EPA/600/A-96/126
ADVANCES IN FINE PARTICLE CONTROL TECHNOLOGY
Wim Marchant and
Grady Nichols
Southern Research Institute
P.O. Box 55305
Birmingham, AL 35255 USA
Norman Plaks and
Charles B. Sedman
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
Research Triangle Park, NC 27711 USA
ABSTRACT
Currently the technologies of choice for the control of fine particle emissions from large
combustion sources are fabric filters and electrostatic precipitators (ESPs). As these two
technologies compete, advances in both technologies and their hybridization hold promise for
significantly reduced fine particle emissions from both new and existing sources. Recent
improvements in fabric filtration include flue gas additives and electrostatic augmentation.
ESP improvements include separation and optimization of particle charging and collection,
fast-rise time pulsed energization, and hybrid ESP/fabric filtration concepts. Mathematical
models which allow diagnosis of problems on existing systems and optimized design of new
systems are also discussed.
INTRODUCTION
Recent studies in the United States point to fine particles as being a major environmental
concern. These studies have focused on areas where the primary sources of ambient
submicron particles are combustion and metallurgical operations. If regulations to reduce fine
particle emissions are forthcoming, mandated additional control of combustion source particles
is possible.
In view of the perceived need for better fine particle control technologies, it is important to
review the more recent advances and their market status. Because the major combustion
sources of fine particles are almost wholly controlled by either electrostatic precipitation (ESP)
or fabric filtration (FF), the focus of this paper will be upon recent improvements and
innovations in these two technologies.
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NEW AND RETROFIT ESP IMPROVEMENTS
In recent years improvements in the ability to design new ESPs, upgrade existing ones,
and to diagnose ESP problems and apply cost-effective solutions have been realized through
the development of mathematical models for ESP simulation, simultaneous with the
development of personal computers. One noteworthy model, ESPV14.0, has been published
by the U.S. Environmental Protection Agency (EPA) and is available (in English) worldwide
for public domain use.1 With this model, the user can simulate practically any ESP and use its
output to assist in determining causes and potential solutions to poor performance, as well as
assist in design of new ESP's. A training course is being prepared under U.S. EPA guidance
for developing a core group of instructors which can train ESP operators in use of ESPVI4.0
in their native language. The first course to be taught will be to ESP experts from India.
Flue Gas Conditioning
The collection efficiency of an ESP is governed primarily by two characteristics of the
particles to be collected,size distribution and their electrical resistivity. The particle size
distribution exiting coal fired utility boilers is influenced by the coal, coal grind, combustion
conditions and, perhaps, particle agglomeration. The opportunity to promote particle
agglomeration in a typical flue gas stream prior to collection is quite limited because the
particles are separated by several diameters with a low probability for particle collisions.
There is a reasonable probability for agglomeration when the particles are collected as they
form a distinct layer on the collection electrodes. The tendency for particles to agglomerate
after collection (cohesivity) is related to the surface conditions of the individual particles.
Small particles adhere to other particles by van der Waals forces. Particles with rough
surfaces and those with surface layers of adhesive materials will tend to remain as
agglomerates when removed from the plates. Therefore, the amount of material reentrained
during rapping and from the normal vibrations associated with plant operation can be reduced
if the surface of the particles can be modified to result in a cohesive ash.
The electrical resistivity of the particles directly influences the electrical conduction
through the collected dust layer, and is the primary factor in the electrical behavior of the
ESP. During normal operation of the ESP, the corona system generates free electrons (in
negative corona) that quickly attach to electronegative gas molecules to form negative ions.
Some small portion of these ions attach to the particles to provide the charge for interacting
with the electrical field and being collected, while the remainder flow through the
interelectrode space through the dust layer to complete the electrical flow path.
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The flow of ions through the collected dust layer together with the applied voltage on the
system establishes an electric field in the collected dust layer. The electric field in the layer
can be expressed as the product of the electrical current density and the resistivity of the
particles:
E =jp
where E is the electric field, j is the current density, and p is the resistivity of the
collected dust layer.
When the resistivity of the particles is high, the electric field in the layer for a given current
density increases. When the electric field in the layer increases above some critical value, on
the order of 10 to 20 kV/cm, the field strength is sufficient to establish an electrical
breakdown in the gas residing between the dust particles analogous to the corona around the
discharge electrode. This electrical discharge in the layer limits the electrical operation of the
ESP. First, if the resistivity is in the intermediate range (mid 1QU ohm-cm) the breakdown
occurs when the applied voltage is sufficiently high to cause a spark to propagate across the
interelectrode space from the positive to the negative electrode. Repeated sparking causes the
automatic spark rate function to reduce the operating voltage to maintain the appropriate spark
rate. A reduction in operating voltage leads to a reduction in collection efficiency in the ESP.
Thus, the first limitation in performance from higher resistivity is sparking at reduced voltage.
If the resistivity of the particles is increased further to the high 10" or 1012 ohm-cm range,
the breakdown in the dust layer occurs at an operating voltage that is too low to propagate a
spark. For this condition, the electrical breakdown in the layer is sustained and grows across
the collected dust layer. This condition, termed back corona, generates positive ions across
the dust layer providing an additional ion source for electrical conduction in the ESP gas
stream. This positive ion conduction in addition to the negative ions from the corona electrode
causes the power supply to operate at high currents and low voltages with a severe limitation
on the collection efficiency of the ESP. The positive ions flow to the negatively charged dust
particles, leading to a net reduction in their charge and therefore a reduction in the collection
efficiency.
Sulfur Trioxide
The primary purpose for the use of flue gas conditioning is to reduce the electrical
resistivity of the particulate matter, to allow the ESP to operate at higher voltages and electric
field strengths. The most common flue gas conditioning agent for coal fly ash installations is
sulfur trioxide (S03). The electrical resistivity of fly ash is a function of the chemical
composition of the fly ash material; principally the concentrations of sodium, calcium, and
iron, and the temperature and composition of the flue gas. Usually the coal contains some
amount of sulfur in addition to the other customary constituents. When the coal is burned in
the furnace, the sulfur is converted to sulfur dioxide (S02). Some percentage of this S02 is
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further oxidized to S03 (somewhere around 0.5%), If the sulfur content of the fuel is greater
than about 1.5 to 2%, the native S03 is usually adequate to provide a resistivity in the
appropriate range for efficient collection.
When the natural sulfur is insufficient to provide the amount of conditioning needed, S03
can be generated at the plant site for injection into the gas stream prior to the ESP. The more
common conditioning system burns sulfur to generate S02 which is then passed through a
catalyst where approximately 96% is converted to S03. This gas stream is then injected into
the flue gas stream ahead of the ESP to provide a concentration of S03 that will reduce the
electrical resistivity of the fly ash particles to provide good electrical operating conditions.
The concentration of S03 required in the ductwork is on the order of about 10 parts per
million (ppm) for operating temperatures of about 150°C.
Ammonia
Ammonia has also been used for conditioning fly ash to improve ESP collection efficiency.
It has been used successfully for conditioning hot-side ESPs that have exhibited the "sodium
depletion" phenomenon that leads to the formation of a high resistivity dust layer that adheres
tenaciously to the collection electrodes until severe cleaning occurs. The severe cleaning can
be water washing, or either sand or wheat blasting. The mechanism by which ammonia
conditioning improves performance is not yet determined, but there is conjecture that the
ammonia molecule, which is electropositive, attaches to the positive ions generated in back
corona and reduces their influence on ESP performance. The action of ammonia when
injected is essentially instantaneous resulting in an immediate increase in operating voltage.
Reversal is also very fast after the ammonia is removed from the system.
Ammonia has also successfully reduced rapping reentrainment from a unit burning high
sulfur coal that generated a very low resistivity ash. The ammonia quickly combines with the
native S03 to form ammonium sulfate-bisulfate which is very "sticky." This "sticky" ash
helps to reduce ash reentrainment which occurs during rapping.
Combined Sulfur Trioxide and Ammonia
Both ammonia and S03 have been used in combination as conditioning agents. They have
been applied to a lignite ash that did not respond readily to conditioning with S03 alone. Upon
examination with an electron microscope, the appearance of the ash was very smooth (in
contrast with most ashes) and the interaction between the S03 and ash was minimal. The
combined injection of ammonia and S03 served as an effective conditioning agent, resulting in
a reduction in resistivity and causing the material to become more cohesive. This combination
of conditioning agents was successfully applied to fabric filter installations reducing both
"bleed through" and the pressure drop across the fabric/dust layer combination.
Ammonium Sulfate
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Ammonium sulfate has also been used as a conditioning agent. The net effect is
approximately the same as the co-injection of ammonia and S03. The material is injected at
temperatures of 350°C, which is sufficient to dissociate the ammonium sulfate. Once
dissociated, the constituents act as if they were injected separately.
Moisture
Moisture conditioning also effectively reduces the resistivity of fly ash. Water is injected
with two fluid nozzles with a size distribution and loading sufficient to humidify and cool the
flue gas to decrease particle resistivity while avoiding droplet impingement on surfaces. The
successful application.of moisture conditioning at a utility plant in the U.S. has provided the
motivation for other installations to consider this option2.
Sodium
Sodium conditioning can be effective in restoring proper electrical resistivity to fly ash that
is experiencing the development of high resistivity from sodium depletion. The application is
primarily for hot-side units where the sodium oxide content of the fly ash is usually less than
1 %. There is also the potential for use in cold-side units that may have very low amounts of
sulfur in the coal and sodium in the fly ash. Sodium carbonate, or other sodium bearing
compounds, is distributed on the coal prior to milling and fed into the furnace with the coal.
The amount of material that is customarily injected is that necessary to bring the equivalent
total sodium oxide concentration in the ash to about 1.5%.
Proprietary Agents
Proprietary conditioning agents have been marketed for several years. These materials
have been formulated to provide changes to specific characteristics of the particles to be
collected. These materials are sometimes combinations of some of the chemicals that are
described above with an additional compound added to provide a modification to some other
aspect of the particles. Ammonium sulfate and sodium compounds are common components
of proprietary conditioning agents.
One of the more recent developments for conditioning has been developed by ADA
Technologies in Englewood, Colorado. The material referred to as ADA-23 or FGC-23 was
developed under the sponsorship of the U.S. Department of Energy and ADA Technologies.
The material is reported to reduce the electrical resistivity of fly ash particles from both cold
side (150°C) and hot-side (300°C) precipitators as well as increasing the cohesivity of the ash.
The increase in cohesivity reportedly reduces the rapping reentrainment from the collecting
electrodes in the precipitators and will also improve the performance of fabric filters by
decreasing the pressure drop across the dust cake and reducing the particle penetration through
the fabric dust cake system. This additive is currently undergoing full scale tests in the U.S. It
is reported to effectively condition both eastern and western U.S. coal fly ashes3.
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Separation of Charging and Collection (Cold Pipe Precharging)
The cold pipe precharger (Figure 1) consists of a charging wire for high voltage and a pipe
for the ground electrode, through which cooled water is circulated. The concept is intended to
reduce the resistivity of dust collected on the cold pipe surface and achieve a very high level of
charge on the entrained dust particles in a very short distance along the direction of gas flow.
In laboratory, pilot and field pilot tests, the addition of cold pipe technology effectively
overcame the negative effects of back corona, and significantly improved collection efficiency
of ESPs operating with high resistivity dust.4,5
A simple application proposed for cold pipe technology is to minimize reentrainment
emissions. Because reentrainment dust typically represents 70% of particle mass emissions
from an ESP, and these emissions tend to be agglomerated into larger particles, placement of a
cold pipe section at the ESP exhaust results in significant ESP performance improvement.6
By placing prechargers in front of each collection section, this new ESP concept is referred
to as a multistage ESP. The high level of ESP performance by the multistage concept is
mainly due to the separation of the charging and collection functions, and the optimization of
each.
The SUPER ESP
The concept of the SUPER ESP (Figure 2) evolved from the multistage ESP by examining
the performance predictions of ESPVI4.0 for conventional and multistage ESP sections of
varying lengths and numbers of wires. As shown in Figure 3, a wire-pipe section containing 3
or 4 wires is capable of equal performance to that of a 7- or 8- wire conventional ESP section
for low resistivity ash, or to a 12- to 14- wire section for high resistivity. This implies that a
SUPER ESP can be constructed at one-half to one-fourth the size of conventional ESPs at the
same performance level. In summary, multiple pairs of individually energized prechargers
with short collector sections have replaced the long, individually energized sections of
conventional ESPs.
In addition to cost advantages due to a smaller ESP, another benefit of using SUPER ESP
is elimination of the need for flue gas conditioning.7,8
Electrical Energization
Historically the conventional precipitator power supply controls have been equipped with
current and voltage limits to protect the transformer-rectifier assembly and a spark rate
control to maintain as high an average operating voltage as possible. These controls attempted
to optimize the performance of each power supply independently. They were effective for
maintaining the operation of the ESP except the case of reverse ionization or "back corona"
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caused by collecting high resistivity particles.
The limitations in performance caused by back corona are associated with the formation of
positive ions in the dust layer on the collection electrodes. The current flow through the
collected layer establishes an electric field in the layer that is proportional to the product of the
resistivity and current density. When the electric field in the layer exceeds the electrical
breakdown field strength in the layer, a localized corona forms in the interstices of the dust
layer. For the case of negative corona, the back corona generates positive ions that flow into
the interelectrode space and tend to discharge the previously negatively charged particles,
reducing collection efficiency. In order for the power supply controls to function properly
with high resistivity dusts, an additional control parameter was needed.
Computer Based Control Systems
The development of the modern personal computer (PC) provides an additional capability
for power supply controls for ESPs. The computer can be programmed to search through the
various measured parameters and work to optimize performance based on items other than
those in conventional systems. The computer can identify the existence of back corona and
establish a current and voltage setting that would either avoid or minimize the influence of the
back corona. The shapes of the ¥-1 curve and the secondary voltage waveform provide the
information necessary to maintain the secondary current density at a level low enough to
minimize the deleterious effects of back corona.
The PC-based control system also provides the opportunity to use non-conventional
energization techniques. The Mitsubishi Company in Japan has developed an approach to
energization that they term "Intermittent Energization." In intermittent energization the
rectifier circuit is programmed to pass one or two half cycles of energization and then skip
some number of cycles. The computer searches through a number of alternatives to determine
the appropriate number of cycles to energize and the number to skip to maintain the maximum
value of the average voltage with a current density low enough to avoid back corona. This
capability exists in almost all PC-based control systems.
Pulse Energization
Pulse energization provides a high operating voltage with a low average current density
and provides for a more nearly uniform current density distribution on the collection
electrodes. Conventional negative corona consists of individual tufts of corona distributed
along the corona electrode, while positive corona is very uniformly distributed over the corona
electrode. The more uniform corona causes a more nearly uniform current distribution on the
collection electrode. If the voltage waveform used for energization has a very fast rise time,
on the order of a few microseconds, the negative corona exhibits the appearance of positive
corona. The entire corona electrode glows uniformly, rather than developing the tufts
characteristic of fully developed negative corona. A typical pulse energization system will
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operate with pulse voltages on the order of 100 kV rather than the 50 kV value expected for
conventional energization. The pulse repetition rate is set to provide an operating current
density low enough to avoid the formation of back corona.
HYBRID FABRIC FELTRATION/ESP
COHPAC I and COHPAC II
The Electric Power Research Institute has developed an upgrade retrofit technology for
utility installations operating with an ESP currently not meeting the U.S. New Source
Performance Standards (NSPS) for atmospheric discharge of any gases which contain
particulate matter in excess of 13 ng/J (0.03 lb/106 Btu) heat input derived from the
combustion of solid, liquid, or gaseous fuel. The technology can be applied to an older
installation installed before the new emission limits were required, or one meeting NSPS for
particulate matter, but for which changing the fuel supply to a low sulfur coal to meet the S02
emission limits is being considered. The technology is known by the acronym COHPAC,
from CQmpact Hybrid PArticle Collector.9 The retrofit installation consists of a pulse jet
fabric filter system operating at very high gas-to-cloth ratios to remove the uncollected
particles that pass through the lower efficiency ESP.
The less than optimum operating ESP is expected to provide collection efficiencies in the
high 90% range with outlet particulate emissions on the order of 43 to 86 ng/J (0.1 to 0.2
lb/106 Btu). Thus the ash loading into the COHPAC unit is low. This low loading allows the
pulse jet fabric filter to operate at very high face velocities without rapidly developing a very
thick dust layer on the fabric filter material10. In addition, the particles that are to be collected
are electrically charged, having previously passed through the ESP. Electrically charged
particles form highly porous dust layers in fabric filters9 that exhibit very low pressure drops
for a given dust loading. The particle loading and dust layer characteristics provide the
conditions for effective operation of a relatively small pulse jet fabric filter.
Two versions of COHPAC are in various stages of development. COHPAC I involves the
installation of the fabric filter assembly downstream from the ESP in a separate structure. The
original ESP remains in its normal condition and the COHPAC I assembly is added. Pilot
scale testing of this concept has been conducted1112 and the results of these pilot tests indicate
that COHPAC I will operate reliably with face velocities of 3 to 3.6 m/min (10 to 12 ft/min).
The COHPAC I concept has been pilot scale tested at a large utility. The favorable test
results guided the utility to a decision to install a full scale COHPAC I unit at that site. The
station is equipped with hot-side ESPs that have been in operation since the late 1960s. The
COHPAC I retrofit is currently in progress and scheduled to be completed by December 1996.
A second version of the technology is known as COHPAC II. In this variation, the outlet
field of the existing ESP is removed and replaced with the internals of a pulse jet fabric filter.
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This installation should be somewhat less expensive to build than COHPAC I and lends itself
to installation in power stations without available spare to construct a fabric filter. The
COHPAC II arrangement results in placing a greater particulate loading on the fabric filter
assembly, which may limit the allowable face velocity and increase the required cleaning
frequency of the unit. An existing EPRI pilot scale ESP was converted to the COHPAC II
configuration for testing on a slip stream from a pulverized coal boiler. The unit operated
very well on both U.S. eastern bituminous and Powder River Basin sub-bituminous coals'3.
Electrostatically Stimulated Fabric Filtration (ESFF)
Fabric filtration, in the form of baghouses, is a major technology in the control of particle
emissions. The two categories of baghouses, shown in Figure 4, are the reverse air (inside to
outside flow) and pulse-jet (outside to inside flow). Because of the ability to handle higher gas
volumes for a given bag surface area, pulse-jet fabric filters have become more popular. Dust
is emitted from baghouses due either to leaks, holes in the fabric or improper seals between
the bag and bag support cage; or to penetration of the fabric by a particle. Another negative
aspect of fabric filtration is the high pressure drop across the dust cake, compared to that of
ESPs.
Previous work in the application of electrostatics to improve fabric filter performance
included charging particles prior to collection, collecting particles in an electric field, and
combining charging and collection.14 Most efforts reported significant pressure drop
reduction. Recent work by the U.S. EPA has hybridized ESP and fabric filtration with the
two concepts shown in Figures 5 and 6. Figure 5 shows a conventional reverse-air baghouse
which has:(l) corona discharge wires axially inside each bag, (2) bag fabric made somewhat
conductive by adding conductive fibers to the woven bag, and (3) an electric field developed
between the electrode and bag surface by a conventional ESP power supply.15
Figure 6 shows the same principles applied to a pulse-jet baghouse, wherein the corona
wire is located at the centerline of each four-bag array, within the baghouse, external to the
bags. An innovation involves placing a pulse-jet ESFF array within the last section of an ESP,
shown in Figure 7. Mathematical models developed on bench-scale data indicate that this
concept can improve ESP efficiency by increasing particle capture and reducing fabric
penetration, by greater than 90% over base performance with the pressure loss of 10 to 30%
of a fabric filter.16
CONCLUSIONS
A number of promising new concepts have been identified which promise to improve
performance and cost-effectiveness of current technologies. Hybrid fabric filter/ESP concepts
have the most potential to lower emissions of fine particles significantly.
REFERENCES
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1. Lawless, P.A..ESPVI4.0 Electrostatic Precipitator V-I and Performance Model: User's
Manual, EPA-600/R-92-104a,(NTIS PB92-169614), U.S. Environmental Protection
Agency, Research Triangle Park, NC, June 1992.
2. Reinhold, Susan D., Clear Stacks; Reinhold Environmental, May 1996.
3. Durham, Michael D., et al., Full Scale Demonstration of Novel Flue Gas Conditioning
Agent for Enhanced Toxic Particulate Control, Air & Waste Management Assoc. 89th
Annual Meeting, Nashville, TN, June 23-28, 1996.
4. Rinard, G., et al., "Development of a charging device for high-resistivity dust using
heated and cooled electrodes," in Proceedings, Third Symposium on the Transfer and
Utilization of Particulate Control Technology, vol. II, EPA 600/9-82-005b(NTIS PB83-
149591), pp 283-294, July 1982.
5. Yamamoto, T., et al., "Evaluation of the cold pipe precharger," IEEE Transactions of
Industry Applications, G24 No. 4, July/August, 1990, pp 639-645.
6. Mosley, R.B., et al., "Electroprecipitator with suppression of rapping reentrainment,"
U.S. Patent No. 4,822,381 (1989).
7. Plaks, Norman, "The SUPER ESP - Ultimate Electrostatic Precipitation," in
Proceedings: 1991 Symposium on the Transfer and Utilization of Particulate Control
Technology, Electric Power Research Institute, 1992.
8. Plaks, N. and Sparks, L.E., "Electroprecipitator with alternating charging and short
collector sections," U.S. Patent No. 5,059,219 (1991).
9. Lamarre, Leslie, COHPing with Particulates, EPRI Journal Jul/Aug 1993. Electric
Power Research Institute, Palo Alto, CA.
10. Chang, Ramsay L., COHPAC Pilot Tests; E C Update, EPRI Summer 1995 m.
11. Harrison, Wallis A., Kenneth Cushing, and Ramsay Chang, Pilot Scale Demonstration
of a Compact Hybrid Particulate Collector for Control of Trace Emissions and Fine
Particles from Coal Fired Boilers; EPRI/DOE International Conference on Managing
Hazardous and Particulate Air Pollutants, Toronto, Canada, 1995.
12. Bustard, C. Jean, et al., Experience With a 145 Megawatt COHPAC Demonstration,
EPRI/DOE International Conference on Managing Hazardous and Particulate Air
Pollutants, Toronto, Canada, 1995.
13. Harrison, Wallis A., Kenneth Cushing, and Ramsay Chang, Pilot Scale Demonstration
10
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of a Compact Hybrid Particulate Collector for Control of Trace Emissions and Fine
Particles from Coal Fired Boilers; Power Gen America, Orlando,FL, 1994.
14. Frederick, E.R., "How Dust Filter Selection Depends on Electrostatics." Chemical
Engineering 68 (1961) p. 107.
15. Plaks, Norman and Daniels, Bobby E., "Advances in Electrostatically Stimulated Fabric
Filtration," in Proceedings: Seventh Symposium on the Transfer and Utilization of
Particulate Control Technology,Volume 2, EPA-600/9-89-046b (NTIS PB89-194047),
May 1989.
16. Plaks, Norman and Sedman, Charles B., "Enhancement of electrostatic precipitation
with electrostatically augmented fabric filtration," U.S. Patent No. 5,217,511 (1993).
11
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Precharger section
Collector section
Figure 1. ESP Section with Cold Pipe Precharger
-------
Cold Pipe.
Precharger
\Wire Plate
v Collector
Gas Flow
Figure 2. Multi-Stage Electrostatic Precipitator
13
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0.7
0.6-
Low resistivity
High resistivity
0.5-
c
o
(Low resistivity)
03
0
c
0
CL
(High resistivity)
0.3-
0.2-
¦01
tr
Electrodes in conventional ESP section
(electrodes in SUPER ESP module collector section)
Figure 3. Predicted Super ESP and Conventional ESP Performance
-------
' REVERSE OR
SHAKER DRIVE DEFLATION GAS
MECHANISM n
(OPTIONAL! X
o
INLET
GAS
A
CLEAN ^
FILTER BAG
-THIMBLE
DiRTV
FLUE GAS "R
TUBE SH££T
HOPPER
MATERIAL DISCHARGE
——-*«a — ¦ ¦>¦ ¦- ¦¦"¦
«» Oi c*s
^SSH,
fcswc
C-> iJAfcj w
•rr -oln ?r
' V-3 v>;.;
COMPRESSED
AIR
. MANIFOLD
• TUBE SHEET
VENTURI
NOZZLE
FILTER BAG
METAL CAGE
HOPPER
MATERIAL DISCHARGE
INSIDE OUT
OUTSIDC IN
Figure 4, Reverse Air and Pulse Jet Baghouses
-------
Spring
To High Voltage
Power Supply
Outlet
Insulators
High Voltage
Power Supply
Corona Discharge
Electrode
Conductive Filter
Cell Plate
— Inlet
Weight
Figure 5. Electrostatically Augmented Reverse Air Baghouse
16
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Insulator
Outlet
ia.
Cell
Plate
Grounded
Wire Cage
Filter
Corona Discharge
Electrode v
Cell
Plate
OO
©
OO
Grounded
Wire Cage
Inlet
Top View
High Voltage
Power Supply
Figure 6. Electrostatically Augmented Pulse Jet Baghouse
17
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00
1. PARTICLE LADEN GAS
2. ESP FIELDS
3. EXIT DUCT
4.' INLET DUCT
5. INLET TRANSITION SECTION
6. ESP HOUSING
7. T/R UNITS
8. DIFFUSION PLATES
j
9. TUBE SHEET
10. T/R POWER SUPPLY
11. ESFF SECTION
12. PLENUM
13. OUTLET TRANSITION SECTION
14. BAFFLE PLATE
15. ESFF HOPPER
16. ESP HOPPERS
Figure 7. Hybrid ESP/ESFF
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,TDMDt „Tn n ,,n TECHNICAL REPORT DATA
IN i% 1VIK J-.- K1 1~ 1 loo (.Please read Instructions on the reverse before completin
1. REPORT NO. , 2.
EPA/600/A-96/126
3. R
4, TITLE AND SUBTITLE
Advances in Fine Particle Control Technology
5, RLpum I UAIC
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
W. Marchant and G. Nichols (SoRI), and N. Plaks
and C. B. Sedman (EPA)
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND AOORESS
Southern Research Institute
P. O. Box 55305
Birmingham, Alabama 35255
10. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
CR 822780 (SoRI)
12. SPONSORING AGENCY NAME ANO ADDRESS
EPA, Office of Research and Development
Air Pollution Prevention and Control Division
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVEREO
Published paper; 6-9/96
14. SPONSORING AGENCY CODE
EPA/600/13
1LT^NT^VN°TE!A/^Cr?? project officer is Charles B. Sedman, Mail Drop 4. 919/
541-7700. Presented at Ukraine-U.S. Technology Meeting. Kiev, Ukraine, 9/10-
11/96.
16. abstractThe paper discusses advances in fine particle control technology. Currently,
the technologies of choice for controlling fine particle emissions from large combus-
tion sources are fabric filters and electrostatic precipitators (ESPs). As these two
technologies compete, advances in both technologies and their hybridization hold
promise for significantly reduced fine particle emissions from both new and existing
sources. Recent improvement in fabric filtration include flue gas additives and elec-
trostatic augmentation. ESP improvements include separation and optimization of
particle charging and collection, fast-rise time pulsed energization, and hybrid ESP/
fabric filtration concepts. Mathematical models which allow diagnosis of problems
on existing systems and optimized design of new systems are also discussed.
17. KEY WORDS AND DOCUMENT ANALYSIS
a. DESCRIPTORS
b.lDENTIFIERS/OPEN ENOED TERMS
c. cosati Field/Croup
Pollution Mathematical Models
Particles Flue Gases
Combustion
Filters
Fabrics
Electrostatic Precipitators
Pollution Control
Stationary Sources
Particulate
Fabric Filters
13 B 12 A
14G
21B
he
131
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (This Report)
Unclassified
21.NO. OF pages
20. SECURITY CLASS {This page/
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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