EPA-450/2-74-017a
BACKGROUND INFORMATION
FOR STANDARDS OF PERFORMANCE:
ELECTRIC ARC FURNACES
IN THE STEEL INDUSTRY
VOLUME 1: PROPOSED STANDARDS
Emission Standards and Engineering Division
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air and Waste Management
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
October 1974
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This report is issued by the Environmental Protection Agency to report
technical data of interest to a limited number of readers. Copies are
available free of charge to Federal.employees, current contractors and
grantees, and nonprofit organizations - as supplies permit - from the Air
Pollution Technical Information Center, Environmental Protection Agency,
Research Triangle Park, North Carolina 27711; or, for a fee, from the
National Technical Information Service, 5285 Port Royal Road, Springfield,
Virginia 22161.
Publication No, EPA-450/2-74-017a
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PREFACE
A. Purposeof this Report
Standards of performance under section 111 of the Clean
Air Act— are proposed only after a very detailed investigation
of air pollution control methods available to the affected
industry and the impact of their costs on the industry. This
report summarizes the information obtained from such a study of
electric arc furnaces in the steel industry. It is being distributed in
connection with formal proposal of standards for that industry
1>n the Federal Reglster. Its purpose is to explain the
background and basis of the proposal in greater detail than
could be included in the Fede ra1 Regis te r, and to facilitate
analysis of the proposal by interested persons, including those
who may not be familiar with the many technical aspects of the
industry. For additional information, for copies of documents
(other than published literature) cited in the Background
Information Document, or to comment on the proposed standards,
contact Mr, Don R. Goodwin, Director, Emission Standards and
Engineering Division, United States Environmental Protection
Agency, Research Triangle Park, North Carolina 27711 [(919)688-8146],
B. Authority for the Standards
Standards of performance for new stationary sources are
promulgated in accordance with section 111 of the Clean Air Act
(42 DSC 1857c-6), as amended in 1970. Section 111 requires
]_/ Sometimes referred to as "new source performance
standards" (NSPS).
in
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the establishment of standards of performance for new stationary
sources of air pollution which "... may contribute significantly
to air pollution which causes or contributes to the endangerment
of public health or welfare." The Act requires that standards
of performance for such sources reflect "... the degree of
emission limitation achievable through the application of the best
system of emission reduction which (taking into account the cost
of achieving such reduction) the Administrator determines has
been adequately demonstrated." The standards apply only to
stationary sources, the construction or modification of which
commences after regulations are proposed by publication in
the Federal Register.
Section 111 prescribes three steps to follow in establishing
standards of performance.
1. The Administrator must identify those categories of
stationary sources for which standards of performance
will ultimately be promulgated by listing them in the
Federal Register.
2. The regulations applicable to a category so listed must
"be proposed by publication in the Federal Register within
120 days of its listing. This proposal provides interested
persons an opportunity for comment.
3. Within 90 days after the proposal, the Administrator
must promulgate standards with any alterations he deems
appropriate.
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It is important to realize that standards of performance,
by themselves, do not guarantee protection of health or welfare;
that is, they are not designed to achieve any specific air
quality levels. Rather, they are designed to reflect best
demonstrated^technology (taking into account costs) for the
affected sources. The overriding purpose of the collective
body of standards is to maintain existing air quality and to
prevent new pollution problems from developing.
Previous legal challenges to standards of performance for
Portland cement plants, steam generators, and sulfuric acid
plants have resulted in several court decisions—' of importance
in developing future standards. In those cases, the principal
issues were whether EPA: (1) made reasoned decisions and
fully explained the basis of the standards, (2) made available
to interested parties the information on which the standards
were based, and (3) adequately considered significant comments
from interested parties.
Among other things, the court decisions established:
(1) that preparation of environmental impact statements is not
necessary for standards developed under section 111 of the Clean
Air Act because, under that section, EPA must consider any
counter-productive environmental effects of a standard in
determining what system of control is "best;" (2) in considering
costs it is not necessary to provide a cost-benefit analysis;
2?Port!ant Cement Association v Ruckelshaus, 486 F, 2nd
375 (D.C. Cir. 1973); Essex Chemical Corp. v Ruckelshaus, 486
F. 2nd 427 {D.C. Cir. 1973).
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(3) EPA is not required to justify standards that require different
levels of.control in different industries unless such different
standards may. be unfairly discriminatory; and (4) it is
sufficient for EPA to show that a standard can be achieved
rather than that it has been achieved by existing sources.
Promulgation of standards of performance does not prevent
State or local agencies from adopting more stringent emission
limitations for the same sources. On the contrary section 116
of the Act (42 USC 1857-D-l) makes clear that States and other
political subdivisions may enact more restrictive standards.
Furthermore, for heavily polluted areas, more stringent standards
may be required under section 110 of the Act (42 USC 1857c-5) in
order to attain or maintain national ambient air quality standards
prescribed under section 109 (42 USC 1857c-4). Finally, section 11
makes clear that a State may not adopt or enforce less stringent
standards than those adopted by EPA under section 111.
Although it is clear that standards of performance should be
3/
in terms of limits on emissions where feasible,—' an alternative
method of requiring control of air pollution is sometimes
necessary. In some cases physical measurement "of emissions
from a new source may be impractical or exorbitantly expensive.
37'"Standards of performance,' ... refers to the degree of
emission control which can be achieved through process changes,
operation changes, direct emission control, or other methods. The
Secretary [Administrator] should not make a technical judgment
as to how the standard should be implemented. He should determine
the achievable limits and let the owner or operator determine the
most economical technique to apply." Senate Report 91-1196.
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For example, emissions of hydrocarbons from storage vessels for
petroleum liquids are greatest during storage and tank filling.
The nature of the emissions (high concentrations for short
periods during filling and low concentrations for longer
periods during storage) and the configuration of storage tanks
make direct emission measurement highly impractical, Therefore,
a more practical approach to standards of performance for
storage vessels has been equipment specification.
C. Selection of Categories of Stationary Sources
Section 111 directs the Administrator to publish and from
time to time revise a list of categories of sources for which
standards of performance are to be proposed. A category is to
be selected "... if [the Administrator] determines it may contribute
significantly to air pollution which causes or contributes to the
endangerment of public health or welfare."
Since passage of the Clean Air Amendments of 1970, considerable
attention has been given to the development of a system for
assigning priorities to various source categories. In brief,
the approach that has evolved is as follows.
First, ^we assess any areas of emphasis by considering the
broad EPA strategy for implementing the Clean Air Act. Often,
these "areas" are actually pollutants which are primarily emitted
by stationary sources. Source categories which emit these
pollutants are then evaluated and ranked by a process involving
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such factors as (1) the level of emission control (if any)
already required by State regulations; (2) estimated-levels •
of control that might result from standards of performance for the
source category; (3) projections of growth and replacement
of existing facilities for the source category; and (4) the
estimated incremental amount of air pollution that could be
prevented, in a preselected future year, by standards of
performance for the source category.
After the relative ranking is complete, an estimate
must be made of a schedule of activities required to develop
a standard. In some cases, it may not be feasible to immediately
develop a standard for a source category with a very high,
priority. This might occur because a program of research
and development is needed or because techniques for sampling
and measuring emissions may require refinement before study
of the industry can be initiated. The schedule of activities
must also consider differences in the time required to complete
the necessary investigation for different source categores.
Substantially more time may be necessary, for example, if a
number of pollutants must be investigated in a single source
category. Even late in the development process the
schedule for completion of a standard may change. For
example, inability to obtain emission data from
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well-controlled sources in time to pursue the development
process in a systematic fashion may force a cha'nge in
scheduling.
Selection of the source category leads to another major
decision: determination of the types of sources or facilities
to which the standard will apply. A source category often
has several facilities that cause air pollution. Emissions
from some of these facilities may be-insignificant and, at the
same time, very expensive to control. An investigation of
economics may show that, within the costs that an owner could
reasonably afford, air pollution control is better served by
applying standards to the more severe pollution problems. For
this reason (or perhaps because there may be no adequately
demonstrated system for controlling emissions from certain
facilities), standards often do not apply to all sources within
a category. For similar reasons, the standards may not apply
to all air pollutants emitted by such sources. Consequently,
although a source category may be selected to be covered by a
standard of performance, treatment of some of the pollutants or
facilities within that source category may be deferred.
D. Procedure for Development of Standards of Performance
Congress mandated that sources regulated under section 111
of the Clean Air Act be required to utilize the best practicable
air pollution control technology that has been adequately
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demonstrated at the time of their design and construction. In so
doing. Congress sought to:
1. maintain existing high-quality air,
2. prevent new air pollution problems, and
3. ensure uniform national standards for new facilities.
The selection of standards of performance to achieve the
Intent of Congress has been surprisingly difficult. In general,
the standards must (1) realistically reflect best demonstrated
control practice; (2) adequately consider the cost of such control;
(3) be applicable to existing sources that are modified as well
as new installations; and (4) meet these conditions for all
variations of operating conditions being considered anywhere in
the country.
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A major portion of the program for development of standards
is spent identifying the best system of emission reduction which
"has been adequately demonstrated" and quantifying the emission
rates achievable with the system. The legislative history of
section 111 and the court decisions referred to above make clear
that the Administrator's judgment of what is adequately demonstrated
1s not limited to systems that are in actual routine use.
Consequently, the search may include a technical assessment
of control systems which have been adequately demonstrated but
for which there is limited operational experience. To date,
determination of the "degree of emission limitation achievable"
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has been commonly based on (but not restricted to) results
of tests of emissions from existing sources. This has
required worldwide investigation and measurement of emissions
from control systems. Other countries with heavily populated,
industrialized areas have sometimes developed more effective
systems of control than those used in the United States.
Because the best demonstrated systems of emission reduction may
not be in widespread use, the data base upon which the standards
are established will necessarily be somewhat limited. Test
data on existing well-controlled sources are an obvious starting
point in developing emission limits for new sources. However,
since the control of existing sources generally represents
retrofit technology or was originally designed to meet an
existing State or local regulation, new sources may be able
to meet more stringent emission standards. Accordingly, other
information must be considered and judgment is necessarily
involved in setting proposed standards.
Since passage of the Clean Air Amendments of 1970, a
process for the development of a standard has evolved. In
general, 'it follows the guidelines below.
1. Emissions from existing well-controlled sources
are measured.
2. Data on emissions from such sources are assessed with
consideration of such factors as: (a) the representativeness
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of the source tested (feedstock, operation, size, age,
etc.); (b) the age and maintenance of the control
equipment tested (and possible degradation in the
efficiency of control of similar new equipment even
•
with good maintenance procedures)5 (c) the design
uncertainties for the type of control equipment being
considered; and (d) the degree of uncertainty affecting
the judgment that new sources will be able to achieve
similar levels of control.
3. During development of the standards, information from
pilot and prototype installations, guarantees by vendors
of control equipment, contracted (but not yet constructed)
projects, foreign technology, and published literature
are considered, especially for sources where "emerging"
technology appears significant.
4. Where possible, standards are set at a level that is
achievable with more than one control technique or
licensed process.
5. Where possible, standards are set to encourage (or at least
permit) the use of process modificatiens or new processes
as a method of control rather than "add-on" systems of
air pollution control.
6. Where possible, standards are set to permit use of
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systems capable of controlling more than one pollutant
{for example, a scrubber can remove both gaseous and
particulate matter emissions, whereas an electrostatic
precipitator is specific to particulate matter).
7. Where appropriate, standards for visible emissions are
established in conjunction with mass emission standards.
In such cases, the standards are set in such a way that
a source meeting the mass emission standard will be able
-to meet the visible emission standard without additional
controls. (In some cases, such as fugitive dust, there
is no mass standard).
Finally, when all pertinent data are available, judgment
is again required. Numerical tests may not be transposed directly
into regulations. The design and operating conditions of those
sources from which emissions were actually measured cannot be
reproduced exactly by each new source to which the standard of
performance will apply.
E. How Costs are Considered
Section 111 of the Clean Air Act requires that cost be
considered in setting standards of performance* To do this requires
an assessment of the possible economic effects of implementing
various levels of control technology in new plants within a
given industry. The first step in this analysis requires the
generation of estimates of installed capital costs and annual
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operating costs for various demonstrated control systems,
each control system alternative having a different overall
control capability. The final step in the analysis is to
determine the economic impact of the various control alternatives
upon a new plant in the industry. The fundamental question to
be addressed in this step is whether or not a new plant would
be constructed given that a certain level of control costs would
be Incurred. Other issues that would be analyzed in this step
would be the effects of control costs upon product prices and the
effects on product and raw material supplies and producer
profitability.
The economic impact upon an industry of a proposed standard
is usually addressed both in absolute terms and by comparison
with the control costs that would be incurred as a result
of compliance with typical existing State control regulations.
This incremental approach is taken since a new plant would
be required to comply with State regulations in the absence
of a Federal standard of performance. This approach requires
a detailed analysis of the impact upon the industry resulting
from the cost differential that usually exists between the
standard of performance and the typical State standard.
It should be noted that the costs for control of air
pollutants are not the only control costs considered. Total
environmental costs for control of water pollutants as well
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as air pollutants are analyzed wherever possible.
A thorough study of the profitability and price-setting
mechanisms of the industry is essential to the analysis so
that an accurate estimate of potential adverse economic impacts
can be made. It is also essential to know the capital requirements
placed on plants in the absence of Federal standards of performance
so that the additional capital requirements necessitated by these
standards can be placed in the proper perspective. Finally, it
is necessary to recognize any constraints on capital availability
within an industry as this factor also influences the ability
of new plants to generate the capital required for installation
of the additional control equipment needed to meet the standards
of performance.
The end result of the analysis is a presentation of costs
and potential economic impacts for a series of control
alternatives. This information is then a major factor which
the Administrator considers in selecting a standard.
F. Impact on Existing Sources
Proposal of standards of performance may affect an existing
source in either of two ways. First, if modified after
proposal of the standards, with a subsequent increase in
air pollution, it is subject to standards of performance as
if it were a new source. (Section 111 of the Act defines a
new source as "any stationary source, the construction or
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modification of which is commenced after the regulations are
proposed.")—/
Second, promulgation of a standard of performance requires
States to establish standards of performance for the same pollutant
for existing sources in the same industry under section lll(d) of
the Act; unless the pollutant limited by the standard for new
sources is one listed under section 108 (requiring promulgation of
national ambient air quality standards) or one listed as a
hazardous pollutant under section 112. If a State does not act,
EPA must establish such standards. Regulations prescribing
procedures for control of existing sources under section lll{d)
will be proposed as Subpart B of 40 CFR Part 60.
G. Revision ofStandards of Performance
Congress was aware that the level of air pollution control
achievable by any industry may improve with technological
advances. Accordingly, section 111 of the Act provides that
the Administrator may revise such standards from time to time.
Although standards proposed and promulgated by EPA under section 111
are designed to require installation of the "... best system of
emission 'reduction (taking into account the, cost)..."
the standards will be reviewed periodically. Revisions will be
proposed and promulgated as necessary to assure that the standards
4/ Spedf i c provisions dealing with modifications to existing
facilities are being proposed by the Administrator under the
General Provisions of 40 CFR Part 60.
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continue to reflect the best systems that become available
in the future. Such revisions will not be retroactive but
will apply to stationary sources constructed or modified after
proposal of the revised standards.
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TABLE OF CONTENTS
I. THE STEEL INDUSTRY (ELECTRIC ARC FURNACES) 1
A. General 1
B. Description of the Process 7
C. Emissions 9
II. PROPOSED OF 13
A. Standards as Proposed 13
B. Discussion of the Concentration Standard 14
C. Discussion of the Opacity Standard on the Control
Device . 16
D. Discussion of the Opacity Standards on the Building. . 17
III. EMISSION CONTROL TECHNOLOGY 21
A. Direct Shell Evacuation System in Combination with
Natural Ventilation Through the Open Roof ...... 22
B.. Building Evacuation in a Shop with a Sealed Roof ... 26
C. Canopy Hoods in a Shop with a Sealed Roof 28
D. Canopy Hoods In Combination with Natural Ventilation . 3jD
E. Combinations 32
F. General Discussion 34
IV. ENVIRONMENTAL EFFECTS 43
A. Impact on Air Pollution 43
B. Impact on Water, Soltd Waste, and Noise Pollution . . 53
C. Impact on Energy Considerations 54
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V. SUMMARY OF THE PROCEDURE FOR DEVELOPING STANDARDS 63
A. Literature Review and Industrial Contacts ....... 63
B. Selection of Pollutants 63
C. Affected Facilities 65
D. Plant Inspections 66
E. Emission Measurement Program , ..... 68
F. Units of the Standard , 69
6. Development of the Proposed Standards 72
VI. DATA TO SUBSTANTIATE A .............. 77
A. Particul ate Emission Data . . 77
B. Carbon Monoxide Emission Data ..... 88
VII, SUMMARY OF ECONOMIC INFORMATION ..... 93
A. Cost 93
B. Economic Impact 101
C. Overall Economic Considerations 101
VIII. ALTERNATIVE STANDARDS ,.,.,..».....,».,.. 107
A. Alternative Standards for Particulate and Visible
Emissions from the Electric Arc Furnace 107
B. Alternative Standards for Carbon Monoxide Emissions
from the Electric Arc Furnace 118
C, Alternative Standards for Visible Emissions from
Handling of Dust Collected by the Fabric Filter .... 120
D. Discussion of the Alternative Standards ........ 121
E. Draft Standard . ........ 125
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IX. ENFORCEMENT ASPECTS OF THE PROPOSED STANDARD ...... 133
A. General .................. .... 133
B. Determination of Compliance with the Concentration
Standards ......... . ........... 134
C. Determination of Compliance with Visible Emission
Standards .............. ....... 138
D. Installation and operation of an Opacity Honitoring
Device ..... ................. 139
X. MODIFICATIONS
XI. MAJOR ISSUES CONSIDERED . . .......... .... 143
A. Issue No. 1 ..... ...... . ........ 143
B. Issue No. 2 ......... ........... 14S
C. Issue No. 3 ....... . ..... ....... 148
D. Issue No. 4 ........... . ...... . . 149
XII. REFERENCES ...................... 151
TECHNICAL REPORT DATA SHEET ... ...... ........ 157
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I. THE STEEL INDUSTRY (ELECTRIC ARC FURNACES)
A, General
Major sources of air pollution in the steel industry are basic oxygen
process, electric arc and open hearth steel production furnaces; blast
furnaces; and coke and sintering plants (Figure 1-1). All will emit large
quantities of air pollutants (primarily particulate matter) if not properly
controlled. The first standards of performance for the industry were
promulgated for basic oxygen process furnaces on March 8, 1974. This
.document discusses standards for electric arc furnaces. EPA has now
initiated an investigation of emissions from coke plants and still other
sources will be considered as potential candidates for standards at a
future date.
Standards for the basic oxygen process furnace (BOPF) were developed
first because the BOPF is projected to experience the greatest share of the
future growth in steel production. Electric arc furnaces (EAF) will also
participate in the growth. Steel production in open hearth furnaces (OHF),
however, is declining. These projected growth rates result from both increased
demand for steel and replacement of obsolete open hearth furnaces. Trends
in the production of steel from these three furnace types are shown in
Figure 1-2.^
A BOPF can produce much more steel in a shorter time than the other
types of furnaces. Because of this, most OHF's, which have relatively low
productivity, will be replaced by BOPF's. The BOPF is somewhat unique in
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IRON ORE
COAL*
COKE OVEN
LIMESTONE
BLAST
FURNACE
-^^
SLAG
OPEN HEARTH
FURNACE
HOT METAL
HOLDER
SCRAP
ELECTRIC-ARC
FURNACE
Figure 1-1. Flow diagram of an iron and steel plant.
CONTINUOUS CASTING
BILLETS
INGOTS
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100
80
60
c
o
c
o
40
- 20
c
o
•o
O
10
8
4J
62
I I I I I I ! I
64
66
68
Year
70
72
Figure 1-2, Production Trends By Type Of Furnace
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that it has no exterior source of heat. Consequently, a BOPF can only
be operated in conjunction with a blast furnace because 1t requires a
high percentage or molten pig iron as part of the charge. This limits
the amount of steel scrap that can be recycled, ihe availanility of large
quantities of scrap has made the EAF very attractive because it can
accept a charge that is all scrap. In fact, about 98 percent of the
(2)
steel produced by EAF's in 1971 was recycled steel scrap.v ' EAF's
are also particularly suited to production of alloy steels where only
small batches are needed.
In 1972, 23,721,000 tons of steel were produced in electric arc furnaces.
Of this, 69 percent was carbon steel, 24 percent alloy steel, and 7 percent
stainless steel. This accounts for 14 percent of the carbon, 41 percent
of the alloy and all of the stainless steel produced in all furnace
types.^ ' Production of steel In EAF's is projected to nearly double
from 1970 to 1980. In this same period, 150 new furnaces are expected
f3)
to be constructed.v '
Many finished products are produced from the steel made in electric
arc furnaces. The value or these products varies considerably. Table 1-1
shows some common carbon steel products and their price in 1972, In
general, alloy and stainless steels have a much higher value than carbon
steels.
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TABLE 1-1
PRICES OF MAJOR FINISHED CARBON STEEL PRODUCTS
(F.O.B. Mill Pittsburgh, dollars per 100 pounds)
Product
1972 Price
Plates
Steel Rods
Hot Rolled Sheets, 10 Gauge
Hot Rolled Sheets, 20 Gauge
Cold Finished Bars
Cold Rolled Strip
Hot Rolled Strip
8.15
8.80
8.36
9.31
11.50
10.94
8.15
REFERENCE: 1973 Metal Statistics, The American
Metal Market
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In 1972, the 299 EAF's in the United States were operated by 99
companies at 121 locations. Distribution of the furnaces by size is
shown below. '
Tons of Capacity Number of Furnaces
Smal 1 er
10
50
100
200
300
400
23
170
233
280
298
299
Larger furnaces are usually located in integrated steel mills. Many
of the smaller furnaces are in small plants that produce a limited variety
of products or small quantities of specialty steels.
Many of these furnaces are located in industrial urban areas of
Pennsylvania, Ohio, and Indiana. These States account for about 57
percent of all domestic steel production, Illinois and Michigan are
the next largest steel producing States,
No data were available on employment in EAF shops. However, about
478,000 employees "are engaged in the production and sale of iron and
steel products.^ ' Of course this figure includes many operations in
addition to production of steel in EAF's.
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Section m(b)O) of the Clean Air Act, as amended, requires that
the Environmental Protection Agency develop standards of performance for
sources which "... cause or contribute to the endangerment of public health
or welfare." The major pollutant from EAF's is particulate matter, a pollutant
for which ambient air quality standards were promulgated in 40 CFR 50.
In addition to the deleterious health effects, particulate matter emissions cause
soiling, reduction of visibility, and general nuisance. Iron and steel
plants were specifically mentioned in a report of the Committee on Public
Works, United States Senate, as a source category to which standards of
performance for new sources could be expected to apply. '
There are several sources of air pollutants in an EAF shop, however,
the vast majority of emissions are from the furnace, so it is the prime
candidate for standards of performance. Chapter V presents information
on the other sources.
B. Description of the Process
Electric arc furnaces are cylindrical refractory-lined vessels with
carbon electrodes suspended from above which can be lowered to extend
through the furnace roof (Figure 1-3). With the electrodes retracted,
the furnace roof can be rotated aside to permit the charge of scrap steel
to be dropped into the furnace. Alloying agents and slag materials
are usually added through the doors on the side of the furnace (Some
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CARBON
ELECTRODES
FURNACE
ROOF
THAT LIFTS
AND PIVOTS ROOF
CHARGING
SCRAP,
LIMESTONE,
AND LIME
FURNACE
O I /ALLOY At
_L_L\ ADD1T
L±=±jy '
ALLOY AND SLAG
ONS
SLAG
MOLTEN
STEEL
DESLAGGINGAND TAPPING
FIGURE i-3
ELECTRIC-ARC STEEL FURNACE
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smaller or older furnaces are charged through these.side doors.) Current
is then switched to the electrodes as they descend into the furnace.
The heat generated by the arc as it shorts between the electrodes through
the scrap, melts the scrap. The slag and melt are poured from the furnace
by tilting it.
The production of steel in an EAF is a batch process. Cycles or
"heats" range from about 1 1/2, to 5 hours to produce carbon steel and
from about 5 to 10 hours or more to produce alloy steel. Scrap steel is
charged to begin a cycle and alloying agents and slag materials are added
for refining. Each cycle normally consists of alternate charging and
melting operations, refining (which usually includes oxygen blowing),
and tapping.
C. Emissions
During a furnace cycle, both particulate matter and carbon monoxide are
evolved. The rate of particulate matter emissions varies considerably during a
furnace cycle. Most emissions occur during the early "melting" portion, although
significant quantities are also emitted during charging, tapping and oxygen
blowing operations. Literature references report evolution of up to 30
pounds of particulate matter per ton of steel produced;^ ?*>'*' ^ Infor-
.mation supplied by steel manufacturers on the quantity of particulate matter
collected by control devices suggest that 30 pounds per ton may actually
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be conservative-' for production of carbon steel and 15 pounds per ton
a more reasonable value for alloy steels.
Particulate matter emissions may also vary from cycle to cycle because
of several factors, some of which are:
a. Contamination of the scrap steel with dust3 oil, or volatile
metals will increase emissions during charging.
b. An increase in electrical power to a furnace will increase
emissions during the scrap melting.
c. An increase in the quantity of oxygen blown will increase
emissions during the blow.
Carbon monoxide is generated by reaction of the carbon electrodes
or carbon in the steel with the oxygen blown or with iron oxides. Much
of the carbon monoxide is oxidized to carbon dioxide as it leaves the
furnace. Limited data indicate carbon monoxide emissions can be as
high as 6 pounds per ton of steel produced. ' These emissions vary
considerably during a furnace cycle. Peaks are observed during scrap
melting when maximum electrical power is on and during oxygen blows.
• Information from six steel plants indicates a range in
uncontrolled emissions from production of carbon steel from 23
to 58 pounds per ton of steel production.
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- All States have general regulations that limit particulate matter
emissions and a few have regulations specific to EAF's. No regulations
for carbon monoxide emissions were found. More detail on the emissions
allowed by these State limitations is presented in Chapter IV.
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II. PROPOSED STANDARDS OF PERFORMANCE
A. Standards as Proposed
The proposed standards of performance would limit particulate matter
emissions to the atmosphere from electric arc furnaces and dust handling
equipment -as follows:
1. No more than 12 mg/dscm (0.0052 gr/dscf) of particulate matter
from the control device.
2. Less than 5 percent opacity from the control device.
3. No visible emissions from the building except for one minute
*-
per furnace in any one hour and as specified below.
4. No more than 20 percent average opacity during and as a direct
result of charging a furnace and for three minutes after completion
of the charge.
5. No more than 40 percent average opacity during and as a direct
' result of tapping a furnace and for three minutes after completion
of the tap.
6. If adjustable monitors in the roof of the building are closed
during a charge or tap, the allowable period of visible emissions
permitted in 4 and 5 above will start when the monitors are opened.
13
-------
These standards are the result of revisions from the levels presented
at the National Air Pollution Control Techniques Advisory Committee (NAPCTAC}
meeting on January 9, 1974. The levels presented to the Committee are
discussed in Chapter VIII of this report. The changes are:
1. Relaxation of the limitation on the concentration emitted from
a control device to 12 milligrams per dry standard cubic meter
(mg/dscm) from 9.0 mg/dscm [0.0052 from 0.0039 grains per dry standard
cubic foot (gr/dscf)].
2. A change in the visible emission limitation on the control device
to less than 5 percent opacity.
3. Incorporation of a short time exemption to the standard which
limits the visibility of emissions from the building housing the
furnaces.
4. Separation of the visible emission limitation on the shop during
charging and tapping into two separate standards: 20 percent average
opacity during charging and 40 percent during tapping.
5. Addition of a special provision to allow closing of select
monitors in the roof of the building during a charge or tap.
B. Discussionof the Concentration Standard
At the January 9 NAPCTAC meeting, available emission data indicated
that a 9 mg/dscm (0.0039 gr/dscf) standard could be easily achieved. These
-------
data were supported by a vendor guarantee of 0.004 gr/dscf on fabric filters
at three building evacuation systems at three similar shops. These shops,
owned by one company at one location, produce alloy steel. Another vendor
had also signed a statement that he would guarantee 0.004 gr/dscf on a
system planned for the capture of charging and tapping emissions at a
plant which produces carbon steel. (Emissions during the remainder of the
process cycle at this plant are captured by an existing control system.)
In correspondence to the operator of this plant, two other vendors
stated that 1) although 0.004 gr/dscf was achievable they would not guarantee
it and 2) they would guarantee 0.004 gr/actual cubic foot, approximately
equivalent to 0.005 gr/dscf (see Chapter VI for a more detailed description
of these guarantees). All of these guarantees were for fabric filters
designed to treat large volumes of exhaust gas with low concentrations of
particulates. Industry representatives at the meeting and at least one
member of the NAPCTAC commented that the 0.0039 gr/dscf level was too stringent
for the industry to meet at all times. The industry representatives suggested
the limitation be 0.008 gr/dscf.
Since the meeting, information on another guarantee has been obtained.
A vendor has guaranteed to achieve no visible emissions from a fabric filter
controlling a direct shell evacuation system with a relatively high inlet
concentration of particulate. This guarantee somewhat indirectly implies
by the following quote that 0.005 gr/dscf is a reasonable level to guarantee;
"In the event tests are necessary to determine compliance with the invisible
15
-------
discharge requirement, a concentration of 0.005 grains/scf or less at the
baghouse waste gas discharge shall be considered invisible." The guarantee
further specified that the tests would be conducted with multiple high-
volume samplers in the roof monitor on the fabric filter.
Considering this additional information, it is the Administrator's
judgment that the concentration standard be changed to 12 mg/dscm (0.0052
gr/dscf). Raising the standard to this level will not relax the design
requirements of the control devices installed to meet the standard. It
will allow a greater buffer which many vendors and plant operators claim
necessary to insure the recommended standard can be met at all times with
a well designed and maintained control device.
C. Discussion of Opacity Standard on the Control Device
Opacity restrictions are promulgated concurrently with most particulate
matter standards to provide a readily enforceable means of maintaining
standards of performance. The opacity restrictions are selected such that
a violation of the opacity standard almost certainly assures that the
particulate matter standard is also being exceeded.
Although no quantitative data are currently available, the threshold
of visibility for emissions from electric arc furnaces is estimated to be
from 0.01 to 0.03 gr/dscf^. Since the proposed standard is only 0.005 gr/dscf
or at least 50 percent below the threshold for visible emissions, the opacity
restriction has been changed to prohibit any visible emissions.
-'This estimate is based on information from control equipment manufacturers.
News Focus, JAPCA, 23(7): 608(1973).
-------
D. Discussion of thi Opacity Standards pn_jtheBut]ding
An opacity limitation on the emissions from the shop which houses the
furnaces was proposed to assure that emissions from the furnace are captured
by the control system. At the January 9 meeting, data were not yet available
to specify limits for these standards. These data are discussed in Chapter
VI of this report.
Three separate visible emission standards are proposed for the shop.
Three standards are necessary because the efficiency of a DSE-CH control
system varies with the various operations during a process cycle. The
standards will apply during 1) charging, 2} tapping and 3) the remainder
of a process cycle. Each of these is discussed separately below.
A time exemption of "one minute per electric arc furnace in any
one hour" was added to the "no visible" limitation at times other than
charging and tapping. This exemption will permit emissions during furnace
"cave-ins" or additions of iron ore or burnt lime through the slag door.
These can cause short bursts of emissions which a DSE-CH system cannot
always contain. A 30 second period of emissions observed at Plant M was
probably caused by a "cave-in," however, a positive identification of the
cause could not be made.
"Cave-ins" occur when a "bridge" of scrap in the furnace falls into
a molten pool of steel. When the electrodes are dropped and power to
the furnace is turned on after a scrap charge, the hot electrodes "bore"
holes in the scrap until a molten pool forms at the bottom of the furnace.
17
-------
The scrap pile then melts from the bottom up. At some point the "bridge"
of scrap that forms as the scrap near the bottom of the furnace melts,
collapses. As the cold scrap hits the hot molten steel, a rapid evolution
of gas and fume occurs due to chemical reactions and volatilization of . .
moisture, oils or dirt on the scrap. The resultant sudden increase in
gas volume overloads the DSE system and causes the emissions to escape-
the furnace. The larger of these bursts of emissions are not entirely
contained by CH's and they escape the shop as a visible emission from
the building roof.. Industry representatives claim that a similar situation
results from addition of iron ore or burnt lime to a furnace. Data have not
been provided to substantiate this.
A time exemption of one minute per furnace in any one hour was judged
sufficient to allow for the emissions described above. The relation of -
the exemption to the number of furnaces in a building is provided since
the potential for these emissions is directly related to the number of
furnaces. In lieu of an hourly exemption, one based on the length of a
furnace cycle was considered. However, this would require more field time
and place a larger burden on enforcement.
An allowance for emissions during charging and tapping is also provided
by the standards. The magnitude of tapping emissions is much greater
than that for charging, as the data in Chapter VI show. For this reason
two different limitations are proposed instead of a single one for both
charging and tapping. The limits proposed, based on the available data,
are not to exceed 20 percent average opacity for charging and 40 percent
for tapping.
18
-------
Some operators of new plants may opt for a control system with"adjustable
louvers on the roof monitors. The monitors can then be closed during
charging and tapping and later reopened to permit natural ventilation of
the building. This can increase the effectiveness of the capture system.
The emissions that initially escape the CH and are contained below the roof
of the building during peak evolution from the furnace can be drawn into
a scavenger opening in the ductwork from the CH. This system could be
expected to be only partially effective and some visible emissions may still
•be emitted after the monitors are opened. A special provision in the regu-
lation is needed for this system. It will allow emissions for the same
length of time as other cases but will delay the start of the allowable
period until the louvers on the roof monitors are opened.
The standard of performance is not designed to require this type of
monitor system because the staggered furnace cycles in a shop with many
furnaces would force it to keep the roof monitors closed most of the time.
The staggered cycle would result in at least one furnace being charged or
tapped at any particular time. The result would essentially be a building
evacuation system, which has been determined not the most desirable control
system for reasons given in Chapter VIII. However, a system which
permits selective closing of the roof monitors should be considered in any
new installation since it can result in better control of air pollution.
19
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Page Intentionally Blank
-------
III. EMISSION CONTROL TECHNOLOGY
In addition to achieving compliance with air pollution control
regulations, air pollution control systems for electric arc steel
furnaces must also meet other criteria. They must:
. Be compatible with processes used to make many types of
steel.
. Not prevent attainment or maintenance of a healthful and
acceptable work environment for employees. Control of pollution
generated within the shop is inextricably affected by the
ventilating air system and vice versa.
. A control system which minimizes ambient air pollution can
result in increased concentrations within the work area. Such
increases in particulate would not only endanger the respiratory
health of employees, but also decrease visibility thereby
increasing the opportunity for serious operating errors with their
attendant risk of injury.
. Such effects of air pollution control might also manifest
themselves as restricting ventilation air, thereby increasing the
possibility of serious injury through heat stress.
Several systems are used to control air pollution in the industry
and to meet these additional criteria. The major difference between
21
-------
these systems is the method(s) used to capture the dust emitted by the
furnaces. The capture systems are described below.
A. Direct Shell Evacuation System in Combination With NaturalVentj1ation
through the Open Roof{SeeFTgure Ill-l)
The direct shell evacuation (DSE) system withdraws all potential
emissions directly from within the furnace before they escape and
are diluted by the ventilation air. A water-cooled duct which extends
through the furnace roof is jointed near the furnace with a gap of
one to several inches separating the ends. This separation permits
the furnace roof to be elevated and rotated aside to permit top
charging and tilting of the furnace for tapping and slagging. (During
such timess DSE systems are ineffectual and emissions rise directly
through the roof of the shop.) A few DSE systems remain in operation
while the furnace is tilted. The incremental improvement in the capture
of emissions is very small, however, because the bulk of tapping and
slagging emissions are from the ladle or slag pot. During operation,
the DSE system maintains a negative pressure within the furnace. As
a result, air is drawn into the furnace around the electrodes and
through the gap into the exhaust duct. This air not only cools the
exhaust gas, but it permits combustion of the large amounts of carbon
monoxide present.
22
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BUILDING
MONITOR
%TAPPINGltf3
EMISSION'S t$
rs-T
FURNACE
c
O
CLEAN AIR
EXHAUST GAS
DSE
FABRIC FILTER
00
Figure 111-1. '.Direct shell evacuation (DSE) system open roof.
-------
More carbon monoxide is oxidized to carbon dioxide in this
manner than from furnaces without DSE. Certainly some of the
carbon monoxide that evolves from the annular spaces around the
electrodes in furnaces which do not have DSE is also oxidized
as the gases contact ambient air. In this case, however,
the gases are rapidly cooled and diluted. This limits the degree
of combustion achieved. The DSE system achieves more complete
combustion because the exhaust gases are not so quickly diluted
and they mix with oxygen at a high temperature for a longer period
of time. Combustion of carbon monoxide is now incidental to
the design of DSE systems. Much lower emission levels may be
achieved if future systems are designed to maximize the combustion
of CO,
The most commonly used device to clean the gas after capture
is fabric filters, but venturi scrubbers and electrostatic
precipitators are also occasionally used. If the control device
is a fabric filter, the hot furnace gas must first be cooled by
water sprays, radiant coolers, dilution air or some combination
of these to prevent degradation of the fabric. If a precipitator
is used, the gas is humidified to maximize the efficiency of the
precipitator. Only the scrubber does not require any special
treatment of the exhaust gas.
A well designed and operated DSE system is desirable not only
because it can capture essentially all the dust generated during
24
-------
meltdown and refining (including emissions during the oxygen blow),
but also because it inherently restricts the gas volume which must
be cleaned, thereby maximizing removal efficiency with minimal
energy requirements. Unfortunately, as mentioned earlier, DSE 1s
totally ineffectual when the furnace is being charged or tapped.
During these periods, emissions billow to the roof. If the roof
is open, they exhaust directly to the atmosphere in a very visible
pi urae.
The DSE system has a second favorable effect on the worker's
environment. It contains and exhausts a considerable part of the
heat generated in the furnace which would otherwise escape into
the building. In combination with natural ventilation through
the roof, DSE generally maintains an acceptable working environ-
ment in a shop.
In summary, any new furnace for production of carbon steel
(except perhaps extremely small ones) would almost certainly be
equipped with a DSE system for two reasons. First, because of
its excellent capture efficiency and second, containment of the
pollution within such low gas volumes minimizes the Investment
required for the cleaning equipment.
25
-------
Unfortunately, the DSE cannot be used in the manufacture of all
steels. During the production of some alloys, a second slagging
operation takes place. A "reducing" slag is used to remove impurities
from the melt. Air will oxidize these slags and render them
ineffectual. At such times, induction of air into the furnace is
intolerable. Although it would appear that the fan on the DSE system
could be turned off when the "reducing slag" is in the furnace, the
industry advances a theory that the configuration of the furnace roof
which is required to accommodate the DSE system interferes with the
required temperature homogeneity of the melt. The absence of refractory
where the discharge duct enters the roof is alleged to act as a "black"
surface which absorbs radiant heat from the melt and results in a cold
spot in the molten steel.
B. Building Evacuation in a Shop With a Sealed Roof
(See Figure II1-2)
With the building evacuation system (BE), the entire building
is used to capture dust from the furnaces. Hot exhaust gases
containing dust billow to the roof of the shop where they are
drawn into ducts to a fabric filter. Although the removal
capacity of the duct may be less than the furnace release rate,
the dust-laden gas will accumulate beneath the sealed roof during
26
-------
CLEAN AIR
v HS^> EXHAUST GAS
-v Ir
Figure fll-2. Building evacuation (BE) system closed roof.
-------
periods of high dust generation. Since 1t cannot escape except
through the control device. It does not create a pollution problem.
Since all ventilation air must exhaust through the control
device, operating costs have limited these systems to fabric
filter collectors. Gas cooling systems have not been necessary
because the ambient air drawn Into the building mixes with and
cools the dust-laden gases.
In two aspects, BE systems appear to be superior to DSE systems,
They capture fumes from the charging and tapping operation, and they
operate without any visible emissions from the building. They
also have no effect on "reducing slags" and are often the choice
of shops that produce alloy steels.
C. Canopy Hoods 1n a Shop With a Sealed Roof (See Figure KU>3)
The canopy hood (CH) system 1s very similar 1n principle,
operation, performance, and applicability to the building
evacuation system. Instead of using the building roof, however,
a canopy hood is suspended directly above each furnace. Since
these hoods must not restrict movement of the crane which charges
raw materials to the furnaces, they must allow 30 to 40 feet of
clear area Immediately above the furnaces. (Furnaces which are
charged through doors 1n the side or fed through a chute do not
28
-------
FURNACE
o
A
n_
CLEAN AIR
EXHAUST GAS
FABRIC
FILTER
NJ
ID
Figure 111-3. Canopy hood (CH) closed roof.
-------
require this free board and hoods can be built nearer the furnace.
Unfortunately, side charging 1s too slow and continuous feeding
systems have not been perfected.)
During charging, the fumes rapidly rising from the furnace are
often deflected from the hood by the crane and its charging bucket.
Cross drafts within the building and large fluctuations in emissions
that sometimes exceed the capacity of the hood also cause a great
deal of dust to bypass the hood. Since the building is sealed, fume
not captured 1n the hood accumulates in the upper part of the building
and 1s gradually removed through appropriate "scavenger" openings
In the ductwork for the CH system.
Canopy hoods are sometimes divided Into sections 1n an attempt
to improve their efficiency. Dampers are used to maximize draft
directly above the point of greatest emissions during charging,
tapping or slagging operations.
D. Canopy Hoods in Combination With Natural Ventilation Through
the Open Roof (See Figure Til-4)
The canopy hoods (CH) are identical to those described
previously, but in these shops the roof monitors allow natural
ventilation to augment ventilation which results from the hood
suction. Unfortunately, they also allow any fume which bypasses
the hoods to escape the building as a very obvious visible
30
-------
BUILDING
MONITOR
CLEAN AIR
> EXHjfiUST GAS
Figure 111-4. Canopy hood (CH) open roof.
-------
emission. A1r flows through canopy hoods in this type of system
are quite high, but less than required with a sealed roof. Only
fabric filters are known to be used with this system.
E. Combinations
1. Direct shell evacuationIn a shop with either1) building
evacuation or 2) canopyhoods and a sealed roof.
The union of these two systems combines the advantages of
both. The DSE unquestionably provides the best control during
meltdown and refining and either of the other systems (canopy
hoods or building evacuation) captures emissions during
charging and tapping. The air flow to the canopy hoods or
various strategically located- Inlets to building evacuation
ducts can be shifted as ventilation requirements and emissions
of dust from different furnaces dictate. Separate control
devices can be used or a single one can serve both systems.
This combination requires lower average air flow rates than
a canopy hood or building evacuation system alone because fewer
emissions are released Into the shop building and part of the
heat load is removed by the direct shell system. However, the
air flow must still be quite high to assure adequate ventilation
and an acceptable working environment. Peak air flow rates are
32
-------
used for the building evacuation or canopy hood system
during charging and tapping when the DSE system 1s Ineffectual.
At other times these peak flows can be reduced.
The earlier discussion of the DSE system and the capability
of sealed roof systems to preclude visible emissions also
applies to this combination of systems.
2. Direct shell evacuationin a shop with canopy hoodsand
natural ventilationthrough theopen roof.
This combination .is identical to the preceding with one
notable exception; the open roof monitors permit natural
ventilation. Because the open roof will satisfy ventilation
requirements, continuous air flow through the canopy hood is
not required. As a result, the hoods can be operated on
demand to capture charging and tapping emissions.
Any fume not captured by the hoods will escape as a visible
emission through the open roof monitors. Shops with many
furnaces which have staggered charging and tapping cycles will
probably have visible emissions through some portion of the
roof monitors much of the time.
33
-------
Such losses can be minimized. Louvers on the openings in
the roof can be automated to close during periods when the
DSE is out of service to preclude emissions from the shop
of fumes which may bypass the canopy. "Scavenger" openings
in the exhaust ductwork of the canopy hood could extract the
fume that is trapped in the roof. Such a system will probably
not eliminate all visible emissions as some fume will still be
trapped in the roof when it is reopened for ventilation. Also,
in a shop with many furnaces where many charges and taps occur,
the louvers may have to be closed most of the time. The system
would then approach a BE system.
Because the forced ventilation is supplemented by natural
ventilation, this combination system requires less forced air
flow, hence demands less energy, than systems with a sealed roof
on the shop.
F. General Discussion
A totally new concept for containing air pollution from electric
arc furnaces has been developed for a shop that is scheduled to start
construction in early 1974. The shop will produce carbon steels in two
furnaces with 200 tons of capacity each. ' The furnaces are equipped
With conventional DSE and CH systems. The major innovations are:
1) enclosures around each furnace that act as chimneys to direct
charging fumes up into the CH's and 2) hoods that will capture emissions
from the tapping ladle and slag pot. The shop roof will be closed
above and between the two furnaces. Figure III-5 shows these new concepts.
-------
w
tn
DERATING FLOOR
SLAG POT"
FigureJII -5 New system for capture of emissions from electric arc furnaces.
-------
The enclosure around the furnace 1s designed to restrict and direct
the charging emissions to the canopy hood but stnI allow the crane to
travel between the hood and the furnace to permit the charging bucket
to be positioned over the furnace. The enclosure is much larger than
the furnace. It allows the furnace roof to swing open and extends
over the tapping area where 1t can capture emissions from the pouring
spout or any fumes that bypass the tapping hood.
In anticipation of initial problems in training the crane operators,
the enclosure walls will be built to permit easy replacement when
damaged. The enclosure will partially protect the integrity of the
emission plume from cross drafts 1n the building as 1t rises to the CH.
Although cross drafts may still cause some disturbance of the plume
before it reaches the CH, its capture efficiency will certainly be
improved.
The most significant advance in technology embodied in this new
system is the use of a stationary hood that fits close over the tapping
ladle. The empty ladle will be moved by crane to a rail car which 1s
rolled under the hood. Molten steel will be poured into the ladle
through an opening in one side of the hood. This type of hood cannot
presently be used on electric arc furnaces because the crane cables
Interfere with placement of a hood. Industry has been reluctant to
part with the traditional method of tapping where the crane holds the
ladle and lowers 1t as 1t fills to minimize the freefalI distance of
molten metal. A longer stream allows more heat and product loss by
36
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oxidation. This concern was compromised by the designer of the new
system to achieve better air pollution control.
The new system also has a stationary hood over the slag pot through
which the slag drops. (Although slagging Is a minor source of emissions,
the hood will provide some improvement 1n their control.)
The total air flow design for this system 1s 630,000 dry standard
cubic feet per minute idscfm) or i600 dscfm per ton of furnace capacity.
This 1s about the same as used for conventional DSE-CH systems 1n shops
with open roofs. This system combines the lower cost and energy
requirements of a DSE-CH system with the higher capture efficiency of
systems with high air flow rates. Although this new system will
certainly achieve better control than existing CH systems, the exact
level cannot be quantified until the system 1s operational.
Tapping hoods that fit close over a ladle have been very effective
1n other metallurgical Industries. Either a retractable hood or a
ladle mounted on a rail car allow close hooding.
It 1s difficult to compare the effectiveness of these air pollution
capture systems. Because of the many variables Involved, their
measurement has been very limited and the difficulty of making such
measurements 1s Imposing. These variables Include the capture
efficiency of hoods and DSE systems, the rate of air flow for the
control system, and the particulate concentrations out of the control
37
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device. Estimates of emission rates for the various systems are
extremely sensitive to the values assumed for any of the variables.
TableIII-l was developed to show the effect of the type and
capture efficiency of a control system on emissions from an alloy and
a carbon steel shop equipped with furnaces of comparable size. The
carbon steel shop produces an average of 86 tons of steel per hour,
the alloy steel shop produces only 43 tons of steel per hour. The
difference in production rate is a consequence of the heat length which
1s about twice as long in an alloy shop. The calculations are based
on the following:
. Uncontrolled emissions are 30 pounds of particulate per ton
of carbon steel produced and 15 pounds per ton of alloy steel.
. Charging and tapping emissions are 10 percent of the total
or 3.0 and 1.5 pounds per ton respectively for carbon and alloy
steel. (They have been estimated at 5 to 15 percent of the
total.^12))
. A DSE system cannot be used in the alloy shop.
. Particulate concentrations from the control devices are based
on data obtained by EPA and industry.
. Air flows through the control devices are based on data provided
by Industry. These data are presented in F1gureIII-6.
38
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Table III-l. Calculated Emissions From
Electric Arc Furnace Shops With
Various Control Systems
Type of
Sys tern
Uncontrolled
70% efficient
canopy hoods,
open roof
80% efficient
canopy hoods,
open roof
901 efficient
canopy hoods,
open roof
Building evacua-
tion or canopy
hoods with closed
roof
Direct shell evacua-
tion only, open
roof
Direct shell evacua-
tion and 701
efficient canopy
hoods, open roof
Direct shell evacua-
tion and 80%
efficient canopy
hoods , open roof
Direct shell evacua-
tion and 90X
efficient canopy
hoods, open roof
Direct shell evacua-
tion and building
evacuation or canopy
hoods, closed roof
Average
Control
System
Air Flow,
sdcfm
per ton
of fur-
nace
capaci ty
-
2500
2500
2500
5000
350
2000
2000
2000
4000
Parti cu-
late
Concen-
tration
in Con-
trol
System
Exhaust,
gr/dscf
-
0.003
0.003
0.003
0.003
0.005
0,003
0.003
0.003
0.003
Emissions
Carbon Steel
Shop, 300 tons
furnace capacity,
3 1/2 hr. aver-
age heat time,
85 ton/hr pro-
duction
Ib/hr
2580
-
-
-
_
263
92.8
67.0
41.2
30.9
Ib/ton
30
-
-
-
-
3.05
1.08
0.779
0.479
0.359
Alloy Steel Shop
300 tons furnace
capacity,
7 hr. average
heat time,
43 ton/hr pro-
duction
Ib/hr
645
213
149
84.0
38.6
_
_
_
_
-
Ib/ton
15
4.95
3.47
1.95
0.897
-
-
-
-
-
39
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o
8000
7000
00
5000
am.
.
o i.
ce oj
ou_
oo
3000
2000
1000
COLLECTION SYSTEMS
DSE-DIRECT SHELL EVACUATION
CH- CANOPY HOOD
BE- BUILDING EVACUATION —
PLANT
G
CH
H
CH
B
CH
BE
BE
J
BE
K
BE
TYPE OF COLLECTION DSE DSE DSE DSE DSE
SYSTEM -fCH -4-CK +CH +CH 4CH
MAJOR TYPE OF CARBON CARBON CARBON CARBON CARBON ALLOY ALLOY ALLOY ALLOY ALLOY ALLOY ALLOY
STEEL PRODUCED
SHOP ROOF OPEN OPEN OPEN CLOSED CLOSED PARTLY CLOSED CLOSED CLOSED CLOSED CLOSED CLOSED
CLOSED
Figure III -6. Control system air flow rates for electric arc furnaces.
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Notes for Figure III-6 *•-
Plant C - The roof monitors at this plant are closed during charging
and tapping and for a short period after these operations,
and are opened at other times.
Plant F - Roof monitors at this plant are opened for ventilation 1n
the summer and when necessary to clear dust from the shop
atmosphere. They are generally closed 1n the winter.
Plant 6 - Roof monitors at the ends of the shop building are open, but
partitions 1n the roof trusses Isolate the open monitors from
the furnaces sufficiently to consider this a closed-roof shop.
Plant E - A1r flows are design values for a system under construction.
Design of the shop 1s similar to"Plant G.
Plant L - This shop 1s 1n two sections. One section with a. lower
roof has open monitors and the other section 1s closed.
Furnaces are in both sections.
Plant H - The roof monitors are equipped with motorized louvers, but
they are generally closed.
Plant B - Furnaces are in two separate buildings,,, but one control
system is used.
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The most common collection device used with the capture systems
described above is the pressurized fabric filter which normally has
an open top or "monitor" discharge. This type, which has no exhaust
stack, is cheaper than closed filters. Although fabric filters are
commonly used regardless of the type of capture device, they are used
exclusively with those systems that require large air flows.
The design air flow rate for a fabric filter is directly
proportional to the level of mass 'emissions achieved. Higher design
flows result in lower inlet concentrations; however, the outlet
concentration remains relatively constant. One reference reports that
a "fabric filter might well operate with the same outlet concentration
Cl3\
when the inlet loading changed tenfold. ' Since mass emissions are
a product of the concentration and air flow rates, minimizing air flow
will minimize emissions.
Control of visible emissions from unloading of dust collected by a
fabric filter can be achieved with a closed system by pneumatically con-
veying the dust to a closed truck which is vented to the inlet of the
fabric filter.
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IV. ENVIRONMENTAL EFFECTS
A. Impact on Air Pollution
Table III-l presents partieulate matter emission rates for the various
control systems discussed in Chapter III. Using values from that table,
Table IV-1 shows the reduction from uncontrolled particulate matter emission
rates each system can achieve. Reductions in carbon monoxide (CO) emissions
(based on data presented in Chapter VI) are also shown.
The objective of standards of performance under section 111 of the
Act, as amended, is to prevent new air pollution problems from developing
by requiring affected facilities to use the best systems of emission
reduction available at a cost and within a time that is reasonable. These
standards pertain directly to emissions and are only indirectly related to
ambient air quality. Attainment and maintenance of national ambient air
quality standards is specifically covered by State implementation plans as
provided under section 110 of the Act. Nevertheless, the impact of a new
electric arc furnace on local ambient air quality should be closely investigated.
Such an investigation necessarily depends upon many specific factors such
as topography, meteorological conditions, proximity of other sources of
pollution and the mass of pollutants emitted from all sources in the local
area. As an illustrative example, maximum ground-level concentrations of
particulate matter and CO were estimated for emissions from a hypothetical
source employing the control devices of interest using an atmospheric
dispersion model. These estimates are shown'in Table IV-2.for these
-------
TABLE IV-1
Reduction in Uncontrolled Emissions From Electric Arc
Furnaces For Various Control Systems
Type of System
80$ efficient canopy
hoods, open roof
Building evacuation
or canopy hoods,
closed roof
Direct shell evacuation
only, open roof
Direct shell evacuation
and 80% efficient
canopy hoods, open roof
Direct shell evacuation
and building evacuation
or canopy hoods,
closed roof
Percent Reduction in Emissions
Carbon Steel Production
Parti culates
-
-
89.8
97,4
98.8
Carbon
Monoxide
-
_
84
84
84
Alloy Steel Production
Parti culates
76.9
94.0
„
_
„. .
Carbon
Monoxide
none
none
n
_
P*.
-------
TABLE fV-2. Estimated Ground-Level Paniculate and
Carbon Monoxide Concentrations Resulting From
Electric Arc Furnace Snops at Various Downwind Distances
Total Control Source(s) of Emission Pollutant Emission Aver-
Furnace System
Capacity
-once<.tra>,icn at Specified uistance
Kate, aging from Source, mg/ra3 for CJ, uq/m3
g/sec. Tiroes for particulate
VUliO/ tIC
100
400
1250
100
400
1250
300
4JO
1250
100
400
1250
100
400
1250
a u
BE
BE
BE
USE
bSE
USE
BE
BE
BE
bSE-tri
OSE-CH
USE-CH
USE
uSE
USE
Baghouse with
Monitor Discharge
Baghouse with
Monitor in sen. < -
Baghouse with
Monitor Discharge
Baghouse with
Monitor Discharge
Baghouse witn
Monitor Discharge
Saghouse with
lionitor Discharge
Baghouse with
Monitor uiscnarge
Bagnouse with
Horn tor Discharge
Baghouse with
Monitor Discharge
SagiiO'Jso and Shop
BUI lt.iny
"onitor lis charges
on Baghouse and Shop
Building
Monitor Discharges
on Baghouse and Shop
Building
Monitor Utscharges on
Baghouse and Shop
Bui Jding
Monitor discharges
on Baghouse and Shop
Building
CO
CO
CO
CO
CO
CO
Parti-
cu late
Parti-
culate
Parti -
culate
Parti-
culate
»arti-
cu 1 ate
Parti-
culate
Parti -
culate
Parti-
culate
14
57
180
C.6
26
33
1.3
5.2
16
2.8
11
35
11
44
Monitor Discharges on
Baghouse and Shop
riui Iding
Parti -
culate
142
1 hr
8 hrs.
1 hr.
8 hrs.
1 hr
8 hrs.
1 hr.
8 hrs.
1 hr.
& hrs.
1 hr.
8 hrs.
24 hrs.
1 yr.
24 hrs.
1 yr.
24 hrs.
1 yr.
24 hrs.
1 yr.
24 hrs.
1 yr.
24 hrs.
1 yr.
24 hrs
1 yr.
24 hrs
1 yr.
24 hrs.
1 yr.
C km.
20
20
40
40
70
70
30
30
60
60
90
90
2000
200
6000
700
11000
1500
1000
140
3000
400
5(JQO
600
4000
600
12000
1500
20000
2000
0.3 tar
4
3
15
10
35
25
2.5
2
9
6
25
20
300
30
1000
120
3000
400
300
30
1100
120
4000
400
1100
120
4000
500
14000
1600
2.0 km.
0.4
0.3
1.8
1.3
6
4
0.2
0.2
0.8
0.6
2.5
2
20
2
100
10
300
30
40
4
160
15
500
50
160
15
700
60
2000
200
20 kit.
0.03
0.02
0.1
0.1
0.4
0.3
0.02
0.01
0.06
0.
-------
hypothetical point sources - control device cases. Differing source
configurations and surrounding terrain can cause significantly different
results. The maximum concentrations were estimated for 24-hour and 1-year
averaging periods for particulate matter and for 1-hour and 8-hour averaging
periods for CO. These averaging periods were selected to permit direct
comparison with the respective ambient air quality standards. Comparison
of these maximum ground-level concentration estimates with the national
ambient air quality standards will not necessarily indicate whether or not
these standards (NAAQS) will be met unless there is an estimate of back-
ground concentration arising from natural and manmade sources available
for the specific site.
The dispersion analysis considered the effect of aerodynamic downwash
because the pollutants typically emit from a monitor (no stack)on the
control device or a building and thus aerodynamic downwash is likely to
be a chronic problem. Aerodynamic downwash will most likely be a problem
for wind speeds exceeding 2 or 3 meters per second (mps). At lower wind
speeds, the effluents studied generally would not be affected by downwash.
The CO concentration estimates were made through application of a
dispersion equation {ASME Guide for the Prediction of the Dispersion
-------
of Airborne Effluents, Equation IV-8) that considers aerodynamic
downwash close to the source as well as Gaussian dispersion further
downwind. For the zero and 0.3 kilometers downwind distances on
Table IV-2, stability D and a wind speed of 3 mps were assumed. That
was the downwash condition likely to result in the highest 1 and 8 hour
concentrations at those distances. At 20 kilometers, stability E and
a wind speed of 2 mps were assumed. Those values were chosen based on
the results of an analysis using a point source Gaussian dispersion model.
At the 2 kilometer distance, intermediate values of the stability
parameter and wind speed were used.
The particulate dispersion estimates were made through application
of a Gaussian point source dispersion model recently developed by the
Meteorology Laboratory of EPA. The model generates, for any given year,
maximum 1-hour, 24-hour, and annual ground-level concentrations.
Downwash primarily affected the results of the dispersion calculations
for both CO and particulate matter at zero and 0.3 kilometers, and
had little or no effect at 2.0 and 20 kilometers.
Since many of the facilities under consideration in this
study are located in valleys in Pennsylvania and Ohio for the par-
ticulate dispersion estimates, it was necessary to use meteorological
data representative of the dispersion conditions in such
-------
locations. Hourly surface stability-wind data for a one year period
from Harrisburg, Pennsylvania, were determined to be appropriate.
Table 1V-2 shows that at the zero distance the national ambient
air quality standards (NAAQS) (noted at the bottom of the table) may
be exceeded in most cases. In some cases (primarily particulate concen-
trations), the NAAQS may be exceeded at greater distances. Since the
dispersion calculations result in maximum, time-averaged, ground-level
concentrations for adverse meteorological and topographical conditions,
the concentrations in Table IV-2 do not represent typical values.
Ground-level concentrations may exceed the 1-hour and 8-hour NAAQS for
CO several times per year, and the 24-hour average ground-level particulate
concentrations may be considered typical high values during any given
year.
The reductions estimated in Table IV-1 are based on rates from uncontrolled
furnaces. However, very few furnaces in the United States now have no control
device. The true environmental benefit of a standard of performance is the
reduction over average control already required by State and local regulations.
This average level of control is very difficult to derive since those agencies
use many different types of regulations. However, a comparison can be made
with particulate regulations of those States which contain relatively large
numbers of EAFs. (Carbon monoxide emissions do not appear to be regulated
by any State or local agency.) This comparison is made in Table IV-3 for
the various control systems that the alternative standards in Chapter VIII
-------
Table IV-3
Comparison of Emissions Allowed By State and Local Regulations
And Emissions From Various Control Systems
Regulations
Illinois-process
weight regulation
Indiana-process
weight regulation
Los Angeles County-
process weight regulation
New York-process
weight regulation
Ohio-collection
efficiency regulation
Pennsylvania-
concentration
regulation
Texas-process
weight regulation
Control Systems
80% efficient
canopy hoods , open
roof
Building evacuation,
closed roof
Direct -shell evacuation
and 80% efficient
canopy hoods, open roof
Direct shell evacuation
and building evacuation
or canopy hoods, closed
roof-
Emissions, pounds per hour
Carbon Steel Production9
29
46
21
55
50
206C
94
-
-
67
31
Alloy Steel Production
20
43
17
47
37
257C
76
149
39
-
—
Based on 300 tons of furnace capacity and a 3.5 hour cycle.
DBased on 300 tons of furnace capacity and a 7 hour cycle.
"For a concentration regulation the mass rate of emissions is dependent on the
flow rate of exhaust gas. Values were calculated for 4000 and 5000 standard
EQbic feet per minute per ton of furnace capacity for carbon and alloy steel
production respectively.
49
-------
would require. The regulations shown, although not specific tor EAF's, are
the more stringent ones for those localities where the most furnaces are
operating. The comparison is for shops with 300 tons of furnace capacity.
Most of the regulations are based on process weight curves which are pro-
gressively more stringent for larger plants. Therefore, the comparison will
vary with the size of a shop. To show this more clearly, Figure III-l presents
allowable emissions for the Illinois regulation as a function of capacity
of the furnaces. Superimposed on that curve are curves showing estimated
emissions from two alternate control systems for a shop producing carbon
steel. Notice that the process weight curve is very stringent for large
shops (about 55 Ib/hr for a shop with 1000 tons of furnace capacity).
The alternative standards in Chapter VIII are based on existing technology
(the control systems shown), for which emissions are estimated as 100
and 220 Ib/hr.
Wisconsin and Michigan have regulations which are specific for electric
arc furnaces. They limit emissions to 0.10 and 0.20 pounds of particulate
per 1000 pounds of exhaust gas, respectively. These limits are approximately
equivalent to 20 and 40 pounds per hour for a direct shell evacuation-building
evacuation (DSE-BE) system on a 300 ton shop producing carbon steel or 25
and 50 pounds per hour for a BE system on a 300 ton shop producing alloy steel.
The effect of these regulations cannot be directly compared to emissions from
control systems with open roof monitors on the shop, since the rate of gas flow
through the monitors is not known.
50
-------
Process weight, Ib/hr
[ I a i
_L
10 50 100 300 500 1000
Tons of furnace capacity
Figure "IV-1
Comparison Of A Process Weight Regulation With
Estimated Emissions From Two Control Systems
-------
Nor is it known how any of these State or local regulations will be
enforced for facilities with an open roof on the shop, since no technique
for measuring emissions from roof monitors is specified. Such techniques
are complex requiring either an inordinate number of sampling personnel
or a built-in multipoint sampling system. It is"possible the regulations
may be applied only to emissions from the control device. In this case,
compare the allowable emissions with emissions from the control device
of 19 Ib/hr for an 80 percent efficient canopy hood (CH) on an alloy
shop and 15 Ib/hr for DSE and an 80 percent efficient CH on a carbon
shop. All emissions for the BE system, as shown on Table IV-3, are
emitted from a control device.
Many States also have general visible emission limitations of 20
percent opacity. BE systems can achieve these regulations easily, however,
existing open roof systems may not be able to comply during charging and
tapping operations even if CH's are used. These visible emissions may
last longer than the two or three minute exemption some States have.
From the above comparisons, one may conclude that standards of perfor-
mance which require use of BE or CH-DSE systems will have little impact
on those States that presently have strict particulate regulations. However,
the standards and their supporting documentation, based on "best demonstrated
technology," will provide valuable guidance to State and local/(governments,
and industry on the capability and techniques of available technology.
52
-------
Installation of systems representing best air pollution control
technology on all new plants will minimize the increase in emissions from
growth of the steel industry. The standard of performance will negate
any incentive for a plant to locate in areas with less stringent standards.
(Without uniform standards of performance, such incentives by State and
local agencies could tend to create concentrations of industry which could
result in significant deterioration of air quality in those areas.)
B. Impact on Water, Solid Waste, and Noise Pollution
Standards based on the control systems described in Chapter III will
have no impact on water pollution. The overwhelming majority of control
devices used will be fabric filters which have no liquid effluent. A few
scrubbers may be used on DSE systems? however, in those cases, the decision
to install is not the result of the standard of performance. They would
be installed even without a standard of performance.
Although solid waste will be generated by the control Systems that
use fabric filters, the increase in quantity over present systems is small.
The waste captured by a control device is nearly insignificant compared to
the slag waste generated by the furnaces.
The solid wastes contain potentially harmful constituents such as
cadmium, chromium or lead compounds. Consequently, landfill sites should
be selected to prevent horizontal or vertical migration of these contaminants
53
-------
to surface or ground waters. Where geologic conditions may not reasonably
ensure this, adequate precautions, such as the use of impervious liners,
should be taken to ensure long term protection of the environment. The
location of solid hazardous materials disposed of in this manner should
be permanently recorded in the appropriate office of the legal jurisdiction
in which the site is located.
Large fans are required to move the huge volumes of air which must
be treated at an EAF facility. They generate high noise levels. The
industry has historically used fans of this type so the standard does not
introduce new noise problems. Silencing baffles can be installed around
the fan housing. The EAF process is itself a source of high noise levels.
Consequently, in most cases, the relative contribution of noise from the
fans is small.
C. Impact onEnergy Considerations
Energy requirements for air pollution control systems on electric
arc steel furnaces are almost completely determined by the amount of air
which must be moved through the system. There is considerable variation
in air flow from one type of control system to another, so power requirements
vary widely.
Tables IV-4 and IV-5 show the calculated power requirements of various
control systems and the estimated emissions which will result from generation
of electric power to operate each control system. The tables are based
-------
Table iv-a
Calculated Power Requirements and Emissions from Production
of Power to Operate Air Pollution Control Systems
(86 ton/hr carbon steel electric arc furnace shop)
Type of
system
(Air flow-
sdefm per
ton furnace
capsf ty)
No control
Direct shell
evacuation
(DSE),
open roof
(350)
DSE
and 7Q%
efficient
canopy hood,
open roof
(2000)
DSE and
80% efficient
canopy hood,
open roof
(2000)
DSE and
3Q% efficient
canopy hood,
open roof
(2000)
DSE and
building
evacuation
or canopy
hoods ,
closed roof
8 (4000)
BTU's
heat input
for power
generation
106 BTU/hr
0
2.85
16.3
16.3
16,3
32.5
KWH per
ton of
steel
produced
KWH/ ton
0
3.31
18.9
18.9
18.9
37.8
Tons of
coal needed
to generate
power
ton/day
0
2.61
14.9
14.9
14.9
29.8
Parti
emissif
power g<
Ib/hr
0
0.285
1,63
1.63
1.63
3.25
:ulate
)ns from
sne ration
Ib/ton
0
0.00331
0.0189
0.0189
0.0189
0.0378
Total parti cul ate,
NOX, and SOg
emissions from
power generation
Ib/hr Ib/ton
0
5.69
32.5
32.5
32.5
65.0
0
0.0662
0,378
0.378
0.378
0.756
Parti culate
emissions from
furnaces
Ib/hr Ib/ton
2580
263
92.8
67.0
41.2
30.9
30
3.05
1.08
0.779
0.479
0.359
Combi ned
parti cul ate from
furnaces and
power plants
Ib/hr Ib/ton
2580
263
94.5
68.7
42.9
34.2
30
3.06
1.10
0.798
0.498
0.397
Combined total
emissions from
furnace and
power plant
Ib/hr Ib/ton
2580
26§
125
99.5
73.7
95.9
30
3.12
1.46
1.16
0.857
1.12
-------
Table IV-5
Calculated Power Requirements and Emissions from Production
of Power to Operate Air Pollution Control Systems
(43 ton/hr alloy steel electric arc furnace shop)
Type of
system
(Air flow-
sdcfm per
ton furnace
capacity)
No control
701 efficient
canopy hood,
open roof
(2500)
801 efficient
canopy hood,
open roof
(2500)
901 efficient
canopy hood,
open roof
(2500)
Building
evacuation
or canopy
hoods ,
closed roof
(5000)
BTU's
heat input
for power
generation
106 BTU/hr
0
20.3
20.3
20.3
40.6
KWH per
ton of
steel
produced
KWH/ton
0
47.2
47.2
47.2
94.5
Tons of
coal needed
to generate
power
ton/day
0
18.6
18.6
18.6
37.2
Parti culate
emissions from
power generation
Ib/hr Ib/ton
0
2.03
2.03
2.03
4.06
0
0.0472
0.0472
0.0472
0.0945
Total parti culate
NO*, and S02
emissions from
power generation
Ib/hr Ib/ton
0
40.6
40.6
40.6
81.3
0
0.944
0.944
0.944
1.89
Parti culate
emissions from
furnaces
Ib/hr Ib/ton
645
213
149
84.0
38.6
15
4.95
3.47
1.95
0.897
Combi ned
parti culate from
furnaces and
power plants
Ifa/hr Ib/ton
645
215
151
86.0
42.7
15
5.00
3.51
2.00
0.992
Combined total
emissions from
furnace and
power plant
Ib/hr Ib/ton
645
254
190
125
120
15
5.89
4.42
2.91
2.79
-------
on the same conditions and model plants assumed for Table III-l. Tables
IV-4 and IV-5 are conservative since they presume the power is generated
wholly by new coal-fired power plants which comply with the standards of
performance. Emissions from fossil fuel-fired power plants are shown for
both particulate matter and combined emissions of particulate matter,
sulfur dioxide, and nitrogen oxides.
An alternate method to estimate emissions which will result from
power generated by future power plants is to project a realistic mix of
the types of plants. Coal, oil and natural gas fired, nuclear, and hydro-
electric plants built from 1974 to 1980 would be included. This projection
shows the emissions estimated in Tables IV-4 and IV-5 are high by almost
100 percent. Nuclear plants which will account for about 40 percent of
such new plants, have no significant amount of air pollutants. (Their
potential environmental impact is from hot water discharges and potential
radiation hazards.)
Figures IV-2 and IV-3 show the total air pollution emissions for the
various control systems. The bar chart sums the air pollution emissions
from electric arc furnaces and those from the coal-fired power plant which
generates the power for the various control systems. These figures reveal
that incremental capture efficiency of the closed roof or BE system over
the CH-DSE system are more than off-set by the additional air pollution
generated at the power plant. The additional power is required to move the
larger volumes of air required by the BE system.
57
-------
in
CO
300
200
I
in
o
UJ
100
POWER GENERATION
FURNACE
SYSTEM
DSE
ONLY,
OPEN ROOF
CONTROL SYSTEM GAS
FLOW, SDCFM per ton
SF FURNACE CAPACITY
350
DSE+CH,
70% CAPTURE
BY HOOD, OPE!
ROOF
2000
DSE+CH,
80% CAPTURE
BY HOOD,
ROOF
2000
DSE +CH,
90% CAPTURE
BY hUOD, OPEN
ROOF
2000
3.0
2.0
UJ
1.0
DSE* BE,
CLOSED
ROOF
4000
Figure IV-2. Emissions from electric arc furnaces plus emissions from generation of power to operate the air pollution
control system (carbon steel production, 300 tons furnace capacity, 86 ton/hour produced)
-------
300
200
-g
c/f
o
100
SYSTEM:
CON'IKUL SYSTEM GAS
FLOW, per ton
OF FURNACE CAPACITY
70%
EFFICIENT
CANOPY HOOD,
OPEN ROOF
2500
EFFICIENT
CANOPY HOOD,
OPEN ROOF
2500
EFFICIENT
CANOPY HOOD,
OPEN ROOF
2500
GENERATION
• FURNACE
BE,
CLOSED
ROOF
5000
,
CLOSED
ROOF
7.0
6.0
5.0
4.0
£
vf
3.0 1
2.0
1.0
in
1C
Figure IV-3. Emissions from electric arc furnaces plus emissions from generation of power to operate the air pollution
aontrol system (alloy steel production, 300 tons furnace capacity, 4)3 ton/hour produced).
-------
Several values of capture efficiency of a- canopy hood* were examined
to determine how it influences the overall control efficiency of an open
roof system. To do so, the null point where the environmental impact of
open and closed roof systems is equivalent was calculated. This proves
to be when the canopy hood captures 81 percent of the emissions that escape
a DSE system in a carbon steel shop and 91 percent of uncontrolled emissions
in an alloy shop which has no DSE system. If a mix of power sources is
used instead of just coal-fired power plants, the null points increase to
89 and 94 percent respectively.
Notice that on Figure IV-3, the effect of increasing the air flow
through a BE from 5000 to 6000 dscfm/ton is presented in the last two
bars. Figure IV-4 depicts the variables that must be considered in any -
investigation of prospective control schemes. Each has an effect on the
total emission rate. The discussion above was limited to the most signi-
ficant variable, C which is also the most difficult to quantify or estimate.
60
-------
TOTAL EMISSIONS=X+Y + Z
(FOR A CLOSED SHOP, X-0)
Z«f(e)
X-f(a,b,c)
Y=f(d,e)
ELECTRIC ARC FURNACE SHOP
CONTROL DEVICE
POWER PLANT
a - EMISSION FACTOR.
b - FRACTION OF EMISSIONS THAT ESCAPE THE DIRECT SHELL EVACUATION.
c - FRACTION OF EMISSIONS THAT ESCAPE THE CANOPY HOOD.
d -CONCENTRATION AT THE CONTROL DEVICE OUTLET.
e -GAS FLOW RATE THROUGH THE CONTROL DEVICE.
rigureIV-4. Variables that affect comparisons of various control systems
-------
Page Intentionally Blank
-------
V. SUMMARY OF THE FOR DEVELOPING STANDARDS
A. LiteratureReview and Industria-1 Contacts
Available literature was reviewed to gather background information
on the industry and its processes. The locations of well-controlled facilities,
their design and data on emissions were noted. A prime literature source
was the Air Pollution Technical Information Center, EPA, which routinely
abstracts and catalogues literature related to air pollution. Other sources
were air pollution and industry oriented periodicals, meetings of technical
societies and pertinent textbooks.
Several meetings were held with an Ad Hoc Committee of the American
Iron and Steel Institute, which was formed to provide any technical
information that EPA might require. In addition, contacts were made with
owners of electric arc furnaces, manufacturers of control equipment and
other people knowledgeable about the industry.
B. Selection of Pollutants
Air pollutants considered as candidates for the development of standards
of performance for electric arc furnaces (EAF) include particulate matter,
carbon monoxide, fluorides, nitrogen oxides, and sulfur oxides. Of these,
particulate matter has the potential of being emitted in the greatest
quantity if not properly controlled (see Chapter I).
Significant quantities of carbon monoxide (CO) may also be emitted.
If uncontrolled, emissions are six pounds per ton of steel produced (based
63
-------
on EPA's test at Plant A). Assuming this emission rate for production of
all steel from electric arc furnaces, the CO emissions would be 0.5 percent
of the total industrial CO emissions in the United States (based on 10
million tons per year total industrial CO emissions in 1968^ ' and 15 million
tons per year electric arc furnace steel production in 1967^ '). Near very
large shops, the maximum ground level concentration (under worst meteorological
conditions) of CO may exceed the air quality standard of 40 mg/m^ (one hour
average).
The only known technique to control CO emissions is a DSE system. The
alternative particulate matter standards considered in Chapter VIII encourage
the use of this technique whenever it has been technically demonstrated,
thereby indirectly achieving control of CO. Chapter VIII also discusses a •
possible CO standard.
Data provided by industry on emissions of nitrogen oxides indicate they
are less than 0.1 pound per ton of steel produced (lb/ton).^ ' Emissions
of sulfur oxides have been estimated as 0.01 lb/ton.^ ' No attempt is now
being made to minimize the emissions of these pollutants. Because of the
low emission levels and the absence of demonstrated emission control techniques,
standards for these two pollutants have not been considered in Chapter VIII.
Emissions of fluorides from controlled facilities have been estimated
at levels from 0.004^18' to O.?'19' Ib/ton of steel produced and are evolved
-------
from EAF furnaces only when fluorspar is used to form a slag. Since fluorides
are thought to be emitted from EAF's primarily as Insoluble partlculate,
the efficiency of control would be expected to be essentially the same as
that of particulate control. No separate standard is recommended, since
fluorides may be controlled by the standard for particulates.
C. Affected Facilities
The electric arc furnace is the primary facility and overwhelmingly
the major source of air pollutant emissions in an electric arc furnace shop.
However, there are also other facilities that emit air pollutants. They
include:
1. Argon-oxygen decarburizing vessels.
2. Vacuum-arc remelting furnaces.
3. Inert atmosphere remelting furnaces.
4. Electroslag remelting furnaces.
5. Teemi ng.
b. Continuous casters.
Of these, only argon-oxygen decarburizing vessels emit large quantities
of pollutants, primarily parti oil ate matter. They and the three types of
remelting furnaces produce only small quantities of a few specialty steels.
65
-------
Each process is distinctly different and parallel efforts would be required
to develop standards for each. Since electric arc production furnaces
contribute most of the pollutants emitted from a shop, they were selected as
the initial affected facility. The others may be candidates for standards
of performance in the future but are not now considered because of their
small contribution to the total emissions from a shop.
One other affected facility was selected; the equipment for on-^ite
handling of dust collected by the air pollution control device. Although
this 1s usually a small source, there is potential for large quantities of
collected dust to become airborne if it is handled Improperly.
Although the furnace is the only affected facility within a shop (the
building which houses the furnaces), the recommended standards apply to one
emission point other than those directly connected to the furnace. A portion
of the emissions from the furnace evolve into the shop atmosphere and emit
from a monitor on the roof of the shop. A standard applied only to the
control device would not limit these emissions.
D, Plant Inspections
Preliminary investigations of 30 plants identified from a review of
the literature and contacts with industry revealed the location of 11 plants
reportedly well-controlled (BE or CH systems) for-particulate emissions. Ten
were visited, visible emissions evaluated, and information obtained on the process
and control equipment. Although many of these practiced good control techniques,
66
-------
the facilities at only three plants (Plants A, I and J) were amenable to
testing with EPA Method 5. Others were not suitable for emission measure-
ments because they use pressure baghouses which have no stacks. Although
development work is in progress, sampling methodology for this type
Installation has not been standardized.
These three plants were nearly identical except for size. They all
produced alloy steels and controlled particulate emissions with a building
evacuation system. Each had a fabric filter control device that exhausted
through multiple stacks. Rather than spread the test program effort over
three tests at nearly identical plants, it was decided a more comprehensive
test of one plant would provide more information. The middle sized plant
offered the best possibilities for this comprehensive test. Its size was
typical of the mid-range for the industry, and the fabric filter did not have
an inordinately large number of exhaust stacks. This permitted simultaneous
sampling of a higher percentage of the total stacks with much less effort
than required for the lavge plant.
Six additional plants were visited to obtain more Information on
the process and those systems which capture only a portion of the furnace
emissions. Of the 15 plants visited, 10 had DSE systems, the only known
control technique for carbon monoxide emissions. Two were sampled to
determine the carbon monoxide emission rates. These two plants were selected
primarily on the basis of ease of testing. Design parameters that affect
67
-------
removal of carbon monoxide were not well known and, of course, visual
indications of performance were not possible.
E. Emission Measurement Program
The one installation from which particulate matter emissions were
measured by EPA used a fabric filter collection system and a BE capture
system. The filter system had six discharge stacks. The filter compartments
and stacks were inspected for evidence of any difference in emission rate
from the stacks. None was found., therefore, three stacks, selected for
convenience, were sampled simultaneously.
The particulate samples were collected for four hours. Usually the
sampling period was chosen to coincide with one complete furnace cycle.
However, the plant had two furnaces with staggered cycles served by a common
control system. The sampling period could not coincide with the cycles of'
both furnaces. Four hours was selected to provide capture of a sufficient
amount of sample to obtain an accurate measurement. The sampling periods were
selected to include furnace operations expected to generate above-average
emissions, thus insuring an average or higher particulate loading to the filter.
These operations were scrap melting, oxygen blowing, charging and tapping.
During each sampling period, operation of the process was monitored.
A log of operations was kept for each furnace which included:
1. The level of power to the furnaces.
2. The type and amount of furnace additions.
3. The occurrence of charges, taps, oxygen blows or other furnace
operations.
68
-------
The tons of steel poured and the amount and description of scrap charged
were also recorded for each cycle.
Measurements of carbon monoxide emissions were conducted by EPA at
Plants D and E. Since the tests were designed to measure emissions only
when a DSE system was operating, the sampling periods were selected to
coincide with one complete furnace cycle. After further evaluation of
an alternative standard for carbon monoxide, the data was recalculated for
a sampling period of the first 90 minutes of a cycle excluding periods when
the DSE system is shut off. This is discussed further in the "next section
on units. Monitoring of the process was the same as during the particulate
test.
F. Units of the Standard
The two principal types of units considered are units of mass rate and
concentration. The basic difference is that a standard which restricts
the mass rate of emissions would minimize the total mass emitted, whereas
concentration units allow the mass emission rate to vary with the volume
of gas through the control device.
*
Concentration units are completely unsuitable for a carbon monoxide
standard because controlled emissions are emitted in higher concentrations
(smaller gas volume) than for no control.
69
emissions in Ib/hr-ton. The process information required is furnace capacity
and the times when a cycle starts and ends, which can easily be obtained from
plant lots. The capacity of a single furnace is determined by averaging the
tons of steel produced for all cycles which contribute to a sample obtained
during a performance test. Capacities would be additive for multi-furnace
shops. The figure for tons-of-steel-produced must include both whole ingots and
71
-------
Concentration is easy to measure, requires no reliance on plant records,
and eliminates any potential conflict with OSHA's standards (unlike mass
units, there is no restriction on gas volume). Concentration units allow the
operator some latitude in the gas volume used to insure good capture velocity
at the canopy hood. Good capture at the canopy hoods minimizes emissions
through the open roof.
Two types of mass units were considered; Kg of emissions/metric ton of
production and Kg of emissions/hr-metric ton of furnace capacity. Equivalent
butts. (The steel remaining after ingot molds are filled is called a butt.)
Figure V-I illustrates the calculation of furnace capacity.
Units of "pounds per hour per megawatt of transformer capacity"
(Ib/hr-Mw), suggested by one manufacturer, are no more accurate, hence
have no advantage over Ib/hr-ton.
6. Development of the Proposed Standards
On February 22, 1973, the Agency presented to the National Air Pollution
Control Techniques Advisory Committee (NAPCTAC) a draft technical report
and standard for electric arc furnaces in the steel industry. In summary,
the draft report concluded that best demonstrated technology for control of
emissions from electric arc furnaces in the steel industry is the building
evacuation (BE) system or the combination. BE-direct shell evacuation (DSE)
system in conjunction with appropriate control equipment. The draft stan-
dard recommended a particulate matter limitation of 0.06 Ib/hr-ton and 10
percent opacity and a carbon monoxide limitation of 0.80 Ib/hr-ton.
Representatives of the steel industry attended the meeting and expressed
their comments to the committee, suggesting that the particulate matter
standard be 0.244 Ib/hr-ton and allowing 30 percent opacity for 20 minutes
per furnace cycle. The representatives commented that data representative
of the carbon steel industry were not used in the development of the draft
standard and it is unrealistic to apply data from a low productivity alloy
shop to a carbon steel shop where production rates are two to three times
72
-------
SAMPLING PERIOD
<
I
j^ 140-TON HEAT
F
H 110-T
If
^JA 160-TON HEAT
flf
h 150-TON HEAT ^
* *l
DN HEAT ^ A 90-TOI
Pf
FURNACE 1
^j AVERAGE =150 TONS
il
FURNACE 2
AVERAGE = 150 TONS
FURNACE 3
^HEAT A,! AVERAGE =100 TONS
f!
TOTAL SHOP CAPACITY = 400 TONS
I I I
HOURS'
Figure V-]. Sample calculation of furnace shop capacity.
to
-------
greater. The representatives stated that the CO standard was untenable
and recommended deferral of a standard until more data are obtained.
Concern was expressed regarding the effects of reduced building ventilation
rate on the visibility and working conditions in the shop. The
representatives pointed out that the large air volumes from the BE system
would require large quantities of electrical power, thus increasing the
severity of the energy crisis, power plant emissions and operating costs.
The revised draft technical report and standard were presented at the
NAPCTAC meeting on May 30 and 31, 1973. The particulate matter standard
was changed from 0.06 Ib/hr-ton to 0.10 Ib/hr-ton. The carbon monoxide
and the opacity standards were the same as presented at the previous meeting.
Steel industry representatives expressed their objections to the units of
the standard and the resultant effects of restricted ventilation rate on
workers in shops in hot climates. The representatives argued that the
fallacy in the Agency's analysis was the assumption that ventilation rates
were the same regardless of shop productivity. The industry representatives
suggested that the standard be expressed on a concentration basis and be
set at 0.008 gr/dscf. Difficulties of use of DSE systems when reducing
slags are used were discussed.
A revised draft standard and technical report were presented at
the NAPCTAC meeting on January 9, 1974. The draft standard recommended
that emissions be limited as follows:
-------
1. No more than 9 mg/dscm (0,004 gr/dscf) from the cfi.r pollution
control device.
2. Less than 10 percent opacity from the air pollution control
device.
3. No visible emissions from the shop.
4. No more than percent average opacity from the shop as
a direct result of charging or tapping of a furnace and for
3 minutes thereafter.
5. Less than 10 percent opacity of any gases from dust-handling
equipment.
This draft standard can be achieved by use of either the building
evacuation system or a combination of a system utilizing direct
shell evacuation and a canopy hood which are considered to be best
systems of emission reduction when all relevant factors are considered.
At this meeting industry representatives suggested a standard of 0.008 gr/dscf
for a dry collector and 10 percent opacity, and 0.02 gr/dscf for a wet
collector and 20 percent opacity. A 20 percent opacity standard for
visible emissions from the shop was also suggested. The rationale
for this draft standard is discussed in Chapter VIII. The proposed
standards of performance differ slightly from the draft standards
and the rationale for the changes is discussed in Chapter II.
75
-------
Page Intentionally Blank
-------
VI. DATA TO SUBSTANTIATE A STANDARD
A. Particulate EmissionData
Figure VI-1 presents the results of measurements of particulate
emissions gathered for standards development. Many of the tests were
conducted on fabric filter collectors with multiple stacks or in a
large open area or "monitor" through which several filter compartments
exhaust. Separate samples were collected in one or more stacks or above
one or more compartments. Unless otherwise noted in the following
discussions, each vertical "set" of data in Figure VI-1 is for a
single stack or compartment. This presentation recognizes that
each compartment filters independently and each "set" of data is
representative of levels achievable by fabric filters.
Figure VI-2 presents the results of the same measurements 1n
pounds per hour per ton of furnace capacity (Ib/hr-ton). On this
figure all of the data for each plant is grouped in one vertical
data bar (except Plant A which was sampled by two different
methods) to allow a comparison of the mass emission rate from each
plant. Each data point represents a separate test, combining
samples collected at different sampling locations. The average
of the concentrations for all samples and the total gas flow to
the control device(s) were used to calculate mass emissions.
Pressurized baghouses which discharge the cleaned gases
through a large open area or monitor are typical at electric arc
77
-------
» U.UIU
0.009
0.008
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03
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31 0.005
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•5 111
1 T 1 1 1
PLANT A A A A 11
TYPE OF COLLECTION BE
SYSTEM
MAJOR TYPE ALLOY
OF STEEL PRODUCED
t/r*\s
KEY
AVERAGE
EPA TEST METHOD
OTHER TEST METHOD
BUILDING EVACUATION
CANOPY HOODS
DIRECT SHELL EVACUATION
a
o y
q lUi —
i y
_
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i 1 1
i 1 1
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1 \ r\ () f\ f) \ * II /kl 11 1
11 11 12 12 12 J J J M M B C C C C
BE BE DSE+CH CH DSE+CH
ALLOY ALLOY CARBON ALLOY CARBON
FIGURE VI-1
PARTICULATE EMISSIONS FROM ELECTRIC ARC FURNACE SHOPS
-------
0.15
SS'G
o|
1 « o.io
tu re
fef
_J 0
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0.05
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tf
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o
BE
CH
DSE
f
i
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i
KEY
AVERAGE
EPA TEST METHOD
OTHER TEST METHOD
BUILDING EVACUATION
CANOPY HOODS
DIRECT SHELL EVACUATION
IE
i
'T
i !
'
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11111
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I VI
1
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8 4 i;
1 f 1 ^ 1
PLANT A A 1 J M B C
PE OF COLLECTION
SYSTEM
MAJOR TYPE OF
BE
ALLOY
BE BE DSE CH CH DSE CH
ALLOY ALLOY CARBON ALLOY CARBON
STEEL PRODUCED
FIGURE vi-2
PARTICULATE EMISSIONS FROM ELECTRIC ARC FURNACE SHOPS
-------
furnace shops. Since they have no stacks, they present a difficult
sampling situation which does not meet the criteria for use of EPA
Method 5. EPA Identified only three plants with stacks and only one
was tested, Plant A. ^ Plants I and J -have a similar stack
configuration. All three plants are very similar, however, and the
decision to measure emissions from A was based primarily on its
size and ease of sampling. Plants I and J were later sampled using
EPA's Method ,5. The owners provided the data to EPA.
Plant A has two electric-arc furnaces with capacities of 50 and
75 tons. Particulate emissions from the furnaces, which were
producing alloy steels, are controlled with a BE system and a fabric
filter. Measurements of emissions were made simultaneously on three
of the six stacks on the fabric filter. Each stack serves two
filter compartments. The stacks, only one diameter tall, precluded
compliance with the criteria in EPA Method 5 for minimum distances
from the sampling location to the nearest flow disturbance. How-
ever, the uniform velocity profile found in the stack Indicates
the samples are representative. All other criteria of Method 5
were met. As shown by the first three bars on Figure VI-1 ..average
results of the three samples for each stack were 0.0011, 0.0014
and 0.0015, for a combined average of 0.0013 gr/dscf. Individual
results from the nine samples ranged from 0.0005 to 0.0032 gr/dscf.
80
-------
On one stack, s-imultaneous samples were collected with an ASME
participate sampling train. Its results are shown as the fourth bar
in Figure VI-1-and the second bar in Figure VI^-2 to permit a comparison
with the results of the EPA train shown as the third bar on Figure VI-1.
The ASME sample included particulate matter from a nozzle wash and
alundum thimble catch which are commonly measured, plus a probe wash and
glass -fiber filter catch. The nozzle and thimble catch .averaged 27
percent of the total.
Each sample run was approximately four hours. The sampling periods
were selected to include furnace operations expected to generate above-
average emissions. These operations were oxygen blowing, scrap melting,
charging, and tapping. Process operation was normal during the test.
Plants I and J on Figures VI-1 and VI-2 differ from Plant A
primarily in size. Plant I has three furnaces with 100 tons of capacity
each, one with 75 tons and one with 50 tons. Plant J has two furnaces
with 25 tons capacity each. The data were supplied by the plant
(23)
operators who stated the tests were conducted according to Method 5. '
No abnormal process conditions during the tests were reported. All
samples were collected for about two hours.
At Plant I, two parrallel fabric filters are used (indicated by
I, and I2 on Figure VI-1). One fabric filter has 7 stacks and the
81
-------
other 10. Three runs, consisting of samples from one stack on
each fabric filter, were conducted. Different stacks were sampled
for each test. Plant J has 10 exhaust stacks on one fabric filter.
Each run consisted of a sample from one stack. A different stack
was sampled for each run. All of the concentrations measured at
Plants I and J were below 0.002 gr/dscf.
Plant M produces carbon steels in two furnaces with 100 tons
capacity each and one with 150 tons of capacity. The 150 ton
furnace was not operating during the test and its dampers in the
control system were shut. Emissions are controlled with a DSE-CH
system and fabric filters. Monitors on the building roof were
open. The CH is ducted to one filter and each DSE system is ducted
to a separate filter. One four-hour sample was collected from the
CH filter and one three-hour sample from one of the DSE filters.
No abnormal process conditions during the test were reported. The data
weresupplied by the vendor of the fabric filter.' '
The first point for Plant M on FigureVI-1 shows the result of
the sample collected from the filter servicing the DSE. The sampling
was conducted by traversing a monitor with a Method 5 sampling train.
The sample was collected isokinetically. Results showed 0.0026
gr/dscf. The filter servicing the CH has a stack. The test report
stated it was sampled according to Method 5. Results shown by the
second point on FigureVI-2were 0.0073 gr/dscf. The reasons for the
82
-------
high emissions are assignable. The filter was reconditioned from
a previous use where a lower air flow rate was used. It now has
a 4:1 alr-to-cloth ratio compared to 2 or 3:1 usually used. Also,
an open weave bag Is used to prevent excessive pressure drop
because of the high air flow. On Figure VI-2 the total emissions
from Plant M were calculated based on an emission concentration of
0.0073 gr/dscf from the CH and by assuming both DSE filters achieve
0.0026 gr/dscf and have the same flow rate.
At Plant B, alloy steels are produced 1n five small furnaces
(only three were operating during the test) and emissions are
controlled with a CH system, closed roof on the shop and a fabric
filter with a monitor exhaust (no stack). No abnormal process
conditions during the test were reported. The data were provided by
the plant and collected according to the standard procedures of
foc\
the vendor of the control device, ; The samples were * collected
above the center of one filter compartment. Isokinetic sampling
conditions were not maintained. Results of the two samples were
reported as "negligible" and "2.0 X 10~5 gr/dscf.11
Plant C produces carbon steels in three furnaces, two with 100
tons of capacity each and one with 75 tons capacity. A DSE-CH
control system and fabric filter are used. The data were collected
by a local control agency using their own test method.^ ' The test
83
-------
train consisted of a probe, paper thimble, dry gas meter and vacuum pump.
Results were reported in terms of wet gas. Sampling was conducted at a
single point in various filter compartments above the bags. Four consecutive
tests were run for about one'hour each. The four hour period coincided
with a full cycle on one furnace. Each test consisted of one sample from
each of four selected compartments. No abnormal process conditions during
the test were reported. Results for the 16 samples ranged from 0.0013 to
0.0079 gr/scf (wet).
Visible emission data were also obtained for several plants. Con-
(27)
tunuous observations were made at plants C and G for about one hour each. '
Emissions from two fabric filters were observed at Plant 6 and from one at
Plant C according to EPA Method 9. No visible emissions were observed
from one filter (on a DSE system) at Plant G. Puffs of about five
seconds duration were visible from the other filter at Plant G and
from the filter at Plant C. They appeared to coincide with the bag
cleaning cycle of the filter servicing a BE system at Plant 6 and thus
were believed to be non-representative of a well maintained and operated
fabric filter. Short observations during plant visits showed 12 other
fabric filters, one electrostatic precipitator and one scrubber with
no visible emissions. Method 9 was not used for observations at these
14 installations.
The buildings at plants C and G were also observed according to
Method 9 for about one hour.' ' No visible emissions were observed
-------
at Plant G. At Plant C, visible emissions up to 20 percent opacity
were observed for one or two minutes after monitors on the roof of
the building were opened. The monitors were closed during periods
of high dust evolution in the shop (e.g., charging and tapping) and
reopened after these periods. Process operations during these
observations were not recorded.
Visible emissions from the shop were observed at Plant M.I/
This plant uses a direct shell evacuation (DSE)- canopy
hood (CH) control system similar to that on which the proposed standard
is based. Monitors on the roof of the building are oppn. Readings of
the visibility of emissions observed for each charge and tap are presented
in Table VI-1. Except for periods of charging and tapping, emissions
were visible from the roof of the building for only 30 seconds during
observations over 15 hours of furnace operation. Emissions were visible
within the building during many other short periods, however, they were
not discernible as they left the building. Operation of both the furnace
and control equipment was normal except for one short period with a
DSE damper closed. Power to a control instrument was disrupted and
caused the malfunction. Observations during this upset were not
considered.
I/
Trip report for tests of visible emissions at Plant M, May 20,
1974.
85
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TABLE VI-1
VISIBLE EMISSIONS FROM CHARGING AND TAPPING
PLANT M
Charges
Maximum Opacity
Reading, Percent
10
0
25
35
15
60
0
25
5
35
Average Opacity,
Percent
1
0
7
12
5
10
0
6
1
8
Taps
Maximum Opacity
Reading, Percent
60
80
75
65
75
Average Opacity »a
Percent
16
24
21
21
33
a. Arithmetic average of readings every 15 seconds (including all zero
readings) from the beginning of the process operation until three
minutes after the end of the operation.
86
-------
Visible emissions were ooserved from the building at Plant F
(28)
during a tap and a charge. ' Plant F has a DSE-CH system with open
monitors on the building roof. Ten to 40 percent opacity for 17 minutes
was observed during the tap and up to 10 percent for four minutes during
the charge.
Control of particulate matter emissions from fabric filters has been
guaranteed at levels as low as 0.004 gr/dscf on plants A, I and J; alloy
(29)
shops with building evacuation systems. ; The guarantee applied if
the inlet loading to the fabric filter was below 0.3 gr/dscf. The EPA
measured inlet loading was 0.05 gr/dscf. Above this inlet loading
the guarantee specified 99 percent efficiency. One vendor has stated
they would also guarantee this level for Plant E as discussed below.
A survey of several vendors was conducted by the owners of
Plant E^ ''* ' to determine the lowest guarantee they could obtain
for a new control system now under construction at their plant. The
system is BE (similar to Plant S) to assure control of charging and
tapping fumes. DSE systems are already in operation at the plant.
Although monitors will be open in the roof near the ends of the
building, partitions will sufficiently isolate the center portion of
the roof to render it similar to a BE system.
87
-------
Four vendors responded to the inquiries which asked if they
would guarantee "a concentration lower than 0.004 gr/scf." None would
guarantee a lower concentration. One stated they would guarantee
this level and that they expected it can be maintained "... over a
lengthy period assuming proper maintenance ..." A second vendor stated
they would guarantee 0.004 gr/actual cubic foot (about 0.005 gr/dscf).
Following are quotes from the responses of the other two vendors.
"[The vendor] is confident that the proposed dust
collector for [Plant E] is capable of a discharge
meeting or exceeding 0.004 grains per SCF for solid
particulate. This performance is expected to be
maintained over lengthy periods of time if the unit
is properly serviced." "... it is not within
the limits of good engineering judgment to guarantee
such levels."
11. . . to guarantee [0.004 gr/dscf] would leave
an insufficient margin of safety."
B. Carbon Monoxide Emission Data
Figure VI-3 presents the carbon monoxide (CO) data collected by
EPA. ^ '* ^ ''^ ' The data are presented in units of pounds per ton
of steel produced (Ib/ton) for two plants with DSE control and one with
BE control (a BE system does not reduce CO emissions). These units
88
-------
permit a comparison of the emissions of CO from BE and DSE systems.
Emissions from the two plants controlled by DSE's are also presented in
units of Ib/hr-ton of furnace capacity on the right of Figure VI-3. The
average emissions over the first 90 minutes of a furnace cycle (excluding
times when the DSE system is shut off during charging) in Ib/hr is divided
by the tons of furnace capacity. These units for a standard are discussed
in more detail in Chapter V,
CO emissions from the BE system at Plant A averaged 5.6 Ib/ton and
ranged from 4.9 to 6.5 Ib/ton. Emissions from the DSE systems at plants
D and E averaged 0.76 and 1.04 Ib/ton, respectively. They ranged from
0.52 to 1.07 Ib/ton for Plant D and from 0.54 to 1.39 Ib/ton for Plant E.
For all three tests, the emissions were continuously monitored with a non-
dispersive infrared analyzer. Operation of the processes was normal
except for a short period at Plant D when sampling was discontinued because
of a fan failure.
The sampling locations at plants D and E were well downstream of the
high temperature zones where combustion of the CO occurs. At Plant D,
samples were collected before the scrubber to avoid any bias that absorption
of CO in the scrubber would cause. The collector more commonly found on
DSE's, the fabric filter, does not collect CO. At Plant E, the effluent from
three furnaces is manifolded to a single fabric filter. Samples were
collected upstream of where the ducts combine. This provided data repre-
sentative of the average emissions from a single furnace cycle.
89
-------
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PLANT D E A D E
TYPE OF COLLECTION SYSTEM DSE DSE BE DSE DSE
TYPE OF CONTROL DEVICE VS FF FF VS FF
MAJOR TYPE OF STEEL CARBON CARBON ALLOY CARBON CARBON
PRODUCED
uJ
FIGURE vi-3
CARBON MONOXIDE FROM ELECTRIC ARC FURNACES
-------
Sampling at plants D and E was conducted only during operation
of the DSE system. Emissions were not measured during charging and
tapping, or between heats when the DSE system was shut off. Sampling
facilities were inadequate to obtain data during these periods.
Sampling at monitors on the roof of the building would have been
required. An analysis of data from Plant A showed that CO emissions
at these times are very low, less than five percent of the total
emissions from a cycle. If the sampling were conducted over the
entire cycle, as at Plant A, average emissions at Plants D and E in
Ib/ton could be up to 20 percent lower than shown on Figure VI-3,
because an average that includes the periods of low emissions will
lower the average for the entire cycle.
The average CO concentration measured at Plant A was 55 parts
per million (ppm) by volume, and the maximum five-minute average
during the test was 320 ppm. For Plants D and E, the average
concentrations and the maximum five-minute average concentrations
were 200 and 1,090 ppm., and 440 and 3,200 ppm, respectively.
Concentrations are lower for a BE system because of the large volume
of building air that dilutes the exhaust gas stream. However, mass
emissions are lower for DSE systems as Figure VI-3 shows. Peak
concentrations generally occurred during scrap melting and oxygen
blowi ng.
91
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Page Intentionally Blank
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VII. OF ECONOMIC INFORMATION
A. Cost
1. Cost of air pollution control.
A majority of the electric furnace installations are controlled
by fabric filters. There are a few venturi scrubbers and one
electrostatic precipitator in service. In addition to the variations
in control devices, there are several methods of collecting the fumes
for cleaning. Figure VII-1 depicts the major cost items for three.
First is the direct shell evacuation method whereby fumes are drawn
from the shell of the furnace, the carbon monoxide burned, the
fumes cooled, and then routed to the control device. This method
has the advantage of the lowest flow rate but when fabric filters
are used, requires a cooling system for temperature adjustment to
preclude damage to the control device. However, when the furnace
lid is off during charging, the control system is inoperative. At
the end of the cycle, when the furnace is tilted for tapping, fumes
emerge from the molten metal. Because of these periods of uncontrolled
emissions, direct shell evacuation is not considered a viable control
method by itself.
The second method incorporates a canopy hood to capture charging
and tapping emissions to supplement the direct evacuation system.
A greater total flow of air results. The cooler air from the
93
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canopy hood is normally mixed with the fumes in the direct shell
evacuation system to cool the fumes and lower the volume of water
needed to cool the dust laden stream prior to cleaning. (For
alloy furnaces, in which a reducing slag is used, direct evacuation
cannot be used, and a canopy hood must be used by itself.)
The third method is total building evacuation which results in
the greatest air flow but the costs of gas conditioning are the least.
Industry practice varies widely in the amount of air flow per
ton of furnace capacity for each of the collection configurations;
however, the following figures approximated general usage and formed
the basis of the economic studies:
Alloy Shops
Canopy Hoods 2500 SCFM/Ton of Capacity
Building Evacuation 5000 SCFM/Ton of Capacity
Carbon Steel Shops
Direct Evacuation
plus Canopy Hoods 2000 SCFM/Ton of Capacity
Building Evacuation 5000 SCFM/Ton of Capacity
The present size distribution of furnaces is skewed to the
smaller size (63% are 50 tons or less and 87% are 100 tons per
heat or less). In order to provide an adequate spread, costs
were obtained for 25 ton and 100 ton per heat furnaces.
94
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*-FOR OUST REMOVAL BY BASHOUSE, OFF GAS
IS COOLED Si AIR COOLED SERPENTINE
COIL IN LIEU OF WATER SPBAY INJECTION.
•TEMPERING AIR
) DUSTY SAS TO
' LEANING SYSTEM
ELECTRIC FURNACE
SPRAY COMPITIOMNS TOWER A
.WATER TO COOLINS
TOWER AND SLOWDOWN
A. DIRECT SHELL
EVACUATION
DUSTY 6AS TO
CLEAN1SS SYSTEM
ELECTRIC FURNACE
B. DIRECT SHELL EVACUATION
AND CANOPY HOODS
/
\
1
d DUSTY SAS TO
CLEftNINS SVSTEM
If— BU1LD1M6 ROOF LINE
\
CANOPY MISCELLANEOUS
AIR INLETS
X-BUILDINS WALL
NATURAL AIR INLET
~~
C. TOTAL BUILDING EVACUATION
FIGURE N° VII-T
ELECTRIC ARC FURNACE GAS COLLECTION CONFIGURATIONS
95
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Tables VII-1 and VI1-2 set forth detailed cost estimates for
fabric filter control in each collection configuration. Costs for
precipitators and wet scrubbers are not included since not enough
cost information is available for these methods at higher air flow
rates.
2. Cost effectiveness.
Tables VII-3 and VII-4 depict the cost effectiveness of the
control systems for carbon steel and alloys, respectively. Since
it is difficult to judge capture efficiency when a canopy hood is
involved, efficiencies of 70%, 80%, and 90% are assumed. If the
canopy hood is 80% efficient, the costs are $1.45/ton of steel
produced and 4.9<£/pound of particulate matter captured for a
carbon steel shop. When total building evacuation is used, the
costs rise to $2.49/ton of steel produced and 8.4<£/pound of
particulate captured. It should be noted, however, that it
costs $2.47 for each incremental pound of particulate captured in
going from the direct evacuation with canopies to total building
evacuation.
The costs in Table VII-4 for the alloy shop show the same
trends at a higher level. If the canopy hood is 80% efficient, the
costs are $3.19/ton of alloy produced, and 28<£/pound of particulate
captured. Total building evacuation costs $4.97/ton of alloy
produced and 35<£/pound of particulate captured. However, in
this case the cost for the incremental pound of particulate
captured is only 69<£.
96
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TABLE VII-1
ELECTRIC ARC FURNACE CONTROL COSTS FOR SHOP WITH THREE 100 TON
FURNACES USING FABRIC FILTER CONTROL DEVICE
Gas Flow, SCFM (Design)
Investment
Gas Cleaning Device, $
Auxiliary Equipment, $
Ductwork, Utilities, $
Engineering, Overheads, Etc.,$
Total Investment, $
$/ Annual Ton Capacity
Operating Costs
Operating Labor & Supervision, $/Yr
Power @ 1.2<£/KWH, $/Yr
Make-up Water @ 25<£/1000 Gal, $/Yr
Cooling Water Treatment @ 0. 2^/1000 Gal, $/Yr
Maintenance @ 6% Inv, $/Yr
Property Tax, Insur, G & A, @ 6% Inv, $/Yr
8% Interest (Averaged to 5%), $/Yr
Depreciation, 15 Yr. St. Line, $/Yr
Total Annual ized Cost, $/Yr
Tons/Yr(7920 Hrs/Yr, 7 Hrs/Heat for Alloys & 3.5 Hrs/Heat for C.S.)
Cost/Ton Produced, $
CARBON STEEL
Direct
Evacuation &
Canopy Hoods
600,000
$1,038,500
433,000
1,265,500
583,000
$3,320,000
$9.78
$ 2,240
168,370
23,080
1,850
199,200
199,200
166,000
221,330
$ 981,270
678,600
$1.45
Building
Evacuations
1,500,000
$1,969,700
651,200
1,965,200
976,900
$5,563,000
$16.40
$ 2,240
294,520
_
333,780
333,780
278,150
370,870
H, 613, 340
678,600
$2.38
fll i nvs
Canopy Hoods
Only
750,000
$1,246,200
440,300
1,321,400
700,900
$3,708,800
$10.93
$ 2,240
201 ,600
_
222,530
222,530
185,440
247,250
$1,081,590
339,300
$3.19
Building
Evacuation
1,500,000
$1,969,700
651,200
1,965,200
976,900
55,563,000
$16.40
t 2,240
368,020
_
333,780
333,780
278,150
370,870
P, 686, 840
339,300
$4.97
-------
-------
TABLE VII-3
COST EFFECTIVENESS: 300 TON CARBON STEEL SHOP9
(678,600 Tons/Year Production)
Type of Control
Parti culates:
W/0 Control, Ibs/yr
With Control, Ibs/yr
Controlled, Ibs/yr
Net % Efficient
Investment, $
$/Ton Annual Capacity
Annual Cost, $
$/Ton Steel Produced "
$/lb Particulates Removed
Dir. Evac. with
Open Roof
20,358,000
2,069,700
18,288,300
90
1,946,900
2.87
643,340
0.95
0.035
Direct Evacuation with Open
Roof Plus Canopies
70% Eff.
20,358,000
732,900
19,625,100
96
3,320,000
4.89
981 ,270
1.45
0.050
80% Eff.
20,358,000
528,600
19,829,400
97
3,320,000
4.89
981 ,270
1.45
0.049
90% Eff.
20,358,000
325,000
20,033,000
98
3,320,000
4.89
981,270
1.45
0.049
Building
Evacuation
20,358,000
243,600
20,114,400
99
5,563,000
8.20
1,686,840
2.49
0.084
A Bldg. Evac.
-8Q% Eff.
D.E. & Can.
528,600
243,600
285,000
2,243,000
3.31
705,510
1.04
2.47
Emission data from Table II-l.
-------
o
o
TABLE VII-4
COST EFFECTIVENESS: 300 TON ALLOY SHOP'
(339,300 Tons/Tear production]
Type of Control
Parti culates:
W/0 Control, Ibs/yr
With Control, "Ibs/yr
Controlled, Ibs/yr
Net % Efficient
Investment, $
$/Ton Annual Capacity
Annual Cost, $
$/Ton Steel Produced
$/Lb Parti cul ate Removed
Canooies with Qoen Roof
70% Eff.
5,089,500
1,687,000
3,402,500
67
3,708,800
10.93
1 ,081 ,590
3.19
0.32
80% Eff.
5,089,500
1,180,100
3,909,400
77
3,708,800
10.93
1 ,081 ,590
3.19
0.28
m Eff.
5,089,500
665,300
4,424,200
87
3,708,800
10.93
1 ,081 ,590
3.19
0.24
Evacuation
5,089,500
305,700
4,783,800
94
5,563,000
16.40
1,686,840
4.97
0.35
A Bldg. Evac. -
80% Eff. Can.
1,180,100
305,700
874,400
—
1,854,200
5.47
605,250
1.78
0.69
Emission data from Table II-l.
-------
B. Economic Impact
Seventy percent of the electric arc furnaces are concentrated in
six States: Pennsylvania, Illinois, Ohio, Texas, Indiana, and New York.
Their emission limitations for 25 and 100 ton furnaces are compared in
Table VI1-5 with the proposed standards of performance. The type of
equipment and cost of operation are similar to that required by the
proposed standard of performance. Due to opacity restrictions which
vary from 20% to 40%, a direct shell evacuation system cannot be used
as the sole control method since it is inoperative during charging and
tapping. These two operations consume more than the usual three to
five minutes per hour which are exempt from the normal opacity restrictions
in most jurisdictions. Systems with canopy hoods and open monitors may
also violate the opacity standards due to emissions that escape capture
by the hoods.
For these States, therefore, the proposed standards of performance
will have no economic impact. However, the promulgation of a standard
of performance will result in the uniform, nation-wide, application of
the best available technology. Thus if a company installs a new electric
furnace in a jurisdiction with less stringent regulations, the standard of
performance will require that the company invest as much in controls
as if the unit were installed in Pennsylvania or Illinois.
C. Overal1 Economic Cons1derations
Even though the incremental cost of the proposed standards of
performance is not great, the combined cost of State and standards of
performance regulations is appreciable.
101
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Table VI1-5
SAMPLE STATE EMISSION LIMITATIONS
Kgs/Hr. (Lbs/Hr.)
g
Pennsylvania
Illinois6
Ohio6
Texas
Indiana
New York
TOTAL
Federal Proposal
% U.S.
Furnaces
31
10
11
8
5
_JL-
70
Furnace Size
25 Tons per heat
Carbon Steel1
3.9 (8.6)
3.4 (7.5)
7.3 (16.1)
19.7 (43.4)
7.3 (16.1)
6.6 (14.6)
2.7 (6.0)
Alloy2
9.7 (21.4)
2.4 (5.2)
4.6 (10.1)
22.6 (49.9)
4.6 (10.1)
4.2 (9.2)
1.9 (4.3)
100 Tons per heat
Carbon Steel3
15.5 (34.3)
7.2 (15.8)
18.2 (40,2)
46.5 (103.0)
18.2 (40.2)
16.6 (36.7)
10.9 (24.1)
Alloy4
38.9 (85.7)
5.0 (10.9)
11.6, (25.6)
53.4 (118.0)
11.6 (25.6)
10.5 (23.1)
7.8 (17.1)
NOTES:
1. 3.5 Hour Heat, 50,000 SCFM
2. 7.0 Hour Heat, 125,000 SCFM
3. 3.5 Hour Heat, 200,000 SCFM
4. 7.0 Hour Heat, 500,000 SCFM
6.
Concentration standard
Mass Standard
7. Stack Height Correction Not Applied
8. Concentration standard of 0.004 gr/dscf on the control device and assumina KM efficiency nf canoiv hoods
-------
Estimates of annual steel capacity from all types of furnaces
totaled 157 million ingot tons in 1971.^ ' The median estimated for
1976 is 166.9 million ingot tons.v ' It is anticipated that the
(36)
electric furnace share of this volume will be 17. 1%, v ' or 29.5
million ingot tons. This is an increase of 5.5 million tons over the
(34)
estimated 1971 capacity v .
The investment required for each incremental ton of steel made
is estimated at $246 per ton up to 16 million tons. The amount
(37)
required for BOF or electric furnaces is $76 per ton.v ' Since 5.5 million
more tons of new electric furnace capacity and 0.8 million tons of
replacement capacity will be required in the five-year period, the total
cost will approximate $480,000,000. In recent years carbon steel has
made up about two-thirds of electric furnace production. Assuming average
tap to tap cycles of 3.5 and 7 hours for carbon steel and alloy, respectively,
and 7,920 operating hours a year, 330 tons of alloy capacity and 320 tons
of carbon steel capacity will be required each year.
In order to simulate the economic effect on the industry of the
320 tons of carbon steel and 330 tons of alloy capacity as well as
50 tons of each as replacement capacity, the furnace distribution shown
in Table VII-6 was used. For the building evacuation configuration for
alloys and the direct evacuation plus canopy hood for the carbon steel
shops, the required control investment of $18,670,000 amounts to an
additional 19% over the basic $96,000,000 cost per year of production
103
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Table VII-6
INDUSTRY-WIDE AIR POLLUTION CONTROL COSTS
Strategy I1
Furnaces
Carbon Steel:
20 100 tons/heat
1@ 65 tons/heat
20 50 tons/heat
Sub-Total
Alloy:
20 65 tons/heat
20 50 tons/heat
60 25 tons/heat
Sub-Total
Grand Total
Grand Total, with Depreciation
(1) Strategy 1 involves direct evacuation and canopy hoods for carbon
steel furnaces, and building evacuation for alloy units.
(2) Strategy 2 involves total building evacuation for both types.
(3) Without depreciation.
Strategy 2
Investment
$3,000,000
1,120,000
1,740,000
$5,860,000
$3,960,000
3,200,000
5,650,000
$12,810,000
$18,670,000
Annual Cost
$ 640,000
233,000
390,000
$1,263,000
$ 816,000
667,000
1,123,000
$2,606,000
$3,869,000
$5,114,000
Investment
$ 5,500,000
1,980,000
3,200,000
$10,680,000
$ 3,960,000
3,200,000
5,650,000
$12,810,000
$23,490,000
3
Annual Cost
$1,195,000
388,000
647,000
$2,230,000
$ 816,000
667,000
1,123,000
$2,606,000
$4,836,000
$6,402,000
-------
equipment with no controls. The annual cost, with depreciation added
back in, amounts to $2.00/ton of carbon steel'and $8.OS/ton for alloys
in Strategy 1, which involves building evacuation for alloy and canopy
hoods with direct evacuation for carbon steels. Strategy 2, which
involves building evacuation for both product groups requires a 261
greater investment and the annual costs with depreciation added back
in are $3.65/ton for carbon steel and still $8.05/ton for alloys.
Considering the significant difference in cost and the slight
improvement in control, it appears unjustified to set a standard which
would require total building evacuation for both product groups.
The annual costs for the canopy hood combinations amount to
only about two to four percent of the product values. With the
ending of the Phase Four price controls it will be possible to pass
this cost forward to the steel consumer. The ending of Phase Four
controls should also ease the capital availability problem which has
plagued the steel industry the last few years. Rate of return on
capital has been difficult to raise. However, with profits regaining
a normal level, availability of capital should improve.
105
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Page Intentionally Blank
-------
VIII. ALTERNATIVE STANDARDS
This chapter discusses the alternatives from which the draft
standards of performance were selected for presentation to the National
Air Pollution Control Techniques Advisory Committee meeting on January 9,
1974. Obviously, the objective of the standard of performance for
partfculate matter is to minimize the total mass of emissions which a
facility releases to the atmosphere. Viable alternatives considered
included a concentration limit and standards based on a mass limit.
Two overall approaches were considered possible: a single standard for
both carbon and alloy shops or separate standards for carbon and alloy
shops. Alternatives 1 through 4 in section A were considered for both
carbon and alloy shops and can be used in any combination. Alternative
5 of section A was developed as a separate standard for alloy shops.
The alternatives considered are grouped according to pollutant and source
of emissions.
A. Alternate Standards, for Parti cul ate. Matter _and_j/i_sibTe Emissions
from the Electric Arc Furnace ' '
1 . Alternative No. 1 J/
This option would limit emissions to the atmosphere as follows:
. No more than 0.05 kilogram of particulate matter per hour per
metric ton of furnace capacity (0.10 pound per hour per ton).
-/The roof of the building housing the furnace(s) must be sealed (building
evacuation) to insure capture of all emissions by the control system.
The numerical value of the particulate standard is based on 0.003 grains
per dry standard cubic foot (gr/dscf) in an exhaust gas volume of 4000
standard cubic feet per minute per ton of furnace capacity (scfm/ton).
107
-------
. Less than 10 percent opacity visible emissions, excluding
uncombined water, from the air pollution control device,
. No visible emissions, excluding uncombined water, from the
building housing the electric arc furnace(s) except for two
minutes in any one hour.
a. Advantages .
1} This option is consistent with section 111 of the Clean
Mr
2} A sealed building roof (BE) which the limitation on
visible emissions from the building requires, insures
nearly 100 percent capture of emissions from the furnace.
3) The base concentration of 0.003 gr/dscf includes some
buffer since outlet parti cul ate loadings at three alloy
shops have been measured at or below 0.0013 gr/dscf.
4} The mass standard will restrict the air flow rate of the
control system thereby minimizing total emissions. For
fabric filters (the predominant type of control device
•used) a higher flow rate results in a comparable increase
in the mass rate of emissions.
-'Standards of performance are to reflect "the degree of emission limitation
achievable through the application of the best system of emission reduction
which (taking into account the cost of achieving such reduction), the
Administrator determines is adequately demonstrated." The standard is
based on outlet particulate loadings from fabric filters measured by EPA
Method 5 at three plants and data on control system air flow rates for
existing well controlled plants.
108
-------
5} The units of this option require use of "best control"
Independent of the varying cycle length for this batch
process. (See Chapter V for a complete review of the
alternative units.)
b. Disadvantages.
1} This option, when applied to furnaces producing carbon
steel, may result in higher total emissions to the
atmosphere than alternatives that allow an open building
roof because of the attendant emissions from generation
of power necessary to move the greater volumes of air
through the afr pollution control system.
2) Restriction of the air flow rate through the control
system, which may be necessary to achieve this standard,
might
a) hamper compliance with heat stress regulations
being developed by the Occupational Safety and Health
Administration (OSHA).
b) increase concentrations of air contaminants (including
dust and carbon monoxide) in the building. OSHA has
promulgated "Occupational Safety and Health Standards"
for air contaminants.
109
-------
3) All ventilation air must exit through the control device.
Forced draft of these large gas volumes consumes large
amounts of energy.
4) Without direct-shell evacuation (alloy shops), more
emissions and heat will have to be removed by ventilation
of the building (through the control system) than for
carbon steel production. Therefore, this candidate would
be slightly more stringent for alloy shops.
5) The lowest guarantee by a vendor for a fabric filter on
an electric arc furnace shop is 0.004 gr/scf.
6) Collection of dust from the large gas volumes required,
necessitates a high investment in the control system and
t
high operating costs.
2. Alternative No.2.&
This option would limit emissions to the atmosphere as follows:
No more than 9.0 milligrams of particulate matter per dry
standard cubic meter (0.0039 grains per dry standard cubic
foot) from the air pollution control device.
-'The first two alternatives require an efficient control device, the
third a direct-shell evacuation system, and the fourth an efficient canopy
hood. A building evacuation system can also achieve the standard.
110
-------
. Less than 10 percent opacity visible emissions, excluding
uncombined water, from the air pollution control device.
. No visible emissions, excluding uncombined water, from the
building housing the electric arc furnace(s) except as
noted below.
. No more than percent average opacity of visible emissions,
excluding uncombined water, from the building directly above
and as a direct result of charging or tapping a furnace. The
emissions shall not exceed the charging or tapping period by
more than three minutes. (Data gathered after the January 9
NAPCTAC meeting were used to develop the level for this
alternative. These data are discussed in Chapter VI.)
a. Advantages.
1) This option results in the least total emissions to the
atmosphere when emissions from the generation of power
necessary to operate the air pollution control system are
considered.—'
2) Since this option permits open roof shops, it will avoid
any impact on control of heat stress of workers or
results of this type of analysis are highly dependent on the capture
efficiency of the canopy hood. For about 80 percent capture efficiency and
above, advantage 1 is true (see Chapter IV, Section C).
ill
-------
dust and carbon monoxide concentrations in the
building.-^/
3) Vendors have guaranteed 0.004 gr/scf for fabric
filters on electric arc furnace shops.
4) Outlet particulate loadings at several shops have
been measured at less than half the level of this
alternative.
5) This option will result in less consumption of
electrical power than Alternative No. 1, because
smaller quantities of gas must be moved by mechanical,
draft.
6} This option will have a lesser economic impact on
the steel industry than Alternative No. 15 because
smaller quantities of gas have to be cleaned.
7) This option is achievable by either of two control
systems.
8) This option will encourage use of a direct shell
evacuation system with its attendant reduction of
carbon monoxide emissions.
•2fIf a direct shell evacuation cannot be used or an equivalent system
cannot be developed for use with "reducing slags," the roof of the
building will have to be closed. In these cases, should higher ventilation
rates be required to meet OSHA's regulations, increased gas flow, cost
and energy consumption will result for the control system.
112
-------
b. Disadvantages.
1) This option is not consistent with the concept of
applying best technology (taking into account costs)
to the affected facility.-^/
2} The quantity of emissions that will result from this
option is not accurately known. Emissions from the
building are estimated from assumed values for
parameters such as the capture efficiency of the canopy.
No method exists to measure these parameters.
3} This option will allow some visible emissions from the
open roof. Measurement of these emissions is more
difficult than for those from a stack.
4} A standard based on average opacity would be more
difficult to enforce than a maximum. Continuous readings
would have to be made over the specified period and
synchronized with process operations.
3. Alternati ve No. 3.-
This option would limit emissions to the atmosphere as follows:
— Alternative No. 1 will result in lower emissions from the electric arc
furnace shop than Alternative No. 2.
7/
—'This candidate would require the same control systems as Alternative
No. 2. Only the method of enforcing use of an efficient canopy hood or
equivalent is changed.
113
-------
. No more than 9.0 milligrams of particulate per dry standard
cubic meter CO.0039 grains per dry standard cubic foot) from
the air pollution control device.
. Less than 10 percent opacity visible emissions, excluding
uncombined water, from the air pollution control device.
. No visible emissions, excludtng uncombined water, from the
building housing the electric arc furnace(s) except from
the building directly above and as a direct result of .charging
or tapping a furnace. The emissions shall not exceed the
charging or tapping period by more than three minutes.
. A canopy hood shall be installed above each furnace. The
hood should be designed according to the equations and criteria
in sections 4.2.3 and 5.4.4 of Steel Mill Ventilation. May 1965,
published by the Committee on Industrial Hygiene, American"Iron,
and Steel Institute. Other equipment may be used if demon-
strated to the Administrator's satisfaction that it will capture
at least an equivalent amount of the furnace emissions during
charging and tapping.
a. Advantages.
1} All the advantages for Alternative No. 2 apply.
2) Measurement of visible emissions from a building roof
is not required.
114
-------
b. Disadvantages.
1) Disadvantages 1 and 2 for Alternative No. 2 apply,
2) An "equipment" standard Is not consistent with the
"emission limitations" concept in section 111 of
the Clean Air Act.
\
3) This option presumes a canopy hood designed in this
manner will always achieve a capture efficiency of
81 percent or greater. In reality, the efficiency
of any such hood cannot be accurately determined.
4. Alternative No. 4.^
This option would limit emissions to the atmosphere as follows:
. No more than 9.0 milligrams of particulate per dry standard
cubic meter (0.0039 grains per dry standard cubic foot).
Less than 10 percent opacity visible emissions, excluding
uncombined water, from the air pollution control device.
same control system would be required as for Alternative No. 1,
except there is no restriction on gas volume.
115
-------
No visible emissions, excluding uncombined water, from the
building housing the electric arc furnace(s) except for two
minutes in any one hour.
a. Advantages.
1] This option will avoid any conflict with considerations
of heat stress of workers or dust and carbon monoxide
concentrations in the building. (This option does not
restrict the ventilation rate for the building.)
2) A sealed building roof, which the standard requires,
insures nearly 100 percent capture of emissions from the
furnace.
3) Vendors have guaranteed 0.004 gr/scf for fabric filters
on electric arc furnace shops.
4} The standard is clearly achievable since, outlet
particulate loadings at several shops have been measured
at less than half the level of this alternative.
b. Disadvantages.
1) This option, which does not restrict the air flow rate
through the control system, permits high mass emission
rates from fabric filters, the predominant type of control
device used.
2) Disadvantages 1, 5 and 6 for Alternative No. 1 apply.
116
-------
5. ATIternative No. 5. (for alloy steel production only)—'
This option would limit emissions to the atmosphere as follows:
No more than 0.065 kilograms of particulate per hour per
metric ton of furnace capacity (0.13 pound per hour per ton).
Less than 10 percent opacity visible emissions, excluding
uncomblned water, from the air pollution control device.
No visible emissions, excluding uncombined water, from
the building housing the electric arc furnace(s) except for
two minutes in any one hour.
a. Advantages.
1) All the advantages for Alternative No. 1 apply.
2) This option allows higher ventilation rates which will
remove additional heat and pollutants (normally captured
by a direct shell evacuation system in a carbon shop)
from the shop atmosphere.
b. Disadvantages.
1) Disadvantages 1, 2» 4, 5 and 6 for Alternative No. 1 apply.
9/
-* This candidate 1s the same as Candidate No. 1 except the numerical
value of the particulate standard 1s based on an exhaust gas volume of
5000 scfm/ton.
117
-------
2} This option would not provide as much incentive for industry
to minimize air flow rates as Alternative No. 1.
B. Alternative Standards for CarbonMonoxide Emissionsfrom the Electric Arc
Furnace
1. Alternative No. 1.
Do not promulgate a standard of performance.
a. Advantages.
1} Limited information is available to define a standard.
The contribution to CO emissions from sources other than
the furnace and the process parameters that affect CO
formation in a furnace are not well known.
2) Accurate measurement of the mass rate of carbon monoxide
emissions* as a standard would require, is difficult.
Because of extreme and rapid variation, both concentration
and gas flow must be continuously measured to accurately
determine mass emissions during a compliance test. Continuous
measurement of gas flow may require an in-line meter in the
control system duct.
3} If a particulate standard is proposed that requires or
encourages use of a direct shell evacuation system, carbon
monoxide emissions will be minimized without a standard.
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b. Disadvantages.
1) A standard would require use of a direct shell evacuation
system. This system can achieve a substantial reduction
not only in carbon monoxide emissions but also parti culates.
2) A standard may result in even better control than required.
Control of carbon monoxide with present systems is inci-
dental to the basic function of the system. Without a standard
future systems may not be designed to optimize control of CO.
2. Alternative No.
This option would limit emissions to the atmosphere as follows:
No more than 0.3 kilogram of carbon monoxide per hour per
metric ton of furnace capacity (0.6 pound per hour per ton)
a. Advantages.
1) This option is consistent with the intent of section 111
of the Clean Air Act as amended to require the best
control technology.
2) Emissions measured by EPA will support this limitation.
3) The disadvantages for Alternative No. 1 are advantages
for this alternative.
— A direct shell evacuation system would be required. The standard
would not apply to furnaces where a "reducing slag" is used to produce
alloy steels.
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b. Disadvantages.
The advantages for Alternative No. 1 are disadvantages for
this alternative.
C. Visible Emissions from Handling of Dust Collected by theFabric Filter
1. Alternative No. 1.
This option would limit emissions to the atmosphere as follows:
Less than 10 percent opacity visible emissions from on-site
handling of dust collected by the air pollution control device.
a. Advantages.
1) This option requires the best technology, consistent with
section 111 of the Clean Air Act, as amended.
2) This option would require adequate procedures for removing
dust from the control device to prevent escape to the
atmosphere.
b. Disadvantage.
Dust which escapes to the atmosphere as it is removed from
the control device is probably a minor source of total
emissions from a steel plant.
2. Alternative No. 2.
Do not promulgate a standard of performance. The advantages and
disadvantages are the inverse of those above.
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D. Discussion of the Alternative Standards
A concentration limit alone will not minimize emissions since the
mass rate of emissions is equal to the product of concentration and air
flow rate (grams/dscm x dscm/hour = grams/hour). A mass limit does
minimize emissions for a given time period. There are, however, additional
factors which make both, types of limits viable options. Factors such as:
1) the potential Interface between air pollution and occupational health
standards when air flow rate is limited, and 2) economic incentives for
industry to limit the flow rate without government regulations, are
presented in the advantages and disadvantages of the alternative standards
considered in this chapter.
Alternatives numbered 1 and 5 for the standard for particulate matter
limit the mass rate of emissions, which indirectly restricts the shop
ventilation rate. The limits were "back-calculated" based on an emission
concentration of 0.003 gr/dscf. (Results of the only facility sampled
by EPA showed average emissions from Plant A, an alloy shop, of 0.0013
gr/dscf. Two tests of other plants conducted by industry showed average
emissions of even less.) Admittedly lenient, a basis of 0.003 grains per
dscf includes a buffer which should accommodate any fluctuation in the
discharge concentration from a fabric filter, that might result from the
higher inlet concentrations found in high productivity carbon steel shops.
The second basis for alternatives 1 and 5 is the air flow rate.
Before selecting a numerical level the best method of expressing the flow
rate had to be determined. Two alternatives are furnace capacity, and
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production rate. Ventilation rates provided by operators of shops with
closed roofs are presented as a'function of both in Figure VIII-1. The
correlation was calculated by the least squares method and the correla-
tion measured by the root-mean square of the y-deviations. Although
neither correlation is good, the correlation with furnace capacity is
slightly better. Since production rate is dependent on both furnace
capacity and heat length (productivity), it should have shown the best
correlation ff productivity were a significant factor in determining
ventilation rates. This shows that shop productivity is not a large
factor, however, furnace capacity still does not correlate well. About
the same degree of correlation results from an examination of ventilation
rates and the volume of the shop buildings. In the absence of a better
yardstick, furnace capacity is used as the basis.
The 4000 scfm/ton basis for alternative 1 is based on ventilation
rates (presented in Figure III-6) of existing plants or those under
construction. Seven of these 12 plants use less than 4000 scfm/ton and
three are just above this level. One plant under construction is designing
a new closed roof control system with a ventilation rate of 4100 scfm/ton.
The volume restriction is increased to 5000 scfm/ton for alternative
5. If the data for ventilation rates of alloy shops with closed roofs
are considered, only three of seven shops use less than 4000 scfm/ton.
Five use less than 5000 scfm/ton and one is slightly greater than this
value. Also, the only existing closed roof carbon shop uses a maximum
flow of 5000 scfm/ton during periods when the DSE system is disconnected.
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24
20
16
12
100
200 300
FURNACE CAPACITY, tons
400
500
24
20
16
.12
'0 20 40
60 80 100 120 140
PRODUCTION RATE, tons/hr
160 180 200 220
Figure VHI-l.Ventilation rate correlations
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An average flow of 3900 scfm/ton is achieved by a reduction in flow
when the DSE system is operating. A comparable alloy shop without a
DSE system would need the maximum flow at all times.
A carbon steel shop may have an emission factor as much as six
times that of an alloy steel shop. Although those knowledgeable in the
design and operation of fabric filters generally agree that outlet
concentrations should be nearly independent of the inlet concentration
(after the fabric is precoated and the fabric cleaning variables are
suitably adjusted)s only one published article was found that discusses
this topic. The author stated that a ". . . fabric filter might well
operate with the same outlet concentration when the inlet loading changed
f!3\
tenfold."v ' Because of this limited amount of available information,
the alternative of 0.003 gr/dscf was considered reasonable for the
shop alone.
A disadvantage of a more liberal concentration basis is that the
designer of the air pollution control system might well absorb the
higher permissible emissions by designing for a higher flow rate through
the control device, thereby, significantly increasing mass emissions.
(Since the mass emission rate is the product of the concentration and air
flow rate, an increase in a mass standard will allow an increase in either
variable.) A designer is not likely to change his judgment of the
concentration he expects from a fabric filter because the standard has a
more lenient buffer on concentration. His judgment would be that he can
use a higher air flow rate.
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For alternatives 2 through 4, the alternative of 0.0039 gr/dscf was
considered. This alternative will not result in a significant change in
the air pollution control system required. The same type and design of
control device (fabric filterl will be installed. A number too lax,
however, could permit a decrease in emphasis on maintenance of the control
device over a long period of time. The 0.0039 gr/dscf level corresponds
to the lowest level that has been guaranteed by vendors of fabric filters.
E. DraftStandards of Performance
The standards of performance presented to the National Air Pollution
Control Techniques Advisory Committee on January 9, 1974, were selected
from the previously discussed alternatives. The selection of one
alternative over another necessarily involves matters of judgment on
issues which cannot be precisely quantified. Consequently no one alter-
native is entirely without disadvantages, but when all factors were
considered some alternatives were clearly more viable than others. The
standards presented at the January 9 meeting consisted of the alternatives
which were judged to be the more viable. The alternatives selected were
alternative 2 for the standard of particulate matter and visible emissions,
alternative 1 of the alternative standards for carbon monoxide emissions
and alternative 1 of the alternative standards for visible emissions from
the dust handling equipment. Since the January 9, 1974, NAPCTAC meeting
the draft standards of performance have been revised to the proposed
standards discussed in Chapter II.
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1. The Draft Standards of Performance.
The draft standards presented at the January 9 meeting suggested
limitation of emissions to the atmosphere as follows:
. No more than 9.0 milligrams of participate per standard
cubic meter (0.0039 grains per standard cubic foot) from the
air pollution control device.
. Less than 10 percent opacity visible emissions, excluding
uncombined water, from the air pollution control device.
. No visible emissions, excluding uncombined water,
from the building housing the electric arc furnace(s) except
as noted in the next paragraph.
. No more than percent average opacity of visible
emissions, excluding uncombined water, from the building
directly above and as a direct result of charging or tapping a
furnace. The emissions shall not exceed the charging or tapping
period by more than three minutes.
Less than 10 percent opacity visible emissions from on-site
handling of dust collected by the air pollution control device.
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2. Reasonsfor Selection of These Standards of Performance.
There are two distinct phases in the selection of a standard of
performance. First, the system which best controls air pollution
within the intent of the Act must be identified. Second, the
regulation must be written to require use of this best system of
air pollution control or equivalent alternative methods, yet not
preclude improved control methods.
The proposed standard is based on installation of a direct shell
evacuation (DSE) system in combination with an efficient canopy hood.
However, it can also be achieved with a building evacuation (BE)
system. If the owner elects to use the combination system, the roof
can remain open for supplemental ventilation of the furnace shop.
a. The reasons for basing the standard on this combination system
as representative of best emission reduction are:
1. The "total environmental impact"-^ of the combination
system with an open roof on the shop is potentially less
than that from a closed roof system.
—' "Total environmental impact" is the sum of particulate emissions from
the electric arc furnaces and all incremental emissions, particulate, S0£
and NOX, from a new coal-fired power plant which provides electricity to
run the air pollution control system. The power plant is assumed to meet
the standards of performance for new fossil-fueled power plants. This
analysis is highly dependent on the value assumed for the capture efficiency
of canopy hoods. (Actual measurement would be extremely difficult.) The
open roof system is optimum for hoods of 81 percent or greater capture
efficiency.
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2. This standard permits natural draft ventilation through
the open roof thereby avoiding any potential impact of
standards of performance on existing or pending occupational
12/
safety and health regulations.—'
Those operators of alloy steel shops who cannot use" a
direct shell evacuation system may elect to use a building
evacuation system. Should higher ventilation rates be
required to meet OSHA regulations, Increased gas flow, cost
and energy consumption will result.
3. , This standard results in a lower economic impact than if
all shops were restricted to a BE system.l^/
One of many controllable variables used to assist in meeting
standards for "Occupational Safety and Health" is the ventilation rate
of the workers' environment. The value and amount of ventilation
necessary to achieve specific standards is very difficult to quantify.
This 1s particularly true for heat stress regulations still under
development and which will be affected by climate.
Supplemental ventilation through an open roof minimizes air
flow through the control device. This results in a smaller capital
investment in the control device, lower operational costs and lower
energy consumption.
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4. This standard will require less energy consumption than
if all shops were restricted to a BE system.
5. This standard provides limited flexibility, as an operator
may use either of two capture systems.
6. The 9.0 milligram per cubic meter (0.0039 grain per standard
cubic foot) limit on particulate matter emissions from the
control device is based on results of measurements by EPA.
7. The visible emission limitation on the control device is
supported by EPA's observations.
8. Control of carbon monoxide emissions will be maximized
because this standard encourages a DSE system. (See page 111-3).
9. The visible limitation to minimize reentrainment of dust
collected by the control device is supported by EPA's
observations.
b. The wording of this regulation was selected for the following
reasons:
1. Concentration units were selected for emissions from the
control device to allow the operator the latitude to ensure good
capture velocity at the canopy hood thereby minimizing emission
losses through the open roof. Mass units would limit gas flow through
the control device.
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2. The opacity limit on emissions from the control device
provides an easily enforceable standard minimizing the time
and expense of periodic performance tests.-
3. Absolute prohibition of visible emissions from the building
roof for most of the furnace cycle ensures that the DSE system
will be operated. For example, a standard of "less-than-10-
percent-opacity," would not preclude emissions from escaping the
furnace and becoming heavily diluted within the building before
passing through the roof.
4. Two alternatives were considered to ensure maximum control
during charging and tapping. These are a visible emission
limitation and design specifications for a canopy hood. A
visible standard is recommended because it does not discourage
innovative improvements in design of future control systems and
a standard that specifies a type or design of equipment has
questionable legality.
5. This standard is based on the average opacity of emissions
(the arithmetic average of reading every 15 seconds, including
zeros) during the charge, or tap, and three minutes after. A
charge is defined as the period when the furnace roof is open and
a tap as the period when the furnace is tilted to tap molten steel
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An alternative to a limit based on "average opacity" is a maximum
visibility that shall never be exceeded. This, of course, is by
far the most common type of opacity regulation. In the present case,
however, the concept of average opacity has an advantage.
This averaging technique acknowledges that the opacity of
emissions may have large and rapid variations which may not relate well
to mass emissions. Average opacity provides a more quantitative
measure of emissions. The total mass of emissions from the building
is a function of both the opacity and duration of emissions. The
period specified over which the visibility of emissions is averaged
is generally longer than the duration of the emissions. Therefore,
if the emissions were 50 percent opacity for one-half "the period and
0 percent for the other half of the period, the average opacity is
25 percent. If they last for three-fourths of the period, the
average is 38 percent. In both examples, the maximum opacity is 50
percent; therefore, the maximum limit does not relate to the total
quantity of emissions. This average opacity approach has added
importance because opacity standards are the only restriction placed
on charging and tapping emissions.
6. The opacity limit for on-site handling of dust collected
by the control device provides an easily enforceable standard
that assures proper precautions during transfer of this fine
particulate.
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3. Econonric Impact.
As shown in Chapter VII, the per ton cost of air pollution control
is approximately twice as great for a small shop with one 25 ton furnace
as for a larger shop with three 100 ton furnaces, yet it amounts to
only 2 to 4 percent of the current selling price of steel.
With the current high demand for steel and the prospective relaxation
of price controls, there should be no problem in passing along the entire
cost of both State standards and standards of performance.
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IX. ENFORCEMENT ASPECTS OF THE PROPOSED STANDARD
A. 6enera]_
One difficult situation that may be encountered during enforcement
of the proposed standards of performance is an affected facility located
in the same building with other sources of particulate matter emissions.
Emissions from these other sources may mix with those from the affected
facility. The proposed regulation specifies that when the other emissions
are from existing furnaces, compliance may (subject to approval by the
Administrator) be demonstrated for the new furnace without a test. The
operator must show that the control system is equivalent or superior to
that which would be required if the furnace were installed in a new shop.
Another option for the operator is to base compliance on control of all
the sources.
When the extraneous emissions are from sources other than furnaces,
the plant operator may choose from the following options.
1. Base compliance on control of all emission sources.
2. Shut down the other emission sources during the compliance
test.
3. Use a method acceptable to the enforcement agency to
compensate for the effect of the other emission sources on
results of the compliance test, or
4. Any combination of the above.
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B. Determination of Compliance Hith the Concentration Standard
The control system installed to comply with the proposed standards
may have any of several configurations. One control device may serve
several affected facilities, or several control devices may serve one
affected facility. Where several control devices are involved, the
proposed regulations provide for use of a flow-weighted average concentra-
tion to determine compliance. For the other case, the regulation provides
that a common compliance test of the single control device is sufficient
to show compliance for all the affected facilities. These provisions
allow the proposed standards to be reasonably enforced without restricting
options for the design of control systems.
From the standpoint of measuring the concentration of emissions,
effluents containing particulate matter can be placed into three broad
categories: (1) those confined within a single stack, (2) those
exhausted through multiple stacks, and (3) those not constrained within
a stack or duct after exiting the control device. The enforcement
aspects of oerformance testing vary according to the category and are
discussed below.
(1) Effluent confined within a singlestack. The methods specified
in 40 CFR 60 (36 FR 24876 - Methods 1, 2, 3, 4S and 5) provide specific
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guidelines applicable for measurement of emissions from a stack.
Unlike existing sources which sometimes require deviation from
optimum sampling procedures due to the physical limitations of the
facility, new sources can and should be designed for optimum
accuracy of sampling. As an example, an optimum sampling location
is 8 or more diameters downstream and 2 or more diameters upstream
from anything that might disturb the flow of exhaust gas such as
an orifice or elbow in the line. Although the reference methods
allow deviation from this optimum criteria, new facilities should
be designed for accurate and precise results from sampling. Further-
more, utility services and sample access points can also be
incorporated in the design of new sources to facilitate sampling.
(2) Effluent exhausted through multiple stacks. Actual test
procedures are similar to category 1 except the number of samples
required and the attendant costs may become excessive. In such a
case, a limited sampling plan may be suggested by the enforcement
agency. Possible variations are: a) particulate tests of select
representative stacks with concurrent velocity measurements at
similar stacks; b) particulate tests on a limited number of stacks
combined with an evaluation of design and operating parameters to
determine comparability between those stacks sampled and those not
sampled.
(3) Effluent not constrained within a stack. This category
will include emissions from open or pressure baghouses. Performance
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test methods applicable to these configurations have not been
specified due to the limited experience and the lack of proven
techniques available for testing.
Several problems are involved in such testing. First, due to
large (and sometimes multiple) cross section areas through which
emissions are exhausted, it is not practical to sample at enough
points to totally define the flow profile. To overcome this
limitation, assumptions are made to determine the minimum number of
samples necessary to estimate the actual flow characteristics. When
their locations are determined, the sub-areas they represent may
then be sampled with Method 5 (or other sampling techniques, including
high volume sampling). These individual points may be sampled by
traversing, or by simultaneous sampling at multiple points. One
scheme is to draw a high volume sampler across the horizontal cross-
section of a roof monitor. Another, used in the aluminum industry,
Involves extraction of effluent from representative sampling points
by use of a permanent multipoint sampling manifold. The manifold
discharges into a single stack which can then be sampled with
conventional techniques.
A second problem results from low flow rates common in large
area discharges. They often cannot be measured with conventional
equipment. Low flow rates preclude accurate isokinetic sampling, and
determination of actual volumetric flow rates. This problem is
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usually resolved by determining average velocities with sensitive
measuring devices and then sampling at this average rate. Volumetric
flow rate may be determined in a similar manner, (If dilution air is
not present, volumetric flow rate may be more accurately determined
on the inlet side of the control device.)
Use of dilution air presents a third and equally serious impediment
to accurate emission measurements. Since a concentration limit (mass
per volume) requires a correction for dilution air and a mass emission
limit requires measurement of actual volumetric flow rates, in either
case it is necessary to measure flow rates. This may prevent, or at
least will seriously hamper accurate emission measurements.
Due to these problems, the accuracy and precision attainable in
making mass determinations appears limited and, in fact, certain source
configurations totally defy representative sampling. For most sources,
however, plans can be developed which should yield sufficiently accurate
data to determine compliance. Due to the potential cost, the owner and
the enforcement agency should consider and agree, prior to construction
of a new facility, on a specific means for determining compliance.
EPA is now examining typical configurations of exhaust systems
being marketed to determine optimum test criteria. Until such criteria
are available, owners should select exhaust systems which will allow
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representative sampling in accordance with 40 CFR SO.
C. Determination of Compliance With Visible Emission Standards
Generally, visible emission limitations are standards that
do not require that the plant be notified before a determination of
compliance is made. Their prime function is to insure that air
pollution control equipment is properly operated and maintained.
Enforcement of the standards for handling of dust collected by
the control device and on emissions from the electric arc furnace
shop (except during charging and tapping) require some knowledge of
what operations are actually occurring during the test. Since dust
removal from the control device, charging, and tapping operations are
noncontinuous, the observer will have to determine when these operations
are scheduled before visiting a plant for opacity readings or determine
if such operations have been in progress during observations conducted
without prior notice.
The visible emission standards limit the opacity during specifically
defined charging and tapping periods. To properly enforce these standards,
the periods of observation must be correlated with process operations
which are actually taking place.
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D. Instal1ationand Operatlon of an Opacity Monitoring Device
EPA proposed performance specifications for opacity monitors on
September 11, 1974 (39 FR 32852). These specifications are based on
commercial instruments now available which are capable of measuring
opacity within a narrow path of 50 or more feet in Jength. Instruments
which are installed and operated in accordance with the specifications
will produce reliable opacity data. Effluent discharged through a
stack or duct can be readily monitored.
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X. MODIFICATIONS
If the equipment or operation at an affected facility is altered
in a manner which increases air pollution, that existing facility may
become subject to the standards of performance in accordance with
section lll(a)(4) of the Clean Air Act as amended. This provision
was interpreted in §60.2 of 40 CFR 60.
A change in the type of steel produced may be considered a modification
if it increases the emission rate. An example would be a change from
carbon to alloy steel production which may preclude further use of a
direct shell evacuation system. A second possibility is increasing the
transformer capacity to increase production. These changes, although
economical ways of meeting market demands or increasing production with
minimal investment, may still be considered modifications thereby rendering
the facility subject to the standards of performance.
The following would not be considered a modification:
A. Changes in raw materials, types of scrap steel or use of
slags to produce steels for which the furnace was originally
designed.
B. Routine replacement of furnace linings, or other components
of the furnace and air pollution control system.
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The impact of upgrading an existing system will vary with each case.
The ease of design and cost of hoods or other equipment for efficient
capture of pollutants may vary significantly depending on the configuration
of the building housing the furnaces.
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XI. MAJOR ISSUES CONSIDERED
Development of the alternative and proposed standards of performance
discussed in Chapter VIII and Chapter II revolved around several key issues.
These issues are:
A. What is the proper environmental and energy balance when the
benefit of increasingly efficient air pollution control is
weighed against the pollution caused by generation of the
additional power required to achieve the better control?
B. Should improved air pollution control be required at the
expense of ventilation air in an electric arc furnace (EAF)
shop. If so, at what point is it incompatible with regulations
of the Occupational Safety and Health Administration to protect
and enhance the worker's environment?
C, Are visible emission standards applied to the shop the best
method of assuring good capture of charging and tapping emissions?
D. How can a standard be enforced for a new furnace installed in
an existing shop where emissions from the furnace often co-mingle?
These issues are discussed below:
A. Issue No. 1. The ProperBalance BetweenControl ofAir Pollution And
Emissions Caused by Generation ofthePowerRequired For
Air Pollution Control
Chapter IV shows that a building evacuation (BE) system minimizes the
particulate emissions from EAF's; however, it also requires the control device
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to clean a much larger volume of air than competitive control systems.
Handling this large volume of air requires large amounts of energy which
of course, indirectly results In more air pollution at the power plant which
generates the energy. A comparison of the sum of emissions from EAF's and
from generation of the power required by control systems for a BE and direct
shell evacuation-canopy hood (DSE-CH) system is presented in Chapter IV
It revealed that these two systems are equivalent if the CH achieves slightly
over 80 percent capture of the emissions during charging and tapping of the
furnace.-' The basic question then is, can a CH reasonably be expected to
achieve over 80 percent capture efficiency? A BF system is required bv Alternative
Standards Number 1, 4 and 5 in Chapter VIII and a DSE-CH svstem can achieve
the control limitations of Alternatives 2 and 3.
No method or techniques exist to measure or even to reliably estimate
the capture efficiency of a CH. Visual observations show the capture
efficiency varies considerably with each charge or tap. The noods appear
to capture from 50 to 90 percent of the emissions. It seemed reasonable,
although not certain, that CH's may indeed capture over 80 percent of
charging and tapping emissions. If so, a standard that requires BE might
Indirectly increase the air pollution generated by the manufacture of steel
• With BE the roof ot a shop 1s closed and all air which leaves the
shop must pass through the control device. The capture efficiency is 100
percent. With CH's, some emissions escape capture and are discharged
through the monitors on the roof of the shop. If the monitors are closed,
all ventilation air must discharge through the control device, which
significantly increases the energy required to control the shop.
-------
because of the contribution from the power plant. The lower energy
requirements of the DSE-CH system also make it desirable. Consequently,
the standard being oroposed will allow use of the DSE-CH system.
B. IssueNo. 2. Restriction of Shop Ventilation
The total mass of emissions from an EAF is directly proportional to
the volume of gas which must be cleaned, as explained in Chapter III. Since
the mass emitted is equal to the product of the volumetric air flow and its
concentration of particulate, a regulation expressed in mass units
(Alternatives 1 and 5 in Chapter VIII) will limit the amount of air flow.
Alternatives 2, 3 and 4, for a standard on particulate matter, based on
concentration limits, place no restriction on the plant operator. He may
use as high an air flow as he feels is necessary to ventilate the building.
There remains an economic incentive for a plant operator to minimize air
flow since the size, capital cost and operating cost of the control device
is directly proportional to the flow. Alternatives 2, 3 and 4 also allow
a DSE-CH system with an open roof on a shop. With this system, the air
flow through the CH must exceed some minimal value to insure good capture
of emissions. In this case, limiting the air flow through the control
device is of secondary importance since any losses from Inefficient
capture efficiency of the CH's are of far greater magnitude. Any decision
that a standard of performance should limit air flow through a BE system
would require a determination of the effect of reduced ventilation on
deterioration of the worker's environment.
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The Industry has indicated a very strong concern for their ability to
comply with an environmental standard that restricts the volume of ventilation
air and stm comply with regulations of the Occupational Safety and Health
Administration (OSHA). OSHA has promulgated the following standards for the
workers' envi ronment.* '
Material Concentration
3
Iron oxide fume 10 mg/m (.0044 gr/dscf)
Inert or nuisance dust
Resplrable fraction 5 mg/m3 1.0022 gr/dscf)
Total dust 15 mg/m3 (.0066 gr/dscf)
Carbon monoxide 50 ppm by volume
These concentrations are eight hour time weighted averages.
OSHA is also developing a standard for workers 1n hot environments.
Their "Standards Advisory Committee on Heat Stress" has recommended that
specific work practices be required if the wet bulb globe temperature (WBGT)
exceeds specified limits from 79 to 90, depending on workload and air
f39)
velocity.v ' The temperature would be calculated as a two hour average.
WBGT 1s calculated from the following equation:
WBGT = 0.7 WB + 0.3 GT
where:
WB «= the natural wet-bulb temperature obtained with a wetted sensor
exposed to the natural air movement
GT = globe thermometer temperature
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(A globe thermometer primarily measures radiant heat.)
Although high air ventilation rates can lower the temperature 1n an
electric arc furnace shop, they do not reduce the effects of radiant heat.
Other means available to protect workers from heat stress and permit
compliance with the standard ultimately promulgated are:
1. Decrease the number and duration of workers' exposures to the
hot environment.
2. Provide an air conditioned rest area to decrease the time weighted
average temperature.
3. Use portable fans to blow air on the workers.
4. Blow air ducted from outside the shop (and possibly cooled) on
the workers.
5. Use radiation shields,
6. Use protective clothing.
In correspondence with EPA, OSHA has Indicated that although they agree
some ventilation air 1s requisite to achieve any standard ultimately promulgated,
they do not have sufficient data to say how much. (They also point out
that other means such as those listed above are available to control heat
stress.)* '*^^ Neither is data available on pollutant concentrations 1n
a shop to determine the amount of ventilation required to meet OSHA's standards
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for dust and carbon monoxide cited above. The Industry has historically
used the maximum air flow rates that can be achieved by natural ventilation
to optimize the working environment at minimum cost, in hot climates,
these natural rates may be much higher than 4000 scfm/ton of furnace capacity
typical of most existing BE systems (see Figure III-6). Representatives of
the steel Industry have indicated that as much as 10,000 scfm/ton of furnace
capacity may be a prerequisite to complying with OSHA standards.
The data on ventilation rates for existing BE systems Indicates that
4000, when a DSE system 1s used to remove fumes and heat from a shop, or
5000 scfm/ton of furnace capacity would be reasonable limits for Alternative
Standards Number 1 and 5 presented 1n Chapter VIII. However, Alternative 2,
the draft standard, does avoid any possible conflicts over the auantitv
of ventilation air needed tor EAF shops.
C. Issue No. 3. Visible Emission StandardspntheShop
The standard being proposed allows a DSE-CH system and open monitors
on the roof of the shop to be used. This control system 1s satisfactory only
if the standard requires Installation of efficient CH's. Two alternatives
were discussed 1n Chapter VIII which would assure this. The first is
through specification of the design of a CH. A second way would be through
application of a visible emission standard to the shop during charging and
tapping. A specification or "equipment" standard may discourage Innovative
approaches to air pollution control and thwart advancement of technology.
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Unfortunately, the alternative of visible emission standards also has
disadvantages when applied to large open areas such as a monitor on an
EAF shop. Readings of opacity from such areas are difficult because the
emissions may diffuse over a large area before leaving the shop and the
plume emits at a low velocity. Collectively, they make the plume indistinct.
Another disadvantage is that enforcement officials will have to contact the
owner to obtain process data to assure that visible emissions occur only
during those furnace operations when they are permissible.
D. Issue No. 4. New Furnace in an Existing Shop
Many new EAF's will De installed in existing shops, in these cases or
if one of several existing furnaces in a shop is modified, emissions from
the new or modified furnace may be inseparable from the existing facilities'
emissions. This is primarily true for a BE system which may be used by a
shop producing alloy steel to meet the proposed standard. Emissions from
all the furnaces diffuse together in the roof area of the shop. A compliance
determination would be difficult, if possible at all. To insure collection
of the new or modified furnace's emissions, the entire shop will have to be
controlled; thus forcing control of existing sources. One alternative is
to apply the proposed standard only to grass roots shops, however, this
would significantly reduce the impact of the standard. Another alternative
149
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is to judge the facility in compliance (without a compliance test) if
a control system equivalent to that necessary for a grass roots shop is
installed. Even though this in essence requires an "equipment standard,"
which is of questionable legality for standards developed according to
section 111 of the Clean Air Act, no other viable alternatives were
identified. This alternative was selected for the proposed standard.
150'
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XII. REFERENCES
I. Annual Statistical Report - American Iron and .Steel Institute -
1972, published oy the American Iron and Steel Institute, p. 40.
2. Ibid., p. 58.
3. Iron and Steel Industry, prepared by Environmental Engineering,
Incorporated for EPA, Contract No, CPA 70-142, March 15, 1971,
p. 8-6.
4. Letter from George N. Stoumpas, American Iron and Steel Institute,
to Randy D. Seiffert, EPA, January 23, 1973.
5. Ref. 1, p. 15.
b. National Air Quality Standards Act of 1970, Report of the Committee
on Public Works, United States Senate, Report No. 91-1196, September 17,
1970, p. 16.
7. Ref. 3, p. 3-7.
8. ft Systems Analysis Studyof the Integrated Iron and Steel Industry,
prepared by Battelle Memorial Institute for the U. S. Department
of Health, Education and Welfare, National Air Pollution Control
Administration (predecessor to EPA), Contract No. PH 22-68-65,
May 15, 1969, pp. C-79 to C-83.
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9. Danlelson, J. A., Ed., A1r Pollution Engineering Manual, National
Center tor Air Pollution Control, PHS Publication No. 999-AP-40,
1967, pp. 248-249.
10. "Source Testing Report" tor Plant A, prepared Tor EPA by Roy F. Weston,
Incorporated, Contract No. 68-02-0240, January 1973.
11. Trenholm, Andrew R., EPA trip report, March 8, 1974.
12. Ref. 3, p. 2-24.
13. Beach, Q. H.s "The Stack Test—Final Proof of Non-Pollutlon,"
1n Proceedings of the Specialty Conference On: The User and Fabric
nitration Equipment, October 14-16, 1973, sponsored by the. Air
Pollution Control Association, p. 35.
14. Control Techniques for Carbon Monoxide Emissions From Stationary
Sources, National A1r Pollution Control Administration (predecessor
to EPA), Publication No. AP-b5, March 1970, p. 2-2.
15. Ref. 3, p. 8-7.
16, Report of emission tests conducted at Plant E from June 20 to
August 13, 1970, submitted by the company.
17. Ref. 8, p. V-62.
18, Ref. 3, p. 3-19.
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19. Ref. 8, p. V-67.
20. Environmental Protection Agency, "Standards of Performance for
New Stationary Sources," Federal Register, 36J247): 24888-24890,
December 23, 1971.
21. "Methods tor Determination of Velocity, Volume, Dust and Mist Content
of Gases," Western Precipitation Division of Joy Manufacturing Company,
Los Angeles, California, Bulletin WP-50, 1968.
22. Environmental Protection Agency," Standards of Performance for New
Stationary Sources," Federal Register, 36_(247): 24884, December 23,
1971.
23. Report of emission tests at Plants I and J» submitted by the owner,
December 1, 1972.
24. Report ot emission tests at Plant M, submitted by the vendor of the
control system, September 28, 1973.
25. Report of emission tests at Plant B, submitted by the Assistant Viee-
President, Engineering and Construction, for Plant B, October 10,
1972.
26. Report of emission tests at Plant C, submitted by the owner,
February 28, 1966.
27. Seiffert, R. D., EPA trip report for visits to Plants C and G,
March 23, 1973.
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28. Cuffe, S. T., EPA trip report for a visit to Plant F, December 17,
1973.
29. Letter from John E. Barker to Andrew R. Trenholm, EPA, May 3, 1974,
30. Letter from the owner of Plant E to Randy D. Selffert, EPA,
September 19, 1973.
31. Letter from the owner of Plant E to Andrew R. Trenholm, EPA,
March 22, 1974.
3H. Pfaff, Roger 0., "Emission Testing Report" for tests conducted at
Plant D on December 19, 1972.
33. Pfaff, Roger 0., "Emission Testing Report" for tests conducted at
Plant E on December 15-16, 1972.
34. Booz-Allen and Hamilton, AStudyofthe Economic Impact on the Steel
Industry of the Costs of Meeting Federal Air and Mater Pollution
Abatement Requirements, Part III, Ouly 27, 1972, Exhibit V.
35. Ibid., Exhibit VII.
36. Battelle Memorial Institute, A Cost Analysis for Air Pollution Controls
In the Integrated Iron and SteelIndustry, May 15, 1969, p. III-6.
37. Ref. 31, p. 35.
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3«. Department of Labor, 'Occupational Safety and Health Administration,
"Occupational Safety and Health Standards," Federal Register 33
(202): 22139-22142, October 18, 1972.
39. "Recommendations For a Standard for Work In Hot Environments -
Draft No. 5," prepared by the Standards Advisory Committee on
Heat Stress for OSHA, January 9, 1974.
40. Letter from John P. O'Neil, Department of Labor, Occupational
Safety and Health Administration, to James C. Berry, EPA, May 9,
1973.
41. Letter from John P. O'Neil, Department of Labor, Occupational
Safety and Health Administration, to James C. Berry, EPA, May 31,
1973.
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1 REPORT NO
EPA-450/2-74-005a
3 R ECl PI ENT'S ACCESS IOW NO
4 TITLE AND SUBTITLE
Background Information for Standards of Performance:
Electric Arc Furnaces in the Steel Industry
Volume 1. Proposed Standards
5 REPORT DATE
October 1974
6 PERFORMING ORGANIZATION CODE
7 AUTHOR(S)
B PERFORMING ORGANIZATION REPORT NO
9 PERFORMING ORGANIZATION NAME AND ADDRESS
U. S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
10 PROGRAM ELEMENT NO,
11 CONTRACT/GRANT NO
12 SPONSORING AGENCY NAME AND ADDRESS
13 TYPE OF REPORT AND PERIOD COVERED
Final
14 SPONSORING AGENCY CODE
IS SUPPLEMENTARY NOTES
16 ABSTRACT
This volume is the first in a series on the standard of performance for electric
arc furnaces in the steel industry. This volume provides background information
and rationale used in the development of the proposed standard of performance.
The economic and environmental impacts of the standard are discussed.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b IDENTIFIERS/OPEN 6NDED TERMS
c COSATI Field/Group
Air Pollution
Pollution Control
Steel Industry
Electric Arc Furnaces
Standards of Performance
Steel Making
Air Pollution Control
13 DISTRIBUTION STATEMENT
Unlimited
19 SECURITY CLASS (ThisReport)
Unclassified
21 NO OF PAGES
184
20 SECURITY CLASS (Thispage)
Unclassified
22 PRICE
EPA Form 3220-1 {9-73}
157
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