United States Industrial Environmental Research EPA-600/7-78-177a
Environmental Protection Laboratory September 1978
Agency Research Triangle Park NC 27711
University
of Washington
Electrostatic
Scrubber Tests
at a Steel Plant
Interagency
Energy/Environment
R&D Program Report
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. 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 INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for publication. Approval does not signify that the contents necessarily reflect the
views and policies of the Government, 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.
-------
EPA-600/7-78-177a
September 1978
University of Washington
Electrostatic Scrubber Tests
at a Steel Plant
by
M J. Pilat, G A. Raemhild, and A. Prem
University of Washington
Department of Civil Engineering, FX-10
Seattle, Washington 98195
Grant No R804393
Program Element No. EHE624A
EPA Project Officer: Dale L. Harmon
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
-------
ABSTRACT
3
A 1,700 m /hr (1000 acfm) University of Washington Electrostatic
Spray Scrubber was tested on an electric-arc steel furnace to demonstrate
its effectiveness for control Ting the emissions of fine particles. The
two stage, portable pilot plant operates by combining oppositely
charged aerosol particles and water droplets in two water spray towers.
Aerosol charging sections (coronas) with negative polarity precede
each spray tower.
Simultaneous inlet and outlet source tests utilizing University of
Washington Cascade Impactors, Mark V for the inlet and Mark III for the
outlet, provided both size-dependent and overall mass basis particle
collection efficiency information. Measured overall particle collection
efficiencies ranged from 58.8 to 99.5% depending upon the electrostatic
scrubber operating conditions and upon the inlet particle size distribution.
Tabular and graphical data is presented illustrating the effects of the
corona specific plate area (SCA), liquid to gas flow rate ratio (L/G),
magnitudes of particle and droplet charging voltages, and electrostatic
polarities on the overall particle collection efficiencies and on the
particle collection efficiency as a function of particle size.
m
-------
Table of Contents
Page
Abstract iii
Table of Contents iv
List of Figures v
List of Tables vii
Acknowledgements viii
I. Summary and Conclusions 1
II. Recommendations 2
III. Research Objectives 3
IV. .Description of the Source 4
V. Experimental Equipment and Procedures 5
A. UW Electrostatic Scrubber Apparatus 5
B. Description of Source Test Equipment 20
VI. Results 22
A. Particle Collection Efficiency Tests 22
B. Particle Collection Efficiency as a Function of 26
Particle Size
C. Particle Size Distribution Measurements 35
VII. References 50
-------
List of Figures
Fig. V-l. General Layout of Electrostatic Scrubber Pilot Plant 6
Fig. V-2. Cooling Tower Schematic 7
Fig. V-3. Particle Charging Corona Section 9
Fig. V-4. Collection Plate Flushing System 11
Fig. V-5. Spray Tower #1 Nozzle Configuration 12
Fig. V-6. Spray Tower #2 Nozzle Configuration 13
Fig. V-7. Charged Liquor Recycle System 16
Fig. V-8. Heated Purge Air System 19
Fig. V-9. UW Cascade Impactor Sampling Train 21
Fig. VI-1. Effect of Corona and Spray Voltage on Particle 27
Collection Efficiencies
Fig. VI-2. Effect of SCA and L/G on Efficiency 28
Fig. VI-3. Effect of Charging Voltages on Particle Collection 29
Efficiencies
Fig. VI-4. Effect of Charging Polarities on Particle Collection 30
Efficiencies
Fig. VI-5. Effect of Liquid-to-Gas Flow Rate on Particle 31
Collection Efficiencies
Fig. VI-6: Effect of Liquor Charging Voltages on Particle 32
Collection Efficiency of Spray Tower #2
Fig. VI-7. Particle Collection Efficiency of Spray Towers 1 and 34
2 with Coronas and Mist Eliminator Off
Fig. VI-8. Simultaneous Tests with Mark 5 UW Cascade Impactor at 36
Inlet of Electrostatic Scrubber Pilot Plant
Fig. VI-9. Inlet Particle Size Distributions for Tests 37
17, 18, 19, 20, and 21
Fig. VI-10. Outlet Particle Size Distributions for Tests 38
17, 18, 19, 20, and 21
Fig. VI-11. InTet Particle Size Distributions for Tests 39
22, 23, 26, 27, 28, and 29
Fig. VI-12. Outlet Particle Size Distributions for Tests 40
22, 23, 26, 27, 28, and 29
Fig. VI-13. Inlet Particle Size Distributions for Tests 41
31, 32, 35, 36, 37, and 38
Fig. VI-14. Outlet Particle Size Distributions for Tests 42
31, 32, 35, 36, 37, and 38
-------
Page
Fig. VI-15. Inlet Particle Size Distributions for Tests 43
31, 32, 39, and 41
Fig. VI-16. Outlet Particle Size Distributions for Tests 44
31, 32, 39, and 41.
Fig. VI-17. Inlet Particle Size Distributions for Tests 45
31, 32, 45, and 51
Fig. VI-18. Outlet Particle Size Distributions for Tests 46
31, 32, 45, and 51 ,
Fig. VI-19. Inlet Particle Size Distributions for Tests 47
56, 57, 59, 60, 61, and 62
Fig. VI-20. Outlet Particle Size Distributions for Tests 48
56, 57, 59, 60, 61, and 62
Fig. VI-21. Inlet and Outlet Particle Size Distributions for 49
Test 67
-------
List of Tables
Page
Table V-l. High Voltage Power Supply Units 15
Table V-2. Source Test Parameters and Measurement Techniques 20
Table VI-1. Results of Tests at Electric Arc Steel Furnace 23
-------
ACKNOWLEDGEMENTS
The authors gratefully acknowledge the assistance, advice, and
guidance of our Project Officer, Dale L. Harmon, Chemical Engineer
in the Particulate Technology Branch, Utilities and Industrial Power
Division of the Industrial Environmental Research Laboratories of the
Environmental Protection Agency. The discussions and assistance of
Leslie E. Sparks and James H. Abbott of EPA/IERL are appreciated. The
cooperation and assistance of Harold Schubert and Bob Dutton and their
colleagues at the Seattle plant of the Bethlehem Steel Corporation
provided a major contribution toward the success of our research
project. The efforts of Greg LaFlam, Gene Fioretti, John Lukas, and
Matt Jensen with the pilot plant operation and source testing are
acknowledged.
-------
Section I
SUMMARY AND CONCLUSIONS
3
A 1,700 m /hr (1000 acfm) University of Washington Electrostatic
Spray Scrubber portable pilot plant was tested at an electric-arc steel
furnace in Seattle to demonstrate its effectiveness for controlling the
emissions of fine particles. The pilot plant consists of a cooling
tower, two corona sections which charge the particles to a negative
polarity, two spray towers into which positively charged water droplets
are sprayed, and an electrostatic mist eliminator.
Some problems were encountered during the earlier tests resulting
in lower particulate collection efficiencies than expected. The system
was modified to rectify these problems and high particulate collection
efficiencies were obtained throughout the particle size range. Measured
overall particle collection efficiencies ranged from 58.8 to 99.5%
depending upon the electrostatic scrubber operating conditions and upon
the inlet particle size distribution. During the tests, the inlet
particulate mass concentrations to the Electrostatic Scrubber varied
from a maximum of 10.87 gm/Nnr (4.753 grains/SDCF) to a minimum of
0.0782 gm/Nm3 (0.03417 grains/SDCF).
The electric-arc furnace tests showed that the particle collection
efficiency increased as:
a. The aerosol and/or droplet changed from an uncharged to a
charged state.
b. The gas residence time in the pilot plant increased.
c. The water to gas ratio (i.e., gal/1000 acf) increased.
d. The particles and the droplets were oppositely charged.
In conslusion, it appears that the University of Washington
Electrostatic Spray Scrubber has the capability of effectively collecting
fine particles at a relatively low pressure drop across the system.
Further, the system has a significantly higher particle collection
efficiency than a conventional water spray tower operating with no
electrostatic charge.
-------
Section II
RECOMMENDATIONS
After this year's research project on the UW Electrostatic Scrubber
which consisted mainly of the extensive testing of the system at the
electric-arc steel furnace, additional testing at field sites is needed
in order to correlate the particle collection efficiency as a function of
particle size to the design and operating parameters of this pilot plant.
We also recommend that the results from the extensive field testing
program be used in comparison with theoretically predicted particle collection
efficiency as a function of size.
Finally, we recommend that the pilot plant be used to demonstrate
its effectiveness for simultaneous control of particulate and S0? emissions
from coal-fired boilers.
-------
Section III
RESEARCH OBJECTIVES
The objectives of the research performed under the auspices of
Environmental Protection Agency Grant Number R803278 were to:
1. Demonstrate the effectiveness of the University of Washington
electrostatic wet scrubber for controlling the emissions of
fine particles from industrial sources.
2. With a portable 1,700 m /hr (1000 acfm) pilot plant of the
University of Washington Electrostatic Wet Scrubber, obtain
the data needed to design a larger electrostatic scrubber
system.
-------
Section IV
DESCRIPTION OF THE SOURCE
The UW Electrostatic Scrubber was connected to a duct exhausting
from two electric-arc steel furnaces at the Bethlehem Steel Company in
Seattle, Washington. This source was selected for the tests because the
emission particles contain a large portion in the submicron size range.
The furnaces are top charged and each furnace taps a heat of over 115
tons of refined steel every 3% to 4 hours. Based on the mode of operation
of the furnaces, the inlet particulate concentration to the Electrostatic
Scrubber varied from a maximum of 10.87 gm/Nm3 (4.753 grains/SDCF) to a
minimum .of 0.0782 gm/Nm3 (0.03417 grains/SDCF).
It is reported that the fume-dust emissions during the melt period
contained nonhygroscopic solid particles. The particulates consist
largely of metallic oxides, such as iron oxide, zinc oxide, lead oxide, and
calcium oxide. The percentages vary with each heat. A typical analysis
is as follows:
Iron oxide (Fe^) 37%
Zinc oxide (ZnO) 35%
- Lead oxide (PbO) 7%
Calcium oxide (CaO) 5%
Manganese dioxide (MnOp) 4%
- Silica (Si02) 3%
- Total sulfur (S03) 1%
Copper oxide (CuO) 0.4%
Miscellaneous oxides 3.5%
The furnace fumes are drawn off through an opening in the furnace
roof, through a water-cooled elbow connecting the roof opening to a
cylindrical vertical spray chamber where the gases are cooled down to
316 C (600 F). The flue gases are then transported through a 2.13 m (7 ft.)
diameter duct for 107 m (350 ft.)to the main fan. The induced draft fan
has a capacity of 220,350 Nm3/hr (130,000 SCFM) and will develop a total
head of 0.254 m (10 in.) of water. The flue gas from the main fan is
exhausted to the atmosphere after passing through a baghouse.
-------
Section V
EXPERIMENTAL EQUIPMENT AND PROCEDURES
A. UW ELECTROSTATIC SCRUBBER APPARATUS
1. Description of Overall System
The major components of the pilot plant include a gas cooling tower,
an inlet and outlet test duct, two particle charging corona sections, two
charged water droplet spray towers, and a mist eliminator. Auxiliary
equipment includes transitional ductwork between major components and a fan.
The pilot plant is housed in a 12.2 m (40 ft.) long trailer and can be
easily transported to different emission sources.
The general layout of the pilot plant is shown in Fig. V-l. Incoming
gases enter the top of the trailer to be treated in the vertical gas cooling
tower and then turn vertically upward to enter the inlet test duct. After
moving down through the inlet test duct, the gases enter the first of three
horizontal passes.
The first pass contains both particle charging corona sections and
the first of two water spray towers. The two coronas are at either end of
this pass and are separated by spray tower #1. Spray tower #2 comprises
the entire second horizontal pass and the last (third) pass contains the
mist eliminator.
At the outlet of the third horizontal pass, the gases enter the top
of the outlet test duct and are then directed to the fan before being
exhausted through the trailer roof.
2. Cooling Tower
The cooling tower is designed to lower the gas temperature to below
121°C (250°F) in order to maintain structural integrity of the system
which is constructed of steel and fiberglass reinforced plastic. The
cooling tower, as shown in Fig. V-2 is 0.36 m (14 in.) in diameter x
2.98 m (9 ft. 8 in.) in height and is constructed of 12 gage T. 304
stainless steel. Cooling water is introduced through four ports spaced
at 0.61 m (2 ft.) intervals on one side of the tower and is sprayed
vertically upward from the tower's centerline. Four Bete Model W 10080 F
full cone stainless steel nozzles used for spraying are capable of delivering
up to 11.35 1/min (3.0 gpm) at 50 psig. A funnel built into the bottom of
the spray tower extends through the trailer floor for cooling water removal.
-------
INCOMING
GASES
COOLING
TOWER
P
INLET TEST DUCT
SPRAY TOWER NO. 2
'St
CORONA NO I
EXHAUST
GASES
SECTION A-A
CROSS SECTIONAL VIEW OF
THREE RASS HORIZONTAL SECTION
OUTLET TEST DUCT
MIST
ELIMINATOR
SPRAY TOWER NO. 2
SPRAY TOWER NO. I
CORONA NO. 2
ELEVATION VIEW
FAN
Fig. V-l. General Layout of Electrostatic Scrubber Pilot Plant
-------
.61m
ro
.61 m
.61 m
.61 m
2.95 m
o
_J.
3
o
a>
-s
c/i
o
3-
a>
o>
r+
n
GAS FLOW
DIRECTION
1= X
-------
3. Particle Charging Corona Sections
Particle charging corona sections are located at either end of the
first horizontal gas passage. The corona shells are constructed from
4.76mm (3/16 in.) wall thickness fiberglass reinforced plastic (FRP)
with interior dimensions of 0.61 m (24 in.) wide x 1.07 m (42 in.) high x
1.52 m (60 in.) long in the direction of gas flow. Access to a corona
interior is through removable 4.76 mm (3/16 in.) FRP end plates which are
normally bolted to 5.08 cm (2 in.) full perimeter face flanges on either
end of a corona.
The coronas are designed to operate in either a single or double
lane gas passage mode. Switching from one to another requires rearrange-
ment of the adjustable collection plates and discharge frame(s). The
width of individual gas lane(s) for either mode is maintained at 0.30 m
(12 in.) and the discharge frame to collection plate spacing is therefore
0.15 m (6 in.). Fig. V-3 shows a cutaway schematic of a corona set up
for single lane operation.
The overall dimensions of the discharge frame shown in Fig. V-3 are
0.70 m (27% in.) high x 1.14 m (45 in.) long. The frame is constructed
from 6.35 mm x 19.05 mm (% in. x 3/4 in.) T. 304 stainless steel rectangular
bar stock members. Eight members each 0.69 m (27 in.) high are spaced
vertically and perpendicularly to gas flow and form a grid type pattern.
The collection plates shown in Fig. V-3 are 1.05 m (41% in.) high x
1.50 m (59 in.) long and are constructed from 11 gage T. 316 stainless steel.
The plates serve as full chamber baffles to keep the gases within the
confines of the single lane passage.
A negative corona is used to charge the particles negatively. This
is accomplished by maintaining.the discharge frame(s) at a high negative
potential and the collection plates at a neutral or ground potential. The
discharge frame is electrically isolated from all other components inside
the corona. This isolation is provided by suspending the frame on two
2.54 cm (1 in.) diameter T. 303 stainless steel rods which are connected
to porcelain insulators. The Ceramaseal Model 902B1353-6 insulators are
housed in 0.30 m (12 in.) diameter x 0.61 m (24 in.) long x 6.35 mm (% in.)
wall thickness plexiglass tubes which are centered 1.07 m (42 in.) apart
and are located on top of the corona shells. Two 0.30 m (12 in.) to 0.36 m
(14 in.) x 7.62 cm (3 in.) FRP reducting flanges are used to join the
plexiglass tubes to the corona top.
The insulators are continually flushed with a supply of heated purge
air. The temperature of the purge air is maintained at about 49°C (120°F)
and an even flow across a plexiglass tube section is obtained by introducing
the purge air through a distribution plate having approximately 10% hole area,
The flushing face velocity of the purge air is set at about 0.18 m/sec (0.6
ft/sec). This same purge air distribution flange also serves as a support
flange in that an insulator, and hence the discharge frame(s), is bolted
directly to it. The high voltage lead-in to the discharge frame is through
one of the two feed-through type insulators.
-------
REMOVABLE GROUND PLATE (S.S.)
FOR ONE LANE OPERATION
HIGH VOLTAGE
FEEDER CABLE
'
HIGH
VOLTAGE INSULATOR
DISCHARGE FRAME
SUSPENSION ROD
HIGH VOLTAGE
DISCHARGE FRAME
GAS INLET
AND OUTLET OPENING
PURGE AIR DUCT
FRP WALLS
S.S. GROUND PLATE (OUTER)
FOR TWO LANE OPERATION
GROUND PLATE ALIGNMENT
AND SUPPORT BARS
Fig. V-3. Particle Charging Corona Section
-------
A water flushing system designed to clean the collection plates
is utilized in both coronas and is shown schematically in Fig. V-4. Two
water spray headers are situated inside the top of each corona shell.
Water is intermittently sprayed through Bete Model 45080 80° stainless
steel fan nozzles and covers the entire active portion of the collection
plates.
2
At the nominal gas flow rate of 1,700 m /hr (1,000 cfm), the gas
velocity in the corona is 1.45 m/sec (4.76 ft/sec) for single lane
operation and 0.72 m/sec (2.38 ft/sec) for double lane operation. The
corresponding gas residence times are 1.05 and 2.10 seconds. By varying
the volume of air flow through the system, however, the gas residence time
can range from 0.70 seconds (single lane operation at 2,548 nr/hr (1,500
cfm)) to 4.20 seconds (double lane operation at 850 nr/hr (500 cfm)).
4. Water Spray Tower
The first of two spray towers used in the pilot plant is situated
in the middle of the first horizontal gas passage (between the two coronas)
while the second spray tower comprises the entire second horizontal gas
passage. Both spray towers are 0.91 m (3 ft.) in diameter x 4.76 mm
(3/16 in.) wall thickness and are constructed from FRP. The lengths of
the two spray towers are 3.05 m (10 ft.) and 7.36 m (24 ft.) for tower #1
and #2 respectively.
A total of 21 Bete Model TF.GFCN teflon full cone nozzles are used
to produce water droplets in the two towers. All nozzles spray in the
direction of gas flow (co-currently). The first spray tower contains six
nozzles arranged on one spray header. The arrangement of the spraying
pattern in tower #1 is shown schematically in Fig. V-5.
One header with a total of 16 spray nozzles is employed in spray
tower #2. The nozzles in this tower are arranged as shown in Fig. V-6.
A positive charge is imparted to the water droplets by maintaining
the nozzles at a positive potential (direct charging). The nozzles are
electrically isolated from the spray tower walls by introducing heated
purge air through 7.62 cm (3 in.) diameter x 10.16 cm (4 in.) long
polyvinyl chloride (PVC) entry caps which are situated on top of the two
spray towers (see Fig. V-5, V-6). Both the water and the high voltage
lead-in cable enter through a 6.35 mm (k in.) diameter street tee fitting
connected to the middle of each entry cap.
5. Mist Eliminator
The mist eliminator is situated in the middle of the third and last
horizontal pass and is used to remove entrained water droplets from the
airstream. The mist eliminator is identical to the coronas with the
following three exceptions:
10
-------
COLLECTION PLATES
(SINGLE LANE OPERATION)
PURGE AIR AND HIGH
VOLTAGE ENTRY (PURGE
AIR DUCTS, INSULATORS,
SUSPENSION RODS AND
DISCHARGE FRAME) OMITTED
FOR CLARITY
WATER INLET TO COLLECTION
PLATE FLUSHING SYSTEM
CORONA SHELL
Fig. V-4. Collection Plate Flushing System
-------
WATER, HIGH VOLTAGE
AND PURGE AIR
ENTRY GAP
SPRAY NOZZLE
HEADERS
Fig. V-5. Spray Tower #1 Nozzle Configuration
-------
CO
WATER HIGH
VOLTAGE AND
PURGE AIR ENTRY
CAP
SPRAY NOZZLE
HEADER
Fig. V-6. Spray Tower #2 Nozzle Configuration
-------
1. The discharge frame is maintained at a positive potential.
2. The mist eliminator is not equipped with a collection plate flushing
system.
3. The mist eliminator is 5.08 cm (2 in.) shorter in height.
The last point noted above necessitates an equivalent shortening of the
discharge frame and collection plates.
6. Test Ducts
The inlet and outlet test ducts are located immediately before the
first corona and immediately after the mist eliminator respectively
(see Fig. V-l). Both test ducts are constructed from 4.76 mm (3/16 in.)
wall thickness FRP and are 0.30 m (12 in.) in diameter x 1.22 m (4 ft.)
long. Vertical gas flow in a downward direction is employed because it
allows the most conventient positioning of the particle sizing source
test equipment used as described in Section V-B, "Description of Source
Test Equipment." The particle sizing source test equipment also dictated
the size of the test ports which are 7.62 cm (3 in.) wide x 15.24 cm
(6 in.) high. The test ports are located three duct diameters downstream
and one duct diameter upstream from flow disturbances.
7. Fan
The fan used to induce the air flow (i.e., clean side) through the
pilot plant is a New York Blower Model RFE-12. The straight-bladed fanwheel
and housing are constructed from FRP. The fan is driven through a split
pulley belt drive by a Westinghouse 5 h.p., 208 volt, 3-phase motor turning
at 1,800 rpm and is capable of delivering up to 2,548 nrvhr (1,500 cfm) at
20.32 cm (8 in.) water column (WC) static pressure. The fan has a
horizontal inlet and a vertical outlet. A 4.76 mm (3/16 in.) FRP wall
thickness x 0.30 m (12 in.) diameter exhaust duct containing an adjustable
damper, extends up through the trailer roof.
8. High Voltage Power Supplies
Three high voltage power supply units used in the pilot plant serve
the coronas, mist eliminator, and water droplet charging. All three units
operate off a 110 volt, 60 Hz, 1 0 supply and are equipped with multi-
range voltage and current meters on the high voltage output side. The units
are also equipped with overvoltage and overcurrent surge protection. The
three power supplies are described in the following table.
14
-------
Table V-l. High Voltage Power Supply Units
Source
Coronas
Mist
Eliminator
Droplet
Charging
Model
Universal Voltronics
Hipotronics
#860-16
Hipotronics
#825-40
Polarity
Negative
Positive
Positive
Rated Output
kV mA
70 25
60 16
25 40
9. Water Supply System
a. General
The water supply system for the scrubber is controlled from a single
control panel situated on an interior side wall proximate to the
inlet test duct. Two different sources supply water to this control
panel: recycled water and fresh water. The positively charged
recycle water is used as scrubbing liquor in spray towers #1 and #2
and the fresh water (uncharged) is used in the flushing systems
and the cooling tower.
b. Water recycle system
A water recycle system was designed to satisfy the following
requirements:
1. Water flow rate of 30 gal/min
. 2. Water pressure of 40 psi (at nozzles)
3. Closed system with make-up capability
4. Continuous removal of particles greater than 30 microns.
The entire water plumbing system was redesigned to accommodate the
30 gal/min maximum flow rates as well as minimize frictional losses for
more economic pumping. PVC piping and nonconductive high pressure hose
were used. A schematic of the water recycle system iis shown in Fig. V-7.
A larger teflon spiral nozzle (Bete TF6TCN) was chosen since it
resists plugging by particles in the recycled water and is capable of
creating a relatively small droplet at higher flow rates. The total
number of nozzles was reduced to 21. Spray tower #1 has six nozzles and
is designed for a flow rate of 10 gal/min while spray tower #2 has 15
nozzles and is designed for 20 gal/min.
15
-------
LIQUOR FLOW- RATE
CONTROL BOARD
AIR FL
FRESH
WATER
MAKE-UP
ELECTRICAL
VALVE
LEVEL
fill PURGE AIR |~
. l:!_ j
r> -..- -i, - i- - - fi - - TI t-r -
TT
'LOWt
PUT
) B V.
-H h ' !'
ii ill!: !i Si
" nfcptfRdi/
1 1
lr-.-. - ..
jj ,' H '
' ! ' ! '
kv'* ,;*. ;«.. '^,
rv7 i' >
. ii i
j~|- PURGE AIRp
-ir - n
!' "
!' ,i;.
"* \ \
t
i1
1
B,
L
SPRAY TOWER:; NO. 1
V^Ty II V
30 ^H
1
;
-- ,1 ,-. - -p - -,
i,
A
1_
!
**:
,
^
r| PURGE AIR
- -i ~
I
!| j! i Ji i!
:-i! J v - ^ <:
'URGE AIR v
SPRAY TOWER
N0.2
1"|
RAIN (PVC)
3AIR FLOW
CHARGE
DROPLE
POWER
SUPPL'
6 DRAIN (PVC)
D
T
f
0 DRAIN (PVC)
"ELEVATION VIEW"
TRANSFER PUMP
Fig. V-7. Charged Liquor Recycle System
-------
A Goulds centrifugal pump model 3196ST was chosen to satisfy the
water flow rate and pressure head requirements. Since the spray charging
is achieved by applying from 0 to 30 kV at the throat of each nozzle, the
pump will also be at an elevated potential. It is therefore electrically
isolated on a micarda base with a FRP cover.
The sprayed water is drained from the spray towers into a 135 gallon
settling tank. The settling tank acts as an elutriation chamber designed
such that particles greater than 30 microns in diameter will settle out
with a maximum water flow rate of 30 gal/min. A 3 hp, 3,600 rpm, 110 V,
1 0 Deming centrifugal pump transfers the recycled water from the settling
tank through sprays into the sump tank at a maximum rate of 30 gal/min.
From the sump tank the water is recycled back into the spray towers by
the Goulds pump previously described.
The sump tank is equipped with a liquid level control and fresh
water make-up capability. The Sethco Liquid Level Control is a three
function controller which operates on the action of captive air pressure
in a CPVC column. When the water level in the sump tank is sufficiently
high, no make-up water is injected. When the sump tank water level drops
to a pre-set middle level, the level controller will signal an electrically
actuated ball valve to open and allow fresh make-up water to flow into the
tank. When the water level in the tank becomes dangerously low, the level
controller will activate a relay switch which will shut the pump off.
When a pre-determined amount of fresh make-up water is desired for dilu-
tion purposes, a spray from the water control board can be regulated to
allow continuous make-up water addition.
10. Fresh Water System
The three applications for fresh (uncharged), water are described
below:
1. Test duct cleaning system
One Bete Model W10080F full cone stainless steel spray nozzle
is positioned at the top of both the inlet and outlet test ducts.
Since only infrequent cleaning is required at these locations,
water flow is not monitored.
2. Corona collection plate flushing system
The details of these two users have been specified in Section V-3,
"Particle Charging Corona Sections." The flow rate is not
monitored.
3. Cooling tower spray system
This user, described in Section V-2, "Cooling Tower," is equipped
with a Fisher-Porter Model 2235631 3,8-41.6 1/min (1-11 gpm)
Ratosight rotometer.
17
-------
11. Purge Air Heating System
The new purge air heating system is schematically illustrated in
Fig. V-8. The system consists of both commercially available and
custom built components. The fan is a Barry Blower model BUF-90
Junior Fan employing a 1/3 HP motor with a maximum capacity of
500 cubic feet per minute. The discharge air then passes through
a custom designed Nelco Duct Heater. It is a 19kw heating unit
with 4 stages to regulate the degree of heating required. The
duct heater operates on 308V, 3(j) power with a 110V control source
which is external of the heater. A custom designed distribution
plenum follows the heater and provides an adjustable purge air
supply to the high voltage access points on the two corona sections,
the mist eliminator section and the current limiting device for
the liquid make up to the sump tank. The basic design criterion for
the purge air system is to provide 150 F purge air at a rate of up
to 500 cfm (total).
18
-------
FRESH WATER
MAKE-UP
SPRAY
RECYCLE SUMP
CORONA NO. I
DISTRIBUTION PLENUM-^
MIST
ELIMINATOR
FILTER
CORONA N0.2
DUCT
HEATER
FAIN
<^PURGE AIR
INLET
"ELEVATION VIEW"
MIST ELIMINATOR
Fig. V-8. Heated Purge Air System
-------
B. DESCRIPTION OF SOURCE TEST EQUIPMENT
1. General
The following table indicates the source test equipment used to
measure various parameters. Further information concerning the UW
Cascade Impactor is given below.
Table V-2. Source Test Parameters and Measurement Techniques
Parameter
Equipment
1. Air
2.
a. Velocity and volume
b. Temperature
c. Moisture
Water Spray Towers
a. Water flow
3. Aerosol
a. Mass concentration
b. Size distribution
S-type pilot tube with
draft gauge
Thermometer
Wet and dry bulb thermometer
and checked by volume of
condensate
Rotometers
UW Mark III and Mark V Cascade
Impactors
UW Mark III and Mark V Cascade
Impactors
2. UW Cascade Impactor
The UW Mark III and Mark V Cascade Impactors were used to measure
both particle size distribution and mass concentration at both the inlet
and outlet test ducts respectively. The impactors provide this information
by segregating the aerosol sample into discrete size intervals (seven
collection plates plus one final filter for Mark III and eleven collection
plates plus one final filter for Mark V). The aerosol weight on each
plate provides size distribution information and the total weight is used
to determine the mass concentration. The basic components of a sampling
train utilizing a UW Cascade Impactor are shown schematically in Fig. V-9.
The impingers are used to collect water vapor in the sample air stream
and provide a basis for calculating the moisture content of gas stream
which may be checked against the wet and dry bulb determination. The
dry gas meter is used to determine isokinetic sampling conditions as well
as the total sample volume.
By conducting simultaneous particle size distribution tests at both
the inlet and outlet test ducts, the size-dependent collection efficiency
curve of the pilot plant may be measured.
20
-------
GAS I
FLOW!
TEST DUCT
IM FACTOR
1/2 * STEEL
PIPE PROBE
VACUUM
HOSES
IMPINGER
COURSE ADJUST
VALVE
VACUUM
GAUGE
SILICA
GEL
ICE BOTTLE BATH
o
s
V
T
I J
, 7
"'IX,*'
*
^
J
0
o
1 1J
*
r*
7
KNOCK
OUT
FINE ADJUST THERMOMETERS
VALVE
AIR TIGHT
PUMP
DRY GAS
METER
Fig. V-9 UW Cascade Impactor Sampling Train
-------
Section VI
RESULTS
A. PARTICLE COLLECTION EFFICIENCY TESTS
The results of the particle collection efficiency source tests are
presented in Table VI-1. During the earlier tests (1-16) it was found
that the particle collection efficiency of the system was less than
expected for these tests. This was due to the particle build-up in the
duct downstream of the mist eliminator resulting in particle re-entrain-
ment. The particle re-entrainment problem was detected by a test per-
formed with clean (atmospheric) air which showed a higher outlet particu-
late concentration than at the system inlet (clean water was used as the
scrubbing liquor). Washing down the duct downstream of the mist eliminator
corrected this situation.
Tests 17 to 21 were conducted to study the effect of corona and spray
voltages on collection efficiencies. The liquid-to-gas flow ratio and the
gas residence time in the system were kept constant. The particulate
collection efficiencies during these tests improved compared to the pre-
vious tests but were still lower than expected. On checking out the
system, it was found that the liquor sprays from tower #1 were flooding
corona #2 reducing the particle charging capability of corona #2.
During tests 22 to 29, the liquor sprays to tower #1 were shut off
to eliminate the flooding of corona #2. These tests were run to determine
the effect of SCA and liquid-to-gas flow ratio on the particle collection
efficiency. From the results it is seen that the particulate collection
efficiency is enhanced significantly with higher liquid-to-gas flow ratio
and higher gas residence.time in the system.
After test 29, the pilot plant was shut down and the spray towers
and corona section were washed down thoroughly. Of the six nozzles in
tower #1, the downstream nozzle fittings were plugged and the other three
nozzles were replaced with nozzles providing a fine mist (manufacturer
data specifies 200-300 ym diameter droplets). A screen-type mist elimi-
nator was installed at the outlet of tower #1 (inlet to corona #2). All
the spray nozzles in tower #2 were replaced with the finer droplet nozzles.
The purpose of the above modifications was to obtain smaller droplets,
lower the liquor flow rate, and reduce the flooding of corona #2.
22
-------
Table VI-1 Results of Tests at Electric Arc Steel Furnace
Test
No.
1
2
3
4
5
6
7
8
9 .
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Gas Flow at
Outlet Duct
(acfm)
1,783
1,484
1,553
1,032
1,474
1,428
1,391
1,281
1,470
1,214
1,331
1,281
1,210
1,225
1,259
1,225
1,189
1,174
1,163
1,175
1,148
1,221
1,247
1,293
1,184
Water to Average
Gas-flow Ratio
(gal/1000 acf)
13.6
17.8
17.8
23.4
17.6
23.7
24.2
24.3
23.2
26.8
25.7
24.3
25.2
24.5
23.1
0
26.5
26.2
25.5
26.5
26.1
21.1
20.4
20.8
22.4
Voltage (kV)
Corona
#1 #2
-70 -70
-35 -35
-70 -70
-70 -70
-70 -70
-70 -70
-70 -70
-50 -50
-50 -50
-50 -50
-70 -70
-70 -70
0 0
0 0
0 0
-70 -70
-70 -70
-68 -68
-68 -68
-70 -70
0 0
-70 -70
-70 -70
-65 -65
-70 -70
Spray
#1 #2
+15 +15
+15 +15
+20 +20
0 0
+15 +15
+10 +10
+20 +20
0 0
+20 +20
+10 +10
+20 +20
0 0
+20 +20
0 0
+10 +10
0 0
+20 +20
+10 +10
0 0
+10 +10
+10 +10
0 +10
0 +10
0 0
0 0
Collection
Efficiency
(%)
94.2
94.0
98.1
95.3
92.6
97.4
87.9
89.0
80.2
81.0
91.0
85.6
83.7
80.4
58.8
87.9
93.4
96.6
97.9
97.3
88.8
97.7
96.4
93.3
98.2
Outlet
Cone.
(gr/scf)
0.0057
0.0025
0.0024
0.0016
0.0395
0.0025
0.0075
0.0978
0.0750
0.0811
0.0430
0.0178
0.1042
0.16797
0.33031
0.07380
0.0442
0.0285
0.0269
0.0313
0.1151
0.0194
0.0258
0.0315
0.0074
23
-------
Table VI-1 Results of Tests at Electric Arc Steel Furnace (cont.)
Test
No.
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
45
46
51
52
53
56
57
58
59
60
61
62
67
Gas flow at
Outlet Duct
(acfm)
905
953
1,309
1,338
1,296
. 1,302
1,298
1,122
1,253
1,227
1,233
1,263
1,265
1,228
1,223
1,212
1,260
1,285
1,026
1,290
891
1,031
985
1,067
1,089
1,011
1,018
952
994
997
Water to Average
Gas-flow Ratio
(gal/1000 acf)
32.3
31.8
17.2
17.1
15.8
14.5
14.6
19.9
15.1
14.7
14.9
14.9
14.6
14.9
14.6
15.2
8.9
8.7
12.7
8.5
14.2
12.9
9.2
8.5
8.3
8.9
8.6
9.3
8.7
15.9
Voltage (kV)
Corona
#1 #2
-65 -65
-65 -65
-70 -70
-70 -70
-70 -70
-70 -70
-70 -70
-70 -70
-70 -70
-70 -70
-68 -68
0 0
0 0
-70 -70
-70 -70
-70 -70
-70 -70
-65 -65
-70 -70
-70 -70
-70 -70
-69 -69
-60 0
-70 0
-70 0
-70 0
-70 0
-70 0
-70 0
0 0
Spray
#1 #2
0 +10
0 +10
0 +10
0 +10
+10 +10
+2 +2
+2 +2
+2 +2
+10 +10
0 0
0 0
+10 +10
0 0
-2 -2
-2 -2
-2 -2
+2 +2
+2 +2
+2 +2
+2 +2
+2 +2
+2 +2
0 +2
0 +2
0 0
0 0
0 +10
0 0
0 +10
0 0
Collection
Efficiency
(%)
99.1
98.9
86.5
83.7
96.6
98.5
98.8
98.6
98.8
97.3
95.6
82.0
79.7
98.0
97.4
97.8
99.5
97.8
98.2
96.5
98.4
92.7
93.1
83.7
80.4
91.3
85.5
91.5
82.0
68.5
Outlet
Cone.
(gr/scf)
0.00344
0.00524
0.1563
0.10095
0.00678
0.0100
0.00992
0.0129
0.0157
0.0312
0.03595
0.1226
0.1567
0.0234
0.01749
0.0093
0.00741
0.0299
0.0282
0.0430
0.00652
0.00965
0.02222
0.0345
0.03397
0.01468
0.00293
0.00917
0.00856
0.1283
24
-------
Tests 30 to 41 were run with both spray towers in operation and at
a total liquid flow rate of around 15 gal/min and a liquid pressure of
about 56 psig. These tests were run to determine the effect of particle
and droplet charging on the particulate collection efficiency and also
the effect of oppositely charged and some polarity charged particles and
droplets. For the oppositely charged case, the particles were charged
negatively in a corona at 70 kV and the droplets were charged at 2 kV.
In the same polarity case, both the particles and the droplets were
charged negatively at 70 kV and 2 kV respectively. The test results
show that oppositely charged particles and droplets give higher collection
efficiencies. The results from the tests that were run to determine the
effect of particle and droplet charging showed that particle charging
and droplet charging both enhance collection efficiency of particles.
Tests 42 to 53 were run to obtain some additional data on the effect
of liquid-to-gas flow ratio on the particle collection efficiency. During
these tests, the liquid flow rate was further reduced to 9 gal/min. With
the decrease in the liquid-to-gas flow rate, the collection efficiency of
the particles was lowered somewhat. The test results for tests 30 to 53
illustrate the system's capability for high efficiency fine particle
collection.
Tests 56 to 62 were conducted isolating tower #2. The tests were
run at the inlet and outlet of the number #2 spray tower in an effort to
isolate and measure the effect of liquor charging alone on the particle
collection efficiency. The number #1 corona was operating but corona #2
and spray tower #1 were off. These tests were run at a constant liquid
flow rate of 8 gal/min, constant gas residence time (constant gas flow
rate), and constant voltage (70 kV) on corona #1. Tests were run at three
different spray voltages: 0, 2, and 10 kV. The overall collection effi-
ciencies of spray tower #2 do not appear to correlate well with the applied
voltages. The electrostatic mist eliminator was inadvertently left on
during these tests and thus these tests reflect also the particle collection
efficiency of this unit. Therefore, in our opinion, no conclusions can be
made concerning the effect of liquor charging on the particle collection
efficiencies.
Test 67 was run as a baseline case with no charges on the particles
and droplets with the electrostatic mist eliminator turned off (in other
words the system was operated as a conventional spray droplet scrubber).
The particle overall collection efficiency was found to be 68.5%.
25
-------
B. PARTICLE COLLECTION EFFICIENCY AS A FUNCTION OF PARTICLE SIZE
The particle collection efficiency as a function of particle size
is presented in Fig. VI-1 through Fig. VI-6. Fig. VI-1 shows the effect
of the corona and spray voltages on the particle collection efficiencies.
During these tests flooding of corona #2 was experienced resulting in
the fairly low collection efficiencies in the submicron particle size
range. Also note that the liquor-to-gas flow rate was quite high during
these tests (about 26 gal/1000 acf) compared to later tests.
The effect of the corona SCA and the liquor-to-gas flow rate ratio
are illustrated in Fig. VI-2. During these tests the liquor to spray
tower #1 was shut off to eliminate the flooding of corona #2. Thus
Fig. VI-2 shows that at the highest SCA (about 0.094 sq. ft./cfm) and
L/G (about 32 gal/1000 acf), the particle collection efficiencies are of
the highest magnitude (about 99%).
Based on tests 22 to 29, it was concluded that very high particle
collection efficiencies were obtained by the system but at the expense
of high liquid-to-gas flow rates. After changing the nozzles in both
the spray towers and installing a screen mist eliminator downstream of
spray tower #1, tests were run to determine the effect of charging voltages
on the particle collection efficiencies. These test results are
illustrated in Fig. VI-3. The liquor-to-gas flow rate during these tests
was reduced to about 15 gal/1000 acf. The particle collection efficiencies
in the whole particle size range increased significantly when charges were
added to the particles and droplets. The highest particle collection
efficiencies with these tests at constant SCA and constant L/G occurred
at the particle charging voltage of 70 kV together with liquor charging
voltage of 2kV.
The effect of the electrostatic charging polarities is shown in
Fig. VI-4. The particle collection efficiencies were higher in the whole
particle size range considered. The arrangement with opposite polarities
provides the lower overall particle penetration (about 1.3%) compared to
same polarities at about 2.1%.
The effect of the liquor-to-gas flow rate ratio on particle
collection efficiency is shown in Fig. VI-5. The particle collection
efficiencies in all the particle size ranges considered increased
significantly upon increasing the L/G from about 8.6 gal/1000 acf to
14.6 gal/1000 acf. With this increase in L/G, the overall penetration
decreased from about 2.9% to 1.4% (this was all at constant SCA and
constant charging conditions).
Some tests were run at the inlet and outlet of the #2 spray tower
in an effort to measure the effect of the liquor charging on the particle
collection efficiency of the spray tower alone. The results are shown in
Fig. VI-6. The #1 corona was operating but corona #2 and spray tower #1
were off. The electrostatic mist eliminator was inadvertently left on
during these tests and thus these tests reflect also the particle collection
efficiency of this unit. The particle collection efficiencies for these
26
-------
89.9
Test Corona V. Spray V.
No. (kV) (kV)
17
20
18
19
21
Overall
Coll. Eff.
70 (-)
70 (-)
68 (-)
68 (-)
0
65
O. 89.0
O
O
I I
o
o
CJ
80.0
CJ
(XL
0.0
' ' 'L/G' ' ' Overal
SCA (gal/ Pen.
(ft2/cfm) 1000 cf) (%)
20 ( + )
10 (+)
10 ( + )
0
10 ( + )
93.4
97.3
96.6
97.9
88.8
065
065
065
063
064
26.47
26.51
26.21
25.48
26.07
10-1
Z 4 8 8 10° £ 4 6 8 101
PflRTICLE RERODYNRMIC DIRMETE.R. D50(MICRONS)
Fig. VI-1 Effect of Corona and Spray Voltage on Particle
Collection Efficiencies
27
-------
89.9
or
0- 99.0
u
UJ
8
UJ 90.0
O
-------
89.0
UJ 80.0
CJ
cr
a.
0.0
Test Corona V. Spray V. Overall
SCA L/G(gal/ Overall
No. (kV) (kV) Coll. Eff. (%) (fWcfm) 1000 cf) Pen.(%)
31
-32
35
u36
37
38
TOR
70 (-)
70 (-)
70 (-)
0
0
98.5
98.8
97.3
95.6
82.0
79.7
14.53
14.60
14.75
14.88
14.85
14.57
jcr1 2 4 e e too 2 4 e e iol
PflRTICLE RERODYNflMIC DlflMElER, D50(MICRONS)
Fig. VI-3 Effect of Charging Voltages on Particle Collection
Efficiencies
29
-------
88.8
0. 89.0
2
2
2 (-
2 (-
Test Corona V. Spray V. Overall SCA L/G(gal/ Over
No^ (kV) _(kV) Coll. Eff. (%) (ftz/cfrn) IQOOcf) Pen.(%)
98.5 .060 14.53 1.5
98.8 .060 14.60 1.2 "
98.0 .061 14.90 2.0
97.8 .063 15.21 2.2
31
'32
39
l
70 (-)
70 (-)
70 (-)
70 (-)
31
2 4 8 8 10° 2 4 8 8 10l
PflRTICLE flERODYNRMIC DIRMETER, D50(MICRONS)
Fig. VI-4 Effect of Charging Polarities on Particle
Collection Efficiencies
30
-------
89.9
S
(_>
a! 99.0
UJ
I
(_)
»-«
u_
o
UJ 80.0
OS
CC
Q_
0.0
TestCoronaV. SprayV. Overall SCA L/G(gal/ Overall
No. (kV) (kV) Con.Eff.(%) (ft2/cfm) 1000 cf) Pen.(
31 70 (-)
32 70 (-)
45 70 (-)
-51 70 (-)
2
2
2
2
98.5
98.8
97.8
96.5
.060
.060
.060
.059
10-1 2 4 6 8 10° 2 4 6 8 IQl
PflRTICLE flERODYNRMIC DIfl^ETER. D50(MICRONS)
Fig. VI-5 Effect of Liquid-to-Gas Flow Rate Ratio on
Particle Collection Efficiencies
31
-------
89.9
Test CoronaV. SprayV. Overall
No. (kV) (kV) Coll. Eff.
56
57
59
61
60
62
ft:
0. 89.0
SCA ' 'L/Gfgai/ Overal
(ft2/cfm) 1000 cf) Pen.(%
60TT
70 (-)
70 (-)
70 (-)
70 (-)
70 (-)
M+)
2 (+)
0
0
10 (+)
10 (+)
93.1
2 4 8 8 10° 2 488
PRRTICLE flERODYNRMIC DlflMETER, D50(MICRONS)
Fig. VI-6 Effect of Liquor Charging Voltages on Particle
Collection Efficiency of Spray Tower Number 2
32
-------
tests do not appear to correlate with the charging voltages. However,
the highest collection efficiencies for the submicron particles occurred
at the conditions of 70 kV on the corona and 10 kV on the liquor.
The particle collection efficiency as a function of particle size
with no charging voltages and the electrostatic mist eliminator turned
off is shown in Fig. VI-7. This test was conducted with both the spray
towers on with a total liquor flow of 11 gpm (L/G of 15.9 gal/1000 acf).
33
-------
99.9
Test Corona V. Spray V. Overall SCA L/G(gal/ Overall
No. (kV) (kV) Coll. Eff. (%) (ftVcfm) 1000 cf) Pen(%)
.67
0
0
68.5
.089
15.93
Q_ 89.0
80.0
04}
2 4 6 0 10° 2 4 6 8 101
PflRTICLE HERODYNflMIC DIflMETER. D50(MICRONS)
Fig. VI-7 Particle Collection Efficiency of Spray Towers
1 and 2 with Coronas and Mist Eliminator Off
34
-------
C. PARTICLE SIZE DISTRIBUTION MEASUREMENTS
Fig. VI-8 illustrates the reproducibility of two simultaneous
Mark 5 UW Cascade Impactor tests at the inlet to the Electrostatic
Scrubber. The particle size distributions are almost identical below
three micron diameter. The cascade impactors were located side by
side about three to five feet downstream of a 180 elbow and it is
possible for some particle size stratification to occur here. The gas
velocity in the duct was about 15 ft/sec during this test.
The inlet and outlet particle size distributions for the tests
illustrated in the collection efficiency plots (Fig. VI-1 to Fig. VI-7)
are presented in Fig. VI-9 to Fig. VI-21.
35
-------
oo
en
5.50
4
CD
Z
O
o;
o
UJ
CE
%
Q
UJ
O
CC
Q-
.01 .05.1 .2 .5 1 2
+
' +
64 Lognormal
65 Lognormal
64 Acutal
65 Actual
I I I I I II
5 10 20304050607080 90 95 9899 99.
PERCENTflGE SMflLLER (BY WEIGHT)
Fig. VI-8 Simultaneous Tests with Mark 5 UW Cascade Impactor at Inlet of Electrostatic
Scrubber Pilot Plant
-------
3.50
3
inG
_J ^
0 |
ii D
t- 7
£ 5
4
3
X
/£
.01 .05.1 .2 .5 1
^
a
X
n -
+
X
- u
- 18
- 19
- 20
- 21
10 20 30 40 SO 60 70 80 90 96 9899
PERCENTflGE SMflLLER (BY WEIGHT)
99.899.9 99.99
Fig. Ml-9 Inlet Particle Size Distributions for Tests 17, 18, 19, 20, and 21
-------
oo
oo
(O
DC
U
cr
H^
a
UJ
d
a:
cr
o_
9U
3
2
7
6
5
4
3
2
'8°
8
7
6
5
4
3
2
irt-1
/fa
Vf
.
<$
/ffi
' /
/
4
^r
y
/
/
Js
r y
/
f
t
f
^
/
/^
^ A
/ //
df
'S/
y
ffl^l
$2
V
\-
n i
-| 2
X 2
7
8
9
0
1
l" .01 .05.1 . 2 . 5 12 5 10 20304050607080 90 95 9899 99.899.9 99
PERCENTflCE SMflLLER (BY HEIGHT)
Fig. VI-10 Outlet Particle Size Distributions for Tests 11, 18, 19, 20, and 21
-------
00
'8'
8
7
6
5
I4
C£ -4
O 3
o: 2
LU
LU
o:
if
*"^ M.
I- 6
o£ 5
Q_
4
/>
I P^
y
/
a -
x
O
- 22
- 23
- 26
- 27
- 28
- 29
.01 .05.1 .2 .5 1 2
10 20 30 40 SO 60 70 80 80 86 8889
PERCENTflGE SMflLLER (BY WEIGHT)
89.889.8 99.99
Fig. VI-11 Inlet Particle Size Distributions for Tests 22, 23, 26, 27, 28, and 29
-------
8
7
6
5
O
oc «
0 3
V
UJ
cc
-
O 10°
3 7
~ 8
ry^ 5
Q_
4
3
w
s
A -
4-
X -
O
- 22
- 23
- 26
27
- 28
29
.01 .05.1 .2 .5 1
10 20304050607080 90 95
PERCENTRGE SMflLLER (BY WEIGHT)
88 89
89.899.9 89.99
Fig. VI-12 Outlet Particle Size Distributions for Tests 22, 23, 26, 27, 28, and 29
-------
8'
8
7
6
5
s «
o
CC q
cj 3
UJ
>
UJ
cr
x
_y /I
UJ
cc.
cc
Q_
///
-- 31
-- 32
- 35
36
-- 37
-- 38
10~.(M .05.1 .2 .5 1 2 5 10 20 30 40 SO 60 70 80 80 95 98 99 99.899.9 99.99
PERCENTflDE SMflLLER (BY WEIGHT)
Fig. VI-13 Inlet Particle Size Distributions for Tests 31, 32, 35, 36, 37, and 38
-------
f
7
6
5
CO
o
o
»
3C
LU
UJ
tr
If
O I
o;
cr
o_
-- 31
32
-- 35
-- 36
-- s?
38
.01 -05.1 .2 .5 1
10 20 30 40 50 60 70 80 90 95
PERCENTflGE SMRLLER (BY WEIGHT)
as
89.899.9 99.99
Fig. VI-14 Outlet Particle Size Distributions for Tests 31, 32, 35, 36, 34, and 38
-------
£.
,n\
J8
(O A
2 4
O
^ 4
o 3
1 1
3C
0
JIflMETER
\,
T
UJ o
H S
f R
1 8
£ S
CC 0
Q_
.r»-l
>
/
^
^
^
^/
y
/^
fl
y^
yW'
^^
y
^5^ >
^\X
JX
^
/
X
^
X
//
/
r/
/
X
/.
/f
V
1/1
X
^
yx .
// /
' /
S
^
/
P
r
J
/
^
r*
" 3
» " 3
-- 4
1
2
y
i
.01 .05.1 .2 .5 1 2 5 10 20 30 40 SO 60 70 80 90 95
PERCENTflGE SMRLLER (BY WEIGHT)
99 99.899.8 39-99
Fig. VI-15 Inlet Particle Size Distributions for Tests 31, 32, 39, and 41
-------
s
6
cr
z
8'
8
7
6
5
4
3
2
f\
8
1
8
5
4
3
irrl
^
y
/
/<
/
//
vx
//
X
X
/
~Jf~
1 /,
//
/
£
//
'
/
r
I
/
^
/
/
//,
P
y
V
)
//
Jf/
'/
A
S
P
c
c
£
-i
] - 31
) -- 32
S -- 39
- -- 41
ltr.01 .05.1.2.512 5 10 20304050607080 90 95 9889 99.899.9 99.99
PERCENTflDE SMflLLER (BY HEIGHT)
Fig. VI-16 Outlet Particle Size Distributions for Tests 31, 32, 39, and 41
-------
s
8
7
8
S
f //
CO
|
o
0£
UJ
UJ
111 A
d ?
s
//
n -- 31
O -- 32
A -- 45
+ -- 51
.01 .05.1 .2 .5 1 2
5 10 20304050607080 90 95
PERCENTRGE SMflLLER (BY HEIGHT)
89 99.899.8 89.
Fig. VI-17 Inlet Particle Size Distributions for Tests 31, 32, 45, and 51
-------
X
tni
18
CO A
g '
o 3
ta
9
KflMETER
L
UJ g
H 7
*- o
K- B
*
/
/
//
//
/ /
/
1
/
/j/
r
//
//
/
s /
//
f/
f
f/
r
i
/
^
/
^
//
//
P
/(
fi
$
//
//
''/
A
/
y
/
/
/
'
JL
/
r
^
-i-
] 3
\ "3
' -- O
k - 4
-- 5
1
2.
1
.01 .05.1 .2 .5 I
98 89
Fig. VI-18
10 20304050607080 80 85
PERCENTflOE SMflLLER (BY HEIGHT)
Outlet Particle Size Distributions for Tests 31, 32, 45, and 51
89.899.9 99.99
-------
-2>
§
±! 4
g
UJ
r:
CC
O
UJ
7
6
s
4
cr
a.
2
a
o
+
x
C>
-- 56
-- 57
-- 59
- 60
-- 61
- 62
X
10-1
.01 .05.1 ,2 .5 1 2 S 10 20 30 40 SO 60 70 80 90 35 98 88 99.899.9 99.88
PERCENTflGE SttflLLER (BY WEIGHT)
Fig. VI-19 Inlet Particle Size Distributions for Tests 56, 57, 59, 60, 61, and 62
-------
CO
CO
O
5 *
~ 3
UJ
uj 2
oc
»9
O
OE:
cc
a.
10-1
.01 .05.1 .2 .5 1
/*/
10 20304050607080 80 85
PERCENTflGE SMRLLER (BY WEIGHT)
a -
-f -
- 56
- 57
- 59
- 60
- 61
- 62
89.899.9 99.99
Fig. VI-20 Outlet Particle Size Distributions for Tests 56, 57, 59, 60, and 62
-------
PflRTICLE DIflMETER (MICRONS)
r\
D ro o> * cn co~JCOtoS N 01 * en CB-JCDCOO, rx
13
/
v
w
J
/s
'
/
/ ji
//
Y
/
/
/
/
/
-
/
/
/
/
j
/
f
/
/
/
/
?
/
s
/
/
s
in
s
/
/
/
1
D -- 67, Inlet
O -- 67, Outlet
.01 .05.1 .2 .5 1
10 20304050607080 90 9S
PERCENTflDE SMflLLER (BY WEIGHT)
8889
89.898.8 99.99
Fig. VI-21 Inlet and Outlet Particle Size Distributions for Test 67
-------
Section VII
REFERENCES
1. Pilat, M. J., S. A. Jaasund, and L. E. Sparks (1974) "Collection
of aerosol particles by electrostatic droplet spray scrubbers,"
Envir. Sci. & Tech. 8_, 340-348.
2. Pilat, M. J. (1975) "Collection of aerosol particles by electrostatic
droplet spray scrubber," APCA J. 25_, 176-178.
3. Pilat, M. J. and D. F. Meyer (1976) "University of Washington
Electrostatic Spray Scrubber evaluation," Final report on grant
no. R-803278, EPA report no. EPA-600/2-76-100 (NTIS no. PB
252653/AS).
4. Pilat, M. J. G. A. Raemhild, and D. L. Harmon (1977) "Fine particle
control with UW Electrostatic Scrubber," presented at Second
Fine Particle Scrubber Symposium, New Orleans, May 2-3, 1977.
5. Pilat, M. J., G. A. Raemhild, and D. L.. Harmon (1977) "Tests of
UW Electrostatic Scrubber at an electric arc steel furnace,"
presented at Conference on Particulate Collection Problems in
the Use of Electrostatic Precipitators in the Metallurgical
Industry, Denver, June 1-3, 1977.
50
-------
TECHNICAL REPORT DATA
(Please read Inunctions on the reverse before completing)
. REPORT NO.
EPA-600/7-78-177a
2.
3. RECIPIENT'S ACCESSION NO.
4. T.TLE AND SUBTITLE University of Washington Electrostatic
Scrubber Tests at a Steel Plant
5. REPORT DATE
September 1978
6. PERFORMING ORGANIZATION CODE
. AUTHOR(S)
M.J.Pilat, G.A.Raemhild, and A. Prem
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
University of Washington
Department of Civil Engineering, FX-10
Seattle, Washington 98195
10. PROGRAM ELEMENT NO.
EHE624A
11. CONTRACT/GRANT NO.
Grant R804393
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
Phase; 6/76-6/78
14. SPONSORING AGENCY CODE
EPA/600/13
15. SUPPLEMENTARY NOTEST£RL-RTP project officer is Dale L.
541-2925.
Harmon, Mail Drop 61, 919/
is. ABSTRACT
report gives results of a demonstration of the effectiveness of a 1700 cu
m/hr (1000 acfm) University of Washington (UW) Electrostatic Spray Scrubber in con-
trolling fine particle emissions from an electric -arc steel furnace. The two-stage
portable pilot plant operates by combining oppositely charged aerosol particles and
water droplets in two water spray towers. Aerosol charging sections (coronas) with
negative polarity precede each spray tower. Simultaneous inlet and outlet source
tests utilizing UW Cascade Impactors--Mark V for the inlet and Mark HI for the out-
letprovided both size-dependent and overall mass basis particle collection efficien-
cy information. Measured overall particle collection efficiencies ranged from 58. 8 to
99. 5%, depending on the electrostatic scrubber operating conditions and on the inlet
particle size distribution. Tabular and graphic data is presented illustrating the
effects of the corona specific plate area, liquid to gas flow rate ratio, magnitudes
of particle and droplet charging voltages , and electrostatic polarities on the overall
particle collection efficiencies and on the particle collection efficiency as a function
of particle size.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Pollution
Electrostatics
Scrubbers
Steel Making
Aerosols
Dust
Cooling Towers
Electric Corona
Impactors
Pollution Control
Stationary Sources
Electrostatic Scrubbers
University of Washington
Particulate
Water Droplets
Cascade Impactors
13B
20C
07A,13I
13H
07D
11G
13A
13. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report/
Unclassified
21. NO. OF PAGES
59
20. SECURITY CLASS (This page/
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
51
------- |