United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S7-86/015b June 1986
vxEPA Project Summary
Coal Gasification
Environmental Data
Summary: Sulfur and
Nitrogen Species
Maureen Kilpatrick
This report summarizes data on sul-
fur and nitrogen species from the
source test and environmental assess-
ment studies of low- and medium-Btu
gasification processes which were
sponsored by the Air and Energy Engi-
neering Research Laboratory of the
U.S. Environmental Protection Agency
from 1977 to 1981. The data are focused
on the composition and distribution of
the major streams from the gasifier
unit. Material accountability, elemental
distribution, and species distributions
are included for sulfur and nitrogen.
Consistent trends in the collected data,
comparison with the results of some
laboratory studies, and correlations
with some fundamental chemical rela-
tionships are given.
This Project Summary was devel-
oped by EPA's Air and Energy Engineer-
ing Research Laboratory, Research Tri-
angle 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 ultimate fate of the sulfur and ni-
trogen in coal gasification processes is a
recognized environmental concern. Fu-
ture commercial designs for sulfur
removal units, ammonia stripping pro-
cesses, and wastewater treatment sys-
tems for coal-based synthetic fuel
plants will be based on test data from
pilot-scale facilities and discharge esti-
mates calculated from the existing tech-
nology data base. This report presents a
compilation and review of data on sul-
fur and nitrogen available from the U.S.
Environmental Protection Agency
funded environmental assessment of
gasification processes to facilitate data
access and to provide a more cohesive
basis for understanding the fate of these
components in gasification.
The gasification processes discussed
here were selected based on the greater
availability of process, gas, liquor, and
solid phase data. Most of the data in this
report are from:
• Chapman gasifier—Holston Army
Ammunition Plant, Kingsport, TN.
• Wellman-Galusha gasifiers—Glen-
Gery Brick Company, York, PA; and
U.S. Bureau of Mines, Twin Cities
Metallurgy Research Center, Fort
Snelling, MN.
• Riley gas producer—Riley Stoker
Corporation, Worcester, MA.
• Foster-Wheeler/STOIC gasifier—
University of Minnesota, Duluth,
MN.
• Lurgi-type gasifier—Kosovo,
Yugoslavia.
• Koppers-Totzek gasifiers—Ptole-
mais, Greece; and Modderfontein,
South Africa.
• Texaco gasifier—Ruhrkohle/
Ruhrchemie, Oberhausen-Holten,
Federal Republic of Germany.
• Kellogg Rust/Westinghouse gasi-
fier—Waltz Mill, PA.
Data are available on varied sulfur and
nitrogen species in many gasification
process and discharge streams. How-
-------
ever, not all of the source test facilities
from which the data were collected are
at the same level of development nor
were the various test programs con-
ducted to provide uniform data sets for
comparison among processes. There-
fore, by necessity, the distribution and
fate of the coal sulfur and nitrogen
among the major output streams from
each gasifier have been selected as the
basis for this review. Data from bench-
scale units and laboratory models, al-
though fundamental and necessary,
have been excluded from this report.
Thus, only data from pilot-scale or
larger units have been included.
The most comprehensive data set
available is for the vapor phase species.
Data on sulfur and nitrogen species
present in aqueous output streams are
available for most of the gasification
processes just listed. The aqueous spe-
cies are important to the design and op-
eration of commercial facilities. How-
ever, flow data for the aqueous streams
in the smaller pilot-scale facilities gen-
erally were estimated to be so low as
not to contribute significantly to the fa-
cility mass balance approximations.
Very few data are available on the
chemical forms of the sulfur and nitro-
gen present in the ash or slag from
these processes. The leaching charac-
teristics of these solid effluents under
various regimes, along with the sulfur
and nitrogen species present in the
leachates, are discussed in another
report.
Objectives
The objective of this study was to
summarize the data on the fate of sulfur
and nitrogen in gasification processes.
This summary was intended to make
the relevant data more accessible. Thus,
the accumulated data can be more eas-
ily used to form a basis for understand-
ing. The scope of this summary in-
cluded low- and medium-Btu
gasification process source test and
evaluation data on fixed- and entrained-
bed facilities and process characteriza-
tion data on entrained- and fluidized-
bed facilities, all of which were pilot or
demonstration scale.
Summary
The fate of coal sulfur in gasification
processes generally is well defined by
the available data. Ten of the 11 gasifi-
cation tests reviewed have a sulfur
mass accountability within ±20 percent.
Since the data acquisition periods were
relatively short, 24 to 48 hours in most
cases, this degree of accountability with
limited time-phasing and replication of
samples should be considered quite
satisfactory. Sulfur mass accountability
was poor at the Chapman facility (less
than 40 percent). This may have been
due in part to the experimental tech-
niques in use at that time (1977) which
were not well refined. Insufficient data
were available from the Koppers-Totzek
facility at Modderfontein to provide an
estimated sulfur balance. Figure 1 pre-
sents a summary of the sulfur mass ac-
countability data for the 11 gasification
tests reviewed. The calculated uncer-
tainty in the overall accountability is
shown in the figure for one of the facili-
ties (Foster-Wheeler/STOIC). The uncer-
tainty in the accountability was not de-
termined for all of the processes
presented. However, the uncertainty in
the process measurements and analyti-
cal data is considered to be similar for
the other tests; therefore, the uncer-
tainty in the overall accountability is of
similar magnitude.
The fate of coal nitrogen is less clear.
Five of the processes reviewed were air
blown low-Btu gas producers. There-
fore, the mass of diluent nitrogen (IS^) in
the air feed far outweighed the coal ni-
trogen. Calculating coal nitrogen ac-
countability by excluding diluent N2 in
the feed air or N2 contaminant in the
oxygen feed (as in the Kosovo facility)
and excluding diluent N2 in the product
gases yields low overall accountability
ranging from less than 3 percent to
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about 70 percent. Total inlet nitrogen
accountability is better: 7 of the 11 pro-
cess tests show total nitrogen mass ac-
countability within 10 percent. Some of
the coal nitrogen may be converted to
N2 during gasification. With large N2
feed rates relative to the coal nitrogen
feed rate, this conversion becomes im-
measurable at the production scale of
these facilities. The low accountability
for coal nitrogen when diluent N2 is ex-
cluded is not an a priori proof of the
magnitude of conversion of coal nitro-
gen to N2. The total nitrogen account-
ability for the Texaco process at
Ruhrchemie provides a partial proof of
very low coal nitrogen conversion to N2.
At that facility an extremely small
amount of N2 enters the system as an
impurity in the feed oxygen. The coal
nitrogen is found predominantly
(85 percent) in the raw product gas as
reactive species; however, a small
amount of IM2 is detected in the product
gas. Figure 2 summarizes the coal nitro-
gen accountability with the exclusion of
N2; Figure 3 presents the total nitrogen
accountability for each facility (includ-
ing N2).
As stated previously, some of the
mass accountability data may have
been affected adversely by the rela-
tively unsophisticated experimental
techniques in use at the time. The data
compiled in this summary report origi-
nated from gasification test and evalua-
tion projects conducted over 8 years.
During this time, the measurement
techniques and quality control require-
ments were modified and evolved, so
that no single consistent set character-
izes all of the data.
700-1
Some outlet stream data not available
(generally flow rates for low volume
oil/tar condensates and aqueous
effluents inaccessible for measurement)
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Some outlet stream data not available
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tar/oil condensates and aqueous
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Nitrogen content of
Solids not Available
Accountability of
KRW-PDU Gasifier Unit
Figure 3. Nitrogen accountability (including /V2/
^Accountability of
I KRW-PDU Process
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Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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