X-/EPA
United States
Environmental Protection
Agency
Industrial Environmental Researcl
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S7-81-077 July 1982
Project Summary
Environmental Assessment:
Source Test and Evaluation
Report—Exxon Miniplant
Pressurized Fluidized-Bed
Combustor with Sorbent
Regeneration
R. J. Kindya, R. R. Hall, G. T. Hunt, W. Piispanen, and P. F. Fennelly
The report gives results of a compre-
hensive emission sampling and analy-
sis program conducted at the EPA-
sponsored Exxon Miniplant, a pres-
surized coal-fired fluidized-bed
combustor and sorbent regeneration
system. The sampling and analysis
methods used provide screen ing data
on organic and inorganic pollutants
and indications of biological activity;
however, in general, they are not
designed to provide final quantitative
results.
Air pollutant emissions of trace
elements were measured and com-
pared to appropriate emissions goals.
Seven inorganic trace elements ex-
ceeded emissions goals in the com-
bustor flue gas, indicating a need for
further investigation.
Air pollutant emissions of total
organics were less than for comparable
conventional combustion systems.
Limited further analyses for specific
polynuclear aromatic compounds
indicated that emissions of one of
these compounds exceed its emis-
sions goal.
Analysis of laboratory-generated
leachates from solid waste samples
revealed trace metal concentrations
well below Federal hazardous waste
criteria.
Positive results for mutagenicity
and cytotoxicity screening tests re-
quire further investigation. Similar
results have been reported for other
coal-fired fluidized-bed combustors
and conventional combustion systems.
This Project Summary was devel-
oped by EPA's Industrial Environ-
mental Research Laboratory, Research
Triangle Park. NC. to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report
ordering information at back).
Introduction
The development of fluidized-bed
combustion (FBC) is being supported by
the Federal government, private
industry, and utility groups because of
its potential advantages over conven-
tional coal combustion methods. Re-
duction of S02 during the combustion
process is the primary advantage of FBC
because it eliminates the need for add-
on flue gas desulfurization equipment.
Other advantages include a potential
reduction in capital costs (compared to a
conventional coal-fired boiler) and the
capability to burn a wide variety of fuels,
including such low-grade fuels as
anthracite culm, coal cleaning wastes,
and industrial wastes. An additional
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advantage of pressurized fluidized bed
technology is the potential to achieve
higher fuel-to-electricity efficiencies
than conventional systems.
In fluidized-bed combustion, a mix-
ture of coal and limestone is supported
on a grid at the bottom of a boiler.
Combustion air passes through the grid
at high velocities, typically 1.2 - 2.4 m/s
(4 - 8 ft/s). The upward flow of the air
holds the solids in suspension, creating
a quasi-f lu id that possesses many of the
properties of the liquid. The most
important liquid-like property to the
boiler designer is the fact that bed
material is exceptionally well mixed and
flows throughout the system without
agitation. This well-mixed semiliquid
state produces high heat transfer rates
and permits combustion at temperatures
in the 760 - 930°C (1400 - 1700°F)
range.
The EPA-sponsored Exxon Miniplant
was a pressurized fluidized-bed com-
bustor (PFBC) and sorbent regeneration
system with a coal-firing capacity of 1.8
MW (6.3 x 106 Btu/hr). Exxon operated
the Miniplant from early 1974 to the
summer of 1979, when the program
ended. During the several thousand
operating hours, extensive investiga-
tions of sulfur capture, NOX emissions
and control, high-pressure/high-tem-
perature particulate control, combustion
efficiencies, and many other aspects of
FBC were completed. Sorbent regener-
ation was demonstrated in 1975 and an
experimental program including sorbent
regeneration was conducted during the
first half of 1979.
This report discusses results of
comprehensive sampling and analysis
conducted by GCA/Technology Division
at the Exxon Miniplant m May 1979.*
These efforts were based on a phased
approach to environmental assessment
developed by EPA's Process Measure-
ments Branch at the Industrial En-
vironmental Research Laboratory at
Research Triangle Park, NC (IERL-RTP).
The first phase, Level 1, involves a
screening approach using sampling and
analytical techniques that sacrifice
accuracy and compound specificity in
order to identify any possible problem
areas in a cost-effective manner. Level
1 should yield final analytical results
within a factor of ±3. These results can
be used to: provide preliminary envi-
*GCA/Technology Division conducted the field
measurement program under U S EPA Contract
68-02-2693, Exxon Research and Engineering
operated the Miniplant and supported the field
program under U S EPA Contract 68-02-1312
ronmental assessment data; identify
problem areas; and formulate the data
needed to rank energy and industrial
processes, streams within a process,
and components within a stream, for
further consideration in the overall
assessment. The second phase. Level 2,
is directed by Level 1 results and is
designed to provide additional, more
specific, accurate, and quantitative
information that will confirm and
expand the data gathered in Level 1. The
primary focus of the sampling and
analysis discussed in this report was at
Level 1. Some Level 2 analytical work
was conducted.
Facilities Description and
Emission Streams Sampled
Figure 1 is a simplified schematic
diagram of the Exxon Miniplant as it
operated during the Level 1 sampling
program. As indicated, 11 streams were
sampled for Level 1 analysis at the
Miniplant. These samples are listed and
described in Table 1. Individual com-
ponents of the process are briefly
described below.
Process Description
Coal and sorbent are injected pneu-
matically into the combustor through a
single port, 28 cm (11 in.)-above the
water-cooled fluidizing grid. The flow of
coal is controlled to maintain constant
temperature in the combustor.
The combustor is a 9.75 m (32 ft) high
refractory-lined vessel with an i.d. of 33
cm {13 in.). Heat of combustion is
removed by water-cooled tubes in the
fluidized bed. Coal feed rates of 230
kg/hr (500 Ib/hr) and expanded bed
heights of 6.1 m (20 ft) are possible, but
the unit usually operates at about half
these values. The unit is water cooled
with both the cooling water temperature
and metal temperature continuously
measured.
Solids are rejected from the com-
bustor through a port abovethefluidizing
grid. From this port, the solids flow by
gravity through a steel pipe into a pulse
pot. The solids are then pneumatically
transported by controlled nitrogen
pulses to a pressurized lockhopper from
which they are periodically dumped into
metal drums. A similar system, not
including a pressurized lockhopper, is
used to transfer solids tothe regenerator.
Combustion and fluidizing air are
provided by a mam air compressor
(shown in Figure 1). Pressure in the
combustor is controlled by maintaining
a specified gas flow, across an appro-
priately sized ceramic-coated orifice, b
dilution of the flue gases with higl
pressure air as shown in the top c
Figure 1 .
The sorbent regenerator consists of ;
refractory-lined vessel with an i.d. of 2'.
cm (8.5 in.) and an overall height of 6.'
m (22 ft). Operating temperatures a
high as 1 100°C (2000°F) and pressun
up to 1000kPa (10atm)canbeachievei
in the regenerator. Typical superficia
velocity is 0.6 m/s (2 ft/s) with ai
expanded bed height of 2.3 m (7.5 ft).
The regeneration process is based 01
the one-step reductive decomposition o
CaSCU by the reaction:
CaS04
CaO
S02
An undesirable competing reactior
involving the formation of CaS als<
occurs:
CaS04 + 4
H2
CO
CaS + 4
Therefore, an oxidizing zone is providet
in the regeneration vessel to conver
CaS to CaS04:
CaS + 202
CaSO4
(3
At the Miniplant, natural gas is
burned in the plenum below the
fluidizing grid to achieve the reactior
temperature. Additional fuel is injectec
directly into the bed, just above the
fluidizing grid, to create a reducing zone
in which reaction (1) occurs. Supple
mentary air is injected into the fluidizec
bed to create an oxidizing zone tc
convert CaS to CaSO4 via reaction (3).
Flue Gas and Flue Gas
Particulate Handling
Flue gas and entrained solids (fly ash
and sorbent) exit the top of the com-
bustor and enter a three-stage cyclone
system. Solids separated by the first-
stage cyclone drop through a stee
dipleg and enter a pulse pot from whicr
they are pneumatically conveyed bacl<
to the combustor (100 percent rein
jected). Solids (primarily fly ash) escaping
the primary cyclone enter more efficiem
second- and third-stage cyclones where
finer sizes of solids are captured. The
third-stage cyclone operates at 85 to 94
percent efficiency. The final flue gases
generally contain 0.03 to 0.15 g/Nm3 o1
particulates with a mass median diam-
eter of 1 to 3 /urn. The collected solids
from these cyclones pass thr-ougl"
separate diplegs and enter pressurizec
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To ESP
To
Scrubber
Scrubber
Slurry
(£/
. 'Coal and
Limestone
Feed Supply
A uxiliary
Air
Compressor
Indicated Stream Sampled
a
Natural Gas
Compressor
Main Air
Compressor
Figure 1. Schematic of the Miniplant PFBC as it operated during the Level 1
environmental assessment with Level 1 sampling points indicated.
lockhoppers from which solids are
periodically dumped into metal drums.
After leaving the third-stage cyclone,
the flue gas expands through a converg-
ing nozzle. A secondary source of high
pressure air is metered through a ball
valve with a pneumatic actuator and
positioner. Superimposing this sec-
ondary flow of air on the primary flow of
flue gas through the nozzle, maintains
gas pressure in the combustor at the
desired level, typically 950 kPa (9.5
atm).
During the Level 1 tests, the EPA
mobile electrostatic precipitator was
used to remove additional paniculate
from the cooled, depressurized flue
gases. This experiment was conducted
because the final paniculate concen-
tration of 0.03 to 0.15 g/Nm3 might be
adequate for process performance, but
emissions would need to be limited to
13 ng/J (about 0.035 g/Nm3) to meet
Federal New Source Performance
Standards for utility boilers.
Hot flue gases from the regenerator
pass through a cyclone to remove
entrained particles Next the gases are
cooled from 930°C (1700°F) to about
200°C (390CF) in a water-cooled heat
exchanger. Gases are depressurized
before entering a scrubber for final
cleanup before venting to the atmos-
phere.
Operating Conditions
Combustor and regenerator operating
conditions during the EPA tests are
listed in Table 2 Champion coal (with a
sulfur content of 1.7 percent) andGrove
limestone were used. It was necessary
to feed significant quantities of fresh
limestone to compensate for elutnation
and to maintain the bed in the com-
bustor. Because high sulfur coal was
not available, the resultant Ca/S ratio
was 1.29, much higher than desirable
for commercial regenerative operation.
Also, system pressure was 700 kPa (7
atm), instead of the normal 950 kPa (9.5
atm), to achieve adequate fluidizing
velocities in the regenerator. Because
the pressure was 30 percent lower than
previous experimental runs, coal feed
rate was reduced to maintain the
desired excess air at the specified
fluidizing velocity.
Sampling and Analytical
Methodology
Sarppling Techniques
Six solid streams were sampled at the
Miniplant: two feed streams and four
waste streams. Samples for chemical
and most biological analyses were
collected every 2 hours during the flue
gas sampling. All solid samples were
split for organic and inorganic analysis.
The individual organic and inorganic
samples were each composited during
the test run to provide a representative
sample of each solid stream
To provide samples of the combustor
flue gas and the regenerator offgas for
Level 1 Environmental Assessment
analysis, the Source Assessment
Sampling System (SASS) was used to
collect samples of the paniculate and
gaseous components of each indicated
gaseous stream.
The SASS tram collects particles in a
series of three cyclones with nominal
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Table 1. Summary of Stream Sample Characteristics
Sample Point
Identification
No.
Stream Description
Physical
State
Collected
By
Important Characteristics
1 Diluted combustor flue gas (cooled) Gas
(ESP hopper catch) and solid
2 Undiluted combustor flue gas (hot) Gas
3 Regenerator flue gas (cooled) Gas
4 High pressure dilution air Gas
5 Solids from regenerator cyclone Solid
6 Spent combustion bed solids Solid
7 Solids from second combustor
cyclone
Solids from third combustor
cyclone
9
10
11
Cool feed
Sorbent feed
Scrubber slurry
Solid
Solid
Solid
Solid
Liquid
GCA Fly ash entrained in combustion gases, particle concer
tration about 0.15 g/Nm3, mass median particle sizi
below 5 cm. Temperature 175°C (350°F), pressure 13
kPa (5 psig).
GCA Similar to (1) but temperature is 750°C (1500°F) and
pressure is 700 kPa (7 atm).
GCA Sorbent particles entrained in off gases, low particle
loading, temperature and pressure similar to (1).
GCA Compressor output containing organic residue from
lubricating oil, pressure is 700 kPa (7 atm).
Exxon No special characteristics.
Exxon Solids stream containing spent sorbent and some botton
ash, discharge temperature approximately 900° C
(1700°F).
Exxon Stream contains fly ash, particles of mass median
diameter approximately 17 cm, temperature approxi-
mately 150 to 300°C (300 to 600°F).
Exxon Stream contains fly ash, particles of mass median
diameter approximately 4 cm, temperature approximatel
150 to 300°C (300 to 600°F).
Exxon No special characteristics.
Exxon No special characteristics.
Exxon Liquid stream containing fly ash from stream 3 to
condensed compounds, also ammonia, temperature 25 tc
40°C (70 to 100°F).
cut points of 10 /urn, 3/um, and 1 /urn. A
150-mm filter collects the particles that
are less than 1 /urn in diameter. The
volatile organics are captured by 150 g
of XAD-2 resin in a temperature-
controlled trap. A series of impingers
follows the resin trap to capture volatile
metals. Setup and performance of the
SASS train followed Level 1 specifi-
cations.
The SASS train samples of the diluted
combustion flue gas (stream 1) were
obtained from a temporary duct leading
to the mobile ESP. Samples were
collected on May 3 and 4, 1979.
Because organic contamination of the
diluted combustor flue gas by the
compressed air used for dilution was
suspected, additional sampling was
conducted before dilution (stream 2).
The SASS train cyclones, filter, and
oven were not used at this sampling
location because the Balston filter in the
sample treatment system had already
collected the particulates. The Balston
filter operated at 260°C (500°F). A
SASS train organic module was used to
collect volatile and nonvolatile organic
species. Sampling was accomplished by
connecting a flexible stainless steel line
to the existing metering valve.
The regenerator flue gases were also
sampled with the SASS train. Sampling
was conducted at approximately iso-
kinetic conditions in the center of the
6.4cm (2.5 in.) i.d. pipe transporting the
regenerator flue gases. Sampling was
conducted on May 2 and 3, 1979.
A small resin trap containing 25 g of
clean XAD-2 was used to collect
organics in the dilution air. For sample
collection, the resin trap was adapted t<
a glass EPA Method 5 sampling train
The sampling train was attached to ar
existing tap on the compressed ai
supply line. A metering valve was use<
to control the sample flow rate am
reduce the pressure to acceptable
levels. The samples were recovered ty
transferring the XAD-2 to an ambei
glass jar and then rinsing the resin trap
with methylene chloride (distilled-in
glass grade).
Gaseous components of the Mini
plant flue gas streams were sampled fo
subsequent analysis using a combina
tion of continuous withdrawal, gral:
sampling, and special impinger trair
techniques. Analyses were conductec
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Table 2. Summary of Miniplant PFBC Operating Conditions
Parameter
Combustor
Regenerator
Length of run, hr
Pressure. kPa
Average bed temperature, °C
Expanded bed height, m
Superficial velocity, m/s
Ca/S molar ratio
Coal feed rate, kg/hr
Coal type (percent S)
Coal higher heating value, kJ/kg
Coal size, mesh
Sorbent feed rate, kg/hr
Sorbent type
Sorbent size, mesh
Excess air, percent
Flue gas oxygen content, percent
99
700
894
3.1
1.5
1.29
77
Champion (1 .7)
31,400
81
705
1010-1031
(oxidizing-reducing)
1.9
0.6-0.8
(oxidizing-reducing)
5.4
Grove limestone
8x25
46
4.1
Grove limestone
0.3
for CO, CO2, 02, N2, SO2, H2S, COS, CS2,
ammonia, and cyanide.
Grab samples of the four gaseous
streams for low-boiling (< 100°C)
organic analysis were obtained in
evacuated 2-liter glass sampling bulbs.
Inorganic fixed gas samples were
obtained as integrated Tedlar bag
samples.
Exxon personnel provided a single
sample of scrubber slurry for Level 1
testing.
Analytical Techniques
Inorganic constituents of Miniplant
effluent stream samples were quanti-
fied using a combination of instrumental
and wet chemical techniques. The
primary Level 1 inorganic analysis
technique is spark source mass
spectrometry, which provides sensitive
detection limits for about 70 elements
Interferences, such as variations in the
ion source discharge conditions and the
photoplate interpretation techniques
used in Level 1, provide only semi-
quantitative data accurate to within a
factor of 2 or 3.
Miniplant bulk solid streams, having
the potential to be disposed of in a
landfill or another area where leaching
could occur, were subjected to inor-
ganic analysis of both the solid material
and laboratory-generated distilled water
leachates. Atomic absorption spectrom-
etry was used to accurately quantify
selected elements in the leachates.
The Level 1 test protocol attempts to
identify the major organic compound
classes within each sample stream
tested. Methylene chloride extracts of
the samples are analyzed. Qualitative
and some quantitative data are gener-
ated, using gravimetry, gas chromatog-
raphy, liquid chromatography, infrared
spectroscopy, and low resolution mass
spectrometry. These Level 1 techniques,
in general, do not provide data on
specific compounds. Level 1 methods
were supplemented with high per-
formance liquid chromatography using
fluorescence detection for poly nuclear
aromatic compounds.
Volatile organics (boiling points below
100°C) are separated into six boiling
point ranges by onsite gas chromatog-
raphy. Moderately volatile organics
(boiling points 100 - 300°C), in methy-
lene chloride extracts, are analyzed in
the laboratory by gas chromatography.
Flame ionization detection is used in
both of the above cases. Nonvolatile
organics (boiling points above 300°C)
are measured by gravimetric methods in
methylene chloride extracts. These
organic concentration data provide
some qualitative indication of the types
of compounds that may be present.
Level 1 liquid chromatographic (LC)
separation was designed to separate
samples into seven reasonably distinct
classes of organic compounds and was
applied to all samples that contained a
minimum of 15 mg combined volatile
and nonvolatile organics. A sample was
placed on a silica gel liquid chromat-
ographic column, and a series of eluants
of sequentially increasing polarity were
used to separate the sample into
fractions for further analysis.
Infrared analysis was used to deter-
mine the functional groups in an organic
sample or liquid chromatography frac-
tion of a partitioned sample. The
interpreted spectra provide information
on functionality (e.g., carbonyl, aromatic
hydrocarbon, alcohol, amine, aliphatic
hydrocarbon, and halogenated organic).
Level 1 bioassays are a cost-effective
initial screening tool that indicates
potential health or ecological effects. As
such, the test results should be used to
point out areas requiring further in-
vestigation. Health effects tests con-
sisted of the Ames test for mutagenicity,
and mammalian cell cytotoxicity assays
using rabbit alveolar macrophages
(RAM) and Chinese hamster ovary
(CHO) cells. Fathead minnows, daph-
nids, and algae were used to test for
acute ecological effects.
Results
Data Handling
Criteria or standards for air, water,
and solid waste pollutants are needed to
properly determine the implications of
test results. Federal standards exist for
some pollutants, such as total particu-
lates, NOX, and S02 in boiler flue gases.
Federal criteria are also available to
determine if a solid waste is considered
hazardous. However, emission standards
do not exist for most of the pollutants
measured in this and other environ-
mental assessment programs.
IERL-RTP has developed a set of
conservative Discharge Multimedia
Environmental Goals (DMEGs). They
are derived using models incorporating
available exposure or recommendations
data such as industrial Threshold Limit
Values (TLV), NIOSH recommendations
for worker exposure, drinking water
criteria, results of toxicity experiments
using animals, and EPA/NIOSH order-
ing numbers or animal data on carcino-
genicity. These goals are emission
concentrations that are used in IERL-
RTP research programs to provide
perspective on potential environmental
hazards, to provide direction for control
technology 'research programs, and to
rank emission streams for future
investigation. These conservative goals
are a screening tool to provide focus for
further, more detailed investigation.
The simplest model used to derive
DMEG limits incorporates TLVs as air
pollutant emission goals. Emission
concentrations below the TLV are
assumed to be safe, since dispersion
usually produces ground-level concen-
-------
trations lower than stack concentra-
tions by a factor of 1000 or more. This
dilution factor should, in general,
provide adequate protection for chronic
exposure of the general population. The
other goals and models are based on
similar but more complex (and, at times,
more tenuous) extrapolations.
Measured trace element concentra-
tions for each Miniplant effluent stream
sample were compared to their in-
dividual DMEG specific for the media of
interest (air, water, solid wastes).
Elements in excess of their goals were
"flagged," providing a mechanism to
estimate potential hazards associated
with emission of that stream. Such
estimates may be made to reflect both
human health and ecology. Elements in
excess of their DMEG indicate a need
for further investigation.
Summary of Test Results
Data generated from Level 1 analyses
of Miniplant samples were of three
general types: inorganic analysis rely-
ing on spark source mass spectroscopy
(SSMS), atomic absorption spectrometry
(AA), or wet chemical techniques;
organic analysis using gravimetry,
liquid chromatographic separation,
infrared spectrophotometry, or low
resolution mass spectrometry (and
onsite gas chromatography for gaseous
streams); and bioassay results of
specific health or ecological effects
testing.
Inorganic Data
Table 3 summarizes inorganic ele-
mental data for Miniplant samples. Data
are from SSMS or AA for gaseous waste
stream samples, solid stream samples,
and laboratory-generated distilled
water leachates. Measured concentra-
tions were compared to their respective
appropriate emission goals (DMEGs).
Table 3 data show seven elements
exceeding emissions goals in com-
bustor flue gas. Flagging of these
elements indicates a potential area for
Level 2 investigation. However, Level 2
efforts would have to be preceded by
validation of the Level 1 SSMS results.
Some elemental concen-trations,
especially Cr, Ni, and Fe, may have been
high because of contamination from the
stainless steel of the sampling train.
Although four elements exceed their
DMEG in regenerator flue gas, further
analyses of this stream are unlikely.
Regenerator flue gas would be treated
Table 3. Summary of Inorganic Trace Element Data for Miniplant Samples
Stream Description
Number of Chemical
Species >DMEG
Identity of Chemical
Species >DMEG
Gaseous waste streams3
Regenerator flue gas 4
Combuster flue gas6 7
Solid streams0
Regenerator cyclone solids 14
ESP hopper ash 16
Second combustor cyclone 14
solids
Third combustor cyclone 15
solids
Spent combustion bed 4
material
Laboratory-generated,
distilled water leachatesd
Regenerator cyclone solids 0
Second combustor cyclone
solids 0
Third combustor cyclone solids 0
Spent combustion bed
material 0
Coal feed 0
Sorbent feed 0
V, Cr, Ni, Rh
P, Ca, V, Cr, Fe, Ni, As
Be, Al, P, Ca. Ti, V, Cr, Mn, Fe,
Ni, Cu, Zn, As, Cd
A I, P, Ca. Ti, V, Cr. Mn, Fe. Ni.
Cu, Zn, As, Se, Cd, Ba, Pb
Al. P, Ca. Ti, V. Cr, Mn, Fe. Ni,
Cu.Zn.As.Cd.Pb
Al, P. Ca. Ti, V. Cr. Mn. Fe, Ni.
Cu, Zn. As, Se, Cd, Pb
Ca, P, Fe, Ni
aAir DMEGs used for comparison.
'"Results represent emissions for the total flue gas stream. Dilution air was not
analyzed and is assumed not to contribute to the totals of inorganics analyzed.
cLand DMEGs used for comparison.
d Water DMEGs used for comparison.
before venting to the atmosphere and
thus does not represent a true emission
stream.
Bulk solid waste streams from the
Miniplant PFBC were chemically evalu-
ated in two ways. Solid samples were
analyzed for trace elements by SSMS
(AA for Hg and Sb) and compared to land
DMEG emission goals. In addition,
distilled water leachates were prepared,
analyzed in a similar manner, and the
results compared to water DMEGs.
As seen in Table 3, numerous, albeit
similar, trace elements exceeded their
respective land DMEGs in all solids col-
lected by the various control devices
used at the Miniplant. Only four
elements exceeded one or both land
DMEGs for Spent Combustor Bed
Material. When laboratory leachates of
these bulk solid materials were pre-
pared and analyzed, however, no
element in any sample exceeded any
discharge goal. In fact, most elemental
concentrations in the leachates were
more than two orders of magnitude
below their goals. Based on these
leachate data, leaching of potentially
toxic species from disposed solid waste
streams at the Miniplant would not
appear to be a problem. Solid waste
streams would, therefore, be at a lower
priority for subsequent Level 2 analysis
than would flue gas particles.
Organic Data
Samples from the Miniplant generally
contained low levels of organic com-
pounds compared to DMEGs and Level
1 organic analysis criteria.
The SASS train organic module (XAD-
2 resin adsorbent extracted with ChfeClz)
from the regenerator flue gas streams
and the diluted combustor flue gas
stream were the only samples analyzed
that contained sufficient organic mate-
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Table 4. Summary of Bioassay Results of Miniplant PFBC Samples
Health Effects Tests
Ecological Effects Tests
Sample
Description
Scrubber slurry
XAD blank
Combustor flue
gas - XAD
Regenerator flue
gas - XAD
Fine SASS
paniculate
Coarse SASS
paniculate
SASS filter-control
ESP hopper ash
Regenerator cyclone
Combustor bed
material
2nd Cyclone catch
3rd Cyclone catch
Ames RAM
Mutagenicity* Cytotoxicity
/V
N
+ N
+ N
+ N
+ N
N
+ Low
Low
Low
Low
Moderate
CHO
Cytotoxicity"
_
-
-
High
N
N
N
N
N
N
N
N
Fish
(96-hour LCso)
High
N
N
N
N
N
N
N
High
High
High
Low
Daphnids
(48-hour LCscJ
High
N
N
N
N
N
N
N
High
High
High
Moderate
Algae
[ECscJ
Moderate
N
N
N
N
N
N
N
High
High
High
High
*+/- = positive/negative mutagenic response; no detectable toxicity.
b/V = not run for indicated sample.
°- = negative CHO cytotoxicity response
rial to require liquid chromatographic
separation. Because organic concentra-
tions were so low, the infrared spec-
trometry and low resolution mass
spectrometry analyses provided only
general results that were of limited use
Samples analyzed from the Miniplant
generally contained such low levels of
organic compounds that these data
were interpreted as:
1. Initial Level 1 organic data were
compiled, including totals for
volatile species (TCO-total chro-
matographable organics), non-
volatile species (GRAV-gravimet-
ric), and onsite GC spectra where
applicable.
2. A survey was made of all DMEG
values that have been adopted for
organic compounds or classes of
compounds (586 to date).
3 It was assumed that the total
weight of organics present in the
sample analyzed was representa-
tive of one compound, as a worst
case, and all species whose
DMEG was lower than this total
were listed This exercise resulted
(for some samples) in a list of
compounds of "potential concern "
In other samples, this exercise
resulted in eliminating organic
compounds as an area of concern
for future investigation.
4. These compounds were then re-
viewed based on knowledge of
process chemistry, operating
conditions, and the available
Level 1 bioassay results. This
review eliminated some species
that could not possjbly be present
in these FBC emission streams.
5 A final list (on a stream-by-stream
basis) of organic compounds of
potential concern was compiled.
Organic compounds of concern in
Miniplant emission streams appear to
be limited to polynucleararomatic(PNA)
species that might be present in SASS
tram samples (particles and XAD) from
combustor and regenerator flue gases.
Bioassay Data
Results of testing Miniplant samples
in the Level 1 bioassay screen are sum-
marized in Table 4. Results are listed
based on qualitative Level 1 bioassay
response criteria, except Ames results,
which are listed as positive/negative.
Five samples were positive (muta-
genic) in the Ames test. Except for the
third cyclone catch, all streams exhibited
low toxicity to RAM cells. Regenerator
flue-gas XAD extract was the only
sample toxic to CHO cells. Regenerator
cyclone catch leachate, spent combus-
tion bed material leachate, and second
cyclone catch leachate all exhibited
high toxicity in all ecological effects
tests Third cyclone catch leachate was
variably toxic in these tests depending
on the organism exposed. The toxicity.
found in the ecological tests is probably
attributable to high pH.
The resulting three sets of data from
Level 1 analysis for each tested stream
from the Miniplant PFBC were com-
pared Inorganic species that were
flagged as exceeding one of their
emission goals, organic species of
potential concern possibly present in a
sample (as determined above), and the
response of a sample in the Level 1
battery of biological tests were all
considered in making the final evalua-
tion of which streams should receive
priority for level 2 analysis.
Radioassay of Miniplant
Samples
Multimedia samples collected during
the May 1979 Level 1 sampling program
at the Miniplant were analyzed for
selected radioisotopes. Radioisotope
emissions data from FBC are required
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by the EPA's Office of Radiation
Programs to evaluate the need, if any,
for emissions limitations or other
standards or criteria as instructed by the
Clean Air Act Amendments. Also, these
data serve as an initial effort toward
incorporation of radioactivity (as an
environmental pollutant) into the en-
vironmental assessment methodology
developed by the EPA Office of Research
and Development through IERL-RTP.
Seven solid samples were analyzed.
Coal and sorbent feedstocks were
analyzed for isotopic uranium (234U,
2351J, 238U) and isotopic thorium (228Th,
230Th). ESP hopper ash was not available
m sufficient quantity to permit analysis
for thorium isotopes but was analyzed
for isotopic uranium, 226Ra, 228Ac, 210Pb,
and 210Po. Regenerator cyclone solids,
solids captured by second and third
combustor cyclones, and spent bed
material were assayed for all nine
isotopes.
Data indicate that most of the radio-
isotopes leave the system as part of the
second and third combustor cyclone
catches. Radioisotopes escaping the
plant in the Miniplant flue gases or in a
commercial FBC facility would probably
be 1 - 20 percent of those measured in
the ESP hopper catch.
R. J. Kindya, R. R. Hall. G. T. Hunt, W. Piispanen, and P. F. Fennelly are with
GGA/Technology Division, Bedford, MA 01730.
John 'O. Mi/liken is the EPA Project Officer (see below).
The complete report, entitled "Environmental Assessment: Source Test and
Evaluation Report—Exxon Miniplant Pressurized Fluidized-Bed Combustor
with Sorbent Regeneration," (Order No. PB82-196 858; Cost: $ 18.00, subject
to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
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
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use S300
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