xvEPA
United States
Environmental Protection
Agency
Air Pollution Training Institute
MD20
Environmental Research Center
Research Triangle Park NC 27711
September 1978
EPA-450/3-78-106
Air
APTI
Course 439
Visible
Emissions
Evaluation
Student
Manual
Fina
-------
United States
Environmental Protection
Agency
Air Pollution Training Institute
MD20
Environmental Research Center
Research Triangle Park NC 27711
September 1978
EPA-450/3-78-106
APTI
Course 439
Visible
Emissions
Evaluation
Final
United States Environmental Protection Agency
Office of Air, Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
-------
US/EPA
THIS IS NOT AN OFFICIAL POLICY AND STANDARDS DOCUMENT.
THE OPINIONS, FINDINGS, AND CONCLUSIONS ARE THOSE OF
THE AUTHORS AND NOT NECESSARILY THOSE OF THE ENVIR-
ONMENTAL PROTECTION AGENCY.
EVERY ATTEMPT HAS BEEN MADE TO REPRESENT THE PRESENT
STATE OF THE ART AS WELL AS SUBJECT AREAS STILL UNDER
EVALUATION.
ANY MENTION OF PRODUCTS OR ORGANIZATIONS DOES NOT
CONSTITUTE ENDORSEMENT BY THE UNITED STATES ENVIR-
ONMENTAL PROTECTION AGENCY.
ii
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svEPA
AIR POLLUTION TRAINING INSTITUTE
MANPOWER AND TECHNICAL INFORMATION BRANCH
CONTROL PROGRAMS DEVELOPMENT DIVISION
OFFICE OF AIR QUALITY PLANNING AND STANDARDS
The Air Pollution Training Institute (1) conducts training for personnel working on
the development and improvement of state, and local governmental, and EPA air
pollution control programs, as well as for personnel in industry and academic insti-
tutions; (2) provides consultation and other training assistance to governmental
agencies, educational institutions, industrial- organizations, and others engaged in
air pollution training activities; and (3> promotes the development and improve-
ment of air pollution training programs in educational institutions and state, regional,
and local governmental air pollution control agencies. Much of the program is now
conducted by an on-site contractor, Northrop Services, Inc.
One of the principal mechanisms utilized to meet the Institute's goals is the intensive
short term technical training course. A full-time professional staff is responsible for
the design, development, and presentation of these courses. In addition the services
of scientists, engineers, and specialists from other EPA programs, governmental
agencies, industries, and universities are used to augment and reinforce the Institute
staff in the development and presentation of technical material.
Individual course objectives and desired learning outcomes are delineated to meet
specific program needs through training. Subject matter areas covered include air
pollution source studies, atmospheric dispersion, and air quality management. These
courses are presented in the Institute's resident classrooms and laboratories and at
various field locations.
Robert G. Wilder
Program Manager
Northrop Services, Inc.
Q£sA~$&£&Usn£sr'
/[ .Mean J. Schueneman
fr Chief, Manpower & Technical
Information Branch
ill
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FOREWORD
The Federal Government has discontinued the use of
Ringelmann Number standards in Federal new source per-
formance standards and has now based the determination of
the optical density, or opacity of visible emissions from
stationary sources, solely on opacity. Many State
regulations have not made this change and continue to
operate under a dual system in which Ringelmann Number
is used in the evaluation of black or gray emissions and
Equivalent Opacity is used in the evaluation of all other
visible emissions.
This manual is designed to serve as wide an audience as
possible and so continues to refer to both the Ringelmann
Number and the Equivalent Opacity methods of evaluation.
If opacity is now the only type of visible emission reg-
ulation in your State, please make the proper adjustments
in the manual curriculum to reflect this regulation. If
Ringfelmann and Equivalent Opacity are currently viable
in your State, your trainees should at least be aware of
the Federal practice. A copy of the current Method 9 as
published in the Federal Register is included in this
manual.
This manual is intended for those students who need to
become a qualified visible emissions evaluator for the
first time. To become a qualified visible emissions
evaluator the student must successfully complete a train-
ing school, normally of three days duration presented by
a Federal, State or local air pollution agency, or
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educational establishment. The training school
consists of a series of lectures, slide and film
presentations and the actual training of the students to
evaluate the opacity of visible emissions. The first
half of the school provides sufficient background
material such that competent evaluations of the opacity
of visible emissions can be made in the field during
enforcement operations. The second half includes the
qualification steps in reading visible emissions.
During the second half, students needing only recertifica-
tion can be included. They need not repeat the first
half.
Batelle-Columbus Laboratories is creo. -d for most of
the material in this manual. Under contact with EPA,
they prepared a training package. Because there has
been much time elapsed since completion of their contract
and due to many changes in regulations and techniques,
EPA has found it appropriate to modify the package
prepared by Batelle.
vi
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CONTENTS Page
FOREWORD v
COURSE OBJECTIVES xi
I. VISIBLE EMISSIONS: THEIR CAUSE AND REGULATION 1-1
II. PRINCIPLES OF COMBUSTION 2-1
III. COMBUSTION OF FUEL OIL - CORRECT PRACTICES 3-1
Classification of Fuel Oil 3-1
Oil Burner Types 3-3
Boiler Types 3-8
Soot Blowing 3-9
Black Smoke and White Smoke 3-10
Particulates 3-11
Sulfur Trioxide 3-12
Control Equipment . 3-13
IV. COMBUSTION OF COAL AND ITS CONTROL 4-1
Classification of Coal 4-1
Basics of Coal Combustion and Combustion
Equipment 4-5
Some Terms Used in Coal Combustion 4-9
Plume Visibility 4-11
Mechanical Coal Firing Equipment 4-13
Causes and Control of Particulate Emission
From Coal Combustion 4-16
V. OTHER COMBUSTION EMISSIONS: INCINERATORS, AGRI-
CULTURAL BURNING, NATURAL GAS, AND MOBILE SERVICES 5-1
Solid Waste Disposal by Incineration 5-1
Agricultural Burning 5-7
Combustion of Natural Gas 5-8
Engines Used in Transportation 5-11
Visible Emissions From Mobile Sources 5-13
vii
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Page
VI. NONCOMBUSTICN EMISSIONS AND WATER VAPOR PLUMES 6-1
Metallurgical Furnaces 6-1
Driers 6-4
Terminology in Metallurgical Processing 6-5
Iron and Steel Mills , 6-7
Gray Iron Foundaries 6-12
Non-Ferrous Metallurgical Industry 6-13
Petroleum Refineries 6-15
Portland Cement and Lime Plants 6-17
Kraft Pulp Mills 6-19
Sulfuric Acid Manufacturing , . , . 6-20
Nitric Acid Plants 6-22
Paint and Varnish Manufacturing 6-23
Hot-Mix Asphalt Batching Plants , 6-24
Phosphoric Acid Manufacture 6-26
Phosphate Fertilizer Manufacture 6-28
Soap and Synthetic Detergent Manufacture 6-29
Wet Plumes 6-30
VII. CLASSIFICATION AND IDENTIFICATION OF SOURCES ,... 7-1
Classification 7-1
Identification 7-3
VIII. RINGELMANN CHART AND EQUIVALENT OPACITY 8-1
The Ringelmann Chart £-5
Smoke Reading Aids 8-7
Training of Inspectors 8-10
Problems of Reading Smoke in the Field 8-12
Advantages of Visible Emission Regulations 8-15
IX. QUALIFICATION PROCEDURES AND EXERCISE IN RECORDING FOR
QUALIFICATION 9-1
Instructions to the Student During the
Reading of Smoke ,, 9-2
Filling Out the Training Form 9-4
viii
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X. BASIC METEOROLOGY 10-1
Primary Meteorological Factors Affecting
Concentration of Air Pollutants 10-1
Wind 10-2
Pressure Gradient Force 10-6
Coriolis Effect 10-7
Topographical Features 10-10
Stability 10-11
Solar Radiation, Precipitation, and
Humidity 10-27
Topography 10-28
Sky Condition 10-28
XI. LEGAL ASPECTS OF VISIBLE EMISSIONS 11-1
History and Test Cases 1.1-1
Equivalent Opacity and Smoke Emission
Laws 11-4
Local Regulations 11-6
How to be an Expert Witness..-...- 11-6
XII. OBSERVATION REPORTS FOR VIOLATIONS 12-1
Special Designations 12-4
XIII. EMISSION GENERATOR 13-1
Mark II Smoke Generator 13-1
Black Smoke -13-1
White Smoke 13-2
Transmissometer 13-2
Conduct of the School 13-4
Other Smoke Generating Equipment 13-4
ix
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Page
XIV. OPACITY PROBLEMS CAUSED BY WATER VAPOR 14-1
Visible Identification of Water Vapor Plumes ... 14-3
Typical Operations Which Discharge Water
Vapor 14-5
Methods of Eliminating Visible Wet Plumes 14-6
Reading Water Vapor Plumes 14-8
Description of the Psychrometric Chart 14-9
Example of the Use of the Psychrometric
Chart 14-14
XV. U.S. EPA METHOD 9 - VISUAL DETERMINATION OF THE
OPACITY OF EMISSIONS FROM STATIONARY SOURCES
(40CFR Part 60 Appendix A) 15-1
XVI. FEDERAL STANDARDS OF PERFORMANCE FOR NEW STATIONARY
SOURCES (SUMMARY) 16-1
XVII. VISIBLE EMISSION STANDARDS OF THE UNITED STATES 17-1
x
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COURSE OBJECTIVES
This manual is intended for use by students that have
not been certified as a qualified observer. The con-
tents of this manual will provide the qualified observer
with adequate background knowledge needed to help sub-
stantiate any violation that.he.may record.
At the conclusion of this course the student should be
able to:
(1) Visually measure (i.e., without the use of
devices), the shade or opacity of visible Air
pollution emissions for a set of 25 shades
of white smoke and 25 shades of black smoke:
(a) With an average error not to exceed
7.5 percent opacity in each, category.
("b)_ With an error not to exceed 15%
opacity (or 3/4 of a Ringelmann
Number), on any one reading in
each category.
Define Ringelmann Number and Equivalent
Opacity in the following manner:
(a). The Ringelmann Number gives shades of
gray by which the density of columns
smoke rising from a source may
be compared. It is a system whereby
graduated shades of gray, varying by
five equal steps between white and
black, may be accurately- reproduced
by means of a rectangular grill or by-
xi
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black lines of definite width and
spacing on a white background •
(b) Equivalent Opacity is an extension of
the Ringelmann Chart method of quantify-
ing visible emissions. The opacity or
degree to which a non-black or grey
plume obscures an observer's view is
related to the extent to which a black
or grey plume of a particular Ringelmann
Number obscures an observer's view. For
example, a Ringelmann Number 2 plume is
equivalent to a plume having 40% opacity.
(3) List the following essential conditions for
correctly evaluating the plume:
(.a). Keep the sun in the 140. sector to your
back.
(b)_ Try to have a contrasting background-
(c). Readings should he taken at approximately
right angles to the plume direction and
at any distance to obtain a clear view
of the emissions.
(d). Readings should be made through the most
dense part of the plume and in that
portion of the plume where condensed
water vapor is not present.
(e)_ When observing emissions from rectangu-
lar outlets, readings should be at
approximately a right angle to the.
longer axis of the outlet.
(f) The observer shall not look continuously
at the plume, but instead shall observe
the plume momentarily at 15-second
intervals.
xii
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(41 List the following essential items to be
recorded on the training form:
(al Name (d) Wind speed
(b) Date (e)_ Wind direction
(c). Time (f) Sky condition
and properly fill out these items for his
field recording form.
(31 List at least four of the following techni-
ques (even though not generally in use)_ for
measuring visible emission:
(a) Smoke guide (d)_ Smokescope
(b). Umbrascope (e)_ Smoke tintometer
(c) Photo-electric
cell
(.61 Differentiate between the plumes emitted from
combustion processes and industrial processes.
(.7). Identify condensed water vapor plumes and
breakpoint.
(.81 Make application of his knowledge of meteoro-
logy in the following manner:
(a). Estimate wind speeds from 0-18 mph using
the Beaufort Scale
(bl Define wind direction and estimate wind
direction
(c) Estimate sky condition (percentage of
cloud cover).
(41 List the distinguishing characteristics
of high and low pressure areas
(el Identify on a weather map the symbols
for the following:
high, pressure area
low pressure area
xiii
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cold front
warm front
occluded front
stationary front
(f) List at least two points of information
obtained from a weather map which the
smoke inspector could find useful in
planning his activities.
(9). Testify in court as an effective expert wit-
ness concerning visible emissions observa-
tions. To demonstrate his capability he
should be able to:
(a) Identify 8 of the 10 criteria for being
an expert witness
(b) List 5 of the 8 rules for behavior on
the witness stand
(cX Cite the legal precedents set in the
California appeal cases concerning
visible emission regulations.
(10). State the essential elements of his local
or state visible emission code.
(11). List the primary components of the emission
generator:
(a)_ Combustion chamber for generating black
smoke
(bX Generator's exhaust manifold for white
smoke
(c)_ Transmissometer
(dX Auxiliary blower
(e) Recorder or indicator.
xiv
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CHAPTER I.
VISIBLE EMISSIONS:
THEIR CAUSE AMD REGULATION
1.1 Visible emissions are composed of small solid or
liquid particles or colored gases.
1.2. The more opaque a plume is from a specified source,
the more effluent is being emitted, all other partlc-
ulate and flow characteristics being equal.
1.3.. Some invisible pollutants such as colorless gases
cannot be detected by the naked eye, e.g., S02, CO.
1.4. The micron (y) is a unit of length used to
measure particle diameters. It is equal to 0.001 (one
thousandth) of a millimeter.
1.5. Particles between 0.1 and 100 y are considered
suspended particulates in the atmosphere and are those
normally collected .by high volume samplers.
1.6. Particles between 0.1 and 1.0 y are most capable
of causing haze. They cause sunlight to scatter in the
visible wavelengths (0.4 to 0.7 y) of light. Larger
particles are visible because they intercept or reflect
the sunlight. Smaller particles have little effect on
the light and are invisible.
1-1
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1.7. Visible air contaminants can be classified as
(a) Smoke (e) Fumes
(b) Soot (f) Mist
(c) Fly ash (g) Certain gases
(d) Dust (h) Vapor
1^8. Plumes of condensed water vapor are visible, but
uncombined water is generally not considered a pollutant.
1.9. Smoke is a visible effluent"resulting from incom-
plete combustion and consisting mostly of soot, fly ash,
and other solid or liquid particles.
1.10. Soot is a cluster of carbon particles saturated
with tar. It is formed by the incomplete combustion of
carbon-containing material. It is the principal cause
of the blackness of a smoke plume.
1.11. Fly ash is unburned material arising from the
combustion of fuel. It has sufficiently small size that
it can remain suspended in the air. A pure fly ash
plume will be of a light-brown or cream color.
1.12. Fumes consist of metal or metal oxide particles
less than 1 y in diameter. These are minute solid
particles generated by the condensation of vapors from
solid matter after volatilization from the molten state.
1.13. Dust consists of solid particles, generally
greater than 1 y in diameter, released to the air by
processes such as crushing, grinding, drilling, sweeping,
sanding, demolishing, etc. Since they are larger than
the smoke or fume particles, they will settle to the
ground faster.
1-2
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1.14. Mist consists of liquid particles or droplets
which are not composed of pure pollutant but contain it
in solution or suspension. The droplets are of the size
of fog droplets (about 10 y — ranging from 2 to 200 y).
1.15. Gas is fluidf such as air that has neither
independent shape or volume but tends to expand indef-
initely. Two visible pollutant gases are nitrogen
dioxide (N0_), which is brown to yellow, and chlorine,
which is greenish yellow.
1.16. Vapor is the gaseous phase of a substance that
at normal temperature and pressure, is a liquid or solid,
e.g., vapor from gasoline.
1.17. Most visible plumes are composed of particulates.
The reasons for particulates being objectionable are
their effects on
(a) Materials (d) Health
(b) Visibility (e) Vegetation
(c) Incoming sunlight
The effects of Items (a) through (e) are discussed in
1.18 through 1.22.
1.18. Materials. Particulates deposited on clothes,
automobiles, or houses must be washed off. When partic-
ulates are accompanied by sulfur dioxide and moisture,
the rate of corrosion increases.
1.19. Visibility. Particulates in the air reduce the
distance that one can see. If this visual range is
decreased enough, it can cause unsafe operation of
vehicles and aircraft.
1-3
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1.20. Incoming sunlight. Particulate matter in the air
can cause the sun's rays to be reflected or scattered,
reducing the heat and light reaching the earth's surface.
1.21. Health. Increases in respiratory illness and
even deaths may occur from high particulate concentra-
tions, especially when sulfur dioxide concentrations are
also high. Bronchitis patients will experience symptoms;
particles less than 5 y in diameter can reach the lungs.
1.22. Vegetation. Cement dust can reduce vegetation
growth and cause its damage. Fluoride dust in the
presence of water can damage leaves. If the fluoride
dust is deposited on plants that are.eaten by animals,
the animals can contract fluorotic poisoning.
1.23. Regulations for restricting particulate emissions
are in common use. The regulations are typed by
(a) Weight concentration, which states the limit
in relation to amount of flue gas emitted:
e.g., 0.20 Ib of particulates/ 1000 Ib of flue
gas; 0.03 grains/std cu ft of flue gas at
atmospheric pressure and 60 F.
(b) Mass emission and process weight, which states
the limit in relation to the amount of material
processed, e.g., 12 Ib/hr of particulate for
10,000 Ib/hr of process weight.
(c) Limitation on basis of thermal input in terms
of British thermal units (Btu). Example: For
coal-fired boilers of less than 10 million
Btu/hr heat input, the emission of fly ash and
other particulate matter shall not exceed 0.6
pound of particulate matter/million Btu.
1-4
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(d) Boundary-line measurements of ambient air
quality. Example: The suspended particulate
outside the factory fence shall not exceed a
3
24-hour average of 200 micrograms/m .
(e) Plume shade density or opacity in terms of
Ringelmann Number or its extension to Equiv-
alent Opacity. Example: No emission as dark
or darker than that designated as No. 2 on the
Ringelmann Chart is allowed for a total of
more than 3 minutes in 1 hour.
1.24. The regulation using the Ringelmann Chart and
Equivalent Opacity is the least time consuming and the
least expensive for enforcement by the air pollution
officer.
1.25. Method 9 (40 CFR Part 60 App. A.) refers
to all visible emissions, black, white, or colored in
terms of opacity. (See current Method 9 procedures
later in this manual.)
Suggested Additional Reading
"Effect on the Physical Properties of the Atmosphere,"
E. Robinson, in Air Pollution edited by A. C. Stern.
Vol. 1, second edition, 1968. Vol. 2, ;third edition,
1976. Academic Press, 111 Fifth Avenue, New York, NY
10003.
1-5
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CHAPTER II.
PRINCIPLES OF
COMBUSTION
2.1. Combustion or burning is the rapid oxidation of a
fuel. This chemical reaction between the fuel and
oxygen requires a high temperature.
2,2. Most common fuels contain carbon and hydrogen plus
sulfur and ash materials. The ash does not burn, but
•ne cc-.rbon, hydrogen, and sulfur each combine with oxygen
.icd o roduce heat and waste gases.
2.3, Two parts hydrogen plus one part oxygen equals two
psrts
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compounded with the carbon to form complex tars, resins,
etc.; the sulfur is combined with other compounds or
with elements such as iron.
2.7. Thus, to make sure in practice that all the car-
bon and hydrogen combine with oxygen, three -conditions
must be maintained in the furnace—the "three T's of
combustion":
(a) Sufficient time for the molecules of
oxygen to come into contact with the
molecules of fuel.
(b) An adequately high temperature to sustain
the reaction.
(c) Turbulence or mixing to make sure that all
the molecules of fuel are combined with
the oxygen in the air.
2.-8. One result which will occur if the "three T's"
are not sufficient is that carbon monoxide will be
formed, since insufficient oxygen will combine with
the fuel—two parts carbon plus one part oxygen equals
two parts carbon monoxide:
2C + 02 2CO
2.9. Even with the "three T's," iurnaces are generally
not so efficient as to insure that every molecule of
-hydrogen and carbon will be combined with a molecule
of oxygen. One remedy for this is to use more oxygen
than is theoretically necessary. This extra oxygen is
supplied by using excess air. However, there is a
penalty for using this excess air, since some of it
becomes heated and goes out the stack as part of the
flue gas. This heat used to raise the temperature of
the excess air is wasted.
2-2
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2.10. Methods used to increase the effect of the
"three T's of combustion" in furnaces which are
listed below include the following:
2.11. Temperature
(a) Heat the air before it enters the
furnace.
~.«_ (b) Insulate the combustion chamber of
the furnace.
2.12. Turbulence
(a) Put baffles in the combustion
chamber.
(b) Introduce jets of air which stir
up the air within the furnace as
well as adding more air.
-^tt-a. :• -
2,13. Time
(a) Use baffles that also cause the
fuel and air to remain in the
combustion chamber longer.
(b) Build the combustion chamber
large enough so that the fuel
_ ._. and air will remain inside
13»u .-®
long enough for the combustion
to be completed.
i
2.14. If some of the fuel does not receive enough^
olTTteat to burn "all the carbon, the ash will contain
some pieces of partially burned or unburned carbon.
When these particles are deposited on something, the
deposit is called soot. When the particles remain in
±on in the flue gas, they form a black cloud
called smoke.
2-3
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2.15. If a furnace produces smoke, either the fuel
and air are not in balance or the "three T's of
combustion" are not being satisfied. One should look
for one or more of the following conditions:
(a) Insufficient air for the amount of
fuel;
(b) Too much air, which chills the
flame before combustion is
complete;
(c) Insufficient turbulence of the
air through the fuel;
(d) Cold furnace when the fire is
first lit or is burning at a
low load—this is often accom-
panied by excessive air leaking
into the furnace through doors
and other holes.
2.16. All fuels or combustible materials, whether
solid, liquid, or gas, are burned as a gas. Before it
will burn, a solid or liquid must be hea:ed until it is
transformed into the gaseous or vapor state.
Movie; "The Three T's of Combustion"
2.17. Several components of the kerosene lamp are
analogous to the components of other combustion units,
whether they be coal- or oil-burning furnaces, incine-
rators, internal combustion engines, or other devices.
The necessity for time, temperature, turbulence, and
oxygen is universal among all combustion devices
including the simple use of the kerosene lamp.
2-4
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2.18. The parts of a kerosene lamp include:
(a) The glass container at the base
of the lamp where the kerosene
is stored; this corresponds to
a coal bunker or fuel tank.
(b) The wick through which the kero-
sene is transferred from the
storage to the burning area; this
is similar to a coal stoker or
a fuel line and fuel pump.
(c) The grate where the fuel is burned.
(d) The tuyere or diffuser above the
top of the wick; the tuyere breaks
up the fuel for better mixing with
the air. Its function resembles that
of an atomizer in a fuel burner, an
injection nozzle in a diesel engine,
or a carburetor in a gasoline engine.
(e) The lamp chimney, which serves as an
enclosed area in which the combustion
can take place and also as an outlet
for the exhaust gases. The combustion
area corresponds to the combustion
chamber of a coal furnace or jet engine
and to the cylinder of an automobile.
The exhaust portion is similar to a
smoke stack or a tail pipe.
2.19. There are several examples given in the film
which emphasize that incomplete combustion will occur
if any one of the "three T's of combustion" is lacking.
2-5
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2.20. Without the tuyere to diffuse the fuel, there
is a smoky fire because the fuel cannot be intermixed
vvith e sufficient amount of air fot complete corn-
bus tier. -
2.21. Even with the tuyere the flame remains smoky,
because the cool ambient air reduces the temperature
cf the kerosene-air mixture below the combustion
temperature. When the chimney is placed on the lamp,
the air can enter the lamp only belcv the tuyere. The
fuel and air above the tuyere can circulate around in
the vide part of the lamp chimney thus remaining at a
high temperature for a time sufficient for complete
combustion.
2.22. At first, the lamp chimney glass is cold and it
cools the fuel-air mixture, causing a smoky flame. As
the chimney xjarms up, the glass radiates heat back to
the air-fuel mixture within and maintains the combustion
temperature. The. design of the interior cf furnaces
and the choice cf refractory material to line the walls
are directed toward reflecting the heat of combustion
on particular zones or areas within the furnace.
2.23. If there if. too much air for the amount of fuel,
then some of the heat is used to warm the excess air
and is wasted. The. temperature cf the gas leaving the
combustion area is reduced.
2.24. If there is insufficient air for the amount of
fuel, the temperature oc the exhaust g^ses will "ise
but there will be a dense cloud of black smoke. This
indicates thr.t fuel is being wasted. A diesel engine
can be adjusted to give more power by using excess
fuel, although with the detriment cf creating a black
plume.
2-6
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2.25. The film mentions two other ways of increasing
the amount of air and eliminating-'smoky conditions
>
besides controlling the amount of air entering the lamp
below the flame:
(a) Building a higher chimney so that the
air pressure from the bottom to the
top of the lamp chimney is increased.
This increased draft pulls air into
the combustion chamber at a greater
rate.
(t>) Raising the bottom of the lamp
chimney above its bases allowing
air to enter above the grate.
This additional overfire air
eliminates the smoky flame, but
it also cools the flame causing it
to flutter and have a smoky tip.
Suggested Additional Reading
Anon, North American Combustion Handbook, 1st Ed.
North American Mfg. Co., Cleveland, Ohio (1952)
Edwards, John B., "Combustion-Formation and Emission of
Trace Species," Ann Arbor Science Publishers, Inc.,
P. 0. Box 1425, Ann Arbor, Michigan 48106 (1974)
"Field Surveillance and Enforcement Guide: Combustion
and Incineration Sources," U.S. EPA Publication No.
APTD-1449, Research Triangle Park, N.C. 27711 (June 1973)
2-7
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CHAPTER III.
COMBUSTION OF FUEL OIL -
CORRECT PRACTICES
Classification of Fuel Oil
3.1. The crude oil that is pumped out of oil wells
consists of 83 to 87 percent carbon and 10 to 14 per-
cent hydrogen combined as hydrocarbons. It also con-
tains traces of oxygen, nitrogen, and sulfur.
3.2. The crude oil is refined; this consists of
separating and recombining the hydrocarbons of the
crude oil into gasoline, fuel oil, etc. The refining
process includes distillation and, often, cracking.
3.3. By boiling the crude oil, distillation separates
the hydrocarbons into groups or "fractions" which have
the same range of boiling points. The fractions also
vary in density.
3.4. The lighter fractions, such as naphtha, gasoline,
kerosene, and gas oil, are called the distillates. The
heavier fractions include asphalt and the heavy fuel
oils, are called residuals. During distillation, the
sulfur-bearing compounds and the ash originally present
in the crude oil are concentrated in the residual frac-
tions.
3.5. Products of simple distillation are called
straight run. Additional yield of gasoline can be
obtained by cracking the heavier fractions.
3-1
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3.6. Cracking consists cf changing the hydrocarbon
structure of the oil. This is done by decomposing the
oil through the application of heat and pressure with
or without a catalyst. The resulting products then are
distilled again into heavy and light fractions.
3.7. There are five grades of oil used as fuel oil,
labeled as Numbers 1, 2, 4, 5, and 6. Number 6 is
often called Bunker C. There no longer is a Number 3
oil.
3.8. Numbers 1 and 2 are distillate fuel oils generally
used for home oil furnaces and hot-water heaters.
3.9. Numbers 4, 5, and 6 are residual fuel oils. Both
Number 4 and Number 5 are used in commercial establish-
ments, large apartments, and industrial plants.
Bunker C (Number 6) is used in ocean-going ships, power
generation plants, and larger commercial and industrial
burners which use over 50 gallons of oil per hour.
3.10. Each of these oils has a set of standard specifi-
cations which distinguish it from the other oils. These
specifications may include flash-point temperature,
water and sediment percentage, gravity, ash, and sulfur
content, viscosity, and others.
3.11. The viscosity and the ash and sulfur contents
are the major characteristics that affect air pollutant
emissions.
3.12. The relative ease or difficulty with which an
oil flows is its viscosity. It is measured by the
time in seconds a standard amount of oil takes to flow
through a standard orifice at a standard temperature
(100°F or 122°F).
3-2
-------
3.13. Viscosity indicates how oil behaves when it is
pumped and shows when it must be preheated for handling.
^ Numbers 5 and 6 fuel oils are high viscosity oils and
often require preheating facilities.
3.14. The sulfur content of fuel oil may vary from a
trace to 5 percent while the ash may be as high as 0.3
percent by weight. The distillate fuel oils are limited
by specification to less than one percent sulfur and
Numbers A and 5 fuel oil are limited to no more than
0.1 percent ash.
3.15. The sulfur content of the residual fuel oil
grades can be reduced by desulfurization processes or
by blending low sulfur oils with the higher sulfur oils.
3.16. Crude oil contains thousands of hydrocarbon
compounds which are classified as paraffins, naphthene,
aromatics, resins, and asphalt.
3.17. If an oil is high in paraffins, the temperature
of the flame will cause them to decompose into lighter
and more volatile fractions which burn easily.
3.18. Aromatics do not readily decompose, but at
temperatures at which they do, cracking will occur which
can produce tar, smoke, and soot.
3.19. The olefins may crack and form compounds which
are hard to burn.
Oil Burner Types
3.20. The principal types of oil burners which have
been developed demonstrate a capability of coping with
many possible variations in oils.
3.21. Oil burners do not burn oil. They proportion
the air and oil and mix them in preparation for
burning.
-------
3.22. Since all fuels burn as a vapor, the liquid oil
must either be converted to a gas in the burner
(vaporized) or divided into such small particles or
droplets (atomized) that heat within the combustion
zone of the furnace will vaporize the fuel during its
residence time in the combustion chamber of the furnace.
3.23. If the temperature of flame in the combustion
chamber is too low, incomplete combustion and smoke
emission will result. Cooling of the flame can occur
when the combustion chamber is too small or too much
air is introduced.
3.24. Oil burns like an onion peels, so it is necessary
for turbulence to provide sufficient air to complete the
combustion of each successive layer. Consequently, it
is important to mix the air and oil.
3.25. Vaporizing burners gasify the oil by heating it
within the burner. These burners are limited in the
range of fuels they can handle and are used only for
some residential furnaces and water heaters.
3.26. Atomizing of fuel oil can be accoirplished in
three ways:
(a) Using steam or air under pressure
.to break the oil into droplets
(b) Forcing oil under pressure through
a nozzle
(c) Tearing the oil film into drops
by centrifugal force.
All three methods are used in burners.
3-4
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3.27. With high-pressure steam - or air - atomizing
burners, the steam or air is used to break up the fuel-
oil stream at the burner tip. The auxiliary fluid,
moving at high velocity, atomizes the slower moving oil
stream as the mixture is emitted in the furnace. The
combustion air is introduced through registers around
each burner. When steam is used, it prevents the
entering-oil temperature' from dropping. This aids the
flow of high-viscosity oil and improves atomizing
characteristics.
3.28. Oil-pressure atomizing burners depend on high
fuel pressure to cause the oil to break up into small
droplets upon passing through the orifice.
3.29. Rotary-cup burners provide atomization by
centrifugally throwing the fuel from a rotating cup or
plate. These burners can be divided into two classes—
horizontal rotary and vertical rotary. The vertical
rotary is used only for domestic burners (under 10
gallons per hour).
3.30. Horizontal rotary cup burners are used for the
residual fuel oils. The oil is distributed on the
cup .- plate in a thin film. The primary air from the
burner fan is discharged through an air nozzle which
has vanes to give the air a rotary motion opposite that
of the oil. Additional air for combustion—secondary
air—must also be injected into the combustion chamber
for complete burning.
3.31. Mechanical atomizing burners employ both high oil
pressure and centrifugal action. The fuel oil is given
a strong whirling action before it is released into the
orifice. These are the burners most often found at
large steam power plants.
3-5
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3.32. The key to optimum oil burner operation is
careful control of fuel viscosity. A given burner
functions properly only if the viscosity at the burner
orifice is he]d between narrow limits.
3.33. If the viscosity is too high, effective atoroi-
zation does not take place. If the viscosity is too
low, oil flow through the orifice is too great, up-
setting the balance between combustion air and fuel.
3.34. Most heavy residual oil must be warm to allow
pumping. Preheaters are used to heat the oil and keep
it flowing. For high-viscosity oils, the preheater is
likely to be located at the supply tank. With oils of
lower viscosity, preheaters are often located at the
burner.
3.35. Before the oil reaches the burner, it is passed
through a strainer or filter to remove the sludge. This
filtering process prolongs pump life, reduces burner
wear, and increases combustion efficiency.
3.36. The most important consideration in combustion
chamber design is heat release, or British thermal unit
release per cubic foot of furnace volume. Too high a
heat release will result in excessive furnace tempera-
tures. Too low a heat release will result in excessive
cooling of the flame and smoking fires.
3.37. The size of the combustion chamber will determine
the heat release. The shape of the chamber will pre-
vent the flame from impinging on the sides of the
furnace where it would cool, resulting in incomplete
combustion and smoke.
3.38. Draft systems can be classified as natural,
induced, or forced, or combinations of these.
3-6.-
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3.39. Natural draft results from the difference in
pressure between the stack and the outside air. Stacks
that are too small for the firing rate will create back
pressure. Too large a stack will cause the same condi-
tions because of internal turbulence and too cool a
stack temperature.
3.40. .Induced draft systems require a fan that sucks
combustion products through the boiler and forces them
up the stack-.
3.41. .Forced-draft systems suck air in from the boiler
room, push it into the boiler, and force the combustion
products up the stack.
3.42. The burning of oil can produce sulfur oxides,
inorganic ash, nitrogen oxides, carbon, and unburned
hydrocarbons. The sulfur oxides and inorganic ash are
attributable to the fuel. The air contaminants affected
by burner design and operation are carbon, carbon
monoxide, aldehydes, organic acids, and unburned hydro-
carbons .
3.43. If a burner is operated properly, no visible
emissions should be caused by oxidizable air contami-
nants, and the concentrations of items such as alde-
hydes and carbon monoxide should be negligible. Thus,
when an oil-burning system smokes, emits appreciable
odor, or causes eye irritation, there is something
wrong in atomization, mixing, or burning. The burner
and fuil may not be compatible or the burner may not
be properly adjusted.
3.44. Incomplete atomization of the oil caused by
«
improper fuel temperature, dirty, worn, or damaged
burner tips, or improper fuel or steam pressure may
cause the furnace to smoke.
3-7
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3.45. A poor draft or improper fuel-to-air ratio may
also cause smoking.
3.4i. Other factors that may cause smoking are poor
mixing and insufficient turbulence of the air and oil
mixture, low furnace, temperatures, and insufficient
time for fuel to burn completely in the combustion
chamber.
3.47. There are two kinds of hydrocarbon combustion—
hydroxylation and decomposition (cracking).
3.48. Hydroxylation or blue-flame burning takes place
when the hydrocarbon molecules combine with oxygen and
produce alcohols or peroxides that split into aldehydes
and water. The aldehydes burn to form C0_ and H-0.
3.49. Decomposition or yellow-flame burning takes place
when the hydrocarbons "crack" or decompose into lighter
compounds. The lighter compounds then crack into carbon
and hydrogen, which burn to form CO- and H_0. A mixture
of yellow- and blue-flame burning is ideal.
Boilar Types
3.50. The vast majority of combustion equipment is used
to heat or vaporize water. These boilers and heaters
fall into three general classifications: fire-tube,
water-tube, and sectional.
3.51. In fire-tube boilers, the heated gases resulting
from combustion pass through heat-exchanger tubes while
water, steam, or other fluid is contained outside the
tubes.
3.52. Fire-tube boilers make up the largest share of
small- and medium-size industrial boilers including the
Scotch marine and fire-box types.
3-8
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3.53. In all water-tube boilers, the water, steam,
or other fluid is circulated through tubes while the
hot combustion gases pass outside the tubes. All
large boilers for steam generation are of this type.
The smallest and largest industrial units are likely
to be of a water-tube design.
3.54. Sectional boilers use irregularly shaped heat
exchangers and cannot be classified as either water-
tube or fire-tube types. Hot combustion gases are
directed through some of these passages, transferring
heat through metal walls to water or steam in other
passages. These units are manufactured in identical
sections which can be joined together. A sectional
boiler consists of one or more sections.
Soot Blowing
3.55. Whenever fuels of measurable ash content are
burned, some solids such as carbon and inorganic ash
adhere to heat-transfer surfaces in the combustion
equipment. These deposits must be removed periodically
to maintain adequate heat-transfer rates. It is common
practic.-. to remove these deposits with jets of air or
steam from a long, retractable soot blower while the
combustion equipment is in operation. These removed
soot particles are entrained in the combustion gases.
Thus, during these periods of soot blowing the plume
may have an excessive opacity.
3.56. Whenever residual fuel oils or solid fuels are
burned in large steam generators, tube cleaning is
usually conducted at least once during every 24 hours
of operation. At many power plant boilers, soot blowers
are operated automatically at 2- to 4-hour intervals.
3-9.
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3.57. When tubes are blowr at 2- to 4-hour intervals,
there is little, increase in the opacity of stack
emissions. Intervals of 8 hours or more between soot
blowing car result ir excessive visible opacities.
Black Smcktf: and White Smoke
3.58. When residual oils or solid fuels are burned in
a deficiency of oxygen, carbon particles and unburned
hydrocarbons impart a visible blackness to the exit
g£-se.s.
3.59. Visible, emissions ranging from gray through
brown to white can also be created by the combustion
of hydrocarbon fuels, particularly liquid fuel.
3.60. White or non-black smoke is the result of finely
divided particulates—usually liquid particles—in the
gas stream. These non-black plumes generally are caused
by vaporization of hydrocarbons in the combustion
chamber. This is sometimes accompanied by cracking and
the subsequent condensation of droplets. White smoke
frequently is attribxited to excessive combustion air
or loss of flame.
3.61. Visible plumes of greater than 40 percent opacity
are frequently observed at large oil-fired steam gene-
rators, where incomplete combustion is a relative rarity.
These opaque emissions are commonly attributed tc
inorganic pcrticulates and sulfuric acid aerosols formed
by the combination of sulfur trioxide, moisture, and
flue gases. The. condensation of the sulfuric acid aero-
sol may be enhanced by the presence of particulate
.matter, which provides condensation nuclei.
3-10
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Particulates
3.62. Where combustion is nearly complete, inorganic
ash constitutes the principal particulate emission. The
quantity of these inorganic solid particulates is
entirely dependent upon the fuel. Distillate fuels do
not contain appreciable amounts of ash. In residual
oils, however, inorganic ash-forming materials are
found in quantities up to 0.3 percent by weight, but
not to exceed 0.1 percent for grades 4 and 5. However,
even that amount, when emitted from efficient burning+
is not likely to exceed air pollution control statutes.
3.63. The particulates emitted from normal oil firing
are principally in the submicron range of diameters
where they can cause scattering of light. Over 85
percent of the particles from efficient oil burning are
less than 1 micron in diameter.
3.64. If incomplete combustion occurs and carbon or
hydrocarbon particles are emitted, then the average
particle size is larger.
3.65. If a light fuel oil is burned in a deficiency
of oxygen, the resulting carbon particles are likely
to be very fine. If a residual fuel oil is in-
completely burned, by heating it to a temperature of
only 200-300 C and then cooling it, the carbon particles
are likely to be in the form of cenospheres. Ceno-
spheres are hollow, black, coke-like spherical particles
of low density usually having a minimum dimension of
0.1 micron.
3.66. Particulates emitted from residual fuel oil
combustion consist of 10 to 30 percent ash, 17 to 25
percent sulfate, and 25 to 50 percent cenosphere.
3-11
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Sulfur Trioxide
3.67. Of the sulfur contained in fuel oil, about 95%
shows up in the exhaust gases as sulfur dioxide, a
colorless gas. Up to 5% of the sulfur may be converted
to sulfur trioxide. If the S0_ comes into contact with
surfaces below the dew point of the gas, the SO com-
bines with water vapor to produce sulfuric acid. This
sulfuric acid mist is visible.
3.68. Concentrations of S0_ are negligible in small
equipment, even vhen fired with high-sulfur fuel oils.
As the equipment sizes and firebox temperatures
increase, S0_ concentrations increase rapidly.
3.69. Large steam generators may emit S0_ mist of
greater than 40 percent opacity when fired with oil of
greater than 1.0 percent sulfur.
3.70. Sulfur trioxide tends to acidify particulate
matter discharged from combustion equipment. This is
commonly evidenced by acid spots on painted and metallic
surfaces as well as on vegetation. Acid damage generally
is the result of soot blowing.
3.71. Formation of S0_ depends upon several factors.
Concentrations of sulfur trioxide increase with
increases in
(a) Combustion chamber temperature;
(b) Oxygen concentration;
(c) Vanadium, iron, and nickel oxide content
of the fuel oil.
3.72. The visible plume from a large oil-fired unit
normally varies from white to brown, depending upon
weather conditions and the composition of the parti-
culate matter.
3-12
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3.73. In some cases, the SO- plume will be detached
from the stack. It will become visible at the point
where the sulfuric acid mist is cooled below its dew
point.
3.74. Deposits of dirt which cannot be removed by the
normal soot blowing of the heat-exchanger tubes act as
catalysts oxidizing SO- to SO-, with an increased
opacity of the plume resulting. These deposits can be
removed by washing, but only at the infrequent inter-
vals when the steam generator is out of service.
Control Equipment
3.75. Until recently, the only air pollution control
devices that have found ready acceptance on oil-fired
power plant boilers were multiclones and low draft loss
separators used to control particulates during soot
blowing. Now some oil-fired power plants have in-
stalled electrostatic precipitators to control the
particulate emissions.
3.76. Use of cyclone type collectors during normal
operations is worthless since the collectors are not
efficient in removing particulates of less than 5-
microns diameter, which is the range in which over 95
percent of the oil-fired emissions lie.
3.77. The use of electrostatic precipitators for oil-
fired power plants is limited to areas where restrictive
legislation requires low particulate emissions and low
opacity of stack effluents. They collect nearly all the
particulates including the liquid sulfuric acid drop-
lets. The particulate loading may be decreased by as
much as 90 percent and the SO, emission may be cut in
half.
3-13
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Suggested Additional Reading
Emissions From Fuel Oil Combustion, W. S. Smith. DHEW,
PHS PubJicaticr Ho, 999-AP-2, (1962).
"Stationary Combustion Emissions," R. B. Engdahl, in
Air Pollution Vol. 3, edited by A. C. Stern. Academic
Press, Inc., Ill Fifth Avenue, New York, N.Y. 10003
(1968).
Air Pollution__ Engine &jrin_E Mar.ual, 2nd Edition, edited
by J. J. Da'nielson, U. Si E?A AP-40, 1970, available
through National Technical Information Service, 5285
Fort Royal Road, Springfield, VA 22161.
3-H
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CHAPTER IV.
COMBUSTION OF COAL
AND ITS CONTROL
Classification of Coal
4.1 The types of coal are
(a) Anthracite (hard coal),
(b) Bituminous (soft coal),
(c) Lignite (brown coal).
4.2. Anthracite coal is mined in Pennsylvania, Rhode
Island, and Arkansas.
4.3. There are 23 districts in the United States which
mine bituminous coal.
4.4 Anthracite is less smoky and gives off less sulfur
dioxide, but it is not as abundant as bituminous.
4.5. After coal is mined, it is generally prepared
before it is used. Raw or unprepared coal is used in
some power plants—mine mouth plants. Preparation of
coal includes crushing and cleaning to remove impurities,
drying to remove moisture, and separation into the
desired sizes.
4.6. Two basic methods are normally used to describe
the composition of coal: the Proximate Analysis and the
Ultimate Analysis.
4.7. Proximate Analysis gives the percentages by weight
of the following which are found in the coal:
(a) Volatile Matter - portion of the coal that
will form gases and vapors (hydrocarbofln,
4-1
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hydrogen, and carbon monoxide)
and are driven off when the coal sample is
heated in a covered crucible at 1740 F for
7 minutes.
(b) Fixed Carbon - solid portion
that is left when volatile matter
is distilled off. It is mostly
carbon, burns slowly, and will
give a bluish flame.
(c) Ash - portion that will not
burn. Slate, clay, sandstone,
shale, carbonates, pyrite, and
gypsum.
(d) Moisture Content.
The sulfur content in percent and the heat content in
British thermal units per pound (Btu/lb) are generally
also given, although they are not part of the analysis.
This Proximate Analysis may be made on the coal as
received (AR) or dry (excluding the moisture).
4.8. The Ultimate Analysis gives.the chemical com-
position of the coal by dividing the ccal, except for
the ash, into its basic elements.
4.9. In the Ultimate Analysis the volatile matter and
fixed carbon of the Proximate Analysis are divided into
their''chemical compohents-'-hydrogen, carbon, oxygen,
and nitrogen. - .
4.10. Another measurement which describes the coal is
the Screen Analysis, or-Size Distribution. It tell the
percentage of the coal that will fall through a screen
with a certain size opening but which will not fall
through the next smaller size screen.
4-2
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4.11. The Screen Analysis can be made with a screen
having either round or square holes, but the two screens
will give different totals. Thus, the type of holes
should be specified.
4.12. Coal sizing terms:
Run of mine - unscreened broken coal
from the mine
Slack - all the coal passing through a
screen of a given size, such as
3/4" slack.
Double-screened sizes such as "egg^"
"stove," "nut," "pea," and "stoker" -
trade names in bituminous coal that
are standard sizes for anthracite.
4.13. From the air pollution viewpoint, the amounts of
volatile matter, ash, and sulfur, along with the heating
value, are the most important part of the Proximate
Analysis. Volatile matter is related to the emission of
smoke; ash is related to particulate emission. Sulfur
content is related to sulfur oxide emissions. Heating
value ic related to the total amount of pollutant
production.
4.14. The size of the coal is important to the smoke
and flue dust emission. The optimum coal size is
determined by the method of firing.
4.15. The impurities in coal are ash, moisture, and
sulfur.
4.16. The ash is dispersed throughout the coal as
finely divided matter or is present as pieces of slate,
rock or clay. The pieces of ash can be removed in
preparation plants by crushing and washing.
4-3
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4.17. Power plants usually burn higher ash coals, while
lower ash coals go to the retail market.
4.18. Moisture may be present as finely divided amounts
of water dispersed throughout the coal or as water
clinging to'the coal surface. A certain amount of
moisture is helpful in reducing the tendency of coal
tc forir. strong coke in some stokers. It also prevents
a dust problem.
4.19. Sulfur is fcund in coal in three forms:
• •' (a) As ar iron disulfide, FeS~, called
pyritic sulfur or as golden-colored
iron pyrites in the form of very heavy
balls or lenses and in small flakes or
crystals or bands as partings. This
sometimes is called "Fools Gold."
(b) Organic sulfur originating with and
forming an inherent part of the plant
life that formed the coal.
(c) Combined sulfur, generally a sulfate
with calcium or other mineral matter
-and seen as a gypsum with a white
surface or as veins in the coal.
High-sulfur coal is characterized by the fact that
content of all three forms of sulfur is high. Very
often with high-sulfur coal, the pyritic form will be
as prevalent or more, so than the organic and sulfate
forms combined.
4.20. The pyritic sulfur is found in small discrete
particles within the coal; a percentage of this sulfur
may be removed by washing or other mechanical means.
However, even after washing, most of the pyritic sulfur
and all of the organic sulfur will remain in the coal.
4-4
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4.21. At present, no economical means is in general use
for the removal of any of the organic or sulfate forms
of sulfur from the coal prior to its initial use.
Basics of Coal Combustion
and Combustion Equipment
4.22. Some of the terminology describing characteristics
of most coal-burning furnace systems are as follows:
(a) Fuel bed - layers of coal distributed
over a grate which allows the air to
move through the coal layers.
(b) Stoker for feeding fuel - by which
coal can be added to the bed from
above (overfeed) or below (under-
feed) .
(c) Air - which can be introduced be-
neath the coal burning on the fuel
bed (underfire air) or above it
(overfire air).
(d) Arch - the portion of the combustion
chamber above the fire; it is con-
structed of material capable of
withstanding high temperatures
(refractory material) and is of a
design that will reflect the heat
back into the fire.
(e) Heat-exchange equipment - converts
the heat released by the coal into
a form that can be used; frequently,
the heat exchange is accomplished by
placing metal tubes at the exit of the
combustion chamber and converting the
water in these tubes to steam.
4-5
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(f) Breeching - originally, the connecting
link between the furnace and the chimney;
currently, one may expect to find one
or more of the following between the same
two points: (1) economizer, (2) air
preheater, (3) fly-ash collector (mechanical
and/or electrical), and (4) induced draft
fan. In effect, the breeching thus becomes
a series of, short duct-work connectors.
(g) Chimney - transports the waste products of
combustion out into the air for disposal
by dispersion.
4.23. Coal will not burn as a solid; no fuel will.
The combustion process must vaporize, gasify, or break
down a solid into individual molecules by the addition
of heat.
4.24. When coal is burned on grates, one of two types
of feeding mechanisms is generally used—underfeed or
overfeed.
4.25. The underfeed operation introduces the primary
air and the fuel from below the grate. The fuel burns
from the top to the bottom of the bed.
4.26.- Overfeed operation introduces coal to the grate
from the top and the primary air from below. Burning
occurs from the bottom to the top of the fuel bed.
4.27. When coal burns in an overfeed bed on a grate, the
process takes place in layers:
(a) At the bottom of the bed and above the
grate where a layer of ash serves to
protect the grate and preheat the primary
air.
4-6
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(b) The "oxidation zone," where, as the air
temperature rises, the heat vaporizes the
volatile and carbonaceous material from
the coal particles and removes this material.
In this vaporous state the combustible
material burns in the reaction:
C + 02 - C02-
This is the hottest part of the fuel bed.
(c) The "reduction zone," where, because of the
lack of oxygen, the carbon dioxide combines
with the volatilized carbon forming carbon
monoxide.
(d) The top layer, where the volatile hydro-
carbons and tars are driven off the fresh
coal.
4.28. Unless more air (secondary air) is introduced,
the hydrocarbons and tars crack, decompose, or condense
and are emitted to the atmosphere as white, yellow,
or black smoke. If oxygen is present in sufficient
quantity at the time the volatile matter is distilled,
the hydrocarbons oxidize completely without forming
soot "uu? smoke through the thermal cracking and con-
densation reactions. Secondary air is sometimes called
combustion air and, since it is introduced above the
fire, it is often identical to "overfire air."
4.29. Overfeed fuel beds are smoky because burning
gases rise through fresh fuel, thus resulting in rapid
devolatilization of the fresh fuel in a zone having a
deficiency of oxygen.
4-7
-------
4.?C. Underfeed bt-ds are inherently snicke free. The
£.ir anc! fres;h fuel ilov/ upward together. The zone of
igniticr., which is near the point of maximum evo3.uti.on
of the con.bustihJ e gases, is. supplied with ample well-
irixed air which promotes complete cctrbusticn.
4.3.1. Heat-e>;chcp£e equipment converts the heat released
by the burning of the coal into a form that can be used.
There are five categories:
(a) Padiant heat absorbers - car. line
furnace vails with wate.rc.ooied surfaces.
The&e surfaces transmit to the water
the heat which is radiated to them.
(b) Boilers or convection heat exchangers -
the earliest boilers were tanks containing
water under which a fire was built. Next,
the heated gases from the furnace were
directed around the water tank and. through
a large tube, which passed through the
tank. Next, this return tube was re-
placed by many small tubes (3 or 4-in. ID).
There are three types of boilers in use
currently:
(1) Fire-tube boiler -
fire is itade in the large
tube and the gases make
several passes through the
smaller tubes.
(2) "Fire-box" boiler -
gases flow frcir the furnace
through tubes, then reverse
and flow through more tubes
to the stack.
4-8
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(3) Water-tube boiler -
water goes from a drum
through several straight
tubes to another drum.
(c) Superheaters or gas-to-vapor heat
exchangers.
(d) Economizers or added-convection
heat exchangers.
(e) Air preheaters or gas-to-gas heat
exchangers.
Some Terms Used in
Coal Combustion
4.32. Draft is a measure of the positive pressure or
negative pressure (vacuum) or air or gases in various
parts of a combustion system. There are several types
of draft:.
(a) Forced draft - air pressure is supplied
by a fan pushing air into the system.
(b) Induced draft - a negative pressure
is created by pulling air out of the
system with a fan.
(c) Natural draft - suction in the system
is created when the flue gases expand
and go up the stack. This causes pri-
mary air to be drawn into the furnace
system to balance out the negative
pressure.
(d) Furnace draft - the pressure of the gases
in the furnace is positive or negative.
4-9
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If it is positive, the gases V7ill
leek out of the. furnace. If it is
negative, gases will leak in.
•
(e) Draft losses - pressure, losses occur
as the flue gas flows through the
combustioi; system.
In principle, both natural and induced drafts are akin
in that they both function from the exhaust or discharge
end of the furnace system. Forced draft functions from
the opposite or feed end of the system.
A.33. Coke is the fixed carbon and ash which are left
after the coal has been heated.and the volatile matter
has been driver, off. Coking coal refers to a coal that
melts and fuses to form larger lumps, even though the
coal may have been in small pieces. Bituminous is
usually a good coking coal and anthracite is not.
4.34. Carbon in the ash - if some of the coal is heated
enough to. drive off the volatile matter but does not
finish burning all of the carbon, the ash vill contain
some pieces of unburned carbon or coke.
4.35. Overfire air - air is injected above the fuel
bed instead of through it as is normal. The overfire
air is forced through jets or nozzles in the furnace
walls. The purpose of the overfire air jets is to
increase the mixing or turbulence of the gases to insure
complete combustion and prevent smoke.
4.36. Slagging - when molten ash particles build up on
the v;alls or tubes of 3. boiler and flow together, the
deposit is called slag and the process is celled slagging.
4-10
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Plume Visibility
4.37. The visible plume from coal combustion may be
caused by condensed water vapor, sulfur trioxide/sulfuric
acid mist, organic liquids or solids, particulates,
and smoke.
(a) Water vapor condenses and produces
a white plume which dissipates rapidly.
(b) Sulfur trioxide and sulfuric acid mist
cause a detached bluish-white plume that
does not dissipate readily.
(c) Organic liquids and solids cause a
white, yellow, or brown plume.
(d) Particulates (including fly ash)
cause the plume to be white, brown,
or black.
4,,38. Smoke - the black clouds called smoke are
actually small, unburned or partially burned solid
carbon particles and solid or liquid hydrocarbon
particles. They result from the incomplete combustion
of the volatile products of the fuel. The carbon of
the smoke does not arise from the free carbon of the
fuel but from the cooling of the hot hydrocarbon gases
of the volatile matter. If these particles are depos-
ited inside the combustion system, they are called soot.
4.39. Once formed, carbon soot is difficult to burn.
To prevent this soot from being carried away as pollution,
the hydrocarbons should be burned as close as possible
to the fuel bed before they are decomposed by the heat
into soot and smoke.
4.40. It has been found that there is a marked rise in
the percentage of both carbon (soot) and tar (benzene
soluble) contained in the particulate as the smoke density
increases.
4-11
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£.41. The black r.mckt- picirif is-, visible because of the
size cf its solid end liquid particles. They range
between 0.01 and 2.0 microns in diameter, bvt meat are
between 0.3 and 0.6 ir.icrcn, a size which is highly
effective in scattering <.r absorbing light.
i.£2. These particles between 0.3 and 0.6 ir.icrcn in
diameter contribute, little to the mass of the emissions.
i'ost cf the r.ast. is ir the larger particles, which have
little el feet in absorbing cr scattering light.
4.^.3. The black shade of a combustion plune can be
reduced by s good adjustment of air-to-fuel ratio.
One indication of this is the flame in the furnace:
(a) With a good adjustment of air to the
coal feed, the flame will be yellowish
orange in color with nc black tips. It
will appear soft. And its luminosity will
give a maximuir of radiant heat-energy
transfer.
(b) If the air is increased, the flame
will become whiter in color and will
• appear to be harder, sharper, and more.
erosive. Its radiant heat energy will
be lessened.
(c) If the air is decreased toe much,
the flame will be blacker and will
appear lazy and without life. Since
a reducing atmosphere is now well
indicated, scot may be formed and
collect at some point in the system.
The smoke will be. dark.
4-12
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(d) When complete burning of coal
is accomplished, visible emissions
will range from zero to a light
tan er gray haze depending on the
ash content of the fuel and the
efficiency of the emission control
equipment.
4.44. When a flame impinges on a cold surface, smoke
and soot are formed. Complete combustion should be
obtained before the flame is allowed to hit a cold
surface.
Mechanical Coal-Firing Equipment
4.45. Overfeed stokers - earliest type consisted of a
steeply inclined grate with alternate stationary and
movable sections. Coal moved down the grate when a
lever outside the furnace was moved.
4.46. Underfeed stokers - two forms: single retort
and multiple retort.
4.47. Single retort - consists of coal hopper, one feed
trough or retort containing a feeding device (a screw
or pusher) with .the grate above it. This stoker moves
coal (a) from front to rear in retort, (b) from retort
upward to the grate where it is burned, (c) sideways on
the grate to the ash pits at the sides. Widely used
with smaller boilers.
4.48. Multiple retort - early variety had one coal
hopper across several parallel retorts. Ash was dumped
periodically from the rear into an ash pit. Later, all
the retorts were driven by a single crankshaft. They
require forced draft fans. There may be as many as 18
multiple retorts.
4-13
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4.49. Traveling grate stoker - grate surface, consists;
of an endless belt with sprockets at either end. Coal
hopper with e grate at one. end controls the coal feed.
Grate is moved with gears powered hy an electric motor
or turbine. Coal is laid or the grate frcm the hopper
and is moved through the furnace as the burning takes
place. Ash is dropped off the grate into an ash pit
at the rear. Presently forced-draft fans ?.re used with
traveling grate stokers.
4.50. Vibrating grate stoker - consists of a water-
cooled grate structure on which the coal moves from tl-e
hopper at the front of the boiler through the burning
zone by means of a high-speed vibrating mechanism. As
with the traveling grate, the fuel bed progresses to
the rear, where the ash is continuously discharged.
Vibrating stokers may eir.i t .slightly higher concentra-
tions of fly ash than traveling-grate stokers because
of increased agitation of the fuel bed.
4.51. Spreader stoker - consists of a coal hopper,
a feeding mechanism, and a device that injects the coal
into the furnace (usually a rotating flipper) . The
coal is thrown into the furnace and partly burned in
suspension. The larger particles fall to the grate, and
burn there. Essentially, the spreader stoker employs
overfeed burning, an inherently smokey method, plus
suspension burning, an inherently smoke-free method
producing fly ash. Overfire jets have been found
essential to smoke-free operation. They also reduce
dust emission significc'Titly, but not enough, to meet
most ordinances, unless a partic'ulate collector is
used.
4-14
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4.52. Pulverized-fuel firing unit - in this system,
coal is pulverized to particles, at least 70 percent
of which pass through a 200-mesh sieve (median size of
the particles is 5.0 microns). In direct-firing systems,
raw coal is dried and pulverized simultaneously in a
mill and is fed to the burners as required by the
furnace load. A predetermined coal-air ratio is
maintained for any load. In indirect-firing systems
there are storage bins and feeders between the pulver-
izers and burners. Pulverized-fuel firing units are
of two basic types—wet bottom and dry bottom. In a
wet-bottom unit, the temperature in the furnace is
maintained high enough so that the slag does not solidify
(or fuse) and it can be removed from the bottom as a
liquid. The dry-bottom furnace maintains a temperature
below this point so that the ash will not fuse. The
steam electric plants, where pulverized fuel firing is
used most, emit 50-80 percent of the ash fired in the
coal as fine fly ash. Therefore, all modern plants of
this type must have high-efficiency dust collectors.
A.53. Cyclone furnace - fires crushed coal that is
nearly as fine as pulverized coal into a water-cooled,
refrac .':ory-lined cylindrical chamber 8 to 10 feet in
diameter. The coal and air swirl in a cyclonic manner
as the burning proceeds. Combustion is so intense that
a small portion of the molten ash coating the wall of
the chamber is vaporized. Approximately 85 percent of
the ash fired is retained as molten slag; hence, the
fly-ash load is much lower than with pulverized coal.
However, the ash which does escape the cyclone is
extremely fine and thus difficult to collect.
4-.15
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4.54. Prlverized-coal burners and cyclone furnaces are
the universal equipment for firing coal in the large new
electric-generating stations.
4.55. Some types of burning equipment (underfeed stokers,
overfeed stokers, spreadt-r stokers, and pulverizec-fuel
burners) make use of a certain amount of fly-ash
ceinjection. In this process, cinders are returned to
the grate from the fly-*.yh collector and burned again
to reduce the loss of unburned carbon. The usefulness
of this nethod is limited, for whenever the fly ash is
re.injected pneumatically, the total fly ash from the
unit is eventually increased.
Causes and Control of Particulate
Emissions From Coal Combustion
4.56. Emissions of smoke and particulates nay be
caused by the type of coal, the type of combustion
equipment, or improper combustion.
4.57. Improper combustion - if a furnace produces
siaoke, either the fuel and air are not in balance or
the three T's of combustion are not being satisfied.
The cause may be. one. or more of the following conditions:
(a) Insufficient air for the amount of fuel;
(b) Improper distribution of the air or fuel;
(c) Too much air (usually overfire air),
which chills the flame, before all
combustion is complete;
(d) Insufficient turbulence or mixing of
the air;
(e) Cold fire box - often caused by excessive
furnace, draft, which pulls outside air
into the fire box through doors and leaks;
it usually occurs at low load.
4-16
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4.58. Possible causes for improper distribution of
air or fuel:
(a) Uneven depth of fuel bed,
(b) Plugged air holes in the grate,
(c) Clinker which shuts off air flow,
(d) Leaky seals around the edges of
the grate area,
(e) Improper burner adjustment.
4.59. Possible reasons for insufficient turbulence:
(a) Insufficient overfire air,
(b) Plugged overfire air nozzles,
(c) Nozzles that are improperly aimed,
(d) Incorrect burner adjustment,
(e) Excessive furnace draft.
4.60. Importance of coal and equipment in particulate
emissions:
(a) Type of firing - least emission occurs
with underfeed stokers, the greatest
with pulverized coal.
(b) Furnace design - least emission with large
furnaces and greatest with small furnaces
of pulverized coal furnaces.
(c) Secondary air jets tend to reduce emission.
(d) Coal size - the greater the proportion
of small sizes, the greater the emissions.
Smaller sizes are more easily swept up
the chimney.
4-47
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(e) Volatile content - high-volatile ccal
results in a long, opaque flame that.
is irore likely to strike the cooler
surfaces of the furnace resulting in
soot formation. Low-volatile fuel
burns with a short, transparent flame.
(f) Amount of ash - the higher the ash
content, the greater the emission
of fly-ash.
(g) . Fly-ash reinjection - if fly ash is.
reinjected, there can be an accumulation
in the furnace of suspended solids
formed from the combustible portion
of the coal.
(h) Firing rate - as the firing rate
increases, the velocity of the gases
passing through the furnace increases.
And as the velocity increases, more
and larger particles are carried out
of the furnace.
4.61. The most important variable in hand-fired furnaces
is the volatile content of the fuel burned, the smoke
potential .increasing rapidly as volatile content
increases.
4.62. Several types of control equipment have been
used to collect the particulates from coal combustion:
(a) Settling chambers,
(b) Large-diameter cyclones,
(c) Multiple small-diameter cyclones,
(d) Wet scrubbers,
4-18
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(e) Electrostatic precipitators,
(f) Fabric Filters (ir limited use
as of 1977).
4.63. The settling chamber is a low-efficiency, low-
cost, low-pressure-drup device. It generally is applied
to natural-draft, stoker-fired units. Collection
effic.ier.cy is 50 to 60 percent.
4.64. Large diameter cyclones have lower efficiency
and lower pressure drops than smaller diameter cyclones.
Their efficiency ranges from 65 percent for stoker-fired
units to 20 percent for cyclone furnaces.
4.65. Multiple sirall-diair.eter cyclone, units are used as
precleaners for electrostatic precipitators or as final
cleaners. Efficiencies range from 90 percent for
stoker-fired units to 70 percent for cyclone furnaces.
4.66. Wet scrubbers are limited to the control of
particulate emissions during soot blowing, although
alkaline scrubbers to remove both fly ash and sulfur
dioxide are also used.
4.67. Electrostatic precipitators are the most commonly
used devices for cleaning the gases from large, stationary
combustion sources such as those burning pulverized
coal. They are capable of efficiencies of 99 percent
or mere.
4.68. Efficiency of collection for cyclone collectors
increases ss the load increases. An increase- in the
carbon content of coal is usually associated with an
increase in size distribution. Thus, as firing rate
increases or the carbon content of the coal increases,
the centrifugal collector becomes more efficient.
4-19
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£.69. The electrostatic precipitator becomes less
efficient as the load increases. An increase in
carbon content is associated v-1tr an increase in
electrical resistivity. Electrostatic precipitators
are net generally used for high-carbon ash, which is
derived from stckeis. They are best adapted to
pulverized coal-fired and eyelone-fired units.
Suggested Additional. Reading
Atmospheric Emissions From Coal Combustion, W. S. Smith
and C. W. Cruber, DHEW, PHS Publication No. 999-AP-24,
(1966). Available through National Technical Information
Service, 5285 Port Royal Road, Springfield, VA 22161.
"Stationary Combustion Emissions," R. B. Engdahl, in
Air Pollution Vol. J3- edited by A. C. Stern, Academic
Press Inc., Ill Fifth Ave., New York, NY 1C003, (1968).
Emissions from Coal-Fired Power Plants, S. T. Cuffe and
R. W. Gerstle, DHEW, PHS Publication No. 999-AP-35, 1967.
Available through National Technical Information
Service, 5285 Port Royal Road, Springfield, VA 22161.
4-20
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CHAPTER V.
OTHER COMBUSTION EMISSIONS:
INCINERATORS, AGRICULTURAL BURNING,
NATURAL GAS AND MOBILE SOURCES
The combustion of coal and fuel oil in stationary
sources produces a large number of visible plumes.
More efficient combustion of these fuels can reduce
the opacity of the plumes produced from these sources.
Other types of combustion, both for the production of
usable energy and for the burning of waste materials,
will -produce black and non-black plumes. Some of these
combustion sources and the cause and control of their
plumes are discussed in this section.
Solid Waste Disposal by Incineration
5.1 The methods of burning solid waste include the use
of open-top or trench incinerators, conical metal
("tepee") burners, domestic incinerators, apartment-
house incinerators, and municipal incinerators as well
as open burning.
5.2 Incinerators can be classified in several ways,
such as by their size, their method of feeding, the
type of waste they will handle,, or the number of com-
bustion chambers they contain.
5.3 A single-chamber incinerator is designed so that
feeding .combustion, and exhaust to a stack take place
in one chamber.
5.4 The multiple-chamber incinerator has three or more
separate chambers in series for admission and combustion
5-1
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of the solid refuse, mixing and further combustion of
the fly ash and gaseous emissions, and settling and
collecting of the fly ash.
5.5. Multiple-chamber incinerators are of two general
types:
(a) Retort, in which the ignition chamber,
mixing chamber, and combustion chamber
are arranged in a "U".
(b) In-line, in which the three chambers follow
each other in a line.
5.6. The tepee burner has been used by the lumber
industry to incinerate wood wastes and by some small
cities to dispose of municipal refuse. These burners
range from 10 to 100 feet in height. They are single-
chamber incinerators and are not designed to minimize
atmospheric emissions; thus, they rarely meet visible
emission regulations when in use and have considerable
fly-ash fallout.
5.7. The tepee burner may be fed by a bulldozer, a
dump truck, or a conveyor. Feeding with bulldozers
or trucks requires that the doors at the base of the
burner be opened. This stops the motion of the draft
air inside the burner and cools the combustion gases.
The dumping of the charge on the burning pile smothers
the fire. All of these factors contribute to incomplete
combustion and additional smoke.
5.8. Domestic incinerators may range from units such
as a single-chamber backyard wire basket to dual-chamber
incinerators having a primary burner section followed
by an afterburner section. Many air pollution control
agencies have banned backyard incinerators and some
have banned all types of domestic incinerators.
5-2
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5.9. The emissions of smoke and fly ash from apartment-
house incincerators are often high because of low com-
bustion temperatures, improper air regulation, and poor
operating and maintenance practices.
5.10. Apartment-house incinerators may be of two types—
flue-fed and chute-fed. In the single chamber-flue-
fed unit, refuse is charged down the same passage that
the products of combustion use to leave the unit. Re-
fuse dropped onto the fuel bed during burning smothers
the fire, causing incomplete combustion and emission
of smoke. Unless controlled by an approved type of after-
burner or other equivalent device, the flue-fed and
chute-fed incinerator emissions will exceed emission
standards.
5.11. A chute-fed multiple-chamber incinerator has
separate passages for refuse charging and combustion-
product emission. Nevertheless, the emissions from
this incinerator often exceed emission standards. One
cause is the high natural draft in the flues of the
tall stacks that go to the top of the apartment house.
This high draft carries with it a large amount of
particulates and fly ash. A barometric damper will
alleviate the high draft.
5.12. Single-chamber incinerators used for commercial
or industrial establishments have been largely replaced
by multiple-chamber types. They may handle from 50
to several thousand pounds of refuse per hour.
5.13. The average capacity of municipal incinerators
is 300 tons of refuse per day. They may be fed in
batches or continuously. Continuous-feed units are
preferable, because operating parameters—such as
combustion-chamber temperatures that affect particulate
emissions—can be closely controlled.
5-3
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5.14. The gases leaving an incinerator may have tempera-
tures as high as 1800°F, which is much higher than the
600 F, maximum for steam-generating boilers. The
higher temperatures mean a higher plume rise but also
a greater volume of gas and more expensive breechings,
chimney linings, and air pollution control equipment.
5.15. Some rules that should be met by any incinerator
to minimize the particulate emissions are as follows:
(a) Air and fuel must be in proper proportion
and mixed adequately.
(b) Temperature must be sufficient for combustion
of both solid fuel and gaseous products.
(c) Furnace volume must be large enough to provide
adequate time for complete burning of the com-
bustible materials.
NOTE - these rules are a restatement of the "three T's
of combustion."
5.16. Some operating practices that can help to reduce
the smoke from incinerators include the following:
(a) On a cold start, feed nonsmoky material
slowly and increase the frequency of the
charge—not its size—until the secondary
combustion chambers get hot.
(b) If smoke is a problem, keep the charging
opening practically blocked with waste.
(c) It is often an advantage to mix slow-burning
material with flash-burning material. This
can be done to achieve more efficient in-
cineration of wet garbage or it can be done
to reduce smoke by mixing smoky materials,
such as plastics and rubber, with paper
waste.
5-4
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(d) Excessive fly ash is usually the result of too
great a draft. The draft can frequently be
reduced by partially closing the damper, which
is installed in the breeching between the
furnace and the stack.
5.17. Dark smoke from incinerators consists primarily
of small carbon particles resulting from incomplete
combustion. The dark smoke may mask the light-colored
plumes also emitted from the incinerator.
5.18. Light-colored plumes are emitted from most munici-
pal incinerators. These plumes are caused by volatiliza-
tion of particles or by chemical reactions in the fuel
bed. Analysis of the plume shows appreciable quantities
of metallic salts and oxides in microcrystalline form
which were transformed into the vapor state in the fuel
bed and then condensed. Removal of these very small
particles from the flue gases is difficult. The equi-
valent opacity of the plume can be partially reduced
by proper incinerator design.
5.19. Large fly-ash particles may be either charred
material or incombustible particles. If complete
combustion is achieved, there should be no charred
particles. The incombustible material may come from
chemical reactions in the fuel bed. It may also be
from small particles that were present in the refuse.
5.20. The size of the particles formed by chemical
reactions may range from submicron to 10-micron diameters.
Much of the weight of the particulate matter is in the
particles greater than 5 microns. These can be re-
moved from the combustion emissions by collecting
devices.
5.21. Several types of collection devices which have
been used with incinerators and their efficiencies
5-5
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(by total weight of all particles without regard to
size) are given in the following tabulation: ,
Collection
Efficiency,
Collection Device percent
Settling chamber 10-35
Wetted baffle-spray system 10-55
Cyclones and multiple cyclones 60-80
Wet scrubbers 94-96
Electrostatic precipitators 96-99+
Bag filters 99+
The use of bag filters for incinerators is very
limited. Their utilization depends on considerations
of temperatures and moisture content of the gas stream
as well as the pressure drop across the filter.
5.22. The per catita quantity of solid waste generated
in the United States has been increasing in recent years.
The physical and chemical properties of the garbage have
also been changing. Moisture content has been decreas-
ing with diminishing household garbage. As a consequence
of the decreasing use of coal for home heating, there
are less ashes for disposal. The combustible content
and the heat value of the solid waste have been in-
creasing, principally because of the greater use of paper
and plastics.
5.23. In a study of incineration of tepee burners,
several observations were made regarding the denisty
of smoke produced when different types of material
were burned:
(a) Plastic products (polyvinyl chloride, etc.),
rubber products, and asphalt products (tar
paper, linoleum tar blocks, etc.) produced
Ringelmann No. 5 or 100 percent equivalent
opacity smoke.
5-6
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(b) Leather products produced copious quantities
of Ringelmann No. 5 smoke lasting hundreds
of yards downwind.
(c) Ashes from home use produced Ringelmann No. 3
to 4 smoke.
(d) If the refuse contained garbage of more than
15 to 20 percent by weight and if this garbage
was not mixed uniformly with dry refuse, smoke
emissions of No. 4 to 5 Ringelmann generally
occurred.
(e) If the charge contained more than
30 percent damp material even when mixed
with dry combustible material, the pile
tended to smolder, producing an undesirably
large amount of smoke. Furthermore, the
buildup of a large pile of charged refuse
cut down on the draft through the pile and
contributed to additional incomplete
combustion.
The study recommended that plastic, rubber, asphalt,
and leather products not be burned in tepee burners.
Agricultural Burning
5.24. Open burning of several kinds is done in con-
nection with agriculture. The burning is done for waste
disposal, for disease pest control, and as part of
harvesting or land management. All of these types of
burning will result in visible smoke and other air
pollution effects such as visibility reduction, fallout
of carbonaceous residues, contributions to photo-
chemical smog, and odors.
5.25. For some of this burning, there is a flexibility
in the time when the burning can be done and in the
area that can be burned during any one fire. In these
5-7
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cases, the burning should be scheduled for periods
when meteorological conditions such as wind speed
and inversion height are conductive to good dispersion
of the smoke. However, the winds cannot be too strong
or there may be a chance of the fire getting out of
hand.
5.26. Burning of this type includes the cleaning out
of weeds and brush when chemical methods are undersirable,
the removal of the slash remaining after logging opera-
tions, the clearing of potato vines, peanut vines, and
sugarcane leaves prior to harvest.
5.27. Other agricultural burning cannot be scheduled.
One example is the burning of smudge pots in orchards
to reduce the hazard from frost. Another is disposal
of cattle affected by hoof and mouth disease at a time
of the year when burial is not possible because of
frozen ground or other reasons.
5.28. Other agricultural burning includes the burning
of field crops such as barley and rice, the removal of
prunings from fruit and nut trees, the incineration
of brush, and the burning of cotton gin waste to aid
in the control of bollworms.
5.29. The density of the smoke from agricultural burn-
ing will depend upon the combustion temperature and the
residence time of the fuel at that temperature. If
the moisture content of the fuel is high, the smoke will
be of a white shade indicating the presence of water
vapor. The greener the plant life, the more moisture
it contains and the whiter the smoke will be.
Combustion of Natural Gas
5.30. The particulate emissions from the normal com-
bustion of natural gas are insignificant compared with
5-8
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Coal
5
78
3
7
7
100
Oil
10
86
3
0.6
0.4
100
Gas
24
75
trace
1
-
100
those from coal and oil. Control equipment is not
utilized to control the emission from natural gas
combustion equipment.
5.31. Natural gas constituents normally includes
methane (CH,), ethane (C? H,)in varying proportions,
and lesser amounts of nitrogen (N ) and carbon dioxide
(co2).
5.32. The table compares the chemical composition of
typical samples of coal, fuel oil, and natural gas:
.Content, percent
Hydrogen
Carbon
Sulfur
N,, 02, etc.
Ash
5.33. One should note the high percentage of hydrogen
in natural gas. This high percentage results in a
large amount of water vapor being present in the gases
exhausted from combustion. As a consequence, the plume
from natural gas combustion under certain ambient
temperature and moisture conditions can be a very dense
white plume of condensed water vapor.
5.34. The water produced in combustion will absorb
900 Btu's in changing from the liquid to the vapor
state. Thus, fuels containing more hydrogen provide
less avaiJ "ible heat than fuels containing small amounts
of hydrogen.
5.35. In heat-generating installations, one of the
principal components is the heat exchanf3r. The heat
exchanger contains the medium, such as w^ter, that is
to be heated, and its outside surface area is exposed
5-9
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to the hot gases generated by the burning fuel. Boilers
are rated on the total area of heating surface of their
heat exchangers.
5.36. Burners can be divided into two broad classifica-
tions - atmospheric and mechanical draft.
5.37. The atmospheric burner depends entirely upon the
negative pressure within the furnace to draw combustion
air through the burner assembly. Natural draft can be
created by a stack. Theoretically, the draft is pro-
portional to the difference between the stack temperature
and ambient temperature and to the height of the stack.
5.38. The mechanical draft burner depends upon a
blower (usually, a forced-draft blower—not an induced-
draft blower) to supply the combustion air to the
burner. With this type of burner a low-profile building
with a short "stub" stack can be used to house the
boiler.
5.39. Smoke from the stack of a natural gas installa-
tion is evidence of improper operation of the gas
burner, specifically, that there is insufficient com-
bustion air.
5.40. Other indications of insufficient air will be
(a) A burner flame that is extremely rich,
having an orange-red appearance;
(b) Soot deposits on heat-exchanger surfaces;
(c) Burner pulsation;
(d) Excessive gas consumption.
5.41. One of the common reasons for insufficient com-
bustion air—one that is frequently overlooked—is the
lack of adequate fresh air opening into the boiler room.
There must be some permanent provision (not just an
open window) to ensure that fresh air will always be
supplied to the combustion equipment. One of the first
5-10
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indications of an inadequate air supply is a hot,
stuffy feeling in the boiler room.
Engines Used in Transportation
5.42. There are three engines commonly used in the
United States to propel surface vehicles and aircraft.
These are the spark-ignited internal combustion engine,
the compression ignited internal combustion engine,
which is frequently referred to as the diesel, and the
aircraft gas-turbine engine.
5.43. The first of these is used in automobiles, light-
duty trucks, light aircraft, motorcycles, outboard motors,
and small gasoline utility engines.
5.44. The diesel engine is used in large trucks, buses,
locomotives, ships, and heavy construction equipment.
5.45. The gas-turbine engine is commonly used on large
aircraft.
5.46. Both types of internal combustion engines can be
subdivided into four-stroke-cycle engines. These two
operating cycles differ in the number of times the piston
rises in the cylinder during the combustion of the fuel
in the cylinder. Both cycles consist of four parts.
The operations that take place in the spark-ignition
engine during the four parts of the cycles are:
(a). Intake of air and fuel;
(b) Compression of fuel-air mixture during which
ignition of the mixture is set off by the
spark from a spark plug;
(c) Expansion of the burning mixture, forcing
down the piston and delivering the power which
drives the vehicle;
(d) Exhaust of the burned gases out of the cylinder.
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5.47. The differences between the gasoline and diesel
engines are the method of ignition and the fuel systems.
In the diesel engine the fuel does not enter the cylinder
as a mixture with the air but is injected into the
cylinder through nozzles during the phase when the air
is being compressed to a high pressure and high tempera-
ture. Fuel injected into this high-temperature air
ignites without a spark.
5.48. The aircraft gas turbine consists of four main
sections: a compressor, a combustion chamber or com-
bustor, a turbine, and a tailpipe.
5.49. When a plane is moving, air is forced into the
front of the engine where the compressor is. The com-
pressor, a jnultibladed fan, compresses the air to several
times its density, increasing its temperature and pressure.
5.50. The compressed air then passes into the combustors,
into which fuel is sprayed. The mixture of fuel and air
is ignited producing a high-temperature exhaust gas.
5.5.1. This exhaust gas is expanded into the turbine.
The expansion drives the turbine, giving it sufficient
power to rotate the compressor blades.
5.52. After passing through the turbine, the exhaust
gas may still have -enough velocity to provide a back-
ward push against the outside air helping to thrust the
aircraft forward.
5.53. There are three categories of aircraft gas-turbine
engines:' turbojet, turboprop, and turbofan.
5.54. The turbojet engine uses a great proportion of the
energy of the turbine exhaust gases to provide thrust
for the aircraft. This is done by designing a suitable
exit nozzle. Turbojet engines perform best at high
altitudes and high speeds.
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5.55. Turboprop, engines have a propeller mounted in
front of the compressor. They are designed so that
most of the energy of the expanding exhaust gases is
used in turning the turbine and subsequently to rotate
the propeller-. These engines operate best at low
altitudes.
5.56. In the turbofan engine the fans of the first
stages are larger in diameter than the others. The air
taken into the center' portion of the compressor passes
through as with the turbojet engine. The exhaust gases
turn the turbine, driving the compressor, and expand out
the rear of the engine producing additional jet thrust.
Because of the increased frontal area of this engine, it
is better adapted to subsonic than to supersonic flight.
Visible Emissions From
Mobile Sources
5.57. Particulate matter is emitted from a gasoline
engine in the exhaust gases and in the blowby gases,
which escape past the piston rings into the crankcase
and then into the exhaust.
5.58. Carbon, metallic ash, and hydrocarbons in
aerosol form are the principal particulate emissions.
If an automobile is performing properly these particles
will essentially all be less than 5 microns in size and
visible smoke will not occur.
5.59. The color of smoky exhausts may be blue, black, or
white. Blue and black smoke are indicators that the
engine needs repair.
5.60. White smoke results from the condensation of
water vapor in the exhaust. There is always water
vapor produced in the combustion of gasoline. White
smoke from an exhaust will be more likely during cold
5-13
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weather when the vapor is cooled to the visible liquid
state. The white smoke will be more noticeable on
moist days when the air is saturated so that the wet
plume cannot evaporate and when an automobile is
standing still so the plume is not dispersed by the
motion of air.
5.61. If the exhaust smoke has a bluish tinge, oil is
leaking into the combustion chamber of the engine and is
being burned there with the gasoline.
5.62. Oil can enter the combustion chamber in three
ways: through a cracked vacuum pump diaphragm, through
an excessive clearance around the intake valve, and be-
tween the piston rings and the cylinder walls. The
latter entry may be due to worn cylinder walls or to
worn or carboned rings.
5.63. Black-exhaust smoke is composed of unburned
gasoline. This indicates that the fuel-to-air mixture
is excessively ric-h in fuel.
5.64. Some causes of black smoke from a gasoline engine
are
(a) Excessive fuel pump pressure
or pump leakage;
(b) Choke not opening properly;
(c) Clogged air cleaner
(d) Carburetor iti need of repair or adjustment;
(e) Faulty spark plugs which cause the engine
to "miss" and not use all the fuel.
5.65. The California Motor Vehicle Code in essence
states that no motor vehicle first sold or registered
after January 1, 1971 shall discharge into the atmosphere
for a period of more than 10 seconds any contaminant
equal to or exceeding 20 percent opacity. Forty percent
opacity applies to vehicles before this date.
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5.66. Particulate matter emitted by diesel engines
consists primarily of carbon and hydrocarbon aerosols,
which result from incomplete combustion of the fuel.
Diesel exhaust is made up of particles of which 62.5 per-
cent are less than 5 microns in diameter and 37.5 per-
cent are from 5 to 20 microns.
5.67. Maximum emissions of visible smoke from diesel
engines occur during full-throttle acceleration and
during deceleration or "lugdown," also at full throttle.
At full or open throttle the fuel-to-air ratio is en-
riched. This fuel-rich mixture is desirable during
acceleration because it provides greater power. The
greater power is achieved at the expense of fuel
economy.
5.68. The power of the diesel engine is controlled
by the amount of fuel injected into the combustion
chamber through nozzles during the compression phase of
the engine cycle. '
5.69. If the fuel system is kept at the setting pre-
scribed by the manufacturer, the smoke emissions should
meet established standards. As vehicle mileage in-
creases, low levels of visible emission can be main-
tained by proper fuel system adjustment, maintenance
at appropriate intervals, use of specified type of
fuel, and good operating techniques. Maintenance
will correct dirty or eroded injection nozzles, which
can occur even in a properly adjusted engine.
5.70. It has been found that truck operators sometimes
increase the horsepower of their engines by altering the
fuel-injection setting prescribed by the manufacturer.
By this means the operator can install an engine which
is underrated for the load required and then meet the
power requirement by overfueling. However, this increase
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in power also raises the level of black smoke.
5.71. Most turbine engines in nonmilitary aircraft
use aviation kerosene as a fuel. The turbine engines
operate at fuel-to-air ratios five to twenty times.
less than those used by piston engines. During flight
the emissions of particulates are low. However during
the takeoff and landing operations, the engines
operate under high fuel-to-air ration -conditions and
visible smoke is emitted. The quantity of the solid
material released is small, but is highly visible.
5.72. Particulate matter originates near the upstream
end of the combustor, where fuel is injected and where
the fuel-rich regions are. Alteration programs for re-
placing smoking engines involve the replacement of con-
ventional combustors (or burner <;ans) with new smoke-
less burner cans.
5.73. A series of tests on different kinds of con-
ventional aircraft turbine engines has been run to
determine the density of the smoke emitted under
different power settings including idle, takeoff,
climb-out and approach power. The results are given
in the following table. For the JT3C-6 engine, the
dense smoke emissions at takeoff power were largely
caused by the water augmentation in this engine.
The water injection is used for additional thrust on
takeoff from a standing start to an altitude of ap-
proximately 500 fee-t.
5.-.16
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Engine Number
and Type
Power Setting
Idle Takeoff Climb-out Approach
501-D13
Turboprop
JT3D-3B
Tubofan
JT8D-1
Turbofan
< 1/2
0
3/4
< 1/2
1 1/2-2
3
< 1/2
1 1/2-2
3
< 1/2
1
3
CJ805-3B
Turbojet
JT3C-6
Turbojet with
water augmen-
tation
3 1/2 3 1/2
Suggested Additional Reading
The following references may be obtained from National
Technical Information Services, 5285 Port Royal Road,
Springfield, VA 22161.
Control Techniques for Carbon Monoxide, Nitrogen
Oxide, and Hydrocarbon Emissions From Mobile Sources,
NAPCA Publication No. AP-66, Washington, DC (1970).
Control Techniques for Particulate Air Pollutants,
NAPCA Publication No. AP-51, Washington, DC (1969).
Air Pollution Engineering Manual, 2nd Edition, (1970)
Chapter 8. US EPA AP-40, Office of Air Quality
Planning and Standards, Research Triangle Park, NC 27711,
Control and Disposal of Cotton Ginning Wastes, DREW, PHS
Publication No. 999-AP-31, Cincinnati, Ohio, (1967).
Air Pollution Aspects of Tepee Burners, T. E. Kreichelt,
DHEW, PHS Publication No. 999-AP-28, Cincinnati, Ohio
(1966).
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Air Pollution, Vol. IV, edited by A. C. Stern, third
edition. Academic Press, Inc. Ill Fifth Avenue,
New York, NY 10003 (1977).
5-18
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CHAPTER VI.
NON COMBUSTION EMISSIONS AND WATER
VAPOR PLUMES
6.1. Discussed below are some of the equipment and the
industries that may emit visible plumes. Where avail-
able, the size distribution of the particles will be
listed. Some of the equipment types are basic to
several industries and processes so these types of
equipment will be discussed first and then referred to
in .e -industry discussions.
Metallurgical Furnaces
6.2. There are several types of furnaces for melting
metals. They are reverberatory, cupola, electric,
crucible, and pot. Most of these furnaces discharge
high-temperature effluents containing dusts and fumes
which are less than 1 micron in size. These effluents
must frequently be cooled before they are ducted to a
control device. The control device must be capable of
high-efficiency collection of submicron particles.
6.3. The reverberatory furnace usually consists of a
shallow, generally rectangular refractory hearth for
holding the metal to be melted. The furnace is en-
closed by vertical walls and covered with a low re-
fractory-lined roof. Combustion of the fuel occurs
directly above the metal in the furnace. The heat
is radiated from the burner flame, roof, and walls onto
the metal. (The radiation "reverberates" within the
furnace.)
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6.4. The largest reverberatory furnace is the open
hearth furnace used in steel manufacture. The charge
of metal is introduced through doors in the front wall;
finished steel and slag are poured out of a tap hole
in the rear wall. Heat is provided by passing a
luminous flame with excess air over the charged metal.
6.5. Other reverberatory furnaces are cylindrical and
may be fired by a flame which enters the end of the
cylinder or is directed tangentially along the side of
-the cylinder. These furnaces are frequently used in
nonferrous (that is, excluding iron and steel) industries
for smelting small amounts of aluminum, brass, and alloys
of several metals.
6.6. The cupola furnace is normally used in gray iron
foundries, where iron is melted and poured into a mold
or casting. This furnace is also used to melt copper,
brass, bronze, and lead.
6.7. A cupola is a refractory-lined cylinder open at
the top and equipped with air inlets (called tuyeres)
at the bottom. Alternate layers of metal, coke and
limestone are dumped from a charging door in the side
of the cupola onto a burning coke bed in the bottom
of the furnace. The combustion air for burning the
coke is forced upward through the tuyeres and layers of
charge by a blower. The heat generated by burning
the coke melts the metal, which is drawn off through
a tap hole. The charging and melting is a continuous
operation. Large amounts of fine particles are
carried off in the gases.
6.8. There are four types of electric furnaces:
direct arc, indirect arc, resistance, and induction.
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6.9. In the direct-arc furnace, graphite, and carbon
electrodes are placed below the slag cover of the
metal. The current passes from one electrode through
the slag, through the metal charge, and back through
the slag to the other electrode. The heat is generated
by radiation from the electric arc between the electrodes
and from the resistance to the passage of electricity
in the metal.
6.10.. In the indirect-arc furnace the metal charge is
placed-below the electrodes..and the .arc is formed be-
tween the electrodes and above the charge. Indirect-
arc furnaces are used mainly in the steel industry.
6.11. The induction furnace consists of a crucible
within a water cooled copper coil. An Alternating
electric current in the coil around the crucible
induces eddy currents in the metal charge. The move-
ment of these eddies develops heat within the mass of
the charge. This furnace. is used for the production of
both ferrous and nonferrous metal and alloys.
6.12. In the resistance furnace, the electrodes may
be buried within the metal charge or placed above it.
The charge itself acts as the electrical resistance
and generates the heat. The resistance furnace is used
in the smelting of ores to produce ferroalloys at
temperatures up to 6000 F.
6.13. A crucible furnace consists of a large, covered
metal p^ t lined with refractory materials such as
clay-graphite mixtures or silicon carbide. Ther0 is
a small hole in the lid for charging the metal and ex-
hausting the products of combustion. The crucible
of refractory material rests on a pedestal in the
center of the furnace and flames from gas or oil
burners are directed tangentially around it. This
6-3
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furnace is used for melting metals with melting points
below 2500°F.
6.14. Pot furnaces may be cylindrical or rectangular
and consist of an outer shell lined with refractory
material, a combustion chamber, and a pot. The pot
is made of iron or steel and in it are placed metals
which will melt below 1400°F. The pot rests in the
furnace which supports it above the floor of the
combustion chamber. When melted, the metals in the
pot are removed by tilting the pot or by pumping or
dipping.
Driers
6.15. A drier is a device for removing water or other
volatile material from a solid substance. Air con-
taminants emitted include dusts and vapors.
6.16. A rotary drier consists of a rotating cylinder
inclined to the horizontal with material fed from the
higher end and discharged at the lower end. In the
direct rotary drier, heated air or combustion gases
flow through the cylinder in direct contact with the
material. Air flow may be in either the same or the
opposite direction as the flow of material. Dust
carryout increases proportionately to the square of
the increase in air flow through the drier.
In another type, the indirect rotary drier, heat
is applied by combustion gases on the outside of the
cylinder or through steam tubes inside the cylinder.
€.17. The direct rotary drier has "flights" attached
to the inside of the cylinder. As the cylinder
rotates-, the flights pick up the material and shower
it down through the gas stream. Thus, the direct rotary
drier has very high potential for dust emissions. It
6-4
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cannot be used for drying fine material because loss
of product would be excessive. Indirect rotary driers
are usually used for drying powdery material since they
have less tendency to emit dust.
6.18. The flash drier consists of a furnace or source
of hot gases, a device for dispersing the wet material
through the gases, a duct through which the gases
convey the material, and a collection system for re-
moving the dried material from the gas stream.
6.19. The spray drier consists of a drying chamber,
a source of hot gases, a device for atomizing the
solution particles to be dried, and a means for
separating the dry product from the exhaust gases.
Atomization is achieved either by disks which rotate
at a high speed, high-pressure nozzles, or by nozzles
that use air or by steam to break up the particles.
The dried product is generally separated from the
exhaust gases and collected in a cyclone separator.
6.20. A tray or compartment drier consists of a
chamber containing racks on which are placed trays of
wet material to be dried. Heated air circulates over
the wet material until the material reaches the
desired moisture content.
Terminology in Metallurgical
Processing
6.21. The metallurgical industry can be divided into
primary and secondary metals industries. The primary
metals industries produce the metal from ore. The
secondary metals industry includes the production of
alloys and the recovery of the metal from scrap and
salvage.
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6.22. The initial objective of metallurgical
operations is to convert the metal ore to a purer form
of the metal and then to mix it with other elements
to form an alloy. Some of the processes used in.these
purifying operations are smelting, refining, electrolytic
reduction, sweating, and sintering. Sometimes, two of
these terms describe the same process.
6.23. The process of heating ores to a high temperature
in the presence of a reducing agent such as carbon
(coke) and of a fluxing agent (such as limestone) to
remove the accompanying clay and sand is termed
smelting.
6.24. In the smelting of iron ore the ore is heated
in a blast furnace with coke and limestone at a
temperature above the melting point of iron and slag
(a mixture of the impurities and the limestone flux).
The molten iron (the more dense material) and molten
slag (the less dense material) are removed separately
from the furnace. The limestone flux helps to purge
the metal of impurities and renders the slag more
liquid.
6.25. Electrolytic Reduction - In this process a molten
compound containing the metal is placed in an electroly-
tic cell known as a pot, which consists of a steel tank
lined with refractory insulating bricks. The compound
is decomposed by a continuous direct electric current
flowing between the cathode and the anode. The
purified metal will flow to one of these electrodes
and be deposited there.
6.26. Roasting - This process involves heating the
material to a temperature not high enough to melt the
material but high enough to cause it to oxidize or be-
come pulverized. The process can also be called
calcining.
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6.27. Sweating Furnace - Sweating can be accomplished
in a furnace when the raw material is composed of two
metals having different melting temperatures. The sweat-
ing furnace temperature is carefully controlled so that
the metal with the lower melting point becomes liquid
and flows from the furnace. After this metal is removed,
the furnace burners are extinguished and the metal with
the higher melting point is raked from the hearth.
6.28. Sintering - A mixture of ore-bearing fine parti-
cles and fuel such as coal or coke is burned. The ob-
ject is to partially melt or sinter the material into
relatively coarse particles' that are more suitable for
other metallurgical operations than were the fine
particles.
6.29. Quenching - The immersion of hot metals or coke
in liquid baths in Order to effect rapid cooling is
termed quenching. The purpose of quenching ordinary
steel is to harden it.
6.30. Materials that will resist change of shape, weight,
or physical properties at high temperatures are known
as refractories. The materials that are chiefly used
for refractories are fire-clay, silica, kaoline, diaspora,
alumina, and silicon carbide. Refractories are used most
often in the form of bricks.
Iron and Steel Mills
6.31. To make steel, iron is reduced to pig iron in a
blast furnace (smelting) and"most of its impurities are
removed as slag. The pig iron is transformed into steel
in open hearth (reverberatory) furnaces, basic oxygen
furna'.es, or electric furnaces, where carbon, manganese,
silicon, and other impurities are oxidized to form gases
and slag. The concentrations of the impurities are reduced
to the limits specified for steel.
6.32. The blast furnace is the chief means for reducing
iron ore to pig iron. The reduction process
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is carried out at a high temperature and in the presence
of a fluxing substance. Furnances may be 90-100 feet
high and of varying diameters. At the top of the furnace
is a double bell, which forms an air lock for the admis-
sion of materials during continuous operation of the
furnace.
When in use, the blast furnace is first charged with
alternate layers of coke, ore, and limestone. The
coke is ignited at the bottom and is rapidly burned
under the influence of a forced draft of air blown
from the base upward through the furnace. As the
coke is burned away, the material moves downward in
the furnace while the stack is kept full by fresh
charges admitted through the bells. The iron at the
bottom is tapped off at intervals through an "iron
notch." The lighter slag may also be tapped off
through a "cinder notch ."
As the hot gases from the combustion region pass up-
ward from the furnace they heat the fresh charges.
They then pass out of the furnace through ducts
which carry them to purifying equipment. This gas
contains about 25 percent carbon monoxide with the
remainder being chiefly inert gases. After the gas
is passed through dust collectors and scrubbers, it
can be burned in stoves which preheat the air going
into the blast furnace.
6.33. "Slips" are the principal operating factor
which causes particulate pollution from blast furnaces.
A slip results from arching of the charge of coke,
limestone, or iron ore across the inside of the furnace.
When the arch finally breaks and the burden slips
downward, there is a rush of gas to the top of the
furnace, which develops abnormally high pressures
that cannot be handled by the gas-cleaning equipment.
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When this occurs, safety valves open to relieve the
pressure and to discharge a dense black or red cloud
of dust to the air. Slips reduce efficiency and the
steel industry is constantly striving to reduce their
incidence. Even under normal conditions most of the
particles emitted from blast furnaces are larger than 50
microns.
6.34. The basic oxygen converter is a cylindrical
container open at one end for charging and pouring
and for oxygen injections. In this steel-making pro-
cess, oxygen is blown at high velocity through a water-
cooled pipe downward onto the surface of the mixture
of molten pig iron, scrap iron, and scrap steel. This
results in violent agitation and mixing of the oxygen
with the iron. Rapid oxidation of the dissolved carbon
and silicon follows forming slag and gases.
6.35. Sintering plants convert iron ore fines and
blast furnace flue dust into a coarser material more
suitable for charging to a blast furnace. This is
done by applying heat to a mixture .of the iron-contain-
ing materials and coke on a slow-moving grate through
which combustion air is drawn. , .
6.36. Major sources of dust in sintering plants
are the combustion gases drawn through the bed and
the exhaust from the grinding, screening, and cooling
of the sinter. Most of the particles discharged in the
sintering process are large and fall out of the air as
dustfall.
6.37. Most of the coke used in blast furnaces is pro-
duced in "by-product" coke ovens from bituminous coal.
The by-product gases from the coke ovens are processed
in a by-product plant, where such items as tar, ammonia,
and light oils are removed. The remaining coke-oven
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gas is used as fuel in a variety of furnaces through-
out the steel plant.
6.38. The coke plant consists of a battery of long,
narrow firebrick ovens separated- by combustion chambers.
Coal is introduced into the red hot ovens through holes
in the top of the battery. When the coking is finished
(17-18 hours), doors at the ends of the oven are
opened and a pusher ram shoves the entire charge of
coke into a railway car. The hot coke will burn in the
air until the car is conveyed to a quench tower where
huge quantities of water are used to extinguish the
burning. Dust, steam, and gas emissions occur during
charging, discharging, and quenching operations.
Since the ovens in a battery are sequentially operated,
the pollutants are discharged at a fairly constant rate.
Most of the smoke and dust emitted at the coke oven
site result from the inadequacies of the charging
process, but there is also leakage of smoke and gases
because of poorly fitted or sealed oven doors. Visible
emission regulations for by-product coke plants vary
from State to State. At the present time there are no
Federal new source performance standard regulations,
but it is anticipated there will be by late 1978 or
early 1979. Because of the many points and kinds of
potential visible emissions from the coke plants, it is
extremely difficult to interpret a Method 9 regulation.
Charging of coal and the pushing of coke are the main
points of concern, and inspectors should be familiar with
the coke plant operations and particularly concerned with
good mechanical maintenance by the operators. Charging
coal into the oven is estimated to account for 60 to
70 percent of the total emissions problem of coke over
batteries. In Allegheny County, Pennsylvania, there
are 20% visible emissions allowed for charging and
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pushing but no visible emissions allowed for top side
leaks. In West Virginia, for coke ovens built after
1972, visible emissions allowed are 30% for 1.5 minutes
per charge.
6.39. Air contaminants are emitted from an open hearth
furnace throughout the process, which may last 10 hours.
Oxygen injection (.lancing) into the furnace speeds the
process but increases the amount of air pollution
emitted. The pollutants emitted are fumes, dust, and
gases, with up to 90 percent being the red iron-oxide
fumes. Other contaminants may arise from the grease and
oil contained in the steel scrap. About 50 percent of
the emissions are particles less than 5 microns in
diameter.
Open hearth shops often contain several furnaces, each
having an exhaust stack. Because of the cojt of pollu-
tion control and the growing obsolescence of open hearth
furnaces, they are being replaced by basic oxygen fur-
naces and electric furnaces.
6.40. More emissions are created by basic oxygen fur-
naces (EOF) than by open hearth furnaces; however, all
BOF's in the United States are equipped vith electro-
static precipitators or venturi scrubbers. The open
me nth of the EOF converter is covered by a hood, and
the emissions are conducted to the collectors. The
particle size of the emissions is small; 85 percent are
less than 1 micron in diameter.
6.41. In the steel industry, electric arc furnaces are
smaller than other types and are used primarily to pro-
duce special alloy steels. Heat is furnished by direct-
arc electrodes extending through the roof of the fur-
nace. Dust, fumes, and gases are emitted, but only 40
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Gray Iron Foundries
to 50 percent of the dust is iron oxide, an amount con-
siderably less than that emitted by the other furnaces.
Approximately 70 percent by weight of the particles are
smaller than 5 microns. Over 95 percent effective
collection can be achieved with appropriate hooding and
high-efficiency collection equipment.
6.42. Gray iron foundries melt and cast iron. The
cupola, electric, and reverberatory furnaces are used;
however, the cupola is the one most often employed.
Plant sizes range from small job cupolas operated
several hours a day to large units operated continuously
for several days.
Particulate emissions are composed of iron oxide,
dust smoke, .oil, grease, and metal fumes. Between
20 and 25 percent of the dust and fume particles are
less than 5 microns in diameter. The dust in the dis-
charge gases arises from dirt on the metal and from
fires in the coke and limestone charge. Smoke and
oil vapor come primarily from partial combustion and
from distillation of oil on the greasy scrap charged
to the furnace.
The exhaust gases which carry the particulates are hot
and voluminous, thus requiring a control system de-
signed to handle large flows. The most effective con-
trol system incorporates an afterburner to eliminate
combustibles and a fabric filter to collect dust and
fume. Coolers must be installed to cool the effluent
before it reaches the baghouse.
6.43. Other possible sources of particulates at
foundries are the core ovens which bake the cores used
in the sand molds. The cores contain binders that
require baking to develop the strength needed to
6-12
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resist any erosion and deformation when the molten
iron is poured into the mold. Sometimes, when special
binders are used in the core, the ovens will emit fine
aerosols that can have excessive opacities and cause
eye irritation. Normally, an afterburner can control
these pollutants.
Nonferrous Metallurgical Industry
6.44. The primary and secondary recovery of copper,
lead, zinc, and aluminum are the chief nonferrous
metallurgical industries.
6.45. Part of the production of aluminum involves
the electrolytic reduction of alumina (an oxide of
aluminum) in a pot that also contains cryolite and
fluoride salts. The effluent released during the pot
reduction process contains hydrogen fluoride, fluoride
fumes, and fine particles of alumina and carbon. The
emissions from some pot furnaces also contain hydro-
carbon tars.
6.46. Secondary aluminum operations involve making
lightweight metal alloys for industrial castings.
Crucible furnaces, reverberatory furnaces, or sweating
furnaces may be used. Fluxes help remove the dissolved
gases and oxide particles from the molten bath. Chlorine
gas is lanced into the molten bath to reduce the
magnesium content. It forms aluminum chloride fumes
having a small particle size. If the scrap charged
is oily or greasy, smoke is given off. The fluxes
used also produce particulate matter.
6.47. The primary smelting of lead and zinc involves
converting the sulfide of both ores to oxide through
roasting and sintering operations. A mixture of sinter,
iron, coke, and limestone flux is charged into blast
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furnaces where the burning of the coke reduces the
lead oxide to molten lead before being tapped off.
The effluent gases from the roasting, sintering, and
smelting operation contain considerable lead dust..
6.48. Zinc oxide from the roasting of the ore or
from processing the slag from the lead smelter can be
converted into metallic zinc by the electrolytic reduc-
tion or by distillation in retorts or furnaces. The
distillation involves the heating of a mixture of zinc
oxide and coke until a zinc vapor is formed and the
oxygen in the zinc oxide combines with the carbon in
the coke to form carbon monoxide. The zinc vapor passes
into a condenser where it is converted into a liquid.
During this refining process, zinc fumes and dust are
discharged. In spite of hoods, baghouses, and electro-
static precipitators, the white zinc oxide fume arising
from the plant is a distinctive characteristic of a
zinc retort plant.
6.49. Scrap and salvage are the raw materials of the
secondary metals industry. A substantial quantity of
lead is recovered from automobile batteries. Various
types of furnaces are used. The discharge of air
contaminants from melting furnaces is generally caused
by the excessive temperatures and by the melting of
metal contaminated with organic material. If fuming
fluxes such as ammonium chloride are used in zinc
smelting, a fume of ammonium chloride will be observed
above the molten metal.
6.50. Over 95 percent of the particulate emission from
the secondary smelting of zinc and lead are less than
5 microns in diameter. Much of this is composed of
oxides of lead and zinc, but there are also sulfides
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and sulfates. Under high temperatures, zinc vapor
will form the white zinc oxide fume. Both lead and
zinc oxide fumes produce very opaque effluents.
6.51. The recovery of copper from copper sulfide ore
involves roasting in multiple hearth furnaces, smelting
in reverberatory furnaces, and "converting" by passing
thin streams of air through a mixture of iron and
copper sulfide. These processes emit CO, sulfur oxides,
nitrogen oxides, and a fine particulate plume. The
particulates consist of oxides, dust, and sulfuric acid
mist.
6.52. The plumes from the primary smelting of copper,
lead, and zinc contain concentrations of sulfur oxides
that are quite large compared with the other large
source-coal and oil-fired power plants.
6.53. Copper is called brass .when alloyed with zinc
and is termed bronze when alloyed with tin. The re-
melting of nearly pure copper and bronze produces
only small amounts of metal fumes due to high boiling
temperatures and low pouring temperatures of copper
and tin. However, the secondary smelting of brass can
produce zinc oxide fumes consisting of submi.cron
particles.
Petroleum Refineries
6.54. Major sources of particulate matter at refineries
are catalyst regenerators, sludge burners, and the air-
blow ng of asphalt. Minor emissions come from heaters,
boilers, and emergency flares.
6.55. Modern refining processes include many operations
using solid-type catalysts. These catalysts become con-
taminated with coke buildup during operation and must be
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regenerated by burning off the coke under controlled
combustion conditions. The flue gases from the regen-
erator vessel may contain hot catalyst dust, oil mists,
aerosols, carbon monoxide, and other combustion products.
If no control devices are used, a visible plume will be
emitted. Its degree of opacity will depend upon the
atmospheric humidity.
6.56. Two catalytic cracking processes are used: fluid
catalytic cracking (FCC) and, less frequently, thermofor
catalytic cracking (TCC)- The catalyst regenerator will
be different for each catalytic cracking reactor:
(a) The generator for the FCC units may be
located alongside, above, or below the
reactor. These regenerators normally have
a vertical cylindrical shape with a domed top.
External size varies from 20 feet in diameter
by 40 feet high to 50 feet in diameter by 85
feet high. Internal cyclones and external
electrostatic precipitators and carbon monox-
ide boilers are used to control the emissions.
(b) TCC regenerators referred to as kilns, are
usually vertical structures with horizontal,
rectangular, or square cross sections.
Typically, one may be 10 feet square by 45
feet high. Wet centrifugal collectors are
used as dust collectors.
6.57. Asphalt is the residue from crude oil distillation
after all the other fractions have been boiled off. The
residual asphalt can be refined by air blowing the
residue at elevated temperatures. Oxygen in the air
combines with hydrogen in the oil molecules to form
water vapor. Hydrogen is removed until the asphalt
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reaches the desired consistency. The blowing is
carried out in horizontal or vertical cylindrical-shell
stills equipped to blanket the charge with steam. Air
blowing of asphalt generates oil and tar mists and malo-
dorous gaseous pollutants.
6.58. At petroleum refineries, the incineration or open
burning of the heavy petroleum residues and inorganic
materials such as clay, sand, and acids can be a major
source of particulate emissions. This sludge is atomized
in much the same way as heavy fuel oil. While the
organic material can be burned, the inorganic matter is
entrained in the exhaust gases and emitted as fine dust.
6.59. To prevent unsafe operating pressures in process
units during shutdowns and startups and to handle mis-
cellaneous hydrocarbon leaks or temporary high-pressure
conditions, a refinery must provide a means for venting
hydrocarbons safely. One method is to incinerate them
in an elevated-type flare. Such flares introduce the
possibility of smoke composed of carbon particles re-
sulting from incomplete combustion. Somkeless com-
bustion is often promoted at elevated flares by intro-
ducing steam through nozzles at the top of the stack.
The steam jets provide turbulence and mixing with the
ambient air.
Portland Cement and Lime Plants
6.60. Raw materials for the manufacture of portland
(gray) cement are ground, mixed, and blended by either
a wet or a dry process. In the wet process the crushed
raw materials are mixed with water and ground and mixed
wet. In the dry process the ingredients are used dry.
Raw materials consist of two basic ingredients—lime-
bearing material and clayey-material.
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After the raw materials are crushed and ground, they
are introduced into a rotary kiln and heated. The kiln
is a rotating steel cylinder, lined with refractory brick,
ranging from 6 feet in diameter by 60 feet in
length to 25 feet in diameter by 760 feet in length.
Heating continues until the mixture reaches 2200. F, at
which temperature a chemical reaction takes place rais-
ing the temperature to 2700°-2900°F. Cement clinkers
about the size of marbles are produced, which are cooled
and ground to a powder. During the grinding, gypsum is
added to prevent the cement from hardening too fast
when mixed with water.
6.61. The largest amount of particulate emission at
cement plants accompanies the exhaust gases leaving the
kilns. Over 85 percent of the particles carried out by
these gases are smaller than 20 microns in diameter. Dust
is also generated from the rotary driers used in pre-
paration of material for the dry process and from the
loading of cement into bags, trucks, and railroad cars.
6.62. Fabric filters and electrostatic precipitators
preceded by mechanical collectors are generally the
controls used.
6.63. Gaseous contaminants from the combustion of fuel
in the kilns are usually minor. Most of the sulfur
dioxide from the sulfur in the fuel combines with the
lime and alkalies such as calcium oxide.
6.64 Lime is produced by calcining various types of
limestone in continuous rotary or verticle kilns lined
with refractory material. This is accomplished by
heating the limestone in the kiln to 2000 F, driving
off the carbon dioxide, and leaving calcium oxide, which.
is called quicklime. Two of its most important single
uses are for refractory materials and steel fluxing.
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Kraft Pulp Mills
The dust generated by rotary lime kilns ranges from
5 to 15 percent by weight of the lime produced. Vertical
kilns emit 1 percent by weight. About 28 percent of the
particles are greater than 44 microns in diameter, which
is the size range collected in dustfall jars. About
one-third are less than 20 microns in diameter.
6.65. The basis of all paper products is cellulose.
The main source of cellulose is wood, although rags
can also be used. The fibers of cellulose are bound
together with lignin in the pulpwood. There are several
chemical pulping processes for separting the cellulose
from the lignin: sulfite; sulfate or kraft; soda; and
alpha. Over three-fourths of the production is done by
the kraft and sulfite processes. Both emit character-
istic odors; however, the kraft process emits a greater
quantity and there are eight times as many kraft as
sulfite mills. The malodorous gases include hydrogen
sulfide, methyl mercaptan, dimethyl sulfide, and sulfur
dioxide.
6.66. In the kraft process, wood chips are mixed with
a cooking liquor of sodium sulfide, sodium hydroxide,
and water and cooked under steam pressure for about 3
hours in a large, upright vessel called a digester.
During the cooking period the pressure is reduced
periodically to prevent overburdening of the digester;
this is accompanied by steam emissions.
When the cooking is completed, the bottom of the
digester is suddenly opened and its contents are forced
into a blow tank. The cellulose then proceeds through
several processes to the finished product. The spent
black liquor containing the lignin is drained from the
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blow tank for processing to recover the chemicals for
reuse. It is concentrated in multiple steam evaporators,
further concentrated in a direct contact evaporator,
burned in a recovery furnace, and dissolved in a smelt
tank.
The green liquor is pumped into a causticizer, where
the sodium carbonate is converted to sodium hydroxide
by the addition of calcium hydroxide for reuse in the
digester. The calcium carbonate, also produced in the
causticizer, is converted into calcium oxide in a lime
kiln and then to calcium hydroxide, which then is reused
in the caueticizer.
6.67. The major source of particulate emissions in
kraft pulping is the exhaust from the recovery furnace.
Sodium sulfate, which is nonodorous, is the major
particulate. Sodium carbonate and carbon particles are
also emitted. As the exhaust gases from the recovery
furnace pass to the chimney, some of their heat is used
to evaporate the black liquor in the direct-contact
evaporator. The water vapor produced by the evapora-
tion can produce a sizable white plume when it con-
denses in the atmosphere.
6.68. Other particulate emissions are lime dust from
the lime kiln; mists from the smelt tank, causticizer,
digester, and blow tank, and combustion products and
unburned bark from the bark-burning boiler.
Sulfuric Acid Manufacturing
6.69. Basically, the production of sulfuric acid in-
volves the generation of sulfur dioxide (S0?), its
oxidation to sulfur trioxide (SO.,), and the hydration
of SO,, to form sulfuric acid.
The sulfur dioxide can be generated by burning sulfur
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or sulfur-bearing materials such as hydrogen sulfide
from oil refineries. The highly concentrated sulfur
oxide emissions from primary smelters are also used as
input to the acid-making process although the contami-
nants such as dust must be removed from the SO,, gas if
high-quality is to be produced.
6.70. The two main processes of producing sulfuric
acid are the chamber process and the contact process.
Over 90 percent of the sulfuric acid in the United
States is produced by the contact process.
6.71. In the chamber process the SO- is oxidized to
S0~ by the reduction of nitrogen dioxide (NO-) to
nitrogen oxide (NO), and then it is combined with water
vapor. This is accomplished as the hot SO- flows
through a Glover's tower, several lead chambers, and two
Gay Lussac towers. The function of the Gay Lussac towers
is to recover the nitrogen oxides (NO and NO-)• The
final Gay Lussac tower is the primary source of emissions
in the chamber process. These emissions include
nitrogen oxides, sulfur dioxide, and sulfuric acid mist.
About 50 percent of the total nitrogen oxides is NO-,
which characterizes the exit gas by a reddish-brown
color.
6.72. The contact process uses a catalyst, vanadium
pentoxide, to oxidize the S02 to SO., in a catalytic
converter. The SO- gas is cooled in an economizer and
then passes to an absorbing tower where most of it is
absorbed in a circulating stream of 99 percent sulfuric
acid. The SO- combines with the water in the acid to
form more sulfuric acid. Any unabsorbed SO- passes
through to a stack to the atmosphere. The tail-gas
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Nitric Acid Plants
discharge from the absorbing tower constitutes the
only significant air-contaminant discharge from a
contact sulfuric acid plant. Most of these tail gases
consist of nitrogen, oxygen, and carbon dioxide, and
some sulfur dioxide but the S0« which is emitted will
hydrate and form a sulfuric acid mist upon contact with
the atmosphere. Under improper operating conditions,
startups or emergency shutdowns, the opacity of this
mist can be very dense. Minor mist emissions may come
from the converter, towers for drying SO,,, tank-car
vents, or leaks in the process equipment.
6.73. The predominant factor in the visibility of an
acid plant's plume is the particle size of the acid
mist rather than the weight of the mist discharged.
Acid particles larger than 10 microns deposit readily
on duct and stack walls and contribute little to the
opacity of the plume. Acid mist composed of particles
less than .10 microns in diameter is visible in the
absorber tail gases. As the particle size decreases,
the plume becomes more dense because of the greater
light-scattering effect of the smaller particles.
6.74. The ammonia oxidation process is the principal
method of producing commercial nitric acid. It in-
volves three main steps
(a) A mixture of ammonia (NH,) and air is passed
through a catalyst at high temperatures. Nitric
oxide (NO) and water are formed.
(b.X When the NO stream is cooled, the. NO reacts
with the oxygen remaining in the mixture to
form nitrogen dioxide (NO^i-
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(c) The N0_ is cooled further and is passed
to an absorber where it is absorbed in
water to produce a 50 to 60 percent nitric
acid (HNO-).
If a higher strength nitric acid is required, the weak
acid is processed in an acid concentrator where some
of the water is removed by mixing the nitric acid with
concentrated sulfuric acid in a dehydrating column.
Some gases are produced in this process and they are
passed through an absorber tower to recover weak nitric
acid.
6.75. The principal source of emissions in a nitric
acid plant is the absorber. The tail gases from the
absorber contain nitric oxide, nitrogen dioxide,
nitrogen, oxygen, and trace amounts of acid mist.
Small amounts of N0« are also lost from acid concen-
trators and acid storage tanks. Nitric oxide is a color-
less gas; nitrogen dioxide is red-orange-brown in color.
6.76. Abatement of the effluents from absorption
towers can be effected by mixing the gases with natural
gas and passing them over a catalyst bed. The nitrogen
dioxide and nitric oxide are dissociated and converted
into nitrogen, carbon dioxide, and water vapor. These
gases are then released from a stack.
Paint and Varnish Manufacturing
6.77. Protective coating manufacturing may include
the processing of pigments, natural or synthetic resins,
drying oils, solvents, driers, and plasticizers. The
pigments give the paint color and covering power. The
resins—such as rosin—contribute to the drying speed,
hardness, and gloss. The pigments are dissolved in
drying oils such as linseed oil, which by oxidation and
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polymerization (the combination of several simple
molecules into a complex molecule) forms a hard film
when applied to a surface. Solvents or thinners, such
as turpentine, reduce the viscosity of the paint so that
it can be spread easily. Upon application, they evapor-
ate from the surface. The driers, such as cobalt soap,
are catalysts which accelerate the hardening of the
oil film. Plasticizers may be added to keep the hardened
film elastic so that it will not crack when subjected to
vibration.
6.78. Much of the manufacturing process consists of
cooking these ingredients at elevated temperatures to
cause decomposition of the products. As long as the
cooking is continued, these decomposition products are
emitted to the atmosphere. A cook may average 8 to 12
hours. The quantity, composition, and rate of emission
depend upon the ingredients in the mix, maximum tempera-
ture, rate of heating, stirring, method of introducing
additives, and the extent of air or inert gas blowing.
6.79. Emissions include organics, odors, vapors, fumes,
gases, and particulate matter ranging from 2 to 20
microns in dimension. Scrubbers have little effect on
most of these small particles.
Hot-Mix Asphalt Batching Plants
6.80. All hot-mix asphalt plants incorporate the
following processes: conveying proportioned quantities
of cold aggregate (stone, gravel, and sand) to a dryer,
heating and drying aggregate in a rotary drier, screen-
ing and classifying the hot aggregate in bins, weighing
out the desired quantities of aggregate sizes, heating
the asphalt oil, mixing the hot aggregate and hot
asphalt in the proper proportions, and delivering the
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hot mixture into trucks which haul it to the paving
site. Strictly speaking, this mixture of aggregates
and asphalt cement should be called asphalt concrete
or bituminous concrete, but it is frequently referred to
as just "asphalt".
6.81. Dust originating in the aggregate is the major
atmospheric pollutant from asphalt plants, and the
principal source of this dust is the rotary drier.
The dust is carried out through the upper end of the
drier with the exhaust gases. Other important sources
of dust are the vibratory screens, unenclosed bucket
elevators, weigh hopper, storage piles and bins, and
traffic dust from the yard.
6.82. Most driers employ a single dry cyclone as a
precleaner, which collects 70 to 90 percent of the
exhaust dust. This precleaner catch is discharged
back into the bucket elevator where it rejoins the
heated aggregate and continues in the process. Of
the particulate emissions from the precleaner, 25
percent are between 5 and 10 microns and 35 percent
are less than 5 microns in diameter.
6.83. Elevators, hot bins, and screens are enclosed
and normally vented to the inlet of the secondary
collector. The stream of dust laden gases is combined
with that of the primary collector (cyclone or multi-
clone) serving the rotary dryer and this enters into
the secondary collector. By the use of high energy
scrubbers (approximately 30 inch H90 pressure drop)
or fabric filters, high removal efficiencies are
possible; however, a visible water vapor plume will be
emitted as part of the exhaust from the wet scrubber.
Since regulations have become more strigent, fabric
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filters are now in general use. Economics often
favor the fabric filter over the venturi scrubber
when meeting NSPS.
Phosphoric Acid Manufacture
6.84. Two processes are used to manufacture phosphoric
acid. High-purity acid for use in the food, detergent,
and plastic industries is produced by the thermal pro-
cess, also.called the phosphorus-burning process. The
wet process is used to manufacture less pure phosphoric
acid for the phosphate fertilizer industry.
6.85. Phosphate rock contains a compound consisting
of calcium, phosphorus, oxygen, and fluorine. This
compound can be reduced (driving off the oxygen), in an
electric furnace so that pure phosphorus is produced.
Pure phosphorus ignites immediately when exposed to
air; therefore, it is generally submerged under water.
For use as a raw material in the thermal-process phos-
phoric acid manufacture, the phosphorus is usually con-
verted to a liquid, placed under water, and shipped
in a tank car.
6.86. Thermal-process phosphoric acid manufacture in-
volves three steps:
(.a) Oxidizing (burning) the liquid phosphorus
by mixing it with air in a combustion chamber
to produce the compound phosphorus pentoxide
(P205) vapor.
(b). Passing the vapor into a hydrator where
it is mixed with water or weak phosphoric
acid to produce a higher strength phosphoric
acid mist.
(.c) Removing the mist from the gas stream in
an absorber. The strong phosphoric acid is then
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stored for shipment or is treated further
if it is to be used in the food industry.
6.87. The principal atmospheric emission from the
thermal process is the acid mist emitted from the
absorber that fails to be collected by the electro-
static precipitator or mesh-entrainment separators.
The mist particles are generally less than 5 microns
in diameter.
6.88. This mist is extremely hygroscopic so that,
unless there is a high collection efficiency, a
dense white plume of 100 percent opacity is emitted
from the stack. The plume may range from 40 to 50. per-
cent water vapor. Depending on weather conditions and
acid mist concentration, the plume usually dissipates
in a few hundred feet.
6.89. In the wet process of phosphoric acid manufacture,
finely ground phosphate rock is decomposed by sulfuric
acid in a reactor (pr digester), tank for a period of
several hours. During this process weak phosphoric
acid and gypsum crystals are created.
6.90. The slurry of these two compounds is sent to a
filter system (e.g., a tilting pan vacuum filter).,
where the gypsum cake is washed out leaving 32 percent
acid.
6.91. This acid is then concentrated to 54 percent in
an evaporator or concentrator.
6.92. Phosphate rock may contain as much as 4 per-
cent fluorine. Emissions from wet-process phosphoric
acid manufacture consist of rock dust, fluoride gases
(primarily silicon tetrafluoride), fluoride particulates,
and phosphoric acid mist.
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6.93. Most of the particulate emissions come from the
reactor and some from the filter. These participates
are often removed by wet collectors.
6.94. The reactor, the evaporator, and the filter
are all sources of fluoride emissions.
6.95. Most of the phosphate rock mined in the United
States is mined in Florida. This is where most of the
wet-process phosphoric acid plants are and where much
of the phosphate fertilizer manufacture is carried on.
Phosphate Fertilizer Manufacture
6.96. Three different manufacutring processes produce
three phosphate fertilizers, each having a different
grade of phosphorus pentoxide (P^O,-), nutrient. These
are normal superphosphate (18 percent), a triple super-
phosphate (45 percent or 54 percent)., and diammonium
phosphate (64 percent).
6.97. In each of these processes there are emissions
of particulates, silicon tetrafluoride and hydrogen
fluoride. The particulate dusts are visible; the
fluorides can cause damage to livestock through
fluorosis.
6.98. Many of the particulate emissions come during the
drying of the fertilizer and during the handling of it
on conveyor belts or in curing and storing sheds.
6.99. Dust is also produced in plants that granulate
the fertilizer or blend it. In graulation, the particle
size of the fertilizer is increased to aid in the handl-
ing and storage of the fertilizer.
6.100. Normal superphosphate fertilizer is being
replaced by high-analysis fertilizers. It is produced
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by mixing dry-ground phosphate rock with sulfuric acid.
The mixture is poured into a large enclosed container or
"den", where it solidifies. The solid is then shaved off
by cutters and stored for drying. The major portion of
the emissions comes from the storage building.
6.101. Triple superphosphate is produced by a contin-
uous process in which dried and ground phosphate rock is
mixed with phosphoric acid. The product can be treated
in several ways:
(.a) It can be discharged to a slowmoving belt
where it becomes solidified. Then it will
be stored in a curing building. After 30-60
days it is dug out from the "pile" in the
curing shed and crushed, screened, and shipped.
(b) It can be fed as a slurry to a "blunger"
where it is mixed by rotating blades and
granulation is begun. The granulation is
completed in heated dryer kilns.
(c). The cured and screened triple superphosphate
produced in (a) can also be passed through a
drum granulator in the presence of steam and
then dried in a horizontal rotary kiln.
6.102. The usual methods of control in the phosphate
fertilizer industry are scrubbers, inertial separators,
and fabric filters.
Soap and Synthetic Detergent Manufacture
6.103. The production of soap normally involves the
hydrolysis or "splitting" of fats to obtain fatty acids,
followed by boiling the fatty acids with-sodium or
potassium hydroxide in large kettles for several days.
6.104. After cooking, the soap is dried to remove the
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moisture and can be finished in several different forms-
bars, flakes, chips, or powder. The hot-air process is
used to dry the soap for bars, flakes, and chips. Soap
powder is finished by spraydrying—the blowing of hot
air upward in tall towers while soap drops are falling
downward.
6.105. Synthetic detergents are produced by combining
a fatty alcohol or linear alkylate with sulfuric acid
and then neutralizing it with caustic. The product is a
paste mixed with water. The paste is pumped to a
large Cpossibly 100 feet high by 20 feet in diameter)
spray .tower where it is dried to the desired moisture
content.
,6.106. The principal sources of particulate matter in
the making of soap and synthetic detergents are the
spray drying of products and the handling of dry raw
materials. Fabric filters are widely used to control
dusts from handling.
6.107. The hot exhaust from the tower contains fine
particles together with moisture evaporated from the
soap or detergent during the spray drying. Often, the
exhaust is passed through both a cyclone and a wet
scrubber before it is released.
6.108. The exhaust is close to the staturation tem-
perature, particularly if a wet scrubber is used, and
it will form a dense white plume that is principally
condensed water vapor.
Wet Plumes
S.109. Most air contains some amount of water in the
vapor or gaseous phase. Water in this vapor phase is
invisible. Only when it is changed to the liquid or
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solid phase does the water become visible as clouds,
fog, rain, snow, etc.
6.110. Relative humidity is one measure of the amount
of water vapor in the air. The warmer the air is, the
more water vapor it can hold without the vapor condens-
ing into the liquid state. Thus, the relative humidity
of air can be increased in two ways:
(.a) Adding more moisture,
Cb) Cooling the air.
6.111. If either of these methods for increasing
relative humidity is carried on long enough, the air
becomes saturated. Any more water vapor added or any
further cooling results in the excess water vapor
changing phase and becoming visible.
6.112. If hot, moist effluent is released to a
cooler atmosphere, the moisture will condense to form
an opaque white plume; if the relative humidity of the
atmosphere is high, this plume will persist for some
distance downwind from its emission point.
6.113. The visible water plumes may be objectionable
if they
Ca) Contribute to the formation of ground
fogs that obscure visibility for automobiles
or airplanes;
(b) Contribute to icing conditions when they
come in contact with very cold surfaces;
(.c) Combine with some other gas (such as sulfur
trioxide) to form a harmful pollutant (such
as sulfuric acid);
(d) Are aesthetically displeasing to the neighbors.
6.114. A pure water plume disappears without a trace.
It evaporates and mixes in all directions in a wispy
pattern.
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6.115. Plumes containing both water and dust will
leave a trail of particulates after the liquid water
evaporates. One method of "reading" these plumes to
observe infractions of equivalent opacity regulations
is to watch them at the point where the water vapor has
evaporated.
6.116. Other regulations specify that only plumes
containing "uncombined water" may be neglected in
enforcing equivalent opacity regulations. This means
that if the water plume contains particulates it should
be kept under surveillance for violation of visible
emissions standards.
6.117. Water plumes can be distinguished from plumes
of white particles in several ways:
(a) The wispiness of the plume as it evaporates;
(b) The greater frequency of occurence and a
greater length of plume in cold, wet weather
than in warm, dry weather;
(c) The detachment of the visible plume from the
top of the stack in hot; dry weather, when
it takes the plume longer to cool to its
•saturation point.
6.118. Water vapor can be emitted from
(a) .Drying operations that remove water by evapora-
tion from foods, chemicals, detergents, paper,
Pharmaceuticals, ores, etc.
(b) Combustion in .which hydrogen-containing fuels
are used. This is especially true of
natural gas combustion and the burning of wet
fuel.
(c) Air pollution control devices that use water
to remove the gases or particulates from the
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gas stream (for example, spray chambers, spray
towers, and venturi scrubbers).
(d) Evaporation of water to remove combustion or
chamical reaction heat from a process (for
example, forced and natural draft cooling
towers, operations for cooling hot gases
to protect pollution control equipment,
removal of the heat generated in the thermal
process of producing phosphoric acid).
6.119. If visible wet plumes must be eliminated, several
methods are available:
(a) Dilution of the plume by mixing it with hot
air;
(b) Superheating the plume prior to emission so
that it will disperse before it condenses;
(c) Condensing the water out of the plume by
cooling it prior to emission.
These are all expensive, however.
Suggested Additional Reading
The Chemical Process Industries, R. N. Shreve, Third
Edition, McGraw-Hill, New York, (1967).
Control Techniques for Particulate Air Pollutants,
NAPCA Publication No. AP-51, Washington, D. C., (1969).
National Technical Information Service, 5285 Port
Royal Road, Springfield, VA 22161.
Compilation of Air Pollution Emission Factors. Second
edition AP-42, (April 1973)_r U.S. Environmental
Protection Agency, Office of Air Quality Planning and
Standards, Research Triangle Park, NC 27711.
6-33
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Note: Above has been supplemented by six
supplements from July 1973 to April
1976.
Air Pollution Engineering Manual, edited by J. J.
Danielson, Publication No. AP-40, USEPA, 2nd edition,
(1973). National Technical Information Service,
5285 Port Royal Road, Springfield, VA 22151.
Background information documents for New Source
Performance Standards are available for those sources
shown in Section XVI of this manual. Where visible
emissions are discussed, rationale is given for the
selection of the opacity limitation.
Source: Standards Development Branch
(MD-13), Emission Standards
and Engineering Division, US
Environmental Protection Agency,
Research Triangle Park, NC 27711.
Field Surveillance and Enforcement Guide for
Primary Metallurgical Industries, US Environmental
Protection Agency, EPA-450/3-73-002, Research
Triangle Park, NC, (December 1973).. National Technical
Information Service, 5285 Port Royal Road, Springfield,
VA 22151.
US Environmental Protection Agency's Div. of
Stationary Source Enforcement, Washington, D.C.
issues inspection manuals and guidelines on various
industrial categories and a limited amount of these
are available at no cost from the EPA Library,
Research Triangle Park, NC, or at a nominal fee from
the National Technical Information Service, 5285 Port
Royal Road, Springfield, VA 22151 Non-combustion
documents are as follows: Emissions from Hot-dip
6-34
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Galvanizing Processes, EPA No. 905/4-76-002 NTIS No.
251910 Asphalt Concrete, EPA No. 340/1-76-003 NTIS
No. 245848/AS
6-35
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CHAPTER VII.
CLASSIFICATION AND IDENTIFICATION
OF SOURCES
Classification
7.1. One reason for classifying sources is to aid one
in discussing their emissions of pollutants. Measure-
ments have been made of the quantity and types of
pollutants emitted for a given amount of fuel or raw
material used in a process. Using these "emission
factors, [ the amount of pollutants emitted from power
plants, industry, automobiles, etc., can be estimated.
The arranging of sources into categories also makes it
easier to point out the similarities in plant appearance,
process equipment, and collection devices.
7.2. There are several categories into which one can
divide or subdivide air pollution sources:
(a) Mobile and stationary sources;
(b) Point and area sources;
(c) Combustion and noncombustion sources;
(d) Industrial, steam-electric, residential,
and commerical-industrial sources;
(e) Sources burning coal, oil, gas, or wood
versus sources not burning fuel such as
forest fires, agricultural fires, or
solid waste disposal;
(f) Reciprocal engines and continuous
combustion engines.
7-1
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7.3. Point Sources are ones whose emissions exceed
some designated value (for example, 50 tons/year).
Sources with smaller emissions can be grouped together
in some manner (for example, all the residences in a
certain square mile of a city) to constitute an Area
Source.
7.4. An example of a classification system that includes
all sources is
(a). Fuel Combustion in Stationary Sources
(1). Industry
(2) Steam-Electric Power Plants
(3) Residential
(4). Commercial-Institutional
(bl Fuel Combustion in Mobile Sources
(1)_ Motor Vehicles
(2) Vessels
(3) Railroads
(4). Aircraft
(c). Industrial Process Losses
(1). Chemical Processing
C2). Food and Agriculture
(31 Metallurgical
(.4), Mineral Products
(.5), Petroleum Refining
(6) Pulp and Paper
(7) Solvent Evaporation and Gasoline Marketing
(8) Other
(d). Solid Waste Disposal
(1) Municipal Incineration
(2) On-Site Incineration
(31 Open Burning
7-2
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Identification
(e) Miscellaneous
(1) Forest Fires
(2) Structural Building Fires
(3) Coal Refuse Burning
(4) Agricultural
(5) Other
7.5. These categories can be subdivided further, such
as into point and area sources; diesel-and gasoline-
powered vehicles; jet and piston-powered aircraft; and
particular types of industries.
7.6. Without experience an inspector must use various
methods and clues to determine the origin of the
visible plumes he sees.
7.7. To learn the nature of the process, he may use
books from the library or other sources describing
manufacturing. Also descriptive of the processes and
the air pollution arising from them are Federal
Government publications.
7.8 The inspector can learn about the processes and
their emissions by asking questions of his associates
and of plant operators, by observing process operations,
and by taking photographs of manufacturing operations
and noting the similarities between types of operations.
7.9. Clues to the origin of emissions can be obtained
from
(a) The Company's name;
(b) Directory of Manufacturers - often published
by Chamber of Commerce of the city or by
the state;
7-3
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(c) Air Pollution files of permits for construction
or for operation;
(d) Surroundings of the source such as objects
sitting in the yard. These might include
the fuel used, the raw materials, the products,
the waste material, and the trucks for carrying
out the product;
(e) The shape of the building housing the
process;
(f) Whether the source of emissions is a stack
or whether the emissions consist of dust
coming out of the building—called fugitive
dust;
(g) Color of the plume;
(h) Odor;
(i) Effects on metal structures, paint,
vegetation, etc.;
(j) Any collection devices for particles
such as scrubbers, cyclones, electric
precipitators, baghouses, ponds, etc.;
(k) Flares for burning waste gases;
(1) Any equipment that is visible such as furnaces,
towers, rotary driers;
(m) Any variation of the plume during the day
or during the year which might indicate
startup operations, batch operations, or
changes in operation with weather; is it a
continuous process for 24 hours a day or does
it cease at the end of the work day?
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7.10. Many visible plumes are wholly or partially
condensed water vapor plumes. An inspector should be
able to identify these since they generally are not
considered as violations of visible emission regulations,
Some sources of water vapor plumes include:
(a) Drying operations;
(b) Combustion operations in which the waste gases
are discharged at temperatures near the dew-
point;
(c) Air pollution control equipment that cleans
the plume by spraying it with water;
(d) Operations in which heat is removed by the
evaporation of water.
7.11. The inspector should be able to identify the
nature of the particulate, whether it is dust, fume,
smoke, mist, vapor, or gas.
7.12. If he knows what type of manufacture is going on,
then he should be able to identify the possible com-
ponent manufacturing processes and their equipment.
7.13. The inspector should determine whether the
emissions are in the form of a
(a) A plume;
(b) A cloud that has become completely
divorced from its source;
(c) A haze that exists over a portion but
not all of a community indicating that
a local problem is present;
(d) "Fugitive" emissions, which do not come
out of a stack but from windows and other
openings in a building.
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7.14. If the emissions are in the form of a plume, the
inspector should note
(a) Whether the plume forms at the top of
the stack or a few feet above the stack
(a detached plume);
(b) The body of the plume and how far it rises
before bending over; its shape after it
bends over can be described as coning, fanning,
or looping;
(c) The point at which it dissipates. This may
indicate whether the emission is smoke, fume,
or contains water vapor. A fume consists of
relatively heavy molten liquid droplets that
rapidly condense to a solid or a mist at a
dissipation point that is closer to the stack
outlet than is the case of smoke particles.
The water vapor portion of a plume may evaporate
leaving particulate matter that persists for a
longer distance.
7.15. For smoke emissions, the color is an indication
of the type of combustion problem or the type of fuel:
(a) Black or gray smoke indicates that the
material is being burned with inadequate
air or inadequate mixing of fuel and air.
(b) White smoke indicates either that the fire
is being cooled by excessive drafts of air
or that the materials being burned contain
excessive amounts of moisture.
(c) Brown or yellow smoke indicates the burning of
a semi-solid tarry substance such as asphalt
or tar paper. Generally, this fuel has not
been raised to a temperature that is hot enough
7-6
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for best combustion and the mixing with
air is inadequate.
(d) Blue smoke often results from the burning
of trash which consists of paper or wood
products. The plume is composed of small
liquid particles and contains only a few
particles of carbon or soot.
7.16. The inspector should make an initial identifi-
cation of a visible plume by placing it in one of the
following classes:
(a) Emissions from stationary combustion
sources which are operated to produce
energy;
(b) Emissions from mobile engines (e.g., gasoline,
diesel, jet);
(c) Emissions that are primarily or totally
water vapor;
(d) Emissions of particulate matter from
industrial processes;
(e) Particulate emissions accompanying
' construction or demolition;
(f) Emissions of visible gases;
(g) Emissions from open-burning incinerators,
agricultural burning, and structural
building fires.
7.17. The air pollution control officer should be
familiar with all of the sources of emission, the
process equipment, and the control devices located in
his area.
(a) Sources of visible plumes
(1) Steam-electric power plants
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(2) Steam-generating facilities for
institutions and schools
(3) Incineration equipment such as
tepee burners, single-chamber and
multiple-chamber incinerators, etc.
(4) Furniture, lumber, and wood products
industry
(5) Cement plants
(6) Carbon black plants
(7) Soap and detergent manufacture
(8) Petroleum refineries
(9) Steel mills
(10) Asphalt batching plants
(11) Phosphate fertilizer manufacture
(12) Phosphoric acid manufacture
(13) Pulp and paper manufacture
(14) Lime plants
(15) Copper, lead, and zinc smelters
(16) Nitric acid manufacture
(17) Coke manufacture
(18) Gray iron foundries
(19) Vehicles powered by internal
combustion engines
(b) Manufacturing process equipment
(1) Furnaces
(2) Kettles
(3) Ovens
(4) Cupolas
(5) Kilns
(6) Dryers
(7) Roasters
(8) Towers
(9) Cookers
7-8
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(10) Digesters
(11) Quenchers
(12) Columns
(13) Stills
(14) Crucibles
(15) Regenerators
(16) Flares
(c) Air pollution collection devices
(1) Cyclones
(2) Baghouses
(3) Electrostatic precipitators
(4) Wet collectors
(5) Scrubbers
(6) Dry centrifugal collectors
(7) Venturi scrubbers
(8) Afterburners
(9) Fabric filters.
Suggested Additional Reading
Compilation of Air Pollutant Emission Factors,
Second Edition AP-42 (April 1973) and six sup-
plements dated 7/73, 9/73, 7/74, 1/75 and 4/76,
US Environmental Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle
Park, NC 27711.
Control Techniques for Particulate Air Pollutants,
NAPCA Publication No. AP-51 Washington, DC (1969).
Available from National Technical Information Service,
Springfield, VA 22151.
"Identification of Effluent Plumes", in Field
Operations and Enforcement Manual for Air Pollution
Control, Vol. ±, USEPA.Publication No. APTD-1100,
Research Triangle Park, NC 27711 (1972).
7-9
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CHAPTER VIII.
RINGELMANN CHART AND
EQUIVALENT OPACITY
8.1. Regulations requiring that plume densities or
opacities not exceed a specified standard are logical
outgrowths of the original laws which prohibited
"excessive or repugnant" as a nuisance. It was a nui-
sance because it was "excessive or repugnant" to our
senses - sight, smell, and, possibly, touch. Thus,
an acceptable method of determining whether a plume was
a nuisance was to set an emission standard based on
visual determination of the effluent—how dense or opaque
was the plume?
8.2. It has been shown that with proper training an
inspector can evaluate the density or opacity of a
plume within 7.5 percent opacity, on the average, and
within 15 percent opacity for any individual reading,
as compared to measurements made by optical instruments.
When his training is supplemented by periodic retesting,
the inspector can maintain his plume reading proficiency.
Or this basis the courts have hpheld the Ringelmann and
Equivalent Opacity regulations when they are enforced
by qualified personnel.
8.3 Emission standards can relate to weight loading as
well . s optical density or opacity. Compliance with the
latter type is easier and cheaper to check. It requires
only that an inspector make.an observation for a
specified time period.
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8.4. Although the visual standard is limited to
estimations of particles of pollution that obscure
vision, its application simultaneously tends to reduce
the total weight of all sizes of particles emitted.
Thus, the visual emissions standard can supplement the
weight loading standard and help to reduce the number
of source tests the latter standard would require.
8.5. In some cases to comply with the opacity standard,
more efficient equipment operation or more efficient
combustion is required of a pollution source. In other
cases more efficient air pollution control devices may
be necessary. A general theoretical relationship
between plume opacity and particulate mass concentration
for several types of particles (carbon, liquid water,
and iron oxide) for a particular source has been
developed.
EPA has established opacity limits for new source
performance standards of several industrial facilities
as well as mass emission limits primarily because it
believes that opacity limits provide the only effective
and practical method for determining whether emission
control equipment, necessary for a source to meet the
mass emission limits, is continuously maintained and
operated properly. It has not been EPA's position that
a single, constant, invariant, and precise correlation
between opacity and mass emissions must be identified
for each source under all conditions of operation.
Such a correlation is unnecessary to the opacity
standard, since the EPA Administrator consistently
develops opacity standards for each class of source at
a level no more restrictive than the corresponding
mass emission limitation with due consideration given
to all conditions of operation. Any source meeting the
mass limit will therefore also be meeting the opacity
limit.
8-2
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8.6. An inspector's knowledge of the size distri-
bution of particle sizes and weights found in the stack
tests of various types of stokers, oil burners,
manufacturing processes, etc., may serve as a guide to
the relation between opacity and mass of effluent.
For example, if 75 percent of the weight of a plume is
in particles whose sizes are larger than 5 microns in
diameter and only 10 percent is in particles whose
diameters are less than 1 micron, then the portion which
is scattering light (0.4 to 0.7 micron) is small. Under
these circumstances, compliance with the visual standard
may not ensure the compliance with the loading standard.
8.7. The Ringelmann chart was developed about 1890
by Maximilian Ringelmann, a professor of agricultural
engineering in Paris. It was introduced into the
United States in 1897 and first incorporated into law
in Boston in 1910.
8.8. The chart is a method of judging the shade of
gray of a given smoke plume and was originally applied
to the emissions from coal-fired boilers.
8.9. Many regulations state that it is illegal to
emit smoke of a darker shade than Ringelmann No. 2
for more than 3 minutes in an hour. This 3-minute
grace period is allowed for starting up or soot
blowing.
8.10. The State of California through its Air Pollution
Control Districts in 1947 extended visual emission
standards beyond the use of the Ringelmann chart for
gray-black plumes. It also prohibited a plume of any
color if the plume's opacity was greater than that of
a plume with a shade of Ringelmann No. 2.
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8.11. While there are actually two regulations which
cover all plumes, both black and nonblack, one regulation
could be sufficient for regulating the opaqueness of
any plume. However, the Ringelmann standard historically
was established first and the equivalent opacity standard
was referred to the Ringelmann Chart. Actually, the
inspector generally judges the amount of light trans-
mitted through both black and nonblack plumes and then
relates this transmission to Ringelmann Numbers as a
measure of the smoke density of gray-black smoke and
equivalent opacity percentages for colored or white
plumes. If he compares the gray-black plume with a
Ringelmann Chart, he is equating the 60 percent of
light transmitted through a No. 2 plume with the 60
percent of light reflected by the No. 2 Ringelmann
Chart. The term "equivalent opacity" refers to the
extension of the Ringelmann Chart to judge the degree
to which a visible plume of any color obscures the
view of the observer. The statement of the equivalent
opacity regulation generally includes a clause stating
"such opacities as to obscure an observer's view to
a degree equal to or greater than does smoke of
Ringelmann No. 2 shade." In its new source performance
standards, the EPA relates all visible emissions with
opacity only. A few States and local agencies also
have dropped the use of the Ringelmann standard.
8.12. The definitions of the terms "smoke density"
and opacity are the source of much controversy and
confusion by defense attorneys attempting to invalidate
the entire smoke-reading procedure. The definitions
of these terms as they apply to visible emissions are
(a) Smoke Density - One definition of density
is "the quantity per unit volume or area."
Another is "the mass of substance per
8-4
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unit volume." In visual emission
usage the first definition is the
correct one. When applied to the
Ringelmann Chart, density refers to
the ratio of the area occupied by
the black grid lines to the total
areas of each card. Since these
grid lines are opaque areas, the
smoke density is compared with opacity.
The definition is not meant to refer
to the weight per unit volume of the
plume.
(b) Opacity - Opacity means the degree to
which transmitted light is obscured.
In air pollution, the expert reader
judges the amount of background, sky,
or light that he cannot see through the
emission.
The Ringelmann Chart
8.13. The Ringelmann system is a method of reproducing
shades of gray by means of a rectangular grid of black
lines having fixed widths on a white background. When
these grids are viewed from a distance, they appear to
form a uniform gray area.
8.14. There are five equal steps between white and
black. The grid lines are 10 mm apart for each card.
The spe< ifications for the square spaces between the
grid lines are
(a) Card 0 - all white (100 percent of the
light transmitted)
8-5
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(b) Card 1 - black lines 1 mm thick,
white spaces 9 mm square (81
square mm) - 80 percent trans-
mission
(c) Card 2 - black lines 2.3 mm thick,
white spaces 7.7 mm square (59
square mm) - 60 percent trans-
mission
(d) Card 3 - black lines 3.7 mm thick,
spaces 6.3 mm square (40 square
mm) - 40 percent transmission
(e) Card 4 - black lines 5.5 mm thick,
white spaces 4.5 mm square (20
square mm) - 20 percent trans-
mission
(f) Card 5 - all black - 0 percent
transmission.
The actual chart as provided by the Bureau of Mines
contains only cards 1 through 4.
Since the accuracy required of the chart will not be
1 percent or less, the difference between 59 percent
and 60 percent can be considered negligible.
8.15. The Ringelmann Chart published by the Bureau of
Mines is the chart that is referred to in air pollution
law. This chart provides the shades of Cards 1, 2, 3,
and 4 in a single sheet. These are known as Ringelmann
No. 1, 2, 3, and 4, respectively.
8.16. If the chart is used while observing smoke, it
should be mounted 50 feet from the observer at which
distance the lines on the chart merge into shades of
gray. The observer glances from the smoke, coming from
the stack, to the chart and notes the number of the
8-6
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card that most mearly corresponds with the smoke
shade. When the correspondence is not exact, the
reading can be made to the nearest I/A Ringelmann
Number. A clear stack is recorded as No. 0 and 100
percent black smoke is recorded as No. 5.
8.17. With proper experience during a training period,
an observer can fix the shades of the Ringelmann Chart
in his memory. The inspector may then make his
observations in the field without having a chart with
him. The Superior Court of Los Angeles has compared
this to one's not needing "a color chart in his hands
to recognize a red flower, a blue sky, or a black
bird."
Smoke Reading Aids
8.18. Although seldom used and difficult to obtain,
a number of smoke reading aids can be used to assist
in measuring the Ringelmann number of gray or black
smoke. None have the versatility of a trained inspector
under varying conditions.
8.19. Smoke Tintometer - This instrument used tinted
glasses graduated to the Ringelmann scale for comparison
with the smoke. It contains two apertures, one for
observing the smoke and one for viewing the clear sky
through the opening or through one of the tinted
glasses.
8.20. Umbrascope - This is a tube using tinted glass
segments which cover one-half of the field of view.
The smoke is seen through the other hald of the field
and is compared with the opacity of the glass. One
thickness of the gray glass gives 60 percent opacity
and is equivalent to Ringelmann No. 3. Additional
8-7
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thicknesses of glass give even greater opacity. Thus,
no opacity less' than 60 percent can be measured with
this instrument.
8.21. Smokescope - This instrument consists of two
barrels for receiving incoming light and one eyecup
for viewing. The stack is viewed through one barrel
of the instrument. Light from an area adjacent to
the stack enters the other barrel and illuminates a
circular standard density film. Half of this film
is equivalent to No. 2 Ringelmann and the other half
is equivalent to No. 3 Ringelmann. The image of these
two half disks is projected onto a screen in front
of the eyecup and this image surrounds a small aperature
where the smoke is seen. The observer then compares the
smoke shade with the two Ringelmann shades. The
advantage of this instrument over a Ringelmann Chart
used in the field is that the illuminations of the
smoke and the reference are both influenced by the
same factors. One is not transmitted light while the
other is reflected. Thus, the smokescope is automatic
compensation for varying light conditions.
8.22. Film Strip - This is called a Smoke Inspection
Guide and consists of four densities: 20 percent,
40 percent, 60 percent, and 80 percent transmission.
The inspector views the source and matches it as closely
as possible with one of the densities on the guide.
8.23. Smoke Comparison Charts - Several charts are
available and all of them work on the Ringelmann
principle. They have shades of gray corresponding to
Ringelmann Numbers 1, 2, 3, and 4 printed on a small,
pocket-sized card that the inspector can carry with him.
When making comparisons with a plume the inspector
should hold the card at arm's length.
8-8
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8.24. Photoelectric Cells - Photoelectric smoke-
metering equipment may be permanently built into a
stack. This device measures variations in the
intensity of a beam of light passing through the
effluent in the stack. As part of the granting of
a permit, these may be required to be mounted on a
stack for continuously monitoring the emissions. In
these devices, a constant light source is used to
illuminate, a standard photoelectric cell that is
located on the opposite side of the stack. The light
must pass through any smoke rising in the stack before
it reaches the cell on the opposite side. The photo-
electric cell produces a current of electricity that
is directly proportional to the amount of light falling
on the cell.
The main problem with most of these devices is in trying
to periodically zero the photocell, especially in
continuously operating stacks. Emission buildup on
the light source and on the photocell also creates a
problem.
8.25. All of these smoke-reading aids, except the
photoelectric call, can be used only with the black-
gray plumes. There are no aids in this nature for
assisting the inspector in judging those plumes which
fall under the equivalent opacity regulation.
8.26. The Smoke Reading Aids are sometimes cumbersome
and are generally not significantly more accurate than
sight reading in establishing opacity violations.
8.27. The lidar (or laser radar) instrument has been
proposed as a method of measuring smoke-plume opacity.
The lidar is composed of a laser transmitter that emits
a very brief, high-intensity pulse cf coherent light
and a receiver that detects the portion of this light
8-9
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being back-scattered to the instrument from the aero-
sols in the atmosphere. When plume opacity is measured,
the lidar light is shot through the plume and is
scattered backward by the aerosols. The receiver
measures the amount of reduction in the intensity caused
by the two passages of the light through the plume. At
present, this instrument is still quite expensive for
routine usage.
Training of Inspectors
8.28. Enforcement agencies have found it possible to
train observers to recognize Ringelmann numbers and
percent opacities without having a comparison chart
before them. The inspectors are taught to judge the
plume shade or opacity by relating it to percent of
light transmission of a training plume. The training
plume is generated by special equipment that regulates
the opacity of the plume and measures the opacity by a
photocell arrangement in the stack of the generator.
8.29. Training with the smoke generator begins by
familiarizing the students with known densities of
black and white smoke. Upon the sound of a horn the
instructor calls out the meter reading. He will go up
and down the Ringelmann and Equivalent Opacity scales.
8.30. Next, the students are given a practice run of
25 black and 25 white shades of smoke. At the comple-
tion of this run, a student can grade his performance
and determine whether he was reading high or low.
8.31. After these familiarization and practice runs,
the students are ready for testing for record. Re-
peated runs of 25 white and 25 black shades of smoke
are made with the smoke generator. In between test
8-10
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runs, short familiarization runs may be made to
reinforce the student's accuracy of judgement.
8.32. A student keeps on observing the testing runs
until he qualifies as an expert smoke reader. The
requirements are that he must read white and black
smoke with an average error not to exceed 7.5 percent
opacity in each category and with an error not to exceed
15 percent opacity (or 3/4 of a Ringelmann number) on
any reading in each category.
8.33. Additional training may be allowed if the student
does not meet the standards. However, if the student
is unable to pass the visible emissions test, he can
be disqualified from serving as an inspector.
8.34. Training runs may be conducted under a variety
of conditions of lighting and background color to
simulate actual field conditions.
8.35. To evaluate plumes at night it is necessary to
have a source of light behind the plume and to evaluate
the transmission of this light through the plume.
Nighttime readings should be made a part of the train-
ing program if the inspector will be required to make
field evaluations at night as part of his duties.
8.36. Readings can also be made of smoke from tailpipes
or exhausts of moving vehicles. The observer should
(a) Read the smoke at its point of
maximum density;
(b) Use a stopwatch to record the
accumulated violation time;
(c) Avoid reading directly into the
long axis of the plume, if possible.
It may be difficult to have a wide
angle between his line of sight and
the line of exhaust smoke.
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(d) Take a photograph of the offending
vehicle and its plume.
Problems of Reading Smoke
in the Field
8.37. There are several criticisms of visible emission
control regulations and the ability of inspectors to
enforce them objectively. Many of these criticisms
can be overcome by the inspector's following proper
procedures in his field.
8.38. Criticism: The opacity or smoke density obser-
vation made by an inspector will vary according to the
position of the sun, the atmospheric lighting, the
background of the plume, and the size of the particles
in the plume.
Response: The inspector should strive to make his
observations with the sun in the 140 degree sector to
his back, with the wind blowing at approximately
right angles to his line of sight, and with a back-
ground that contrasts with the color of the plume.
Multiple observations under varying atmospheric conditions
can also be made to reduce the effects of the back-
ground and atmospheric lighting. An experienced
observer can learn to weigh the opacity conditions in
relation to various conditions.
On the other hand, wide variations of the sizes of
particles in a plume will affect the light-scattering
potential of the plume. In most cases it is the varia-
tion in mass emission rates that affect the opacity.
8.39. Criticism: Opacity and smoke-density measure-
ments have not been correlated with other measurement
methods.
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Response: For two types of particles, D. S. Ensor
and M. J. Pilat have developed a relationship between
plume opacity and a combination of the following
properties: plume diameter, particle size distribution,
particle mass concentration, average particle density,
and particle refractive index. Thus, their equation
includes more variables than plume opacity and mass of
emissions; however, if certain assumptions are made,
predictions of plume transmittance can be related to
particulate mass concentration. The observer should
have a knowledge of the processes emitting a visible
plume so that he can make a judgment of how normal its
appearance is. Its appearance may vary with the se-
quence of startup operations or with the atmospheric
relative humidity.
It is reasonable to assume that the elimination of
visible emissions will reduce dust and aerosol emissions;
however, the reduction may not be in the same ratio.
The small particles between 0.1 and 1 micron that
cause the light scattering require more expensive
control equipment than the large particles (greater
than 10 microns), which obscure light by absorbing it.
8.40. Criticism: Gaseous emissions cannot be deter-
mined by visible observations.
Response: Very few gases are visible, consequently,
visible emission regulations can constitute only a
portion of a full set of air pollution regulations.
The opacity of a reddish-brown plume of nitrogen dioxide
gas from a nitric acid plant will indicate the amount
of that pollutant that is being emitted. A bluish plume
for a boiler burning fuel oil will be an indication of
the high sulfur content of the oil.
8-13
-------
8.41. Criticism: Visible-emission observations are
difficult to apply at night.
Response: If the observer positions himself so that
there is a source of light behind the plume or places
an auxiliary light source behind a plume, then he may
make readings at night.
8.42. Criticism: A wet plume may be judged as opaque
although its opacity is really due to the water droplets,
which are not considered as pollutants.
Response: Since uncombined water is not normally con-
sidered as an air pollutant, some allowance must be
made for those visible plumes whose opacity is derived
from uncombined water droplets. One method is to
require that opacity readings of a wet or steam plume
be taken at that point of the plume where the steam
has evaporated. If the inspector suspects that the
source is in violation, it may be necessary to wait
for a hot, dry day when the steam rapidly dissipates.
He can then make his observation closer to the stack.
8.43. Criticism: Visible-emission regulations can be
circumvented by a polluter if he adds more air to his
effluent or builds a new stack of smaller diameter for
emitting the same quantity of effluent.
Response: The adding of auxiliary air to the effluent
in the stack will reduce the concentration of the
pollutant and will reduce the opacity of the plume.
The adding of air to the plume to obtain a lower
concentration is specifically prohibited in "circum-
vention" clauses of some regulations. These prohibit
the building and operation of equipment that tends to
conceal the emission.
8-14
-------
By decreasing the radius of the stack, the distance
through the plume will decrease and, since the velocity
of the emission increases, the concentration of the
effluent through the plume will remain the same. The
result is that since the light will pass through a
thinner plume, less light will be scattered and the
observer will read a lower opacity.
A narrower stack may not fall under the circumvention
clause. In this case it may be necessary to order a
source test to determine if there is a violation of a
process weight, emission weight, or concentration
ordinance.
It is also possible that the most opaque portion of the
plume may occur at some distance above the stack where
the emission loses its buoyancy. The best time for
observing such a condition would be a day with little
or no wind.
8.44 Criticism: Visible emissions from a point
source within a building cannot be read within the
building.
Response: The observer should be able to read visible
emissions within a building the same way he makes
readings at night. There may be some legality involved
whether or not local regulations allow this. Los
Angeles County gets around this by stating in their
regulations that emissions within a building is consid-
ered emissions to the open atmosphere.
Advantages of Visible
Emission Regulations
8.45 Observers can be trained in a relatively short
time and it is not necessary that observers have an
extensive technical background.
8.46. One man can make many observations in a day.
8.47. No expensive equipment is required.
8-15
-------
8.48. Violators can be cited without resorting to time-
consuming and costly source testing. A particulate
source test takes a minimum of 1 day for a single stack
plus the time needed for laboratory analysis and report
writing at a minimum cost of $1,000 per source.
8.49. Questionable emissions can be located and then
the actual emissions determined by source tests, if
necessary.
8.50. Control can be achieved for those operations not
readily suitable to regular source testing methods,
such as leakage from equipment and buildings; loading
of grain, coal, and ores; or visible automobile or truck
exhaust.
Suggested Additional Reading
"Ringelmann Smoke Chart," U.S. Dept. of the Interior
Information Circular 8333, (1967). Publications Center,
Bureau of Mines, 4800 Forbes Ave., Pittsburg, PA. 15213.
Optical Properties and Visual Effects of Smoke Stack
Plumes, W. D. Conner and J. R. Hodkinson. PHS Publi-
cation No. 999-AP-30, DREW, Research Triangle Park,
N.C. 27711 (1972).
"Plume Opacity and Particulate Mass Concentration,"
M. J. Pilat and D. S. Ensor, Atmospheric Environment,
Vol. 4, pp. 163-173 (1970).
"Calculation of Smoke Plume Opacity From Particulate Air
Pollutant Properties," D. S. Ensor and M. J. Pilat,
Presented at 63rd Air Pollution Control Association
Meeting in St. Louis, Missouri, June, 1970.
8-16
-------
"The Relationship Between the Visibility and Aerosol
Properties of Smoke Stack Plumes," D. S. Ensor and
M. J. Pilat, Presented at the Second International
Union of Air Pollution Prevention Associations in
Washington, D. C. (December, 1970).
EPA Response to Remand Ordered by U. S. Court of Appeals
for the District of Columbia in Portland Cement
Association v. Ruckelshaus, EPA-450/2/74/023 OAQPS
Research Triangle Park, N. C. 27711 (November, 1974).
8-17
-------
CHAPTER IX.
QUALIFICATION PROCEDURES AND
EXERCISE IN RECORDING FOR
QUALIFICATION
9.1. The proficiency test requires the inspector to
observe 25 shades of black smoke and 25 shades of white
smoke.
9.2. To qualify, the inspector must read each shade
with no deviations greater than 15 percent opacity or
3/4 of a Ringelmann number. His average deviation must
be no more than 7.5 percent opacity for each category.
9.3. The field portion of this course consists of read-
ing series of 25 black and 25 white shades of smoke
produced by the smoke generator.
9.4. There will be some familiarization runs of both
black and white smoke during which the opacity or
Ringelmann number will be announced while the smoke is
being emitted.
9.5. There will then be a practice run of 50 smoke
emissions. Twenty-five black shades will be run follow-
ed by 25 white shades Or vice versa. The student will
record his observations to the nearest 1/4 Ringelmann
number or the nearest 5 percent equivalent opacity. At
the conclusion of the 50 emissions, the student will
compare his readings against the transmissometer readings,
record his deviations, and complete his average deviation.
9.6. Following the practice run there will be repeated
runs of 50 emissions during which the student will try
to refine his smoke-reading ability until he meets the
requirements of average deviation not to exceed 7.5
9-1
-------
percent opacity for each category, and no reading
deviating more than 15 percent opacity (or 3/4
Ringelmann).
9.7. A Smoke School Training Form will be used to
record the readings and deviations and to compute the
information required for qualification. It also has
spaces for information regarding the observer, the
time of day, the weather, and the observer's position
in relation to the wind direction, the sun, and the
background for the smoke.
9.8. This form must be filled in completely when it is
submitted to the examiner by the student who has quali-
fied on a series of emissions.
Instructions to the Student
During the Reading of Smoke
9.9. The aim of the training and testing of smoke
readers in this course is to produce an inspector whose
judgment of plume density will be accurate and unaffect-
ed by variable field conditions. His expert observations
serve in place of the measurements of a mechanical device,
and his accuracy must stand up if the case is brought
to court.
9.10. To aid the accuracy of inspectors and to promote
uniformity among inspectors' readings, several rules of
smoke reading should be followed while the smoke reader
is making his observations:
(a) The sun should be within a 140
sector behind the observer during
daylight hours. This avoids the
problems arising from the forward
scattering of light by the particles
in the plume.
9-2
-------
(b) A light source should be behind
the plume at night.
(c) Readings should be made at
approximately right angles to
the wind direction, and from any
distance necessary to obtain a
clear view of the stack and back-
ground. This might be from 100
feet to 1/4 mile in the case of
stacks in the field but not
closer than 50 feet in the case
of observing the plumes from the
smoke generator.
(d) For plumes not containing water
vapor, the inspector should estimate
the plume density at a point only a
foot or two above the stack at which
height the plume is no wider than the
diameter of the stack. The inspector
should make his observations of water
vapor plumes in accordance with local
ordinances.
(e) The inspector should try to read the
plume against a contrasting background
such as blue sky for black plumes and
tree leaves for white plumes.
(f) The inspector should not stare at the
plume, but should look at it only at
the prescribed 15 second interval.
Staring at the plume will cause fatigue
and produce erroneous readings.
9-3
-------
9.11. During the inspector's training and testing with
the smoke generator, a horn will be sounded when he
should look at the plume and make his observation. In
between the soundings of the horn he should not stare
at the plume. The time interval between the sounding
of the horn and the glancing at the stack top by the
observer is approximately the time it takes the generator
smoke to travel from the generator's transmissometer to
the top of the stack.
9.12. If the local agency permits it, the inspector may
use small, hand-held Ringelmann Charts or other aids as
guides in judging the black and gray shades.
9.13. The inspector should not wear dark glasses while
taking the test unless he plans to wear these glasses
while making smoke readings in his normal enforcement
and inspection duties.
Filling Out the Training Form
9.14. Name and Affliation of the observer are self-
explanatory, as is the Date of the test.
9.15. The Time should be the approximate time when the
switch between black and white smoke was made.
9.16. Location refers to the address and city where the
test was given.
9.17. The Wind Speed should be estimated by the observer
within a 3 to 5 mile-per-hour range. If an anemometer
(wind speed instrument) is not available, he may estimate
the wind speed by using the Beaufort wind scale.
9-4
-------
9.18. To determine the Wind Direction the observer
must first know his orientation with respect to north.
This can be learned from a map. The direction from which
the wind is blowing can then be estimated to 16 points
of the compass (N, NNE, etc.) by watching a 2lag or
seeing which way a handful of grass blows when thrown
into the air.
9.19. Sky Condition should be filled in as:
(a) Clear - less than 0.1 of the sky
covered by clouds;
(b) Scattered - 0.1 to 0.5 of the sky
covered;
(c) Broken - 0.5 to 0.9 of the sky
covered;
(d) Overcast - more than 0.9 of the
sky covered.
9.20. Observer's Position should show his position in
relation to the sun, the smoke generator, and the
plume.
9.21. Run No. - Each run during the training session
will consist of 25 black (B) and 25 white (W) shades of
smoke. The runs will be numbered successively be-
ginning with 1-B and 1-W.
9.22. The student will enter his observations in the
Observer's E.eading columns. The black smoke readings
should be entered as fractions of Ringelmann Numbers,
with 0 being the lowest and 5 being the largest. The
minimum increment is 1/4. If appropriate in relation
to the laws or regulations of the jurisdiction in which
the students work, the observations of black smoke may
be recorded in opacity, to the nearest 5 percent. The
9-5
-------
white smoke readings should be entered in percent
opacity. The lowest possible reading is 0 and the
highest is 100. The observations are made to the
nearest 5 percent.
9.23. At the end of the run the instructor will read
off the transmissometer readings and the student should
enter these values in the Transmissometer Reading
columns.
9.24. The student will then fill out the Deviation
columns. If the observer's reading is less than the
transmissometer readings, the difference is entered in
the - Deviation column.
9.25. In computing the deviations for the black smoke
readings, it will be more convenient to convert the
fractional Ringelmann number differences into percents,
similar to the white smoke. A deviation of 1/4
Ringelmann is equivalent to 5 percent, 1/2 to 10 per-
cent, 3/4 to 15 percent, 1 to 20 percent, and so on.
As can be seen, these conversions to percentages are
done by multiplying the Ringelmann deviations by 20.
9.26. The entries in the + Deviation and - Deviation
columns are added and their Sum is entered at the bottom
of the column. The Number of deviations in each column
is also entered at the bottom of the column. These
entries can be used by the student to guide him as to
whether he is tending to read high or low. If he
divides the sum of his deviations by the number of
deviations, he can estimate how high or low he is
reading.
9.27. In the QUALIFICATION portion of the form, the
two sets of boxes refer to the black and white portions
of the run.
9-6
-------
9.28. In the first set of boxes enter the run number.
9.29. In the second set of boxes, enter the number of
readings on which the observer agreed exactly with the
transmissometer reading.
9.30. In the third set of boxes, enter the number of
readings on which the observer disagreed with the trans-
missometer by more than 3/4 of a Ringelmann Number (black)
or by more than 15 percent equivalent opacity (white).
9.31. Calculate the average deviation on the black and
then the white portion of the run by adding the sum of
the + Deviations to the sume of the - Deviations and
dividing this by the number of readings (25).
9.32. The Examiner will verify the Training Forms of
those students who will qualify.
9.33. To qualify, the student must have no readings
of black or white smoke that deviate by more than 3/4
of a Ringelmann Number or more than 15 percent equiva-
lent opacity, and his average deviation for white and
for black smoke must both be less than 7.5 percent.
Suggested Additional Reading
Guidelines for Evaluation of Visible Emissions, R.
Missen and A. Stein. EPA Contract #68-02-1390,
Publication No. 340/1-75-007, U. S. Environmental
Protection Agency, Washington, D. C. (April, 1975).
"Smoke Reading School," in Field Operations and Enforce-
ment Manuaii for Air Pollution Control, Volume 1, pgs.
4.28 - 4.32. EPA Publication No. APTD-1100, U. S.
Environmental Protection Agency, Research Triangle
Park, N. C. 27711.
9-7
-------
ENVIRONMENTAL PROTECTION AGENCY
VISIBLE EMISSION TRAINING FORM
1. Name of Observer
2. Affiliation
3. Date
Time
4. Wind Speed
5. Observers Position
6. Corrected By
Direction,
Sky Condition,
Record Black and/or White Smoke in Percent Opacity (for example: 5 percent smallest division)
RUN NO.
o
oo
c
•o
OC.
1
2
3
4
5
6
7
8
9
10
11
12
|S?
^'•5
jS S
ooe
Transmissometer
Reading
o
"2
0)
0
+
c
o
2
'»
a:
13
14
15
16
17
18
19
20
21
22
23
24
25
I.E
55 -a
£ S
0°=
Transmissometer
Reading
+ Deviation 1
— Deviation
RUN NO.
•
o
.5
•3
ra
o>
OC
1
2
3
4
5
6
7
8
9
10
11
12
S.s
m -O
* S
«-i O)
00=
Transmissometer
Reading
-*• Deviation
—Deviation
d
BO
(=•
•o
ra
a>
a:
13
14
15
16
17
18
19
20
21
22
23
24
25
g f
* "2
^ s
oo:
Transmissometer
Reading
c
o
ro
'>
o>
o
+
—Deviation |
8. Number Correct
9. Number of Plus Deviations
10. Number of Minus Deviations
11. Average Plus Deviations : Sum of Plus Deviations
No. of Plus Deviations
12. Average Minus Deviations = Sum of Minus Deviations
No. of Minus Deviations
13. Average Deviation ^ (Sum of Plus Deviations) + (Sum of Minus Deviations)
I + (Si
3. of Re
Total No. of Readings
14. Number of Readings 20% Deviation and Over (or 1 Ringeimann and more)
9-8
7.
8.
9.
10.
11.
12.
13.
14.
-------
CHAPTER X
BASIC METEOROLOGY
10.1. Primary Meteorological Factors Affecting Concen-
tration of Air Pollutants-There are two meteorological
factors of primary concern in the life cycle of an air
pollutant. These are wind and stability. As Figure 10-1
indicates, we can think of wind primarily as the horizon-
tal motions and fluctuations of the air, while stability
can be thought of as an index of vertical turbulence.
Since the diffusion of pollutants in the atmosphere is
basically dictated by the amount of motion or turbulence
in the atmosphere around the source, we can begin to see
very quickly why wind and stability are of basic concern
to the air pollution meteorologist.
W|ND "DIRECTION
'SPEED
10-1
-------
Wind
10.2. Meteorologists usually consider two obvious
factors in relation to wind. They are wind direction
and speed. When considering the winds at a particular
point or over an area, we need to remember that the
wind direction is the direction from which the wind
blows. Figure 10-2 is a segment of a weather map
representing the weather conditions reported at several
stations. Note the little flag or arrow that extends
from the station circle at Miles City, Montana. This
points or flies from the northwest and tells us that the
wind is a northwest wind...a wind that blows from the
northwest. If you consider this as a "wind arrow" with
the speed indicated by the number and length of the
barbs, or "feathers," then the arrow flies with the wind,
toward the station circle.
In studying the wind patterns-or wind climatology-for a
certain location, meteorologists construct what is known
as a wind rose. A wind rose is a graphical representa-
tion of the percent frequency with which winds from a
certain direction occur. On the wind rose shown as
Figure 10-3, note that the winds from the northwesterly
direction occur about 15% of the time, with winds from
the south and the south-southeast also occuring frequently.
This wind rose indicates that the prevailing winds are
from the south-southeast. A wind rose, then, provides
a picture of the patterns of wind direction. Wind direc-
tion determines the source-receptor relationship in air
pollution. More simply speaking, wind direction deter-
mines who and what will be affected by emissions from
•sources. Information about the frequency of wind direc-
tion in a given area can be useful in basic planning
for the locations of industrial operations with respect
to residential areas.
10-2
-------
SURFACE WEATHER MAP
AND STATION WEATHER
SURFACE WEATHER MAP
AND STATION WEATHER
AT 1:00 A. M., E. S. T.
10-3
-------
WIND ROSE
- PERCENT FREQUENCY
SEATTLE, WASHINGTON
BOEING FIELD
OCTOBER, 1962
Figure 10-3
Wind speed is a second consideration. Table 10-1 is the
Beaufort Scale of wind-speed equivalents. A lay person
can estimate wind speed by this table. Wind speed has
as great a significance as wind direction in how a
receptor will be affected as illustrated in Figure 10-4.
Low wind speeds or calm conditions will extend the "life
cycle" of pollutants by allowing various chemical and
photochemical reactions to occur that produce secondary
pollutants. Ground level concentrations of pollutants
will be lower when high winds bring in fresh air to di-
lute the pollutants further. Mechanical turbulence,
which results from winds moving over rough terrain, can
increase and will hasten the gravitational settling of
particulate pollutants, as well as speeding the disper-
sion of pollutants in the atmosphere. High wind speeds
are generally favorable for the dispersion and transport
of air pollutants.
10-4
-------
Table 10-1
The Beaufort Scale of Wind-Speed Equivalents
General
Description
Calm
Light
Gentle
Moderate
Fresh
Strong
Gale
Whole gale
Hurricane
Specifications
Smoke rises vertically.
Direction of wind shown by smoke drift
but not by wind vanes.
Wind felt on face; leaves rustle;
ordinary vane moved by wind.
Leaves and small twigs in constant
motion; wind extends light flag.
Raises dust and loose paper; small
branches are moved.
Small trees in leaf begin to sway; crested
wavelets form on inland waters.
Large branches in motion; whistling heard
in telegraph wires; umbrellas used with
difficulty.
Whole trees in motion; inconvenience
felt in walking against the wind.
Breaks twigs off trees; generally
impedes progress.
Slight structural damage occurs (chimney
pots and slate removed) .
Trees uprooted; considerable structural
damage occurs.
Rarely experienced; accompanied by
widespread damage.
Miles per Hour
Limits of Velocity
33 feet (10 m)
above level ground
Under 1
1 to 3
4 to 7
8 to 12
13 to 18
19 to 24
25 to 31
32 to 38
39 to 46
47 to 54
55 to 63
64 to 75
Above 75
10-5
-------
r~
SHORTEN TIME POLLUTANTS ARE
AVAILABLE FOR PHOTOCHEMICAL-
REACTION " — -^
INCREASE MECHANICAL
TURBULENCE ^
Figure io-4ihe volume of air in which pollutants can be diluted is directly
proportional to the wind speed.
The wind around a particular point at a given time is
influenced by a number of forces. Three factors are im-
portant in the flow of air: the pressure gradient force,
the Coriolis effect, and the effects of surface features
and topography.
Pressure Gradient Force
10.3. Wind, or air flow, results basically from the presence
of high and low pressure systems. Pressure, in meteoro-
logical terms, is simply the weight of the atmosphere.
Cool air weighs more than warm air. A high pressure
system then, is a mass of cool, relatively heavy air,
while a low pressure system consists of warm, relatively
light air. The rate and direction of the pressure differ-
ence between areas of high and low pressure is know as
the pressure gradient. The pressure difference exerts
a force on an air parcel, causing it to move from the
area of high pressure to the area of low pressure. This
force is called the pressure gradient force. Thus, winds
will tend to blow from a high pressure area to a low pres-
10-6
-------
Coriolis Effect
sure area. Figure 10-5-a shows the pattern of wind flow
related to the pressure gradient force. Figure 10-5-b
shows this air flow from high to low pressure in a cross-
sectional view. Air will tend to spiral out near the
surface of the earth from the center of a high pressure
system, and cool, heavier air from aloft will sink to
replace it. Air will tend to spiral in toward the center
of a low pressure system, and this warm air will rise.
The pressure gradient force then, sets the air in motion
from an area of high pressure to an area of low pressure.
10.4. The basic flow of air is deflected by the Coriolis
force. In reality, this is not a force at all, but an
effect resulting from the rotation of the earth, and
the movement of air relative to the earth's surface.
From a fixed point on the earth, it appears to us that
there is a force that deflects winds to the right in the
northern hemisphere, and to the left in the southern
hemisphere. So any wind flow caused by the pressure
gradient force will be deflected or altered slightly
by this Coriolis effect, as shown in Figure 10-6.
Please study Figure 10-7. Imagine two winds over North
At erica, a wind blowing from the south along the meridian
at 90 W and a wind blowing from the west along the parallel
at 40 N. Four hours later the earth has rotated to the
east 60 , one-sixth of a total rotation. To an observer
from -»uter space the wind directions have not changed.
They ,.ave maintained their original absolute direction
with respect to a point in space, while the earth under-
neath has turned. To an observer on the earth, however,
it appears that these winds have bf-.en deflected to the
right. And indeed, since the meridians and parallels
have rotated and changed absolute direction, the original
10-7
-------
a.
Weak gradient
Clockwise flow around a
high pressure area in HIGH
the Northern Hemisphere.
Steep gradient
Surface winds —^
Wind above
3000 ft. >•
Counterclockwise flow
around a low pressure
LOW area in tne Northern
Hemisphere.
Pressure gradient is the rate and direction of pressure change. In the
drawing abovf (and on weather maps) the solid lines are isobars, lines
of equal pressure. Where the isobars are close together, the pressure
change is rapid, and the pressure gradient is "steep" or high in magni-
tude. Here the pressure gradient will exert a greater accelerating
force, and there will be greater wind speed. Weak winds can be associ-
ated with widely spaced isobars, where there is a weak gradient. The
direction of the wind flow is from high to low pressure. But the rota-
tion of the earth will cause this wind flow to be indirect.
b.
HIGH
PRESSURE
Flow of air from a high pressure area to a low pressure area caused by the
pressure gradient force.
Figure 10-5
L
10-8
-------
DEFLECTION
TO THE RIGHT IN THE
NORTHERN HEMISPHERE
TO THE LEFT IN THE
SOUTHERN HEMISPHERE
Figure 10-6
Deflection of the winds by the Coriolis effect,
8=OO AM 12=OO N
A B
Figure 10-7 Coriolis force.illustrated.
10-9
-------
south wind now appears to be from the southeast, and the
west wind is now from the northwest. Thus the Coriolis
force, or the Coriolis effect as it can more accurately
be called, is the deflecting force of the earth's rota-
tion, which causes winds, and all other moving objects,
to appear to be deflected to the right of their direction
of movement in the northern hemisphere, and to the left
in the southern hemisphere.
This is a rather difficult concept to really understand.
However, you should remember that a given air flow re-
sulting from the pressure gradient force will be deflected
to the right in the northern hemisphere.
Topographical Features
10.5. To this point, two basic influences acting on the
winds have been presented: the Coriolis effect (a global
or macroscale phenomenon), and the pressure gradient force
(a synoptic or continental scale phenomenon). On a still
smaller scale, the direction and force of the winds near
the surface of the earth are influenced by the presence
of topographical features, buildings, and bodies of water.
Some of these are shown in Figure 10-8. This friction, or
drag, of the surface features tends to slow the winds and
change the direction of their flow, so that there are
frequent local variations from the basic flow set up by
the pressure gradient force. There are, then, at least
three effects acting on the winds, ranging from the
largest to the smallest scale of motion - the Coriolis
effect, the pressure gradient, and the topographical
features.
10-10
-------
Figure 10-8 Friction and drag of topographical features also act to change
and influence the winds on a local or regional basis.
Stability
10.6. The second meteorological parameter of basic con-
cern to the air pollution expert is stability. Stability
is defined as the tendency of the atmosphere to enhance
or suppress vertical motions. The amoun': of vertical
motions. The amount of vertical motion in the atmos-
phere over a polluted area will, in part, determine
hovr quickly and effectively these pollutants are dis-
persed through the atmosphere. An index of vertical
motion can be determined by investigating how the
temperature changes as we ascend in the atmosphere.
This Is usually done at weather stations by releas-
ing a radiosonde (Figure 10-9). This box carries sen-
sors and a radio transmitter. As the radiosonde
ascends through the atmosphere it ^ends back informa-
tion about temperature, pressure, and humidity at
various altitudes.
10-11
-------
BOX CONTAINING
INSTRUMENTATION
INCLUDING PRESSURE,
TEMPERATURE, AND
HUMIDITY SENSING
ELEMENTS.
Figure 10-9 Radiosonde
—RADIO TRANSMITTER
What sort of picture emerges from these readings? -
Normally, the air near the earth's surface is slightly
warmer than that aloft. The warmer, lighter air will
rise, and the cooler, heavier air will sink and re-
place it. This causes an overturning or mixing in the
air, which provides a large volume of air in which to
mix pollutants. Meteorologists call this rate of temper-
ature change the lapse rate. In order to represent the
lapse rate graphically, the meteorologist plots a
temperature profile (Figure 10-10). In such a profile
the temperature is plotted against altitude and
the slope indicated as a solid line called the environ-
mental lapse rate. The dotted line is the "standard"
lapse rate. The "standard" lapse rate represents a
10-12
-------
Figure 10-10
2,000
Ol
-a
-(->
1,000
REPRESENTS "STANDARD" LAPSE RATE
(REFERRED TO AS THE DRY ADIABATIC
LAPSE RATE) - 5.4°F PER 1000 FEET
ALTITUDE.
REPRESENTS AN ENVIRONMENTAL LAPSE
RATE OR ACTUAL CHANGE WITH HEIGHT.
45 46 47 48 49 50 51 52 53 54 55 56 57 58
Temperature in degrees fahrenheit
drop of 5.4 Fahrenheit for each 1000 feet increase in
altitude. When the measured or environmental rate is
the same as this standard decrease in altitude tempera-
ture, the parcels of air at any height in that environ-
ment are in equilibrium, and will not tend to rise or
subside unless some outside force is applied. If you
think of typical weather patterns, you can easily be-
gin to imagine conditions under which there will be un-
stable conditions because of a large difference between
ground level temperature and temperature aloft. In mid-
afternoon on a clear day, the air near the surface
will be very warm because the earth is giving off the
heat it has absorbed from the sun. Thus, there will be
overturning, often called thermal turbulence. A slightly
different condition often occurs when there is a cloud
cover or windy conditions, and the ground does not re-
ceive as much heat, as shown in Figure 10-11. Here,
the air near the ground stays nearly the same tempera-
ture as the air aloft during the day and does not cool
off as much at night. This is called a weak lapse rate.
There is still moderate mixing and dispersion of pollu-
tants, enhanced by the likelihood of high winds.
10-13
-------
1.000
0)
TD
3
500
ENVIRONMENTAL
LAPSE RATE IS
SLIGHTLY STABLE
MODERATE
DISPERSION
43«
5V
Temperature (F)
53°
49"F
COOL AIR
Figure 10-11
Consider Figure 10-12. This shows what happens as the
sun sets on a clear day. The ground will begin to cool
off rapidly, much more rapidly than the air above it.
A layer of cool air will form near the ground. As the
night continues, the cool layer of air will extend fur-
ther into the atmosphere. Pollutants emitted into this
cool air will remain near the surface of the earths since
they are essentially trapped under the warm layer of air
into which they cannot rise. This condition is called
an inversion, since the normal temperature structure is
inverted. When the sun rises again on such a clear day,
the solar radiation will quickly heat the surface of the
earth, warming the layer of air in contact with it. This
10-14
-------
23°
COOLER AIR
20°
\
ENVIRONMENTAL LAPSE
-RATE IS INVERTED IN
COMPARISON WITH THE
NORMAL STRUCTURE -
POOR DISPERSION
28°
WARMER AIR
28°
20°
COOL AIR
\
\
J5°
30°
Temperature (F)
Figure 10-12
warm air will mix with cool air aloft, soon eliminating
the cold inversion layer. Usually within two or three
hours after sunrise, we will have returned to the un-
stable temperature structure as shown in Figure 10-13.
In such unstable atmospheric conditions, good vertical
mixing will occur. This cycle may be altered by stir-
ring of the atmosphere with high winds, or by presence
of clouds or precipitation, which will make both day-
time mixing and nighttime inversions less extreme.
We can watch a plume or stream of smoke emitted from a
large source of pollution and observe its behavior to
determin whether conditions are stable or unstable.
Figure 10-15 illustrates three of these plume types.
When we have very unstable conditions, there is a
great deal of mixing and overturning in the atmosphere.
The plume in this case will take the eaape of the
overturning eddies, and will form what we call a "looping"
10-15
-------
1,000
. \ ENVIRONMENTAL
\ \ LAPSE RATE IS
UNSTABLE
-a
3
\ GOOD DISPERSION
N
COOL AIR
52o
\
32° 35° 60°
Temperature (F)
Figure 10-13
-1,000
•O
500
INVERSION ALOFT
MODERATE DISPERSION
SURFACE INVERSION \
60° 63"
Temperature(F)
Figure 10-14
REPRESENTS "STANDARD" LAPSE RATE ( REFERRED TO AS THE DRY
ADIABATIC LAPSE RATE) - 5.4°F PER 1000 FEET ALTITUDE.
REPRESENTS THE ENVIRONMENTAL LAPSE RATE.
10-16
-------
plume. This will result, as you would expect, in very
rapid mixing and good dispersion, although high ground-
level concentrations will result near the source when a
plume actually reaches the surface. When the atmosphere
becomes more stable, the tendency for overturning de-
creases, and we will see what is known as a coning
plume. Here, the amount of spreading out in the hori-
zontal and vertical directions are about the same, and
dispersion is fairly good. In an inversion situation,
the atmosphere resists vertical mixing, and a plume
emitted into the atmosphere will stay very near the
level at which it is emitted. This is a "fanning"
plume. There are two additional plumes, lofting and
fumigation, which are not discussed here. Please refer
to Table 10-2 for a detailed outline of the conditions
and the associated behaviors of the five plumes. As
depicted in Figure 10-14 an inversion can occur near the
surface or aloft. Emissions from ground-level sources
will stay within the surface inversion layer. (We fre-
quently see this situation in the early morning hours,
when there is heavy traffic and the exhaust fumes are
trapped in a surface inversion).
A high stack is an advantage in an area where there are
frequent surface inversions, since pollutants emitted
above the inversion level will stay at that level, and
ground-level concentrations from that source will gen-
erally be minimal. With a little practice, you can
learn the trick of judging the dispersion capacity of the
atmosphere by watching the behavior of plumes.
Meteorologists use a concept called mixing depth, or
mixing height to quantitatively represent the disper-
sion capacity of the atmosphere. Mixing height simply
refers to the height to which vigorous vertical mixing
takes place. Meteorologists have devised a method of
10-17
-------
UNSTABLE LAPSE
RATE
o-
SLIGHTLY STABLE
LAPSE RATE
VERTICAL MIXING ENHANCED
r;ON! NG PLU ME
MODERATE MIXING
INVERTED LAPSE
RATE
FANNING PLUME
VERTICAL MIXING
SUPPRESSED
Figure 10-15
forecasting the maximum mixing height which can be ex-
pected on a given day, so that they can anticipate
whether or not high concentrations of pollutants are
likely to occur.
Figure 10-16 shows two different mixing heights. If the
same emissions of pollutants were found in both situa-
tions, you would expect a much higher concentration of
pollutants in the second instance, since there is a smaller
volume within which the pollutants can be diluted. There
are significant differences in the seasonal averages for
mixing height at most locations. During the summer day-
light hours, the mixing height may extend up to several
thousand feet. In the winter, when less heat is received
from the sun, the mixing height may be as low as a few
10-18
-------
Table 10-2
PLUME BEHAVIOR AND RELATED WEATHER
LOOPING
Description
Irregular loops and waves with random sinuous movements; dissipates in
patches; relatively rapid with distance.
Temperature Profile-Stability
Adiabatic or4 super-adiabatic lapse rate
— unstable.
Height
Temperature-
Typical Occurrence
During daytime with clear or partly cloudy skies and intense solar heating;
not favored by layer-type cloudiness, snow cover or strong winds.
Associated Wind and Turbulence
Light winds with intense thermal turbulence.
Dispersion and Ground Contact
Disperses rapidly with distance; large probability of high concentrations
sporadically at ground relatively close to stack.
Ground Level Patterns
10-19
-------
Table 10-2 (continued)
CONING
Description
Roughly cone-shaped with horizontal axis; dissipates farther down-wind
than looping plume.
Temperature Profile - Stability
Lapse rate between dry adiabatic and
isothermal-neutral or stable.
Height
\
i • \
Temperature —
Typical Occurrence
During windy conditions, day or night; layer-type cloudiness favored in
day; may also occur briefly in a gust during looping.
Associated Wind and Turbulence
Moderate to strong winds; turbulence largely mechanical rather than thermal
Dispersion and Ground Contact
Disperses less rapidly with distance than looping plume, large probability
of ground contact some distance downwind; concentration less but persisting
longer than that of looping.
Ground Level Patterns
Top view _
of Stack °
10-20
-------
Table 10-2 (continued)
FANNING
Description =
Narrow horizontal fan; little or no vertical spreading; if stack is high,
resembles a meandering river, widening but not thickening as it moves
along; may be seen miles downwind; if effluent is warm, plume rises slowly,
then drifts horizontally.
Temperature Profile - Stabilty
Inverted or isothermal lapse rate - very
stable
Height
Temperature
Typical Occurrence
At night and in early morning, any season; usually associated with inversion
layer(s); favored by light winds, clear skies and snow cover.
Associated Wind and Turbulence
Light winds; very little turbulence.
Dispersion and Ground Contact
Disperses slowly; concentration aloft high at relatively great distance down
wind; small probability of ground contact, though increase in turbulence can
result in ground contact; high ground level concentrations may occur if
stack is short or if plume moves to more irregular terrain.
10-21
-------
Table 10-2 (continued)
LOFTING
Description
Loops or cone with well defined bottom and poorly defined, diffuse top.
Temperature Profile - Stability
Adiabatic lapse rate at stack top and
above; inverted below stack—lower
layer stable, upper layer neutral or
unstable.
Height
Temperature —
Typical Occurrence
During change from lapse to inversion condition; usually near sunset on
fair days; lasts about an hour but may persist through night.
Associated Wind and Turbulence
i Moderate winds and considerable turbulence aloft; very light winds and
little or no turbulence in layer below.
Dispersion and Ground Contact
Probability of ground contact small unless inversion layer is shallow and
stack is short; concentration high with contact, but contact usually pre-
vented by stability of inversion layer; considered best condition for
dispersion since pollutants are dispersed in upper air with small probability
of ground contact.
10-22
-------
Table 10-2 (continued)
FUMIGATION
Description
Fan or cone with well defined top and ragged or diffuse bottom.
Temperature Profile - Stabilty
Adiabatic or super-adiabatic lapse
rate at stack top and below; isothermal
or inverted lapse rate above - lower
layer unstable or neutral, upper layer
stable.
Height
Temperature
Typical Occurrence
During change from inversion to lapse condition; usually nocturnal inversion
is being broken up through warming of ground and surface layers by morning
sun; breakup commonly begins near ground and works upward, less rapidly in
winter than in summer; may also occur with sea breeze in late morning or
early afternoon.
Associated Wind and Turbulence
Winds light to moderate aloft, and light below; thermal turbulence in lower
layer, little turbulence in upper layer.
Dispersion and Ground Contact
Large probability of ground contact in relatively high concentration,
especially after plume has stagnated aloft.
10-23
-------
_ _MI_XING_ HEIGHT
65°F
COOLER AIR
O
o
oo
COOLER AIR
22°F
WARMER AIR
27°F
MAXIMUM MIXING HEIGHT
WARM AIR
75°F.
CLEAR SUMMER DAY
INVERSION CONDITIONS ON
A WINTER DAY
Figure 10-16 Mixing Heights
hundred feet. The mixing height will also vary in the
course of a day. Morning and afternoon mixing heights
are calculated each day for the major weather stations
around the country. The mean, or average, wind speed
through the mixing depth is also calculated (Figure 10-17),
When these two critical meteorological parameters are
considered, we have information about both horizontal
and vertical motion, and we get a very good picture of
the kind of dispersion which will occur.
The map in Figure 10-18 shows the average annual after-
noon mixing heights and the corresponding annual wind
speed averages for some of the major cities in the country.
10-24
-------
MAXIMUM MxNGT
WIND SPEED AT 1000 ft. 11 mph
WIND SPEED AT 500 ft. - 10 mph
AVERAGE WIND SPEED
> THROUGH MAXIMUM
MIXING HEIGHT =
9 mph
SURFACE WIND SPEED - 6 mph
Figure 10-17
You can see that for Phoenix there is an average annual
afternoon mixing height of about 2400 meters, while for
Boston the average is about 1000 meters. The average
wind speed through this mixing depth is about 6 meters/
second, or 13 mph, in Phoenix, while it is 8 meters/
second, or about 18 mph over Boston. You can convert the
rest of these figures to feet of mixing height and wind
speed in mph by using the approximte conversion formulas
and the table given in Figure 10-18. You will find that
in meteorology, as in many of the sciences, both metric
and the more familiar British units of measurements are
used. It will help you to become familiar with both of
these, and to learn a few of the simple rules for
conversion.
10-25
-------
AVERAGE MEAN AFTERNOON MIXING HEIGHTS AND WIND SPEEDS
AVERAGED THROUGH MIXING LAYER FOR SOME MAJOR U.S. CITIES
• Portland
»1200 meters
m. sec-'
Minneapolis •
A 1200 meters
A 8 m. sec-'
• Pittsburgh
A!400 meters
A 7 «i. sec-1
Denver
*2600 meters
m. sec''
St. Louis •
»1400 meters
sec-'
Charleston
A1600 meters
A 6 m. sec''
• Phoenix
A2400 meters
A 6 m. sec-'
Atlanta •
meters
A 6 m. sec'
New Orleans
A! 100 meters
A 6 m. sec"1
Los Angeles
»1000 meters
A5 m. sec-1
Boston
»1000 meters
«B m. sec-1
Mean afternoon mixing height, annual
average to convert: 1 meter =
approximately 3.3 feet
Mean annual wind speed averaged
through the afternoon mixing
layer to convert: 1 m. sec-' =
approximately 2.2 mph
EQUIVALENT UNITS OF MEASURE USED IN METEOROLOGY
LENGTH,
DISTANCE
1 meter
0.305 meter
0.914 meter
39.37 inches
1.094 yards
1 foot
1 yard
VELOCITY
(WIND SPEED)
1 meter per second
(m.sec-1 or m/sec)
= 2.2. miles per hour
(mi. hr-.-l or mi/hr)
TEMPERATURE
0°centigrade = 32° Fahrenheit
( freezing point of water)
100°centigrade - 212° Fahrenheit
(boiling point of water)
to convert C = (5/9)(F-32) F=(9/5) (O32)
PRESSURE
(BAROMETRIC PRESSURE)
1 millibar
1. inch mercury
.0295 inches mercury
33.9 millibar^
1013.25 mb.Hg. = 29.9 in.Hg.
(pressure at sea level)
Figure 10-18
10-26
-------
The information given on the map in Figure 10-18 does not
tell the whole story about dispersion capacity over these
cities, since these are annual averages. However, by
studying data of this sort, about vertical and horizontal
movement and especially by looking at patterns of daily
and seasonal variation and the implications for disper-
sion of pollutants, meteorologists have identified some
areas of the country where we should recommend against
extensive urban development. These areas, where weather
conditions simply do not favor the dispersion of pollu-
tants, include Oregon and central California, the great
basin in the Rocky Mountains, northern Minnesota, and
the area around and including West Virginia.
We have examined in some detail the two meteorological
factors that are of primary concern in air pollution
dispersion. Let us look briefly at a few other factors
that can be important in local or specific situations.
Solar Radiation, Precipitation, and Humidity
10.7. Solar radiation is important in the formation of
photochemical oxidants, since it plays a vital role in the
interaction of nitrogen oxides and hydrocarbons emitted
from automobiles and some industrial plants. Sunshine
becomes a meteorologically important factor, especially
in urban areas on the west coast and in the Rocky Moun-
tain area, where there are a great many days each year
with clear skies. Precipitation and humidity can also
play an important role, affecting both the dispersion and
formation of pollutants. Precipitation acts as a natural
cleansing process, washing particles out of the air.
In this sense, precipitation is advantageous, but when
there is rain, fog. °r high humidity in the air, there is
also the potential for the conversion of some gaseous
pollutants into more potent forms. One prime example
10-27
-------
Topography
is the conversion of sulfur dioxide into sulfuric acid,
which acts to corrode metals and to damage building
materials. The acidity of rain in many urbanized areas
has increased significantly in recent years as a result
of absorption of air pollutants.
10.8. Topography affects the meteorological factors,
and thus, affects the dispersion of pollutants.
Local air pollution problems are often related to the
effect that topography has on the ability of the atmos-
phere to mix pollutants. Figure 10-19 illustrates
some of these problems. Los Angeles and other coastal
areas are plagued by a combination of land and sea breezes
and encircling mountain ranges, together with a low
mixing height and transport wind speed which act to
trap pollutants and cause their accumulation. Emissions
from sources located in mountain valleys or river basins
will be trapped by topographical features, especially
at night or in the early morning. Even minor features
of the landscape, such as hills, small bodies of water,
or a parking lot, can modify the microscale wind flow •:
and turbulence, significantly affecting pollutant dis-
persion. So, we can add topography to our list of fac-
tors affecting the formation and dispersion of pollutants.
Sky Condition
10.9. Sky condition is another reportable meteorological
element that can help make the total visible emission
observation process more complete and credible. Clouds
and obscuring phenomena like haze, smoke, or rain de-
finitely affect the contrast between the plume and back-
ground as does the elevation of the sun and the location
of the observer with respect to the plume.
10-28
-------
A SEA BREEZE WILL PREVAIL ALONG A LAKE OR SEACOAST DURING THE DAY.
A LAND BREEZE IS MORE COMMON AT NIGHT. THIS CYCLE, TOO, CAN CAUSE
POLLUTANT CONCENTRATIONS TO RECUR IN URBAN AREAS
WINDS WILL TEND TO FLOW OUT OF A VALLEY IN THE DAYTIME, AND DOWN
INTO THE VALLEY AT MIGHT, SOMETIMES CAUSING A 'RECYCLING' OF POLLUTANTS
Day Night
UNEVEN TERRAIN WILL CAUSL MECHANICAL TURBULENCE IN THE WIND
MINOR FEATURES, SUCH AS PARKING LOTS, BUILDINGS, OR VEGETATION, CAN
AFFECT DISPERSION Of- POLLUTANTS
^..---. -r~
•*\ .-"*""'* ^"C— ' *""
-\-
.J
Figure 10-19 Topography affects weather circulation and dispersion of
n.j] Tula iits.
10-29
-------
i—^" "'iV ' '4-f?°^ -^^"^'v^i'SLJ
/ _^f * • •"•* J *^'v^***''^ *>?i6 iSS**'
&<^^:^^^«
SURFACE WEATHER MAP
AND STATION WEATHER
AT 1:00 A.M.E.S T
(SURFACE WEATHER MAP
AND STATION WEATHER
AT 1:00 A. M., E. S. T.
Wmd speed '2/1 SPECIMEN J
lo 25 miles per K gT^TinM WnHlTT /I
houri I \
Direction
ifrom the
west I
Temperature in !
degrees Fahrenheit (^,
Total a.-r.ount of j \
clouds tSky com- K N,
pletety covered i I X \
Visibility I */
miles I
Present weather
(Continuous s//g/if
mow jn Hakes }
Oewpomt in de-
grees Fahrenheit
Cloud type (Low
fractostratus and/or
fractocamalus ',
Height of cloud
base 1300 to 599
feet-t
Ooudtype iM/d-
e/y« a/focu/nu/uj )
B*rom«tnc pre»-
IUTC at MO level Ini-
tial 9 01 10 oroittad
(10247 millibar* I
Amount of baro-
metric change in
past 3 hour* I In
tenths of millibars )
Barometric tend-
ency in past 3 hour*
ismo:)
Siqn thowing
whether pressure is
higher or lower than
3 houii ago
Tim* pivcipiUtion
began 01 ended (fie-
gan 3lo4 hours ago \
Weather in put 6
hours • t Rain I
Amount of precipi-
tation in last 6 hour*
Abridged fiom W M O. Code
Figure 10-20.
10-30
-------
The National Weather Service has very explicit rules for
determining sky condition, most of which are too technical
to be discussed in detail here. Usually most air pollution
inspectors are only required to specify the total cloud
cover according to one of four categories, i.e. clear,
scattered, broken, or overcast, depending on the number
of tenths of the entire sky covered by cloud layers.
Inspectors/smoke readers should also be able to determine
total cloud cover at a given station on a national
weather map such as in Figure 10-20.
A complete evaluation of sky condition includes the
type of clouds or obscuring phenomena present, their
stratification, amount, opacity, direction of movement,
height of bases and the effect on vertical visibility
of surface-based obscuring phenomena. Much of this in-
formation can also be gleaned from the plotted station
data in Figure 10-20. However, this detail is not re-
quired on smoke reading forms.
A few definitions are in order, taken from the GPO Pub-
lications: "Manual of Surface Observations (WBAN),"
Circular N, 7th Ed. (Rev.) 1966 with changes to May
1969 (now out of print) and; Federal Meteorological
Handbook No. 1, "Surface Observations," April, 1970.
1. Sky Cover. A term used to denote the amount
(to the nearest tenth) of the sky which is:
(a) Covered but not necessarily hidden
by clouds and/or obscuring phenomena
aloft
(b) Hidden by surface-bases obscuring
phenomena,
or
(c) Covered or hidden by a combination of
a or b.
10-31
-------
2. Total Amount of Sky Cover. The amount of tenths
of the entire sky that is covered, but not neces-
sarily hidden, by all layers present. This amount
cannot be greater than 1.0 (10/10).
3. Horizon. The actual lower boundary (local horizon)
of the observed sky or the upper outline of terres-
trial objects including nearby natural obstructions.
It is the distant line along which the earth, or the
water surface at sea, and the sky appear to meet.
The local horizon is based on the best practical
point of observation near the earth's surface and
selected to minimize obstruction by nearby buildings,
towers, etc.
4. Transparent Sky Cover. Those portions of cloud
layers or obscurations which do not hide the sky.
Blue sky or higher clouds can be discerned through
these portions during daylight, and the moon and
brighter stars may be discerned at night.
5. Opaque Sky Cover. Those portions of cloud layers
or obscurations which hide the sky and/or higher
clouds. Translucent sky cover that hides the sun
and moon (not stars) may be dimly visible will be
considered as opaque.
6. Sky Cover Amounts. Sky cover amounts are evaluated:
(a) In terms of the entire sky area above the local
(apparent), rather than celestial horizon.
(b) In tenths of the sky covered for aviation ob-
servations and national weather map plotting.
(c) In terms of the amount of sky covered or hidden.
(d) With reference to an observer on the earth's
surface.
The sky cover symbols, together with their meaning,
teletype contraction, and brief explanation are given
in Table 10-3, from "Circular N", referred to above.
To assist you in determining total sky cover from sur-
face weather maps, remember the basic plotting model where:
10-32
-------
dd = wind direction
ff = wind speed
TT = surface temperature
T T, = dew point temperature
VV = surface visibility
ww = present weather
N = sky coverage (total amount)
Table 10-3 sky Cover Symbols
Symbol
Meaning &
Contraction
Explanation1
o
0
-X
-©
_;®_j
Clear CLR
0.0 total sky cover. (This symbol is used
alone - not in combination with others.)
Scattered Layer
Aloft SCTD
0.1 to 0.5 sky cover at and below level of
layer aloft and not classified as "thin".
Broken Layer
Aloft BRKN
0.6 to 0.9 sky cover at and below level of
layer aloft and not classified as "thin".
Overcast Layer
Aloft OVC
. _
1.0 (ten tenths) sky cover at and below level
of layer aloft and not classified as "thin".
Obscuration
(Surface Layer)
All of sky is hidden by a surface-based layer,
i.e., vertical visibility is restricted by the
layer.
Partial
Obscuration
(Surface Layer)
THIN
THIM
BRKN
THIN
OVC
C.I or more, but not all of sky is hidden by
surface-based layer, I.e., vertical visibility
through the layer is not completely restricted.
Transparent sky cover comprises 1/2 or more
of the total sky cover. Ref. definition of
sky
10-33
-------
N
O
(D
O
(B
3
^
J
O
•
<8>
SKY COVERAGE (Total Amount)
No clouds
Less than one-tenth or
one-tenth
Two-tenths or three-tenths
Four-tenths
Five-tenths
Six-tenths
Seven-tenths or eight- tenths
Nine-tenths or overcast
with openings
Completely overcast
Sky obscured
The map plotting symbols for N,
total amount of sky coverage, are shown
in Figure 21 and can easily be converted
to the terms clear, scattered, broken,
and overcast as previously defined.
Observer skill in determining sky
condition can and must be developed with
practice and inspectors/smoke readers
should make it a habit to evaluate sky
cover and effects of obscuring phenomena
whenever they are outdoors. For example,
if the circle represents the horizon in
the figure below, what is your initial
estimate of the sky cover?
The correct answer is 5/10 or scattered
cloud cover. Remember, 6/10 of the sky,
rounded to the nearest tenth, must be
covered with clouds to be termed broken.
Figure 10-21
(a) Determine amounts to the nearest tenth,
i.e., if amount present is judged to be
zero rather than one tenth, it will be
reported as clear ( J .
(b) The symbol fM is used in combina-
tion with other lower overcast symbols
10-34
-------
in Col. 3 only when such lower over-
case layers are classified as thin,
i.e., reported as — f\ J .
(c) Note that when more than 9/10 of the
sky, but not all of the sky, is hidden
by obscuring phenomena, and:
(1) When the sky overhead is obscured,
report the condition as an obscura-
tion "X".
(2) When it is not so obscured, e.g., a
homogeneous layer, report the condi-
tion as partial obscuration, "—X".
(3) Report the direction of discontinui-
ties or breaks, as remarks, e.g., THIN
FOG NW, or BREAK IN F TO NW.
10-35
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CHAPTER XI.
LEGAL ASPECTS OF
VISIBLE EMISSIONS
History and Test Cases
11.1. Law may be divided into two categories - common
law and statute law.
11.2. Early air pollution laws fell under the category
of prohibiting smoke as a common nuisance or a public
nuisance. Under these common law nuisance regulations
it had to be proven in each individual case that the
smoke was injurious or offensive to the senses. .In the
case of a public nuisance, it had to be proven that a
large number of persons were affected.
11.3. In modern times, smoke and air pollution came to
be regarded as an absolute nuisance (a nuisance per se)
and a state could pass a statute that declared the emission
of dense black smoke to be illegal. Injury did not have
to be proven in each case.
11.4. The State may grant to a city, county, or other
local government the power to pass ordinances regulating
air pollution. The State can later cancel the powers
which they granted earlier. The Federal government can
also regulate air pollution in certain instances.
11.5. This power to regulate air pollution is given
to the States by the Tenth Amendment of the Constitution,
which states: "The powers not delegated to the United
States by the Constitution nor prohibited by it to the
States are reserved to the States respectively, or to
the people."
11-1
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11.6. The only constitutional limitation to how far the
State's air pollution control law can go is in the Four-.
teenth Amendment to the Constitution: "...nor shall any
State deprive any person of life, liberty or property,
without due process of law, nor deny to any person with-
in its jurisdiction the equal protection of the laws."
Most of the air pollution cases that are appealed test
the constitutionality of the control ordinance by means
of the "due process" clause or the "equal protection"
clause.
11.7. Once black smoke had been declared illegal, laws
were needed to limit the emission by setting maximum
permissible pollution standards, or regulating the use
and operation of equipment and fuels. ./
11.8. Examples of maximum permissible emission standards
are the Ringelmann Standard and the Equivalent Opacity
Standard.
11.9.. In 1910 the Ringelmann Chart was first recognized
legally in the United States b.y its inclusion in a smoke
ordinance for Boston passed by the Massachusetts
Legislature.
11.10. The constitutionality of the Los Angeles County
rule that provides standards for reading of densities
and opacities of visible emission (L.A. County Rule 50 or
Section 24242 of the California Health, and Safety Code)_
has been tested twice, in 1951 and in 1955. In both of
these cases its constitutionality was upheld b.y the Los
Angeles Superior Court. In 1955 an appeal of the
•Superior Court's decision to the United States Supreme
Court was dismissed by the Supreme Court.
11.11. When first adopted, Section 24242 stated: "A
person shall not discharge into the atmosphere from any
single source of emission whatsoever any air contaminant
11-2
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for a period or periods aggregating more than three
minutes in any one hour which is
(a) As dark or darker in shade as that desig-
nated as No. 2 on the Ringelmann Chart as
published by the United States Bureau of
Mines, or
(b) Of such opacity as to obscure an observer's
view to a degree equal to or greater than
does smoke described in subsection (a)_ of this
section."
11.12. The 1951 case, People Versus International
Steel Corporation, dealt with subsection (a) of Rule 50.
The 19-51 Supreme Court dismissal directly concerned sec-
tion (b.)_ and involved four separate cases of smog
(1)_ People Versus Plywood Manufacturers of
California
(2), People Versus Shell Oil Company
(.3) People Versus Union Oil Company
(4)_ People Versus Southern California Edison
Company
Other cases approving the use of the Ringelmann Chart
include: Board of Health of Weehawken Township Versus
New York Central Railroad (New Jersey, 1950).., and
Penn-Dixie Cement Corp. Versus City of Kingsport
(Tennessee, 19.49.)..
1.1.13. The California appeal cases established
(a). That the Code is constitutional.
(b)_ That it is permissible for a
statute to adopt, for a description
of a prohibited act,- a publication
of the United States Bureau of Mines.
(c). That inspectors trained in the use.
of the Ringelmann Chart are experts.
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They may testify as expert witnesses con-
cerning the Ringelmann Number of a particular
smoke emission without having had a chart
in their possession while observing the plumes.
(d) That the fact that the ordinary person is un-
certain whether a smoke plume is as dark as
Ringelmann No. 2 or whether its opacity equals
that of smoke matching Ringelmann No. 2 is
no reason for the unconstitutionality of the
Rule.
(e) That the drawing of a line between permission
and prohibition (Ringelmann No. 2) is a
matter of legislative discretion that will
not be reversed by the Courts unless abused.
Of).. That if the plume, fairly viewed from any
position, exceeds the regulation of Ringelmann
shade, the smoke is in violation no matter how
light the color may look to someone situated at
another vantage point.
Equivalent Opacity and Smoke Emissions Law
11.14. Some requirements for a good air pollution law
are:
(a). It must have the power to reduce
contaminat ion.
(bX It must be enforceable. It must
be capable of being enforced uni-
formly and it should not be expen-
sive to enforce.
(c) It must be reasonable.
(d). It must be clear and precise
so that people can understand
it and avoid breaking it.
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(e) It is not necessary to prove that
the owner of the stack had criminal
intent in violating the ordinance,
just the fact that his smoke is
blacker than the allowed Ringelmann
No. is sufficient.
(f). Any classification of sources it
establishes must be reasonable.
For example, an industry operates
its stack for profit while a home-
owner does not; therefore, different
emission standards can be required
of industrial and domestic chimneys.
11.15. As a practical matter, judges will weigh the
equities in a case to determine which of the two
parties will sustain the most injury. They would not
put a large company out of business, but could require
them to pay a fine or install a control device.
11.16. Smoke emissions and equivalent opacity regu-
lations may restrict the shade of smoke to be no
darker than a specified Ringelmann Number or a particu-
lar percent opacity, depending upon the source and the
conditions.
11.17. The different sources regulated may be listed
as fuel burning equipment, internal combustion engines,
open fires, incinerators, railroad locomotives, and
steamships. The restricted sources may also be described
as stacks or vents or as any single source of emissions
whatsoever.
11.18. Different restrictions may apply to incinerators
and domestic installations.
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11.19. Limitations may be set allowing smoke of a
darker shade for several minutes of every hour during
periods when a new fire is being built.
11.20. Exceptions may be granted for fires used in
training firemen or on farms. There may also be
exceptions for industrial accidents which, cause black
smoke or for special processes.
11.21. Codes may exclude plumes of uncomhined water from
the restrictions.
Local Regulations
11.22. The air pollution inspector must know and
understand the visible emissions regulations that he
will be enforcing.
How To Be An Expert Witness-
(.1) Under ordinary circumstances the average
citizen cannot testify as to his opinions or
conclusions, but the expert witness can. The
opinion of the expert witness helps the judge
make his decision.
(.2), It is preferable to subpoena a
witness, even a smoke inspector, to
appear in court rather than to have
him appear voluntarily. When the
witness is subpoenaed, it demonstrates
that he is not appearing in court just
because he has a prejudiced opinion for or
against one of the parties in the case.
(3), Before appearing in court, prepare your
materials and refresh, your memory. An attorney
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spends 2 to 10 hours in preparation for
every hour in court. An expert witness
should spend a comparable amount of time in
reviewing his observations before he testifies.
(4) As an expert witness the air pollution officer
should not have to read his testimony. How-
ever he has a right to refer to his records
and notes to refresh his memory.
(5). Since the case may not appear in court until
months after the violation occurred, the
officer should complete his report fully
at the time of violation.
(.6) If you take a picture of a plume, you
should know what operation or process is
going on in the plant at the time of the
picture. Record the time, weather, film type,
exposure setting, lens type, and distance from
the plume.
(.7). Before having any telephone conversations
with a plant operator, it is desirable to meet
the man so that you can later identify hi's
voice on the phone.
(8). Investigate every case thoroughly. Do not
become overconfident after you have appeared
in court several times.
(_9-X Behavior on the witness stand:
(aX Dress and act like an expert.
(bX Be responsive to the question that is
asked you. Do not volunteer information
about some unrelated topic or question.
(c) Take a second to frame your answer before
giving it.
(d). If you hear "objection," quit talking.
11-7
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(e) If you make a mistake, admit it.
(f) If you cannot answer just "yes" or "no"
to a question, say so.
(g) Keep calm. Don't lose your temper.
(h) Don't try to second guess your attorney.
(10) You will be directly examined by your attorney
and cross-examined by the opposing attorney.
There can then be a redirect examination and
a recross examination. You can also be recalled
at a later time to clear up your testimony.
Suggested Additional Reading
Field Operations and Enforcement Manual for Air
Pollution Control APTD-1100, U. S. Environmental
Protection Agency, Research Triangle Park, NC 27711
1972, available from National Technical Information
Service, Springfield, VA 22151.
Environment Reporter, The Bureau of National Affairs,
Inc., Washington, D.C.
11-8
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CHAPTER XII,
OBSERVATION REPORTS FOR VIOLATIONS
12.1. The purpose of making a visual observation of the
degree of blackness or whiteness of a plume is to deter-
mine if the source is in compliance with regulations.
12.2. To provide a sufficient basis for court prose-
cution, the inspector must gather evidence essential for
a prima facie case — that is, a case which unless
contradicted adds up to a violation of the law.
12.3. Each and all of the elements of the violation
must be proven or else there is no case to take to
court. For instance, if the regulations states:
"A person, owner, agent, operator, firm or
corporation shall not discharge into the atmos-
phere from any single source of emission whatsoever
any air contaminant for a period or periods aggre-
gating more than three minutes in any one hour which
is as dark or darker in shade than that designated
as No. 2 on the Ringelmann Chart..."
Then all of the following must be proven:
(a) A person, owner, agent, operator, firm
or corporation
(b) Discharged
(c). Into the atmosphere
(d) From a single source
(e) A contaminant
(f) Of greater than No. 2 Ringelmann
(g). For more than 3 minutes in 1 hour.
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12.4. The report and the citation forms when filled
out completely assure the inspector that he has
collected the data essential for supporting a prose-
cution of a violation.
12.5. The written report is not in itself the evidence
that is used to prove a case in court. Rather, the
evidence compiled by an inspector consists of his
expert opinion concerning the shade of the emissions
he observed and his testimonial evidence given when
he testifies to the facts surrounding his observations.
12.6. The written report may not actually appear in the
court proceedings, but the inspector may use it to re-
fresh, his memory.
12.7. The facts that the inspector should record in his
report of the observation include:
(a). The nature and extent of the violation;
(b)_ The time and location of the violation;
(c). The person(s), responsible for the violation;
(d). The equipment involved with the violation;
(e)_ The operational or maintenance factors
which caused the violation.
12.8. This information can be filed in two reports-a
smoke observation report and a plant operation report.
The latter would cover information identifying and
describing the equipment that generated the plume and
determining the factor(s)_ that caused the violation.
12.9.. Either of the two reports might contain
information concerning the names and addresses of the
owners of the company and of the operators of the
equipment as well as any remarks these people may have
regarding the equipment.
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12.10. The smoke observation portion of the report
form should include spaces for the following supplementary
information:
(a). Direction or distance of the observer
from the source;
(b) Direction from which the wind was blowing
and, possibly, the wind speed;
(c) Weather conditions during the observation
describing whether the sky was clear, over-
cast, scattered, or broken, and whether it
was hazy or raining;
(d) Date and time during which the observation
was made;
(e) Name and address of the firm where the
observation was made;
(_f). Type of air contaminant;
(g)_ Description of the source, such as number
of stacks and their height;
(h)_ Signature of the inspector.
12.11. The basic portion of the smoke observation
report should record the visible emissions observed,
showing the continuous time intervals for each density
and opacity and color changes. The inspector should
note to the -nearest quarter minute the beginning and
ending observation times for each change of density
of color.
12.12. The total violation time for each hour of
observation should be recorded as well as the total
violation time during the entire period of observation.
12.13. A photograph of the source can be taken before
or after, but not during the observation. Photographs
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do not always give a true reproduction of plume color.
12.14. Since the accuracy of reading visible emissions
is within 7.5% opacity, it is suggested that a viola-
tion notice not be issued to the owner of the equipment
unless it is in violation for 1 minute longer than the
legal limit and for 1/2 Ringelmann or 10 percent opacity
greater than the legal limit.
Special Designations
12.15. In some state, county, and municipal visible
emissions regulations, special source categories or
specific sources are named. Some of these include
(a). Fuel-burning equipment
(b)_ Combustion equipment
(c) Apartment houses
(d> Office buildings
(e) Schools
CfX Hotels
Cg)_ Hospitals
(h).. Process equipment
CiX Motor vehicles
(jX Internal combustion engines
(k)_ Diesel motor vehicles
(IX Railroads
(m). Steamships
(nX Incinerators
GoX Open fires
12.16. Emissions from incinerators are often required
not to exceed a Ringelmann No. 1 or an equivalent opacity
of 20 percent although the limit for other sources may
be No. 2 Ringelmann. Some state implementation plans
have reduced opacity standards to 20% or less.
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12.17. Some ordinances and regulations grant exceptions
to the visible emissions regulations. A few of these are:
(a) Smoke may attain densities as high
as No. 3 for an aggregate of 3 minutes
in any 15 consecutive minutes when a
new fire is being built, a fire box is
being cleaned, tubes are being blown,
or an equipment breakdown occurs.
(Regulations may vary on the time allowed.
Other codes include 3 minutes in a
30-minute period, 12 minutes in a 24-
hour period, etc.)
(b). Smoke from railroad locomotives or steamships
may attain values as high as No. 3 Ringelmann
for a limited number of minutes during
periods ranging from 6 minutes to 8 hours.
(,c)_ In some localities, exceptions to visible
emission regulations may be granted to
certain industrial operations. Some ex-
amples from one State's code are
(!)„ Transfer of molten metals;
(,2X Emissions from transfer ladles;
(3). Coke ovens when pushing coke.
after discharge from the ovens;
(4). Water quenching of coke after
discharge from the ovens;
(5). Gray iron cupola furnaces.
Suggested Additional Reading
"Guidelines for Evaluation of Visible Emissions" - EPA-
340/1-75-00.7, April 1975, National Technical Information
Service, Springfield, VA 2216d
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CHAPTER XIII.
EMISSION GENERATOR
13.1. For use in training personnel to read smoke,
it is necessary to have a device that will produce
both black smoke and white smoke plus an instrument
to measure the opaqueness of the smoke that is produced.
13.2. Smoke-generating devices have been built by some
air-pollution control agencies for their use. The
principles of operation of all these units are similar.
Other agencies have purchased manufactured generators.
Mark II Smoke Generator
Black Smoke
13.3. The Mark I.I Smoke Observers Training Unit,
manufactured by Environmental Specialties, is the
most widely used smoke generating unit. It is portable
and each unit is custom made; however, the principal
features of the Mark II are present in all models.
13.4. When a carbon-containing fuel is burned with
insufficient air, a smoky flue gas is produced. The
smoke consists of partially burned carbon particulates
suspended in the gas.
13.5. In the smoke generator, black smoke is created
by burning toluene with a deficiency of oxygen. (Diesel
fuel is used by some generator operators.) This fuel
is burned in a furnace that consists of a 12-cubic-foot
steel combustion chamber lined with refractory bricks.
The combustion air entering this chamber is limited.
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White Smoke
Transmissometer
The toluene flow into the furnace is controlled by a
fine metering valve. The density of the black smoke
is varied by using this valve to adjust the rate of
fuel injection through a nozzle into the combustion
chamber. Note: Toluene has replaced benzene. Benzene
has been placed on the toxic substance list.
13.6. To produce the white smoke, No. 2 fuel oil (the
grade usually used for home or commercial heating).
is vaporized. This vapor is then condensed into an
aerosol cloud of a white color. The opacity of this
cloud is controlled by adjusting the flow of the No. 2
fuel oil.
13.7. In the Mark II, the white aerosol vapor is
created by injecting the fuel oil through a hypodermic
needle into the manifold carrying the hot exhaust
from a small lawnmower-sized gasoline engine. This
engine runs a generator that can provide electric power
for the Mark II unit. Considerable heat is required for
vaporizing the fuel oil. Sufficient heat is provided
by operating the generator under an appreciable load.
13.8. In the production of both black and white smoke.,
the smoke is diluted with ambient air before it enters
the stack. The degree of dilution is controlled by
dampers in the air inlet to the induced draft blower fan.
13.9. The opaqueness of the white or black smoke is
measured by a transmissometer located in a 4-foot length
of pipe mounted perpendicular to the smoke stack, at a
point 6 feet below the top of the stack. The opaqueness
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measurement from the transmissometer can be read by
the generator operator on a scale divided into Ringelmann
Numbers and equivalent opacity percentages. The trans-
missometer reading serves as the standard with which the
smoke reader compares his visual observations.
13.10. The transmissometer for the Mark II is a
simple light source and photocell combination. The
light source may be a flashlight bulb or automobile
taillight bulb mounted in a silvered reflector that
concentrates the light into a beam that is aimed at
the photocell 4 feet away. The photocell has a special
sensitivity closely approximating the standard spectral-
luminosity curve for photopic vision.
13.11. One foot of the path length of the beam is
through the stack of the generator. In this portion of
the path the intensity of the light is reduced in
proportion to the amount of smoke being produced by
the generator. This smoke is prevented from entering
the remaining 3 feet of the transmissometer path by
circular smoke stops that reduce the diameter of the
transmissometer pipe. In addition, these 3 feet of the
transmissometer path are continually flushed with outside
air by two fans, one mounted at each end of the pipe.
13.12. The combination of smoke stops and ambient air
flushing ensures that there will be no smoke buildup in
the pipe. As a result, the only obstruction to the light
beam occurs when the beam passes through the 1-foot-
diameter stack.
13.13. The percent transmission of light that reaches
the photocell is relayed electrically to the operator's
station. Here, it may be read from the dial of a micro-
ammeter or from a pen trace on a recorder depending
upon which of these devices is supplied with the. generator
unit.
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13.14. The transmissometer system is calibrated from
100 percent to zero transmission (zero to #5 Ringelmann
and zero to 100 percent equivalent opacity) by inserting
several grades of neutral density filters into the light
path between the bulb and the photocell and adjusting the
microammeter or recorder for the percent of light
transmitted.
Conduct of the School
13.15. The smoke reader's training on the smoke genera-
tor begins with a familiarization series of black and
white smoke densities. Upon the sound of the horn,
the instructor calls out the meter or recorder reading of
Ringelmann Number or equivalent opacity.
13.16. After this familiarization period the students
go through a practice run of 25 shades of black and 25
shades of white smoke. Each reading is made by the
student at the sound of the horn and entered on his
training form just as he will do it later when he is
reading for qualification.
13.17. Following the practice run the students will
begin their qualification runs of 25 white and 25 black
shades.
13.18. In between qualification runs the generator
operator may conduct short series of familiarization
review runs for the benefit of the students.
Other Smoke Generating Equipment
13.19. Los Angeles - 19.62
(a) Black Smoke System
The oil burner is a modified mechanical
pressure atomizing type. The. combustion
13-4
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chamber is a 40-cubic-foot-rectangular steel
box lined with 6 inches of refractory fire
clay. The various degrees of incomplete com-
bustion of the fuel are obtained by adjusting
the fuel flow. The smoke from the combustion
chamber passes along a horizontal duct into a
cooling chamber and then into the stack. A
forced-draft fan discharges ambient dilution
air into the base of the stack and pushes the
smoke up the stack. This forced draft helps
to prevent distortion of the plume by the
wind as the smoke exits from the stack. The
cooling chamber prevents secondary combustion
from occuring at the base of the stack as the
combustion products are diluted with air.
(b). White Smoke System
The "white smoke" is created by spraying
a distillate type of oil into a chamber
where it is vaporized by the heat generated
in an adjacent heating chamber. The vapor
is forced up the stack by a forced draft
fan that pumps in dilution air. The vapor
is condensed into a white cloud of aerosols.
The operator controls the opacity of the
plume by adjusting the rate at which the
oil is sprayed into the vaporizing chamber
and the temperature of the heating chamber.
The heat in this chamber is created by burn-
ing distillate oil.
(c)_ Opacity and Density Detection System
Similar to the Mark II, this system consists
of a light source and a photoelectric cell
positioned at opposite ends of a light tube
13-5
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protruding horizontally from each side of
the smoke stack. The milliammeter, which
registers the light received by the photo-
cell, has a scale arranged so that 100
indicates no light and zero indicates free
passage of light. When the operator adjusts
the output of the light source to cause a
full-scale deflection of the milliammeter,
an opacity of zero is read. If the light is
turned out, no light energy reaches the cell
and the milliammeter reads 100 percent opacity.
Suggested Additional Reading
Guidelines for Development of A Quality Assurance
Program; Volume IX - Visual Determination of Opacity
Emissions from Stationary Sources. EPA Publication
EPA-650/4-74-005-1, U.S. Environmental Protection Agency,
Research Triangle Park, NC November, 19.75.
Field Operations and Enforcement Manual for Air
Pollution Control. Volume I; Organization and Basic
Procedures, EPA Publication APTD-1100, U S Environmental
Protection Agency, Research Triangle Park, NC, August .19.72.
13-6
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CHAPTER XIV.
OPACITY PROBLEMS CAUSED BY
WATER VAPOR
14.1. Introduction. The ease of monitoring a control
area by visual observation has led to the enactment of
regulations prohibiting plumes which obscure more than
a certain percentage (frequently 40 percent) of an
observer's view when he looks through the plume. One
of the problems confronting control officials - using
regulations which depend upon the visual determination
of equivalent opacity - is that of evaluating plumes
containing large quantities of water vapor. This water1
vapor, when it condenses and becomes visible, may make
the plume 100 percent opaque even though the quantity of
other particulate material is small enough so that the
plume, if dry, would not be in violation of the opacity
standard.
14.2 Is Water Vapor a Pollutant? The question arises
as to whether equivalent opacity regulations should
distinguish between those plumes that contain water
vapor and those that do not. Water alone is not
injurious to health, and is normally present in any
atmosphere, either in the invisible vapor state or
in a visible liquid state in the form of fog or clouds.
There are objections to water vapor emissions. Under
certain topographical and meteorological conditions, the
artifically created water vapor is a contributing
factor to a higher frequency of ground fogs. These
can be dangerous if they form in the vicinity of a
highway or air field, because they decrease the
visibility. Industrial accidents, also resulting from
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the decreased visibility, may occur within the area of
the emitting factory. In freezing weather, there is a
possibility of increased ice formation because of the
presence of higher atmospheric relative humidity.. Even
though the emission may be a pure water vapor, there is
the possibility that a combination of the vapor and
other substances in the air will create a harmful pol-
lutant. This may occur in the vicinity of large power
plants; when water vapor emitted from cooling towers in
large quantities and sulfur oxides emitted from coal
burning equipment combine in the air to form sulfuric
acid mist, the damage to vegetation and materials may he.
far greater than would be expected if there was no
water vapor emission.
Finally, there may be an objection ha.sed on aesthetic
grounds, to dense plumes regardless of their composi-
tion. The average citizen cannot distinguish between
a white plume, which is primarily water vapor and
one of the same color containing only a small per-
centage of water.
14.3. Regulations Governing Wet Plumes. While
ordinances in some air pollution codes make no distinc-
tion between the visible evaluation of water vapor and
non-water plumes, other air pollution regulations do
make provisions allowing for the emission of "uncombined
water." Questions can arise about the interpretation
of this term as to whether it means "chemically" un-
combined. Even though the intent of the regulation may
be to allow for only pure steam plumes, one may argue
that no water vapor, either naturally or artificially
produced, can condense unless it contains some particle
as a nucleus for the water drop.
One method of "reading" wet plumes is to instruct the
14-2
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plume inspector to observe these plumes at the point
where the condensed water vapor portion of the plume has
evaporated. This prevents the citation of a plume
containing a dry opacity below the legal limit, but
which because of the accompanying water, exceeds the
opacity limit. This method, however, may protect a
polluter because the dry opacity of his plume may
exceed the legal limit near the stack. But at the
point where the water evaporates, the plume has dis-
persed enough so that its opacity becomes legally
acceptable.
Visible Identification of Water Vapor Plumes
14.4 Atmospheric Effects on Water Taper, Water in the
gaseous state (as water vapor) is invisible and is
always present in the atmosphere. One of the measures
of the volume of water vapor contained in the atmosphere
is relative humidity; the more water vapor contained
in a given amount of air, the higher the relative
humidity content. When the air is "saturated"
with water vapor, the relative humidity present is
100 percent. Any additional water vapor must condense
out into the liquid state and will become visible in
the plume.
The amount of the water vapor held in the air varies
with the temperature of the air. Warm air can hold
more water vapor than cold air. Consequently, air
that is not saturated with water vapor may be cooled
until it becomes saturated and the relative humidity
then reaches .100 percent. If this cooling is done at
constant pressure, the temperature at which saturation
occurs is called the dew point. If the air is cooled
below its dew point, it will be supersaturated and the
excess water vapor condenses out into the liquid form
of a cloud.
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When wet plumes are initially created in a process, the
gas temperature may be hot enough so that the water is
invisible and is in the vapor form. If the plume is
cooled sufficiently, either in the stack or in the atmos-
phere, then the plume becomes saturated with water vapor
and condensation takes place. As the plume is mixed
with the surrounding air, some of the moisture in the
plume is transferred to the ambient air. This increases
the relative humidity of the ambient air and decreases
the relative humidity of the plume. When the relative
humidity of the plume reaches 100 percent, the visible
water begins to change by evaporation to an invisible
vapor. In time the water plume completely disappears.
Under varying atmospheric temperatures or humidity
conditions, two plumes that are emitted from a given
process under identical conditions may form and then
dissipate at different distances from the stack. In
cold weather a plume may condense, and become visible,
as soon as it leaves the stack. In hot weather not as
much atmospheric cooling occurs and condensation may
not take place until the effluent has moved some
distance from the stack. This latter condition results
in a detached plume.
Once formed, the plume disappears more quickly into
the warmer air, which can hold additional water vapor
without becoming saturated. For example, on two
days with identical temperatures, the plume will persist
for a longer distance on the day with a higher relative
humidity, because the ambient air can hold less water
vapor and cannot absorb additional moisture from the
plume. Some materials, such as sulfur trioxide (S0_),
are hygroscopic and tend to attract the water vapor
in the air. These plumes can remain visible to the
observer for longer distances.
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Identifying Visible Plumes. A pure water vapor
plume disappears without a trace of dust. It evaporates
quickly, mixes in all directions, and is characterized
by its "wispiness."
When plumes are observed under varying atmospheric
conditions, those containing large amounts of water
vapor may be distinguished by their reactions. The
wet plume may be detached from the stack in warmer
weather, and it will persist for longer distances
during periods of high relative humidity.
Plumes containing large amounts of sulfur trioxide
will become visible as detached plumes when the
relative humidity of the ambient air is high because
the SCL is hygroscopic. For the same reason, they
will also persist for longer distances than the pure
water vapor plumes.
Typical Operations Which Discharge Water Vapor
14.5. Typical Operations Which Discharge Water Vapor.
• Drying operations:
(1), Type of Equipment
(a). Rotary dryers
(b)_ Spray dryers
(c) Drum dryers
(d) Tray and tunnel dryers
(2) Type of Industry
(a) Powdered milk
(b) Chemicals
(c) Pharmaceuticals
(d). Instant coffee
(e) Detergents
(f) Ores
(g) Paper
14-5
-------
• Combustion operations in which fuels containing
hydrogen and hydrocarbons are used
• Air pollution control operations which use
water scrubbing to remove solids or pollutant
gases:
(1) Typical Equipment
(a). Venturi scrubbers
(b)_. Packed towers
(c). Spray towers
• Cooling operations in which the heat is removed
by water evaporation
Methods of Eliminating Visible Wet Plumes
14.6. Methods Eliminating Visible Wet Plumes.
Several methods are available to eliminate condensation
of the stream plume from a stack:
(1) Dilution of the Plume with Heated Air.
Hot air can be mixed with the moist effluent
to reduce the dew point and thus prevent the
effluent from becoming super-saturated as
it enters into the colder air. (An example
of this method will be given later.),
(2X Superheating the Plume.
The plume is heated (before emission) to a
temperature high enough to disperse the
effluent in the atmosphere, before it has
cooled to the dew point.
(3). Direct-Contact Condensation with Water.
The effluent can be cooled to its dew point
by bringing the plume into direct contact
14-6
-------
with cold water. There are several ways
to accomplish this direct-contact cooling:
(a) Surface water
(b) Cooling tower
(c) Air-fin cooler
(.4) Indirect-Contact Condensation with a
Surface Condenser
If contamination of the cooling water with
the effluent is a problem, then the plume can
be cooled by passing it through a tubular
surface condenser containing circulating water.
The three methods listed in A-3 above, can
also be applied to indirect cooling.
(5) Combination Processes.
When the outdoor temperature is low, the
problem of preventing condensation of the
plume becomes more difficult because the
air contains less water vapor before it
becomes saturated. Under these conditions
a combination of methods must be used, e.g.,
removing some of the moisture by condensation
and then reheating the plume before dis-
charging it.
Problems.that may be encountered include:
(1) Additional pollutants and excess energy use
occurs when the plume is superheated or
diluted with heated air.
(2) When the water vapor in the plume is prevented
from condensing in the atmosphere (by use of
the direct-contact condenser cooling method)
certain requirements must be considered:
14-7
-------
(a) A large quantity of cooling
water must be available.
(b) The cooling water will pick up
and convert some of the air
contaminants into water pollutants.
(c) The cooling water will absorb some
of the heat from the plume. If
the volume of heat is large enough,
thermal pollution may become a
problem.
(3). When the water vapor contained in a plume is
condensed by direct or indirect contact
condensation with water there will still be
a discharge of water vapor into the atmos-
phere . The condensate will be transferred
from the stack, to a cooling tower or the
surface of a river or lake, where it may be-
come less objectionable to the community.
(.4) The most economical method, on an annual
operating cost basis, is direct condensation
with natural surface water; however, natural
water is not always available. The only
method that minimizes air, water, and thermal
pollution (condensation with a surface
condenser using an air-fin cooler) is the
second most expensive one. In tall stacks,
such as found in power plants, it is nec-
essary to heat the effluent gases (when
scrubbers are used) to obtain adequate
bouancy of the gases in the stack.
9
Reading Water Vapor Plumes
14.7. If the condensed water vapor plume is detached,
opacity determinations can be made immediately at
14-8
-------
the stack exit, i.e., before the water vapor begins
to condense.
If the water vapor plume is attached to the stack,
readings should be made at the point where the water
droplets have revaporized completely. This point may
be some distance downwind thus allowing the pollutants
to become diluted by mixing with the ambient air.
The further downwind this point is, the more dilute
will be the pollutants and the lower the opacity read-
ings will become, which of course, tends to act in
favor of the source.
If the inspector has any question about the quantity
of pollutants being emitted by a source and is unable
to take a reading close to the stack because of the
condensed water vapor plume, a source test should be
ordered.
The best way of handling the problem is to make
the visit to the plant when there is a good possibility
that the condensed water vapor plume will not be present.
Using a psychrometric chart, according to the procedures
of Section 14.9. in conjunction with estimates of
meteorological and effluent conditions, and a few
minutes of computation, the inspector may determine
whether or not there is a good possibility that the
water vapor in the plume will condense. This procedure
could save the inspector a wasted trip to the plant in
question. An example of the use of the psychrometric
chart is given below.
Description of the Psychrometric Chart
14.8. A psychrometric chart is a graphical solution of
various temperature and humidity states of air and
water vapor mixtures. Each point on the chart represents
14-9
-------
one unique combination of the following atmospheric
properties:
(.1) Dry bulb temperature, which is the
actual temperature of the gas.
(2) Wet bulb temperature, which is the temperature
indicated by a thermometer that has its bulb
covered with water and placed in a stream
of moving air.
(3X Relative humidity, which is the ratio of
the partial pressure to the saturation
vapor pressure of water, at the same
temperature.
(.4X Humidity ratio, which is the ratio of the
mass of water vapor present per unit mass
of dry air.
C5)_ Specific volume of dry air, which is the
volume occupied by unit mass of dry air.
If any two of these parameters are known, then the
state point on the psychrometric chart is defined.
The psychrometric chart for normal atmospheric
pressure conditions is shown in Figure 14-1, which
is sufficiently accurate for the estimates involved
in this procedure for most parts of the country.
The curved line along the left side of the chart
represents the 1QO percent relative humidity line, or
the saturation line. Any state point to the left
of this line, or the path of any process crossing
this line, will normally be accompanied by condensation
of the water vapor resulting in the formation of a
steam plume. As can be seen from the psychrometric
chart:
(a) Toward the lower end of the ambient
temperature range it takes very little
14-10
-------
1450 t
o
i
400 x
PSYCHROMETRIC CHART
Barometric Pressure 29.92 Inches of Mercury
350
300
730 •
700
cr
<
650 >
-------
moisture to fully saturate the air, and thus
the possibility of the moisture in the plume
condensing is very high, no matter what the
stack exit conditions may be;
(b) The possibility of a steam plume being formed
is smallest on hot, dry days.
Example of the Use of the Psychrometric Chart
14.9. The psychrometric chart shown in 14.1 may be
used to determine if a condensed water vapor plume is
to be formed from a specific source if the ambient
weather conditions are known.
Usually the information given (or estimated), is
the ambient temperature and relative humidity, and the
effluent gas temperature and moisture content, the
latter being defined as the volume percentage of water
vapor in the effluent gases.
Knowing the moisture content (M.C.), a value for the
humidity ratio may be obtained from the following
expression:
u .,._ D „. 4354 (M.C.) Grains
Humidity Ratio = , ^— '~ .
1-M.C. Lb of Dry Air
which follows from the Ideal Gas Law and the defini-
tions of humidity ratio and moisture content.
The initial state point is given by the effluent gas
temperature and the humidity ratio, and the final
state point is given by the ambient wet and dry bulb
temperatures.
Ambient
Air Temperature (dry bulb) = 70°F
Wet Bulb Temperature = 60°F
Barometric Pressure = 29_ 92 inches Hg
14-12
-------
Effluent Gas
Exhaust Temperature (dry bulb) = 160 F
Moisture Content =16.8%
Substituting these values into the expression for the
humidity ratio gives:
ti -A-* T, „• 4354 (0.168)
Humxdity Ratio = -
= 880 Grains
Lb. of dry air
The state point of the ambient air is at the inter-
section of the 70 F dry bulb temperature line and the
60 F wet bulb temperature line. The effluent gas
state point is at the intersection of the 880 grains per
pound of dry air line and the 160 F dry bulb temperature
line.
Figure 14.2 shows the two state points plotted on the
psychrometric chart. A line connecting these two
state points crosses the saturation curve at about 112°F
and 84 F indicating that a condensed water vapor plume
is a distinct possibility. As the plume mixes with
the ambient air the water vapor in the plume will
begin to condense when the effluent temperature reaches
112 F and will begin to revaporize when its temperature
is further cooled to 84 F.
Bibliography For Subsection on "Reading Water Vapor Plumes"
1. Buffalo Forge Company. Fan Engineering. 19.70..
2. California Air Resources Board. Visible Emission
Evaluation Course Manual. 1974.
3. Crocker, B. B., Water Vapor in Effluent Gases:
What to do about Opacity Problems. Chemical
Engineering, June, 1968.
14-13
-------
0.12
I
M
*•
PSYCHROMETRIC CHART
Barometric Pressure 29.92 Inches of Mercury
40 SO 6O 70 80 90 IOO 110 120 130 140 ISO 160 170 180 190 200 2IO 220 230 240 230 26O 270 280 290 300 310 320 330
DRY BULB TEMPER JRE-'F
Buffalo Forge Company
Figure 14-2. PSYCHROMETRIC CHART (Sea Level Conditions)
-------
4. Faires, V. Thermodynamics. The MacMillan Company,
New York. 1962.
5. Kalika, P. W. How Water Recirculation and Steam
Plumes Influence Scrubber Design. Chemical
Engineering, July 1969.
6. Lee, J. F. and F. W. Sears. Thermodynamics.
Addison-Wesley Publishing Company, 1955.
7. Reigel, S. A. and C. D. Doyle. Using the
Psychrometric Chart. Pollution Engineering,
March 1972.
8. Rohr, F. W. Suppressing Scrubber Steam Plume.
Pollution Engineering, November .19.69.
9., From "Guidelines for Evaluation of Visible Emissions"
EPA^340/l-75-007, April 1975,
14-15
-------
References
Ringelmann, M., "Methods d1Estimation des Fumes
Produites par les Foyers Industriels," La Revue
Technique, 268 (June 1898).
Marks, L. S., "Inadequacy of the Ringelmann Chart,"
Mech. Eng., 681 (Sept. 1937).
Health and Safety Code, State of California, Chap. 2,
Sec. 24242 (19.47)...
Yocom, J. E., "Problems in Judging Plume Opacity,"
J. Air Poll. Control Assn.. 13, 36-39 (Jan. 1963).
Connor, W. D., Hodkinson, J. R. "Optical Properties
and Visual Effects of Smoke Stack Plumes," U. S. Dept.
of HEW, Public Health Service, Publication 999-AP-30,
Cincinnati, 1967, pp. 23-28, 58-59L.
Tukey, J. W., et al., "Restoring the Quality of Our
Environment" Panel of the President's Science Advisory
Committee, the White House, (Nov. 1967), pp. 71-72.
Crocker, B. B., "Water Vapor in Effluent Gases: What
to Do about Opacity Problems," Chemical Engineering
(July 15, 1968)..
Sheehy, J. P., Archinger, W. C., Simon R. A.,
"Psychrometric Chart," Handbook of Air Pollution.
U. S. Dept. of HEW, Public Health Service, pages
11-9-11-14.
Citation: Lloyd A. Fry Company v. Utah Air Conservation
Committee, 545 P 2d 495 (Utah, 19-75). APCA Journal,
August, 1976, Volume 26, No. 8, pg. 819.
Kalika, Peter W. "How Water Recirculation and Steam
Plumes Influence Scrubber Design," Chemical Engineering,
(July 28, 1969).
14-16
-------
STATIONARY SOURCES
S-395
121:1579
METHOD 9 VISUAL DETERMINATION OF THE
OPACITY OP EMISSIONS FROM STATIONARY
SOURCES
Many stationary sources discharge visible
emissions into the atmosphere; these emis-
sions are usually In the shape of a plume.
This method Involves the determination of
plume opacity by qualified observers. The
method includes procedures for the training
and certification of observers, and procedures
to be used In the field for determination of
plume opacity. The appearance of a plume as
viewed by an observer depends upon a num-
ber of variables, some of which may be con-
trollable and Eome of which may not be
controllable in the field. Variables which can
be controlled to an extent to which they no
longer exert a significant Influence upon
plume appearance Include: Angle of the ob-
server with respect to the plume: angle of the
observer with respect to the sun; point of
observation of attached and detached steam
plume; and angle of the observer with re-
spect to a plume emitted from a rectangular
stack with a large length to width ratio. The
method Includes specific criteria applicable
to these variables.
Other variables which may not be control-
lable In the field are luminescence and color
contrast bstween the plume and the back-
ground against which the plume Is viewed.
These variables exert an Influence upon the
appearance of a plume as viewed by an ob-
server, and can affect the ability of the ob-
server to accurately assign opacity values
to the observed plume. Studies of the theory
of plume opacity and field studies have dem-
onstrated that a plume Is most visible and
presents the greatest apparent opacity when
viewed against a contrasting background. It
follows from this, and is confirmed by field
trials, that the opacity of a plume, viewed
under conditions where a contrasting back-
ground Is present can be assigned with the
greatest degree of accuracy. However, the po-
tential for a positive error is also the greatest
when a plume Is viewed under such contrast-
Ing conditions. Under conditions presenting
a less contrasting background, the apparent
opacity of a plume Is less and approaches
zero as the color and luminescence contrast
decrease toward zero. As a result,- significant
negative bias and negative errors can be
made when a plume Is viewed under less
contrasting conditions. A negative bias de-
creases rather than Increases the possibility
that a plant operator will be cited for a vio-
lation of opacity standards due to observer
error.
Studies have been undertaken to determine
the magnitude of positive errors which can
be made by qualified observers while, read-
ing plumes under contrasting conditions and
using the procedures set forth In this
method. The results of these studies (field
trials) which Involve a total of 769 sets of
25 readings each are as follows:
(l).For black plumes (133 sets at a smoke
generator), 100 percent of the sets were
read with a positive error1 of less than ".5
percent opacity; 99 percent were read with
a positive error of less than 5 percent opacity.
(2) For white plumes (170 sets at a smoke
generator, 168 sets at a coal-fired power plant,
298 sets at a sulfuric acid plant), 99 percent
of the sets were read with a positive error of
less than 7.5 percent opacity; 05 percent were
read with a positive error of less than 6 per-
cent opacity.
The positive observational error associated
with an average of twenty-five readings Is
therefore established. The accuracy of the
method must be taken into account when
determining possible violations of appli-
cable opacity standards.
'For a set, positive error=average opacity
determined by observers' 25 observations—
average opacity determined from transmls-
someter's 25 recordings.
1. Principle and applicability.
1.1 Principle. The opacity of emissions
from stationary sources is determined vis-
ually by a qualified observer.
1.2 Applicability. This method Is appli-
cable for the determination of the opacity
of emissions from stationary sources pur-
suant to § 60.11 (b) and for qualifying ob-
servers for visually determining opacity of
emissions.
2. Procedures. The observer qualified In
accordance with paragraph 3 of this method
shall use the following procedures for vis-
ually determining the opacity of emissions:
2.1 Position. The qualified observer shall
stand at a distance sufficient to provide a
clear view of the emissions with the sun
oriented In the 140' sector to his back. Con-
sistent with maintaining the above require-
ment, the observer shall, as much as possible,
make his observations from a position such
that his line of vision Is approximately
perpendicular to the plume direction, and
when observing opacity of emissions from
rectangular outlets (e.g. roof monitors, open
baghouses, nonclrcular stacks), approxi-
mately perpendicular to the longer axis of
the outlet. The observer's line of sight should
not Include more than one plume at a time
when multiple stacks are Involved, and in
any case the observer should make his ob-
servations with his line of sight perpendicu-
lar to the longer axis of such a set 6f multi-
ple stacks (e.g. stub stacks on baghouses).
2.2 Field records. The observer shall re-
cord the name of the plant, emission loca-
tion, type facility, observer's name and
affiliation, and the date on a field data sheet
(Figure 9-1). The time, estimated distance
to the emission location, approximate wind
direction, estimated wind speed, description
of the sky condition (presence and color of
clouds), and plume background are recorded
on a field data sheet at the time opacity read-
ings are initiated and completed.
4-21-78
Published by THE BUREAU OF NATIONAL AFFAIRS, INC.. WASHINGTON. D.C. 20037
91
-------
121:1580
FEDERAL REGULATIONS
Oi
2.3 Observations. Opacity observations
shall be made at the point of greatest opacity
In that portion of the plume where con-
densed water vapor Is not present. The ob-
server shall not look continuously at the
plume, but Instead shall observe the plume
momentarily at 16-second Intervals.
2.3.1 Attached steam plumes. When con-
densed water vapor Is present within the
plume as It emerges from the emission out-
let, opacity observations shall be made be-
yond the point In the plume at which con-
densed water vapor Is no longer visible. The
observer shall record the approximate dis-
tance from the emission outlet to the point
In the plume at which the observations are
made.
2.32 Detached steam plume. When water
vapor In the plume condenses and becomes
visible at a distinct distance from the emis-
sion outlet, the opacity of emissions should
be evaluated at the emission outlet prior to
the condensation of water vapor and the for-
mation of the steam plume.
2.4 Recording observations. Opacity ob-
servations shall be recorded to the nearest 6
percent at 15-second Intervals on an ob-
servational record sheet. (See Figure 9-2 for
an example.) A minimum of 24 observations
shall be recorded. Each momentary observa-
tion recorded shall be deemed to represent
the average opacity of emissions for a 15-
secoad period.
"23 ~Data Reduction. Opacity shall be de-
termined as an average of 24 consecutive
observations recorded at 15-sccond Intervals,
Divide the observations recorded on the rec-
ord sheet Into sets of 24 consecutive obser-
vations. A set is composed of any 24 con-
secutive observations. Sets need not be con-
secutive in time and In no case shall two
sets overlap. For each set of 24 observations,
calculate the average by summing the opacity
of the 24 observations and dividing this sum
by 24. If an applicable standard specifies an
averaging time requiring more than 24 ob-
servations, calculate the average.for all ob-
servations made during the specified time
period. Record the average opacity on a record
sheet. (See Figure 9-1 for an example.)
3. Qualifications and testing.
3.1 Certification requirements. To receive
certification as a qualified observer, a can-
didate must be.tested and demonstrate the
ability to assign opacity readings in 5 percent
Increments to 25 different black plumes and
25 different white plumes, with an error
not to exceed 15 percent opacity on any one
reading and an average error not to exceed
7.5 percent opacity in each category. Candi-
dates shall be tested according to the pro-
cedures described in paragraph 3.2. Smoke
generators used pursuant to paragraph 3.2
shall be equipped with a smoke meter which
meets the requirements of paragraph 3.3.
The certification shall be valid for a period
of 6 months, at which time the qualification
procedure must be repeated by any observer
In order to retain certification.
3.2 Certification procedure. The certifica-
tion test consists of showing the candidate a
complete run of 50 plumes—25 black plumes
and 25 white plumes—generated by a smoke
generator. Plumes within each set of 25 black
and 25 white runs shall be presented In ran-
dom order. The candidate assigns an opacity
value to each plume and records his obser-
vation on a suitable form. At the completion
of each run of 50 readings, the score of the
candidate Is determined. If a candidate falls
to qualify, the complete run of 50 readings
must be repeated In any retest. The smoke
test may be administered as part of a smoke
school or training program, and may be pre-
ceded by training or familiarization runs of
the smoke generator during which candidates
are shown black and white plumes of known
opacity.
3.3 Smoke generator specifications. Any
smoke ganerator used for the purposes of
paragraph 3.2 shall be equipped with a smoke
meter installed to measure opacity across
the diameter of the smoke generator stick.
The smoke meter output shall display In-
Etack opacity based upon a pathlength equal
' to the stack exit diameter, on a full 0 to 100
percent chart recorder scale. The smoke
mster optical design and performance shall
meet the specifications shown in Table 9-1.
The smoke meter shall be calibrated as pre-
scribed in paragraph 3.3.1 prior to the con-
duct of each smoke reading test. At the
completion of each test, the zero and span
drift shall be checked and If the drift ex-
ceeds ±1 percent opacity, the condition shall
be corrected prior to conducting any subse-
quent test runs. The smoke meter shall be
demonstrated, at the time of installation, to
meet the specifications listed In Table 9-1.
This demonstration shall be repeated fol-
lowing any subsequent repair or replacement
of the photocell or associated electronic cir-
cuitry Including the chart recorder or output
meter, or every 6 months, whichever occurs
first.
TABLE 9-1 SMOKE METER DESIGN AND
PERFORMANCE SPECIFICATIONS
Parameter: Specification
a. Light source Incandescent lamp
operated at nominal
rated voltage.
b. Spectral response Photoplc (daylight
of photocell. spectral response of
the human eye—
reference 4.3).
c. Angle of view 15° maximum total
angle.
d. Angle of projec- 15° maximum total
tion. angle.
e. Calibration error. ±3% opacity, maxi-
mum. <
f. Zero and span ±1% opacity, 30
drift. minutes.
g. Response time— £5 seconds.
3.3.1 Calibration. The smoke meter Is
calibrated after allowing a minimum of 30
minutes warmup by alternately producing
simulated opacity of 0 percent and 100 per-
cent. When stable response at 0 percent or
100 percent Is noted, the smoke meter is ad-
justed to produce an output of 0 percent or
100 percent, as appropriate. This calibration
shall be repeated until stable 0 percent and
100 percent readings are produced without
adjustment. Simulated 0 percent and 100
percent opacity values may be produced by
alternately switching the power to the light
source on and off while the smoke generator
Is not producing smoke.
Environment Reporter
[Appendix A]
92
-------
g
2
C
a
5!
n
1
n
G
COMPANY
LOCATION
TEST NUMBER,
DATE
TYPE FACILITY
CONTROL DEVICE
FIGURE 9-1
RECORD OF VISUAL. DETERMINATION. OF OPACITY
pf_
HOURS OF OBSERVATION.
OBSERVER
OBSERVER CERTIFICATION DATE_
OBSERVER AFFILIATION
POINT OF EMISSIONS
O
30
O
c
3D
O
HEIGHT OF DISCHARGE POINT
z
I
r
3
to
Z
n
i
O
O
to
a
a
x'
CLOCK TIME
12 OBSERVER LOCATION
Distance to Discharge
Direction from Discharge
Height of Observation Point
BACKGROUND DESCRIPTION
WEATHER CONDITIONS
Wind Direction
Wind Speed
Ambient Temperature
SKY CONDITIONS (clear,
overcast, % clouds, etc.)
PLUME DESCRIPTION
Color
Distance Visible
OTHER IHFOOTIOtl
Initial
Final
SUMMARY OF AVERAGE OPACITY
Set
Number
TlmP
Start—End
Opadti
Sum.
"verage
Readings ranged from
to
% opacity
The source was/was not In compliance with
the time evaluation was made.
.at
to
-------
COMPANY
LOCATION
TEST NUMBER
DATE
73
a
•o
o
3
a
FIGURE 9-2 OBSERVATION RECORD
PAGE OF
OBSERVER
TYPE FACILITY
POINT OF EMISSIONS
Hr.
M1n.
0
1
2
3
4
5
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
Seconds
n
m
:w
r~
30
o
z
V)
-------
CHAPTER XVI
FEDERAL STANDARDS OF PERFORMANCE FOR
NEW STATIONARY SOURCES OF AIR POLLUTION
A Summary of Regulations
Linda S. Chaput
U. S. Environmental Protection Agency
In order to make the information in the Federal Register more easily ac-
cessible, a summary has been prepared of Federal standards of perfor-
mance for new stationary sources of air pollution. The standards of perfor-
mance promulgated by the Environmental Protection Agency in the peri-
od from December 1971 through June 1976 are presented in tabular form.
Ms. Chaput is in the Standards
Development Branch, Office of Air
Quality Planning and Standards, U.
S. Environmental Protection Agen-
cy, Research Triangle Park, NC
27711.
Anyone who must use the Federal Reg-
ister frequently to refer to regulations
published by Federal agencies is well
aware of the problems of sifting through
the many pages to extract the "meat" of
a regulation. Although regulatory lan-
guage is necessary to make the intent of
a regulation clear, a more concise refer-
ence to go to when looking up a partic-
ular standard would be helpful. With
this in mind, the following table was
developed to assist those who work with
Federal standards of performance for
new stationary sources of air pollu-
tion.
The table lists the standards of per-
formance which the Environmental
Protection Agency (EPA) has promul-
gated since December 1971. It includes
the categories of stationary sources and
the affected facilities to which the
standards apply; the pollutants which
Reprinted from APCA JOURNAL, Vol. 26, No. 11, November 1976
16-1
-------
Standards of Performance - 40 CFR Part 60.
Source Affected
category facility
Subpart D:
Steam generators Coal fired boilers
(>250 million Btu/hr)
Promulgated
12/23/71 (36 FR 24876)
Revised
7/26/72 (37 FR 14877)
6/14/74 (39 FR 20790) oil fired boilers
1 /1 6/75 (40 FR 2803)
10/6/75 (40 FR 46250)
Gas fired boilers
Subpart E:
Incinerators Incinerators
(>50 tons/day)
Pollutant
Particulate
Opacity
S02
NOX
(except lignite
and coal
refuse)
Particulate
Opacity
SO2
NOX
Particulate
Opacity
NOX
Particulate
Emission level
0.10lb/106Btu
20%
1.2 lb/10<*Btu
0.70 lb/1Q6Btu
0.10lb/106Btu
20%; 40% 2min/hr
0.80lb/106Btu
0.30lb/106Btu
0.10 lb/106Btu
20%
0.20lb/106Btu
0.08 gr / dscf corrected
to 12% CO2
Monitoring
requirement
No requirement
Continuous
Continuous
Continuous
No requirement
Continuous
Continuous
Continuous
No requirement
No requirement
Continuous
No requirement
Promulgated
12/23/71 (36 FR 24876)
Revised
6/14/74 (39 FR 20790)
Subpart F:
Portland cement plants
Promulgated
12/23/71 (36 FR 24876)
Revised
6/14/74 (39 FR 20790)
1 1/1 2/74 (39 FR 39874)
10/6/75 (40 FR 46250)
Subpart G:
Nitric acid plants
Kiln
Clinker cooler
Fugitive
Emission points
Process equipment
Perticulate
Opacity
Particulate
Opacity
Opacity
Opacity
NOX
0.30 Ib/ton
20%
0.10 Ib/ton
10%
10%
10%
3.0 Ib/ton
No requirement
No requirement
No requirement
No requirement
No requirement
No requirement
Continuous
Promulgated
12/23/71 (36 FR 24876)
Revised
5/23/73 (38 FR 13562)
6/14/74 (39 FR 20790)
10/6/75 (40 FR 46250)
Subpart H:
Sulfuric acid plants
Promulgated
12/23/71 (36 FR 24876)
Revised
5/23/73 (38 FR 13562)
6/14/74 (39 FR 20790)
10/6/75 (40 FR 46250)
Process equipment
SO2
Acid mist
Opacity
4.0 Ib/ton
0.15 Ib/ton
10%
Continuous
No requirement
No requirement
1056
16-2
Journal of the Air Pollution Control Association
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Source
category
Affected
facility
Pollutant
Emission level
Monitoring
requirement
Subpart I:
Asphalt concrete plants
Promulgated
3/8/74 (39 FR 9308)
Revised
10/6/75 (40 FR 46250)
Dryers; screening and Particulate 0.04 gr/dscf
weighing systems; (90 mg/dscm)
storage, transfer, and Opacity 20%
loading systems; and
dust handling equipment
No requirement
No requirement
Subpart J:
Petroleum refineries
Promulgated
3/8/74 (39 FR 9308)
Revised
10/6/75 (40 FR 46250)
Catalytic cracker
Fuel gas
combination
Particulate
Opacity
CO
SO2
1.0 lb/1000 Ib
30% (3 min. exemption)
0.05%
0.1 gr H2S/dscf
(230 mg/dscm)
No requirement
Continuous
Continuous
Continuous
Subpart K:
Storage vessels for
petroleum liquids
Promulgated
3/8/74 (39 FR 9308)
Revised
4/17/74 (39 FR 13776)
6/14/74 (39 FR 20790)
Subpart L:
Secondary lead
smelters
Promulgated
3/8/74 (39 FR 9308)
Reviced
4/17/74(39FR13776)
10/6/75 (40 FR 46250)
Storage tanks
>40,000 gal. capacity
Hydrocarbons
For vapor pressure
78-570 mm Hg, equip
with floating roof,
vapor recovery system,
or equivalent; for
vapor pressure >570
mm Hg, equip with
vapor recovery system
or equivalent
No requirement
Reverberatory and
blast furnaces
Pot furnaces
Particulate
Opacity
Opacity
0.022 gr/dscf
(50 mg/dscm)
20%
10%
No requirement
No requirement
No requirement
Subpart M:
Secondary brass and
bronze plants
Promulgated
3/8/74 (39 FR 9308)
Revised
10/6/75 (40 FR 46250)
Subpart N:
Iron and steel plants
Promulgated
3/8/74 (39 FR 9308)
Reverberatory
furnace
Blast and
electric furnaces
Basic oxygen
process furnace
Particulate 0.022 gr/dscf
(50 mg/dscm)
Opacity 20%
Opacity 10%
Paniculate 0.022 gr/dscf
(50 mg/dscm)
No requirement
No requirement
No requirement
No requirement
November 1976 Volume 26, No. 11
16-3
1057
-------
Source
category
Affected
facility
Pollutant
Emission level
Monitoring
requirement
Subpart O:
Sewage treatment
plants
Promulgated
3/8/74 (39 FR 9308)
Revised
4/17/74(39FR13776)
5/3/74 (39 FR 15396)
10/6/75 (40 FR 46250)
Sludge incinerators
Particulate
Opacity
1.30lb/ton
20%
Mass or volume
of sludge
No requirement
Subpart P:
Primary copper
smelters
Promulgated
1/15/76(41 FR2331)
Revised
2/26/76 (41 FR 8346)
Dryer
Roaster, smelting
furnace,* copper
converter
•Reverberatory furnaces
that process high-
impurity feed materials
are exempt from
SC>2 standard
Particulate
Opacity
S02
Opacity
0.022 gr/dscf
(50 mg/dscm)
20%
0.065%
20%
No requirement
Continuous
Continuous
No requirement
Subpart Q:
Primary zinc
smelters
Promulgated
1/15/76(41 FR 2331)
Subpart R.:
Primary lead
smelters
Promulgated
1/15/76(41 FR2331)
Subpart S:
Primary aluminum
reduction plants
Promulgated
1/26/76(41 FR3825)
Sintering machine
Roaster
Blast or reverberatory
furnace, sintering
machine discharge end
Sintering machine,
electric smelting
furnace, converter
Potroom group
(a) Soderberg
plant
(b) Prebake
plant
Anode bake plants
Particulate
Opacity
SO2
Opacity
Particulate
Opacity
SO2
Opacity
(a) Total
fluorides
Opacity
(b) Total
fluorides
Opacity
Total fluorides
Opacity
0.022 gr/dscf
(50 mg/dscm)
20%
0.065%
20%
0.022 gr/dscf
(50 mg/dscm)
20%
0.065%
20%
2.0 Ib/ton
10%
1.9 Ib/ton
10%
0.1 Ib/ton
20%
No requirement
Continuous
Continuous
No requirement
No requirement
Continuous
Continuous
No requirement
No requirement
No requirement
No requirement
No requirement
No requirement
No requirement
are regulated and the levels to which
they must be controlled; and the re-
quirements for monitoring emissions
and operating parameters. The stan-
dards apply to new, modified, and re-
constructed stationary sources of air
pollution and are set at levels required
to control emissions of air pollutants to
the greatest degree practicable using the
best systems of emission reduction,
considering the costs of such reduc-
tion.
1058
16-4
Journal of the Air Pollution Control Association
-------
Source
category
Affected
facility
Pollutant
Emission level
Monitoring
requirement
Subpart T:
Phosphate fertilizer
plants
Promulgated
8/6/75 (40 FR 33152)
Subpart U:
Subpart V:
Subpart W:
Subpart X:
Wet process
phosphoric acid
Superphosphoric acid
Diammonium
phosphate
Triple super-
phosphate
Granular triple
superphosphate
Total fluorides
Total fluorides
0.02 Ib/ton
0.01 Ib/ton
Total fluorides 0.06 Ib/ton
Total fluorides 0.2 Ib/ton
Total fluorides 5.0x10-"
Ib/hr/ton
Total pressure
drop across
process
scrubbing
system
Total pressure
drop across
process
scrubbing
system
Total pressure
drop across
process
scrubbing
system
Total pressure
drop across
process
scrubbing
system
Total pressure
drop across
process
scrubbing
system
Subpart Y:
Coal preparation
plants
Promulgated
1/15/76(41 FR2232)
Thermal dryer
Pneumatic coal
cleaning equipment
Processing and Conveying
equipment, storage
systems, transfer and
loading systems
Particulate
Opacity
Particulate
Opacity
Opacity
0.031 gr/dscf
(0.070 g/dscm)
20%
0.018 gr/dscf
(0.040 g/dscm)
10%
20%
Temperature
Scrubber
pressure loss
Water pressure
No requirement
No requirement
No requirement
No requirement
Subpart Z:
Ferroalloy production
facilities
Promulgated
5/4/76(41 FR 18497)
Revised
5/20/76 (41 FR 20659)
Electric submerged
arc furnaces
Particulate
0.99 Ib/Mw-hr
(0.45 kg/Mw-hr)
("high silicon alloys")
0.51 Ib/Mw-hr
(0.23 kg/Mw-hr)
(chrome and
manganese alloys)
No visible emissions
may escape furnace
capture system
No requirement
Flowrate
monitoring
in hood
Before developing standards for a
particular source category, EPA must
first identify the pollutants emitted and
determine that they contribute signifi-
cantly to air pollution which endangers
public health or welfare. The standards
are then developed and proposed in the
Federal Register. After a period of time
during which the public is encouraged to
submit comments on the proposal, ap-
propriate revisions are made to the
regulations and they are promulgated in
November 1976 Volume 26, No. 11
16-5
1059
-------
Source
category
Affected
facility
Pollutant
Emission level
Monitoring
requirement
Ferroalloy production
facilities (cont.)
Dust handling equipment
Opacity
CO
Opacity
No visible emission
may escape tapping
system for >40% of
each tapping period
15%
20% volume basis
10%
Flowrate
monitoring
in hood
Continuous
No requirement
No requirement
Subpart AA:
Iron and steel
plants
Promulgated
9/23/75 (40 FR 43850)
Electric arc Furnaces
Particulate
Opacity
(a) control
device
(b) shop roof
Dust handling equipment
Opacity
0.0052 gr/dscf
(12 mg/dscm)
3%
0, except
20%—charging
40%—tapping
10%
No requirement
Continuous
Flowrate
monitoring
in capture hood
Pressure
monitoring
in DSE system
No requirement
the Federal Register. To cite such a
promulgation, it is common to refer to it
by volume and page number, i.e., 36 FR
24876, which means Volume 36, page
24876 of the Federal Register. The table
gives such references for the promulga-
tion and subsequent revisions of each
standard listed.
Once a year, all regulations that have
been published in the Federal Register
during that year are codified for inclu-
sion in the Code of Federal Regulations
(CFR). Only the regulations are codi-
fied; the preambles which appear with
the regulations in the Federal Register
are not included in the CFR. The CFR
is divided into 50 titles which represent
broad areas subject to Federal regula-
tion. Each title is divided into chapters
which usually, bear the name of the
issuing agency. Each chapter is further
subdivided into parts covering specific
regulatory areas. EPA's regulations are
included in Title 40—Protection of the
Environment, Chapter I—Environ-
mental Protection Agency. Breaking the
classification down further, Subchapter
C covers regulations concerning Air
Programs which is then broken down
into more specific parts. Part 60 is titled
"Standards of Performance for New
Stationary Sources," thus the reference
in the table heading to 40 CFR Part
60.
The table lists all standards of per-
formance promulgated through June
1976. The complete regulations for these
standards are included in the CFR
which was revised July 1, 1976, and
contains Parts 60 to 99. Any regulations
proposed or promulgated between July
1,1976, and July 1,1977, will appear in
the Federal Register (published daily
Acept Saturday and Sunday) and will
b3 codified in the 1977 revision to the
CFR. Anyone wishing to subscribe to the
Federal Register or purchase the CFR
should contact the Superintendent of
Documents, U.S. Government Printing
Office, Washington, DC 20402.
1060
16-6
Journal of the Air Pollution Control Association
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CHAPTER XVII.
VISIBLE EMISSION STANDARDS
OF THE UNITED STATES
Volume 2 of "The World's Air Quality Management
Standards," EPA publication No. EPA 650/9-75-001-b by W.
Martin and Arthur C. Stern, gives visible emission
standards in existence as of 1973 for 49. states, the
District of Columbia and Puerto Rico expressed in terms
of emissions from mobile sources, aircraft, automobiles,
trucks and buses, locomotives, and marine vessels, as
well as from a wide variety of stationary sources and
the combustion of wood, fossil fuels, and refuse. This
publication is available from the National Technical
Information Service, 5285 Port Royal Road, Springfield,
Virginia 22161. Another source of information would
be reference to the "Environmental Reporter" available
in most libraries.
With the requirement of State Implementation Plans by
Section 110 of the Clean Air Act, as amended,
all 55 states and territories have adopted Ringelmann
and equivalent opacity provisions, now commonly referred
to as "opacity regulations." The standard predominantly
adopted by the states is 20 percent opacity; however, a
few agencies and the Federal Government in some of their
new source performance standards are adopting 10 percent
and in some cases zero opacity regulations for many
source categories. There is now considerable test
data available to support new source performance
standards with very low opacity limitations.
17-1
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-450/3-78-106
2.
I. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
VISIBLE EMISSIONS EVALUATION
TRAINING COURSE 439
Student Manual
- AIR POLLUTION
5. REPORT DATE
September 1978
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Northrop Services, Inc.
Air Pollution Training Institute
c/o U.S. Environmental Protection Agency (MD-20)
Research Triangle Park, NC 27711
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
68-02-2374
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Control Programs Development Division
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
FINAL
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
There is an accompanying instructor's and operators manual to be used in conducting
visible emission training courses. See EPA publication EPA-450/3-78-105.
16. ABSTRACT
This manual is to be used by students who are learning how to evaluate ("read")
visible emissions to the atmosphere from air pollution sources. Both black, grey,
and white plumes are covered. The manual discusses sources of air pollution and
describes visible emissions to be expected and the reasons why such may occur. A
brief review of meteorological phenomena affecting stack plume behavior is given.
Practices and procedures to be used in evaluating visible emissions of both the
black/grey and other color nature are described in detail. The Ringelmann chart
and its use are discussed. Equipment for generating visible emissions to be observed
in training observers is described in detail.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
EPA Method 9
Smoke
Air Pollution
Inspection
Effluents
Detection
training materials
smoke inspection
visible emissions
13 b
68 A
18. DISTRIBUTION STATEMENT
Unlimited.
Available from National Technical
Information Service, 5285 Port Royal
Road. -
19. SECURITY CLASS (This Report)
unrl agg-if -i
21. NO. OF PAGES
240
20. SECURITY CLASS (Thispage/
unclassified
22. PRICE
EPA Form 2220-1 (9-73)
17-3
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