United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S7-84-092 Oct. 1984
&ER& Project Summary
Environmental Assessment:
Source Test and Evaluation
Report—Riley Gas Producer
M. R. Fuchs, R. A. Magee, and P. M. Jeans
In December 1979, Riley Stoker
Corporation conducted a test of the
Riley Gas Producer, fueled by North
Dakota (Indianhead) lignite. The test, at
Riley Stoker's research center in
Worcester, MA, was sponsored jointly
by Riley Stoker and American Natural
Service Company of Detroit, Ml. Radian
Corporation performed a Source Test
and Evaluation (STE) of the Gas Pro-
ducer as part of EPA's program to
define and evaluate the environmental
effects of low-Btu gasification. The
results of the STE are presented in this
report.
The STE involved characterization ot
all inputs and outputs of the Gas Pro-
ducer. Material balances were also
developed. The output streams included
the product gas, ash pan water, cyclone
dust, and gasifier ash. The results in-
dicate that all output streams have
some potential for environmental con-
cern, as either fugitive emissions (prod-
uct gas) or discharge streams (dust,
ash, ash pan water). Analyses of the
leachates of the gasifier ash and cyclone
dust showed that they were nonhaz-
ardous according to Resource Conser-
vation and Recovery Act protocol and
standards.
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
Radian Corporation is under contract to
the EPA to perform a comprehensive
environmental assessment of low- and
medium-Btu coal gasification. This pro-
gram includes the performance of Source
Tests and Evaluations (STEs) to gather
data for the assessment of viable low-
and medium-Btu gasification systems.
This report, a Source Test and Evalua-
tion Report (STER), gives results of an
environmental assessment of the Riley
Gas Producer. Riley Stoker Corporation,
the Riley Gas Producer licensor, operates
a commercial-scale pilot plant at its
research center in Worcester, MA. The
test program, commissioned by American
Natural Service Company (ANSC) of De-
troit, Ml, was conducted in December
1979. Radian Corporation performed the
STE during this period.
Test Overview
The STE was designed to collect data
pertinent to the environmental assess-
ment of the Gas Producer. For the most
practical application of the results, testing
was performed under steady-state oper-
ating conditions. The discharge and pro-
cess streams of the gasification process
were characterized to determine the
potential environmental impact of each.
Four streams were characterized: product
gas, gasifier ash, cyclone dust, and ash
pan water.
The product gas was separated into two
fractions at 115°C (240°F) by the samp-
ling procedure. The separation allows the
assessment of potential health and eco-
logical effects of fugitive emissions by
characterizing the vapors of the product
gas which are the most likely source of
fugitive emissions. The separation was
achieved by collecting the aerosol phase
of the product gas in an electrostatic
precipitator (ESP) operated at 115°C
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(240°F). The aerosol phase consists of
particulate matter and mist consisting of
liquid tars and oils. The vapors of the
product gas were collected downstream
of the ESP, in a condenser at about 15°C
(60°F), followed by either an organics
adsorption resin (for collecting organic
vapors) or an impinger train (for collecting
vaporous trace elements, ammonia, or
hydrogen cyanide).
The Riley Gas Producer is a modifica-
tion of the Morgan Gas Producer, devel-
oped in England in the early 1900s. Riley
Stoker purchased the licensing rights to
the Morgan Gas Producer and has up-
dated several design features. The gasi-
fier feedstock was North Dakota (Indian-
head) lignite supplied by ANSC. (NOTE: In
December 1978, EPA characterized a
Wellman-Galusha gasification system,
using North Dakota (Indianhead) lignite,
at the U.S. Bureau of Mines' Twin Cities
Metallurgy Research Center at Fort Snel-
ling.)
Major findings of this program are:
• Health effects bioassay tests of both
solids and neutral leachates of the
gasif ier ash and cyclone dust indicated
no adverse health effects; ecological
bioassay results of neutral leachates
of the gasifier ash and cyclone dust
showed significant toxic effects.
• Leaching studies of the gasifier ash
and cyclone dust, to determine the
effects of solid waste disposal, indi-
cated that the materials are nonhaz-
ardous according to Resource Conser-
vation and Recovery Act(RCRA) proto-
col and standards.
• Over 50 percent of the lignite sulfur is
converted to reduced sulfur species in
the product gas.
• The nitrogen content of the ammonia
(NHa) and hydrogen cyanide (HCN) in
the product gas is equal to about 26
percent of the I ignite nitrogen content.
• Enclosing and pressurizing the coal
bin and using nitrogen purge on the
gasifier pokehole significantly reduces
fugitive emissions from these sources.
Results
A major concern about using coal and
coal-derived fuels in industry centers
upon emissions of sulfur dioxide (SO2,
nitrogen oxides (NO,), and particulates.
While the actual emissions of SOz and
NOX due to syngas combustion depend on
application, the following correlations
can be made.
The North Dakota (Indianhead) lignite
gasifier feedstock for the 24-hour test
had an average sulfur concentration of
0.44 g/106 J (1.02 lb/106 Btu). About 53
(31-100+) percent of the sulfur being fed
to the gasifier was converted to reduced
sulfur species in the product gas. If 100
percent of the reduced sulfur species in
the product gas were converted to S02
during combustion, the resulting SO2
emission level would be 0.49 g/106 J
(1.10 lb/106 Btu), based on the heat
content of the lignite.
The average NHa concentration of the
product gas was 7.8 x 105 fjg/Nm3 and
the average HCN concentration was 1.8 x
105/ug/Nm3. The nitrogen content of the
product gas NH3 and HCN is equal to
about 26 percent of the lignite nitrogen
content.
The particulate loading of the product
gas stream was 4.76 x 105 /ug/Nm3,
downstream of the cyclone. The partic-
ulate was assumed to be of the same
composition as the cyclone dust, and the
cyclone dust ash content (39.93 percent)
was used to calculate the particulate
emissions from combustion. Basing the
adjusted particulate loading on the heat
value of the lignite feedstock, the partic-
ulate emission after combustion would
be 0.26 g/106 J (0.06 lb/106 Btu). This
emission estimate does not consider
possible particulate formation resulting
from incomplete combustion of tars and
oils.
Fugitive emissions of hydrocarbons
were measured in the area of the gasifier
by several methods. Hydrocarbon con-
centrations were less than 6.5 x 102
/ug/Nm3 (<1 ppm as CH<). Hydrocarbons
were also measured in the off-gases of
the nitrogen-pressurized coal bin: the
concentrations were 3.2 to 3.9 x 103
fjg/Nm3 (5 to 6 ppm as methane, CH4).
Readings of two carbon monoxide (CO)
monitors maintained by Riley Stoker
were recorded during the sampling: the
maximum recorded concentration was
2.7x104//g/Nm3 (24 ppm), with readings
generally well below this value. The
Occupational Safety and Health Admin-
istration (OSHA) permissible exposure
limit (PEL) for CO is 5.7 x 104 pg/Nm3 (50
ppm). There is no OSHA regulation for
hydrocarbons as a compound class. Pro-
pane, the lightest hydrocarbon regulated
by OSHA, has a PEL of 1.8 x 106 /ug/Nm3
(1000 ppm).
STEs have been performed for a Chap-
man low-Btu gasifier (with a bituminous
coal feedstock) and a Wellman-Galusha
low-Btu gasifier (with an anthracite coal
feedstock). The Chapman STER gives
results for coal feeder vent gases for
hydrocarbons «C7) of 2.5 x 106 /jg/Nm3
and CO of 2 x 107 //g/Nm3. The coal
hopper gases at the Wellman-Galusha
facility (anthracite) were reported in the
STER as 1.4 x 106 /ug/Nm3 CH« and 2.7 x
108 CO. Related values measured at the
Riley Gas Producer are several orders of
magnitude less. These data demonstrate
the relative reduction of fugitive emis-
sions achieved by the controls used on
the coal bin at the Riley Gas Producer.
Trace elements enter the gasification
process with the lignite feedstock and are
subjected to the high temperatures of the
process. Many elements, especially the
more volatile ones, are volatilized in the
hot areas of the system and may: (1)
remain a vapor in the product gas, (2)
condense homogeneously, or (3) con-
dense on aerosol particulates. Other
elements, chemically transformed into
gaseous species, are emitted in the
product gas. Most trace elements remain
in the coal solids and are emitted in the
gasifier ash. Even though the majority of
most elements are emitted with the solid
waste streams, RCRA extraction proce-
dures analysis results in the classification
of these solids as nonhazardous.
Minor and trace elements can be
grouped according to the mechanisms by
which each is discharged. The elements
found primarily in the product gas are
considered highly volatile or transfomed
into gaseous compounds. Moderately
volatile elements, those found predomi-
nantly in the cyclone dust or product gas
particulate, can be evaluated on the basis
of volatilization and recondensation. Ele-
ments discharged predominantly in the
gasifier ash are considered to be non-
volatile.
For this STE, an element was con-
sidered to be highly volatile if 25 percent
or more of its total mass was found in the
vapor portion of the product gas. These
were:
bromine
cesium
chlorine
fluorine
gallium
iodine
mercury
selenium
silicon
sulfur
tellurium
An element was classified as moder-
ately volatile if 25 percent or more of its
total mass was found in the cyclone dust
and aerosols of the product gas. These
were:
antimony lead
arsenic tin
chromium zinc
germanium
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The following elements require addi-
tional data to characterize their behavior
definitively:
I Product Gas O Ash Pan Water • Cyclone Dust
I GasifierAsh
beryllium iridium
bismuth neo-
cadmium dymium
dysprosium osmium
erbium palladium
europium platinum
gold praeseo-
holmium dymium
rhenium
rhodium
ruthenium
silver
tantalum
terbium
thallium
thulium
uranium
yterrbium
Figure 1 shows the elemental distribu-
tions in the discharge streams, in the
order of increasing boiling points. In
general, as the elemental boiling points
increase, the predominance of elemental
distribution shifts from the product gas to
the gasif ier ash. Although a general trend
is evident, there is no direct correlation
between elemental boiling point and
distribution. The distribution of individual
elements in the system depends not only
on elemental boiling point, but also on
much more complex properties. These
may include chemical reactions in the
gasifier, the volatility of compounds con-
taining the elements, and solubility of
compounds in the tars and oils.
Gross alpha and beta radioactivities
were determined on two samples of
lignite, a composite cyclone dust, and a
composite gasifier ash. In addition, gam-
ma and alpha spectrometry was used for
specific isotope analyses of these solid
samples. Complete analytical results for
gross alpha, beta, and specific isotope
analyses are given in the full report.
Bioassay tests of the solid gasifier ash
and cyclone dust indicated little or no
health hazard. A neutral leaching of the
two solid streams provided a liquid for
bioassay testing that showed a high level
of potential ecological hazard. However,
subjecting the gasifier ash and cyclone
dust to RCRA leaching studies resulted in
the solids being classified as nonhazard-
ous.
100'
75-
50-
>*. 25-
F Cl Br I P Hg S As Se Rb Cs K Na ZnMgiBa Li Sb Yb EuCa PbSmMnSnGa
Elements in Order of Increasing Boiling Point
WO-\
75H
50H
25-
At Cr B CuDyScNi BeTbiGcCo Y Gd Fe V Pr Ti CeLaZr U ThNbMoW
Elements in Order of Increasing Boiling Point
Figure 1. Stream elemental distributions or percentage of combined discharge streams.
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M. P. Fuchs, R. A. Magee, and P. M. Jeans are with Radian Corporation, Austin, TX
78766.
William J. Rhodes is the EPA Project Officer (see below).
The complete report, entitled "Environmental Assessment: Source Test and
Evaluation Report—Riley Gas Producer," (Order No. PB 84-246 396; Cost:
$31.00, 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; 1984 — 659-016/7839
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
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