vvEPA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45226
Research and Development
EPA-600/PS7-80-148 Sept. 1980
Project Summary
Environmental Assessment of
a Waste-to-Energy Process,
Burlington Electric's Wood
and Oil Co-Fired Boiler
Mark A. Golembiewski, K.P. Ananth, T. Sutikno and
Harry M. Freeman
In July 1978, Midwest Research In-
stitute conducted a series of emission
tests at the Burlington Electric
Department's power plant in Bur-
lington, Vermont. The study was
designed to provide multi-media
emission data for the purpose of iden-
tifying potentially adverse envi-
ronmental impacts, and to identify
pollution-control technology needs.
The No. 1 boiler at Burlington Elec-
tric, which was tested for this study,
is fueled by a combination of wood
chips and No. 2 fuel oil. Approxi-
mately 82% of the heat input (9.3
tons/hr) was provided by the wood
fuel and the remaining 18% by the fuel
oil (175 gal/hr). Electrical power
generated from this boiler system
was about 8 MW. The air pollution-
control system consists of two
mechanical collectors in series.
Four effluent streams were sampled
and analyzed for this assessment pro-
gram: bottom ash, primary collector
ash, secondary collector ash, and
stack emissions. Common to all
streams were characterizations for
elemental composition and poten-
tially hazardous compounds such as
polychlorinated biphenyls and
polycyclic aromatic hydrocarbons. In
addition, the boiler exhaust gases
were analyzed for paniculate, NOx,
S02, CO, and total hydrocarbon con-
centrations. The Source Assessment
Sampling System was also used,
following guidelines established by
EPA's Level 1 environmental assess-
ment protocol.
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. En-
vironmental Protection Agency's Fuels
Technology Branch in Cincinnati,
Midwest Research Institute (MRI) is
presently conducting multi-media envi-
ronmental assessments of various waste-
to-energy conversion systems. This paper
will discuss the results of one such effort
at the Burlington Electric Department's
power plant in Burlington, Vermont. The
Burlington plant was selected for study
because of the renewed interest in wood
and wood waste as a primary boiler fuel in
certain regions of the country. The Bur-
lington plant is the only facility in the U.S.
presently firing oil with wood waste to
generate electric power.
The sampling and analysis program at
Burlington was designed to provide multi-
media emission data for the purpose of
identifying potentially adverse environ-
mental impacts and assessing pollution-
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control needs. In the following sections of
this paper, we will briefly describe the test
facility, the sampling and analysis pro-
cedures that were used, and the results of
the test program. An assessment of the
results using EPA's Source Analysis
Model (SAM-1A) is also presented.
Description of Boiler Test
Facility
The No. 1 Unit at the Burlington Elec-
tric plant was originally a coal-fired boiler
that was modified to fire wood chips with
supplementary oil injection. Steam pro-
duced to power a 10 MW turbine
generator is rated at 100,000 Ib/hr.
Wood chips are conveyed from the
storage bin to four gravity-fed chutes.
From the base of the chutes, the chips are
injected into the boiler using compressed
air. The wood chips fall onto a horizontal,
traveling grate which is supplied with
underfire air. Because of the high
moisture content of the chips, the boiler
cannot provide the needed steam output
from wood alone; therefore, supplemen-
tary fuel oil is used. No. 2 fuel oil, along
with overfire air, is introduced above the
grate bed from both sides of the firebox,
thus insuring adequate steam production.
Residual ash is discharged at the end of
the grate into a hopper, from which it is
removed pneumatically to an outdoor
storage silo.
The flue gases leaving the boiler are
ducted to an emission control system
consisting of two, high efficiency
mechanical collectors in series. For a flue
gas flow rate of 60,000 acfm at 330° F, the
collectors were designed for an overall
pressure drop of 6.5 in. H20 and a collec-
tion efficiency of 97.75%.
Sampling and Analysis
Methodology
The sampling and analysis test matrix
that was used is shown in Figure 1. The
input fuels, bottom ash, primary and
secondary collector ash, and air emissions
at collector inlet and outlet were sampled.
Three complete sets of samples from each
of these streams were taken over a two-
day period. The sampling and analysis
procedures used were either EPA
methods or those approved by the EPA
project officer. Results of the sampling
and analysis efforts are discussed below.
Results
Input Fuels—The wood/oil feed ratio
during the MRI tests was approximately
80% wood and 20% oil, on a heat input
basis. The average composition of the
wood was 4.3% ash, 70% volatile matter,
and 25.7% fixed carbon (dry basis). The
average sulfur content was 0.35% and the
average heat of combustion was 5,870
Btu/lb (as received) and 9,480 Btu/lb (dry
basis). The sulfur content of the oil was
0.35%, v\/hile its heat of combustion
average was 19,500 Btu/lb (138,100
Btu/gal).
Bottom Ash—Analysis of elemental
composition in bottom ash indicated that
most elements were more concentrated in
the bottom ash relative to the fuel inputs.
Those elements exhibiting the largest in-
creases in concentration were Ba, Zr, Sr,
and Li. No PCB materials were detected in
the bottom ash samples above the 0.05
^g/g detection limit. One PAH com-
pound, phenanthrene, was identified at a
concentration of 0.89 ng/g.
Analysis for PCB materials at 0.05 pg/g
detection limit was negative in the ash
samples. No PAH compounds were iden-
tified in the primary ash sample extracts.
Wood Feed
Collector Inlet
Collector Outlet
Samp/ing- Take Three 5-Liter Samples
Each Day. Mix and
Extract a 1 -Liter Composite
Analysis: Determine H2O Content
HHV. Proximate/Ultimate
Elemental Analysis by
SSMS
Oil Feed
Sampling:
Analysis.
Bottom Ash
Samp/ing:
Analysis:
Take One or Two 0.5-L/ter
Samples
HHV, Proximate/Ultimate
Elemental Analysis by
SSMS
Oil *-
Wood *•
Take Three 1 kg Samples
Each Day, Mix and Extract
1 kg Composite
Elemental Analysis by
SSMS
PCB/PAH
Sampling and Analysis'
a. Method 5-Particu/ate - 1 Per Day
Elemental Analysis by SSMS°
b. Orsat (02 & CO2)
c. Particle Sizing - 1 Per Day
Wickes Boiler
85,000 Ibs/hr
r
hr
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Sampling and Analysis:
a. Method 5-Particu/ate - 1 Run Per
Day Elemental Analysis by SSMS*
b Orsat (O2 & C02)
c. Particle Sizing - 1 Run Per Day
d. Opacity (Method-9) - Two 1 Hr
Tests/Day
e. Continuous Analyzers (Oz, NO*,
SOz HC, CO)
f. PCB/PAH with Florist I Train -
2 Runs
g. SASS - 1 Run
Analyze Per Level 1 Requirements
Primary & Secondary Collector Ash
Sampling. Take a 1 kg Grab Sample
Each Hour - Mix & Extract
1 kg Composite
Analysis: SSMS
PCB/PAH
Bottom Ash
Primary Secondary
Collector Collector
Ash Ash
* Atomic Absorption Analysis May Be Conducted
Based on Results of SSMS Analysis
Figure 1. Test matrix for Burlington Electric's wood and oil-fired power plant
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However, several compounds were con-
firmed in the secondary ash samples, in-
cluding acenapthylene, phenanthrene,
fluoranthene, and pyrene. One sample
contained 10 ng/g of phenanthrene,
which was the highest PAH concentration
observed.
Uncontrolled Air Emissions—The
average uncontrolled paniculate concen-
tration was 2.96 g/dscm (1.30 gr/dscf) as
measured by EPA Method-5. On the basis
of heat input, uncontrolled paniculate
emissions averaged 1.47 g/MJ (3.43
lb/106 Btu). Oxygen and carbon dioxide
contents averaged 12.3% and 8.2%,
respectively. Filter samples from the
Method-5 paniculate tests were analyzed
for elemental composition. The elements
emitted at concentrations greater that 10
ng/dscm were Pb, Ba, Sr, As, Ga, Zn,
Cu, Fe, Mn, Ti, and P.
An optical/diffusional particle counting
system was used to measure the particle
size distribution of the uncontrolled emis-
sions. Particles in the range of 0.005 to
0.10 urn were counted by a diffusion bat-
tery/condensation nuclei counter ar-
rangement, while those in the 0.3 to 2.6
/jm range were counted by an optical
counter. Because the dilution system con-
sistently became plugged with larger par-
ticles during operation, no particle counts
could be obtained in the size region above
2.6 urn. Therefore, the mean particle size
could not be determined. Within the size
range of particles counted (0.005 to 2.6),
the majority of the particles appeared to
be between 0.3 to 0.5 pirn in diameter.
Controlled Air Emissions-Using con-
tinuous gas analyzers, concentrations of
02, NOX, SO2, CO, and total hydro-
carbons (THC) were measured in the
stack gas. NOX, and SOz concentrations
P P
and V were in the range of 1 to 75
fxg/dscm. The remaining elements had
concentrations which were less than 1
ng/dscm.
Particle size data was obtained by the
same method used at the collector inlet
(optical/diffusional particle counter). As
with the inlet measurements, data for par-
ticles > 2.6 ^m in diameter could not be
obtained. The number of small particles
« 2.6 jim) appeared to increase in the
controlled gas stream relative to the un-
controlled emissions. The reasons for this
increase are not clear.
Plume opacity data, obtained using
EPA Method-9, averaged about 20% on
both test days. Samples for analysis of
PCB and PAH materials were collected in
a special sampling train utilizing impingers
and a Florisil adsorbent trap. PCB analysis
did not produce any responses greater
that the 1 ng/sample detection limit of the
GC/MS analytical technique. Similarly,
no PAH compounds were identified at
levels which permitted structural confir-
mation.
Organic analysis of the Source Assess-
ment Sampling System (SASS) com-
ponents, in accordance with Level 1
guidelines, revealed low levels of organic
constituents. Characterization of the
organic emissions was difficult, although
they appeared to be composed mainly of
carbonyl-containing groups.
Source Assessment Model
(SAM-1A)
The EPA's SAM-1A methodology was
applied to the four effluent streams as a
means of interpreting the emission
results. The SAM-1A analysis results in-
dicated that the secondary collector ash
contained the highest degree of hazard,
although all three ash streams were
similar in the magnitude of their hazard
values. Stack emissions showed a
relatively low degree of hazard.
The primary collector ash stream had
the highest Toxic Unit Discharge Rate
(TUDR) which would seem to indicate
that this effluent should receive the first
priority for control measures. However,
because of certain limitations which are
inherent in the SAM-1A methodology,
this observation should not be regarded
as being definitive.
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However, several compounds were con-
firmed in the secondary ash samples, in-
cluding acenapthylene, phenanthrene,
fluoranthene, and pyrene. One sample
contained 10 ng/g °f phenanthrene,
which was the highest PAH concentration
observed.
Uncontrolled Air Emissions—The
average uncontrolled paniculate concen-
tration was 2.96 g/dscm (1.30 gr/dscf) as
measured by EPA Method-5. On the basis
of heat input, uncontrolled paniculate
emissions averaged 1.47 g/MJ (3.43
lb/106 Btu). Oxygen and carbon dioxide
contents averaged 12.3% and 8.2%,
respectively. Filter samples from the
Method-5 particulate tests were analyzed
for elemental composition. The elements
emitted at concentrations greater that 10
ng/dscm were Pb, Ba, Sr, As, Ga, Zn,
Cu, Fe, Mn, Ti, and P.
An optical/diffusional particle counting
system was used to measure the particle
size distribution of the uncontrolled emis-
sions. Particles in the range of 0.005 to
0.10 fim were counted by a diffusion bat-
tery/condensation nuclei counter ar-
rangement, while those in the 0.3 to 2.6
^m range were counted by an optical
counter. Because the dilution system con-
sistently became plugged with larger par-
ticles during operation, no particle counts
could be obtained in the size region above
2.6 urn. Therefore, the mean particle size
could not be determined. Within the size
range of particles counted (0.005 to 2.6),
the majority of the particles appeared to
be between 0.3 to 0.5 urn in diameter.
Controlled Air Em/ss/ons-Using con-
tinuous gas analyzers, concentrations of
02, NOx, S02, CO, and total hydro-
carbons (THC) were measured in the
stack gas. NOX, and SOa concentrations
averaged 66 and 138 ppm, respectively.
CO readings averaged 213 ppm and
THC concentrations were only 9 ppm.
Three Method-5 particulate runs were
made simultaneously with the sampling
runs at the collector inlet. The average
particulate concentration was 0.18
g/dscm (0.08 gr/dscf). The particulate
emission rate averaged 0.09 g/MJ (0.17
lb/106 Btu), on the basis of heat input.
The average efficiency of the two-stage
mechanical collection system, as deter-
mined from the simultaneous inlet/outlet
tests, was 94.2% for total particulate.
Elemental analysis of the Method-5 par-
ticulate filters indicated moderately high
elemental concentrations. Pb, Ba, Sr, Zn,
and Ti were present at the highest con-
centrations, approaching 100 /jg/dscm,
while Hg, Sb, Zr, Br, Se, As, Ga, Cu, Ni,
and V were in the range of 1 to 75
ng/dscm. The remaining elements had
concentrations which were less than 1
Particle size data was obtained by the
same method used at the collector inlet
(optical/diffusional particle counter). As
with the inlet measurements, data for par-
ticles > 2.6 fjm in diameter could not be
obtained. The number of small particles
« 2.6 ^m) appeared to increase in the
controlled gas stream relative to the un-
controlled emissions. The reasons for this
increase are not clear.
Plume opacity data, obtained using
EPA Method-9, averaged about 20% on
both test days. Samples for analysis of
PCB and PAH materials were collected in
a special sampling train utilizing impingers
and a Florisil adsorbent trap. PCB analysis
did not produce any responses greater
that the 1 ^g/sample detection limit of the
GC/MS analytical technique. Similarly,
no PAH compounds were identified at
levels which permitted structural confir-
mation.
Organic analysis of the Source Assess-
ment Sampling System (SASS) com-
ponents, in accordance with Level 1
guidelines, revealed low levels of organic
constituents. Characterization of the
organic emissions was difficult, although
they appeared to be composed mainly of
carbonyl-containing groups.
Source Assessment Model
(SAM-1A)
The EPA's SAM-1A methodology was
applied to the four effluent streams as a
means of interpreting the emission
results. The SAM-1A analysis results in-
dicated that the secondary collector ash
contained the highest degree of hazard,
although all three ash streams were
similar in the magnitude of their hazard
values. Stack emissions showed a
relatively low degree of hazard.
The primary collector ash stream had
the highest Toxic Unit Discharge Rate
(TUDR) which would seem to indicate
that this effluent should receive the first
priority for control measures. However,
because of certain limitations which are
inherent in the SAM-1A methodology,
this observation should not be regarded
as being definitive.
Mark A. Golembiewski, K. P. Ananth and T. Sutikno are 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, Burlington Electric's Wood and Oil Co-Fired Boiler,"(Order No.
PB 80-220627; Cost $12.00, subject of change) will be available from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-557-4650
The EPA Project Officer can be contacted at:
Industrial Environmental Research Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
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Official Business
Penalty for Private Use $300
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