HEW
EPA
United States Public Health Service, Center for Disease Control DHEW(NIOSH)Pub. No. 78-120
Department of Health, National Institute for Occupational Safety and Health
Education, and Welfare Cincinnati, Ohio 45226
United States Office of Energy, Minerals, and Industry
Environmental Protection Office of Research and Development
Agency Washington, D.C. 20460
EPA-600/7-78-007
January 1978
RECOMMENDED HEALTH AND
SAFETY GUIDELINES FOR
COAL GASIFICATION
PILOT PLANTS
Interagency
Energy-Environment
Research and Development
Program Report
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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 in 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 protectthe 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.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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RECOMMENDED HEALTH AND SAFETY GUIDELINES FOR
COAL GASIFICATION PILOT PLANTS
NATIONAL INSTITUTE FOR OCCUPATIONAL
SAFETY AND HEALTH
Rockville, Maryland 20857
ENVIRO CONTROL, INC.
Rockville, Maryland 20852
Contract No. 210-76-0171
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Center for Disease Control
National Institute for Occupational Safety and Health
Division of Criteria Documentation and Standards Development
Cincinnati, Ohio 45226
January 1978
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DISCLAIMER
The Division of Criteria Documentation and Standards Development, National
Institute for Occupational Safety and Health, had primary responsibility for
development of the recommended health and safety guidelines for coal gasifi-
cation pilot plants. The division review staff for
of Richard A. Rhoden, Ph.D. (chairman), Frank L.
Paul E. Caplan.
~ • ^j —
this document consisted
Mitchell, D.O., and
Enviro Control, Inc., prepared the document under contract No. 210-76-0171
for consideration by NIOSH staff. Murray L. Cohen had NIOSH program responsi
bility and served as Project Officer.
The views expressed and conclusions reached in this document are the result
of careful review of the available evidence, and consideration of comments
from external reviewers. These views and conclusions, however, are not
necessarily those of the external reviewers or of the contractor.
Partial funding of this project was provided
by the Environmental Protection Agency under
the Energy/Environmental R and D Program.
DHEW (NIOSH) Publication No. 78-12®
11
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PREFACE
The Occupational Safety and Health Act of 1970 emphasizes the need
for standards to protect the health and safety of workers exposed to
an ever-increasing number of potential hazards at their workplace.
The National Institute for Occupational Safety and Health has pro-
jected a formal system of research, with priorities determined on the
basis of specified indices, to provide relevant data from which valid
criteria for effective standards can be derived.
This document has been developed as part of the Interagency Energy and
Environment Research and Development Program. It's purpose is to
identify potential hazards to workers in coal gasification pilot plants,
and to develop hazard control strategies. The guidelines emphasize
worker protection measures such as safe work practices, personal pro-
tective equipment and clothing, industrial and personal hygiene, work-
place and medical monitoring, labeling and posting, hazard information
and awareness, and recordkeeping.
Although this document is specific for pilot scale coal gasification
plants, many of the potential hazards and research and development
needs are similar to those in bench or demonstration scale coal
gasification or coal liquefaction facilities. The recommended health
and safety guidelines are in many ways applicable to these facilities
as well. This document should also be a valuable reference for re-
searchers and administrators responsible for the development and
operation of these related coal conversion implementation of these
guidelines in experimental coal conversion facilities will not only
help protect the health and safety of today's workers, but will also
make occupational health and safety research an integral part of
the development of coal conversion technology. In this way, hazards
can be identified and effective control technology can be developed
prior to the design and construction of commercial coal gasification
plants.
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CONTENTS
Pneface iii
Introduction 1
Coal gasification: Process discussion 4
Health effects 69
Employee health protection program 86
Monitoring the work environment 109
Medical monitoring 117
Safety 125
Recommendati ons for further research 138
References 146
Appendixes
A. Possible constituents of gasifier off-gas 156
B. Standards for materials known to be present or possibly
present in coal gasification plants 168
C. Monitoring equipment 171
D. Recommended method for analysis of benzene soluble
fraction total particulate matter (BSFTPM) 174
E. Detailed process information 176
Glossary 226
FIGURES
1. Representation of high-volatile bituminous coal
structure (Wiser 1973) 4
2. Synthane coal gasification pilot plant 14
3. Synthane coal gasification process (coal preparation) 16
4. Petrocarb lockhopper system 19
5. Coal pretreatment section, HYGAS start-up configuration 23
6. Pretreater and gasifier—Synthane Pilot Plant 24
7. Hydrogasification reactor, start-up configuration —
HYGAS>ilot Plant 24
8. Gas quench and scrubbing system, Synthane Pilot Plant 43
9. Carbon monoxide shift conversion, Synthane Pilot Plant 51
10. Acid gas scrubbing — Benfield system, Synthane
Pilot Plant 52
11. Selexol flow sheet for a gas containing large amounts
of both H2S and CQ2 •••• ". 57
12. Tube wall reactor methanation, Synthane Pilot Plant 60
13. Hot gas recycle methanation, Synthane Pilot Plant 61
14. Acid gas processing, Synthane Pilot Plant 64
15. Claus "once through" process flow scheme 65
16. Holmes-Stretford sulfur recovery, Synthane Pilot Plant 67
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CONTENTS
17. Products and their carcinogenicity summarized 71
18. Days at which 25% of mice were tumorous versus daily dose
and cumulative dose of BaP (yg) 81
19. Safe work permit (C02 Acceptor Pilot Plant) 88
20. Pump and shutoff valve „ go
21. Doubl e 1 ocker room 97
22. Job safety analysis sample form 129
23. Schematic for low-temperature, laser-excited
BaP mom" tor 142
TABLES
1. Mean analytical values for 101 bituminous coals 6
2. Second generation coal gasification processes under
consideration 9
3. Coal gasification systems used as references 10
4. A synopsis of unit operations at seven coal gasification
research facilities . 12
5. Gasifier products 13
6. Analyses of drainage from two industrial coal piles 17
7. Coal pretreatment yields 22
8. Mass spectrometric analyses of Synthane benzene
soluble tar 28
9. Organic compounds condensed from the Synthane
gasification process (bench scale unit) 30
10. Components in Synthane Gasifier Gas (25 Ib/hr coal
feed bench scale gasifier) 31
11. Decreased phenol production with increased depth
of fresh coal injection 33
12. Steady-state effluent production rates: free-fall,
shallow-bed, and deep bed injections of North Dakota
lignite into the Synthane 25 Ib/hr bench scale gasifier 34
13. Sulfur distribution 35
14. HYGAS Pilot Plant liquid effluent characteristics,
hydrogasification of Montana lignite, Run 37 35
15. Trace elements — estimated volatility 37
16. Trace element concentration at various stages of the
HYGAS gasification process, calculated on a raw
coal basis for Pittsburgh #8 38
17. Char and ash analyses 41
18. Trace elements in condensate, coal gasification tests 47
19. Composition of effluent condensate • 48
20. HYGAS Pilot Plant, vent gas compositions, Montana
1 i gni te • f9
21. Gas purification: Synthane Pilot Plant 54
22. Sulfur components in acid gas stream, Run 37, HYGAS
Pi 1 ot PI ant Montana 1 i gni te • |°
23. Acid gas feed compositions to sulfur removal umt o^
24. Synthane sulfur removal plant product • •••• •
25. Relative risk of death for selected causes by coke
oven subdivisions for coke oven workers (1951-l%bj /J
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CONTENTS
Relative risk of death for selected causes by length of
employment at entry to study for coke oven workers 73
27. Mean level of coal-tar pitch volatiles (mg/tn?) 73
28. Ratio of CO to some gas stream components 113
A-l. Possible constituents of gasifier off-gas categorized
by boi 1 i ng range 157
A-2, Index of individual tar acids from low-temperature
bituminous tar based on boiling range "162
A-3. Index of individual tar bases from low-temperature
bituminous tar (based on boiling range) 165
Standards for materials known to be present in coal
gasification plants 169
Standards for materials possibly present in coal
gasification plants 170
CO moni tors 172
H-S monitors 173
vn
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INTRODUCTION
NEED FOR HEALTH AND SAFETY MEASURES
The United States Energy Research and Development Administration estimates
that by the year 2000 coal gasification products will be supplying 8.6 X 1015
Btus/year towards our national energy demand (Energy Research and Development
Administration 1976), at which time this industry may employ 140,000 workers.
To develop coal gasification technology, the Federal Government and private
industry are investigating at least 21 different approaches at the theoretical,
bench, or pilot plant stages. Currently there are 16 pilot plants either in
operation or expected to begin operation within the next 3 years, each
employing between 80 and 200 workers.
The pilot plant worker may be exposed to chemical and physical health and
safety hazards. The potential toxic hazards are the focus of this document
because they may cause serious health effects. These hazards are generally
less well understood than the other hazards, and protective measures against
them are less well established. The toxic hazard potentials are assessed on
the basis of the known presence of a variety of toxicants in process streams
and wastes, the probability of emissions through leaks and equipment failure,
and the necessity for opening, and perhaps entering, equipment.
The presence of potential toxic hazards, including that of exposure to
chemical carcinogens, is established. Therefore, measures that protect the
health and safety of coal gasification workers are needed.
PRIORITY GIVEN TO PILOT PLANTS
The focus of this document is on pilot plants for the following reasons:
Several of the coal gasification pilot plants are now in operation, and they may
be without adequate control measures to protect worker health and safety.
A special approach to develop these measures is required because pilot plants
are, in addition to size differences, significantly different from demonstra-
tion and commercial scale plants in operational characteristics. No commer-
cial plant, based on present pilot plant technology, will be in operation in
the United States before 1985 at the earliest. The pilot plants are the only
observable domestic models of working conditions. Their study will provide a
useful and appropriate basis for future development of recommended standards
for occupational safety and health protection in commercial coal gasification
plants.
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CHARACTERISTICS OF PILOT PLANTS
The pilot plant is a hybrid of specially designed and makeshift equipment.
Although it is much larger than a laboratory unit, by a factor of perhaps 100,
little of its equipment would be useful in a commercial-size plant. Apart
from the gasifier, few of the components have been designed for the highly
specialized operating conditions of coal gasification. Even with the best of
engineering know-how, exploration of new processes is attended by unforeseen
problems and failures. This is one of the major reasons for the pilot plant
stage of process development.
The pilot plant is designed primarily to obtain process data in order to
define the engineering specifications required to build larger plants,
determine the best materials of construction, and develop work practices and
equipment for optimum operation. Process testing often occurs under
non-optimum conditions, which may cause run failure. In this event, the en-
tire plant is generally shut down, as there is insufficient surge volume to
permit one section to run independently of the others. Thus, frequent shut-
down, cleanup, repair, modification, maintenance, and start-up constitute major
portions of the pilot plant cycle. Due to the continual replacement of
equipment, a coal gasification pilot plant will have less than 35% onstream
operating time.
Pilot plants may therefore be expected to have more leaks, be subject to more
emergencies, and undergo much more dismantling of equipment for maintenance,
repair, or modification than commercial scale plants.
CHARACTERISTICS OF EXPOSURE AND PERTINENT HEALTH DATA
The pilot plant worker may be exposed to toxicants by inhalation of gases or
airborne particles, skin deposition of airborne material, contact with con-
taminated surfaces, and accidental ingestion. In maintenance operations,
liquid and solid residues may be encountered that would not ordinarily
constitute normal operational hazards.
The range of toxicants and possible health effects is extremely wide, from
simple chemicals like carbon monoxide to complex mixtures of organic carcino-
gens. This complexity is further complicated by the special problems
associated with carcinogens: long latent period, doubt about "safe" levels,
and unpredictable multiagent interactions.
These conditions cannot be met by protective measures, monitoring procedures,
and medical tests that are simply the sum total of controls for each indi-
vidual toxicant. The complexity of the potential hazards calls for
innovative control strategies.
Few data are available concerning the workplace environment and other
occupational health factors in coal gasification plants. The somewhat better
documented health hazards of coke ovens, coal liquefaction, and^similar plants
are relevant, but not fully acceptable as models for coal gasification.
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APPROACH TO DOCUMENT DEVELOPMENT
Because of the foregoing considerations, this document has been oriented
towards processes rather than towards specific toxic hazards. The sequence
and structure of the document are as follows:
t A representative process is described in detail and significant
differences in other processes are noted.
• Toxicants and potentially hazardous operations are identified.
• Health effects associated with the toxicants are reviewed, including
diseases observed in association with coal processing.
• On the basis of identified potential hazards, guidelines for worker
protection are prescribed: engineering controls, work practices,
workplace monitoring, medical surveillance, personal protection.
• Monitoring procedures are recommended to meet the perceived needs for
environmental sampling and medical surveillance.
• Safety hazards are discussed, and safety measures are presented.
0 Recommendations are made for research and development to meet
identified gaps in knowledge and technology for worker health and
safety protection.
THE DOCUMENT
These guidelines are deemed appropriate for the pilot plant stage of develop-
ment of advanced coal gasification technology. They are based on pilot plant
experience thus far, and on known hazards and control procedures in analogous
industries. It is recognized that no two coal gasification pilot plants are
alike in process technology or hazards. Additionally, workplace conditions
are variable at any one plant.
Those responsible for health protection require information that they can
apply to their specific problems and operations. The document is therefore
designed to help the user by presenting evidence and rationale that can be
evaluated and modified or adjusted for application to individual circumstances
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COAL GASIFICATION: PROCESS DISCUSSION
INTRODUCTION
Coal
Coal, as shown schematically in Figure 1 below, is derived from decayed plant
material laid down in the vast swamps which covered large areas of the northern
hemisphere during the lower carboniferous to tertiary periods. This decayed
material (peat) was subjected to a variety of microbiological, geophysical,
and geochemical conditions, which varied not only from one section (or swamp)
to another but also within local regions. Consequently, any quantitative
statement concerning the composition, structure, and products of coal is
subject to variation, even for coal mined from the same general section of a
specific coal seam.
H/S-cf^Hz
(TH-^^H
Figure 1. Representation of high-volatile bituminous coal structure (wiser 1973).
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Coal is "ranked" systematically according to volatile matter and heat content
(Btu/lb). Coal rank depends on the extent of "coalifaction" and varies se-
quentially from the low-rank lignite through sub-bituminous and bituminous to
high-rank anthracite. In general, carbon content increases and volatile matter
decreases with increase in rank, while oxygen content correlates with decreas-
ing rank.
Coal is composed of organic and inorganic matter (up to 50%). The organic
elements include carbon, hydrogen, oxygen, nitrogen, and sulfur, all of which
are combustible except oxygen. The inorganic mineral matter present is
associated partly with the coal (organometallic) but primarily with the ash,
which ranges from 3-20 wt % in commercial coals and averages about 10 wt %.
Ash content reflects the degree of care in both mining and cleaning as well as
the intrinsic grade or quality of the coal itself. The variability of coal
composition is illustrated by the values for 101 bituminous coals shown in
Table 1. In short, coal is probably the most highly variable fuel used by
man. The products of any given coal in any given reaction (combustion,
pyrolysis, gasification, liquefaction, etc.) will differ from those of another
coal under similar circumstances. It is even impractical to operate some
processes with certain coals (e.g., coking with lignite or C02 Acceptor
gasification with bituminous coals). Despite the extreme variability, it is
possible to generalize about coal and coal reactions, providing that the
limitations are kept in mind.
Coal Gasification
Gasification of coal transforms a cumbersome, inconvenient, dirty solid fuel
into a convenient, clean, gaseous fuel, or into synthesis gas. The impetus
for this effort is that both the individual consumer and business have become
highly dependent upon natural gas. At the same time the rate of natural gas
production is and has been exceeding the rate at which new gas reservoirs are
being discovered and added to the supply system. Alternately our coal re-
serves are sufficient for approximately 300 years at the accelerated produc-
tion rates proposed in the recent national energy initiatives.
Gasification of coal entails the treatment of coal in a reducing atmosphere
with air, oxygen, steam, C02, or hydrogen or mixtures of these gases, to yield
a combustible product. The product of primary gasification of coal and of the
reaction of coal carbon with the gasifying agent is usually a mixture of H2,
H20, CO, C02, CHit, inerts (such as nitrogen), and minor amounts of hydrocarbons
and other impurities.
The product is called a low-Btu gas if an air-steam mixture is used directly
to gasify the coal and it contains nitrogen as a major component. Low-Btu
gas is suitable for use as an energy source near its point of generation, but,
because of its low Btu content, it is not economically attractive for long
distance transmission.
Intermediate-Btu gas (synthesis gas), which contains only a minor amount of
nitrogen, is obtained when oxygen-steam mixtures are used to gasify the coal.
Intermediate-Btu gas can be used either as an energy source or as a synthesis
gas for the production of chemicals and synthetic liquid and gaseous fuels.
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Table 1. Mean analytical values for 101 bituminous coals.a
Constituent
Arsenic
Boron
Beryl lium
Bromine
Cadmium
Cobalt
Chromium
Copper
Fluorine
Gallium
Germanium
Mercury
Manganese
Molybdenum
Nickel
Palladium
Lead
Antimony
Selenium
Tin
Vanadium
Zinc
Zirconium
Aluminum
Calcium
Chlorine
Iron
Potassium
Magnesium
Sodium
Silicon
Titanium
Organic Sulfur
Pyritic Sulfur
Sulfate Sulfur
Total Sulfur
Moisture
Volatile Matter
Fixed Carbon
Ash
Btu/lb
Carbon
Hydrogen
Nitrogen
Oxygen
High -Temperature Ash
Low- Temperature Ash
Mean
14.02 ppm
102.21 ppm
1.61 ppm
15.42 ppm
2.52 ppm
9.57 ppm
13.75 ppm
15.16 ppm
60.94 ppm
3.12 ppm
6.59 ppm
0.20 ppm
49.40 ppm
7.54 ppm
21.07 ppm
71 .10 ppm
34.78 ppm
1 .26 ppm
2.08 ppm
4.79 ppm
32.71 ppm
272.29 ppm
72.46 ppm
1.29 %
0.77 %
0.14 %
1.92 %
0.16 %
0.05 %
0.05 %
2.49 %
0.07 %
1.41 %
1.76 %
0.10 %
3.27 %
9.05 %
39.70 %
48.82 %
11.44 %
12,748
70.28 %
4.95 %
1.30 %
8.68 %
11.41 %
15.28 %
Standard
Deviation
17.70
54.65
0.82
5.92
7.60
7.26
7.26
8.12
20.99
1.06
6.71
0.20
40.15
5.96
12.35
72.81
43.69
1.32
1.10
6.15
12.03
694.23
57.78
0.45
0.55
0.14
0.79
0.06
0.04
0.04
0.80
0.02
0.65
0.86
0.19
1.35
5.05
4.27
4.95
2.89
464.50
3.87
0.31
0.22
2.44
2.95
4.04
Minimum
0.50
5.00
0.20
4.00
0.10
1.00
4.00
5.00
25.00
1.10
1.00
0.02
6.00
1.00
3.00
5.00
4.00
0.20
0.45
1.00
11.00
6.00
8.00
0.43
0.05
0.01
0.34
0.02
0.01
0.00
0.58
0.02
0.31
0.06
0.01
0.42
0.01
18.90
34.60
2.20
11,562.00
55.23
4.03
0.78
4.15
3.28
3.82
Maximum
93.00
224.00
4.00
52.00
65.00
43.00
54.00
61.00
143.00
7.50
43.00
1.60
181.00
30.00
80.00
400.00
218.00
8.90
7.70
51.00
78.00
5,350.00
133.00
3.04
2.67
0.54
4.32
0.43
0.25
0.20
6.09
0.15
3.09
3.78
1.06
6.47
20.70
52.70
65.40
25.80
14,362.00
80.14
5.79
1.84
16.03
25.85
31.70
^Adapted from the work of Rucn et al. (1974)
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Synthetic pipeline gas, which is indistinguishable from natural gas and con-
tains over 90 percent CH^, is produced by further processing of intermediate-
Btu gas. The required processing includes removal of particulate matter and
condensables, adjustment of the gas composition by converting some of the CO
to H2 and C02 (shift conversion), removal of H2S and C02, and methanation of
the resulting gas mixture.
The pyrolysis or devolatilization of coal to char and volatile matter occurs
during coal heating.
1. Coal + heat — >- C + volatile hydrocarbons
The gasification of char with C02,
2. C + C02 — > 2 CO
and the water-gas shift or hydrogasification reaction
3. C + H20 — > CO + H2
are the heart of the gasification reaction and supply the synthesis gas. The
hydrogasification reaction and the gasification of char with C02
4. C + C02 — ^2 CO
are slow and are thermodynamically favored at temperatures above 1350°F (732°C),
but are rarely at equilibrium at temperatures below 2000°F (1093°C). Heat for
this reaction is supplied by the combustion reactions
5. C + |02 — >- CO
6. C + 02 — >• C02
7. H + £ 02 — >• H20
which are very rapid and proceed to completion with oxygen disappearance. The
methanation of char
8. C + 2 H
2
is highly exothermic and is thermodynamically favored at high pressure or at
temperatures less than 1150°F (621 °C). The shift reaction
9. CO + H20 — > C02 + H2
is mildly exothermic and because it has a favorable equilibrium at temperatures
below 1350°F (732°C), it is usually carried out externally to the reactor. The
methanation reaction
10. CO + 3 H2 — j- CHij
is highly exothermic but is favored at low temperatures and elevated pressures.
This reaction, necessary to the production of pipeline quality gas, is gener-
ally catalytically augmented and is carried out externally to the reactor.
7
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Because any incremental increase in methane production (reactions 8 and 10) in
the gasifier favors the economics of pipeline gas production, most high-Btu
gasification processes are high-pressure processes. For the same reason,
several of the advanced or second generation coal gasification processes
(processes not already commercialized) utilize a hydrogen gas feed to augment
or replace that produced by the water-gas shift reaction. Alternately, methane
content is not of economical significance in low-Btu coal gasification and
these processes tend to favor low pressure.
Coal Gasification Research Facilities
Coal gasification research facilities include low- and medium- as well as
high-Btu gasification processes. From a number of coal gasification projects
currently planned or under way (Table 2), seven were chosen (Table 3) from
which to generalize about all such plants. Each is currently investigating a
unique feature of the gasification process, as illustrated in the following
list of plants chosen and their special focuses:
HYGAS — Two-stage hydrogasification plus one-stage
standard gasification utilizing counter-
current flow of solids and gas
C02 Acceptor — Utilization of chemical reaction between CaO
and C02 to supply process heat and to drive
the gasification reaction to high hydrogen
production rates with lignite
Synthane — Utilization of any coal for the production
of natural gas via simplified pretreatment
plus fluid-bed gasification
Bi-Gas — Utilization of medium-temperature dilute-phase
gasification followed by high-temperature
combustion to produce a synthetic natural gas
from any coal
MERC — Demonstration of the direct use of fixed-bed
processes with fine and/or agglomerating coals
Agglomerating — Production of high-Btu gas from caking coals
Burner with air by using agglomerated ash as a heat
transfer mechanism
Steam-Iron — Production of hydrogen from coal char
utilizing the oxidation of iron powder and
reduction of iron oxide
The seventh process described above utilizes char, rather than coal, as its
feed material to produce hydrogen for hydrogasification or hydro!iquefaction
processes, including HYGAS, Hydrane, Solvent Refined Coal, and H-Coal. As
such, the Steam-Iron process may be an integral part of the gasification
process and was chosen for study as an example of processes that might
utilize char in noncombustion processes.
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Table 2. Second generation coal gasification processes under consideration.
Developer
Westinghouse"
BiH"
Exxon"
Combustion
Engineering"
Grand Forks
Energy Research
Center0
IGT*
General
Electric"
ERDA"
M. M. Kellogg
Company"
FMCa
AM Squires ,
CUNY
University
of Wyoming
Foster Wheeler"
Sys tern
Combined
Cycle
Entrained
bed
Catalytic
gasification
Entrainment
gasification
Slagging Lurgi
U-Gas
GE-Gas
Hydrane
Molten salt
Cogas
Circulating
bed
Multiple
catalyst
Entrained
feed
(Nuclear „
process heat)
Feed
Size
1/4" x 0
1/4" x 0
1/4" x 0
1/4" x 0
Lump
1/4" x 0
ND
Crushed
-12 mesh
ND
Crushed
ND
ND
ND
Requirement
Coal Restrictions
Dried
ND^
ND
ND
Dried
Noncaking or pre-
treated caking (?)
Noncaking or
mildly caking
No pretreatment of
bituminous coal
necessary
None
Sub-bituminous
and bituminous
ND
ND
ND
Dried
Type of Process
Reactor
Fluidized bed surrounding
central draft tube (feed)
atop combustor
Pressurized, water-cooled
gasifier
Fluidized bed
Slagging, fixed bed
Slagging, entrained bed
Fluidized bed
Moving fixed bed
2- zone hydrogen
Molten Na2C03
Fluidized bed
High velocity
(10-40 ft/sec)
Heated Ni catalyst
Entrained- type, 2 stage
slagging pressure gasifier
Heated He from nuclear
plant provides heat for
coal hydrogasi fication
Feed
Steam, air
Air
Steam, air
Steam, air
Steam, 02
Steam, air
or Steam, 02
ND
Steam, 02
Steam, air
Steam, air
Steam, air
or 02
Steam
Steam, air
ND
Operating
Pressure, psi
200
50-100
Atmos-1000
Atmospheric
80-400
Atmos-350
Atmos-250
1000
420
50
ND
1000
520
560-1400
Operating
Temperature, °F
2100
Gasifier: 900
Combustor: 1600
at 95 psi
Gasifier: 1400-1500
Char heater: 1700+
Combustor: 3000-3200
Reductor: 3000-1780
250-2800
1900
250-1600
1650
1830
1000
2200-2300
1200-1300
2100+
1550-1630
Stage
Development
Pilot
Pilot
ND
Pilot
PDI/
PDU^
PDUrf
Bench
Bench
Pilot
Bench
(at HRI)
Bench
ND
Paper
?Adapted from the work of Howard-Smith and Uerner (1976).
No data.
^Adapted from the work of Ellman and Johnson (1976).
^Process development unit.
Adapted from the work of Squires (1976).
Adapted from the work of Schrader et al. (1975).
-------
Table 3. Coal gasification systems used as references.
Process
HYGAS, Steam-Oxygen
C02 Acceptor
MERC Unit
Synthane
Bi-Gas
Agglomerating Burner
Steam- Iron
Pressure, psig
1000<3
1000-15000
150°
150-30QC
200a
Atmos-300°
1000a
600-1000°
Upper stage (entrained flow)
1000-1500
Lower stage (vortex flow)
1000-1500
Atmos-100
1000-1200
Temperature, °F
1300-1900
1500-1850^
Combustion zone
2400-2500
Gas off take
1000-1200
1500°
1400-1800°
1400-1700
2800
1800
Hydrogasifier
1300-1700
Producer
2000-3000
Product
Gas Quality Liquids
Medium or high Light oil
and tar
Medium or high None
Low, medium, or Light oil
high and tar
Medium or high6 Light oil
and tar
Medium or high6 (Doubtful)
Medium or high (Questionable)
Hydrogen None
Coal Feed
Lignite
Sub-bituminous
Bituminous^
Lignite
Sub-bituminous
Lignite
Sub-bituminous
Bituminous
Lignite
Sub-bituminous
Bituminous*
Lignite
Sub-bituminous
Bituminous
Lignite
Sub-bituminous
Bituminous^1
Char
Status
(Dec. 1976)
Operational
Operational
Operational
Start-up
Start-up
Start-up
Under
construction
Type
Pilot
Pilot
Pilot
Pilot
Pilot
PDU
Pilot
"Normal operating pressure.
"Must pretreat agglomerating bituminous coal.
mal range.
bed 1500°F, regenerator 1840°F.
be converted to low-Btu gas production.
-------
In addition to the unique feature of each gasification process, each pilot
plant is also a test bed for process equipment such as pumps, valves, insula-
tion, repair techniques, and metallurgy, and for downstream techniques such as
quenching, acid gas scrubbing, methanation, and sulfur removal. Despite the
differences introduced by this variety of research goals, the unit operations
of most pilot plants are quite similar (Table 4). The same is true of their
operating and maintenance techniques. Further, the primary process streams,
while differing in quality, are sufficiently similar in their major constitu-
ents (Table 5) that generalization about major properties for the purpose of
this document will not produce major discrepancies. However, generalization
about minor constituents in the process streams is most difficult since the
exact constitution of the process streams is not yet known in detail (Magee
et al. 1973), and concentrations of minor constituents change depending upon
reactor configuration, residence time, reaction temperature or reaction-
temperature sequence, pressure, and coal feed (Braunstein 1976). This second
point must be emphasized: The composition of the "oil" and tar products from
any given reactor may be unique to that process. One example is the differ-
ence between the condensable oils found in the off-gas from HYGAS and the
expected condensable oils in the Synthane off-gas. Oil from HYGAS is 85%
toluene, 8% benzene, and 3% Cg aromatic hydrocarbons (Lee 1975). In contrast,
based on laboratory data, little minus ]00°C oil (benzene) is anticipated
from Synthane (oral communication December 9, 1976, by A. J. Forney, Pittsburgh
Energy Research Center, Bruceton, Pennsylvania) and 30% to 60% of the oil
product is expected to have a boiling point in excess of 500°C (932°F) (Forney
et al. 1974). Unlike liquefaction or pyrolysis processes (coking), gasification
processes provide — through the carbon-steam reaction — atmospheres contain-
ing relatively large quantities of hydrogen, so that gasification products are
not necessarily the same as liquefaction or pyrolysis products. The fact that
some compounds are formed commonly by all three reactions (gasification,
pyrolysis, liquefaction) does not give one license to assume that all sub-
stances found in one operation will be found in all operations. As the data
indicate, the range of known second generation gasification products is limited.
Known plus suspected gasification products are shown in Appendix A.
The Synthane Pilot Plant (Figure 2) has been chosen for the generalized process
description which follows. This process was chosen because of its relative
simplicity, because it contains more points of similarity to the gasification
pilot plants referred to here than any other process, and because of the variety
of products anticipated from this plant. Information from or pertaining to
the remaining six processes will be used to illustrate, or be presented as,
special cases.
SOLIDS HANDLING
Coal Storage
The coal or char storage piles in coal gasification pilot plants tend to be
relatively small, varying from no storage to several railroad carloads. Coal
is either taken from the storage piles with a front-end loader (e.g., at the
HYGAS and Agglomerating Burner plants) or unloaded from a truck or railroad car
to an underground storage bin. From this bin, it is transported by conveyor
belt to a closed tank (e.g., at the C02 Acceptor, Bi-Gas, and Synthane plants).
11
-------
Table 4. A synopsis of unit operations at seven coal gasification research facilities.
Unit Operation
Coal stock pile
Coal feed
Coal preparation
Ground coal storage
Gasifier feed
Pretreatment
Gasification
Gas quench
Gas scrubbing
Shift
Acid gas scrub
Methanation
Gas product disposal
Sulfur
Water
Condensable hydrocarbons
Ash or Char
Overhead coal or char
HYGAS
Yes
Payloader-bin-
conveyor
Williams mill
(negative pres-
sure) water scrub
Purged bin
Toluene slurry
Low pressure
Countercurrent
flow through
fluid beds
Quench towers
Water
No
Diglycolamine
Ni catalyst
cold gas recycle
Thermal oxidation
Claus
Filter, city
sewage disposal
Recycle
Filtered and
disposed
Filtered and
disposed
C02 Acceptor
Stored off site
Truck-bi n-conveyor
Williams mill
(positive pres-
sure) water scrub
Purged bin
Simple lockhopper
No
Dolomite plus char
fluid beds
Water venturi
Water
No
Hot carbonate
Packed tube
reactor
Thermal oxidation
Thermal oxidation
Hay filter, city
sewage disposal
None
Dredged from pond
Sent to pond to settle
for later disposal
MERC Unit
Yes
Truck-bin-
conveyor
Run of mine
steam dry
Bin
Simple lockhopper
No
Stirred fixed
bed
Cyclone separator
No
No
No
No
Thermal oxidation
Thermal oxidation
Thermal oxidation
Thermal oxidation
Disposal
Thermal oxidation
Synthane
Stored off site
Truck or rail road-
bin-conveyor
Dryer, Raymond
mill , screen
Purged bin
Petrocarb lockhopper
High pressure
Single fluid bed
Water-venturi
Water, then oil
Fixed bed
Benfield
Tube-wall reactor
(Raney Ni)
Thermal oxidation
Stretford
Thermal oxidation
Thermal oxidation
Filtered and disposed
Thermal oxidation
Bi-Gas
Yes — compacted
Truck or rail-
road-bin conveyor
Cage mill
wet ball mill
Purged bin
Water slurry
steam-injected
No
Hedium-and high-
temperature en-
trained beds
Water-venturi
Water
Fixed bed
Selexol
Fluidized bed
to fixed bed
Thermal oxidation
Claus
Filter, city
sewage disposal
Tar generation
not expected
Slag from lower
stage is water-
quenched
Pond for later
disposal
Agglomerating Burner
Yes
Pay loader-bin- screen
to -35 mesh
Williams mill
Purged bin
Lockhopper
Low pressure, if
requi red
Agglomerated ash
supplies gasification
heat to fluid bed
Water-venturi
No
No
No
No
Thermal oxidation
Thermal oxidation
Thermal oxidation
Thermal oxidation
Landfill
Thermal oxidation
-------
Table 5. Gasifler products.
Co
Product HYGASajfc
Coal Feed Rate (Ib/hr) 6000
Gasifier Overhead Products (vol %)
Carbon Dioxide 4.8
Carbon Monoxide 9.7
Hydrogen 33.1
Methane 19.0
Ethane ND
Water 31.8
Nitrogen 0.4
Ammonia ND
Oil and Tar 0.6
Hydrogen Sulfide 0.6
Solids (char or coal) 5%-10% coal feed
"Adapted from the work of IGT (1973).
Adapted from the work of Anastasia and Blair (1975).
^Adapted from the work of Stearns-Roger (1976b).
Adapted from the work of Lewis et al . (1975).
^Adapted from the work of Haynes and Forney (1972).
^Adapted from the work of Grace and Diehl (1974).
fAdapted from the work of Grace (1972).
.Adapted from the work of Battelle Columbus Laboratories
.Adapted from the work of Detman (1976).
JHo data.
*Does not include slurry oils.
C02 Acceptor0
2730
6.6
8.7
38.8
9.0
ND
34.7
2.2
ND
0.0
0.05
105 Ib/hr
(1974).
MERC Unitd
2250
9.6
16.6
16.9
2.4
0.2
8.3
45.5
ND
ND
0.5
2%-4% coal feed
Syn thane6
2000-6000
18.3
7.9
12.3
11.9
0.4
46.8
0.9
0.7
0.4
0.4
53S-102; coal
Bi-Gas^
10,000
16.2
22.1
24.2
11.8
ND
24.6
0.5
ND
ND
0.6
feed ND
Agglomerating Burner
1225
5.6
27.0
49.7
ND
ND
17.0
0.3
ND
ND
0.4
5X-10% coal feed
Steam- Iron
NET7'
0.0
0.0
26.0
0.0
0.0
73.4
0.6
0.0
0.0
0.0
ND
-------
CYCLONE
SEPARATOR
BUCKET ELEVATOR
30 TPH
TAR TO THERMAL
OXIDIZER
FEED CONVEYOR"^
30 TPH
FINAL
METHANATOR
SYNTHETIC
PIPELINE GAS
950 BTU/CF
890 PSIG
KP. CO, STORAGE
TANK
CO2 COMPRESSOR
CO2 COMPRESSION
Figure 2. Synthane coal gasification pilot plant.
14
-------
Problems--
There are three types of health and safety problems associated with this
initial coal storage and transportation sequence: dusting, fire, and leach-
ing.
Dusting—The greatest amount of dust will be generated when a truck or rail-
road car is unloaded. (If the coal is unloaded into a bin [C02 Acceptor] and
the bin is enclosed on three sides, as is done at many coal mines, spread of
the dust into the surrounding area will be reduced.) Coal dust can and will
blow off of a storage pile or conveyor. Coal will also be scattered and
crushed when a front-end loader is used to convey coal from a concrete pad to
a bin (HYGAS, Agglomerating Burner). There are no means of alleviating this
problem. In passing from the receiving bin to the storage bin, coal is fed
into a moving belt with a vibrating conveyor, then passed under a magnet
which removes scrap iron, and finally to a bucket elevator. At each transfer
point the coal can and will produce more dust.
Observation of existing coal gasification pilot plants both during operation
and when shut down has indicated that coal pile and conveyor dusting should
normally be only a nuisance to plant operators and a housekeeping problem.
In general, gasification workers do not appear to be at risk from coal dust.
The possible exceptions are those personnel assigned to unloading, front-end
loader operation, or cleanup (all of these jobs are intermittent).
Fire--Coal will ignite spontaneously under at least two conditions:
1) Lignite or sub-bituminous coals will ignite when dried and exposed to air
at ambient conditions. Resultant fires tend to be on the surface.
2) High-sulfur bituminous coals, especially coals containing fines, will
ignite after excessive exposure to normal weather. Such fires are not
uncommon after 2 to 6 months of exposure. Fires in these coals tend
to be submerged in the piles. Small piles of "fine" high-sulfur
bituminous coal dust, such as might accumulate from dusting or equipment
leakage, may ignite within 12 to 48 hours, according to M. A. Evans (oral
communication December 2, 1976, 620 N. Franklin Street, Somerset, Pa.).
Fires in the small coal storage piles normally found at pilot plants should
pose few or no safety problems because of the size of the piles and the
relative frequency of inventory turnover. (This is especially true where
good housekeeping practices are followed.) However, the hazardous gases,
vapors, and particulates from such a fire would be similar to those found in
coke oven emissions or in other destructive distillation processes.
Leaching--Coal exposed to rain will be subjected to leaching by the water.
Water will also carry coal fines into the plant sewer system, and in many
cases this water may go into the plant water treatment pond.
Currently very little is known about the effect of residence time, weather,
pile size, and coal composition of the leachate from coal storage piles.
Several long-term (5-year) studies are being considered by both the Bureau
of Mines and the Illinois State Geological Survey (oral communication,
15
-------
February 1976, with H. J. Gloskoter, Illinois State Geological Survey, Urbana,
Illinois). One piece of information that has recently become available is
presented in Table 6, which does indicate that a number of objectionable
compounds can be dissolved. Even this limited information indicates that the
concentration of dissolved materials in the leachate varies widely. Un-
fortunately, the table includes no data on either coal composition or other
factors mentioned.
Coal Preparation
The raw coal from storage must be properly sized and dried before it is fed
to the gasifier system (Figure 3). The coal is passed through a presizing
crushing operation (a hamrnermill is generally used) to eliminate large lumps.
The coal is then fed directly to a mill., where it is crushed and dried simul-
taneously. (Williams mills are used at C02 Acceptor [positive pressure],
HYGAS [negative pressure], and Agglomerating Burner plants; a ball mill is
used at the Bi-Gas plant; and a Raymond mill is used at the Synthane plant.)
A mixture of hot flue gas from an auxiliary furnace and recycle gas is also
piped into the mill at such a quantity and velocity that the ground coal is
conveyed pneumatically to a cyclone located at the top of the structure,
and the coal is simultaneously dried. Gas temperatures at the cyclone vary
from 175° to 350°F (79° to 177°C) depending upon the rank of the coal being
ground. Gas composition includes only minimal quantities of oxygen (which
are defined by rank of coal being ground, fineness of grind, drying gas
temperature, and mill system being used). The C02 Acceptor plant limits oxy-
gen concentration to 3 to 5 vol % while other units grinding Eastern bitumi-
nous coal to -14 mesh and drying it at 180°F (82°C) find that 15 vol % oxygen
is below the explosive limit. (Mill systems are generally equipped with
oxygen monitors, auxiliary inert gas feed systems, and blowout hatches.)
VENT TO ATMGS. -
CYCLONE
SEPARATOR
BUCKET ELEVATOR
30 TPH
_ DRYING
I SYSTEM FAN
' r
TO PULVERIZED COAL
STORAGE BIN
RAW COAL SUPPLY
BY TRUCK
V4" X 0 MESH
FEEDER HOPPER
IZJ TONS
FEED CONVEYOR \
30 TPH N
3LOWER
PULVERIZER
AND DRYER
5 TPH
Flgun 3. Synthan* coil gasification process (coal preparation).
16
-------
Table 6. Analyses of drainage from two Industrial coal piles.
Constituents
Acidity (total), as CaC03
Calcium
Chemical oxygen demand
Chloride
Conductance, mho/cm
Dissolved solids (total)
Hardness, as CaC03
Magnesium
pH, unit
Potassium
Silicon (dissolved)
Sodium
Sulfate
Suspended solids (total)
Turbidity, JTU
Aluminum
Arsenic
Barium
Beryllium
Cadmium
Chromium
Copper
Iron
Lead
Manganese
Mercury
Nickel
Selenium
Titanium
Zinc
Concentration,
Plant J
1,700
240
9
0
2,400
3,200
600
1.2
2.9
ND
91
ND
2,600
550
300
190
0.01
ND
ND
<0.001
<0.005
0.56
510
<0.01
27
<0.0002
1.7
0.03
<1
3.7
mg/liter
Plant L
270
350
NDfc
ND
2,100
1,500
980
0.023
2.9
0.5
ND
4.1
ND
810
ND
ND
0.009
0.1
<0.01
<0.006
<0.005
0.18
830
0.023
no
0.027
0.32
0.003
ND
1.0
the work of Chu et al. (1976).
No data.
17
-------
Coal from the cyclone passes over a vibrating screen that returns oversize
material to the mill, while undersize material is conveyed by gravity or
screw conveyor to a fine-coal bin. The fine-coal bin is airtight and it is
purged with inert gas to prevent fires, explosions, and moisture pickup by
the coal.
The fine coal is removed from the cyclone discharge gasj a portion of the
gas is recycled to the furnace; and a smaller portion of the gas is purged
from the system to the atmosphere to reduce the gas moisture content. Both
the baghouse system and the venturi water scrubbing system have been used
to remove the fine coal from the cyclone discharge gas. The venturi has
become the more popular for pilot plant operation because of the number of
problems encountered with the baghouse. Either system can produce a discharge
gas of acceptable quality. Fines from the baghouse are discharged to the
fine-coal bin. Fines accumulated in the circulating water of the venturi
scrubber are discharged to the dirty water pond at a concentration of
approximately 5 wt % solids.
Problems--
In coal crushing sections of the plant, there tend to be two types of
problems, other than those already discussed.
Dusting—Dusting may present an inhalation hazard with the potential for pre-
cipitating pneumoconiosis. (Casarett and Doull [1975] linked respirable coal
dust to pneumoconiosis [black lung]). Dusting is also a safety hazard; both from
the very real potential for dust explosion, which increases with decreasing
coal rank, and as a fire hazard under the conditions already described.
Dusting from any equipment is possible, particularly if the equipment has to
be maintained often and is not properly reassembled. (Elevators, rotating
valves [star valves], augers or conveyors, and vibrating screens are common
points of rapid wear and failure.)
Dusting during plant operation is, in general, not a major problem, provided
that good housekeeping and maintenance procedures are consistently followed.
Dusting can be a major problem when equipment or bins must be maintained or
emptied inasmuch as pilot plants may not have facilities for the removal of
coal from bins. This can be a very dusty and dirty procedure. (Fortunately,
it is not often necessary.)
Noise—All grinding operations are inherently noisy. Screening operations
are also noisy, although vibrating screens in most pilot plants are located
away from normal traffic.
Special Cases—Two of the pilot plants use other feed solids in addition to
coal. The C02 Acceptor operation crushes and screens dolomite or limestone
to a 6 by 8 mesh particle size, while the Bi-Gas plant is prepared to add
finely crushed silica or limestone to the feed to alter the coal ash slagging
properties as required. In either case, the problems are similar to those
encountered with coal, except that fires and explosions would not be
anticipated.
18
-------
At the Bi-Gas plant, coal is fed into a cage mill for initial grinding. Upon
demand, the cage mill product is mixed with water and final pulverization is
accomplished in a wet ball mill. The ball mill product is sent to a weigh
tank (Grace and Diehl 1974).
Coal Feeding
Coal is fed from the pulverized coal storage bin through a lockhopper system
to the gasifier. The Synthane Pilot Plant uses a Petrocarb lockhopper system
(Figure 4), which operates as follows: Pulverized coal flows from the coal
storage bin through two low-pressure valves to a weigh-hopper. When the
0.85-ton weigh-hopper is filled, a low-pressure diversion valve is opened
below the weigh-hopper and two high-pressure valves above the storage injector
are opened. The 0.85-ton storage injector is filled and all valves are
closed. The injector is pressurized with inert gas (C02) to 1065 psig. Two
high-pressure valves below the storage injector are opened to the 5-ton
primary injector and the coal flows by gravity into it. All valves are then
closed. The inert gas from the storage injector is bled to the thermal
oxidizer. The sequence is then repeated. The storage injector system is
duplicated so that while one injector is filling, the other is discharging.
The Synthane lockhopper system is the most sophisticated such system in
operation at any pilot plant at this time. Others have less elaborate valving
(single rather than double) and are more directly connected to the reactor
(e.g., MERC, C02 Acceptor).
CUSTOMERS STORAGE
COZ
TO- PRETREAT
Figure 4. Pitrocart locfchoppar sysUm (Synthane Pilot Plant)
"Pttrocirb, Inc.. (1975).
19
-------
Problems--
The one primary problem in this area is lockhopper valves; a problem of
lesser importance involves the cleaning and maintenance of these valves and
vessels.
Lockhopper valves are subject to extraordinary abuse. They must hold a
differential pressure of from several hundred to 1000 psig. At the same time,
they must pass large quantities of solids rapidly and thus must be relatively
large. Fine solids may adhere to the valve seating surfaces and invariably
either the valve surface is abraded, or the valve cannot be closed against
the solids. In either case, process gas may escape to the low-pressure
portion of the system and then to the atmosphere. The composition of this
escaping gas depends upon two factors:
• The proximity of the lockhopper to the reactor
• The reactor feed point (i.e., above the bed, into the bed, or at
the bottom of the bed)
In the worst case, it may be assumed that the escaping gas will have the same
composition as that of the off-gas from the reactor. The degree of serious-
ness obviously varies with the total system utilized. For example, in the
Synthane plant, coal is carried pneumatically with steam to the pretreater.
A leak in the Petrocarb valving system would consist of C02 or steam. The
lockhopper system for the MERC unit is directly connected to the top of the
fixed-bed reactor through a two-valve system. Leaking gas from the lock-
hoppers would contain reactor gasification products.
Should the valves leak process gas to the atmosphere, it is certain that
portions of the hydrocarbon vapors contained in the gas would condense on the
cold interior surfaces of the valves. They would also condense on interior
vessel surfaces and on any feed coal in any of the vessels or piping through
which they might pass. Hydrocarbon condensate would also be deposited around
the exterior surfaces at the leak point and on any nearby structures, depend-
ing upon the size of the leak.
Special Cases--
Two of the pilot plants, HYGAS and Bi-Gas, utilize slurry feed systems. At
the HYGAS plant, coal from the fine-coal storage bin is fed continuously into
a slurry-mix weigh tank, which has been filled with light oil (^ 86% toluene).
The slurry is mixed both by a turbine blade mixer and by circulation from the
bottom of the tank through a centrifugal pump to the top of the tank. When a
run is started, circulation is diverted through a high-pressure piston pump
(spared*). Excess slurry is recirculated to the mix tank. From the piston
pump, the pressurized slurry flows at a velocity of approximately 6 ft/sec
through a heater (temp = 300°F or 149°C) and then into the reactor.
*A duplicate pump and valving system is installed in parallel so that either
pump can be used. Should one pump malfunction, flow can be switched to the
spare pump and the malfunctioning pump can be repaired.
20
-------
The feed arrangement at the Bi-Gas plant is roughly similar, although water
is used as the liquid carrier. Here the slurry from the piston pump passes
through a preheater, where the water is flashed to steam. The coal is then
transported pneumatically to a cyclone and into the gasifier.
A major problem with using a slurry feed system is one of housekeeping (leak-
ing equipment). In the HYGAS Pilot Plant system, there is also the possi-
bility of light hydrocarbon vapors' leaking from the slurry system. Pump
problems are not uncommon, nor are plugged lines, especially during initial
plant start-up.
Pretreatment
Background—
Many of the Eastern bituminous coals swell and melt as they are heated through
the 400° to 800°F (204° to 427°C) range. As the particles melt, they adhere
to one another. As the temperature is maintained or raised, the volatile
constituents vaporize while the higher molecular weight liquids crack into
light or vaporizable material and into unstable molecules that polymerize and
"coke." This coking or agglomerating phenomenon is highly desirable for the
making of coke but is undesirable in coal gasification, because, if coal
agglomeration occurs in a fluid-bed gasifier, the fluid properties of the bed
are destroyed, while in a fixed-bed gasifier an agglomerated bed would block
the flow of air or oxygen through the bed.
The agglomerating properties of coal can be destroyed if the coal particles
are exposed to a limited quantity of oxygen at approximately 800°F (427°C).
Apparently, a thin layer of coal on the exterior of the particles combines
with the oxygen, forming a surface film, which prevents particle agglomeration.
During the pretreatment process, some off-gas is produced as indicated in
Table 7. No data are available concerning the concentrations of sulfurous
or nitrogenous gases from pretreatment or the exact analysis of the hydro-
carbon vapors. Hydrocarbon vapor may be high in light oils content, but it
will include a complete range of materials with boiling points up to the pre-
treating temperature (normally, 750° to 825°F [400° to 440°C]).
Operation—
In the Synthane process (see earlier section of this chapter on coal feeding),
coal is metered out of the primary injector through a rotating valve to fall
into a pickup pot. High-pressure steam from the utility section (^ 1100 psi,
556°F [291°C]) then transports the coal pneumatically to the pretreater. The
transport line is electrically heated to initiate coal heat-up. Oxygen can
also be supplied to the transport line to initiate pretreatment, if this is
desirable.
It may be assumed that although the feed line is heated, the solids velocity
will be sufficiently high to prevent pretreatment temperatures from being
altered and that no pretreatment off-gases or hydrocarbon vapors are produced
up to the pretreater feed inlet. Sufficient oxygen is added to the pretreater
fluidizing gas to maintain the temperature at ^ 800°F (427°C). Because of
the circulation that exists in a fluid bed (discussed later in this chapter),
it is again reasonable to assume that at least a portion of the pretreater
off-gas, however diluted, exists at any given point within the pretreater.
Both pretreater off-gases and pretreated coal are carried through the over-
flow pipe to the reactor.
21
-------
Table 7. Coal pretreatment yields.
Test Number
Coal
Pressure, psi
Temperature, °F (°C)
Maximum
Average
Residence Time, Min.
Pretreating gas: coal ,
wt ratio
02, vol, % pretreating
gas
Steam : coal , wt ratio
Gas Yield
scf/ton MAFG coal
wt % of coal feed
Btu/lb coal
Gas Analysis, vol %
H2
CO
CO 2
CH4
C2H6
S02
Tar Recovered, Ib/ton
Wt % Coal Feed
F.B.P. 7a
Pittsburgh
1029
842 (450)
798 (426)
3
1.07
7
0
1000
5.1
109.5
2.1
8.4
72.0
16.5
1.0
ND
20
1.0
F.B.I. 8a
Illinois #6
1029
878 (470)
860 (460)
3
1.01
7
0
1140
5.1
81.6
2.8
8.4
79.0
8.8
1.0
ND
42
2.1
Process Flow
Diagram^
Bituminous
Atmospheric
ND
^800 (427)
^30
0.76
21
0.47
3416
15.3
ND
ND
44.4
34.4
-i -1 r- "I
}15.1
6.1
16.4
0.8
,From the work of Gas ior et al. (1976).
From the work of Institute of Gas Technology (1973).
^oisture-ash-free.
a*
'02,N2,H20 free basis.
-------
Special Cases—
In other pilot plants (HYGAS [Figure 5], Agglomerating Burner), pretreatment
is carried out at essentially atmospheric pressure. The pretreatment
mechanism is similar to that already described, except that raw coal may be
fed with a screw conveyor directly to the pretreater fluid bed. The pre-
treated solids are removed from the bed by a fixed-point offtake or stand-
pipe and, in general, are cooled before transfer to a holding bin. From
here they are introduced into the gasifier feed system. The pretreater
off-gases pass through a cyclone and are then scrubbed with a circulating
water venturi scrubber. (This scrubber is similar to the gasifier off-gas
scrubber described in detail later). The scrubbed gas is fed to the thermal
oxidizer.
PBETREATEFt
TO
INCINERATOR
COOUNG
WATER
CHAR TO
HYOROSASIFIER
IMjurt 5. Co«l pr»tr»iOntnt stction, HTGAS «Urt-up
IiwtttuU of Sn Ttchnology (1975).
Problems--
It is important to note that any part of the pretreater or of the pretreater
off-gas system may contain condensed aromatic hydrocarbon vapors. It is
equally possible that the pretreated coal may contain condensed heavy tars.
(At ambient .temperatures, any such tars on or in the pretreated coal would be
solids.) It is also possible that pretreater tars* contain compounds with
kFor the purpose of this document "tar" means condensable aromatic hydro-
carbons.
23
-------
boiling points in excess of the pretreater temperature of 800°F (420°C).
These compounds would have melted at the pretreater temperatures and would
therefore have exerted sufficient vapor pressure to be exhausted from the
pretreater with the product gas.
GASIFIER
General
The gasifier is the heart of the coal gasification pilot plant operation.
The pilot plant exists to study the process operating variables within this
vessel. The gasifier may be 130 feet high and up to 5 feet in diameter. It
may be built to operate at pressures below 100 psi (MERC, Agglomerating
Burner) or at pressures of up to 1500 psi (Bi-Gas). It may be constructed to
maintain temperatures which may vary from 1400°F to ^ 3000°F (760°C to
•^ 1650°C). Further, the vessel is connected to other vessels by a number of
major and minor lines and it incorporates a number of ports and hatches for
use as inspection ports or for alternative connections for lines or instru-
iK < ITS ,
Six of the seven reactors under study either are fluid-bed units or have the
fluid-bed characteristics. Only the MERC stirred reactor is a fixed-bed
unit. The reactor vessel may contain one fluid bed (Synthane [Figure 6]),
multiple fluid beds (HYGAS [Figure 7], Steam-Iron), or an entrained bed
(Bi-Gas); or it may consist of several fluid beds in separate vessels
(C02 Acceptor, Agglomerating Burner).
COAL
FEED
SASIFIER
J PRETREATER 3_JPH OFF-3AS TO
"* VENTum SC1JUB8ER
H.P.
STEAU,
OXYISEN
0
HYOROGASIFI6H
EFFLUENT
STEAU VENT
TO 4TMQS.
f
PREHEATED
E2.AL RECYCLE
BENZENE
HYDROGEN
AND STEAM
CHAR SLURRY
QUENCH TANK
Flgwn 6. Pr«tr*at«r and gulfltr —
Wlot PI int.
f1gur« 7. Hydrogaslflcatlon reactor,
start-up configuration —
HYGAS Pilot Plant.
Vfram: Schora (1975)
24
-------
Two-Phase Fluidization--
As fluidization is a unit operation of major importance to most of the second
generation coal gasification concepts, it will be defined in detail.
A fluidized bed consists of solids, which may be as large as 2h inches or as
small as 1 micron, although a bed of particles in the size range of 208 microns
(65 mesh) to 12 microns is best for smooth operation. To fluidize these
solids, gas is injected into the bottom of the bed in such a manner as to be
evenly distributed over the bottom of the bed. When gas flow is initiated to
the bed, the gas pressure increases until it equals the sum of the weight of
the bed per unit of cross-sectional area plus the friction of the bed against
the walls. When this point is reached the bed expands and the solids assume a
more open arrangement, so that the gas can flow without exceeding the unit-bed
weight. With further increases in gas velocity, the pores and channels enlarge
and the particles become more widely separated. For free-flowing materials,
the pore spaces eventually become so large that no stable arrangement can
exist, and the particles will vibrate or circulate locally in a semistable
arrangement; this is the point at which fluidization begins, forming the
quiescent or incipient fluidized bed. Another increment of gas velocity re-
sults in overall circulation of the bed, often with transient gas streams
flowing upward in channels that contain relatively few particles, with clumps
or particles flowing downward (Perry et al. 1963). It is at this latter point
that solids are carried from the dense phase (i.e., fluid bed) into the lean
phase (disengaging space) of the reactor. While the heavier of these parti-
cles fall back into the bed relatively quickly, many are carried to the top of
the reactor, where a cyclone is usually located. The cyclone will separate up
to 99% of the particles from the gas entering it and will return them deep
into the bed via the cyclone dipleg.
Advantages--
Fluid-bed processing offers several advantages over other modes of processing,
such as fixed-bed. Fluidized beds are particularly adaptable to the contact-
ing of free-flowing, nonsticky, granular solids with gases. Other advantages
of fluid-bed systems include the following:
t Temperature Control
1) Turbulence within the fluidized mass breaks up and disperses any
hot or cold spots.
2) High heat capacity of the bed stabilizes the temperature, permitting
the bed to absorb large heat surges in the fluid with relatively
small bed temperature changes.
3) High heat-transfer rates are due to the large amount of transfer
surface per unit volume of the bed. (The surface volume of
ordinary sand would be 1000 to E300 square feet/cubic foot of bed.)
• Continuity of Operation
1) The high degree of internal turbulence and mixing assures rapid
dispersal of fresh solids added to the bed.
25
-------
2) Fluidized solids can easily be transported from vessel to vessel, and
can be circulated in various paths at various densities and residence
times through any network of processing equipment,
0 Heat Transfer
1) The fluid-bed offers the possibility of combining heat transfer with
other operations.
2) For large heat-transfer unfts, the fluid-bed equipment can be smaller
than conventional heat-transfer equipment.
3) Through the use of ceramic materials for interior wall construction,
both corrosion and extreme temperature resistance can be easily
obtained.
4) Heat transfer can be effected in multiple stages, the fluidized solid
acting as the heat reservoir to carry heat from one fluid to another;
the stages may be physically close together.
5) Heat transfer can be effected with extreme rapidity because of the
large surface available — often with the ability to negate the un-
favorable reactions that would occur at more leisurely heat-up rates.
6) Similarly, a liquid may be heated, vaporized, and dispersed in a
fraction of a second by direct contact with hot fluidized solids.
• Catalysis or Other Operations
1) Easy control of bed or reaction temperature
2) Maintenance of uniform catalyst activity
3) Continuous removal of solid by-products
4) Supply of heat to endothermic reactions
5) Simple equipment with few moving parts
6) Continuous operation with automatic controls
7) Adaptability to sulfur scavenging via dolomite addition
Disadvantages—
Fluidized-bed systems also have disadvantages:
§ Sticky or agglomerating solids cannot be processed.
• Fine solid particles may be formed, either trapped within the process
or entrained in the gas leaving the bed,
• Particles are elutriateo from the bed and carried along with the off-gas
into the quench system, despite precautions.
26
-------
• Solids withdrawn from the process are of average bed composition, thus
making complete conversion in a single bed impossible.
9 Localized overheating is possible if adequate gas dispersion is not
provided.
• The pressure drop in the gas system of a fluidized-bed (boiling-bed) type
of reactor is larger than in other types of equipment and may be a serious
objection because of the large compressors required (Zenz and Othemer 1960)
Operation of Gasifiers
In general, raw or pretreated coal is injected into a gasifier either above
the bed or into it. At the same time, fluidizing gas and/or steam and oxygen
are fed to the bottom of the bed. Bed temperature is controlled for the
needs and conditions of each reactor system. Ash or residual char is removed
from the bottom of the bed and product gas is driven upward to the top of the
reactor. Because in all cases the gas is carrying particles elutriated from
the bed, it is passed through a cyclone. The solids escaping the cyclone are
generally fine and may constitute as much as 1-5 wt % or even 10 wt % of the
raw coal fed to the gasifier. In a free-fall injection system (Synthane,
HYGAS), a major portion of the elutriated solids is coal. (Bi-Gas is a
special case where it is desirable to have all solids elutriated from the
bed.) In a bottom-of-the-bed coal injection system, the solid's composition
will more closely approach that of the bed.
From the cyclone, the product gas leaves the reactor to be quenched. The
line from the cyclone generally protrudes through the side or top of the
reactor and is reasonably short, i.e., 10 to 20 feet at a maximum.
Gasifier Products
Because feed-entry geometry, temperature, pressure, and reactor configura-
tions vary, it is difficult to define a generalized reactor product. This
problem is complicated by the fact that few detailed studies have been made
of the components produced in gasifiers. Undoubtedly there are significant
differences in the gas-vapor composition at different levels within the
reactor as the various dissociation, hydrogenation, polymerization, combus-
tion, and reduction reactions occur. At the pilot plant level, the primary
components of the make-gas (or product gas) are of prime interest — as is
the maximization of methane production and the study of the relationship be-
tween CO, C02, and H2. The other components, with the exception of H2S and
NHa, make up a minor fraction of the gasifier product and have to date been
largely ignored. Thus, because of this dearth of data, one must treat process
gas in any part of the reactor system as if it had the same composition as the
off-gas from the reactor itself.
Oils and Tars in the Gas--
In addition to the major quantities of H2, CO, C02, CH^, and C2H6 made in the
Synthane gasifier, there are numerous minor constituents. Table 8 shows some
of these minor constituents of interest including sulfur compounds and BTX
(benzene, toluene, xylene) components. In practice, the BTX components
should be removed in the oil scrubber, and the sulfur compounds should be
27
-------
Table 8. Mass spectrometric analyses of Synthane benzene soluble tar.a
ro
oo
Parent Compound
Structural Type
Benzenes
Indenes
Indans
Naphthalenes
Fluoreftes
Acenaphthenes
3-ring aromatics
Phenyl naphthalenes
4-ring pericondensed
4-ring catacondensed
Phenols
Naphthols
Indanols
Acenaphthenols
Phenanthrols
Dibenzofurans
Dibenzothiophenes
Benzonaphthothiophenes
Fo rmu 1 a
C6H6
C6H,,CH2CH:CH
C6H,,CH2CH2CH2
C1CH8
C6H^CH2C6H^
CioH6(CH2)2
C6H^:(CH2)2:C6H,,
C6H5C]o H?
ND
C6H5OH
C10H7OH
C6H,,CH2CH2:CHOH
ND
CnHsOH
C6H,,OC6H,,
ND
B.F.°C
80.1
182.4
176.5
217.9
295
277.5
354.5
325
ND
ND
182
288
ND
ND
168
287
332.3
ND
Illinois #6 Coal
Vol %
Benzene
Soluble
2.1
8.6
1.9
11.6
9.6
13.5
13.8
9.8
7.2
4.0
2.8
ND
0.9
ND
2.7
6.3
3.5
1.7
ECI
Estimate
Vol % Gas6
0.017
0.048
0.010
0.058
0.037
0.056
0.05
0.031
ND
ND
0.019
ND
0.0043
ND
0.0089
0.024
0.012
m
Lignite
Vol %
Benzene
Soluble
4.1
1.5
3.5
19.0
7.2
12.0
10.5
3.5
3.5
1.4
13.7
9.7
1.7
2.5
ND
5.2
1.0
ND
ECI
Estimate
Vol % Gasfc
0.02
0.005
0.011
0.059
0.018
0.030
0.023
0.0066
ND
ND
0.056
0.026
0.0049
ND
ND
0.012
0.002
ND
Montana Sub-
bituminous Coal
Vol %
Benzene
Soluble
3.9
2.6
4.9
15.3
9.7
11.1
9.0
6.4
4.9
3.0
5.5
9.6
1.5
4.6
0.9
5.6
1.5
ND
ECI
Estimate
Vol % Gasfc
0.026
0.012
0.021
0.061
0.03
0.037
0.026
0.016
ND
ND
0.03
0.034
0.0057
ND
0.0023
0.017
0.004
ND
Pittsburgh Seam Coal
Vol %
Benzene
Soluble
1.9
6.1
2.1
16.5
10.7
15.8
14.8
7.6
7.6
4.1
3.0
ND
0.7
2.0
ND
4.7
2.4
ND
ECI
Estimate
Vol % Gasfc
0.016
0.034
0.011
0.083
0.041
0.066
0.053
0.024
ND
ND
0.020
ND
0.0033
ND
ND
0.018
0.0083
ND
aThe analyses given are derived from the Bruceton 25 Ib/hr coal feed laboratory scale Synthane gasifier. "These may be representative of those
gases which will be obtained from a [pilot plant and a] commercial operation [of the Synthane process!. There will be some differences due
to both variation in temperature, steam-oxygen feed quantities, and coal. Adapted from the work of Forney et al. (1974).
ECI estimate of concentration in gas phase.
°No data.
-------
removed by gas scrubbing (Synthane employs a Benfield hot carbonate gas puri-
fication system and activated carbon traps) (Forney et al. 1974). Table 9
shows combined data from two gas chromatographic analyses of the bench scale
product. One scan was of soluble oils dissolved in the condensed liquor from
the Synthane bench scale unit. The second analysis was of the benzene soluble
oils collected in the Synthane bench scale tar trap. The data were obtained
at Oak Ridge National Laboratory in conjunction with a project involving oils
from a number of sources of synthetic fuels (see also Tables A-l, A-2, and
A-3 in Appendix A).
The benzene soluble oils represent approximately 85% of the total oils col-
lected. This is a relatively consistent finding, whether the coal used in
the Synthane process is lignite, sub-bituminous, or bituminous. However, tar
yields do increase with increasing rank of coal, varying from approximately
3 wt % for lignite to approximately 5 wt % for bituminous coals (Lebowitz
et al. 1975). This information was utilized to determine the concentrations
of the individually identified components in the reactor product gas, assuming
a gas yield of 25 scf/lb coal (Table 10).
Special Cases--
Each plant is a special case. For example, it can be anticipated that the
tar yield from the MERC fixed-bed unit may be higher than that from any of
the fluid-bed units and that these tars may have a wider boiling range than
any others.
Material balances indicate that the HYGAS process produces about the same
quantity of liquid hydrocarbons as the free-fall Synthane process already
described. However, 95 wt % of the total HYGAS oil in the gasifier off-gas
can be defined as follows: 85 wt % toluene, 8 wt % benzene, 3 wt % (and
higher) C9 (Lee 1975) — excluding pretreater tars. The high proportion of
light oils is explained as being due to the extraordinarily rapid heat-up
in the second entrained flow gasifier, after volatilization of the more
reactive components in the first gasifier bed.
The C02 Acceptor process emits few, if any, light oils or tars. Undoubtedly
any that are produced are absorbed into the circulating dolomite and are
coked in the regenerator and thus are destroyed before they can leave the
reactor-regenerator system.
The Bi-Gas process is supposed to produce no oils, nor is it likely that the
Agglomerating Burner will produce oils. Therefore, the pilot plant designs
do not provide for oil production in either process.
Effects of Gasifier Coal Feed Geometry--
Coal may be fed to the gasifier at the top of the bed (fixed-bed reactors,
fluidized-bed reactors), at the bottom of the bed, or between these two ex-
tremities (fluid beds only). Apparently, the point of coal-feed delivery
does not affect the Btu value of the gasifier off-gas, but seems to affect
some constituents of the gas. In general, the available data from observa-
tions of the difference between C02 Acceptor bench scale product composition
and pilot plant product composition (oral communication, October 27, 1976,
by D. McCoy, C02 Acceptor Pilot Plant, Rapid City, South Dakota) and from
29
-------
Table 9. Organic compounds condensed from the Synthane gasification process (bench scale unit).a
Chromatographic
Identification
Acetic Acid
Propanoic Acid
n-Butanoic Acid
Acetamide
n-Pentanoic Acid
Propionamide
n-Hexanoic Acid
Butyramide
Phenol
n-Heptanoic Acid
a-Cresol
m&p-Cresols
n-Octanoic Acid
2, 6-Oimethyl phenol
o-Ethylphenol
2, 5- Dimethyl phenol
3,5-Oimethylphenol
2,3-Oimethylphenol
n-Nonanoic Acid
3,4-Dimethylphenol
n-Decanoic Acid
«-Naphthol
B-Naphthol
Naphthalene
2-Methylnaphthalene
1-Methylnaphthalene
Azalene
Biphenyl
2, 6- Dimethyl naphthalene
1,3 and 1 ,6-Dimethylnaphthalene
Butylated Hydroxytoluene
1,5 and 2,3-Dimethylnaphthalene
1 ,2-Dimethylnaphthalene
Acenaphthylene
Acenaphthene
Fluorene
9,10-Oihydroanthracene
Formula
CH3COOH
CH3CH2COOH
CH3CH2CH2COOH
CH3CONH2
CH3(CH2)3COOH
CH3CH2CO(NH2)
CH3(CH2)^COOH
ND
C6H5OH
ND
CH3C6HUOH
rCH^MH
'CHjCgh^OH'
ND
(CH3)2C6H3OH
C2H5C6H,,OH
(CH3)2C6H3OH
(CH3)2C6H3OH
(CH3)2C6H3OH
ND
(CH3)2C6H3OH
ND
CloHyOH
C,0H7OH
Cio^a
C10H7CH3
C10H7CH3
ND
£e:H5C6H5
CioMCH3)2
£10^5(^3)2
ND
CioH6(CH3)2
CioH6(CH3)2
C^ Qng CHCH
Cio^e (CH2)2
CgHijCI^CgHi,
C6HH:(CH2)2:C6HH
B.P.°C
118.1
141 .1
163.5
222
187
213
205
ND
182
ND
191 .5
f202.8.
1202.5^
ND
212
207.5
211.5
219.5
218
ND
225
ND
288
294.85
217.9
245
240-3
ND
254-5
ND
ND
ND
268
ND
265-75
277.5
293-5
305
Concentration
ug/g (ppm)
591
60.5
20.86
NCP
10.62
ND
21.16
ND
1958.9
ND
640.2
1740.1
ND
ND
34.48
28.92
213.9
237.6
25.86
ND
101.73
ND
8.17
24.65
0.139
1.263
0.031
ND
0.0017
0.048
0.066
ND
0.024
0.010
ND
IR6
0.0175
0.0022
^Adapted from the work of Massey and Dunlap (1976) and Guerin and Epler (1976).
Incomplete resolution.
No data.
30
-------
Table 10. Components in synthane gasifier gas (25 Ib/hr coal feed bench scale gasifier).13
Illinois # 6
Coal
Hydrogen Sulfide
Carbonyl Sulfide
Thiophene
Methyl Thiophene
Dimethyl Thiophene
Benzene
Toluene
C9 Aromatics
Sulfur Dioxide
Carbon Disulfide
Methyl Mercaptan
B.
H2S
COS
<(CH:CH)2>S
C5H6S
C6H8S
C6H6
C6H5CH3
ND
S02
CS2
CH3SH
P °C
-60
-50
84
112-116
137-141
80
111
ND
-10
46
6
ppm
9800
150
31
10
10
340
94
24
10
10
60
vol %
0.9800
0.0150
0.0031
0.0010
0.0010
0.0340
0.0094
0.0024
0.0010
0.0010
0.0060
Wyoming Sub-bituminous
Coal
ppm
2480
32
10
ND&
ND
434
59
27
6
ND
0.4
vol %
0.2480
0.0032
0.0010
ND
ND
0.0434
0.0059
0.0027
0.0006
ND
0.00004
Western Kentucky
Coal
ppm
2530
119
5
ND
ND
100
22
4
2
ND
33
vol %
0.2530
0.0119
0.0005
ND
ND
0.0100
0.0022
0.0004
0.0002
ND
0.0033
North Dakota
Lignite
ppm
1750
65
13
ND
11
1727
167
73
10
ND
10
vol %
0.1750
0.0065
0.0013
ND
0.0011
0.1727
0.0167
0.0073
0.0010
ND
0.0010
Pi ttsburgh
Seam Coal
ppm
860
11
42
7
6
1050
185
27
10
ND
8
vol %
0.0860
0.0011
0.0042
0.0007
0.0006
0.1050
0.0185
0.0027
0.0010
ND
0.0008
^Adapted from the work of Forney et al. (1974)
No data.
-------
Synthane bench scale data (Massey et al. 1975) would indicate that less of
such components as tar, phenol (Table 11), cyanide, and thiocyanate are pro-
duced from deep-bed injection than from free-fall injection of the coal
(Table 12).
The data presented by Massey et al. (1975), from the 4-inch-diameter Synthane
bench scale unit, indicate that for Synthane-produced tar and heteroatomic
compounds
• Changes in coal-feed geometry materially affected the quantity of tar
produced.
• All samples analyzed had initial boiling points substantially in excess
of 100°C (212°F). This suggests that few low molecular weight hydro-
carbons such as benzene, toluene, or xylene were produced,
• Thirty to sixty percent of the hydrocarbons present in the samples boiled
above 500°C (932°F). Tars collected late during these runs tended to
contain less +500°C material, though this shift did not lead to increased
Btu production. It is assumed that the Synthane tars will be more like
the late run samples collected from the 25 Ib/hr coal-feed unit, which
generally ran for less than 5 hours.
9 Changes in coal injection geometry had little effect on ammonia or H2S
production rates.
Sulfur Compounds--
It has been reported that approximately 90% of the organic sulfur in coal can
be expected to be converted to H2S during gasification (Williams and Dressel
1973). It has also been estimated that 8% of the total sulfur in the
feed coal to the Synthane process will remain in the char (U.S. Bureau of
Mines 1972), and in the HYGAS process, 0.5 wt % of the sulfur in the coal
was found to remain in the char (Lee 1975). Thus, it is obvious that the
total quantity of sulfur gasified will depend upon reactor conditions. The
distribution of sulfur compounds will be dependent upon the mode of operation,
temperature of operation, and coal feed. The available data would indicate
that the gasified sulfur may be distributed as shown in Table 13.
Nitrogen--
Nitrogen balances indicate that 78% of the nitrogen in the coal fed to the
Synthane Pilot Plant gasifier is converted to ammonia (U.S. Bureau of Mines
1972). Within the accuracy of bench scale data, ammonia production (from the
Synthane process) appears to vary from 15 to 20 Ib/ton moisture-ash-free
(MAP) coal for lignite and to average about 20 to 22 Ib/ton (MAP) for Illinois
No. 6 coal (Nakles et al. 1975). At the HYGAS Pilot Plant, measured ammonia
production yields were constantly below 50% though actual NH3 production
levels were expected to be 15 to 20 Ib/ton of coal or a 55% to 70% yield of
the total nitrogen in the coal feed (Massey et al. 1976a). In characterizing
the effluents of HYGAS, Massey et al. also indicated that the distribution of
nitrogen compounds was as shown in Table 14.
32
-------
Table 11. Decreased phenol production with increased depth of fresh coal injection.
a
OJ
CO
Procedure
Run No.
Compound Present
Phenol
Cresols
C2-Phenols
C3-Phenols
Dihydrics
Benzofuranols
Indanols •,
Acetophenones
Free-Fall Injections, ppm
CHPFI-49
3,400
2,840
1,090
no
250
70
150
CHPFI-55
2,660
2,610
780
100
540
100
100
Shallow-Bed Injections, ppm
CHPFI-80
1,300
530
140
20
60
30
40
CHPFI-96
1,270
890
270
50
20
40
50
CHPFI-97
1,000
930
330
50
20
50
60
Recovered from aqueous condensates from a range of Illinois #6 coal gasification
tests (Massey et al. 1975).
-------
Table 12. Steady-state effluent production rates: free-fall,
shallow-bed, and deep-bed injections of North Dakota
lignite into the Synthane 25 Ib/hr bench scale gasifier.a
Pollutant
Ib/ton MAP Coal
Gasification of North Dakota Lignite
Free-Fall
Injection
Shallow-Bed
Injection
Deep-Bed
Injection
Tar
74.1 ± 27
10.1 ± 5
6.3 ± 2.2
Phenol
11.9 ± 1.3
3.5 ± 1.9
0.5 ± 0.6
Chemical Oxygen
Demand
77.7 ± 14.4
11.8 ± 5.4
3.6 ± 2.4
Total Organic Carbon 22.0 ± 3.3
4.8 ± 1.3
2.7 ± 0.7
Inorganic Carbon
12.5 ± 2.4
11.0 ± 2.3
11.4 ± 2.4
Cyanide
Thiocyanate
Negligible
Negligible
Negligible
0.045 ± 0.083 £0.016 ± 0.002° <0.017 + 0.004C
Adapted from Massey et al. (1975).
The relatively constant inorganic carbon production levels reported for
different lignite injection positions are expected and reflect the
presence of a saturated amount of C02 in basic (pH 9) condensate.
^Measurements at or below the limiting sensitivity of the analytical
method employed.
34
-------
Table 13. Sulfur distribution.
Synthane (bench scale)*2
Compounds
H2S
COS
Thiophenes
S02C
CS2
Mercaptans
Illinois #6
Bituminous
vol %
97.2
1.5
0.5
0.1
0.1
0.6
North Dakota
Lignite
vol %
94.2
3.5
1.3
0.5
ND
0.5
Pittsburgh
Bituminous
vol %
91.1
1.2
5.8
1.1
ND
0.8
Lurgi,
vol T
95
2.4
0.3
md
0.3
2.0
a
,From the work of Forney et al. (1974).
From the work of Williams and Dressel (1973).
^Present in bench scale unit, but should be eliminated in pilot plants
aNo data.
Table 14. HYGAS Pilot Plant liquid effluent characteristics,
hydrogasification of Montana lignite, Run 37.a
Effluent Component
NH3
CN" (xlO6)
SCN"
Effluent Production
of Nitrogen Compounds
Ib/ton Coal, MAF^
13.1 ± 0.3
28.7 ± 15.7
2.5 ± 0.2
Wt % of
Nitrogen
Effluent
83.97
0.0002
16.02
Estimated Vol % of
Reactor Gas Stream
(dry basis)
0.47
0.67 (xlO~6)
0.03
aAdapted from Massey et al. (1976a).
Reported data represent only lower bounds on actual plant effluent production
rates. Not included in any steady-state data are effluents contained in oil
stripper water condensate, coal mill venturi scrubber water, and condensate
depressu-rization off-gas. In addition, during steady-state period #1, ef-
fluents in product gas cyclone slurry water and the oil/water/solids inter-
face from the product gas quench system were not measured.
35
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Because the gasifier atmosphere is reducing (contains excess hydrogen), no
NOX is expected to be produced during the gasification of coal, whether air
or oxygen is used. Further, even though NH3 converts relatively easily to
NOX when combusted, tests conducted on a low-Btu gasifier combustor combina-
tion indicated that "the overall conversion of coal nitrogen to NOX in a
gasification/combustion process was significantly less than that which occurs
in the direct burning of pulverized coal. These results indicate that the
conversion was reduced by a factor of two."(Lisauskas and Johnson 1976)
Trace Elements--
The degree of volatility of all elements and compounds is dependent both
upon the characteristics of the element or compound and upon the chemical
and physical characteristics of the atmosphere in which the element or com-
pound is placed. A study of the volatility of the trace elements in a
hypothetical coal was made by Ruch and Associates (1974) under the reducing
atmospheric conditions of a gasifier (Table 15). This study was expanded by
Attari (1973), who examined the volatility of coal-contained trace elements
at various points in the HYGAS gasifier. The anticipated trace element con-
centration that might be expected in the make-gas at various parts of
Attari's gasifier system has been calculated as shown in Table 16.
These calculations, based upon Attari's data, indicate that, under the con-
ditions specified in Table 16, the concentration of mercury could reach 0.7
ppm in the pretreater off-gas and 1.2 ppm in the gasifier off-gas (HYGAS type
system). If pretreater and gasifier are one continuous unit, then at a
gasifier temperature of 1830°F (1000°C), the total concentration of mercury
in the bed might be 1.6 ppm (Synthane or Bi-Gas type operation). In the
HYGAS operation where the liquid in the slurry feed appears in the reactor
off-gas stream, the actual concentration of mercury in the gasifier off-gas
stream would be more likely to approach 0.9 ppm than 1.2 ppm.
None of the available data indicate what occurs in the gasifier when an
element which is volatilized at a high-temperature portion of the reactor
passes into a lower-temperature portion of the reactor. It would be normal
for the element to condense on the nearest surface, e.g., coal, metal,
refractory, etc., and to concentrate at that point.
Problems
Problems in the gasifier system as described will probably consist primarily
of plugged lines, hot spots, insulation problems, and leaks. Leaks involve
release into the workplace of toxic substances, including the oils and trace
elements, estimated in Tables 10 and 16. To rectify any of the problems
listed, the reactor would have to be opened, probably after an emergency
shutdown.
Gross condensation in the reactor is unlikely unless the top of the reactor
cools. Condensation between the reactor and the quench system is possible,
particularly when high-temperature tars are produced (Synthane, MERC).
Low-temperature distillates such as those produced in HYGAS should not con-
dense prior to being quenched. (These generalizations on condensation will
also be valid for pretreater systems. Some of the distillates produced at
36
-------
Table 15. Trace elements —estimated volatility.
Component
Chlorine
Mercury
Selenium
Arsenic
Lead
Cadmium
Antimony
Vanadium
Nickel
Beryllium
Chromium
Zinc
Boron
Fluorine
Titanium
Hypothetical Coal,
ppnf3
1,400
0.2
2.08
14
34.78
2.52
1.26
32.7
21.07
1.61
13.75
272.2
102.2
60.9
700
Percent
Volatile23
90+
90+
74
65
63
62
33
30
24
18
nil
eg, 10
eg, 10
eg, 10
eg, 10
^Analyses taken from Table 5.
Volatility based mainly on gasification experiments (Attari 1975); chlorine
is taken from combustion tests; zinc, boron, fluorine, and titanium are
estimated at 10% for illustration in absence of data (Jahnig 1975).
Adapted from Ruch et al. (1974).
37
-------
GO
cx>
Table 16.
Trace element concentration at various stages
calculated on a raw coal basis for Pittsburg
After PT
430°C (806°F)fc
Element
Mercury
Selenium
Arsenic
Tellurium
Lead
Cadmi urn
Antimony
Vanadium
Nickel
Beryllium
Chromium
Raw Coal
ppm
0.27
1.7
9.6
0.11
5.9
0.78
0.15
33
12
0.92
15
After HG
650°C
(1200°F)fc
of the HYGAS gasification process,
#8 coal.a
After ETG
1000°C
Loss after
PPm
0.19
1.0
7.5
0.07
4.4
0.59
0.13
36
11
1.0
17
Loss, %
30
41
22
36
25
24
13
0
8
0
0
ppm
0.06
0.65
5.1
0.05
3.3
0.41
0.12
30
10
0.94
16
PT, %
68
35
32
29
25
31
8
9
9
0
0
PPm
0.01
0.44
3.4
0.04
2.2
0.30
0.10
23
9.1
0.75
15
(1832°F)b
Estimated Trace Element
Concentration in Off-Gas, Vol %
Total
Loss after Loss,
HG, %
19
12
18
9
19
14
13
21
8
18
0
%
96
74
65
64
63
62
33
30
24
18
0
After
PTa
7.1 x 10"7
1.6x 10"
5. Ox 10"5
7
5.6x 10"
1.3x 10"5
-6
3. Ox 10
2.9x 10~7
—
3. Ox 10"5
—
—
Between ,
PT and ETG
1.2 xlO"6
-6
9.4 xlO
7.2xlO"5
3.1 xlO"
1.4 xlO"5
-6
3.4 xlO
3,3 xlO"7
2.6 x 10"
4.3 xlO"5
3.7 xlO"5
Total
PT + HG + ETGe
1.6xlO"6
-5
1.9X 10
l.Ox 10"1*
_7
6.7 x 10
2.2X10"5
- 6
5.2 xlO
5.0X10"7
2.4 xlO""*
6.0 xlO"5
2.3 xlO"5
PT = Pretreatment
HG = Hydrogasification
ETG = Electrothermal Gasification
£Adapted from Attari (1973).
"Maximum temperature.
c,Basis: Assume 21.2 scf total gas/lb coal, 0.038 Ib make and feed water/lb coal
0.0082 Ib make oil/lb coal (IGT 1973).
IBasis: Assume 28.7 scf total gas/lb coal, 0.43 Ib make and feed water/lb coal, 0.038 Ib make oil/lb coal (IGT 1973).
"Basis: Assume 21 scf total gas/lb coal, 0.43 Ib make and feed water/lb coal, 0.046 Ib make oil/lb coal (IGT 1973).
-------
pretreater reactor temperatures will condense in the reactor or in the reactor
off-gas line if either the reactor head temperature or line temperature drops
below the reactor temperature by only a few degrees.) If condensation does
occur, employees will be exposed to the possibility of skin contact with
condensed products on the interior vessel walls when it is opened.
Solids in a fluid-bed reactor will most likely be so highly coked or ashed
that they are essentially inert. However, this may not be true in a fixed-
bed unit. They may also pose a dust hazard.
Ash Removal and Disposal
As stated previously, the composition of material in a fluid bed is an average
of fresh feed plus partially and completely reacted materials at operation
conditions. Therefore, material discharged from a median-temperature gasifier
(Synthane, HYGAS) will contain more carbon than that from a high-temperature
gasifier (Bi-Gas) or combustor (Agglomerating Burner). It may be presumed
that at the temperature of the gasification reaction, the char product will be
reasonably stable and that, therefore, fresh unquenched char will probably
present only a dust hazard. The higher the process temperature, the more
stable the solid by-products. The fixed-bed gasifier (MERC) is a different
case. Here, the highest temperatures are observed near the bottom of the bed,
where the devolatilized coal is in contact with the incoming air or oxygen.
Temperatures are relatively high and essentially complete combustion takes
place. The discharged ash will be stable.
At the Synthane Pilot Plant, char from the fluid bed will flow into one of two
lockhoppers, similar to those of the Petrocarb system already described for
the coal-feed system. In the ash system, the bottom of the gasifier is com-
parable to the weigh-hopper, the ash lockhoppers to the storage injector, and
the low-pressure char slurry tank to the primary coal injector, except that,
here, the bottom of the gasifier is pressurized while the char slurry tank is
at atmospheric pressure.
From the char lockhopper, the char is conveyed pneumatically with low-pressure
steam to the low-pressure agitated slurry tank through a cold water venturi
nozzle. The venturi insures complete wetting of the char. Water to the ven-
turi is supplied by circulation of the tank contents. Any gases (primarily
steam or oxygen) released from the gasifier with the char are vented from the
tank to the atmosphere. From the low-pressure agitated slurry tank, the
cooled slurry is pumped to the agitated slurry filter feed tank. (In case of
emergency, the lockhopper system can be bypassed and the hot char conveyed to
a high-pressure slurry tank. Slurry is depressurized through a flow control
valve to the slurry filter feed tank, which is, presumably, vented to the
atmosphere.) The char slurry is then pumped to one of two continuous filters.
The 150°F (65°C) filtrate is cooled and recirculated to the slurry tank in
current operation. The filter cake (char containing ^ 15-25 wt % water) is
conveyed to a storage pile, and then to disposal (U.S. Bureau of Mines 1972).
Special Cases--
The HYGAS Pilot Plant char removal system is similar to the Synthane emergency
system. The primary difference is that from the high-pressure slurry tank,
the slurry is pumped through a de-energizer (spared) for pressure reduction.
39
-------
Gas dissolved in the slurry is vented to the atmosphere. After depressuriza-
tion, the char slurry stream joins the several venturi scrubber water streams
at the Edens separator (IGT 1973), to be separated and filtered as previously
described.
Ash from the C02 Acceptor system is sufficiently fine to be elutriated from
the regenerator, removed from the gas stream with cyclones, and dropped into
a lockhopper-slurry system similar to the one described for the Synthane
plant. The slurry is dumped into the wastewater pond for eventual recovery
and burial in a clay-lined pit. Other char and limestone purge systems
employ lockhoppers and tote bins. Tote bin contents are also buried (Evans
1976a; Steams-Roger 1976b).
Analyses-
Char analyses are shown in Table 17. The differences in the carbon-to-ash
ratios reflect the differences in the process variables.
Analyses of trace elements in the water from Synthane and C02 Acceptor are
depicted in Table 18. It should be noted, however, that in both cases this
water !s r-cycled filtrate. (It is of interest that the values for phenol
and several trace elements in the Rapid City municipal water are the same as
or higher than those for the process pond water.)
Problem Areas--
Leaks--In the ash system, the primary problem is the probability of leaks in
the lockhopper valves and/or the formation of plugs in the system. If these
valves do leak, process gas from the vessel may be vented into the atmosphere,
depending on the size of the leak and the process flows.
Toxicity--In general, it would appear that the ash or chars themselves are
essentially inert. However, because of the large surface areas common to
most chars, they may act as oil or tar adsorbers when they are dumped into or
slurried with water that contains make-oil/tar, dissolved or suspended. By
the same mechanism, they may also concentrate the dissolved trace elements
from the recycle water. Then, although the trace elements in the char or ash
may be inert (i.e., tied up in the carbonaceous and ash materials within the
coal), the adsorbed trace elements would be easily removed by leaching.
(Alternatively this possibility for adsorption might be exploited to clean up
pond water,)
Radioactivity—There has been some concern expressed about radioactive coal
ash as certain coals in the Rocky Mountain Region have been shown to contain
uranium. Some of these coal deposits contain 0.005% to 0.01% uranium, and
deposits in local areas may contain higher percentages. Investigations by
the U.S. Geological Survey suggest that lignites may contain the most uranium,
and sub-bituminous B and C coals the next largest concentrations. Uranium-
bearing coal is present in Wyoming, Colorado, New Mexico, and southeastern
Idaho. The higher ranked bituminous coals and anthracite of the central and
eastern United States rarely contain more than 0.001% uranium (Magee et al.
1973).
40
-------
Table 17. Char and ash analyses.
Hydrogen
Carbon
Nitrogen
Sulfur
Oxygen
Ash
CaS - CaO
HYGAS
Lignitea
0.76
34.49
0.19
0.17
3.26
61.13
me
C02 Acceptor
Lignite
0.00
7.38
0.00
0.00
0.00
90.79
1.83
Synthane
Bituminous0
1.0
72.4
0.5
0.4
1.8
23.9
ND
Lignite
1.2 ± 0.2
52.4 ± 4.8
0.5 ± 0.1
0.3 ± 0.1
3.9 ± 0.8
41.9 ± 5.3
ND
^Adapted from Lee (1975).
^Adapted from Fink et al. (1975).
^Data from pilot plant drawings (U.S. Bureau of Mines 1972).
Data from 25 Ib/hr bench scale reactor (Nakles et al. 1975).
eHo data.
-------
From measurements of gamma activity, it has been determined that the content
of radioactive elements in coal is generally less than that in sedimentary
rocks (Magee et al. 1973). Thus, it appears that radioactive ash would
rarely be a problem. Should the ash be sufficiently radioactive to present
a problem, it should be handled as if it were a uranium ore and should be
further processed to recover its nuclear fuel value.
Analytical Difficulties—Massey (Project Manager of the ERDA-sponsored
"Gasification Pilot Plant Environmental Assessment Project") has expressed
concern about the accuracy and representativeness of either single grab
samples or 8-hour samples of condensate or gas streams. He has obtained
data which indicate that this type of pilot plant sample can be highly
variable. The data may indicate, for example, that component A_is disappear-
ing while component B is increasing and the concentration of C is stable.
This sequence is especially true when one is looking for very small concen-
trations of materials. However, unwary extrapolation of such data would lead
to incorrect results (Evans 1976a). Such variability in minor element sam-
pling is not only possible, but quite likely at the pilot plant. Of special
concern is preservation of the samples, as coal conversion liquid products
or water (liquor) samples tend to be highly unstable.
GAS QUENCH AND SCRUBBING SYSTEM
Venturi Water Scrubber
Synthane gasifier off-gas contains solids, tars*, and oils*, which must be
removed prior to downstream use. It must also be cooled. The quench system
in most general use is the water venturi scrubber followed by a scrubber
surge tank and secondary scrubbing (Figure 8).
In the Synthane plant, the 1400°F (760°C) reactor off-gas is contacted with
350°F (177°C) recycle water. The venturi action atomizes the scrubbing water,
which provides a high contact surface and cools the gas to 445°F (229°C).
This is the best available means for intimate water/gas contact and for water
scrubbing. The cooling effect condenses both excess water and some tars.
The gas-water mixture flows into a scrubber surge tank, where the gas separates
and passes into the raw gas scrubber. The water, now containing tar, dis-
solved gas, and solids, is fed through a centrifugal pump (spared). From the
pump, the venturi feed water flows through a cooler (spared), which cools the
*It is estimated that the Synthane gasifier off-gas will contain 212 Ib per
hour of oils and tars, assumed to be divided in the following manner (see
Appendix E):
Light Oil Middle Oil Heavy Oil Residue
Estimated molecular weight 150 190 230 400
Estimated average boiling
point, °C 168.5 260 413 510
Estimated weight, Ib/hr 10.6 61.5 55.1 84.8
42
-------
L.P. STiAM
WATER TO
THERMAL OXIOIZER
TAR TO ITHeRUAL OXIOIZER
8. tea quancti and tcruttlnf syitM — Syfithsn* Pilot Plwit.
venturi feed water while producing low-pressure steam from boiler feed water.
No regular makeup water is supplied, as off-gas condensate should supply all
that the system requires.
Raw Gas Scrubber
In a second system on the scrubber surge tank, water is taken from the surge
tank to a second centrifugal pump (spared), through a second cooler (spared),
to the top of the lower section of the raw gas scrubber. Here the gas is
recontacted with the scrubbing water, first in a baffled section, and then in
a packed bed for further removal of elutriated solids or tar. The water is
then returned to the scrubber surge tank. If required in the Synthane process,
an oil scrubber is available.
If the oil scrubber is used, the gas passes through a series of oil-laden
baffle plates, and then through a demister placed at the top of the vessel.
Emerging gas temperature will be 330°F (165°C). The gas stream should then
be free of heavy tar, solids, and excess water. Some gas and light hydro-
carbons will be dissolved in both the scrubber water and the wash oil.
Alternatively, vapor pressure calculations indicate that light oils formed
-------
will be coal-derived distillate, probably boiling in the 400° to 600°F
(204° to 316°C) range, may be vaporized out of the raw gas scrubber. (Based
on these calculations, it is estimated that the clean raw gas from the
scrubbers in the Synthane Pilot Plant may contain 10.6 Ib/hr of light oil,
82 Ib/hr of middle oil, and 0.1 Ib/hr of heavy oil.)
The wash oil is recycled from the upper portion of the raw gas scrubber to
the wash oil tank. The wash oil tank is the surge for the centrifugal wash
oil pump (spared), which returns the oil back to the top of the raw gas
scrubber at a maximum rate of 24 gpm. (Each gallon of oil scrubs ^ 107 scf of
gas per hour.) Makeup oil is added to the system as required by a recipro-
cating pump at a maximum rate of 5 gpm. Drained oil is sent to the decanter
via an oil drain tank. This oil will probably contain most of the heavy oil
and some residue. It is also obvious that these concentrates of higher boil-
ing components will progressively increase as the gas strips out the lighter
components.
Decanter
Excess condensate from the scrubber surge tank will overflow into the decanter,
It will be cooled (cooler spared) from 396°F (202°C) to 180°F (82°C), then
depressurized through a pressure control valve (double blocked and bypassed)
from 1000 psig to atmospheric pressure. It is estimated (U.S. Bureau of
Mines 1972) that this water will contain 0.9 wt % C02, 0.8 wt % NH3, up to
3.9 wt % tar and oil, and 0-9.9 wt % solids (coal fines and char). Decanted
water goes to a wastewater receiver to be either recycled to the gasifier or
pumped (pump spared) to the thermal oxidizer. Gases dissolved in the scrub-
bing water at high pressure are released to the thermal oxidizer. Decanted
tar and solids may be either recycled back to the gasifier for gasification
(reciprocating pump spared) or disposed of by thermal oxidation.
Problems
There are a number of potential problems in the gas quenching and scrubbing
systems, many of which depend specifically on the product and product mix
being handled.
If the gasifier product contains heavy tar, this tar may condense in some of
the cooler inlet portions of the venturi piping, as previously described. If
condensation does occur, solids will collect in the tar while the tar is
simultaneously undergoing polymerization. Next, the shearing action plus the
rapid quenching in the venturi may form tar fog (submicron aerosol of con-
densed tar particles). Such a fog is difficult to precipitate, except by
thorough oil scrubbing. If sufficient heavy tar is present in the venturi
discharge liquid, an extremely stable emulsion will be formed in the scrubber
surge tank. (Coal or char fines will add to the emulsion stability.)
Another potential problem in the scrubber surge tank is the buildup of sludge
(solids and tars) in the bottom of the tank, with subsequent possible plugging
of the venturi scrubber recycle pump suction line.
The venturi scrubber recycle pump will have to pump solids, which could cause
excessive wear. This pump also circulates some coal-derived oils, which
could affect pump seals, i.e., unless a proper choice of seal is made. It is
44
-------
also possible that solids will collect in the raw gas scrubber section of the
scrubber surge tank and cause similar problems in this pump. The two recycle
water coolers may also be subject to heavy wear due to solids in the recycle
water. Further, it is possible that tar deposition will occur at the cold
ends of these coolers. Such deposition is a function of tar molecular weight
and the temperature differential between the coolant and the fluid being
cooled.
In the lower (water) portion of the raw gas scrubber, sludge may accumulate
either on any of the plates or in the packed bed. Likewise, sludge could
accumulate on the oil-side plates or in the demister screen. Such accumula-
tion will decrease the efficiency of oil-gas contact and increase the pressure
differential across the unit.
The scrubber surge tank overflow water cooler will be subject to wear or tar
deposition, and the letdown valve downstream from the cooler will be subject
to rapid wear from both dissolved gas release and solids.
The list of possible problems described for the scrubber system and scrubber
surge tank is multiplied in the decanter and the decanter oil and water trans-
fer pumps. While the higher temperatures in the surge tank may reduce emul-
sion formation, letdown of the cooled condensate across the letdown valve
will promote their formation. Sludges will also form in the bottom of the
decanter and in the decanter oil well.
The problems described for the scrubber and decanter systems will cause
operating difficulties, which will necessitate frequent visual inspection,
cleaning, and maintenance of equipment. Vessel cleaning will often require
entry by the cleaning crew, especially for the removal of sludges. It will
also be necessary to see that the sludges are correctly handled during clean-
ing to reduce spills, and that the sludge is disposed of properly. Available
data do not indicate that planned procedures for this operation are widely
disseminated.
Special Cases
The venturi scrubber-quench section just described is similar to those in many
of the major plants, as the requirement for removal of solids is universal.
However, the HYGAS plant uses a system of sequential quench towers instead of
a venturi scrubber for scrubbing and quenching the reactor off-gas. The re-
mainder of the HYGAS system is also unconventional. Use of toluene as the
feed slurry liquid in the HYGAS plant means that the magnitude of any tars
generated in the reactor may be overwhelmed by the presence of the toluene.*
It has been necessary to install a two-stage quench and a light oil stripping
section in the HYGAS Pilot Plant to insure recovery of make- and slurry-oil
(Institute of Gas Technology 1975). Therefore, tar or tar deposits from the
gasifier will probably present few problems. At the HYGAS plant, solids from
all of the venturi or quench systems go to an Edens separator for recovery.
*Data indicate that the HYGAS oil is 85 wt % toluene, 8 wt % benzene, and
3 wt % C9 hydrocarbons (Lee 1975). Discussion at the HYGAS plant indicated
that the top end point for this oil is normally 550°F (228°C) with an
occasional 650°F (343°C) observed.
45
-------
(This unit is essentially a settling and drag tank. Coarse settled solids are
removed with a chain conveyor to a pile for subsequent disposal.) Fines from
the separator are removed via a precoated filter, and "clean" water is re-
turned to the wastewater pond. At the pilot plant, the Edens separator, the
filter, and the wastewater pond are open to the atmosphere. The water in each
of these unit operations does contain dissolved light oil. When hot water_is
pumped into the wastewater pond, it may tend to steam distill some light oils
into the atmosphere.
Water from the venturi scrubbers at the C02 Acceptor Pilot Plant goes directly
to the wastewater pond. Solids are filtered out of the water with hay filters
and the water is recirculated. A system was installed for oil recovery but
no oils or only trace quantities of oil were generated; the oil recovery
system therefore is no longer used (Massey et al. 1976b; Evans 1976a).
The Agglomerating Burner is not expected to produce tars or oils. If any are
produced, they will be skimmed from the venturi scrubber recycle water and
fed directly to the thermal oxidizer with the product gas and burner off-gas.
Product gas and recovered oils from the MERC unit are fed directly to a
thermal oxidizer.
No product oils are anticipated from the Bi-Gas plant. Venturi scrubber
solids are settled in a wastewater pond for eventual recovery and disposal.
Composition of Coal Gasification Condensates
The condensate or quench water, in addition to having gross quantities of oil,
tar, and solids mixed into it, also contains dissolved measurable quantities
of heterocyclic and hydrocarbon compounds. Further, if the volatilized trace
metals are to be removed from the gasifier product gas, they must be removed
either in the scrubbing water, in the scrubbing oil, or in a guard bed.
Available data would indicate that appreciable quantities of these trace
metals are found in the condensate or gas scrubbing liquors (Table 18).
The gross quantities of solids, tars, or oils can be separated from the water
by decanting or settling.* After these treatments, the water will still con-
tain finely divided solids and dissolved materials, as illustrated in Tables
18 and 19. (This Synthane benchscale information should not be accepted as
the final word for that process, but it is indicative of relative values of
the components that may be found in the effluent.)
Prior to disposal, recovered tars and oils are stored in tank yards within
the plant area. Vent gas compositions for two HYGAS systems are given in
Table 20. These should be considered as indicative of values only at the
It should be noted that since these solids have been in the scrubbing system,
they may have adsorbed a relatively large quantity of oil or trace metals,
which could be readily leached. If the solid material or the water is in-
cinerated, these trace elements will be released into the atmosphtere — a
matter of little concern at the pilot plant level because of both the
dilution factor and the relatively small quantities of coal being converted.
46
-------
Table 18. Trace elements in condensate, coal gasification tests.
Trace Elements
in Condensate
Synthane*
Run #1 Run #2
C02 Acceptor2
Bituminous
Coal
Lignite
Calcium
Iron
Magnesium
Aluminum
Chlorine
Sodium
Selenium
Potassium
Barium
Phosphorus
Zinc
Manganese
Germanium
Arsenic
Nickel
Strontium
Tin
Copper
Columbium
Chromium
Vanadium
Cobalt
4.4
2.6
1.5
0.8
ND
ND
401
117
109
82
44
36
32
44
23
33
25
16
7
4
4
1
Parts per Million
3.6
2.9
1.8
0.7
NO
ND
Parts per Bill ion
323
204
155
92
83
38
61
28
34
24
26
20
5
8
2
2
*
*
171
md
7
30
ND
86,000
ND
ND
ND
40
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
*Less in pond water than in city water.
aFor a commercial coal-to-gas plant, this water would be
purified as completely as possible and then used as re-
cycled cooling water. Adapted from Massey et al. (1975).
Analyses of the Synthane 25 Ib/hr bench scale gasifier
condensate performed by the EPA at its Southeast Environ-
mental Research Laboratory for trace elements in the
water. Adapted from Forney et al. (1974).
3Process pond water values less city water values.
dNo data.
47
-------
Table 19. Composition of effluent condensate.
Product Gas
Quench Condensate
pH
Phenols, mg/i
HH, as 1, mg/t
IOC. mi/i
s".»»/i
CN~, B9/L
iCH". will
TDS. »9/t
TSS, ng/t
Toluene, wt t
Hexane-soluble
oil. mg/t
lor de, ng/t
Bicarbonate
Hln.
7.7
1,480
2.980
3,876
120
<0.001
270
1.352
20
0.004
"
Hax.
8.3
2,680
5,000
4,948
138
<0.001
780
2.168
52
0.007
6.328
HTGAS Pilot PI.
Oil Stripper
Bottoas
Hln. Hax.
9.2 9.9
185 1.560
10 251
3,192 13,560
0.03 0.03
0.001 0.007
128 420
684 6,154
28.530 59,076
6,328 8.567
nt Montana
Gas If
Slurr
Hln.
7.0
0.008
3.12
25
<0.003
<0.001
0.2
370
225
--
8
t Ignite"
ier Ash
y Water
Hax.
10.2
0.245
4.75
384
<0.01
<0.001
5
20.078
96,052
--
11
Discharge from
Holding Pond
Hln. Hax.
8.8 10.6
212 612
54 540
505 10,704
<0.01 108
670 1 ,920
0.001 0.007
2 134
908 27,292
0.001 (7)
35 95
Effluent
Production
Ib/ton Coal . MAF°
__
11.4 j 2.4
13.1 1 0.3
39.1 t 15.4
0.2 i 0.1
(28.7 i 15.7)xlO'S
2.5 1 0.2
12.4 j 0.69
__*
"
-
Illinois
No. 6
Bituminous0
8.6
2.600
8,100*
400J
0.6
152
--
600
"
"
15,000
500
6,000k
ll.OOO*
Synthane 25 Ib/hr
Pittsburgh Western
Seam Kentucky
Bituminous0 Bituminous
9.3 8.9
1,700 3.700
11,000 10,000
_.
-.
0.6 0.5
186 200
23 55
Bench Scale Gaslfler
Wyoming North North Dakota
Sub- Dakota L1gnlted
bituminous0 Lignite Ib/ton HAF Coal
8.7 9.2
6,000 6,600 11.9 ± 1.3
9,520 7,200
22.0 1 3.3
0.23 0.1 Negligible
23 22 0.045 1 0.083
140 64
„
CO Acceptor
Process Hater
Holding Pond/
Win. Max
7.8 8.9
0.001 0.017*
24 Z 296
0.01 0.48"
0.02 0.12
1,002 2.988
257 2.988
-pi
oo
TOC - Total organic carbon
TDS = Total dissolved solids TSS = Total suspended solids COD = Chemical oxygen demand
: al. (1976a).
''teoSfted'daa'Jepresent'on'rtouer bounds on"actual plant effluent production rates. Not Included In any steady state data are
effluents contained In oil stripper water condensate, coal .111 Venturt scrubber Hater, and condensate depressurllatlon off-gas.
In addition, during steady-state period II, effluents In product gas cyclone slurry water and the oll/water/sollds Interface
fro» tbe product gas quench system were not measured.
•Adapted from the work of Forney et at. (1974).
"Adapted from the work of Nakles et al. (1975).
"jar Ib/ton HAF coal • 71.1 1 27.
•'Adapted from the work of Hassey et al. (1976b). ,
»TB itata froo steady-state period 14 are not Included In the reported average. A revelw of the TDS data for all samples of
gtslfler ash slurry water during Run 37 Indicates that the value reported for the single test In steady-state period (4 Is
*D«ur9atnered Here not believed to be sufficiently representative to fora a basis for proper characterization of TSS.
^85 percent free NH,.
JS- - 400; SO; - 300; SO; . 1,400; S2OS - 1,000.
7Not from same analysis.
'City water » 0.004
"V • 0.48; SOI ' 1.12; SnJ = 380.
-------
Table 20. HYGAS Pilot Plant, vent gas compositions,
Montana lignite.a
Gas Composition, vol %
Component
N2
CO
C02
H2
H2S
CH4
C2H6
C3H8
C4H10
C5H12
C2H4
C3H6
C4H8
C5H10
C4H6
C5H8
C8H10
C2H 2
Ar
Oil Stripper
Vent Gas5
Run 37
Minimum
19.6
CNDd
56.8
8.3
0.1
5.6
0.5
ND
0.2
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
Maximum
22.5
0.8
61.0
10.9
0.7
9.8
1.1
0.2
0.3
0.07
ND
0.1
0.2
0.06
0.03
0.01
ND
0.01
0.02
Light Oil
Storage Tank
Run 37
Minimum
4.3
me
50.2
6.7
ND
9.0
1.0
0.01
0.2
ND
ND
0.06
ND
0.07
ND
ND
ND
ND
ND
Maximum
27.
1.5
7.5
9.0
0.
12.3
1.7
0.4
0.4
0.1
0.1
0.2
0.4
0.2
0.03
0.02
0.01
0.03
0.02
^Adapted from the work of Massey et al. (1976a)
Components not analyzed include NH3 aad HCN.
jVent gas flow rate, 81 to 165 Ib/hr.
Component not detected.
eNo data.
49
-------
time and place they were taken. "What little information is available on
gaseous effluents (from the second generation pilot plants), in particular
sulfur (and nitrogen), fs based strictly on thermodynamic arguments; and no
comprehensive gas or solid effluent data have been taken, as yet, which could
serve as a reference for evaluation of published data (or of the process
itself)" (Massey et al. 1976a).
Hot Gas Cleanup
Hot gas cleanup of low-Btu gas has not yet been considered here. These pro-
cesses attempt to retain the sensible heat of the low-Btu gas — which repre-
sents a considerable fraction of the total available heat from such gases
while at the same time removing from the gas the objectionable contaminants,
i.e., solids, trace metals, H2S, and the other sulfur- or nitrogen-bearing
compounds. Two benchscale units are being tested at MERC. One process
under test utilizes an iron oxide fly ash adsorbent which has removed 97% to
98% of the sulfur (H2S) in hot (1300° to 1500°F [704° - 816°C]), low-Btu gas,
and shows an adsorption capacity of 10-12 wt %. An iron-oxide silica adsor-
bent that permits operation at temperatures of up to 1700°F (927°C) has also
been developed (Lewis et al. 1974; Seamans and White 1976). A two-part
paper study on high-temperature particulate removal and sulfur capture is
being sponsored by the Electric Power Research Institute. To date, no new
developments from this study have been published (Andrews 1976), In any
case, these systems are in very early stages of development.
Medium-Btu Gas
At this point in the gasification process, a relatively clean medium-Btu gas
has been produced. All particles and heavy tars have been removed from the
gas (at the Bi-Gas plant a pair of alumina filters have been placed upstream
of the shift conversion unit to insure solids removal), and the water, light
oil, and medium oil contents have been reduced. In the low-Btu processes,
the gas is ready for "drying" or for use; no further processing of the gas is
necessary. In pipeline gas manufacturing plants, the medium-Btu gas is ready
for further processing.
SHIFT CONVERSION
The water-gas shift reaction
CO + H20 —* C02 + H2
is performed to adjust the hydrogen .-carbon monoxide ratio in the raw gas to
3:1, the required ratio for carrying out the methanation step.
In the Synthane process (see Figure 9), the clean gas from the raw gas scrubber
is divided, half of the gas bypassing the shift converter system and Kalf
passing through it. The gas to the converter is heated and steam is added, and
the mixture is then passed down through a packed catalyst bed. The usual
catalyst for this reaction is cobalt-molybdenum on an alumina base, (This
catalyst is being tested so that its capacity for thiophene destruction can
be observed.) The exothermic reaction raises the inlet gas temperature from
50
-------
720°F (382°C) to 825°F (441°C). The shifted gas then rejoins the main gas
stream and the entire stream is cooled to 125°F (52°C) as the acid-water
condensate is drained to the decanter. It is estimated that the heavy oil
has essentially been eliminated at this point, that the middle oil has been
reduced to 0.16 Ib/hr, and that the light oil is unaffected.
CLEAN RAW
GAS fffO
-------
GAS PURIFICATION
General Discussion
Before the raw gas is upgraded to pipeline specifications by methanation, all
sulfur compounds must be removed from the methanator feed gas. If they are
not removed, the methanation catalyst will be "poisoned" and its activity
severely reduced. Further, carbon dioxide must be separated from the combus-
tible product to achieve the pipeline heating value of 1000 Btu per scf.
A variety of processes is available for simultaneously separating carbon
dioxide and hydrogen sulfide from the product gas stream.
Process Discussion
The Benfield process is used for acid gas removal at both the C02 Acceptor
and Synthane pilot plants (see Figure 10). This process uses a hot carbonate
solution with diethanolamine as the activating agent, and is based on the
following overall reactions:
K2C03
K2C03
C02
H2S
H20
> 2 KHC03
KHS + KHC03
Ftjura 10. *c1d JU KTUtMnf —9«if1«l4 lyim. SyntHun Pilot Pint.
52
-------
The hot potassium carbonate process adsorbs H2S readily, and reduces it to
trace quantities in the sweet gas. Carbon dioxide is adsorbed less readily
and its concentration is higher (approximately 4%) in the sweet gas.
An added advantage of the carbonate process is that both carbon disulfide and
carbonyl sulfide can be removed from the gas stream without significant deg-
radation of the solution. Carbonyl sulfide, for example, will hydrolyze as
follows:
COS + H20
C0
HS
The products of the hydrolysis will then react as shown in the equations
already presented.
At the Synthane Pilot Plant, the cold (125°F [52°C]), sour process gas enters
the bottom of the absorber and passes upward in countercurrent contact with
the descending lean 226°F (108°C) potassium carbonate solution. In the top
tray, 125°F (52°C) potassium carbonate is introduced to lower the total acid
gas concentration. The sweetened gas leaves the top of the absorber at 130°F
(55°C) (see Table 21). Because of the difference in gas-carbonate temperatures,
no hydrocarbons will condense in the absorber.
In the Synthane Pilot Plant, approximately 70% of the sweetened gas is used
as fuel for plant furnaces or burned in the thermal oxidizer. The remaining
30% of the gas containing 3.26 Ib/hr light oil and 0.072 Ib/hr middle oil
is cooled to 95°F (35°C) for removal of excess water. Upon cooling, the
middle oil content of the gas drops to less than 0.01 Ib/hr and the light oil
content drops to 0.8 Ib/hr due to condensation.
Rich carbonate solution leaves the bottom of the absorber and flows to the
stripper, which operates at about 50 psig. The sudden release in pressure
flashes a large portion of the acid gases at the top tray of the stripper.
The partially stripped solution then flows downward through the stripper
for further regeneration by stripping steam from the reboiler.
The acid gases, together with some water vapor, pass overhead from the stripper
and through a condenser. The steam is condensed and separated from the acid
gases in the reflux accumulator. From the reflux accumulator, water is re-
turned to the stripper as reflux and acid gases flow to the thermal oxidizer
or go to a Stretford unit for further processing.
Regenerated solution from the bottom of the stripper is pumped to the top of
the absorber for reuse. The temperature at the bottom of the stripper will
normally run about 237°F (114°C) (Maddox 1974).
Problems--
No unusual problems are foreseen in the gas purification section (see the
section on nitrosamines below). As the potassium carbonate is an electrolyte,
stress corrosion may occur; however, potassium disulfide formed from the H2S
reactions should act as a corrosion inhibitor. Trace impurities in the gas
may form undesirable side reactions, but these can be minimized by removing
53
-------
Table 21. Gas purification: Synthane Pilot Plant.a
Component
Hydrogen
Carbon Monoxide
Carbon Dioxide
Methane
Ethane
Nitrogen
Hydrogen Sulfide
Water
Sour Gas
mol/hr
107.0
34.7
145.7
84.1
2.7
6.1
2.6
0.8
Sweet Gas
mol/hr
106.2
34.6
2.3
83.6
2.7
6.1
<10 ppm
0.6
Pressure, psig 965 964
Temperature, °F
°C
125
51.7
130
54.4
^Adapted from U.S. Bureau of Mines (1972)
54
-------
a small sidestream (purge) from the unit. Erosion problems may also occur,
especially at the lean solution pump and at the pressure reduction valve.
These problems could lead to leaks in the system unless maintenance checks on
the equipment are made regularly.
It should be noted that the acid gas from the gas sweetening process now
contains much higher concentrations of H2S, COS, CS2, CH3SH, and thiophenes
than was heretofore possible. Leaking gases and vapors in this portion of the
system (to and including the sulfur recovery section) would be exceedingly
toxic.
Special Cases--
The HYGAS Pilot Plant uses the diglycolamine process for gas purification. In
this process, H2S is removed to pipeline specifications while C02 is completely
removed. The diglycolamine will react with both carbonyl sulfide and carbon
disulfide (see Table 22). These reactions are irreversible in the normal
regeneration cycle. The sweet gas leaving the absorber at 100°F (38°C) will
contain some toluene, but no problems seem to have developed at the HYGAS
plant. There may be one problem encountered in the diglycolamine absorber
not seen with the Benfield unit —foaming. According to Maddox (1974),
foaming can be caused by the following:
• Suspended solids
• Condensed hydrocarbons
t Almost any other foreign material
The use of diglycolamine or other amine absorbers poses the potential problem
of nitrosamine formation if the amine comes in contact with NOx compounds
(Neurath 1972). While it is doubtful that NOx compounds would be generated
in the gasification process (Lisauskas and Johnson 1976), it is possible that
the amine could leak to the atmosphere. In the open air it is much more
possible for the amine to come in contact with the NOX compounds in the at-
mosphere —for example, from nearby electrical generating stations, plant
thermal oxidizers, steam generators, or normal air pollution.
At the Bi-Gas Pilot Plant, the Selexol process has been chosen for gas
purification. The Selexol solvent is the dimethyl ether of polyethylene
glycol (DMPEG).
The basic Selexol process flow scheme (Figure 11) is simple. Dehydrated sour
gas is contacted with the DMPEG solvent at high pressures to adsorb the acid
gas constituents. The acid gas solubilities in DMPEG are essentially pro-
portional to the partial pressures of the acid gases. Hydrogen sulfide is
significantly more soluble than C02 in DMPEG. Therefore, some selectivity
for H2S can be designed into the absorption system. The heat of absorption
with the DMPEG solvent and the acid gas system is negligible so that the
increase in solvent temperature across the absorber is insignificant
(Maddox 1974).
The DMPEG shows a preferential selectivity for acid gases as opposed to
hydrocarbons. Methane may be included among those hydrocarbons absorbed
though the higher molecular weight hydrocarbons are more soluble than the
lighter hydrocarbons. Intermediate distillation of these absorbed hydro-
carbons by flash depressurization is required to remove them.
55
-------
Table 22. Sulfur components in acid gas stream, Run 37, HYGAS Pilot Plant Montana lignite.
a
en
cr>
Compound
Methyl mercaptan
Methyl 1-propanethiol
sulfide
Carbon di sulfide
Isopropyl mercaptan
Ethyl methyl sulfide
Hydrogen sulfide
Carbonyl sulfide
Dimethyl sulfide
Chemical
Formula
CH3SH
CH3SCH2-CH2-CH2SH
CS2
(CH3)2CHSH
CH3SCH2CH3
H2S
COS
CH3SCH3
Scrubbed Gas
from DGA Scrubber
(ppm)
0.0050
0.0004
0
0
0
0.1460
0
0
Purified Gas
After Guard System
(ppm)
0.0032
0
0
0
0
0
0.0287
0
a
Adapted from Lee (1975)
-------
RESIDUE GAS
ABSORBER
INLET GAS
= SORJT REC
"C
YC
COMPR
H
p-= —
LE
C02 '
FUEL &
GAS H,S
1 A
[— i • n__L n3___L
H,P. iU LRLJ LTPTT—C
.FLASH FLASH FLASH^l
H2S&AIR
EATER
1
STRIPPER
AIR
SOLVEN T VENT
Figure 11. Salexol flow sheet for a gas containing large
amounts of both H2S and C02 (Maddox 1974).
Final Cleanup—
When gas must be treated by catalytic processes, even a few parts per million
of sulfur may constitute a serious poison for the catalyst. For conventional
methanation processes using nickel catalysts, catalyst life will be about 2
years when the gas contains 0.07 ppm sulfur; whereas a catalyst life of 5
years or more is expected for sulfur-free gas (Institute of Gas Technology
1972).
The Synthane process uses activated carbon for final sulfur cleanup (duplicate
vessels so that one vessel can be taken offstream for regeneration).
According to the Institute of Gas Technology (1972), activated carbon which
has been impregnated with certain metal oxides is used as a guard system to
obtain very low sulfur concentrations. Hydrogen sulfide, carbonyl sulfide,
carbon disulfide, thiophenes, and mercaptans are removed by the carbon
(Table 22) as are any oils remaining in the gas. When the capacity of the
bed is reached, the adsorber is removed from service and regenerated with
steam and air. Some elemental sulfur formed during regeneration accumulates
in the carbon pores, gradually deactivating the bed. After repeated adsorption-
regeneration cycles, the impregnated carbon must be replaced with fresh adsorbent.
If the Synthane carbon is regenerated, the available flow diagrams indicate that
regeneration steam and materials driven off the activated carbon are returned
to the Ben field regenerator tower, where they commingle with other condensate
from the regenerator and are sent to the decanter. At the Synthane Pilot
Plant, the flow diagram would indicate that the carbon drum stripping steam
and accompanying oil will indeed be routed to the Benfield absorbent re-
generator overhead flux stream. It would appear that these light oils would
not stay in the regenerator column, but would go with the acid gas stream to
the Stretford unit.
The above estimates indicate that the gas feed to the activated carbon reactor
will contain some light oil and some high molecular weight aromatic hydrocarbons.
These would be concentrated in the activated carbon. It seems doubtful that
the heavier material could be completely removed from the adsorbent.
57
-------
METHANATION
General Discussion
The sweetened coal-derived synthesis gas contains a large quantity of carbon
monoxide (low-Btu value) and hydrogen (low Btu/unit volume). In order for
this gas to be brought up to pipeline quality, the carbon monoxide and the
hydrogen contents must be reduced to low enough values to yield a product with
a heating value greater than 900 Btu/cf. (The gas industry specifies that
pipeline gas contain <0.1 vol % CO.)
To accomplish this objective all existing processes use the methanation
reaction, which occurs in the presence of a catalyst, and combines carbon
monoxide and hydrogen to produce methane and water:
rn + ?n high pressure rH , H n
C0 + 3H2 800° to 900°F! CH^ + H2U
The methanation reaction is highly exothermic, liberating as much as 10% of
the heating value of the total methane produced in the overall gasification
process (Institute of Gas Technology 1974).
If the reaction temperature is allowed to rise above 900°F (482°C), carbon
will be deposited from the breakdown of either the carbon monoxide or the
methane (Moeller et al. 1974). Further, temperatures above 900°F will
result in rapid catalyst deactivation.
The very large amount of heat released is a major problem in methanation.
This heat must be removed while the temperature is maintained between the limits
of 450°F (232°C) and 900°F (482°C) at all points in the system. The various
processes differ in the methods they use to handle this problem (Institute of
Gas Technology 1972).
Although the heats of reaction are not influenced greatly by temperature,
changes in free energy and equilibrium constants for methanation reactions
are quite sensitive to temperature. Thus, equilibrium methane yields are
reduced critically at high temperatures, requiring that catalyst beds be
operated at the lowest temperatures that are consistent with acceptable
catalyst activity (Huffstetler and Rickert 1976).
Pressure does not appreciably affect methane yield until the temperature
exceeds 942°F (506°C); above this temperature, increasing pressure tends to
decrease the minimum hydrogen:carbon monoxide ratio required to prevent carbon
deposition (Mills and Steffgen 1973).
Considerable research has been done on catalyst materials. Only five —
ruthenium, nickel, cobalt, iron, and molybdenum — have been identified as
having commercial importance (Strakey et al. 1975). Ruthenium is very active,
but because it is relatively rare, there is a question as to whether the ton-
nages required for large-scale commercial use would be available (Huffstetler
and Rickert 1976).
58
-------
Nickel is inexpensive, very active, and highly selective to methane; thus, it
is the catalyst of choice for most commercial operations. Cobalt is less active
and less selective than nickel; iron is less active than cobalt and catalyzes
carbon formation; molybdenum is of lower activity than iron, fairly selective,
but it has the advantage of being resistant to sulfur (Huffstetler and Rickert
1976).
Commercial nickel catalysts consist of 25-77 wt % nickel on a high-surface area,
refractory support such as kieselguhr or alumina. Raney nickel is also a
widely used catalyst. This catalyst is formed by the leaching of the aluminum
from an alloy, composed of 42 wt % nickel and 58 wt % aluminum, with sodium
hydroxide. The result is a spongy skeletal catalyst that is very active in
methanation (Huffstetler and Rickert 1976).
Catalyst deactivation, a severe problem in catalytic methanation, can occur
through any of several mechanisms (Strakey et al . 1975):
1. Ni + H2S — *- NiS + H2
2. Ni (75 A) — ^ Ni (1000 A)
3. 2CO — >• C + C02
>- C + 2H2
4. 3Ni + 2CO — > Ni3C + C02
3Ni + CH — )- Ni3C + 2H2
5. Ni + 4CO — > Ni(CO)4
6. Fe(CO)5 — v Fe + 5CO
Reaction 1, the poisoning of the catalyst by sulfur, is common to all metallic
catalysts except molybdenum. Strakey et al . (1975) tried to keep sulfur concen
tration below 0.1 ppm to avoid irreversible contamination.
The sintering effect is represented by reaction 2. It is generally known
that, at temperatures above 842°F (450°C), nickel crystallites grow in size
and a loss of surface area leads to reduced catalytic activity. Reaction 3
is the Boudouard reaction in which elemental carbon is formed by heterogeneous
decomposition of CO or CH^ during methane synthesis. Nickel carbide forms as
a result of reaction 4. This reaction deactivates the catalyst material,
but is reversible; treatment with hydrogen at >482°F (250°C) will reactivate
a nickel carbide-deactivated catalyst (Strakey et al . 1975). A potentially
serious reaction is the one that forms nickel carbonyl (reaction 5). Because
this reaction occurs only at low temperatures, it is avoided by contacting
the catalyst with synthesis gas at temperatures above 500°F (260°C) and
maintaining that temperature until all carbon monoxide has been purged
from the system (Huffstetler and Rickert 1976).
The final reaction, 6, is one that has its beginnings outside the reactor
vessel. Iron carbonyl can form when carbon monoxide reacts, at high pressure
and low temperature (212° to 392°F [100° to 200°C]), with carbon steel piping.
59
-------
The iron carbonyl is carried into the reactor, where it decomposes according to
reaction 6 and effectively deactivates the nickel catalyst by forming iron
deposits. Choosing less reactive piping material, such as stainless steel, will
prevent the reaction from occurring (Strakey et al. 1975).
Process Discussion
The tube wall reactor (TWR) methanator and the hot gas recyle (HGR) methanator,
both designed by the U.S. Bureau of Mines, are being tested at the Synthane
Pilot Plant. In most methanation systems, the heat of reaction is removed from
the reactor as sensible heat in the gas. The TWR (Figure 12) methanation system
involves removing the heat of reaction directly from the catalyst surface. An
alloy of nickel and aluminum is flame-sprayed on the inner surface of the tubes.
Treatment with caustic removes the aluminum, leaving a highly active Raney-
nickel catalytic surface. The fresh feed gas enters the reactor and reacts on
the catalytic surface of the tubes. The heat flows from the nickel surface
through the tube wall to boiling Dowtherm A on the shell side. The tempera-
ture on the inside tube wall is held at the desired level by controlling the
pressure at which Dowtherm is boiling.
FINAL
METHA NATGrt
ORY
SWEET GAS
METH. RECYCLE
COMPRESSOR
Ffjun 12. Tutu mil rttctor ntlumtton — Syntham Pilot PUnt.
60
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The HGR methanator (Figure 13) is a simpler system. Product gas is recycled
back to the inlet of the reactor to dilute the feed and to reduce the CO con-
centration so that a conversion of about 2% CO is obtained in the reactor. Thus,
with an inlet temperature of 572°F (300°C), the exit temperature does not exceed
750°F (400°C). These limits apply to the Raney nickel catalyst. Other catalysts
are claimed to operate at higher temperatures. In the original bench facility,
a feed gas containing about 23% CO with an H2:CO ratio slightly in excess
of 3:1 was used, for which the required recycle volume is 10 times the feed
volume (10:1). If all this recycle were returned hot so that no moisture
was removed, the steam concentration would approach 50%, which is undesirable
from an equilibrium standpoint and may cause catalyst oxidation. Therefore,
30% of the recyle stream is cooled to room temperature and water is condensed.
Thus, a 7:1 hot recycle ratio and a 3:1 cold recycle ratio are used (Strakey
et al. 1975).
Horc
UETHANATOR
ETIC
'iPsiiNj 3is
950 BTU/CF
ago ?si
HOT GAS
SSCTCL6 EOUCTOf!
OS COMPRESSOR
MSTH. 9ECYCLT
C3MPSUSOR
Flora 13. «« gai r«»el« mOiMitloo — imtkiM fil« n«t.
Of special interest is the low pressure drop through the HGR unit, which is
only 0.3% of that through a pelleted catalyst bed. This low pressure drop is
a result of applying the catalyst to flat plates that are arranged in parallel
and stacked in bundles in the HGR. Flame spraying or metallizing is used to
deposit the catalyst. For the HGR plates, Raney nickel alloy powder (80 to 200
mesh) is fed through a hydrogen-oxygen flame, where it partially melts and
solidifies on the surface of the flat plate. This process is normally used
to apply corrosion resistant coatings, for hard-facing soft metals with hard
coatings, and to build up worn journals. First, a bond coat, .006" thick,
containing 95% Ni and 5% Al, is applied to the stainless steel substrate to
improve adhesion, and then a coating of Raney nickel, .019" thick, is sprayed
onto the plate. The plate is then activated by caustic leaching and kept under
hydrogen until it contacts the SYNGAS at an elevated temperature (Strakey et al.
1975).
61
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After this first-stage methanation, the cold (107°F [42°C]) product gas is
heated to 600°F (316°C) and then passed through a final, or polishing, packed-
bed methanator. The final product gas is 89.6 vol % methane. This gas is
sampled and then burned in the thermal oxidizer (Institute of Gas Technology
1972; U.S. Bureau of Mines 1972).
Special Cases--
The Bituminous Coal Research, Inc., (BCR)-developed fluidized bed catalytic
methanation reactor is being tested at the Bi-Gas plant. As stated previously,
the fluidized bed offers far better heat-transfer capabilities than are pos-
sible with fixed-bed reactors. The BCR unit is designed with sufficient
internal cooling coils and heat-exchange capacity to control the exothermic
heat of methanation at higher levels of carbon monoxide concentrations in the
feed gas than is possible with fixed beds (Evans 1976c),
The C02 Acceptor uses the heat extraction method of methanation. Here, heat-
exchanger tubes are packed with a pelleted catalyst. Boiling Dowtherm on
the shell side of the exchanger removes the heat and the hot Dowtherm is used
to raise high-pressure steam (Strakey et al. 1975).
The original methanation system used at the HYGAS Pilot Plant was a combination
of the cold quenching and recycle systems. In this system, fresh feed is mixed
with recycle gas in order to (1) dilute the feed to maintain as low a temperature
as possible in the reactor and (2)act as a coolant for the gas stream itself.
In practice, a portion of the coal-feed gas is mixed with hot recycle gas and
then fed to the first catalyst bed. The hot gas from the first reactor is
mixed with recycle gas from the second reactor and/or more fresh sweet gas.
It is cooled further if necessary and reacted in a second catalyst bed. A
portion of the gas product is cooled and passed through a final catalyst bed
to insure maximum conversion. Gas temperatures vary from a 550°F (288°C) feed
temperature to 800°F (427°C) outlet temperature. In this way the overall re-
cycle ratio and pressure drop can be significantly reduced. More recently, a
carbon guard system for removal of sulfur compounds has been installed upstream
of the methanation unit (Evans 1976d).
In October of 1976, a skid-mounted liquid phase methanation process unit
developed by Chem Systems, Inc., was installed at the HYGAS plant. This unit
was to have been brought onstream in March of 1977. In this process, inert
liquid (either a paraffinic or aromatic oil —WITCO 40 mineral oil has been
used) is pumped upward through the reactor, which operates at 1000 psig and
570°F (300°C), at a velocity sufficient both to fluidize the catalyst and to
remove the reaction heat. At the same time, the sweet feed gas is passed up-
ward through the reactor, where it is converted to methane in the presence of
the fluidized nickel catalyst.(Calsicate Ni-2305 has been tested.) The heat
of the exothermic reaction is adsorbed by the inert liquid as sensible heat.
The liquid is then circulated through an external heat exchanger to maintain
the desired temperature, and the cooled inert liquid stream is recycled to
the reactor.
The product gas leaving the top of the reactor contains 95% to 99.5% methane,
depending on the pressure, temperature, and flow rate of the inlet gas. Other
components of the product gas are water vapor and vaporized inert liquid, along
62
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with minute quantities of ethane, propane, hydrogen, and carbon dioxide. Most
of the inert liquid condenses in the primary cooler; the remainder condenses in
the secondary cooler along with the water. The inert liquid and water are
separated; the inert liquid is recycled to the methanator and oily water is
sent to the incinerator. No recycle is required as the reaction is nearly
complete in one pass, and the product is high-Btu synthetic natural gas
(U.S. Energy Research and Development Administration 1976b).
Problems--
Each of the above described systems may develop its own operating problems of
plugged bed or lines, leaking valves, or leaking pumps. The leaks will re-
lease carbon monoxide, methane, and hydrogen into the workplace. However,
the frequency and severity of these leaks should be far less than in the
upstream portion of the plant.
The formation of nickel carbonyl is of concern. Again, as long as the proper
operating procedures are followed, few if any problems should develop. Operating
personnel at the HYGAS Pilot Plant state that they have been concerned about this
problem, but that they have seen no signs of catalyst deactivation, such as
reduction in gas quality out of the vessel or change in the temperature pattern
within the reactor bed. Catalyst deactivation would be the first sign of nickel
carbonyl formation (oral communication, November 9, 1976, with W. G. Baer,
HYGAS Pilot Plant, Institute of Gas Technology, I.T.T. Center, 3424 South State
Street, Chicago, Illinois 60616). It has been suggested that nickel carbonyl
formation could occur at the cold surfaces of the heat-transfer piping in the
fluid-bed, liquid phase methanation unit, depending upon the pipe surface
temperature. However, since nickel carbonyl does dissociate at the normal
methanation temperatures at which the fluid bed is operated, one would expect
the chances of escape of the nickel carbonyl from the reactor to be minimal.
In case of an operating problem in this or any gas purification system, the
product gas can be diverted directly to the thermal oxidizer until the problem
is eliminated.
ACID GAS TREATMENT
The acid gas from the Synthane Pilot Plant's hot carbonate regenerator
(Figure 14) contains carbon dioxide, hydrogen sulfide, and water, as shown in
Table 23. This acid gas may contain some light oil as already indicated.
The light oil should pass through the absorbers with the carbon dioxide and
other hydrocarbon gases. The composition of the desulfurized acid gas will
approximate that shown in Table 24. At Synthane, this desulfurized acid gas
may be thermally oxidized or recycled as inert gas in other parts of the
plant. The composite molten sulfur analysis from the Stretford unit will
approximate that shown in the second column of Table 24.
At the Bi-Gas Pilot Plant, a commercially available skid-mounted Claus unit
will be used to treat the acid gas. This unit will also produce a molten
sulfur, which can be pumped into a truck for disposal.
63
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Table 23. Acid gas feed compositions to sulfur removal unit.
Gas Components, mol %
Hydrogen
Carbon Monoxide
Carbon Dioxide
Methane
Ethane
Hydrogen Sulfide
Water
Nitrogen
Synthanea
Bituminous Coal
0.49
0.06
87.65
0.31
W°
1.59
9.90
ND
HYGAS
Run 37, Montana Lignite
3.57
0
93.24
1.71
0.12
0.10
ND
1.26
Based on process flow diagram calculations, not on pilot plant data
(U.S. Bureau of Mines 1972).
?Dry basis (Lee 1975).
'Ho data.
CO, COMPRESSOR
H.P. COj STOHAOE
TANK
ACIO 4AS F£EO
FROM aEN^ISLO
Of F SAS UNIT
I
COMPRESSOR
U. *CIJ jn pnaiilni — SyntlUM Mtgt Plint.
64
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Table 24. Synthane sulfur removal plant product.
a
Components, mol %
Hydrogen
Carbon Monoxide
Carbon Dioxide
Methane
Hydrogen Sulfide
Water
Sulfur
C02 Recycle and/or
Off-gas to Thermal
Oxidizer
0.51
0.06
91.76
0.32
(150 ppm)
7.35
ND
Sulfur to
Disposal
ND
ND
ND
ND
ND
2.1
97.9
a
Adapted from U.S. Bureau of Mines (1972).
Claus Process
The Claus process (Figure 15) is an essentially atmospheric pressure process
operating basically in the following manner.
AIR' IACIO
IOAS
a i«c
SECOND HOT GAS 9Y-"ASS
• FIRST HOT GAS BY-PASS
'HUB
V
^
«,
r—
c,
9 - 9UHNER R2 - SECOND CATALYTIC CONVeRTES
RC- REACTION CHAM3ER C, - FIRST CONDENSER.
WHS- WASTE HEAT BOILER C2 - SECOND CONDENSES
R, - FIRST CATALYTIC \ - LIQUID SULFUR
SUFFICIENT AIR IS ADDED TO BURN 1/3 Of TOTAL HjS TO S02 AND
ALL HYDROCARBON TO COj.
r*fv< 19. Cltu 'MO Otrwgft* >rguil 1«. tOiwi (P*4»« 1174).
65
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The acid gas, containing 15 to 90 mol % H2S (Beers 1973) is combined with
sufficient air to burn one-third of the total H2S to S02 and all of the
hydrocarbons to C02. (Alternatively, one-third of the total acid gas is
burned, then recombined with the unburned gas.) A part of the hot gas is
cooled and a portion bypasses the coolers so that the reactor temperatures
can be maintained. (Each reactor inlet temperature must be above the sulfur
dew point, preferably 450°F [232°C], to avoid condensation of the liquid
sulfur in the catalyst bed. Condensation could cause plugging and catalyst
deactivation. )
In the reactor the S02 and H2S react to form sulfur.
on Bauxite catalyst -
^HS + S0 -
700° to 750°F .
From the catalytic reactor the hot gases flow into the condenser, where they
are cooled to 300°F (149°C) and the liquid sulfur is removed. Sulfur must be
removed from the condenser in the 300°F range. (Because of a phase change at
320°F (160°C), the viscosity of liquid sulfur increases rapidly with increasing
temperature and could not be removed from the condenser.) Cooled gases can
then be recombined with a second hot gas bypass flow to balance temperatures
at the entrance of the second reactor inlet. Product gas should contain only
0.5% to 10% of the H2S fed into the unit (Maddox 1974). This composition is
acceptable in the pilot plant situation.
Claus reaction variations accommodate the various concentrations of acid gas
feeds, with the optimum Claus process depending primarily on the hydrogen
sulfide concentration in the feed (Dailey 1976).
Problems--
Hydrocarbon in the feed to the Claus unit causes an increase in undesirable
side reaction products. Following are some of the possible reactions
(Maddox 1974):
CH4 + S02 - > COS + H20 + H2
CO + S - > COS
Should this unit prove inoperable, the regenerator acid off-gas will be sent
to the thermal oxidizer.
Holmes-Stretford Process
The Holmes-Stretford process (Figure 16) is capable of operating on acid gases
containing only low concentrations of H2S.
66
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TREAT-JO _ MS'F
ACIO CAS
8. HolBM-Strecfort lulftir ncovtry — SynUiiiw IMlot Pl«nt.
In this process, the 120°F (49°C) acid gas is washed countercurrently by
sodium vanadate containing the sodium salt of anthraquinone disulfonic acid
(ADA) as an activator. The hydrogen sulfide in the acid gas reacts with the
vanadate to form sulfur.
4NaV03 + 2H2S
Na2V409 + 2S + 2NaOH + H20
The reduced vanadate is then oxidized by the ADA, which in turn is reoxidized
in the atmospheric air. This is done in an oxidizer vessel by air spraying.
The air also acts as a flotation agent in frothing out the fine grained sulfur
product. The slurry of solid sulfur is filtered; the filtrate is returned
to the process; and the sulfur is collected in a molten sulfur storage tank
(Maddox 1974; Institute of Gas Technology 1972; Vasan and Willett 1976).
There is a by-product conversion of H2S into thiosulfate. Through proper
design and the use of special additives this conversion into thiosulfate
can be kept down to the 1% to 2% level. Accumulated thiosulfate must be
purged.
UTILITIES
The coal gasification pilot plants require a substantial utility section
including facilities for:
• Water demoralization
• Water treating to boiler feed water specifications
• Potable water supply
67
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Steam production (with natural gas or oil fired boilers)
Water for fire fighting
Cooling water supply
Cooling water anticorrosion treatment
Cooling water towers
Air compression and drying (for instrument air supply)
Thermal oxidation
Wastewater ponds
Emergency power generation (diesel or propane generator supplying
sufficient power to permit the plant to shut down safely under
emergency conditions)
0 Compressed or liquid gas storage such as carbon dioxide, oxygen,
and/or nitrogen
• Inert gas generation and compression such as carbon dioxide
• Electrical power conversion and transmission to the plant workplace
These utilities are similar to those in most commercial facilities. In
general, these functions are generally located within or near to a single
building and are noisy.
OTHER FACILITIES
There are other operating facilities within the plant for maintenance,
instrumentation, and laboratory analysis. The maintenance force may be large
enough to cover all operating and maintenance requirements, or it may be only
large enough to cover maintenance problems in rotating equipment, such as
centrifugal and reciprocating pumps and compressors. At the HYGAS plant,
maintenance is concerned only with the rotating equipment. In this latter
case, regular inspection and cleaning of vessels are performed by the
operating crew, while major maintenance functions are contracted to commer-
cial firms. At the Synthane plant, all maintenance functions are carried
out by an outside contractor, while at the C02 Acceptor plant, all maintenance
is done by the plant maintenance force.
Analytical functions are relatively simple and may be confined to the definition
of major process components as required for plant operation. In general, facili-
ties other than gas chromatographs for routine gas or liquid analyses are not
available. Detailed analyses must be performed in an outside laboratory. In
some cases, the analysts also do the plant sampling during plant operations
(HYGAS). This crew is then exposed to emissions which may accompany the
sampling procedure from the entire workplace for most of the workday in
addition to say other hazards in the workplace.
68
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HEALTH EFFECTS
This chapter reviews the health effects that might ensue if workers were ex-
posed to the process stream and waste chemical hazards identified in the
process discussion of coal gasification and Appendix A; it also reviews
potential physical stresses. Its purpose is to support recommendations for
protection of workers and to provide a convenient source of information for
those responsible for the protection of workers' health. Description of an
effect does not imply that workers will necessarily be at risk in any
particular coal gasification pilot plant. Assessment of that risk requires
knowledge also of likelihood of exposure, and such knowledge is at present
incomplete.
TOXIC EFFECTS
"Toxic" here includes "carcinogenic," although the terms are often separated.
Chemical carcinogenesis can be regarded as "a very special aspect of an
adverse toxicologic reaction." (Weisburger 1975)
Sources of data include toxicologic experiments and epidemiologic studies.
Animals have been exposed in the toxicology laboratory, usually to single
substances or to simple mixtures and occasionally to complex coal products.
Epidemiologic studies have been performed on humans who have worked in coal
processing plants, but — in contrast to the laboratory — exposure there is
uncontrolled and difficult to estimate.
A special characteristic of coal gasification plants is that any occupational
exposures occurring therein are likely to be to complex mixtures of chemicals.
If the chemicals are similar in constitution and toxicologic mechanism, the
total effect might be simply additive, and it might then be calculable in the
same manner as is recommended by the American Conference of Governmental
Industrial Hygienists (1976) for the estimation of threshold limits for ex-
posure to such mixtures: If the sum of the fractions, (observed concentra-
tion)/(threshold limit), for each component is more than unity, the limit is
exceeded. Synergistic action (i.e., combined effect exceeding the sum of
individual effects) may occur and this is particularly significant with car-
cinogens. Other chemicals, not carcinogenic of themselves, can enhance the
potency of carcinogens or can promote tumor formation even long after appli-
cation of the carcinogen. Carcinogenic potency can also be decreased, as in
the application of weak carcinogens such as dibenz(ajg')fluorene and chrysene
together with strong carcinogens such as benzo[a]pyrene (BaP). Finally, if
components act independently, each can be considered as though the others
were not present. This is seen with some carcinogens and with other toxi-
cants; e.g., in concurrent exposure to an azo dye that induces liver tumors
and 4-dimethylaminostilbene, which affects the ear duct (Weisburger 1975).
69
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There are several practical consequences of exposure to complex multiagent
hazards. Complete chemical characterization of exposure hazards may be diffi
cult or impossible, and even if a full analysis were available, the total
effect would generally be unpredictable. It is clear also that the use of a
single component of exposure as an index of total exposure —e.g.,_BaP as an
index of total polycyclic aromatic hydrocarbons —must be viewed with
caution.
The first evidence of health effects presented here is from studies of coal
conversion workers and their environments; evidence is next presented for
similar working environments such as coke ovens. The remainder of the
evidence comes from observations on humans in quite different circumstances
or from animal experiments.
Evidence of Health Effects from Coal Conversion Plants
Large-scale plants for coal conversion were constructed in Germany in the
1920's, in Great Britain in the 1930's, and in South Africa in the 1950's;
pilot plant work began in the United States in the 1950's. The American ex-
perience provides the best available evidence of effects in man; it has been
reported principally in a series of reports that appeared in the Archives of
Environmental Health in 1960 (see below), relating to a pilot plant operated
from 1952 through the late 1960's.
Sexton (1960a) stated that it was known that the plant would generate a wide
range of chemicals, many of which could present acute or chronic toxic
hazards. Examples of the expected compounds were aliphatic hydrocarbons,
single-ring aromatics, polynuclear aromatics, phenols, aromatic amines, and
N-heterocyclic aromatics. Sexton also stated that most of the hazards did
not occasion great concern with the available controls in force but special
attention was given to the presence of "at least one high boiling polycyclic
aromatic chemical which is known to be carcinogenic." A toxicological in-
vestigation confirmed the cancer hazard (Weil and Condra 1960) and an indus-
trial hygiene investigation (Ketcham and Norton 1960), concentrating on
airborne material and skin contamination, established the etiology of skin
contamination and resulted in recommendations for its abatement.
The medical report stated that:
"In reporting the clinical effects in a group of 359 coal hydrogena-
tion workers who were examined regularly over a 5-year period, it
was found that the exposure of these men varied from several months
to 23 years, and all of the lesions of significance were discovered
in those workmen with less than 10 years' exposure. Those employees
with more than 10 years' exposure obtained much of this in small
experimental or laboratory-sized operations, and the exact extent
of their exposure is not known. Those with skin lesions probably
had much heavier exposures, although they were obtained over a
shorter period of time. During the 5-year examination period, 63
skin abnormalities were discovered in 51 of the men. Of the 60
lesions excised, 55 tumors were subjected to histological study by
local pathologists. Eleven of these lesions were diagnosed as skin
cancers by either clinicians or pathologists, but the pathologist
70
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who reviewed the sections at a later date believed that only five of
these were epitheliomas. The incidence of cancer in these men was
between 16 and 37 times that reported in the literature. There were
54 suspected precancerous lesions of the skin, and 42 of these were
verified as precursors of skin cancer by several pathologists."
Among the conclusions reached by these investigators were:
"3. Heavy exposures to coal hydrogenation materials, even those
of relatively short duration (less than 10 years) are
capable of producing cutaneous tumors — both precursors
and neoplasms.
"4. The incidence of skin cancer in workmen exposed to the
coal hydrogenation process in one plant is many times
greater than that of West Virginia or the United States
as a whole."
An association of coal hydrogenation with skin cancer was thus indicated,
and Weil and Condra (1960) suggested its cause. They found, in mouse skin
assays, that:
"The light and heavy oil products were mildly tumorigenic. The
light oil stream, boiling below 260°C, and its derivatives were
without tumorigenic action. The streams boiling at higher
temperatures, middle oil, light oil stream residue, pasting oil,
and pitch product, were all highly carcinogenic, the degree of
carcinogenicity increasing and the length of the median latent
periods decreasing as boilina points rose."
The results are summarized in Figure 17.
Heavy Oil Product
10 T.I. - 0 C.I.
Llokt Oil Product
27 T.I. - < C.I.
]
Stabilizer Overhead
15° to 100'C
0 T.I. - 0 C.I.
"Phenolic
Compounds"
Crude Nitrogen Bases
195° to 260"C
0 T.I. - 0 C.I.
Neutral Light Oil
116° to 260"C
0 T.I. - 0 C.I.
H1*15S-'8 8S*"*"
OT.I. -oc.i.
Figure 17. Products and their carcinogenic! ty sumarized.13
T.I. • Tuaor Index. Bice with tuners as a percentage
of total nice exposed after subtracting Bice
tkat dl<4 vtthovt tianr.
"tKII wd Con*-.. IMO.
C.I. • Cancer IndMi similarly
71
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In the industrial hygiene study (Ketcham and Norton 1960) benzo[a]pyrene was
used as a proxy for this group of chemicals because it was known as a potent
carcinogen and was present in all of the middle oil and heavy oil fractions.
Most of the air samples collected at the facility showed concentrations of
the same order as that of large-city air, a few micrograms per 100 m3.
Some, taken close to particular operations, showed several hundred micrograms,
or even over 1000 yg per 100 m3. There was, however, no opportunity to
establish any quantitative relationship with either observed skin contamina-
tion or skin cancer incidence.
No other reports of positive evidence of increased skin cancer incidence in
coal conversion plants have been found in the United States, nor has any
evidence for other specific effects been found. It is clear, however, that
this does not dispose of the hazards. A recent examination of a pilot plant
by ultraviolet light showed extensive surface contamination, which very
probably contained carcinogenic hydrocarbons (Bolton 1976).
T^P absence of reported lung cancer is similarly no cause for complacency.
For txcmp'ie, high airborne concentrations of BaP were reported in some circum-
stances as -Iready noted (Ketcham and Norton 1960), and the fact that only
skin cancer was observed may have been due to the long induction period for
lung cancer (Hueper 1952) and lack of adequate follow-up. In this connection,
a paper by Holmes et al. (1970) presents "evidence of an increased risk of
subsequent primary cancer in the respiratory and upper digestive tracts of
men who have had epithelioma of the scrotum " The same may be true of
skin cancer generally.
Evidence of Health Effects from Similar Plants
Gasworks, where coal is heated in retorts with the primary purpose of pro-
ducing flammable gas, or coke ovens, where the coke is the primary product,
have provided much more evidence of associated health effects than coal con-
version plants, and some of it is quantitative. It should be noted,
however, that this evidence does not imply comparable levels of hazard in
coal conversion. Gasworks and coking plants heat the coal with minimal con-
tainment. Conversion plants typically operate at high pressure as well as
high temperature, and therefore necessarily with good containment in normal
operating conditions. The nature of the toxic hazards and their amounts
within the various process streams are similar: the likelihood of exposure
is however less at conversion plants.
Producer gas plants have features in common with coke ovens and gasworks on
the one hand and with coal conversion on the other; and studies of producer
gas workers provided the first evidence of increased lung cancer incidence
(Kuroda and Kawahata 1936). Later evidence showed a mortality rate from
lung cancer 33 times that of control workers from the same steelworks
(Kawai et al. 1967).
In a British study (Doll et al. 1963) over 11,000 gasworkers and pensioners
were observed for an 8-year period and over 3,000 of them were followed for a
further 6 years as part of another study (Doll et al. 1972). In the
12-year period lung cancer deaths were higher by 140% and bladder cancer
deaths by 208% in men heavily exposed to the products of coal carbonization
72
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as compared with those exposed only to by-products. Analysis of gasworks
air (Lawther et al. 1965) showed a general level of about 3 yg per m3 of
benzo[a]pyrene (100 times that in typical London air) and over 200 yg per
m3 in the worst working area. The tarry particles were in the respirable
size range, mostly 1 y and below and therefore capable of penetrating the
deep lung, although not being completely retained. These reports clearly
established a relationship of illness with exposure at gasworks but did not
provide a quantitative dose-response relationship.
Coke oven studies provided similar evidence. Studies initiated in 1962 in
Allegheny County, Pennsylvania, (and later extended: Fannick et al. 1972)
were reported in 1970-1972 (Lloyd et al. 1970; Lloyd 1971; Redmond et al%
1972). These showed a strong association of excess deaths from respiratory
and urogenital neoplasia with both intensity of exposure and length of
employment. Tables 25 and 26 are extracted from this work and Table 27
shows the relative levels of exposure of topside workers and two categories
Table 25. Relative risk af death for selected cauut by coke mm subdivisions far
cot* ov«n «rkan (19SI-1966)."
Cause of death
All causes
Malignant neoplasms — lung, bronchus, and trachea
Malignant neoplasm — genitourinary system
Other malignant neoplasos
Tuberculosis of the respiratory systeai
Other diseases of the respiratory system
Cardiovascular renal diseases
Accidents
All other causes
Full topside
Relative risk
1.1Z
7.24
b
0.86
b
0.99
0.64
0.72
1.00
Partial topside
Relative rltk
1.07
2.14
b
0.44
b
1.78
1.18
0.94
0.76
Side 0'
Relative
0.92
1.73
2.02
0.79
1.06
1.01
0.80
1.19
o.as
ttn
risk
from th* work of Redmond et al. (1972).
"lt*s than 5 deaths observed.
Tablt 2*. MUt.v* risk of d*«tlt for lelected ciwses by length of e.*>.oy.*ent at
Mtry to ttwty for cokt own workers.*
Cause of death
All causes
Malignant neoplasms — lung, bronchus, and trachea
Hallqnant neoplasms — genitourinary organs
Other malignant neoplasms
Tuberculosis of the respiratory systea
Other diseases of the respiratory system
Cardiovascular renal diseases
Accidents
All other causes
5 years or more at
coke oven
Relative risk
l.OB
3.48
2.01
0.93
1.00
1.28
0.90
0.68
0.94
Less than 5 years at
coke oven
Relative rUk
0.83
1.70
b
0.40
b
0.88
0.79
1.12
0.77
"Adapted fro. the work of Redmond et al. (1972).
Lets than S deaths observed.
Table 27. Me. 'svel of coal tar pitch volatile* (mg/m3).c
Exposure group Average CTPV (mg/m3)
Topside
Side oven 1
Side oven 2
3.15
1.99
0.88
Adapted from the work of Mazumdar et al. (1975).
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of side oven workers (Mazumdar et al. 1975). Mazumdar et al. concluded that
the Threshold Limit Value (TLV) recommended by ACGIH, 0.2 mg/ro3 coal tar
pitch volatiles in total particulates, was acceptable because their analysis
indicated that exposure at this level for an average of 30 years did not
increase the risk of death from lung cancer.
The ACGIH TLV of 0.2 mg/m3 was first adopted in 1967 and it was subsequently
adopted as a Federal standard under the Occupational Safety and Health Act of
1970. The standard (29 CFR 1910) refers specifically to anthracene, BaP,
phenanthrene, acridine, chrysene, and pyrene, and a note on interpretation
says that "coal tar pitch volatiles include the fused polycyclic hydrocarbons
which volatilize from the distillation residues of coal, petroleum, wood, and
other organic matter."
The NIOSH criteria document for coke oven emissions (National Institute for
Occupational Safety and Health 1973a) remarked of the TLV and Federal
standard that "in the absence of information on a safe level, this environ-
mental standard can be considered only an index of worker exposure." NIOSH
also noted that the benzene soluble fraction of total particulates may be a
questionable index of health hazard because (1) irritants may enhance
carcinogenicity and (2) respiratory protection against gases may be needed.
In 1974 the U.S. Department of Labor (OSHA) established a Standards Advisory
Committee on Coke Oven Emissions. A proposed standard of 300 yg of respirable
particulate matter per cubic meter of air was published in 1965 and a new
standard for worker exposure to coke oven emissions was promulgated in 1976
(Federal Register 1976), which became effective on January 20, 1977. Ex-
posure is limited to 150 yg of benzene soluble fraction of total particulate
matter (BSFTPM) per cubic meter of air, averaged over an 8-hour period. OSHA
found the BSFTPM to be a "more specific measure of exposure to the carcino-
genic components of coke oven emissions than either respirable or total
particulate matter. The benzene soluble fraction of total particulate matter
sampling is less likely than sampling of other indicator substances to be
affected by interference from emissions present but not generated from the
destructive distillation of coal."
Other Evidence of Health Effects
Additional evidence of health effects is derived from observation of humans
in circumstances quite different from those at coal conversion plants or from
animal experiments. In comparison with the previous evidence, the available
data are abundant and generally much more precise, but they are necessarily
derived from conditions that are more remote, inferentially, from those of
direct concern. Most of the evidence is experimental and comes from con-
trolled exposures to single substances or to very simple combinations of
substances.
The evidence is presented very briefly in relation to individual chemicals
or closely related groups of chemicals selected from the process stream com-
ponents and possible emissions described in the process discussion of coal
gasification and listed in Appendix A. The selection was based on potential
hazards as indicated by specific toxicity and estimated probability of worker
exposure in normal operations and maintenance.
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The chemicals are arranged alphabetically. Some are treated individually,
while others are treated as groups which are similar in toxic effects and
chemical properties. To help in locating information, a list is provided
below.
Aliphatic hydrocarbons
Ammonia
Aromatic amines
Aromatic hydrocarbons — see also Polycyclic aromatic hydrocarbons
Arsine — see under Trace elements, Arsenic
Carbon disulfide
Carbon monoxide
Carbonyl sulfide
Heterocyclic aromatics
Hydrogen chloride
Hydrogen cyanide
Hydrogen sulfide
Mineral dust and ash — see also Trace elements
Nickel carbonyl
Nitrogen oxides
Nitrosamines
Phenols
Polycyclic aromatic hydrocarbons
Sulfur oxides
Trace elements
The information is presented on the basis of relevance to other chapters of
this report:
• Toxic effects are of interest to those involved with medical
monitoring. The emphasis is on chronic exposure and the organs
affected: i.e., "what to look for."
• Occupational (OSHA) standards or other indicators of "safe" levels
of exposure are useful in selecting workplace monitoring require-
ments and controls.
• Physical properties— physical state at ambient temperatures and
boiling point if normally liquid or solid — determine the type
of exposure and consequent requirements for personal protective
equipment. They also affect workplace monitoring and engineering
control requirements.
Aliphatic Hydrocarbons--
This group in general is unlikely to present a significant hazard at coal
gasification plants because any probable exposure will be to gas or vapor at
concentrations far below toxic levels. There is one notable exception:
dodecane, a liquid boiling at 421°F (216°C). It is not highly toxic but it
is a remarkable potentiator of skin tumorigenes is by BaP, lowering the
threshold dose in experiments by Bingham and Falk (1969) by a factor of 10\
and it is a known product of low-temperature coal conversion. It accordingly
has a special status as a target for investigation and as a signal for protective
action. It presents a suspected but unproven inhalation hazard as a carcinogen,
as well as the proven contact hazard.
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Ammonia--
This gas is very soluble in water. It is so intensely irritating that an
acutely toxic dose cannot voluntarily be inhaled. There is no evidence of
ill effects from prolonged workplace exposure at tolerable concentrations.
The OSHA standard is a time-weighted average (TWA) concentration of 50 ppm.
NIOSH has recommended a 50 ppm/5 min ceiling limit.
Aromatic Amines--
These liquids or solids have moderate to high boiling points. Aniline and
other substituted benzenes are highly toxic, causing methemoglobinemia,
central nervous system effects, liver damage, and skin sensitization. The
fused two-ring g-napththylamine and the biphenyl benzidene are potent car-
cinogens, especially the former which has been shown to be associated with
excess bladder cancer in gasworkers (Doll et al. 1965).
The OSHA standard for aniline and similar compounds (toluidine, xylidine) is
a time-weighted average concentration limit of 5 ppm; e-naphthylamine and benzi-
dine are regulated by engineering controls and work practices, not by exposure
limits.
Aromatic Hydrocarbons (other than polycyclics)--
These are liquids and solids of moderate to high boiling point. Vapor hazards
are likely only with benzene and related compounds of relatively low molecular
weight. Narcosis is seen in acute exposure, but only at concentrations of a
few thousand ppm (i.e., more than 0.1% by volume) and hence it is unlikely to
occur. Benzene presents a unique and serious hazard. It has been known for
some time that it is toxic to the blood-forming components of bone marrow
(Gerarde 1960). A review (National Institute for Occupational Safety and
Health 1976a) of recent epidemiologic studies compiled substantial new
evidence that benzene is a carcinogen with a capacity to cause leukemia in
exposed workers. It is now less certain that, as once believed, its myelo-
toxic effect is immediately arrested on cessation of exposure.
The OSHA standard for benzene is a 10 ppm TWA concentration limit, with a
25-ppm ceiling concentration limit. Because of evidence discussed, NIOSH has
recommended (ibid), and OSHA has proposed, a ceiling limit of 1 ppm (3.2 mg/m3);
this is the lowest level at which a reliable measurement is now practical.
The OSHA standard for toluene is 200 ppm (NIOSH-recommended standard = 100 ppm);
for xylene and styrene it is 100 ppm. Reported bone marrow damage by toluene
is believed to be due to benzene impurity (NIOSH 1976a).
Carbon Disulfide--
This is a liquid that boils at 46°C. It induces acute effects in the central
nervous system at about 300 ppm and is considered immediately dangerous to
life at about 3000 ppm; in the open, these levels would require a large leak
from a stream rich in CS2. Chronic poisoning is a more serious hazard. Ef-
fects have been most freqently reported in the central nervous system but
there are indications of a range of target organs. A study of workers ex-
posed to carbon disulfide plus about 10% hydrogen sulfide at 10 to 40 ppm
showed increased incidences of coronary heart disease and hypertension
(Hernberg et al. 1970).
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The OSHA standard is a 20 ppm TWA concentration limit, a 30-ppm ceiling limit,
and a 100 ppm/30 min limit for a single peak. The NIOSH-recommended standard
is a 1-ppm TWA limit, 10 ppm/15 min ceiling limit.
Carbon Monoxide--
This gas is a chemical asphyxiant causing acute symptoms rapidly at 1000 ppm
and above and in 1 hour at about 500 ppm. The symptoms are generally those of
hypoxia. The intoxication is reversible but hypoxemia sufficient to cause
unconsciousness may leave permanent damage. Susceptibility varies considerably,
being increased by any condition predisposing to cellular hypoxia, especially
of the central nervous system. The hazards of chronic low-level exposure are
not to be ignored. In particular there is some indication of cardiovascular
effects (U.S. Department of Health, Education and Welfare 1972).
The OSHA standard is a TWA limit of 50 ppm; NIOSH has recommended a 35-ppm
time-weighted average limit and a 200-ppm ceiling limit.
Carbonyl Sulfide--
This gas is a slight irritant; it exerts its principal effects on the central
nervous system. It is likely to be found in association with carbon disulfide
and hydrogen sulfide and it is toxicologically similar to them. There is
little evidence about its human toxicity but it probably is less hazardous
than hydrogen sulfide. (The inhalation concentration for lethality in mice is
much higher.)
There is no occupational standard for this chemical.
Heterocyclic Aromatics--
These are liquids and solids of moderate to high boiling point. N-heterocyclic
compounds are the ones of main interest. The one-ring pyridine and its deriva-
tives are generally irritant and narcotic, and hepatorenal injury has been re-
ported. Their significance as hazards in coal gasification is uncertain; it
may be as irritant potentiators of carcinogenesis rather than as direct toxi-
cants. The multi-ring N-heterocyclics, and especially the acridines, present
a more conspicuous hazard. They are strong irritants of skin and mucous
membranes and have a special significance in coal tar as proven agents of
irritancy and photosensitization. During estimation of the carcinogenic and
other hazards of coal carbonization products, the acridines must be taken into
account as potentiators. There also are indications of mutagenic and other
effects associated with the 0-heterocyclic (e.g., dibenzofuran) and
S-heterocyclic (e.g., dibenzothiophene) compounds which are known to occur in
coal conversion process streams.
The OSHA standard for pyridine is a TWA limit of 5 ppm; there is no standard
for acridine.
Hydrogen Chloride--
This gas is very soluble in water. It is an intense irritant, apparently
without irreversible effect at tolerable concentrations.
The OSHA standard is a 5-ppm ceiling limit.
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Hydrogen Cyanide--
This Is found as a liquid or gas (boiling point 26°C). It acts as a chemical
asphyxiant by inhibiting a cellular respiratory enzyme. Possible acute ef-
fects include immediate death at 270 ppm and death after 10 minutes at 181
ppm. Exposure at 18 to 36 ppm is said to cause slight symptoms after several
hours (Patty 1962). Chronic effects are those of moderate hypoxia, including
symptoms such as weakness, vertigo, nausea, rapid pulse, headache, flushing
of the face, and gastric distress. Also, skin penetration by the vapor can
be dangerous.
The OSHA standard is a 10-ppm TWA limit. The NIOSH-recornmended standard is a
5 ppm/10 min ceiling limit.
Hydrogen Sulfide—
This gas is a dangerous acute poison at concentrations of about 400 ppm and up;
it therefore calls for emergency protection where such concentrations might
occur, such as in the immediate vicinity of H2S-rich process streams. It
affects the nervous system and induces respiratory failure. The warning odor
is soon ignored because of olfactory fatigue and collapse may be sudden.
Chronic low-level exposure may induce various symptoms of malaise. The gas is
a strong irritant of the eye and respiratory tract at about 100 ppm and above,
and a slight irritant at 10 ppm. There appears to be no clear evidence of
chronic injury from it or of its potentiation of other toxicants. (Methyl
mercaptan and other thiols might be encountered. Their toxicology is generally
similar to that of hydrogen sulfide.)
The OSHA standard is a 20-ppm ceiling limit, 50 ppm/10 min peak limit. NIOSH
has recommended a 10 ppm/10 min ceiling limit and continuous monitoring in areas
where a concentration of 50 ppm (70 mg/m3) may occur, requiring evacuation
(NIOSH 1977b).
Mineral Dust or Ash--
Processes such as coal preparation and the discharge of ash from furnaces
release particles which, if airborne in sufficient concentration, enter the
hazard spectrum in several ways. Silica and limestone dusts may be encoun-
tered in the Bi-Gas and C02 Acceptor processes and might cause pneumoconiosis.
Coal dust presents a similar hazard that may or may not be dependent on a high
content of free silica (Casarett and Doull 1975). However, the induction of
pneumoconiosis seems unlikely at coal conversion plants. The exposures are of
less intensity than those in the occupations where such effects are seen.
Doll et al. (1965), for example, reported that pneumoconiosis was not relata-
ble to coal carbonization in their study. Action as an irritant of the lung
(fine particles) or skin (coarse particles) and hence as a promoter for
carcinogens and other toxic agents is more likely. The aspect calling for
most attention is action as a vehicle for toxicants. Polycyclic aromatic
hydrocarbons in the air are preferentially carried on smaller particles
(National Air Pollution Control Administration 1969); their respiratory
potency as carcinogens is enhanced by adsorption on certain materials (e.g.,
iron oxide: Saffiotti et al. 1964); and other toxicants may be intensified
in effect when associated with particles (e.g., sulfur dioxide: Amdur 1957;
Amdur and Underhill 1968).
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Nickel Carbonyl--
This is a liquid with a boiling point of 43°C. Metal carbonyls are generally
toxic, nickel carbonyl being regarded as the most hazardous. Inhalation of
the vapor affects the central nervous system and may induce acute chemical
pneumonitis. Brief exposure at 0.15 ppm is reported to induce transient
headache (1975 communication to Threshold Limit Committee, AC6IH by Morgan).
It has long been considered a carcinogen and the ACGIH recommended a TLV of
0.001 ppm. This view has been challenged however (e.g., Doll et al. 1970)
and the 1976 recommended TLV is 0.05 ppm. However, the NIOSH recommendation
to OSHA is that it continue to be considered a suspected carcinogen with an
exposure limit of 0.001 ppm (1 ppb) (NIOSH 1977c).
The OSHA standard is a TWA of 7 yg/m3.
Nitrogen Oxides--
Of these gases, nitrogen dioxide is generally the most conspicuous hazard. It
is an irritant of insidious effect because it can penetrate the lung deeply
without immediate severe discomfort and induce a delayed pulmonary edema,
which may be fatal. However, nitrogen oxides are likely to be produced only
if there is high-temperature combustion (steam plant or combustion of wastes)
and even then only in low concentrations. A possible, but unproven, hazard is
in association with carcinogenesis. There is an indication of lung tumor by
nitrogen oxides in susceptible mice. A further possibility is reaction of
nitrogen oxides with vapor from glycolamine scrubbers or other amines,
forming carcinogenic nitrosamines (see below).
The OSHA standard for nitrogen dioxide is a TWA limit of 5 ppm. NIOSH recommends
a 1-ppm ceiling limit.
Nitrosamines--
The simplest members of this group —e.g., dimethylnitrosamine and diethyl-
nitrosamine — are liquids with boiling points in the range of 150° to 200°C
and can exist at significant vapor concentrations. They are exceptionally
potent carcinogens, and although their presence has not been demonstrated at
coal conversion plants, it has been hypothesized that nitrogen oxides from
combustion processes might react with vapors from glycolamine scrubber-s or
with other amines. Dimethylnitrosamine was identified as a mutagen by
Legator (1974).
Phenols--
These may be either solids or liquid mixtures of moderate to high boiling
point. Phenol and related aromatic hydroxy compounds can be absorbed through
the skin and some (e.g., phenol) are sufficiently volatile to be possible
respiratory hazards; others (cresols) are less volatile and present an un-
likely vapor hazard. Their toxic effect is primarily on the central nervous
system and they are also strong irritants. It is the latter property which
is likely to be the more significant in coal conversion plants, in the en-
hancement of carcinogenicity through the presence of phenols in skin contami-
nation by tars or oils or in inhaled particles. Tye and Stemmer (1967) ex-
posed mice to coal tar aerosols by inhalation; with phenols removed, the tar
was less carcinogenic.
The OSHA standard is a TWA limit of 5 ppm. NIOSH has recommended a 20 mg/m3
TWA limit and a 60 mg/m3/15-min ceiling limit.
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Polycyclic Aromatic Hydrocarbons--
Examples are benz[a]anthracene, benzo[a]pyrene, dibenz[a.,ft]anthracene,
dibenzo[Zp,,
-------
A positive correlation was obtained between carcinogenicity and mutagenicity of
dibenz[a.,fr]anthracene metabolized with rat liver homogenate and tested against
a Salmonella typhimurium mutant (Teranishi et al. 1975).
OSHA has prescribed no "safe" exposure limits for these proven carcinogens.
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Sulfur Oxides--
These gases or aerosols may be present in significant amounts if fossil fuels or
sulfur-containing wastes are burned at or near the plant. Sulfur dioxide is an
irritant, affecting chiefly the upper respiratory tract. Its significance at
coal conversion plants is as a possible cocarcinogen (Laskin et al. 1970).
This may be due to its irritancy, in which case the sulfuric acid and sulfates
which may be found in combustion products or formed by oxidation of sulfur di-
oxide are also potential hazards, being generally more intense respiratory ir-
ritants than S02. Their irritancy may be intensified, moreover, by the presence
of other particulate matter.
The OSHA standard for sulfur dioxide is a TWA limit of 5 ppm. NIOSH has
recommended a 0.5-ppm TWA limit.
Trace Elements--
It does not appear that any trace elements in dust, ash, etc., will be significant
hazards in the general atmosphere at gasification plants because of their probably
low concentrations, but they require consideration in relation to operations such
as the cleaning of filters, quench water ponds, and furnace stacks, and maintenance
work in the top of gasifiers, etc. An example of this is quoted later, under
"Vanadium." A great difficulty in evaluating hazards is that toxicity is heavily
dependent on chemical state and occasionally also on physical state. Elementary
analysis is of little value in predicting hazards, which may range from severe
in one chemical state to negligible in another. Notes are presented here on some
minor constitutents of coal that may be encountered in ash, flue dust, etc.
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Arsenic (inorganic)--Effects of chronic exposure include anemia, gastric dis-
turbance, renal symptoms, and ulceration. It is a suspected carcinogen. The
OSHA standard is a TWA limit of 500 yg/m3. NIOSH has recommended a 2 yg/m3/
15-min ceiling limit.
Arsine might be encountered. Chronic exposure to arsine produces effects simi-
lar to those of arsenic dusts and fumes. The OSHA standard is a TWA limit of
0.05 ppm.
Beryllium--0verexposure to this metal induces a characteristic syndrome in which
respiratory symptoms are conspicuous among others involving the lymphatic system,
liver, spleen, and kidney (Eisenbud et al. 1949). Beryllium is a proven car-
cinogen in animals. The OSHA standard is a TWA limit of 2 yg/m3, and a 25 mg/m3/
30-min ceiling limit. The NIOSH-recommended standard is the same.
Cadmium—Chronic exposure to cadmium is associated with a variety of effects,
among which are emphysema and renal Injury (proteinuria). Cadmium has been found
in serum samples around the industrial steel complex in Birmingham, Alabama, and
the serum cadmium values showed a significant association with cardiovascular
disease (Peakcock 1970). It is a suspected carcinogen in animals (NIOSH 1976b).
The OSHA standard is a TWA limit of 200 yg/m3, and a 600 yg/m3 ceiling limit.
The NIOSH-recommended limits are a TWA concentration of 40 yg/m3 and a 200 yg/m3/
15-min ceiling.
Lead (inorganic)--Characteristic signs of chronic lead poisoning include blue
gums, weakness, anemia, neurological symptoms, and gastrointestinal dysfunctions.
Urine/blood monitoring is required. The condition has been discussed in detail
by Kehoe, e.g., Kehoe 1959; Kehoe 1962. Some lead components are carcinogens
in animals. There is evidence of teratogenicity in the hamster (Perm and Carpenter
1967) but specific evidence in humans has not been found (Scanlon 1975); feto-
toxic effects have been observed (Cantarow and Trumper 1944). The OSHA standard
is a TWA limit of 200 yg/m3. The NIOSH-recommended limit is 100 yg/m3.
Manganese—Chronic exposure induces a wide range of ill effects. Respiratory
dysfunction is characteristic and a correlation of industrial manganese exposure
with respiratory function was recently shown by Nogawa et al. (1973). Manganese
salts have been reported to be mutagenic: e.g., intraperitoneal manganic sulfate
caused cytogenic changes in the blood cells of rats (Markaryan et al. 1966). The
OSHA standard is a 5 mg/m3 ceiling limit.
Mercury (inorganic)--Among the more characteristic consequences of chronic ex-
posure to inorganic mercury compounds are tremors, psychic disturbances, renal
damage, and cardiovascular disease. Fetal effects have been observed in some
instances in humans and animals (Alonso and DeAlvarez 1960; Gale and Perm 1971).
The OSHA standard is a ceiling limit of 100 yg/m3. The NIOSH-recommended limit
is a TWA concentration of 50 yg/m3.
Selenium—Chronic exposure induces gastrointestinal disturbance, nervous symptoms,
liver and spleen damage, and anemia. The characteristic garlicky breath, fre-
quently reported, may not be apparent if tellurium is absent. Selenium is a pos-
sible carcinogen. The OSHA standard is a ceiling limit of 200 yg/m3.
Vanadium—Exposure to vanadium induces acute and chronic respiratory dysfunction
and there are several reports that this has occurred in maintenance workers engaged
in cleaning fossil fuel plants, e.g., Fear and Tyrer 1958. The OSHA standard for
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vanadium fume is a ceiling limit of 100 ug/m3 and for vanadium dust a ceiling
limit of 500 ug/m3. The NIOSH-recommended limit (1977e) for total vanadium is
a ceiling limit of 500 yg (V)/m3; for metallic compounds and alloys, it is a
TWA limit of 1 mg (V)/m3.
Discussion
The purpose of studying toxic effects is to develop and support recommendations
for acceptable exposure limits, monitoring procedures, and other protective
measures. The usual basis for such recommendations is quantitative expressions
of the relation between level of exposure and degree of resultant health effect.
These dose-response relationships permit the setting of rational limits for
acceptable exposure. This approach will not serve in the present case. A partial
solution, recommended in a later chapter, is to use the index that has been adopted
for coke oven emissions (Federal Register 1976a), namely, the benzene soluble
fraction of total particulate matter (BSFTPM). Use of the coke oven emissions
exposure limit also is recommended: 150 yg/m3 BSFTPM. This has the merit of
having been derived from epidemiological evidence but it is to be noted that
(1) it assumes similarity between workplace conditions at coke ovens and coal
gasification plants and (2) Land's analysis (Federal Register 1976d) did not
demonstrate that the coke oven exposure limit provides a safe exposure.
No complete solution to the problem can be seen at present. There are two reasons
for this: the complexity of the multifactorial toxic hazard and the uncertainty
about safe limits for exposure to carcinogens.
The multifactorial hazard presents a very difficult problem because of the
spectrum of possible effects. Respiratory exposure to the range of known toxi-
cants in the coal gasification process streams is potentially carcinogenic in
various parts of the respiratory, alimentary, and excretory systems, and toxic
to the lung, central nervous system, liver, and bone marrow, to name only the
more conspicuous hazards. Furthermore, a number of agents may pose the same
threat, a notable example being those polycyclic aromatic hydrocarbons which are
carcinogens. If one were dealing with a set of closely similar toxicants, a
simple additive effect might be reasonably hypothesized and even validated in
animal models, provided that there were dose-response relationships known for
each toxicant. We do not in fact have the dose-response data in many cases and
we know that the simple additive concept does not apply to many agent interactions.
Consequently, it is not possible to estimate quantitative health effects from
chemical analysis — even if routine full analysis were practical — or to define
an acceptable atmosphere in chemical terms. Nor is it possible to overcome the
difficulty of translating chemistry into biology by using a direct biological
test, the problems here being the assessment of the long-term effects of chronic
low-level exposure and the modeling of multifactorial interactions. Some
acute effects might be monitored by whole animal or cellular level exposure, but
this is clearly useful only for immediate protective action in a similar way to
the canary-in-coal-mine method. Rapid tests for mutagenicity might establish
the presence of a carcinogenic hazard but the prospect of their serving as a
quantitative model of human response to multiagent exposure is uncertain.
These problems in multifactorial exposure and the controversial issue of safe
exposure to carcinogens would seem to dispel any reasonable hope that acceptable
exposures can be defined in a manner similar to occupational standards for
single toxicants in the near future. It is possible, however, to recommend
environmental monitoring, work practices, and protective equipment to minimize
exposure.
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The greatest toxic hazards in coal conversion are presented by the known and
suspected carcinogens, because they are hazardous at low levels of exposure,
have delayed action with no immediate warning, and have grave consequences.
As for routes of entry, it is to be noted that carcinogenicity is shown by
various solids and liquids which may reach the body by inhalation of particles,
deposition of particles, or indirectly by contact with dirty surfaces. There
are also unproven possibilities of cancer induction by vapor inhalation. Other
toxicants are most likely to enter the body by inhalation.
HEAT EFFECTS
Metabolic heat load is determined by conduction and convection currents,
radiant heat transfer, and degree of evaporation as well as by the level of
worker activity. Responses to increased heat load include cardiovascular
strain, fatigue, and depressed psychological performance. If the heat load
is excessive or prolonged, frank heat disorders, including heat stroke, ex-
haustion, and cramps, may occur. It is not expected that heat stress will be
a problem in coal gasification plants since most work areas are located out
of doors and employees do not have to work in close proximity to the hot re-
actors. Only during maintenance operations when workers will be required to
enter reactors or to repair hot hardware is it expected that problems may
occur. Proper work practices and engineering controls are necessary to assure
that no undue heat burden is imposed on the employees.
NOISE EFFECTS
The primary adverse health effect of industrial exposure to noise is hearing
loss. The pathological event — destruction of the organ of Corti — is
clinically manifested as either a temporary or permanent hearing loss, primarily
at frequencies above 2000 Hz. Nonauditory noise effects include imbalance and
ear pain. High noise levels in coal gasification plants may be found in coal
preparation areas, around large compressors, and in utility rooms. Exposures
are generally of short duration and are likely to be below the OSHA standard
of 90 dba TWA (8 hours).
CONCLUSIONS
1. The overall carcinogenic hazard cannot be precisely estimated from chemical
analysis alone, because the possible interactions are far too complex.
2. Further, the hazard cannot at present be quantitatively defined by available
biological tests.
3. The same limitations probably apply to toxic effects other than carcinogenesis,
with the possible exception of some immediate responses (e.g., chemical
asphyxia, primary respiratory irritation).
4. It is not practical to recommend comprehensive workplace exposure limits
on a basis similar to those for individual toxicants; however, a limit for
one important kind of hazard (high-boiling suspected carcinogens) can be
recommended.
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5. The carcinogenic hazards associated with airborne particles and surface
contamination are the most crucial of the whole spectrum and offer a
practical target for control, if not for quantitative evaluation.
6. The only direct quantitative evidence now available is from epidemiology
in analogous circumstances and there are severe limitations on the compre-
hensiveness and reliability of such evidence.
7. Some specific targets for control through industrial hygiene practices can
be identified.
8. The presence of any strong irritant of the respiratory mucosa, other mucous
surfaces, and the skin should be regarded as a danger signal because of pos-
sible potentiation of carcinogens and other toxicants.
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EMPLOYEE HEALTH PROTECTION PROGRAM
The purpose of this chapter is to assist existing or future coal gasification
pilot plants in developing worker protection strategies that will minimize the
potential for acute or chronic illness. Before evaluating what additional
controls are necessary, it is desirable to describe the nature of existing pilot
plant programs. The current effort is directed almost exclusively toward fire
prevention, assurance of safety, and avoidance of gross exposures such as acute
carbon monoxide poisoning. This chapter in no way suggests that the effort in
these areas be diminished. On the contrary, they are critically important,
However, very little attention has been given to evaluating the potential haz-
ards of long-term chronic exposures, particularly those resulting from low air-
borne concentrations of carcinogenic compounds and coal-derived surface con-
tamination. This sparsity of attention is evidenced by the absence of employee
exposure data developed through periodic workplace monitoring.
Without monitoring data to determine the extent and source of potential worker
exposures, it is difficult to evaluate program requirements specific to the
necessities of each individual pilot plant. Therefore, the recommendations
contained in this chapter should be considered a base into which modifications
and improvements can be incorporated as the nature of the potential exposures
becomes better understood.
Each facet of the employee health protection program is very important to the
overall goal of maximizing worker protection. However, because of the nature
of the gasification processes and the extent of existing programs, several items
deserve special emphasis. The development of effective engineering controls
and work practices is imperative now, while the coal gasification industry is
still in the pilot stage. If this development is postponed until the industry
has proliferated into the commercial stage, the costs in time, dollars, and
general effort for retrofit will be an extreme financial burden, and a vastly
increased number of workers will be needlessly exposed.
The personal hygiene procedures are critical to the success of the program and
should be implemented as soon as possible, without regard to the results of
the monitoring program. Efforts to reduce or eliminate skin contamination with
coal-derived materials must be coordinated with a comprehensive health educa-
tion program for all workers.
An effective air sampling program is essential to provide necessary information
on potential exposure to airborne toxicants and to set engineering and work
practice controls.
ENGINEERING CONTROLS AND WORK PRACTICES
Existing coal gasification pilot plants are essentially closed processes with
few continual sources of air or surface contamination. In addition, the processes
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are frequently down for extensive maintenance and/or system modification during
which potential exposure sources are different. Therefore it is convenient to
discuss emission sources and suggested engineering controls in terms of the
process operating condition (i.e., process down, start-up, onstream operation,
and scheduled or emergency shutdown).
Process Down
When the process is down, there are no continual sources of emissions into the
workplace; rather, potential exposures will result from maintenance, repair or
modification operations that require workers to open process lines or to enter
vessels that could contain residual gases or vapors and surface contaminants.
Vessel and Confined Space Entry--
Coal gasification facilities contain large numbers of tanks and vessels
(reactor vessels, holding tanks, surge tanks, etc.) of various sizes and ge-
ometries. In addition, relatively confined spaces (baghouses, storage bins,
and pits) are common. Entry to such areas can pose serious health hazards to
employees.
Confined spaces are conveniently defined as any enclosed areas not subject to
continuous ventilation or changes in atmosphere by natural air movements
adequate to maintain oxygen concentrations at safe levels or to prevent
formation of explosive or toxic atmospheres.
Health and safety hazards may arise from several conditions within the vessels
or confined spaces:
• Inert atmospheres: Oxygen concentrations well below 19% can be expected to
be found in all gasification process vessels. Confined areas such as bag-
houses may be designed to operate with reduced oxygen levels. Areas where
02 concentrations are below 19% should be considered hazardous areas.
t Toxic gases and liquids: The gas stream will contain a multitude of gas
and liquid components that are toxic. These components are to be expected
in all gas stream vessels and lines.
• Explosive atmospheres: Enclosed areas exposed to gas stream components may
contain gases or vapors from highly volatile liquids capable of forming ex-
plosive mixtures with air. Similarly, in coal preparation areas explosive
concentrations of coal dust may be present in enclosed spaces.
t Surface contamination: Vessel surfaces exposed to gas stream components will
be contaminated, in some cases, by condensed coal gasification products
containing carcinogenic material.
The purpose of a safe work permit is to protect the employee from these hazards
during normal and emergency situations.
The safe work permit for vessel or confined space entry (Figure 19) is the
mechanism by which a "health hazard and work procedure" evaluation is performed
for every task requiring personnel to operate in confined areas.
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GOOD FOR ONE CREW ONLY ON THIS DATE
UNIT EQUIPMENT LEVEL
DESCRIPTION OF JOB IN DETAIL: LIST WORKMEN
CRAFT
SPECIAL SAFETY INSTRUCTIONS:
BADGE NO.
CONFINED SPACE ENTRY HOT WORK
1. Explosimeter test result % % %
2. Oxygen deficiency test result % % %
3. Drager test for:
4. Draqer test results were PPM PPM PPM
MgM3 MgM3 MgM3
5. Removed combustibles 35 feet from work site
6. Firewatch posted Standby posted
7. Area wet down BC extinguisher issued
8. Check type of ignition source - Burned fuel 1 I Elec welding a Torch CZ]
Electrical equipment O Drill or saw (hand or air) i i Lead pot(hot) CH
Air hammer or gun CD Soldering gun CH Jack hammer CD
Grinder (portable) a Equipment entry a Other C3
9. Removed residual material, cleaned, flushed, and purged
10. Nuclear devices, main switch, and local switch locked out
11. DANGER tag placed on nuclear devices and main switch
12. CAUTION tag placed on nuclear devices and main switch
13. Main switch, local switch tested to assure lockout
14. .Explosimeter, oxygen deficiency, and toxicity testing results
shown in 1, 2, 3, and 4 above
15. Ventilation (at least 6 turns/HR) by Exhausting ~ Air line ~
16. Employee entering and standby outfitted with chemically resistant
clothing (jacket, pants, gloves, boots, wrist straps and lifeline,
eye and face protection, safety hat)
17. Work lighting 12 volts or less
18. Air line breathing equipment worn/available to standby
19. Thirty (30)-minute breathing equipment worn/available to standby
2U. Two-way radio, L.E.L. 02 meter for standby
21. Fire extinguisher with BC rating available to standby
22. Location of extinguishers, safety showers, and monitors reviewed
with crew
23. Other precautions taken (detail)
YES
NO
DNA
24. SHIFT SUPERVISOR'S SIGNATURE DATE
25. MAINTENANCE SUPERVISOR'S SIGNATURE DATE
Uait voided by
SIGNATURE
Copy to safety files on / / (Date)
Job at this site was was not completed
Figure 19. Safe work permit (C02 Acceptor Pilot Plant).
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Vessel and confined space entry procedures can be subdivided into five basic
operations.
Preparation of Vessel--Before the vessel is opened, all material must be drained
or pumped from it and disposed of or stored in a suitable manner. The vessel
should then be flushed with steam or chemical solvents to remove all toxic gases
or chemical residues. Next, it should be depressurized, if necessary, and flushed
with inert gas. Use of air at this stage may result in formation of explosive
air-vapor concentrations if residual amounts of flammable solvents or gas remain
in the vessel.
Isolation of Vessel—The vessel should be mechanically isolated from gas stream
lines and other sources of hazardous material either by blanking off entering
lines with caps or plugs, or by removing a section of pipe.
Other methods such as closing valves and draining do not provide the desirable
feature of the positive break between the line and the vessel. The policy of
relying totally on valves is to be discouraged.
When unavoidable, shut valves should be chained and double locked by the shift
supervisor and workman.
Ventilation—Fresh air should be introduced into the vessel by exhausting the
existing vessel atmosphere with ventilation fans and flexible ducts. Exhausted
air should not be dumped into areas where ignition sources exist or where per-
sonnel may have an opportunity to come into contact with them. Further, the
contaminated air should be treated to prevent environmental contamination.
If the vessel has only one opening, a flexible exhaust duct should be extended
as far into the vessel as possible and attached to a high-volume exhaust fan.
The geometry of the vessel should be considered during ventilation operations
to preclude the possibility of leaving dead air spaces, which may contain
toxic or explosive gases and vapors.
Testing of Atmosphere—After ventilation and prior to human entry, the atmosphere
within the vessel must be checked for the following:
• Presence of adequate oxygen concentration, at least 19%
• Explosive atmospheres (Atmospheres greater than 1/10 of the lower explosive
limit should never be exceeded.)
• Presence of toxic gases and vapors, determined by direct reading indicator
tubes or instruments
General Safety Procedures--If it is determined by measurement that toxic gases
or vapors are present or that adequate oxygen concentrations cannot be maintained
within the vessel or confined area, then respiratory protective equipment must
be provided as described in later sections on respiratory protective equipment.
A "buddy system" must be used whenever personnel are required to enter vessels
or other confined spaces. The standby employee should:
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• assist in moving tools or equipment,
o keep in continuous contact with the person inside the vessel, and
• initiate rescue of person in the vessel if required.
No more than one employee shall enter any one vessel unless means are
available to retrieve all personnel in an emergency.
Process Line Opening--
Frequently it is necessary to open process lines to remove or change equipment
such as pipes or compressors. Depending on where these lines are in the process,
they may contain residual gases, vapors, and/or liquids. As with vessel entry,
a safe work permit requiring a comprehensive safety and health hazard evalua-
tion should be completed prior to these operations. As a minimum precaution, a
double block and bleed valve arrangement (Figure 20) should be available and
used. The line should be blocked upstream and downstream of the two flanges
or joints prior to opening the bleed valve.
/
£
Figure 20. Pump and shut-off valve.
Unfortunately, a potential health hazard may be caused by emissions from the
bleed line. If the health hazard evaluation indicates that toxic material may
be emitted, a portable or permanent exhaust hood should be used to remove any
toxic gases or vapors to the flare. The bleed valve should be gradually opened
over a period of time to prevent high-velocity discharges under pressure, which
could negate the benefit of the exhaust hood. Obviously, if liquids are antici-
pated, the bleed line should be connected to a container to prevent work surface
contamination.
A formal, well-scheduled preventive maintenance program can be very useful in
reducing the frequency of leaks during process operations. Primary targets for
frequent examination include pump and compressor seals, valves, and gaskets in
flanges and vessel hatches. Scheduled replacements, regardless of need, should
be considered in attempts to eliminate problems before they have a chance to
occur. The scheduled changes should be planned to coincide with process down
time.
Process Start-up
Start-up procedures vary from plant to plant, but it is important that each
include a thorough leak testing sequence using inert gases in the system.
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Clearly, if leaks can be located and corrected before the process is started,
sources of potential health hazards will be reduced, as will the probability
of emergency shutdowns.
Before the inert gases are brought into the system it is beneficial to tape the
perimeters of all flanges with duct tape. The tape will turn brown if the
flange is leaking and thus the search for leaks is simplified.
To initiate the testing sequence, all valves within a given section should be
opened, the compressors started, and the inert gases admitted and gradually
pressurized to operating pressure. Each section should then be held at pres-
sure to determine whether there is either a pressure drop within the section or
a detectable leak. Once cold leak testing is completed, the pressure may then
be reduced and heat-up may be started. At 50% of operating temperature, leak
testing may be repeated, and it should include inspection of taped flanges.
Because there are many potential sources of leaks, as many as possible employees
should assist in the search. An adequate number of portable gas detectors is
also necessary. All leaks must be corrected by tightening flanges, changing
gaskets or seals, or replacing nonrepayable equipment (Oral communication,
February 14, 1977, by K. Martin, 6205-101 Avenue, Apartment 707, Edmonton,
Alberta, Canada).
Onstream Operation
When the process is under normal operating conditions, there should be very few
if any continuous sources of workplace emissions or airborne toxicants. All of
the processes are essentially closed, and most operate under such high pressures
that continuous leaks could not be tolerated without a severe fire hazard or an
adverse effect on essential operating parameters. Low-pressure processes may
require extra precautions because leaks could go unnoticed without affecting
quality parameters.
Worker exposure can and will occur because of minor leaks, primarily through
pump and compressor seals, valves, flanges, and other similar equipment. Thus
the most effective engineering control technique should incorporate good process
design characteristics and modification conducive to leak minimization; equip-
ment (such as pumps, compressors, and valves) capable of withstanding the severe
process stresses induced by high temperatures and pressures and by the existence
of slurries in many process streams; and proper seal and gasket materials and
design, modification, or equipment selection or development. These are primary
goals of the overall coal gasification pilot plant program. Obviously problems
associated with each process will have to be solved prior to the construction
of full-scale commercial plants.
The question of most effective seals for pumps and compressors does deserve
attention because of its importance to leak prevention. Double or even triple
mechanical seals (or 'their equivalent) should be used whenever possible on lines
containing toxic materials, because of their effectiveness in preventing leakage
Additional methods of leak reduction are the following:
• The maximum use of welded joints and connections rather than gasketed
flanges: The additional burden created by the required welding and cutting
should be more than offset by the elimination of leak sources and the
reduction in the number of emergency shutdowns.
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® The use of local exhaust ventilation in areas of frequent sources of leaks,
especially those in enclosed areas: This method has merit where all other
control techniques have not been completely effective.
o The development and use of standard operating procedures: The interactions
between the workers and the process are critical to preventing upset condi-
tions and the resulting exposures. When a worker makes an error there is a
potential for large emissions of toxicants and gross work surface contamina-
tion. Although there is little that can be considered standard under pilot
plant conditions, employees should be well trained and intimately familiar
with proper operating procedures. Written standard operating procedures in
conjunction with a formal training program are essential.
However, since the primary control strategy (a tight process) is still in the
developmental stage at the pilot plants, a total prevention of leaks is doubtful.
Therefore, methods of containing or correcting leaks as they occur are necessary
(leak detection strategies are presented in the monitoring chapter and discussed
further in this chapter under the heading "Air Sampling Program"):
® For lines containing toxic materials, valves might be "spared" (parallel
duplication) so that leaks can be bypassed. A system of parallel pumps
and compressors in critical areas is also desirable to bypass leaks without
causing an unplanned shutdown.
» A system of long, strategically located flexible exhaust ducts connected to
a common main may be practical and effective, particularly in enclosed plant
areas. When a leak is located, the flexible duct is positioned to capture
and remove the toxicants before they can contaminate the workplace. This
type of system eliminates the need for a separate exhaust for each potential
leak source, and does not require unusually large volumes of air because the
branches can be "deadheaded" or dampered when there are no leaks to contain.
The polyvinyl chloride industry uses this control technique extensively and
effectively to remove inadvertent leaks of vinyl chloride monomer. To over-
come the problem of capturing high-velocity leaks, a low-volume, high-velocity
exhaust system should be considered. This type of exhaust system induces
extremely high capture velocities.
e For liquid leaks, portable barricades or shields should be considered, to
contain and localize the area of surface contamination.
§ Drip pans or equivalent containers should be installed under process
equipment that has a potential for leaking liquids.
Planned or Emergency Shutdowns
During a shutdown (particularly for processes using a preheater or pretreater)
it is desirable to burn off all line material by bypassing it through the gasifier,
then to the thermal oxidizer. Following this, the system should be purged
repeatedly with inert gases until the process gas chromatographs reflect that
the lines are free of gases and vapors. Essentially, this procedure is
appropriate for both planned and emergency shutdowns.
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In most cases prior to an emergency or involuntary shutdown, a concerted effort
will be made to remedy the cause of the problem, such as a blocked line. It is
conceivable that certain of these efforts may greatly increase the potential for
employee exposure to process stream gases, vapors, or liquids. The decision of
when the shutdown is necessary must take into account potential health hazards.
Although it is important that emergency shutdowns be minimized,, worker
protection must be the primary concern.
Other Suggestions
• The composition of vented material and location of all process outlet vents
should be determined. Preferably, the vents should be fed to the thermal
oxidizer, but if not, the outlets should be located such that vented gases
and vapors cannot reenter the workplace.
• Enclosed process areas should have adequate general exhaust ventilation and
tempered makeup air. Without a continual turnover of air, concentrations of
airborne toxicants can build up and cause severe problems.
• The collection of process samples, particularly through the use of "shot
pots," can be a source of workplace emissions. Many times there are prob-
lems with closing valves, and toxicants can escape over a significant period
of time. Consideration should be given to providing local exhaust for these
operations. (See chapter on safety.)
9 Mixers, separators, and other vessels containing volatile liquids or liquids
containing dissolved toxic gases should not be open to the workplace
environment.
• The control rooms and lunch facility should be kept under positive pressure
relative to the workplace. This may be accomplished using an air supply
cleaned through a high-efficiency particulate (HEPA) filter. To encourage
maximum use of the facilities and to assist in keeping the doors shut, the
supply air should be cooled during hot weather and heated during cold
weather.
• The importance of good housekeeping procedures cannot be overemphasized.
particularly as it relates to good personal hygiene. Adequate time must
be allocated during every shift to clean up and, where necessary, to de-
contaminate work surfaces. Otherwise, residue will accumulate and greatly
complicate the problem. It must be understood that generally workers will
not initiate cleanup activities on their own unless convinced of their
value — it is not the most pleasant of jobs. The stimulus must come from
top management, through the supervisory levels, to the workers. The policy
on good housekeeping should be quite clear. Good housekeeping also has a
beneficial effect on individual attention to safety, observance of rules,
and personal hygiene. It engenders a good frame of mind, which is critical
to the success of the overall program.
SUGGESTED INDUSTRIAL HYGIENE PROCEDURES
Health Education Program
Most occupational physicians and industrial hygienists agree that workers must
be familiar with the hazards to which they may be exposed. As Eckhardt (1960)
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aptly stated, "It seems axiomatic that if a man is to protect himself from a
hazard he must be informed of the nature of the hazard from which he is protecting
himself." This has particular significance for hazards involving skin contact
with carcinogenic compounds, where good personal hygiene is essential. It
follows that workers should be knowledgeable about the provisions that are
available to them for protection against the hazards. They must be educated in
the proper use and reason for each protective device or procedure in the program.
A meeting of all employees should be held to describe in detail all potential
health hazards, as well as the features of the medical surveillance program.
Although exposures to carcinogenic materials will necessarily get the greatest
attention, exposure to other potential toxicants or irritants such as CO, H2S,
and coal dust, as well as harmful physical stresses such as noise and heat,
should also be discussed. Good preventive health procedures should be stressed.
Existing or newly implemented protective measures should be fully described.
Of course, during this meeting there is insufficient time to actually instruct
the workers on the specific aspects of the preventive program. This should be
done during subsequent meetings and should be a supervisory responsibility.
However, each item should be touched on, and the joint responsibility of supervi-
sors and employees in the implementation of this program should be stressed.
To yield any degree of success, the program must be continual, with periodic
meetings and continuous emphasis from those in charge.
Topics of discussion during the periodic meetings may include:
• specific operations resulting in high exposures to toxicants, with emphasis
on airborne particulate and surface contamination containing carcinogenic
compounds and vapors;
® purpose and results to date of the air sampling and work surface inspection
programs;
• purpose and proper use of respiratory protective equipment;
9 open discussion concerning the protective clothing program;
• purpose and discussion of the work surface cleanup and decontamination
program;
9 open discussion of improved work practices and engineering control
options;
ft outline of emergency procedures, including first aidi and
t other topics of importance based on program results to date.
The success or failure of this program hinges on the diligence and support of
three groups: (I) plant management, (2) supervisory personnel, and (3) the
unions or plant operators.
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Personal Hygiene Practices
A strict personal hygiene program is essential for proper worker protection in
coal gasification pilot plants. Even if all external sources of skin contami-
nation could be eliminated by extensive engineering and work practice controls,
exposures would remain because of frequent operating changes and the concomitant
potential for contact with contaminated surfaces inside of process equipment.
Protective Clothing--
The selection of the optimum type and combination of protective clothing is a
difficult one requiring trade-offs among several options. The clothing should
minimize exposed skin surfaces, provide good repellency against liquids, reduce
the passage of vapors and aerosols, and be relatively acceptable to the workers.
A rubberized fabric has excellent repellency and is very impervious, but could
cause an unacceptable risk of heat stress problems. Many close-knit synthetic
fabrics have very desirable protective properties, but they also could cause
heat stress problems and they tend to melt when a flame is applied to them.
It is suggested that jumpsuit-type, cotton coveralls will provide a great deal
of protection, provided that they are a fairly close weave and are designed not
to "breathe" heavily with normal body movements. The coveralls should be white
so that contaminated areas will not be masked.
There is evidence that the type of underclothing is very important to the
reduction of skin contamination. From an experiment undertaken in 1957 at a
coal hydrogenation pilot plant it was concluded that pajamas, buttoned at the
neck, with close-fitting arm and leg cuffs, worn under typical work clothes,
were very effective (Ketcham and Norton 1960). Apparently this prevents con-
taminants absorbed into the outer clothing from continually contacting exposed
skin beneath it. It also provides an additional barrier to the passage of vapors
and aerosols. Regardless of whether normal work clothes or loose underclothes
are selected to wear under the coveralls, they should be long sleeved, buttoned
to the neck, and have close-fitting arm and leg cuffs.
Gloves are usually worn at coal gasification plants during cold weather, when
heavy equipment is handled,or in areas where process equipment is hot. Where
gloves will not cause a significant safety hazard, they should be worn to assist
in preventing hand contact with coal-derived materials. Gloves also have the
secondary effect of reducing the spreading of contaminants from the hand to
other parts of the body, particularly the head and face. However, gloves made
out of absorbent materials should not be used because, once contaminated, they
will remain a constant source of hand contamination until laundered. The pre-
ferred glove should be impervious to the absorption or passage of process
residue, and capable of withstanding daily laundering.
There should not be large quantities of liquid residue from the gasification
process, so work boots should provide adequate protection. However, if prob-
lems with foot contamination develop, loose impervious overshoes should be
considered. Rubber overshoes are not recommended because of swelling problems
caused by contact with process oils.
It would be prudent to conduct tests with several types of clothing and fabrics
prior to selecting and purchasing a large number of any one type. The tests
°5
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should be performed on a small number of employees within a similar job
category (preferably those with the highest risk of skin contamination), and a
decision based on fluorescence testing of inside fabric surfaces should be
made.
Laundering--
Several sources indicate that the best method of ridding work clothes of coal-
derived contamination is dry cleaning, followed by washing with soap and water
or a commercial detergent (Sexton 1960b). The fact that work clothes should be
periodically cleaned is not open to much question, although the proper frequency
is. Eckhardt (1960) suggests that if a choice is necessary, a daily supply of
clean underclothing is preferable to daily cleaned outer clothing. He states
that "(i)n our view, if the clothing in contact with the skin is cleaned daily,
the cleanliness of the outer clothing is less important. In our experience
at Esso and from studies done by Venable and Wilkening (1958), not enough
material is retained by the outer clothing to penetrate clean underclothing
for more than the day of contamination, but once contaminated thoroughly,
underclothing can repeatedly soil the skin." (It is inferred that outer clothing
means anything that is not in direct contact with the exposed skin, i.e., cover-
alls.) This implies that although the underclothing should be cleaned daily,
this frequency is not necessary for the outer clothing.
It is felt that this is unacceptable because of the potential carcinogenicity of
the coal-derived residues, the higher possibility of preventable skin contami-
nation for several shifts after the outer clothing is soiled, and the fact that
the additional burden of daily cleaning of the coveralls is relatively
insignificant.
Because of the large amount of required laundering, it is preferable for each
pilot plant to have cleaning facilities. However, whether the cleaning is done
in house or commercially, laundry employees should be warned of the hazard of
making skin contact with contaminated clothing or laundry fluids.
It is recommended that clean outer garments and underclothing (including socks)
be issued to all workers at the beginning of each shift. The effectiveness of
the cleaning method should be periodically evaluated by examining laundered
clothing under an ultraviolet lamp.
The above discussions place significant responsibility on pilot plant personnel
to determine the most effective protective clothing and cleaning programs.
This is necessary because specific suggestions could preclude the location or
development of better methods, and not enough is known at this point to
substantiate specifics.
Further, the discussion implies that it is necessary for all employees who
enter the plant processing area to follow the same guidelines. If the personal
hygiene program is to be accepted by the workers, it must be administered and
adhered to uniformly, with no exceptions. If engineers and other office person-
nel or visitors enter areas where coal-derived contamination is possible, it is
logical to assume that they need equivalent protection.
Locker and Shower Facilities--
In the coke oven industry, showering at the end of each work shift has been
cited as one of the most significant factors in preventing skin cancer
96
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(Federal Register 1976a). At coal gasification pilot plants, it is similarly
important that employees shower at the end of each shift to assure that skin
contamination is removed. Adequate time and well-designed facilities are
necessary to encourage adherence to this requirement.
To promote good personal hygiene practices, encourage adherence to the daily
shower requirement, and segregate contaminated clothing from street clothing,
a double locker room separated by a large shower facility should be installed.
The essential features of the double locker room are depicted in Figure 21
and summarized below:
• Two sets of lockers are provided on the clean side for each employee — one
set is for street clothing, the other for clean work clothes provided daily
t A set of lockers is necessary on the contaminated side to allow storage of
work boots, hard hats, and other safety equipment. These items are acces-
sible through a one-way door in the partition separating the clean and
contaminated sections of the facility.
t Soiled clothing removed following shift activity should be segregated so
that outer garments are not mixed with employee clothing in direct contact
with the skin. The indiscriminate collection of all clothing may cause the
spreading of contamination from overalls, for example, to undergarments.
• Grossly contaminated clothing should be totally segregated from all other
clothing for disposal.
q
uj
K
ct-oseo cowT/j/A/es. POK. DISPOSAL
Of GROSSLY CONTAMINATED
•LOCXER5 FOR WOZ.K, BOOTS
Hft-rS OTI-IE^ SAFETY £<0'J
SOILZP
CLOSSO CQHTQ/H£R FOR.
SOILED OUTSR. CLOTHING
QOOR
CL£AM PLANT
CLOTHES
COCKERS-
' WT/
1
y
--STREET CLOTHES
Figure 21. Double locker room.
-------
Regular soap is recommended for the shower facility: the use of solvents may
transport the contaminants into the skin (oral communication, January 1977, by
J. Hultz, Pittsburgh Energy Research Center, 4800 Forbes Avenue, Pittsburgh,
Pennsylvania 15213) and thus hinder removal. It is important also that workers
thoroughly wash their hair during showers.
General--
After study at a coal hydrogenation plant, Ketcham and Norton (1960) concluded
that "(t)he waterless hand soaps appear by far the best." Lanolin based or
equivalent nonaqueous hand cleansers should be provided in all washrooms in
the plant and in the locker facility. All trips to sanitary facilities should
be preceded by a thorough cleansing of the hands.
Barrier creams are frequently mentioned as being of value in occupations where
skin contamination or dermatitis is a recognized problem, although actual
benefit has not been proven and is a subject of some controversy. It is there-
fore not possible to fully encourage or discourage the use of barrier creams; at
best, they may only be considered a minor adjunct to the overall protective
program. Unless the efficacy of specific, barrier creams can be proven, workers
should not be required to use them. However, the creams should be made avail-
able to employees for use upon request or under advisement of an occupational
physician.
The presence or consumption of food, beverages, and smoking material, and the
application of cosmetics, should be restricted to designated areas that are
enclosed, under pressure from a clean air supply, and not contaminated with
process residues. It is preferable to have a central lunchroom for this purpose,
but control rooms or other areas that meet the above requirements are acceptable.
An adequate number of washrooms should be provided throughout the plant area to
encourage frequent cleaning by workers. In particular, a washroom facility is
necessary in close proximity to the lunchroom so that employees can wash thor-
oughly prior to entering. It is very important that the lunchroom remain un-
contaminated as it is one area where most or all employees will consistently
congregate. Therefore, it is advisable that the workers remove their gloves
and hard hats prior to entering. This necessitates the provision of some type
of interim storage area or facility. Employees with contaminated coveralls
should change them prior to entering the lunchroom.
If gross contamination of either exposed skin surfaces or outer clothing occurs
during a shift, it is extremely undesirable for the worker to remain exposed
until the shift is over. In such situations, a prompt shower and change of
clothes should be required. Because of the importance of this protective
measure, supervisory employees must accept the responsibility of assuring strict
compliance with this requirement.
The personal hygiene procedures described in this section must be supplemented
with a continual worker education program, and an adequate amount of time should
be allotted each shift for employee participation. If the necessary time and
training are not provided, the protective programs will simply not be effective.
Respiratory Protection
Respirators are considered a "last resort" method of reducing employee exposure
to airborne toxicants, acceptable only after it is demonstrated that engineering,
work practice, and/or administrative controls are not sufficient, during the
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interim period until effective controls are implemented, or in hazardous
operations or emergencies. The primary goal of the health protection program
should be the control of process emissions at the source to eliminate employee
exposure and the resulting need for respirators. The source control strategy
is important because respirator use may not afford adequate protection. For
example, the fit may be poor, or the respirator may not be used because of
worker discomfort or ignorance about the fact that a significant airborne ex-
posure exists. Further, respirators interfere with communication, may contrib-
ute to heat stress problems, frequently cause facial rashes, and if not
maintained properly, will not provide protection even when worn.
However, during certain maintenance operations (these are frequent in pilot
plants), during leak conditions, and while effective controls are being de-
veloped, respirators are necessary. Since it is apparent that they will be
needed periodically, an evaluation of the proper respirator is necessary.
The selection of respirators is dependent upon the following:
t The airborne toxicants causing the potential health hazard, its hygienic
standards, and its olfactory warning properties
t The physical state of the airborne toxicant (i.e., gas, vapor, aerosol)
• The estimated maximum concentration of the toxicant in relation to its
hygienic standard
• The job requirements of the workers (e.g., mobility around moving equipment)
Potential airborne toxicants in most pilot plant areas include a large and
complex variety of gases, vapors, and aerosols. Of the currently available
respirators, only a supplied air system can provide protection against the wide
range of anticipated exposures. Unfortunately, supplied air respirators require
umbilicals in the form of air lines or hoses, which reduce mobility, introduce
unacceptable additional safety hazards, and may restrict immediate escape
during an emergency. Although supplied air respirators have been successfully
integrated into other segments of the chemical industry without overwhelming
problems, a coal gasification pilot plant is unique because of the frequent
process changes, continual maintenance requirements, and peculiar safety
hazards associated with the extremely high operating temperatures and pressures.
Except at very restricted maintenance operations where the oxygen may be de-
ficient, where large concentrations of gases (CO, H2S) may be anticipated, or
during emergency conditions, supplied air respirators are not suggested.
However, self-contained air or air line respirators should be readily available
at all times for use when needed.
Until a respirator is developed that can provide protection against the wide
range of toxicants emitted during coal gasification process leaks, specific toxi-
cants must be selected as the basis for respirator determination. A precedent
exists in the coke oven industry, in that a similarly wide range of airborne
toxicants is emitted into the workplace. The coke oven emissions standard
(Federal Register 1976a) recommends protection against carcinogenic particulate
matter and specifies respirators accordingly, based on the airborne concentra-
tion of coke oven emissions. For concentrations not greater than 1500 yg/m3
benzene soluble compounds (as the benzene soluble fraction of total particulate
matter), the recommended respirator provides protection against organic vapors
and particulate matter. In coal gasification pilot plants, a combination
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participate matter and chemical cartridge respirator is suggested for maintenance
and operating personnel for protection against carcinogenic aerosols and organic
vapors such as benzene. A formal respirator program that meets the requirements
of Title 29 CFR 1910.134 should be mandatory.
This respirator should be carried by every employee while in operating areas,
and is recommended for use except in the following circumstances:
• During emergency conditions when an employee has to be in the immediate area
of a bad process leak: In this situation, high concentrations of toxic gases
(CO, H2S) could be anticipated and could cause acutely adverse effects.
Supplied air respirators are necessary for this type of emergency condition.
e During vessel entry when tests have shown that the oxygen is deficient (<19%),
that CO concentration >35 ppm, or that H2S >10 ppm: Further purging and
ventilation are necessary prior to entry.
0 In areas where carcinogenic particulate matter or organic vapors are not the
prime concern, for example, in the acid gas cleaning process where H2S is of
primary concern, or around certain methanators, where nickel carbonyl may
contaminate the workplace: In these instances, respirators designed
specifically for protection against the particular toxicants are required.
Regulated Areas
There are several reasons for designating and posting regulated areas, including
the following:
• Restricting employee entry into the area
• Specifying the required type of personal protective equipment and
controlling usage
• Pinpointing employees in the area who should have additional protective
requirements
All occupational health standards to date have relied heavily on the concept of
regulated areas to simplify the task of administering and regulating the re-
quirements of the standard. When one toxic agent or one area (e.g., coke ovens)
is concerned, the determination of which areas should be regulated is a straight-
forward and relatively simple task. Employees remain in essentially the same
area; emissions are relatively constant; and periodic personal monitoring can
provide a very good estimate of worker exposure. Unfortunately, this is not
the case in coal gasification pilot plants, where there are multiple toxicants
potentially entering the workplace from various sources and at different times.
To complicate the matter further, the various process areas are usually in close
proximity to each other and not enclosed, so leaks of toxicants in one area may
contaminate work areas throughout the plant. Further, employees frequently move
throughout the plant area, experiencing numerous potential exposures from many
different sources. The typical regulated area concept is thus not totally
applicable to coal gasification pilot plant conditions.
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Several options may accomplish the purposes derived from the usual regulated
area concept:
• Job functions are regulated instead of work areas. All jobs that involve
opening or entering any process vessel, line, or other piece of equipment
should be considered regulated. Most maintenance jobs and tasks such as
sample taking will fall into this category.
• Process areas are regulated if the results of the monitoring program show
that the concentration of any of the following routinely exceeds the
indicated limit:
Carbon monoxide (35 ppm)
Hydrogen sulfide (5 ppm)
Benzene solubles (150 yg/m3 in any area other than coal storage and
preparation)
Respirable particulates (2.0 mg/m3 in the coal storage and preparation
areas)
Benzene (1 ppm)
This will apply primarily to enclosed plant areas; open plant areas may
exceed the indicated levels during a leak condition but the frequency should
be low.
• Plant areas with work surfaces that are frequently contaminated with coal-
derived materials should also be regulated. The same is true for plant
areas where gross contamination has occurred. Entry into these areas should
be restricted to the extent that no employee should risk potential skin
contamination unless entry into the area is absolutely necessary.
Everyone who enters these areas should be required to wear respiratory
protective devices until engineering controls can be installed to reduce ex-
posure to acceptable levels. Entry into the regulated areas must be strictly
on a need basis.
Posting
Posting warning signs at various plant areas reinforces adherence to the
requirements of the overall health protection program. The signs serve as
oeriodic reminders to workers that potential hazards exist and protective
measures are necessary. To be effective the signs must be kept clean and
visible, and should be illuminated at night.
Because work surfaces in many plant areas may be contaminated with coal-derived
compounds, all entrances to plant process areas should be posted. Example:
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CAUTION
Work Surfaces
May Be Contaminated
With Cancer Suspect Agents
Authorized Employees Only
Protective Clothing Required
Avoid Contact With
Process Liquids or Residues
Smoking and Eating Restricted
to Designated Areas
Although it may be argued that these signs should be selectively posted only
in areas of known harmful contamination, it is important that workers consider
all surface contamination potentially hazardous.
Entrance to regulated areas should also be posted. Example:
CAUTION
Cancer Suspect Agents*
Respiratory Protection Required
Authorized Employees Only
During regulated job functions (e.g., maintenance work), the work area should
be cordoned off and a warning should be posted at the extrance. Example:
CAUTION
Restricted Area
Authorized Employees Only
^Because of the number of possible toxicants, this general statement is suggested,
In regulated areas where carcinogens are definitely not present, different or
more specific statements are preferred (e.g., "Dust Hazard," "Hydrogen Sulfide
Present," "Toxic Gases and Vapors Present").
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Label ing
In the developing stages of fluid catalytic cracking in the petroleum industry,
an integral part of the control program was the identification, labeling, and
painting of all tanks, lines, or other equipment that might contain carcinogenic
oils. In addition, process samples and contaminated equipment going to repair
shops were identified with brightly colored tags (Holt et al. 1951). This
helped to warn employees that a potential hazard
maintenance operations or when a leak occurred.
for coal gasification pilot plants. All process
genie compounds should be identified by a brightly colored paint.
vessels should be painted and labeled. Example:
existed, particularly during
A similar approach is of value
equipment containing carcino-
Process
CAUTION
Contains Toxic Materials
Equipment or other items that are contaminated with coal-derived materials should
also be identified with a brightly colored tag.
Surface Cleanup and Decontamination
There are three types of cleanup and decontamination problems.
Liquid Spills or Leaks--
Once a significant leak or spill
as possible to minimize the area
is
of
located, it must be contained as quickly
contamination. Extreme care must be ex-
the cleanup
step in the
or leak and
a pump seal
to reduce the potential of gross
containment of the spill is to
correct the problem. This correction
packing gland or switching to a
ercised by workers involved in
skin contamination. The first
locate the source of the spill
may be as simple as tightening
"spared" valve, or as drastic as initiating a process shutdown. Next it is
necessary to contain the spread of the contamination by perimeter diking, using
heavy work cloths, or materials such as long lengths of lumber. After the
spill is contained, several methods can be employed to transfer the liquid
into sealed, impervious containers. Squeegees and scoops can get up the bulk
of the liquid, and then absorbent particles can be deposited and swept up when
the remaining liquid is absorbed. Alternatively, portable suction pumps can be
used to transfer liquids into a container for disposal. Finally, it is necessary
to clean the surface with commercial detergents and a stiff brush. Water flushing
should not be used to disperse and remove liquid spills, however minor, because
the area of contamination may be increased.
Other Surface Contamination—
Dried, condensed tars are difficult to remove from any surfaces and particularly
from the inside of process vessels. Manual scraping and chipping of the sur-
faces, coupled with the use of chlorinated hydrocarbon solvents or commercial
cleansers, are frequent methods of cleanup. Where solvents are used, special
care is necessary to prevent more hazardous exposures to solvent vapors.
Cleaning solvent should be selected in terms of low toxicity and vapor pressure,
and respirators should be worn. Steam stripping is also used extensively and
is effective, but it should be noted that severe airborne exposures to potential
carcinogens may result. Lower boiling point residue may vaporize and high
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boiling point material may become entrained in induced air currents. Generally,
steam stripping is not recommended because of this potential for gross air con-
tamination, but there may be instances (e.g., small, confined surfaces) where
it is essential. It is recommended that if steam stripping is used, supplied
air respirators be worn by all employees.
Tools and Equipment--
Hand tools and portable equipment may frequently become contaminated with coal-
derived materials and present an exposure to employees using them. These should
be periodically cleaned with detergents and/or solvents. Again, care must be
taken to prevent exposure to hazardous solvent vapors. Before the tools or
equipment are returned to service they should be examined for residual
contamination in an ultraviolet dark box.
A UV scan of the affected areas following decontamination will determine whether
additional cleaning is necessary. All employees involved in the cleanup opera-
tion should be required to shower and change clothes after the operation is
completed.
Soiled work clothes and other materials used during the cleanup must be placed
in closed containers for disposal. Reusable items such as scraping or chipping
tools should be placed in closed containers for transfer to specially designed
areas with adequate ventilation for cleaning and decontamination.
Record Keeping
In a new industry where no useful precedents exist and there are more questions
than answers, it is imperative that complete records be developed and maintained.
Pilot plant personnel would not think of completing a process without recording
and maintaining all pertinent data on operational parameters and results. These
data are critical to the performance of future runs and imperative for the
determination of the nature of future demonstration and commercial plants. It
is similarly essential that thorough records of all aspects of the health
protection program be produced and maintained.
Detailed records of the following activities should be maintained:
* Air sampling: Date, instrumentation, and analytical method; location if area
sample; employee name and job classification if personal sample; operating
conditions, and meteorological conditions (if outdoors), during the sample;
duration of sample; sample air volume; sample result; additional information
as required to evaluate employee exposure or for other purposes such as
prospective epidemiology studies.
• Leak detection: Date, instrumentation; location, concentration, sfid cause
of the leaks; method of containment or repair (it is beneficial to categorize
leak data to assist in analyzing trends or diagnosing problem areas for
investigation — for instance, frequent leaks from a particular valve or
flange).
• Training: Date, employee group, type of training or meeting, objectives,
significant results.
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• Preventive maintenance: Equipment, location, scheduled date, completion
date, outcome.
t Medical records^ See chapter on medical monitoring.
AIR SAMPLING STRATEGY
The measurement and subsequent evaluation of workplace concentrations of airborne
toxicants are fundamental to an effective and efficiently administered health
protection program. It is absolutely necessary for pilot plant personnel to
initiate a monitoring program designed to yield pertinent and timely data on
the nature, sources, and extent of the existing exposure.
The suggested features of the sampling programs are discussed in the following
chapter, "Monitoring the Worker's Environment," and consist of the following:
• Quick response monitoring for selected indicator gases such as CO or H2S
• Personal monitoring for benzene soluble compounds, measured as the benzene
soluble fraction of total particulate matter (BSFTPM)
• Workplace area monitoring and the evaluation of worker exposure in all enclosed
areas conducted in accordance with existing standards.
Monitoring for the selected indicator gases is the foundation of the sampling
program, and thus, it must be continually emphasized. In pilot plants where
the gasifier section is enclosed, a permanently affixed, multiple gas monitoring
system is recommended. If there is a leak, CO or H2S concentrations will build
up until one of the sampling heads picks up a high reading. At this point, a
system of warning lights should be activated, and two actions are required:
• The workers in the areas will have to put on respirators until the warning
lights go out, indicating that the potential hazard has subsided.
• A designated worker will immediately use a portable gas analyzer for a
systematic search to locate the source of the exposure. Once located, the
leak may be repaired on the spot, contained by local exhaust ventilation,
bypassed by switching to a parallel line, or if it cannot be repaired or
contained, maintenance will be summoned (must be priority task).
If CO concentrations are high enough to create an acute exposure hazard, the
warning lights should flash. This indicates that a respirator is insufficient
for adequate protection, and a supplied air respirator is required. However,
this condition should be very rare. As discussed previously, for open process
areas, a permanent monitoring system is not practical. The monitoring must be
done manually, with a portable gas analyzer. For the purpose of profiling
process areas where CO or H2S ,5 to be used as an indicator gas, respirators
must be specifically assigned to an employee or employees on each shift.
Essentially, this constitutes a manual leak test program. The instrument
sensor should be maneuvered around all potential sources of leaks (flanges,
valves, sample pots, etc.). Leaks will be indicated by any instrument reading
above the normal background CO or H2S level, and they can be located and cor-
rected before they become larger and pose a significant employee exposure. As
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explained before, wearing of respirators may be required until the leak can be
repaired, contained, or bypassed.
What if leaks occur while the leak-testing employee is not in the area? First
of all, the leaks detected by this method will generally be small and develop
gradually. Larger leaks will be apparent, either visually or by a drop in
operating pressure, or by the fires they cause. This method is certainly not
perfect, but it is acceptable because the frequency of the search cycle in each
area will be high and leaks will thus be identified soon after they occur.
This approach to monitoring is used extensively and successfully in the polyvinyl
chloride industry. It has considerable merit because it not only provides an
indication of employee exposure, but. also assists in the control program and
determines periods when respirators are required. In some ways this approach is
superior to standard personal monitoring. For instance, personal sampling yields
no information on what the sources of exposure are and when the exposures occur.
Of primary concern is the potential for airborne exposure to carcinogenic
compounds. The indicator gas monitoring system provides some indication of
exposure but, because of the importance of this exposure, personal monitoring
for benzene soluble fraction of total particulate matter (BSFTPM) is necessary.
Workers in each job classification should be periodically monitored. In the
initial stages of the program, the frequency of personal sampling should be
relatively high. At least for the first several months, an employee in each
classification should be sampled once a week. Based on the results of these
tests the frequency may be increased or reduced. Because of the large number
of maintenance workers, the relatively high potential of exposure, and the
variability in their work routines, this job classification should initially
be monitored on a daily basis.
When the sample is collected, the worker should be questioned concerning his
location during the shift, what tasks he was involved with, and any unusual
conditions during the sample period. This information must be recorded to allow
an analysis of the sample result. It should be noted that employees working in
the coal handling or preparation areas should be exempt from this type of
sampling. This is because coal dust contains benzene solubles and thus the
result would not necessarily be indicative of actual exposure to. carcinogenic
compounds. Personal sampling in these areas should follow NIOSH recommendations
for evaluating exposure to airborne coal dust.
Periodic personal sampling should be undertaken to determine the efficacy of the
indicator gas strategy. Personal samples for toxicants such as benzene or toluene
are recommended for each job classification (in areas where these vapors may be
present) initially once a month. If, after several months, it is apparent that
exposures are low (e.g., consistently lower than one-half the respective
standards), the sampling frequency may be reduced to a quarterly cycle.
Some toxicants may be unique because of their probable location and/or
toxicological properties and need to be investigated separately. A good example
of this is the potential for nickel carbonyl exposure in the methanation area
or trace metals in areas where reactor char and ash may become airborne.
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MISCELLANEOUS
Physical Stresses
Relative to the health hazards posed by toxic chemical agents, employee exposure
to physical stresses such as heat, noise, and vibration is not so severe. How-
ever, the potential for problems cannot be neglected.
Sound level readings (dBA) should be taken and recorded for all plant areas,
with a properly calibrated sound level meter. All areas having steady-state
noise levels over 90 dBA should be posted with signs indicating that ear plugs
or muffs are required. This should be required even if employees are only in
the area of exposure for short periods of time. Even though time-weighted
average exposures may be well below the limit, it is prudent to provide pro-
tection even for short exposures. The area of most concern is the coal prepara-
tion building, because of noisy mills and vibrating screens. When possible,
these sources should be controlled by isolation, with acoustical enclosures.
However, this may be difficult to implement because of problems with the need
for frequent maintenance and dust buildup and a resulting potential for ex-
plosions. Since workers spend much of their time in control rooms, these should
be acoustically treated to provide relief from high noise levels.
Impact noise and vibration are not anticipated to be significant sources of
exposure. Heat stress problems should not be especially significant either,
with one exception — those encountered by workers entering vessels or confined
spaces. These operations should be surveyed with wet bulb, dry bulb, and globe
thermometers and the WBGT index should be calculated. The NIOSH Criteria for
a Recommended Standard —Occupational Exposure to Hot Environments (National
Institute for Occupational Safety and Health 1972c) should be used to evaluate
the exposure. If it is excessive, management should implement the control
recommendations outlined in this document (that is, reducing exposure time,
providing air movement and specific clothing, and reducing temperature and
humidity).
Welding
Because there is a substantial amount of inherent maintenance and equipment
modification in pilot plant operations, welding operations can involve many
workers and, therefore, present potential hazards from metal fumes, toxic gases,
electrical shock and the potential for explosion. Much of the steel used in
pilot plant equipment is alloyed with toxic metals such as chromium and nickel.
Further, torch temperatures have to be very high, and welding and brazing materials
may contain an unusual combination of toxic metals. All of this may contribute
to a very severe health hazard if proper work practices, eye protection, and local
ventilation are not used. Because of the nature of the welding operations, it
is essential that only highly trained, certified welders be used. The American
National Standards Institute publication, "Safety in Welding and Cutting" (1973),
may be used as a guide for proper engineering controls.
PRIORITIES
Not enough is known about the nature and sources of air and surface contamination
to attempt even a general analysis of potential engineering and work practice
controls on a unit process basis. The potential hazards associated with each
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unit process have been thoroughly discussed in the "Coal Gasification: Process
Discussion" chapter of this document and need not be reiterated. However, it
is desirable to determine which areas present high health hazards, particularly
which ones contain carcinogenic tars and oils. Clearly, intermittent exposure
to coal dust does not have the priority of leaking tars and oils from the
pretreater.
There are several provisional high-priority areas:
Pretreater
Gasifier
Venturi scrubbers
Scrubber surge tanks
Decanter
Equipment for ash removal and disposal
There is one item that deserves special attention, although it is not directly
related to employee exposure or protection. Coal dust may become airborne con-
tinuously from open coal piles and intermittently from various operations in-
cluding unloading, front-end loader of conveyor transporting, and cleanup.
From an employee exposure point of view, this is a low-priority hazard relative
to others encountered in the plant. However, if this coal dust is blown or
drifts into other process areas, it will have an extremely adverse effect on air
monitoring activities. The success of the air sampling program rests heavily on
the ability to accurately measure airborne concentrations of BSFTPM. As coal
dust in the areas where the samples are taken may render the results meaningless,
it is important to institute control measures that will either reduce dust
generation at the source or prevent it from entering other process areas.
Possible controls include .the following:
• Enclosing coal storage piles
• Keeping open coal storage piles tight and compact
• Shielding or partially enclosing coal transport conveyors
• Enclosing all conveyor transfer points (e.g., bin to conveyor, conveyor
to bin)
• Scheduling and requiring periodic cleanup operations to minimize coal
accumulations throughout the area
0 Wetting and/or removing undesired coal accumulations
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MONITORING THE WORK ENVIRONMENT
INTRODUCTION
The normal purpose of monitoring is to learn whether exposure to chemical and
physical hazards is within prescribed limits and to trigger corrective action
if it is not. There are two types of monitoring:
• Area monitoring: Data is collected on workers' locations during a
shift and exposure is calculated from that.
0 Personal monitoring: The sampling device is worn by the worker.
This procedure provides time-weighted exposure data.
Effective monitoring requires practical methods of sampling that are readily
adaptable to industrial environments. Sampling must be oriented towards pro-
tection of health rather than accumulation of analytical data.
There are few industrial fuel processes that match the chemical and engineer-
ing complexities of the coal gasification plant. Solid, liquid, and gaseous
intermediates and effluents associated with various operations within all coal
gasification pilot plants can come into contact with the skin and respiratory
system. As indicated earlier, there are exposure risks from thousands of
different chemicals.
If we assume that occupational exposure standards exist for 200 of these
chemicals, there are still many remaining substances for which there are no
applicable standards or reliable toxicological data. The carcinogens associated
particularly with condensable coal-derived hydrocarbons are an extreme case of
multifactorial exposure problems. Even the single category of polycyclic
aromatic hydrocarbons, considered separately, is very complex. It could not be
fully analyzed, compound by compound, on a routine basis, nor could an analysis
be translated into a quantitative index of hazard. The evaluation is further
complicated by a wide range of potentiators and modifiers:
t High-boiling compounds in the same fractions
• Compounds such as sulfur dioxide and phenol
• Particulates with adsorbed chemicals
Therefore, the recommended approach is to achieve a simplified exposure approxi-
mation by measuring only one or two variables. Being an incomplete solution,
this calls for other measures to augment worker protection. These measures
should be directed towards preventing and controlling emissions, rather than
monitoring exposures, and a strong medical surveillance program should be
implemented.
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An approach is needed that will simplify the problem by a rational method,
without sacrificing worker protection. The important concern in developing
guidelines is to work within a margin of safety that can reasonably be expected
to cover all probable health hazards and to protect personnel from an unde-
sirable level of risk until adequate information leads to the establishment of
safe limits.
Sampling and analytical methods are already available for a wide range of
chemical and physical agents. In most occupations, a worker in any single job
category is exposed to only one or a few toxic hazard(s), and ways to assess
the total effect of multiple hazards have been recommended (American Conference
of Governmental Industrial Hygienists 1976). Coal gasification plants present
unusual problems that demand a special approach to monitoring. The approach
recommended here is based on standard instruments, procedures, and exposure
limits and it is believed to offer workers the best practical protection, in
light of current knowledge. It is also designed to minimize interference with
plant operations.
THE PLANT ENVIRONMENT
The open nature of some coal gasification pilot plants creates problems in
obtaining representative and realistic samples. There are difficulties in
choosing monitoring sites that will provide an accurate reflection of the
hazard level in light of changing environmental factors, especially air move-
ments. The problems are less at the enclosed plants (062 Acceptor, Bi-Gas);
furthermore, these processes do not produce the polycyclic aromatic hydro-
carbons (PAHs) that are of particular concern.
The process areas in a typical coal gasification facility have both unique and
common problems that will influence monitoring strategies. Some of the
unique aspects of process areas are described:
% Coal stock piles: Spontaneous combustion that may occur, influencing
sampling data from other areas
* Coal preparation: Noise associated with milling; airborne coal dust
generated by conveying and crushing procedures
• Gasification feed: Toluene slurry in HYGAS process
© Gasification: Possible high concentrations of carcinogenic materials
in the gas stream
• Methanation: Potential for formation of nickel carbonyl during
start-up and shutdown
» Waste disposal: Thermal oxidation that may emit S02
Exposure to Airborne Material
In an enclosed workplace, the concentration field of a contaminant is often
fairly constant during normal operation; there may be hot spots and relatively
clean areas, but their distribution does not change much. This means that a
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systematic sampling plan can adequately describe the exposure of a worker
assigned to one place or one who averages the concentration by moving about
the area. This is the situation existing only in the enclosed space at the
gasification plant.
Most of the potential sources of hazard are in open air and many man-hours are
spent outside. A point-source emission from a leak, eddying and dispersing
through the plant structure and downwind, will set up a very uneven and widely
fluctuating concentration field and the general distribution of this "hazard
zone" will depend on wind direction and other factors. Furthermore, small
differences in working routine may make large differences in worker exposure.
It follows that no practical array of sensors can adequately describe the con-
centration field and even if it could estimates of worker exposure would be
very unreliable. However, detection and measurement of point source emissions
are valuable in preventing wide area contamination and for initiating repair
operations before majcr effluent emissions occur.
Personal sampling could help to overcome both difficulties but reliable
procedures are available only for certain agents and not individually for the
carcinogens that are of major concern.
Exposure by Contact
Skin may be contaminated by contact with either surfaces soiled by leakage or
the interior of equipment during maintenance. The hazard cannot be quantified
because total exposure depends on chance circumstances. A realistic monitoring
program should identify the hazard and quantify potential exposure. This is a
check on system integrity. It is also a check on cleanliness and good house-
keeping.
Physical hazards such as heat and noise can be dealt with as in other
occupations, and there are many chemical hazards for which OSHA standards
provide a working basis: e.g., for carbon monoxide and hydrogen sulfide.
There is a possible complication here in multifactorial exposures, where a
simple additive approach may not be justified; however, in the present state
of knowledge, no alternative is available.
THE INDICATOR SUBSTANCE CONCEPT
A complete monitoring program must serve two purposes:
• To provide the information required to keep employee exposure at safe
levels, using techniques suitable for pilot plant conditions and
personnel
• To accumulate data to support the design of engineering controls to be
incorporated into demonstration and commercial gasification plants
The approach proposed here recognizes the need for a simple index to serve the
first purpose and it will provide useful data for the second. In this ap-
proach, a single substance acts as indicator for all the components of a given
process stream. The assumption is made that any leak of the indicator sub-
stance will be accompanied by a leak of each toxic constituent in the same
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ratio as in the process stream, so that a measurement of the indicator sub-
stance can do duty for individual measurements of each toxic emission. It
is recognized that this assumption may not always be valid and that it cannot
always be checked by experiment.
Indicators should have the following characteristics:
• Easily monitored in real time by commercially available personal
or remote samplers
• Suitable for analysis where resources and technical skills are limited
• Not present in ambient air at high or widely fluctuating concentrations
• Free from interfering substances in the process stream or ambient air
• A regulated agent, so that the measurements serve two purposes
Leading candidates for the indicator substance are carbon monoxide and
hydrogen sulfide, as one or the other is always a major constituent in gaseous
streams and both meet the criteria.
The rationale for adopting carbon monoxide (CO) as an indicator gas for
monitoring in confined areas and as the basis for alarm mechanisms in selected
areas is illustrated in Table 28. It can be summarized as follows:
a The concentration of CO is higher than that of other vapors and gases
of interest—NH3, H2S, and coal tar volatiles (BSFTPM).
e Available alarm and monitoring instrumentation can detect CO concen-
trations of approximately 0.2 mg/m3.
• Assuming that emissions from the gas stream will contain the relative
concentrations of CO to the other gases and vapors, the approximate
level of these can be calculated.
• When calculated, these levels can.be compared to existing exposure
standards.
Table 28 illustrates that CO serves as an adequate indicator of potential
hazard from process stream leakage in all areas except the pretreater, where
the benzene soluble fraction is indicated to be above exposure limits.
Although benzene soluble material is the major concern, it is not feasible to
choose it or a component of it as an indicator. Quick-response monitors at
the necessary sensitivities are not available for these compounds.
Carbon monoxide in particular should be an excellent indicator of system and
unit operation gas leaks throughout most gasification and downstream pro-
cesses. The level of CO at points of fugitive emissions (flanges, pumps,
seals, etc.) is high enough that it can serve as an effective indicator for
the presence of other toxic gas stream agents.
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Table 28. Ratio of CO to some gas stream components.
co
Stream Component
C02/C0a
Minimum detectable level C02, mg/m3i>
Concentration C02 as % OSHA exposure limit
NH3/COa
Minimum detectable level NH3, mg/m3i>
Concentration NH3 as % OSHA exposure limit
H2S/COa
Minimum detectable level H2S, mg/nr
Concentration H2S as % OSHA exposure limit
Light oil fraction/COa
Medium oil fraction/CO0
Heavy oil fraction/COa
Residual oil/CO (only 50% benzene
soluble)
Minimum detectable level as total
benzene solubles , mg/m3^
Concentration benzene solubles as %
OSHA exposure limit
13.4
2.6
0.03
ND
ND
ND
ND
ND
ND
0.32
1.75
1.28
ND
0.67
335
3.62
0.72
0.01
0.05
0.01
0.02
0.06
0.01
0.08
0.01
0.04
0.04
0.05
0.03
15
3.63
0.72
0.01
0.06
0.01
0.02
0.06
0.01
0.08
0.01
0.04
0.01
ND
0.012
6
3.60
0.72
0.01
0.02
ND
ND
0.06
0.01
0.08
0.01
0.05
ND
ND
0.012
6
6.61
1.32
•0.02
ND
ND
ND
0.09
0.02
0.12
0.01
ND
ND
ND
0.002
1
0.10
NDC
ND
ND
ND
ND
ND
ND
ND
0.01
ND
ND
ND
0.002
1
0.10
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
^Calculations are based on Synthane material balance sheet (Appendix C).
Minimum detectable levels are calculated using 0.2 mg/m3 as lowest concentration of CO detectable
^by available instrumentation.
No data.
-------
This method serves several purposes:
• It allows real-time detection of leaks.
• It serves as an indicator for substances that cannot be analyzed
in real time.
© It serves as an indicator for substances that are difficult or impossible
to analyze at prevailing concentrations.
A comparison of constituents of the overhead gas streams from different
gasification unit processes indicates that CO is usually present in high
concentration relative to other agents of interest. However, between the
pretreater outlet and the gasifier in the example shown, the concentration of
condensable hydrocarbons in the gas stream is substantially greater than at
any other point in the process. For this reason, CO concentration in any
emission from this part of the gas stream will not indicate the presence of
benzene soluble material with enough sensitivity. (Fortunately, this is a
small, simple vessel and the line is short: extra precautions might be
taken.)
Once the gas stream has been quenched in the venturi scrubber, the concentra-
tion of CO relative to condensable hydrocarbons will rise significantly as
water vapor and condensable hydrocarbons are condensed and removed. Although
its concentration fluctuates, CO remains a major constituent of the primary
gas stream until the final methanation step, which upgrades the gas to pipe-
line qual ity.
An area where a different indicator species must be employed downstream from
the acid gas separator, is the sulfur recovery unit. The gas stream in this
operation contains a high concentration of H2S and little, if any, CO. Thus,
the most suitable indicator will be H2S.
A significant consideration is that as the quality of the gas improves from
operation to operation, the CO concentration decreases. This decrease is
accompanied by an even greater reduction in the other toxic components. The
CO monitoring system is therefore most sensitive to a given leak rate where
the impact of a leak is most serious, and the probability of false alarms
from leakage of "clean" gas is diminished.
SAMPLING METHODS
Surface Contamination
If the contaminant contains condensed polycyclic hydrocarbons, search of
surfaces with a handheld UV lamp will make it visible by fluorescence. This
may be most conveniently done at night, with any nearby lamps temporarily
turned off or shaded. Alternatively, a portable, battery-operated ultraviolet
lamp (longwave and shortwave) could be used in a fabric-skirted box to permit
surface viewing in a brightly lighted environment. Problems stemming from
individual variation in dark adaptation and color sensitivity could be avoided
by using a photovoltaic detector and meter readout of fluorescence emission
intensity per ft2 of surface.
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Hazards inside equipment may be anticipated from knowledge of the process
stream's constituents. Finally, a UV scan of workers' clothing will indicate
whether the risk of contact contamination is real. This very nonspecific test
does not indicate either whether the compounds causing the fluorescence are
carcinogenic or whether a carcinogen might be present that does not fluoresce.
The general rationale, however, is that since the class of PAH compounds as a
whole exhibits fluorescence and members of the class are known to be carcino-
gens, this test gives an indication of the presence of suspect agents.
Personal Monitoring
It is recommended that the special problem of high-boiling carcinogens be
dealt with in the same way as coke oven emissions are dealt with in Title 29
CF.R 1910.1029 (Federal Register 1976a); that is, they should be measured in
aggregate, together with other benzene soluble compounds, as the benzene
soluble fraction of total particulate matter (BSFTPM) (see Appendix D).
The referenced standard presents the argument for preferring this measure to
alternatives such as using respirable particles as a basis or analyzing for
benzo[a]pyrene as proxy for the whole spectrum of carcinogens (Federal
Register 1976a). The standard is supported by epidemiologic evidence, which
is not available for gasification plants. In the absence of a better basis
for prescribing an exposure limit, it is proposed to assume that benzene
soluble matter found in gasification plants is sufficiently similar for the
coke oven standard to apply.
No exposure limits can be recommended for substances that may enhance carcino-
genicity. The effect may be significant but the required evidence is lacking.
However, it is recommended that efforts be made to minimize exposure to known
categories of enhancing agents wherever exposure to carcinogens is likely.
These categories include skin irritants, lung irritants, mineral particles,
and chemical potentiators such as phenol and dodecane.
ANALYTICAL METHODS
It is recommended that standard analytical methods, already approved or
recommended for other applications, be used whenever practical, e.g., for CO
and H2S; and that advances in technique be incorporated as appropriate, e.g.,
in analysis of the benzene solubles.
Analytical methods and instrumentation for CO and H2S monitoring are well
developed. These systems can provide the necessary sensitivity and reliability
for implementing the indicator substance concept.
Real-time remote sensing apparatus and portable handheld monitors operating in
a variety of modes are available from several sources. These are presented in
Appendix C.
Schulte et al. (1974) have considered a number of published analytical methods
for applicability to analysis of benzene solubles, PAHs, and BaP as obtained
from coke oven emissions. Benzene soluble extract was determined based on a
weight difference of a filter before and after Soxhlet extraction with hot
benzene. Comparison was also made with PAH content (14 compounds) as
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determined by gas chromatography and with BaP separated using thin layer
chromatography and measured fluorometrically. They found a high degree of
correlation between BaP concentration and benzene soluble concentration when
samples were collected by a high volume (HIVOL) sampler and the horizontal
elutriator.
The gas chromatographic (GC) determination of PAH compounds did not correlate
well with benzene solubles. It is possible that analytical methods based on
gas chromatography introduce opportunities for material losses or gains and
chemical reactions ultimately affecting the "signal" ascribed to BaP. Oxida-
tion of PAHs becomes much more significant with increasing duration of
exposure to light, air, and heat (Lannoye and Greinke 1974).
Particularly significant to this document is the finding that BaP by thin
layer chromatography (TLC) is highly correlated with the benzene soluble con-
tent of particulate matter collected on either a high-volume sampler or a
horizontal elutriator (Schulte et al. 1974). Extremely poor correlation was
observed between all methods for BaP and benzene solubles from samples
collected with cyclones or membrane filter field cassettes.
Although the authors of the NIOSH study chose not to speculate on the manner
in which methodology affects sample composition, it is possible that some
selection process operates where either air washing of volatiles or filter
fouling occurs. High surface area collectors, e.g., glass fiber filters,
permit greater air washing of the trapped particulate matter during collection,
and it is not surprising to lose more volatile "benzene solubles" relative to
less effectively air-washed systems or fouled filter systems.
Results have been published of studies on the problems associated with Soxhlet
extraction for determining coal tar pitch volatiles (CTPVs) (Seim et al. 1974).
They showed that weight loss errors can be appreciable when ultrafines are
present (as in aluminum smelter operations). Adipates or other plasticizers
in membrane filter cassette housings add to the weight loss noted after Soxhlet
extraction. Units with polystyrene housings are preferred over those with
cellulose acetate or polypropylene housings.
It is not proposed at present that BaP be monitored as part of the worker
protection program. If it is required as part of a research project or in a
future modification of the program, recent advances in technique may be ap-
plied. Although BaP exhibits violet fluorescence, the protonated species
exhibits a bright green fluorescence, which is used in the APHA tentative
method for BaP. The protonated species is formed in concentrated sulfuric
acid. Lannoye and Greinke (1974) have suggested many improvements in the
APHA tentative method for BaP. By implementing these suggestions into the
procedure, it is possible to obtain a relative standard deviation of 3.5% to
6.2% over the range from 14 to 400 yg BaP. However, their implementation
requires both exceptional analytical capability and an exceptional laboratory
facility, not normally available at a coal gasification plant. It may also
be noted that PAHs in coal dust could interfere.
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MEDICAL MONITORING
SCOPE
This chapter discusses and recommends medical monitoring procedures for
workers at coal gasification pilot plants. It is directed to the physicians
responsible for monitoring and also to others, such as plant management and
policy makers, who wish to understand the general purpose and nature of the
recommended medical procedures. Consequently it is written for a dual audi-
ence. For example, respiratory function tests are recommended, specifically
FVC and PEM^. "Respiratory function" explains it sufficiently for the layman
and there is no need to expand on FVC and FEVX for the physician.
The chapter on health effects has identified known and suspected toxic agents
and their health effects. Heat and noise stresses have also been discussed.
The more conspicuous toxic hazards include polynuclear aromatic hydrocarbons
and other carcinogens such as g-naphthylamine and benzidine, nitrosamines,
and possibly nickel carbonyl. Compounds capable of potentiating carcinogen-
esis include acridines, dodecane, sulfur oxides, and other irritants such as
phenols. Organs conspicuously at risk are the skin, the lung, and other
parts of the respiratory tract and the genitourinary system, especially the
bladder.
Effects other than cancer are significant. The skin may develop" dermatitis
or photosensitization. Nonmalignant respiratory effects include chronic
bronchitis, emphysema, and possibly pneumoconiosis. The liver and central
nervous system (CNS) may be at risk from aromatic amines such as aniline.
CNS effects are induced by phenols, carbon disulfide, and carbonyls. A
highly specific hazard is benzene, which is myelotoxic and leukemogenic.
Mutagenic and teratogenic effects are a possibility which must be borne in
mind because of the serious consequences. Exposure to some suspect classes
of compounds is possible.
The purpose of the foregoing very brief review is to help focus on the major
targets for medical monitoring and to identify the organs at risk. This
supports an orderly and convenient approach to medical monitoring on an organ-
by-organ basis.
It should be borne in mind that the discussion and recommendations are gener-
alized for all coal gasification plants. The physician at any particular
plant must consider what specific exposures might be expected. These can be
identified from chemical engineering data and perhaps workplace monitoring.
He should also consider individual risk of exposure based on job description.
This kind of information will permit tailoring of medical tests: for example,
possible exposure to aromatic amines should suggest addition of a liver func-
tion test to the recommended basic examination.
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OBJECTIVES
A preemployment physical, routine checkups, and a physical on termination are
common practice in industry. Medical monitoring has considerable added im-
portance at coal gasification plants because it is not possible (and may
never be possible) to assure "safe" exposure by application of controls or
environmental monitoring. Another reason is that health effects may show up
after a long latent period, perhaps long after exposure has ended. A third
reason is that some of the possible ill effects would develop inconspicuously
at first; that is, they would not clamor for immediate attention. Conse-
quently, regular and continued medical monitoring is needed as a warning
system, so that emerging problems will be dealt with at the earliest possible
time.
The primary purpose of medical examination is to protect the examined worker's
health, during a period of occupational exposure and thereafter. There is
also a valuable by-product in that medical records will help to protect the
health of other workers, at different plants and in the future. Accumulated
knowledge of occupational health is the best input to development of recom-
mended procedures for protection of workers' health. Medical records and
associated histories of working exposure should therefore be prepared and
held with this in mind. Development of the present document would have been
considerably helped if past records and follow-ups had not been scanty or
nonexistent; although the recommendations might not have been different, they
would certainly have rested on more solid evidence.
In summary, the recommended scope of medical monitoring includes:
» full preemployment physical, including history and laboratory tests,
which serves three purposes — a general check on fitness, identifica-
tion of high-risk individuals so that they may be advised, and a
baseline for further routine examinations;
9 regular checkups, more frequently and in more detail for high-risk
individuals (those with 5 years gf exposure or over 45 years of age);
e long-term follow-up of high-risk individuals after transfer to other
job categories for termination; and
9 full record keeping, including work history and exposure data.
It should be remembered that full medical surveillance requires good liaison
between the occupational physician and the individual's private practitioner,
so that untoward signs may not be neglected.
MONITORING NEEDS
As Dixon (1973) has emphasized, "Humans want to be medically tested rather
than biologically monitored" and measuring only the "health of the air" is
unsatisfactory. Bioassay and area monitoring alone are clearly not suffi-
cient. When one reviews the natural history of the development of cancer
(Kotin 1976), the need for medical surveillance is obvious. The time,
place, or amount of exposure which causes the initial interaction between
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the carcinogenic agent and the host cannot be precisely determined. No spe-
cific biomedical markers can be identified in tissues indicating that initi-
ation has occurred. When tissue responses become detectable, they are usually
nonspecific and often not pathognomonic. Once initiation and even transfor-
mation have occurred, a long latent period, sometimes lasting 20 to 30 years,
occurs. During this time other factors, such as age, sex, genetic abnormali-
ties, exposure to promoters or to hormonal agents, and injuries which cause
tissue proliferation may determine if cancer will ever appear. Under such
circumstances, only periodic clinical evaluation will determine if exposures
are causing an increased incidence of tumors.
Medical monitoring is also an essential part of worker protection against the
consequences of chronic exposure to noncarcinogens.
A relatively small number of workers (probably less than 5,000) have been
employed at coal conversion pilot plants in the United States during the
past 20 to 25 years. They have not been carefully monitored and their ex-
posures may have been fairly high. Even though their future exposures may
be at "safe" levels, the effects of past exposures must be followed. Since
what is "safe" is not known, it would also seem prudent to monitor new em-
ployees under new working conditions very thoroughly until enough experience
has been obtained for management to be comfortable in reducing medical sur-
veillance procedures.
A part of worker protection must come from adequate follow-up after exposure
in hazardous areas. The information gained in this as well as routine occu-
pational examination should be used not only for the workers' immediate pro-
tection but also to enhance knowledge generally for the protection of others.
The value of all medical monitoring in its broader application will be en-
hanced by having suitable control populations, followed in a closely similar
manner. Offering the same surveillance program to all employees at a plant
has obvious advantages for employee relations and may incidentally furnish
an adequate control population even if the numbers are relatively small and
their characteristics do not match closely.
Evaluation of medical records may on occasion be facilitated by comparison
with those from other similar locations and this will be more effective if
the data have been collected and recorded in the same way. Uniformity would
also permit aggregation to form a larger and more useful historical data base.
In this connection, and also for individual protection in long-term follow-up,
it is recommended that a national system be set up to preclude loss or in-
accessibility of records if, for example, a plant closes.
EFFECTS ON ORGAN SYSTEMS
Possible health effects are reviewed here with reference to the affected
organ system. This is for convenience in developing medical monitoring
procedures for specific circumstances, in conjunction with reference to the
presentation of health effects by specific compounds in an earlier chapter.
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Skin Effects
Nonallergic dermatitis, cell-mediated hypersensitivity, cutaneous photosensi-
tization, acne, premalignant lesions, and malignant lesions have been associ-
ated with PAH exposures (National Academy of Sciences 1972). At the Union
Carbide plant in Institute, West Virginia, skin cancers and premalignant
changes were seen sometimes after a remarkably short latent period of less
than 5 years (Sexton 1960b). Since these changes are not specific and a
possible association with occupational exposures could easily be missed in
random observations by scattered individual private practitioners, close
medical surveillance by one or very few trained and interested observers is
necessary. Longitudinal observation over a period of years enables a skilled
physician to become familiar with the texture, appearance, and disease
problems of the skin in a small group of workers.
Appearance of skin cancer may be a warning sign for later cancer in the re-
spiratory and upper digestive tracts. Holmes et al. (1970) reported a sig-
r if'cant association of these effects in men who had had scrota! cancer.
This is an important point in follow-up of cases.
Noncarcinogenic skin effects that may be encountered in exposure to agents
other than PAH are irritation and sensitization.
Lung Effects
The National Academy of Sciences (1972) stated that "in no instance has ex-
posure to a specific polycyclic aromatic hydrocarbon been proved to have
caused a tumor in man." Although this is strictly true, the evidence of an
increased risk of lung cancer in coke oven and roofing workers exposed to
PAH is impressive (Menck and Henderson 1973; Lloyd 1971) and medical sur-
veillance is clearly obligatory.
PAH compounds in coal conversion processes may be adsorbed on fine particles,
a good portion of which may be 0.5 ym to 2.5 ym in diameter and therefore
"respirable." It has been shown that many inhaled compounds can have a
ciliostatic effect, which could increase the length of time of exposure in
the lower respiratory tract. Even if particles contaminated with tars are
cleared fairly rapidly from the respiratory tract, leaching has been shown
to occur, which suggests that the PAH material is retained even though the
particle may be cleared. The fate of the leached material is still unknown
(National Academy of Sciences 1972). In animal experiments, inert particles
such as hematite (Saffioti et al. 1968) or carbon (Pylev 1967) have had to be
inhaled in order to produce lung cancers.
Among other effects is acute irritation, which may be caused by a wide range
of possible emissions (ammonia, hydrogen chloride, sulfur oxides, nitrogen
oxides, phenols, etc.) and might be associated with cancer promotion. Acute
and chronic respiratory dysfunctions are known effects of some trace elements
which are likely to be present, especially vanadium and also beryllium,
cadmium, and manganese. Dusts of silica, limestone, and coal can induce
pneumoconioses.
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Urinogenital Effects
An excess of bladder and kidney cancers has been reported for workers exposed
to coal gas, tar, and pitch (Redmond et al. 1972; Doll et al. 1965). These
tumors are relatively rare and have a long latent period. Early detection
and treatment usually improves the prognosis. A requirement for medical
surveillance using urine cytology has appeared in the Coke Oven Emissions
Standard (Federal Register 1976b).
A range of aromatic nitrogen compounds has been shown to cause kidney injury.
Several of the possible trace elements have been similarly implicated:
beryllium, cadmium, lead, mercury, and selenium.
Blood and Blood-forming Tissue Effects
Leukemia and myelotoxicity are associated particularly with exposure to
benzene (NIOSH 1976a). Carbon monoxide induces carboxyhemoglobinemia and
aniline induces methemoglobinemia. Anemia is a characterisitic sign of lead
and selenium poisoning.
Cardiovascular Effects
Chronic exposure to carbon monoxide has been said to cause or aggravate
cardiovascular disease. Carbon disulfide has similarly been implicated in
cardiac disease and hypertension. Among the trace elements, chronic mercury
poisoning is characterized by cardiovascular disease and other effects.
Liver Effects
Aromatic amino compounds (e.g., aniline) and N-heterocyclic aromatics (e.g.,
pyridine) are possible sources of hepatotoxicity among coal conversion
products if exposure is high enough. Liver function and serum transaminase
tests should be considered for inclusion in routine examinations if this is
suspected. Among the trace elements, beryllium and selenium affect the
liver.
Central Nervous System Effects
Carbon monoxide at a sufficient exposure level may produce characteristic and
reversible signs of hypoxia; no persistent effect on the CNS has been proven,
short of damage through severe hypoxia. Several other possible contaminants
induce acute and probably reversible CNS effects: hydrogen sulfide, carbon
disulfide, carbonyl sulfide, phenols, and carbonyls. Prolonged or permanent
damage may be associated with chronic exposure to lead, mercury, and selenium
PREEMPLOYMENT ASPECTS
Acquiring knowledge of the general health status of prospective employees is
prudent for several reasons. In addition to the usual criteria of physical
fitness, individuals with blonde or red hair and pale complexions will need
to be evaluated for high risk of skin cancer. Individuals with existing
chronic lung disease or marked atypia in cells exfoliated from their bron-
chial mucosa may have enhanced susceptibility to lung cancer. Individuals
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with abnormal urine cytology or a history of a bladder papilloma or tumor
will need to be evaluated for risk of carcinoma of the bladder or urinary
tract.
A preemployment examination provides an important baseline for future exami-
nations. For this reason, as well as the high-risk indicators just mentioned,
it is essential for the examiner to be aware of the special purposes of the
examination and the nature of possible health hazards. Since pilot plants
usually do not have their own occupational health physicians and are likely
to depend on outside general practitioners, transmission of the necessary
information should be a stated responsibility of plant management. A point
to be emphasized is the desirability of obtaining as full an occupational
history as possible, including past exposures to chemical and physical
stresses, and also details about smoking and drinking.
The Federal Register (1976a) contained a recommendation for both urine and
sputum cytology for coke oven workers. The former is more generally accepted
as a routine monitoring tool, but only if the preparation and evaluation are
done expertly and by established methods. Sputum cytology is more contro-
versial and more likely to be misleading unless in expert hands. However,
both techniques have the obvious advantage of generating a permanent record
(microscope slide) that can be reexamined.
Sputum cytology may be performed according to the technique of Saccomanno et
al. (1974). The cytologist must be experienced in classifying degrees of
atypia. The sputum may be collected spontaneously if the worker can produce
a deep-cough, morning specimen. Sputum induction, using inhalation of a
fine aerosol of 20% propylene glycol and 15% saline, can provide an
excellent specimen. At least two sputum cytology studies should be performed
to assure an adequate sampling of cells exfoliating from the bronchial
mucosa. Individuals with marked atypia (or, of course, those with carcinoma
in situ or invasive carcinoma cells) should be carefully evaluated before
being employed. Those with marked atypia who are cigarette smokers are at
increased risk of developing a future lung cancer.
OCCUPATIONAL AND POSTOCCUPATIONAL ASPECTS
The physical examination should pay particular attention to the skin. Actinic
effects and the presence of benign or premalignant lesions should be carefully
noted. Suspected malignant lesions should be removed and their histology
documented. A high quality, close-up color photograph (slide) of the skin,
especially of the face, neck, and hands, is probably the only adequate way
of documenting the appearance of the skin. The lungs should be evaluated
for the presence of rales or rhonchi, suggesting a chronic bronchitis. A
general examination should be carried out.
Laboratory studies should include posteroanterior (PA) and lateral (14" x 17")
chest X-rays, weight, pulmonary function (a minimum of FVC and FEVj, and a
routine urinalysis. An ECG and multiple serum chemistries are desirable,
especially if the applicant is over 40.
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The frequency and extent of examination should reflect the degree of need,
which depends on duration and extent of past exposure, expected future ex-
posure, and personal characteristics such as age and medical history. The
skin should be examined at least once a year, preferably during the winter
months when effects of current ultraviolet light exposure are less apparent,
but complete physicals might be acceptable at less frequent intervals for
low-risk individuals. Recommended schedules are given in the next section
of this chapter.
A termination physical examination with the same content as the regular
complete examination should be performed when a worker leaves if a complete
examination has not been performed in the preceding year.
RECOMMENDED PROCEDURES AND SCHEDULES
It is recommended that a preemployment medical examination be required for all
before hiring. All workers should be offered regular examination and a
signed statement should be obtained from those who refuse it. Individuals
judged to be at significantly higher than average risk because of personal
factors, work history, or expected future exposure should be advised by a
physician before signing the release.
Basic Procedures
The following should be included in the initial examination but not neces-
sarily in all subsequent examinations: skin examination; X-ray, 14" x 17"
PA and lateral; FVC and FEV}; weight; blood chemistry; urinalysis including
test for hematuria-
Additional Procedures
It is recommended that consideration be given to additional procedures such
as an ECG, especially for high-risk individuals. Exposure to certain toxi-
cants calls for special procedures: e.g., liver function test for workers
exposed to aromatic amines.
The recommended basic and additional procedures are not intended to exclude
further tests. The physician will of course consider other aspects such as
physical fitness for heavy manual work.
Schedule for Normal-risk Individuals
This applies to all exposed workers except the high-risk category defined
below. Annual examination is recommended, to include: skin; X-ray; FEV and
FVC^; weight; urinalysis; cytology.
Schedule for High-risk Individuals
Workers who have accumulated 5 years of exposure or are over 45 years old
should be considered as a high-risk group. The job categories which con-
stitute "exposure" must be determined in the light of environmental moni-
toring records, work practices, prevalence of leaks, etc. Six-monthly
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examination should include: skin; FEV and FVCV, weight; serum analysis;
urinalysis; urine cytology; sputum cytology. X-ray examination should
continue to be annual.
RECORD KEEPING
Medical Records
Following are the minimum recommended scope and duration for keeping medical
records on file:
• Medical history on employment: 40 years
• Initial X-ray and cytology slides: 40 years
• Abnormal X-ray (if any) and all subsequent X-rays: 40 years
• Cytology slide showing atypia (if any) and all subsequent slides:
40 years.
• All X-rays for the last 5 years and cytology slides for the last 10
years
Exposure Records
The physician responsible for filing medical records should obtain from the
plant management, and file with the relevant medical records, a record of
each worker's job history. This work record should be adequate to support
an estimate of level of exposure and nature of toxic or physical agents
involved. Adequacy will depend on circumstances; suggested criteria include
the following:
t Full history of workstation assignments exceeding 1 month, for
single-station workers
• Principal areas of work, for mobile workers
t Work history obtained at preemployment or other examination or interview
Summary Reports on Environmental Monitoring at Relevant Workstations
The full monitoring data should be kept on file but preferably not with
the medical records; the summary reports are necessary to determine whether
the environmental data files should be searched in event of a retrospective
investigation.
Special records of heavy exposure to substances retained inside equipment
may be desirable when maintenance operations are carried out or when modi-
fications are implemented. The decision to include these would depend on
identification or strong suspicion of the presence of toxic hazards, as
determined by chemical analysis or biological test.
Exposure records should be kept as long as medical records; i.e., 40 years.
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SAFETY
INTRODUCTION
The development of recommended safety guidelines for coal gasification pilot
plants is complicated by the great variety of processes and facilities planned
and now in use as well as by the dearth of information available on existing
safety procedures. This situation makes necessary a process-by-process over-
view of hazards followed by comprehensive safety program recommendations that
take into account applicable existing regulations.
In general, process development or pilot plant installations present more
unpredictable hazards than fully tested production-scale facilities, simply
because they are essentially large laboratories where equipment and process
conditions are examined on an experimental basis. As a consequence, opera-
tions are cycled up and down frequently and the plant as a whole is shut down
for maintenance much of the time while equipment is inspected, repaired,
modified, or replaced. Hazards encountered during maintenance are always a
major concern in large chemical plants. This problem is accentuated in pilot
facilities. Further, the many process variables encountered in pilot plant
production runs may contribute to unusually high vessel and piping erosion
rates as well as unexpected overpressures and overheating.
This chapter will attempt to identify the hazardous conditions that may be
present in a typical coal gasification pilot plant and will present recommen-
dations for control of these hazards. Alternative safety implementation pro-
grams and their relative merits will also be discussed.
OVERVIEW OF HAZARDS
The first unit operation encountered in the coal gasification plant is coal
crushing and grinding. This is usually accomplished in a dry mill at feed
rates of up to 5 tons per hour. In operations that do not dampen the coal in
the crusher to minimize dust, the grinding areas may show substantial con-
centrations of coal dust in the air, and surfaces in the vicinity will be
subject to dust buildup.
Such conditions can result in the possibility of a deflagration of suspended
dust and of subsequent deflagrations of dust dislodged from rafters and other
surfaces. The likelihood of coal dust explosions is dependent on several
factors, among them the presence of a suitable ignition source, the type of
coal used, the coal's moisture content, the particle size and shape, uniformity
of dust particle suspension, and ratio of dust concentration to oxygen content
of the gas. The most hazardous form of coal dust found in these operations is
fines from heat-dried lignite, which is highly pyrophoric in air; however,
there is a hazard in the use of other coals such as bituminous, sub-bituminous,
and anthracite.
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The next process downstream in certain operations is pretreatment of the
crushed coal prior to its introduction into the gasifier. Here the coal is
heated to around 800°F (545°C) while blanketed with recycled gas and/or steam.
Sufficient air is metered in to maintain temperature. The major hazardous
condition at the pretreater occurs when samples of coal from the pretreater
are collected. This is done by opening a valve in the bottom of the pretreater
vessel and handling the hot coal in a sample can. There is, therefore, the
hazard of burns either from direct contact with the hot coal and sample can or
from the fire that may result if hot pyrophoric coal is spilled because of
sample valve failure. Coal samples from the pretreater are collected from
once a day to as frequently as several times per shift to determine the
moisture content and overall quality of coal going into the gasifier.
Some gasification processes require that oxygen be metered into the gasifier
to maintain process temperatures. Liquid oxygen is trucked to the site and
stored in tanks adjacent to the process area, prior to being vaporized and
introduced under pressure into the gasifier. The hazards associated with
handling liquefied oxygen are well known and safe work practices have been
developed (The Applied Physics Lab 1963). The major an-site hazards are
accidental overheating and rupture of the oxygen tank, and failure of auto-
matic controls, due to the excess oxygen metered into the gasifier.
The primary fire hazard in the gasification process is the gasifier unit,
because of the high pressures and temperatures at which it operates combined
with the combustible and abrasive nature of the gasifier effluents. Pipes
carrying crushed coal or char into or out of the main gasifier vessel are
particularly susceptible to erosion, overheating, and rupture. Such ruptures
force hot process gases into the atmosphere at high pressure. These can ignite
immediately, resulting in dangerous but largely self-contained gas fires.
Additionally, the escaping gases can drift several hundred feet before igni-
tion, creating a serious explosion potential. The routine procedure of
manually sampling gasifier bed solids is particularly vulnerable to starting
leaks. This sampling procedure may be accomplished by screwing a steel
cylinder "shot pot" onto a sample tee, opening a valve, and allowing the
cylinder to fill with solids. The valve is then closed and a cooling down
period of 40 to 60 minutes is allowed, after which a valve in the bottom of
the cylinder is opened and the solids are collected in a sample can. If the
valve at the sample tee has failed to reseat properly because of the intense
heat, process gases may then escape into the air and ignite, presenting a
hazard to workers in the area. Use of a double valve sample train eliminates
many of the leak hazards.
Failure of automatic process control systems may also result in hazardous
conditions, especially if failure results in overheating of vessels and piping
due to insufficient water jacket cooling or introduction of excess oxygen into
the gasifier. However, redundant instrumentation and "fail-safe" design can
reduce these hazards to a negligible level by providing for emergency shutdown
when process parameters exceed preset limits.
Downstream of the gasifier is product gas quenching and scrubbing, described
in detail in the chapter on processes. During normal operations samples of
quench water are taken manually about once every shift. This can be a
hazardous procedure, as hot quench water spilling on exposed skin can cause
burns.
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In the remaining downstream processes of shift conversion, acid gas scrubbing,
sulfur removal, and methanation, highly combustible gases are being processed.
The possibility of these gases' escaping into work areas creates potential for
fire, explosion, and acute toxicity (e.g., CO and H2S).
Many potentially hazardous conditions exist in pilot plants because of the
frequent maintenance and process equipment modification work required as a
process is developed. In the following analyses, frequently encountered
situations are discussed and general guidelines for safety in maintenance and
modification work are presented.
In any maintenance procedure that requires a vessel, duct, flange, valve, pump.
or compressor to be opened the potential hazard is present for the release of
toxic and/or combustible gases or solids into the work area. Many factors
contribute to the possibility of such a release, especially the incomplete
isolation and purging of the involved system prior to its opening. Even when
a thorough purging of gases is carried out, workers entering the vessel or
piping may be exposed to toxic and/or combustible mixtures because of adsorbed
gases from solid particles remaining in the purged space. Pulverized coal or
char is a particularly good adsorbent of many gases and its presence in the
gasifier vessel contributes to this problem. Tight bends and blind sections
of piping can also harbor high concentrations of acutely toxic and flammable
gases. Additionally, the possibility of an accidental release of gases from
another part of the system into the part undergoing maintenance creates a
hazard.
Whenever vessel entry by maintenance personnel is required, there is a poten-
tial for simple asphyxiation because of the lowered 02 concentrations. Heat
stress may also occur if the vessel has not cooled completely to ambient
temperature. (A gasifier that normally operates at 3000°F will require at
least 3 days to cool down to ambient temperature.)
Welding and cutting operations can be particularly hazardous in coal gasifica-
tion plants because of the variety of combustible materials in the plant area.
Coal dust, process gases, methane, concentrated oxygen, and certain coolants
(e.g., diphenyloxide) used in heat-exchange systems all present combustion or
explosion hazards, particularly when the ignition source is a 6000°F welding
arc or flame.
General safety considerations in maintenance operations include the necessity
of properly isolating the work area to prevent entry by unauthorized persons,
proper shielding of welding and cutting operations, the provision of easily
accessible fire fighting equipment and breathing apparatus, provisions for
orderly evacuation in emergencies, and the ready availability of first aid
and medical care.
It is absolutely necessary to develop and enforce safe operating practices
during start-up and shutdown of the plant. Hazards inherent in start-up
include incomplete isolation of the system from its surroundings due to open
valves and leaks from flanges, vessel ports, and tie-ins. Such leaks are
likely to be found at start-up because maintenance operations are usually
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performed during shutdown; therefore, the system has been opened; valve posi-
tion sensors may have been disconnected; and the system may have been incom-
pletely resealed following the work. Hazards arising from shutdown involve
the incomplete purging of the system and the possible entrapment of process
gases in one part of the system due to faulty valve operation.
RECOMMENDATIONS
General
Recommended safety standards for coal gasification pilot plants will be most
effective if a detailed safety clause is included in all labor contracts which
specifies the safety regulations and practices that are to be followed and
where the responsibility lies for their implementation. This emphasis on
safety in contractual agreements should be carried through with the establish-
ment of an independent safety section within the company, with its own budget,
and supervised by a competent, full-time professional safety manager who is
responsible for the thorough implementation of the safety program. (The
part-time employment of safety consultants to fill the post of safety manager
or safety engineer is clearly inadequate to deal with the comprehensive safety
programs outlined here.) This implementation would include safety analyses at
the design stage of the plant, rigorous enforcement of safe work practices
during construction, indoctrination of employees via imaginatively designed
safety training courses, and use of complete system of accident and "near
miss" reporting for internal use. The recording of "near miss" hazardous con-
ditions and minor injury accidents is rarely done in industry but it is
essential in pilot plant operations, which have very little previous safety
information to work with. Continuing analysis of detailed internal accident
reports is particularly important to an effective safety program, as it can
allow potential hazards to be identified before a serious accident occurs.
Further, a job safety analysis should be conducted by the safety supervisor
for each operation in the plant to pinpoint specific hazards unique to each
job and to aid in the development of appropriate work practices. Figure 22 is
a sample form for such an analysis (Battelle Northwest Laboratory 1976).
Because of the wide variety of processes under development in various pilot
plants, it is essential that the managers and operators of each plant have a
clear and detailed picture of all potential hazards that exist in each area of
the plant. Although many hazards are common to all plants and can be pin-
pointed and analyzed in a document such as this, only a systematic review of
hazards conducted by the operating company, preferably during the design phase
of plant development, will give a sufficiently complete overview of problem
areas. The analysis should include, but not be limited to, discussion of
procedures for operational start-up, normal onstream operation, shutdown, and
emergency. The requirement of such a "system safety analysis" will impose a
disciplined and inclusive approach to safety considerations. It should assure
proper safety engineering in equipment design (MacNab 1975) and eliminate any
inconsistencies in the safety equipment or in safety procedures. This type of
analysis should be utilized throughout the life of the plant whenever new
equipment or procedures are contemplated. (The Fault Tree Analysis for safety
and reliability [e.g., the Lapp-Powers Fault Tree Synthesis Algorithm] or its
equivalent is recommended as such an approach.)
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JOB HAZARD
BREAKDOWN
JOB DESCRIPTION
COM PONENT
JHS NUMBER
BUILDING
REVIEWED BY
INDUSTRIAL SAFETY
PREPARED 8Y
IN ITI ALS
REVIEW DATES
SAFETY EQUIPMENT REQUIRED
TOOLS * EQUIPMENT REQUIRED
JOB PREPARATION
HAZARDOUS MATERIALS
RELATED REQUIREMENTS
RADIATION WORK PROCEDURE YEsf 1 NO I1
•JUCLEAR SAFETY SPEC. YES P"! NO [~~j
JOS STEP
SAFETY RULES AND SAFE PRACTICES
PAGE I Of
S4-gooo-tzo (1-70)
Fioure 22 . Job safety analysis sample form.
129
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This requires that all responsible departments —process engineering, me-
chanical engineering, safety engineering, maintenance, operations, and plant
management — become involved in this decision analysis process. An example
of this procedure, applicable to coal gasification pilot plants, is now
available (Wilson 1976).
Control of Specific Hazards
The dust hazard in coal grinding operations already described is controllable
by a combination of careful maintenance of adequately designed crushing equip-
ment, and daily emphasis on wash-down of collected dust. If a coal crushing
pneumatic coal conveying system is property maintained, with either a venturi,
scrubber or baghouse for the removal of fines, there should be a minimum
amount of dust in the surrounding area. Daily spray-down of structures and
floors in the crushing and grinding area will minimize the possibility of
dislodged dusts creating an explosion or fire hazard. Hinged pressure-
release doors should be provided on ducting to the crusher and grinder to
minimize the potential danger of rupture in the event excessive oxygen concen-
trations result in an internal dust explosion.
Recommended safe practices for various sampling start-up and shutdown proce-
dures are outlined in the next part of this chapter. These procedures were
described in the course of a personal communication with Mr. Kenneth M. Martin,
safety consultant formerly with Steams-Roger Corporation. The following is
a generalization of several different sampling procedures that were developed
over a 4-year period at an operating pilot plant (C02 Acceptor); they will be
implemented at another (Bi-Gas). This experience produced sampling techniques
with a high degree of safety and reliability.
Sampling of Reactor Solids
Purpose--
Solid samples are to be obtained from different bed levels in order to
determine degree of coal gasification, solids size, solids distribution, and
degree of calcination (C02 Acceptor).
Process Sample--
Fluid-bed solids are collected through gasifier and regenerator levels (C02
Acceptor).
Process Conditions--
The temperature range should be 1500° to 3000°F (814° to 1650°C), the pressure
level 150 to 1500 psi.
Sample Container--
A steel cylinder should be used. It has a screwed nipple on one end, and a
valve on the other. A prepurged 1/2-gallon container will also be required.
Number of Workers--
Two workers are needed.
Worker Apparel--
Hard hats, asbestos gloves, face shields, coveralls, safety shoes or other
protective footwear are worn.
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Procedure—
One operator is stationed within 10-15 feet of the sample point near an alarm
button. The alarm button activates the emergency shutdown procedure (as de-
scribed later) in case of mishap. The second operator screws the sampling
cylinder onto the sample tee and then opens a manual valve, allowing the
cylinder to fill with solids. The manual valve is closed and the operators
may leave the area during a cooling down period of 40 to 60 minutes. The
operators then return, resume positions, and open the valve at the bottom of
the cylinder in order to release the collected solids into the container. The
container is then sealed. The cylinder is purged and unscrewed from the sample
tee.
Hazards--
Repeated exposure to entrapped gases or vapor may be harmful. Use of an
appropriate respirator should be required.
Process gas leaks due to the freezing of valves by intense process heat can be
hazardous. Operators should first attempt to close manual backup valves
upstream of the sample point. If this is unsuccessful, the hydraulic emergency
valve is closed. If this also fails, both operators should leave the area
immediately, and activate the alarm to initiate emergency shutdown procedures.
Simultaneously, emergency crews are dispatched to the area — dressed in proper
clothing — to begin wetting down structures or discharged solids (see later
discussion of "Fire").
Hot Coal Sampling
Purpose—
Hot coal analysis.
Process Sample--
Coal is to be collected.
Process Conditions--
Temperature should be set at 500°F (260°C); 10 psi is the proper pressure.
Sample Container--
Prepurged 1/2-gallon can.
Number of Workers--
One worker is required.
Worker Apparel —
Hard hat, face shield, coveralls, asbestos gloves, and safety shoes or other
protective footwear should be worn.
Procedure--
The can is placed under the sample tap and opened. Then the process valve is
opened for a sufficient time — 15 to 30 seconds — to allow partial filling
of the container. The container is immediately sealed and is not reopened
until the coal has cooled.
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Hazards--
Under these conditions there is a small possibility that the sample will ignite
spontaneously. Further, the hot gases at this temperature are predominantly
inert, containing little or no toxic material. If the valve should freeze,
hot coal will spill onto the floor. This will begin to smolder or ignite
after 3 minutes. The sample line should contain a double valve, and a fire
extinguisher should be readily available.
Cool or Cold Gas Sampling
Purpose--
To collect product gas analyses.
Process Sample--
Gas streams except methanated gas stream.
Process Condition--
The temperature should be below 400°F, process pressure.
Sample Container--
Evacuated metal sample bottles.
Number of Workers—
One worker is required.
Worker Apparel--
Hard hat, coveralls, gloves, face shield, and safety shoes or other protective
footwear should be worn.
Procedure--
Sample container is attached to sample port and container is opened; valve is
partially opened to permit container to equilibrate. Close both the sample
valve and the sample container.
Hazards--
Inability to close sample valve may result in a container leak, releasing
gases to atmosphere and operator breathing zone. The danger of fire is small
because of the low volume and low temperature of the gas. If the leak does
occur, the operator should put on breathing apparatus (located conveniently
to all sample ports) and attempt to plug the leaking fitting. If this fails,
emergency shutdown procedures should be initiated.
Quench Water Sampling
Purpose--
To determine process efficiency.
Process Samples--
All water quenching or water scrubbing processes should be sampled.
Process Conditions--
Should be below 110°F (55°C), process pressure.
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Sample Container--
A closed can is used.
Number of Workers—
One worker is required.
Worker Apparel--
Hard hat, coveralls, safety shoes or other protective footwear, gloves im-
pervious to aromatic hydrocarbons, and safety goggles should be worn.
Procedure--
Attach sample can to sample port and open can. Open sample valve to partially
fill the can. Close valve and cover can.
Hazards--
The primary hazard results from splashing. The quench water will contain
contaminants which can cause dermatitis. It may also contain hydrocarbons at
low concentrations. In the event of a splash on the operator's skin or
clothing, the operator should shower and change clothes.
Slurry Sampling
Purpose--
Stream constituents are to be analyzed.
Process Sample--
Any of the circulating tar streams or gasifier feed streams should be sampled.
Process Conditions--
Temperature should be ambient to 450°F (232°C), and process pressure should
be maintained.
Sample Container—
Double-valve metal cylinder is used.
Number of Workers--
One worker is required.
Worker Apparel--
Hard hat, coveralls, impervious gloves, face shield, safety shoes or other
protective footwear should be worn.
Procedure--
The metal cylinder is inserted into a line bypass and purged with inert gas.
The sampling vessel's valves are opened, while the main line valves are closed
The container is flushed with slurry for 2 minutes, the container valves are
then closed and main line valves opened. The bypass is purged to decontami-
nate the lines, and the container is removed.
Hazards--
If a valve will not close, the sample container is to be left in the system.
The primary hazard is from leaking material, which can contaminate both the
work space and the worker. In case of severe splashing (union not properly
purged, cylinder leaking), the operator should be required to shower and put
on clean work clothes.
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START-UP AND SHUTDOWN
Safe start-up and shutdown procedures will be discussed together in the follow-
ing analysis. Pilot plants continually go through cycles of process start-up
and shutdown; runs generally last no longer than 2 weeks (7 days at equilibrium
conditions), and maintenance and modification are frequent needs. The un-
usually large number of cycle-up and cycle-down periods, especially when high
temperatures and pressures must be reached, creates the need for special safety
considerations. Start-up, voluntary shutdown, and emergency shutdown pro-
cedures are presented, based upon procedures developed at several coal gasifi-
cation pilot plants.
Start-up After Extended Shutdown (1 week or more)
System leaks are a major safety consideration in starting up the plant. There-
fore, the entire system is gradually repressurized with inert gas (N2) to about
150 psi (C02 Acceptor). At this point, teams of workmen check the entire
system for leaks, especially at valve outlets, glands, and flange tie-ins,
paying particular attention to areas which have recently undergone maintenance
or replacement. If no gross leaks are found, the system is slowly brought up
to operating pressure and temperature. The expansion of equipment at high
temperature generally serves to "tighten up" any pinpoint leaks which may exist,
and a leak-free condition is said to exist when, at operating pressure, no
more than 145 cubic feet per hour (3500/24 hr) of gas is lost from the system.
If any leaks are found, the system is depressurized and the appropriate
maintenance work is done.
Voluntary Shutdown
At the scheduled run shutdown time, a voluntary shutdown is initiated. This
is done by first venting all process gases to a flare stack and then purging
the system twice with inert gas, then allowing the system to cool down for 24
to 48 hours. When the reactor contents are cool, flanges on the gasifier are
opened to allow quenched residual solids to fall into large aluminum tote
bins. The solids are disposed of as landfill. Voluntary shutdown is essen-
tially a safe procedure, the only safety hazard being incomplete purging of
process gas prior to cracking the flanges. This is avoided by having two
complete purges before cool-down, and by avoiding difficult to purge S-bends
and blind piping in the original design.
Emergency Shutdown
Emergency shutdown should be initiated in the case of a fire, as noted before,
or in case of equipment failure, such as faulty refractory lining causing a
vessel shell to overheat. The latter is signaled by a discoloration in a heat-
sensitive paint on the vessel or piping. Such an occurrence should be observed
at routine hourly inspection by the operators during process runs. If a hot
spot is noted, a stream of dry, superheated steam should be immediately di-
rected on the spot to keep it cool. If the spot continues to rise in tempera-
ture, emergency shutdown should be initiated. The coal feed should be stopped
immediately, opening all valves to headers terminating at flare stacks. Inert
gas purging through the system should be initiated to halt combustion.
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It is essential in case of emergency shutdown to confirm that all valves are in
fact open and that no pockets of hot, high-pressure gases remain in the system.
This is done by operator inspection of all valves and pressure gauges. Further-
more, after such shutdown, all vessels and pipes should be tested for wall
thickness and freedom from cracks by means of an ultrasonic wall thickness
gauge applied to the outside of the vessel or pipe.
MAINTENANCE
Safety recommendations for maintenance procedures have the common requirement
that any work be fully coordinated via clear communication between operations
staff and the various maintenance teams. An effective means of accomplishing
such communication is by requiring that a "safe work permit" be issued by the
shift supervisor before any maintenance work is done. In the process of
approving the work permit, the supervisor must determine which valves and
electrical equipment must be locked to assure the safety of the system requir-
ing maintenance. Before work is begun, the valves and electrical equipment
•thus identified are locked in the appropriate positions and tagged to indicate
the nature of the work being done, and to warn other workers not to tamper with
them. A thorough description of the C02 Acceptor work permit, lock-out, and
tag-out procedure can be found in the "Operational Safety Practices for Coal
Gasification Plant, Rapid City, South Dakota" (Steams-Roger 1972).
When vessel entry is required, the same permit procedure should be followed,
with the additional stipulation that thorough tests for toxic gases, explosive
conditions, and oxygen concentration be carried out prior to entry. Supplied
air, continuous flow, full-face piece breathing apparatus should be used if
there is any possibility of hazard from toxic gases or insufficient oxygen.
If an explosive mixture is found, the vessel must be repurged with inert gas
and the above tests must be repeated.
Similar tests to those already described, with the exception of oxygen
concentration tests, must be performed on any piping that is to be opened for
work.
All maintenance procedures that include welding, cutting, or grinding to be
done in the plant area should be approved beforehand by the issuance of a "hot
work permit." This permit should not be issued until the shift supervisor has
ascertained, by means of inspection and combustible gas tests, that the work
area is free of combustible material and that the area is shielded in such a
way that sparks from the operation do not fall to floors below or fly to
another, uninspected area. The permit should be good only for the time and
job specified by the shift supervisor on the permit form. If work must con-
tinue into another shift, the new supervisor should approve the work permit
for that shift.
FIRE
Fire hazards are not unique to the pilot plant. The unique aspect of the coal
gasification pilot plant is that all process units are linked without surge.
If one section requires emergency shutdown, then all sections must go into
emergency shutdown procedures.
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The emergency shutdown procedure has already been described. Fire fighting
follows normal procedures used in any refinery or gas transmission station.
However, three points must be emphasized:
• A combustible process material will pass through the break before igniting.
As long as there is pressure in the vessel, no air can get into it. Some
pressure should be maintained in the vessel until it is completely purged
of combustible material and the fire dies out.
e A fire in a high-pressure vessel should not be extinguished. The com-
bustible gases will continue to spew from the vessel, creating an explosion
hazard. Instead, the vessel contents should be dumped to the flare, as
already described, and inert gas purging should be initiated simultaneously.
• While structures should be kept cool during a fire, it could be dangerous
to wet down or to otherwise excessively cool hot reaction vessels. This
sudden cooling could cause excessive stresses to develop and could either
seriously weaken the vessel or cause additional leaks to develop.
Existing OSHA regulations are not specifically applicable to coal gasification
pilot plants, especially with respect to the potential hazards that exist in
them. Documents that are more directly applicable to these conditions include:
• American Standard Codes for Pressure Piping, ASA B31.1-1955 and B31.8-1958.
The American Society of Mechanical Engineers, New York
• The ASME Boiler and Pressure Vessel Code - Section 8, Unfired Pressure
Vessels - 1965, The American Society of Mechanical Engineers, New York
• Battelle-Northwest Pressure Systems Manual, BNWL-MA-21
• Hanford Engineering Standards
HWS-10000 - Architectural-Civil Standards
HWS-10001 - Mechanical Standards
HWS-10002 - Electrical Standards
HWS-10003 - Guides, Vol. 1
HWS-10003 - Guides, Vol. 2
HWS-10004 - Welding Standards
HWS-10005 - Instrument Standards
HWS-10006 - Standard Design Criteria
HWS-10007 - Protective Clothing Standards
t National Fire Codes, The National Fire Protection Association., Boston (1965)
Volume 1, Flammable Liquids
Volume 2, Gases
Volume 3, Combustible Solids, Dust, and Explosives
Volume 4, Building Construction and Facilities
Volume 5, Electrical (The National Electrical Code)
Volume 6, Sprinklers, Fire Pumps, and Water Tanks
Volume 7, Alarm and Special Extinguishing Systems
Volume 8, Portable and Manual Fire Control Equipment
Volume 9, Occupancy Standards and Process Hazards
Volume 10, Transportation
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• Safety Code for Cranes, Derricks, and Hoists - 1943, Reaffirmed 1952, ASA
B30.2, United States of American Standards Institute
• Safety Code for Elevators, Dumbwaiters, and Moving Walks - 1965, ASA A17.1,
United States of American Standards Institute
• Uniform Building Code, Vol. 1, International Conference of Building
Officials, Pasadena, California (1964)
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RECOMMENDATIONS FOR FURTHER RESEARCH
During the development of this document it has become increasingly obvious
that there is very little hard information on the subject of occupational
health in coal gasification plants. Further development of reasonable and
real criteria for the protection of the workers in this new industry can only
be accomplished when there is an honest understanding of the true nature of
the problem. Until then, recommendations such as the ones that appear in this
document must be considered preliminary.
This section summarizes overall research needs as well as important areas for
future research in process, process equipment, health effects, monitoring and
analytical procedures, industrial hygiene, and safety. The recommendations
should generate more thoughts on the subject.
INDUSTRIAL HYGIENE SURVEY
Comprehensive, reliable industrial hygiene surveys of breathing zone and
ambient air concentrations of potentially hazardous materials in pilot plants
are sorely lacking. Precise standards cannot be developed before data are
available on which to base them. The following information gathering tasks
must be performed for each work station in each pilot plant:
• Description of operation
• Determination of number of workers exposed
• Determination of the nature of employee exposures to
potentially toxic agents
• Description of these exposures
• Correlation of the extent of worker exposures to materials in
process streams
• Description of ventilation systems and their efficacy
• Documentation of work practices instituted to reduce
worker exposure
• Documentation of existing conditions
• Documentation of past and present industrial hygiene practices
The NIOSH Appalachian Laboratory for Occupational Safety and Health is engaged
in a study of ambient air concentrations at coal gasification facilities and
will determine the information listed above.
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Accurate information on specific toxic agents and on classes of toxicants that
might be expected in the workplace air of a coal gasification facility is of
equal importance to the industrial hygienist. Initially, qualitative analysis
of the workplace air should be performed. (Qualitative sampling of the HYGAS
facility has been completed.) Quantitative sampling and analysis will be
completed at a later date. More specific quantitative monitoring should be
done to determine levels of hazardous materials in all work areas of the pilot
plant. Procedures that are recommended for the qualitative analysis include
the following*:
« High-volume area sampling and analysis aimed at determining classes
of compounds
» Personal monitoring
e Strict correlation of samples with work stations and
environmental monitoring protocols
• lexicological testing of collected materials
• Overview analysis of plant
0 Validation of indicator contaminants to measure indices of
exposure
Once potentially hazardous agents in the various work stations have been
identified, extensive quantitative sampling should be done to obtain informa-
tion on worker exposures. During this in-depth industrial hygiene survey the
following tasks should be performed:
e Determination of 8-hour time-weighted average and peak con-
centrations of potentially harmful agents
• Collection of area samples where high concentrations are
suspected
• Collection of enough samples to provide statistically
valid data
INFORMATION TRANSFER
A primary reason for construction of a pilot plant is to perform experiments
on a large scale so that operating problems can be evaluated and corrected.
Data on process and major problems are transmitted on a routine basis. In
addition routine maintenance problems dealing with pumps, valves, flanges,
cavitation, material, etc., are solved at the pilot plant. While they may be
solved routinely in one plant, they may present difficulty in another.
Because the problems are not always major and because they are not concerned
with process data, information concerning their solution can be lost. There
should be a mechanism for transmitting this information to management at other
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pilot operations and to the designers of the demonstration and commercial
plants. ERDA could be the centralized data collection center, with informa-
tion disseminated to each of the interested groups on a routine regular basis.
Alternately, a private contractor could also serve in this capacity.
PROCESS AREAS
(a) The actual range of pretreater effluents, especially of the oils and tars,
should be defined. The gaseous effluents in the 800°F (427°C) range may be
more hazardous than those from the gasifier. It is probable that the off-gas
may contain tars boiling above 800°F (427°C) because of either vapor pressures
within the pretreater or polymerization reactions of the components.
(b) A study of the thermal oxidation process area should be undertaken to
verify that complete oxidation of polynuclear aromatic hydrocarbons has been
effected.
(c) The formation of oxides of nitrogen in flares, furnaces, and oxidizers
is probable in the combustion area. If an amine process is used in acid gas
removal, ambient concentrations of amines may be present. Information should
be developed to determine the probability that the oxides of nitrogen will
react with the amines to form nitrosamines.
(d) Knowledge of the constituents of the gas stream at each point in the
process is crucial in identifying the compounds to which employees may be
exposed. The true distribution of sulfur and nitrogen decomposition products,
for example, should be determined. At this time, estimation of the total
distribution is based primarily on reactions determined by calculations.
(Appendix E presents material flows for the Synthane process. Concentrations
of potentially carcinogenic oils and tars have been estimated on the basis of
vapor pressure alone.)
(e) The fate of trace metals in the coal has not been accurately described.
More explicit information on the subject should be gathered through more
in-depth analysis of the gas stream.
(f) Detailed study is needed to determine the various components present in
the gasifier for each process, and the affect of the temperature gradient on
the condensation of the gasifier component products. What is the effect of
shutdown on the deposition of carcinogenic products on surfaces that will
be contacted by maintenance and/or production workers?
(g) Study is needed to determine the volatilities of trace elements,
especially those of a toxic nature, after the method of Attari. The quantita-
tive analysis of toxic elements in each of the process streams is desirable
so that worker exposure may be determined.
(h) Existing data for the C02 Acceptor (personal communication, Oct. 27,
1976, with D. McCoy, c/o C02 Acceptor Pilot Plant, Rapid City, South Dakota),
personal observations at the Synthetic Fuels Pilot Plant, and Synthane bench
scale data (Massey et al. 1975) indicate that deep-bed injection produces
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less tar, phenol, cyanide, and thiocyanate than free-fall injection of the
coal. Research is needed to determine the optimum economical operating condi-
tions to limit these undesirable products.
(i) It is assumed that the coked or ashed solids from the reactor are essen-
tially inert. Study is required to determine the real hazard classification
of these solids (i.e., are they dust hazards, carcinogenic, toxic, neutral,
etc.).
(j) Activated carbon is used as an adsorbent in many chemical processes.
There is research needed to determine whether char can act as an adsorbent for
oil and trace metals.
(k) There is the possibility of iron carbonyl formation as a result of the
reaction between carbon monoxide and carbon steel pipe at high pressures and
low temperatures. Research should be undertaken to determine the extent of
this reaction. The quantity of iron carbonyl formed should be determined,
as well as its effect on the methanator catalyst, and the possibility for
worker exposure.
(1) Under certain operating conditions or temperatures nickel carbonyl may
be formed. The maintenance of temperatures above 500°F (260°C) while the
synthesis gas is in contact with the catalyst will avoid this problem.
However, in the event of an upset in the operating parameters or a "crash
shutdown" of part of the process, the operating condition may no longer be
safe. There is a need to determine the conditions under which nickel carbonyl
is formed at the methanator. If it is formed, what is the potential for worker
exposure and environmental damage?
HEALTH EFFECTS
(a) The relative toxicity of aromatic hydrocarbons condensed on the exterior
surfaces of equipment and structures should be determined. These hydrocarbons
are considered a source of contamination, but as yet little is known on the
subject. (Studies will be conducted in each of three pilot plants to determine
the presence of polynuclear aromatic [PNA] hydrocarbon compounds. Ultraviolet
[UV] detection of settled PNA compounds should be employed in this study.)
(b) Rapid tests should be developed to determine the relative hazard (toxicity,
mutagenicity, and/or carcinogenicity) of whole process streams. When fugitive
emissions occur, whatever their cause, employees are exposed to the total
stream of emissions, not single compounds or fractions. The total process
stream contains both inhibitors and cocarcinogens. The entire toxic effect of
the emissions may be tremendously enhanced (or diminished) by the presence of
those compounds. Even the test material for the Ames test, as developed by
Dr. J. Epler for testing coal conversion effluents, must be fractionated into
14 separate parts (Guerin 1976).
A program of surveillance for occupational teratogenicity, which is now
feasible, should also be developed. (NIOSH research in this area is ongoing
and the results are expected in the summer of 1978.)
141
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(c) Fifty-one cases of skin lesions reported by Sexton offer an opportunity
for follow-up of medical records to look for the association observed by
Holmes et al. (1970) in men with scrota! epithelioma, i.e., enhanced incidence
of malignancies of the respiratory and upper disgestive tracts. It is recom-
mended that this be done and that consideration be given to follow-up of
other workers who were at the Union Carbide plant in Institute, West Virginia.
(d) The Pittsburgh Energy Research Center has a 25-year history of work on
coal treatment and conversion without a reported case of cancer- (Other
coal oriented research facilities have made similar statements.) A follow-up
of medical records for each of the workers who have left the center should
be instituted to determine the incidence of any type of cancer and, where
applicable, cause of death. There are other fertile areas for retrospective
epidemiological studies of workers in facilities studying coal conversion.
These should be identified and followed up as rapidly as possible.
(e) Medical histories, in conjunction with work histories, can benefit others
as well as the workers examined. These records can provide the data base for
prospective and retrospective epidemiologic studies of great potential value
in determining the health hazards of coal gasification. It is recommended
that steps be taken to maximize the usefulness of future records and the
availability of past and future records. Such steps would include standardiza-
tion of a basic testing protocol and of record formats, and perhaps establish-
ment of a central depository for records from terminated projects. It is
recommended that no test be introduced specifically for epidemiologic use.
(f) Research is needed on the interaction effects of chemical carcinogens
and physical agents, such as heat, ionizing radiation, noise, etc., to
determine the potential for increase or decrease of workers' risk.
Studies are under way at the Biomedical Science Laboratories in Cincinnati,
Ohio, to determine interaction effects between heat and benzo[a]pyrene. The
estimated available date for the report is early 1979.
While the biomedical studies will be illuminating, further work of whole
process streams is needed.
MONITORING AND ANALYTICAL PROCEDURES
(a) A real-time monitor for polycyclical
or an indicator such as BaP is desirable.
in Figure 23.
aromatic hydrocarbon (PAH) compounds
A possible approach is diagramed
Air Hexane
In Wetting
Photodetector
Glass Filter
Tape'
(640 ran)
(520 nm)
Cooler
Recorder
Figure 23 Schematic for low-temperature, laser-excited BaP monitor.
142
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The device uses the principle of low-temperature, laser-excited fluorescence.
Both discrimination of BaP and signal intensity are increased severalfold
through the temperature dependence of the Boltzmann distribution. The lowest
energy levels are populated at the expense of the higher energy levels as the
temperature approaches zero.
For more conventional monitoring, areas of further investigation include
problems associated with collection, storage, and analysis of polycyclic
aromatic hydrocarbons.
Jones et al. (1975) described an efficient sampling system that increased
collection efficiency of PAH compounds as much as 10 times over standard
sampling techniques. Adaptability of this method to personal sampling devices
for BSFTPM should be explored.
(b) Research must be done on collected particulate matter containing PAH
compounds to determine sample losses due to vapor pressure. Perhaps the ideal
experimental approach would be to generate a defined PAH aerosol and then
collect it on standard sampling media such as the following:
t Particulate filter from HIVOL
• Silver membrane filter
§ Cold trap
0 Combination of above
This could be repeated with various pure PAHs, mixtures of PAHs, particulates
coated wtih PAHs, oily particulates coated with PAHs, etc., to resolve the
severity of the problem of sample loss due to vapor pressure and to facilitate
the development of improved collection techniques.
(c) Alternatives to benzene soluble fraction of total particulate matter as
the measure of biologically active carcinogenic material should be explored.
The Standard for Exposure to Coke Oven Emissions (Federal Register 1976a)
addresses several established alternative analytical techniques. Perhaps a
process involving selective solvation of collected particulate matter followed
by a total fluorescence (luminescence) scan could be developed to fill this
need. Such a research instrument should be superior to present methods based
on benzene solubles.
When monitoring for a specific component in the collected PAH is being done,
purity of reference material is crucial. In the fluorescence monitor just
discussed, for example, care must be taken to ensure that the reference BaP
material is BaP and not a mixture of BaP, SeP, and other PAHs with closely re-
lated physical properties. The feasibility of high-pressure liquid chromatog-
raphy followed by multipass automatic zone refining should be studied as a
means of preparing high-purity reference samples of BaP- Bulk electronic
conductance could be used to monitor final purity, as conductance will plateau
at a final purity not easily verified by any routine analytical chemical or
instrumental method. The stability of the BaP material during storage must
also be demonstrated.
143
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A feasibility determination should also be made for continuous semiautomatic
monitoring with remote readout for particulates using some of the newer glass
monitors.
(d) Finally, analytical work should be done on the coal fines, chars, ash,
and other solid effluents from the coal gasification processes. These should
be examined for the presence of soluble aromatic hydrocarbons and Teachable
trace elements.
It has generally been thought that the solid effluents from coal conversion
processes are inert. However, in a number of instances, these solids are con-
tacted with water recycled from the wastewater pond, or with water recycled
internally such as in the coal grinding gas scrubber, and the pretreater and
gasifier off-gas venturi scrubbers. These solids are reasonably porous and may
absorb or concentrate phenols, tars, or trace elements from the water.
INDUSTRIAL HYGIENE
(a) Protective clothing for the coal gasification worker is necessary. While
the type of clothing has been described and suggested in the chapter on health
protection, however, no information is available defining material in that
clothing. Research is required on the following:
• Coveralls
9 Gloves—for various purposes
9 Shoes—particularly on the best type of sole
9 Underclothing
(a) Barrier creams seem to be controversial and more information on their
effectiveness must be gathered. A useful barrier cream should be developed.
A standard test for these creams should be devised and used to make publishable
comparisons. The Pittsburgh Energy Research Center (PERC) has conducted a pre-
liminary internal survey on barrier creams and has found varying degrees of
effectiveness. They have found that effectiveness is dependent upon the con-
scientiousness of the individuals involved. Research is needed to develop an
effective long lasting barrier cream. A standard test for these creams should
be determined and published as part of the manufacturing specifications.
(b) The effectiveness of available cleansing materials for removal of tars
from the skin should also be investigated. More effective materials are
needed.
(c) The permissible concentration of PAH materials in the cleaning fluid or
wash water from the plant laundry facilities should be defined. It is possible
that in large gasification plants the percentages of this PAH material could be
high.
(d) A cleaning agent should be made available to remove oils and tars from
equipment and surrounding structures and from tools used on tarred surfaces.
Effective means for disposing of this material should also be developed.
144
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(e) An effective personnel monitoring device should be devised for use in
areas where considerable coal-derived hydrocarbons could be present.
(f) The effectiveness of UV light in detecting skin contamination should be
thoroughly demonstrated. At the same time the possibility of damage due to
the use of UV light for surveillance should be examined. Alternative pro-
cedures for contamination detection should also be investigated.
(g) Research is needed to determine the effectiveness of a sputum cytology
program in helping to protect the exposed workers.
145
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Appendix A. Possible constituents of gasifier off-gas.
As has been mentioned several times in this report, there are no good analyti-
cal data characterizing constituents of gasifier off-gas. In the "Research
Recommendations" section the need for further analytical work on components
of the gas stream has been emphasized. In the absence of analytical data and
keeping in mind the fact that off-gases from the different processes will vary
we present here a list of products of coal pyrolysis. (Coal pyrolysis is the
oxygen-deficient reduction of coal. It is similar to several of the coal
gasification processes.) The compounds listed in this appendix are intended
only as a first approximation of possible constituents of the gasifier off-gas.
Products of coal pyrolysis represent a myriad of different organic species.
Complete analyses of coal tars have, over the years, generated long lists of
polycyclic aromatic hydrocarbons (PAHs) and heterocyclic hydrocarbons. This
appendix presents several tables that categorize identified coal tar con-
stituents by boiling range. Constituents of coal liquefaction have not been
included in the list of coal pyrolysis products because it was determined that
different compounds would result from the two procedures.
Table A-l is a partial list of coal tar constituents compiled from Freudenthal
and co-workers (1975), Dailey (1976), and Ensminger (1976). An "x" in the
"Present in Gasification" column of this table indicates that the compound has
been identified in the process condensate from a bench scale gasification unit
(Guerin and Epler 1976) or in the condensate from the MERC unit (Gillmore and
Liberatore 1975). In addition, Wynder and Hoffman (1967) and Kornreich (1976)
have been used to identify coal tar compounds with known carcinogenic activity.
Most of the compounds indicated as carcinogenic have undergone toxicologic
testing in animals and have been generally accepted by the scientific
community as being primary carcinogens. Examples of cocarcinogenic compounds
are also included. Compounds that are under question as to their carcinogenic
potential have not been indicated. Insufficient data exist to make a more
exhaustive table.
Tables A-2 and A-3 are taken from a Bureau of Mines report (Karr et al. 1961).
They list tar acids and tar bases that were identified in low-temperature
bituminous coal tar. The fact that a compound is listed in these tables does
not mean that it will necessarily be in the gas stream, but rather that it
could be in the gas stream. This is some indication of the complexity of
the problem.
156
-------
Table A-l. Possible constituents of gasifier off-gas categorized by boiling range.a>°>°
Boiling Point < 100°C
Aliphatic Hydrocarbons:
Amylene
1 ,5-Butadiene
Butyl ene
Crotonylene
Heptane
Heptene
Hexane
M _ v _ n _
fie xcne
Pentane
Cyclic Hydrocarbons:
Cyclohexadiene
Cyclohexane
Cyclohexene
Cyclopentadiene
Aromatic Hydrocarbon:
Benzene
Oxygen-containing Compounds:
Acetaldehyde
Acetone
Carbon monoxide
Methyl ethyl ketone
Nitrogen-containing Compounds:
Acetonitrile
Ammonia
Hydrogen cyanide
Nitrogen oxides
Sulfur-containing Compounds:
Carbon disulfide
Carbonyl sulfide
Diethyl sulfide
Dimethyl sulfide
Ethyl mercaptan
Hydrogen sulfide
Methyl mercaptan
Sulfur dioxide
Thiophene
Present \t\d'e
Gasification
X
X
X
X
X
Known ?
Carcinogen
X
Boiling Point = 100°C to 150°C
Aliphatic Hydrocarbon:
Octane
Cyclic Hydrocarbons:
Dimethyl cyclohexane
Methyl cyclohexane
Nonaphthene
Aromatic Hydrocarbons:
Ethylbenzene
Styrene
Toluene
o-Xylene
m-Xylene
p-Xylene
Oxygen-containing Compounds:
Acetic acid
Propanoic acid
Nitrogen-containing Compounds:
2,6-Dimethyl pyridine
2-Methylpyridine
3-Methyl pyridine
4-Methylpyridine
Pyridine
Pyrrole
Sulfur-containing Compounds:
3-Methylthiophene
Thioxene
Present in
Gasification
X
X
X
X
X
Known
Carcinogen
i
"Adapted from Dailey (1976) and Ensminger (1375).
"Adapted from Lebowitz et al. (1975).
Adapted from Freudenthal et al . (1975).
Adapted from Gillmore and Liberatore (1975).
^Adapted from Guerin and Epler (1976).
JAdapted from Wynder and Hoffman (1967).
^Adapted from Kornreich (1976).
(cont'd)
157
-------
Table A-l. (cont'd)
Boiling Point = 150°C to 200°C
Aliphatic Hydrocarbon:
Decane
Cyclic Hydrocarbon:
Dicyclopentadiene
Aromatic Hydrocarbons:
DursnG
o- Ethyl toluene
m-Ethyl toluene
p-Ethyl toluene
Hemellitene
Hydrindene
I sodurene
Isopropyl benzene
Mesitylene
n-Propylbenzene
Pseudocumene
Polynuclear Aromatic Hydrocarbons:
2,7-Dimethylindene
3,6-Dimethylindene
I ridcris
Oxygen-containing Compounds:
n-Butanoic acid
Loufns ronG
o~ CI*GS ol
Dime thy Icouma rone
n-Pentanoic acid
Phenol
Nitrogen-containing Compounds:
Benzonitri le
Dimethyl aniline
2,3-Dimethylpyridine
2,4-Dimethylpyridine
2,5-Dimethylpyridine
3,4-Oimethylpyridine
Toluidine
2,4,5-Trimethylpyridine
2,4,6-Trimethylpyridine
Present in
Gasification
X
X
X
X
X
Known
Carcinogen
cocarcinogen
Boiling Point = 200°C to 250°C
Aliphatic Hydrocarbon
n-Dodecane
Polynuclear Aromatic Hydrocarbons:
Cholanthrene
Dihydronaphthalene
4 ,6-Di methyl i ndene
5,7-Dimethyl indene
1 -Methyl naphthal ene
2-Methylnaphthalene
Naphthalene
Oxygen-containing Compounds:
Acetophenone
Benzoic acid
m-Cresol
p-Cresol
2,2,'-Dihydroxydiphenyl
2, 3-Dimethyl phenol
2,4-Dimethylphenol
3, 4,-Di methyl phenol
3, 5- Dimethyl phenol
2, 6- Dimethyl phenol
2, 5-Dimethyl phenol
pi methyl coumarone
Durenol
o-Ethylphenol
m-Ethyl phenol
p-Ethylphenol
n-Heptanoic acid
Isopseudocumenol
3-Methy 1 -5-ethy 1 phenol
Nitrogen-containing Compounds:
Acetamide
Isoquinoline
2-Methylquinoline
8-Methylquinoline
Propionamide
Qu incline
1 ,2,3,4-Tetramethylpyridine
Present in
Gasification
X
X
X
X
X
X
X
X
X
X
Known
Carcinogen
cocarcinogen
X
|
x
X
X
(cont'd)
158
-------
Table A-l. (cont'd)
Boiling Point = 200°C to 250°C
(cont'd)
Sulfur-containing Compounds:
Diallylsulfide
Dime thy Ibenzothiophene
Methylbenzothiophene
2,3-Benzothiophene
Boiling Point = 250°C to 300°C
Aromatic Hydrocarbons:
3,4'-Dimethyldiphenyl
4,4'-Dimethyldiphenyl
Di pheny 1
2-Methyldiphenyl
3-Methyldiphenyl
4-Methyldiphenyl
Polynuclear Aromatic Hydrocarbons:
Acenaphthylene
Acenaphthene
1 ,2-Cyclopentanonaphthalene
1 ,2-Dimethylnaphthalene
1 ,3-Dimethylnaphthalene
1 ,5-Dimethylnaphthalene
1 ,6-Dimethyl naphthalene
1 ,7-Dimethylnaphthalene
2, 6- Dimethyl naphthalene
2, 7-Dime thy! naphthalene
2 ,3- Dimethyl naphthalene
1-Ethylnaphthalene
2-Ethylnaphthalene
Fluorene
Oxygen-containing Compounds:
Diphenylene oxide
1-Methyldiphenylene oxide
1-Naphthofurane
2-Naphthofurane
a-Naphthol
B-Naphthol
Resorcinol
Present in
Gasification
y
X
X
X
X
X
X
X
X
X
X
X
Known
Carcinogen
Boiling Point = 250°C to 300°C
(cont'd)
Nitrogen-containing Compounds:
1 ,3-Dimethylisoquinoline
2,8-Dimethylquinoline
5,8-Dimethylquinoline
Indole
2-Methylindole
3-Methylindole
4-Methylindole
5-Methylindole
7-Methylindole
1-Methylisoquinoline
3-Methylisoquinoline
3-Methylquinol ine
4-Methylquinoline
5-Methylquinoline
6-Methylquinoline
7-Methylquinol ine
1-Naphthonitrile
Boiling Point > 300°C
Aliphatic Hydrocarbons:
n-Heptadecane
Nonadecane
Polynuclear Aromatic Hydrocarbons:
Anthracene
1 ,2-Benzanthracene
2,3-Benzchrysene
3,4-Benzfluorene
Benz[m ,TI, o]f luoranthene
2 , 3-Benzf 1 uoranthene
3 ,4-Benzf luoranthene
7 ,8-Benzfluoranthene
8, 9- Benzf luoranthene
1 ,2-Benzfluorene
2,3-Benzfluorene
1 ,2-Benznaphthacene
1 ,2-Benzoanthracene
1 ,2-Benzpentacene
Present in
Gasification
Known
Carcinogen
X
X
X
(cont'd)
159
-------
Table A-l. (cont'd)
Boiling Point: > 300°C
(cont'd)
Polynuclear Aromatic Hydrocarbons
(cont'd)
1 ,12-Benzperylene
3,4-Benzphenanthrene
1 ,2-Benzpicene
1 ,2-Benzpyrene
4,5-Benzpyrene
Chrysene
Coronene
1 ,2,3,4-Dibenzanthracene
1 ,2,5,6-Dibenzanthracene
1 ,2,7,8-Dibenzanthracene
1 ,2,6,7-Dibenzpyrene
1 ,2,7,8-Dibenzpyrene
3,4,8,9-Dibenzpyrene
3,4,9,10-Dibe.nzpyrene
3,4,8,9-Dibenztetraphene
9,10-Dihydroanthracene
5,12-Dihydronaphthacene
9, 10- Dime thy Iphenanthrene
2, 3- Dimethyl anthracene
2 ,7- Dimethyl anthracene
3, 6- Dime thy Iphenanthrene
2,2-Dinaphthyl
Diphensuccindan
Fluoranthene
1 -Methyl anthracene
2-Me thy 1 anthracene
9-Me thy 1 anthracene
1-Methylchrysene
2-Me thy! chrysene
1-Methylfluorene
3-Methylfluorene
9-Methylf luorene
1-Methylphenanthrene
2-Me thy Iphenanthrene
3-Methylphenanthrene
9- Me thy Iphenanthrene
1-Methylpyrene
3-Methylpyrene
4-Me thy! pyrene
Present in
Gasification
X
X
Known
Carcinogen
X
X
X
X
X
X
X
cocarcinogen
X
X
cocarcinogen
cocarcinogen
cocarcinogen
Boiling Point: > 300°C
(cont'd)
Polynuclear Aromatic Hydrocarbons
(cont'd)
Naphthacene
Naphthof luorene
Naphtho-2' ,3'-l ,2-anthracene
Perylene
Phenanthrene
4,5-Phenanthrylene methane
2,3-o-phenylene pyrene
1-Phenyl naphthalene
2-Phenyl naphthalene
2- Pheny Iphenanthrene
Picene
Pyrene
1 ,2,3,4-Tetrahydroanthracene
1 ,2,3,4-Tetrahydrofluoranthene
2, 3, 6, 7-Tetramethyl naphthalene
1 ,3,7-Trimethylnaphthalene
1 ,3,6-Trimethylnaphthalene
1 ,2,8-Trimethylphenanthrene
Triphenylene
Truxene
Oxygen-containing Compounds:
Benzanthrone
1 ,2-Benzdiphenylene oxide
1 ,9-Benzoxanthene
Brazan
Dibenzocoumarone
1 ,8-Dimethylphenylene oxide
0,0' -Oi phenol
5-Diphenyl-y-pyrone
Hydroxy anthracenes
4-Hydroxydiphenyl
2-Hydroxyf 1 uorene
9-Hydroxy-4-methyl f 1 uorene
p-Methoxybenzophenone
Methyl brazans
2-Methyldiphenylene oxide
3-Methyldiphenylene oxide
Present in
Gasification
X
X
X
Known
Carcinogen
X
X
cocarcinogen
(cont'd)
160
-------
Table A-l. (cont'd)
Boiling Point: > 300°C
(cont'd)
Oxygen-containing Compounds
(cont'd)
peri-Naphthoxanthene
o(3-Naphthyl)phenol
2-Phenanthrol
4-Phenanthrol
1-Phenylbenzanthrone
p-Phenylphenol
Tetramethyldi phenol
Xanthene
Nitrogen-containing Compounds:
Acridine
1-Azacarbazole
2-Azafluoranthene
13-Azafluoranthene
4-Azafluorene
1-Azapyrene
1 ,2-Benzacridine
3,4-Benzacridine
2,3-Benz-l-azacarbazole
2,3-Benz-4-azafluorene
1,2-Benzcarbazole
2,3-Benzcarbazole
3,4-Benzcarbazole
2,3-Benzfluoreneni trile
5,6-Benzquinoline
7,8-Benzquinoline
Carbazole
1 ,2,5,6-Dibenzacridine
1,2,7,8-Dibenzacridine
9,10-Dihydroacridine
Fluorene nitriles
Hydroacridine
Indenofl ,2,3-c^dlpyrene
4,5-Iminophenanthrene
2-Methylacridine
2-Methyl-5,6-benzquinole
Present in
Gasification
Known
Carcinogen
X
X
X
X
Boiling Point: > 300°C
(cont'd)
Nitrogen-containing Compounds
(cont'd)
2-Methylcarbazole
3-Methylcarbazole
2-Naphthoni trile
1-Naphthylamine
2-Naphthylamine
1-oxo-l ,2-dihydro-2-azapyrene
Phenanthridene
1 ,2,3,4-Tetrahydroacridine
Sulfur-containing Compounds;
1 ,2-Benzdiphenylene sulfide
Benzole, /Jdibenzothiophene
4,5-Benzthionaphthene
5,6-Benzthionaphthene
6,7-Benzthionaphthene
Benzyl thiophene
Dibenzothiophene
2,3,5,6-Dibenzthionaphthene
1 ,8-Dimethylphenylene sulfide
Dinaphthothiophene
Diphenylene sulfide
Methyldibenzothiophene
Methyl thiophene
Tetrahydrobenzo thiophene
Naphthobenzo thiophene
Present in
Gasification
Known
Carcinogen
161
-------
Table A-2. Index of individual tar acids from low-temperature
bituminous tar based on boiling range.
Compound Boiling Range, °Ca
Phenol 182
2-Methylphenol 190.8
2,6-Dimethyl phenol 201
4-Methylphenol 202.1
3-Methylphenol 202.2
2-Ethylphenol 207
2,4-Dimethylphenol 210
2,5-Dimethylphenol 210
2-Ethyl-6-methylphenol 212-214
3-Ethylphenol 214
2-Isopropylphenol 214
2-Ethyl-4-methylphenol 216-218
2,3-Dimethylphenol 218
4-Ethylphenol 219
3,5-Dimethylphenol 219.5
2,3,6-Trimethylphenol 220
2-n-Propylphenol 220
4-Ethyl-2-methylphenol 222
2,4,6-Trimethylphenol 222
5-Ethyl-2-methylphenol 223
2-Ethyl-5-methylphenol 224.2
3,4-Dimethylphenol 225
3-Ethyl-2-methylphenol 227
2,4-Dimethyl-6-ethylphenol 227-228
3-n-Propylphenol 228
3-Isopropylphenol 228
2-Isopropyl-3-methylphenol 228.5
2-Isopropyl-4-methylphenol 228-229/763
4-Isopropylphenol 228-229/745
4-Ethyl-3-methylphenol 228-230
2-(Propen-l-yl)phenol 230-231
2,4,5-Trimethylphenol 232
4-n-Propylphenol 232.6
2-Methyl-6-n-propylphenol 233
3-Ethyl-5-methylphenol 233
2,3,5-Trimethylphenol 233
(cont'd)
aAll temperatures are measured at atmospheric pressure unless followed by
a slash (/). The number to the right of the slash is the pressure at
which the boiling ranges were obtained, in mm. Figures in parentheses are
atmospheric boiling points estimated from reduced pressure data or from
boiling-point data of isomers and homologues, in mm.
162
-------
Table A-2. (cont'd)
Compound
Boiling Range, °C
2-Isopropy1-5-methylphenol
4-Isopropyl-2-methy!phenol
3-Ethyl-4-methylphenol
2,3,4-Trimethylphenol
5-Isopropyl-2-methylphenol
4-Isopropyl-3-methylphenol
2,3-Dimethyl-6-ethylphenol
4-Methy!-2-n-propylphenol
3-Isopropyl-5-methylphenol
4-Indanol
Catechol
2,3,5,6-Tetramethylphenol
3,5-Diethylphenol
3-Methylcatechol
3,4,5-Trimethylphenol
3,5-Dimethyl-2-ethylphenol
3,4-Dimethyl-6-ethylphenol
6-Methyl-4-indanol
7-Methyl-4-indanol
2,3,4,6-Tetramethylphenol
5-Indanol
2,6-Di-n-propylphenol
4-Methylcatechol
3,5-Dimethyl-2(propen-l-yl)phenol
7-Methyl-5-indanol
2,3,4,5-Tetramethylphenol
5,6,7,8-Tetrahydro-l-naphthol
2-Ethylresorcinol
Pentamethylphenol
4-Ethylresorcinol
2-(Cyclopenten-2-yl)phenol
2-(Cyclopenten-l-yl)phenol
2-Phenylphenol
5,6,7,8-Tetrahydro-2-naphthol
4-Methyl-5,6,7,8-tetrahydro-l-naphthol
4-Methyl-2-phenylphenol
2-Cyclohexylphenol
2-(Cyclopenten-2-yl)-4-methylphenol
2-Ethylhydroqui none
1-Naphthol
3-Methyl-5,6,7,8-tetrahydro-2-naphthol
4-Methyl-5,6,7,8-tetrahydro-2-naphthol
4-(Cyclopenten-l-yl)phenol
4-(Cyclopenten-2-yl)phenol
2-Naphthol
233.5
230-235
234-235
235-237
236.8-237.4
238
(240)166/100
(241)121-123/18
241
245/764
245
247-248
248
248
248-249
(250)90-93/1
(250)
(250)
(250)
250
255
256/764
258
(260)
(260)
260
264.5-265/705
(265)
267
(270)131/15
(270)133-135/12
(272)
275
275-276
(280)
(280)101-105/2
282.5-283.5
(284)105-108/1.;
(285)
288.01
(290)
(290)
(293)
(293)114-117/1.!
294.85
(cont'd)
163
-------
Table A-2. (cont'd)
Compound Boiling Range, °Ca
2-Methyl-l-naphthol (295)
4-Cyclohexylphenol 293.5-295.5/752
4-Methyl-1-naphthol (298)177-179/25
1 Methyl-2-naphthol (300)
1,4-Dimethyl-5,6,7,8-tetrahydro-2-naphthol (305)
5-Methyl-2-naphthol (305)
3,4-Dimethyl-l-naphthol (315)205-210/15
4-Phenylphenol 319
7-Ethyl-4-methyl-l-naphthol (320)
3-Phenylphenol 325
5-Acenaphthenol (332)221/40
4-Acenaphthenol (338)
1-Fluorenol (345)
2-Fluorenol 340-350
3-Fluorenol (350)
8-Methyl-2-fluorenol (355)
164
-------
Table A-3. Index of individual tar bases from low-temperature
bituminous tar (based on boiling range).
Compound
Boiling Range, °C
Pyridine
2-Methylpyridine
2,6-Dimethylpyridine
3-MethyIpyridine
4-Methylpyridine
2-Ethylpyridine
2,5-DimethyIpyridine
2,4-Dimethylpyridine
2-Isopropylpyridine
2,3-Dimethylpyri di ne
2-Ethyl-6-methylpyri di ne
3-EthyIpyridine
2,4,5-Trimethylpyridine
4-Ethylpyridine
3,5-DimethyIpyridine
2,4,6-Trimethylpyridine
4-Isopropylpyridine
5-Ethyl-2-methylpyri di ne
2,3,6-Trimethylpyridine
3-IsopropyIpyridine
3,4-DimethyIpyridine
4-Ethyl-2-methylpyridine
2,4-Dimethyl-6-ethylpyridine
2,3,5-Trimethylpyridine
Aniline
2,6-Dimethyl-4-ethylpyri di ne
2,4-Diethylpyridine
2,3,4-Trimethylpyri di ne
N,N-Dimethylaniline
3-Ethyl-4-Methylpyri di ne
N-Methylanine
2,3,5,6-Tetramethylpyridine
2,3-Cyclopentenopyri di ne
2-Methy!aniline
4-Methylaniline
2,3,4,6-Tetramethylpyridine
3-Methylaniline
115.4
129.42
144.05
144.14
145.0
148.6
157.01
158.40
158.9
161.16
160-161.5
162-165/762
165-168
169.6-170/750
171.91
171-172
173
174-176
176-178/759
177-178
179.13
179-180
181-182
182-183/739
183.93
186
187-188
192-193
192.5-193.5
195-196/753
196.1
197-198
199.5
200.3
200.55
203/750
203.34
a
(cont'd)
'All temperatures are measured at atmospheric pressure unless followed by a
slash (/). The number to the right of the slash is the pressure at which
the boiling ranges were obtained, in mm. Figures in parentheses are
atmospheric boiling points estimated from reduced pressure data or from
boiling-point data of isomers and homologues, in mm.
165
-------
Table A-3. (cont'd)
Compound
Boiling Range,
N-Methyl-3-methylani1i ne
N-Methyl-2-methylani1i ne
N-Methyl-4-methylani1i ne
2,5-Dimethylaniline
2,6-Dimethylaniline
2-Ethylaniline
2,4-Dimethylaniline
3,5-Dimethylaniline
5,6,7,8-Tetrahydroquinoline
3,4-Dimethylaniline
Quinoline
2-Methylquinoline
8-Methylquinoline
2,8-Dimethylquinoline
3-Methylquinoline
7-Methylquinoline
5-Methylquinoline
6-Methylquinoline
2,3-Dimethylquinoline
4-Methylquinoline
2,4-DimethyIquincline
2,7-Dimethylquinoline
2,6-Dimethylquinoline
2,6,8-Trimethylquinoline
2-Phenylpyridine
3-Phenylpyridine
2,5,8-Trimethylquinoline
4,6-Dimethylquinoline
4-Phenylpyridine
2,4,8-Trimethylquinoline
2,7,8-Trimethylquinoline
2,3,8-Trimethylquinoline
25457-Trimethylquinoline
2,5,7-Trimethylquinoline
2,4,6-Tm'methylquinoline
2-Naphthylamine
2,4,7,8-Tetramethylquinoline
1-Naphthylamine
2,4,,5,8-Tetramethylquinoline
N-Benzyl-2-methylaniline
N-Benzyl-3-methylani1i ne
N-Benzyl-4-methylani1i ne
7,8-Benzoquinoline
6,7-Benzoquinoline
2,3-Benzoquinoline
206-207
207-208
209-211/761
213.5
214/739
215-216/769
215.8-216.0/728
220-221
222.2
226
237.1
245.8
247.3-248/751.3
252
252/735
251.5252.5
253-255/735
257.4-258/745
261/730
264.2
264-265
264-265
266-267
267.4/746
268-269
269-270/749
(273)143-145/15
273-274
274-275
275.8/740
276.1/740
280/747
280-281
286.6/746
287/758
294
295.5/742
300.8
(310)168-172/12
(310)176/10
312
312-313
335
(345)200-205/14
345-346
(cont'd)
166
-------
Table A-3. (cont'd)
Compound Boiling Range, °Ca
3,4-Benzoquinoline 349/769
5,6-Benzoquinoline 350/721
2,4-Dimethylbenzo(72)quinoline 355
l,3-Dimethylbenzol(/)quinoline (358)240/35
9-Methylacridine 359-360/740
2-Methylbenzo(g-)quinoline (360)
4-Methylbenzo(g')quinol ine (360)
2,3-Dimethylbenzo(f)quinoline (360)
2,4-Dirnethylbenzo(gr)quinol ine (370)
3,4-Dimethylbenzo(gr)quinoline (370)
167
-------
Appendix B. Standards for materials known to be present or possibly present
in coal gasification plants.
OSHA standards limiting the concentration of some potentially toxic contami-
nants in the workplace air have been established under the OSHA Act of 1970.
Many of these standards will pertain to coal gasification plants. This appen-
dix presents two tables of the OSHA standards. The first includes names and
locations of compounds anticipated in a gasification facility. The second
table is a list of compounds for which standards have been adopted and which
may be found at some point in a coal gasification plant. These lists are not
intended as a comprehensive list of all hazardous compounds, for they cover
only material for which there is an OSHA standard. These standards may be
found in Federal Register 1976b. Shown in parentheses are the currently
available recommended standards from NIOSH Criteria Documents as referenced
in the table.
168
-------
Table 8-1. Standards for materials known to be present 1n coal gasification plants."
Compound
Acetic acid
Acetone
Ammonia
Aniline-skin
Antimony
Arsenic
Benzene
Beryllium
1 ,3-Butad1ene
Cadmium fume
dust
Carbon dioxide
Carbon dlsulflde
Carbon monoxide
Carbon tetrachloride
Chromium, soluble salts
Metal , insoluble salts
Coal dust (<5X S102)
(>5X S10j)
Coal tar pitch volatiles
Cresol -skin
Ethyl mercaptan
Hydrogen chloride
Hydrogen sulflde
Lead and inorganic lead
compounds
Manganese
Mercury
Methyl ethyl ketone
Methyl mercaptan
Naphtha (coal tar)
Napthalene
Nickel caroonyl
Nickel metal and soluble
compounds (as N1)
Phenol-skin
Propane
PyHdlne
Selenium compounds
SIHca (resplrable)
(total dust)
Styrene
Sulfur dioxide
Toluene
Vanadium
V205 dust
V205 fume
Xylene
TWA, ppm
1 0
1000
50
5
10(D/
1000
5000(10, OOO)1
20(1 )J'
50(35)*
10
5
200
100
10
o.ooi
5
1000
5
100
5(2)*
200(100)"
100(100)"
TWA* mg/m3
?c
£3
2400
35
19
0.5
0.5
0. 002(0. 002)?
2200
0.1 ,
0.2(.04r
9000(18, DOO)1
55
1
0.5 (0.025)1
1
2.4
0.10
0.2
i1)
£.£.
-
-
-
0.2(0.10)"
0.1(0.05)°
590
400
50
0.007
1
19(20)p
1800
15
0.2
0.10(0.05)'
0.30
13
01*
435
Acceptable celling
concentration
en<*
50
(.002 mg/m3!8
25(5 ppm/
005 mg/m3
3 mg/m3 .
0.5 mg/m3 (0.2 mg/m3)
(30000 ppm/
30 ppm (10 ppm)17
(200 ppm)*
25 ppm
(0.05 mg/m3)Z
10 ppm
5 ppm
20 ppm (10 ppm)"
5 mg/m3
10 ppm
(60 mg/m3)p
(0.05 mg/mg3)*
0.5 mg/m3
0.1 mg/m3
Where found
Gas stream
Laboratory
Gas stream
Trace element in coal
Trace element in coal
Gas stream, laboratory
Trace element in coal
Gas stream
Trace element in coal
Gas stream
Gas stream
Gas stream
Laboratory
Trace element in coal
Coal preparation areas
Gas stream
Gas stream
Gas stream
S tream
Gas stream
Trace element in coal
Trace element in coal
Trace element in coal
Laboratory
Gas stream
Gas stream
Gas stream
Methanation areas
Trace element in coal
Gas and effluent stream
Gas stream
Gas stream
Trace element in coal
Thermal oxidizer
Slurry oil, gas stream
Trace element in coal
Gas stream
federal Register 1976b. Skin after certain compounds indicates that
.there Is the possibility for exposure via a cutaneous route.
Time-weighted average. Numbers in parentheses indicate NIOSH recommended standards.
Coal tar pitch volatiles, as measured by the benzene-soluble fraction of particulate matter, includes
such polycycllc aromatic hydrocarbons as anthracene, benzo[a]pyrene, phenanthrene, acridlne, crysene,
.and pyrene.
"rlational Institute for Occupational Safety and Health (1974a).
Rational Institute for Occupational Safety and Health (19755).
'National Institute for Occupational Safety and Health (1976a).
?N»tional Institute for Occupational Safety and Health (197'-).
.National Institute for Occupatlona Safety and Health (10" jb).
^National Institute for Occupationa Safety and Health (1976C).
^National Institute for Occupatlona .i.ity and Health (l977a).
^National Institute for Occupatlona Safety and Health (1972b).
National Institute for Occupationa Safety and Health (1975a).
"National Institute for Occupationa Safety and Health (19775).
"National Institute for Occupational Safety and Health (1972b).
National Institute for Occupational Safety and Health (1973b).
pNational Institute for Occupational Safety and Health (197Sg).
'National Institute for Occupational Safety and Health (1974a).
rNational Institute for Occupational Safety and Health (19745).
'National Institute for Occupational Safety and Health (1973c).
^National Institute for Occupational Safety and Health (1977e).
"National Institute for Occupational Safety and Health (1975c).
169
-------
Table B-2. Standards for materials possibly present
in coal gasification plants.
Compound
Butyl mercaptan
Calcium arsenate
Cyclohexane
Cyclohexanol
Cyclohexene
Cyclopentadiene
Dimethyl ami ne
Dimethyl sul fate skin
Di nitrobenzene skin
Dinitro-o-cresol skin
Dinitrotoluene skin
Diphenyl
Ethanol
Ethanolamine
2-Ethoxyethanol - skin
Ethyl acetate
Ethyl ami ne
Ethyl benzene
n-Heptane
n-Hexane
Isobutyl acetate
Methyl acetate
Methyl alcohol
Methyl ami ne
Nitrobenzene skin
Nitrogen dioxide
Octane
Oil mist, mineral
Pentane
Petroleum distillates
Phosphorus compounds
Picric acid skin
n-Propyl acetate
Propyl alcohol
Sodium hydroxide
Tellurium
ppm
10
300
50
300
75
10
1
0.2
1000
3
200
400
10
100
500
500
150
200
200(200)*
10
1
5 (1)°
500
1000
500
200
200
mg/m3
35
l(0.002)a
1050
200
1015
200
18
5
1
0.2
1.5
1
1900
6
740
1400
18
435
2000
1800
700
610
260
12
5
9
2350
5
2950
2000
0.1-3
0.1
840
500
2 (2}d
0.1
^National Institute for Occupational Safety and Health (1975b).
^National Institute for Occupational Safety and Health (1976e).
^National Institute for Occupational Safety and Health (1976f).
National Institute for Occupational Safety and Health (1976h).
170
-------
Appendix C. Monitoring equipment.
Quick response continuous monitors are important for measuring levels of carbon
monoxide (CO) and hydrogen sulfide (H2S) in the ambient air and in the vicinity
of potential leaks. The measurement of these compounds may give an indication
of the concentration of carcinogenic material in the workplace air (see section
on monitoring worker's environment).
Tables C-l and C-2 list some commercially available instruments that may have
applications in the gasification plant environment.
171
-------
Table C-l. CO monitors.
Manufacturer
Andros, Inc.
Analytical Instrument
Development, Inc.
Bachrach Instrument Co.
Beckman Instruments, Inc.
Beckman Instruments, Inc.
Byron Instruments, Inc.
Calibrated Instruments,
Inc.
Devco Engineering, Inc.
Energetics Sciences, Inc.
Enviro Metrics, Inc.
Hewlett-Packard
Horiba
InterScan Corp.
Matheson Gas Products
Mine Safety Appliances
Mine Safety Appliances
Mine Safety Appliances
Philips Electronic
Instruments
Wi 1 ks
Model Principle of Operation Sensitivity, ppm
7000
511-14
US400L
866
6800
233A
SL/LC
Series 10
APMJOOO
Ecolyzer
5831
APMA-10
1140 Series
803 Series
D
70
202
9775
Mi ran
Fluorescence NDIRa
GC/FID&
Hg Substitution-UV
Absorption
NDIRa
GC/FID&
GC/FID15
NDIRa
Catalytic Oxidation
Electrochemical
Electrochemical cell
GC/Thermal Conductivity
NDIRa
Electrochemical
Voltammetric
Catalytic Oxidation
Catalytic Oxidation
Thermal Conductivity
NDIRa
Amperometric
DIRC
0.2
0.5
0.05
1
0.01
0.01
ND
0.5
0.25
0.1
10
0.5
1
1
5
1
1
0.03
0.5
NDIR = Nondispersive infrared spectrometer.
GC/FID = Gas chromatograph with flame ionization detection.
DIR = Dispersive infrared.
172
-------
Table C-2. H2S monitors.
Manufacturer
Analytical Instrument
Development
Barton ITT
Bendix/Process
Instruments Division
Canadian Research
Institute
Ecology Board
E.I. du Pont de Nemours
and Co.
Energetics Sciences, Inc.
Hewlett-Packard
IBC Celesco
International Ecology
Sys terns
InterScan Corp.
Meloy Labs, Inc.
Monitor Labs.
Philips Electronic
Instruments
Technicon Industrial
Systems
Thermo Electron Corp.
Tracer
Varian Aerograph
Model
511-19
246,400,
406
8770
HS-2
300
400
Ecolyzer
5830
NS-300
A102S
1170
Series
SA Series
8450
PW9700
Air Monitor
IV
43/340
270H
1490
Method of Operation
GC/FPDa
Amperometric
GC/FPDa
Nondispersive UV and
Visible Absorption
Voltammetric
Nondispersive UV and
Visible Absorption
Electrochemical
GC/FPDa
Voltammetric
Amperometric
Electrochemical
Voltammetric
FPD^
FPD&
Amperometric
Col orimetri c-Methyl ene
Blue
Pulsed Fluorescence
GC/FPDa
GC/FPDa
Sensitivity, ppm
.03
0.03
0.001
ND
2
2
0.1
0.001
1
0.002
0.1
0.0005
0.001
0.001
0.002
0.002
.001
.01
?GC/FPD = Gas Chromatograph attached to
FPD = Flame photometric detector.
flame photometric detector.
173
-------
Appendix D. Recommended methoda for analysis of benzene soluble
fraction total participate matter (BSFTPM).
SAMPLING
Full-shift (8-hour) samples should be collected with a personal sampling
pump (with pulsation damper) at a flow rate of 2 liters per minute. Samples
should be collected on 0.8 micrometer pore size silver membrane filters (37 mm
diameter) preceded by Gelman glass fiber type A-E filters encased in three-piece
plastic (polystyrene) field monitor cassettes. The cassette face cap should
be on and the plug should be removed. The rotameter should be checked every
hour to ensure that proper flow rates are maintained.
A minimum of three full-shift samples should be collected for each job
classification, at least one during the night, if applicable. If disparate
results are obtained for particular job classifications, sampling should be
repeated. It is advisable to sample each shift on more than one day to account
for environmental variables (wind, precipitation, etc.), which may affect
sampling. Differences in exposures among different work shifts may indicate
a need to improve work practices on a particular shift. Sampling results from
different shifts for each job classification should not be averaged. Multiple
samples from same shift may be used to calculate an average exposure for a
particular job classification.
ANALYSIS
The following procedure is for measuring BSFTPM as outlined in the Coke Oven
Emissions Standard:
1. All extraction glassware is cleaned with dichromic acid cleaning solution
and rinsed with tap water, then deionized water and acetone, and it is allowed
to dry completely. It is rinsed with nanograde benzene before use. The
Teflon cups are cleaned with benzene and then with acetone.
2. Preweigh 2-ml Perkin-Elmer Teflon cups to 0.01 mg on a suitable balance
tare (weight of the cups is about 50 mg).
3. Place the silver membrane filter and glass fiber filter into a 15-ml
test tube.
aFederal Register, 1976c.
174
-------
4. Extract with 5 ml benzene for 5 minutes in an ultrasonic cleaner.
5. Filter the extract in 15-ml medium glass fritted funnels.
6. Rinse test tube and filters with two 1.5-ml aliquots of benzene,
and filter through the fritted glass funnel.
7. Collect the extract and two rinses in a 10-ml Kontes graduated
evaporative concentrator.
8. Evaporate down to 1 ml while rinsing the sides with benzene.
9. Pi pet 0.5 ml into the Teflon cup and evaporate to dryness in a vacuum
oven at 40°C for 3 hours.
10. Weigh the Teflon cup. Weight gain is due to the benzene soluble
residue in half the sample.
175
-------
Appendix E. Detailed process information.
The seven coal gasification processes chosen as the basis for this document are
briefly described. Accompanying each description are semi-detailed flow sheets
of the process and the material balances for strategic points within the pro-
cess. Each flow sheet is based on a Process and Instrumentation line diagram
provided by the management of the pilot plant through the Energy Research and
Development Administration, Office of Fossil Energy, Gaseous Fuels Project
Branch. The material balances, provided at the same time, have been altered
in only two respects:
• To show the possible presence of solids elutriated from the gasifier,
where they are not shown in the original balance
a To show the possible presence of coal-derived condensable hydrocarbons
and their distribution where they are not shown in the original balance
The material balances supplied with the information from the C02 Acceptor,
Bi-Gas, and Agglomerating Burner do not indicate the presence of coal-derived
condensable hydrocarbons. Information from the C02 Acceptor pilot plant operat-
ions confirms this lack of condensable hydrocarbons. There is insufficient
information from either Bi-Gas or Agglomerating Burner pilot plants to estimate
either the quantity or distribution of condensable hydrocarbons in either process,
The HYGAS material balance indicates the presence of light oil throughout the
process. There is no indication of its distribution, the MERC Stirred Fixed
Bed information also indicates the presence of condensable hydrocarbons, but
does not define their distribution. In this latter case all gasifier products
are fed to the thermal oxidizer.
Data from the Synthane process indicates that when Pittsburgh seam coal is fed
to the unit, 212 pounds per hour of condensable hydrocarbons are produced.
Bench scale data indicated that 80% of these hydrocarbons were benzene soluble
and that no condensate boiling lower than 100°C was produced. This same data
gave a boiling point curve for the liquids recovered (see Process discussion of
coal gasification). Based on this data the following information was constructed
by guesstimation.
Synthane Condensable Hydrocarbon
Guesstimated Properties
Boiling Range
F C
Light oil
Middle oil
Heavy oil
Residue
272-400
400-600
600-950
+950
133-204
204-316
316-510
+510
Avg. Boiling Point
°F
336
500
775
950
SC
169
260
413
510
Molecular
Weight
150
190
230
400
176
-------
The following assumptions were also made:
• 2.5 wt % solids pass through the gasifier cyclone.
• The scrubber circulating oil is a coal derived middle oil.
• There is no change in oil composition at the Shift Conversion unit.
0 There is no holdup of oil in the Benfield gas purification system.
METHOD OF CALCULATION
It was assumed that normal vapor-phase pressure-temperature relationships held
throughout the system. The vapor pressure was calculated from the "Vapor
Pressure Chart" as shown in the Journal of the Institute of Petroleum Technology
23-311 (1937).* It was further assumed that the gas streams could not contain
condensable hydrocarbons in excess of the saturation limits of the gas. The
results of these assumptions are indicated in the material balances for the
Synthane unit.
* This data was confirmed by J.M. Evans for hydrocarbon condensates derived
by coal liquefaction under an Office of Coal Research contract with Con-
solidation Coal Co., R&D Division, November 24, 1964.
177
-------
SYNTHANE
Coal dried and crushed to a 0.03-inch diameter (minus 20 mesh) is fed to a
Petrocarb lockhopper system. From this lockhopper system it is fed pneumatically,
using steam as the carrier fluid, to a fluidized bed pretreater. Steam and a
controlled quantity of oxygen are used as the fluidizing medium and oxidant to
control pretreater temperature at 800°F (427°C). (Controlled pretreatment to
reduce coal agglomeration is a principal feature of the Synthane process.) The
pretreated coal overflows into the gasifier.
The gasifier is a vertical, single-stage, fluid-bed reactor with an internal
cyclone separator operating at 1500°F (815°C). The fluidized bed is supported
by a funnel shaped grid plate with a central char withdrawal pipe. The fluid-
izing media are steam and oxygen. Coal feed can be located above the bed or in
the bed. Char and ash are continuously removed from the bed by a Petrocarb
lockhopper system or by an emergency water slurry system.
Downstream processes include a conventional water-venturi scrubber plus water
wash, carbon monoxide shift unit, Benfield gas purification and both a Tube
Wall Reactor and a Hot Gas Recycle methanation system. A Stretford unit is
used for sulfur removal.
178
-------
MATERIAL BALANCE
Stream I dent.
Stream No.
Rate. Ibs/hr
Analysis
H2
C02
CH^
02
C2H6
N2
MoO
CO
Light 011
Middle Oil
Heavy 011
MAP Coal
Moisture
Ash
Total
Press. , psig
Temp. , °F
fulverlzec
Coal to
Cyclone
Separator
<$>
1000D cap.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
_
Atmos.
250-300
Pulverized
Coal
to
Storage
A
10000 cap.
-
-
-
-
-
-
-
.
-
-
-
-
-
-
_
Atmos.
100-125
Pulverized
Coal to
Uetgh-
Hopper
/y
6TBO
-
-
_
_
-
-
-
_
-
-
-
5541
154
455
6150
Atmos .
100
-------
TO THE ft MA L
DEOX.'C" Z-CA.
5oi/g.C&- ; LUMMUS
OD
o
MATERIAL BALANCE
Stream I dent.
Stream No.
Rate, Ibs/hr
Analysis
Hz
C02
CH,
02
N2 6
H20
CO
Light Oil
Middle Oil
Heavy 011
MAF Coal
Moisture
Ash
Total
Press. , pslg
Temp., °F
Coal Feed
to
Welgh-
Hopper
A
6150
_
-
-
'
-
-
-
-
-
-
5541
154
455
6150
Atmos.
100
COo to
Storage
Injectors
A
3801*
1.2
3797
3.3
-
-
-
-
-
-
-
-
-
-
-
3801
1100
290
Feed.
C02 to
Primary
Injector
<3>
1946
0.6
1944
1.6
-
-
-
-
-
-
-
-
-
-
-
1946
1100
290
Vent
Gas
§
1855
0.6
1853
1.6
-
-
-
-
-
-
-
-
-
-
-
1855
-
-
High
Pressure
Steam
Feecj
A
1633
-
-
-
-
-
1633
-
-
-
-
-
-
-
1633
1100
800
Oxygen
Fead
_
-
452.7
-
8.6
-
-
-
-
-
-
-
-
461
1100
100
Gas1f1er
Feed
I
0.3
244.5
20.4
-
2.3
8.6
1786.8
18.2
6.2
32.0
23.3
5541
-
455.0
8139
1000
800
Note: The sum of the components may not equal the total because of round!nq.
*Material balance Indicates possibility of traces of light oil when C02
discharged from Stretford unit used here.
-------
AUD Oil-
PIL-OT
CO
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate. Ibs/hr
Analysis
H,
C02
CH^
02
C2H6
N2
H20
CO
Light Oil
Middle 011
Heavy Oil
NH,
H2S
Residue
Coal & Fines
Total
Press. , pslg
Temp., °F
Gaslfler
Feed
8139
0.3
244.5
20.4
-
2.3
8.6
1786.8
18.2
6.2
32.0
23.3
-
-
-
5996.5
8139
1000
800
Gaslfler
Outlet
Gas
3
173.8
5655.3
1349.0
-
81.9
170.9
5907.5
1554.5
10.6
61.5
55.1
86.8
92.0
84.8
150.0
15433
1000
1400
Gaslfler
02
Feed
^
1066
-
-
-
1046.4
-
19.6
-
-
-
-
-
-
-
-
-
1066
1100
100
Gaslfier
Water
Feed
-
-
-
-
-
-
800
-
-
-
-
-
-
-
-
800
975
167
Gaslfler
Steam
Feed
^
5909
-
-
-
-
-
-
5909
-
-
-
-
-
-
-
-
5909
1100
800
Gaslfler
Bottom
Steam
Feed
^
3109
-
-
-
-
-
-
3109
-
-
-
-
-
-
-
-
3109
1100
800
Venturl
Recycle
Water
Feed
<8>
78230
-
-
-
.
.
-
78230
-
-
_
-
-
_
.
-
78230
1080
350
Fluid
Stream
to
Decanter
^6>
5549
_
48
_
_
_
_
5170
_
_
55.0
42
84.1
150.0
5549
1000
396
Scrubber
Water
Ctraila1-
Uon
/\
63970
_
766
_
_
_
_
62500
_
_
_
704
_
_
63970
1010
320
Scrubber
Off-Gas
A
9899
173.8
5606.9
1349.0
„
81.2
170.9
733.2
1554.5
10.6
82.0
0.1
44.3
92.0
Trace
_
9899
990
330
Scrubber
Oil
Circula-
tion
0
_
_
_
_
_
_
_
_
_
8600
_
_
_
_
8600
1010
330
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
H
C02
CH,,
o :
C2H6
N
H20
C
Light Oil
Middle Oil
Heavy 011
NH3
S
Ash
Coal & Fines
Total
Press. , pslg
Temp.. °F
Gasifler
Char
Outlet
<46>
1831
18
-
-
33
-
9
-
1325
-
-
-
-
8
438
-
1831
1000
600
Note: The sum of the components may not equal the total because of rounding.
-------
<£>—s
H. P.
TO
A 8 sex &E. ft.
P/L.OT
5'o u/i. c £ .' LUMMUS
oo
ro
MATERIAL BALANCE
Stream I dent.
Stream No.
Rate, Ibs/hr
Analysis
Ho
Z
CO,
**** £.
CH,,
02
C,Hc
Mr
"2
H20
CO
Light Oil
Middle 011
Heavy Oil
wu
i'tn3
HnS
M2-J
Residue
Total
Press. , pslg
Temp. , °F
Scrubber
Off-Gas
173.8
5606.9
1349.0
81.2
170.9
733.2
1554.5
10.6
82.0
0.1
44.3
92.0
-
9899
990
330
Off-Gas
Fraction
for
Conversion
1
86.9
2803.4
674.5
40.6
85.5
366.6
778.7
5.3
41.0
0.05
22.1
46.0
Trace
4951
990
330
High Pres-
ure Steam
for
Conversion
J
_
-
;
_
2198
_
_
-
-
2198
990
600
Converted
Off-Gas
Stream
A
7149
128.8
3718.9
674.5
40.6
85.5
2189.8
196.1
5.3
41.0
0.05
22.1
46.0
Trace
7149
980
825
Off-Gas
and
Converted
Gas
&
12097
215.7
6522.3
1349.0
81.2
171.0
2556.5
972.0
10.6
82.0
0.1
44.2
92.0
Trace
12097
970
447
Converted
Gas for
Purifica-
tion
A
9315
215.7
6412.3
1349.0
81.2
171.0
14.4
972.0
10.6
0.16
:
88.6
-
9315
965
125
Condensate
from
Converter
A
2779
_
no
-
_
-
2540
-
81.8
0.1
44
3
Trace
2779
970
125
Note: The sura of the components may not equal the total because of rounding.
-------
—0 7XE
/?£CYCi.£- 7XK TAB- TO
DE.CANTEP. AND WASTE. STPE-AM
PILOT PL-AkST
CO
CO
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
C02
CH,,
02
C2H6
N2
II20
CO
Light 011
Middle Oil
Heavy Oil
NH3
H2S
Residue
Coal & Fines
Total
Press. , pslg
Temp. , °f
Fluid from
Surge Tank
to
Decanter
A
5492
48
-
-
-
-
5170*
-
-
-
5.5
42
-
76.3
150.0
5492
1000
396
Condensate
from
Converted
Gas
110
-
-
-
-
2540
-
-
81.8
0.1
44
3
Trace
_
2779
970
125
Tar
to
Thermal
Ox1d1zer
A
*
„
.
-
-
-
*
-
-
-
.
_
_
_
_
.
50
180
C02
Compressor
Condensate
A
100
0.5
-
-
-
-
99.5
-
_
-
-
_
_
_
_
100
0.5
100
Add
Gas
Condensate
A
1X4
_
_
-
-
-
1714
-
_
_
-
_
_
_
_
1714
50
150
dastewater
to
Thermal
Oxldlzer
A
8971
158
_
-
_
-
8724*
_
_
_
_
86
3
_
8971
50
147
Recycle
Tar
to
Gaslfler
_
.
_
-
_
800*
-
_
_
-
_
_
„.
_
800
975
167
Note: The sum of the components may not equal the total because of rounding.
*Decanter liquid feed pressure is dropped from lono psiq to atmospheric. It
is probable that emulsion formation may take place, and therefore the quantity
of oil is questionable.
-------
^BSOHBEK HP(^ P/LTf:Kl
TO MerrtAJVATO«5
CAT 1
P/L.OT
or
oo
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
II,
Z
CO,
^
CH,,
02
Colir
Z b
No
•*/
HoO
"2V
CO
Light 011
Middle Oil
Heavy Oil
H2S
K2C03
KHC03
KHS
Total
Press. , pslg
Temp., °F
Converted
Gas
A
9315
215.7
6412.3
1349.0
81.2
171.0
14.4
972.0
10.6
0.16
-
88.6
_
_
-
9315
965
125
Sweet
Gas
214.1
101.2
1340.9
81.2
171.0
10.8
969.2
10.6
0.16
-
-
_
-
-
2899
964
130
Sweet Gas
to
Fuel Gas
150.0
70.4
939.9
57.1
120.5
5.4
677.8
7.3
0.09
-
-
-
-
-
2029
964
130
Sweet Gas
to
Cooler
A
869
64.1
30.8
401.0
24.1
50.4
3.6
291.3
3.2
0.07
-
-
-
-
-
869
964
130
Sweet Gas
Condensate
A
4
-
.
-
„
-
1.5
-
2.46
0.07
-
-
-
-
-
4
960
95
Sweet Gas
to
Reactors
A
864
64.1
30.8
401.0
24.1
50.4
1.8
291.3
0.8
-
-
-
-
-
-
864
960
95
Purified
Gas to
Hethana-
tors
A
864
64.1
30.8
401.0
24.1
50.4
1.8
291.3
-
-
-
-
-
-
-
864
940
95
Acid Gas
to
Sulfur
Plant
A
670B
1.6
6311.0
8.0
_
-
291.9
2.8
0.8
-
-
88.6
-
-
-
6705
3
120
Rich
Carbonate
Solution
$
158897
-
-
-
_
-
102001
-
-
-
-
-
4882
50510
1504
158897
964
217
Partially
Stripped
Carbonate
Solution
A
114500
-
-
-
I
-
78110
-
-
-
-
-
17630
17520
1240
114500
1000
226
Regener-
ated
Carbonate
Solution
<$>
38000
_
.
-
I
_
26473
-
-
-
-
-
7400
4050
77
38000
1000
237
Carbonate
Stripper
Steam
Feed
A
2000
-
_
-
:
_
2000
_
-
-
-
-
-
-
2000
6
300
Acid Gas
to
Condensate
Jaste Water
A
1714
_
_
-
~
.
1714
_
-
-
-
-
-
-
1714
50
120
Note: The sum of the components may not equal the total because of rounding.
-------
oo
tn
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CHu
02
C2H6
N2
H20
CO
Light Oil
Middle 011
Heavy Oil
H2S
Total
Press. , pslg
Temp. , °F
Add
Gas
1.6
6311.0
8.0
-
-
-
291.9
2.8
0.8
-
-
83.6
6705
3
120
Treated
Gas
<£s>
6531
1.6
6311.0
8.0
-
-
-
207.2
2.8
0.8
-
-
150 ppn
6531
1
105
Off -Gas
to
C02
Recycle
^
3176
0.8
3068.7
3.9
-
-
-
100.3
.1.4
0.4
-
-
150 ppm
3176
1
105
Off-Gas
to
Thermal
Ox1d1zer
0.8
3242.3
4.1
-
-
-
106.4
1.4
0.4
-
-
150 ppm
3355
1
105
Note: The sum of the components may not equal the total
because of rounding.
-------
REMOVAL- UkllT
PILOT
oo
CT)
MATERIAL BALANCE
Stream Ident.
Strean No.
Rate, Ibs/hr
Analysis
H
C02
CH^
0
C2H6
N
H20
C
Light 011
Middle Oil
Heavy Oil
Char
Ash
S
Total
Press. , pslg
Temp. . "F
Gaslfler
Char
Outlet
A
1831
18
-
-
33
-
9
-
1325
-
-
-
.
438
8
1831
1000
600
Slurry
Filtrate
A
23450
-
-
-
-
-
-
23400
-
-
-
-
50
-
-
23450
15
160
Char
Slurry
Tank
Outlet
11
-
-
-
-
-
24100
-
-
-
-
1881
-
-
25981
1090
165
-------
DOW JHE. EM
P/I—OT PL.AUT
00
HATERIAL BALANCE
Stream I dent.
Stream No.
Rate. Ibs/hr
Analysis
H2
C02
CHM
02
C2H6
N2
H20
CO
Light 011
Middle Oil
Heavy 011
Total
Press. , ps1g
Temp. . °F
Purified
Gas
to TWR
Hethanatoi
32.0
15.4
200.5
-
12.0
25.2
0.9
145.7
-
-
432
940
95
Methanatec
Gas
to
Recycle
A
612
1.3
27.7
513.6
-
22.0
45.7
0.9
1.1
-
-
612
920
100
Gas Feed
to
TWR
Methanator
<6>
1044
33.4
43.1
714.1
-
34.0
70.9
1.8
146.8
-
-
1044
940
710
TWR
Methanator
Outlet
Gas
A
1044
2.0
43.1
797.2
-
34.0
70.9
95.1
1.7
-
-
1044
939
715
Cold
Product
Gas
A
371
0.7
15.4
283.6
-
12.0
25.2
33.9
0.6
-
-
371
920
220
Product
Gas
§
338
0.7
15.4
283.6
-
12.0
25.2
0.5
0.6
-
-
338
900
100
Note: The sum of the comnonents mav not equal the total hecause of rounding.
-------
PURIFIED
GAS
P/L.OT
co
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
Cl^
02
C2H6
N2
H20
CO
Light Oil
Middle 011
Heavy Oil
Total
Press. , pslg
Temp.. °F
Purified
Gas
to HGR
Methanator
32.0
15.4
200.5
-
12.0
25.2
0.9
145.7
-
-
432
940
95
Recycle
•tethanatea
Gas
1
4.0
83.6
1540.8
-
65.6
137.0
2.9
3.4
-
-
1837
950
107
HGR
Methanatec
Gas to
Recycle
&
8012
16.5
350.3
6439.7
-
274.2
573.6
343.4
14.0
-
-
8012
915
765
Gas Feed
to
HGR
Methanator
^7>
10281
52.5
449.3
8181.0
-
351.8
735.8
347.1
163.1
-
-
10281
916
700
HGR
Methanator
Outlet
Gas
W
10281
21.2
449.3
8264.1
-
351.8
735.8
440.5
17.9
-
-
10281
915
765
Hot
Product
Gas
4.7
99.0
1824.4
-
77.6
162.2
97.1
3.9
-
-
2269
915
765
Product
Gas
0.7
15.4
283.6
-
'12.0
25.2
0.5
0.6
-
-
338
900
100
Final
Methanator
Gas Feed
(HGR)
1.1
15.4
282.6
-
12.0
25.2
0.5
2.2
-
_
"
339
900
600
Alternate
Effluent
Drum
Condensate
_
_
-
-
_
-
93
-
.
_
"
93
900
100
Note: The sum of the components may not equal the total because of rounding.
-------
HYGAS (STEAM-OXYGEN CONFIGURATION)
Coal is crushed to 0.125-inch diameter (6 mesh) and dried. Agglomerating coals
are pretreated at atmospheric pressure and 750° to SOOT (400°C to 427°C). The
prepared coal is then mixed with toluene and the slurry is pumped with a Wilson
Snyder pump to the reactor pressure of 1000 to 1500 psi.
The hydrogasifier is a vertical reactor divided into four fluid-bed sections.
The coal slurry is fed into the top section, where the toluene is vaporized by
the 1300°F (705°C) gas from stage two and the solids then fall into stage two.
In stage two light ends and reactive portions of the coal are gasified. The
partially gasified coal then falls down a standpipe to a pot, where is is pneu-
matically lifted to stage three by the 1700°-1800°F (925°-980°C) producer gas
from stage four. The "instantaneous" transition to the higher temperature is
claimed to reduce production of heavy oils. The heavy volatile material is
gasified in this section as is a portion of the hydrogen-rich solid by the
hydrogen-rich producer gas from the fourth stage. Char from the third stage
overflows into the fourth stage, where it is burned with the steam-oxygen
fluidizing gas to produce the process heat and the producer gas used in the
other stages. The unreacted residual char is removed as a water slurry and
filtered.
Downstream processes include a venturi scrubber, no carbon monoxide shift unit,
a diglycolamine gas purification system and both a hot gas recycle methanator
with a packed bed and the Chem Systems, Inc., liquid phase methanation system.
A Claus unit is used for sulfur removal.
189
-------
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CH,,
02
C2H6
N2
H20
CO
Light Oil
Middle Oil
Heavy Oil
MAP Coal
Ash
Moisture
S
Total
Press. , |)sig
Temp. , °F
'ulverlzed
Coal to
Cyclone
Collector
12200 cap,
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
< Atmos.
300
'ulverized
Coal to
Storage
12200 cap.
-
-
-
-
-
-
_
-
-
-
-
-
-
-
-
-
-
-
'ulverized
Coal to
Screw
Feeder
6000
-
-
-
-
-
-
_
.
-
-
-
4742
622
636
.
6000
Atmos.
-
Coal Dust
to
Edens
Separator
0
10125
_
_
-
-
-
-
10000
_
_
_
198
13
13
1
10125
Atmos.
-
NOTE: Material balance based on
data presented in paper
given at the seventh
Synthetic Pipeline Gas
symposium by Bernard S. Lee,
October 27-29, 1975.
-------
COAL-*
TO 5PFNT
QUENCH TAW<
1&-
-*- TO LIGHT OIL
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
II2
C02
CH,,
02
C2H6
N2
H20
CO
Light Oil
Middle 011
Char
MAF coal
Moisture
Ash
H2S
Total
Press. , psig
Temp., °F
Feed to
Slurry
Tank
A
17801
-
-
-
-
-
396
-
-
11405
-
-
4742
636
622
-
17801
Atmos.
300
Vent from
Slurry
Tank
-
-
-
-
-
-
-
-
605
-
-
-
-
-
-
605
Atmos.
300
Feed to
Gasifier
\y
17196
-
-
-
-
-
396
-
-
10800
-
-
4742
636
622
-
17196
1100
300
Sparger
to
Gasifler
-
-
-
795
-
_
7176
_
-
-
-
-
_
-
-
7971
1520
1133
Gasifler
Overhead
to
Cyclone
<8>
24Xl
150
3265
627
-
23
396
6573
589
12271
_
_
195
103
19
24211
1050
650
Water to
Cyclone
\}
4626
_
.
.
.
.
_
4626
_
_
_
_
_
_
_
_
4626
1000
Ambient
Effluent
Stream
Gasifier
to Dis-
charge Pot
A
21932
_
_
_
_
_
10098
_
11531
_
195
5
103
21932
30
150
Spent
Char
A
1320
_
_
_
_
_
_
.
1320
1320
1150
1509
NOTE: Material balance based on
data presented in paper
given at the seventh
Synthetic Pipeline Gas
symposium by Bernard S. Lee,
October 27-29, 1975.
-------
/=M UiGtJT e>xA
L IG.HJ- 0/L.
7-0 WA 2 T£ TA A/fc
£A\J\I GA
S
. purnp
UD
tVI
MATERIAL BALANCE
Stream I dent.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CHM
02
C2H6
N2
H20
CO
Light 011
Middle Oil
Heavy Oil
II2S
s
Total
Press. , pslg
Temp. , °F
Effluent
Stream
to
Quench
System
A
M10
150
3265
627
-
23
396
1101
589
740
-
-
19
-
6910
1000
600
Effluent
Quench
Tower to
Purifi-
cation
A
5065
150
3262
627
-
23
396
-
588
-
-
19
PPm
5065
975
140
NOTE: Material balance based on
data presented 1n paper
given at the seventh
Synthetic Pipeline Gas
symposium by Bernard S. Lee,
October 27-29, 1975
-------
TO
HYGAS p/LOJ-
UD
OJ
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
C02
CH,,
02
C2H6
N2
H20
CO
Light Oil
Middle Oil
Heavy Oil
H2S
S
Total
Press. , psig
Temp. , °F
Effluent
Quench
Tower to
Purifi-
cation
A
5065
150
3262
627
-
23
396
-
588
-
-
-
19
ppm
5065
975
140
Scrubbed
Gas
Effluent
1465
83
411
356
-
31
243
_
335
-
-
-
-
-
1465
975
150
Purified
Gas
to
lethanator
4
83
356
-
37
243
.
335
-
_
_
_
-
1054
975
100
NOTE: Material balance based on
data presented in paper
given at the seventh
Synthetic Pipeline Gas
symposium by Bernard S. Lee,
October 27-29, 1975.
-------
<§>
EF
CLUZMT A/>
c.oe>/L
-------
UD
cn
MATERIAL BALANCE
Stream I dent.
Stream No.
Rate. Ibs/hr
Analysis
H2
C02
02"
C2H6
N2
H20
CO
Light Oil ,
Middle Oil'
Heavy Oil
S02
Fines
Total
Press. , psig
Temp. , °F
^retreater
Feed
\y
6700
-
-
_
-
-
-
-
-
-
-
-
_
6700
Atmos .
Ambient
Effluent
Gases
from
Pretreatet
Reactor
A
9140
-
457
183
-
4588
3153
375
{73
55
119
137
9140
5
800
To
Edens
Separator
A
186
_
-
_
-
-
-
-
-
-
53
-
133
186
-
-
To Incin-
erator
A
9960
_
458
179
_
4592
4153
379
-
-
-
80
115
9960
.
-
* Dry crushed bituminous coal.
-------
UD
O-l
S
TO BLOW DOWN TAMK.
PL A A//-
/ 9/S
NOTE: No data available to calculate material balance.
-------
NOTE: No data available to calculate material balance.
-------
IT)
oo
LIGHT OIL
STI^IPPEK
-TO 5DEWS
OR FH.TEK. FZED
To
£>o 7/"o/v7j-
EOeA/5 SEPARATOR,
OK. FILTER. FEE.D r/)W<
P/
-------
'-O
NOTE: No data available to calculate material balance.
-------
C02 ACCEPTOR
Lignite or sub-bituminous coal is crushed to 0.006-inch diameter (minus 100
mesh) and dried. The coal is then preheated to 350 to 500°F (178° to 260 C).
A normal lockhopper system is used to feed the coal into the gasifier.
The C02 Acceptor system uses a two-vessel system. The gasifier is a single-
stage, fluid-bed reactor with an internal cyclone that operates at 1520 F (825 C)
and 150 psi. Steam is fed to the bottom of the reactor, both to fluidizeothe
solids and to supply hydrogen through the steam carbon reactor. The 1850 F
(1000°C) calcined dolomite or limestone acceptor showers into the top of the
reactor, falling countercurrent to the rising gas. The acceptor is collected in
a boot at the bottom of the gasifier and is returned pneumatically to the re-
generator. Char is withdrawn from the middle of the bed and also fed pneumat-
ically to the regenerator.
The heat for the gasification reaction is supplied in part by the hot acceptor
but primarily by the chemical reaction between the calcined dolomite and carbon
dioxide:
CaO
calcined
limestone
CO;
carbon
dioxide
CaC03 + heat
1imestone
This reaction results in the production of more hydrogen by eliminating a large
portion of the carbon dioxide and unbalancing the water gas shift reactor equi-
librium to force the production of hydrogen. The limestone also reacts with
the hydrogen sulfide in the system.
The regenerator is a single-stage, fluidized-bed vessel that operates at 1850°F
(1000°C) and 148 psi. The crushed and sized dolomite (8x14 mesh) is fed to the
regenerator through a lockhopper similar to that used to feed coal to the gas-
ifier. Air is used to fluidize the bed and to burn the spent char to ash,
thereby supplying the heat to reverse the caronation reaction and to heat the
calcined dolomite. The calcined dolomite is transferred pneumatically to the
gasifier. Ash is entrained with the hot combustion gas from the regenerator
and cooled in a venturi scrubber.
The downstream product gas system includes a water-venturi scrubber plus a
dish-and-donut quench tower, no carbon monoxide shift unit, a Benfield gas
purification unit, and a fixed-bed methanator employing a patented catalyst.
200
-------
ro
/S£ 6E. A/£/2
MILL
CO. - ACCErPrOR P/LQT PL-ALIT
o
MATERIAL BALANCE
Stream I dent.
Stream No.
Rate, Ibs/hr
Analysis
CaC03
MgC03
Other
MAP Coal
Moisture
Ash
Char
Total
Press. , pslg
Temp., °F
Raw
Acceptor
A
72800
70200
864
936
-
-
-
72000
0
Ambient
Sized
Acceptor
A
(#95
8575
106
114
-
-
-
8795
0
Ambient
Raw
Coal
A
12769
.
-
-
7719
4469
561
12769
0
Ambient
Coal Feed
and
Oversize
\)
12769
.
-
-
7719
4469
581
12769
0
Ambient
Char
A
60000
.
-
-
-
6000
-
54000
60000
0
Ambient
-------
FM.
IX)
o
ro
d00 - ACC&PTQP PILOT PL-AMT
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate. Ibs/hr
Analysis
Moisture
CaCOs
HgCOs
Other
MAP Char
C
Hz
N2
S Total
Ash
02
C02
CaO
MgO
CH.,
CO
Inert
Total
Press. , pslg
Temp. , °F
Sized
Acceptor
A
8^95
8575
106
114
-
-
_
_
-
-
-
_
_
-
-
-
-
8795
0
Ambient
Sized
Char
4>
5000
100
-
-
-
4900
-
-
-
-
-
-
-
_
-
-
_
-
5000
0
125
Coal to
Preheater
xy
4211
211
-
-
-
-
4000
_
-
-
-
_
-
-
-
-
-
_
4211
0
100
Sized
Acceptor
A
600
.
585
1.2
7.8
-
-
-
-
-
-
-
-
-
-
-
-
-
600
168
Ambient
Sized
Char
46
1
-
-
-
45
-
-
-
-
-
-
-
-
-
-
-
-
46
156
Ambient
Coal to
Gasifier
2874
144
-
-
-
-
2730
_
_
-
_
-
-
-
-
-
-
2874
155
300
Recarb
Acceptor
<&
12000
_
-
-
-
-
-
-
-
24
-
-
1080
9120
324
-
-
1452
12000
168
1450
Fuel Char
from Gas-
ifier to
Regenerator
A
fil7
_
-
-
-
-
817
_
_
_
-
-
-
-
-
-
-
817
150
1450
Acceptor ir
Fuel Char
from Gas-
ifier to
Regenerator
A
18DO
_
-
-
-
-
-
-
-
2
-
-
715
911
32
-
-
140
1800
150
1450
Calcined
Acceptor
<$>
10450
_
-
-
-
-
-
-
-
21
-
-
84
8777
38?
-
-
1181
10450
149
1800
Gasifier
Overhead
Solids
Withdrawal
_
-
-
-
71
-
1
-
Trace
7
26
-
-
-
-
-
-
105
148
450
Gaslfier
Overhead
Gas
\7
3475
1180
-
-
-
25
-
1319
75
-
-
-
224
-
-
306
296
-
3425
148
450
-------
TO
-ACCEiPTQR P/L-QT PLA/W7"
ro
o
CO
MATERIAL BALANCE:
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
Moisture
Char
C
H2
N2
S Total
Ash
02
Total
Press. , pslg
Temp.. °F
Coal from
! Cyclone
A
56M
284
_
3564
243
27
27
378
1161
5684
0
200
Coal to
'reheater
1
211
_
2640
180
20
20
280
860
4211
0
100
-------
OXIDI7.ER.
G)U£MC-H5V
GX>S TO
A>ec.ycLe
R/L.OT PL.AL1T
ro
o
MATERIAL BALANCE
Stream I dent.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CH^
02
C2H6
N2
H20
CO
Moisture
Char
S
Total
Press. , psig
Temp. . °F
Gasifier
Overhead
Gas
\y
3425
1319
224
306
-
-
75
-
296
1100
25
3425
148
450
Solids in
fjuench
Tower
Water
A
37
1
-
11
-
-
-
-
-
_
_
Trace
37
146
120
Approximately 25% of the gasifler quench tower
product is used for controlling the system
pressure. The balance is directed to the thermal
oxidizer or the methanator, as conditions warrant.
-------
TO
TO
-ACCEPTOR PILOT
ro
o
en
HPC - 3 HYOROXY-2-PHENYLCINCHONINIC ACID
MATERIAL BALANCE
Stream I dent.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CH,,
02
C2H6
N2
H20
CO
Light Oil
Middle Oil
Heavy Oil
H2S
Total
Press. , pslg
Temp. , "F
Flue Gas
from
Regener-
ator
fy
10178
20
2840
-
-
-
7175
-
143
-
-
-
Trace
10178
146
775
-------
BI-GAS
Coal is crushed to 0.003-inch diameter (minus 200 mesh) in a roll mill, then
mixed into a water slurry. A triplex pump is used to pressurize the slurry to
1500 psig. A preheater heats the slurry to 1000°F (538°C) and the gas and solids
are separated in a flash tank-cyclone combination.
The gasifier is a vertical, two-stage, fast-fluid-bed reactor. The preheated
coal is fed to the top stage, where it contacts the hot (2700° to 3000°F, [1480°
1650°C]) hydrogen-rich producer gas from the bottom stage. The coal reacts to
form a methane-rich gas and char. Gas and char are swept out of the top of the
reactor at 1700°F (925°C) to a cyclone, which returns the solids to the lower
stage reactor. The char is gasified with steam and oxygen and the ash is melted.
The resulting slag falls from the lower stage into a pool of quench water and
is removed from the reactor.
Downstream processes include a conventional water-venturi scrubber-cooler, a
carbon monoxide shift unit, a Selexol gas purification unit and both a fluidized
bed and a conventional packed-bed methanator. A Claus unit is used for sulfur
removal.
206
-------
$
^ ,
(A
v'i
r;
liAKL-L'£
-C-OAL
C-YC-l <~>UR-
To ^LUR^f
bLtlUD
"y\
— -I
GF21
J=3
X^CWJTS
;
;
DM;
WLL.
\
\
\
•'I t^L
^EYI
^
'
} P'
1
1
1
v\-ir£.i?
BLEN/D TflNK
PULP sTo&A6t
COAL hi AM PL
o
--J
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate. Ibs/hr
Analysis
H2
C02
CM,,
02
C2H6
N2
H20
CO
Light Oil
Middle 011
Heavy 011
Coal
Flux
Ash
Total
Press. , pslg
Temp. , °F
Coal
from
Storage
$
15000
-
-
-
-
-
-
1000
-
-
-
-
14000
-
-
15000
Atmos.
Ambient
Coal
from
Cyclone
A
38TOO
-
-
-
-
-
-
19000
-
-
-
-
19000
-
-
38000
Atmos .
Ambient
Coal
from
Grinding
Mill
A
38DOO
-
-
-
-
-
-
19000
-
-
-
-
19000
-
-
38000
Atmos.
Ambient
Coal
from
Pulp
Tank
A
94DOO
-
-
-
-
-
-
61000
-
-
-
-
33000
-
-
94000
Atmos .
Ambient
Coal
from
Coal
Cyclone
A
56MO
-
-
-
-
-
-
42000
-
-
-
-
14000
-
-
56000
Atmos.
Ambient
Coal
to
Centrifuge
A
52TOO
-
-
-
-
-
-
39000
-
-
-
-
13000
-
-
52000
Atmos.
Ambient
Centrifuge
Coal
Bypass
0
4000
-
-
-
-
-
-
3000
-
-
-
-
1000
-
-
4000
Atmos.
Ambient
Coal-
Centrifuge
to
Thickener
A
3«00
-
-
-
-
-
-
33400
-
-
-
-
1000
-
-
34400
Atmos.
Ambient
Coal-
Centrifuge
to
Pulp Tank
A
17^00
-
-
-
-
-
-
5600
-
-
-
-
12000
_
-
17600
Atmos.
Ambient
Coal to
Slurry
Blend
Tank
A
27600
-
-
-
-
-
-
17800
-
-
-
-
9097
-
703
27600
25
60
Coal
from
Pulp
Storage
A
15600
-
-
-
-
-
-
69200
-
-
-
-
86800
-
-
156000
Atmos.
Ambient
Coal
Recycle
Pulp
Storage
A
12OTOO
-
-
-
-
-
-
51400
-
-
-
-
77000
_
-
128400
Atmos.
Ambient
Flux to
Pulverlzec
Flux
Bin
A
i¥o*
-
-
-
-
-
_
-
-
-
-
-
_
1100
-
1100
Atmos.
Ambient
'ESTIMATED NORMAL ADDITION RATE WHEN REQUIRED.
-------
X X
r7~\
1
1
1
1
-***J — 1
s
.5 L UK. S- Y
^TO COfiL HYCLONE VESSEL.
£ AA.
3LUP&Y
&CR.
PILOT
DRYlklG
o
oo
MATERIA
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
02"
C2H6
N2
II20
CO
Light Oil
Middle Oil
Heavy Oil
Coal Ash Free
Ash
Total
Press. , pslg
Temp. , °F
Coal to
Slurry
Blend
Tank
A
27600
-
-
.
-
-
17800
-
-
-
-
9097
703
27600
25
60
Flux to
'ulverizec
Flux
Bin
A
DODO
_
-
.
-
-
-
-
-
-
-
_
0000
0000
Atmos .
Ambient
BALANCE
Coal
to
Slurry
C1rc.
Pumps
A
46032
_
-
_
-
-
29700
-
-
-
-
15160
1172
46032
5
60
Coal
Slurry
Reclrcu-
lating
Stream
A
18432
_
-
_
-
-
11900
-
-
-
-
6063
469
18432
80
60
Coal
Slurry
thru Pre-
leater to
Spray Drier
/x
27600
_
-
_
-
-
17800
-
-
-
-
9097
703
27600
1175
475
N2-Coal
to
Coal
Cyclone
A
251300
_
-
_
-
223700
17800
-
-
-
-
9097
703
251300
1210
550
-------
>- TO CO
THERMAL OXIOI2ER.
CLARIFIED
sues OUTLET- OX,Y<5£A/
LOCK HO PP€ si
2221/
ro
o
MATERIAL BALANCE
Stream I dent.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CHM
02
C2H6
Nz
H20
CO
Light Oil
Middle 011
Heavy Oil
Coal Ash Free
Ash
Char Ash Free
H2S
Total
Press. , pslg
Temp. , °F
N2-Coal
to
Coal
Cyclone
A
25T300
-
-
-
~
-
223700
17800
-
-
-
-
9097
703
-
-
251300
1210
550
(Each)
Slurry to
Gasifler
Upper Stage
o«
V 5001 V
-
-
-
~
-
-
100
-
-
-
-
4549
352
-
-
5001
1175
475
(Each)
Slurry to
Slag
Outlet
Hoppers
A*
40B68
-
-
-
-
-
-
40000
-
-
-
-
-
668
-
-
40668
1150
170
(Each)
Slag
Slurry
to Pond
f"
-
-
-
-
-
_
1057
-
-
-
_
_
668
_
-
1725
1150
170
Raw Gas
from
Gasifler
A
54811
937
10762
1649
-
-
62
22001
9442
-
-
.
_
1152
8523
283
54811
1150
800
(Each Leg)
Char
to
Gasifler
A
3176
-
-
-
-
-
_
-
-
-
-
_
„
372
2754
-
3126
1145
800
Raw Gas
from
Cyclone
A
451(31
937
10762
1649
-
_
62
22001
9442
-
-
-
_
435
260
283
45431
1145
800
Recycled
Purge
Gas
A
2042
88
1068
146
-
_
_
-
740
-
-
.
_
_
_
-
2042
1145
100
Gas
to
Washer
A
47^73
1025
11830
1795
-
_
62
22001
Hi 1ft?
-
-
_
_
35
260
283
47173
IMG
GOO
Scrubbed
Raw
Gas
A
36490
1025
11830
1795
-
-
62
11313
10182
-
-
_
_
_
_
283
36490
1145
440
Char Slurry
to Atmos-
pheric
Vent Gas
Washer
4^
109B3
-
-
-
-
-
-
10688
-
-
-
_
_
35
260
-
10983
1145
440
Char
Slurry
to Water
Treatment
A
10983
-
.
-
-
-
-
10688
-
-
-
-
_
35
260
-
10983
10
150
*These lines operate alternately.
-------
co SHIFT
&/-GAS PILOT
oo
- /- 004-)
MATERIAL BALANCE
Stream I dent.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CHH
02
C2H5
N2
H20
CO
Light Oil
Middle Oil
Heavy Oil
H2S
Total
Press. . pslg
Temp., °F
Scrubbed
Raw
Gas
A
36490
1025
11830
1795
-
-
62
11313
10182
-
~
-
283
36490
1145
440
Sulfur
Conversion
Feed to
Reactor
A
17132
481
5554
842
-
-
28
5318
4776
-
~
-
133
17132
1144
440
Shift
Converter
Gas Feed
A
19358
544
6276
953
-
-
34
5995
5406
-
~
~
150
19358
1144
440
Shift
Converter
Steam
Feed
A
6159
-
-
-
-
-
-
6159
-
-
~
~
~
6159
1105
765
Shift
Converter
Total
Feed
A
25517
544
6276
953
-
-
34
12154
5406
-
~
~
150
25517
1105
580
Shift
Converter
Reactor
Effluent
7
848
12899
953
-
-
34
9443
1190
-
~
~
150
25517
1095
790
Sulfur
Conversion
Reactor
Effluent
&
17132
481
5554
842
-
-
28
5318
4776
-
~
-
133
17132
1144
440
Combined
Effluent
Gas to
K.O. Drum
19
1328
18454
1795
-
-
62
14761
5966
-
~
-
283
42649
1060
105
Cooled Gas
to Gas
Treating
Section
A
27757
1328
18314
1795
-
-
62
23
5966
~
~
269
27757
1060
105
-------
<^
TO
..MAKE-UP ^XIDIZe.^
WATFR
rFh rp-i rFh
^
/
/yfr/'
6/1S itJ-Lii/e
SEft* RA Ton
ZHO 3I<*. (,u^ <=r
A&SO&.&E: H. I C
(SELCXOL)
cowe/weo
(JS> Efn-UENT K.O. O^OM
G^
970
-
670
-
-
-
-
23
-
-
-
-
269
-
970
20
105
Waste Gas
to Thermal
Ox1d1zer
^2>
V
2
15443
59
-
-
-
20
45
-
~
-
-
2619
18108
20
40
-------
t A?/
t
"^
•4
y C-.AT". ~^f\uic
,1
JU
J'E^, ^f^r
U
£>er<3
r_D
1. J
/•7/p >
^
(
'
&&CR &!'GA$ PILOT
I COHDEHSflTE.
DRUM
IJ4—-^
BLOWOOV/AV
-OOL.
ro
ro
MATERIAL BALANCE
Stream I dent.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CH,,
02
C2H6
N2
H20
CO
Light 011
Middle 01T
Heavy Oil
H2S
Total
Press. , pslg
Temp. , °F
Gas to
Methanator
'
1170
598
2316
-
56
-
5207
-
~
-
5ppm
9347
1016
80
Fluid Bed
Methanator
Total
Feed
&
9347
1170
598
2316
-
56
-
5207
-
—
-
9347
998
80
Fluid Bed
tethanator
Effluent
4^
9347
157
598
5000
-
56
3015
521
-
~
~
9347
970
750
Fluid Bed
Reactor
Effluent
K.O. Drum
7
157
598
5000
-
56
3015
521
~
~
~
9347
960
500
Secondary Methanator
Effluent
No. 1 No. 2
Reactor Reactor
^6> <47>
9347 9347
69 42
577 577
5229 5300
-
56 56
3281 3361
135 11
~
-. _
_
9347 9347
945 935
800 650
Compressor
Recycle
4^
10732
76
1039
9492
-
92
13
20
-
-
-
10732
935
105
Total to
Suction
K.O. Drum
^>
20079
118
1616
14792
-
148
3374
31
-
-
-
20079
930
120
Effluent
from Pro-
duce Gas
K.O. Drum
<6^
16739
.118
1616
14792
-
148
34
31
-
-
-
16739
930
120
Product
Gas
to
Selexol
)
42
577
5300
-
56
12
11
-
-
-
5998
925
105
Gas to
Recycle
Compressor
4b
v
76
1039
9492
-
92
22
20
-
-
-
10741
925
120
-------
SLA G D/SPOSA L
&J-&AS P/LOJ
TA/Jk?
PUMPS
fj r
PUMPS'
z>i
/•
Pi
t/
3U
1
fl*
A
^
fjl
/A i
IF
> WE/B
~—
^
T *•- ~ *~
L
W£/e-
p 0 Jj D
n;
,
-V — 1 |
1
1
.
—
-
/0//S/73.
Note: No data available to calculate material balance.
-------
ATM
Ac. ip
£>LO\MPOWA/
c-OAtD£rJ
fc_
/-
k
i
.
£ri
L w^
1
' i r
1 50iJ=^72.
.1 '' '1 "
II II II '
•M. .. i"
i, ,i ii n
JJL,-!! i'
f C,<=>rtD&
1 *
U >^ '
J* (
&/-GAS P/LOJ
~T~K. uc-jf.
Note: No data available to calculate material balances.
-------
AGGLOMERATING BURNER
Coal Is crushed to two different sizes, 0.09 x 0.006 inch (8 x 100 mesh)
particles for the gasifier and 0.006-inch (minus 100 mesh-diameter) particles
for the burner. Recirculating hot air dries the coal. The operation has two
reactors — the gasifier and the burner.
The gasifier is a vertical, single-stage reactor operating at 1800°F (980°C)
and 100 psig with an internal cyclone separator. Coal is fed into the reactor
by lockhoppers, and steam is fed into the bottom of the reactor, fluidizing
the coal bed. Hot agglomerates are formed when small residual ash particles
are released from the coal and stick together. They are then fed into the top
of the reactor, shower down through the coal bed, transfer heat to the coal
gasification reaction, and are removed from the bottom of the reactor. The
cyclone removes solids from the synthesis gas stream, and returns them directly
to the coal bed via a standleg. Ash and excess agglomerates are removed by
lockhopper from the bottom of the reactor to disposal. Char and agglomerates
are removed and fed into the burner.
The burner is a vertical, single-stage reactor operating at 2100°F (1150°C).
Char and ash agglomerates from the gasifier, compressed air, and coal by lock-
hopper are fed into the burner. The coal, char, and air combust to heat the
recycling agglomerates. These are then continuously transferred back to the
gasifier by a steam lift.
Off-gases from both units are passed through cyclone separators, scrubbed in
a venturi, and thermally oxidized. Burner flue gas may pass through a heat
exchanger and a gas turbine energy.
215
-------
ro
en
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CH,,
02
C2H6
N2
H20
CO
Light 011
Middle Oil
Heavy Oil
Moisture
MF Coal
Total
Press. , pslg
Temp. , °F
incoming
Coal
A
10666
-
-
-
-
-
-
-
-
-
-
-
1066
9600
10000
Atmos.
Ambient
'ulverlzed
Coal to
Vibrating
Screen
A
11600
-
-
-
-
-
-
-
-
-
-
-
464
11136
11600
Atmos.
200
Pulverized
Coal to
Cyclone
Separator
A
4200
-
-
-
-
-
-
-
-
-
-
-
168
4032
4200
Atmos.
200
Oversized
Coal to
Coal
'ulverlzer
<4>
5800
-
-
-
-
-
-
-
-
-
-
-
232
5568
5800
Atmos .
200
Screened
Coal to
Gasifler
Feed Bin
\y
58CO
-
-
-
-
-
-
-
-
-
-
-
232
5568
5800
Atmos .
2QO
Coal to
)ombuster
Feed Bin
A
4200
-
-
-
-
-
-
-
-
-
-
-
168
4032
4200
Atmos.
200
-------
f" ,"X£ T££,A ^E&
COAL-
AGQLQMERATIMG
LAPS
AIR,
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CH,,
02
N2 6
H20
CO
Light Oil
Middle Oil
Heavy Oil
Moi s ture
MF Coal
Total
Press. , psig
Temp. , °F
Screened
Coal to
Sasifler
:eed Bin
A
5800
_
_
_
-
_
-
_
-
-
_
232
5568
5800
Atmos.
200
Coal to
Combuster
Feed Bin
/\
4200
_
_
_
-
I
_
_
_
_
_
168
4032
4200
Atmos.
200
Coal to
)ombuster
/7\
1018
_
_
_
-
_
_
_
_
_
41
977
1018
200
175
Coal to
Gasifier
/\
1276
.
_
_
-
_
_
_
_
_
51
1225
1276
150(max)
175
-------
F/CAT/O/J
AGGLOMERATING bURNk-R PLANT C3
cwg. c\v
/97-f.
INi
CO
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
02"
C2H6
N2
H20
CO
Light Oil
Middle Oil
S02
H2S
Ash
MF Coal
Char
Total
Press. , pslg
Temp. , "F
Coal to
Gaslfler
A
1279
5
13
_
-
-
-
36
-
_
-
-
-
1225
-
1279
150(max)
175(max)
Coal to
Combustor
1165
-
-
45
-
143
-
-
-
-
-
-
-
977
-
1165
120(max)
175(max)
Combustor
Off-Gas
^
12042
-
2690
259
-
8539
452
-
-
-
47
-
55
-
-
12042
100
2050
Gaslfier
Off-Gas
)
191
471
_
-
14
584
1448
-
-
-
27 .
-
-
105
2840
100
1800
Char
A
244
-
-
_
-
-
-
-
-
-
-
-
-
-
244
244
100
1800
Gaslfler
Gas to
Scrubber
2295
191
31
_
-
14
584
1448
-
-
-
27
-
-
_
Z295
100
180
Combustor
Gas to
Scrubber
A
11993
-
2690
259
-
8539
452
-
-
-
47
-
6
-
_
11993
100
2050
Ash from
Combustor
to Gaslfler
\/
41041
-
-
_
-
-
450
_
_
-
-
40591
_
_
41041
100
2050
Ash from
Gaslfler to
Combustor
XX
44102
-
-
586
-
1925
.
-
-
-
-
41591
-
-
44102
100
1500
Ash from
Combustor
to Letdown
Hopper
<8>
47
-
-
I
.
-
_
_
-
-
-
-
47
-
-
47
100
2050
-------
F=-fLO>*-( (jj> I
COMKjb-s.Toe. /X
C^A^
SE-p^RATDK
•i i
1 « ' ^
I_J
.
it
J '
m i ,
POMP
ro
UD
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CH,,
02
N2 6
H20
CO
Light 011
Middle Oil
Heavy 011
SO 2
H2S
Total
Press. , psig
Temp. , °F
Gaslfier
Gas to
Scrubber
<$>
2295
191
31
,
-
14
584
1448
-
-
-
-
27
2295
100
180
)ombustor
Gas to
Scrubber
<^>
11993
_
2690
_
259
8539
452
_
„
_
_
47
-
11993
100
2050
Combustor
Gas to
:ombustor
Furnace
<^>
17292
_
2690
-
259
8539
5757
_
_
-
..
47
-
1 7292
90
279
aslfler
Gas to
ombustor
Furnace
A
4774
191
471
_
-
14
2623
1448
_
_
_
_
27
4774
90
281
&LOVJER
-------
COAL PR E.TP/L AT/WE A7T
PLA/JT
ro
o
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
02"
N2 6
H20
CO
Light Oil
Middle Oil
Heavy Oil
MF Coal
Solids
Total
Press. , psig
Temp. , °F
Gasifier
Feed Bin
TO Pre-
treater
A
1339
-
-
-
.
-
_
-
1339
-
1339
Atmos .
175
1
Gas From
'retreaten
5
-
194
19
701
360
-
c-
-
Trace
1315
-10*
750
Pretreater
Gas To
ombustor
Furnace
i
-
194
19
701
541
_
"
_
-
1455
-30*
175
'retreatei
Coal To
Gasifier
Feed Bin
i
-
-
-
_
-
_
-
1225
1225
Atmos.
250
* Inches of water.
-------
MERC STIRRED FIXED BED
Coal is broken to 2.0 x 0 inches and fed into a normal lockhopper system. The
coal is then fed directly from the lockhopper to the gasifier.
The gasifier is a fixed-bed unit with a rotating ash grate. It is also fitted
with a vertical agitator, capable of both rotation and vertical movement, to
insure uniform distribution of coal in the bed and to break up agglomerates.
The reactor operates at 2500°F (1370°C) and at up to 300 psig. Air or oxygen
and steam enter the reactor below the grate so that gas flow is through the bed.
The product gas is removed from the top of the reactor to a venturi scrubber,
which cools the product for sampling before it is sent to the thermal oxidizer.
221
-------
™ '1 "i
•zAt-
P ETf<,
TV*1 T~& •&-
•<8» — (S^
^.-»U
1 i
— f- ,uct
GftS
K
f
TO
As//
Er P C - ST
P I «- QT
r-o
ro
IN)
Operating Data,
Feed Coal
HHV of coal .
Btu/lb
Gas Analysis
CO
C02
N2
H2
CHM
C2H6
H2S
Heating Value
Btu/scf
Test Results:
West Virginia
Pittsburgh Bed
13,850
19.1
8.8
55.4
12.8
2.9
.3
.5
140
New Mexico
Sub-bituminous
8,900
15.3
12.7
59.3
10.7
2.1
.0
.2
105
-------
STEAM- IRON
For the pilot plant, char is crushed to 0.06-inch diameter (12 mesh), mixed as
a water slurry, and pumped to 1000 psig. The slurry is vaporized and the steam
conveys the char to the top of the preheater. The steam-iron process has two
reactors — the producer and the steam-iron reactor.
The producer is a vertical, two-stage reactor. The char is fed into a char bed
in the top section (preheater) and partially oxidized with steam and air at
1750°F (950°C). Off-gas is removed from the top and the hot char drops to the
bottom stage to make a fluidized bed with steam and air. The char reacts at
2000°F (1090°C) to produce H2 and CO, which is removed from the top of the lower
stage. Ash is removed from the bottom of the reactor.
The H2 and CO enter the top section of the vertical, two-stage iron-steam reactor,
and fluidize a bed of iron oxide at 1500°F (815°C). In the bed the producer gas
and iron oxide react to reduce the oxide to iron as follows:
Fe304 + 2H2 + CO - * 3Fe + 2H20 + C02
The upper stage has two sections for greater efficiency. The spent gas is
removed from the top of the reactor, and the iron falls to the lower stage,
creating a bed fluidized by steam. It is here that the iron reacts with the
dissociated steam to form hydrogen and iron oxide, as follows:
4H20 + 3Fe - >• Fe304 + 4H2
The iron oxide is recycled to the top stage of the reactor and the H2 is
removed from the top of the lower stage, which also has two sections for greater
efficiency.
At the present time, char residues are discharged, slurried, cooled, and
separated out in a settling pond. The H2 and off-gases are being thermally
oxidized.
223
-------
51-Ufs.K.Y
H.P. H.fi
/"/eoCES-S ^
A'n.O
. erf*.
ro
ro
R£.PUC;MG GAS PR.ODUCT/OU
PILOT
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CH,,
C2H
N2 6
H20
CO
Coke/Char
Ash
H2S
S
Iron Solids
Total
Press. „ pslg
Temp. , °F
Char
Slurry
A
10758
.
-
-
-
_
6992
-
2918
788
-
60
~
10758
1200
73
Preheater
Feed
A
10758
-
-
-
-
.
6992
-
2918
788
-
60
~
10758
1070
600
Preheat
Off-Gas
<§>
10114
10
695
-
-
1717
7498
134
31
8
20
1
~
10114
1020
852
Ash
^
1061
-
-
-
-
-
10
-
279
752
-
20
~
1061
1070
1400
Producer
Gas
A
12815
170
1144
86
-
6341
582
4342
101
27
20
2
~
12815
1030
2000
Ash
Flume
<&
2065
-
-
-
-
_
1014
-
279
752
-
20
-
2065
1070
807
Slurry to
Flash
Tank
A
14666
-
-
-
-
_
13615
-
279
752
-
20
-
14666
1070
200
Flash
Tank
Off-5as
A
199
7
58
1
-
95
14
23
-
-
1
-
-
199
25
144
Flash
Tank
Slurry
^
38206
<0.02
4
-
-
Trace
36956
1
410
788
<0.4
23
24
38206
25
144
'roducer
Quench
Bleed
A
10252
3
54
-
-
73
10000
21
66
18
<0.1
1
15
10252
1000
114
Preheat
Quench
Bleed
V
8427
<0'.3
8
-
-
22
8355
2
31
8
<0.3
1
-
8427
1000
110
-------
ro
rv>
on
FM
*• . y
" (f*i~£ & J
„ i
,L
f
<^
1
70 //vc
SLUG:
A>H
iY COL
f. H
7-0 w r.
op 1974-
MATERIAL BALANCE
Stream Ident.
Stream No.
Rate, Ibs/hr
Analysis
H2
C02
CHH
02
N2 6
H20
CO
Light Oil
Middle Oil
Coke/Char
Ash
H2S
S
Iron Solids
Total
Press. , pslg
Temp. , °F
Preheat
Off-Gas
<£>
ion 4
10
695
-
-
1717
7498
134
-
-
31
8
20
1
10114
1020
852
Producer
Gas
A
12815
170
1144
86
"
6341
582
4342
-
-
101
27
20
2
12815
1030
2000
Producer
Quench
Tower
Bleed
A
10252
3
54
1
-
73
10000
21
-
-
66
18
<0. 1
1
15
10252
1000
114
Preheat
Quench
Tower
Bleed
8427
<0.3
0
-
-
22
8355
2
-
-
31
8
<0.3
1
8427
1000
110
Hydrogen
from
S-l
Reactor
^
3962
284
-
-
-
63
3543
-
-
-
36
10
17
-
9
3962
1050
1460
Product
Quench
Off-Gas
A
5982
280
-
-
-
63
5623
-
-
-
--
-
16
-
5982
1040
597
Product
Quench
Bleed
0
4
-
-
-
<0 1
5000'
-
-
-
36
10
<0. 1
r
9
5060
1040
105
Lift Line
Dense
Phase
A
186012
-
-
-
-
_
-
-
-
-
-
-
1838
-
184174
186012
1075
1440
Cooled
Preheat
Off-Gas
A
10911
10
607
-
-
1696
8365
133
-
-
-
-
20
-
10911
1000
593
Quenched
Product
and
Producer
Gas
A
28912
343
5029
85
-
6422
15199
1814
-
-
-
-
20
-
28912
1000
595
Product
Gases
3
236
-
-
-
53
4760
-
-
-
-
-
14
-
5063
1040
597
Low
Pressure
Off-Gas
A
28910
343
5029
85
~
6422
15197
1814
-
'
-
-
20
-
28910
25
540
Upper
Reducer
Spent
Gas
w
16421
117
5464
92
-
6924
1761
1972
-
-
66
18
6
1
16421
1000
1400
Lift Line
Dilute
Phase
A
202433
117
5464
92
~
6924
3600
1972
-
-
66
18
6
1
184173
202433
1000
1400
Iron
Solids
Recycle
A
185424
8
381
6
_
482
251
137
-
-
-
-
<0.8
-
184159
185424
1000
1400
-------
GLOSSARY
ACGIH
ABRADE
ABSORPTION
ACID GAS
ACTIVATED CARBON
ACUTE
ADA
ADENOMA
ADSORPTION
AEROSOL
AGA
AGGLOMERATE
ALIPHATIC
AMBIENT
American Conference of Governmental Industrial
Hygienists.
To rub or wear away, especially by friction.
The dissolution of a gas in a liquid.
Hydrogen sulfide (H2S) and carbon dioxide (C02).
Carbon obtained by carbonization in the absence of
air, preferably in a vacuum; has the property of
absorbing large quantities of gases, solvent vapors;
used also for clarifying liquids.
Having a sudden onset, sharp rise, and short course;
demanding urgent attention.
Anthraquinone disulfide acid.
A neoplasm of glandular epithelium.
The physical and chemical adherence of a gas to the
surface of a solid.
A suspension (in a body of gas) of liquid or solid
particles of such size that they tend to remain sus-
pended for an indefinite period.
American Gas Association.
Assemblage of particles rigidly joined together, as by
partial fusion (sintering).
One of the major groups of organic compounds charac-
terized by straight-chain or branched arrangement of
the constituent carbon atmos. [Aliphatic hydrocarbons
include three subgroups: (1) paraffins (alkanes),
which are saturated and unreactive; (2) olefins (alkenes
or alkadienes), which are unsaturated and quite reactive;
and (3) acetylenes (alkynes), which contain a triple
bond and are highly reactive.]
An encompassing atmosphere: environment.
226
-------
AMINE
AROMATIC (ARENE)
AROMATIC HYDROCARBON
ASH
BAFFLE
BaP
BATCH
BENCH PLANT STAGE
BIOASSAY
BITUMEN
BITUMINOUS COAL
BSFTPM
BOILING FLUIDIZED BED
Any of various basic compounds derived from ammonia by
replacement of hydrogen by one or more univalent
hydrocarbon radicals.
A major group of unsaturated cyclic hydrocarbons con-
taining one or more rings (e.g., benzene). (These
highly reactive and chemically versatile compounds
have a strong, but not unpleasant, odor--thus the name
"aromatic.")
An unsaturated cyclic hydrocarbon containing one or
more six-carbon rings.
Theoretically, the inorganic salts contained in coal;
practically, the residue from the combustion of dried
coal that has been burned at 1,380°F for an extended
period of time.
A device to deflect, check, or regulate flow.
Benzo[a]pyrene.
The quantity produced at one operation without adding
more feed.
A small-scale laboratory unit for testing process con-
cepts and operating parameters as a first step in the
evaluation of a process.
An assay method using a change in biological activity
as a qualitative or quantitative means of analyzing a
material's response to biological treatment; a method
of determining toxic effects of industrial wastes and
other wastewaters by using viable organisms as test
organisms.
A general name for various solid and semisolid hydro-
carbons; a native substance of dark color that is com-
paratively hard and nonvolatile and is composed prin-
cipally of hydrocarbon.
A broad class of coals containing 46 to 86 percent
fixed carbon and 20 to 40 percent volatile matter.
Benzene-soluble fraction of total particulate matter.
Also referred to as "benzene solubles."
A fluidized bed through which part of the fluidizing
medium passes in the form of bubbles of a size approx-
imately equal to the size of the solid particles, but
very small relative to the dimensions of the contain-
ing vessel.
227
-------
Btu
BTX
BY-PRODUCTS
(RESIDUALS)
CAGE MILL
CAKING
CANCER
CARBON STEAM REACTION
CARBON TRAP
ACTIVATED
CARBOXYHEMOGLOBINEMIA
CARCINOGEN
CARCINOMA
CARCINOMA IN SITU
CATALYST
British thermal unit, the quantity of energy required
to raise the temperature of one pound of water one
degree Fahrenheit.
Benzene, toluene, xylene; aromatic hydrocarbons.
Secondary products (possibly of commercial value) that
are obtained from the processing of raw material.
(By-products may be the residues of the gas production
process [such as coke, tar, and ammonia] or they may
be the result of further processing of such residues
[such as ammonium sulfate].)
A common name for a Stedman Disintegrator. Mill con-
sists of a number of parallel bars equally spaced
around the circumference. Sizing is accomplished by
the opening between bars.
The softening and agglomeration of coal as a result of
the application of heat.
A malignant and invasive growth or tumor, especially
one originating in epithelium.
Water gas reaction whereby the passage of steam over
carbon results in the formation of carbon monoxide and
hydrogen.
A trap filled with activated carbon to prevent the
passage of toxic gas.
The presence of carboxyhemoglobin (a compound formed
from hemaglobin on exposure to carbon monoxide) in the
blood.
A substance or agent that produces or incites cancer-
ous growth.
An epithelial cell, new growth, or malignant tumor
that is enclosed in connective tissue and tends to
infiltrate and give rise to metastases.
A carcinoma that is confined to the site of origin,
does not invade neighboring tissue.
In a chemical reaction, an extra substance that is
usually used to speed up the reaction to produce the
desired result. (The catalyst usually does not appear
in the reaction product in any appreciable amount and
therefore is not used up, as are the main ingredients
in the reaction; the catalyst may have to be periodi-
cally discarded because of contamination.)
228
-------
CAVITATION
CHAR
CHRONIC
"CLOSED" SYSTEM
COAL
COAL GAS
COAL GASIFICATION
COAL GASIFICATION
(HIGH-Btu GAS)
COAL LIQUEFACTION
(COAL HYDROGENATION)
COAL OIL
COAL SLURRY
COAL TAR
COALIFICATION
COKE
COKE OVEN GAS
The pitting and wearing away of solid surfaces (as of
metal) as a result of the collapse of these vacuums in
the surrounding liquid.
The solid residue remaining after the removal of mois-
ture and volatile matter from coal.
Marked by long duration or frequent recurrence.
Any collection of matter within prescribed boundaries,
which does not cross the boundaries.
A natural solid material consisting of amorphous ele-
mental carbon with various amounts of organic and
inorganic compounds.
The gas that comes from retorts, mufflers, or ovens
during the distillation of coal. (Coal gas has a high
illuminating value and is a relatively suitable engine
fuel. Large quantities of coal gas are produced when
coal is used to make coke, coal tar, benzoil, toluene,
ammonia, and other products.)
The conversion of coal to a gas suitable for use as a
fuel (HYGAS, C02 Acceptor, Bi-Gas, methanation, Lurgi
ATGAS processes).
The combustion of coal at high temperatures (+1000°F)
in an atmosphere deficient in oxygen (reducing) to
produce a combustible gas.
The conversion of coal into liquid hydrocarbons and
related compounds by hydrogenation.
Oil obtained by the destructive distillation of bitu-
minous coal; also an archaic term for kerosene made
from petroleum.
Pulverized coal suspended in a liquid.
A gummy, black substance produced as a by-product of
distillation of bituminous coal.
Metamorphosis of vegetable debris into coal.
Strong porous residue consisting of carbon and mineral
ash formed when bituminous coal is heated in a limited
air supply or in the absence of air. Coke may also be
formed by thermal decomposition of petroleum residues.
The gas secured from coke ovens during the production
of coke. (The properties of this gas are identical to
those of coal gas, and the two products are inter-
229
-------
CONDENSATE
CRACKING
CYCLONE
CYTOLOGY
DEGRADATION
DEHYDROGENATION
DISPERSION
DISTILLATION
DOLOMITE
DOWTHERM
DRY GAS
DUST
EDEMA
changeable. Coke is particularly useful in making
iron and steel and as an industrial fuel.)
Liquid hydrocarbon obtained by the combustion of a
vapor or gas produced from oil or gas wells and ordi-
narily separated at a field separator and run as crude
oil.
The partial decomposition of high-molecular-weight
organic compounds into lower-molecular-weight com-
pounds, generally as a result of high temperatures.
A separator that depends upon centrifugal force to
separate particles or droplets from the stream (used
to separate solids from gases and water from steam).
Branch of biology concerned with the study of cells as
vital units with reference to their structure, func-
tion, multiplication, pathology, and life history.
A type of decomposition characteristic of high-
molecular-weight substances such as proteins, polymers,
and branched-chain sulfonates, resulting from oxida-
tion, heat, solvents, and bacterial action.
The process by which hydrogen is
from compounds.
removed chemically
A suspension of particles in a medium; the opposite of
flocculation; a scattering process.
A process of vaporizing a liquid and condensing the
vapor by cooling; used for separating liquids into
various fractions according to their boiling points or
boiling ranges.
A mineral having the chemical formula CaMg (C03)2,
i.e., a carbonate of calcium and magnesium.
Trademark for a series of eutectic mixtures of di-
phenyl oxide and diphenyl used as high-temperature
heat-transfer fluids.
A gas that does not contain the heavier fractions,
which may not easily condense under normal atmospheric
conditions (e.g., methane and ethane).
A general term used to describe solid particles that
are in the micron-size range (e.g., fly ash, coarse
dirt, and mechanically produced particles.
The presence of abnormally large amounts of fluid in
the intercellular tissue spaces of the body.
230
-------
EFFLUENT
ELECTROLYTE
ELUTRIATION
EMULSION
ENDOTHERMIC
ENTRAIN
ENTRAINED BED (FLOW)
EPIDEMIOLOGY
EXOTHERMIC
FILTER CAKE
FINES
FIRST GENERATION
FIXED BED
FLOTATION
A discharge of pollutants into the environment, par-
tially or completely treated or in its natural state
(generally used in regard to discharges into waters).
A substance that when dissolved in a suitable solvent
or when fused becomes an ionic conductor.
The preferential removal of the small constituents of
a mixture of solid particles by a stream of high-
velocity gas.
A stable mixture of two or more immiscible liquids
held in suspension by small percentages of substances
called emulsifiers. [These are of two types: (1) pro-
teins or carbohydrate polymers and (2) long-chain
alcohols and fatty acids.]
A chemical reaction that absorbs heat.
To draw in and transport (as solid particles or gas)
by the flow of a fluid.
A bed in which solid particles are suspended in a
moving fluid and are continuously carried over in the
effluent stream.
The study of diseases as they affect populations.
A reaction in which heat is liberated.
The moist residue remaining from the filtration of a
slurry to produce a clean filtrate.
In general, the smallest particle of coal or mineral
in any classification, process, or sample of material;
especially those that are elutriated from the main
body of material in the process.
The first attempt at the development of an object or
process.
A bed in which the individual particles or granules of
a solid are motionless and supported by contact with
each other (in contrast with moving bed).
A process for separating minerals from waste rock or
solids of different kinds by agitating the pulverized
mixture of solids with water, oil, and special chemi-
cals, which causes preferential wetting of solid par-
ticles of certain types by the oil. (The unwetted
particles are carried to the surface by the air bub-
bles and thus are separated from the wetted particles.)
A frothing agent is also used to stabilize the bubbles
231
-------
FLUE GAS, STACK GAS
FLUIDIZATION (DENSE
PHASE)
FLUIDIZATION
(ENTRAINED)
FLUIDIZED BED
FROTHING
ft/sec (fps)
FUEL
9
yg
GAS CHROMATOGRAPHY
GASES
in the form of a froth, which can easily be separated
from the body of the liquid (froth flotation).
Synonymous terms for the gases resulting from combus-
tion of a fuel.
The turbulent motion of solid particles in a fluid
stream; the particles are close enough to interact and
give the appearance of a boiling liquid.
Solid particles transported by a high-velocity fluid
stream with little or no solid interaction.
A bed of suitably sized solid particles through which
a fluid (usually a gas) flows at a velocity high enough
to buoy the particles, to overcome the influence of
gravity, and to impart to them an appearance of great
turbulence.
Vapor escaping from rapidly boiling liquid carries
liquid with it causing bubbles to form, which impedes
the reaction taking place.
Feet per second.
A substance used to produce heat energy, chemical
energy by combustion, or nuclear energy by nuclear
fission.
Gram.
Microgram.
(GC; gas-liquid chromatography, GLC; vapor-phase
chromatography, VPC). The process in which the com-
ponents of a mixture are separated from one another by
volatilizing the sample into a carrier gas stream that
is passing through and over a bed of packing consist-
ing of a 20- to 200-mesh solid support. The surface
of the latter is usually coated with a relatively non-
volatile liquid (the stationary phase). This gives
rise to the term gas-liquid chromatograph. If the
liquid is not present, the process is gas-solid chro-
matography which is also widely useful for analysis.
Different components move through the bed of packing
at different rates, and so appear one after another at
the effluent end where they are detected and measured
by thermal conductivity changes, density differences,
or ionization detectors.
Materials that can be condensed to liquids only by
pressure or at temperatures below ambient (such as
oxygen, methane, hydrogen).
232
-------
GAS LIQUOR
(SOUR WATER)
GASIFICATION
GASWORKS
GRAB SAMPLE
HEAT RESERVOIR
(SINK)
HETEROCYCLIC
HIGH-Btu GAS
HYDROCARBON
HYDROCRACKING
The aqueous streams condensed from the coal conversion
and processing areas by scrubbing and cooling of the
crude gas stream.
In the most commonly used sense, refers to the conver-
sion of coal to the high-Btu synthetic natural gas
under conditions of high temperatures and pressures;
in a more general sense, conversion of coal into a
usable gas.
Plants built during the 19th and early 20th centuries
to produce gas. Coal was generally burned in reducing
atmosphere with steam to form a low-Btu gas. The hot
gas was passed through a brick checkerwork at atmos-
pheric pressure to heat the brick. When the brick was
hot, the gas was switched to a second checkerwork and
oil was sprayed into the first. The gas produced from
the two thermally cracked oil was added to the coal
gas to form a medium (500-Btu) town gas.
Obtaining a sample of an atmosphere in a very short
period of time, so that this sampling time is insig-
nificant in comparison with the duration of the opera-
tion or the period being studied.
Anything that absorbs heat, usually part of the envi-
ronment (such as the air, a river, or outer space).
A cyclic or ring structure in which one or more of the
atoms in the ring is an element other than carbon.
Fuel gas having a higher heating value of about 1000
Btu/scf or more.
An organic compound consisting exclusively of the ele-
ments carbon and hydrogen. The principal types are
aliphatic (straight-chain) and cyclic (closed ring).
Aliphatic hydrocarbons include paraffins (alkanes),
olefins (alkenes and alkadienes), acetylenes, and
acyclic terpenes. Cyclic hydrocarbons include ali-
cyclics (cycloparaffins, cycloolefins, cycloacety-
lenes); aromatics (benzene group [ring], naphthalene
group [2 rings], anthracene group [3 rings]); and
cyclic terpenes (monocyclic [dipentene], dicyclic
[pinene]).
An oil-refining process in which the large molecules
of crude oil are broken into smaller molecules through
reaction with hydrogen. (The process is used to con-
vert heavy oil into lighter fractions such as gaso-
line.)
233
-------
HYDROGASIFICATION
HYDROGENATION
IN SITU
INERT GAS
INORGANIC
LEACHING
LIGHT GASOLINE,
LIGHT NAPHTHA
LIGNITE
LIQUEFACTION
LOW-Btu GAS
LOCKHOPPER
MAKE GAS/OIL/TAR
METHANATION
MICRON
MORBIDITY
MORTALITY
Gasification that involves the direct reaction of
fuels with hydrogen to optimize formation of methane.
Chemical reactions involving the addition of gaseous
hydrogen to a substance under high temperatures and
pressures.
In its original place, e.g., underground gasification
of a coal seam.
A gas that does not react with other substances under
ordinary conditions.
Being or composed of matter other than plant or ani-
mal .
The process of extracting a soluble component from a
mixture by percolation of the mixture with a solvent,
usually water, resulting in the solution and later
separation of the soluble component.
Liquid C5, C6> C7, C8 derived from crude oil (about
the same as condensate from raw natural gas).
Brownish-black coal containing 65 to 72 percent carbon
on a mineral-matter-free basis, with a rank between
peat and sub-bituminous coal.
Conversion of a solid to a liquid; with coal, this
appears to involve the thermal fracture of carbon-
carbon and carbon-oxygen bonds, forming free radicals.
The radicals abstract hydrogen atoms yielding low-
molecular-weight gases and condensed aromatic liquids.
A gas having a heating value of up to 350 Btu per
standard cubic foot.
A mechanical device that permits the introduction of
a solid into an environment of different pressure.
(Defined in text) Product gas--gas resulting from the
gasification process.
The catalytic combination of carbon monoxide and hy-
drogen to produce methane and by-product water.
(About 60% of the end-product methane is produced in
the methanation step.)
A unit of length equal to one millionth of a meter.
The relative incidence of disease.
The number of deaths in a given time and place; the
proportion of deaths to population.
234
-------
MOVING BED
NARCOSIS
NEOPLASM
OIL, GAS
ON-STREAM OPERATING
TIME
ORGANIC
OXIDATION
PARTICULATE
FLUIDIZED BED
PARTICULATES
PEAT
pH
PHOTOSENSITIZE
PILOT PLANT
A body of solids in which the particles or granules of
a solid remain in mutual contact, but in which the
entire bed moves in piston-like fashion with respect
to the containing walls (in contrast with fixed bed).
A reversible condition characterized by stupor or
insensibility.
A new and abnormal formation of tissue, as a tumor or
growth that serves no useful function but grows at the
expense of the healthy organism.
An oil intermediate between the light distillates and
the lubricating oils. (Most of the gas oil produced
is turned over to the cracking apparatus for the pro-
duction of gasoline and is used by gas companies for
the manufacture of gas.)
The time during which the entire pilot plant is actu-
ally working at preset conditions, as opposed to the
time in which it is shut down for repairs, is starting
up, etc.
Of, relating to, or containing carbon compounds.
Originally meant a reaction in which oxygen combines
chemically with another substance, but term now in-
cludes any reaction in which electrons are transferred.
A bed in such a condition of fluidization that the
individual particles are discretely separated from
each other and the volumetric concentration of solid
particles is uniform throughout the bed.
Small particles of solid material produced by the
burning of fuels.
One of the earliest stages of coal in which the re-
mains of plants and ferns that have been preserved may
be clearly seen. (Peat contains a very high percent-
age of water and has been used as a fuel for hundreds
of years in Ireland, England, and Germany.)
A measure of the acidity or alkalinity of a material,
liquid or solid. (pH is represented on a scale of 0
to 14, with 7 representing a neutral state, 0 repre-
senting the most acid, and 14 the most alkaline.)
To make sensitive to the
and especially light.
influence of radiant energy
A small-scale industrial process unit operated to test
the application of a chemical or other manufacturing
235
-------
PIPELINE GAS
PITCH OF TAR
PNEUMOCONIOSIS
POISONING OF A
CATALYST
POLYMERIZATION
POLYNUCLEAR
ppm
PROCESS POND WATER
PROCESS STREAM
PRODUCT STREAM
psi
Psig
PULMONARY
PYROLYSIS
process under conditions that will yield information
useful in design and operation of full-scale manufac-
turing equipment.
A methane-rich gas that conforms to certain standards
and has a higher heating value between 950 and 1,050
Btu per standard cubic foot.
A black or dark brown solid or semisolid residue ob-
tained by partial evaporation or fractional distilla-
tion of tars and tar products.
A chronic fibrous reaction in the lungs to the inhala-
tion of dust.
The deactivation of a catalyst by the addition of
another substance, leaching of active metals, or
destruction of crystal structure.
The reverse of cracking; a method of combining smaller
molecules to make larger ones. (Polymerization was
developed during the late 1930's to utilize refinery
gases, which were often wasted or burned as fuel. The
product of polymerization is usually "poly" gasoline;
these fractions are high in antiknock value and are
used primarily to raise the antiknock value of the
finished gasoline.)
Chemically polycyclic especially with respect to the
benzene ring, used chiefly of aromatic hydrocarbons
that are important as pollutants and possibly as
carcinogens.
Parts of a substance per million parts of gas (air).
Wastewater stored in the pond that was used in some
way during the gasification process.
Any material stream within the coal conversion pro-
cessing area.
Streams within the coal conversion plant that contain
the material which the plant was built to produce
(e.g., oil, SNG, SRC).
Pounds per square inch.
Pounds per square inch, gauge.
Pertaining to the lungs.
Thermal decomposition of organic compounds in the
absence of oxygen.
236
-------
QUENCHING
RANK
RAW GAS
REACTIVE CHAR
REACTOR
REAL TIME
REDUCING ATMOSPHERE
REFRACTORY
RESIDENCE TIME
RUN
SARCOMA
scf
SCRUBBER
SECOND OPERATION
SENSIBLE HEAT
SHIFT CONVERSION
Cooling by immersion in oil, water bath, or water
spray.
Those differences in the pure coal material due to
geological processes designated as metamorphic, where-
by the coal material changes from peat through lignite
and bituminous coal to anthracite or even to graphite;
the degree of coal metamorphism.
Impure gas produced in a gasifier.
Char that is capable of spontaneously catching on fire
while in strategic piles.
Vessel in which coal-conversion reactions take place.
The actual time in which an event takes place with the
reporting on or recording of the event practically
simultaneous with its occurrence.
At atmosphere that lowers the state of oxidation of
chemicals within it.
A material capable of withstanding extremely high
temperatures and having a relatively low thermal con-
ductivity.
The period of time during which a substance resides in
a designated area.
The period during which a machine or plant is in con-
tinuous operation; the use of machinery for a single
set of processing procedures.
Cancer arising from underlying tissue, muscle, bone,
and other connective tissue that may affect the bones,
bladder, kidneys, liver, lung, parotids, and spleen.
Standard cubic foot.
Apparatus in which a gas stream is freed of tar,
ammonia, and hydrogen sulfide.
A type or class of objects or processes developed and
improved from earlier objects or processes.
That heat that results in only the elevation of the
temperature of a substance with no phase changes.
Process for the production of gas with a desired car-
bon monoxide content from crude gases derived from
coal gasification; carbon-monoxide-rich gas is satu-
rated with steam and passed through a catalytic
237
-------
SINTERING
SLUDGE
SLURRY
SMOG
SMOKE
SOOT
SOUR GAS
SOUR WATER
STEADY STATE
SUB-BITUMINOUS COAL
SWEET GAS
SYNERGISM
SYNGAS
SYNTHETIC NATURAL GAS
(SNG)
reactor where the carbon monoxide reacts with steam to
produce hydrogen and carbon dioxide, the latter being
subsequently removed in a scrubber employing a suit-
able sorbent.
The agglomeration of solids at temperatures below
their melting point, usually as a consequence of heat
and pressure.
A soft mud, slush, or mire; e.g., the solid product of
a filtration process before drying.
A suspension of pulverized solid in a liquid.
Term used broadly to mean polluted air. (There are
various types of smog which are produced from certain
classes of pollutants under specific meteorologic con-
ditions, Photochemical smog results from photochemi-
cal reactions involving hydrocarbons and nitrogen
oxides.)
Solid and/or liquid particles formed by the incomplete
combustion of fuels and discharged suspended in the
gaseous combustion products.
Agglomeration of tar-impregnated carbon particles that
form when carbonaceous material does not undergo com-
plete combustion.
A gas containing hydrogen sulfide.
See gas liquor.
A state or condition of a system or process that does
not change in time.
Coal of intermediate rank (between lignite and bitumi-
nous); weathering and nonagglomerating coal having
calorific values in the range of 8,300 to 13,000 Btu,
calculated on a moist, mineral-matter-free basis.
Gas with H2S removed.
The harmonious action of two agents (e.g., drugs) or
organs (e.g., muscles) producing an effect neither
could produce alone, or an effect that is greater than
the total effect of each agent operating by itself.
Synthetic gas (SNG).
Substitute natural gas; a manufactured gaseous fuel
generally produced from naphtha or coal that contains
95% to 98% methane and has an energy content of 980 to
1,035 Btu/scf (about the same as that of natural gas).
238
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TAR (COAL)
TAR FOG
THERMOCYNAMICS,
LAWS OF
THRESHOLD LIMIT VALUE
TLC
TOXICANT
TRACE ELEMENTS
VAPOR
VARIABLE FUEL
VENTING
VENTURI SCRUBBER
VOLATILITY
WASHOUT
A dark brown or black, viscous, combustible liquid
formed by the destructive distillation of coal.
Submicron aerosol of condensed tar particles.
The first law of thermodynamics states that energy can
neither be created nor destroyed. The second law of
thermodynamics states that when a free exchange of
heat takes place between two bodies, the heat is al-
ways transferred from the warmer to the cooler body.
Refers to airborne concentrations of substances and
represents conditions under which it is believed that
nearly all workers may be repeatedly exposed for an 8-
hour day, 5 days a week (expressed as parts per mil-
lion [ppm] for gases and vapors, and as milligrams per
cubic meter [mg/m3] for fumes, mists, and dusts).
Thin-layer chromatography.
A substance that kills or injures an organism through
chemical or physical action or by altering the organ-
ism's environment; for example, cyanides, phenols,
pesticides, or heavy metals, especially used for in-
sect control.
Elements found in small quantities or traces, usually
because of their insolubility.
The gaseous form of a substance that is normally in
the solid or liquid state at ambient conditions and
which can be changed to the solid or liquid state by
increasing the pressure and/or decreasing the tempera-
ture.
A fuel substance that can be used in more than one
form (e.g., solid, liquid, gas).
Release of gases or vapors under pressure to the
mn<;nhprp
at-
mosphere.
A gas-cleaning device that involves the injection of
water into a stream of dust-laden gas flowing at a
high velocity through a contracted portion of a duct,
thus transferring the dust particles to the water
droplets, which are subsequently removed.
That property of a liquid that denotes its tendency to
vaporize.
The removal of a pollutant by precipitation.
239
>US GOVERNMENT PRIMING OFFICE 1*78— 7 5 7 - 1 4 ) /t, 7 7 -4
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