x>EPA
United States
Environmental Protection
Agency
Industrial Environmental Researc
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S7-80-170 Dec. 1980
Project Summary
7
Environmental
Assessment of a
Waste-to-Energy Process:
GSA/Pentagon Co-Fired
Boiler Tests
Mark A. Golembiewski, K. P. Ananth, T. Sutikno, and Harry M. Freeman
A series of emission tests at the
Virginia Heating and Refrigeration
Plant (VHRP) in Arlington, Virginia,
were conducted by Midwest Research
Institute. This plant provides steam
heat or refrigerated air to the
Pentagon building. The study was
designed to obtain emission data
while one of the steam boilers was co-
fired with different blends of coal and
densified refuse-derived fuel (d-RDF).
The No. 4 boiler at VHRP was util-
ized for this test program. The steam
output of this underfeed-retort stoker
boiler is rated at 70,000 Ib/hr,
although usual maximum load is about
50,000 Ib/hr. Coal is normally the
sole fuel. For this d-RDF burn
program, sampling, was conducted
during three fuel firing modes: coal
only, 20% d-ROF + 80% coal, and 60%
d-RDF + 40% coal. The tests were
intended to be run at a single boiler
load for comparative purposes, but
steam output could not be held
constant during much of the sampling
period.
Samples of the coal, d-RDF, and
coal/d-RDF fuel mixtures were col-
lected hourly and analyzed by the
National Center for Resource
Recovery (NCRR) for moisture, ash,
heating value and chemical composi-
tion. Several daily samples of bottom
ash were also collected by NCRR.
These were analyzed for loss-on-
ignition and chemical composition.
Midwest Research Institute was
responsible for sampling and analysis
of the stack effluent. Tests were con-
ducted for particulate concentration,
gaseous criteria pollutants (SO2. NCK,
CO, and total hydrocarbons), and
chlorides. Particulate samples were
also analyzed for lead content.
This publication is a summary of the
complete project report, which can be
purchased from the National
Technical Information Service.
Introduction
Under the sponsorship of the U.S.
Environmental Protection Agency's
Fuel Technology Branch in Cincinnati,
Midwest Research Institute (MRI) is
presently conducting multi-media
environmental assessment of various
waste-to-energy conversion systems.
This paper will discuss the results of a
series of emission tests at the Virginia
Heating and Refrigeration Plant (VHRP)
in Arlington, Virginia.
VHRP is operated by the General
Services Administration (GSA) for the
purpose of satisfying the steam heat
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and chilled water needs of the Pentagon
and the Henderson Hall office building.
The heating plant consists of five
coalfired boilers, one of which (No. 4)
was utilized for the testing described in
this report.
The National Center for Resource
Recovery (NCRR) in Washington, D.C., is
concerned with developing the use of
refuse-derived fuel (RDF) as an alterna-
tive energy source. Discussions were
held with representatives of GSA
concerning possible use of densified
RDF as a supplemental fuel for their
coal-fired boilers. The outcome of these
discussions was an agreement to test
fire a coal-RDF fuel mixture at VHRP and
evaluate the subsequent effects on
boiler operation and air emissions. The
U.S. Environmental Protection Agency
(EPA), with MRI as contractor, provided
air sampling and analysis capabilities.
The test burn and air sampling activ-
ities were conducted during the week of
March 19-23, 1979, and results of
those emission tests are described
herein. Subsequent sections of this
report present a description of the boiler
test facility, an overviewof the sampling
and analytical methodologies
employed, and a discussion of the test
results.
Test Facility
The No. 4 boiler at VHRP was ma
factured by the Riler Stoker Compj
and installed in 1941. Itisanunderfe
retort stoker boiler with a rated ste
capacity of 70,000 Ib/hr. Normal m;
mum operating load for the boi
however, is about 50,000 Ib/hr.
schematic of the boiler with its auxili
equipment is shown in Figure 1.
Coal is supplied to the plant from
outdoor storage pile or directly from
cars via an underground beltconve\
The coal is transferred from t
conveyor to a bucket conveyor wh
feeds a coal bunker located above 1
Surge
Tank
Condens
I
D/A
(Deaeratorl ^
Tank
Chemical
Tank
COAL FIRED BOILER
VIRGINIA HEAT & REFRIG. PLANT
Figure 1. Schematic diagram of the test boiler.
2
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oiler. During the tesfburn program, the
RDF pellets were fed to the same
cket conveyor, using a-second belt
onveyor. The specified volume ratio of
lellets to coal was maintained in each
lucket through the use of throttling
ilates at the conveyor transfer points.
'he coal/d-RDF mixtures were also
ransferred to the same overhead
>unker that is normally used for coal
ceding.
Further information on the process
:onditions and equipment specifica-
ions is given in the complete project
eport.
Sampling and Analytical
Methodology
The emissions sampling program for
he GSA/NCRR d-RDF test burn was
esigned to characterize boiler exhaust
as emissions when firing coal and
vhen firing two blends of coal and d-
1DF. The sampling matrix is illustrated
n Figure 2. In addition to the stack
esting conducted by MRI, samples of
he input fuels as well as bottom ash
were collected by NCRR during the test
jrogram. The analytical matrices for
hese samples are also shown in Figure
I. A summary of the test chronology is
esented in the table below.
Brief discussions of the sampling and
analytical procedures are presented
next. Full descriptions of the methods
used are contained in the complete
report.
Coal and d-RDF Fi/e/s-Hourly grab
samples of the fuels (of about one cubic
ft) were taken from the weigh station
area above the ram feed chutes. Each
sample was then progressively sub-
divided to about a 5 kg size using a riffler
apparatus and stored in a plastic bag.
The fuel analysis basically followed
standard procedures of American
Society for Testing and Materials
(ASTM).
Moisture
Ash
Heating Value
C.H.N.
Chlorine
Sulfur
Lead
d-RDF'
Stack
Emissions
Coal-
GSA/
Pentagon
Boiler
Mechanical
Collector
T
Particulates
(Lead Analysis
by AAS)
02 & CO2
NOx
SOx
HC
CO
Chlorides
Moisture
Ash
Heating Value
C.H.N.
Chlorine
Sulfur
Lead
Bottom Ash
Collected
Fly Ash
Loss on Ignition
C.H.N.
Lead
Figure 2. Samplng and analysis matrix.
Bottom Ash—Grab samples of the
boiler bottom ash were collected twice
daily and composited. Analysis was
done in accordance with the standard
procedures of ASTM and U.S. Bureau of
Mines, and consisted of loss-on-
ignition, carbon/hydrogen/nitrogen,
and lead determinations.
Stack Emissions—Samples of the
boiler exhaust gases were collected
over a 4-day period and later analyzed in
the MRI laboratories. The sampling
analysis methods used for each of the
gas parameters measured are
discussed next.
Particulate Concentration—Three
EPA Method 5 runs were conducted
during each of the three fuel firing
Table 1. Pentagon Boiler Test Schedule
Run No. Date Fuel Fired
Test Period
/, 2, 3
4. 5. 6
7. 8, 9
10. 11
3/20
3/21
3/22
3/23
100% coal
20% d-RDF/80% coal
60% d-RDF/40% coal
100% coal
10:15-18:57
08:10-17:05
08:10-17:02
08:07-12:49
modes. In addition, two extra runs were
taken during a second baseline coal
mode, for a total of five runs when the
boiler was supplied with 100% coal. The
probe wash, filter catch, and impinger
contents of each sample were analyzed
for net particulate weight. Filter
samples were also analyzed for lead
content using atomic absorption spec-
trometry (AAS).
Oxygen and Carbon Dioxide—02 and
C02 contents of the stack gas were
measured using Fyrite detectors.
Replicate readings were taken during
each Method 5 run to determine the
molecular weight of the air stream and
the percentage of excess air used by the
boiler.
Criteria Gaseous Pollutants—
Continuous gas analyzers were used to
measure the concentrations of Oa, CO,
NO», SOa, and total hydrocarbons in the
stack effluent on a realtime basis. The
sample was drawn through a heated
Teflon sample line to a field trailer
which housed the monitoring equip-
ment. There, the sample stream was
dried and filtered before it was
proportioned to each of the analyzers.
Instrument responses were registered
on strip chart recorders and transcribed
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to data log sheets at 15-minute
intervals.
Chlorides—A midget impinger train
containing a dilute sodium hydroxide
solution was used to collect stack gas
samples for chloride analysis. One
chloride sample was taken for each
Method 5 particulate run (i.e., three per
fuel firing mode). Each sample was
collected over a half-hour period.
Presentation and Discussion of
Results
Results of the sampling and analysis
efforts are discussed as follows:
Boiler Operation
Although the full load rating of the No.
4 boiler is 70,000 Ib of steam per hour,
unseasonably mild weather conditions
(and thus reduced steam demand)
precluded running the unit nearfull load
conditions. As a result, GSA plant
personnel established an operating
level of 30,000 Ib/hr as one that could
be reasonably maintained for the test
program.
Fuel usage and heat input data from
the test program are summarized in the
complete project report. These data,
which have been selected to correspond
with the particulate sampling runs,
show a wide variation in boiler opera-
tion, even among the three runs at each
fuel firing conditions. Heat input rates
during the 11 sampling runs ranged
from 23.5 to 82.1 x 106 kJ/hr (22.3 to
77.8 x 106 Btu/hr). The variation in
boiler operation was primarily due to
fluctuating steam demand, the influ-
ence of the adjoining on-line boilers
when loads changed, and improper
functioning of some control instru-
ments.
Coal and RDF Fuels
The chemical composition of each
fuel was analyzed. Analysis results are
reported in detail in the complete project
report. Basically, the results are
report. Basically, the results showed
that the blend with the higher
proportion of d-RDF had a greater
moisture content, a lower ash content,
and a lower heating value. The higher
heating value of d-RDF was about 7800
Btu/lb dry.
Bottom Ash
The bottom ash sample of both coal
only and the 20% d-RDF blend showed a
very high proportion of combustible
material (over 30%), which would indi-
cate incomplete combustion of the fuels
during these two firing modes. The
average percentages of hydrogen and
nitrogen in the bottom ashes of the fuels
were about 0.10% and 0.08%, respec-
tively. The lead content in each bottom
ash sample was below the detectablility
of the instruments (0.6 ppm).
Stack Emissions
Particulate emissions were reduced
from 22 to 38% when d-RDF was
blended with the original coal fuel.
Filterable particulate emissions were
lowest when using the 20% d-RDF
blend and rose again when the propor-
tion of d-RDF was raised to 60%. This
finding may not be conclusive, however,
since the boiler load was held steady
during the 20% d-RDF firing but not
during the 60% mode. Further tests,
conducted over longer periods of time,
and at consistent boiler conditions, are
needed to substantiate the observed
trend.
The amount of particulate lead
emitted when burning the d-RDF with
coal is substantially higher than that
from combustion of coal alone and may
be a cause for environmental concern.
Approximately 200% more lead was
emitted during firing of the 20% d-RC
blend (an average of 1,000 //g/n
versus 330 /yg/m3 during co<
combustion), and 580% more (2,26
yug/m3) when the 60% d-RDF fuel WE
used.
Concentrations of sulfur dioxidi
nitrogen oxides, and carbon monoxid
all decreased slightly when the RDF wa
used with coal. Because of the very \o\
sulfur content of d-RDF, SOa emission
were reduced progressively as th
proportion of d-RDF with coal wa
increased. NOX and CO levels, howeve
are highly dependent on boiler combus
tion conditions which may or may nc
have been the direct result of burning c
RDF.
Chloride emissions showed n
definite trend which could be used t
correlate chloride emissions with RD
modes, though slightly highe
concentrations of HCI were observed i
two of the samples collected durin
combustion of the 60% d-RDF blend.
In summary, co-firing of d-RDF witl
coal at the Virginia Heating and Refrig
eration Plant appears to be a viabl
option from an environmental stand
point. However, the role of lead emis
sions must be considered when makin
a final evaluation of the overall potentia
of d-RDF substitution.
Mark A. Golembiewski. K. P. Ananth, and T. Sutiknoare with Midwest Research
Institute. Kansas City, MO 64110.
Harry M. Freeman is the EPA Project Officer (see below).
The complete report, entitled "Environmental Assessment of a Waste-to-Energy
Process: GSA/Pentagon Co-Fired Boiler Tests," (Order No. PB 81-109100;
Cost: $6.50, subject to change) will be available 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
Cincinnati, OH 45268
U.S GOVERNMENT HHNTCNO OFFICE: 1W1-757-064/OZ50
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Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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