United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S7-81-037 July 1981
Project Summary
Fabric Filter System Study
Second Annual Report
K. L. Ladd, R. L. Chambers, 0. C. Plunk, and S. L. Kunka
This report describes second year
activities of a comprehensive EPA-
funded study of a commercial fabric
filter on a 360 MW low sulfur coal-
fired unit at Southwestern Public
Service Company's Harrington Station
near Amarillo, Texas. Special tests
were performed to characterize gas-
eous and particulate emissions, to
evaluate fabric performance, and to
optimize the fabric filter system's
performance. Tests will continue dur-
ing the third year of study.
This report is submitted in fulfillment
of Contract No. 68-02-2659 by South-
western Public Service Company
under the sponsorship of the U.S.
Environmental Protection Agency.
This report covers the period October
1,1978 to October 1,1979.
This Project Summary was developed
by EPA's Industrial Environmental
Research Laboratory. Research Trian-
gle Park. NC. to announce key find-
ings of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
In order to assess the feasibility of
utilizing fabric filters for air quality
control, the U.S. Environmental Protec-
tion Agency (EPA) executed a contract
with Southwestern Public Service Corn-
pa ny (SPS) in 1977 to make a compre-
hensive study of a fabric filter system
used for particulate collection on a large
electrical generating unit that burns low
sulfur Western coal. The plant site
selected was Harrington Station (Unit
2), Southwestern's first coal-fired facility.
When constructed, the baghouse was
the first and largest to be used on a new
utility boiler. It remains one of the
largest baghouses currently in operation.
The baghouse being studied at
Harrington Station is a Wheelabrator-
Frye, Inc. structural baghouse with
deflate/shake cleaning. It first went on
line in June, 1978. The baghouse con-
sists of 28 compartments with 204 bags
per compartment for a total of 5,712
bags; each bag is 11V4 inches in diam-
eter and 30 feet, 8 inches long. The
baghouse was specified at 1,650,000
acfm of flue gas at 313°F, thus yielding
a design air-to-cloth ratio of 3.15 to 1
(gross) or 3.4 to 1 (net).
Unit 2, on which the baghouse is
installed, has a 360 MW turbine with a
tangentially-fired steam generator. The
boiler utilizes pulverized, low sulfur
Western coal to produce 2,688,000
Ibs/hr of steam. The fly ash-laden flue
gas from the boiler flows through the
preheater directly through the fabric
filter system and then out the stack.
The study objectives set out in the
EPA/Southwestern contract are de-
scribed below. These objectives were
formulated to help utilities and other
coal burning facilities obtain information
for evaluating air control alternatives.
SPS especially hopes to aid those burn-
ing low-sulfur Western coal.
1. Determine operating and mainte-
nance costs of an operating fabric
filter system over an extended
period of time in order to give other
utilities data on the economic
feasibility of baghouses.
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2. Characterize performance of the
unit by looking at specific param-
eters which include (a) an assess-
ment of the effect of pressure drop
versus time; (b) removal efficiency
to be determined by special manual
testing; (c) continuous opacity
monitoring; (d) an investigation of
the long-term reliability of the sys-
tems; and (e) determination of
optimum operating conditions.
3. Bag performance and bag life will
be studied by (a) periodic removal
of test bags for analysis by an
independent consultant; (b) analy-
sis of pressure drop and through-
put on an individual compartment
basis; (c) and other special fabric
studies.
Progress during the first year of study
is discussed in the First Annual Report
(EPA-600/7-79-183, August, 1979).
This report describes project activities
during the second year of study, which
progressed from the first year's organi-
zational stage to actual testing and
evaluation. The first set of special tests
was conducted, a fabric assessment
program was implemented, and a wide
range of operation and maintenance
tasks were completed. In addition, a
data acquisition system was established
and certain study areas were given
special consideration.
The original work plan for the second
year of study entailed a number of tests
and programs which could not be con-
ducted during an abnormal start-up
phase typical of first-year operation.
However, project activities provided
valuable information about parameters
neither the utility nor the vendors had
expected. These circumstances allowed
for trouble-shooting to bring the bag-
house up to an expected level of per-
formance.
Summary of Project Activities
1. To characterize gaseous and
particulate emissions from the
boiler/baghouse system, South-
western conducted a series of
special tests during December,
1978. Results of particulate test-
ing confirmed that Unit 2 can
operate in compliance with the
existing New Source Performance
Standard (NSPS) of .1 lb/108Btu.
However, problems in the testing
with the heated probe caused
particulate results to be biased
(high). Concentrations of NO*
were determined to be consistent
at all five sampling locations. As
a result. Southwestern and EPA
concluded the testing program
could be better managed by ex-
cluding NO, from future testing.
Test results from the stack loca-
tion indicated the unit can meet
existing NSPS standards for S02
and results correlated well with
stoichiometric calculations. S02
measurements at inlet locations
were erratic due to high negative
duct pressure. Table I shows
results of particulate, NOX and
S02 testing.
2. GCA Corporation conducted ex-
tensive tests from February 9,
1979 through February 15,1979.
(See Table II, GCA Data Summary.)
Mass emissions of particulate
were conducted at the stack loca-
tion with five sampling runs.
Mass emissions ranged from
.007 lbs./106 Btuto.034lbs./106
Btu. Average particulate collec-
Table I. Results of Particulate Testing
tion efficiency was determined to
be approximately 99.3%.
Particulate size distributions
were made utilizing Anderson
impactors. The mean particle
diameter was determined to be
5.4 microns at the stack exit. The
mean particle diameter for the
east and west inlet was deter-
mined to be 3.8 and 2.6 microns,
respectively. Due to erratic data
scatter, further testing by impac-
tor is recommended.
Sulfur dioxide emissions were
within NSPS of 1.2 lb/10« Btu.
However, the results were erratic,
probably due to high negative
stack pressure. Oxides of nitrogen
emission were consistent across
the entire baghouse.
Results of sulfur trioxide testing
ranged from 0.3 to 3 ppm. To
obtain a better measurement and
to better understand S03 con-
centrations and their relationship
Run
n
East
Inlet
gr/SCF
West
Inlet
gr/SCF "
Theoretical
Inlet +
gr/SCF
Stack***
gr/SCF lb/106 Btu
1* 2.28 2.74 2.09 .053 .106
2* 2.04 2.26 1.96 .050 .097
3** 1.67 1.63 2.27 .033 .061
^Assumes 70% Fly ash, 30% bottom ash and economizer ash; no consideration for
sootblowing.
*Sootblowing continuously.
**Not sootblowing.
**The concentrations of particulate obtained from the stack are biased high because
a reaction took place in the unheated Inconel probe liner.
Results of /VO, Testing
Run
#
/
2
3
East
Inlet
Method 7
.68
.71
.67
East
Outlet
Method 7
.64
.68
.71
West
Inlet
Method 7
.61
.59
.62
West
Outlet
Method 7
.62
.62
.62
Stack
Method 7
.63
.66
.64
Results of SOz Testing
t
Run
#
2
3
East Inlet*
Method 6
lb/106 Btu
.53
.59
.62
West Inlet*
Method 6
lb/106 Btu
.36
.32
.20
Stoichiometric**
lb/106 Btu
.76
.84
.88
Stack
Method 6
lb/106 Btu
.73
.78
.84
*These concentrations are suspected of being low because of the high negative
pressure pulling the absorbing solutions forward, thereby resulting in the
absorbed SO? not being analyzed. t
**Assumes alt sulfur is converted to SOa. '
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Table II. GCA Data Summary
Results of Paniculate Testing EPA Method 5
Run
#
1
2
3
4
5
6
East
Inlet
gr/SCF
1.03
0.99
1.34
2.21
1.53
1.36
West
Inlet
gr/SCF
1.57
1.68
1.20
1.36
1.02
2.36
East
Outlet
gr/SCF
0.011
0.007
0.004
0.004
0.001
0.005
West
Outlet
gr/SCF
0.019
0.005
0.008
0.007
0.002
0.042
Stack
gr/SCF
#
0.009
0.008
0.012
0.004
0.017
Stack
lb/106 Btu
*
o.o/s
0.076
0.024
0.007
0.034
Results of SO* Testing EPA Method 6
Run
#
2
4
6
East
Inlet
lb/106 Btu
#
0.98
1.10
West
Inlet
lb/106 Btu
0.91
0.80
0.61
East
Outlet
lb/106 Btu
0.82
0.94
0.68
West
Outlet
lb/106 Btu
0.95
*
0.64
Stack
lb/106 Btu
1.10
#
0.74
Results of /VOx Testing EPA Method 7
Run
tt
2
4
6
East
Inlet
lb/106 Btu
ft
0.55
0.63
West
Inlet
lb/106 Btu
*
0.50
0.53
East
Outlet
lb/106 Btu
0.60
0.52
0.48
West
Outlet
lb/106 Btu
0.69
0.53
0.55
Stack
lb/106 Btu
*
0.51
0.47
Results of 503 Testing EPA Method 8
Run
#
2
4
6
East
Inlet
ppm
0.27
2.07
2.56
West
Inlet
ppm
0.79
0.67
1.96
East
Outlet
ppm
0.99
0.60
1.81
West
Outlet
ppm
0.72
0.82
1.67
Stack
ppm
1.10
«
1.86
*No data this run.
**Average based on three samples only.
to acid dew point, a Goksoyr Ross
test will be performed during the
next series of tests.
Difficulties encountered during
organic emission sampling pre-
vented a conclusive analysis of
this data during the second year
of study. GCA's final report will
deal with this parameter in a
more complete manner.
3. During the second year of study,
Southwestern implemented a
fabric assessment program in
which individual bags were re-
moved from compartments at
random and sent to an indepen-
dent testing firm for evaluation.
This phase of study will continue
in the third year to determine if
such tests are useful in evaluating
bag performance and bag life.
Another special study was initi-
ated between Southwestern and
Wheelabrator-Frye, Inc. This study
was designed to determine distri-
bution of ash on bags in a given
compartment and differences in
particle size distribution in the
compartment and along the fab-
ric. Preliminary results of these
tests show that the bags receive
equal dust loading regardless of
position in the compartment.
Furthermore, indications are that
both dust loading and particle
size do not change significantly
along the length of the bag.
An additional fabric assessment
program was conducted by Acurex
Corporation utilizing a small mo-
bile baghouse. Recommendations
made to Southwestern following
this study were that Southwes-
tern should evaluate the perfor-
mance of an Acid Flex coating
and performance characteristics
of higher deflation pressures
with ringed bags. Acurex also
recommended higher shake fre-
quencies, confirming results of
previous tests performed by
Southwestern.
6. Southwestern developed a tech-
nique for analyzing individual
compartment performance by
measuring relative flow. This
technique allows data taken at
any flow condition to be compared
with data taken at any other set of
flow conditions. Results to date
have indicated this technique to
be a reliable and sufficiently
accurate method for measuring
compartment performance.
7. Improved performance was ob-
tained during the second year of
study by optimizing deflation
pressure drop and shaker speed.
As a result, deflation pressures
were attenuated from the initial
0.5-inch w.g. to 0.1-inch w.g.
Excellent results were obtained
by increasing rapidity of shake in
several experiments. Studies are
in progress to determine the
effect of increased shake on bag
life. Preliminary results to date
indicate that there is no drastically
detrimental effect on bag life.
8. Originally, pressure drop in the
baghouse was excessive. Since
rebagging with different bags,
optimizing deflation control, and
increasing shake speed, baghouse
performance has been greatly
improved.
9. A data collection and assessment
program was initiated during the
second year of study. However,
due to a faulty magnetic tape
system, appropriate data proc-
essing has not been possible so
that data can be easily reduced
and analyzed. An intense effort
will be made in the third year of
study to manually reduce much
of this data. In addition, a new
magnetic tape system will be
installed. Due to concern about
high pressure drop problems,
much of the pressure drop data
was manually processed to give
monthly values for the full load
pressure drop. Plots of full load
pressure drop for each month
-------
have proven to be an invaluable
tool in assessing trends in bag-
house performance. (See Figures
1 and 2).
10. A special study area of the EPA/
Southwestern project includes
corrosion testing, electrostatics,
and quality assurance (QA). Cor-
rosion coupons were installed
and then removed for analyses
during the second year of study.
Results indicate that corrosion in
the Harrington baghouse at this
point is minimal. Cage voltage
measurements made by Acurex
during the mobile baghouse study
led to a decision by EPA to initiate
a program with Research Trian-
gle Institute to study electrostatics
and its relationship to pressure
drop problems.
East Side
West Side
14.0
12.0
10.0
A/>
H*°8.0\
6.0
4.0
2.0
Before Rebagging
Sept. Nov. Jan. Mar. May
Oct. Dec. Feb. Apr.
Month
*Air to cloth ratio of 3.4
Figure 1.
Monthly full load pressure
drop, original fabric.
CD
"• 7
I
(0
I
.C
0.
< 5
OAt V = 3.4 ft./min.
X At V = 3.0 ft./min.
July
Aug. Sept.
1979
Oct.
July Aug. Sept.
1979
Oct.
Figure 2. Monthly full load pressure drop., new fabric.
K. L Ladd, R. L Chambers, O. C. Plunk, and S. L Kunka are with the Southwest-
ern Public Service Company, Amarillo, TX 79170.
Dale L Harmon is the EPA Project Officer (see below).
The complete report, entitled "Fabric Filter System Study: Second Annual
Report," (Order No. PB 81-185 670; Cost: $17.00, 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
» U.S. GOVERNMENT PRINTING OFFICE 1»1 -757-01Z/7H9
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Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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