EPA-600/2-76-054
March 1976 Environmental Protection Technology Series
CONTROL OF STEEL PLANT SCARFING EMISSIONS
USING WET ELECTROSTATIC PRECIPITATORS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application of
environmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to develop and
demonstrate instrumentation, equipment, and methodology to repair or prevent
environmental degradation from point and non-point sources of pollution. This
work provides the new or improved technology required for the control and
treatment of pollution sources to meet environmental quality standards.
EPA 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-600/2-76-054
March 1976
CONTROL OF STEEL PLANT
SCARFING EMISSIONS USING
WET ELECTROSTATIC PRECIPITATORS
by
John Varga, Or.
Battelle-Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
Contract No. 68-02-1323, Task 32
ROAP No. 21AQR-042
Program Element No. 1AB015
EPA Project Officer: Robert C. McCr1ll1s
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
Washington, DC 20460
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SUMMARY
The purpose of scarfing slabs, blooms, and billets is discussed as an
introduction to a discussion of the control of emissions from scarfing
machines. Some technical design information pertaining to the design
of wet electrostatic precipitators is presented, as is the limited amount
of information available on the characteristics of scarfing emissions.
Operating characteristics are given for several electrostatic precipi-
tators presently in operation.
This report was prepared in response to Item AM-5 of the Protocol of
the First Working Meeting of the US/USSR Task Force on Abatement
of Air Pollution from the Iron and Steel Industry.
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-------
TABLE OF CONTENTS
Page
I. INTRODUCTION 1
II. TRENDS IN THE USE OF SURFACE CONDITIONING IN THE
UNITED STATES IRON AND STEEL INDUSTRY 3
III. AIR-POLLUTION CONTROL FOR SURFACE CONDITIONING
OF STEEL . . 5,
IV. CHARACTERIZATION OF EMISSIONS 9
V. SCARFING MACHINE WET ELECTROSTATIC PRECIPITATOR
DESIGN CHARACTERISTICS 11
Electrostatic Precipitator Parts 11
Wet Electrostatic Precipitator 14
Wet-Dust-Collection Fundamentals 15
Horizontal-Flow Wet Electrostatic Precipitator 23
Range of Applications 24
Scarfer Wet Electrostatic Precipitator Design Data . 25
VI. REFERENCES 28
LIST OF FIGURES
Figure 1. Two types of rectifier circuits for an electrostatic
precipitator 12
Figure 2. Typical duct-type electrostatic precipitator 13
Figure 3. Typical pipe-type electrostatic precipitator .... 13
LIST OF TABLES
Table 1. Air-Pollution Control Systems on Surface-Conditioning
Operations 6
Table 2. Surface Conditioning Air-Pollution Control Systems in
the U. S. Iron and Steel Industry 7
v
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LIST OF TABLES
(Continued)
Page
Table 3. Scarfing Machine Wet Electrostatic Precipitator
Dust Loadings 9
Table 4. Nomenclature for Wet-Dust-Collection Fundamentals . 18
Table 5. Design Characteristics and Operating Conditions for
Scarfing Wet Electrostatic Precipitators 26
Table 6. Design Operating Conditions and Test Results for
Scarfing Wet Electrostatic Precipitators 27
VI
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I. INTRODUCTION
Scarfing is a process that is used to remove surface defects from
steel slabs, blooms, and billets before rolling into semifinished
products. A mixture of gaseous fuel and oxygen is used to burn away
the defects. The scarfing may be selective on individual defects or it
may be over the entire surface of the slab, bloom, or billet. The
operation is usually done after the slab, bloom, or billet has been
heated to the rolling temperature, but it may also be done on cold
steel.
There are about 122 rolling mills of various types in the iron and
steel industry of the United States, of which about 59 have scarfing
operations for the removal of surface defects. Scrubbers, cyclones,
baghouses, water flumes with water sprays, and wet and dry electro-
static precipitators are used to control emissions from about 47 of
the scarfing installations.
This Protocol Report discusses the application of wet electrostatic
precipitators for the control of emissions from scarfing operations;
it is based on available published information and additional informa-
tion supplied by iron and steel companies.
-------
II. TRENDS IN THE USE OF SURFACE CONDITIONING
IN THE UNITED STATES IRON AND STEEL INDUSTRY
Because of the specifications established by customers, many semi-
finished steel products must be free of surface defects. Surface
conditioning, the designation for the removal of surface defects, is
done by hand and machine chipping, by hand and machine grinding, and
by hand and automatic scarfing. Until the early 1930's, hand chipping
was the only method used for removing surface defects. Chipping
machines and grinding machines were developed to make surface
conditioning less laborious.
Scarfing is a surface-conditioning method that uses high-purity oxygen
to oxidize the surface of the steel and remove the defects. A fuel gas,
such as acetylene or natural gas, is used in combination with the oxy-
gen. The purpose of the fuel gas is to ensure that the steel is heated
to a sufficiently high temperature, about 870 C (1600 F), so that the
high-purity oxygen can react with the steel and remove the surface
defects.
In the United States iron and steel industry (excluding most mini-steel
mills), about 130 rolling mills of various kinds are used for rolling
slabs, blooms, and billets. (1) Automatic scarfing machines are
installed in line with the mills to condition the surfaces of slabs and
blooms before they enter the first stand of the mill. Billets are
usually surface conditioned in the cold state before they are reheated
for further rolling. However, some steel companies surface-condition
slabs and blooms after they have cooled to ambient temperatures.
There are 57 mills, located at various steel plants, with automatic
scarfing machines, one plant using scarfing for surface conditioning
cold billets, and four plants that use grinding of cold slabs, blooms,
and billets as a means of surface conditioning. i^"-") Scarfing is used
more than any other method for surface conditioning of steel. In 1935
about 1 percent of the steel produced in the United States was condi-
tioned by scarfing. This increased to about 41 percent in 1968.
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in. AIR-POLLUTION CONTROL FOR SURFACE
CONDITIONING OF STEEL
The emissions generated during scarfing are primarily iron oxide
fumes. There may be a small amount of carbon dioxide and/or car-
bon monoxide depending on the carbon content of the steel. The higher
the carbon content of the steel, the higher will be the fume emission
rate.*35)
Wet and dry electrostatic precipitators, scrubbers, cyclones, bag-
houses, and water flumes with sprays are used to control emissions
from scarfing operations. The distribution of the different types of
air-pollution control systems in integrated and nonintegrated steel
plants is given in Table 1. A detailed list of the control systems is
given in Table 2. (1-32)
The distribution of surface-conditioning installations in Table 1
accounts for 44 installations. There are three additional installations
under construction for which detailed information is not as yet avail-
able. Of the 47 mills with automatic scarfing machines, 43 have some
type of air-pollution control facilities. The remaining four installa-
tions use grinders for surface conditioning of the slabs, blooms, and
billets.
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TABLE 1. AIR-POLLUTION CONTROL SYSTEMS ON SURFACE-CONDITIONING OPERATIONS
Type of Mill
Integrated Plants
Slabbing
Blooming
Billet
Rail
Dry
ESP
2
1
3
1
Wet
ESP
5
4
2
Scrubber Cyclone Baghouse
6 l^a)
3 1 l
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TABLE 2. SURFACE CONDITIONING AIR-POLLUTION CONTROL SYSTEMS IN THE U.S. IRON AND STEEL INDUSTRY
Company & Location Type of Mill
Atlantic Steel Co.
Atlanta, Ga.
Armco Steel Corp.
Houston, Texas
Kansas City, Mo.
Middletown, Ohio
Babcock & Wilcox Co.
Koppel, Pa.
Bethlehem Steel Corp.
Burns Harbor, Ind.
Johnstown, Pa.
Los Angeles, Cal.
Sparrows Point, Md.
Copperweld Corp.
Warren, Ohio
Carpenter Technology Corp.
Bridgeport, Conn.
CF & I Steel Corp.
Pueblo, Colo.
Crucible Inc.
Midland, Pa.
Ford kotor Co.
Dearborn, Mich.
Inland Steel Co.
East Chicago, Ind.
J & L Steel Corp.
Aliquippa, Pa.
Cleveland, Ohio
Pittsburgh, Pa.
Jessop Steel Co.
Owensboro, Ky.
Kaiser Steel Corp.
Fontana, Cal.
Lukens Steel Co.
Coatesville, Pa.
Phoenix Steel Corp.
Phoenixville, Pa.
Blooming
Blooming
Slabbing
Blooming
Slabbing
Blooming
Slabbing
Blooming
Billet
Blooming
Slabbing
Blooming
Blooming
Blooming
Blooming
Blooming
Slabbing
Blooming
Blooming
Slabbing
Blooming
Slabbing
Blooming
Blooming
Slabbing
Plate
(e)
Annual Capacity
tonne
435,456
589,680
1,360,000
752,976
2,358,720
453,600
3,084,480
2,195,424
884,520
612,360
2,721,600
2,639,952
480,816
181,440
563,371
1,020,600
3,628,800
1,134,000
1,632,960
2,903,040
1,918,728
2,449,440
1,647,475
145,152
2,830,464
521,640
net tons
480,000
650,000
1,500,000
830,000
2,600,000
500,000
3,400,000
2,420,000
975,000
675,000
3,000,000
2,910,000
530,000
200,000
621,000
1,125,000
4,000,000
1,250,000
1,800,000
3,200,000
2,115,000
2,700,000
1,816,000
160,000
3,120,000
575,000
Type of Control
Equipment
Baghouse
High-energy scrubber
High-energy scrubber
High-energy scrubber
High-energy scrubber
High-energy scrubber
High-energy scrubber
High-energy scrubber
Wet ESP
Baghouse
Wet ESP
Wet ESP
Wet ESP^c)
Baghouse
(c)
(c)
Water flume ft sprays
Water flume & sprays
Water flume & sprays
Water flume & sprays
Wet ESP
Wet ESP
Cyclones
Baghouse
Wet ESP
Venturi scrubber
Gas
Flow
Nm3/min ACFM References
(b)
3,996
2,834
1,304
2,834
2,550
3,117
2,834
737
(b)
4,251
708
1,417
2,692
2,550
2,267
2,834
3,542
2,834
2,834
2,324
141,000
100,000
46,000
100,000
90,000
110,000
100,000
26,000
150,000
25,000
50,000
95,000
90,000
80,000
100,000
125,000
100,000
100,000
82 , 000
2
3
3
3
3
4
5
6,7
8,9
10
10
10
11
12
12
12
13
14
14
14
15
15,16
15
17
18
19
20
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TABLE 2. (Continued)
Company & Location Type of Mill -
Republic Steel Corp.
Buffalo, N.Y.
Cleveland, Ohio
Youngstown, Ohio
Roblin Steel Co.
Dunkirk, N.Y.
Timken Co.
Canton, Ohio
United States Steel Corp.
Braddock, Pa.
Duquesne, Pa.
Fairless Hills, Pa.
Gary, Ind.
Homestead, Pa.
W-P Steel Corp.
Steubenville, Ohio
Y.S. & T Co.
East Chicago, Ind.
Campbell, Ohio
Blooming
Blooming
Slabbing
Billet
Blooming
(f)
(g)
Slabbing
Slabbing
Blooming
Slabbing
Slabbing
Billet
Rail
Bar
Bar
Slabbing
Slabbing
Slabbing
Blooming
Annual Capacity
tonne net tons
781,099 861,000
925,344 1,020,000
2,574,634 2,838,000
635,040 700,000
1,584,878 1,747,000
535,248 590,000
2,268,000 2,500,000
1,496,880 1,650,000
1,542,240 1,700,000
2,630,880 2,900,000
2,558,304 2,820,000
1,088,640 1,200,000
618,710 682,000
453,600 500,000
186,883 206,000
2,792,362 3,078,000
1,385,294 1,527,000
2,363,348 2,604,000
1,545,869 1,704,000
Type of Control
Equipment
Wet ESP
Wet ESP
Wet ESP
Wet ESP
Baghouse W)
Baghouse(d)
Baghouse
Scrubber
Wet ESP
Esp(g)
Esp(g)
ESP
ESP
ESP
ESP
ESP
Multi-cyclones^
Low-pressure scrubber
High-energy scrubber
High-energy scrubber
Gas
Flow
Nm3/min ACFM^
1,700
2,343
2,834
1,275
1,417
5,951
2,834
2,343
3,259
2,692
1,757
879
1,757
1,757
232
2,834
2,834
60,000
75,000
100,000
45,000
50,000
210,000
100,000
75,000
115,000
95,000
62,000
31,000
62,000
62,000
8,200
100,000
100,000
References
21
22
22
22
23
24
25,26
27
27
27,28
27
29
29
29
29
29
30
31
/
32
32
(a) ACFM - actual cubic feet per minute.
(b) Scarfing emissions are exhausted to a common baghouse also controlling electric-arc
melting-furnace emissions.
(c) Under construction.
(d) Conditioning of slabs, blooms, or billets is done by grinding.
(e) Ingot scarfing.
(f) Selective grinding of billets.
(g) Selective scarfing of cold billets at several scarfing stations.
(h) To be replaced by wet electrostatic precipitators .
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IV. CHARACTERIZATION OF EMISSIONS
The fume generated during a scarfing operation is predominantly iron
oxide. No information is available pertaining to the size distribution
of the emissions or specific chemical composition. It has been re-
ported that the loss in yield for scarfing billets varies from 3 to
6 percent depending on the types of steel scarfed. (36) However, most
of this loss is in the form of metal splatter rather than fume. Several
factors that influence the amount of metal removed include: (1) speed
of the semifinished product through the machine, (2) oxygen pressure
at the scarfing head, (3) temperature of the steel, and (4) the chemi-
cal composition of the steel. (35, 37-40) iniet and outlet dust loadings
for several wet electrostatic precipitator installations are given in
Table3.<10>22)
TABLE 3. SCARFING MACHINE WET ELECTROSTATIC PRECIPITATOR DUST LOADINGS
Type of
Mill
Billet
Billet
Blooming
Blooming
Slabbing
Slabbing
Gas
Nm3/min
643
1,032
740
1,700
2,018
2,891
Flow
ACFM
22,
36,
26,
60,
71,
102,
700
400
100
000
200
000
Inlet
grams/Nm3
2.0-48.0
1.329-2.528
5206
0.093-0.101
0.027-0.389
0.400-2.002
Loading
grains/SCFD
0.50-3.
0.332-0.
1.3
0.023-0.
0.007-0.
0.100-0.
00
631
025
097
500
Outlet
grams/Nm3
0.
0.
0.
0.
0.
0.
028-0
009-0
015-0
003-0
017-0
026-0
.029
.057
.047
.004
.026
.056
Loading
grains/SCFD
0.0070-0.
0.0023-0.
0.0038-0.
0.0008-0.
0.0042-0.
0.0065-0.
0073
0143
0117
0009
0064
0139
Nm /min - normal cubic meters per minute.
ACFM - actual cubic feet per minute.
SCFD - standard (normal) cubic feet, dry.
grain, - 1/7000 pound.
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V. SCARFING MACHINE WET ELECTROSTATIC
PRECIPITATOR DESIGN CHARACTERISTICS
This section is concerned with design fundamentals for tube or pipe-
type wet electrostatic precipitators and duct-type (i.e. , those that
use plates for collection) wet electrostatic precipitators. Dry electro-
static precipitators are not considered. Dry electrostatic precipita-
tors have had severe corrosion problems and the trend is toward the
use of wet electrostatic precipitators. Seven dry electrostatic pre-
cipitators are listed in operation in Table 1. Two of these installa-
tions are scheduled for replacement by wet electrostatic precipita-
tors. (27) This will bring the number of wet electrostatic precipitators
in operation to 14.
ELECTROSTATIC PRECIPITATOR PARTS*
The three basic parts of any precipitator installation are:
(1) Power supply
(2) Collection area
(3) Dust-removal area.
The power supply generally consists of a single-phase, high-voltage
transformer, appropriate control equipment, and a bridge rectifier
circuit. The rectifier circuit can be either a full-wave or double half-
wave circuit, as shown in Figure 1.
Rectifier design has progressed from the mechanical rectifier to the
high-voltage Kenotron vacuum tube, selenium, or silicon rectifiers.
Normal transformer ratings are between 15 and 25-kva, 440-volt
primary and 50 to 75-kv secondary. To limit short-circuit current
surges, the transformer primary circuit usually contains a ballast
4 Reprinted from Iron and Steel Engineer. Electrostatic Precipitator Primer. J. Katz. by permission
of the Association of Iron and Steel Engineers, pp. 21-40, May 1964.
11
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HIGH VOLT.
TRANS.
BRIDGE
RECTIFIER
PRECIPITATOR
(-) PROPER
LOW VOLTAGE
INPUT
FULL-WAVE CIRCUIT SCHEMATIC
HIGH VOLT.
TRANS.
BRIDGE
RECTIFIER
PRECIPITATOR
-) PROPER
LOW VOLTAGE
INPUT
GRD. .—i
RETURN -±-
DOUBLE HALF-WAVE CIRCUIT SCHEMATIC
Figure 1. Two types of rectifier circuits for an
electrostatic precipitator
resistance or a reactor. Manual or automatic control is used to
regulate electrical conditions in the precipitator dust-collection area.
The collection area consists of either ducts or pipes with high-voltage
discharge electrodes uniformly spaced and of uniform length, as
illustrated in Figures 2 and 3. Collecting electrodes (the metal sur-
faces that collect the particles) are at ground potential and are con-
nected directly to the frame of the precipitator. The collecting-
surface design varies with the manufacturing company and process.
The collecting surface of ducts may consist of perforated or solid
metal plates up to 1.4 x 6. 0 meters (4. 5 x 20 feet). Normally a
precipitator has three to four duct sections in series. The duct width
may be 200 mm (8 inches), although 250 mm (10 inches) ducts are
sometimes employed in cleaning gases that contain large quantities of
dust. There can be five or six discharge electrodes equally spaced
12
-------
• —-> -JT jf- — —•*- Clean gas flow
The mam discharge /\r / /
electrode frame is s^\ /S
suspended by post //f //\
precipitator roof.
This maintains
electrical clearance
from grounded
collecting plates.
Usually stiffener »-
baffles are present
on ends to help '
/
minimize erosion '
/
'
/
/ /
(
X
>
r/
/
?
f'
/
s .
y
/
/
/ /
*
\
/
.
/
v
/
/
/
f
/
;
/
/ x //\*
'/y/y
/\ / /\/
Y
j
/
/
V
^'
A\
S )
A/
/ &
/ L
I °
A
a
by dust. / / O/'Q / 9 0
Dirty gas flow -^ -^ ^ '
,V
_ L
~
* Collecting plates are
/tied into the top shell
of the precipitator.
Spacer plates at the
bottom keep plates
properly aligned.
Plates can be rapped
separately or in
sections by a bar
connecting the ends
or bottoms.
Figure 2. Typical duct-type electrostatic precipitator
Clean Gas Flow
* \ Negative output from
_ ' power suoplv to
-r L j i ^
tied into the shell of \ /
which is at ground ~
potential. Header
provides support to /
pipes and acts as a
shield between
dirty and clean gas.
The number of pipes »•
per electrical set
may vary from 50 to
100. Pipe diameters
vary between 300
and 380 mm (12 and
15 inches). Pipe
length averages 3.6
./IC.
/
x^
s*-
t
r-
T>
1
t
1
-l>
I1
1
1
x
/ 1 | insulated disc arge
X l S electrode frame.
r ~y i 1C IT) /
-\-7 4 1 ^ — ' — /
^ ISC
±y
. —
i
B*
, —
t
D
OP A
^1 '
~K
1
i!
C^T
n
i
i
i
i
i
:
^
/
r.
/
For wet precipitators,
weir rings on top of
each pipe provide
uniform water flow
over the insides of the
pipes. The header
serves as a base for
the water reservoir.
* Weights or other methods
hold the discharge wires
plumb. The bottom
frame (not shown) keeps
wires properly spaced.
to 4.6 meters (12 ' ' 1 _ J _ J _ Dirty gas flow
to 15 feet).
Figure 3. Typical pipe-type electrostatic precipitator
13
-------
in each 1.4-meter (4. 5-foot) duct section. These discharge electrodes
receive the high-voltage rectifier output and are suspended in parallel
from a framework that is insulated from ground by ceramic insulators.
Pipe-type collecting units are normally used for cleaning blast-furnace
gas, removing tar from coke-oven gas, cleaning scarfing-machine
emissions, and in recent years have been considered for cleaning
reclamation (sinter) plant emissions. Pipe units differ from duct units
primarily in having only one discharge electrode for each collecting
electrode; duct units have several discharge electrodes in each duct.
(See Figures 2 and 3. )
Both pipe-type and duct-type wet precipitators normally use water
flowing over the collecting surfaces to flush the emissions from the
collecting surfaces. The practice for wet electrostatic precipitators
on scarfing operations is to flush the collecting surfaces periodically
after a given number of slabs, blooms, or billets have been scarfed.
The flushing period is influenced by the kind of semifinished product,
the type of steel, and the amount of steel removed during the scarfing
operation.
WET ELECTROSTATIC PRECIPITATOR
The use of wet electrostatic precipitators for control of emissions from
industrial sources was generally restricted to rather specialized appli-
cations such as on acid mist, coke-oven off-gas, blast furnaces, and
detarring applications. The method of cleaning was in most cases
intermittent and of the wetted-wall type.
As a result of much more stringent local, state, and Federal emission
regulations, condensable materials were added to the total particulate
loading. The removal of organic condensables, which are very difficult
to wet and which form small droplets in the 0. 1 to 2-micron range,
requires scrubber pressure drops in the range from 1000 to ISOOkg/m^
(40 to 60 inches of water gage). Because the wet electrostatic pre-
cipitator is always operated at saturation temperature (100 percent
relative humidity), it will remove organic materials with a condensa-
tion temperature higher than or equal to the gas saturation temperature.
It will also remove solid dust particles in the submicron range and
gaseous contaminants soluble in the spraying liquor. Emissions are
removed with very low energy consumption and a pressure drop
usually less than 13 kg/m^ (0. 5 inches of water gage). The electric
power input through the high-voltage power supplies is quite low, from
14 to 23 kw/m3/min (0. 5 to 0. 8 kw/1, 000 actual ft3/min).
14
-------
The recent development of a continuously sprayed, parallel plate,
frame electrode and horizontal flow design has provided industry with
a realistic alternative to high-energy scrubbers. The theory of opera-
tion, description of the design, and the power consumption are dis-
cussed in the following sections.
Wet-Dust-Collection Fundamentals(55>
The corona generation and the charging and discharging processes in
the wet electrostatic precipitator are, in general terms, similar to what
takes place in a conventional dry electrostatic precipitator except for
some important differences.
Because the gas in the wet precipitator is always saturated with water
vapor, the current and voltage relationship is somewhat different
from that in the dry precipitator. With increasing amounts of water
vapor, the spark-over voltage increases (i. e. , the voltage at which the
field breaks down), but the corona current at a given voltage is lower.
When solid particles and droplets enter the electrostatic field, they will
cause a local distortion of the electrostatic field between the electrode
and the collecting plate. Some of the electric-field lines intersect the
particles, and ions generated by the corona discharge will tend to travel
along lines of maximum voltage gradient or along the field lines; there-
fore, some of the ions will collide with the particles and the charge
gradually builds up on the particles.
This process continues until the charge on the particles is so high that
it diverts the electric-field lines away from the charged particles, pre-
venting new ions from colliding with the dust particles. When this state
has been reached, the particles are said to be saturated with charge.
Theory shows that the saturation charge value and charging time are
dependent upon electric-field strength, size of the particle, the dielec-
tric constant of the particle, and the relative position of the particle in
the field. This charging process is said to be field dependent and is the
dominant process down to a particle size of 0. 2 j-im. For smaller
particles, the so-called diffusion charging process is the dominant
mechanism; this is governed by the random thermal motion of the ions
and is not limited to a saturation charge.
As soon as the charging process of the particle starts, the resulting
electrostatic force will pull the particle toward the collecting plate.
This force, together with the gravitational and the-drag forces, and the
gas-flow distribution in the field determine the particle trajectory and
its point of collection.
15
-------
In a dry electrostatic precipitator, the dust buildup on the collecting
plate limits the maximum voltage at which the precipitator can operate.
For dust layers with high resistivity (greater than 2 x ICr" ohm-cm)
the voltage drop can be from 10 to 20 kv. This condition lowers the field
strength in the space between the electrode and the dust deposit surface,
and results in a lower saturation charge, which again gives a lower
electrostatic force. If, on the other hand, the resistivity of the dust
layer is lower than 10? ohm-cm, the electrostatic force holding the dust
particle on the plates is low, and reentrainment can become a serious
problem during the electrode- and plate-cleaning (rapping) cycle and also
during the steady operation, having the overall effect of lowering the
precipitator collection efficiency.
For a continuously sprayed wet electrostatic precipitator, the pre-
viously discussed problems are nonexistent. The spray liquid drops
form a film on the collecting plates which continuously washes off the
dust that is being collected. The resistivity of the liquid film is the
governing factor in the dust-discharging process and not the resistivity
of the dust layer itself. Reentrainment problems are also nonexistent,
because the collected particles are instantaneously and continuously re-
moved from the point of collection and are washed down as a light
slurry. The exit loading is, therefore, much more stable and does not
have the characteristic sharp increase that the dry electrostatic pre-
cipitator has during the collection-plate- and electrode-rapping cycles.
Therefore, for a wet electrostatic precipitator, the operation is not
influenced by the resistivity of the dust layer. The major parameters
that must be considered are the particles' dielectric constant and size.
To better understand the effect of low dielectric constants on
horizontal migration distance of the particle, a mathematical model of
the particle collection mechanism was developed. The analysis was
based upon a field-charging process and a particle or droplet which had
to traverse the whole net field spacing (one half of the plate-to-plate
spacing). Particles of different sizes with dielectric constants of 2,
10, and 78 were investigated.
The unit consisted of parallel collecting plates with a separation of 2r.
The velocity profile between the plates was assumed to be flat (plug flow)
and turbulent drag forces were neglected. Centered between two plates
was an electrode frame, with electrode spacing assumed sufficiently
close to provide an approximately uniform electrostatic field near the
plate surface. The field strength was approximately 70 percent of the
field that was to be produced by a solid discharge-plate electrode, or
16
-------
E = -0. 70 dv/dr. (1)
The nomenclature for the equations is given in Table 4.
The current density under no-load condition will be
J = i/Ac. (2)
The ionic space charge can be determined from the current density -
electric field equation:
J = N0ejUjE (E = mean electrostatic field strength). (3)
The saturation charge for a nonconductive particle is
e 2
qs= 12— 7T£0adE. (4)
The relative dielectric constant, £, for a conducting particle approaches
infinity and is equal to one for a perfect insulator.
The expression for the charge as a function of time is
(5)
where r is a charging time constant or
r = 4e0/N0ejU (6)
The particle-size range examined is larger than 0.2 jum, so the diffu-
sion charge can be omitted.
If we start with a particle entering the field halfway between two plates
and without any charge, the force balance is divided into three different
components:
x - axis, the direction of the electrostatic field
(transverse to gas flow)
y - axis, the direction of the gravitation force
(vertically down)
z - axis, the direction of the gas flow
(horizontal and axial).
17
-------
TABLE 4. NOMENCLATURE FOR WET-DUST-COLLECTION
FUNDAMEN TALS
A = 67Ta7)/m = constant
Ac = Collection area
aj = Particle diameter
B = qsE/m = constant
ci = Particle inlet loading
co = Particle outlet loading
E = Electrostatic field strength
e = Electric charge
F = Force
g = Gravitational constant
i = Current
J = Current density
In = Natural logarithm
m = Particle mass
N0 = Number density of free ions
V = Gas flow rate
q = Charge
qs = Saturation charge
r = Net field spacing
sx = Transverse distance
sz = Horizontal distance
T = Migration time for collection
t = Time
v = Voltage
w = Velocity
Wgas = Gas average velocity
wx = Transverse particle velocity
wz = Horizontal particle velocity
x = Transverse horizontal distance
y = Vertical distance
z = Horizontal axial distance
e = Dielectric constant
€0 = Permittivity of free space
9 = Viscosity of gas
r\ - Collection efficiency
/Ji = Carrier mobility of the gas
TT = 3.1416
T = Charging time constant
co = Migration velocity parameter
18
-------
The force balance is then as follows:
ZFX = Fqe - Fx - Fix = 0 (7)
ZFy = Fg - Frjy - Fiy = 0 (8)
SFZ = F^ - Fiz = 0 . (9)
The electrostatic force can be expressed as
(10)
Substituting Equations (1), (4), and (5) in Equation (10) gives
£ad-eT- • °'49>
t+
which shows the influence of the dielectric constant, the particle size,
and the field strength on the electrostatic force.
The gravitational force is
Fg = mg . (12)
The viscous force, assuming Stoke 's Law applies (laminar flow), is
F^ = 67iad0w , (13)
and the inertia force can be expressed as
Fi = m dw/dt . (14)
If we assume that a spherical particle with a radius a is moving in this
field, it will be charged to carry an amount of g (coul) charges, and the
force balance in the transverse direction, after substituting Equations
(10), (13), and (14) in Equation (7), becomes:
qE = 67Tad7)wx - m dwx/dt = 0 . (15)
Substituting Equation (5) into Equation (15) gives
19
-------
£ dwx
qs—E -67Tad0wx = m — ; (16)
let
A = 6-nai^e/mand B = qgE/m . (17)
Substituting this in Equation (16) and integrating gives
f e"At
The term \ dt cannot be integrated but can be approximated using
^/ t~r •
a series solution:
oo
Then, by using this expression in Equation (18) and integrating it once
more with the following initial conditions
t = 0, wx = wxo = 0 and sx = sxo = 0 ,
the travel distance sx becomes
sx =
oo
• Fin — + Y [(A (t+T)]n - (AT)n)/n-njl - r In — .
L T / ; J T
The migration distance is from 0 to 150 mm (0 to 6 inches), and the
migration time, T, needed for the particle to be collected can then be
found for sx = 150 mm (6 inches) by a trial-and-error solution of
Equation (19).
20
-------
In order to obtain the horizontal distance needed for the particles to be
collected, the force balance in the z direction must be considered, i. e. ,
Equation (8). This expression becomes
6-na.^O (Wtf-c, - w7) = m dw7/dt , (20)
gat> * &
where (wgas ~ wz) is the relative velocity between the particle and the
gas. Integrating Equation (20), using the constants given by Equa-
tion (17) gives
+ wzoe~At ' (21)
where w is the initial particle velocity along the z-axis. The hori-
zontal travel distance becomes, then,
= J wzdt = wgas [t + 1 e-At - 1 ] - I
sz=\ wzdt = weas |t + i- e-~L-l | -£WZO e-At-l . (22)
Then, by using the travel time calculated from Equation (17), the hori-
zontal traveling distance can be calculated as a function of particle
(droplet) size and dielectric constant. With two 5-jUm particles or con-
densed droplets, one with a dielectric constant of 2 (e. g. , a condensed
hydrocarbon droplet) and one with a dielectric constant of 78 (e. g. ,
pure water droplet), migration across a field spacing of 150 mm
(6 inches) with an applied voltage of 50 kv and a gas velocity of
0. 9 m/sec (3 fps) will take a horizontal distance of 2. 2 m (7. 2 ft)
and 1.2 m (3.9 ft), respectively. Therefore, the low-dielectric particle
takes almost twice the horizontal distance before being collected. This
analysis points to the fact that condensable hydrocarbons (tars) and
other materials with a low dielectric constant will be much more dif-
ficult to collect than conductive particles, and this has been confirmed
by measurements.
When considering the removal of condensable hydrocarbons (tar mist),
it should be remembered that the dielectric constants for petroleum
distillates are quite low (i.e., around 2). For example, hexane (CfcHj^)
has a dielectric constant of 2 and a boiling point of 69 C (156 F), toluene
(CyHg) has a dielectric constant of 2. 15 and a boiling point of 110 C
(230 F), and naphthalene (CigHg) has a dielectric constant of 2. 54 and
a boiling point of 218 C (424 F). Other organic liquids like phenol form-
aldehyde resin have a dielectric constant of 6.6. Pure water has a
dielectric constant of 78.
21
-------
The removal efficiency of the wet electrostatic precipitator on a given
gas and dust stream is a function of six basic parameters:
Collection Area
Operating Voltage
Discharge Current
Liquid-to-Gas Ratio
Treatment Time
Local Average Velocity.
The performance is often stated by the so-called migration velocity.
The higher the migration velocity is, the better the particulate removal
efficiency or the smaller the wet electrostatic precipitator in terms of
collection area needed to treat the gas flow. The relationship between
migration Velocity and wet electrostatic precipitator performance is
given below.
u = -V/A 0. 508 In (co/Ci) . (23)
The efficiency of the unit is given by
T)= (l-c0/Ci) 100 , (24)
and when substituting Equation (23),
T,= (l-e(-Aw/0.508Q), 100 , (25)
which is another expression for the |Duetsch-Anderson Equation for
precipitator efficiency:
~ \~V~~)
T) = 1 — e
The migration velocity w is a performance parameter that does not in
reality relate directly to the speed at which the particles migrate to the
collecting plates. It is a "catch-all" which also includes all operating
parameters not included in Equation (23).
22
-------
HORIZONTAL-FLOW WET ELECTROSTATIC
PRECIPITATOR
One of the wet electrostatic precipitators can be characterized as a con-
tinuously sprayed, horizontal-flow, parallel-plate, and solid-discharge
electrode type. In terms of gaseous absorption, it can be characterized
as a combination cocurrent and a cross-flow scrubber.
In the application of a wet electrostatic precipitator, it is very important
that the gas to be treated is saturated with water vapor to prevent the
water inside the wet electrostatic precipitator from evaporating, which
causes loss of washing water and dry zones on the internal members.
The saturation of the gas can be done in a spray tower or scrubber up-
stream of the wet electrostatic precipitator, or it can be done in the
inlet section of the wet electrostatic precipitator, or both.
In addition, it is also necessary to obtain a uniform velocity profile
across the wet electrostatic precipitator, and the diffusion of the flow
from the inlet duct velocity down to the wet electrostatic precipitator
face velocity has to be performed in the inlet section. Furthermore,
by spraying cocurrent into the inlet section, some of the coarser parti-
cles will be removed and the gas-absorption process will be started.
To accomplish this, sections of baffles and sprays are located in the
inlet cone of the wet electrostatic precipitator.
After passing through the sections of transverse baffles, the dirty gas
stream then enters into the first electrostatic field. Water sprays
located above the electrostatic-field sections introduce the proper
amount of water droplets to the gas stream for washing of internal sur-
faces. The particulates and the water droplets in the electrostatic field
pick up a charge and migrate to the collecting plates. The collected
water droplets form a continuous down ward-flowing film over all the
collecting plates and keep them clean. The water film and the collected
particulates flow down the collecting plates into the troughs below,
which are sloped to a drain.
The transverse-baffle gas-distribution system combined with the ex-
tended electrode, located upstream and downstream of each field, insures
complete gas-flow uniformity from passage to passage, and collects
particulates and droplets by impingement, and by electrostatic forces.
Also, the extended discharge electrode system improves the collection
efficiency by increasing effective collection area. At the entry of a
field, particles not captured by the transverse baffles are given an
23
-------
advance charge by the forward-extended electrode before they come into
proximity of the collecting plates. Thus charged, the particles start
immediately to migrate toward the leading edge of the plates. It has
been found that the downstream side of the baffles at the exit of a field
collects a considerable amount of material. The very small charged
particles escaping the parallel-plate field are pulled into the wake of the
baffles by the slight vacuum resulting from the turbulent dissipation of
energy. Because the particles have an electrostatic charge, some of them
will be collected on the back side of the baffles.
All baffles systems are arranged so that a walkway runs across the front
and the back of each of the electrostatic fields. The discharge electrode
frames are mounted on collar-type, high-voltage support insulators.
Insulator compartments are heated and pressurized to prevent moisture
and particulate leakage into the insulator compartment.
In any particulate and/or gaseous removal process where a liquid is
used, it is important to remove the carryover liquid drops and mists
before reaching the outlet of the equipment. It has been found that doing
this electrostatically is highly efficient. Hence, the last section is
operated dry, thereby establishing an electrostatic barrier that the
liquid droplets cannot penetrate. The mist collects on the front side of
the baffles, and the downstream side is dry. However, some small
dust particles can penetrate and these will collect on the downstream
baffles. Therefore, this surface is washed intermittently to prevent
buildup of particulates.
RANGE OF APPLICATIONS
During the past 2 years, many new applications have been piloted and
units have been sold and installed following successful pilot-plant work.
The wet electrostatic precipitator can be used for applications on gas
streams containing relatively light dust loading of submicron particles
and/or condensed organic materials forming a submicron fume.
Ordinarily these applications would require very-high-pressure-drop
scrubbers. The energy consumption and operating costs are less than
what would be needed to operate scrubbers. The water-treatment
requirements for the wet electrostatic precipitator are about the same as
those for scrubbers.
In some applications, where the dust resistivity is either very high or
very low, the wet electrostatic precipitator can also be applied success-
fully in competition with dry electrostatic precipitators.
24
-------
Scarfer Wet Electrostatic Precipitator Design Data
There is no information in the published literature pertaining to the
design and operating data of scarfing machine wet electrostatic pre-
cipitators. Table 5 presents data supplied by some steel companies
for wet electrostatic precipitators installed at their steel plants in the
United States. (22> 27>
There is no published information pertaining to the size distribution of
scarfer emissions or their chemical compositions. This type of infor-
mation is not available from any steel companies in the United States.
Table 6 presents data on the operating design conditions and test
results for three scarfing wet electrostatic precipitators. '9) These
data were obtained by the steel plants to verify the performance of the
precipitators.
No major operating or maintenance problems were reported during
start-up and operation of the wet electrostatic precipitators installed
on the 762 533-mm (30 21-inch) billet mill and the 1016-mm (40-inch)
blooming mill. About three years after the wet electrostatic precipi-
tator was installed on the 1143 x 2286-mm (45 x 90 inch) slabbing mill,
a reduction in exhaust capacity resulted in a reduction in the ability of
the hood to capture fume at the scarfer. It was determined that the
mist eliminator of the separator was becoming clogged and dirt buildup
was taking place on the precipitator tubes. Clogging of the mist
eliminator was resolved by removing approximately two thirds of the
flex rings in the mist eliminator bed and washing down the remaining
rings and bed area. The buildup of dirt on the precipitator tubes was
eliminated by more frequent flushing of the modules. Originally a
module was flushed after every ten scarfs. This was reduced to
flushing after every three scarfs. (9)
Operating and maintenance costs in 1974, for the 1016-mm (40 inch)
blooming mill and 1143 x 2286-mm (45 x 90 inch) slabbing mill, were
reported to be $0. 009 per tonne ($0. 01 per net ton) or less. This cost
did not include the cost to operate and maintain the exhaust fans which
were a part of the original equipment before installation of the wet
electrostatic precipitators. (9)
25
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TABLE 5. DESIGN CHARACTERISTICS AND OPERATING CONDITIONS FOR SCARFING WET ELECTROSTATIC PRECIPITATORS
NO
Item
Gas volume
Gas temperature
Pressure
Inlet dust loading
Outlet dust loading
Number of precipitators
Modules per precipitator
Fields per chamber
Discharge electrodes
per module
per precipitator
Collecting surfaces
per module
per precipitator
Collecting surface
type
material
diameter
length
Reactor rating
Transformer -rectifier
type
KVA
MA
dielectric
Power source
Volts
Hz
Phases
Insulator compartment
ventilation
18 -inch Billet Mill
1, 275 m3/min 45, 000 ACFM
4-66 C 40-150 F
<25 mm < 1 inch
4. 6 grams/m3 2. 0 grains/SCF
0. 02 grams/m3 0. 01 grains/SCF
1
2
1
96
192
96
192
Tube
Stainless steel
25.4 cm 10 inches
4. 6 m 15 feet
Silicon
460
60
3
Blooming Mill Slabbing Mill
2, 125 m3/min 75, 000 ACFM 2, 834 m3/min 100, 000 ACFM
4-66 C 40 -150 F 52 C 125 F
-380 mm -15 inches 12. 7 mm 6 inches
4. 6 grams/m3 2. 0 grains/SCF
0. 02 grams/m3 0. 01 grains/SCF 0. 02 grams/m3 0. 01 grains/SCF
1 1
3 4
1
96 84
288 336
96 84
288 336
Tube Tube
Stainless steel Stainless steel
25.4 cm 10 inches 25.4 cm 10 inches
4. 6 m 15 feet 4. 6 m 15 feet
42 KVA
Silicon
60 60
400 ' 1,200
Askarel
460
60
3
Forced draft, electrically heated
ACFM - Actual cubic feet per minute.
Grain = 1/7000 pound.
SCF - Standard cubic foot.
-------
TABLE 6. DESIGN OPERATING CONDITIONS AND TEST RESULTS FOR SCARFING WET ELECTROSTATIC PRECIPITATORS
Item
Design Operating Conditions
Gas volume
Gas temperature
762 x 533 mm
Billet
736 m3/min
10-66 C
(30 x 21 inch)
Mill
26, 000 ACFM
50-150 F
1016 mm (40 inch)
Blooming Mill
708 m3/min 25, 000 ACFM
52 C 125 F
1143 x 2286 mm (45 x 90 inch)
Slabbing Mill
4, 248 m3/min 150, 000 ACFM
38-66C 100 -150 F
Moisture content
Average gas inlet loading
Average gas outlet loading
Test Results
Gas volume
Gas temperature
Moisture content
Average gas outlet loading
Scarfing rate
Saturated
3.43 grams/m3 1. 50 grains/SCFD
0. 07 grams/m3 0. 03 grains/SCFD
643 m3/min 22, 700 ACFM
24 C 75 F
5. 5 percent
0. 016 grams/m3 0. 007 grains/SCFD
81 tonne/hr 89 net tons/hr
5 percent
2. 98 grams/m3 1.30 grains/SCFD
0. 07 grams/m3 0. 03 grains/SCFD
739 m3/min 26,100 ACFM
46 C 115 F
2.1 percent
2-10 percent
0. 23 grams/m3 0.30 grains/SCFD
0. 07 grams/m3 0. 03 grains/SCFD
2, 889 m3/min 102, 000 ACFM
33 C 91 F
4. 6 percent
0. 019 grams/m3 0. 008 grains/SCFD 0. 023 grams/m3 0. 010 grains/SCFD
152 tonne/hr 168 net tons/hr 428 tonne/hr 472 net tons/hr
ACFM - Actual cubic feet per minute.
Grain = 1/7000 pound.
SCFD - Standard cubic foot (dry).
-------
VI. REFERENCES
(1) Directory of Iron and Steel Works of the United States and Canada,
American Iron and Steel Institute, 1974, pp. 19-359.
(2) Brown, D. I. , Mini and Medium Steel Plants of North America -
A Roundup, Iron and Steel Engineer, 52: MM-51, November 1975.
(3) Communication from B. Steiner, Armco Steel Corporation to
J. Varga, Jr., Battelle's Columbus Laboratories, July 7, 1975.
(4) Large Fan Pulls 90, 000 CFM of Air Through Scrubber at Steel
Tube Plant, Industrial Heating, 39: 494,498, March 1972.
(5) Labee, C. J. , From Sand to Steel — The Burns Harbor Story,
Iron and Steel Engineer, 48: B18-B48, October 1971.
(6) Bethlehem Installing Hot Scarfer System, American Metal Market,
p. 4, December 27, 1968.
(7) Kleinman, M. , Planning and Design of Bethlehem's Hot Scarfing
Facility at Johnstown, Iron and Steel Engineer, 47: 108, 110,
April 1970.
(8) Communication from R. C. McCrillis, Environmental Protection
Agency to J. Varga, Jr., Battelle's Columbus Laboratories,
April 25, 1975.
(9) Communication from J. W. Leming, Jr. , Bethlehem Steel Cor-
poration to R. C. McCrillis, Environmental Protection Agency,
June 27, 1975.
(10) Communication from H. C. Henschen, Bethlehem Steel Corpora-
tion to J. Varga, Jr., Battelle's Columbus Laboratories,
August 8, 1975.
28
-------
(11) Communication from F. Jackson, Copperweld Corporation to
J. Varga, Jr., Battelle's Columbus Laboratories, April 29, 1975.
(12) Kotsch, J. A., and Labee, C. J., Annual Review 1974 - Develop-
ments in the Iron and Steel Industry, Iron and Steel Engineer,
52; D6, January 1975.
(13) Communication from H. B. Beech, Ford Motor Company to
J. Varga, Jr., Battelle's Columbus Laboratories, July 7, 1975.
(14) Communication from J. R. Brough, Inland Steel Company to
J. Varga, Jr., Battelle's Columbus Laboratories, July 8, 1975.
(15) Communication from D. H. Miller, Jones & Laughlin Steel
Corporation to J. Varga, Jr., Battelle's Columbus Laboratories,
July 8, 1975.
(16) J & L 2nd Quarter Earnings Drop 50% Below 1st Qtr. , American
Metal Market, 82: 2, June 17, 1975.
(17) Annual Review — Developments in the Iron and Steel Industry
During 1973, Iron and Steel Engineer, 51: D7, January 1974.
(18) Communication from J. Pounds, Kaiser Steel Corporation to
J. Varga, Jr., Battelle's Columbus Laboratories, July 7, 1975.
(19) Annual Review — Developments in the Iron and Steel Industry
During 1974, Iron and Steel Engineer, 52: D10, January 1975.
(20) McNabb, A. J. , Cold Ingot Scarfing Machine - Phoenix Steel,
Iron and Steel Engineer, 51: 60-63, November 1974.
(21) Republic Awards Contract for Precipitator, Iron and Steel Engi-
neer, 52: p. 112, October 1975.
(22) Communication from W. Tucker, Republic Steel Corporation to
J. Varga, Jr. , Battelle's Columbus Laboratories, July 18, 1975.
(23) Communication from C. M. Brown, Republic Steel Corporation to
J. Varga, Jr., Battelle's Columbus Laboratories, July 1, 1975.
(24) Brown, D. I. , Mini and Medium Steel Plants of North America —
A Roundup, Iron and Steel Engineer, 52; MM-55, November 1975.
29
-------
(25) Timken Co. Blueprints $50-Million in Projects, American Metal
Market/Metalworking News, 81: p. 28, April 1, 1974.
(26) Communication from E. Leisser, Timken Company to J. Varga,
Jr., Battelle's Columbus Laboratories, May 2, 1975.
(27) Communication from P. X. Masciantonio, United States Steel
Corporation to J. Varga, Jr., Battelle's Columbus Laboratories,
September 16, 1975.
(28) Ess, T. J. , Fairless Works - United States Steel's Newest, Iron
and Steel Engineer, 31: F75, June 1954.
(29) Communication from J. G. Munson, United States Steel Corpora-
tion to J. Varga, Jr., Battelle's Columbus Laboratories, July 7,
1975.
(30) Double Grinder, Iron and Steel Engineer, 52: p. 115, October 1975.
(31) Communication from W. P. McShane, Wheeling-Pittsburgh Steel
Corporation to J. Varga, Jr., Battelle's Columbus Laboratories,
July 8, 1975.
(32) Communication from T. M. Hendrickson, Youngstown Sheet and
Tube Company to J. Varga, Jr., Battelle's Columbus Laboratories,
May 5, 1975.
(33) Communication from E. J. Lancellotti, Union Carbide Corporation,
Linde Division to J. Varga, Jr., Battelle's Columbus Laboratories,
June 20, 1975.
(34) Communication from A. L. Hodge, Union Carbide Corporation,
Linde Division to J. Varga, Jr., Battelle's Columbus Laboratories,
January 30, 1969.
(35) Elliott, A. C. , and LaFreniere, A. J. , The Design and Operation
of a Wet Electrostatic Precipitator to Control Billet Scarfing
Emissions, Preprint No. 71-159, Air Pollution Control Associa-
tion meeting in Atlantic City, New Jersey, 9 pp. , June 27-July 1,
1971.
30
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(36) Glossbrenner, A. B., Timken Steel and Tube Division's Approach
to Bloom and Billet Conditioning, AIME Metallurgical Society
Conference, Vol. 13. Bar and Applied Products, Interscience
Publishers, New York, N. Y. (1961).
(37) Trilli, L. J., Hot Machine Scarfing of Semi-Finished Carbon
Steels, AIME Metallurgical Society Conference, Flat Rolled
Products II: Semi-Finished and Finished, Interscience Publish-
ers, New York, N. Y., 6: 3-17, I960.
(38) Whittaker, R., and Long, R. L., Factors Affecting the Yield of
Free-Cutting Steels at Park Gate, ISI Publication 107, The Iron
and Steel Institute, 47-55, 1967.
(39) Keefe, J. M. , Optimization of Yield in Wide Strip Rolling, Part 2:
Ingot to Pickled Coil, Optimization of Steel Product Yield, ISI
Publication 107, The Iron and Steel Institute, 64-72, 1967.
(40) McLean, C. J. , Control of Defects - Flat Rolled Products, Blast
Furnace and Steel Plant, 54: 231-240, March 1966.
31
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-76-054
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Control of Steel Plant Scarfing Emissions Using
Wet Electrostatic Precipitators
5. REPORT DATE
March 1976
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
John Varga, Jr.
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Battelie-Columbus Laboratories
505 King Avenue
Columbus, Ohio 43201
10. PROGRAM ELEMENT NO.
1AB015; ROAP 21AQR-042
11. CONTRACT/GRANT NO.
68-02-1323, Task 32
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Task Final; 3-8/75
14. SPONSORING AGENCY CODE
EPA-ORD
is. SUPPLEMENTARY NOTES EpA prOject officer for this report is R. C. McCrillis, Mail
Drop 62, Ext 2557.
16. ABSTRACT
The report discusses the purpose of scarfing slabs, blooms, and billets,
as an introduction to a discussion of the control of emissions from steel plant
scarfing machines. Some technical design information pertaining to wet electrostatic
precipitators is presented, as is the limited amount of information available on the
characteristics of scarfing emissions. Operating characteristics are given for sev-
eral electrostatic precipitators presently in operation in scarfing applications. The
report responds to Item AM-5-1 of the Protocol of the First Working Meeting of the
U.S./USSR Task Force on Abatement of Air Pollution from the Iron and Steel Industry
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATl Field/Group
Air Pollution
Iron and Steel Industry
Scarfing
Electrostatic Precipitators
Air Pollution Control
Stationary Sources
13B
1106, 0503
13H
09C
3. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (Tins Report)
Unclassified
21.
. OF PAGES
39
?0. SECURITY CLASS /This naar
Unclassiiied
2?. PRICE
EPA Form 2220-1
33
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