United States Office of Air Quality EPA-450 3-79-033
Environmental Protection Planning and Standards Guober 1979
Agency Research Triangle Park NC 2771 1
vvEPA Review of Standards
of Performance for
Electric Arc Furnaces
in Steel Industry
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EPA-450/3-79-033
Review of Standards of Performance
for Electric Arc Furnaces in Steel Industry
Emission Standards and Engineering Division
EPA Project Officer: Reid E. Iversen
P.O. Environrr ;"•'•
j ,' o a o f i-j -i' -* - •"->
WO S. Dearborn L
Chicago, IL 6060^t
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air, Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, North Carolina 27711
October 1979
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This report has been reviewed by the Emission Standards and Engineering
Division, Office of Air Quality Planning and Standards, Office of Air, Noise,
and Radiation, Environmental Protection Agency, and approved for publica-
tion . Mention of company or product names does not constitute endorsement
by EPA. Copies are available free of charge to Federal employees, current
contractors and grantees, and non-profit organizations - as supplies permit
from the Library Services Office, MD-35, Environmental Protection Agency
Research Triangle Park, NC 27711; or may be obtained, for a fee, from the
National Technical Information Service, 5285 Port Royal Road, Springfield,
V f\
Publication No. EPA-450/3-79-033
11
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TABLE OF CONTENTS
1.0 INTRODUCTION 1-1
2.0 SUMMARY 2-1
2.1 Latest Control Technology for Electric Arc Furnace Shops 2-1
2.2 Rationale for Review of the Mew Source Performance
Standards for Electric Arc Furnaces 2-2
2.3 Inclusions and Exemptions in Revised New Source
Performance Standards 2-3
2.4 References for Section 2.0 2-3
3.0 ELECTRIC ARC FURNACES IN THE STEEL INDUSTRY 3-1
3.1 General 3-1
3.2 Description of Process 3-5
3.3 Emission Sources 3-8
3.4 References for Section 3.0 3-10
4.0 STATUS OF EMISSION CONTROL TECHNOLOGY FOR ELECTRIC ARC FURNACES 4-1
4.1 Capture Systems and Control Devices 4-1
4.1.1 Canopy Hoods in a Shop with a Sealed Roof 4-1
4.1.2 Direct Shell Evacuation in a Shop with Either
Building Evacuation or Canopy Hoods and a Closed Roof 4-3
4.1.3 Semi-enclosed Furnaces with Direct Shell
Evacuation, Canopy Hoods and Tapping Hoods 4-3
4.1.4 Side Draft Hoods 4-7
4.1.5 Furnace Enclosure 4-7
4.1.6 Brusa Closed Charging System 4-15
4.1.7 Canopy Hoods in Combination with Natural Ventilation
through Open Roof 4-15
4.1.8 Direct Shell Evacuation in Combination with Natural
Ventilation through Open Roof 4-17
4.1.9 Building Evacuation in Shop with Closed Roof 4-20
4.1.10 Direct Shell Evacuation in Shop with Canopy Hoods
with Open Roof
4.2 Effectiveness of Various Control Devices 4-23
4.3 Control Technology Applicable to New Source Performance
Standards for Electric Arc Furnaces 4-24
4.4 Control Technology in Current Use in Mew Electric
Arc Furnace Shops 4-24
4.5 Potential New Control Technology 4-26
4.6 References for Section 4.0 4-27
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5.0 CURRENT STANDARD FOR ELECTRIC ARC FURNACES IN STEEL INDUSTRY 5-1
5.1 Electric Arc Furnace Exemptions from New Source
Performance Standards 5-1
5.2 New Source Performance Standards for Particulate Emissions 5-2
5.3 Problems with New Source Performance Standard for
Visible Emissions 5-3
5.4 References for Section 5.0 5-4
6.0 CURRENT STATUS OF ELECTRIC ARC FURNACES IN STEEL INDUSTRY 6-1
6.1 Emission Data Since New Source Performance Standards
Promulgation 6-1
6.2 Comparison of New Control Technology and Current
New Source Performance Standards Emission Control
Performance 6-2
6.3 Future Growth 6-4
6.4 Justification to Revise New Source Performance Standards 6-4
6.5 References for Section 6.0 6-5
7.0 RECOMMENDATIONS FOR REVISION OF STANDARDS 7-1
iv
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LIST OF ILLUSTRATIONS
Figure Mumber a^e
3-1 Flow Diagram of an Iron and Steel Plant 3-2
3-2 Steel Production Trend by Type of Furnace 3-3
3-3 Electric Arc Furnaces 3~6
3-4 Electroslag Remelting Furnace 3-9
3-5 Reduction of Slag Inclusions 3-9
4-1 Canopy Hood with Closed Roof System 4-2
4-2 Direct Shell Evacuation, Building Evacuation
with Closed Roof System 4-4
4-3 Direct Shell Evaucation, Canopy Hood with
Closed Roof System 4-4
4-4 Semi-Furnace Enclosure System 4-6
4-5 Side Draft Furnace System 4-8
4-6 Total Furnace Enclosure with Proprietary 4-9
through Steam Scrubber through
4-10 4"u
4-11 The Brusa Charging and Preheating System 4-16
4-12 Canopy Hood with Open Roof System 4-18
4-13 Direct Shell Evacuation with Open Roof System 4-18
4-14 Building Evacuation System 4-21
4-15 Direct Shell Evacuation, Canopy Hood with Ooen Roof 4-21
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TABLE
Table Number
Table 6.1 Comparison of New Control Technology and Existing
NSPS Control Technology for EAF's in the
Steel Industry 6_3
VI
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1.0 INTRODUCTION
Section 111 of the Clean Air Act, "Standards of Performance for New
Stationary Sources," requires that "The Administrator shall, at least
every four years, review and, if appropriate, revise such standards
following the procedure required by this subsection for promulgation of
such standards."
The purpose of this study is to review the current new source
performance standards (NSPS) for electric arc furnaces (EAF's) in the
steel industry and to assess the need for revision on the basis of
developments that either have occurred or are expected to occur in the
near future. This report addresses the following issues:
1. Utilization of EAF's in the steel industry.
2. Review of the best demonstrated control technology for emission
control.
3. Review of existing and new control technology since promulgation.
4. Review of EAF's that are exempt from the standard.
5. Review of problems related to compliance with NSPS.
6. Analysis of available FAF particulate and visible emission test
results.
Based on the information developed in this study, specific recommendations
are made for changes in the current NSPS.
1-1
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2.0 SUMMARY
Control technology for EAF shops has been improved and refined
since the promulqation of the original NSPS. Fugitive emission control
technology, especially for charging and tapping emissions, has been
developed, and furnace emissions can be captured more effectively.
These improvements afford a more stringent control of visible emissions
than required by the present NSPS. Some compliance test problems have
developed in enforcing the visible emission portion of the NSPS.
2.1 LATEST CONTROL TECHNOLOGY FOR ELECTRIC ARC FURNACE SHOPS
There are several control technologies that EAF shops can use, but
only a few recent ootions are available that can be considered best
demonstrated control technology for both process and fugitive emissions.
The combination of direct shell evacuation, canopy hoods, fugitive dust
pickup system, and a closed roof aopears to be the most overall efficient
system. Another commonly used system includes a canopy hood, fugitive
dust pickup system, and a closed roof. Total enclosure of the furnace,
a new concept since the NSPS was promulgated in 1974, can potentially
capture all process and fugitive emissions (charging and tapping).
Since these emissions do not mingle with other shop emissions, enforcement
issues are reduced (See Section 5.3). Partial or semi-furnace enclosure
is another concent which encloses the furnace by four walls with the top
open, so that a crane can reach the furnace area. The walls, acting as
a "stack", force the emissions to rise from the furnace into the overhead
canopy hoods. The EAF shop itself can also have a closed roof.
2-1
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One European system preheats the scrap feed with the hot furnace
gases while scrap is fed continuously to the furnaces. This system
offers the advantage of confining the charging emissions to the preheater
(ducted to a control device) and thus permits a simple collection system.
The scrap size for this system must be controlled. Only one U.S. plant
(foundry) uses this type of system. The systems previously described
usually have baghouses as the control devices. The one furnace enclosure
system used in the U.S. uses a proprietary scrubber system, but a baghouse
could be used effectively on this system.
2.2 RATIONALE FOR REVIEW OF NEW SOURCE PERFORMANCE STANDARDS FOR ELECTRIC
ARC FURNACES
The rationale of the current NSPS that closed roofs, building
evacuation, and limited control for tapping or fugitive emissions was
too costly and energy intensive, or that technology was not developed
may not be valid today. Regulations currently being developed by some
local agencies appear to be more stringent than the NSPS. Also, more
stringent control (than required by NSPS) may be necessary to prevent
significant deterioration of the air quality or to meet off-set policies
in specific areas. The technology trend is toward the use of sealed
roofs, canopy hoods, and a fugitive dust pickup system, Control technology
developed and demonstrated for fugitive emissions mainly from tapping
and charging is the major improvement in controlling visible emissions.
Although only one official NSPS compliance test has been carried out
since promulgation of NSPS, some unofficial test data indicate that
emissions from certain new furnaces are below the NSPS for particulates
1-4
and visible emissions.
2-2
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2.3 INCLUSIONS AND EXEMPTIONS IN REVISED NSPS
A speciality type furnace known as the argon-oxygen decarbonization
(ADD) furnace should be included in the NSPS because this furnace is a
significant source of particulate and visible emissions. Although AOD
furnaces are not electric furnaces, they are an integral part of an EAF
shop and should, therefore, be considered for inclusion under an EAF
standard. This change may require alternation of the definition of the
affected facility portion of the NSPS.
Several other speciality electric arc furnaces used in the industry
should officially be listed as exempt from the NSPS. Electric arc furnaces
using prereduced pellets should also be reviewed in detail to determine
whether their exempt status should be continued. These findings indicate
revision of the current NSPS should be considered.
2.4 REFERENCES FOR SECTION 2.0
1. Region IV, 1977. Memo dated February 28, 1977 to Drew Trenholm,
ESED from Bruce Miller, Region IV.
2. Blair and Martin, 1978. EAF Fume Control at Lone Star Steel Company,
Lone Star, Texas.
3. Reinke, J.M., 1976. Letter dated November 1, 1976 to Mr. Michael Maillard.
Wayne County Department of Health, Air Pollution Control Division.
Detroit, Michigan.
4. Adams, J.I., 1978. Letter dated September 20, 1978 to
Mr. John E. McGrogan, P.E., Department of Environmental Resources,
Bureau of Air Quality. Wernersville, Pennsylvania.
2-3
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3.0 ELECTRIC ARC FURNACES IN STEEL INDUSTRY
3.1 General
Major sources of air pollution in the steel industry are the basic
oxygen process, electric arc, and open hearth steel production furnaces;
blast furnaces; and coke and sintering plants (Figure 3-1). All will
emit large quantities of air pollutants (primarily particulate matter)
if not properly controlled. The first standards of performance for
electric arc furnaces were Promulgated in October 1974. This review was
conducted to determine whether existing standards for electric arc
furnaces should be revised as required in Section lll(b) of the Clean
Air Act as amended August 1977.
Standards for the basic oxygen process furnace (BOPF) were developed
before those for the electric arc furnace (EAF) because the BOPF was
projected to experience the greatest share of the future growth in steel
production. Electric arc furnaces will also participate in the growth
because of the increased use of scrap to produce steel. These projected
growth rates result from increased demand for steel, replacement of
obsolete steel producinn furnaces, and higher energy costs. Figure 3-2
shows trends for the oast 15 vears in the production of steel from these
three types of furnaces.
A BOPF can produce steel at a greater rate than the other types of
furnaces. Since the BOPF has no exterior source of heat, it must be
operated in conjunction with a blast furnace. Because the BOPF requires
a high percentage of molten pig iron as part of the charge, the amount
of steel scrap that can be recycled by the BOPF shops is limited. In
contrast the EAF is very attractive because it can accept a charge that
is all scrao.
3-1
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IRON OR
CO
ro
X
HOT METAL
HOLDER
SCRAP
CONTINUOUS CASTING
y BILLETS
Sintering Machine
OPEN HEARTH
FURNACE
_ SOAKING
CTg PIT
INGOTS
ELECTRIC-ARC
FURNACE
Figure 3-1. Flow-diagram of an iron and steel plant.
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1963 1965 1967 1969 1971 1973 1975 1977
YEAR
Figure 3-2. Steel production trend by type of furnace.
3-3
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In fact, about 98 percent of the steel produced by EAF's in 1977 was
recycled steel scrap.2 EAF's are also particularly suited to production
of alloy steels where only small batches are needed.
The steel industry categorizes the majority of electric furnaces
into electric arc (EAF), argon-oxygen decarbonization (ADD), vacuum arc
remelting (VAR), vacuum induction melting (VIM), consumable electrode
melting (CEM), and electroslag remelting (ESR) furnaces. Each has a
specific function for producing different types of steel. The existing
NSPS exempts AOD, VAR, VIM, and ESR electric furnaces because the tonnages
produced were found to be significantly less than the production from
conventional electric arc furnaces. Some differences are involved in
the operation of these furnaces, and the emission rates may vary considerably,
For these reasons, the furnaces were made exempt from the NSPS.
In 1977, electric arc furnaces produced 27,882,000 tons of steel.
Of this amount, 70 percent was carbon steel, 23 percent was alloy
steel, and 7 percent was stainless steel. This production accounts for
18 percent of the carbon steel, 42 percent of the alloy steel, and all
of the stainless steel produced in all furnace types.
In 1977, the 303 EAF's in the United States were operated by 85
companies at 114 locations. Furnace capacity ranges from an almost toy-
scale 3 tons to 400 tons, with about 50 percent of the furnaces under 49
tons, 25 percent at 50 to 99 tons, 9 percent at 100 to 149 tons, 10
percent at 150 to 199 tons, 5 percent at 200 to 300 tons, and 1 percent
over 301 tons capacity. Larger furnaces are usually located in integrated
3-4
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steel mills. Many of the smaller furnaces are in small plants that
produce a limited variety of products or small quantities of specialty
steels.
Among the factors now tending to increase EAF steel production are:
increasing blast furnace energy costs, larger supplies of steel scrap,
growing use of specialty steels, additional mini-steel plants that
normally use EAF's exclusively, and adoption of ultra-rapid steel melting
technology from Japan and other foreign countries.
3.2 Description of the Process
Electric arc furnaces are cylindrical refractory-lined vessels with
carbon electrodes that are lowered through the furnace roof (Figure 3-3).
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 smaller or older furnaces are charged through
these side doors. Current is applied to the electrodes as they descend
into the furnace. The scrap is melted by the heat generated by the arc
as it shorts between the electrodes and 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 1.5 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, ^ach cycle normally consists of alternate charging
and melting operations, refining (which usually includes oxygen blowing),
and tapping.
3-5
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CARBON
ELECTRODES
SCRAP,
LIMESTONE,
AND LIME
FURNACE
ROOF
MECHANISM THAT LIFTS
AND PIVOTS ROOF
FURNACE
/ALLOY AND SLAG
ADDITIONS
CHARGING
SLAG
BOLTEH
STEEL
DESLAGGING AND TAPPING
Figure 3-3. Electric-arc steel furnace.
3-6
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ADD furnaces are refractory-lined vessels generally U-shaped like
basic oxygen furnaces. They are used to refine hot metal from EAF
furnaces. Molten steel from the EAF is transferred by ladle to the AOD
furnace. Although procedures vary somewhat, major alloy additives are
made in the AOD. A mixture of argon-oxygen is blown into the molten
steel through tuyre pipes in the bottom or side of the furnace to oxidize
the carbon. Nitrogen can also be added through these pipes if a nitrogen-
bearing grade of steel is desired. After carbon oxidation is complete,
additional fluxes are added to remove sulfur and other undesirable
impurities from the molten metal. Upon completion of the refining
process, excess slag is removed and the remaining molten steel is cast
into ingots or electrodes for further processing. The complete AOD
process usually takes about 90 minutes.
During the carbon oxidizing process, emissions from an AOD furnace
are given off as copious dense black fumes. When decarbonization is
complete, the emissions are much less, but are still quite significant.
The opacities of emissions from AOD's are similar to those from EAF's,
but mass emission data are not available.
VIM and VAR furnaces are sealed refining furnaces that remelt materials
made by the other furnaces for very special types of steel products.
Current applied across the furnaces generates heat to the material to be
remelted, and a vacuum to about 5 micrometers is drawn at the same time
to degas the molten steel. The steel is reformed into a new ingot or
electrode, which may be further processed. As shown in Figure 3-4, the
electrode is a long (10-15 feet) cylindrical (6-12 inches in diameter)
piece of steel. The electrode is used in all the remelting furnaces,
3-7
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except the VIM furnace, which requires smaller than fist-size pieces for
easier remelting. Imperfections in castings made from this steel are
eliminated by degasing. Because these furnaces operate under a vacuum,
no emissions are generated.
ESR melting is a hyper-refining process in which ingots (electrodes)
made from the EAF, VIM, and VAR furnaces are remelted under a specially
compounded molten slag. Figure 3-4 is a schematic of the ESR furnace
system. Steels produced in an ESR furnace have more uniform grain
structures, fewer defects, and better mechanical properties than conventionally
produced steels. Figure 3-5 shows one of the features of steel made
from an ESR furnace. Current applied across the furnace generates heat
to remelt the electrode. New and usually larger ingots are made.
There are no emissions generated during this process.
3.3 Emission Sources
Most emissions occur during the early "melting" portion of a furnace
cycle, although significant quantities are also emitted during charging,
tapping, and oxygen-blowing operations. Emissions of up to 30 pounds of
particulate matter per ton of steel produced 4'5 are generally acknowledged.
Information supplied by steel manufacturers on the quantity of particulate
matter collected by control devices suggests, however, that 30 pounds
per ton may actually be conservative for production of carbon steel
and that 15 pounds per ton is a reasonable value for alloy steels.
Particulate matter emissions may also vary from cycle to cycle and
from batch to batch. Contamination of the scrap steel with dust, oil, or
volatile metals, for example, increases emissions during charging.
An increase in electrical power to a furnace increases emissions during
the scrap melting. Variations in the quantity of oxygen blown varies
emissions during the blow.
3-8
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r^
-ELECTRODE CLAMP
-ELECTRODE
COOLING WATER OUTLET
WATER COOLED MOULD
SLAG BATH
SOLIFIED SLAG LAYER
MELTING SUMP
SOLIDIFIED INGOT
COOLING WATER INLET
WATER COOLED BASE PLATE
Figure 3-4. Electroslag remelting process in which a solidified ingot is
remelted and reformed into a superior product.
Figure 3-5. Slag in H13 bar before (left) and after (right) refining.
3-9
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3.4 References for Section 3.0
1. Annual Statistical Report - American Iron and Steel Institute -
1977. published by the American Iron and Steel Institute, p. 53.
2. Ibid, p. 72.
3. World Steel Industry Data Handbook, Volume 1:33, Metal Processinq -
1978.
4. Iron and Steel Industry, prepared by Environmental Engineering,
Incorporated for EPA, Contract Mo. CPA 70-142, March 15, 1971,
p. 8-6.
5. Letter from George N. Stoumpas, American Iron and Steel Institute,
to Randy D. Seiffert, EPA, January 23, 1973.
6. Background Information for Standards of Performance: Electric Arc
Furnaces in the Steel Industry, Volume 1, page 10,
EPA 450/2-74-017a, October 1974.
3-10
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4.0 STATUS OF EMISSION CONTROL TECHNOLOGY FOR ELECTRIC ARC FURNACES
Emission control technology studied during the development of the
MSPS has not changed significantly since NSPS promulgation. However,
insistence by some local control agencies today that no visible emissions
escape the EAF shop has encouraged the use of efficient systems and
caused some new concepts to be developed. The more efficient systems
and new concepts are discussed in Section 4.1.1 through 4.1.6. Other
EAF control systems are discussed in Sections 4.1.7 through 4.1.10. The
major difference among all the systems is the method used to capture the
emissions from the furnaces.
4.1 CAPTURE SYSTEMS AND CONTROL DEVICES
4.1.1 Canopy Hoods in a Shop With a Sealed Roof
The canopy hood (CH) system (Figure 4-1) consists of a canopy hood
suspended directly above each furnace connected to fans and ducts that
evacuate the air. Since these hoods must not restrict movement of the
crane that transports charges by raw materials to the furnaces, 30 to 40
feet of clear area is provided immediately above the furnaces. Furnaces
charged through doors in the side or fed through a chute do not require
much freeboard and hoods can be built nearer the furnace.
During charging, the fumes rising rapidly 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 emissions to bypass the hood. Because the building is sealed,
fugitive emissions not captured in the hood accumulate in the upper part
of the building and are gradually drawn into designed openings provided
in the CH ductwork.
4-1
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Canopy hoods are sometimes divided into sections and are dampered
to maximize draft directly above the point of greatest emissions during
charging, tapping, or slagging operations.
After capture, the effluent is cleaned in the fabric filter. The
hot furnace gas must be cooled by water sprays, radiant coolers, dilution
air, or some combination of these devices to prevent rapid degradation
of the fabric. Electrostatic precipitators and Venturi scrubbers are
sometimes used. If a precipitator is used, the gas is humidified to
maximize the efficiency of the precipitator. Only the Venturi scrubber
does not require any special treatment of the exhaust gas.
FUGITIVE PICK-UP
OPENINGS
^P> EXHAUST GAS
CLEAN AIR
Figure 4-1. Canopy hood (CH) closed roof.
4-2
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4.1.2 Direct Shell Evacuation in a Shop with Either Building Evacuation
or Canopy Hoods and a Sealed Roof
The direct shell evacuation system (DSE) unquestionably provides
the best control during meltdown and refining, and either building
evacuation (Figure 4-2) or canopy hoods (Figure 4-3) 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 emission of particulate from different
furnaces dictate. Separate control devices can be used, or a single one
can serve both systems.
This combination of equipment 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 be
adequate to assure proper ventilation for an acceptable working environment.
Peak air flow rates are used for the building evacuation or canopy hood
system during charging and tapping when the DSE system is ineffectual.
At other times these peak flows can be reduced.
The direct shell evacuation system cannot be used for all steels,
as explained in Section 4.1.8.
4.1.3 Semi-enclosed Furnaces with Direct Shell Evacuation, Canopy Hoods
and Tapping Hoods
A new concept for containing air pollution from electric arc furnaces
was developed in 1976 for a shop producing carbon steels in two furnaces
with 225 tons of capacity each. The furnaces are equipped with conventional
4-3
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CLEAN AIR
EXHAUST GAS
Figure 4-2. Direct shell evacuation - building evacuation (BE) system with closed roof.
FUGITIVE PICK-UP
OPENINGS
CLEAN AIR
EXHAUST GAS
Figure 4-3. Direct shell evacuation - canopy hood (CH) with closed roof.
-------
DSE and CH systems. The major innovations are: (1) enclosures around
each furnace that act as chimneys to direct charging fumes up into the
canopy hoods (CH) and (2) hoods that capture emissions from the tapping
ladle and slag pot. The shop roof is closed above the two furnaces.
Figure 4-4 shows these new concepts.
The enclosure walls are designed to allow the crane to travel
between the hood and the furnace to position the charging bucket over
the furnace. The charging enclosure is ample sized to allow the furnace
roof to swing over the tapping area, where it can capture emissions from
the pouring spout or any fumes that bypass the tapping hood.
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, as shown in Figure 4-4. The empty ladle is moved by crane to a
railcar, which is rolled under the hood. Molten steel is then 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.
This system also has a stationary hood over the slag pot through
which the slag drops to capture the slag emissions, even though they are
a minor source of emission from EAF's.
The total air flow design for this system is 630,000 dry standard
cubic feet per minute (dscfm) or 1600 dscfm per ton of furnace capacity.
This volume is about the same as that used for conventional DSE-CH
systems in shops with open roofs. This system combines the lower cost
4-5
-------
OPERATING FLOOR
SLAG POT
Figure 4-4. New system for capture of emissions from electric arc furnaces.
A_r,
-------
and energy requirements of a DSE-CH system with the higher capture
efficiency of systems with high air flow rates. According to the local
agency, this new system achieves better control than previous CH systems,
and no visible emissions are noted except during upsets.
4.1.4 Side Draft Hoods
The side draft hood is another fume evacuation system available to
EAF's. It is mounted on or near the furnace roof, as illustrated in
Figure 4-5. The hood is designed with one side open so that the travel
of the electrodes is not restricted. As fumes escape from electrode
holes, they are drawn into the open side of the hood. Vanes for directing
air flow are provided on the ends of the finger ducts. Hoods may also
be installed over the pouring spout and slag door to capture fumes
during melting. Large exhaust volumes must be maintained for the side
draft to draw fumes laterally into the hood. The larger exhaust flow
insures combustion of carbon monoxide and reduces downstream exhaust
temperatures. The side draft hood is simpler than a roof hood, places
less weight on the furnace and furnace tilting mechanism, and improves
access for maintenance of electrodes and cooling glands. To insure
effective capture of melting emissions, the furnace roof must be sealed
tightly to avoid the escape of fume. This is not a requirement of roof
hoods, which enclose the entire furnace top.
4-7
-------
1DD.
Figure 4-5. Side draft hood.
4.1.5 Furnace Enclosure
Another new concept for containing air pollution from EAF's was
applied at a shop containing two 60-ton electric arc furnaces. This
concept is a total furnace enclosure, which captures both primary and
fugitive emissions. Openings were to be provided in the enclosure for
the charging, tapping, and slagging operations. The system is a metal
shell shaped somewhat like a barn (Figure 4-6); it completely encloses
the furnace and tapping area and can effectively capture emissions from
melting, charging, and tapping. A large exhaust duct or hood near the
enclosure top removes charging and melting emissions (Figure 4-7) while
a separate, local hood contains tapping fumes (Figure 4-8). Tapping
fumes are collected by diverting exhaust flow from the enclosure to a
local hood adjacent to the ladle. Sliding doors on the front, back, and
top of the furnace allow entry of the charge bucket by conventional
crane and also provide for slagging, chemical addition, and oxygen
lancing (Figures 4-6 and 4-7).
4-8
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CHARGING
DOORS CLOSES
SEGMENTED
TOP DOOR CLOSED
(AIR CURTAIN ON)
DIRTY GAS
T0 UNITS
PERSONNEL
DOOR CLOSED
(EXCEPT TO .LANCE)
• COOLING AND
COMBUSTION AIR
IN FROM BASEMENT
(SLAGGING FUMES
ALSO CAPTURED)
SECTION TO EAST
Figure 4-6. Furnace during melt and refine.
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CRANE SLOT
AIR CURTAIN
DISCHARGE
OVERHEAD
CRANE CABLES
INTAKEn
DUCT
AIR CURTAIN
BLOWER
CHARGE
BUCKET
VIEW TO SOUTH
(DOORS SHOWN' OPEN FOR CLARITY)
'(FRONT OF FURNACE)
•ROOF SWUNG
OFF FURNACE
SECTION TO NORTH
(BACK OF FURNACE)
AIR
CURTAIN
INLET
FLOW
Figure 4-7. Furnace being charged.
-------
CHARGING
DOORS
CLOSED
•SEGMENTED
TOP DOOR' CLOSED
(AIR CURTAIN ON)
FURNACE
ROTATED
FOR TAP.
wan
DIRTY GAS
TO UNITS
ERSONNEL
DOOR CLOSED
DOORS
CLOSED
N
SECTION TO EAST
TRANSFER CAR-i ' ""LADLE
VIEW TO SOUTH
-------
MELT SHOP BUiLDING n DIRTY GAS FROM
~ L- ] FURNACE NO. 7
i
Fo
DIRTY GAS FROM
FURNACE NO. 6
VENTUR!
LEAN-TO ROOF
COMMON DUCT
DOWN-COMER
MANIFOLD DUCT
STEAM HYDRO ' UNIT
Figure 4-9. Gas cleaning system layout.
-------
STEAM LINE
NOZZLE
MOUNT DUCT
-WATER INJECTOR LINE
STEAM NOZZLE
k
-WATER . A
INJECTOR
MIXING-
TUBE
DRAIN WATER
CYCLONES
Figure 4-10. Typical steam hydro unit.
-------
During melting, doors are closed and fumes are exhausted from the
enclosure by a large rectangular exhaust duct located below the enclosure
top, above the furnace. Between 75,000 and 90,000 afcm is withdrawn
from each enclosure by suction developed by the company's proprietary
Steam-Hydro scrubber, which cleans furnace exhaust (Figures 4-9 and 4-
10). Slagging, chemical additions and oxygen lancing are conducted
through a third set of doors at the rear of the furnace. The furnace is
tapped in a ladle, which is placed on a rail car by the overhead crane
and then rolled into position under the enclosure. Tapping fumes are
collected by diverting the air flow from the main exhaust duct at the top
of the enclose to a hood adjacent to the ladle. Poth furnaces and
enclosures rest on a platform about 6.3 m (20 ft) above the melt shop
floor. This arrangement provides room for the tapping ladle car and
also provides air flow from underneath the furnaces to carry fumes to
the main exhaust duct.
Durino charqina, the seamented too door (Figure 4-6) is opened to
allow the crane to enter with the charge bucket (Figure 4-7) and the
feed material is discharged to the FAF. The unique feature about the
charging system is that a curtain of air is blown across the open too of
the enclosure (Figure 4-7) to push the charging emissions into the
intake duct leading to the scrubber. This was designed to prevent most
of the charging emissions from escaping the enclosure and building. The
company reports it has not, encountered any major oroblems in using the
enclosure. According to the company, about 90 percent or better of the
charging emissions are contained by the enclosure; however, recent FPA
observations of this facility report capture efficiency of 50 to 90
percent, depending upon the operation. There appear to be some engineering
4-14
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deficiencies in the design of the enclosure which could be corrected on
newer systems and improve the collection efficiency. Another criticism
of the furnace enclosure is that only clean scrap can be melted because
flames from contaminating oil and organic matter from the hot furnace
reach the top of the enclosure. The company indicated that trial runs
using dirty scrap showed additional enclosure height would be necessary
if dirty scrap were to be used routinely. The fact that furnace enclosures
are being used in large BOPF shops suggests that this system offers a
comprehensive solution to the many problems of controlling process and
fugitive emissions from EAF's.
4.4.6 Brusa Closed Charging System
The Brusa closed charging system, illustrated in Figure 4-11, has
been operating on a steel-making furnace in Italy for several years.
Exhaust gases from the hot furnace are vented through a rotary kiln or
drum. Charge material is fed continuously down through the kiln and
into the furnace, where it is preheated by furnace gases to about 1000 C.
Volatile matter entrained in the charge is thus oxidized and withdrawn
at the top of the kiln along with furnace exhaust gases.
This system has the advantages of heat recovery and containment of
charging emissions in a fashion allowing for simple collection and
ducting to a control device. This type of steel making is a continuous
process in that charge material is continuously added and the furnace is
tapped frequently. There is a trend toward this type of operation in
steel-making furnaces, only one domestic foundry EAF is known to use
continuous charging. The Brusa and other conceptual designs for closed
charging systems require small-sized scrap that will pass through the
enclosed conveyor system.
. ~ .." <„• • ->v 4-15
-------
-pi
^
figure 4-11. Brusa charging and preheating system.
-------
4.1.7 Canopy Hoods In Combination With Natural Ventilation Through
Open Roof
The canopy hoods (CH) are identical to those described previously;
but, as shown in Figure 4-12, in some shops the roof monitors allow
natural ventilation to augment ventilation resulting from the hood
suction. Unfortunately, they also allow any fume that bypasses the hoods to
escape the building as visible emissions. Air 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.
4.1.8 Direct Shell Evacuation System in Combination With Natural Ventilation
Through Open Roof)
The direct shell evacuation system, -shown in Figure 4-13, withdraws
all potential emissions directly from within the furnace before they can
escape and be diluted by the ventilation air. A water-cooled air exhaust
duct, which extends through the furnace roof, is jointed near the furnace
with a gap of one to several inches separating the ends of the two duct
sections. 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 times, 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
4-17
-------
i.(SA ^
MONITOR f, 7 />
• CLEAN AIR
iiS^p> EXHAUST GAS
FURNACE
O
FABRIC FILTER
Figure 4-12. Canopy hood (CH) with open roof.
BUILDING
MONITOR
CLEAN AIR
> EXHAUST GAS
&£ CHARGING
V4 AND K
WAPPiNGtfe
EMISSIONS W
FURNACE
Figure 4-13. Direct shell evacuation (DSE) system with open roof.
4-18
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the electrodes and through the gap into the exhaust duct. This air not
only cools the exhaust qas, but it permits combustion of the large
amounts of carbon monoxide present.
A well designed and operated DSE system is desirable not only
because it can capture essentially all the dust generated during meltdown
and refining (including emissions during the oxygen blow), but also
because it inherently restricts the gas to be cleaned. The DSE system
provides maximum removal efficiency with minimal energy requirements.
Unfortunately, as mentioned earlier, when the furnace is being charged
or tapped, emissions billow to. the roof. If the roof is open, the
emissions exhaust directly to the atmosphere in a very visible plume.
DSE cannot be used in the manufacture of all steels. During the
production of some alloys, a second slagging operation is necessary. A
"reducing" slag is used to remove certain 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 that accommodates 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 constitute a surface which absorbs more radiant heat from the melt
than it returns, and results in a cold spot in the molten steel. Recently,
air curtains have been used to prevent oxidizing air from entering a
furnace. Air curtains also therefore promote better temperature control
within the furnace. Some furnaces may not be able to use air curtains
because of their specific operation and design.
4-19
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4.1.9 Building Evacuation in Shop with Closed Roof
With the building evacuation system (BE), the entire building is
used to capture dust from the furnaces. As shown in Figure 4-14, hot
exhaust gases containing dust billow to the roof of the shop, where they
are drawn into ducts leading to a fabric filter. Because the removal
capacity of the duct may be less than the furnace release rate, dust-
laden gas sometimes accumulates beneath the closed roof during periods
of high dust generation. Since air cannot escape except through the
control device, the dust does not create an outside 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 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.
4.1.10 Direct Shell Evacuation in Shop with Canopy Hoods with Ooen Roof
This combination is identical to the system described in Section
4.1.2, 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.
4-20
-------
CLEAN AIR
EXHAUST GAS
Figure 4-14. Building evacuation (BE) system with closed roof.
BUILDING
MONITOR
CLEAN AIR
SHMXHAUST0AS
Figure 4-15. Direct shell evacuation (DSE)-canopy hood system with open roof.
4-21
-------
Fumes not captured by the hoods escape as a visible emission
through the open roof monitors. Shops with many furnaces that have
staggered charging and tapping cycles will probably have visible emissions
through some portion of the roof monitors much of the time.
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 of fumes that bypass the canopy. Fugitive dust
openings in the exhaust ductwork of the canopy hood could extract the
fugitive emissions that are trapped near 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 and less energy
than systems with a closed roof on the shop.
4-22
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4.2 Effectiveness of Various Control Techniques
Because direct assessment of these capture systems is difficult,
few attempts are made to measure their efficiencies. Efficiency "measurements'
are usually visual estimates, which can vary considerably among observers.
Estimates of emission rates for the various control systems are, then,
extremely dependent on the values and estimates assumed.
For NSPS development, theoretical emission rate calculations were
based on a canopy hood capture efficiency of 80 percent from an estimated
range of 70 to 90 percent, depending upon several variables. 2 These
variables include the age of plant, design of hood, distance of hood to
EAF, shop configuration, air currents in building, building design, and
rate of air flow to control system.
Because of the many variables involved, the newer technology
requires closed roofs and scavenger ducts to capture those emissions
escaping the hoods. At some shops full or partial enclosure of the
electric arc furnace is reported to capture 90 percent of all furnace
3
emissions. Again, this is a visual observation rather than a measurement,
but the furnace enclosure configuration appears to improve the reliability
of the visual observation compared to canopy hoods, which may be 40 feet
or more above the source of emissions. The semi-enclosed furnace system
also appears to provide better canopy hood capture efficiency because of
the ability to direct the emissions more effectively into the canopy
hoods. Visual observations of this system estimate a hood capture
4-23
-------
efficiency of 90 percent; but because the roof is sealed, all of the
emissions should be captured and directed to a control device.
In conclusion, current control technology such as total furnace
enclosure, partial furnace enclosure with canopy hoods, canopy hoods
with fugitive dust pickup system, and sealed roof provides for improved
capture and control of all furnace emissions compared to the systems in
use at the time of promulgation of the NSPS. Also, controls for tapping
and other fugitive emissions can be installed to further improve the
control of significant sources of EAF emissions.
4.3 CONTROL TECHNOLOGY APPLICABLE TO NSPS FOR EAF FURNACES
Emission control technology to meet current NSPS is directed to
controlling only primary emissions. All the systems for the NSPS study
used a baghouse for the control device. The present NSPS provides only
limited control of fugitive emissions, meaning some of the emissions
from tapping and charging are not captured by the canopy hoods. The
visible emission portion of the NSPS is intended primarily to regulate
or to allow for some of these emissions. The NSPS is generally based on
direct shell evacuation with canopy hoods and an open monitor or canopy
hoods with adjustable louvers in the monitor that can be closed to
contain heavy emissions and opened when there are no significant emissions.
In the NSPS development, this system was considered the most effective,
considering costs.
4.4 CONTROL TECHNOLOGY IN CURRENT USE ON NEW EAF SHOPS
The control technology reviewed for this study revealed that well-
controlled EAF shops can use (1) direct shell evacuation and canopy
hoods with a closed roof, (2) canopy hoods with a fugitive dust pickup
-------
system and a closed roof, (3) total furnace enclosure with an open roof
(however, the roof could be closed in future designs), and (4) semi-
enclosed furnace and canopy hoods with a fugitive dust pickup system and
a closed roof. The reasons for the change from an open roof to a closed
roof are: (1) the insistence of some local air pollution control agencies
on a more stringent visible emission limitation on the EAF shop than
required by the NSPS, (2) to meet EPA's off-set policies, or (3) to
prevent significant deterioration of the air quality in an area. These
control systems also control essentially all emissions from the EAF
shop, including those from charging, tapping, slagging, and teeming
operations and AOD furnaces and ladle fumes.
The concern for the high cost attributed to handling large volumes
of gases from the evacuation of gases from a closed roof building apparently
has been overcome by using canopy hoods and adding a fugitive duct
system in the closed roof monitor to collect fugitive emissions. This
type of system allows for collecting and restraining the fugitive dust
emissions within the building and slowly drawing these emissions into
the control device as the process goes through its cycles. Also, the
gas volume is reduced in comparison to that involved in building evacuation,
because direct shell evacuation or canopy hoods still collect the greatest
portion of the emissions, while the fugitive dust system is designed
only to pick up the small balance of the emissions.
There are not enough data available from the testing of these
systems to indicate whether one or all of them could be considered "best
demonstrated control technology." The only criteria for comparison of
these systems during this review was visible emissions. Plant visits
and reports from air pollution control agencies indicate that these
systems are below the present NSPS for visible emissions.
-------
4.5 POTENTIAL NEW CONTROL TECHNOLOGY
Control technology for future EAF shops can be designed as previously
discussed in Section 4.4 or additional control measures can be added to
provide better control of the significant sources of fugitive emissions
during charging and tapping. Tapping emissions, for instance, can be
controlled by using a tight-fitting swing-away hood over the ladle; or a
totally enclosed room can be used, with the ladle on a railcar. The
industry practice has been to have the crane hold the ladle during
tapping; therefore, hoods and enclosures have not been used during the
tapping cycle. This concept is slowly disappearing, however.
Another potential technology, used at an EAF shop in Europe and at
one foundry in the United States, is to use the gases from the EAF
furnace in a kiln to preheat scrap being continuously fed to the furnace.
This system permits heat energy recovery and reduces the volumes of
gases to be collected and treated. The size of the scrap being fed must
be controlled. This system will also need to be reviewed for other
negative aspects.
Most of the discussion in this study is devoted to the capture of
the emissions. Baghouses are still the most widely used control device;
only one proprietary scrubber has been installed since 1974. The design
of the baghouse may only vary between having stacks or open tops to
discharge the gases. The open-top, pressure-type baghouse is not easy
to source test and enforcement based on compliance tests is difficult.
Methods for source testing this type of baghouse will have to be developed
for enforcement compliance requirements.
4-26
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4.6 REFERENCES FOR SECTION *.Q
1. Iron and Steel Engineer, July 1978. Air Curtains on Electric
Furnaces at Luken Steel Company.
2. Background Information for Standards of Performance: Electric
Arc Furnaces in the Steel Industry. U.S. Environmental
Protection Agency, Research Triangle Park, N.C. Publication No.
EPA-450/2-74-017a. October 1974.
3. Blair and Martin, 1978. EAF Fume Control at Lone Star Steel Company,
Lone Star, Texas.
4-27
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5.0 CURRENT STANDARD FOR EAF'S IN STEEL INDUSTRY
The MSPS regulates FAF's and their associated dust-handling equipment
that were planned, under construction, or being modified after
October 31, 1974. An existing EAF is subject to the promulgated NSPS
if: (1) a physical or operational change in the existing facility causes
an increase in the emission rate to the atmosphere of any pollutant to
which the standards applies, or (2) if in the course of reconstruction
of the facility the fixed capital cost of the new components exceeds 50
percent of the fixed capital cost that would be required to construct a
comparable new facility that meets the NSPS.
5.1 EXEMPTIONS FROM NSPS
Electric arc furnaces that process prereduced ore pellets are
exempt from the NSPS because the process was in the development stage at
the time of the NSPS investigation. Also, emissions from this type of
furnace are reportedly generated at different rates and cycle times than
those from conventionally charged EAF's; therefore, the cycle for these
furnaces would be different.
Electric arc furnaces used in foundries are not covered in this
MSPS, but will be covered under another NSPS regulation, specifically
for the foundry industry. Specialty furnaces, such as, AOD, VAR, VIM,
CEM, and ESR furnaces, are exempt from this standard because they were
not entirely investigated during the development of the NSPS for conven-
tional EAF's. These furnaces produce specialty steels, and the number
of such furnaces is relatively small compared to conventional EAF's.
Emission rates and process information for these types of furnaces were
not completely documented during MSPS development.
5-1
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5.2 NSPS FOR PARTICULATE EMISSIONS
Particulate matter is the EAF pollutant to be controlled by the
NSPS, as defined by 40 CFR 60, Subpart AA, dated October 21, 1974:
"On and after the date on which the performance test required to be
conducted ... is completed, no owner or operator subject to the provi-
sions of this subpart shall caused to be discharged into the atmosphere
from an electric arc furnace any gases which:
(1) Exit from a control device and contain particulate matter in
excess of 12 mg/dscm (0.0052 gr/dscf)."
This standard was derived from test results from six well-controlled
plants of various capacities and control systems. Vendor guarantees of
the control devices were also used in developing the NSPS. Opacity
standards were developed to limit visible emissions from the EAF shops
during the various process steps. Recent emission test data are discussed
in Section 6.0.
Performance tests to verify compliance with particulate standards
for EAF's must be conducted within 60 days after the plant has reached
its full capacity production rate, but not later than 180 days after the
initial startup of the facility (40 CFR 60.8). The EPA reference methods
to be used in connection with EAF testing include:
1. Method 5 for concentration of particulate matter and associated
moisture content.
2. Method 1 for sample and velocity traverses.
3. Method ? for volumetric flow rate.
4. Method 3 for gas analysis.
5-2
-------
Each performance test consists of three separate 4-hour runs, with
a minimum sample volume of at least 4.5 dscm (160 dscf). The arithmetic
mean of the three runs is the test result to which performance of record
used to determine compliance with the standard (40 CFR 60.8). Performance
test requirements, including provision for exceptions and provision for
approval of alternative methods, are detailed in 40 CFR 60.8.
Continuous monitoring for the measurement of opacity of emissions
from the control device(s) is required.
5.3 PROBLEMS WITH NSPS FOR VISIBLE EMISSIONS
No air pollution control agency has reported any problem with the
present NSPS, except that EPA Region IV, (Atlanta, Ga.) expressed concern
about the EAF shop opacity requirement or definition. Opacity source
tests conducted at one electric arc furnace shop showed that emissions
trapped in by a sealed-roof during the charging and tapping cycles
escaped when doors were open at each end of the shop, but produced no
violation of the NSPS. Also, it was noted that overlapping charging and
tapping periods from heat to heat caused some confusion about the NSPS
shop opacity requirement. This concern may be valid because the NSPS
opacity limits are:
1. Any gases which exit from a central device and exhibit
three percent opacity or greater.
2. Any gases which exit from the shop and, due solely to
operations of any EAF(s), exhibit greater than zero percent shop
opacity exceot (a) shop opacity greater than zero percent, but less
20 percent, may occur during charging periods and (b) shop
5-3
-------
opacity greater than zero percent, but less than 40 percent, may
occur during tapping periods.
Some review is needed to determine whether the opacity part of the
NSPS needs to be revised to cover problems such as those cited. The
review should determine whether:
1. The definitions of charging and tapping periods need to be
revised.
2. A NSPS for no visible emissions from an EAF may be viable
because technology to control tapping and charging
emissions is now available.
3. An EAF shop might be engineered to prevent emissions from
drifting out the openings below the closed roof area.
4. This specific situation is a problem for enforcing NSPS for
visible emissions
Problems such as these are likely to emerge as agencies start more
compliance tests.
5.4 REFERENCE FOR SECTION 5.0
1. Memorandum from Bruce Miller, EPA Region IV, to Drew Trenholm, EPA,
OAQPS, ESED. February 28, 1979. Electric Arc Furnace Shop NSPS.
5-4
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6.0 CURRENT STATUS OF ELECTRIC ARC FURNACES IN STEEL INDUSTRY
6.1 EMISSION DATA SINCE NSPS PROMULGATION
There are five EAF's that are presently subject to NSPS regulations;
however, one furnace has not started operation, three are still in the
startup mode, and one was tested for visible emissions. This last
furnace met the NSPS, but the EAF shop did create the visible emission
problem that concerned Region IV discussed in Section 5.3.
Four other recently constructed EAF's were required by local agencies
to at least meet NSPS even though the EAF's were not subject to NSPS
because their construction started before NSPS promulgation. One shop
with two partly enclosed furnaces using canopy hoods and a closed roof
was source tested for oarticulate and visible emissions. The local
agency has certified the system as meeting NSPS. However, the control
system uses a pressure-type baghouse, and the testing was conducted by
company personnel with local agency observers. The testing was conducted
by placing a Hi-Vol sampler in the various compartments of the baghouse.
The results show the compartment loading ranged from 0.0097 mg/dscm
(0.0000042 gr/scf) to 0.08 mg/dscm (0.000035 gr/scf) during 12 tests of
4 to 5 hours duration. This test method has not been approved by EPA.
Another EAF shop with a closed roof submitted source test data on a AOD
furnace using a canooy hood. The control device, a baghouse with stacks,
was source tested using EPA Method 5. The results showed an average of
3 3
6.9 mg/m (0.003 gr/ft ) for the three tests. One shop with a totally
enclosed furnace, using a scrubber as the control device, reported a
range of 4.4 to 4.8 mg/dscm (0.0019 to 0.0021 gr/dscf) for three tests
using EPA Method 5. The tests, conducted by the company, were observed
6-1
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by State and FPA personnel.1 Two official test reports were submitted
to EPA.1'2
Although no other source tests have been conducted on any of the
EAF's that are required to meet "!SPS, Regions III and V have contracts
with 6CA Corporation and Acurex to study and source test about 20 steel
facilities, some of which have EAF's. These contracts should be completed
in late 1979.3
6.2 COMPARISON OF NEH CONTROL TECHNOLOGY AND CURRENT NSPS EMISSION
CONTROL PERFORMANCES
Table 6.1 shows emission reductions expected by the control technology
being used today compared to control technology for the current NSPS.
The table shows that the total reduction of particulates from EAF shops
would be about 50,340 tons per year if the NSPS were revised to include
improved emission control technology. Visible emissions would also be
significantly reduced.
Data from industry and EPA source tests indicate that uncontrolled
particulate emissions from the EAF furnaces average about 25.3 pounds
per ton of combined carbon and alloy steel production. Additionally,
alloy fugitive emissions from the charging and tapping operation average
about 1.5 pound per ton of steel. About 42,000 tons of particulate is
generated annually from the charging and tapping operation, plus 353,000
tons per year of uncontrolled particulates generated from the EAF furnaces
based. These emission data are based on 27,882,000 tons of steel production
by EAF's in 1977.
The control systems considered for the development of the current
NSPS were the canopy hood and open roof or direct shell evacuation,
canopy hood, and open roof. These systems would reduce uncontrolled
6-2
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Table 6.1 COMPARISON OF NEW CONTROL TECHNOLOGY AND EXISTING NSPS CONTROL TECHNOLOGY
FOR ELECTRIC ARC FURNACES IN STEEL INDUSTRY
Emission
category
From
furnace
Charging and
tapping
Control
system
Canopy hood
Direct shell
evacuation/
canopy hood
Furnace
enclosures or
semi-enclosures
Canopy hood
Direct shell
evacuation/
canopy hood
Furnace
enclosures or
semi-enclosures
Removal efficiency, %
Current
NSPS and
open roof
87
87
Not
developed
80
80
Not
developed
New technology
and
closed roof
99
99
99
99
99
99
National particulates, tons/yr
Total
emitted
(uncontrolled)
353,000
42,000
Total
captured
Old New
307,110
33,600
349,470
41 ,580
Reduction
42,360
7,980
cr>
i
oo
-------
participate emissions from FAF furnaces by an average of about 87 percent,
collectively. For emissions from the charging and tapping operation, it
was assumed that the canopy hoods would be 80 percent efficient.
Presently available control systems are essentially the same as
those available for the original NSPS except that closed roofs with
fugitive pickup systems are being used. New control technology includes
total or semi-enclosed furnaces and in most cases, closed roofs. Even
though presently available systems should theoretically capture 100
percent of all emissions and should not allow any visible emissions, 99
percent particulate capture from an EAF shop was assumed because of
possible upsets, malfunctions, and other operating problems.
6.3 FUTURE GROWTH
Because of the slow growth in the steel industry at this time and
because most new furnaces being planned for the next 4 years are replacements
for existing furnaces, the impact of emissions due to growth should be
negligible during this period. In fact, emissions could be reduced
through the superior control technology being aoplied to the new furnaces.
The exact number of new furnaces that will actually be constructed in
the next 4 years cannot be determined because industry representatives
are reluctant to state future plans.
6.4 JUSTIFICATION TO REVISE NSPS
There is probably sufficient justification to revise the present
NSPS, based on the following considerations:
1. In general, control technology better than that needed to
comply with the NSPS is being used by industry today for new and existing
EAF shops.
-------
2. Although data on NSPS compliance for new EAF shops are lacking,
enough data may be available from existing well-controlled FAF shops to
extrapolate to future EAF shops. This is especially true in the visible
emission portion of the f'SPS.
3. Fugitive emission control technology (especially, for charging
and tapping emissions) has been developed.
4. AOD furnaces are significant sources of particulate and visible
emissions, and should be considered for inclusion in the NSPS even
though they are not really EAF's. However, they are an integral part of
an EAF shop operation, and frequently use the same or similar control
system as those used by EAF furnaces. This inclusion would probably
require an additional definition of an affected facility in the NSPS.
6.5 REFERENCES FOR SECTION 6.0
1. Reinke, J.M., 1976. Letter dated November 1, 1976, to Mr. Michael
Maillard. Wayne County Department of Health, Air Pollution Control
Division. Detroit, Michigan.
2. Adams, J.I., 1978. Letter dated September 20, 1978 to Mr. John E.
McGroqan, P.E. Department of Environmental Resources, Bureau of Air
Quality. Wernersville, Pennsylvania.
3. Region III and V Enforcement Divisions, 1979. Personal Communications.
4. Particulate Emission Factors Applicable to the Iron and Steel Industry,
Midwest Research Institute Draft Report - Table No. 8, April 5
1979, EPA Contract No. 68-02-2609.
6-5
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1. REPORT NO.
EPA-450/3-70-033
4. TITLE ANf. SUBTITLE
Review of Standards of Performance for Electric Arc
Furnaces in Steel Industry
9 PERFORMING ORGANIZATION NAME AND ADDRESS
Office of Air Quality Planning and Standards
Environmental Protection Agency
Research Triangle park, North Carolina 27711
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
2.
3. RECIPIENT'S ACCESSION-NO.
5. REPORT DATE
October 1979
6. p;-.nr-r>HMiNG ORGANIZATION CODE
. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
DAA for Air Quality Planning and Standards
Office of Air, Noise, and Radiation
U.S. Environmental Protection Agency
Research Triannlp Park, N.O. 27711
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA/200/04
15. SUPPLEMENTARY NOTES
16. ABSTRACT
The purpose of this study is to review the current new source performance
standards iNSPSy for electric arc furnaces (EAF, in the steel industry and to
assess the need for revision on the basis of developments that either have occurred
or are expected to occur in the near future: this document contains background
information, current status of emission control technology for EAF s, and
recommendations for revision of the standard.
17.
a.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Air Pollution
Pollution Control
Standards of Performance
Electric Arc Furnaces
Particulates
13.
DISTRIBUTION STATEMENT
Unl imited
b. IDENTIFIERS/OPEN ENDED TERMS
Air Pollution Contr
19. SECURITY CLASS (Tlui Report)
Unclassified
20. SECURITY CLASS (This page)
Unclassified
c. COSATi Field/Group
3l 13 B
21. NO. OF PAGES
56
22. PRICE
EPA Form 2220-1 (9-73)
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