United States
                   Environmental Protection
 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).

                     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,
  • Lurgi-type gasifier—Kosovo,
  • 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

  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.

  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
    100 A


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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.
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
                   (generally flow rates for low volume
                   tar/oil condensates and aqueous
                   effluents inaccessible for measurement)
                                                       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
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                               Cincinnati OH 45268
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