Figure VI-5.1.
Emissions fron zinc smelters consist of sulfur dioxide, dust, and metal
fumes. Nine plants recover SO. with acid plants. Particulates are collected
by flues, cyclones, precipitators, and baghouses.
GAS FLOW RATE
Roaster exhaust gas volumes vary primarily with the type and size of
roaster. The Rapp roasters produce 20-35,000 scfm at temperatures of 730 -
900°F; multiple hearth roasters generate about 15,000 scfm at 500°F entering
the precipitator (includes dilution); suspension roasters produce 10,000 -
15,000 scfm at 600° after a waste heat boiler; fluid bed roasters produce
11,000 - 18,000 scfm at about 500°F at the precipitator.
Sintering machines vary the gas flow rates depending on feed. With a
calcined feed,exit gas rates are from 140-240 scfm per sq. ft. of grate.
With a concentrate feed, the gas rate is only 18-20 scfm per sq. ft.
Calcining gas flow rates are not known and data were available on only
two distillation furnaces. The volume of gases emitted directly from each
of the three primary sources (i.e., roasters, sinter machines and distillation
VI-38
furnaces) is correlated with plant zinc production. Since both dilution
air and water sprays are used for cooling furnace gases, data presented
for copper smelters can be utilized to estimate the quantity of dilution
air and water required to produce a certain stack temperature. By knowing
or estimating the degree of cooling associated with each method, dilution
air and/or water vapor can be summed with furnace gases to estimate the
total stack gas flow rates as a function of plant production capacity.
Figure VI-5.2 relates the volumetric flow rate of exhaust gases from
the roasting and sintering furnaces respectively, as a function of plant
2
capacity. Based upon the data available, straight line correlations exist
for all but a few data points. No explanation was found for the wide
variations of these few points, and so for the purpose of this study, they
were neglected.
The one source of data found for volumetric flow rates from distillation
o
retort furnaces indicated that approximately 20-30 scfm of exhaust gases
would be generated per Ib./hr. of zinc produced. These values suggest that
large volumes of dilution air mix with the gases generated in the distillation
furnace after they leave the condenser.
GAS TEMPERATURE
Operating temperatures for zinc roasters vary between 1200 and 1900°F.
Since fluid bed and suspension roasters are most commonly used and since
operating temperatures for these units generally ranged from 1700 to 1800 1',
an outlet temperature (T1) for roasters of 1750°F should be selected.
Sintering machine exit gases usually range from 500 - 700°F and so an average
temperature (T1) of 600 F should be selected.
Gas temperatures at the stack exit were available for 8 of the 14
prinary zinc smelters. The cooled exit gases ranged in temperature from
130 to 400°?. Gases iron the roaster and calciner were cooled to 300 to
400 F whereas gases from the sintering machine were cooled to 200 F.
Although there is no available data for stack temperatures of cooled
retort combustion gases, the one data point in column 4 suggests that these
gases are cooled down to approximately 160 F. In general, an exit temperature
of 30C°F should be used for calculating plume rise unless specific data are
available.
VI-39
-------
GAS
No data were available, but gas discharge velocity at each stack will
vary from plant to plant and within each plant depending upon existing plant
operations. An exit velocity of 25-50 fps should be assumed for stacks
associated with primary zinc smelters,
STACK HEIGHT
Zinc smelters will utilize several stacks to discharge process effluent
gases. Stack height will vary from plant to plant and within each plant.
Primary operations at one plant had stacks exceeding 150 feet in height; stack
heights should be assumed as 200 feet unless data are available.
VI-40
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100 .
50
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(1.000 scfm) (1.000 Ib./nr.)
10 20 30 40
Production Capacity (1,000 Ib./hr.)
50
Figure VI-5.2 Exhaust flow rates from zinc roaster, sintering machine,
and calciner vs. plant production capacity
VI-4 3
-------
CHAPTER VI-6
METALLURGICAL COKE MANUFACTURE
Coke is the major fuel and reducing agent used in blast furnaces for iron
manufacture and other metallurgical production operations. Technological
developments have resulted in a decrease over the past 10 years in the amount
of coke required to produce a ton of pig iron from 1,600 pounds to 1,250
pounds per ton. Still, there are some 60 plants in the U. S. producing
about 80 million tons of coke annually. Sixteen plants are located in
Pennsylvania, 12 in Ohio, and the rest in 14 other states. A typical plant
will have a battery of about 100 slot type ovens. Each oven will receive
about 27 tons of coal and produce about 20 tons of coke per cycle.
The manufacture of metallurgical coke is carried out primarily in by-
product type coke ovens. The alternative coking technique, beehive coking,
has been limited to less than 1 percent in the American integrated iron and
steel industry for the last five years.
Figure VI-6.1 is a flow diagram of a typical by-product coke plant.
Emissions from coke ovens arise from charging coal, discharging or pushing
coke, leaking oven doors during carbonization, and quenching of finished coke.
During the 18-20 hour carbonizing period, coke ovens are heated with coke
oven or blast furnace gases which are rich in carbon conoxide. Under ordinary
operating conditions, exhaust from this combustion process does not contain
significant air contaminants. Accordingly, these exhaust gases are not a
significant source of pollution unless coal gas from the ovens leaks into the
4
flues. This sometimes occurs in older plants.
The majority of the losses from coke ovens occur during the charging
9
operation. Other losses primarily occur during the discharging or pushing
of coal. Leaking may occur around the ports and the end doors during coking,
4
but these emissions are usually a "mere wisp*' when compared to the gases re-
leased during charging. No specific control equipment is utilized to reduce
smoke and volatile gas emissions from these coke ovens.
During pushing the open-air release of incandescent coke produces a con-
siderable induced draft in the immediate surroundings, and fine particulates are
blown high into the atmosphere. This draft, however, is comprised almost com-
pletely of ambient air, and any oven losses consist mainly of blown particulates.
VI-44
With proper coking cycles and oven heating practices, however, these particu-
late emissions are minimal.
The pushed coke is received into an open hopper car of special design,
with a sloped bottom and side gates made of grating. This car may be self-
propelled or moved by locomotive tc a large brick chimney that fits over the
open top of the car. Sprays in the chimney- deluge the hot coke with water to
cool and quench it. During the quenching operation, substantial quantities
of steam are generated which rise up the chimney carrying particulate matter
with it. These particulates tend to fall out locally in the vicinity of
the quenching tower and usually are not carried great distances as a sus-
pended dust plume. The quenching time is about 2 minutes depending on the
practice in any particular plant.
GAS FLOK RATE
Coking coal generates a considerable volume of volatile material estimated
at 20 - 30"'.- of the incoming coal. These volatilized gases amount to 7.8 - 13.4
scf/lb. of coke produced. A centrifugal exhauster collects the majority
of the gases froc the ovens during the coking process for further processing
downstream m the by-product plant. No data were found on the gaseous emission
rate free coke ovens. However,if it is assumed that 0.1% of the volatilized gases
(0.1'. of 10 scf Ib. coke) escapes into the atmosphere, then the estimated volume
of exhaust gases discharged to the atmosphere would be 0.01 cubic feet Ib. of
coke produced.
GAS TEi-iPERATURE
The temperature of the gases escaping during the charging cycle generally
approximates 550°F. A similar temperature is expected during coking or
pushing. Quenching tower gases are expected to be about 200 F.
GAS VELOCITY
A coke oven, processing about 27 tons of coal per day, has 4 or 5 coal-charging
^
ports each about 10-14 inches in diameter. These openings provide an area
of 2.2 to 5.4 sq. ft. through which the gases escape. Resulting velocities
of gases escaping through these ports at 550 F approximate 10 fps.
VI-45
-------
STACK HEIGHT
There is not a normal stack associated with the coking process, and all
smoke and exhaust gases are exhausted at an elevation of about 10 - 20 feet.
Quenching towers would exhaust at elevations of about 50 feet.
VI-46
Figure VI-6.1 Flow diagram of a typical by-product coke plant
VI-47
-------
CHAPTER VI-7
SECONDARY ALUMINUM SMELTER B
.Secondary aluminum operations consist of remelting, demagging, alloying
and casting aluminum from scrap aluminum parts. The melting process is
carried out in crucible or reverberatory furnaces. Crucible or pot-type
furnaces are Indirectly heated and are used for melting small quantities, e.g.
1,000 Ibs. of aluminum. Reverberatory furnaces are directly fired and are
used for medium and large capacity heats or batches of 2,000 - 200,000 Ibs.
(Table VI-7.1).
A typical plant will have 4 or 5 furnaces and produce 100,000 - 1,000,000
Ib./day. One heat is produced in a 24-hour period; however, batch tines vary
fron 4 to 72 hours. The material charged, charging methods, furnace capacity
and design, heat-input, fluxing, refining and alloying procedures all influence
the tioe required to complete a heat. Two other operations are common to
these smelters. Sweat furnaces are used to melt aluminum off of iron and other
netals. Barings or turnings from aluminum metal fabricating plants are fired
with a burner to remove cutting oils and grease.
Emissions are primarily magnesium and aluminum chloride fumes which react
with moisture in the air to form magnesium and aluminum oxides and hydrogen
chloride. The chlorine gas is blown through the metal batch to remove magnesium
and gases from the molten aluminum. High energy scrubbers are the commonly used
control equipment. 'Black smoke from the oil burning operation can be controlled
with afterburners.
GAS FLOW RATE
During the melting part of the heat cycle, when the burners are on, the
combustion gases are generally free of pollutants and no controls are necessary.
This assumes that the scrap feed material is relatively clean. However,
emissions of aluminum and magnesium chloride require control during the charging,
degassing and demagging operations. During these operations, however, the
burners are off and the volume of gases generated are significantly less than
if combustion gases were also present. The exhaust rate then will depend entirely
on the chlorine gassing rate. Stack gas flow rates from reverberatory furnaces
in California during the charging, degassing and demagging operations ranged
from 0.25 to 1.0 scfn per Ib./hr. of metal processed. In New Jersey three
VI-48
plants showed gas flow rates between 0.1 and 2.5 scfm per Ib./hr. of metal
processed. It is very likely that the low flow rate was reported for demagging
operations, and the high values represent straight melting operations, although
such details were not specific.
GAS TEMPERATURE
The temperature of molten slmr.ini3r. netal in reverberatory and crucible
furnaces generally ranges from 1300 - 1350°F. Gases emitted from the furnaces
at these temperatures are combined with ventilation air prior to entering
ventilation hoods. In order to control the fluoride and chloride emissions
during the fluxing, degassing and denagging operations, wet scrubbers are
generally utilized and may be follovec by a baghouse or electrostatic precipi-
tator to control solids. A typical stack temperature following such air
pollution abatement equipment is 200 ?. Temperatures from 3 New Jersey plants
ranged from 300 - 700°F. Where control equipcent is not utilized, 500°F should
be assumed.
GAS VELOCITY
Stack gas velocities for three California secondary aluminum smelters during
charging, degassing and denaggir.g or. reveroeratory furnaces ranged from 17 - 23
fps. The three New Jersey plants showed velocities between 1 and 25 fps, but the
velocity of 1 fps is highly suspect. There d=ta are not available, assurae 20 fps
for calculations.
Stack Height
Based on several observations ir. the industry, stack heights for a typical
aluminum smelting operation will range fron 15 to 75 feet with an average value
of approximately 40 feet. Four stacks for which data were reported ranged from
33.5 to 65 feet. Each furnace will have a separate stack.
VI-49
-------
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GAS TEMPERATURE
Smelting furnaces are generally operated at temperatures between 2000 and
2200 F. Gases discharge at these temperatures but are cooled prior to
passing through appropriate air pollution control systems. Large quantities
of ventilation air enter the system at the hood-furnace interface and serve
also to cool the furnace gases. Water sprays and radiation cooling are commonly
utilized to further reduce the flue gas temperature. Indirect cooling
utilizing cooling towers is also practiced. Baghouses are the most cannon type
of control equipment. Typical operating temperature for these baghouses, and
therefore stack temperatures, range from 150 - 275°F. If glass fibers are
utilized as the filter media, temperatures of up to 500°F can be tolerated.
Data for two plants showed 70% and 250°F as exit temperatures. Where infor-
mation is lacking, 200°F should be assumed. Without control equipment 500°F
may be assumed.
GAS VELOCITY
Stack gas velocities for 11 brass smelters ranged from 32 - 70 fps with an
average of 53 fps.11'12 where no data exists, 50 fps should be assumed.
STACK HEIGHT
Stack heights for brass and bronze foundries normally can be found in the
range of 20 - 50 feet. Two plants had stack heights of 20 and 26 feet.
An average value of 30 feet may be assumed.
VI-52
CHAPTER VI-9
GRAY IRON FOUNDRY
Gray iron foundries produce a heavy, brittle metal commonly called cast
iron, but named after its characteristic gray-white color. There are over
6,000 foundries in the United States which use over 3,300 cupolas. Cupolas
are used to melt over 907S of the metal poured for gray iron casting. They
range in capacity from 1 to 50 tons of melted metal per hour with over 607,
ranging front 3 to 11 tons per hour. However, electric furnaces are gaining
in popularity partially because of the lower emission characteristics associated
with this furnace. Reverberatory and crucible furnaces are occasionally utilized,
but their conbinee usage is less than 2% of all foundries and they generate
relatively low quantities of emissions.
Table '.'1-9.1 shows operating characteristics for 6 plants with cupolas
ranging from 4 to 20 tons per hour. Approximately 95%. of all cupolas fall
vithin this range. As seen, melt times vary from 3-16 hours per day and
foundries operate iron 175 to 250 days per year.
A flow diagrar. of a typical pattern shop and gray iron foundry is
shovr. ir. Figure 71-9.1. Principal emissions from iron foundries are iron
oxide dust and fume and carbon monoxide. Major controls are precipitators
and venturi scrubbers, although only a small precent of the total number of
foundries are controlled.
GAS FLOW RATE
Data froc two Xew Jersey cupolas shoved exhaust rates of 7,000 scfm from
production of ",000 Ib./hr. of iron and 45,540 cfm from producing 34,000 Ib./hr.
of iror.. Both exhaust volumes were at 165°F. so correcting to "0°F gives
O.S to 1.1 scfn per Ib./hr, of iron produced. Another cupola in Ohio melted
70,000 I?, hr. with a steady blast of 14,500 cfai. Wet exhaust gases after
a scr-_bcer totalled 70,000 cfm at 160°F with 31% moisture.
Because of the many types of flue gas conditioning systems employed,
stack gas flow rates may be expected to vary somewhat. However, since about
1 Ib. of air is blown through the cupola tuyeres per Ib. o£ Iron produced, and
from 200 - 500" infiltration air enters through the charging ports, the
resultant volumetric flow rate will,generally be 0.62 - 1.25 scfm per Ib./hr.
of iron produced.16 Figure VI-9.2 may be of further assistance in determining
exhaust gas flow rates from gray iron foundrys.
VI-53
-------
CAS TEMPERATURE
Gases from cupola furnaces range from 1500 - 2000°F. These gases are
generally vented directly from a cupola sealed at the top to a control system
or alternatively vented out the top of the cupola directly if no control system
is utilized. The control system generally consists of an afterburner, flue gas
conditioning and a baghouse or electrostatic precipitator. Cooling may be
accomplished by dilution air, water sprays, radiation-convection columns or a
combination of these. Of the three, water sprays are the most commonly
employed. Stack gas temperatures following control systems generally range
from 200 - 500 F. The three foundries for which data were available had exit
temperatures of 160, 165, and 166 F. Therefore, assume 200°F whenever specific
data is lacking.
GAS VELOCITY
Velocity data for 3 gray iron cupolas located in Los Angeles County
ranged from 32 - 42 fps. Two in New Jersey had velocities of 39 and 53 fps.
The one in Ohio had a stack velocity of 61 fps. When data are unavailable,
40 fps day be assumed.
STACK HEIGHT
Stack heights normally increase with foundry size but generally fall in the
50 - 100 foot range with an average height of approximately 75 ft. Large
foundries have stacks on the order of 200 feet. For calculating assume 75 feet.
TABLE VI-9.1
Typical Gray Iron Foundry Operating Characteristics
12
Melt rate/cupola,
tons/hr.
4
6
8
12
16
20
Melt time
hr./day
3
5
7
16
days/year
175
200
225
250
250
Number
of cupolas
VI-5A
VI-55
-------
TABLE VI-9.2
Exhaust Gases From Gray Iron Foundry Installations
Cupola
Capacity
Ib./hr.
Exhaust
Flow
scfm
8,380
14,000
16,800
24,650
8,200
36,900
39,100
5,520
20,300
8,430
17,700
8., 300
21,000
30,500
Exhaust
Temp.
1,400
430
482
210
1,085
222
213
VI-S6
iS-IA
-------
30
O 20
10
R=.843
O
Exhaust Flow Rate • 0.59 x Cupola Capacity + 3.5
(1,000 sefm) (1,000 Ib./hr.)
10 20 30 40
Cupola Capacity (1,000 Ib./hr.)
50
Figure VI-9.2 Exhaust Flo* rates for various size gray Iron foundry
Installations.
VI-58
CHAPTER VI-10
SECONDA.'1.':
StELTER
There ar.; aho.it 5T secondary lead smelters in the United States. Some of
the plants al^o manufacture lead batteries and utilize scrap batteries as their
input materials, but the actual degree to which the t»'o operations are combined
is not known. A typical plant will produce on t>» cruet of 50,000 Ib./day of
lead ingot. Although no information was found in the literature regarding
operating times of secondary lead smelters, it is assumed to be similar to
other secondary smelters, i.e. operating 2-3 shifts per day and 5 to 6 days
per week, depending on product demand.
Lead smelting is conducted in blast furnaces, pot furnaces or reverberatory
furnaces. The nature of each furnace and their resulting emissions vary enough
so that a discussion of each furnace is presented later.
Emissions are primarily lead oxide fumes, although other metals, silica, and
sulfur oxides will be present. Principal control devices are baghouses or pre-
cipitators. Cases are cooled by dilution air, radiatior., or water prior to
entering the control equipment.
GAS FLCK RATE
The gases leaving reverberatory furnaces, which operate under positive
pressure to sustain the required lead bath temperature, cocbine with ventilating
air and are ducted through external hoods to collectors. As mentioned above,
such collection devices generally consist of baghouses with the typical techniques
for gas cooling employed. Data for one reverberatory furnace , utilizing indirect
heat exchange cooling techniques in addition to ventilation air, showed a stack
gas flow rate of 4.2 scfn per Ib./hr. of metal produced. Another investigator
indicated that a dross reverberatory furnace with no collection devices generated
approximately 1.1 scfm per Ib./hr. of lead processed. Other tests showed
exhaust gases to total 9,350 scfm from a reverberatory furnace.
Lead blast furnaces or cupolas are very similar to the cupolas utilized in
the gray iron foundry industry.
Blast furnace gas temperatures exit at temperatures fron 1200 - 1350 F.
Afterburners nay be necessary to control the combustible emissions in the
effluent since carbon monoxide concentrations range from 1 to 10 percent. The
gases are generally vented directly to a control system after being cooled or
VI-59
-------
receiving seme type of gas conditioning. Cooling may be accomplished by
dilution air, water sprays, radiation-convection columns or a combination
of these.
Because lead blast furnaces or cupola operations are similar to the
cupolas used in the gray iron foundry industry, volumetric flow rates pre-
sented in Chapter VI-9 apply here. Data for one lead blast furnace
installation show a stack volumetric flow rate of 4.95 scfm per Ib./hr. of
metal processed. This furnace utilized dilution air for cooling and,
therefore, falls within the range (2.5 - 5.0 scfm per Ib./hr, of metal pro-
cessed) estimated in the section on gray iron foundries for dilution cooling.
Since pot furnaces are indirectly fired, their pollution potential is
much less significant than either the blast or reverberatory furnaces. These
furnaces vary in size from 1-50 tons and are utilized primarily for alloying
and refining. No data were found on gas flow rates. Based on experience in
the steel industry, lead pots would be expected to have flow rates on the
order on one-tenth that of the reverberatory furnace or 0.1-0.4 scfm per Ib./hr.
of netal produced.
GAS TEMPERATURE
Gases exiting from the melting furnaces are 1200-1400°F. However, dilution
and cooling prior to clean-up lowers temperatures to about 30Q°F. Temperatures
on the stack following a baghouse serving both a reverberatory and blast furnace
were 200°F. Since most lead smelters would be controlled, 200°F should be
as SUM d for exit gas temperature.
GAS VELOCITY
Data from one set of stack tests showed the combined exhaust exit velocities
to be 32 fps prior to the baghouse and 50 fps afterwards. Stack diameters were
29 inches on two cooling inlet pipes and 36 inches on one outlet stack.
STACK HEIGHT
Observations at one plant indicated a steel 36" diameter stack with a height
of about 100 feet.
VI-60
CHAPTER VI-11
MAGNESIUM SMELTING "
Magnesium smelting is done in small steel pots having a capacity of
between 500 and 5,000 Ib./batch. Each sEelt takes about 8 hours: 2 hours
charging, 2 hours melting (at about 1200 Fl, 4 hours pouring and 2 hours for
clean out. Plants usually operate 2 or 3 shifts per day depending on the
market demand. Magnesium scrap is usually made up of oily Volkswagen engine
blocks, magnesium shavings/turnings, bomber wheels etc. The major pollutants
are particulates in two forms. During charging, the oily material burns and
black soot (of about Renglemann 5) is visible for a few seconds after each
"hand full" of scrap is added. The other forn of particulates is submicron in
size emanating during the entire process and are netal fumes. Fluxes contain
about 98% Cl " (like MgClj, BaCl2 and KCDanc about 2% F~(like CaF2). As a
result HC1 is given off in high concentrations, 200 ppm over the duration
of the cycle. Natural gas is usually the heat fuel for the pots. Very few
plants have any control equipment. Those that do control particulates would
use a high energy scrubber or a baghouse.
Plant capacity depends on the p.unber of pots. Some of the pots may
have heat shields, conical in shape, which also serve as an "inner stack".
From the inner stack, pollutants are hooded to several roof top ventilation
fans.
GAS FLOW RATE
The gas flow rate for one plant having several lines ranged from 800 to
17 ,
1100 scfm for the entire 8 hour cycle at the inner stacks. The exit flow
at roof top depends on the power of the fans. One plant having 6 roof top
fans had a total exit flow of 180,000 scfm for a capacity of 8,000 Ib./hr.
17
GAS TEMPERATURE
The gas temperature about 15 feet above the molten metal will range from
160 to 320°F unit a mean of 220°F for the 8 hour cycle. Hoods and dillution
air will make the temperature at roof top 90°F.
VI-61
-------
GAS VELOCITY
The velocities for one plant having several pots ranged from
10 to 14 fps at the pot inner stack. Roof ventilation, however, is
commonly used, and exit velocity will depend on fan size. The exit
velocity at the roof is about 20 to 25 fps.
STACK HEIGHT
Common stack heights for smelting operations are about 65 feet.
Because ventilation fans are mounted in the roof apex, there is not
the traditional round or square stack protruding several feet above
the roof top.
CHAPTER Vl-12
STEEL FOUNDRIES C
Steel foundries differ from the basic iron and steel plants since their
primary rav material is scrap steel (instead of pig iron). Steel foundries
produce cast steel, i\& a finished product, usually for heavy industrial end
uses like the frame of a bulldozer, locomotive wheels, etc. There are about
400 steel foundries operating in the U. S. Typical plant sizes depend on
the number of furnaces but range from 25 to 240 tons per day. There are
five types of furnaces: direct electric, electric induction, open hearth,
crucible and pneunatic converter.
Particulate emissions from the foundry include iron oxide, sand fines
(from the casts), graphite, and metalic dust. Gaseous emissions include SO ,
SO and hydrocarbons. Most plants will use air pollution abatement devices
except plants having electric induction furnaces. At minimum, all plants will
>ave sore ver.tilati.on system to remove heat from the work area. Conaaon types
o£ control ecuipcer.t include electrostatic precipitators, venturi scrubbers
and baghouses, The operating times of steel foundries is continuous 24 hours
a day ard 7 days a week for large plants and intermittent for small plants
Average 8 hr. dayi.
GAS -I.CV .SATS
exhaust gas flow rates for three steel foundries ranged between 1 and 5
scfc per li. hr. for plants using control equipment as well as those which
used or.ly a roof ventilation system. Exhaust flow averaged 3.3 scfm per Ib./hr.
capacity. See Taile VI-12.1.1 >1/
GAS 7£>gE5tAIVH£
The exhaust gas temperature is about 150 F because of the dilution air
needed to cool the work area. (Furnace gas temperatures range from 2,000 to
3,000°F.'> The range for the data was 80 to 675 F for exit temperatures.
GAS VELOCITY
Typical exit velocities will be 50 fps. From the data collected the exit
velocity ranged from 50 to 60 fps for both plants having control equipment and
plant* having only ventilation fans.
VI-62
VI-63
-------
S9-IA
STACK HEIGHT
The stack heights for 3 foundries ranged from 55 to 85 feet. Typical
stack heights fall in this range, and 75 feet should be used for calculation
purposes.
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VI-64
-------
CHAPTER VI-13
SECONDARY ZINC SMELTER D
In 1967, 73,000 tons of redistilled secondary zinc slab were produced in
U V. S. plants.
Secondary zinc is melted in a variety of furnaces for use in alloying,
casting and galvanizing. These furnaces include crucible, pot, kettle,
reverberatory and electric induction units. The melting operation is essen-
tially the same for all these units. The zinc feed may be in the form of
ingots, rejected castings, flashing or scrap. Pouring temperature for the
rolceti zinc is generally maintained between 800 and 1100 F. Fluxes are added
prior to pouring and cause a dross to form at the top of the melt. Following
5'
-------
CHAPTER VI REFERENCES
10.
11.
12.
13.
14.
15.
16.
Personal Communications with Alpiser, P.M., NAPCA, Division of Abate-
ment, Engineering Branch, Durham, N.C., February, 1970.
"Systems Study for Control of Emissions From Primary Non-Ferrous
Smelting Industry", Arthur G. McKee and Co., Publication No. 184-885,
June 1969.
"Air Pollution Aspects of the Iron and Steel Industry", U.S. Department
of HEW, Public Health Service, Publ. No. 999-AP-l, Cinn., Ohio, June 1963.
Varga, J. Jr., et al, "A Systems Analysis Study of the Integrated Iron
and Steel Industry", Battelle Memorial Institute, Columbus, Ohio
May 15, 1969, PG 184-577.
Skelly, J.F., "Profits in EOF Gas Collection", Iron and Steel Engineer,
March, 1966, pgs 82-88.
Gille, Paul V., KemmetmueHen, Roland, "Minimizing Dust Problems in
EOF Shops", Iron and Steel Engineer, September 1966, pgs 193-201.
Danielson, John A., Air Pollution Engineering Manual, Air Pollution
Control District, County of Los Angeles, U.S. Department of HEW,
Public Health Service Publication No. 999-AP-40,
Stern, A.C., Air Pollution, Vol. Ill, New York, Academic Press,
1968.
Elliott, A.C., "Experience with A "Smokeless" Oven," Larry Car, Presented
at the 63rd Annual Meeting of APCA, June 1970, APCA Paper No. 70-98.
Smith, William M. ."Evaluation of Coke Oven Emissions", Presented at the
63rd Annual Meeting of APCA, June, 1970, APCA Paper Xo. 70-94.
Allen, GlennL., et al, "Control of Metallurgical and Mineral Dusts and
Fumes in Los Angeles County, California," Bureau of .Mines Information
Center 7627, 1952.
State Air Pollution Permit Data, April 1971.
"Air Pollution Aspects of Brass and Bronze Smelting and Refining
Industry", Brass and Bronze Institute, National Air Pollution Control
Administration, NAPCA Publication No. AP-58, 1969.
Personal Communication with Alpiser, F.H., APCO, April, 1971.
"Economic Impact of Air Pollution Controls on Gray Iron Foundry Industry",
HEW, NAPCA Publication No. AP-74, 1970.
"The Cupola and its Operation", American Foundrvmen's Society, 3rd Ed.,
1965.
VI-68
17. Unpublished data, Zurn Environmental Engineers.
18. Robertson, D.J., "Filtration of Copper Smelting Gases at Hudson Bay
Mining and Smelting Company", Can._Mining Met. Bull., Vol. 53, p. 236,
1960.
19. Johnson, J.E., Wet Washing of Open Hearth Gases. Iron and Steel Engineer
February 1967.
20. Smith, W.M. and Coy, D.W., "Fume Collection in a Steel Plant", Chemical
Engineering Progress, Vol. 62, No. 7, July 1966.
21. Broman, Carl V. and Iseli, Ronald R., "The Control of Open Hearth Stack
Emissions with Venturi Type Scrubber", Blast Furnace and Steel Plant,
February 1968.
22. Danielson, John A., Air Pollution Engineering Manual, Air Pollution
Control District, County of Los Angeles, U.S. Department of HEW,
Public Health Service Publication No. 999-AP-40, pp. 253-256.
23. Schueneman, Jean J., High, M.D., Bye, W.E., "Air Pollution Aspects of The
Iron and Steel Industry", Public Health Service Publication So. 999-AP-l
1963.
26.
Punch, G., "Elimination of Fumes in Iron and Steel Industry", Steel
International Vol. 3, So. 12, London, July-August 1967.
Duprey, 8.L., "Compilation of Air Pollutant Emission Factors", Public
Health Service Publication No. 999-AP-42, 1958.
Bintzer, W.W. and Kleintop, D.R., "Design, Operation and Maintenance of
a 150 Ton Electric Furnace Dust Collection System", Iron and Steel
Engineer, June 1967. >
VI-69
-------
CHAPTER VII-1
ASHPHALT ROOFING PLANT A
Asphalt is a residue produced as a by-product in regular petroleum refining
processes. Oxidized asphalts (air blown asphalts) are commonly used in the
manufacture of roofing papers and shingles and for grouting. The air blowing
process used in the manufacture of asphalt roofing consists of blowing air
under controlled conditions into the asphalt residue for perdetermined periods
of time. The air blowing is not only a physical process but is also a chemical
process for conversion of hydrocarbons. The asphalt roofing market comprises
about 1/5 of the total asphalt market with 1968 sales of 5 million short tons.
Asphalt roofing plants are located in every state with California leading the
nation in production.
Typical operational times for this continuous process are 5-6 days a week
and 2 shifts per day. The points of air contaminent emission are the asphalt
presaturater sprays, the saturator tank and the wet looper (Figure VII-1.1).
Pollutants are organic asphalt mists and particulates. Spray scrubbers and
two stage electrostatic precipators are the recommended control equipment for
the wet looper and the saturator tank. Since virtually no material is liberated
from the sum of process weights, input-output quantities will be equal.
GAS FLOW, RATE
Air volumes handled by the exhaust system vary with hood design and saturation
size but range between 10,000 and 20,000 scfm where control equipment is used.
Of the three operations where data were collected few control devices were used
and the exit flow rates ranged from 100 to 20,000 scfm (Table VII-1.1).
For modeling purposes a flow rate of 15,000 scfm should be used on plants
with abatement equipment and 1000 scfm on plants which have no control equipment.
GAS TEMPERATURE
Gas temperatures ranged from 82 to 185 F for the asphalt roofing plants
with control equipment and 180 - 270°F for those plants without control. An
average temperature of 110°F and 230°F should be used for plants with control
equipment and without control equipment, respectively.
VIJ-1
-------
GAS VELOCITY
Where no control equipment is used, molding process emissions were vented
through 20 - 28 inch stacks to the atmosphere with no auxiliary vent fan.
From the data collected, exit velocity was 4 fps. For three plants with control
equipment, velocities ranged from 36 to 68 fps with a mean of about 40 fps,
J3TACK HEIGHT
Stack height depended mainly on the building since the stacks are about
10 feet above the roof. For three plants without control) heights ranged
from 45 to 90 feet. A stack height of 60 feet should be as aimed when no data
are available.
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VII-3
VII-4
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CHAPTER VII-2
ASPHALT PLANT B
The 1968 production of asphaltic concrete totalled 14 million tons; it was
used for construction of state, county, interstate and municipal roadways,
parking lots, driveways, airports and playgrounds. Typical plant sizes are on
the order of 50 to 200 tons per hour. There are over 10,000 plants in the U.S.
some of which are mobile to allow relocation as construction sites change.
Manufacture of asphaltic concrete is simply a blending, drying and mixing
operation (Figure VII-2.1), For practical purposes, process feed rates are
matched one for one with the process output since moisture in the aggregate is
replaced, on a weight basis, by asphalt.
Asphalt plants run 8 hours per day, 5 or 6 days per week, from about 7:00 a.m.
to 3:00 p.m. The principal emissions are dust particles erainating from the drjer
kiln. Production of the fine surface mixes gives rise to the greatest dust enissions.
Control equipment always includes mechanical collectors for separating products from
the air scream. Scrubbers are very common, and occasionally baghouses are used to
2 4
minimize dust loading.
GAS FLOW RATE
The dryer kiln is either gas or oil fired. Suitable drying is attained when
the flow velocity through the kiln is between 200 and 400 fpm. Since the gas
effluent volume is determined by the type and size of drying kilns and the
collection systems used, some variation was found in the literature (.Figure VII-2.2).
For most plants in the 100 - 200 ton/hour capacity, exhaust flow rate was between
15 and 25,000 scfm (Table VII-2.1)?
GAS_TE MPE BAT URE
The temperature of exhaust gases for 4 plants was from 180 to 430 F vith a
mean of 225 F without control equipment. Use of a scrubber will reduce exit gas
temperatures to about 100 F.
GAS VELOCITY
No data were obtained, but stack diameters are typically 3 to 10 feet. There-
fore, an average of 10 fps should be used unless specific data are available.
VII-5
-------
STACK HEIGHI
Most asphalt plants have stacks over the drier exhaust,and the entire plant
is elevated so that trucks can load by gravity from the mixing pr storage bins.
Therefore, the stack heights will be 20 - 30 feet above ground.
TABLE VII-2.1
Exhaust Gases from Asphaltic Concrete Batch Plants'
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
Exhaust
Flow
1,000 scfin
23.1
19.8
26.2
25.7
18.2
18.0
16.1
19.5
7. 7
IS. 7
17.0
23.7
28.3
24.3
15.9
17.2
22.0
24.6
18.0
18.2
20.0
19.6
21.0
22.2
17.1
VII-7
VII-6
-------
8-IIA
8 1-
(D —
30 -
20 •
10 .
O
Exhaust Flow Rate = .053 x Production Rate + 12.6
(1,000 scfm) (tons/hr.)
50
100 • 150 200
Production Rate (tons/hr.)
250
Figure VII-2.2 Exhaust flow and production for asphaltic concrete batch
plants
VII-9
-------
CHAPTER VII-3
BRICKS AND RELATED CLAY PRODUCTS MANUFACTURING
There are about 520 manufacturers of brick plants in the U.S. Most
brick plants also produce other clay products like tile. Since clay is the
principle raw material used, and clay is rather abundant in all of the U.S.,
no geographic preference is found for location of these plants.
The manufacture of bricks is rather simple. Different kinds of clays are
ground, screened, mixed with water, extruded (pressed into shape) and dried
in tunnel kilns. Other types of kilns include beehive, scove and shuttle
kilns,but the tunnel kiln is the most popular. Typical size of a tunnel
kiln is 12 ft. wide by 10 ft. high and 800 to 900 feet long for the newer
kilns and 400 to 500 feet long for older tunnel kilns. The temperature in
the tunnel ranges from 1400°F to about 2200°F and varies with the structural
properties of the brick desired. The exhaust gases from the tunnel are used as
a drier for the fresh extruded brick before it enters the high temperature
tunnel. Typical plant capacity is about 100 million bricks per year. There
is no stack used at the end of a tunnel kiln to exhaust emissions at an
elevation. There is no particulate emission associated with the tunnel kilns
other than products of combustion which have been discussed in earlier chapters.
The fev beehive kilns still in use may use coal as a heat fuel which produces
a distinct plume. Seventy-five percent of the brick manufacturers use natural
gas as their heat source for the tunnel kiln. The remaining manufacturers
use coal or resid oil. The major air pollution enission sources are the
grinding, screening and mixing operations which emit dust. Most plants will
control emission with baghouses from the grinding, screening and mixing operations.
The building brick is made by mixing one or two clays with water (10 - 25
percent water and 75-90 percent clays). About one ton of clay will yield one
ton of finished brick. Operational time for these plants are usually 1 or 2
shifts per day and 5 days a week.
GAS FLOW RATE
The gas flow rates for those plants with control devices on the grinding,
screening and mixing operations will range from 5,000 tc 30,000 scfm depending
on the size of the area which is ventilated. This range is typical with other
VII-10
mir .Tal process catagories which utilize a crushing and screening operation.
For modeling purpose use 15,000 scfm for plants with control equipment when
specific fan data is not available.
The flow rate of the hot gases eminating from the tunnel kilns are low,
about 1500 scfm.
GAS TEMPERATURE
The gas temperature will be ambient for the grinding, screening, and
mixing operations.
For the tunnel exhaust the temperature will be near 200 F (no data were
available).
GAS VELOCITY
Based on data from similar processes, the gas exit velocity for brick
plants is estimated at 10 fps since baghouses will usually have a lowered
wall instead of a stack for emission points.
The flow rate from tunnel kilns is about 10 fps ar.d are not vented
through a stack.
STACK HEIGHT
Baghouses usually sit alongside a plant and have an effective stack height
of about 15 feet. Tunnel kilns also have a stack height of 15 feet.
vn-ii
-------
CHAPTER VII-4
CALCIUM CARBIDE PLANT C
Of the 1.15 million tons of calcium carbide produced in the U. s. in
1965, 70% was used in the preparation of acetylene and the remaining 307. to
prepare cyanamide. Calcium carbide is prepared by reacting quicklime (CaO)
and carbon (coke, anthracite or petroleum coke) in an electric furnace at
o 2200 C. The reaction proceeds according to the equation (Figure VII-4, 1) •
CaO + 3C + 111
VII-4. 1
In 195». there were 13 operating calcium carbide plants in the U.S.
Because of the availability of natural resources many plants are located in
northwestern Sew York. Most plants are equipped with continuous tapping
furnaces which keep the reactatits at the most efficient level in the reaction
chamber. The capacity range of these furnaces is 5,000 to 25,000 kw-hr which
producesup to 200 tons of carbide per day (Figure VII-4. 2). The plants run
continuously 3 shifts a day and 7 days a week. The major air contaminants are
dusts: CaO, MgO, Si02, Fe^ and C. Most plants control emission with a high
energy scrubber, baghouse or an electrostatic precipitatror.^
GAS FIO." HATE
Or.ly two plants were available for analysis of exhaust flow; the flow
rates vere 152,000 and 368,000 scfm (Table VII-4. 1) for a 40 ton per hour and
a 15 ton per hour plant respectively.3 No accurate conclusion can be drawn from
these few data. However, similar flow rates in excess of 100,000 scfm can be
expected from calcium carbide plants.
GAS TEMPERATURE
The gas exit temperatures for the plants were 135 and 153°F. Exit temper-
atures are not expected to vary much from 150°F.
GAS VELOCITY
The gas exit velocity was 30 and 75 fps for the two plants.
STACK HEIGHT
Stack heights for the two plants «ere 70 and 95 feet. If no data are
available use a height of 80 feet for calculations.
VII-12
O CU
01 S C
I s
•B 3
5 S
-------
3 i:
T - 1
50 100 150 200
Production Rate (tons/day)
250
Figure VII-4.1 Production Rate of CaC2 vs. Reactant Feed Rate
VII-1A
200
n
100
5 10 15 20 25
Furnace Capacity (1,000 kv,-hr.)
Figure VII-4.2 Production rates of CaC, in Electric Furnaces
VII-15
-------
CHAPTER VII-5
rf' CASTABLE REFRACTORY PLANT8
Refractories are used principally as heat shields in a variety of high
temperature furnace applications like melting glass, steel or nonferrous
metals, kilns and ceramic drying furnaces. Refractories are sold in the form
of fire brick; silicon, magnesite, chrcmite, silicon carbide and aluminum silicate
to name a few. Each type of refractory has unique properties which are applied
for specific furnace use.
Typical plant capacity ranges between 30 and 50 tons per day, and plants
are located in large metropolitan industrial areas of the country. Since the
manufacturing operation is simply a drying and pressing operation, the input
rate is the same as output rate.3 Most plants use gas or oil fired tunnel kilns
to dry the ceramic raw materials. The major ait contaminant is dust especially
from the dryer and processing (transport) operations. Baghouses, scrubbers
and cyclones are used as abatement equipment. Refractory plants operate 5 days/
week and 2 shifts per day.
GAS FLOW RATE
Exhaust flow rates from castable refractory plants ranged from 1,000 to
14,000 scfin for several driers. All driers had control equipment in use.
Plant flow rates are consistent with other kiln drier applications. An average
flow rate of 7,500 scfm should be used when no specific fan data are available
(Table VII-5.1).
GAS TEMPERATURE
Exhaust gas temperatures from the drier ranged from 200 - I,000°F with a
0
mean of about 500 F. Exhaust gases from screening and crushing operation
would be near ambient temperatures.
GAS VELOCITY
Exhaust gas velocities ranged from 7 to 76 fps with a mean of 35 fps.
STACK EEICHt
Table VII-5.1 shows stack heights for several castable refractory plants.
They range fr«B> 15 to 60 feet with an average of near 30 ft. For modeling
purposes a stack height of 30 feet should be assumed.
VII-16
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VII-19
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-------
CHAPTER VII-6
dry process.
CEMENT PLAHT
B
There are about 200 cement plants in the U. S. which make 500 million
pounds of cement annually. Cement, of course, is the basic raw material for
concrete, which is utilized in most every form of large construction of roads,
buildings, bridges, etc. Cement plants are scattered throughout the U. S.
since their basic material is the abundant limestone and other hard rock.
Portland cement is manufactured either by the dry or wet process, in
large calcining kilns which are several hundred feet in length. The trend
today is toward kilns over 400 feet in length which means increased throughput
rates. To produce one barrel of cement weighing 376 pounds, approximately 600
pounds of raw materials (not including fuel) are required (Tables VII-6.1 and
VII-6.2 and Figure VII-6.1).
Particulate matter is the primary emission from the manufacture of Port-
land ceaent (Figure VII-6.2). Most of the particulate is emitted from the
rotary calcining kilns. Fuel requirements to generate heat for the kilns are
about 1.2 million BTU/bbl. for those plants built prior to 1963. Newer plants
require about 0.9 million BTU/bbl. Fossil fuels commonly used include coal,
oil and natural gas. Short dry process kilns with vertical suspension pre-
heaters utilize 540,000 to 640,000 BTU/barrel, and grate preheater process
g
kilns utilize approximately 600,000 BTU/barrel. Although the wet-process
kiln has a higher heat requirement than the dry-process kiln, the fuel con-
sumption difference, in many cases, is partially offset by the heat consumed
in the dryers preceeding the dry process kiln, whenever they are used. When
preheaters are not used, the wet process requires more heat to drive off the
30 to 40 percent water in the slurry.
Most plants have some air pollution control equipment associated with
the kiln emission source. Baghouses and/or mechanical collectors are commonly
g
used to control dusts.
GAS FLOW RATE
The exhaust gas flow rate from kilns follows a close relationship from
plant to plant despite various configurations of the drying kilns (Figure VII-6.3
and Figure VII-6.4). The exhaust flow rate is about 0.75 scfm for each Ib./hr.
of cement produced by the wet process and 0.6 scfm for each Ib./hr. for the
GAS TEMPERATORE
The range of exhaust temperatures from 22 wet process plants was 285 to
750°F with a mean of 425°F. For 11 dry process plants the temperatures ranged
from 375 to 845°F with a mean of 555 F. For calculations assume 400 F for
wet process plants and 550 F for dry process plants.
G-AS^ VELOCITY
No data were available, but gas exit velocity for these plants is expected
to be between 20 and 60 fps with a mean of 40 f ps .
STACK HEIGHT:
No data were available, but cement plants have a single large concrete
stack extending 100 to 300 feet high. Assume 200 feet when data are not
available.
VII-20
VII-21
-------
TABLE VII-6.1
o
Exhaust Gasses from Wet Process Cement Manufacturing Plants
TABLE VII-6.2
Production Rate Process Weight Exhaust Gas Exhaust Gas
Volume Temperature
1000 bbl./da. 1000 Ib./hr. 1000 scfm "F
19.44 486 371 450
10.56 264 205 550
8.88 222 217 750
9.192 230 144 385
3.98 99.5 98 363
5.0 125 129 290
4.5 112.5 97 320
2.2 55 51 550
7.5 187.5 285 350
5.6 140 176 355
2.5 62.5 87 385
1.9 47.5 54 450
3.475 86.9 109 330
3.9 - 97.5 59 285
7.1 177.5 148 343
6.25 156 109 525
7.6 190 253 460
6.86 171.5 211 450
3.6 90 79 547
2.8 70 133 352
8.3 208 170 390
11.4 285 230 500
Q
Exhaust Gases from Dry Process Cement Manufacturing Plants
Production Rate Process Weight Exhaust Gas Exhaust Gas
Volume Temperature
1000 bbl./da. 1000 Ib./hr. 1000 scfm °F
9.216 230 152 700
4.0 100 30 375
1.88 47 22 500
5.26 132 109 500
9.58 240 161 510
3.8 95 131 467
1.67 42 57 497
3.3 82 66 550
0.5 12 16 845
2.9 ~2 . 60 (>00
2.75 69 64 560
VII-22
VII-23
-------
i
Process weight * 25.0 x Production rate
(1,000 Ib./hr.) (1,000 bbls./day)
200.
100
25
Production Rate (1,000 bbls./day)
Figure VI1-6.1 Process weights used in wet and dry cement manufacturing
VII-24
-------
o
go -
R=.862
200 -
100 •
:o
Exhaust flow rate
(1,000 scfnt)
0.710 x process weight + 40.2
(1,000 Ib./hr.)
100 200 300 WO 500
Process Welqht (1.000 Ib./hr.)
Figure VII-6.3 Exhaust flow vs. process weight for wet process cement
manufacturing
VII-26
150-
100
50
R.=869
Exhaust flow rate = 0.612 x Process weiaht + 16.5
(1,000 scfm) (1,000 Ib./hr.)
0
50 TOO 150 200 250
Process Weiaht (1,000 Ib./hr.)
Figure VI1-6.4 Exhaust flow vs. process weight for dry process cement
manufacturina
VII-27
-------
62-IIA
CHAPTER VII-7
CERAMIC CLAY PLANT
In nearly all clays used by the ceramic industry, the basic mineral
02-
is kaolinite (A1203'2S102-2H20) . Clays have the special property of plasticity
or workability which make its use as a raw material applicable to the manufacture
of glassware, pottery, china, porcelain, stoneware, and vitreous ware. By
adding raw materials like borax, iron oxides, calcined bones and pearl ash
special refractory properties can be obtained.10 Typical plant capabilities
vary widely — from 50 to 5,000 Ib./hr.
$The manufacture of ceramic products involves conditioning basic raw
materials, mixing or blending and forming. Drying and mixing operations
generate most of the dust pollutants. Settling chambers, cyclones, wet
scrubbers, and electrostatic precipitators are the main abatement devices,
when used. However, most plants have no controls for pollutants. Operating
times are 1 or 2 shifts/day and 5 days per week.
GAS FLOW RATE
Exhaust gas flow rate is determined by the collection system used and
specifically by fan size. Typical exhaust flow systems range from 500 to
5,000 scfin for 10 ton/day plants (Table VII-7. 1)? When fan size is not
available 4,000 scfm should be assumed.
GAS TEMPERATURE
Except for the drier exhaust, temperatures will be essentially ambient.
The drier exhaust temperature ranged from 130 to 420 F.
GAS VELOCITY
Gas exit velocity values ranged from 18 to 80 fps with a mean of
near 50 fps.
STACK HEIGHT
From the data collected all stacks heights were less than 50 feet.
For modeling purposes use an average stack of 30 feet.
§
o
X
SET
..
s--
o w
-> ox
•n 3 it
S
VII-28
-------
I
•H
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C
8
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VII-31
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<§•
VII-30
-------
CHAPTER VII-8
Clay and Fly Ash'Sintering Plants
There are less than 5 fly ash sintering plants in the U. S. which operate
full scale and on a continuous basis with a throughput rate of about 200 tons/
hour. The basic raw material is fly ash from coal fired power plants. The
fly ash is first pelletized into spherical bodies then placed on a traveling
srate (8 ft. wide and 98 ft. long) where the fly ash balls are fused together.
All units are fired with natural gas at a bed temperature of 1900 - 2300°F.
Fly ash products are, at present, limited to use as an aggregrate in
structural concrete or building blocks. A small amount of all fly ash
produced from coal combustion goes through a sintering process. Full scale
operating plants are located in Anodazo, N.Y., Pittsburgh, Pa., and Detroit,
Mich. All three of these plants use control equipment (precipitator or
baghouse) because of a high fine particulate emission. No information was
available on natural gas usage at these installations. Plants operate
11 12
continuously 24 hours per day and 7 days a week. '
No information about clay plants was obtained, but one source indicated
that there is little difference between clay and fly ash sintering plants.**
GAS FLOW RATE
Specific fan sizes from these three installations were not known but were
estimated at about 10,000 to 20,000 scfm. The product sizing is controlled
(with the use of dampers) by the amount of over fire air passing through the
steel belt.
GAS TEMPERATURE
The gas temperature at the stack exit point was estimated at 450°F for
the sintering plants.
GAS VELOCITY
No information was secured concerning exit velocities, however,. 20-40 fps
is expected. For modeling purpose use an exit rate of 30 fps.
STACK HEIGHT
The stack height* for the three unit* were estimated at 150-200 feet.
VII-32
CHAPTER VII-9
CONCRETE BATCHING PLANT C
Concrete batching plants store, convey, measure and discharge the
ingredients for making concrete to mixing or transportation equipment.
Concrete is used in a vast number of construction applications like highways,
office buildings, water dams, bridges and foundations. Concrete plants are
located throughout the U. S.; the Washington, D.C. area alone has over 200
concrete contractors.
There are basically two kinds of concrete batch plants, wet and dry
batching. Both will be analyzed together even though wet plants will not emit
as cuch dust as the dry batching plants. The major pollutant is dust which is
generated during unloading of cement, gravel and sand, transport and filling
operations. The recommended air pollution abatement equipment is the baghouse;
however, most plants do not have any control devices. Typical operating times
are 3 hours per day and 5 days per week. Figure XII-9.1 is a sketch of the plant.
GA5 now RATE
Exhaust gas flow rate (from plants which have control devices) is
entirely dependent on the system configuration and fan size. The recommended
collection rate is 6000-7000 scfm. From the data collected the exhaust flow
ranged from 250 - 5000 scfm. For calculation purposes use an average of
5000 scfe for all plants with control and 300 scfm for plants with no control
equipment (Table VII-9.1).
C-AS TEMPERATURE
Exhaust gas temperature will be ambient since there is no combustion
associated with this process.
GAS VELOCITY
The gas velocities are low because few plants control dust. The exit
velocity for these plants with no control equipment will, by natural convection,
be 3 to 10 fps. Those plants which control dusts have an exit velocity of
about 15 to 30 fps.
VII-33
-------
SC-HA
STACK HEIGHT
Stack heights ranged from 26 to 50 feet with a mean of about 35 feet.
For modeling purposes th$.s process should be treated as an area source.
o- •
rt O*
1 g
§
£ n
&§
VII-34
-------
. , 1 1
"l 1
1 I
i iC'
Sand" | Cement ( Rock
1 1
1 i
Weigh Hoppers
Gathering Hopper
Mixing and/or Transportation Equipment
Figure VII-9.1 Flow diagram of a concrete batching plant
VII-36
CHAPTER VII-10
FIBER GLASS PLANT
B
About 50 percent of the manufactured fiber glass is used for thermal and
acoustical insulation and about 35 percent is used for textiles. The basic
ingredients for continuous filament fiber include silicon dioxide, calcium
oxide, aluminum oxide, and boric oxide. Increasing widespread uses continue to
cake the demand favorable. Glass marbles are melted then extruded through
scall holes (forming operation) making a filament. The filament travels through
a coring oven before it is packed. Plant size is determined by the number of
lines or forming and curing machines. Since the raw materials for the process
are or.ly changed in form, one pound of ingredients will yield one pound of
glass fiber material. Special properties like strength, elongation and dur-
ability are controlled by the addition of various basic ingredients. The
:za;or air pollutants from fiber glass manufacture are glass fiber particulates
ar.c pher.ol resins. Cyclones and fume incinerators are the common types of air
pcllutior. abatement equipment.
Exhaust gas flow rate, as well as other pertinent data.are listed in
Table VII-10. 1. Some plants only indicated data from one phase of the operation.
The tvo critical phases are forming and curing operation. Figure VII-10. 1
displays exhaust flow rate as a function of process weight for both operations.
The figure indicates that flow rate is dependent on the individual configuration
used and not on the process weight. All plants used some form of air pollution
control equipment.
CAS rEXPEHAUTiE
Exhaust gas temperatures ranged from 200 - 250 F for the curing operation.
The forcing operation temperature ranged from 70 - 160°F. For modeling, use
200 ' for both curing and forming operations.
GAS VELOCITY
Stack gas velocities ranged from 5-41 fps for all operations of the
fiber glass plant. The average velocity for the 7 plants was about 40 fps.
VII-37
-------
STACK HEIGHT
The stack heights reported for three plant4%anSed
For modeling use a stack height of 60 feet.
30 * 71 feet.
m
VII-38
F 5 1
00
S."1?1 i te*sa *< 1W 3"
<< v CT« >-* K!
0)1*0^0 OU100 W> <" « "•
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ss§5 III is si
x- w w
£??? sSSg^ S =
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}? f. !? f !? !|
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Step
§!
rr
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-If
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n
f operating
Time
Control
Kqulpnent
-------
60.
50 -
40 .
20
io
o
©
o
100
500
200 300 400
Input Rate (1,000 Ib./hr.)
Fiaure VII-10.1 Exhaust flow vs. input rates for various fiber qlass plants
vn-40
CHAPTER VII-11
GYPSUM PLANT8
Gypsum (CaS04.2H2Cn is a mineral that occurs in large deposits throughout
the world. Calcination of gypsum is performed In large kilns (10-25 tons) at
temperatures up to 190°C. Between 120 and 150°C, first settle plaster la
formed which is mixed with sand or wood pulp and sold as gypsum plaster. Heating
to 190 C forms second settle plaster (CaSO^) which is used in the manufacture of
gypsum products such as plasterboard. A common gypsum plant capacity is about
500 tons/day and plants are located in almost every state. Plants operate Hks
other mineral products industries, about 16 hours/day and 5 days a week.
Operational times, of course, depend on product demand. When more material is
needed, longer work hours are ordered.
The cajor air pollutant is fine particulates from the drying kiln.
However, other particulate emission sources include the crushing, screening,
and transport system. All of the plants will use some form of a pollution
abatement device such as scrubbers (the most common), baghouses or cyclones.
GAS FLOW RATE
Exhaust gas flov ranged from 40,000 to 48,000 scfm (from the drier) for
plants with a capacity of 500 tons/day. of the three plants for which relevant
data were obtained, two had control systems for crushing, grinding, or screening
operations. The data are presented in Table VII-11.1.
GAS TOgERAILTtE
Exit temperatures of flue gas from the drier were 129°F and 220°F for
the two plaats. Temperatures from the other processes wert mainly ambient
but reached a high of 146°F. When data are not available, use 150°F.
GAS VELOCITY
Gas velocity from various operations was relatively constant at 50 - 65
fps. When data are not available assume 50 fps.
STACK HEIGHT
Stack heights ranged from 45 - 106 ft. For modeling purposes 75 feet
is recommended.
VII-4L
-------
ZV-IIA
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CHAPTER VII-12
LIME PLANT0
The annual production rate of lime products in 1964 was over 500 million
tons produced from over 100 plants scattered throughout the country. Typical
plant sizes range from 50 to 650 tpd. About 60 percent of the quarried lime-
stone is used for concrete agregate; 20 percent is used for cement manufacture;
and the remaining 20 percent is used for soil additives, chemical and metal-
lurgical industry constituents, sugar production, pulp and paper production
and reagents for the treatment of both water and air pollution.
Raw material used in lime production is the abundant hard rock-limestone
(CaCO •"• some impurities). Lime manufacturing plants will vary in the
relative eopfcasis given to potential products, whether the product is used
for comercial sale or captive use and the type of kiln used (verticle, rotary,
open). The manufacturing process includes obtaining the rock, crushing,
scree-.inz and burning the crushed rock in large kilns (calcination) to produce
calcic oxide. The product may then be packaged for sale or conveyed to a
lice '-.ydrator to produce slaked lime (calcium hydroxide' vhich is then sized
ar.d racked ir. 50-lb. paper bags for distribution. (Figure '. 11-12. !'• The
reaccicss involved in these processes are:
Calcining:
Hvarating-
CaCO.
-»• CaO -I- CO
CaO * H.O •
2
Ca(OH)0
Plants iS-allv operate continuously 24 hours a day for 6 or ~ days a week.
The tza'or air pollution problem from lime production is particulate
ecissior.s free che kiln drier. Other emission points include the
crushing and screening operations, transport corridors and final packaging.
Xost plar.ts '--ill use primary collectors (mainly cyclones' as air pollution con-
trol aevices for kiln emissions. Vertical kilns have a low capacity (7-15 tpd)
and are a=out 10-24 feet in diameter and 35-75 feet in height. Vertical kilns
used by the alkali and sugar industry are sealed because of the need for CO.,
ar.d present no air pollution problem. Coal fired and gas fired open kilns do
present an air pollution problem but are of small capacity and are becoming
obsolete.
Rotary kil-s have capacities which exceed 500 tpd. Typical rotary lime
kilns vary ia size from 6 to 11-1/2 feet in diameLer and from 60-400 feet
in length though 150 feet is a common length. Various fuel/lime ratios are
presented in Table VII-12.1 to show process weights and exhaust flow.
About 60 percent of the line kilns used evaluated pulverized coal; 28
percent used natural gas; 6 percent used oil and the remainder used combinations
-------
of fuels. Figure VII-12.2 shows the heat input requirements for various
size plants, using rotary kilns and a fuel lime ratio of 1.0:3.37.
GAS FLOW RATE
Gas volumes from 7 kilns ranged from 19,000 - 62,000 scfm after the
collector with a mean value of 40,000 scfm. (Table VII-12.2).
GAS TEMPERATURE
- Q
Exhaust gas temperatures ranged from 350 to 522 F with a mean of about
450°F before the collector system. The temperature drop across the collector
system was about 150 F. The exit temperature after the scrubber was about 170°F.
GAS VELOCITY
The gas exit velocity ranged from 25 to 58 feet. For modeling use 35 f ps.
STACK HEIGHT
The stack heights were 250 and 400 feet. For modeling use 300 feet.
Fuel/lime ratio
1/1.4
1'2.0
1/3.0
1/4.0
1/5.0
1/6.0
TABLE VII-12.1 6
Process Weights for Pulverized
Bituminous Coal Fired Rotary Kilns
Exhaust Gas Flow
_cf/ton of lime
203,500
146,200
101,500
79,200
66,100
57,000
(a) Bituminous coal with 13,500 BTU/lb.
VII-44
VI1-45
-------
9V-HA
I— PO < U)
s § s.s
Pi
, rr rt
. ft rr
•3.
88
300
_ 203 .
100
200
300
400
500
,£ n
c o
•
Plant Capacity (tons of lime/day)
Figure VII-12.2 Heat Input for Lime Kiln
VII-47
-------
8<7-IIA
CHAPTER VII-13
PERLHE PLANT8
Perlite is a glassy, volcanic rock arranged by nature Into small spherical
bodies. Chemically, perlite consists of silicon and aluminum combined as natural
glass with water of hydration. When the perlite is heated, the water escapes
causing the spheres to expand and form a low desnity material (2-15 Ib./ft.^).
About 90 percent of all manufactured expanded perlite is used as an
aggregate in plaster and concrete. Perlite ore deposits are mainly located
in California and six other Rocky Mountain States, however expansion plants are
located throughout the U. S. A plant for the expansion of perlite consists
of a receiving and feeding device, an expansion furnace, a product classification
system anda packing line (Figure VIII-13.1). Vertical furnaces, horizontal
furnaces and horizontal rotary furnaces may be used to expand perlite ore.
Essentially all perlite furnaces, are fired with natural gas. The natural gas
rate, amount of excess air and ore feed rate are governed to provide a furnace
temperature, gas flow rate and naterial residence time vhich will yield a product
of the desired density. Perlite plants usually operate continuously 20 hr./day
and 5 days per week.
The major air pollutant is fine expanded perlite particles suspended in
the flue gas which escape the controls. Most plants use control devices such
as cyclones; some use baghouses. If ore cyclone is not sufficient to abate
the dust, two or more are ccoaonly used in series for control. The furnace
temperatures range from 1450 to 1300°F,but flue gases are cooled (to protect
controll equipment) to about 200-250 F. Dilution air is commonly employed
to reduce flue gas temperatures.
GAS FLOW RATE
Exhaust gas flow rates from perlite plants are governed by the furnace
design and control system configuration more than production rate and are
quite similar from plant to plant (Table VII-13.1). Flow rates from 4 plants
ranged from 3500 scftn to 6400 scfm with an average near SOOO scfm for a
2000 Ib./hr. plant.
VI1-49
-------
GAS TEMPERATURE
Exhaust gas temperatures from the limited amount of data ranged from
near ambient to 360 F with a mean of near 210 F. Use 200 F when data are
not available.
GAS VELOCITY
Gas exit velocity ranged from 30 to 50 fps for four data points with an
average of 40 fps. Stack diameters of about 3 feet are common.
STACK HEIGHT
One plant had its control unit mounted on the ground and had a stack
height of only 17 feet. Other stack heights ranged from 49 to 55 feet.
Fifty feet should be used for modeling purposes.
VII-50
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-------
CHAPTER VII-14
MINERAL WOOL PLANT A
The general product classification known as mineral wool was formerly
divided into three catagories: slag wool, rock wool, and glass wool. Today
slag wool and rock wool are no longer manufactured separately. Instead, a
combined product made of slag wool and rock wool is called mineral wool.
Mineral wool is manufactured by a molten process in a cupola using blast
furnace slag, silicon rock and coke (Figure VII-14.1). It is used mainly for
domestic insulation ia residential homes. Plants tend to be located near a
source of slag such as a steel plant. Mineral wool plants operate 24 hours
per day and 5 days a week. The major source of pollution is the cupola.
Air contaminants are particulates, sulfur oxides and organic mists from
the binder. Typical plant capacity is about 50 tpd. Essentially all raw
materials are converted to mineral wool; therefore, no input-output curve
is offered. Common control devices include baghouses, cyclones, scrubbers
and afterburners. Most plants will use as minimum either a baghouse, cyclone
or scrubber to abate particulate enissions.
GAS FLOW RATE
Exhaust gas flow rate for the cupola ranged from 4,510 scfm to 4,760 scfm
for about a 4,000 Ib./hr. cupola? One author recommends exhaust requirements
of 5,000 to 7,000 sera for the same size unit? Exhaust gas data are displayed
for 25 tests (some made on the same line) on the cupola, reverberatory furnace,
blow chambers, curing ovens, coolers and conveyor system (Figure VII-14.2).
The blow chamber cools molten material into fibers by sucking air through
a belt which transports the molten product. A recommended minimum ventilation
of 20,000 scfm for a 4,000 Ib./hr. process has been suggested. The range for
observed data was 11,000 to 28,000 scfm (Table VII-14.1).
Stack gas flow rate from curing ovens ranged from 1,642 to 8,000 scfm with
a mean of about 5,000 scfm.
Exhaust flow from the coolers ranged from 1,860 to 16,000 scfm with a mean
of about 9,000 scfm.
VII-53
-------
GAS TEMPERATURE
Table VII-14.1 indicates data on temperatures found for each phase of
mineral wool manufacture. The cupola exhaust temperature averaged about
310°F (after the control device); blow chambers are kept at 200°F for
process conditions, thus the exit gas temperature averaged about 190°F,
The curing oven temperatures averaged about 300°F while the mineral wool
cooler exhaust averaged about 200°F. Where specific data are unavailable,
250°F should be assumed.
GAS VELOCITY
Gas velocity on one plant which had 3 cupolas ranged from 10 to 40 fps.
A mean of about 25 fps may be assumed.
STACK HEIGHT
The stack heights were all below 65 feet as can be seen from Table VII-14.1.
Tor modeling purpose use 50 feet.
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VII-54
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V1I-57
-------
30 -
20
10
©
G
e
o
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3000
4000 5000
Input Rate (Ib./hr.)
Figure VI1-14.2 Exhaust flow vs. input rates from various mineral wool plants
VII-58
CHAPTER VII-15
ROCK, GRAVEL AND SAND PLANT0
Rock, gravel and sand are all fundamental elements of the construction
industry. The baste material associated with this category is hard
rock. It is abundant nearly everywhere and plants are scattered throughout
the L'.S. catering to most all construction needs. Typical plant capacities
average about 100 tph.
Dust is the only air pollution problem associated with rock, gravel and
sar-.c processing plants (Figure VII-15.1). Major emissions arise from the
rertiory crushing and screening operations. Control equipment is generally
a baghouse although cyclones, scrubber or water sprays have some application.
Stone crushing operations give rise to more dust problems than do sand
ar.c gravel operations. >!ost of the sand and gravel operations are wet pro-
cesses taking place in a stream bed. Huge stones from quarries, after being
crushed cany tices, provide all dry surfaces and large quantities of fines
vh-cr. are easily entrained by wind movement.
A tor. of raw rock obviously will yeild a ton of crushed stone. The
plar.ts usually operate 5 or 6 days a week and 8 hours per day. Vagrant or
f-siiive dust nay be very important during dry weather or when truck traffic
is heavy or fast.
CAS ?-CH>' HATE
Many rock, gravel and sand plants have no air pollution control devices
to a'sata the dust caused by the crushing, screening and transporting operations.
tr.e dust becoces suspended in the air wlfh little plume rise, but is carried
vertically by ordinary convection currents. For this reason, those rock
acd gravel plants which have no air pollution control equipment should be
treated as an area source instead of a point source. Thus,by knowing the
particulate emission factor, Ib./ton of rock.and the plant production rate
ir. tons per hour, the time emission factor can be determined.
For those plants which do enclose processing operations to control dust,
the flow rates will depend on the type system utilized. Almost every system
is unique to the plant, some controlling all operations and some controlling
only the crushing operation. Table VII-15.1 provides seme guidance on the kind
VII-59
-------
of system and exhaust flow from two installations. Exhaust flow ranged from
500 - 750 scfm per ton/hr. of aggregate produced.
GAS TEMPERATURE
Exhaust gas temperature for rock and gravel plants, for all practical
purposes, is ambient conditions. Therefore, 60°F should be assumed unless
specific data indicate otherwise.
GAS VELOCITY
Those plants having control equipment will have an exit velocity of near
30 fps. A low stack velocity, 5 fps, is suggested for use with dispersion
equations.
STACK HEIGHT
Where no control equipment is utilized, except perhaps water sprays on
the crushers, dust emissions vill be generated at elevations ranging from
ground level to about 50 feet maximum. Even if baghouses are used, stack
height will not exceed 50 feet. Therefore,since most screens, crushers, and
conveyors are elevated at least 20 to 40 feet, 30 feet is suggested for
modeling purposes.
VII-60
Plant size
Tr.put rate
toiM/'hr.
40 - 45
65
LOO
TABLE VII-15.1
Exhaust Gases From Rock Crushing Operations15
Exhaust Flow
1000 scfm
23.7
46.6
5.1
Wet Scrubber
Wet Scrubber
Crusher only
VII-61
-------
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CHAPTER VII-16
GLASS MANUFACTURING PLANT E
Soda-lime glass represents by far the largest tonnage of glass made
today and serves for the manufacture of containers of all kinds, flat glass,
auto glass, tumblers, and tableware. Soda-lime glass is produced on a mass
scale in large direct fired continuous melting furnaces. Plant capacities
range fron a few pounds to several tons per day. The basic raw materials
for soda glass include: silica sand, cullet, soda ash, limestone, niter,
salt cake, arsenic, and a decolorizer. The raw materials are brought to
the plant on railroad cars and unloaded into storage bins. The materials
are withdrawn from the storage bins, batch weighed and blended in a mixer.
The mixed batchs are fed continuously to the furnace and brought to a
molten state 2,700°F. The glass is drawn from the furnace and then passed
through a forming machine, which either presses, blows, rolls, draws or
casts the molten glass to its final shape.
The furnace is usually natural gas fired and is not a major source of
air pollution. Grease and oils are used to lubricate the glass forming machine
which is the source of significant smoking. Often the molten glass is sprsyed
after forming vith annealing reagents to provide specific strength properties.
The poll..£ar.t -foe this arr.ealir.g process is usually of a Cl~ structure like
HC1 gas or Sr.Ci^. The annealing furnace is either electric heated or gas fired
and presents no air pollution problem. Very few plants will have any control
devices for any of the operations associated with the glass in the molten state.
Soae plants use cyclones and baghouses to handle the fine dusts eminating from
the raw material transport operations. Glass manufacturing plants operate
continuously, 24 hours per day.
Gas Flow Rates
The collection system for controlling dusts from the raw material transport
operations is the only sizeable exhaust flow from the air polluting sources at
the glass plants. The exacC flow rate will depend on the size of the fans but
flow rates are expected to be less than 10,000 scfm. No data were available
for this specific source.
The flow rate from the lubricatine grease smoke (forming machine) and
the annealing operations at one plant was 1200 scfm, driven by natural convection
up a small stack.
-------
Gas Temperature
The exhaust gas temperatures from the air pollution sources sited above
are mainly ambient. For calculation purposes, assume 100°F.
Gas Velocity
The exit velocity for these control units associated with the transport
dust would be about 25 fps.
The exit velocity for the annealing and forming machines are due to
natural convection; assume 2 fps.
Stack Height
No data vere available but stack heights will not be higher than the
plant buildings. For calculation purposes, use 60 ft.
VII-64
CHAPTER VII-17
FRIT MANUFACTURING0
Frit is a ceramic base product which is mainly used (when combined with
a large portion of fluxes) as porcelain enamel coating for bathtubs, sinks,
latrines, and household cooking pots. The preparation of frit is similar to
the first steps of the manufacture of ordinary glass. The raw materials are
mixed in proper proportions and charged to a melting furnace. Frit smelting
is a batch operation and has varying melt times, however 3 hours is typical.
The molten materials are then poured into a quenching tank of cold water,
shattering the melt into friable pieces. The frit is further ground with a
ball mill, mixed with a variety of fluxes and sprayed on as a surface coating
of specific products.
The major source of air pollution in a frit manufacturing plant is the
frit smelter. The principal air contaminants are dusts (metalic fumes and
fluorides'* and hydrogen fluoride gas Most plants will control emissions
from this source by using a baghouse or a high energy (venturi) scrubber.
Frit manufacturing plants operate continuously, 24 hours/per day and
seven days a week.
Gas Flow Rate
Data were collected from several frit shelters and tabulated in Table
VII-17.2. The flow rates were all less th a 5000 scfta. Figure VII-17.1 is
a plot of the data in Table VII-17.1.
Gas Temperature
The gas exit temperature for frit plants ranged from 340 to 960°F with
a mean of about 600°F (Table VII-17.I). Several tests were made after the
control device, however this data was not reported. The temperature is
expected to drop about IOO°F across a venturi scrubber and about 20°F across
a baghouse.
Gas Velocity
The gas exit velocity was not available for the data in Table VII-17.1.
The exit velocity is expected to be between 20 and 50 fps. Assume 40 fps for
calculation purposes.
VII-65
-------
Stacfcjte_lght
Baghouses do not usually have a stack, per se. Often a louvered wall
acts as the emission point and is usually located at ground level. Venturi
scrubbers will have a stack height of about 40 feet.
TABLE VII-17.1
Exhaust Gases from Frit Manufacturing
Production
Rate
.._ Ib./hr. _
17ft
174
472
472
472
292
472
472
472
174
174
162
162
857
857
890
890
1360
1360
1360
1360
1360
1360
1390
1540
1630
1310
1400
1480
2240
2270
2260
1400
1600
1000
1000
2430
2430
4347
4347
4280
4280
4280
4280
4280
4280
Exhaust
Tgmp.
450
750
900
960
950
930
630
800
840
530
340
480
480
600
600
340
340
570
552
564
570
552
564
VII-66
VII-67
-------
CHAPTER VII REFERENCES
Q
R=.929
G
Exhaust Flow Rate * 2.62 x Production Rate + 800
(1.000 scfin) (Ib./hr.)
O
O
O
250
1250
500 700 1000
Frit Production Rate (Ib./hr.)
Figure VII-17.1 Exhaust flow rates for various frit production rates.
1. "Shipments of Asphalt in 1968", Mineral Industries Surveys, U.S. Dept.
of Interior, Bureau of Mines, Washington, D.C., June 17, 1969.
2. "Air Pollution Engineering Manual", U.S. Dept. of Health, Education
and Welfare, Public Health Service, Publication No. 999-AP-40, 1967.
3. State Air Pollution Permit Data, June, 1971.
4. Fuedrich, H.E., "Air Pollution Control Practices, Hot-Mix Asphalt
Paving Batch Plants", Journal of the Air Pollution Control Association,
Vol. 19, No. 12, December 1969.
5. Private ccnmunication with industry, August, 1971.
6. "Dust Emission Control in Calcium Carbide Production", translated from
the German by NAPCA, U.S. Dept. of Health, Education and Welfare, Public
Health Service, Washington, B.C., December 1965.
7. Kreichelt, T.E., Kemnitz, D.A. and Cuffe, S.T., "Atmospheric Emissions
from the Manufacture of Portland Cement", U.S. Dept. of Health, Education,
and Welfare, Public Health Service, Cincinnati, Ohio, 1967.
8. Vincent, E., Private Communication, Bureau of Abatement and Control,
NAPCO, November 1969.
9. Omara, Richard F. and Flodin, Carl R., "Filter and Filter Media for the
Cement Industry", Journal of the Air Pollution Control Assoc., Vol. 9,
No. 2, August 1959.
10. Shreve, R. Morris, Chemical Industry Processes. McGrav Hill Publishing Co.,
New York, N.Y., 1967.
11. Private Conraunlcation with U.S. Bureau of Mines, Morgan town, W. Va.,
August, 1971.
12. "Informative Air Pollution Problems in Fly Ash Sintering Plant",
Journal of the Air Pollution Control Association. Vol. 15, No. 3,
March, 1965.
13. "Venturi Scrubber Lime Test Report", Zurn Air Systems, Birmingham, Ala.
14. Minnick, L. John, "Control of Particulate Emissions from Lime Plants -
A Survey", Journal of the Air Pollution Control Assoc., Vol. 21, No. 4,
April, 1971.
15. Cross, Frank L. and Ross, Roger W., "Field Control of a Dolomite Plant",
Journal of the Air Pollution Control Assoc.. Vol. 18, No. 1, January, 1968.
16. Unpublished data. Zurn Environmental Engineers.
VII-68
-------
CHAPTER VIII-1
PETROLEUM REFINERY B
In 1969 the total daily demand for petroleum products in the U.S. was
12 million barrels. Although the demand for petroleum products is growing
at a rate of about 4 percent per year, the 263 operating U.S. petroleum
refineries (Table VIII-1.1) are able to supply nearly all of the reftned
petroleum products needed to meet domestic requirements for transportation,
heating, electric power generation and industrial uses. Each of these
operations has its particular fuel need which is obtained by different methods
of refining crude oil at a petroleum refinery. These plants are usually
located near oil producing fields or harbors and serve as storage and dis-
tribution points for particular refining districts.
Refinery operations can be considered in terms of four major kinds of
functions: separation, conversion, treating, and blending. Crude oil is
first separated into selected fractions by distillation. The relative
volume of each fraction produced depends on the type of crude oil. Conver-
sion of a specific distilled fraction to products of greater value is accom-
plished by cracking and reforming. The products from the separation and con-
version steps are then treated, usually by the removal or inhibition of gum
forming materials. As a final step, the refined base stocks are blended with
each other and with additives to meet product specifications.
Separation
Crude oil is a mixture of many different hydrocarbons, some of them
combined with small amounts of impurities. Crude oil usually consists of
three families of hydrocarbons: paraffins (C.H. _),naphthenes (C-H. ),and
aromatics (C,H, in molecular structures). Significant elements other
o b
than carbon and hydrogen in the crude include sulfur, oxygen and nitrogen.
Primary separation is accomplised by distillation in crude topping
units where the crude is heated and passed to fractionating tower* for
vaporization and separation (Figure VIII-1.1). Heavy fractions of the
crude which do not vaporise in the topping operation will be separated by
vacuum distillation.
The bottoms from the atmospheric tower go to the vacuum tower for further
separation. Since cracking and coke formation occur at temperatures in excesi
VIII-1
-------
of 800°F, this Cover must be operated at a vacuum to recover, as overhead,
materials boiling in excess of 800°F. The overhead from the crude is
a fuel feed. The bottoms from these towers are high sulfur residual fuel oil.
Conversion
Conversion by cracking is employed to convert high molecular-weight
hydrocarbons into products of lower molecular weights for gasoline production
which is done with the use of catalytic cracking, reforming, isomerization,
polymerization, and alkylation units.
Treating
As noted earlier, crude oils contain small amounts of impurities, one
being sulfur, a major undesirable constituent. It is usually found in com-
bination with hydrogen or hydrocarbons as hydrogen sulfide (H-S), mercaptans
(R-SH), sulfides (R-S-R), polysulfides (R-S -R) and thiophenes (ring compounds
with sulfur as a member of the ring structure). During the refining process,
part of the original sulfur compounds are often converted to H S and to lower
molecular weight mercaptans. Sulfur removal from both product and intermediate
feedstocks, therefore,will be necessary, since sulfur compounds are frequently
odorous and may cause adverse plant and product quality effects. Removal
processes which will be used include hydrogen treatment, chemical treatment,
and physical treatment.
The sources of air pollutants from petroleum refineries are (Table VIII 1.2):
• heaters and boilers
e sulfur recovery units
• catalyst regeneration
• miscellaneous sources
The exhaust gas analysis fpr heaters and boilers would be the same as
the combustion sources which have already been discussed. Likewise, factors
for emission from sulfur recovery units axe similar to the sulfuxic acid
plants and reference should be made to Chapter IV-13. Miscellaneous sources
include purge lines or vents, leaks, pumps and compressors which have flow
rates due to natural convection at ambient temperatures. Catalyst regeneration
will be analyzed separately.
Cyclones, scrubbers or electrostatic preclpitators are commonly installed
on the high emission operations such as catalyst regeneration for air pollution
4
abatement. Improved housekeeping along with equipment maintenance is usually
the least disruptive method of reducing emissions. Plants are operated on a
VIII-2
continuous basis with shut-down only for periodic repair and maintenance.
GAS FLOH RATE '
The major source of visible emissions from refineries is the catalyst
regeneration units. The exhaust flow rates from these units are shown
in Table VII1-1.3 and Figure VIII-1.2.2 The exhaust flow rate can be
determined accurately since the exhaust flow is 2,000 scfm for every 1,000
barrels per day throughput capacity.
GAS TEMTERAI11RE
Exhaust gas temperatures from catalyst regeneration units range from
485 to 850°F with a mean of 650 F.
GAS VELOCITY
No specific gas velocity data were obtained for exit velocities; how-
ever, 30-60 fps is typical.
STACK HEIGHT
Stack heights from several refiners ranged from 150 - 200 feet high
on several petroleum catalyst regenerator unit stacks.
1!
II
VIII-3
-------
TABLE VIII-1.1
Capacities of V.S. Petroleum Refineries
TABLE VIII-1,2
Potential Sources of Specific Emissions From Oil Refineries
No. Crude
State Plants bpd
Alabama
Alaska
Arkansas
Ca!ifotn»l
Colorado
Delaware
Honda
Georgia
Hawaii*
Illinois
Indiana
Kansas
lou.sjjna
Maryland
M.cttigan
Minnesota
Vis«,*S'!>pl
MlSSCL"
Vonla^
Nebraska
New Vuito
He* York
(With Oitota
Ohio
C'tgon
Pe"sy!»ar,ia
Hi-tie Island
Tennessee
Utah
Virginia
Washington
West Virginw
Wisconsin
Wromm
Total
6
1
6
32
4
1
1
2
1
II
10
12
i
iS
2
8
3
i
1
S
-1
e
E
2
2
11
11
1
13
1
1
47
5
1
6
2
2
9
2E3
34 620
20,'000
93.500
1,529075
42.900
140,000
3.100
9.500
35.000
704.100
565,700
389.300
128.509
1.! 90.850
U6.050
138300
158700
83:30
:2E2M
4000
S23.JOO
42.EIO
76,600
55.000
491 600
449,367
11,000
628.920
7.500
28.500
3,118,250
11,950
53600
219000
8.570
29500
132.900
11.522,512
Emission
Oxides of sulfur
Hydrocarbons
Oxides of nitrogen
Particular matter
Aldehydes
Amnonia
Odors
Carbon monoxide
Potential sources
Boiler, process heaters, catalytic cracking unit
regenerators, treating units, H S flares, decoking
operations.
Loading facilities, turnarounds, sampling, storage
tanks, waste water separators, blow-down systems,
catalyst regenerators, pumps, valves, blind
changing, cooling towers, vacuum jets, barometric
condensers, air-blowing, high pressure equipment
handling volatile hydrocarbons, process heaters,
boilers, compressor engines.
Process heaters, boilers, compressor engines,
catalyst regenerators, flares.
Catalyst regenerators, boilers, process heaters,
decoking operations, incinerators.
Catalyst regenerators.
Catalyst regenerators.
Treating units (air-blowing, steam-blowing), drains,
tank vents, barometric condenser sumps, waste water
separators.
Catalyst regeneration, decoking, compressor engines,
inc inerators.
VIII-4
VIII-5
-------
Z-IIIA
TABLE VIlr-1.3
Exhaust Gases from
Catalyst Regeneration Units in Petroleum Refineries 2
Operation
Input Rate
bjd
Catalyst
Regeneration Units 50,00
31.54
24.00
46.26
11.02
15.92
34.00
10.00
11.00
12.60
12.10
13.10
12.06
7.06
11.00
31.80
11.90
Exhaust Flow
Exhaust Teffl
°F
112.00
28.00
22.20
97.50
27.00
27.00
64.00
22.00
27.60
24.00
25.00
27.00
23.00
13.30
16.80
80.60
14.90
820
510
520
485
840
700
530
660
610
850
740
810
710
610
680
-a
i
i
VIII-6
S J
Ss | 5 2£ |5
?s o5 a Si 05
r Fs s & if
i: .—i mz
MOTOR
.ASOUN
-------
150 -
100 •
50 -
Exhaust flow rate - 2.06 x throughput rate - 3.55
(l.OOOscfm) (1,000 bpd)
10 20 30 40 50
Crude Oil Throughput (1,000 bpd)
Figure tIH-1.2 Exhaust flow rates from catalyst regeneration units
VIII-8
CHAPTER VIII REFERENCES
1. "Atmospheric Emissions from Petroleum Refineries", U.S. Dept. of Health,
Education and Welfare, Public Health Service, Publication No. 973, 1960.
2. "Air Pollution Engineering Manual", U.S. Dept. of Health, Education, and
Welfare, Public Health Service, Publication No. 999-AP-40, 1967.
3. Unpublished data, Zurn Environmental Engineers.
4. "The Petroleum Refining Industries", Journal of the Air Pollution Control
Association, Vol. 14, No. 1, January, 1964.
VII1-9
-------
CHAWER IX-1
KRAFT PULP MILLB
As of December 31-, 1968 there were 116 kraft pulp mills in the United
States with a pulp capacity of over 30 million tons. Actual production in
1968 totalled 24 million tons. The mills are located principally on the east
and west coasts with the greatest concentration in the southeastern United
States. The kraft process accounts for over 75 percent of all the chemical
pulp produced in the U.S. but only 50 percent of the total mills. In other
words the kraft mills tend to be larger than sulfite or neutral sulflte semi-
chemical (NSSC) mills. Together these three processes account for 95 percent
of the total wood pulp produced in the U.S.
An excellent description of the process has been prepared in an earlier
study and is quoted here without change.
Pulp wood can be considered to have two basic components, cellulose and
lignin. The fibers of cellulose, from which the pulp is made, are bound to-
gether in the wood owing to the presence of the lignin. To render cellulose
usable for pulp manufacture, any chemical pulping process must first remove the
lignin.
The major discriminating factor of the kraft process (Figure IX-1.1) lies
in its utilization of a solution of sodium sulfide and sodium hydroxide in
water to dissolve lignin from wood. This liquor is mixed with wood chips in
& large, upright pressure vessel, known as a digester, and cooked for about 3
hours with steam at a gauge pressure of approximately 110 pounds per square
inch. Figure IX-1.2 shows feed rate versus production rate.
During the cooking period the digester is relieved periodically to reduce
the pressure build-up of various gases within.
When cooking is completed, the bottom of the digester is suddenly opened,
and its contents forced into the blow tank. Here the major portion of Che
spent cocking liquor containing the dissolved lignin is drained and the pulp
enters the initial stage of washing. From the blow tank the pulp passes through
the knotter, which removes the chunks of wood not broken down during cooking.
It then proceeds through various intermittent stages of washing and bleaching,
after which,it is pressed and dried into the finished product.
A major reason for the economic success of t.iis type of pulping operation
lies in It* ability to recover most of the chemicals from the spent cooking
IX-l
-------
liquor for re-use in subsequent cooks. The recovery process is initiated by
Introducing the spent ("black") liquor from the blow tank into a multiple
effect evaporator where it is concentrated into a mixture with a density of
about 25° Baume. The spent or black liquor is further concentrated in a
direct contact evaporator, which, by bringing the liquor into direct contact
with recovery furnace flue gases, evaporates an additional portion of water.
The combustible, concentrated black liquor thus produced is then forced
through spray nozzles into the recovery furnace, where it is burned to recover
a portion of the heat by oxidation of the dissolved lignin and to conserve the
icorganic chemicals, which fall to the floor of the furnace in a molten state.
The resulting melt, which consists mainly of a mixture of sodium sulfide
aad sodium carbonate, is withdrawn from the furnace and dissolved with water
and veak liquor from the causticizing plant. The "green" liquor thus produced
is pumped into a causticizer, where the sodium carbonate is converted to
sodiiaa hydroxide by the addition of calcium hydroxide. The calcium carbonate
resulting from the reaction precipitates from the solution and is collected
and introduced into a lime kiln, where it is converted to calcium oxide. This
is slaked to produce calcium hydroxide for further use in the causticizer.
The effluent solution produced by the causticizing reaction with the
greec liquor contains sodium hydroxide, sodium sulfide, and smaller quantities
of sodium sulfate and sodium carbonate. Known as "white" liquor, this
solution is withdrawn and re-used in the digestion process.
Ihe sources of particulate and sulfurous gas emissions from a kraft pulp
Bill in order of importance are: 1.) recovery furnace, 2.) lime kiln, 3.) power
plant, 4.) digester relief and blow tank, 5.) black liquor oxidation tower,
6.) d is solver tank and 7.) evaporator.
Controls are generally precipitators on the recovery furnace, scrubbers on
the line kilns, mechanical collectors on the back fed boilers, and combustion
in the line kiln of many of the odorous gas streams.
Kraft mills operate continuously about 350 days per year with down time
only for routine maintenance.
Exhaust gases from the bark-fired power plants were discussed in Chapter
II-7 and will not be repeated here. Other processes are examined in detail.
"Recovery Furnace"
GAS TiOil
Data from 20 separate recovery furnaces were tabulated and plotted
tX-2
to show the pulp production rate versus exhaust gas flow rate (Table IX-1.1
and Figure IX-1.3). The production of 1 ton of air dried pulp was assumed
to be directly related to the amount of black liquor solids (2700 Ib.) fed
to the recovery furnace. A systems study showed 272,000 scf of exhaust
gases would be discharged from the recovery furnace for every ton of air
4
dried pulp produced. Stated another way, the flow rate is 189 scfra
for every ton/day of pulp produced.
GAS TEMPERATURE
The systems study showed 325 F to be an average temperature for the
exhaust gases from the precipitator. The range was from 325 to 375 F. When
scrubbers were used the exit temperature ranged from 165 to 200°F.
GAS VE_LOCnY
Gas velocity from 6 black liquor recovery furnace stacks ranged from
13 to 38 £ps. Assume 30 fps when, no data are available.
STACK, HEIGHT
Stack height was available for 10 recovery furnaces; the range was from
125 to 400 feet with 250 feet being rather typical.
IX-3
-------
"Lime Kiln"
Calcining of the calcium carbonate sludge from the causticizing reaction
is performed in the lime kiln. Dust loading varies with kiln length, soda
content, and gas velocity. With a short kiln (100 feet), high velocity, and
low soda content, dust loading will be high. With a long kiln (300 feet)
and high soda content, dust loading will be low.
GAS PLOW RATE
The systems study showed a gas flow rate from the lime kilns of 38,199 scf
per ton of pulp produced. Another investigator used 37,265 scf per ton. One
plant showed 18,700 scfm from the lime kiln on a 500 ton/day mill. The 38,100
converts to 13,250 scfm for a 500 ton/day mill (Table IX-1.2). Therefore assume
26 scfm of lime kiln exhaust gas per ton/day of pulp production.
GAS TEMPERATURE
The systems study assumed an average exit temperature of 180°F. One
other data point showed 150°F so the 180°F should be used.
GAS VELOCITY
No data were available on stack gas velocity. Assume 20 fps when no data
exist.
"STACK HEIGHT
Data for 6 mills showed steel stubs to be used on the lime kiln exhaust.
In the absence of other data assume 30 feet for stack height.
IX-4
"Digester Relief and Blow Tank"
Sulfur compounds are released during the cooking and discharge of pulp
to the blow tank. A large quantity of steam is released, but it is normally
condensed.
GAS FLOW RATE
Non-condensible gases from the digester or blow tank discharge at 155 scfm
at one 500 ton/day mill. Another author reported 137 and 274 scf per ton of
pulp produced by continuous and batch type digesters. Thus, for a 500 ton/day
mill 48 scfm or 100 scfm would be generated. The systems study reported 274
scf per ton when an accumulator was used.
GAS TEMPERATURE
The system study reported 120°F for these exhaust gases. No other data
were found.
GAS VELOCITY
So data were available; assume 20 fps.
STACK HEIGHI
No data were available; assume 30 feet.
DC-5
-------
"Dissolving Tank"
CAS FLOW BATE
The system study reported an average 36,100 scf per ton of pulp produced,
Hough reports 24,000 scf per ton of pulp produced. Walther reported 20,700
scftn from the dissolver tank vent on a 500 ton/day mill; this is equivalent to
59,600 scf per ton of pulp. Therefore, use 36,100 scf per ton of pulp pro-
duced or 40 scfm per ton/day.
GAS TEMratiATURE
Exhaust temperature for uncontrolled tanks or those using mesh pads will
be about 200°F. If a scrubber is used 160°F will be the exit temperature.
GAS VELOCITY
No data were available, but 20 fps may be assumed.
STACK HEIGHT
No data were available, but 30 feet may be assumed.
rx-6
"Miscellaneous Other Operations"
Remaining pollution sources in a kiaft mill which may generate some air
contaminants and their total volume per ton of pulp produced are tabulated
, i 4.5
below.
Department
Washers
Bleach Plant
Evaporators
Power Boiler (Hag Fuel)
Paper Machine
Slaker
Total Volume
(scf/ton)
70,000
80,000
300
300,000
430,000
7,000
rs-7
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IX-11
-------
150
100-
50
200 400 600 800 1.200
Production Rate (tons/day)
Figure IX-1.2 Feed rate vs. Production rate for kraft pulp mills
n- u
II
£ 200 •
Exhaust Flow = 0.33xProd. Rate-5.1
(1,000 scfm) (tpd)
200 400 600 800
Pulp Production (tons/day)
1000
Figure IX-1.3 Recovery furnace exhaust gas flow rate vs. pulp
production rate.
Dt-13
-------
CHAPTER IX-2
SUUFITE PULP MILLS C
There are 43 sulfite pulp mills in the U.S. with an annual capacity of
about 3.5 million tons. The average size of these mills is 10,875 tons of
air dried pulp per day. Fifty percent of the sulfite pulp production comet
from the northwestern United States. The plants operate continuously
350 days per year.
The sulfite pulping process dominated the commercial pulping field from
1890 to 1930 but has declined in importance because of chemical costs and dis-
posal problems. A description of the process is quoted from the systems study.
Sulfite pulping is an acid chemical method of dissolving the lignin that
bonds the cellulose fibers together. Many of the older mills use a sulfurous
acid - calcium bisulfite solution for the cooking acid. Calcium-base spent
liquor, because of problems associated with evaporation and chemical recovery,
is discarded and may result in water pollution problems. In order to overcome
this problem several other acid bases have been developed, the most, important
being sodium, magnesium, and ammonium.
Because sulfite pulp is used in a wide variety of end products, operations
will vary considerably among mills. These products can include pulp for
making high grade book and bond papers and tissues, for combining with other pulps,
and for making dissolving pulp for producing cellophane, rayon, acetate, films,
and other products.
The pulping operation involves cooking the wood chips in the presence of
an acid within a digester. The heat required for cooking is produced by the
direct addition of steam to the digester or by the steam heating of the re-
circulated acid in an external heat exchanger. The cooking liquor, or acid,
is made up of sulfurous acid and a bisulfite of one of the four above bases.
The sulfurous acid is usually produced by burning sulfur or pyrites and absorbing
the SO. in liquor, normally, part of the sulfurous acid is converted to the
base bisulfite to buffer the cooking action. During the cooking action it is
occasionally necessary to vent the digester as pressure rises within the
digester. These vent gases contain large quantities of sulfur dioxide and,
therefore, are recovered for reuse in the cooking acid.
Upon completion of the cooking cycle the contents of the digester,
consisting of cooked chips and spent liquor, are dlshcarged into a tank.
IX-14
During this operation some water vapor and fumes escape to the atmosphere from
the tank vent. The pulp then goes through a washing stage, where the spent
liquor is separated from the fibers. The washed pulp is either shipped or
kept within the plant for further processing.
The spent liquor that was washed out of the pulp can be discarded or, as
an alternative, can be concentrated by evaporation and run through a recovery
cycle. The concentrated liquor is sprayed into a furnace where the organic
compounds are burned. The residual inorganic compounds may be collected and
reused in the manufacture of cooking acid.
Emissions consist of sulfur oxides and particulates. Controls generally
involve use of cyclones and scrubbers on the recovery boiler and mechanical
collectors on the boiler.
Major emission sources are the power plant (discussed earlier), recovery
furnace, digester and dump tank, and miscellaneous sources such as evaporators,
washers and screens, and the bleach plant.
IX-15
-------
"Recovery Furnace"
GAS FLOW SATE
Exhaust gas volume from the recovery furnace is reported to be 297,000 -
A
339,200 set per ton of air dry pulp produced. Not many of the sulfite
pulp mills will recover chemicals, so this point should be checked before
estimating emissions.
CAS TEMPERATURE
Exhaust gas temperature was reported to average 165°F.
GAS VELOCITY
No data were available, but assume 20 fps.
STACK HEIGHT
No data were available, but assume 200 feet since a fairly tall stack is
expected.
"Digester Relief and Dump Tank"
GAS FLOW RATE
Exhaust gas flow rates are small, about 414 scf per ton of
pulp produced. In some sulfite mills without chemical recovery the digester
relief gases are reported to be 16,600 scf per ton.
GAS TEMPERATURE
Gas temperature of these gases ranges from 80 to 250 F. When data are
not available, assume 180 F.
GAS VELOCITY
No data were available, but assume 20 fps.
STACK HEIGHT
No data were available, but assume 30 feet.
n-u
I!
Dt-17
-------
"Miscellaneous Sources"
From the comprehensive study of control of atmospheric emissions in
the wood pulping industry the following gas flow and temperature data are
offered for miscellaneous sources.
Source
Evaporator
Washer and screens
Bleach plant
Acid tower
Boiler
Total Flow
_«cf/ton
44
86,100
37,600
15,000
240,100
Temperature
r
140
125
90
70
350
CHAPTER IX-3
NSSC PULP MILLS0
The neutral Sulfite semichemical (NSSC) pulping process is used mainly
for making corrugated board. There are 43 mills in the U.S. producing some
3.5 million tons annually. The average production rate is 10,675 tons/day
of air dry pulp.
A description of the NSSC process is quoted as it appears in the systems
^
study of the pulping industry.
The process derives its name "neutral sulfite" from the fact that the
solution containing the cooking chemicals, consisting of sodium sulfite and
sodium carbonate, is maintained above a pH of 7.0. The name "semichemical"
is given because all of the cementing material is not completely removed by
the chemical reaction and some mechanical disintegration is required to
separate the fibers. Because some of the cementing material remains with the
fibers it follows that the "yield" for this process is higher than that for a
conventional full-chemical pulping process. Semichemical pulping may produce
yields of 60 to 80 percent.
The cooking process is carried out in either batch or continuous digesters.
Steam maintains the temperature and pressure of the cook within certain limits
depending on the end use of the pulp. During this cooking stage odorous gases
are created within the digester. At the completion of the cooking cycle,
residual pressure within the digester is used to discharge the entire contents
of the batch digester into a blow tank. Waste gases, containing the odorous
compounds formed in the digester, are usually vented to the atmosphere.
Before the pulp fibers can be used in the production of paper products the
spent liquor must be washed from the pulp. This washing is usually performed
on multi-stage drum filters. If a kraft system is adjoining, the NSSC spent
liquor can be mixed with the spent kraft liquor, up to a limiting percentage,
and burned in the recovery furnace. The recovered chemicals are used entirely
in the kraft system. Emissions of both sulfur dioxide and hydrogen sulfide
may be increased from the kraft recovery furnace when NSSC liquor is added.
Besides the two above spent liquor systems, one discharging the spent
liquor to sewer and other mixing NSSC liquor with kraft liquor, there is a
fluidized bed recovery system. This is a patented system in which the NSSC
spent liquor is oxidized in a reactor producing a pelleted product, consisting
of sodium carbonate and sodium sulfate.
IX-19
-------
The one source of emissions common to all NSSC pulp mills Is the blow
tank. About half (15-20) of the mills have no chemical recovery. Ten or
15 deliver spent liquor to an adjoining kraft recovery system and 2 to 4
recover chemicals in a fludlzied bed process.
a-20
"Blow Tank"
GAS FLCW RATE
Exhaust gases total 17,350 - 27,600 scf/ton from the blow tank. As an
average assume 23,700 scf/ton.
GAS TEMPERATUBE
From all three types of NSSC pulp mills the blow tank exhaust temperature
runs 200 - 212°F. Since the more popular processes discharge blow gases at
212°F use this for calculations.
GAS VELOCITY
No data were available; assume 20 fps.
STACK HEIGHT
No data were available; assume 30 feet.
IX-21
-------
"Absorption Tower"
GAS FLOW RATE
For those NSSC mills which use an absorption tower and sulfur burner
emissions can be expected to total 3,400 scf/ton.
GAS TEMPERATURE
Exhaust gas temperatures from the absorption tower exit at 100°F.
GAS VELOCITY
No data were available; assume 20 fps.
STACK HEIGHT
No data were available; assume 30 feet.
IX-22
"Recovery Furnace"
GAS FLOW RATE
Where spent liquor is sent to a kraft mill for chemical recovery, the
emissions from the NSSC portion are 22,500 scf/ton.
GAS TEMPERATURE
Exit gas temperatures after a precipitator can be expected to be 325°F.
GAS VELOCITY
No data were available; assume 20 fps.
STACK HEIGHT
No data were available, but recovery furnace stacks are expected to be
200 feet.
IX-23
-------
"Fluidized Bed Reactor"
GAS FLOW SATE
After the exhaust gases have passed through a venturi scrubber, the
volumetric flow will be 121,700 scf/ton.
GAS TEMPERATURE
Average temperature following the venturi will be 180 F.
GAS VELOCITY
No data were available; assume 20 fps.
STACK HEIGHT
No data were available; assume 30 fpa.
a-2*
CHAPTER IX REFERENCES
1. Kenline, P.A. and Hales, J.M., "Air Pollution and the Kraft Pulping
Industry - An Annotated Bibliography", U.S. Dept. of Health, Education,
and Welfare, Public Health Service, Cincinnati, Ohio, November, 1963.
2. Walther, J.E. and Amberg, H.R., "A Positive Air Quality Control Program
At a Jtev Kraft Mill", Unpublished, Crown Zellerbach Corporation, Camas,
Washington.
3. Unpublished data from the files of Engineering Science, Inc., Washington,
D.C.
4. Hendrickson, E.R., et.al., "Control of Atmospheric Emissions In The
Wood Pulping Industry", U.S. Dept. of Health, Education and Welfare,
National Air Pollution Control Administration, Washington, D,C.,
.Xarch 15, 1970.
5. Hough, G.W. and Gross, L.J., "Air Emission Control In A Modern Pulp and
Paper Mill", American Paper Industry, page 36, February, 1969.
6. Hendrickson, E.R., editor, "Proceedings of the International Conference
On Atmospheric Emissions From Sulfate Pulping", U.S. Dept. of Health,
Education, and Welfare, Public Health Service, April 28, 1966.
IX-25
-------
CHAPTER X-l
DRY CLEANING PLANT C
Some 50,000 or so dry cleaning plants are located throughout the U, S.
In San Francisco, which may be typical of the larger cities, 720 plants were
operating in 1965. Two types of solvents are commonly used by the dry
cleaning industry: petroleum solvents (e.g. Stoddard solvent and 140°F solvent)
and chlorinated solvents (e.g. perchloroethylene). A typical dry cleaning
plant will have a capacity on the order of 500 pounds/day. Plants usually
operate 8 hr./day and 5 or 6 days a week. The amount of solvent necessary
to clean clothes varies with the type solvent. For perchloroethylene it takes
4.9 Ibs. solvent per pound of clothes; for the Stoddard solvent it takes
7.6 Ibs. solvent per pound of clothes;and for Safety 140 F the ratio is 6.5
Ibs. solvent per pound of clothes cleaned.
The basic air pollution problem associated with dry cleaning is solvent
evaporation. Clothing or other textiles are cleaned by agitation in a
solvent bath, and then, after being rinsed in a clean solvent, are placed in a
drier to evaporate the latent solvent. The principal control device for
the chlorinated solvents is a water cooled condenser which is an integral
part of the closed cycle in a tumbler or drying system. About 95 percent of
the solvent is recovered here for reuse. Activated carbon adsorbers may
also be used in addition to the water cooled condenser to provide an
2
overall solvent recovery efficiency of 97 - 98 percent. Other plants do not
attempt to recover the solvents. Instead they use catalytic afterburners to
incinerate exhaust waste gases. There are no commercially available control
units for solvent recovery in petroleum based plants (Stoddard and 140 F
solvents), because it is not economical to recover the vapors. Stoddard and
140 F solvents cost $.20/gal. Perchloroethylene costs S2.00/gal.
GAS FLOW RATE
The eadisust gas flow rates from dry cleaning units (driers) are relatively
low, less than 10,000 scfm for most size plants. Natural gas is commonly used
t» the heat source. Driers usually have name plates denoting size and other
related operating data. Table X-l.l lists operating data.
X-l
-------
GAS TEMPERATURE
Temperatures in driers do not exceed about 150°F; hotter temperatures
would damage the clothing. Gas temperatures for three units without in-
cinerators ranged from 75 to 110°F, Gas exit temperatures with incinerators
would be about 1000°F, For modeling assume 100°F for most units.
GAS VELOCITY
Exit velocity from the driers will be about 40 fps for controlled units.
Other units are expected to have an exit velocity of 10 fps.
STACK HEIGHT
Stack heights for three plants ranged from 20 - AO feet. Assume 30 feet
when data are unavailable.
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CHAPTER X-2
SURFACE COATING OPERATION *
Surface coating operations cover a myriad of industrial applications
ranging from the spray painting of automobiles to the lithographing of food
cans. Most fabricating plants which manufacture a finished product will
have a surface coating operation.
Basic coating operations consist of dipping, spraying or flow coating.
Combinations of these operations are likely. Spraying is probably used more
than dipping or flow coating simply because of the economics of the materials
used. All spraying operations are vented to prevent buildup of the paint
odors. The principal air contaminants are particulate matter, consisting of
fine paint particles and solvent vapors. Dipping and flow coating operations
are seldom vented or controlled. The principal air contaminant from
these operations is solvent vapors.
Farticulate air pollutants can be controlled by baffle plates, filters
and water spray curtains. Organic vapors are controlled by thermal or
catalytic incineration. '
Operational times vary with the Industrial applications. Spray painting
of automobiles would be expected to operate continuously 24 hours/day and
5 days a week. Fainting of steel drums may operate 1 shift per day and S
days a week.
GAS FLOW RATE
Exhaust gas flow rate in the case of spray painting is dependent on the
size opening of the spray booth and on a minimum indraft velocity of about
100 fpm. Larger areas would, of course, require more gas flow. Table X-2.I
o
summarizes data from several kinds of surface coating operations. Exhaust
flow rates ranged from 600 to 60,000 scfm,but most vented areas run about
12,000 cfm (Figure X-2,I). Operations using thermal incinerators generally
operate at 5,000 scfm or below because of the cost of fuel and the desire to
have high concentrations of vapors.
GAS TEMPERATURE
Exhaust gas temperatures for operations without incinerators are ambient,
so assume 60°F. Gas exit temperature* for those operations with Incinerators
X-4
ranged from 400 - 1000°F for six units. Assume 700°F.
GAS VELOCITY
Gaa exit velocities from over 20 data observations ranged from 5 to 63
fps with a mean of about 40 fps. It should be noted that one industrial plant
may have many stacks for surface coating ventilation. One site visit
revealed about 20 stacks from an auto assembly plant.'
STACK HEIGHT
The stack heights ranged from 0 to 75 feet. Surface coating vent stacks
are usually located on the top of the plant and protrude about 10 feet. The
stacks are almost all made of sheet steel and are about 15 inches in diameter.
When no stack height data are available, assume 50 feet for modeling.
X-5
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X-9
-------
CHAPTER X-3
GASOLINE MARKETING D
Gasoline marketing requires several transfer phases to get gasoline
from refineries to the carburetor of an automobile. Every metropolitan area
of the U. S. will have several clusters of bulk storage tanks (tank farms)
as part of a large distribution network for the major oil companies. Gasoline
is moved from here to the service stations by truck as needs demand.
The major points of emission include:
• Breathing and working losses from bulk terminal storage tanks.
• Filling losses from bulk terminals tank filling and truck loading.
• Filling losses free underground storage tanks at service stations.
• Filling losses (and spillage) from automobile tank filling at
service stations,°
Air contaminants associated with gasoline marketing are simply gasoline vapors
expelled from a tank by displacement as a result of the filling operation.9
The only type of air pollution control utilized is a vapor return system; i.e.
a return line deliver the vapors to the master vessel while unloading.
Return lines are popular in California,but, at present, are not being used
elsewhere in the U. S. Service stations have a vent pipe about 10 to 20 feet
high made out of 2" pipe which carrys the vapors away to be dispersed into the
atmosphere.
15 gallons of gas is pumped into a car during a filling operation which takes
about 5 minutes. The gas flow rate from this operation would be 0.5 scfm.
GAS TEMPERATURE
Exhaust gas temperatures from gasoline marketing will be near ambient
conditions, so 60°F should be assumed.
GAS VELOCITY
Gas exit velocities will usually be less than 5 fps.
STACK HEIGHT
Gasoline storage tanks are about 50 feet high. The vent pipe at a
service station is about 10 - 20 feet high. However, gasoline marketing
sources should be treated as an area source for modeling because of the
number and scale of the operations.
GAS FLOM RATE
American Petroleum Institute nomographs may be used for calculating
emissions and exit gas volumes from petroleum storage tanks. Figure X-3.1
Illustrates breathing losses from a fixed roof tank. Since one gallon of
gasoline will vaporize to 29.6 ft. , one barrel of liquid gasoline will
occupy 1240 cubic feet of space as a vapor.5 Thus, by knowing the breathing
loss in bbl/yr., exhaust flow rates can be calculated.
The exit flow resulting from filling bulk terminals, tank trucks, or
an underground tank at a service station can be calculated by knowing the sice
of the tank and the time to fill it. One gallon of liquid gasoline will
occupy 0.133 ft. of space (7.5 gallon equals 1 cubic foot). Therefore, if
a bulk tank service station had a capacity of 2,000 gal. and was filled in
20 minutes, the flow rate could be calculated as 13.3 scfm. An average
X-10
X-ll
-------
Zl-X
= 1-
1
r
CHAPTER X REFERENCES
1. Grouse, W.R. and Flynn, N.E., "Report on Organic Emissions from the
Dry Cleaning Industry", Bay Area Air Pollution Control District,
San Francisco, Calif.
2. Chass, Robert L., Ranter, C.V., and Elliot, J.H., "Contribution of
Solvents to Air Pollution and Methods for Controlling Their Emissions",
Journ. of Air Poll. Control Assoc., Vol. 13, No. 2, Feb., 1963.
3. State Air Pollution Permit Data, June 1971.
4. Shreve, R. Norris, Chemical Process Industries, McGraw Hill, New York,
N.Y., 1967.
5. "Air Pollution Engineering Manual", U.S. Department of Health, Education,
and Welfare, Public Health Service, Publication No. 999-AP-40, Cincinnati,
Ohio, 1967.
6. Brewer, Gerald L., "Fume Incineration", Chemical Engineering. October 14,
1968.
7. Unpublished data, Zurn Environmental Engineers.
8. McGraw, M.J., "Air Pollutant Emission Factors", Draft Copy, U.S. Dept.
of Health, Education, and Welfare, Air Pollution Control Office,
Durham, N.C., August, 1970.
9. Chass, Robert L., et al., "Emissions from Underground Gasoline Storage
Tanks", Journ. of the Air Pollution Control Assoc., Vol. 13, No. 11,
November, 1963.
10. Deckert, Ivan S., et al., "Control of Vapors from Bulk Gasoline Loading",
Air Pollution Control Association, Vol. 8, No. 3, November, 1958.
X-13
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APPENDIX A
Theoretical Exhaust Flow Rate and Velocities
Flow Rate
Often more precise flow rates will be needed to evaluate a specific
combustion source. This part of the appendix will show the reader how to
calculate the exhaust flow rates when data on coal analyses and excess
air rates are known. The theoretical procedure is taken from Combustion
Engineering (New York, N.Y.) one of several published sources
which have similar calculation procedures. The following example is for
bituminous coal combustion.
Coal Analysis
Given: element % weight composition
C 63.5
H2 4.0
°2 7'5
S 1.5
N 1.3
Moisture 15.0
Ash 7.2
Higher heating value is 11,350 BTU/lb.
Excess air rate is 207,
A factor, VM, is calculated, then used with Figure A-l to determine the
amount of air needed for combustion.
- 13.2
H2 + 0.1 02 4.0 + 0.1 (7.5)
With an excess air rate of 20% and VM - 13.2, read the atmospheric air
requirement of 940 pounds of air per million BTU input. The density of air
is 0.0750 Ib./ft. at 70°F, 1 atm. The amount of combustion air needed to
burn 10 tons per hour of coal being fed to the boiler is
10 tons hrs. 2000 Ibs 11.350 BTU 940 Ib. air ft3
I, ust ™ hr. 60 nl«Tton Ib. 10° BTU 0.0750 Ib. air
» 47,000 scfm
The exhaust flow rate from chis source is 1.05 times the combustion air or:
Exhaust Flow Rate (scfm) > 49,000 scfm
A-l
-------
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NOTE GUIDE LINES AfiE DRAWN fQR
TYPICAL HIGH TEMPERATURE
CO^E BREEZE
WHERE VM iS USED
ON THESE CHARTS
'TIS VOLATILE MAT-
TER ON MOISTURE AND {- 1
1700
1600
1500
(400
1300 £
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uool
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1000 Si
9OO
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Velocity
Often, throughout this report, data were available on stack flow rate,
but no data were listed for gas exit velocity. With the use of Figure A-2,
Combustion Engineering, the reader can also determine economic stack exit
velocity. For example, if the flow rate for a sulfurie acid plant was 30,000
scfra (500 scfs) the stack diameter can be read from Figure A-2 of 5.9 feet.
The area of the stack can be calculated which is then used to calculate the
velocity, or Figure A-2 can be read directly.
Calculated Gas Exit Velocity (fps) • Flow Rate
Area of stack
= 500 ft.3/gec.
(5.9)2 ft.2
4
• 18.2 fps
K> 2O 30 4O 50 60 70 8O 90 100
EXCESS AIR-PER CENT
Figure A-l Theoretical Air Requirements for Bituminous
Coal Combustion.
"T • '» o >
HCAN IMStOC SIMK OUUKTCM.
Figure A-2 Theoretical CM Exit Velocity - Stack
Capacity (cuft per sec.) vs
inside stack diameter (feet).
A-2
A-3
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