United States Industrial Environmental Research EPA-600/7-79-200
Environmental Protection Laboratory August 1979
Agency Research Triangle Park NC 27711
Pollutants from Synthetic
Fuels Production:
Coal Gasification
Screening Test Results
Interagency
Energy/Environment
R&D Program Report
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports m this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide-range of energy-related environ-
mental issues.
EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for publication. Approval does not signify that the contents necessarily reflect
the views and policies of the Government, nor does mention of trade names or
commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
EPA-600/7-79-200
August 1979
Pollutants from Synthetic Fuels Production
Coal Gasification Screening Test Results
by
J. G. Cleland, S. K. Gangwal, C. M. Sparacino,
R. M. Zweidinger, D. G. Nichols, and F. O. Mixon
Research Triangle Institute
P. 0. Box 12194
Research Triangle Park, North Carolina 27709
Grant No. R804979
Program Element No. EHE623A
EPA Project Officer: N. Dean Smith
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park. NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
-------
POLLUTANTS FROM SYNTHETIC FUELS PRODUCTION:
COAL GASIFICATION SCREENING TEST RESULTS
ABSTRACT
Coal gasification test runs have been conducted in a semi batch, fixed-bed
laboratory gasifier in order to evaluate various coals and operating conditions
for pollutant generation. Thirty-eight tests have been completed using char,
coal, lignite, and peat. Reactor temperatures ranged from 790°C to 1035°C
with high carbon and sulfur conversions in the bed.
Extensive analyses were performed for organic and inorganic compounds and
trace elements in the tars and hydrocarbon oils, aqueous condensates, and
reactor residues resulting from the gasification tests. Over 300 compounds
were identified from the various gasifier streams, and more than 100 of these
compounds were quantified for several of the test runs.
Statistical analyses have been performed on the data. The quantity and
composition of the various effluents have been examined in relation to coal
type and operating variables. Results are reported for sulfur species in the
product gas stream, for consent decree pollutants contained as volatile organic
compounds in the product gas, for phenol and related compounds in the aqueous
condensate and tar/oil sample, and for polynuclear aromatic hydrocarbons (PNA)
species in the tar/oil.
m
-------
TABLE OF CONTENTS
Section Page
Abstract iii
List of Figures v
List of Tables vi
Acknowledgments viii
1.0 Introduction 1
2.0 Screening Test Conditions 4
2,1 Fossil Fuels Gasified 4
2.2 Reactor Operating Conditions 4
2.3 Effluent Sampling and Chemical Analysis 6
3.0 Experimental Results 10
3.1 Reactor System Behavior 10
3.2 Chemical Analysis Results 13
4.0 Material Balance Results 34
4.1 Computation Procedure 34
4.2 Material Balance Adjustments 42
4.3 Trace Element Balances 43
5.0 Statistical Analysis 48
5.1 Linear Regression Technique 48
5.2 Statistical Analysis Results: Phase I 51
5.3 Statistical Analysis Results: Phase II 54
6.0 Conclusions 69
References 73
Appendices
I. Signal Processing System 76
II. Pollutant Production Factors 82
iv
-------
LIST OF FIGURES
Number Page
1 Gasifier and sampling train 2
2 Tar partitions 22
3 Production factors for major pollutants from run no.16 with
Illinois No.6 coal 23
4 Production factors for major pollutants from run no.21 with
Illinois No.6 coal 24
5 Production factors for major pollutants from run no.23 with
Illinois No.6 coal 25
6 Production factors for major pollutants from run no.41 with
Western Kentucky No.9 coal 26
7 Production factors for major pollutants from run no.25 with
Montana Rosebud coal 27
8 Production factors for major pollutants from run no.33 with
Wyoming subbituminous coal 28
9 Production factors for major pollutants from run no.35 with
Wyoming subbitumino'us coal 29
10 Production factors for major pollutants from run no.36 with North
Dakota Zap lignite coal 30
11 Production factors for major pollutants from run no.43 with North
Dakota Zap lignite coal 31
12 Comparison of the observed and predicted tar organic base yields
for the RTI gasifier screening tests 63
13 Comparison of the observed and predicted tar organic acid yields
for the RTI gasifier screening tests 64
14 Comparison of the observed and predicted tar yields for the RTI
gasifier screening tests 65
15 Comparison of the observed and predicted H2S yields for the RTI
gasifier screening tests . 66
16 Comparison of the observed and predicted COS yields for the RTI
gasifier screening tests 67
17 Signal processing hardware configuration 77
18 Signal processor function relative to gasification tests 78
19 Signal processor function relative to GC analyses 79
20 Signal processing software system 81
-------
LIST OF TABLES
Number Page
1 Analysis of Fuels Gasified 5
2 Experimental Test Parameters and Commercial Gasifier Operating
Conditions 7
3 Operating Conditions—Screening Tests 8
4 Residue (Bottom Ash) Analyses 12
5 Compounds Identified in Gasifier Effluents 14
6 Pollutant Production 16
7 Reactor Gas Streams 19
8 Tar Pollutants 20
9 Weight Percent of Individual Fractions Obtained from Crude Tar
Partitioning : 21
10 Primary Elements of Tars 33
11 Elemental Balances for RTI Screening Runs 35
12 Material Balance Results for Run No.16 (Illinois No.6
Bituminous Coal) 36
13 Material Balance Results for Run No.*25 (Montana Subbituminous
Coal) 37
14 Material Balance Results for Run No.33 (Wyoming Subbituminous
Coal) 38
15 Material Balance Results for Run No.36 (North Dakota Lignite
Coal) 39
16 Material Balance Results for Run No.41 (Western Kentucky
Bituminous Coal) 40
17 Trace Metal Analyses (Tar and Condensate) 44
18 Trace Metal Analyses—Residue (Bottom Ash) 45
19 Comparison of Trace Element Analysis Results 47
20 Important Gasifier Operating Parameters 49
21 Important Pollution Production Parameters and Gasifier
Performance Variables 50
22 Summary of the Statistical Analysis of the RTI Gasifier Screening
Runs Using All Independent Variables in Table 20 52
-------
LIST OF TABLES (continued).
Number Page
23 Ranking of Operating Parameters in the Order of Importance in
24
25
26
II-l
II-2
II-3
II-4
II-5
II-6
II-7
II-8
II-9
Influencing Pollutant Production
Ranking of the Most Important, Independent Operating
Influencing Pollutant Production
Parameters
55
56
-Summary of the Statistical Analyses of the RTI Gasifier Using
the Most Important, Independent Operating Variables
Summary of Linear Models for Pollution Production and
Performance
Pollutant Production in Coal Gasification—Run No. 16:
No. 6 Coal
Pollutant Production in Coal Gasification— Run No. 21:
No. 6 Coal
Pollutant Production in Coal Gasification—Run No. 23:
No. 6 Coal
Pollutant Production in Coal Gasification— Run No. 41:
Kentucky No. 9
Pollutant Production in Coal Gasification— Run Mo. 25:
Rosebud Coal
Pollutant Production in Coal Gasification— Run No. 33:
Subbituminous Coal
Pollutant Production in Coal Gasification— Run No. 35:
Subbituminous Coal
Pollutant Production in Coal Gasification— Run No. 36:
Dakota Zap Lignite
Pollutant Production in Coal Gasification — Run No. 43:
Dakota Zap Lignite
Gasifier
Illinois
Illinois
Illinois
Western
Montana
Wyoming
Wyoming
North
North
58
60
83
84
85
86
87
88
89
90
91
VII
-------
ACKNOWLEDGMENTS
The project "Pollutants from Synthetic Fuels Production," has been
sponsored by the U.S. Environmental Protection Agency (EPA) through the Fuel
Process Branch, Industrial Environmental Research Laboratory, at Research
Triangle Park, North Carolina. The guidance of Dr. N. Dean Smith, Project
Officer, Mr. William J. Rhodes, Program Manager, and Mr. T. Kelly Janes,
Branch Chief, are gratefully acknowledged.
Substantial contributions and collaboration have been provided by a
number of personnel at the Research Triangle Institute (RTI). These persons
include David Green, John Pierce, William McMichael, Robert Truesdale, Edward
Bean, and Tina Webb of the Process Engineering Department. From the Environ-
mental Measurements Department, major inputs were provided by Peter Grohse and
Denny Wagoner, as well as Douglas Minick, Jesse McDam'el, Steven Frazier, and
Kenneth Tomer of the Chemistry and Life Sciences Division. Deborah Whitehurst
and Ty Hartwell participated in the statistical analysis of data. William
Drake assisted in signal processor software development.
Mr. Fred Schwarz of the Process Engineering Department manufactured and
fabricated essentially the complete gasification facility in the RTI machine
shop. His insights and handiwork gave rise to functional and productive
hardware.
vm
-------
1.0 INTRODUCTION
This project is being conducted by the Research Triangle Institute in
order to develop an understanding of the nature and extent of the production
of environmental pollutants in synthetic fuels processes. Screening test runs
have been conducted in a laboratory scale nonisothermal reactor. Eight distinct
coals or related materials have been gasified under various operating con-
ditions so as to screen the pollutants produced by a variety of feed materials
considered to be candidates for coal gasification within the United States.
A report on the facility construction and preliminary tests was pre-
viously prepared. That report described the design and construction of the
gasification facility including the reactor and associated feed devices, the
sampling and analysis system development, and the on- and off-line data
collection and evaluation capability. (See Figure 1).
Some 38 gasification tests were conducted in order to (1) establish the
range of operating conditions over which the laboratory reactor can be success-
fully operated, (2) establish the operating characteristics of the gasifier
and ascertain the extent to which its results match those of large scale
units, (3) conduct extensive chemical analysis work aimed at the identification
of the chemical species in the various effluents from the gasifier, (4) com-
plete approximate quantitative analyses on the gasifier effluents which are
present in sufficient quantities to be environmentally significant, and (5)
establish operating conditions for parametric studies. The fossil fuel
sources which have been gasified include FMC char, Illinois No.6 coal, Western
Kentucky No.9 coal, Pittsburgh No.8 coal, Montana Rosebud coal, Wyoming sub-
bituminous (Smith-Roland) coal, North Dakota Zap lignite, and North Carolina
humus peat. These tests have been conducted both with externally supplied
heat as well as with heat derived from partial combustion taking place as a
part of the overall gasification process.
-------
STEAM GENERATION SYSTEM
ro
SCRUBBER
STEAM FURNACES
WATER SUPPLY
SAMPLE PORTS
RESIN
CARTRIDGES
CONTINUOUS
ANALYZER
|J7J>_' HEACTOR_ _ _ _ _ |
REACTOR SYSTEM
AND NONVOLATILE J
SAMPLING
~]
I I
PRODUCT GAS SAMPLING
ANALYSIS. METERING
| j«2
REACTANT GAS SUPPLY AND CONTROL
Figure 1. Casifier and sampling train.
-------
Operating conditions have been chosen in many cases to approximate those
of large scale gasifier operations producing low heating value fuel gas or
synthesis gas. However, coal addition has been by way of batch addition to
the reactor from a pressurized lockhopper. Thus, the coal feed has been a
batch process while the addition of air and/or steam to the reactor has
involved continuous flow throughout a gasification test run. Hence, operation
of the reactor during the screening tests is referred to as being in the
semi batch fixed-bed mode.
If the effluent concentrations for a semibatch run are averaged by integra-
tion over the time of the run to simulate the steady-state concentrations of a
continuous process, then the semibatch reactor produces effluent concentrations
which appear to provide a reasonably good simulation of gas product compositions
from full scale process gasifiers. Where comparative results are available,
the results obtained in this study have shown good agreement for such major
pollutants as sulfur compounds, phenols, total organics, benzene derivatives,
and total tar.
Companion reports are simultaneously being prepared and issued on (1) the
sampling and analysis methodology which has been developed for use in this
project and (2) the health and environmental significance of the results which
2 3
have been obtained from the screening tests. Separate reports are also
planned on related topics. One is intended on the transient behavior of the
gasification test runs relative to both reactor operation and the concentration
of effluents. Another is to be a comparison of the results of this study with
the available comparative data on pilot plant and commercial gasification
operations.
Future reports will also present information relative to parametric
studies, which examine the generation and control of potential pollutants in
coal gasification under various operating conditions. The parameters under
consideration are coal type, coal particle size, reactant flow rates, chemical
additives, and other factors. Information being generated in this-project is
intended to provide a basis for the assessment of the potential health and
environmental significance of the effluents from coal gasification processes.
The project results should also lead to process modifications and/or control
technology developments which permit substantial reductions in potential
emissions.
-------
2.0 SCREENING TEST CONDITIONS
Screening tests have been completed using selected coals, lignite, peat,
and a coal-derived char. Semibatch fixed-bed gasification was conducted to
generate, collect, process, analyze, characterize, and evaluate the pollutants
from the gasification of each feed material. Flow rates of steam and/or air
were predetermined for each run so as to achieve desired reaction temperatures.
Additionally, external furnaces were utilized to control the temperatures and
heating rates involved. An on-line signal processing system was utilized to
collect process data, to collect and analyze gas chromatograph output signals,
and to perform overall data processing functions. This POP 11/34 system and
associated equipment and software are described in an appendix.
2.1 FOSSIL FUELS GASIFIED
The eight distinct fossil fuel sources which have been studied during the
screening tests are presented in Table 1. These coals and related materials
have been subjected to determinations of free swelling index, heating value,
ultimate analysis, proximate analysis, sulfur species, and ash fusion temper-
ature. These values are typical or representative of the various coal seams
from which the samples were obtained. (It is known that the moisture content
as well as other possible parameters for a particular coal type can vary from
one sample to another. Representative analyses, as shown in Table 1, were
used for the screening test studies. However, individual analyses for the
particular feed material utilized for each gasifier test run are being
performed for the feed materials in the parametric test runs of this research
program).
2.2 REACTOR OPERATING CONDITIONS
The air-to-coal ratio, steam-to-coal ratio, reactor pressure and tempera-
ture were selected for many of the screening tests in order to obtain con-
ditions comparable to those used in pilot plant or commercial coal gasification
-------
TABLE 1. ANALYSIS OF FUELS GASIFIED
en
Fuel
U. Kentucky
FHC Char
Illinois
No. 6
Bituminous
Montana
Rosebud
Subbi luminous
N.C. Humus
Peat
Pittsburgh
No. 8
Wyoming
Subbi luminous
N. Dakota
Lignite
M. Kentucky
No. 9
Bituminous
Btu/lb (inc. Volatile Fixed
moisture & Moisture Ash Hatter Carbon
ash) XXX X
11,090 1.90 19.70 7.80 71.50
11,331 6.85 13.52 32.58 47.05
9,004 21.19 8.86 31.56 38.39
4,975 45.98 3.67 31.81 16.54
12,288 3.08 11.09 29.16 56.67
7,880 15.56 6.31 38.30 39. 30
7,880 29.63 6.39 28.57 35.41
12,130 7.03 7.83 38.78 46.36
Sulfur:
Sulfate
Organic
Pyritic Carbon Hydrogen Oxygen Nitrogen FSI
Total X X X X X
1.80 74.02 1.48 1.70 1.3 <1 .0
0.15
1.16
1.71
3.02 63.26 5.37 13.46 1.35 3.5
0.17
0.21
0.21
0.59 53.95 6.87 . 28.53 1.20 0.0
0.05
0.06
0.01
0.12 30.22 5.34 59.84 0.81 0.0
<0.01
1.28
1.24
2.53 72.29 3.45 8.62 1.95 7
0.07
0.08
0.40
0.55 56.80 5.94 30.02 0.38 0
0.01
0.54
<0.01
0.56 46.82 9.85 35.63 0.73
0.05
2.90
1.83
4.78 67.36 5.58 13.68 1.08 4
Ash
Fusion
Temp.
°F
2600*
2350°F**
(2030-
2730°F)
2280*
(2150-
2240°F)
2270°F**
(2060-
2780°F)
2280°F*
(2110-
2460°F)
2340°F**
2090°F**
(1970-
2400°F)
*As received--*!) and XO include that portion in moisture
"Mean temperature
-------
reactors. Table 2 presents various experimental test conditions for the RTI
tests in relation to selected gasifier operating conditions. While the air-
to-coal ratio is generally lower for the RTI tests, most of the conditions
which have been examined have shown a quite close correspondence to those for
pilot scale and commercial fixed-bed gasification processes.
Actual quantities of coal, steam, air, and tar involved in various
screening tests are presented in Table 3. Steam-to-carbon ratios have been
investigated over the range from 0.4 to 18 g/g and air-to-carbon ratios from
0 to about 4 g/g. Although the air-to-coal ratio has varied depending upon
the intended method of supplying heat to the reactor, the steam-to-coal ratio
has been predominantly in the range of 0.5 to 3.0 g/g. (Excessive steam
simply passes through the reactor and results in additional aqueous condensate
formation in the reactor condenser system). Maximum bed temperatures have
been in the range of 900 to 1000°C. Carbon conversions have ranged from 52
to near 100 percent, oxygen-to-coal ratios from 0.0 to 0.9 g/g, and steam-to-
oxygen ratios from 0.9 to infinite. Both internal and external heat has been
supplied to the reactor system.
2.3 EFFLUENT SAMPLING AND CHEMICAL ANALYSIS
The effluent gas stream from the fixed-bed reactor passes through a
particulate trap which is insulated to maintain hot gas conditions. This is
immediately followed by a refrigerated condenser unit which remov.es aqueous
condensate and low volatile organic material at the system pressure. The
condenser unit is followed by a backpressure regulator.
A glass sampling system has been installed on the low pressure side of
the backpressure regulator. This system includes ports for grab samples and
a valving system for direct adsorbent cartridges. A port also exists for
removal of a continuous gas stream for infra-red analysis. Further, the
primary gas stream passes through a continuous dry gas meter to measure the
total volumetric flow of the effluent stream.
Raw gas samples were collected periodically during the gasification test.
These samples were contained in special glass sample bulbs and maintained
under controlled conditions in a specially designed sample storage chest.
-------
TABLE 2. EXPERIMENTAL TEST PARAMETERS AND COMMERCIAL GASIFIER OPERATING CONDITIONS
Air/Coal g/g
Steam/Coal g/g
Carbon Conversion %
Coal Residence Tine (mln.
Tar Produced g/g
Gas Produced SCF/lb
HHV Btu/SCF
Throughput Ib/hr ft2
Coal Type
Pressure psia
Mesh Size
Maximum Temperature °C
Heatup Time to 800°C
(mln.)
Gas Composition
CO
C02
CH4
H2
N2
H2S
HHV Btu/SCF
RTI Tests
21
1.1
3.1
97
340
0.035
48
106
16
Illinois
No. 6
200
8 x 16
1015
20
16
18
5.4
30
30
0.4
200
23
2.2
1.2
96
300
0.033
56
96
19
Illinois
No. 6
200
8 x 16
1050
11
10
18
3.1
13
55
O.fi
100
25
1.7
0.50
99.7
180
0.018
41
142
30
(•ion tana
Subbit.
200
8 x 16
1060
3
24
9.1
2.4
13
52
0.06
140
32
1.5
0.37
99.5
110
0.011
32
183
44
Wyoming
Subbit.
200
8 x 16
1050
5
29
9.1
5.7
20
36
0.07
210
33
1.5
0.36
98.9
110
0.012
35
201
45
Wyoming
Subbit.
200
8 x 16
1040
8
32
4.9
5.7
20
37
0.07
210
35
1.7
0.37
97
110
0.029
40
128
46
Hy owing
Subbit.
200
8 x 16
910
23
16
12
3.7
14
54
0.08
130
METC*
2.3
0.31
98.7
120-540
0.022
47
153
107
Illinois
No. 6
315
2" x 0
—
__
21.8
6.9
2.0
17.8
51.5
156
5,6
Lurgi
3.0
1.5
95
60
NA
52
195
248
Subbl luminous C
New Mexico
300
1.75" x 0.08"
--
„
17.4
14.8
5.1
23.3
38.5
NA
200
Wellman
Galusha5
3.5
0.4
99+
120-540
0.06
NA
168
899
Bituminous
ATM
2" x 1.25"
1300
__
28.6
3.4
2.7
15.0
50.3
NA
170
Uoodal 1
Duckham5
2.3
0.25
99
NA
0.075
NA
175
70
HVCB
ATM
1.5" x 0.25"
1200
--
28.3
4.5
2.7
17.0
47.2
0.3
170
-------
TABLE 3. OPERATING CONDITIONS—SCREENING TESTS
oo
^""-•^Test
Coal ^v^
Steam (g)
Air (g)
Coal (g)
Air/Coal
Steam/Coal
Air/Steam
T * °C
max
Carbon Conversion (%)
Sulfur Conversion (X)
Tar Yield (g/g Coal)
RTI Test Number
16
Illinois No. 6
3704
1350
1569
0.86
2.4
0.35
941
89
93
0.036
21
Illinois No. 6
4713
1720
1543
1.1
3.1
0.35
984
97
98
0.033
23
Illinois No. 6
1952
3288
1594
2.1
1.2
1.8
1020
96
95
0.033
41
Western Kentucky
1390
3060
1250
2.5
1.1
2.2
1034
99.8
98
0.030
25
Montana
748
2482
1491
1.7
0.50
3.4
1006
99.7
85
0.018
33
Wyoming
500 '
2097
1396
1.5
0.36
4.2
1010
98.9
91
0.012
35
Wyoming
527
2461
1420
1.7
0.37
4.6
790
97
85
0.029
36
North Dakota
639
1939
1444
1.3
0.44
3.1
916
99.7
91
0.013
43
North Dakota
422
2022
1458
1.4
Kl.29
4.8
914
99.4
80
0.0072
Mime averaged maximum bed temperature.
-------
These samples were systematically subjected to gas chromatographic analysis
for a range of specific compounds including ethane, ethylene, and acetylene;
benzene, toluenes, and xylenes; hydrogen sulfide, carbonyl sulfide, and other
sulfur species. Moreover, a continuous gas monitor was utilized in all
screening tests in order to obtain a continuous analysis for methane, carbon
monoxide, carbon dioxide, and hydrogen.
The adsorbent cartridges have utilized XAD-2 resins for the volatile
organic constituents. A single cartridge was used throughout the initial
portion of the run, the so-called surge period. A valving arrangement
permitted switching of the cartridge to a fresh resin for utilization during
the so-called steady-state period, which presumably represents primarily the
char gasification process. These XAD-2 resins were extracted with, methylene
chloride; the extracts were subjected to GC/mass spectrometer analysis.
The condensate collection container was drained periodically throughout
a run with the content being accumulated for a complete gasification test.
This mix of aqueous condensate and low volatile organic material was sub-
jected to phase separation followed by a detailed chemical partitioning
process. The aqueous phase was extracted with methylene chloride to remove
residual organic constituents. The low volatile organic phase was extracted
so as to obtain tar acids, tar bases, polar neutrals, nonpolar neutrals, PNA,
2
and hexane insoluble chemical constituents.
The effluents from screening test runs have been subjected to a wide
variety of chemical and bioassay tests in order to characterize and evaluate
3
these materials. Individual reports have been prepared on the sampling and
analysis scheme as well as the environmental/health aspects of the results
2 "5
which have been obtained. Additional reports are under preparation to
describe the results of parametric runs using the fixed-bed coal gasification
unit.
-------
3.0 EXPERIMENTAL RESULTS
Chemical analysis results have been obtained for the raw gas bulb samples,
the XAD-2 adsorbent resin samples, the low volatile organic material (tar),
the aqueous condensate, and bottom ash, which remained within the reactor.
The results include continuous monitor values for four primary gases, GC
analyses for a variety of hydrocarbon and sulfur species gases, GC/MS analyses
for volatile and low volatile organic compounds, plus a variety of elemental
determinations by atomic absorption and other techniques.
3.1 REACTOR SYSTEM BEHAVIOR
A detailed examination of the temperature profiles throughout various
screening test runs was completed. These results indicate that (1) the
initial temperature distribution undergoes considerable modification early in
a run (surge period) but maintains a common character throughout the steady-
state period in most cases, and (2) severe temperature gradients occur at or
near the top of the fixed-bed of solids throughout a run. The surge period
is generally of relatively short duration, e.g., 20 minutes, and is indicated
by that period over which the methane concentration in the raw effluent gas
is 2 percent, by volume, or greater. Thus, reasonably uniform temperature
control was obtained over the duration of the char gasification process
(steady-state period).
Results that have been obtained with various coals in the RTI gasification
tests indicate that the degree of desulfurization during partial gasification
is always higher than the carbon conversion. Sulfur in the resulting gas is
present mainly in the form of hydrogen sulfide. Recent research7 conducted
in Germany has also indicated that during the gasification of coal at tempera-
tures about 950°C, rapid degassing takes place which involves desulfurization
of the coal, with up to 55 percent of the sulfur being removed in the first
four seconds. The resulting material is a coke or char which reacts with
oxygen and/or steam to produce carbon monoxide, carbon dioxide, and hydrogen.
Raw gas analyses indicate a decrease in hydrogen sulfide concentration
with time followed typically by a period of level (constant) concentration,
or in some cases, an increase. Carbonyl sulfide concentrations were found
10
-------
generally to initially decrease and then level off or follow the hLS pattern.
These concentrations of carbonyl sulfide generally were found to be between
one to two orders of magnitude lower than those for the hydrogen sulfide,
Methanethiol and thiophene concentrations for all tests were found to undergo
an early decrease from an initial maximum value to levels below the detection
limits of the gas chromatograph being utilized, i.e., below 1 ppm by volume.
Additional work is, of course, needed in elucidating the mechanisms for
the formation of sulfur species. It is generally believed that pyritic
compounds give rise to hydrogen sulfide under the reducing conditions typical
in coal gasification processes. Other sulfur compounds such as methanethiol,
ethanethiol, thiophene, etc., may well result from the decomposition of
organically bound sulfur in the coal material. An additional consideration is
that elemental sulfur may well exist in the gas phase.
Considering the behavior of the lower sulfur coals tested, the surge
phase levels of volatile organic sulfur compounds, e.g., methanethiol and
thiophene, are found to be much lower than those for the high sulfur Illinois
No.6 coal. For reactive coals, e.g., Wyoming subbituminous and Montana
Rosebud, the levels of devolatilized organic sulfur compounds were reduced to
lower than minimum detectable levels as measured with an FPD detector on the
GC within less than 15 minutes from the introduction of the coal into the
reactor. Ninety percent or more of the Cg-Cg aromatics also evolved during
the first 15 minutes of these tests.
Concentration of the inorganic sulfur compounds HLS and COS were generally
found to follow the C0« concentration. These concentrations reached a minimum
about midway during the tests carried out over 1000°C, but decreased mono-
tonically for tests carried out at lower temperatures (900°C). In some cases
the concentrations of H^S and COS were found to increase near the end of a
run, indicating that relatively inactive sulfur-containing compounds in the
reactor were being converted after almost all of the carbon content had been
converted.
The residue (bottom ash) analyses for various screening test runs are
presented in Table 4. These values indicate that substantial carbon conversions
were obtained in almost all of the screening test runs. Sulfur conversions
generally were not as high, indicating that while there may be char species
11
-------
TABLE 4. RESIDUE (BOTTOM ASH) ANALYSES
Volatile Matter
Fixed Carbon
Moisture
Ash
C
H
N
S
Cl
0 (difference)
Organic Sulfur
Pyritic Sulfur
Sulfate Sulfur
X
I
%
X
I
X
X
%
X
X
X
X
X
Heating Value (Btu/lb.)
F.S.I..
16
2.04
34.46
0.15
63.35
35.90
0.29
0.32
1.06
HA
-
NA
NA
NA
3890
0
21
4.80
11.14
0.46
83.60
14.51
0.'43
0.53
0.43
< 0.01
0.04
0.24
0.09
0.10
. 1990
0
23
6.58
10.37
0.68
82.37
15.57
0.52
0.57
0.92
NA
-
0.40
0.25
0.27
2263
0
25
5.88
-
0.66
96.50
1.77
0.20
0.06
1.16
NA
-
0.07
0.04
1.05
< 50
0
RTI Test
33
9.94
9.76
2.58
77.72
15.28
1.19
0.14
1.20
0.05
1.84
1.04
0.15
0.01
2700
1/2
Number
35
2.00
26.76
2.53
68.71
24'. 81
0.71
0.31
1.28
0.03
1.62
0.86
<.01
0.42
3933
NA
36
1.59
2.66
3.76
91.99
2.52
0.15
0.06
1.03
0.08
0.41
0.15
0.80
0.08
309
1/2
41
2.76
0.10
o.n
97.03
1.64
0.02
0.08
0.88
0.04
0.20
0.83
0.03
0.02
340
1/2
43
14.38
_
4.69
88.51
5.24
1.63
0.00
2.21
0.09
_
0.44
0.06
1.71
544
NA
NOTE: NA = Not Analyzed.
C and H are exclusive of moisture.
-------
possessing relatively low reactivity carbon, the residual sulfur compounds are
quite resistant to gasification. This is particularly true for sulfur which
has been oxidized to, or originally was, sulfate sulfur. It is of interest to
note, that in almost every case the organic sulfur content also exceeded the
sulfate sulfur level within the reactor residue. The two exceptions are for
runs 25 and 43 which involved Montana Rosebud and North Dakota lignite feed
materials, respectively. (The individual carbon conversion and sulfur conver-
sion values for each of the runs shown in Table 4 can be found in Table 3).
3.2 CHEMICAL ANALYSIS RESULTS
The gas chromatograph/mass spectrometer analysis of the various samples
and extracts (partitions) obtained from the sampling and analysis programs
associated with the gasification tests have resulted in the identification of
more than 300 organic species. Additional compounds have been quantitated by
direct gas chromatographic analysis. Atomic absorption measurements have been
performed on the various effluents to determine trace element compositions.
Special attention has been given to compounds which were judged to have
environmental significance with less attention being paid to organic species
which currently available information indicates as being harmless. Criteria
utilized for the analysis of screening test samples for this selectivity were
twofold: first, compounds were specifically selected for study if they
possessed moderately toxic to severe health hazard potentials as evidenced by
a toxic threshold value less than 17 mg/m and were suspected to occur in the
gasifier effluents; and secondly, any compound present in the effluents at
3
concentrations of 5 mg/m or greater was given consideration. The list of
compounds which have been detected throughout the screening test sequence is
provided in Table 5. (It should be noted that some of the compounds listed
were detected only in the aqueous condensate which was collected from the
condenser unit on the effluent stream. The compounds thus identified may have
been formed as a result of reaction of precursors in the condenser system.)
The quantity of selected compounds produced in various of the screening
test runs per unit mass of carbon converted in the gasifier is presented in
Table 6. It may be noted that the sulfur species and phenolic type compounds
13
-------
TABLE 5. COMPOUNDS IDENTIFIED IN GASIFIER EFFLUENTS
(Arranged by MEG Category)
MEG Category Name
Category
Name
MEG Category
Name
1. Aliphatic Hydrocarbons
methane
ethane
propane
n-butane
(sobutane
n-pentane
Isopentane
n-hexane
2-methylpentane
3-methylpentane
n-heptane
n-octane
n-nonane
n-decane
n-undecane
n-dodecane
n-tHdecane
n-tetradecane
n-pentadecane
n-hexadecane
methylcyclobutane
cyclopentane
cyclohexane
d1methyleye1ohexane
trlmethy1cyclohexane
cyclooctane
dimethyIdecahydronaphthalene
ethene
propene
butene
Isobutene
hexene
1-pentene
2-methy1-1-butene
1,3-butadiene
pentadlene
cyclopentene
cyclohexene
cyclopentadlene
ethyne
propyne
2. Alkyl Hal ides
d1ch1oromethane(artifact)
trlchloromethane(artifact)
carbon tetrachlorfde
(artifact)
3. Ethers
dlethylether
pheny1-2-propynyIether
1-methoxynaphtha1ene
2-(iiethoxynaph tha 1 ene
3,6-d1mthoxyphenanthrene
2-methoxyf1uorene
5. Alcohols
3,5,5-trlmethyl-l-hexano!
7. Aldehydes, Ketones
acetaldehyde
butanal
pentana 1
p-hexanal
n-heptanal
n-octanal
n-nonanal
undecanal
dodecanal
1. (Continued)
benzaldehyde
dlmethylbenzaldehyde
acetone
methylIsopropyl ketone
butanone
1-pheny1-1-propanone
2-pentanone
acetophenone
o-hydroxyacetophenone
m-hydroxyace tophenone
benzophenone
9-fluorenone
benzofluorenone
d1hydroxyanthraqui none
tetrahydroanthraqui none
phenanthrfdone
8. Carboxylic Acids and Derivatives
acetic add
benzole add
benzamlde
ethyl acetate
a thy 1 benzyl acetate
methyl benzoate
isobutyl cinnamate
dibutyl phthalate(artifact)
d1isobutyl phthalate
(artifact)
dlcyclohexyl phthalate
(artifact)
9. NUHles
acetonltrile
cyanobutadiene
benzonitrile
2.2'-dicyanobiphenyl
10. Amines
aniline
diphenylamine
benzidlne
1-aminonapnthaiene
N-methyl-o-toluidine
13. Thiols, Sulfides, and Bisulfides
methanethiol
ethanethiol
2,3,4-trithiapentane
dimethyl sulfide
dimethyl disulfide
trlthiahexane
d1pheny1 disulfide
15. Benzene, Substituted Benzene
Hydrocarbons
benzene
toluene
o-xylene
m-xylene
p-xylene
ethyl benzene
styrene
methylstyrene
ethylstyrene
n-propyibenzene
Isopropylbenzene
1,2-dimethylbenzene
t-butylbenzene
n-oentvlbenzene
IS. (Continued)
3,5-d1methyl-l-fsopropyl-
benzene
triethyl benzene
o-ethyltoluene
m-ethyltoluene
trlmethylbenzene
1,2,4-trimethyl-
benzene
1,3,5-trlmethylbenzene
o-d1ethylbenzene
m-d1ethylbenzene
p-d1ethylbenzene
methyltetrahydro-
naphthaiene
dimethyltetra-
hydronaphthalene
trimethyltetra-
hydronaph tha1ene
1,2,3,4-tetrahydro-
naphthaiene
5,8-d1methyl-l-n-octyl-
1,2,3,4-tetrahydronaph-
thalene
1-methyl-4-n-hepty1-
1.2,3,4-tetra-
hydronaphthaiene
bipheny1
nmthylbiphenyl
3-methylbipheny1
diphenylroethane
d1pheny1 ethane
di (ethylPheny1)
ethane
stllbeneO.2
dlphenylethene)
me thy1pheny1ethyne
d1pheny1ethyne
1,2-diphenylpropane
dlxylylethane
o-terphenyl
m-terphenyl
p-terphenyl
indan
methylindan
dimethylindan
pentamethy 1 indan
indene
methylindene
methy-l-2,3-dihydro-
indene
dlmethylindene
trimethylindene
18. Phenols
phenol
o-cresol
m-cresol
p-cresol
o-ethylphenol
in-ethyl phenol
p-ethy1 phenol
Isopropylphenol
o-allylpnenol
m-phenylphenol
2,3-xylenol
2,4-xylenol
2,5-xylenol
2.6-xylenol
14
-------
TABLE 5 (continued).
ME6 Category
Name
MEG Category
Name
MEG Category
Name
18. (Continued)
3,4-xylenol
3,5-xylenol
3-methy1-6-ethylphenol
2-methy!-4-ethylphenol
4-tert-butyl-o-cresol
di-t-butyl-4-
ethy1 phenol
trtmethyl phenol
2-hydroxynaphthalene
methy1hydroxynaphthalene
hydroxyfluorene
21. Fused Polycycllc Hydrocarbons
naphthalene
cyclobutadlbenzene
1-methyl naphthalene
methyld1hydronaphtha1ene
2-methy1naphtha1ene
ethylnaphthalsne
1sopropy1 naphtha 1ene
1-methyl-7-isopropy1-
naphthaiene
l,2-d1hydro-3,5,3-
trimethylnaphthaiene
2-benzy1 naphtha1ene
dimethyl naphtha 1ene
l,4-d1nethylnaphthalene
2,3-d1methyInaphthalene
2.6-d1methy1 naphtha 1ene
trimsthyInaphthalene
acenaphthene
acenaphthylane
methylacenaphthy1ene
3-methy1acenaphthy1ene
anthracene
9-methy1 anthracene
ethyl anthracene
phenanthrene
methylphenanthrene
1-methylphenanthrene
3-methylphenanthrene
4,5-methylenephenanthrene
propenylphenanthrene
trans-9-propenylphen-
anthrene
8-n-bu ty1phenanthrene
2,/-dimethylphenanthrene
pyrene
methylpyrene
1,2-benzanthracene
hexahydro-l,2-benz-
anthracene
methyl-1,2-benzanthracene
2.3-benzanthracene
(naphthacene)
3,4-benzophenanthrene
methylbenzophenanthrene
5,8-dlmethy1- 3,4-benzo-
phenanthrene
9,10-benzophenanthrene
(triphenylene)
1,2.3,4-tetrahydro-9,10-
benzophenanthrene
2-methyl-9,10-benzophen-
anthrens
chrysene
methylchrysene
benzo(a)pyrene
benzo(e)pyr«ne
perylene
21. (Continued)
2-n-hexylperylene
benzo(g.h,1)perylene
dibenzo(a,h)anthracene
22. Fused Non-Alternant Polycycllc
Hydrocarbons
f1uorene
nwthylfluorene
1-me thylfl uorene
dime thy If] uorene
fluoranthene
1,2,3,4-tetrahydro-
fluoranthene
benzo(a)fluorene
benzo(b)fl uorene
benzo(b)f1uoranthene
benzo(k) fluoranthene
1ndeno(l,2,3 cd)
pyrene
23. Heterocycllc Nitrogen Compounds
pyrrole
methyl pyrrole
pyrfdlne
methyl pyridlne
4-acetylpyHdlne
d1methylpyr1d1ne
tr1methylpyr1d1ne
2,4-d1methyl-6-ethy1-
pyrtdlne
2-hydroxy-4-pheny1pyri d1ne
2-hydroxy-6-phenylpyridine
3,4-d1phenylpyr1d1ne
benzopyrldlne
2,2'-d1methyl-4,4--
dlpyrldyl
indole
methylIndole
methyl-3-allylhydroindole
3-methyl-3-allyd1hydro-
indole
phenylIndole
3-methyl-2-phenylIndole
3,3'-biindolyl
quinoline
isoquinoline
methylquinpline
3-methyIguinoline
6-methylqu1noline
sthylquinollne
3-n-propylqulnol1ne
4-n-propylqu1noline
8-n-propylqu1nol1ne
<31methylqu1nol1ne
2,6-d1methylquino11ne
methylphenylquinoxalIne
4-styrylqu1nol1ne
7,8-benzoqu1noline
3-methylbenzoquinol1ne
benzimldazole
methylbenzlnrldazole
2-ethylbenzimidazole
benzylbenzimldazole
benzothlazole
2-m«thy1 -5-pheny1te trazo1e
dlphenyloxazole
acHdine
d1n«thy1acr1d1ne
acridone
carbazole
9-methylcarbazole
23. (Continued)
1,2,3,4-tetrahydrocarbazole
3-am1no-9-ethylcarbazole
vlnylphenylcarbazole
1,4-dihydro-2,3-benzo(b)
carbazole
2-am1no-4-phenyl-6-methyl-
pyr1m1d1ne*
2-am1no-5-ch1oro-4,6-
dlmethy 1 pyrlmidi ne*
4-(l,2.3,4-tetrahydro-2-
naphthyl)-morphol1ne
3-benzyHndene phthallmlde*
24. Heterocycllc Oxygen Compounds
furan
benzofuran
2-methylbenzofuran
3-methy1benzofuran
5-methy1benzofuran
7-methy1benzofuran
3,3-d1hydro-2-methylbenzofuran
dimethylbenzofuran
3,6-d1methylbenzofuran
di hydromethy1pheny1benzofuran
d1benzofuran
xanthene
25. Heterocycllc Sulfur Compounds
thiophene
2-methylthiophene
3-methylthiophene
2,3-d1methy!thiophene
2,4-dimethy1thiophene
2,5-dimethy1thi ophene
3,4-d1methy1thiophene
trimethylthiophene
i sopropy1thiophene
ethylthiophene
2-n-propyl-5-
isobutylthiophene
benzothiophene
methylbenzothlophene
dimethylbenzothiophene
trimethylbenzo-
thiophene
benzodithiophene.
me thyIbenzodithiophene
dibenzotniophene
methyldibenzothiophene
di hydrodi methy1thi eno-
thiophene
dimethylthiaindene
thiaxanthene
42. Carbon Compounds
carbon monoxide
carbon dioxide
47. Nitrogen Compounds
ammonia
hydrogen cyanide
52. Sulfur Compounds
sulfur
sulfur dioxide
hydrogen sulflde
carbonyl sulfide
carbon dlsulfide
99. Hydrogen
hydrogen
15
-------
TABLE 6. POLLUTANT PRODUCTION
produced in all streams)
g carbon
converted
Compound
hydrogen sulfide
carbonyl sulfide
niethanethlol
e thane thiol
carbon disulflde
thiopliene
methyl thiophene
hydrogen cyanide
auinon 1 a
an i 1 1 ne
qulnoline
acridine
Indole
phenol
cresols
xylenols
t rime thy 1 phenol
o-isopropyl phenol
16 21
3.8E3 3.8E3
4.0E2 2.0E2
3.9E1 8.3E1
-
7.8E1 4.9E1
1.8E3 5.9E2
3.2E2 .OE3
.3E2
.5E4
.5E1
.7E2
9.1E1
3.1EO
4.3E2 4.7E2
7.2E2 1.3E3
7.4E2
6.5E1
*" ""
23
9.8E4
5.6E2
5.2E1
2. 1EO
2.5E2
3.8E3
1.1E3
-
-
1.0E1
1.3E2
8.1E1
-
7.8E2
1.7E3
7.6E2
1.3E2
1.3E2
RTI
25
4.6E3
~'l.5E2
4.1EO
-
-
5.2E1
1.1E1
1.2E2
8.7E3
1.3EO
9.5E1
2.5EO
1.3EO
8.3E2
1.0E3
1.9E2
2.3E1
"
Test
33
3.4E3
2.0E2
2.5E1
-
-
1.6E1
1.8E2
-
-
1.6EO
I.8E1
4.3EO
-
2.7E3
8.9E2
3.1E3
5.8E1
2.0E1
Number
35
5.9E2
3.1E2
4.6E1
-
-
5.5E1
5.5E1
-
-
2.5EO
6.3EO
1.8EO
1.3EO
2.9E3
2.6E3
2.3E3
7.4E1
3.3E1
36
4.9E2
3.7E2
1.7E2
1.4E2
-
1.1E3
2.9E1
1.4E2
6.0E3
-
2.5E1
1.8E1
-
1.4E3
1.0E3
I.1E3
3.0E1
8.9EO
41
4.0E4
8.5E2
5.8E1
-
1.1EO
4.0E2
4.9E2
-
-
-
4.9E1
2.1E1
-
1.2E3
1.3E3
2.9E2
7.6E1
3.2E1
43
3.1E3
5.8E2
2.4E1
-
1.4E1
1.9E1
7.6E1
-
-
-
3.9EO
-
-
2.7E3
2.0E3
4.1E3
3.8E2
4.5E1
Note: Ammonia was not measured in these runs.
-------
TABLE 6 (continued).
Compound
benzene
toluene
xytenes
ethylbenzene
indan
in dene
dibenzofuran
fluoranthene
fluorene
naphthalene
anthracene
phenanthrene
chrysene
pyrene
perylene
16
5.0E3
3.5E4
8.9E1
3.7E1
5.9E1
4.1E2
-
4.0E2
4.8EO
1.2E3
7.1E2
2.2E2
-
1.2E2
-
21
-
-
4.4E2
4.4E2
2.4E1
9.3EO
3.5E2
7.1E2
4.3E2
4.0E3
7.7EO
1.2E3
4.3E2
4.8E2
-
23
1.4E4
5.2E3
6.3E2
4.9E2
3.4EO
3.6E2
4.5E2
7.1E2
2.5E1
4.8E3
4.1E2
1.2E3
4.6E2
5.9E2
2.0E2
RTI
25
6.6E3
1.0E3
8.9E2
5.6E2
7.1EO
1.6E2
3.5E2
3.6E2
2.4E2
5.9E2
2.0E2
5.9E2
2.4E2
3.3E2
8.9E2
Test Number
33
8.1E3
3.3E3
8.1E2
2.0E2
1.4E2
9.8E2
1.1E2
5.8E1
1.0E2
6.3E2
1.5E2
7.2E1
3.7E1
4.5E1
2.4E1
35
6.8E3
4.0E3
1.5E3
6.2E2
3.6E1
2.6E2
8.7E1
2.2E1
8.9E1
2.5E2
1.4E2
8.5E1
3.6E1
6.3E1
1.3E1
36
1.1E4
3.1E3
8.3E2
3.8E2
1.4E1
1.7E2
6.6E1
1.4E2
8.5E1
5.2E2
2.1E2
1.3E2
4.7E1
8.5E1
1.5E1
41
1.9E4
3.0E3
4.1E2
7.4E2
7.4E1
7.4E2
3.6E2
1.5E3
3.4E2
3.5E3
1.0E3
9.8E2
-
1.1E3
-
43
3.4E3
2.1E3
6.2E2
1.9E2
3.7E1
4.8E2
7.6E1
2.3E1
6.3E1
1.7E2
1.1E2
3.6E1
9.1E1
2.0E2
1.3EO
Note: Ammonia was not measured in these runs.
-------
generally dominated in terms of quantity produced. Additionally, ammonia,'
benzene, toluene, naphthalene, and phenanthrene were present at substantial
levels.
A list of selected compounds of intermediate volatility, which may easily
condense from a gasifier effluent gas stream, is presented in Table 7. The
quantity of each produced during gasification per unit of coal loaded into the
gasifier is presented for six different tests. This table also identifies
which of these compounds have been detected in products from the Morgantown
fixed-bed gas producer, as well as a Chapman-Wilputte gasification unit. *
Similar information for chemical compounds contained in the crude tar from
various screening test runs is presented in Table 8.
Additionally, the mass of the individual fractions obtained via crude tar
partitioning for the screening test runs are shown in Table 9. These values
have been averaged for the various coal types utilized in order to obtain the
relative amounts of individual partitions shown in Figure 2. As can be seen in
this figure, the total quantity of tar generated per unit mass of coal loaded
or coal converted was highest for bituminous coals, i.e., Western Kentucky No.9
and Illinois No.6, and was least for the North Dakota lignite. The Wyoming and
Montana Rosebud coals were at intermediate levels relative to tar production.
The PNA fraction was the predominant individual fraction in every case. While
the total tar produced is very nearly the same from the gasification of Wyoming
subbituminous coal and Montana Rosebud coal, the Wyoming coal resulted in
larger percentage of organic acids and less PNA compounds than from the Montana
coal.
The quantities of pollutants produced per unit mass of carbon converted
during the coal gasification process are shown graphically in Figures 3 through
11. Numerical values are also provided representing the total amount of
compound measured per unit of coal loaded into the gasifier. These bar graphs
and numbers represent total pollutant quantities generated for all the various
effluents collected. The compounds have been ranked so that the mass per unit
of carbon converted of each of the various compounds shown may be observed.
These figures represent a span of over 4 orders of magnitude in the specific
pollutant mass production quantity, as expressed in units of yg pollutant per
gram of carbon converted. Thus, it was necessary to represent these output
values in logarithmic form in order that the specific mass values resulting
could be displayed in such a comparative fashion on a single diagram.
18
-------
TABLE 7. REACTOR GAS STREAMS4*8
Compounds
9 produced/g coa)
Methyl thiophenes
Cy- thiophenes
C.-benzenes
Benzofuran
Indan
Indene
Phenol
Cresols
Xylenols
Naphthalene
Biphenyl
Olphenyline thane
Oibenzofuran
Anthracene
Phenanthrene
C, -benzenes
Acenaphthene
5
2
2
5
1
1
7
1
4
5
8
2
4
1
21
.1E-4
.OE-4
.3E-4
.4E-5
.3E-5
.2E-4
.4E-5
.8E-4*
*
.5E-4
.OE-6
.1E-7
.6E-5
.1E-6
.8E-6
NA
NA
23
4.8E-4
2.4E-4
2.2E-4
1.4E-4
1.5E-6
1.6E-4
9.9E-5
2.3E-4*
*
1.5E-3
7. OE-6
7. OE-6
3. OE-5
3.0E-10
2.0E-10
NA
NA
RTI Test
25
5.6E-6
2.5E-6
1.4E-4
2.5E-5
3.7E-6 •
7.9E-5
7.4E-5
2.5E-5
5.2E-5
9.6E-5
1.5E-6
7.4E-7
2.2E-6
1.5E-6
NA
NA
NA
No.
32
l.OE-5
3.3E-6
l.OE-4
1.6E-5
4.1E-6
4.9E-5
1.3E-4
7.1E-5
1 . 3E-4
2.6E-4
2.5E-6
l.OE-6
2.6E-6
8.1E-7
NA
3.9E-5
NA
33
l.OE-4
2.7E-6
al.lE-4
NA
7.6E-5
5.4E-4
1.2E-3
3.2E-4
1.4E-3
2.5E-4
6.3E-6
2.8E-6
1.8E-5
2.3E-6
0
2.3E-5
NA
3
2
1
2
1
5
2
7
8
3
1
7
1
1
5
35
.OE-5
.3E-5
.3E-5
.1E-4
.OE-5
.4E-4
.9E-4
.7E-4
.OE-4
.5E-5
.OE-6
.5E"-6
.3E-6
.2E-6
0
.2E-4
.OE-7
Found In
METC
Cond.
X
X
X
X
X
X
X
X
X
X
X
Found In
METC
Tar
X
X
X
X
X
X
X
X
X
X
X
Found In Found In Found In
C-W C-W C-W
Vent Gas Cond. Tar
X
X XX
X XX
X
X
X XX
X X
X
X X
C-W - Chapman-Wllputte
-------
TABLE 8. TAR POLLUTANTS4'8
(V)
o
Compounds
g produced/g coal
Quinoline
Acridine
Naphthalene
Fluorene
Dibenzofuran
Fluoranthene
Chrysene
Perylene
Anthracene
Phenol
Cresols
1
5
1
2
2
4
2
9
3
21
.OE-4
.7E-5
.9E-3
.7E-4
.5E-4
.1E-4
.7E-4
NA
NA
.7E-5
.7E-4
23
8.2E-5
5.0E-5
8.5E-4
1.5E-4
1.7E-4
4.3E-4
2.8E-4
1.2E-4
2.4E-4
1.5E-4
4.6E-4
RTI
Test
25
5.0E-5
1
2
1
9
1
1
4
1
7
1
.3E-5
.1E-4
.3E-4
.4E-5
.9E-4
.3E-4
.7E-5
.1E-4
.5E-5
.3E-4
Number
32
1
3
1
4
3
1
9
7
1
3
1
.1E-5
.8E-6
.3E-4
.6E-5
.8E-5
.4E-4
.7E-5
.4E-5
.5E-4
.8E-5
.2E-4
33
l.OE-5
2.4E-6
8.9E-5
5.7E-5
4.1E-5
3.2E-5
2.1E-5
1.3E-5
8.2E-5
1.6E-4
3.5E-4
35
1.2E-5
1.1E-5
4.6E-5
4.8E-5
4.2E-5
1.2E-5
7.0E-6
7.5E-5
7.5E-5
3.3E-4
7.7E-4
METC
NA
NA
7.2E-4
1.6E-5
1.5E-4
NA
NA
NA
NA
1.4E-5
6. OE-4
Chapman
Wilputte
1.9E-3
9.0E-5
2.1E-4
2.4E-4
NA
1.4E-4
2.9E-4
8.0E-5
6.E3-4
1.8E-4
NA
*Maximum of three samples assumed 0.034 g tar/g coal.
-------
TABLE 9. WEIGHT PERCENT OF INDIVIDUAL FACTIONS OBTAINED FROM CRUDE TAR PARTITIONING
Tar Mass (grams)
X Organic Acids
% Organic Bases
X Insoubles
% Nonpolar Neutrals
& PNA's
% Polar Neutrals
1 Tar/Coal
6
15.9
30.3
12.5
13.9
13.0
16.5
13.8
1.54
16
56.5
13.2
6.0
9.5
29.8
33.3
8.1
3.59
20
54.3
13.96
5.52
16.70
12.56
44.49
6.76
3.44
Test Number
21
5.11
10.05
7.49
10.15
13.95
53.13
5.23
3.30
23
52.33
12.9
7.2
11.3
11.1
53.6
4.0
3.26
25
26.42
11.1
4.8
2.8
7.4
68.7
5.2
1.77
26
26.46
13.3
6.6
5.4
17.2
51.4
6.0
1.78
32
14.7
14.6
5.3
6.2
16.5
51.9
5.5
1.081
Test Number
Tar Mass (grains)
X Organic Ads
X Organic Bases
X Insolubles
X Nonpolar Neutrals
X DNA's
X Polar Neutrals
X Tar/Coal
33
16.823
26.9
3.3
1.7
20.4
39.8
7.8
1.20
35
41.2
29.6
3.4
4.)
18.3
35.4
9.2
2.90
36
12.0
—
--
—
--
—
—
--
38P
1.194
9.93
1.04
1.82
- 49.68
29.94
7.59
0.159
38G
12.93
20.37
3.73
0.33
23.75
35.57
11.45
1.72
41
37.56
5.22
7.06
8.05
12.50
61.75
5.42
3.00
43
10.49
25.28
5.42
5.66
20.70
33.21
9.73
0.719
44
30
6.47
6.49
4.80
11.22
67.38
3.64
2.40
-------
TAR PARTITIONS (Averaged)
(Tar as percent of coal)
y\
iORACID
I I I I I I T
ORBASE
\\ \ \ \ n
—NPNEU-
2.78%
yu^gougcc
ooooooooc
OOOoOCOOC
S92SS939S
1.82% 1.78%
0.78%
W.Ky. #9
Wyoming Montana
N.D. Lig.
Figure 2. Tar partitions.
22
-------
Compound
Log ug pollutant/g carbon converted
Toluene
Benzene
Hydrogen Sulflde
Thiophene
Naphthalene
CresoIs
Anthracene
Phenol
Indene
FTuoranthene
Carbonyl Sulfide
Methyl thlophene
Phenanthrene
Pyrene
Xylenes
Carbon 01su1f1de
Indan
Methanethlol
Ethyl benzene
Fluorene
1 2
2.0E-2 g/g coal loaded
2.8E-3
2.1E-2
l.OE-3
6.9E-4
4.1E-4
4.0E-4
2.4E-4
2.3E-4
2.3E-4
2.3E-4
1.8E-4
T.3E-4
6.8E-5
5.1E-5
4.3E-5
2.3E-5
2.2E-5
2.1E-5
2.7E-6
Figure 3. Production factors for major pollutants from run no. 16
with Illinois No.6 coal. NOTE: Ammonia was not measured
in this run.
23
-------
Log _g pollutant/g carbon converted
Hydrogen Sulfide
Ammonia
Naphthalene
Cresols
Phenanthrene
Methylthiophene
Xylenols
Huoranthene
Thiophene
Pyrene
Phenol
Dibenzofuran
Xy1enes
Ethyl benzene
Chrysene
Fluorene
Carbonyl Sulfide
Ouinoline
Hydrogen Cyanide
Acridine
Methanethiol
Trimethy 1 phenol
Carbon Disulfide
Indan
Aniline
[ndene
Anthracene
Indole
2.1E-2
8.8E-3
2.2E-3
7.3E-4
6.8E-4
5.6E-4
4.0E-4
3.8E-4
3.3E-4
2.7E-4
2.6E-4
2.5E-4
2.4E-4
2.4E-4
2.4E-4
2.4E-4
1.1E-4
J9.2E-5
•8.0E-5
,5.1E-5
;4.6E-5
'3.6E-5
2.7E-5
I1.3E-5
4.4E-6
8.0E-6
4.4E-6
g/g coal loaded
1.7E-6
Figure 4. Production factors for major pollutants from run no. 21
with Illinois No.6 coal.
24
-------
Compound
Hydrogen Sulfide
Benzene
Toluene
Naphthalene
Thiophene
Cresols
Phenanthrene
Methyl thiophene
Phenol
Xylenols
Fluoranthene
Xylenes
Pyrene
Carbonyl Sulfide
Ethyl benzene
Chrysene
Dibenzofuran
Anthracene
Indene
Carbon Oisulfide
Perylene
Trimethyl phenol
Quinoline
Acridine
Methanethiol
Fluorene
Aniline
Indan
Ethanethiol
Log ug pollutant/g carbon converted
V 1 t t
1 £ J T
g/g coal loaded 6.0E-2
3.5E-3
3.2E-3
3.0E-3
2.3E-3
l.OE-3
7.7E-4
6.7E-4
-
4.7E-4
4.6E-4
4.2E-4
3.8E-4
3.6E-4
3.4E-4
2.9E-4
2.SE-4
2.1E-4
2.4E-4
2.2E-4
1.5E-4
1.2E-4
8.1E-5
8.1E-5
4.9E-5
3.2E-5
1.5E-5
6.1E-6
2.0E-6
1.3E-6
Figure 5. Production factors for major pollutants from run no. 23
with Illinois No.6 coal. NOTE: Ammonia was not measured
in this run.
25
-------
Hydrogen Sulfide
Benzene"
Naphthalene
Toluene
Fluoranthene
Cresols
Phenol
Pyrene
Anthracene
Phenanthrene
Carbonyl Sulfide
Indene
Ethyl benzene
Methyl thiophene
Xylenes
Thiophene
Oibenzofuran
Fluorene
Xylenols
Ethanethiol
Trimethyl phenol
Indan
Methanethiol
Quinol ine
o-isopropylphenol
Ac r1 dine
Carbon Disulfide
Log ug pollutant/g carbon
i i i
2.7E-2 g/g coal loaded
1.3E-2 |
2.5E-3
2.0E-3
l.OE-3
8.8E-4
8.2E-4
7.4E-4
6.7E-4
5.6E-4
5.7E-4
5.0E-4
4.2E-4 '
3.3E-4
3.2E-4
2.7E-4
2.4E-4
2.3E-4
1.9E-4
1.1E-4
5.1E-5
5.0E-5
3.8E-5
3.3E-5
2.2E-5
1.4E-5
J 7.4E-7
Figure 6. Production factors in major pollutants from run no.41 with
Western Kentucky No.9 coal. NOTE: Ammonia was not
measured in this run.
26
-------
Log ug poHutants/g carbon converted
i i
Ammonia
Benzene
Hydrogen Sulfide
Toluene
Perylena
Xylenes
Phenol
Phenanthrene
Naphthalene
Cresols
Fluorantnene
Pyrene
Ethylbenzene
Fluorene
Chrysene
Anthracene
Dibenzofuran
Inderte
Carbonyl Sulfide
Quinoline
Thiophene
Acridine
Trimethylphenol
Hydrogen Cyanide
Methylthiophene
Indan
Methanethiol
Indole
Aniline
4.8E-3
3.6E-3
2.5E-3
5.4E-4
4.3E-4
4.8E-4
4.2E-4
3.2E-4
3.2E-4
2.3E-4
2.0E-4
1.8E-4
1.5E-4
1.3E-4
1.3E-4
1.1E-4
9.3E-5
3.3E-5
8.0E-5
5.1E-5
2.8E-5
1.4E-5
1.2E-5
6.3E-6
5.9E-6
3.8E-6
2.2E-6
6.8E-7
S.3E-7
g/g coal loaded
Figure 7. Production factors for major pollutants from run no.25 with
Montana Rosebud coal.
27
-------
Compound
Benzene
Hydrogen Sulfide
Toluene
Xylenols
Phenol
Indene
Cresols
Xylenes
Naphthalene
Ethylbenzene
Carbonyl Sulfide
Methylthlophene
Anthracene
Indan
Dlbenzofuran
Fl uorene
Phenanthrene
Trimethylphenol
Fluoranthene
Pyrene
Chrysene
Methanethiol
Perylene
o-isopropylphenol
quincline
Thiopnene
Acridlne
Aniline
Log ug pollutant/g carbon converted
A.6E-3 q/q coal loaded
1.9E-3
1.8E-3
1.7E-3
1.5E-3
5.5E-4
5.1E-4
4.6E-4
3.5E-4
1.1E-4
1.1E-4
l.OE-4
8.5E-5
7.6E-5
5.9E-5
5.7E-5
4.1E-5
3.4E-5
3.2E-5
2.1E-5
2.5E-5
1.4E-5
1.3E-5
1.2E-5
l.OE-5
9.0E-6
2.4E-6
8.7E-7
Figure 8. Production factors for major pollutants from run no.33 with
Wyoming subbituminous coal. NOTE: Ammonia was not measured
in this run.
28
-------
Log jQ pollutant/g carbon converted
Hydrogen Sulfide
Benzene
Toluene
Phenol
Cresols
Xylenes
Xylenols
Ethyl benzene
3.5E-3
3.5E-3
2.0E-3
1.2E-3
1.1E-3
7.4E-4
5.4E-4
1.9E-4
Carbonyl Sulfide 1.6E-4
Indene
Naphtnalene
Anthracene
Fluorene
Oibenzofuran
Phenanthrene
Trimethylphenol
Pyrene
Thiophene
1.3E-4
7.9E-5
7.2E-S
4.6E-S
4.5E-5
4.4E-5
3.8E-5
3.2E-5
2.8E-5
Methylthiophene j 2.8E-5
Chrysene
Indan
. 1.9E-S
I.3E-5
o-isopropy!phenolj 1.7E-5
Fluoranthene
Perylene
Quinoline
Aniline
Acridine
Indole
1 Z
g/g coal loaded
Figure 9. Production factors for major pollutants from run no. 35
with Wyoming subbituminous coal. NOTE: Ammonia was not
measured in this run.
29
-------
Benzene
Ammonia
Hydrogen Sulfide
Toluene
Phenol
Thiophene
Xylenes
Naohthalene
Carbon Sulfide
Ethyl Benzene
Anthracene
Indene
Methanethiol
Xylenols
Fluoranthene
Phenanthrene
Pyrene
Fluorene
Dibenzofuran
Ethanethiol
Chrysene
Trimethyl Phenol
Methyl Thiophene
Ouinol ine
Acridine
Perylene
Indan
o-Isopropylphenc
Log ug pollutant/g carbon converted
5.4E-3 g/g coal loaded
2.5E-3 1
2.3E-3
1.4E-3
l.GE-3
5.1E-4
3.9E-4
2.4E-4
1.7E-4
1.6E-4
l.OE-4
7.9E-5
7.9E-5
6.9E-5
6.3E-5
6.2E-5
4.0E-5
4.0E-5
3.1E-5 J
2.2E-5
2.2E-5
1.4E-5
1.3E-5
1.2E-5
8.3E-5
6.9E-6
•6.4E-6
)l)4.2E-6
Figure 10. Production factors for major pollutants from run no. 36
with North Dakota Zap lignite coal.
30
-------
Log i,g pollutant/g carbon converted
Benzene
Hydrogen Sulfide
Toluene
Xylenols
Cresols
Phenol
Xylenes
Carbonyl Sulfide
Indene
Trimethyl Phenol
Naphthalene
Ethylbenzene
Anthracene
Chrysene
Methylthiophene
Dibenzofuran
Fluorene
o-Isoprophylphenol
Indan
Phenanthrene
Ethanethiol
Methanethiol
Fluoranthene
Pyrene
Thiophene
Carbon Disulfide
Quinoline
Perylene
I.6E-3
1.4E-3
9.1E-4
3.7E-4
4.9E-4
3.5E-4
2.9E-4
2.7E-4
2.2E-4
•1. 7E-4
7.7E-5
6.0E-5
5.2E-5
U.3E-5
3.5E-5
3.5E-5
2.9E-5
2.1E-5
1.7E-5
I.7E-5
I.3E-5
I1.1E-5
9.5E-6
1.1E-5
8.9E-6
6.7E-6
1.8E-6
6.3E-7
g/g coal loaded
Figure 11. Production factors for major pollutants from run no. 43
with North Dakota Zap lignite coal. NOTE: Ammonia was
not measured in this run.
31
-------
Figures 3 through 11 indicate that no consistent hierarchy of compounds
exists regardless of whether one considers compounds produced from an in-
dividual coal or from coals of equal rank gasified under alternative operating
conditions. Ammonia was not measured in all of these tests; yet, it is known
that ammonia occurs at high levels in the effluent of gasifiers operating on
fuels containing nitrogen. It is important to note that benzene, toluene,
and xylene as well as sulfur species^ phenolic compounds, and two-ring PNAs
were important in every case.
The composition of the major elements in selected tars (low volatile
organic condensate) is shown in Table 10. While the sulfur and nitrogen
content of these materials is relatively high, the higher oxygen content
indicates that phenolic, carboxylic, and other hetero-oxygen compounds are
present in relatively significant quantities.
In order to effectively analyze the extensive data obtained during the
screening test sequence, material balance computations and statistical
correlation analyses were performed. Data values were entered into a com-
puter memory for the statistical analysis. Stepwise multiple linear regression
techniques were utilized in order to effectively evaluate the influence of
the independent variables present during these experiments. The material
balance results, as well as the statistical analysis technique and results,
are discussed in the following sections.
32
-------
TABLE 10. PRIMARY ELEMENTS OF TARS
1,4,9
Run
No.
6
15
16
21
23
25
33
35
36
41
43
METC
METC
METC
Coal Type
Illinois No. 6
Illinois No. 6
Illinois No. 6
Illinois No. 6
Illinois No. 6
Montana Rosebud
Wyoming Subbituminous
Wyoming Subbituminous
North Dakota Lignite
Western Kentucky No. 9
North Dakota Lignite
Montana Rosebud
Western Kentucky No. 9
New Mexico Subbituminous
Weight Percent of Element in Tar
% Carbon
78.7
87.5
87.6
87.7
86.0
88.6
86.5
83.0
86.1
86.3
82.3
78.0
80.0
84.4
% Hydrogen
6.3
6.1
6.2
6.1
5.8
6.0
6.0
7.7
7.0
6.1
7.5
6.6
8.7
7.2
% Nitrogen
1.3
1.3
2.1
1.4
1.6
0.8
0.8
1.5
1.3
1.6
1.8
1.1
1.9
1.7
% Sulfur
2.9
1.9
1.6
1.8
2.5
0.7
2.4
0.5
0.7
2.7
0.9
2.4
2.7
1.4
% Oxygen
10.9
3.2
2.4
3.1
3.8
4.0
4.3
7.4
4.9
2.8
7.0
11.0
NA
NA
33
-------
4.0 MATERIAL BALANCE RESULTS
A variety of screening tests have been performed in the RTI fixed-bed
gasifier. One purpose of these tests was to develop operating procedures and
sampling techniques for the gasifier. Nine runs representing five coal types
were chosen as candidates for complete material balances- on ash and the major
elements: hydrogen, oxygen, carbon, nitrogen and sulfur. The material
balances were taken over the length of the gasification run which was con-
sidered to be the time from the coal drop to oxygen breakthrough.
Results of the material balances are summarized in Table 11. It can be
seen that the average of the overall material balance for each of the runs
gives a 100 percent closure but with a standard deviation of 13 percent. The
other component balances except sulfur are within 11 percent of closure but
they also have a large standard deviation indicating considerable scattering
of the closures. Sulfur is the component in the material balances which
appears in the smallest amounts. The deficiency in the closure of the sulfur
balances is probably due to the sampling procedure used in these preliminary
screening runs. This point as well as experimental deviations in other
balances are discussed in more detail below. Also discussed is the possible
improvement of the balances obtained by making judicious and reasonable changes
in experimental values that could perhaps be in error.
4.1 COMPUTATION PROCEDURE
Detailed material balances were performed for various runs on each of the
five coals considered. The amount of each of the major components in the
various inlet or outlet streams was computed. Sample results are shown in
Tables 12 through 16.
The coal charge for each experiment was measured within ± 1 gram using a
scale; however, it was found that 4 to 5 grams of coal usually retained in the
coal feeder giving an error of up to 0.5 percent in the coal feed reported in
Tables 12 through 16. An ultimate analysis of the coal charges for each
individual run was not made and this could be a source of considerable error
due to changes in moisture content. The amount of each major element in the
34
-------
co
en
TABLE 11. ELEMENTAL BALANCES FOR RTI SCREENING RUNS
% Closure (outlet wt./inlet wt.)
RUM 1
16
21
23
25
33
35
36
41
43
Standard
Deviation
OVERALL
74
(96)
91
(97)
117
(100)
97
98
107
(100)
99
(101)
106
(100)
111
(101)
13
(2)
HYDROGEN
64
(99)
86
(95)
114
(100)
82
100
80
(98)
80
(112)
118
(109)
95
(115)
17
(10)
OXYGEN
64
(100)
91
(100)
119
(100)
101
104
92
(99)
90
(100)
109
(100)
105
(100)
16
(1)
CARBON
81
86
97
86
84
91
(100)
37
(100)
106
87
(100)
8
(9)
NITROGEN
94
96
121
(99)
100
100
126
(100)
115
(104)
105
.(100)
128
(101)
13
(3)
SULFUR
75
63
114
72
53
12
48
81
73
28[20]*
ASH
114
123
118
85
65
107
74
72
123
24
[ ] Excludes Run #35
NOTE: By adjusting selected experimental values, results shown In parentheses are obtained.
-------
TABLE 12. MATERIAL BALANCE RESULTS FOR RUN NO.16 (ILLINOIS NO.6 BITUMINOUS COAL)
co
Component
Coal
Steam
Air
Total Input
Gas
Condensate
Tar
Residue
Total Output
Balance, %
Total *
Amount
1572.8
4110.0
2021.4
7704.2
3569.2
1734.0
(3461.6)
59.6
325.7
5688.5
(7416.1)
74
(96)
Hydrogen
Amount
83.36
456.67
540.03
147.78
192.67
(384.62)
3.69
0.94
345.08
(537.03)
64
(99)
Oxygen
Amount
191.88
3653.33
380.76
4225.97
1147.59
1541.33
(3076.95)
1.43
0.00
2690.35
(4225.97)
64
(100)
Carbon
Amount
1046.54
1046.54
680.32
52.25
115.85
848.42
81 .:
Nitrogen
Amount
23.91
1640.60
1664.51
1561.53
1.24
1.04
1563.61
94
Sulfur
Amount
48.44
48.44
31.97
0.95
3.42
36.34
75
Ash
Amount
178.67
178.67
204.44
204.44
114
*•
Amounts in Grams
NOTE: By adjusting selected experimental values, results shown in parentheses are obtained.
-------
TABLE 13. MATERIAL BALANCE RESULTS FOR RUN MO.25 (MONTANA SUBBITUMINOUS COAL)
co
Component
Coal
Steam
Air
Total Input
Gas
Con den sate
Tar
Residue
Total Output
Total *
Amount
1495.0
704.0
2901.1
5100.1
4020.9
783.0
24.4
114.3
4942.6
Hydrogen
Amount
102.71
78.22
180.93
60.82
87.00
0.23
148.05
Oxygen
Amount
426.52
625.78
676.00
1728.30
1051.49
696.00
0.12
1747.61
Carbon
Amount
806.55
806.55
673.04
22.78
0.46
696.28
Nitrogen
Amount
17.94
2225.13
2243.07
2232.23
0.11
2232.34
Sulfur
Amount
8.82
8.82
3.30
1.64
1.37
6.31
Ash
Amount
132.46
132.46
112.0
112.0
Balance, %
97
82
101
86
100
72
85
Amounts in Grams
-------
TABLE 14. MATERIAL BALANCE RESULTS FOR RUN NO.33 (WYOMING SUBBITUMINOUS COAL)
Component
Coal
Steam
Air
Total Input
Gas
Condensate
Tar
Residue
Total Output
Total ^
Amount
1399.6
504.0
2027.7
3931 . 3
3219.2
545.0
16.8
71.4
3852.4
Hydrogen
Amount
83.14
56.00
139.14
75.43
60.56
1.86
0.87
138.72
Oxygen
Amount
420.16
448.00
472.45
1340.61
905.30
484.44
5.37
1.36
1396.47
Carbon
Amount
793.57
793.57
651.49
7.61
11.20
670.30
Ni trogen
Amount
5.32
1555.25
1560.57
1584.27
0.73
0.10
1585.10
Sulfur
Amount
9.10
9.10
2.72
1.25
0.88
4.85
Ash
Amount
88.31
88.31
57.0
57.0
Balance, % 98 100 104 84 100 53 65
*
Amounts in Grams
-------
TABLE 15. MATERIAL BALANCE RESULTS FOR RUN NO.36 (NORTH DAKOTA LIGNITE COAL)
GO
IO
Component
Coal
Steam
Air
Total Input
Gas
Condensate
Tar
Residue Particulates
Total Output
Balance, %
Total *
Amount
1446.7
629.8
2414.4
4490.9
3681 . 2
(3590.6)
676.0
(871.1)
14.9
71.6
4443.7
(4548.2)
99
(101)
Hydrogen
Amount
94.90
69.98
-
164.88
56.23
(86.44)
75.11
(96.79)
1.15
0.11
132.60
(184.49)
80
(112)
Oxygen
Amount
563.63
559.82
562.57
1686.02
910.16
-
600.89
(774.30)
1.25
0.31
1512.61
(1686.02)
90
(100)
Carbon
Amount
677.04
_
-
677.04
572.65
(663.29)
-
-
12.17
1.88
586.70
(677.34)
87
(100)
Nitrogen
Amount
10.56
_
1851.79
1862.35
2139.23
(1927.74)
-
-
0.13
0.04
2139.40
(1927.91)
115
(104)
Sulfur
Amount
8.10
_
-
8.10
2.94
-
-
-
0.16
0.77
3.87
-
48
-
Ash
Amount
92.44
_
-
92.44
_
_
_
_
68.44
68.44
-
74
-
Amounts in Grams
NOTE: By adjusting selected experimental values, results shown in parentheses are obtained.
-------
TABLE 16. MATERIAL BALANCE RESULTS FOR RUN NO.41 (WESTERN KENTUCKY BITUMINOUS COAL)
Component
Coal
Steam
Air
Total Input
Gas
Condensate
Tar
Residue Particulates
Total Output
Balance, %
Total *
Amount
1250.0
1388.0
3764.2
(3956.2)
6402.0
(6594.2)
5316.4
1360.0
(1183.3)
35.0
84.0
6795.4
(6618.7)
106
(100)
Hydrogen
Amount
62.37
154.22
_
_
216.59
101.48
•151.09
(131.46)
3.27
0.01
255.85
(236.22)
118
(109)
Oxygen
Amount
230.54
1233.78
877.06
(921.80)
2341 . 38
(2386.12)
1334.36
1208.75
(1051.67)
-
0.09
2543.20
(2386.12)
109
(100)
Carbon
Amount
786.59
-
-
-
786.59
800.56
-
-
30.05
0.04
830.65
106
Nitrogen
Amount
17.39
-
2887.16
(3034.44)
2904.55
(3051.83)
3050.96
0.16
-
0.71
-
3051.83
105
(100)
Sulfur
Amount
37.14
-
-
-
37.14
28.99
-
-
1.01
0.02
30.02
81
Ash
Amount
115.63
-
-
-
115.63
—
-
-
-
83.80
83.80
72
*
Amounts in Grams
NOTE: By adjusting selected experimental values, results shown in parentheses are obtained.
-------
coal feed was obtained by multiplying the coal charge by the as-received
ultimate analysis.
Steam was fed to the gasifier at a constant rate using a positive dis-
placement metering pump. The accuracy of the steam input is thought to be
fairly high, i.e., ± 5 percent, since the pump was calibrated prior to use.
The flow of air to the gasifier was not constant since it was used to
maintain the maximum temperature in the gasifier below a specified limit. The
flow rate measurement was based on the heat capacity of the gas and could have
been in error by 10 percent. The total flow of air was obtained by integrating
the flow measurements taken at least every two minutes over the length of the
run.
The flow of product gas was estimated by differentiating the dry test
meter data; from a consideration of system leakage, flow rate was estimated
to be accurate to within ± 20 percent. The composition of the gases were
determined by two independent measurements. The gas composition was monitored
every two minutes for CO, COo. CH», and Hp. The accuracy of these measure-
ments of CO, C02, and CH. was considered to be within ± 1 percent of the
measured percentage but the H~ measurement could be in error by as much as ± 3
percent. Bulb samples were taken throughout the runs. These were analyzed
for the major components as well as minor components such as benzene, toluene,
xylene, and sulfur compounds. Major gases were detected within a 2 percent
accuracy, and BTX and sulfur compound measurements were estimated to be accu-
rate within 10 percent. In order to perform material balances on the gasifi-
cation runs shown in Tables 12 through 16, the discrete concentration values
were multiplied by the flow rate and summed (integrated) over the duration of
the run. The integrated data showed that up to 8 percent of the product gas
was unaccounted for in these data. Sources of error in the integration could
be due to inaccurate flow rates and/or inaccurate measurement of the time
intervals between samples. In coal gasification the devolatilization of coal
takes place rapidly; thus, if only a few sample bulbs are taken during the
initial stage of a batch run, considerable amounts of devolatilization pro-
ducts may leave the system undetected. This could explain the nonclosure of
the sulfur balances shown in Table 11.
The condensate is measured volumetrically and this measure is converted
to weight. The accuracy in the measurement is estimated to be normally within
41
-------
± 5 percent. In cases where the condensate was analyzed for contaminants, the
contaminants were considered in the elemental breakdown of the condensate.
Otherwise, the condensate was considered to be essentially water.
The amounts of tar reported in Tables 12 through 16 consist of the actual
tar phase plus organics extracted from the condensate. The ultimate analysis
of the tar was determined by standard techniques. In several runs the tar
analyses were not available and the composition of the tar was estimated from
the analysis of tars from runs using the same coal. This procedure could
introduce little error into the elemental balances because of the small amounts
involved.
The residue is weighed accurately; however, there are inadvertent losses
in removing the residue from the gasifier. The ultimate analysis was obtained
by standard procedures. The weight of particulates retained in the filter in
most cases was not taken. Several of the runs showed a net loss of ash. The
missing ash could be contained in the unmeasured particulates.
4.2 MATERIAL BALANCE ADJUSTMENTS
Better closures of the material balances can be obtained by the reasonable
adjustment of selected experimental measures. For example, in Table 12 it can
be seen that 4110 g of steam was fed to the gasifier but that only 1734 g of
condensate is reported to be collected. This represents a steam conversion of
58 percent which is not typical for Illinois No. 6 coal. By increasing the
condensate mass so that the oxygen closure is assured, the hydrogen and over-
all balances approach 100 percent closure for the run, as can be seen in Table
12. In Table 16 both the air flow and condensate measurements were adjusted
to ensure closure of nitrogen and oxygen. This resulted in improvements to
both the overall balance and the hydrogen balance.
Table 15 shows a case where both the condensate and gas analysis were
adjusted to give closure of carbon and oxygen resulting in improved closures
of the hydrogen and nitrogen balances. The corrected amount of condensate
shown in Table 15 appears too large, in that it exceeds the steam input;
however, taking into account the moisture in the lignite coal, the corrected
condensate corresponds to almost 20 percent steam decomposition.
Adjustments similar to those discussed above were made in several other
runs. Table 11 summarizes these results. It can be seen that the average of
42
-------
the closures for each of the major components is improved and that the scatter
within the closures is reduced. Some of the arbitrariness involved in the
adjustments could be removed from the material balance analyses using a well-
known procedure which minimizes the sum of the weighted squares of the
differences between an experimental measurement and a computed measurement,
where the computed composition analysis must sum to 1.0. There is sufficient
redundancy of measurements in the RTI gasifier system that this procedure
could be used. Such may be justified for the parametric test runs, for which
more precise control is being exercised over the reaction process.
The adjusted material balances for the nine gasifier runs as summarized
in Table 11 demonstrate that the major elements can, in principle, be accounted
for in semi batch experiments. RTI is presently attempting to further reduce
the errors in the material balances by performing gas bulb sampling more
frequently in the initial stage of the runs, and using improved operating
procedures and calibration techniques.
4.3 TRACE ELEMENT BALANCES
Samples of aqueous condensate, tars, and reactor residues were subjected
to atomic absorption measurement so as to determine the levels of various
trace elements present. Table 17 presents the results of tar and condensate
analysis for antimony, arsenic, cadmium, and lead. Arsenic, beryllium,
cadmium, lead, mercury, and selenium analyses were determined in the reactor
residue samples as shown in Table 18. These tables present trace element
concentrations in yg/g for the gasifier effluents as well as the percentage of
the element originally present in the feed which was recovered in the tar,
condensate and gasifier ash. The operating conditions for each run shown are
presented in Table 3,
The trace element behavior is seen in these tables to be quite variable.
Two important factors may be primarily responsible. First the feed coals
varied greatly in their inherent trace element contents. Then, individual
coal charges were not always analyzed seoarately, allowing possible error due
to non-homogeneity within a given coal type. Further, the metallic elements
present in the reactor system, viz., iron, nickel, cadmium, and manganese, may
have entered various of the samples as a result of corrosion phenomena.
43
-------
TABLE 17. TRACE METAL ANALYSES (TAR AND CONDENSATE)
M9/9 (% Recovered)
TEST
Antimony
Arsenic
Cadmium
Lead
Antimony
Arsenic
Cadmi urn
Lead
16
NA
1.3(1.4)
NA
NA
0.014(26)
0.0063(2.3)
NA
NA
21
NA
4.2(4.3)
.035(1.7)
1.1(1.5)
0.0035(13)
0.23(16)
0.0038(12)
0.030(2.8)
23
Tar yg/g (%
NA
4.6(4.7)
.027(0.8)
.31(0.4)
Condensate ug/ml
0.0096(23)
0.44(20)
0.00013(0.2)
0.012(0.7)
25
Recovered)
NA
NA
NA
NA
(% Recovered)
<.003
0.11(4.6)
0.0044(3.4)
0.0085(0.7)
33
0.14(0.3)
.20(0.3)
NA
NA
<.003
0.036(2.0)
NA
NA
35
.095(5.4)
.48(1.9)
.017(1.9)
.73(21)
<.003
0.013(0.7)
0.015(22)
0.021(7.8)
36
.42(2.6)
.66(0.2)
.042(0.6)
2.1(6.8)
<.003
0.029(0.6)
0.00013(0.1)
0.044(9.0)
NA = Not Analyzed
No Tar or Condensate Analyses Available for Tests 41 or 43
-------
TABLE 18. TRACE METAL ANALYSES - RESIDUE (BOTTOM ASH)
yg/g (% Recovered)
en
TEST
Arsenic
Beryl 1ium
Cadmium
Lead
Mercury
Selenium
16
13(84)
NA
NA
NA
21
12(51)
6.5(99)
0.88(177)
9.0(54)
23
41
25
33
35
36
3.0(41) 1.4(13)
9.1(46) 7.2(20)
4.5(82) 11(100)
0.41(108) 1.8(188)
4.9(34) NA
<1 NA
1.7(18) 9.9(30)
4.8(29) 16(90)
4.9(95) NA
0.028(3.1) NA
2.1(27) NA
<1 NA
1.8(18) NA
8.3(77) 41(84)
3.4(67) 3.7(52)
0.22(57) 0.51(43)
2.3(154) 1.4(28)
<1 NA
5.9(37) NA
43
54(112)
3.2(46)
1.0(87)
0.53(11)
NA
15(104)
NA = Not Analyzed
-------
Beryllium was presented at low levels in the coals and was retained
principally in the reactor residue. Beryllium retention was most pronounced
for the higher rank coals. Arsenic retention was higher for the lower rank
coals. Cadmium levels indicate that contamination from the metallic reactor
system may have taken place. The unusually low recovery for cadmium in Run
25 (Montana Rosebud) as compared with the other coals studied (3.1 percent
versus 43 percent or higher) may be due to the use of a nonrepresentative
coal sample for the original trace element determination. (Trace element
determinations for parametric runs are being performed by selecting samples
for analysis from small aliquots which have been specifically prepared for
each run.)
A comparison of selected trace element distribution results of the RTI
screening tests with those available from various research gasifiers are
presented in Table 19. The RTI gasifier was found to accumulate arsenic in
the reactor residue when gasifying Pittsburgh No.8 seam coal, as shown in
Table 19. This may be an error or artifact, rather than an actual condition.
The Synthane PDU gasifier of the Pittsburgh Energy Technology Center was
found to accumulate arsenic, cadmium and lead when operating with an Illinois
No.6 coal. This may be associated with the fact that the Synthane gasification
process does not achieve a high carbon conversion as a result of limited
fluidized bed residence time. (The resulting char material is assumed to be
useful in'alternative conversion steps in order to fully utilize the carbon
content of the material.)
Overall, the comparative data indicate that trace element behavior is
quite variable in gasification processes. Low elemental recovery rates
indicate that significant percentages of the elements escape to one or more
effluents. Arsenic, cadmium, lead, and mercury must then all be regarded as
potentially volatile elements in coal gasification reactors.
46
-------
Table 19. COMPARISON OF TRACE ELEMENT ANALYSIS RESULTS 10'1]'12
Mass Fraction ^Sen1c Cadm1um Lead Mercury
(ug/g)
01 u «) 01
Feed •§•§•§ p
Process ~v "* "S '£ "S ~ «5 '£
Research Group ££££££££
Pittsburgh No. 8 Coal
RTI Gasifler
Research Triangle Institute 8.71 20.6 0.16 0.01 6.50 2.62. 0.13 <0.03
Pittsburgh No. 8 Coal
Hygas PDU Gasifler
Institute of Gas Technology 9.6 3.4 0.78 0.30 5.9 2.2 0.27 0.01
Illinois No. 6 Coal
RTI Gasifler
Research Triangle Institute 3.26 2.39 0.34 0.13 16.8 0.30 0.12 <0.03
Illinois No. 6 Coal
Hygas PDU Gasifler
Institute of Gas Technology 24 16 0.89 0.21 11 5.8 0.12 <0.01
Illinois No. 6 Coal
Synthane POU Gasifler •
Pittsburgh Energy Research
Center 1.3 3.3 0.01 0.77 1.1 21 0.14 NO
f _ _ .^_____^_
Montana Rosebud Coal
RTI Gasifler
Research Triangle Institute 0.71 <0.02 0.14 0.04 20.5 1.98 0.10 <0.03
Montana Rosebud Coal
GEGAS Gaslfier
Peabody Coal Company 2.6 1.2 1.0 6.1 1 51 0.09 0.12
NO = Not detected.
47
-------
5.0 STATISTICAL ANALYSIS OF DATA
A statistical analysis of the RTI gasifier screening runs was carried out
to identify the most important operating parameters affecting the production
of selected potential pollutants. A stepwise linear regression analysis was
used to determine the correlation between the operating and production para-
meters .
A list of the important gasifier operating parameters is shown in Table
20. These were used as the independent variables in correlating the pollutant
production parameters which were considered to be the dependent variables in
the analysis. The operating parameters were chosen from a more extensive set
using engineering judgment and past experience in analyzing gasifier data. Of
the 20 variables, 14 characterize the coal used in the tests and the remainder
describe the operation of the gasifier. The heating rate during pyrolysis
(HTRT), air-to-coal (AC) and steam-to-coal (SC) ratios, and bed temperature
(TMAXAVG) are known to affect both the quantity and distribution of products
from gasifiers. The amount of coal charged (CLCHRG) and the average gas flow
into the gasifier (TGAS) were chosen as independent variables because they are
indicative of gas-solid contacting and bed height.
5.1 LINEAR REGRESSION TECHNIQUE13
Selected pollutant production variables along with several other indicators
of gasifier performance, which make up the dependent variable set, are shown
in Table 21. In general, the pollutant production parameters are yields for
a specific compound per unit of carbon gasified, or coal loaded. They were
chosen because the raw product gas concentration of these compounds typically
exceeded published thresholds for adverse health effects.
The stepwise linear regression analysis was carried out using a standard
statistical program. Briefly, the stepwise computer program finds the single-
2 2
variable model which produces the largest R statistic (where R is the square
of the multiple correlation coefficient). After entering the variable with
2
the largest R , the program uses the partial correlation coefficients to
select the next variable to enter the regression. That is, the program enters
the variable with the highest partial correlation coefficient (given that the
n
variable with the largest R is already in the model.) An F test is performed
48
-------
Table 20. IMPORTANT GASIFIER OPERATING PARAMETERS
(Independent Variables in the Regression Analysis)
PCTVOLMT
PCTASH
SULFUR
HTRT
AC
AS
PCTMOIST
FBTULB
CLCHRG
TGAS
TMAXAVG
ORG
SULFATE
SC
FXDCAR
PYR
CARBON
HYDRO
OXY
NITRO
Percent volatile matter in coal.
Percent ash in coal.
Total percent sulfur in coal.
Heating rate of the coal during pyrolysis phase
taken as the slope of the time temperature curve
as the coal is heated from 300°C to 700°C.
Air-to-coal ratio (g/g).
Air-to-steam ratio (g/g).
Percent moisture in coal.
Higher heating value of coal.
Coal charged to the gasifier (g).
Average gas flow rate into gasifier (slpm).
Mean of the maximum bed temperature averaged over
the entire test, °C.
Percent organic sul.fur in coal.
Percent sulfur as sulfate in coal.
Steam-to-coal ratio (g/g).
Percent fixed carbon in coal.
Percent sulfur as pyrites in coal.
Percent carbon in coal.
Percent hydrogen in coal.
Percent oxygen in coal.
Percent nitrogen in coal.
49
-------
Table 21. IMPORTANT POLLUTION PRODUCTION PARAMETERS AND
GASIFIER PERFORMANCE VARIABLES (Dependent Variables In The
Regression Analysis)
SCFLB
BTUSCF
ORACL
ORBCL
NPNCL
PNACL
PCTTARCL
AR4
SU2
BEN10
BTX
PHET
CRET
HS10
CS10
SRAT10
MTH10
NAPT
PTHT
INE8
BFU8
FTH4
FLU4
Total gas produced (scf/lb coal)
Higher heating value of gas produced (Btu/scf)
Tar organic acid yield (g x 100/g coal)
Tar organic base yield (g x 100/g coal)
Tar nonpolar neutral yield (g x 100/g coal)
Tar polynuclear aromatic yield (g x 100/g coal)
Percent tar yield from coal
Tar arsenic yield (ug/g carbon converted)
Ash sulfur yield (yg/g carbon converted)
Benzene production (ug in bulb/g carbon converted)
BTX production (yg/g carbon converted)
Total phenol production (yg/g carbon converted)
Total cresol production (yg/g carbon converted)
HgS yield in gas (yg/g carbon converted)
COS yield in gas (yg/g carbon converted)
Ratio H2S to COS in gas (g/g)
CH3SH yield in gas (yg/g carbon converted)
Total naphthalene yield (yg/g carbon converted)
Total phenanthrene yield (yg/g carbon converted)
Indene yield in gas (g/g carbon converted)
Benzofuran yield in gas (yg/g carbon converted)
Fluoranthene yield in tar (yg/g carbon converted)
Fluorene yield in tar (yg/g carbon converted)
50
-------
to determine if the variable to be entered has a probability greater than the
specified significance level for entry into the analysis. (For the analysis
presented here this level was 50 percent.) After a variable is added, the
program searches all the variables already included in the model and computes
a partial F-statistic to determine if these variables should remain in the
model. Any variable not producing a partial F significant at the specified
significance level for retention, i.e., 0.10, is then deleted from the model.
The process then continues by determining if any other variables should be
added to the regression. The process terminates when no variable meets the
conditions for inclusion or when the next variable to be added to the model is
the one previously deleted from it.
5.2 STATISTICAL ANALYSIS RESULTS: PHASE I
The results of the analysis using the independent variables from Table 20
and the dependent variables in Table 21 are summarized in Table 22. Entrees
in this table correspond to the order of importance of each independent vari-
able in accounting for the variation in each dependent variable. For example,
in the row labeled "SCFLB" (total scf of product gas per Ib coal) a value of 1
•
was entered in column "AC" (air-to-coal ratio.) This means that the air-to-
coal ratio was the most important parameter in correlattng the total product
gas. Also from the same row it can be seen that the steam-to-coal ratio was
the second most important variable in correlating the total product gas with a
linear model.
The positive or negative sign following each numerical entree in Table 22
is the sign of the coefficient of the corresponding independent variable in
the linear model. For example, examination of the first two dependent variables
shows that the volume of product gas increases and the heating value of the
gas decreases with increase in air-to-coal ratio. This is to be expected due
to increased nitrogen concentration in the product gas.
In order to identify the most important variables affecting pollutant
production, the most important independent variables in determining each of
2
the dependent variables (dependent variables with an R less than 0.500 were
not considered) shown in Table 22 were assigned the value of V equal to seven
minus its ranking in any specific correlation giving an overall ranking index
W which gives a measure of the overall importance of that variable in affecting
pollutant production.
51
-------
TABLE 22. SUMMARY OF THE STATISTICAL ANALYSIS OF THE RTI GASIFIER
SCREENING RUN USING ALL INDEPENDENT VARIABLES IN TABLE 20
Dependent
Variables
gas produced
(SCFLB)
gas HHV
(BTUSFC)
organic acids
(ORACL)
organic bases
(ORBCL)
nonpolar neutrals
(NPNCL)
PNAs
(PNACL)
tar yield
(PCTTARCL)
arsenic in tar
(AR4)
sulfur in ash
(SU2)
benzene yield
(BEN10)
BTX yield
(BTX)
phenol yield
(PHET)
cresols yield
(CRET)
hydrogen sulfide
(HS10)
ifE
• c
.— >
0 t—
a.
n-
2+
2+
2+
Independent Variables
^— «
to >-
ta o
Q.
5+
i— u_
rs _i
CO 3
1 +
2+
1 +
1 +
01
(O
c — «
•r- 1—
X— *•
0) <
r- C3
C 1—
2+
3-
2-
>ed temperature
TMAXAVG)
3-
6-
4+
2-
to
0
•1—
c
ItJ
o». — •.
J- CD
0 QL
Oj
°
UJ
•0 1—
«*-
S- O
-o cc
6^
3+
Q>
CD
X >-
0 X
o
&«
c:
o>
i- o
E »-•
z
&s
4+
5-
1-
CM
o:
0.965
0.766
0.662
0.981
0.338
0.876
0.850
0.768
0.688
0.838
0.958
0.346
0.456
0.715
No.
Observations
34
25
19
19
19
18
19
8
18
17
15
14
14
21
(continued)
-------
Table 22 (continued).
Dependent
Variables
carbonyl sulfide
(CS10)
H2S/COS
JSRAT10)
methanethiol
(MTH10)
naphthalene
(NAPT)
phenanthrene
(PTHT)
indene
(INE8)
benzofuran
(BFU8)
fluoranthene
(FTH4)
fluorene
(FLU4)
Independent Variables
£ vol . matter
[PCTVOLMT)
4+
co
V) 1 —
tO CJ
a.
3 C£
«*- rs
i— U_
•3 —i
10 ID
CO
1 +
Ol
10
t-
Cn
*-> cc.
to t—
Ol n:
r- CO
01
r- Q
4- X
U_
4-
co
0
0-
o ~zz.
XJ 0
S- CQ
03 CC.
o >Q
x: >-
c
O)
en
x >-
0 X
o
c
Ol
en
i. 0
4->
-------
The independent variable(s) of greatest importance were different de-
pending upon the specific dependent variable of interest. Table 22 shows that
the sulfur level was of primary importance in the yield of organic tar bases
and benzene, both of which are known to have a high level of potential for
carcinogenic and/or mutagenic activity. Gasifier operating parameters CLCHRG
(coal charged) and TGAS (inlet gas flow rate) were found to be of importance
in the production of several pollutants. As discussed previously, these
parameters represent the reactor bed height and the conditions of gas-solid
contacting. The mechanism(s) through which the parameters identified in Table
23 influence pollutant production is not explicitly known at present. It is
possible that mechanisms of pollutant production may not directly involve the
identified parameters but that these parameters may be indicative of inter-
mediate processes or parameters not considered in the analysis but which are
highly correlated with the identified parameters. A more basic phenomeno-
logical study of gasification process would help reveal the relationship
between the identified independent parameters and pollutant production rates;
such work is planned as a part of this project.
5.3 STATISTICAL ANALYSIS RESULTS: PHASE II
Statistical analyses were performed to determine if the independent para-
meters shown in Table 23 are significantly correlated with each other. In the
case where two variables have a high degree of correlation one can be eliminated
from the analysis. A reduction in variables is beneficial in that the linear
models for predicting pollutant product yields would involve fewer independent
variables. A strategy was developed for reducing redundant variables:
1. Starting with the most important variable as listed in Table 23,
variables of lesser importance were eliminated from consideration as
a primary parameter if they had a high degree of correlation with
the most important variable.
2. Step 1 was repeated throughout Table 23 until no variables were
remaining for consideration.
Applying this procedure to Table 23 resulted in the set of primary independent
variables listed in Table 24. The stepwise linear regression procedure
described above was applied in correlating the pollutant production yields and
gasifier performance variables listed in Table 21 with the primary dependent
variables in Table 24. The results of this analysis are summarized in Table
54
-------
TABLE 23. RANKING OF OPERATING PARAMETERS IN THE ORDER OF
IMPORTANCE IN INFLUENCING POLLUTANT PRODUCTION
Independent
Variable
% sulfur
(SULFUR)
coal charged
(CLCHRG)
inlet gas flow
JTGAS)
% vol . matter
(PCTVOLMT)
bed temperature
(TMAXAVG)
steam/coal
CSC)
% sulfate S
(SULFATE)
air/ steam
(AS)
heating rate
(HTRT)
% pyritic S
(PYR)
air/coal
(AC)
% organic S
(ORG)
heating value
(FBTULB
% nitrogen
(NITRO)
% hydrogen
(HYDRO)
% fixed coal
(FXDCAR)
% ash
(PCTASH)
% moisture
(PCTMOIST)
% carbon
(CARBON)
% oxygen
(OXY)
Ranking
Index*
W
29
25
22
19
18
17
16
15
13
12
11
6
5
5
4
3
2
0
0
0
Overall Importance
in Pollutant Formation
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
*The overall ranking index, W, is the sum of the V values from the individual
correlations, where V is seven minus the ranking of the independent variable
under consideration.
55
-------
TABLE 24. RANKING OF THE MOST IMPORTANT, INDEPENDENT OPERATING
PARAMETERS INFLUENCING POLLUTANT PRODUCTION
Independent
Variable
% sulfur
(SULFUR)
% sulfate S
(SULFATE)
% vol . matter
(PCTVOLMT)
steam/coal
(SO
coal charged
(CLCHRG)
inlet gas flow
(TGAS)
bed temperature
(TMAXAVG)
air/ steam
(AS)
air/ coal
(AC)
heating rate
(HTRT)
Ranking
Index*
W
40
24
22
21
20
18
16
15
12
8
Overall Importance
in Pollutant Production
1
2
3
4
5
6
7
8
9
10
*The overall ranking index, W, is the sum of the V values from the individual
correlations, where V is seven minus the ranking of the independent variable
under consideration.
56
-------
25. (The entries in this table have the same significance as described for
Table 22.) An overall ranking of importance of the dependent variables in
affecting pollutant production was again performed. The results of this
ranking are shown in Table 24.
The linear models for pollutant yields and gasifier performance using the
dependent variable listed in Table 24 are shown in Table 26. The entries in
the columns of this table are coefficients of the corresponding independent
variables in the linear model of the dependent variable. For example, the
product gas yield is given by
SCFLB = -12.23 + 3.928*SC + 0.01611*CLCHRG + 19.12*AC-0.1472*HTRT.
Relative to the yields of potential pollutants considered in this analysis,
the coal characterization parameters of total sulfur, sulfate and volatile
content were the most important parameters. The importance of the volatile
matter content of the raw coals undoubtedly reflects the fact that the coal-
derived volatiles contain many of the potential pollutants under study here.
The three sulfur variables of total sulfur, pyritic sulfur, and organic sulfur
were found to exhibit generally the same behavior in the regression analyses.
This is explained by the fact that the pyritic sulfur and organic sulfur
levels were highly correlated with the total sulfur level, the correlation
coefficients being 0.90 and 0.85 respectively.
The importance of sulfur indicated in Tables 24 and 26 may to some extent
be the result of statistical bias which lacks physical meaning. However, an
attempt to further evaluate the possible existence of causative factors has
been initiated. The sulfur species, viz., pyritic, organic, and/or total
sulfur content, were intercorrelated as independent variables relative to
dependent variables as hydrogen sulfide yield, etc. Moreover, the iron con-
tent of the coal is highly correlated with the pyritic sulfur. Iron is
capable of substituting for sulfur in thiophene structures; thus, a higher
iron pyrite content for coal can result in a greater potential for the modi-
fication of organically bonded sulfur.
Also, sulfur is known to form thia- and dithiaether linkages in hydro-
carbon media. This can be a form of "vulcanization" in which the presence of
the sulfur promotes the formation and/or maintenance of larger molecular
57
-------
TABLE 25. SUMMARY OF THE STATISTICAL ANALYSES OF THE RTI GASIFIER
USING THE MOST IMPORTANT, INDEPENDENT OPERATING VARIABLES
Dependent
Variables
gas produced
(SCFLB)
gas HHV
(BTUSFC)
organic acids
(ORACL)
organic bases
(ORBCL)
nonpolar neutrals
(NPNCL)
PNAs
(PNACL)
tar yield
(PCTTARCL)
arsenic in tar
IAR4)
sulfur in ash
(SU2)
benzene yield '
(BEN10)
BTX yield
(BTX)
phenol yield
(PHET)
cresols yield
(CRET)
hydrogen sulfide
(HS10)
carbonyl sulfide
(CS10)
H2S/COS
(SRAT10)
methanethiol
(MTH10)
Independent Variables
t vol . matter
(PCTVOLMT)
1 +
1 +
1 +
1 +
3+
3^
*3 _l
00
2+
1 +
2+
1 +
1 +
O)
tj
01
O) X
4-
3+
2+
4+
10
o
u
i. O
r- ^
1 +
1-
6-
2+
1 +
E
V
1/1
i- oo
r-eC
3-
2-
2-
•o
00
(U <
•— o
C 1—
2+
3-
2-
3-
aed temperature
(TMAXAVG)
3-
5-
2-
if
^ —i
10 oo
4+
1 +
2-
3-
1 +
2-
steam/coal
(SO
2+
2+
1 +
u
1 +
2+
H
CM
o:
0.965
0.766
0.662
0.955
0.313
0.777
0.860
0.768
0.608
0.878
0.710
0.251
0.456
0.701
0.801
0.731
0.334
No.
Observations
34
25
19
19
19
17
19
8
18
17
15
14
14
21
21
21
19
58
-------
TABLE 25 (continued).
Dependent
Variables
naphthalene
(NAPT)
phenanthrene
(PTHT)
indene
(INE8)
benzofuran
(BFU8)
fluoranthene
(FTH4)
fluorene
(FLU4)
Independent Variables
steam/coal
JSC)
3-
C\J
o;
0.323
0.990
0.091
0.513
0.555
0.261
No.
Observations
15
7
16
14
16
16
59
-------
TABLE 26. SUMMARY OF LINEAR MODELS FOR POLLUTION
PRODUCTION AND GASIFIER PERFORMANCE
INTERCEPT
INDEPENDENT
VARIABLES
SULFUR
SULFATE
PCTVOLMT
SC
CLCHRG
TGAS
TMAXAVG
AS
AC
HTRT
R2
No. Observations
INTERCEPT
INDEPENDENT
VARIABLES
SULFUR
SULFATE
PCTVOLMT
SC
CLCHRG
TGAS
TMAXAVG
AS
AC
HTRT
R2
No. Observations
ORACL
9.623E-1
_-
--
1.815E-2
--
--
7.733E-3
- 1.456E-3
--
--
--
0.662
19
AR4
- 1.159E-3
2.378E-4
--
--
—
7.500E-7
_-
--
--
--
--
0.768
8
ORBCL
3.155E-2
3.372E-2
--
4.950E-3
--
1.123E-4
—
- 2.682E-4
- 2.319E-2
1.510E-2
—
0.955
19
SU2
- 1.791E+1
--
1.399E+2
--
--
—
--
--
--
5.632
—
0,608
18
PNACL
- 9.817E-1
3.474E-1
--
—
--
7.792E-4
- 1.516E-2
--
--
9.913E-3
--
0.777
18
BEN10
-5.372E+3
--
2.585E+2
--
7.195E+3
—
- 2.172E+2
__
—
1.184E+2
—
0.878
17
PCTTARCL
- 5.916
4.694E-1
5.447
1.014E-1
--
2.315E-3
--
--
--
--
—
0.860
19
BTX
8.350E+3
—
- 2.420E+4
—
1.084E+4
--
—
--
—
—
—
0.710
15
continued
60
-------
TABLE 26 (continued).
INTERCEPT
INDEPENDENT
VARIABLES
SULFUR
SULFATE
PCTVOLMT
SC
CLCHRG
TGAS
TMAXAVG
AS
AC
HTRT
R2
No. Observations
INTERCEPT
INDEPENDENT
VARIABLES
SULFUR
SULFATE
PCTVOLMT
SC
CLCHRG
TGAS
TMAXAVG
AS
AC
HTRT
R2
No. Observations
HS10
1.148E+5
1 . 502E+4
--
--
--
--
--
- 1.242E+2
--
--
--
0.701
21
CS10
- 8.406E+2
i
t
i
i
i
—
- 4.962E+3
—
3.639E+2
!
--
--
9.352E+2
--
0.801
21
FTH4
- 1.482E-5
1.490E-4
—
--
--
1.611E-2
--
—
--
--
0.555
16
PTHT
.)
- 1.462E+1
1.388
--
—
- 4.332E-1
9.725E-3
--
—
--
--
--
0.990
7
SCFLB
- 1.223E+1
— _
--
--
3.928
--
—
--
--
1.912E+1
- 1.472E-1
0.965
34
BFU8
1.459E+3
__
-_
__
__
__
-_
- 1.120
- 7.813E+1
__
—
0.513
14
BTUSCF
1 . 990E+2
_ _
__
._
2.143E+1
-_
--
--
__
- 5.963E+1
9.628E-1
0.766
25
61
-------
weight hydrocarbons» i.e., tars. Clearly, the sulfur, nitrogen, and oxygen
content of gasifier tar precursors influences its chemical properties.
The most important gasifier operating variable affecting pollutant
production was the steam-to-coal ratio. This variable had a significant
influence on benzene and total BTX production. (The steam may have functioned
to reduce the oxygen partial pressure in the reactor during the devolatilization,
i.e., unsteady-state, period. This phenomenon should not occur in a continuous
fixed-bed gasifier). The other operating variables except the heating rate
listed in Table 24 also had about the same order of significance in influencing
pollutant production as did the steam-to-coal ratio. Heating rate was only
found to be influential in the yield of tar PNA.
The height of the coal bed in the RTI laboratory gasifier was also found
to have some statistical influence on various of the output (dependent)
variables, as measured by the coal charge quantity (CLCHRG). This is pro-
bably a result of the fact that a greater bed height reduces the zone above
the bed where residence time and thermal conditions are favorable to the
cracking or gasification of tars and oils, for example. Hence, as the coal
charge quantity increases the yield of tar, for example, may increase, as was
found in this study.
In Figures 12 through 16, the predicted yields for several pollutants are
compared to the experimental values obtained from the RTI gasifier. It can
be seen that the agreement is reasonable even though the gasifier runs include
a variety of coals and operation conditions.
The predicted yield of organic bases (ORBCL) in crude gasifier tar is
shown in Figure 12 versus the actual yield. A correlation coefficient of
0.955 was obtained. Six independent variables appear in the correlation, as
shown in the second column of Table 26. The amount of scatter in the data is
seen to be quite low and uniform over the range of the correlation for the 19
values available.
The predicted polynuclear aromatics (PNACL) yield in crude gasifier tar
is shown in Figure 13 versus the actual yield. The noticeable degree of
scatter seen in this figure is reflected by a correlation coefficient of
0.777. As seen in Table 26, the three independent variables which most
successfully represent the yield of polynuclear aromatics are coal sulfur
content (SULFUR), coal charge amount (CLCHRG), the gas flow rate (TGAS) to
62
-------
CO
0.27 '
0.24
.21
S °*18
o
o
X
C7I
0.1S
o
O)
Q.
0.09
0.06
0.01
0.00 »
!
3.00 0.0? 0.06 0.09 0.12 0.15 0.18 0.21 0.24 0.27 0.30
Observed Tar Organic Base Yield (g x 100/g coal)
Figure 12. Comparison of the observed and predicted tar organic base yields for the RTI gasifier screening
tests.
-------
o
u
O
o
X
o>
2.1 »
1.8
1.5
1.2
en
I/)
u
-M
(O
I
$_
eo
OJ
U
0.9
0.6
A A
O
Q_
TD
O)
O
•i—
-a
0.3
0.0 «
0.0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
2.4
Observed Polynuclear Aromatlcs Yield (g x 100/g coal)
Figure 13. Comparison of the observed and predicted tar organic acid yields for the RTI gasifier screening
tests.
-------
01
3.6
3.0
2.4
o
o
o
o
X
O)
OJ
i-
ta
1.8
1.2
01
o
OJ °'&
Q.
T3
(U
U
•i—
T3
O>
t- 0.0
0.0
0.6
S.2
1*8
J..C
A A
3.6
Observed Percent Tar Yield (g x IGO/g coal)
Figure 14. Comparison of observed and predicted tar yields for the RTI gasifier screening tests.
-------
cr>
en
T3
O)
0>
c
o
fc.
o
o>
O)
I/)
fO
o
O
Q-
•i—
>-
to
CM
0>
-o
0)
S-
tx
64 COO *
56000
48000
40000
32000
24000
16000
AA A
-8000
10000
* — « 4- ^ ••••
20000
. ». ^«> _•
30000
40000
50000
60000
70000
80000
90000
100000
Observed H2S Yield in the Product 6as(yg/g carbon gasified)
Figure 15. Comparison of observed and predicted hUS yields for the RTI gasifier screening tests.
-------
cr>
-vl
5000
1500
(O
c.
o
-d
fO
u
o>
O)
to
-------
the gasifier, and the air/coal feed ratio (A/C). (One of the observations is
not shown on Figure 13 as it was off-the-scal.e used.)
Figure 14 displays the predicted versus observed yield of crude gasifier
tar (PCTTARCL), expressed as percent of the raw coal feed which appears as
tar, i.e., grams tar x 100/grams coal. A good correlation was obtained; the
correlation coefficient was 0.860 based on four significant independent vari-
ables. These were the total sulfur (SULFUR), sulfate sulfur (SULFATE), percent
volatile matter (PCTVOLMT), and quantity of coal used (CLCHRG).
The yield of hydrogen sulfide is displayed in Figure 15 where the pre-
dicted values are plotted versus the measured values. Some 20 of the 21
observations are shown, one being off-scale. The degree of scatter is reason-
ably low (correlation coefficient = 0.701); one point is seen to be at an
extreme value and could be considered an "outlier." The hydrogen sulfide
yield was found to be higher when the total sulfur level of the raw coal was
higher and lower when the reactor bed temperature was lower.
The carbonyl sulfide yields were always secondary to those for hydrogen
sulfide by about two orders of magnitude. A reasonably good correlation
2
coefficient (R = 0.801) resulted for the carbonyl sulfide yield in terms of
the sulfate, steam/coal ratio and air/coal ratio, as shown in Table 26.
However, it is seen in Figure 16 that the data are heavily grouped near the
low end of the range of yield values. Probably the most significant aspects
are that (a) the carbonyl sulfide yield did not vary substantially, even with
wide variations in the total sulfur content of the feed coal, and (b) the
yield level was well-correlated by three variables each of which provide
measures of oxygen input to the gasifier. (This latter condition may indicate
that carbonyl sulfide is formed primarily via secondary reactions, for example
from hydrogen sulfide interactions with oxygen and oxides of carbon. It is
generally known that the reaction of hLS and CO to form COS and H~ tends to be
near an equilibrium condition in the raw product gas from a coal gasifier.
This latter condition is consistent with the general concentration levels
observed, i.e., the H2S/COS ratio was in the range of 20 to 200 typically.)
68
-------
6.0 CONCLUSIONS
The objective of this project is to develop a fundamental understanding
of those factors which influence the production of potential environmental
pollutants in synfuel processes. This information is needed to provide guid-
ance for the control of potentially harmful pollutants from future synfuels
plants.
A series of screening tests have been completed using a laboratory scale
gasification reactor. The purpose of these screening tests was to compare
pollutants, qualitatively and quantitatively, from a variety of coals under
similar gasification conditions. Coals tested were Montana Rosebud, Wyoming
subbituminous, North Dakota Lignite, Pittsburgh No.8, Illinois No.6, Western
Kentucky No.9, and FMC char. Chemical analyses of the coals, particulate
residues, tars, aqueous condensates, primary gaseous products, and volatile
organics have been performed. Emphasis has been upon determination of the
organic constituents in the effluent streams.
The laboratory reactor has been operated primarily as a nonisothermal
pollutant generation facility. Steam furnaces have been utilized to provide a
primary reactant to the bottom of the vertical reaction chamber. Also, pres-
surized air and/or oxygen have been supplied for reaction. The air-to-steam
ratios have been controlled so as to achieve operating conditions representa-
tive of practical gasifier operation. Further, both the steam and air rates
have been controlled so that the coal bed temperature is maintained at desir-
able levels. In this way, successful operation of the reactor has been achieved
while operating with simultaneous temperature control; this is provided through
use of a three-zone electric furnace which surrounds the reactor. Data collec-
tion has been possible as a result of the utilization of a POP 11/34 signal
processing system operated on-line with the reactor facility.
High carbon conversions have been achieved as desired. Higher rank coals
showed slightly less carbon conversion; they possess a somewhat lower reactivity.
Also, the conversion of the sulfur species in the feed coal have been generally
above 80 percent during gasification runs to approximately 1000°C. It has
been concluded that the level of sulfur conversion can be increased if the
overall residence time for reaction exceeds that required for carbon conver-
sion alone. However, the screening test runs were terminated once oxygen was
detected in the gas exit stream.
69
-------
Two distinct time phases for reaction were observed in the screening test.
runs. These have been characterized as surge and steady-state periods. The
surge period involves devolatilization of the coal and represents the conditions
under which effluent concentrations vary substantially with time. After the
methane concentration in the effluent gas has dropped below approximately two
volume percent, it has been observed that the temperature and concentration of
the effluent stream is generally well behaved, i.e., steady-state. It is
believed that this phase involves primarily the gasification of char via the
carbon/steam reaction, the partial oxidation of carbonaceous material, and the
carbon/carbon dioxide reaction. The supporting evidence for the understanding
of reactor behavior and characterization of pollutant production has been
obtained as a result of using sampling and analysis techniques which have been
specifically developed for these studies.'
Application of these testing methods have provided concentrations and
amounts for the reactor residue, aqueous condensate, oils and tar, as well as
the primary gas product stream. This stream has been subjected to routine gas
chromatographic analysis as well as infra-red measurements so as to success-
fully maintain known and desirable operating conditions within the facility.
Relative quantities of organic pollutants have resulted from these tests. For
convenience, these results have been expressed as mass of compound produced
from each effluent per unit of feed carbon converted within the reactor. The
dominant compounds which have been identified in the effluent streams are
hydrogen sulfide,-carbonyl sulfide, phenol, cresols, benzene, toluene, naphtha-
lene, anthracene, and phenanthrene. Additional studies are currently underway
to characterize the tar fractions relative to the wide distribution of compounds
which are contained therein.
The Western Kentucky No.9 and Illinois No.6 coals were found to generate
larger tar yields, while subbituminous and lignite coals resulted in somewhat
less tar production. The smallest yield of PNA and organic base materials
were obtained from North Dakota lignite, while the largest yields resulted
from Western Kentucky No.9 coal. Generally, the tar yields were found to be
substantial during these runs. This is in agreement with the tar yields of
commercial fixed bed coal gasifiers operating with medium and high volatile
14 15
coal feed materials.
70
-------
Trace element studies have indicated that arsenic, cadmium, lead and
mercury may also generally be volatilized during gasification. (Additional
results on trace element analyses have recently been obtained via neutron
activation analysis techniques. While the results are generally in agreement
with those of atomic absorption, both sets have revealed that measurements of
the trace elements being carried by the primary gas stream may be necessary
to fully account for the fate of these elements within the gasification
process.
Material balance calculations have been completed for many of the screening
test runs. It was generally difficult to achieve a high degree of closure on
material balances for the semibatch tests as they were conducted over extended
time periods. However, overall closure was obtained for these runs at a
level well within a standard deviation of only 13 percent. Closure was
•obtained least well for sulfur, ash, and hydrogen. (It has been demonstrated
that the percentage closure for the individual elements can be substantially
improved by adjusting the material balances so as to force closure on a
selected element, e.g., oxygen. This condition indicates that some experi-
mental error is present in the results which is due, perhaps, to inaccuracies
in the overall determination of gas flow rates.)
A statistical analysis of the RTI gasifier screening runs was carried
out to identify the most important operating parameters affecting the produc-
tion of selected pollutants. Specifically, a stepwise linear regression
analysis was used to determine the correlation between the operating, and
production parameters. Some 20 operating variables were chosen for analysis.
In the production of potential pollutants, the coal characterization parameters
of total sulfur, sulfate and volatile content were the most important quantities
in determining yields. Total sulfur was indicated to significantly affect
the production of both sulfur and nonsulfur compounds. The most important
gasifier operating variable affecting pollutant production was the steam-to-
coal ratio. This variable had a significant influence on benzene and total
BTX production. A number of other operating variables were also of significance
in influencing pollutant production. Heating rate was found to be influential
in the yield of the PNA fraction of the tar.
The statistical analysis also showed that increases in both the air-to-
steam ratio and the bed temperature decreased the yield of several of the
major pollutants. However, no significant correlation existed between the
71
-------
selected independent variables and the yields of phenol and naphthalene.
Since phenol is the primary pollutant in the gasifier condensate, a mechanis-
tic approach to explaining the production of phenol rather than the statis-
tical approach is warranted.
The screening test runs have been extremely useful in providing operating
experience with a unique experimental facility. The simultaneous function of
the reactor facility, signal processing system, and sampling system has required
check-out procedures and numerous troubleshooting tasks. The successful
operation of a gasification process in which feed materials and operating
variables are intentionally being changed for experimental purposes gives rise
to complexities in chemical process control. However, a versatile system has
been established and prepared for parametric test runs.
Parameters for gasification tests are pressure, temperature, coal particle
size, reactant flow rates, and coal additives. Hence, operation of the test
facility under carefully controlled conditions in which specifically determined
variables are set at preselected values will be performed and analyzed. This
is intended to provide basic data for the understanding of pollutant formation
during coal gasification.
72
-------
REFERENCES
1. Cleland, J. G., F. 0. Mixon, D. G. Nichols, C. f1. Sparacino, and D. E.
Wagoner, "Pollutants from Synthetic Fuels Production: Facility Con-
struction and Preliminary Tests," U.S. Environmental Protection Agency,
EPA-600/7-78-171, August 1978.
2. Gangwal, S. K., P. M. Grohse, D. E. Wagoner, D. J. Mi nick, C. M. Sparacino,
and R. A. Zweidinger, "Pollutants from Synthetic Fuels Production:
Sampling and Analysis Methods for Coal Gasification," U.S. Environmental
Protection Agency, EPA-600/7-79-201, August 1979.
3. Nichols, D. G., J. G. Cleland, D. A. Green, F. 0. Mixon, T. J. Hughes,
and A. W. Kolber, "Pollutants from Synthetic Fuels Production: Environ-
mental Evaluation of Coal Gasification Screening Tests," U.S. Environ-
mental Protection Agency, EPA-600/7-79-202, August 1979.
4. Gillmore, D. W., and A. J. liberators, "Pressurized, Stirred, Fixed-Bed
Gasification," in; Symposium Proceedings: Environmental Aspects of
Fuel Conversion Technology, II (December 1975, Hollywood, Florida), U.S.
Environmental Protection Agency, EPA-600/2-76-149, pp. 125-132, June
1979.
5. Cavanaugh, E. C., W. E. Corbett, and G. C. Page, "Environmental Assessment
Data Base for Low/Medium-Btu Gasification Technology: Vol. I, Technical
Discussion," U.S. Environmental Protection Agency, EPA-600/7-77-125a,
November 1977.
6. Cavanaugh, E. C., W. E. Corbett, and G. C. Page, "Environmental Assessment
Data Base for Low/Medium-Btu Gasification Technology: Vol. II, Appendices
A-F," U.S. Environmental Protection Agency, EPA-600/7-77-125b, November
1977. .
7. Hauk, R., et al., "Gas-Wasserfach, Gas-Erdgas," 118: No.10, 427-340,
October 1977.
8. Page, C. C., "Application of Environmental Assessment Methodology,"
Working Paper, Radian Corporation, 1978. (See EPA-600/7-78-022, October
1978).
9. Lewis, P. S., "A Study of Stirred, Fixed-Bed Gas Producer Behavior with
Caking Coals," in: Proceedings of Fourth National Conference on Energy
and the Environment, AIChE/APCA, pp. 43-49, October 1976.
10. Attari, A., J. Pau, and M. Mensinger, "Fate of Trace and Minor Constituents
of Coal During Gasification," U.S. Environmental Protection Agency, EPA-
600/2-76-258, September 1976.
11. Somerville, M. H., and J. L. Elder, "A Comparison of Trace Element Analyses
of North Dakota Lignite Laboratory Ash with Lurgi Gasifier Ash and Their
Use in Environmental Analyses," jn_: Symposium Proceedings: Environmental
Aspects of Fuel Conversion Technology, III, (September 1977, Hollywood,
Florida), U.S. Environmental Protection Agency, EPA-600/7-78-063, pp. 292-
315, April 1978.
73
-------
12. Forney, A. J., W. P. Haynes, S. J. Gasior, R. M. Kornosky, C. E. Schmidt,
and A. G. Sharkey, "Trace Elements and Major Component Balances Around
the Synthane PDU Gasifier," in: Symposium Proceedings: Environmental
Aspects of Fuel Conversion Technology, II (December 1975, Hollywood,
Flordia), U.S. Environmental Protection Agency, EPA-600/2-76-149, pp.67-
81, June 1976.
13. Statistical Analysis System Users Guide. 1979 Edition, SAS Institute,
P. 0. Box 10066, Raleigh, NC 27605.
14. Handbook of Gasifiers and Gas Treatment Systems, FE-1772-11, Dravo
Corporation, Pittsburgh, PA, February 1976.
15. Ad Hoc Panel on Low-Btu Gasification of Coal, National Research Council,
"Assessment of Low-and Intermediate-Btu Gasification of Coal," National
Academy of Sciences, Washington, DC, 1977.
74
-------
APPENDICES
I. Signal Processing System-
II. Pollutant Production Factors
75
-------
APPENDIX I
SIGNAL PROCESSING SYSTEM
The laboratory reactor facility which has been used to study coal gasi-
fication and pollutant generation is equipped with versatile signal processing
and data handling capabilities. The hardware includes an on-line digital
processor, i.e., the central processing unit, as well as quick-response
accessories. Detectors for temperatures, pressures, flow rates, and chemical
compositions are connected directly to the experimental facility, as shown in
Figure 17. Signals from these detectors or monitors move directly to the
industrial control (remote), i.e., ICR, where signal conversion and con-
ditioning occurs. The ICR is connected directly to the CPU, which is a POP
11/34. Operator access to the CPU may be achieved via a console at the CPU
or a terminal near the experimental system.
Generally, four modes of system operation are in use. The first mode
represents "system generation" activities, i.e., software introduction and/or
modification. The second operational mode is that of real-time signal
processing, i.e., the activity which involves experimental runs on the
laboratory gasifier and/or real-time chemical analysis operations using gas
chromatographs. Next, the post-experimental data processing activity is
conducted. The fourth mode" of system function is that of batch processing,
i.e., the execution of user prepared programs in source (FORTRAN) language.
The functional states of the signal processing system which are active
for the performance of experimental gasification tests are shown in Figure
18. Before the tests, scan condition and display inputs are provided along
with test parameters, and load and start instructions. During the gasifi-
cation tests, data are stored, print and store alarms are activated; and,
other user overrides are instituted. Subsequent to each gasification test, a
run log is produced and data accumulated during the run are processed to
determine average temperatures, flow rates, compositions and other relevant
data values. Carbon conversion and steam conversion values are also computed.
Signal processor function 1n support of gas chromatograph (GC) analyses
is also an important component of system use. As shown in Figure 19, various
system operations take place before, during, and after the GC analyses.
Before GC runs, the operator introduces input parameters and calibration
76
-------
Mass
Console
C.P.U.
Storage
Room Divider
Experimental
System
I.C.R.
GC
GC
GC
Terminal
1. Decwriter (LA-36)
2. Central Processing Unit
(POP 11/34)
3. Dual Disk Drives (RK05)
4. Coal Gasification Process
5. Industrial Control, Remote
6. Gas Chromatograph Units
7. Video Terminal (VT-52)
Figure 17. Signal processing hardware configuration.
77
-------
Hardware
Diagnostics
Before Gasification Test
Define &
Store Test
Parameters
Scan, Condition,
& Display Inputs
Load Test
Parameters &
Start the Test
During Gasification Test
After Gasification Test
Stop
Scan
Store Test
Data
Stop
Test
Log and/or Analyze
Test Data
Print &
Store Alarms
Figure 18. Signal processor function relative to gasification tests,
78
-------
Hardware
Diagnostics
Before GC Run
Scan,
Condition,
& Display
Inputs
Prepare,
Modify, or
Recalibrate
Analysis Method
Call Method
& Start
Extract
& Store
Peak Data
During GC Run
Stop GC
Run
After GC Run
Stop
Scan
Identify Peak*
& Compute
Concentrations
Print Report
of GC Run
Call New
Analysis Method
if Wanted
Load Stored
Data &
Analyze Again
Figure 19. Signal processor function relative to GC analyses,
79
-------
instructions. During operation of the gas chromatographs, the signal pro-
cessor is receiving input data through an analog/digital converter interface.
After the GC run, the signal processing system is activated to determine
residence times for compound identification as well as the integration and
correction of peak areas for an accurate determination of the concentration of
each species being analyzed. Next, a report is printed of the results of the
GC runs.
The various software packages which have been prepared in this project in
support of gasification test run monitoring, gas chromatograph operation and
data analysis are shown in Figure 20. This figure displays the functional
interrelations among the software packages and the signal processing system
hardware. It may be noted that most of the software serves a supervisory
function. As such, these software packages provide the capability for on-line
data collection, system monitoring, and process variable manipulation. Thus,
accurate and comprehensive data collection can be achieved. Further the
continuous monitoring of specific process variables permits control over the
range of these variables and immediate response should the level of a critical
variable, e.g., reactor temperature or pressure, exceed its safety threshold.
The software packages which have been implemented in support of GC data
collection and analysis include programs to achieve input/output, perform peak
integration including baseline correction, compute test parameters, list
parameters, assemble and store data, generate summary reports, etc. A cap-
ability for achieving simultaneous use of two or more GC systems is being
developed.
80
-------
DIALOG
COMMAND
INTERPRETER
VIDEO AND
HARD-COPY
TERMINALS
oo
Figure 20. Signal processing software system.
-------
APPENDIX II
POLLUTANT PRODUCTION FACTORS
(g produced/g coal loaded)
82
-------
TABLE I1-1.
POLLUTANT PRODUCTION IN COAL GASIFICATION—RUN N0.16:
ILLINOIS NO.6 COAL
g produced/g coal loaded
H2S
COS
cs2
methanethiol
e thane thiol
thiophene
methyl thiophene
ammoni a
benzene
tol uene
xyl enes
phenol
cresols
xylenols
chrysene
perylene
pyrene
fluorene
anthracene
naphthalene
biphenyl
Indene
benzofuran
di benzofuran
aniline
GAS
2.1E-2
2.2E-4
4.2E-5
2'.2E-5
l.OE-3
1.8E-4
N/A
2.8E-3
2.0E-2
4.9E-5
1.3E-5
1.1E-5
2.5E-7
1.8E-8
1.4E-6
7.0E-5
l.OE-6
2.3E-4
3.3E-4
CONDENSATE
2.2E-4
3.8E-4
TAR
,
7.8E-6
1.9E-5
6.4E-5
2.7E-6
3.9E-4
6.1E-4
3.2E-7
TOTAL
2.1E-2
2.2E-4
4.2E-5
2.2E-5
N/A
l.OE-3
1.8E-4
N/A
2.8E-3
2.0E-2
4.9E-5
2.4E-4
4.1E-4
N/A
N/A
N/A
6.4E-5
2.7E-6
3.QE-4
6.8E-4
l.OE-6
2.3E-4
3.3E-4
3.2E-7
N/A
83
-------
TABLE II-2.
POLLUTANT PRODUCTION IN COAL GASIFICATION—RUN NO.21
ILLINOIS NO.6 COAL
g produced/g coal loaded
H2S
COS
cs2
methanethiol
ethanethiol
thiophene
methylthiophene
ammonia
benzene
toluene
xylenes
phenol
cresols
xylenols
chrysene
perylene
pyrene
fluorene
anthracene
naphthalene
blphenyl
indene
benzofuran
di benzofuran
aniline
GAS
2.2E-2
1.2E-4
3.0E-5
5.0E-5
3.6E-4
6.0E-4
7.8E-4.
2.6E-4
8.3E-5
2.0E-4
2.0 E-4
4.8E-6
5.0 E-4
5.6E-6
5.6E-6
6.3 E-5
3.0E-5
CONDENSATE
8.7E-3
l.OE-4
2.4E-4
1.5E-4
TAR
9.4E-5
3.6E-4
8.7E-5
2.6E-4
2.9E-4
2.6E-4
1.9E-3
2.4E-4
8.7E-6
TOTAL
2.2E-2
1.2E-4
3.0E-5
5.0E-5
N/A
3.6E-4
6.0E-4
9.5E-3
N/A
N/A
2.6E-4
2.8E-4
8.0E-4
4.4E-4
2.6E-4
N/A
2.9E-4
2.6E-4
4.8E-6
2.4E-3
5.6E-6
5.6E-6
6.3E-5
2.7E-4
8.7E-6
84
-------
TABLE II-3.
POLLUTANT PRODUCTION IN COAL GASIFICATION—RUN NO.23
ILLINOIS NO.6 COAL
g produced/g coal loaded
H2S
COS
cs2
methanethiol
ethanethiol
thiophene
methylthiophene
ammonia
benzene
tol uene
xyl enes
phenol
cresols
xyl enol s
chrysene
perylene
pyrene
fluorene
anthracene
naphthalene
biphenyl
indene
benzofuran
dibenzofuran
aniline
GAS
5.9E-2
3.4E-4
1.5E-4
3.1E-5
1.3E-6*
2.3E-3
6.6E-4
8.7E-3
3.1E-3
3.8E-4
1.3E-4
3.1E-4
4.1E-6
2.0E-3
9.3E-6
2.2E-4
1.9E-4
4.1E-5
CON DENS ATE
1.9E-4
2.4E-4
9.3E-5
TAR
1.5E-4
4.5E-4
3.5E-4
2.8E-4
1.2E-4
3.5E-4
1.5E-5
2.4E-4
8.5E-4
1.7E-4
6.1E-6
TOTAL
5.9E-2
3.4E-4
1.5E-4
3.1E-5
1.3E-6
2.3E-3
6.6E-4
N/A
8.7E-3
3.1E-3
3.8E-3
4.7E-4
l.OE-3 .
4.4E-4
2.8E-4
1.2E-4
3.5E-4
1.5E-5
2.4E-4
2.9E-3
9.3E-6
2.2E-4
1.9E-4
2.1E-4
*Includes dimethyl sulfide.
85
-------
TABLE II-4.
POLLUTANT PRODUCTION IN COAL GASIFICATION—RUN NO.41
WESTERN KENTUCKY NO.9
g produced/g coal loaded
H2S
. COS
cs2
methanethiol
ethanethiol
thiophene
methyl thiophene
ammonia
benzene
to! uene
xylenes
phenol
cresols
xylenols
chrysene
perylene
pyrene
fluorene
anthracene
naphthalene
blphenyl
Indene
benzofuran
dlbenzofuran
aniline
GAS
2.7E-2
5.7E-4
7.5E-7
3.8E-5
1 . 1 E-4*
2.7E-4
3.3E-4
1.3E-2
1.7E-3
2.8E-4
3.6E-4
2.4E-4
6.9E-6
2.1E-3
5.7E-6
5.0E-4
1.2E-4
3.5E-6
CONDENSATE
4.2E-4
3.8E-4
5.3E-5
TAR
3.6E-5
2.6E-4
1.4E-4
7.2E-4
2.3E-4
6.8E-4
2.6E-4
2.4E-4
6.3E-7
TOTAL
2.7E-2
5.7E-4
7.5E-7
3.8E-5
1.1E-4
2.7E-4
3.3E-4
N/A
1.3E-2
1.7E-3
2.8E-4
8.2E-4
8.8E-4
1.9E-4
N/A
N/A
7.2E-4
2.3E-4
6.8E-4
2.7E-3
5.7E-6
5.0E-4
1.2E-4
2.4E-4
6.3E-7
*Includes dimethyl sulfide.
86
-------
TABLE II-5.
POLLUTANT PRODUCTION IN COAL GASIFICATION—RUN NO.25
MONTANA ROSEBUD COAL
g produced/g coal loaded
H2S
COS
cs2
methanethiol
ethanethiol
thiophene
methylthlophene
ammonia
benzene
tol uene
xylenes
phenol
cresols
xylenols
chrysene
perylene
pyrene
fluorene
anthracene
naphthalene
biphenyl
Indene
benzofuran
dibenzofuran
aniline
GAS
2.5E-3
8.0E-5
2.2E-6
2.8E-5
5.9E.-6
5.9E-4
3.6E-4
5.4E-4
4.8E-4
8.0E-5
2.8E-5
5.6E-5
1.6E-6
l.OE-4
1.6E-6
8.3E-5
2.6E-5
2.3E-6
CONDENSATE
4.2E-3
2.6E-4
1.1E-4
9.6E-6
TAR
7.6E-5
1.4E-4
4.1E-5
1.3E-4
4.8E-4
1.8E-4
1.3E-4
1.1E-4
2.1E-4
9.6E-5
6.8E-7
TOTAL
2.5E-3
8.0E-5
N/A
2.2E-6
N/A
2.8E-5
5.9E-6
4.8E-3
3.6E-3
5.4E-4
4.8E-4
4.2E-4
2.8E-4
1.1E-4
1.3E-4
4.8E-4
1.8E-4
1.3E-4
1.1 E-4
3.1E-4
1.6E-6
8.3E-5
2.6E-5
9.8E-5
6.8E-7
87
-------
TABLE II-6.
POLLUTANT PRODUCTION IN COAL GASIFICATION-RUN MO.33
WYOMING SUBBITUMINOUS COAL
g produced/g coal loaded
H2S
COS
cs2
methanethiol j
ethanethiol
thiophene
; methylthiophene
ammonia
benzene
to! uene
xylenes
phenol
cresols
xylenols
chrysene
perylene
pyrene
fluorene
anthracene
naphthalene
biphenyl
indene
benzofuran
dibenzofuran
aniline
GAS
1.9E-3
'1.1E-4
1.4E-5
9.1E-6
l.OE-4
4.6E-3
1.8E-3
4.6E-4
1.2E-3
3.3E-4
1.4E-3
2.4E-6
2.6E-4
6.3E-6
5.5E-4
1.8E-5
CONDENSATE
.
1.3E-4
1.4E-4
5.1E-5
TAR
-
1.6E-4
3.5E-5
2.7E-4
2.0E-5
1.3E-5
2.6E-5
5.7E-5
8.3E-5
8.9E-5
4.1E-5
8.7E-7
TOTAL
1.9E-3
1.1E-4
N/A
1.4E-5
N/A
9.1E-6
l.OE-4
N/A
4.6E-3
1.8E-3
4.6E-4
1.5E-3
5.1E-4
1.7E-3
2.0E-5
1.3E-5
2.6E-5
5.7E-5
8.5E-5
3.5E-4
6.3E-6
5.5E-4
N/A
5.9E-5
8.7E-7
-------
TABLE II-7.
POLLUTANT PRODUCTION IN COAL GASIFICATION—RUN NO.35
WYOMING SUBBITUMINOUS COAL
g produced/g coal loaded
H2S
COS
cs2
methanethiol
ethanethiol
thiophene
methyl thiophene
ammonia
benzene
tol uene
xylenes
phenol
cresols
xylenols
chrvsene
perylene
pyrene
fluorene
anthracene
naphthalene
biphenyl
Indene
benzofuran
dibenzofuran
aniline
GAS
3.8E-3
2.0E-4
2.5E-5
3.0E-5
3.0E-5
3.8E-3
2.2E-3
8.0E-4
6.0E-4
2.8E-4
7.1E-4
1.2E-6
8.5E-5
3.0E-6
1.4E-4
l.OE-4
7.3E-6
CON DENS ATE
6.8E-4
4.1E-4
8.5E-5
TAR
3.2E-4
7.8E-4
4.9E-4
2.0E-5
6.9E-6
3.5E-5
4.9E-5
7.6E-5
4.7E-5
4.1E-5
1.4E-6
TOTAL
3.8E-3
2.0E-4
N/A
2.3E-5
N/A
3.0E-5
3.0E-5
N/A
3.8E-3
2.2E-3
8.0E-4
1.6E-3
1.5E-3
1.3E-3
2.0E-5
6.9E-6
3.5E-5
4.9E-5
7.7E-5
1.3E-4
3.0E-6
1.4E-4
l.OE-4
4.8E-5
1.4E-6
89
-------
TABLE II-8.
POLLUTANT PRODUCTION IN COAL GASIFICATION-RUN NO.36
NORTH DAKOTA ZAP LIGNITE
g produced/g coal loaded
H2S
COS
cs2
methanethlol
ethanethiol .
thiophene
methyl thiophene
ammonia
benzene
toluene
xyl enes
phenol
cresols
xylenols
chrysene
perylene
pyrene
fluorene
anthracene
naphthalene
biphenyl
indene
benzofuran
dibenzofuran
aniline
GAS
2.3E-3
1.7E-4
7.9E-5
2.2E-5*
5.1E-4
1.3E-5
5.1C-3
1.4E-3
3.9E-4
1.6E-4
1.4E-4
4.9E-4
9.3E-7
2.3E-4
3.2E-6
7.9E-5
1.4E-5
CON DENS ATE
•
.
4.7E-4
2.5E-4
6.2E-5
TAR
4.7E-5
9.1E-5
7.1E-6
2.2E-5
6.9E-6
4.0E-5
4.0E-5
l.OE-4
1.8E-5
3.1E-5
TOTAL
2.8E-3
1.7E-4
N/A
7.9E-5
2.2E-5
5.1E-4
1.3E-5
N/A
5.4E-3
1.4E-3
3.9E-4
6.8E-4
4.8E-4
5.6E-4
2.2E-5
6.9E-6
4.0E-5
4.0E-5
l.OE-4
2.5E-4
3.2E-6
7.9E-5
1.4E-5
3.1E-5
N/A
'Includes dimethyl sulfide.
90
-------
TABLE I1-9.
POLLUTANT PRODUCTION IN COAL GASIFICATION—RUN NO.43
NORTH DAKOTA ZAP LIGNITE
g produced/g coal loaded
H2S
COS
cs2
methanethiol
ethanethiol
tniophene
methylthiophene
ammonia
benzene
to! uene
xylenes
phenol
cresols
xylenols
chrysene
perylene
pyrene
fluorene
anthracene
naphthalene
biphenyl
indene
benzofuran
dibenzofuran
aniline
GAS
1.4E-3
2.7E-4
6.7E-6
1.1E-5
1 . 3E-5*
8.9E-6
3.5E-5
1.6E-3
9.1E-4
2.9E-4
1.9E-5
1.1E-4
8.1E-7
4.0E-6
.5.1E-5
2.1E-6
2.2E-4
6.3E-5
7.7E-7
CONDENSATE
1.2E-3
6.9E-4
1.4E-4
TAR
3.7E-5
1.2E-4
8.7E-4
4.2E-5
6.3E-7
9.5E-6.
2.9E-5
4.9E-5
2.6E-5
3.4E-5
2.7E-8
TOTAL
1.4E-3
2.7E-4
6.7E-6
1.1E-5
1.3E-5
8.9E-6
3.5E-5
N/A
1.6E-3
9.1E-4
2.9E-4
1.3E-3
9.2E-4
l.OE-3
4.2E-5
6.3E-7
9.5E-6
2.9E-5
5.3E-5
7.7E-5
2.1E-6
2.2E-4
6.3E-5
3.4E-5
2.7E-8
91
-------
TECHNICAL REPORT DATA
(Pleas* read Instructions on the reverse before completing}
1. REPORT NO. ~~
EPA-600/7-79-200
2.
3. RECIPIENT'S ACCESSION NO.
4-TITL5ANOSU8T'TI-6 Pollutants from Synthetic Fuels Pro-
auction: Coal Gasification Screening Test Results
3. REPORT DATE
August 1979
6. PERFORMING ORGANIZATION CODE
HOR(S) J.G.Cleland, S.K.Gangwal, C. M.Sparacino,
R.M. Zweidinger, D.G.Nichols, andF.O.Mixon
7. AUTI
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING OROANIZATION NAME AND ADDRESS
Research Triangle Institute
P.O. Box 12194
Research Triangle Park, North Carolina 27709
10. PROGRAM ELEMENT NO.
EHE623A
11. CONTRACT/GRANT NO.
Grant R804979
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
NO PERIOD COVERED
13. TYPE OF REPORT AND PERIOD CC
Task Final; 8/78 - 7/79
14. SPONSORING AGENCY CODE
EPA/600/13
is.SUPPLEMENTARY NOTES ffiRL-RTP project officer is N. Dean Smith, Mail Drop 61, 919/
541-2708. Grant-related reports include EPA-600/7-78-171, EPA-600/7-79-201, and
EPA-600/7-79-202.
O. ABSTRACT
The report gives screening results of 38 coal gasification tests in a semi-
batch, fixed-bed laboratory gasifier to evaluate various coals and operating condi-
tions for pollutant generation. The tests involved char, coal, lignite, and peat. Reac-
tor temperatures ranged from 790 C to 1035 C with high carbon and sulfur conversions
in the bed. Extensive analyses were performed for organic and inorganic compounds
and trace elements in the tars and hydrocarbon oils, aqueous condensates, and reac-
tor residues resulting from the gasification tests. Over 450 compounds were identi-
fied from the various gasifier streams: more than 100 of the compounds were quanti-
fied for several of the test runs. Statistical analyses have been performed on the
data. The quantity and composition of the various samples have been examined in
relation to coal type and operating variables. Results are reported for sulfur species
in the product gas stream, for consent decree pollutants contained as volatile orga-
nic compounds in the product gas, for phenol and related compounds in the aqueous
condensate and tar/oil sample, and for PNA species in the tar /oil.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Pollution
Coal Gasification
Charcoal
Coal
Lignite
Peat
Sulfur
Phenol
Polycyclic Compounds
Aromatic Compounds
b.lOENTIFIERS/OPEN ENDED TERMS
Pollution Control
Stationary Sources
Synthetic Fuels
Char
Consent Decree Pollu-
tants
Polvnuclear Aromatics
c. COSATI Field/Group
13 B
13H
21D
07B
07C
13. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
100
20. SECURITY CLASS /Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9>73)
92
------- |