United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S9-82-005a Aug. 1983
Project Summary
Third Symposium on the
Transfer and Utilization of
Paniculate Control Technology:
Volume I. Control of
Emissions from Coal-Fired
Boilers
F. P. Venditti, J. A. Armstrong, and M. Durham
Summarized herein is Volume I of the
four volumes of proceedings of the
Third Symposium on the Transfer and
Utilization of Particulate Control Tech-
nology held in Orlando, FL, March 9-12.
1981. Volume I papers discuss control
of emissions from coal-fired boilers.
Most of the papers deal with fabric
filters and electrostatic precipitators
(ESPs); also discussed are dry SOZ
scrubbers and conventional scrubbers.
Volumes II, III, and IV are described in
three separate project summaries.
This Project Summary was developed
by EPA's Industrial Environmental Re-
search Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering infor-
mation at back).
Introduction
The papers in Volume I of the four
volumes of proceedings were presented
at the Third Symposium on the Transfer
and Utilization of Particulate Control Tech-
nology in Orlando, FL, March 9-12,1981,
sponsored by the Particulate Technology
Branch of EPA's Industrial Environmental
Research Laboratory at Research Triangle
Park, NC.
The symposium brought together re-
searchers, manufacturers, users, govern-
ment agencies, educators, and students
to discuss new technology and provided
an effective means forthe transfer of this
technology out of the laboratories and
into the hands of the users.
The three major categories of control
technologies—electrostatic precipitators
(ESPs), scrubbers, a nd fabric filters—were
the major concern of the symposium.
These technologies were discussed from
the perspectives of economics, new tech-
nical advancements in science and engi-
neering, and applications. Several papers
dealt with combinations of devices and
technologies, leading to a concept of
using a systems approach to particulate
control, rather than device control. Addi-
tional topic areas included novel control
devices, high-temperature/high-pressure
applications, fugitive emissions, and
measurement techniques.
The symposium was conducted as a
series of parallel sessions, each contain-
ing four to six related papers. The sessions
were scheduled to avoid conflict due to
simultaneous sessions dealing with the
same topic. Each series of related ses-
sions represented a thread of technology.
These parallel threads, extending over
the total period of the symposium, pro-
vided a highly integrated approach to the
total subject of particufate control tech-
nology, with strands of specialized tech-
nologies. These strands of specialized
technologies, or perspectives, provided
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the basis for the division of the papers
into four volumes, each volume contain-
ing a set of related session topics so as to
provide easy access to a unified tech-
nology area.
Volume I Papers
Volume I, summarized here, consists of
papers dealing with the control of emis-
sions from coal-fired boilers. One section
of Volume I deals with fabric filters and
covers the characterization, or modeling,
of a fabric filter, operating experiences
with fabric filters on coal-fired plants,
electrostatically augmented fabric filters,
and pulse jet filtration under conventional
and electrostatic-charge conditions. The
second section of Volume I is dedicated to
the use of ESPs. It covers two-stage ESP
demonstrations and evaluations, resistiv-
ity studies, pulse-energized ESPs, and
conditioning to improve hot- and cold-
side ESP performance. The third section
of this volume deals with dry SOz scrub-
bers and treats dry injection, two-stage
cleaning, and the applications of SOj
scrubbing in bag house systems. One
paper was devoted to the use of a venturi
scrubber and the operating experiences
encountered.
Section A—Fabric Filters
Coal Properties and Fly ash
Filterability
R. Dennis.
GCA Corporation Technology Division
The results of a survey of U.S. coal
sources, types, compositions, production,
and use are described. Coals most likely
to be burned in applications where fabric
filters are used were identified. Physical
and chemical properties of these coals
and their mineral constituents were
evaluated for potential impact on resul-
tant flyashes. Several ASTM criteria
commonly used to delineate coal fouling
and slagging properties were examined
for probable impact upon flyash size and
surface properties. Consideration was
also given to the method of coal combus-
tion, operating temperatures, fusion and
hardness properties of mineral constitu-
ents, and slag viscosity as possible factors
in determining flyash filtration character-
istics. High alkalinity contents were ex-
amined for their potential to increase
flyash gas and moisture absorption. A
major purpose of the survey was to pro-
vide a rationale for selecting represen-
tative flyash samples for laboratory deter-
mination of the specific resistance coef-
ficient (((2) and the cleaning parameter
(ac).
Pulse-Jet Filtration with
Electrically Charged Flyash
R. P. Donovan,
Research Triangle Institute
Pulse-jet performance equations differ
from those of reverse-air cleaned or
shaker baghouses, especially when oper-
ated at high air-to-cloth ratios, as has
been described by Leith, Ellenbecker,
Dennis, and others. These differing per-
formance equations imply that dust elec-
trical charge should influence pulse-jet
performance differently than, say, shaker-
baghouse performance. Measurements
exploring this prediction are presented
and the observed performance effects of
dust electrical charge are interpreted in
terms of contemporary pulse-jet models.
Comparisons with the shaker baghouse
are emphasized.
Electrically Charged Flyash
Experiments in a Laboratory
Shaker Baghouse
L S. Hovis. USEPA
As has been demonstrated for numer-
ous dust/fabric systems, increasing the
electrical charge of the dust particles
dramatically reduces the K2 values of the
dust cake formed by such particles. This
demonstration has been repeated in a
room-temperature-operated shaker bag-
house, using redispersed flyash from
Southwestern Public Service with sili-
cone-graphite finished fiberglass bags.
The observed dependencies of this effect
on operating time and relative humidity
are presented.
Prolonged operation with a charged
flyash gas stream at 50% relative humidity
causes the low K2 values, characteristic
of highly charged dust, to gradually
increase to the range characteristic of
uncharged dusts. Increasing the opera-
ting relative humidity to 70% rapidly
restores the low Ka operation. These
observations are interpreted in terms of
flyash electrical resistivity and its role in
electrically enhanced dust filtration.
Electrostatic Augmentation of
Fabric Filtration
D. VanOsdell. Research Triangle Institute
The performance of fabric filters can be
substantially improved through the use of
an electric field parallel to the collector
surface. The field is created by parallel
wires adjacent to the fabric, with alter
nating electrical polarity and relatively
high potentials. The electric field leads tc
improved collection efficiency and a modi-
fied dust cake which has a lower resis-
tance to gas flow.
A project team composed of RTI, ETS,
and TRI, under the sponsorship of EPA,
reports on the process at pilot scale,
utilizing a slipstream from a coal-fired
boiler. This paper discusses the design
and implementation of the pilot unit, test
methods and results, conclusions, eco-
nomic projections, and future plans for
this continuing study.
Fabric Wear Studies at
Harrington Station
R. Chambers,
Southwestern Public Service Co. (SPS)
SPS, among several other utilities,
conducted a fabric evaluation program in
conjunction with an EPA study at its
Harrington Station. This paper discusses
SPS's experience with fabrics and some
of the conclusions that have been drawn
from (1) the use of systematic physical
testing on fabrics to monitor fabric wear
and eventually predict fabric life, (2) an
analysis of fabric wear mechanisms at
Harrington Station, (3) results of individ-
ual compartment throughput measure-
ments for various fabrics, and (4) fabric
failures by compartment position.
SPS Pilot Baghouse Operation
W. Hooks,
Southwestern Public Service Co.
In 1977, EPA contracted with SPS to
assess the performance of a large fabric
filter system used on a new utility boiler
burning low sulfur Western coal. One
option provided for the installation of a
pilot filter system on-stream with
Harrington Station Unit 2. This paper
outlines the overall objectives of the pilot
unit program. In addition, proper system
design, problems in start-up and opera-
tion, and a fabric evaluation program are
discussed.
A Review of SPS
Investigation of Harrington
Unit 2 Fabric Filter System
K. Ladd,
Southwestern Public Service Co.
For the last 3 years, SPS has tested and
monitored the Harrington Station Unit 2
fabric filter system to characterize its
operation. The unit was one of the first
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large air quality control devices to be used
in association with a low sulfur, coal-fired
boiler. This paper reviews the start-up,
monitoring, testing, and operation of the
fabric filter system since an EPA spon-
sored program began in October 1977.
Numerous operation and maintenance
problems encountered in the first year of
the program are discussed. Also, a sum-
mary of the extensive flue gas and panic-
ulate sampling performed by both SPS
and GCA in an effort to characterize the
baghouses is presented.
A Summary of Performance
Testing of the Apitron
Electrostatically Augmented
Fabric Filter
D. J. Helfritch, Apitron
The Apitron filter is currently the only
commercially operating electrostatically
augmented fabric filter. As such, it has
been intensively investigated by industry
and governmental agencies over the past
several years. A large amount of perform-
ance data has been gathered. Following a
brief description of Apitron operating
principles, these data are reviewed and
compared for consistency. General con-
clusions are drawn from the data regard-
ing performance improvements which
result from electrostatic augmentation.
These conclusions are compared to those
predicted by available theory.
Fabric Filter Operating
Experience from Several Major
Utility Units
0. Fortune, Buell Envirotech Corp.
This paper presents operating experi-
ence with several reverse-air fabric filter
units operating with pulverized-coal and
cyclone-type boilers. Start-up experience
with different firing techniques (coal, oil
assist, gas) is presented.
Field pressure drop data are correlated
with a model. This field correlation dem-
onstrates the dependence of pressure
drop on the flyash particle size distribu-
tion, grain loading density, cleaning, and
air-to-cloth ratio. This model explains the
high pressure drop experienced by some
units on lignite coal. The impact of alterna-
tive cleaning cycles upon pressure drop is
compared based on modeling. The impact
of various cleaning cycles on pressure
drop is verified by field test data.
Flyash particle size distributions from
various compartments and within com-
partments are compared for a few units to
investigate industry's conjecture of vari-
able particle size in different compart-
ments.
Evaluation of the 25 MW
Kramer Station Baghouse:
Trace Element Emission
Control
M. W. McElroy.
Electric Power Research Institute (EPRI)
This paper describes a major EPRI
research program characterizing the
emission control performance of fabric
filter baghouses in coal-fired utility boiler
applications. An integra'l part of this
program is the determination of particu-
late matter chemical composition and
collection. The effort reported here is an
evaluation of the Kramer Station bag-
houses of the Nebraska Public Power
District. These units represent the first
application of fabric filter control technol-
ogy to pulverized-coal-fired utility boilers
burning a western, low-sulfur, subbitu-
minous coal.
The collection efficiency of over 35
individual trace elements was essentially
equivalent to that of total mass. Size-
dependent chemical analysis for nearly
30 elements over a 0,50-10//m diameter
size range further reveals that the vast
majority of elements exhibit penetration
profiles remarkably similar to total mass.
A notable exception was selenium, which
exhibited much higher penetration. Inlet
size distributions indicated fine particle
enrichment for several elements relative
to the matrix elements. This behavior was
still evident at the outlet of the baghouse,
despite very low outlet emissions.
Characterization of a 10 MW
Fabric Filter Pilot Plant
R. C. Can,
Electric Power Research Institute (EPRI)
EPRI is conducting a baghouse pilot
plant program to define design and oper-
ating parameters which will improve the
reliability, economics, and collection effi-
ciency of fabric filters. This paper reports
results of the air-load and start-up tests.
Air-load test results include the effects of
hopper inlet design on the gas flow distri-
bution and dust stratification in the inlet
duct, hopper region below the tube sheet,
and through the tube sheet from bag to
bag. In addition, data are reported illus-
trating the reverse-air-flow distribution
from bag to bag, and the re-entrainment
of dust from the hoppers under several
inlet-flow conditions. Start-up test results
show the effects of bag precoat, cleaning
method and cycle, and gas/dust flow
distributions on operating pressure drop
and particulate matter penetration.
Specifying a Fabric Filter
System
R. L Ostop, City of Colorado Springs
Fabric filtration is emerging as an
alternative to hot-side precipitators and
flue gas conditioning for control of flyash
from low sulfur coal. With the new appli-
cation of this old technology, fabric filter
baghouse applications have resulted in
many successes; and in some instances,
systems that were not so successful. This
paper presents the basic information
needed to specify a fabric filter system
that will provide cost-effective operation.
The discussion includes the conceptual
requirements for specifying such param-
eters as air-to-cloth ratio, pressure drop,
by-pass capability, inlet and outlet valve
requirements, pneumatic and electronic
control systems, and emergency control
instrumentation.
Evaluation of the 25 MW
Kramer Station Baghouse:
Operational Factors in
Particulate Matter Emission
Control
R. C. Carr,
Electric Power Research Institute (EPRI)
The effort reported here is an evaluation
of emission control performance of the
Kramer Station baghouse of the Nebraska
Public Power District. Results show that
the baghouse cleaning cycle had the
greatest effect on particulate matter
removal efficiency compared to any other
operational parameters. Implementation
of a "preferred" 100-minute cleaning
cycle, obtained by extending the time
between compartment cleaning from zero
to 8 minutes, reduced particulate matter
penetration by 50% without an increase
in pressure drop. Total particulate matter
collection efficiency measured for the
baghouse with the preferred cycle in
effect averaged 99.93%, with associated
outlet emissions and stack opacity of
0.002 lb/106 Btu and 0.07%, respectively.
In addition, the baghouse size-dependent
mass collection efficiency exceeded 99%
over the 0.02-10 ;um size range.
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Pulse-Jet Type Fabric Filter
Experience at Air-to-Cloth
Ratios of 5 to 1 on a Boiler
Firing Pulverized Coal
G. L. Pearson, Adolph Coors Co.
Since November 1979, a modular bag-
house of Carter-Day design has been in
operation controlling emissions from the
Boiler No. 5 pulverized-coal-fired unit
rated at 450,000 Ib/hr. Bags are made of
felted Ryton and are cleaned using the
pulse-jet technique.
An overview of the system and opera-
ting experience with this 12 module unit
is presented. Data on outlet particulate
emission, pressure drop, cleaning cycles,
and cleaning frequency are reviewed.
Selection and Operation of
Baghouses at P. D. Nixon
Station, Unit 1
R. C. Hyde, Joy Industrial Equipment Co.
This paper discusses the selection
criteria and the subsequent successful
operation of two baghouses which have
been in continuous service since April
1980, at the R. D. Nixon Station, Unit 1,
servicing a 220 MW boiler.
The paper identifies the specification
criteria deemed most important for a
successful baghouse installation and
reviews the architect's decision-making
process in selection of this type of air
pollution control equipment. Results from
the first 6 months of operation are
presented, including pressure drop, opac-
ity, and outlet emission. To date, the unit
has operated with low outlet emissions
and low-pressure drop (3-4 in., W.C.).
Additionally, start-up, shutdown, and
maintenance procedures are discussed.
Potential for Improvement in
Baghouse Design
R. Jensen, Bechtel Power Corp.
This paper describes design deficien-
cies of large, structural, reverse-air bag-
houses of the type now being applied to
remove flyash from large coal-fired power
plants. Analyses, curves, and data show
that some of the currently acceptable and
recommended design details cause un-
necessary pressure loss, increase the
energy required for cleaning, and de-
crease bag life. The paper also demon-
strates that cloth ratio has no real mean-
ing: it is nothing more than a sizing
parameter and, in fact, actual cloth ratios
exceed the design cloth ratio. The con-
sequences of the design deficiencies are
more important to the utility industry than
to industrial users because of the differ-
ences in evaluation methods. Correction
of the deficiencies would be of value to
both.
Review of Operating and
Maintenance Experiences with
High-Temperature Filter
Media on Coal-Fired Boilers
L K. Crippen and H. H. Forsten
E. I. DuPont de Nemours & Co.
Operating and maintenance procedures
which can affect bag life and performance
at high operating temperatures in dry gas
filtration are reviewed using case his-
tories for Teflon and Nomex fibers in a
variety of applications. Maintenance ex-
periences are examined from both a
preventive and a problem-solving orienta-
tion. Operating problems and their solu-
tions are included. Bag refurbishment is
outlined-. The review of experiences on
full-scale coal-fired industrial boiler appli-
cations using Teflon fiber includes an
installation in operation for more than 5
years.
Section B—Electrostatic
Precipitators
Pilot Demonstration of the
Precharger-Collector System
P. V. Bush, Southern Research Institute
Results from the evaluation of a 1000
acf m pilot scale precharger-collector sys-
tem in September 1979, justified the
development of a larger scale two-stage
ESP system. A pilot demonstration system.
with a 30,000 acfm gas volume capacity
was designed, fabricated, and installed at
TVA's Bull Run steam plant. Continuous
monitors interface to a computer/data
acquisition system to provide real-time
mass efficiency, outlet particle-size distri-
bution, SOz concentration, and ESP vol-
tages and currents. These measurements
are supplemented with standard stack
sampling techniques for selected ESP
conditions. Start-up information and pre-
liminary data are presented.
Remedial Treatments for
Deteriorated Hot-Side
Precipitator Performance
R. E. Bickelhaupt,
Southern Research Institute
Adding a sodium compound to the coal
feed of a steam generating system with a
poorly operating hot-side ESP greatly
improved the performance of the ESP
This report describes laboratory work
conducted to: (1) re-create and examine
the conditions prevailing when the hot-
side ESP was in a deteriorated condition,
(2) substantiate earlier evidence for the
sodium depletion hypothesis, and (3)
determine the effect of the sodium addi-
tion and the mechanisms whereby sodi-
um addition is beneficial.
The data show that 1 X 1010 ohm cm
resistivity ash can develop high resistivity
(1 X 1012 ohm cm) when held for a long
time under electrical stress on a collection
plate. Furthermore, it has been confirmed
that the sodium concentration in the thin
film of ash contiguous to the collection
electrode is reduced. The circumstantial
evidence suggests that conditioned ash
acts as a source of sodium that diffuses
toward the sodium depleted zone under
the influence of the concentration gradi-
ent.
Evaluation of the United-McGill
Electrostatic Precipitator
D. S. Ensor, Research Triangle Institute
A United-McGill ESP installed on an
industrial coal-fired boiler was field
tested. Included in the testing were
measurements of particle-size distribu-
tion from 0.05 to 10 ^m, opacity, charge-
to-mass concentration, mass concentra-
tion, resistivity, and plant parameters.
The particle-size dependent efficiency,
rapping losses, and power requirements
are reported for the unit. A mathematical
model describing the performance is
presented.
Predicting the Effect of
Proprietary Conditioning
Agents on Flyash Resistivity
R. J. Jaworowski,
Apollo Technologies, Inc.
Flyash resistivity plays an important
role in the performance of ESPs. As ash
resistivities approach approximately 5 X
1010 ohm-cm, operational problems oc-
cur.
Recognition of flue gas conditioning
agents as a means to lower ash resistivity
has placed increased emphasis on the
development of predictive methods to
determine how the resistivity will be
influenced by a specific chemical.
Based on previous work by Bickelhaupt
and Sparks, a correlation has been devel-
oped to predict the effect of proprietary
chemicals in flyash resistivity. The corre-
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lation is relatively insensitive to tempera-
ture, field strength, and coal type.
Data obtained from field trials are used
to demonstrate the effectiveness of this
approach. A comparison of predicted
results with field data yields favorable
agreement.
SOa Conditioning to Enable
Electrostatic Precipitators to
Meet Design Efficiencies
J. J. Ferrigan, Wahlco. Inc.
This paper deals with a case study to
choose an effective and reliable method
of increasing the collection efficiencies of
two new ESPs, plagued with high resistiv-
ity flyash. The study is traced from the
time of erection of the two cold-side ESPs
in the early 1970's to the final solution
(80s flue gas conditioning) in 1979.
The paper goes into detail on mechan-
ical modifications and consultants' recom-
mendations, which were undertaken to
no avail. It then points out that, after all
possible mechanical "fixes" had been
completed, proprietary chemical condi-
tioning of the flue gas was tried, which
proved to be more detrimental than good.
As a last resort, SO3 flue gas conditioning
was tried, and it brought both cold-side
ESPs into design compliance. These facts
are supported by ESP outlet grain loading
tests, which show that the proprietary
chemical conditioning would not come
within a factor of 10 when trying to meet
the guarantee of 0.02 gr/scf, while SOs
flue gas conditioning enabled the ESPs to
operate under the 0.02 gr/scf limit.
Enhanced Precipitator
Collection Efficiencies Through
Resistivity Modification
D. Mahoney, Apollo Technologies, Inc.
High resistivity process dusts and fly-
ashes from low-sulfur coal may be modi-
fied by chemical treatment to improve
cold-side ESP performance. A new series
of noncorrosive, neutral pH additives have
been developed which are effective in
lowering resistivity. Studies have shown
that treatment is insensitive to coal vari-
ations. Furthermore, resistivities of 1011 -
1012 ohm-cm may be lowered to less than
108-1010 ohm-cm, depending on the addi-
tive choice and treatment level.
This paper discusses laboratory data
and actual field results during treatment
of a 100 MW boiler. It reviews the detailed
mechanism of the resistivity modification
and the practical effects of conditioning
levels on ESP performance.
Development of a New Sulfur
Type Ash Conditioning
R. H. Gaunt,
Air Correction Division, UOP. Inc.
Various types of chemical ash condi-
tioning agents are used to alter flyash
resistivity, and thereby improve ESP
performance. ACD/UOP has had experi-
ence with many chemicals and processes
on a pilot and full scale basis. Sulfuric
acid conditioning has advantages over
other sulfur conditioning systems in
availability, cost of chemical, process
control, ease of handling, and relative
lack of corrosion problems. In the past,
operating costs (power consumption) of
sulfuric acid systems have not been par-
ticularly attractive, especially in large
power plants. Now, ACD/UOP has devel-
oped a new system that utilizes sulfuric
acid with its advantages and also reduces
the capital and operating costs to be
competitive with other systems. This
system utilizes existing energy in the
compressed and heated plant combustion
air. A prototype unit at a 46 MW station
improved ESP collection efficiency to
99.8%from 85.0% at an operating cost of
$40 per day.
Operating Experience with Flue
Gas Conditioning Systems at
Commonwealth Edison
Company
L L. Weyers, Commonwealth Edison Co.
To restore ESP performance, a flue gas
conditioning program was established by
Commonwealth Edison in the early
1970s.
This paper is a history of its experience
with flue gas conditioning agents over the
last 8 years. Extensive testing of these
systems has supplied valuable informa-
tion which is currently being used as a
basis in design of future plant additions.
The Application of a Tubular
Wet Electrostatic Precipitator for
Fine Paniculate Control and
Demisting in an Integrated Fly
Ash and SO2 Removal
System on Coal-fired Boilers
E. Bakke, Peabody Process Systems
The development of a combined, tubu-
lar, wet electrostatic precipitator (WESP)
and vapor condensing heat exchanger
mounted in the top section of an SO2
absorber is discussed.
Pilot plant data on an integrated flyash
and SC*2 removal system with a variable
pressure drop venturi, a high velocity
spray tower, and the WESP show that it is
possible to operate with a specific collec-
tion area in the WESP of only 20-30
ftVIOOO acfm, tube velocities of 16-20
ft/sec., and overall system pressure drop
of 4-8 in. W.G., and still have flyash
removal efficiencies of 99.25-99.65% or
outlet emissions of 0.015-0.006 gr/scfd.
Heat recovery and flue gas reheat
options made possible by the WESP/heat
exchanger combination are discussed,
and installations of this system on indus-
trial boilers are reviewed. Initial and
annualized costs and space-saving bene-
fits are presented.
Evaluations of Ammonium
Sulfate Conditioning for
Improvement of Cold-Side
Electrostatic Precipitator
Performance
E. C. Landham,
Southern Research Institute
Measurement and analysis of the im-
provement in cold-side ESP performance
through the use of ammonium sulfate
conditioning agents were conducted at
two electric utility generating stations.
One plant was burning a low sulfur, high
alkali Western coal and the other a
moderate sulfur, low alkali Eastern coal.
Comprehensive field tests were per-
formed with and without the agents to
evaluate the change in performance as
well as to determine the mechanisms
involved. The measurements included
total mass and fractional efficiencies,
particle size distributions, rapping emis-
sions, in situ resistivity, ash and flue gas
analyses, opacity, and voltage-current
characteristics of the power supplies.
Measurements were made with a propri-
etary formulation of ammonium sulfate
injected on the hot and cold sides of the
air heater and with a generic formulation
injected on the cold side. The performance
of the ESPs was compared with a theore-
tical model, and an engineering analysis
of the installations was performed.
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Evaluation of Performance
Enhancement Obtained with
Pulse Energization Systems on a
Hot-Side Electrostatic
Precipitator
W. Piulle,
Electric Power Research Institute
Two pulse energization systems of dif-
fering design were temporarily installed
on separate chambers of a hot-side ESP.
Measurements of overall and size depend-
ent collection efficiency were performed
using conventional and pulse energiza-
tion for transformer-rectifier sets on each
of the chambers. The enhancement in
performance resulting from the use of
pulse energization was evaluated on an
overall mass and on a particle-size-
dependent basis. The results obtained
from the full-scale installation are com-
pared with results obtained in a pilot ESP
.at EPA's IERL-RTP.
The ESP was performing below design
values without sodium conditioning and
had experienced a pattern of performance
deterioration with accumulated time of
operation following plant outages during
which the ESP was cleaned by water
washing. Sodium conditioning is normally
used to maintain desired levels of per-
formance.
A New Microcomputer
System and Strategy for the
Control of Electrostatic
Precipitators
K. J. McLean, University of Wollongong
The paper outlines a new control
strategy being developed for ESPs opera-
ting with severe back corona. The inter-
face design, the algorithm developed, the
control strategy, and some test results
are presented. The aim of the system is to
maintain optimal efficiency using current
and voltage relationships, spark rate, and
optical monitor signals. The system is in
the development stage and is being cur-
rently tested at Munmorah Power Station,
N.S.W., Australia.
Assessment of the Commercial
Potential for the High Intensity
Ionizer to the Electric Utility
Industry
John S. Lagarias, Kaiser Engineers. Inc.
EPRI has performed extended labora-
tory and pilot scale tests of the APS High
Intensity Ionizer (HII), which reached a
level of performance where projections
could be made of its potential commercial
application to the electric utility industry.
Computer simulations were made of the
anticipated performance of a full-scale
HII for both high and medium resistivity
f lyash, and an evaluation was made of the
projected cost of commercially sized units.
Future ESP performance requirements
are forecast, based on an assessment of
stricter regulatory requirements for mass
emissions, fine particulates, and opacity.
An assessment of the technology, includ-
ing the HII, which could be used by
utilities over the next 30 years, for
upgrades and new installations, shows
that the HII could be used for upgrading
ESP's to meet the more stringent regula-
tions.
Application of Energy
Conserving Pulse Energization
for Precipitators—Practical and
Economic Aspects
H. H. Petersen. F. L. Smidth & Co.
Performance of ESPs collecting high
resistivity dust can be improved consider-
ably by pulse energization. The energy
consumption, however, is a major prob-
lem for its application. The system dealt
with here solves this problem: the unused
energy stored in the ESP during the pulse
is recovered to be used for the next pulse.
Operating results from full-scale field
tests over more than 2 years are pre-
sented to demonstrate that the system,
utilizing high-power electronic compo-
nents, has the required degree of reliabil-
ity for practical applications. The improve-
ment of ESP performance in relation to
installation and operating costs makes it
an attractive option to new ESPs for high
resistivity dust as well as to existing ESPs
with resistivity problems. Practical and
economic aspects of the installation and
preparation of the system are discussed.
Section C—Dry SO2 Scrubbers
SOz Removal by Dry
Injection and Spray Absorption
Techniques
E. Parsons, Buell Envirotech
A dry injection technique is shown to
have removal efficiencies greater than
70% for cost competitive systems by
results of a Colorado Springs pilot plant
test. The disposal of waste products from
the process has been a major problem.
The paper presents the most recent
results of an EPA sponsored waste dis-
posal study to -investigate the effecti
ness, including cost impact upon syst
process, of processing the waste to eli
inate waste disposal problems.
S02 removal for the spray absorpt
process is summarized. These data i
based on extensive testing at the Colors
Springs facility. Analysis of the by-prod
from the spray absorption demonstra
that no disposition problems would
quire additional processing of the I
products.
Dry Scrubbing SOz and
Particulate Control
N. J. Stevens, Research-Cottrell
In dry scrubbing SO2, the spray dr
and fabric filter are used to a signific;
extent for both SOz removal and partk
late solids collection. Pilot test resu
were obtained on low sulfur fuels
elucidate the roles of each control dev
in the dry scrubbing system.
SO2 removal reactions in the spi
dryer and fabric filter are compared a
the important process variables identif i<
Particulate collection of flyash/F(
solids mixtures by the spray dryer a
fabric filter is examined. Fabric fil
pressure drop variation with time and t
effect of dry scrubbing solids on t
specific resistance coefficient are c
scribed. Spray dryer and fabric filter soli
are examined for particle size distributic
chemical composition, moisture conte
and alkalinity. The cementious nature
flyash and its effect on SOz remov
solids collection, and system operabil
are also discussed.
Fiber and Fabric Aspects for
SOz Dry Scrubbing Baghouse
Systems
L Bergmann. Filter Media Consulting
This paper discusses both the chemic
reaction in dry scrubbing systems and t
role of fibers and filter media in tl
baghouse. The choice of available fibe
and their main characteristics are di
cussed, as well as factors influencing tl
selection of filter media and their pe
formance. Specifications for differe
fabrics are recommended.
Two-Stage Dry Flue Gas
Cleaning Using Calcium Alkali
D. C. Gehri, Rockwell International
Most of the dry flue gas cleaning (FG
systems that have been sold to date w
use high-calcium lime as the alkali r
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actant for SO? removal. In a two-stage dry
FGC system, optimum performance and
utilization of lime is achieved by passing
gas around the first stage spray dryer
and/or by recycling particulates removed
in the second-stage collector.
Three examples of dry FGC system
performance with lime, using these tech-
niques, for three types of coals are
considered: (1) low-sulfur, western subbi-
tuminous, (2) medium-sulfur lignite, and
(3) high-sulfur eastern bituminous. The
required FGC systems are discussed in
terms of the lime preparation equipment,
the FGC equipment, and waste disposal
techniques. The economics of the three
dry FGC systems is compared to that of
equivalent ESP wet scrubber combina-
tions.
Control of Sulfur Dioxide,
Chlorine, and Trace Element
Emissions from Coal-Fired
Boilers by Fabric Filtration
ft. Demski.
°ittsburgh Energy Technology Center
In studies conducted at OOE's Pitts-
burgh Energy Technology Center (PETC)
in a 500 Ib/hr coal-fired furnace equipped
with a baghouse, it was found that the
jaghouse filter cake removed significant
jortions of the toxic trace elements Hg,
As, and Se. When used in combination
with injection of dry sorbents such as
nahcolite, trona, and sodium bicarbonate,
approximately 95% removal of S02 and Cl
was obtained.
This paper summarizes previously re-
jorted studies relating to control of trace
elements. Emphasis is placed on the
recently completed investigation of SO2
control by dry sorbent injection. In the
atter study, tests were conducted with
coals ranging in sulfur content from 1 to
3%. Operating variables considered in-
cluded baghouse temperature, cleaning
cycle time, sorbent particle size, and
stoichiometric ratio of alkali to sulfur.
Except for baghouse cleaning cycle rate,
sach parameter had a significant effect
an SC"2 removal.
Section D—Scrubbers
-lyash Collection Using a
fenturi Scrubber—Minnesota
Bower's Commercial Operating
Experience
?. A. Johnson, Peabody Process Systems
Minnesota Power and Light elected to
jse a venturi scrubber as a particulate
removal devipe for Clay Boswell Station,
Unit 4 (500 MW). The selection had been
based on significant cost savings com-
pared to conventional ESP technology.
Prior to start-up of the full scale system,
extensive pilot plant test work was done
to determine performance characteristics
with regard to both particulate removal
and opacity. Unit 4 is now in commercial
operation. This allows comparison of
predicted performance based upon pilot
plant data with full scale system per-
formance.
F. P. Venditti, J. A. Armstrong, and M. Durham are with the Denver Research
Institute, Denver, CO 80208.
Dale L. Harmon is the EPA Project Officer fsee below).
The complete report, entitled "Third Symposium on the Transfer and Utilization of
Particulate Control Technology: Volume I. Control of Emissions from Coal-Fired
Boilers," (Order No. PB 83-149 583; Cost: $29.50, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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Fees Paid
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Agency
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Penalty for Private Use $300
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