United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
EPA-600/2-78-118e
June 1978
Research and Development
Pollution Effects of
Abnormal
Operations
in Iron  and Steel
Making - Volume V.
Electric Arc Furnace,
Manual of Practice

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                    RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental Protec-
tion Agency, have been grouped into nine series. These nine broad categories were
established to  facilitate further development and application of environmental tech-
nology. Elimination of traditional grouping was consciously planned to foster technology
transfer and a maximum interface in related fields. The nine series are:

          1. Environmental Health Effects Research
          2. Environmental Protection Technology
          3. Ecological Research
          4. Environmental Monitoring
          5. Socioeconomic Environmental Studies
          6. Scientific and Technical Assessment Reports (STAR)
          7. Interagency Energy-Environment Research and Development
          8. "Special" Reports
          9. Miscellaneous Reports

This report has been assigned to the ENVIRONMENTAL PROTECTION TECHNOLOGY
series. This series describes research performed to develop and demonstrate instrumen-
tation, equipment, and methodology to repair or prevent environmental degradation from
point and non-point sources of pollution. This work provides the new or improved tech-
nology required for the control and treatment of pollution sources to meet environmental
quality standards.
                             REVIEW NOTICE


          This report has been reviewed by the U.S. Environmental
          Protection Agency, and approved for publication.  Approval
          does not signify that the contents necessarily reflect the
          views  and policy of the Agency, nor does mention of trade
          names or commercial products constitute endorsement or
          recommendation for use.


          This document is available to the public through the National Technical Informa-
          tion Service, Springfield, Virginia 22161.

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                                         EPA-600/2-78-118e
                                                  June 1978
Pollution  Effects of Abnormal Operations
   in Iron and Steel Making  -  Volume V.
              Electric Arc Furnace,
                Manual of Practice
                             by

             D.W. VanOsdell, B.H. Carpenter, D.W. Coy, and R. Jablin

                      Research Triangle Institute
                         P.O. Box 12194
                Research Triangle Park, North Carolina 27709
                      Contract No. 68-02-2186
                     Program Element No. 1AB604
                  EPA Project Officer: Robert V. Hendriks

                Industrial Environmental Research Laboratory
                  Office of Energy, Minerals, and Industry
                   Research Triangle Park, NC 27711
                          Prepared for

                U.S. ENVIRONMENTAL PROTECTION AGENCY
                   Office of Research and Development
                      Washinaton DC 20460

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                                     PREFACE

     This study of the environmental effects of substandard, breakdown, or
abnormal operation of steelmaking processes and their controls has been made to
provide needed perspective concerning these factors and their relevance to
attainment of pollution control.  The use of the term Abnormal Operating
Condition (AOC) herein, in characterizing any specific condition should not be
construed to mean that any operator is not responsible under the Clean Air Act
as amended for designing the systems to account for potential occurrence in
order to comply with applicable State Implementation Plans or New Source
Performance Standards.
                                        ii

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                                 ACKNOWLEDGMENT

     This report presents the results of a study conducted by the Research
Triangle Institute (RTI) for the Industrial Environmental  Research Laboratory
of the Environmental Protection Agency (EPA) under Contract 68-02-2186.  The
EPA Project Officer was Mr. Robert V. Hendriks.
     The project was carried out in RTI's Energy and Environmental Research
Division under the general direction of Dr. J.  J.  Wortman.  The work was
accomplished by members of the Process Engineering Department's Industrial
Process Studies Section, Dr. Forest 0. Mixon, Jr., Department Manager,  Mr. Ben
H. Carpenter, Section Head.
     The authors wish to thank the American Iron and Steel Institute for their
help in initiating contacts with the various steel companies and for their
review of this report.  Members of the AISI study committee were:  Mr.  William
Benzer, American Iron and Steel Institute; Mr.  Stephen Vajda, Jones and
Laughlin Steel Corporation; Dr. W. R. Samples,  Wheeling-Pittsburgh Steel
Corporation; Mr. Tedford M. Hendrickson, Youngstown Steel; and Mr. John R.
Brough, Inland Steel Company.  Acknowledgment is also given to the steel
companies who participated in this study.

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                                TABLE OF CONTENTS


                                                                          Page

LIST OF FIGURES                                                             v>

LIST OF TABLES                                                             vii
INTERNATIONAL SYSTEM OF UNITS AND ALTERNATIVE (METRIC)  UNITS WITH
CONVERSION FACTORS                                                        vili

1.0  INTRODUCTION                                                             1

     1.1  Purpose and Scope                                                   1
     1.2  Definition of Abnormal Operating Condition (AOC)                     2

2.0  ELECTRIC ARC FURNACE (EAF) STEELMAKING                                   3
     2.1  Flow Plan and Material Balance                                      3

          Charging                                                            4
          Meltdown, Oxidation, and Refining                                   6
          Tapping and Pouring                                                 7
          Slag                                                                8
          Further Information                                                 8
3.0  CONTROL TECHNIQUES AND EQUIPMENT                                         9
     3.1  Emissions from an Uncontrolled EAF                                  9
     3.2  Arc Furnace Emission Standards                                    11
     3.3  Emissions Capture Systems                                         11
     3.4  Emission Control Systems                                          14

          Fabric Filtration                                                 14
          Electrostatic Precipitation                                       16
          Wet Scrubbers                                                     17
4.0  ABNORMAL OPERATING CONDITIONS                                          18
     4.1  Process Related Abnormal Operating Conditions                     18

          4.1.1  Startup                                                    18
                 Burn-In                                                    18
          4.1.2  Shut Down                                                  18
          4.1.3  Abnormal Operating Conditions                              19
                 Abnormal Furnace Reactions                                 19
                 Poor Scrap Quality                                         19
                 Improper Oxygen Lance Practice                             20
                 Capture Duct Misalignment                                  20
                 Running Stoppers                                           20


                                      iv

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                           TABLE OF CONTENTS  (cont'd)
                                                                           Page
                 Ladle Breakout                                              21
                 Wind Conditions                                             21
                 Pit or Charging Explosions                                  21
                 Relief Damper Opening                                       21

     4.2  Control Equipment Related                                          22

          4.2.1  Baghouse AOC                                                22

                 Stack Puff on Startup                                       22
                 Bag Failure                                                 23
                 Bag Blinding                                                24
                 Shaker or Reverse Air System Failure                        24
                 Dust Removal System Breakdown - Baghouse                    25
                 Fan Failure                                                 26

          4.2.2  Electrostatic Precipitator AOC's                            27
          4.2.3  Scrubber AOC's                                              28

5.0  TABULATED SUMMARY OF AOC                                                29

6.0  REFERENCES                                                              33

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                                 LIST OF FIGURES
Figure                                                                     Page

  1        Material  balance of electric arc furnace based on 1000 kg
          of steel  produced                                                   5

  2       Fume collection systems                                            12

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                                 LIST OF TABLES

Table                                                                      Page
  1       Chemical Analysis of Electric Arc Furnace Fume                     10
  2       Electric Arc Furnace Abnormal Operating Conditions                 30
                                     vii

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          INTERNATIONAL SYSTEM OF UNITS AND ALTERNATIVE (METRIC) UNITS
                             WITH CONVERSION FACTORS
Quantity
mass
vol urne
concentration or
rate
energy
force
area
SI Unit/Modified SI Unit
kg
Mg (megagram =10  grams)
Mg
Gg (gigagram = 10  grams)
m  (cubic meter)
dscm (dry standard cubic meter)
scm (standard cubic meter: 21C, 1 atm)
a (liter = 0.001 m3)
   3         3
g/m  (grams/m )
    3              *3
mg/m  (mi 11igrams/m )
gAg
J (joule)
    3              -3
kJ/m  (kilojoules/m )
MJ (megajoules = 10  joules)
MJ/Mg
kPa (kiloPascal)
1 Pascal = 1 N/m2 (Newton/m2)
 o
m  (square meter)
Equivalent To
2.205 Ib
2205  Ib
1.1025 ton

35.32 cf
0.437 gr/ft
0.000437 gr/fr
2  Ib/ton
0.000948 Btu
0.02684 Btu/ft:
0.430 Btu/lb
859 Btu/ton
0.146 lb/in2
                                                                 10.76 ft'
                                      viii

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                               1.0  INTRODUCTION
1.1  PURPOSE AND SCOPE
     Air and water pollution standards, generally based upon control of dis-
charges during normal (steady-state) operation of a control system, are fre-
quently exceeded during "upsets" in operation.  When such upsets become repetitive
and frequent, the regional and local enforcement agencies undertake, through
consent agreements, to work with the plant toward resolution of the problem,
and plans are developed for equipment and operating practice changes that will
eliminate or alleviate the frequent violations.  Should the planning process
fail to resolve abnormally frequent occurrences of malfunctions, the problem
may lead to litigation.  Thus, periods of abnormal operation are becoming
recognized as contributing to the emission of high concentration of pollutants.
Similarly, upsets contribute to spills of excessive amounts of effluent-borne
pollutants into waterways.
     There is a need for information concerning abnormal operating conditions
(AOC):  their identity, cause, resulting discharges, prevention, and minimiza-
tion.
     The purpose of this manual is to alert those who deal with environmental
problems on a day-to-day basis to the potential problem areas caused by abnor-
mal conditions, to assist in determining the extent of the problem created by
abnormal conditions in a specific plant, and to provide help in evaluating any
efforts to reduce or eliminate the problems.  Electric arc furnace steelmaking
is discussed in this manual.  The other manuals developed as part of this
project deal with sintering, blast furnace ironmaking, open hearth steelmaking,
and basic oxygen process steelmaking.
     This manual is based on review of somewhat limited data, including visits
to four electric arc furnace shops, interviews with persons intimately involved
in either steelmaking or attendant environmental regulations, and the expertise

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of the study team.  It is, therefore, a preliminary assessment which concen-
trates on enumerating as many of the conditions as possible, with emphasis on
those which have the most severe environmental impact.
     Each arc furnace shop visited differed somewhat from all the others; fur-
nace design, shop design, fume collection equipment, emission control equip-
ment, and operating practice and philosophy all varied.  Variations in equip-
ment and process are reflected by variations in AOC's.  The flow sheets and
material balance presented are examples and not average values, as the avail-
able information is generally insufficient to justify averages.
1.2  DEFINITION OF ABNORMAL OPERATING CONDITION (AOC)
     In general, an abnormal operating condition (AOC) is considered to be that
which departs from normal, characteristic, or steady-state operation, and
results in increased emissions or discharges.  In addition to abnormal operations,
this study includes startup and shut down difficulties of processes and control
equipment.  It also includes substantial variations in operating practice and
process variables, and outages for maintenance, either scheduled or unscheduled.
     The use of the term Abnormal Operating Condition (AOC) in characterizing
any specific condition should not be construed to mean that any operator is
not responsible under the Clean Air Act as amended for designing the systems
to account for potential occurrence in order to comply with applicable State
Implementation Plans or New Source Performance Standards.

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                   2.0  ELECTRIC ARC FURNACE (EAF) STEELMAKING

     The direct-arc EAF commonly used for steel making today was developed in
France in the late 1800's by Paul Heroult.  This EAF is distinguished from
other electric furnaces by the patterns of heat and electrical current flow.
In the basic-lined, direct-arc furnaces discussed here, the current flow is
from an electrode to the metal through an arc, through the metal, and then to
another electrode through a second arc.  The needed heat is generated both by
the arcs and by the electrical resistance of the metal.
     The EAF has in the past ten years or so become a major steel producing
process.  It is particularly well suited to meet two of the requirements of
modern steelmaking.  One is the EAF's ability to make steel directly from scrap
steel without the necessity of having a source of molten iron (blast furnace
and coke ovens).  Economic constraints generally favor the use of EAF's for low
to medium tonnage steelmaking facilities.
     The basic oxygen process (BOP), which requires molten iron, and the open
hearth furnace (OHF), which operates best with some molten iron, are generally
preferred when the steel complex produces something more than a million ingot
tons annually.  Even in a large steelmaking complex where the primary steel
producer is a BOP, a company may find it economical to have EAF's as well,
their purpose being to control the scrap usage or to extend steelmaking capacity
beyond that allowed by the blast furnace iron production capacity.
     The other aspect of the EAF which leads to its widespread use is the
control which can be exercised over the quality of the steel.  High quality
steels such as stainless steel, high alloy steels, and tool steels are generally
made in an EAF.
2.1  FLOW PLAN AND MATERIAL BALANCE
     The production of steel in an EAF is a batch operation consisting of
several functional elements which must be performed more or less sequentially.
The production cycle requires 1 1/2 to 5 hours for carbon steel, and 5-10

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                             o
hours for a high alloy steel.   The steel making procedures are discussed
below, while pollution control is left for the next section.   Figure 1
illustrates the EAF steelmaking process, and also presents an example material
balance.
Charging
     The initial task of an arc furnace operator is to charge the furnace with
the materials necessary to make steel.  As has been mentioned, EAF's generally
utilize scrap as the major iron bearing raw material.   As might be expected,
scrap varies considerably in composition (many possible grades of steel,
coatings, and extraneous material) and in size and shape.  The initial  require-
ment for an arc furnace shop, then, is a suitable scrap yard, preferably covered
to keep water (and ice) from the scrap as much as possible.  The scrap yard is
segregated with respect to carbon steel and various ranges of alloy steel
composition.  A scrap yard might have 5 to 10 segregated scrap bins, although
more are used in some cases;  the plants choose their classification schemes
based on the variety of steels produced and the variety of virgin alloys avail-
able.  The purpose of scrap segregation is to allow the furnace operator to
conserve the valuable alloys in the scrap and to produce a melt which is close
to the desired steel composition.  In addition, not all elements are equally
easy to add or remove from various heats, and the furnace operator must consider
these differences; sometimes the steel grade must be changed.
     Based on the materials on hand and the desired product,  a scrap "recipe"
is made up for each heat.  The scrap yard includes the necessary transfer
cranes and magnets, as well as weigh stations, to load the charging bucket with
the proper charge.  In addition, the bulk density of the scrap is considered.
Light scrap is loaded in the bottom of the furnace to somewhat cushion the
impact of heavy scrap when the charge is dumped.  The number  of backcharges
(charges after the initial filling of the furnace) is dependent on the average
bulk density of the charges and the working volume of the furnace, as is the
time required for meltdown.
     Charging of modern EAF's is done through the roof, which is removable and
has been lifted and swung aside.  The charging bucket is generally of/ the drop-
bottom type, ranging up to 4000 cubic feet in capacity, depending on furnace
size.  As has been mentioned, light scrap is dropped into the bottom of the

                                        4

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                                                  BUILDING EVACUATION SYSTEM - ItSicmMn
                                                     \
                                                 CANOPY HOOD
                                                 5S-120 scin/min
                                     ELECTRICITY - 5 kw TO MELT
                                              - >00 kw TO REFINE

                                     ELECTRODE CONSUMPTION - 5 kg
                              SCRAP-1076 kg
                              ALLOYS-VARIABLE
                              LIME - 38 kg
                              SILICA -12kg
                                                              DIRECT SHELL EVACUATION
                                                              ROOF TAP (WATER-COOLED!
                                                                                        FAN
                                                                                    12 um/min
                        CHARGING
                        BUCKET
n?*r<
 COMBUSTION AIR GAP


   STEEL -1000 kg


        STEEL LADLE
                             OXYGEN-4.1-25 m
                                                                                                      CLEANED GAS IOUVERS
                                                                                                         BAGHOUSE
                                                             \/\/\/
                                                                SCREW CONVEYORS
                                                                                COllECTEO
                                                                                OUST (10 15 kg)
                                                                                                   INGOT MOLDS
Figure  1.   Material  balance  of electric  arc furnace  based  on  1000 kg of steel  produced.

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furnace and is also dropped along the walls to shield the refractory from the
arc during early meltdown.  Heavy scrap is charged in the area near the
electrodes.  Alloying materials which are not easily oxidized can also be
charged before meltdown, as may iron ore and coke.  Limestone, silica, and a
small amount of fluorspar are also added as fluxing agents.
Meltdown, Oxidation, and Refining
     Once the furnace is properly charged the metal must be melted, the excess
carbon removed by oxidation, and the metals' values adjusted by refining.
Before discussing these operations in detail, a description of the furnace
itself is in order.
     The modern, large EAF as discussed in this report has a squat cylindrical
steel shell lined with refractory material and equipped with a tight-fitting,
refractory-lined roof.  The electrodes (generally three, either graphite or
carbon) enter the furnace through holes arranged equilaterally around the
center of the roof.  The vertical position of the electrodes is adjustable and
they can be raised completely out of the furnace.  Most large EAF's are top
charged, and the roof is often independently supported so that it can be lifted
slightly and swung aside.  Openings are present in the furnace body for both
steel and slag removal, and appropriate pouring spouts are provided.  Other
doors or openings are sometimes also provided, and are necessary if some side
charging is anticipated.  The EAF is mounted on rockers so the furnace can be
tipped forward for tapping and back to remove slag.
     The discussion in this document deals primarily with the basic-lined EAF,
referring to the type of refractory used in the lining and the operating
practice which is compatible with this lining.  Acid-lined furnaces have some
advantages, but require carefully selected scrap for successful operation and
are not widely used today in steel production.
     Meltdown of a charged EAF is begun by lowering the electrodes to within an
inch or so of the scrap, setting a starting power level, and striking the arc
under automatic control.  After a few minutes, during which the electrodes bore
into the scrap, the power can be increased to its maximum in order to melt the
scrap as fast as possible.  As the electrodes melt the scrap, a pool of molten
metal forms in the bottom of the furnace, melting the scrap in that area.
While operating, the furnace electrodes are consumed at a rate of around 5
kg/Mg (10 Ibs/ton) of steel produced.
                                      6

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     Oxidation of the melt begins as soon as molten metal is present.  Oxygen
is present both from injected oxygen and from chemical reactions in the bath
which make oxygen available.  The oxidation process removes carbon as CO and
C02, and various metal oxides are formed as well.
     Refining the steel in the melt is basically a process of removing unde-
sirable elements while either adding or preventing the removal of desired
elements.  Generally, carbon, sulfur, and phosphorus must be removed to within
some limits, and the other components adjusted as needed.  The major reactions
take place at the slag-melt interface, and agitation improves the reaction
rate.
     Refining can be carried out under either a single or a double slag pro-
cedure.  In both cases the meltdown slag forms during oxidation and contains
the oxidation products along with the slagging agents lime and silica.  Phos-
phorus and carbon are the main impurities removed under the meltdown slag,
along with some sulfur and other nonmetallics.  In the single slag process the
meltdown slag is made reducing within the EAF by the addition of the materials
needed to achieve a carbidic slag.  In the double slag procedure, the meltdown
slag is removed and a new, carbidic slag made up by the addition of 5-8 parts
lime, 1/2 to 2 parts fluorspar, 1 to 2 parts coke, and 1/2 to 1 part silica.
In both cases the reducing slag tends to force certain reducible metal oxides
from the slag to the melt, and these metals (manganese, chromium, and others)
can be added to the bath at this time without excessive loss.  In addition,
oxides are removed from the bath, and sulfur is removed as calcium sulfide.
The double slag process gives better control of the steel composition, and is
particularly important for high alloy steels.
Tapping and Pouring
     After the steel has been tested and the composition adjusted if necessary,
the steel is transferred from the furnace to a ladle.  The electrodes are
raised out of the bath and the furnace tilted so that the heat can be tapped
into the ladle.  The ladles are similar to those used in other steelmaking
operations, being refractory-lined with an operable refractory valve in the
bottom.  A slag layer is carried on top of the steel for insulation.  The steel
is transferred within the ladle to either the teeming area, where ingot molds

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are filled directly from the ladle, or to the vicinity of a continuous caster,
where the steel is poured into a "tundish", which controls the steel  flow to
the caster.
Slag
     Slag from the EAF is either poured into a slag ladle and removed or poured
on the floor under the furnace, where it is allowed to cool  and is removed by
front end loader.
Further Information
     The reader desiring further information concerning steelmaking practice
should begin with The Making, Shaping, and Treating of Steel, published by the
U.S. Steel Corporation.
                                      8

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                      3.1  CONTROL TECHNIQUES AND EQUIPMENT

3.1  EMISSIONS FROM AN UNCONTROLLED EAF
     The major pollution control task facing an EAF operator is that of pre-
venting emissions to the air.  The waste gas flow rate and composition as  well
as the particulate loading and composition vary widely during a heat.   As  was
shown in Figure 1, the normal gas emissions after combustion are around 12
scm/Mg steel (350 scf/ton steel), the gas containing about 10-15 kg of par-
ticulate per Mg of steel (20-30 Ib/ton).  Particulate loadings from 6  to 29
kg/Mg of steel (12-58 Ib/ton steel) have been cited.2'3'4  Table 1  presents
data indicating the changes in dust composition throughout a heat.   As might be
expected, most of the dust is iron oxide, although during the time  the reducing
slag is on the furnace CaO becomes the major constituent of the dust.   The
particle size of EAF dust is quite small, one source  citing 95 percent of the
dust less than 2.0 pm in diameter, and a mean size of 0.5 ym.  Gas  composition
also varies widely throughout the heat; during oxygen lancing the off  gas
(prior to combustion) is around 30 percent CO, 0.5 percent 09, and  the rest  N9,
                                                               5
although CO values as high as 88 percent have been encountered.  Another
source cites a composition of 63 percent CO, 2 percent COp, 4 percent  H^,  and
31 percent Np for the same gas.   The high concentrations of combustibles
leaving an EAF during a heat require that steps be taken either to  dilute  the
gas to below the explosive limits or to burn the flammable gases under con-
trolled conditions.  The latter case is used by those collection systems which
attempt to minimize the collected gas volumes.
     Charging an EAF results in heavy emissions which are hard to capture.
Scrap cleanliness plays a big part in the rate of emissions, as scrap  contam-
inated with dirt, water, grease, oil, or heavy rust causes increased emissions.
Charging emissions contain carbonaceous material, indicative of their origin.
     The highest furnace emissions occur during meltdown and the subsequent
oxidation process.  The fume characteristics are dependent on such  parameters
as charge composition, electrical power input, and scrap size.   Oxygen lancing
                                      9

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                           TABLE  1.   CHEMICAL  ANALYSIS OF ELECTRIC ARC FURNACE FUME5
Phase

Melting
Oxidizing
Oxygen Lancing
Reduction
Dust Composition
% Si00 % CaO % MgO % Fe.,0,1 % A100, % MnO % Cr00, % SO. %P~0,
^ . 
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increases the emission rate significantly.  Otherwise gas evolution is not high
during the refining period, and the emission rate is moderate.  Tapping emissions
are difficult to capture, as the furnace is tilted out of reach of the control
device.  The emissions occur both from the furnace and from the ladle.
3.2  ARC FURNACE EMISSION STANDARDS
     New Source Performance Standards (NSPS) have been promulgated by the U.S.
EPA for EAF's in the steel industry.   These standards regulate particulate
emissions from the control device, from the shop, and from the dust-handling
equipment.  Control device emissions are limited to less than 12 mg/dscm
(0.0052 gr/dscf) and 3 percent opacity.  Emissions which bypass the collection
system are limited to 0 percent opacity with the exceptions that emissions
may reach 20 percent opacity during charging and 40 percent during tapping.
Emissions from the dust-handling equipment are limited to 10 percent opacity.
3.3  EMISSIONS CAPTURE SYSTEMS
     Several methods have been developed to capture the primary emission from
an EAF.  Some of the basic types are discussed below.  Combinations and varia-
tions are common.
     Hooded Furnace fume collection systems have been used for some time.  The
hood is placed down close to the furnace, and an attempt is made to capture the
fume as it escapes from the furnace (Figure 2a).  The hoods do not capture
charging and tapping emissions.  At high working rates and with oxygen blowing,
these close-fitting hoods have been found to be comparatively less effective
                                    3
and are used only on small furnaces.   These hoods generally draw in sufficient
dilution air to eliminate the explosion hazards without special provisions.
     A Direct Shell Evacuation (DSE) system keeps the furnace under a slight
vacuum, causing all the fumes to leave the furnace through the suction duct.
The suction duct entry into the furnace may be either through the roof or
through the sidewall; entry through the roof via a replaceable water-cooled
elbow has been found to be the preferred arrangement.  As shown in Figure 2b,
the exit end of the furnace elbow is aligned with a fixed duct leading to the
control equipment.  The gap between the elbow and the fixed duct is sized to
admit sufficient air for combustion and dilution, and the initial length of  the
fixed duct serves as a combustion chamber.  Both the furnace elbow and the
                                       11

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    er.ruus.%s
  a.  Furnace Hood
b.  Direct Shell Evacuation

c.  Semi-direct Evacuation
    d. Canopy Hood
                 Figure 2.  Fume  collection  systems.
                                 12

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combustion chamber are generally refractory lined and water cooled.  In con-
junction with the DSE system, the electrode holes can be shielded, using air
curtain seals, to prevent puffing through those ports.  A water-cooled damper
is needed in the elbow to control furnace pressure.  The DSE system has the
potential advantage of collecting the smallest total gas volume of all the
collection systems, around 12 scm/min per 1000 kg of steel (350 scfm/ton)
including combustion air.  The DSE system is not effective against charging and
tapping emissions, and its efficiency is reduced if furnace doors beyond those
planned for are opened.  In addition, the DSE system cannot be used with double
slag practice because the reducing slag cannot be maintained with air entering
the furnace.
     The Semi-Direct Evacuation  (SDE) system attempts to clean the smallest
practical air volume while remaining compatible with double slag practice.
Again, the fume exits the furnace through a hole in the roof (Figure 2c), but
the furnace remains under positive pressure and the fume leaves at its own
rate.  The total waste gas volume can be kept as low as 2 to 2 1/2 times that
required by a DSE system.  Combustion takes place in the refractory lined hood.
As with all the close-fitting capture systems, charging and tapping emissions
are not controlled.
     Canopy Hoods (CH) are suspended above the furnace and attempt to capture
the fume as it rises from the EAF (Figure 2d).  A CH is the least effective
means of capturing normal EAF emissions, although it does have the advantage of
capturing emissions during charging and tapping.  Design of the CH's has been
                                                           o
aided by modeling studies of the flow patterns of the fume.   The hoods are
generally 30-40 feet above the furnace to allow clearance for the cranes, and
they draw in large volumes of air.  As was shown in Figure 1, a CH can be
successfully combined with a DSE system, the CH providing enough dilution air
to cool the gas for cleaning in a baghouse.  CH's are sometimes partitioned
into sections, and the majority of the draft diverted to the tapping side or
charging side as appropriate.  Fume evacuation rates range from around 55 to
120 scm/min per 1000 kg of steel (1650-3650 scfm/ton), the lower rates generally
being associated with open roof shops and the higher rates with closed roof
shops.  The effectiveness of a CH is considerably affected by building layout
and cross-drafts within the building.
                                       13

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     A Building Evacuation (BE) system can be thought of as a logical  extension
of the CH concept.  The entire arc shop building serves as the capture hood.
The BE system requires the control device to clean huge quantities of air, but
it does capture all emissions within the shop.  A BE system is designed to
handle the average emissions from the EAF's in the shop, so there is generally
a buildup of fume in the top of the building during periods of very heavy
emission, followed by clearing as the emission rate drops off and the BE system
continues to draw fume out of the building.  At least one shop has found it
advantageous to use CH's as the collection points for the BE system, capturing
more of the heavy fume as it is emitted and reducing buildup in the shop.  The
main criticisms of the BE systems are the high cost and energy use associated
with the huge gas volumes [165 scm/min per 1000 Kg steel (5000 scfm/ton)]
and the fact that even a low concentration of emissions at the very high gas
rate amounts to a significant total mass emission.
3.4  EMISSION CONTROL SYSTEMS
     The most effective of the EAF emission capture systems (with the exception
of BE) will normally contain 95-97 percent of the total fume generated.    Most
of that which escapes collection does so during charging and tapping.   This
section deals with cleaning the gas which is captured.
     The NSPS as promulgated allow the use of any control device, the principal
candidates being fabric filtration, high-energy venturi scrubbers, and electro-
static precipitators (ESP's).  All three processes are discussed below.  However,
fabric filters (commonly baghouses) appear to best match the requirements of
the NSPS for both very high efficiency cleaning and some secondary emission
control.
Fabric Filtration
     With respect to use on EAF's, baghouses have generally been quite success-
ful, and the design parameters are well known by now.  The emissions data used
in setting the NSPS were collected at a baghouse.  The two prime considerations
are to control temperature and to keep the bags dry.  Both criteria are gen-
erally met by using baghouses on CH systems, BE systems, or a combination of
DSE and canopy hood because of the large volume of dilution air present.
                                       14

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     Baghouses can be operated either as pressure systems or suction systems.
In pressure systems the fan is on the dirty side of the baghouse, and only the
dirty side of the baghouse must be kept airtight.  The clean gas is generally
discharged through louvers or monitors near the top of the baghouse and a stack
is not required.  For this reason, emissions from a pressure baghouse are
difficult to monitor.  On the minus side, operating the fan on the dirty side
of the system allows dirt buildup on the fan blades, a potential source of
imbalance and subsequent fan maintenance problems.  Placing the fan on the
clean gas side relieves this problem, but the entire baghouse must be under
vacuum and kept airtight.  The fan is placed at ground level for access, and a
stack must be provided.  Pressure baghouses have been successful on EAF's
without excessive maintenance, so apparently the dry conditions coupled with
the particulate loadings and characteristics reduce dust buildup to a manage-
able level.
     Baghouses can be cleaned with either a shaker mechanism or reverse-air
                                                               o
flow.  No clear advantage for one system has been demonstrated.   The three EAF
                 911 12
baghouses visited ''   during the course of this study all utilized reverse-
air cleaning.  Polyester bags were used to collect the dust, and the face
velocity in the baghouses was 0.76 to 0.91 m/sec (air-to-cloth ratio of 2.5-3.0
ft3/min/ft2).  Bag life has been 5-6 years.
     Continuous baghouses such as are described here generally have several
compartments which are cleaned independently in sequence.  The cycling is
handled automatically.
     In the design of a baghouse it is important to make provisions for routine
maintenance.  In addition to providing access to separate compartments, the
removal of individual bags must be considered.  In general, increasing the
spacing between bags and reducing the "reach" (the number of bags which make up
a row) make a baghouse easier to maintain.  The EAF baghouses visited during
this study ''   were designed with a three-bag reach and 5 cm (2 in.) spacing
between bags.
     As has been mentioned, temperature is an important parameter in baghouse
design.  The baghouse fume collection system must include a means of maintain-
ing a safe temperature, around 122C (250F) for polyester bags.  Polyester is
commonly used because of its resistance to fluorine compounds  (from fluorspar
                                        15

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added as flux) as opposed to fiberglass bags, which have a higher temperature
rating but are adversely affected by hydrofluoric acid.
     Dust handling for baghouses generally involves collection in hoppers,
followed by transport in screw conveyors to a central location, where the dust
can be pelletized or removed to a landfill.
Electrostatic Precipitation
     The successful use of ESP's on arc furnaces requires that the resistivity
of the arc furnace dust be carefully controlled.  Both conditioning of the dust
and temperature control are necessary.  The resistivity of the dust is too high
for successful collection between about 50C and 250C (120F and 480F).
Outside of that range successful collection can be achieved if the gas stream
is humidified, generally with water sprays serving to both cool and condition
the gas.  Maintaining the proper conditions of temperature and humidity through-
out the operational cycle is a difficult problem,  although it has been done on
many furnaces.
     The cooling and humidification are done in a wet spark box.  The target
humidity is in the range of 10 to 20 percent, with recent experience suggesting
the high end of the range.  Banks of sprays controlled by temperature are
necessary, as is good atomization and water distribution at both high and low
flows.  Within the precipitator itself condensation must be prevented.  The
frequency and intensity of rapping is important in order to keep the plates
clean.  The fan is generally located on the clean side of the ESP.
     The statements above apply to a dry ESP.  It is also possible to use a wet
ESP, in which the collection plates are washed clean rather than "rapped" to
knock the dust loose.  The same general design considerations apply, except
that the gas should be saturated with water to prevent iron oxide from bonding
                                     3
to the electrodes and other surfaces.
     While ESP's can do a creditable job of cleaning fume from an EAF, alone
they are unlikely to meet NSPS.  ESP's are not particularly well suited to
cleaning the large volumes of gas from a canopy hood.  The temperature is too
low for effective cleaning.
                                       16

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Wet Scrubbers
     A high-energy wet scrubber may be utilized to remove particulate matter
from the EAF fume.  As outlined in the Federal Register,  a scrubber system
operating to clean the DSE fume to approximately 23 mg/dscm (0.01 gr/dscf)
coupled with a baghouse on a CH (and cleaning the effluent to 9 mg/dscm
(0.004 gr/dscf) would meet NSPS.
     Scrubbers have a very high energy requirement per unit volume of gas
handled when operated at the high efficiencies required by the NSPS.  According
to one source, more than 150 cm WG (60 in. WG) would be required to clean EAF
fume to 9 mg/dscf (0.004 gr/dscf).   The scrubber system would include a
preconditioning vessel to cool and humidify the gas.  Saturation of the gas is
necessary to prevent problems with the dust bonding to the scrubber surfaces.
Adequate residence time must be provided to achieve complete humidification.
Following the scrubber, a demister is required.  The fan is placed downstream
of the demister.  Slurry removal equipment is needed for the bottom of the
                                                     q
collector, and wastewater treatment must be provided.
                                        17

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                       4.0  ABNORMAL OPERATING CONDITIONS

     The following sections of this manual  discuss the AOC's related to EAF
operation.  The problems directly related to the process  itself are considered
first, followed by sections on the pollution control  equipment as  applied to
EAF's.  The importance of a given AOC in terms of environmental  effect is not
necessarily indicated by the length of the discussion. Simple descriptions of
severe problems are possible, while less serious conditions  may require elab-
orate explanation.  It should be noted that BE shops  do not  suffer additional
emissions due to process AOC's.  All the emissions within the shop are col-
1ected.
4.1  PROCESS RELATED ABNORMAL OPERATING CONDITIONS
4.1.1  Startup
       For the purposes of this manual, startup is defined as bringing a new
vessel into service or restarting a cold vessel.  The beginning of each new
operating cycle is not considered a startup.
Burn-In
     Burn-in relates to bringing a new or newly lined vessel into  service.
While the refractories used in most EAF's do not require  burn in,  portions  of
the lining sometimes do.  Tar-bonded refractories are an  example.   When needed,
burn-in is accomplished by putting burning coke into  the  furnace and operating
the oxygen lance.  The emissions from this procedure  have not been quantified;
they are carbonaceous in composition.  As the furnace-lining life  is around
100-200 heats, burn-ins occur on a given furnace about once  every  month or two,
depending on heat time and production rate.
4.1.2  Shut Down
       No specific AOC's were identified with respect to  shut-down of an EAF.
                                       18

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4.1.3  Abnormal Operating Conditions
Abnormal Furnace Reactions
     The melting of steel scrap and the backcharging of an electric arc furnace
are normally periods of turbulence within the vessel due to arcing, rapid
vaporization, and gas-generating reactions; fume generation is high during
these periods.  Fugitive fume emissions often occur during these operations.
Contamination of the scrap with oil, grease, water, dirt, concrete, ice, or
similar material exacerbates the situation, and cause abnormal emissions.
Furnace additions of some metals during the oxygen blow can also cause abnormally
violent reactions and emissions.  Abnormal furnace reactions might be considered
to be the generation of fume at a rate above that which the furnace control
system can collect at times other than during meltdown.
     If the EAF shop includes a CH, a portion of this escaping fume will be
captured.  Based on limited data, the duration of an emission due to abnormal
furnace reactions ranges from 2 to 5 minutes.  No estimate of emission rates
was available.  One shop   estimated one occurrence per month, but differences
of opinion as to what constitutes an AOC impact this type of upset strongly.
Corrective measures include reducing oxygen blowing rate and/or electrical
power input, and increasing the furnace draft.  Careful selection of scrap and
proper storage are preventative measures.  These conditions are generally of
short duration and require fast response by the operators.
Poor Scrap Quality
     The general level of emissions from an EAF goes up as the quality of the
scrap goes down, even in the absence of severe reactions as described above.
One arc shop   which we contacted estimated that poor quality scrap led to a
third more particulate emissions as measured by the amount of dust collected in
the control device.  This increase in captured dust indicates an increase in
emissions, both from the control device and from uncontrolled emissions.  The
extent to which scrap quality can be controlled varies from shop to shop,
depending on the amount of home scrap available, and purchased scrap price and
availability.
                                        19

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Improper Oxygen Lance Practice
     The additional fume generated by oxygen lancing can be influenced by the
position of the lance within the vessel.  Shops which rely upon manually placed
lances for oxygen injection therefore have variable emissions from oxygen
lancing.  The extra emissions become especially significant if the fume is
generated at a rate which overloads the fume-collection system, causing
emissions into the shop.  Excessive fume can also be generated by blowing with
high oxygen rates.  No data are available to quantify emissions due to improper
lance practice.
Capture Duct Misalignment
     As has been described, the DSE method of fume collection requires that an
elbow be attached to the furnace roof and that this elbow be aligned with a
fixed duct for fume collection.  A gap is left between the two flange faces
(the furnace elbow and the fixed duct) to admit combustion air and to allow
tilting of the furnace.  The severity of the process conditions at this point
demands that the clearances be generous and the construction substantial.  When
the furnace is tilted the two ducts are not aligned and the efficiency of
furnace evacuation drops off rapidly.  Under conditions of foaming slag or
severe reactions due to oxygen lancing, the EAF is tilted to keep the slag in
the furnace.  Misalignment of the duct occurs, and increased emissions ensue.
If the shop utilizes a canopy hood and maintains draft on it at all times, a
significant portion of the fume can be captured.  Firm data on the frequency
with which this AOC occurs is not available: one shop   estimates that it
occurs daily with an estimated duration of 10 minutes.  Another estimate was
that it occurred "frequently."  Capture duct misalignment was observed during
the visits to both shops utilizing DSE.
Running Stoppers
     A running stopper occurs when a steel ladle develops a leak at the nozzle
in the bottom of the ladle.  The problem can range between a slight leak and a
full-running stopper.  The steel dropping onto the shop floor is very dangerous
as well  as a cause of emissions.  The shop generally has an emergency ladle
station, which is used to contain the steel if necessary.
                                        20

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     Stopper rod ladles may be more likely to have problems than slide-gate
ladles.  One arc shop's   experience with slide-gate ladles was better than
99.5 percent dry pours, while stopper rod ladles were estimated at around a
percent lower.  Slide-gate ladles cannot be used with all grades of steel,
however.  No data are available to quantify the emission.
Ladle Breakout
     A ladle breakout occurs when the molten steel penetrates worn refractory
in a ladle and melts a hole through the ladle.  The effects are similar to
those of a running stopper, and the extent of the problem dependent on the size
and location of the breakout.  Only a general estimate of frequency (one break-
out per year per EAF shop) was obtained, and no estimate of emissions was
available.
Wind Conditions
     Wind within the arc shop can significantly influence the collection effi-
ciency of a CH.  Wind effects become more important when a shop is not totally
enclosed.  Baffles and louvers can be used to direct the air flows within the
shop.  No data are available to quantify this effect.  The problem was not
observed.
Pit or Charging Explosions
     Explosions are generally caused by contact between molten steel  or slag
and water.  The water flashes to steam and the explosion splashes  molten metal
or slag around the shop.  The explosion usually shakes the building enough to
stir up settled dust and cause a minor emission.
     No data were available for EAF shops; for BOF shops, these explosions were
estimated to occur a few times per year.
Relief Damper Opening
     The fume capture systems generally include emergency relief or bypass
dampers for pressure relief and temperature protection.  Pressure and temperature
excursions are not common problems for EAF shops because the arc shops practice
less decarburization and use lower oxygen injection rates.  The large amount of
                                        21

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dilution air used for baghouse systems greatly reduces the likelihood of
temperature excursions.  Of the four arc shops visited (two of which were BE
systems) only one instance of relief damper opening was reported, and that
was due to failure of the instrumentation rather than to process problems.
     If the situation did occur, the total fume production would be vented to
the atmosphere as long as the furnace(s) remained in operation with the damper
open.  A shop with open monitors could probably continue to operate, but at a
reduced rate in order to maintain suitable working conditions.
4.2  CONTROL EQUIPMENT RELATED
     As has been mentioned, each of the three generic gas cleaning systems is
used to control EAF emissions in the United States, although baghouses are by
far the most common.  Within this section, control equipment-related AOC's are
discussed, beginning with baghouses.  The baghouse is the only control device
discussed in depth.
     The most serious AOC's associated with control devices are those which
lead to complete failure of the control device.  The EAF operator must then
decide how to handle a heat which is in the furnace, weighing the impact of his
decision on safety, emissions, and production.  Written protocols concerning
action to be taken in the event of total or partial control device failure were
not available at the shops visited in the course of this project.  AOC's which
have only a partial impact on the control device are correspondingly less
severe.
4.2.1  Baghouse AOC
Stack Puff on Startup
     Stack puff refers to a temporary increase in particulate emissions, vis-
ually recognizable, leaving the process stack.  There are stack puffs resulting
from continuous operating problems, but stack puffs during startup are caused
by particulate which was deposited on the duct floor or on flow control louvers
in the system reentraining into the gas stream.  During a fan or system shut
down dust being conveyed by the gas stream settles onto the duct floors.  Also,
where a single fan in a multiple fan system is shut down, dead or low flow
areas may develop in some duct runs leaving dust on the duct floors and flow
control  surfaces.  Upon restarting the fan, the settled dust begins to sluff
into the gas stream.
                                      22

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     The effect of this action is greatest when the deposits are downstream of
the collecting device where no chance to collect the dust exists.  It also
occurs upstream of the collector in which case the net effect is reduced by the
collector.
     The frequency in a multiple fan system can be as often as once per week,
to as little as once per year in a single fan system.  The duration of the
puffs is widely variable.  An estimate is 1 to 5 minutes, supported by obser-
vation of these and many other sources.  No data or estimate of the extent of
the additional emissions are available.
     No good corrective action for this AOC can be recommended.  If dust drop-
out in the flues is an extensive problem occurring during normal operation, it
is periodically (perhaps once per year) necessary to remove the dust to prevent
overloading of the duct structures.  Since the dust is deposited under normal
operating circumstances, it cannot be stated with certainty that dust emissions
upon startup would be any less than had the flue not been cleaned.
Bag Failure
     The environmental effect associated with a bag failure is dependent upon
the size of the hole and the time required to replace the bag.  Experience with
bags at the three baghouse-controlled EAF shops visited during this project has
been very good.  Bag life seems to be on the order of 5-6 years, perhaps longer;
annual failure rates were 0.3 percent over 7 years at one shop and  around 1
percent for 1 year at another shop.
     The common causes of bag failure are abrasion, old age, and high tempera-
ture, although it often appears that individual bag failures are related to
factors that are specific to that bag, such as the way it was handled, spark
carryover, or manufacturing defects.
     Sparks that are conveyed through the duct work to the baghouse burn holes
                                                                       12
in the bags.  A recorded instance of spark carryover in an EAF baghouse   occurred
because a scrap contaminant burned off, forming slow burning sparks that did
not extinguish in the duct residence time, as is commonly the case.  That par-
ticular installation had to replace 139 bags due to the one instance of spark
carryover.
                                        23

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     The failure or partial failure of a single bag in a compartment is not
always immediately noticeable.  The emission rate is dependent on the effective
size of the hole.  No estimates of emission rates are available, nor were we   k
able to estimate the time required before a bag is replaced.  Replacement of
bags in the modern multicompartment baghouses requires that the compartment be
closed down, the bag replaced, and the compartment put on line again.
Bag Blinding
     Bag blinding (plugging) generally occurs from moisture condensation, oils
or resin vapor condensation, or extremely fine particulate.  The effect grad-
ually increases over the life of the bags in most cases, although a serious
moisture problem could rapidly take effect.  Fine particulate can be readily
collected by baghouses given appropriate choice of fabrics and operating con-
ditions.  New bags may require preconditioning to prevent initial blinding.
The increase in emissions due to bag blinding is dependent on the reduction in
draft available within the shop.
     No estimates were available of increased emissions due to bag blinding.
One shop was replacing bags after 6-7 years due to a reduction in draft; this
should be considered a normal rather than abnormal condition and not blinding
as discussed here.  Assuming the proper bags have been selected, efforts to
prevent or reduce blinding include good temperature control (for moisture),
control of scrap contamination (oils) and good recordkeeping to identify com-
partments with blinded bags.
Shaker or Reverse Air System Failure
     Shakers or reverse air cleaning are common ways to perform bag cleaning.
Both systems may fail on a portion of the baghouse or the entire baghouse.
When the bags are not being cleaned, dust continues to build up in the affected
compartments, increasing the pressure drop.  If possible, the affected compart-
ments can be shutdown and the load shifted to others.
     No failures of the cleaning systems of EAF baghouses were identified, so
no estimates of frequency of occurrence can be made.  Efforts to minimize
emissions from this AOC should include frequent inspections of the mechanism
and preventive maintenance.  Complete failure of the cleaning system would
eventually lead to shutdown of the baghouse.

                                       24

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Dust Removal System Breakdown - Baghouse
     This AOC is produced by a myriad of causes.  Among them are broken or mis-
aligned screw conveyor shafts, plugged dust valves, bridging in the hoppers,
hopper heating failures, and hopper vibrator failures.  This AOC was common to
all the dry dust collection systems visited, although it was apparently less of
a problem for EAF systems than for other facilities.
     Failure of dust storage and removal equipment leads to full hoppers.   When
the 
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plant operators.  If nothing else, the insulation and heating prevent moisture
condensation in the hoppers.  Some people believe that hot dust is more fluid
or less "sticky" than cold dust without considering the effects of moisture.
The dusty environment of the dust valves and conveyor drives makes preventive
maintenance and frequent inspections essential  to minimizing AOC's.
     Few problems of this nature causing emissions were identified at EAF
                                                         12
shops, and essentially none in the recent past.  One shop   had suffered from
misalignment problems during startup, but had had no problems in some time.  If
hopper capacity is sufficient to hold dust until  the conveyor is repaired, no
emissions occur.  Based on all of the steel making processes visited, problems
may occur from once per week to once every couple of months.  Repair jobs
generally take 1 to 8 hours.  Emissions may or may not increase due to the
problem.
                        i
Fan Failure
     The common causes of fan failure are high bearing temperature, vibration,
loss of bearing oil, and motor failure^  The shutdown may be automatic from a
bearing temperature or vibration controller or it may be manual.  Vibration is
commonly caused by an out-of-balance condition, in which particulate has de-
posited on the fan blades or corrosion/abrasion has removed metal  from the
blades.  Fan failure in a one-fan system shuts down the entire control system,
leaving all process emissions uncontrolled.   In the more common multiple-fan
systems, the effects of loss of a single fan depends on the availability of a
spare fan, the ability of the system to operate at reduced draft,  or the amount
of excess capacity designed into the system.
     The EAF shops contacted indicated that they would reduce the  production
rate of the shop (reduced blowing, electrical input) in the event  of a signif-
icant loss of draft.  For BE shops, loss of draft means the shop fills with
smoke, so operations must be shut down.  Shops with open roof monitors can
continue to operate, and a decision would be made based on the extent of the
failure, amount of emissions produced, shop atmosphere, and the status of the
heat.
                                        26

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     The EAF shops visited had not suffered unexpected fan failures.  Shutdowns
had been planned based on suspected or  known problems and the problem repaired.
Major fan failures apparently occur at  a rate of less than one per year in a
well-maintained shop even with the fan  on the dirty gas side.  Periodic shut-
downs are needed to clean deposits off  the fan blades, but these can apparently
be scheduled between production cycles.
4.2.2  Electrostatic Precipitator AOC's
       ESP's as the main control device on EAF shops are not common in the U.S.
and cannot alone meet NSPS for EAF shops.  In addition, ESP's are unlikely to
be installed on new EAF shops.  For these reasons, the discussion of ESP abnor-
mal operating conditions will be brief  and the reader is referred to the Basic
Oxygen Process Manual from this series  for a more complete discussion.  A list
of AOC's is presented to acquaint the reader with the possible problem areas.
                                                                    13
     The ESP controlled Arc  Furnace shop visited during this project   was an
essentially trouble-free operation.  Dust handling problems had apparently been
encountered in the past, as  the rapper  control mechanism was more elaborate
than is common.  Rapping was manually initiated three times per shift, and
under certain atmospheric conditions the frequency of rapping was increased.
In addition, this EAF did not utilize screw conveyors; dust was dumped directly
from the hoppers into trucks.
     Precipitator AOC's which were identified for other precipitators include:
          Emissions during ESP warmup at startup
          Unbalanced flow among manifolded fans
          Insufficient draft due to manifolded fan failure
          Wire breakage
          Plugged or corroded humidification sprays
          Insufficient gas conditioning
          Pump failure
          Transformer-rectifier set failure
          Insulator failures
          Rapper failures
          Dust removal system problems.
                                        27

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4.2.3  Scrubber AOC's
       Like ESP's, scrubbers are not widely used to control  EAF's, especially
the larger, newer shops.  Scrubbers are not able to meet NSPS when used alone.
No EAF shop utilizing scrubbers was visited during this project, and no data on
EAF scrubbers was available.  A description of scrubber AOC's can be found in
the BOP manual issued in this series.  Problems known to often afflict scrubber
installations are listed below:
          Corroded or plugged sprays
          Corroded or plugged pipes
          Corroded pump impellers and pump failures
          Plugged or failed demister
          Vacuum filter failure
          Acid cleaning of scrubber components  spills
          Unbalanced water system.
                                        28

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                          5.0  TABULATED SUMMARY OF AOC

     Table 2 summarizes the AOC's described herein.  The identification  of an
AOC carries no implication whatsoever concerning liability for resulting air or
water pollution.  Liability for an AOC can only be determined by the enforce-
ment officer responsible for a given set of regulations (NSPS, SIP)  or permit
requirements (NPDES, special conditions, etc.).
                                        29

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                                 TABLE  2.    ELECTRIC  ARC  FURNACE  ABNORMAL  OPERATING CONDITIONS

Abnormal
Operating
Condition

Cause

Effect on
Process

Corrective
Action

Frequency

Duration

Environmental
Effects

Reference
                                                              PROCESS RELATED   START-UP
Burn-In
Abnormal  furnace
reactions
Poor scrap
quality

Improper oxygen
lance practice
Capture duct
misalignment
Running stoppers
Ladle breakout
                Some types of furn-
                ace lining require
                a burn-in
Scrap contamination,
furnace additions
Scrap less  uniform)
more contamination

Lance manually held
at wrong angle


Active bath condi-
tions require tilt-
ing to keep slag in
furnace

Stopper not seating
properly
Molten steel pene-
trates refractory,
then ladle wall
                    May be necessary
                    Burn-in under con-
                    trol device
5/year where appli-
cable
Unknown
Carbonaceous fume,
unqualified; slight
effect If control
device utilized
                                                   PROC SS RELATED   ABNORMAL OPERATING CONDITIONS
Requires reduction
of blowing rate
Requires additional
refining

Inefficient oxygen
use


Must tilt furnace
Loss of steel, dan-
ger to personnel
Loss of steel,
danger to personnel
11, 14
Reduce oxygen rate
or power Input; In-
crease furnace draft


None

Improve practice


T1lt furnace back
to upright position
Dump into emergency
ladle, better in-
spection/repair of
ladles
Dump in emergency
ladle, better In-
spection, repair
Once/month




Unknown

Unknown


Dally

Estimated at 1-2
percent of pours


One/year


2-5 minutes




As long as this
scrap is used.
Unknown


10 min.

10 minutes



10 minutes


No estimate of fugi-
tive emission rate
available; a portion
may be caught in a
canopy head
Increased emissions,
not quantified
Fugitive emission
Increase, as does
loading In gas
Increased fugitive
emissions
Fugitive emissions



Fugitive emissions


11




13

13


11

11



11



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TABLE  2.    (cont'd)
Abnormal
Operating
Condition
Wind conditions
Pit or charging
explosion
Relief damper
opening
Cause
Affects canopy hoods
Contact between
water and molten
steel or slag
Pressure relief,
high temperature,
Instrumentation
failure
Effect on
Process
None
Dangerous to person-
nel; can damage
equipment
Generally requires
slowdown of process
Corrective
Action
Baffling In shop
Control water
carefully; keep
scrap relatively dry
Reduce blowing rate
Frequency
Unknown
2-3 per year
Only case noted In
" 20 bauhouse years
was due to instru-
ment failure during
start-up
Duration
Unknown
10 m1n.
Until problem
repaired.
Environmental
Effects
Effect depends on
shop design; re-
duction In collec-
tion efficiency of
canopy heads
Stirs up shop dust,
leading to some
monitor emissions
Uncontrolled emis-
sions
Reference
10

11
                                                         CONTROL EQUIPMENT RELATED   START-UP
  Stack puff




  Baghouse

  Bag  failure




  Bag  blinding
Settled dust In
ductwork re-entrain-
ing
Abrasion, age,
sparking
Moisture condensa-
tion, oil condensa-
tion, extremely fine
partlculate
None
                     None
None
                    None                  Once/week to once/    1-5 minutes



         CONTROL EQUIPMENT RELATED  ABNORMAL OPERATING CONDITIONS
Choose bag type care-
fully, inspect  fre-
quently, prevent
spark carryover

Prevent condensation
choose proper bag
type
                                          Annual  failure  rate
                                          of 0.3-1.0 percent
                                          Seldom
Until bags
replaced
                                                              Until bags
                                                              replaced
                                                               Increased  particu-
                                                               late  emissions
Increased emissions
                     Reduced draft at
                     furnace allows
                     Increased  fugitive
                     emissions
                                          1.1,13
4,9,11,12
                     9..12

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    TABLE 2.   (cont'd)
Abnormal
Operating
Condition
Shaker or re-
verse air systen
Dust removal
system break-
down
Fan failure
Cause
Loss of reverse air
fan, mechanical
failure
Broken or misaligned
conveyors, plugged
hoppers, hopper
heater or vibrator
failure
High bearing temper-
ature, vibration,
loss of bearing oil,
motor failure
Effect on
Process
None
None
Operation at reduced
rate; probable shut-
down
Corrective
Action
Repair
Repair: requires
careful design and
good preventatlve
maintenance
Repair fan; Install
spare
Frequency
Unknown
Not quantified at EAF
shops; 1n other shops
once/week to once/
month
Less than once/year
Duration
Unknown
1-8 hours
Unknown
Environmental
Effects
Reduced draft due to
dirty bags; eventual
excessive pressure
drop and baghouse
shut-down
Can cause shut-down;
more likely In-
creased fugitive
emissions as dust
removed by alternate
techniques
Uncontrolled emis-
sions for remainder
of heat
Reference
11,12
11-
9,11,12
co
ro

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                                 6.0  REFERENCES


1.   McGannon, H. E., editor, The Making. Shaping, and Treating of Steel.
     Ninth Edition, 1971, United States Steel Corporation.

2.   Background Information for Standards of Performance:  Electric Arc
     Furnaces in the Steel Industry; Volume I:  Proposed Standards. Emissions
     Standards and Engineering Division, U.S. EPA, EPA-450/2-74-017a,  October
     1974.

3.   Flux, J. H., "The Control of Fume from Electric Arc Steelmaking," Iron and
     Steel International, June 1974, pp. 185-192.

4.   Kaercher, L. T., and J. D. Sensenbaugh, "Air Pollution Control for  an
     Electric Furnace Melt Shop," Iron and Steel Engineer, May  1974, pp. 47-51.

5.   Culhane, F. R. and C. M. Conley, "Air Pollution Control  -  Electric  Arc
     Melting Furnaces," Proc. Annual Ind. Air Pollution Contr.  Cont.,  1974,
     pp. 90-112.

6.   Whitehead, C., "Design and Operating Experience with Electrostatic
     Precipitators on Electric Arc Furnaces," in C. E. Feazel,  Ed.,
     "Proceedings:  Particulate Collection Problems Using ESP's in the
     Metallurgical Industry."  Denver, 1-3 June 1977; EPA-600/2-77-208,
     October, 1977.
7.   Federal Register.  Electric Arc Furnaces in the Steel Industry - Standards
     of Performance, 40 FR 43852, 23 September 1975.
8.   Marchand, D., "Dust and Gas Evolution in Arc Furnace Steelmaking and
     Possible Alternatives for Reducing Emissions with Suitable Collection
     and Cleaning Systems," Engineering Aspects of Pollution  Control in  the
     Metals  Industries, The Metals Society, London, 1975.
9.   Trip Report, Crucible, Inc., Midland, Pa., August 4, 1977.

10.  Flux, J. H., "Containment of Melting Shop Roof Emissions in Electric Arc
     Furnace Practice," Ironmaking and Steelmaking Quarterly. No.  3, 1974,
     pp. 121-123.
11.  Trip Report, Inland Steel Corporation, East Chicago, Indiana, April 19-
     20, 1977.
12.  Trip Report, Babcock & Mil cox, Beaver Falls, Pa., June 29, 1977.
13.  Trip Report, Jones and Laughlin Steel, Cleveland, Ohio,  August 2-3, 1977.

14.  Trip Report, Republic Steel Corporation, Gadsden, Alabama, July 6-7, 1977.
                                      33

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                                TECHNICAL REPORT DATA
                         (Please read Instructions on the reverse before completing)
 1. REPORT NO.
 EPA-600/2-78-118e
                           2.
                             3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE Pollution Effects of Abnormal Oper-
ations in Iron and Steel Making - Volume V.  Electric
Arc Furnace, Manual of Practice
                             5. REPORT DATE
                              June 1978
                             6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
D.W.VanOsdell, B.H.Carpenter, D.W.Coy, and
    R.Jablin
                                                      8. PERFORMING ORGANIZATION REPORT NO,
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Research Triangle Institute
P.O. Box 12194
Research Triangle Park, North Carolina 27709
                                                      10. PROGRAM ELEMENT NO.
                              1AB604
 12. SPONSORING AGENCY NAME AND ADDRESS
                             11. CONTRACT/GRANT NO.

                              68-02-2186


                             13. TYPE OF REPORT AND PERIOD COVERED
 EPA, Office of Research and Development
 Industrial Environmental Research Laboratory
 Research Triangle Park, NC 27711
             13. TYPE OF REPORT AND P
             Final; 10/76-1/78
                             14. SPONSORING AGENCY CODE
                               EPA/600/13
 is. SUPPLEMENTARY NOTES IERL-RTP project off leer is Kobert V. Hendriks, Mail Drop 62,
 919/541-2733.
 16. ABSTRACTfhe report is one in a six-volume series considering abnormal operating
 conditions (AOCs) in the primary section (sintering, blast furnace ironmaking, open
 hearth, electric furnace,  and basic oxygen steelmaking) of an integrated iron and
 steel plant.  Pollution standards,  generally based on controlling discharges during
 normal (steady-state) operation of a process and control system, are often exceeded
 during upsets in operation. Such periods of abnormal operation are becoming recog-
 nized as contributing to excess air emissions and water discharges.  In general, an
 AOC includes process and control equipment startup and shutdown, substantial var-
 iations in operating practice and process variables, and outages for  maintenance.
 The purpose of this volume, which covers  the electric arc process,  is to alert those
 who deal with environmental problems on a day-to-day basis to the potential pro-
 blems caused by AOCs, to assist in determining the extent of the problems in a
 specific plant,  and to help evaluate efforts  to reduce or eliminate the problems. The
 report enumerates as many AOCs as possible, with emphasis on those which have the
 most severe environmental impact. Descriptions include flow diagrams, material
 balances,  operating procedures,  and.conditions representing typical process config-
 urations.
17.
                             KEY WORDS AND DOCUMENT ANALYSIS
a.
                DESCRIPTORS
                 b.lDENTIFIERS/OPEN ENDED TERMS
                        c.  COS AT I Field/Group
 Pollution
 Iron and Steel Industry
 Electric Arc Furnaces
 Steel Making
 Abnormalities
 Failure
Starting
Shutdowns
Pollution Control
Stationary Sources
Abnormal Operations
13 B
11F
13A
13H
 3. DISTRIBUTION STATEMENT
 Unlimited
                                          19. SECURITY CLASS (ThisReport)
                                          Unclassified
                                          21. NO. OF PAGES
                                               42
                 20. SECURITY CLASS (Thispage)
                 Unclassified
                         22. PRICE
EPA Form 2220-1 (9-73)

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