U.S. Environmental Protection Agency Industrial Environmental Research EPA~600/7~77~045
Office of Research and Development Laboratory _ - - 07-7
Research Triangle Park. North Carolina 27711 May I 977
IN-SITU COAL GASIFICATION:
STATUS OF TECHNOLOGY
AND ENVIRONMENTAL IMPACT
Interagency
Energy-Environment
Research and Development
Program Report
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S.
Environmental Protection Agency, have been grouped into seven series.
These seven broad categories were established to facilitate further
development and application of environmental technology. Elimination
of traditional grouping was consciously planned to foster technology
transfer and a maximum interface in related fields. The seven 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
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-agehcy Federal Energy/Environment
Research and Development Program. These studies relate to EPA's
mission to protect the public health and welfare from adverse effects
of pollutants associated with energy systems. The goal of the Program
is to assure the rapid development of domestic energy supplies in an
environmentally—compatible manner by providing the necessary
environmental data and control technology. Investigations include
analyses 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 environmental issues.
REVIEW NOTICE
This report has been reviewed by the participating Federal
Agencies, and approved for publication. Approval does not
signify that the contents necessarily reflect the views and
policies of the Government, nor does mention of trade names
or commercial products constitute endorsement or recommen-
dation for use.
This document is available to the public through the National Technical
Information Service, Springfield, Virginia 22161.
-------
EPA-600/7-77-045
May 1977
IN-SITU COAL GASIFICATION:
STATUS OF TECHNOLOGY
AND ENVIRONMENTAL IMPACT
by
9
Nancy P. Phillips and Charles A. Muela
Radian Corporation
P.O. Box 9948
Austin, Texas 78766
Contract No. 68-02-2147, Exhibit A
Program Element No. EHE623A
EPA Project Officer: William J. Rhodes
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, N.C. 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, D.C. 20460
-------
ABSTRACT
A brief overview of the current status of U.S. and
foreign in-situ coal gasification technology is presented in
this report. In addition to summaries of specific U.S. in-
situ projects, general discussions of the chemistry, technical
problems and environmental considerations associated with in-
situ technology are given.
In-situ gasification is being applied on a commercial
scale today only in the U.S.S.R.; however, there are several
other foreign countries, e.g., Great Britain, in which pilot-
scale projects are underway." Field experiments are also being
conducted in the United States. One such upcoming test, Hanna V,
is designed to produce up to 90 MM scfd of low-Btu gas.
There are numerous unresolved technical problems asso-
ciated with underground coal gasification (UCG). The primary
problem in the pregasification phase has been achievement of a
continuous linkage between injection and production wells. In
the gasification phase the major problems have been associated
with maintaining control over the process and producing a pro-
duct gas of uniform quality. Some recent progress has been
reported in these areas, however,
Associated with these technical problems are the poten-
tial environmental impacts of in-situ gasification which include
groundwater contamination and air emissions from ground leaks.
Environmental impacts from UCG gas purification and pollution
control operations will be similar to the impacts assoicated
with those operations in above-ground gasification facilities.
111
-------
CONTENTS
Page
Abstract iii
Figures viii
Tables x
1. 0 INTRODUCTION 1
2.0 OVERVIEW OF IN-SITU COAL GASIFICATION
TECHNOLOGY 4
2.1 General Description of UCG Technology 4
2.1.1 Chemistry of In-Situ Coal
Gasification 4
2.1.2 Fundamental UCG Operations......... 5
s>
2.1.3 Unresolved Technical Problems...... 10
2 .2 Current UCG Proj ects . 12
3.0 SUMMARY OF ENVIRONMENTAL IMPACTS OF UCG 22
3 .1 Water Quality 22
3. 2 Air Quality 27
3.3 Subsidence 28
3.4 Effects of Hazardous By-products or Wastes 29
4.0 COMPARISON OF IN-SITU GASIFICATION WITH
ABOVE-GROUND MINING AND GASIFICATION 30
4.1 Resource Recovery Efficiency 30
4. 2 Energy and Water Usage 31
4.3 Technological Development Status 36
4.4 Economics . 37
-------
Appendix
CONTENTS (Continued)
4. 5 Land Usage and Impact 38
4.6 Water Pollution Potential.„ 41
4. 7 Air Pollution Potential 41
4. 8 Health and Safety Aspects 42
A ERDA'S LINKED VERTICAL WELL PROCESS AT
HANNA, WYOMING 44
LVW Process Description 44
Hanna Test Site 45
Test Program - Status and Results 50
Water Quality Studies 65
Air Quality Studies at Hanna 72
B ERDA/LLL IN-SITU COAL GASIFICATION PROGRAM 81
LLL Process Description 83
Scope of Work and Project Status 89
C MORGANTOWN ENERGY RESEARCH CENTER 112
Scope of Work and Status 113
D TUSI IN-SITU LIGNITE GASIFICATION PROJECT 118
Process Description 120
Project Status and Scope 122
E UNIVERSITY OF ALABAMA - FEASIBILITY STUDY OF
IN-SITU COAL GASIFICATION IN THE WARRIOR COAL
FIELD 134
Process Features 136
Project Status and Results 136
VI
-------
CONTENTS (Continued)
F RANN DIVISION (NATIONAL SCIENCE FOUNDATION)/
UNIVERSITY OF TEXAS - IN-SITU CONVERSION OF
TEXAS LIGNITE TO SYNTHETIC GAS 156
Scope of Work 158
Experimental Configuration 158
Project Status and Results 159
G OTHER U.S. IN-SITU GASIFICATION PROJECTS.. . 160
Los Alamos Scientific Laboratory. 161
Texas A & M University 161
Sandia Laboratories 162
Argonne National Laboratory. 162
West Virginia University....................... 162
Project Thunderbird............................. 162
A. D. Little Study.............................. 162
H UCG PROJECTS OUTSIDE THE U.S................... 163
BIBLIOGRAPHY 166
VI1
-------
FIGURES
Number Page
2-1 U.S. Patent on In-Situ Gasification of Coal
Utilizing Non-Hypersensitive Explosives 9
4-1 Energy Return Ratio from Underground Coal
Gasification Experiment, Hanna 1 35
4-2 Energy Recovery Efficiency from Underground
Coal Gasification Experiment, Hanna 1 37
A-l Diagram of Linked Vertical Well Concept of UCG.. 46
A-2 Location Map of LERC Underground Coal
Gasification Experiment Site 47
A-3 Sequence of Linkage in the Hanna #1 Experiment.. 51
A-4 Well Pattern; Phase 1 of the Hanna II
Experiment 55
A-5 Well Pattern for Hanna II, Phases II and III.... 58
A-6 Hanna III Well Pattern 63
B-l LLL In-Situ Coal Gasification Concept 84
B-2 Block Diagram of LLL In-Situ Coal Gasification
Process 85
B-3 Sorption Isotherm for Soluble Organic Components
from Coal Tar on Subbituminous Coal 94
B-4 Sorption Isotherm for Ca Ions on Subbituminous
Coal 95
B-5 Location of Hoe Creek Test Site 103
B-6 Stratigraphic View of Hoe Creek Site 104
B-7 Schematic Diagram of Hoe Creek Experiment No. 1. 109
B-8 Hoe Creek No. 2 Experiment - Five Spot Test HQ
VI11
-------
FIGURES (Continued)
C-l A Longwall Generator Development Scheme........ 116
C-2 Longwall Generator Concept (Application to
Power Generation Facility) 117
D-l Process Flow Diagram for In-Situ Gasification
Technological Test Site........................ 121
D-2 TUSI In-Situ Lignite Gasification Project -
Stratig'raphic Cross Section of Test Area. ...... 124
D-3 Monitor Well Locations at Technological Test
Drilling Site 125
E-l Location of the Experimental In-Situ
Gasification Study Area with Respect to the
Warrior Coal Field in Alabama 137
E-2 Lithology Present in In-Situ Gasification
Core Hole 1-A at Experimental Gasification Site 139
E-3 Gas Flow System for Laboratory Combustor
(University of Alabama) ......................... 141
E-4 Leaching Apparatus............................. 146
E-5 BOD Concentration Change with Time in the
Contacting Experiments 150
E-6 COD Concentration Change with Time in the
Contacting Runs 151
E-7 Organic Acids Concentration Change with Time
in the Contacting Runs 152
E-8 Phenols Concentration Change with Time in the
Contacting Runs 153
E-9 Chromium Concentration Change with Time in
the Contacting Runs 154
ix
-------
TABLES
Number Page
2-1 Summary of Ongoing UCG Research Projects 14
4-1 Comparison of UCG with Conventional Mining
Plus Surface Gasification 32
4-2 Effects of Underground Coal Gasification
Compared with Strip Mining Plus Surface
Gasification 39
A-l Chemical Composition of Subbituminous "A" Coal
Core Samples from Sites 1 and 2 of the Hanna
Coal Field, Hanna, Wyoming 49
A-2 Typical Composition of Dry Gas Produced in Under-
ground Coal Gasification Experiment, Hanna I... 53
A-3 Overall Average Composition of Product Gas
from Hanna II, Phase 1 56
*
A-4 Summary of Hanna II Results 57
A-5 Summary of Instrumentation Fielded for Phases
II and III of the Hanna II Underground Coal
Gasification Experiment 59
A-6 Typical Elemental Analysis of Coal Tar 67
A-7 Total Nitrogen, Total Sulfur and Titratable
Nitrogen for Acid, Base and Neutral Fractions
of UCG Coal Tar 68
A-8 Compositional Ranges of UCG Coal Tars 69
A-9 Composition of Aliphatics Fraction of Hanna I
Coal Tar Sample 70
A-10 Tabulated Spectra on Separated Components from
Tar Base Fraction of Hanna Carbonization Sample 71
A-11 Concentrations of Major Components in Wellhead
Particulates • 74
A-12 Composition of Wellhead Particulates 76
x
-------
TABLES (Continued)
A-13 Ammonia, Hydrogen Cyanide, Carbonyl Sulfide
and Carbon Bisulfide Concentrations in the
Production Gas
A-14 Vapor Phase Elemental Concentrations in UCG
Production Gas
A-15 Particulate Concentration and Distribution
in Flare Discharge Gas
A-16 Composition of Flare Discharge Gas
B-l Gas Compositions Expected from Hoe Creek
Experiments Nos. 1 (Air-Blown) and 2 (Oxygen-
Blown)
B-2 Analysis of Ash (As Constituent Oxide) from
Coal Typical of Hoe Creek Test Site
B-3 Results of Laboratory Inorganic Leaching
Studies ..................................
B-4 Summary of Input Parameters for Water Quality
0 Model Calculations............................
B-5 Summary of Input Data Used for Air Quality
Calculations
B-6 Source Strengths for Various Effluent Gases..
B-7 Summary of Hydraulic Characteristics of #2
Coal and Associated Strata - Hoe Creek Site..
B-8 Chemical Quality of Groundwater from Various
Strata - Hoe Creek Site 1
D-l Baseline Water Quality Standards for Texas
Lignite Gasification Project..............
D-2 Additional Baseline Quality Parameters of
Water in Geologic Units
D-3 Sampling Frequency for Gasification Period...
XI
-------
TABLES (Continued)
E-l Properties of Coal Used.
E-2 Experimental Parameters in Laboratory Leaching
Studies
E-3 Water Effluent Analysis Exponential Decay
Constants ...... ,
Xll
-------
SECTION 1.0
INTRODUCTION
The feasibility of in-situ gasification as an alter-
nate coal conversion route is currently being assessed. This
reaearch effort is being carried out by federal and private
organizations interested in determining its commercialization
potential. The process consists of several distinct stages:
Drilling conventional wells to the coal seam
Ignition and linkage between wells
Injection of air or oxygen and in some cases
steam to induce the gasification reactions
A gas of either low or intermediate heating value is produced
which, after cleanup, can potentially be utilized for electric
power generation, upgraded to pipeline-quality gas or used for
in-plant process requirements. The commercial feasibility of
in-situ coal gasification will ultimately depend on the recovery
efficiencies achievable and the economics. At this time these
efficiencies are not well defined, although encouraging indica-
tors are seen.
The concept of underground coal gasification (UCG) was
first suggested in 1868 by William Siemens. Other early research
was carried out by the Russian chemist, Mendeleev. In 1909 an
American, Anson Betts, received the first patent on this type of
process. Although small-scale experiments were conducted in
England prior to World War I, the highest levels of activity on
a large scale occurred in Russia beginning in 1933. After World
War II interest was revived in several European Countries includ-
ing England, France (Morocco), Belgium, Italy, Poland, and
-------
Czechoslovakia, and in Japan, Canada and the United States as
well. While the U.S.'s activities in this area died out primar-
ily because of an unfavorable economic outlook, research was
again initiated in the early 1970's under sponsorship by the
Bureau of Mines, ERDA, private industry and other research in-
stitutions (L-871, L-748).
At the present time UCG is in full-scale operation
in Russia and in pilot-scale stage in several other foreign
countries such as Great Britain. Field experimentation at a
less advanced level is in progress within the U.S., with one
plan calling for possible production rates up to 90 MM scfd
(Hanna V). The major test sites within the U.S. are:
• Hanna, WY (LERC)
Gillette, WY (ERDA, Lawrence Livermore Lab.)
Fairfield, TX (Texas Utilities Services, Inc.)
Pricetown, WV (MERC)
Adger, AL (University of Alabama)
Several other in-situ projects are also underway, although no
field work has been done so far. These studies are being con-
ducted by the University of Texas, Los Alamos Scientific Labora-
tory, Texas A&M University and Argonne National Laboratory. In
addition, instrumentation development and testing is being
carried out by Sandia Laboratories under ERDA sponsorship.
Underground coal gasification is considered a viable
approach to the production of low-Btu gas. As such, it falls
within the overall scope of the Environmental Assessment of Low-
Btu Gasification and its Utilization (EPA Contract No. 68-02-
2147, Exhibit A).
-2-
-------
This document presents an overview of in-situ coal
gasification technology and its potential environmental impacts.
A general description of the chemistry, technology and technologi-
cal problems involved is contained in Section 2.1, while the
remainder of Section 2 briefly summarizes ongoing UCG projects.
Detailed descriptions of the technical objectives, approaches and
results of each are included in the Appendix. Section 3 summa-
rizes the current state of knowledge regarding environmental
issues. A comparative discussion of the technological and
environmental aspects of UCG and conventional mining plus surface
gasification is the concluding chapter of this report.
-3-
-------
SECTION 2.0
OVERVIEW OF IN-SITU COAL GASIFICATION TECHNOLOGY
In this section a general discussion of UCG technology
and descriptions of ongoing research projects are presented.
2.1 GENERAL DESCRIPTION OF UCG TECHNOLOGY
Many facets of in-situ gasification are generally
applicable to all process variations. In this section the
chemistry and basic mechanisms of coal gasification, basic pro-
cess operational methods and unresolved technical problems are
summarized. Much of the material presented here is based on
project summary reports and other previously published literature
(L-683, L-871, L-1216, L-5480, L-2645). These documents should
be consulted for further details.
2.1.1 Chemistry of In-Situ Coal Gasification
In most in-situ processes two distinct phases are
usually involved: carbonization and gasification. In addition,
combustion supplies the heat required for both the carbonization
and gasification reactions. Air reacts exothermically with coal
and/or char producing C02 and H20 as combustion products. These
hot gases react with char to form product gas consisting mainly of
CO, H2, and CHi>. The combustion heat also promotes carbonization
(or devolatilization) of coal resulting in methane, char, H20 and
coal tar. The tars are subject to fractionation according to the
boiling points of the constituents as they move with the product
gas away from the reaction zone. Heavier components condense in
the coal seam while the lighter components remain with the product
gas (L-683, L-8580).
.4-
-------
Extensive laboratory-scale investigations of mechanisms,
reaction products and kinetics of individual reactions and coal
chemistry in general have been reported in the literature. The
following reactions summarize some of the important steps
involved in underground coal gasification (L-683):
Combustion Coal + 02 -*• H20 4- CO2
Hydrolysis Coal + H20 -> CIU + CO 4- higher
hydrocarbons
Carbonization Coal -»• C + CEn + H20
Bouduard (undesirable
side reaction) 2CO -> C + C02
Water gas reaction
(gasification) C + H20 -> H2 + CO
Shift reaction CO + H20 -> H2 + C02
Methanation 3H2 + CO •> CH4 + H20
The extent to which each of these reactions predominates and/or
can be controlled under in-situ conditions is one of the princi-
pal subjects of current technical investigations.
2.1.2 Fundamental UCG Operations
Pregasification -
In-situ processing steps consist of pregasification
followed by gasification and production. The main feature of
pregasification is preparation of the bed by linking definable
points in the coal seam such as the inlet and outlet boreholes
or shafts. These linking processes generally increase the per-
meability of the coal bed and promote a smoother and faster gasi-
fication process. Some coal seams are naturally quite permeable
and do not require "pregasification." The majority of coal
seams, however, do require some pretreatment. Methods of
-5-
-------
linking the desired points in the bed include electrolinking;
pneumatic linking; fracturing by hydraulic pressure, explosives,
or possibly nuclear reaction; deviated drilling and reverse com-
bustion. This last method has been successfully used during the
Hanna experiments (L-727, L-8730, L-5480).
Electrolinking is performed by passing a current
through the coal seam carbonizing the coal. The rearrangement
within the coal structure which occurs with this technique
increases its permeability. Pneumatic linking involves pre-
treating the coal seam by passing high-pressure air through it
before the gasification step. Fracturing the seam will obviously
increase its permeability. The process of hydraulic linking
involves injecting fluids under high pressure into the coal seam,
thereby causing fracturing and hence increased permeability.
Sand or some other inert agent is often subsequently injected
into the fracture to prop it open after release-of the pressure.
Studies are also being conducted with liquid explosives. Another
possible linking method is drilling horizontal or deviated holes
through the coal seam from the inlet air shaft to the exiting gas
shaft (L-871, L-683, L-2116, L-5480).
During the linkage phase of the vertical linked well
technique practiced at Hanna, a path of increased permeability
between the two wells is created by reverse combustion (combustion
front propagation countercurrent to injected air movement).
Combustion is initiated at the bottom of the production well with
an electric heater and moves toward the injection well during a
period of low-flow (^50 scfm) , high-pressure (^250 psig) air
injection. An increase in permeability occurs as the combustion
zone nears the injection well allowing injection of larger
quantities of air (^2000 scfm) at low pressure O30-50 psig).
-6-
-------
Gasification -
The gasification of the coal seam involves introducing
the gasifying agents, contacting these agents with the coal, and
recovering the reaction products. The methods of gasification
can be classified as shaft type, shaftless type, or a combination
of both. Shaft-type gasification requires the drilling of under-
ground channels or passageways. Shaftless gasification requires
only surface drilling operations. Current research is almost
entirely devoted to the development of shaftless technology
including: 1) the blind borehole method which employs a single
hole with concentric pipes and 2) the percolation or filtration
technique in which multiple boreholes are used. With this second
approach, the coal seam is penetrated by boreholes at specified
distances and gasification takes place between pairs of holes.
This vertical linked well concept utilizes the natural permeabil-
ity of the coal bed, often in conjunction with overt linking
methods.
The gasifying agents used are oxygen, steam and carbon
dioxide. These gases are introduced in varying proportions and
contacted with the pretreated coal seam. During combustion
oxygen reacts with the carbon in the coal to form carbon monoxide
and dioxide. Water vapor reacts with the coal to produce carbon
monoxide and hydrogen. Other reactions in the process (as listed
in Section 2.1.1) produce additional carbon monoxide, carbon
dioxide, and hydrogen. The exit gas from a UCG process consists
of carbon monoxide, carbon dioxide, hydrogen, water vapor, nitro-
gen, methane, and various other volatile organics from the coal
seam (L-8730). The product gas stream also contains heavier
entrained hydrocarbons and hydrogen sulfide. The heavy hydro-
carbons can be removed in a mechanical separator while the hydro-
gen sulfide must be removed by a chemical treatment method such
-7-
-------
as amine absorption. A typical in-situ gasification process is
diagrammed in Figure 2-1 (L-727).
Utilization -
Possible utilization schemes for the gas produced from
in-situ processes include (L-1216, L-2645):
Combustion in boilers to produce electricity
Use in turbine or combined-1 cycle power generating
systems
Conversion to high-Btu gas for transport to
consuming centers
Conversion to liquid fuels via Fischer-Tropsch
synthesis
Utilization as a hydrogen source for ammonia or
methanol synthesis
Utilization as a reductant gas
Utilization as a chemical feedstock
Since long-distance transport of low-Btu gas is generally regarded
as economically unattractive, the product gas must either be
utilized at the production site or converted to a pipeline-quality
gas or liquid fuel.
-8-
-------
A
KEY
A - Fuel Gas'.Product
B - Coal Tar Products
C - Compressor
D - Fuel Gas and/or Oxidizer
E - Production Well
F - Overburden
G - Injection Well
H - Charred Residual
I - Crumbled Coal
J - Combustion Front
ABSTRACT
Two or wore wells are drilled into a coal seam. The
veils are completed so as to isolate all other strata
from the coal seam and a. radially extended horizontal
fracture is directed by introduction of a non-hypersen-
sitive explosive under hydraulic fracturing conditions
so as to connect the uells communitively. The explo-
sive is ignited so that a horizontally and vertically
directed fracture network is formed within the coal
system. A combustion front, is ignited and propagated
through the fractured network to produce combustible
gases and coal tar liquids.
Figure 2-1. U.S. PATENT ON IN-SITU GASIFICATION OF COAL
UTILIZING NON-HYPERSENSITIVE EXPLOSIVES
(Source: No. 3,734,180 [May 22, 1973] V. W. Rhoades, Cities Service Oil Company)
-9-
-------
2.1.3 Unresolved Technical Problems
Experience with in-situ gasification has revealed the
existence of several potential technical difficulties. Numerous
studies are underway to resolve or further define the causes of
some of these problems.
Achieving positive connection between the inlet and
outlet wells during the pregasification phase has been accom-
plished by two methods. Directionally drilled boreholes is the
first method and has been proven to be effective for various
types of coal. The second technique is linkage by reverse
combustion. This method was successfully demonstrated during
the Hanna II tests using a subbituminous coal seam. The effec-
tiveness of reverse combustion still needs to be demonstrated
on other coal types.
Numerous problems during the gasification phase have
been pointed out. The majority deal w,ith the question of main-
taining good control over the process.
The major objectives of any UCG control strategy are
to achieve a uniform gas quality and production rate. Contact
between the coal and reactant gases should be controlled so as
to minimize production of C02 and H20, and to maximize oxygen
consumption and efficiency of coal usage. These objectives are
relatively easy to meet during the intial period of any test
but become more difficult to ahcieve as the void space increases
causing poor gas-coal contact.
An associated problem is the development of accurate
process monitoring techniques to follow the gasification or link-
age process from the surface and to provide data for process
control. Specific problems include (L-5480, L-871, L-683,
L-1326, L-2645, L-847):
-10-
-------
Establishment and maintenance of ignition
Directional control of the flame front
Uneven burning due to nonuniformity in coal bed
Control of temperature in the reaction zone
Plugging and reduced permeability due to depo-
sition of tars and slags
Gas leakage from the gasification area (safety and
environmental as well as efficiency loss aspects)
Penetration of groundwater into the reaction zone
resulting in oxygen loss, temperature fluctuation,
possible extinguishing of combustion process, and
later groundwater contamination
Control of roof collapse which can cause decreased
permeability and increased oxygen bypass as well
as create subsidence problems in some situations
A decrease in the product gas heating value as
gasification proceeds due to the poor gas-coal
contact that results as the void fraction of the
coal bed increases and/or as water enters the
gasification zone
Control of shut-down
-11-
-------
Some problems are also foreseen in the utilization of
the product gas. These problems are primarily due to fluctua-
tions in gas production rate flow and quality. Solutions to
these problems are being sought. No major technical problems
are envisioned in this area; however, upgrading the product gas
to a pipeline-quality fuel or gas has not yet been demonstrated
to be practicable.
Several general disadvantages associated with in-situ
gasification have also been noted (L-5480, L-1326, L-683, L-727,
L-8730). Coal energy recovery at this time remains low or ill-
defined. The underground process itself is not completely under-
stood; therefore, extrapolation from small field tests to the
commercial scale is not yet feasible. Site-related variations
pose more difficult problems than other mineral extraction proces-
ses because thermal and chemical as well as mechanical aspects
are involved.
Intimately tied up with these technological problems
are associated potential environmental impacts such as groundwater
contamination, air quality degradation and subsidence. These
problems are specifically addressed in Section 3.0 of this report.
Specific approaches to defining these problems which are currently
under investigation are discussed in Section 2.2.
2.2 CURRENT UCG PROJECTS
In this section summaries of ongoing studies related to
in-situ coal gasification are presented. The major efforts in
the U.S. include the ERDA-funded projects at Hanna (LERC) and
Gillette (LLL), Wyoming, and Pricetown, West Virginia (MERC);
Texas Utilities' lignite gasification test; and the University
of Alabama's in-situ project. These and some additional smaller
-12-
-------
scale investigations are summarized in Table 2-1. Foreign
projects are also briefly covered. More detailed descriptions
of the objectives, scopes and available results to date are
presented in the Appendix.
-13-
-------
Table 2-1., SUMMARY OF ONGOING UCG RESEARCH PROJECTS
-P-
i
Results
Objectives
Current status
Environmental
O v erall__jjb 1ec11 v e - Evaluate the tech-
nical , environmental and economic
feasibility of UCG in a thick, western
subbitumlnous coal seam.
PKOJECT.° Hanna - Linked Vertical WelJ Process
LOCATION: Hanna, Wyoming
PARTICIPANTS: La ramie Energy Research Center (LERC)
The most advanced of
any U.S. project. Two
field test programs
have been successfully
completed and more ace
planned.
Hanna I - March 1973 - March 1974.
Investigate forward and reverse
combustion as linkage techniques and
forward gasification in a 5-well
pattern using air as the oxygen source.
Hanna Ila Phase I - April - Aug. 1975.
Evaluate coal seam permeability;
linkage via pneumatic fracturing and
reverse combustion; sustained gasi-
fication between two linked vertical
wells in a 4-well pattern.
Hanna II, Phase II - Hay 4-31, 1976
(gasification period)
Investigate process control capa-
bllities during two linkages and
one gasification burn In a square
4-well pattern. Injection rate was
varied during gasification. Exten-
sive monitoring Instrumentation
utilized (Sandia Lab.),
Hanna II, Phase III - June 24-July
31, 1976 (gasification period)
A line-drive reverse combustion
between two linkage pathways
established in Phase II was planned,
to be followed by gasification of
the area encompassed by the 4 wells.
Completed Forward combustion linkage unsuccessful.
Reverse combustion linkage was success-
ful at high-pressure, low-volume injec-
t ion conditions. During gasification
tests, production rate averaged 1.6
million scf/day with average product gas
heating valnfe of 126 Btu/scf. It was
demonstrated that groundwater influx and
gas leakage can be controlled by air
injection pressure. Directional control
of combustion front was achieved.
Completed Control of reverse combustion linkage
was demonstrated. Air injection rate
could be reduced by a factor of 10 with
only a 10% decrease In gas heating value
(avg. 152 Btu/scf). Gas production
totalled 102.5 million scf.
Completed Narrow linkage path can be placed at
bottom of seam. Gasification front
could have been as wide as 60 feet.
No dramatic effect of varying injec-
tion rate during gasification. Overall
Improved gas quality (171 Btu/scf) and
resource utilization attributed to high
injection rates and use of back-pressure
to contro I Influx of groundwater.
Completed Attempt to create broad 1Inkage path
was not successful. Plans therefore
mod i fled to another two-well burn.
Excess water greatly lowered healing
value of gas (137.8 Btu/scf) and
thern.il efficiency of the process.
No measurable gas leakage from reaction zone has
occurred to date. Similarly, no measurable
surface subsidence has occurred.
Condensate from the product gas stream collected
during llanna I and II have been separated into
organic (coal tar) and aqueous fractions. The
water fraction along with some additional water
samples from down-hole sampling are presently
being characterized by GC-MS to identify organic
components which might potentially enter ground-
water systems.
The organic fraction has received considerable
attention. After separation Into tar acids,
bases„ neutral aliphatics, and neutral aroma-
tics , each fraction is being analyzed. The
weak acids are almost exclusively phenolic in
nature, while the tar base fractions contain
pyridlnes, anilines and quinolines with some
substituted pyridines also present. Prelimi-
nary results indicate that the aliphatic
neutrals apparently contaIn a normal saturate
series running from Cm to Ca 2 with some
branched saturates and a pnrtlcularly heavy
level of C|9 branched chains. Very low con-
centrations of unsatur.ited or eye 1 lc compounds
were measured.
Results of product gas monitoring during Hanna
II, Phase II, Indicated Hint no unforeseen
problems should be encountered in the area of
air quality monitoring. Particulate loading
ranged from 0-0025-0.36 gr/scf, with the major-
ity being <2\\. Nib, HCN, COS, CSa and trace
elements were also determined. NHi levels
wore lower than expected, ,-uut COS and CS2
varied with time, with COS decreasing and CS2
increasing over the monitoring period. The
only trace elements of those monitored to
exceed I ppm were Na and Ca.
Continued
-------
Table 2-1. Continued
Ln
I
Objectives
Banna_II_I - Third Quarter 1977
Determine water quality impacts ut UCC
via monitoring of seam and overlying
aquifers. Demonstrate feasibility of
computer monitoring for process con-
trol and stability of product gas
composition by maintaining constant
air/water ratio.
Hanna IV -
Investigate feasibility of relatively
long-distance linking (100-150 feet).
Determine relationships between
injection rate, well separation and
sweup width. Define void shape and
gasification front as a function of
t true,, Demonstrate relaying process
from one 2-well system to another.
Determine gas composition and pressure
gradients within the seam with time.
Monitor trace components in product
gas over the total test.
Hanna V -
One-year test consisting of 9 wells in
3 by 3 matrix with production rates up
to 90 MM scf/day. May involve testing
gas cleanup and utilization in gas
turbine. Monitor subsidence effects
and obtain scale-up design information.
Overall objective - Evaluate the
feasibility of applying an underground
packed-bed reactor model to the produc-
tion of pipeline-quality gas from thick,
deep scams of western coal.
Funclajuenlal^ Laboratory Studies -
Define fundamental mechanisms of UCG
including thermal wave propagation,
coal behavior and product quality
parameters- Define leuchability of
c liars and sorpt ive capacities of coal.
Results
Current status
TechnologicaI
Knvironmental
Planned
Planned
Planned
PROJECT; LLL's Underground Packed-Bed Reactor
LOCATION: Hoe Creek Site near Gillette, Wyoming
PARTICIPANTS: 6 Lawrence Livermote Laboratory
• ERDA (current sponsor)
• Atomic Energy Coaunission (initial sponsor)
Ongoing
Gas quali ty using steam and oxygen reac- I.cachate from laburatory-pns i f I rd ros I due (nnh) was
tants is comparable to that produced in a analyzed for Al , Ca, OH and pli. It was found Lhat
Lurgi system. Wyoming subbl tumi nous <:o:iJs ioaching of Ca and OH
were found to shrd nk and become cons i dor- and A I for 7 years based on asnumi
ably more permeable upon lio.otJ ng. Tnr IcHchaLos contained 1000-2000 p|ii
wuu Id cunt tin it? for 26 yc.irs
ions used.
soluble
jrganics (mostly pbcnols) which would proh.ilily
C-onL i nuod
-------
Table 2-1. Continued
Results
I
M
O\
Objectives
Current Status
Technological^
Environmental
Uater Quality Dispersion Model -
Describe groundwater plume movement
based on laboratory-derived pollutant
teachability and sorption data as
well as hydrogeological site
description.
Air Quality Modeling - Model air
pollution plume expected to result
from Hoe Creek gasification test.
Kommerer Field Test - Conduct small-
scale high-explosive fracturing test.
Hoe Creek Experiment No. 1 - This
preliminary test was a simple two-
spot fracturing test to improve the
permeability of the seam. Original
plans called for air gasification
to follow (see Phase tl below).
Hoe Creek Experiment No. 1» Phase II - Drilling in progress
This revised plan now calls for drill-
ing new production well closer to the
in]ect ion well. Followi ng dewatering,
gasification via a forward burn is
planned. If plugging occurs, reverse
combust ion may be called for prior to
gasification.
Preliminary results are The model has been developed and many
available input parameters have been defined.
Preliminary conclusions
are reported
Completed
Completed
(November 5, 1975)
Measured permeabi11ty and fracturing
were in good agreement with predictions
for the one- and two-dimensional stress-
strain codes.
Preliminary explosive fracturing resulted
in lower than expected permeability
increases. Therefore, a second phase
was planned before gasification (see
Phase II below).
Hoe Creek Experiment No. 2 (Five-Spot
Test) - The objective of this test is
to explosively fracture and dewater
a suitable zone, then over a 2-month
period gasify ^3000 tons of coal in
a 25-foot thick block. Caseous and
liquid effluents will be monitored.
Drilling operations
were halted December
1975. The future
status of this exper-
iment will depend on
the outcome of Hoe
Creek 1, Phase II.
be released as a slug. Sorption J.sutherms anil
distribution coefficients (Kj) were then deter-
mined. Coal was aa infinite sorbent for A10 K^
for organicH depended on the initial concentra-
tions and ranged from 2.0 to 50.0 as ctineenlra-
tlon decreased from 2000 ppw. Ca was snrhed by
coal Lo a much less extent than th« organ l<:s.
The organic plume is predicted to move only
M500 tn in 1000 years and its concentration will
be reduced from 2000 to 200 mg/fc. The Cn+2 plume
will move ^3000 m downstream in 100 years and its
concentration will be *^A5% of the original
"input" concentration.
General conclusion reached is that the Hoe Creek
site should not produce adverse air quality
condi Lions even under worst operating conditions.
Continued
-------
Table 2-1. Continued
Results
Objectives
Current status
Technological
Environmental
The overall objective la to determine
the applicability of Russian tech-
nology to deep East Texas lignite
deposits for electric power genera-
tion. In the first test, the heating
value and quantity of gae produced,
process economics, and environmental
impacts will be investigated.
PROJECT: TUSI Lignite Gasification Project
UKATION: Site near Fairfield, Texas; near TUSJ's Big grown Powei Plant
PARTICIPANTS; Texas Utilities Services, Inc. ITIJSI)
Drilling and other site
preparation work was
initiated in March 1975.
The first burn took
place in August and
September 1976.
Grouuduater monitoring
is continuing. If
analyses of results are
encouraging a pilot-
scale operation may be
considered.
The operation was shut down after 28 days Results of .groundwater monitoring showed
when the gas quality became too Inferior
to continue. Operation under much
decreased pH and Increased conductivity levels
in 4 wells (3 in the lignite seam and one in
reduced pressure was necessary to control the overlying aquifer). The pll drops were
in-situ water quality. No data was
available regarding gas quality.
noted as soon as 1 day after air Injection was
initiated, with the conductivity changes occur-
ring a few days later. After 5-31 days the pH
levels appeared to line out but at below-normal
levels. Other analyses were either Inconclu-
sive or not yet available.
Oyer^l^Objective - Identify
controlling mechanisms in UCC
using deviated drilling technology.
Specific objectives Include improve-
ment of resource utilizations
optimization of product gas heating
value and composition, and minimi-
zation of environmental degradation
and cost.
Theoretical studies - Conduct process
simulation of coal bed, emphasizing
internal effects such as shrink-
swell behavior, phase changes, etc.
Laboratory Studies - Investigate
actual physics of UCG; quantification
of mechanical and thermal effects and
physical properties, and supply data
for process simulation studies.
Fle^ld _PrpJ_e£t - Demonstrate feasibil-
ity of new directional drilling
technology.
PROJECT: MEHC's Longwall Generator Concept
LOCATION: Pricerown, Werzel County, (Vest Virginia
PARTICIPANTS: • Horgantown Energy Research Center IMERC)
• Consolidation Coal Co.
• Continental Oil Co.
In progress
In progress
Drilling of one directional
hole is finished but linkage
with the vertical hole has
not yet been achieved.
Cont inued
-------
Table 2-1. Continued
Results
00
I
Objectives
Current status
Technological
Environmental
Over ajj^^objgcj^ive - Two-year study
of the technical" feasibility of in-
situ gasification of thin seams o£
eastern bituminous coal.
Site Selection - Requirements Include
seam thickness less than 1 meter thick.
Characterisation of Site - Charac-
terize coal, geology and overburden
in vicinity of {imposed test site.
Air Acceptance Tests - Measure rate
at which air or another gas can be
forced into a coal seam through a
drilled and cased borehole at a
specified pressure.
Laboratory Combustor Studies -
I'rovide data for correlation between
product gas quality and input
variables.
Investigation of. Linking Technique^ -
Evaluate hydraulic fracturing for
initial permeability development and
possibly reverse combustion to com-
plete the linkage. MERC's deviated
drilling technology is also being
considered.
Develop__Nume_rical Analysis Methods -
This Is a support task involving an
analysis of results from other tasks
to supplement laboratory and field
stud ins. Topics under study include
advance rate and lateral extent of
combustion front during reverse burn
and associated heat transfer and
fluid flow considerations.
PRO.1ECT: University of Alabama
LOCATION; Warrior Coal Field near Adger, Alabama
PARTICIPANTS: • University of Alabama
- Alabama Power Co. ^co-sponsor,)
• Mineral Resources of Alabama (co-sponsor)
• NSF (co-sponsor)
One year into project
Completed
Significant progress
has been made.
Properties of coals in Warrior Field have
been compiled. Most are ranked as high
or medium bituminous coals.
In progress - two test No results reported yet.
holes have been, drilled
and more are planned.
Some meaningful results Results are summarized in the Appendix.
have been obtained.
This part of the pro-
gram is continuing.
In progress No results reported yet.
In progress
No results reported yet.
Continued
-------
Tahle 2-1. Continued
Results
Objectives
Croundwater Contamination Studies -
Define potential long-term contamina-
tion oE groundwater, considering both
organic and inorganic species* This
task involves laboratory leaching,
modeling studies and baseline ground-
water monitoring activities.
Determine geological, physical and
chemical conditions conducive to UCG.
Develop model for physical and
chemical processes. Demonstrate UCG
on a bench scale. Select site for
field tests based on engineering
and geological data.
Current status
Technological
Environmental
Evaluation of reverse combustion
linkage and subsequent forward
gasification with air for In-sltu
gasification of Texas lignite.
In progress
itesulr.s of leaching studies on laboratory-
derived gasification residues were reported in
terms of decay coefficients and initial, release
concentrations. Leaching curves were fitted
by an exponential decay equation; phenols,
however, did not fit this curve. The general
conclusion reached to date la that LULlaii&r.t prill.
problems should result from UCG although initial
releases of some components exceeded availably
water quality standards used in the stuci^.
Particle size was found to have a significant
effect.
PROJECT: University of Texas Project for Texas Lignite Gasification
LOCATION: site not yet selected.
PARTICIPANTS: ' University of Texas
• RANN/NRF
Texas Utilities Services Co.
Continental Oil Co.
• Mobile oil Co.
State of Texas
Based on results to date, it has been
concluded that IJCC is technically feasible
for application to deep basin Texas lignite.
It appears that in-situ gasification will
expand the extraction limits for coal by a
factor of ten over strip mining.
The program has been
underway for 2% years.
Significant work has
been done to charac-
terize potential site
areas but a site has
not been selected. A
bench-scale reactor has
been designed and con-
structed. A process
simulation model has
been developed and an
economic model is nearlng
completion.
PROJECT: Texas ASH Project
LOCATION: Hear College Station, Texas
PARTICIPANTS: Texas ASM University
Just getting underway. No results reported yet.
Cuntinued
-------
Table 2-1. Cnntlnued
Objectives
Evaluation of process based on gasi-
fication by COz and Oz rather than
steam and Oj or air for application
in semi-arid regions of the Southwest.
Result*
Current status
Tec! mo 3 o gl c a
Environmental
PROJECT: Los Alamos
PARTICIPANTS:
Los Alamos Scientific Laboratory
ERDA (to be proposed)
Initial conceptual devel-
opment being carried out
by Los Alamos. Plan to
submit the proposed pro-
cess to KRDA Cor funding
later.
O
I
Development of instrumentation
for monitoring UCG processes*
Investigation of reaction-controlling
variables and product distributions
for the gasification of coal and char
using steam and oxygen. Also,
evaluation of using brackish water as
water source.
PROJECT; Sandia Lab Instrumentation Development
LOCATIONS: • Wanna, Wyoming
• Gillette, Wyoming (later)
PART 1CIPANTS .-
Sandia Laboratories
EKDA (sponsor)
Instrumentation developed
to date was tested during
the Hatuia 11 burns. Plans
also call for probable
application and testing at
the LLL site.
PROJECT: Argonne Natior&l Lab Project
PARTICIPANTS: • Argone National Laboratory
' ERDA (sponsor)
PROJECT: West Virginia UCG Modeling
PARTICIPANTS:
Nest Virginia University
Bureau of Mines
Conduct computer studies on In-situ
gasification.
PRO.1ECT: USSR Applications
PARTICIPANTS: USSR
Development of UCG to commercial
scale.
There are currently four Consult overview report (L-8618),
or five electrical gener-
ating stations powered by
gas frum UCG in Russi a.
No environmental problems are x'cported in this
11terature.
Cont inued
-------
Table 2-1. Continued
Objectives
Develop in-siCu technology for
utilization in coal fields located
in West German Ruhr through northern
Belgium and the Netherlands. Pos-
sibly combined-cycle utilization
will be tested. If successful
results are achieveds substitution
of hydrogen for air to obtian high-
Btu gas may be attempted.
Current status
Technological
PROJECT: Belgium/West Germany Cooperative Study
LOCATION: Specific tost site not yet named
PARTICIPANTS; • Helgium
• West Germany
Just getting underway.
Initial testing planned
for early 1978.
No results reported yet.
PROJECT: Canadian UCG Project
PARTICIPANTS: Alberta and British Governments
A test burn has been conducted.
Result's
Environmental
No results have been reported.
ro
M
i
In-situ gasification of a lou-grade
coal with high mineral content and
subsequent utilization for electrical
power generation is being tested'in a
5-MWe unit.
PROJECT: Pilot-Scale NCR Project
LOCATION: Newman Spinney Station near Sheffield
PARTICIPANTS: • National Coal Board
Work has been underway
since 1957.
Central Electricity Cenerating Board
Specific results not yet reported.
PROJECT: Czechoslovakia UCG Project
tfKATION: Northern Bohemia
PARTICIPANT: Czechoslovakia
Development and application of lateral Current status unknown.
gas removal technology to gasification
of brown coal in northern Bohemia.
Industrial-scale project was planned
involving 220-MWe power generating
unit, tar and HzS removal units, and
wasteuater treatment.
Trial tests initiated in 1956 were
successful.
-------
SECTION 3.0
SUMMARY OF ENVIRONMENTAL IMPACTS OF UCG
The purpose of this section is to summarize real and
potential environmental problems associated with in-situ coal
gasification. Ongoing studies of air and water quality impacts
were summarized in Section 2.2; details are available in the
Appendix. Significant results forthcoming from those efforts
will be summarized here.
The areas addressed in this section include:
Water quality impacts
Air quality impacts resulting from the
production and utilization of product gas
Subsidence
Effects of hazardous by-products or wastes
3.1 WATER QUALITY
The potential for contamination of groundwater is
considered by some to constitute the most serious environmental
threat posed by underground coal gasification. While this aspect
of UCG is still in the definitional stages, more work has been
done in the water quality area than in any other area of poten-
tial environmental concern. Degradation of groundwater could
result from any of the following three sources:
Organic contaminants in the tars produced
during carbonization or gasification
-22-
-------
Inorganic salt or trace element loading due
to dissolution of ash
Changes in flow patterns or rates resulting
from subsidence or interconnection of aquifers
by fracturing
In addition, disposal of water pumped from the coal seam during
dewatering operations may constitute a surface water problem
depending on the nature and level of contaminants found in the
water.
Due to hydraulic gradients, migration of groundwater
will occur through coal seams and burned-out areas which lie below
the water table. This may cause soluble components in or sorbed
on the ash or char to be leache.d out and transported away from
the gasification site. An increase in dissolved organic material
could result from partial dissolution of coal tars formed during
gasification. As a general rule, the lighter, more soluble tar
fractions will be swept to the surface with the product gas, while
heavier, less soluble fractions tend to remain in the ground.
Over a long period of time, however, slow dissolution of even
these fairly insoluble components might occur.
Similarly, incorporation of inorganic salts and trace
elements into the groundwater regime could occur via leaching of
ash components. In order to develop a predictive capability for
levels of contaminants in the groundwater exiting the burn area,
characterization of gasification residues and their short- and
long-term leaching behavior must be determined. Actual field
data from samples of groundwater exposed to in-situ gasification
materials can supply additional valuable insight to the problem.
-23-
-------
Several types of studies have been performed or are in
progress in order to characterize water that comes in contact
with product gas (via gas leakage) or gasification residue. These
investigations include bench-scale leaching of carbonization and
gasification residues (LLL and University of Alabama), analysis
of organic condensate from product gas (Hanna), characterization
of water samples from burn areas (Hanna and TUSI), and groundwater
monitoring at gasification test sites (Hanna, TUSI, and planned
at LLL). Additional groundwater studies are planned for all these
projects.
Results to date indicate that coal tar components
include:
phenols
. • pyridines
anilines
0
quinolines
aromatic hydrocarbons
Based on general solubility characteristics of these potential
water pollutants, phenols pose the greatest threat, while
pyridines and anilines are also regarded as soluble and therefore
likely to be present in the water. Quinolines, which are some-
what less soluble, may be present at trace levels. Aromatic
hydrocarbons are not expected to present a .significant hazard to
water quality.
The dispersion of soluble contaminants will be a
function of groundwater flow and the sorptive properties of the
materials through which the leachate passes. Laboratory studies
are in progress at Lawrence Livermore and at the University of
Alabama to determine the sorptive capacities of coals and chars.
The results will be used in modeling studies designed to describe
-24-
-------
ground-water plume behavior. Results to date indicate that coal
appears to be a very sorptive material for both organic and
inorganic species. In one study in which tap water was used as
the leaching medium, trace metal levels in the effluent were
lower than baseline levels; that is, the coal appeared to remove
not only those trace metals leached from the gasification resi-
due but also those present originally in the tap water. Concen-
trations of those species for which intial leach concentrations
exceeded available water quality standards* (NHa, COD, phenols)
were lowered to undetectable or acceptable levels by passage
through the coal.
Results to date from the LLL modeling study also
indicate that coal is a very sorptive material for both organic
species (individual components not measured) and inorganic ions.
Based on this fact and the slow flow rate exhibited by ground-
water, plume movement should have negligible short- and long-term
effects upon most groundwater regimes. Some of the assumptions
and experimental methods employed, however, may have optimisti-
cally biased these findings.
* Promulgated and recommended standards for comparison in the referenced study
include:
BOD, COD Effluent averages of samples, Tuscaloosa (Alabama) Wastewater
Treatment Plant.
BOD Effluent monthly average set by EPA as suitable for Tuscaloosa
Wastewater Treatment Plant.
2V#3 Recommended maximum level for public water supply (Water Quality
Nitrite Criteria 1972)
Sulfate
Phenols
TDS Desirable maximum level for public water supply; may be exceeded
if concentration of other individual substances remains below
recommended limits (Water Quality Criteria 1972).
Nitrate Maximum level set by law for public water supply (Federal Register,
December 24, 1975).
-25-
-------
All of the test sites planned or operating include
instrumentation and/or sampling wells for monitoring groundwater
quality. The only project for which data are presently available
is the TUSI lignite gasification project in East Texas. These
results are very preliminary, but noticeable increases in conduc-
tivity and decreases in pH were measured in some wells located in
the coal seam and the immediately overlying aquifers. Limited
data indicate the presence of phenols in the overlying aquifer as
well. Temperature and NH3 levels were not affected, while sulfate
levels showed a "decrease. Based on the data available, no long-
range conclusions can be drawn at this time, but monitoring is
continuing at the site.
Another potential water quality problem which has
received limited attention is the disposal of water removed from
the gasification zone during dewatering operations.- Although no
decisions can be made until the quality of this type of water has
been more fully characterized, the following utilization/disposal
options have been suggested.
Pumping the water to nearby stock tanks for
livestock use
Using the water for dust suppression on roads
Surface treatment for phenols and/or pyridine
removal by some method such as activated carbon
Reinjection into the reaction zone or deeper
saline aquifers
-26-
-------
3.2 AIR QUALITY
Only one investigation of the potential impact of UCG
on air quality has been conducted to date. Product gas and flare
discharge at the Hanna test site were monitored for particulate
matter content and fourteen trace components. These included
carbonyl sulfide (COS), carbon disulfide (082), ammonia (NH3),
hydrogen cyanide ( HCN), mercury (Hg), lead (Pb), cadmium (Cd),
arsenic (As), selenium (Se), sodium (Na), potassium (K), lithium
(Li), vanadium (V), and calcium (Ca). The primary concern with
Na, Ca, V, Li and K is their corrosive effects should the product
gas be utilized in gas turbines. The other five trace elements
are of environmental concern.
The particulate loading in the product gas ranged from
less than 0.0025 gr/scf to 0.36 gr/scf, with the majority of the
particulate matter being <2y in diameter. Only one out "of six
samples deviated significantly from this size distribution; in
this one case greater than 85 percent of the particulate was <2y.
Since this occurred near the end of the monitoring period, it was
surmised that the natural filtering capacity of the coal in the
seam was diminishing as the test proceeded, allowing larger par-
ticles to be entrained with the product gas.
The results of the NH3, HCN, COS, CS2, and trace ele-
ment measurements were also reported. The NH3 emissions were
relatively constant and lower than previous rules of thumb had
predicted; i.e., that 80 percent of the fuel nitrogen is con-
verted to NH3 . One explanation for the observed lower values
is that some ammonia may have been scrubbed out by the conden-
sables in the product gas. It is also possible that this
general rule of thumb may be invalid for in-situ coal gasifica-
tion.
-27-
-------
Levels of HCN, COS and CS2 were low, as expected.
The latter two were observed to be time dependent, with COS
trending downward and CS2 upward. Analytical results for HCN
were relatively uncertain. Of the trace elements monitored only
Na and Ca exceeded the 1 ppm level.
The overall conclusion reached from this study was that
no unforeseen problems should be encountered in the area of air
quality monitoring. Development of a broad data base is needed,
however, in order to verify this preliminary conclusion.
3.3 SUBSIDENCE
Instrumentation for monitoring subsidence effects has
been installed at all operating test sites. To date, no detect-
able surface movements have been observed at Hanna. Information
of this nature from the TUSI site has not been made available.
No tests have yet taken place at the other project sites. Since
any measured subsidence will be related to geologic conditions at
the particular site and may not be generally applicable to other
sites, it will be necessary to gather this type of data for a
range of sites before any general conclusions as to the severity
of the subsidence problem can be drawn.
Subsurface subsidence is generally most likely to occur
as a result of roof collapse in the void area created as gasifi-
cation proceeds. This could have three direct effects: the
fallen material could decrease the permeability of the burn area,
reduce the flow of oxygen and, in extreme cases, extinguish the
burn. A second possible effect is the alteration of groundwater
flow patterns. This could increase the potential for groundwater
contamination or could alter the gasification process by reducing
the burn temperature or even extinguishing the flame. There is
also some indication that roof collapse results in a temporary
-28-
-------
increase in atmospheric particulate emissions. Another possible
effect of subsidence is increased potential for gas leakage,
resulting in a drop in process efficiency and/or possible ground-
water contamination by the escaping gases.
3.4 EFFECTS OF HAZARDOUS BY-PRODUCTS OR WASTES
Another related potential problem is spillage of coal
tar liquids condensed from the gas product stream. In one minor
incident reported, some of this liquid was spilled on the ground;
the vegetation was killed but new growth was observed in most
contaminated areas the following season. The herbicidal and other
toxicological properties of the tar liquids require further
investigation.
-29-
-------
SECTION 4.0
COMPARISON OF IN-SITU GASIFICATION
WITH ABOVE-GROUND MINING AND GASIFICATION
Commercialization of in-situ gasification will be in
direct competition with conventional coal mining and above-ground
gasification processes. This section briefly discusses techno-
logical and environmental aspects which should be considered in
comparing these alternate coal conversion routes. Economic
factors are not addressed in any depth in this discussion although
they would obviously be included in any definitive comparison.
Because UCG is in an early stage of development there are
insufficient hard data regarding commercial-scale gasification
facilities and environmental impacts; therefore, the following
discussion is limited to general comparisons of these important
issues:
Resource recovery efficiency
Energy and water usage
Technological development status
Economics
Land usage and impacts
Water pollution potential
Air pollution potential
Health and safety aspects
4.1 RESOURCE RECOVERY EFFICIENCY
The application of in-situ coal gasification is estima-
ted to expand the extraction limits for coal by a factor of ten
over strip mining (L-9168, L-9169). This is based on a comparison
-30-
-------
of overburden to seam ratios which define the limits of economic
attractiveness. For in-situ this ratio is 150:1, while that
associated with strip mining is 15:1. Of the total U.S. coal
resources, only 12 percent is considered recoverable by present
coal mining methods (L-4822). In-situ gasification could expand
the base of recoverable coal to include deep, thick seams over-
lain by excessive overburden and steeply dipping seams presently
not considered minable.
In conventional room-and-pillar mining, coal recovery
is typically 60 percent because some coal must be left in place
to provide support for the overburden (L-1216, L-871). Coal
utilization efficiencies for in-situ processes are presently
estimated to be of similar or greater magnitude. The coal utili-
zation estimated for the Hanna I experiment, based on material
balance calculations, was reported to be 63 percent (L-6631).
This represents the percent of coal affected (i.e., either
carbonized or completely gasified). Recovery efficiencies of
latent energy in the coal are addressed in Section 4.2. Recovery
calculations from a more recent test (Hanna II, Phase III) showed
that the total utilization in the 4-well pattern was 6700 tons
compared to 4600 tons within the 60- by 60-foot square, indicat-
ing a high overall areal sweep efficiency (L-9118).
Another aspect of resource utilization to be considered
is that in-situ gasification might impact the extraction of other
minerals (L-683). Decisions impacted by this factor must be made
on a site-specific basis.
4.2 ENERGY AND WATER USAGE
The two resources considered here are water and energy.
A comparative estimate of water usage for two base cases de-
scribed in Table 4-2, underground coal gasification and strip
-31-
-------
Table 4-1. COMPARISON OF UCG WITH CONVENTIONAL MINING PLUS SURFACE GASIFICATION
Underground coal
gasification
Conventional mining plus
surface gasification
1. Resource recovery
2. Energy and water usage
u>
K>
3. Technological develop-
ment status
Extraction limit (overburden:
seam ratio) of 150:1. In-situ
increases total recovery of
present U.S. coal resources.
Coal utilization for Hanna I was
63%, while apparently even
greater for later Hanna tests.
The water requirements of a UCG
process should be somewhat less
than those of an equivalent
strip mining-surface gasifica-
tion operation.
Energy return ratio of approxi-
mately 4 and overall energy
efficiency of V50% calculated
for Hanna I experiment.
Extraction limit of 15:1. Only 12%
of U.S. coal resources recoverable
by conventional coal mining. Re-
source recovery of 60% is typical of
room-and-pillar mining.
Water usage rate for a given strip
mining-gasification case is given in
Table 4-2.
Similar energy recovery efficiencies
for in-situ and stirred-bed producer
have been calculated. Energy input
for conventional mining not included,
however.
Most advanced U.S. project (Hanna) Low-Btu gasification is commercial-
has been successfully operated at
less than pilot level. Pilot-
scale project to be operational
in 1981 is planned. Outside U.S.
UCG is commercialized.
ized, although in U.S. only small
gasifiers are presently in operation.
There are still unresolved problems
with high-Btu gasification.
4. Economics
Equipment costs and UCG in gen-
eral will probably be less.
Transport of low-Btu gas from
remote locations is economically
unfeasible.
High coal transport costs between
mine and gasification facility.
Overall costs will probably be higher
than for UCG.
Continued
-------
Table 4-1. Continued
Underground coal
gasification
Conventional mining plus
surface gasification
5.
Land use and impacts
(refer to Table 4-2)
Minimal land disturbance.
Disposal requirements only for
coal tar (if not marketable) and
recovered sulfur. Future land
use applications not yet deter-
mined.
Water pollution
potential
Considerable land disturbance and
massive reclamation requirements
associated with strip mining. Addi-
tional solid waste disposal problems
compared to UCG. Future land use
typically restricted to recreational
and agricultural purposes.
Both strip and deep mining methods
have tremendous impact on water
quality in the form of acid mine
drainage. Pollution control methods
are difficult to apply since source
is undontained.
Major source of wastewater from
above-ground gasification is ash
quenching. Can be minimized by
recycle and methods are available
for treatment.
7. Air pollution potential Potential gas leakage from out- Fugitive dust from mining activities,
crops and high-pressure equipment, particularly strip mining, vehicular
Still undefined at this time.
Potential problems of unconfined
groundwater contamination by
inorganic components of ash,
organics from coal tar, and gas
leakage.
8. Health safety aspects
Fugitive dust from vehicular
traffic and site preparation.
Process sources include gas
purification units (similar to
above-ground facilities).
Minimal.
traffic and site preparation activi-
ties. Process emission sources
include gas purification (similar to
UCG) plus coal preparation and
product up-grading units (high-Btu
only).
High degree of occupational safety
and health hazards associated with
deep coal mining. Investigations in
surface gasification facilities in
preliminary stages.
-------
mining plus surface gasification, yielded the same water require-
ments on a yearly basis, i.e., 11 million cubic meters per year.
This comparison may or may not be meaningful, however, because
of the various factors that influence water usage in the gasifi-
cation processes. Stoichiometrically UCG and surface gasifica-
tion have similar water requirements. However, for UCG, some
of the water required is present in the coal seam. There will
also be some difference in the quantities of process water the
two gasification operations will require. The water quantity
comparison specified above does not consider the differences
in the quality of the water required by the processes.
Energy usages obtained from the in-situ Hanna I
experiment and a stirred-bed producer were calculated and com-
pared in one study reported in the literature (L-4822, L-8520,
L-6921, L-6631). The results indicated that similar energy
recovery efficiencies were achieved from both systems; however,
energy used in coal extraction was not considered in the stirred-
bed producer case.
The rate of energy return is defined as the ratio of
total energy produced from a system to the total energy consumed
in running the process. Energy available from the coal is not
considered in this indicator, which must be greater than one in
order for a process to be commercially feasible. The input and
output parameters considered in calculating the energy return
ratio for the Hanna I experiment are shown in Figure 4-1. This
ratio was 3.5-3.6, but it was noted that the use of more effi-
cient compressors and an improved flare system could increase
this factor to 8.0-8.3 (L-4822, L-6631).
A second factor used to compare processes is the
energy recovery efficiency. This is the ratio of energy produced
-34-
-------
Energy input
Energy output
m
i
Diesel fuel for «^
air compression/^
and mobile f
equipment /
10.9 x 109 Btu
Utilities
0.5 x 109 Btu
Total 11.4 x 109 Btu
HANNA I GASIFICATION EXPERIMENT
• 5% month operation
• 1.6 million cubic feet/day
• 126 Btu/cubic foot gas
Low-Btu gas
33.3 x 109 Btu
Liquid hydrocarbons
1.7 x 109 Btu
Sensible heat
4.4-5.8 x 109 Btu
39.2-40.8 x 109 Btu
Energy out
Energy in
= 3.5-3.6
Figure 4-1. ENERGY RETURN RATIO FROM UNDERGROUND COAL
GASIFICATION EXPERIMENT, HANNA I
(Source: L-6631, L-8520)
-------
to total energy available to the system; i.e., energy consumed
in running the process plus the latent energy available in the
amount of coal affected (i.e., gasified or carbonized). Overall
energy recovery efficiencies take into account all coal avail-
able, not just that affected. Material balance calculations for
the Hanna I test indicated that an average of 20 tons of coal
(dry basis) were affected daily. This represented an estimated
coal utilization of approximately 65 percent. Based on the
assumptions employed, the energy recovery efficiency was cal-
culated to be 0.497-0.515 for this case, as illustrated in
Figure 4-2. Improved compressors and flare system could possibly
result in an efficiency ratio of 0.541-0.560 (L-4822, L-6631).
An overall energy recovery efficiency of 37 percent
was reported for the Hanna I test (L-8520). The original
literature should be consulted for details of the various cal-
culations. Some discrepancies were noted which were apparently
due to different sets of assumptions and calculation techniques
applied to the Hanna I test results.
4.3 TECHNOLOGICAL DEVELOPMENT STATUS
In-situ gasification has been developed to commercial
scale in several countries outside the U.S., but it is not con-
sidered fully developed in this country. A summary of technical
research needs for UCG was presented in Section 2.1.3.
Surface coal gasification processes are presently at
various stages of development. Numerous small commercial-scale
low-Btu gasifiers are presently operating in the U.S.; although
several large plants have been proposed, none are yet built.
This is not the case in other countries, however, where coal
conversion has been more fully utilized. There are still un-
solved technological problems with high-Btu processes.
-36-
-------
LO
Energy available from
coal affected
20 tons moisture-free
coal per day
67.9 x 109 Btu
Energy to operate
system
Diesel fuel for air
compression and mobile
equipment
10.9 x 109 Btu
HANNA I GASIFICATION EXPERIMENT
• 5% month operation
• 1.6 million cubic feet/day
• 126 Btu/cubic^foot gas
Energy produced
Low-Btu gas
3.3 x 109 Btu
Liquid hydrocarbons
"l.7 x 109 Btu
Sensible heat
V4-5.8 x 109 Btu
Utilities
0.5 x 109 Btu
Total 79.3 x 109 Btu
Energy produced
Energy used + energy in coal
= 0.497-0.515
39.4-40.8 x 109 Btu
Figure 4-2. ENERGY RECOVERY EFFICIENCY FROM UNDERGROUND
COAL GASIFICATION EXPERIMENT, HANNA I
(Source: L-6631)
-------
4.4 ECONOMICS
Only very general comments regarding economic compari-
sons of in-situ gasification and above-ground gasification can
be made at this point. It has been stated that, although it is
generally considered economically unfeasible to transport the
low-Btu product from remote locations, UCG in general may be
cheaper than above-ground processes (L-1326, L-5480, L-8520).
In addition the costly transport of coal to the above-ground
conversion plant (if not a mine-mouth facility) must be
considered.
4.5 LAND USAGE AND IMPACT
This category includes such aspects as land (space)
requirements, subsidence and degree of land disturbance or
tremors, reclamation requirements, land disposal of Wastes, and
future land use.
Land area requirements for in-situ gasification will
be much less than for a comparable strip mine/surface gasifica-
tion module as is indicated by the estimated figures presented
in Table 4-2. The degree of land disturbance from each case is
indicated by the acreage subjected to subsidence (in situ) and
stripping (strip mining). Approximately twice as much land will
be disturbed by strip mining, and in addition the degree of dis-
turbance is likely to be much greater for this case; only mild
subsidence is generally predicted for in-situ gasification
although this estimate is unsupported at this time (L-683,
L-8520). The exact degree will be a function of many factors
such as depth and thickness of seam gasified, quantity of coal
blocks left for support, characteristics of overburden, degree
of faulting in area, and other geological and hydrological fac-
tors. Along a similar line, the impact due to tremors from
-38-
-------
Table 4-2. EFFECTS OF UNDERGROUND COAL GASIFICATION
COMPARED WITH STRIP MINING PLUS SURFACE GASIFICATION
Case A Case B
Underground Strip mining
coal plus surface
gasification gasification
Land area for plant facilities,
square meters 81,000 490,000
Stripped land per year, square
meters 0 1,000,000
Total land subjected to
subsidence per year, square
meters * 510,000 0
^Water required, cubic meters per
year 11,000,000
11,000,000
Sulfur recovered, kg per day
(needs to be disposed of if it
cannot be sold) 180,000 180,000
Ash to be disposed, kg per day 0 1,800,000
Basis : One plant producing 7 million normal cubic meters (2.50
million standard cubic feet) of SNG per day; coal contain-
ing one percent sulfur and 10 percent ash; 50 percent
recovery of coal for Case A with a seam thickness of 15.2
meters (50 feet); 50 percent recovery of coal stripped for
Case B with a seam thickness:of 7.6 meters (25 feet).
Source: L-683
*This value is based on stoichiometric water requirements and does not
include such items as water quality requirements and the potential for
utilizing the water present in the coal seam; however, water quality
generally does not have to be as high for underground gasification.
Also, there will usually be more water available for the underground
seam than for above ground.
-39-
-------
explosive fracturing during in-situ pregasification has also not
been quantified. To date, little evidence of a significant pro-
blem has been noted (L-683).
Reclamation of strip-mined land is a massive undertak-
ing. Based on current plans for installation of commercial gasi-
fiers for power generation, all those nearing commitment are
located in the western states and will be in conjunction with
strip mining. The arid climate in these regions will complicate
the reclamation efforts because of the difficulties involved
with revegetation (L-683).
Disposal requirements for wastes generated by in-situ
processes will be minimal compared to those for a comparable
conventional mining/surface gasification case. The only signi-
ficant wastes from in-situ gasification will be coal tar conden-
sate from the product gas and sulfur recovered during gas
f
purification. Surface processes, on the other hand, have to
deal^with the additional problems of ash disposal and signifi-
cant coal mining and preparation wastes. This includes spoil
banks, slack piles and tailings ponds (L-1216, L-683).
Future uses which can be made of the land overlying
an in-situ gasification site are also undetermined at this time.
This may be comparable to that over deep-mined regions. Factors
such as seam thickness, depth and nature of overlying rock
strata will be involved (L-683). Strip-mined land, on the other
hand, can usually be converted to recreational or agricultural
purposes after considerable reclamation. Some light building
may be possible.
-40-
-------
4.6 WATER POLLUTION POTENTIAL
This environmental aspect is the one receiving most
attention in UCG investigation. The main area of concern is
contamination of groundwater as a result of gas leakage, excur-
sions, and leaching of inorganic ash components and organic
coal tars condensed in and around the reaction zone. Coal has
been found to have high sorption capacities for many of the
potential contaminants. Modeling studies are being conducted
to predict dispersion and movement of the groundwater plume.
Preliminary results of these studies indicate a low potential
for significant groundwater contamination.
The main source of wastewater from surface gasifica-
tion is ash quenching. This stream can be treated by currently
available technology. The magnitude of the water pollution
problem from strip mining and deep mining, however, is much
greater. This acid mine drainage can be controlled, but appli-
cation of the technology is difficult because it is an uncon-
tained source.
4.7 AIR POLLUTION POTENTIAL
The potential impact on air quality due to in-situ
gasification was summarized in Section 3.2 of this report. In
general, a possibility exists for fugitive hydrocarbon and carbon
monoxide emissions from coal seam outcrops and high-pressure
equipment. Fugitive dust will be generated from on-site vehicu-
lar traffic and site preparation activities.
Process emission sources will include gas purification
units which should be similar in magnitude and composition to
surface low-Btu process emissions. Additional emissions from
-41-
-------
surface facilities will include particulates from the coal
preparation module and glycol and additional process condensate
from the gas up-grading units (high-Btu only).
4.8 HEALTH AND SAFETY ASPECTS
There are many occupational health and safety hazards
associated with deep coal mining methods. These include occu-
pational diseases, mine explosions and fires due to high levels
of gas and dust, mine collapses and other safety hazards (L-1215,
L-1326, L-4822, L-8520). In the case of in-situ coal gasifica-
tion, worker exposure to all of these problems is avoided.
Occupational safety and health aspects of UCG have not yet been
investigated, while studies of this type related to above-ground
coal conversion have only recently been funded.
-42-
-------
APPENDIX A
-------
ERDA'S LINKED VERTICAL WELL PROCESS AT HANNA, WYOMING
The linked vertical well (LVW) concept of in-situ
gasification has been under development since 1972 by the Laramie
Energy Research Center (LERC). Initial funding was provided by
the Bureau of Mines but the program has more recently been
carried out under ERDA sponsorship. The objective of this project
has been to test the feasibility of UCG in thick (>7.6m or 25
ft), deep (>107m or 350 ft) seams of western subbituminous coal.
A secondary objective of tests completed thus far has been to
maximize the heating value of the product gas while simultaneously
stabilizing the production rate and achieving a high coal
utilization efficiency (L-8520).
9
This process is in the most advanced development stage
of any on-going U.S. in-situ gasification project. Two full
field test programs have been completed (Hanna I and II) and
additional tests are planned. Results of the Hanna II experi-
ment showed greatly improved gas production rates and heating
values over earlier phases of the testing. Over a 30-day period
an average of 2.2x105 Nm3/day (8.5x106 scf/day) of gas rated at
7.12-7.52xl05 J/Nm3 (175-185 Btu/scf) was produced. This is
equivalent to approximately 6 MW of electricity. Future plans
include a pilot-scale project (15 MW) to be operational by 1981
(L-9171). Further details of .this project are given below.
LVW Process Description
The UCG experiments at the Hanna site are based on the
linked vertical well (LVW) technique with air as the oxidizer.
LVW is a two-phase procedure for gasification of the coal between
two wells in a coal seam in which one well serves as the injection
-44-
-------
well for introducing the oxidizer into the coal seam and the
other serves as the production well for transport of the product
gas to the surface (L-8555, L-8300). Figure A-l illustrates
the LVW concept of in-situ coal gasification.
During the first phase, linkage, a path of increased
permeability between the two wells is created by reverse combus-
tion (combustion front propagation countercurrent to injected
air movement). Combustion is initiated at the bottom of the
production well with an electric heater and moves toward the
injection well during a period of low-flow (^0.02 Nm3/sec or 50
scf/min), high-pressure (^1.8 MPa or 250 psig) air injection.
An increase in permeability occurs as the combustion zone nears
the injection well allowing injection of larger quantities
of air (^0.9 Nm3/sec or 2000 scf/min) at lower pressure (^0.31-
0.45 MPa or 30-50 psig).
At this point the system is prepared for gasification,
the second phase of the process. The combustion zone movement
is shifted to forward combustion (propagation of the combustion
front in the same direction as air injection) while high injection
air rates are maintained. The combustion front spreads over a
larger area around the injection well and the coal between the
two wells is gasified as the front moves toward the production
well while producing a low-Btu gas.
Hanna Test Site
Parameters considered in site selection included
seam depth and thickness, overburden characteristics, seam water
content, coal characteristics and dip. The test site chosen is
located approximately 110 km (70 miles) northwest of Laramie near
Hanna, Wyoming, as indicated in Figure A-l (L-8557, L-6631).
-45-
-------
WELL 1 WELL 2
////
/////
'//
GAS
PRODUCTION
HIGH-PRESSURE
AIR INJECTION
r
///
11 LLLi
DOWN-HOLE
ELECTRIC
HEATER
W
(A) VIRGIN COAL
(B) IGNITION OF COAL
HIGH-PRESSURE GAS
AIR INJECTION PRODUCTION
mill
(C) REVERSE COMBUSTION
LINKING FRONT PRO-
CEEDS TO SOURCE OF
AIR
LOW-PRESSURE
AIR INJECTION
GAS
PRODUCTION
mil
(D) LINKAGE COMPLETE WHEN
COMBUSTION ZONE REACHES
INJECTION WELL (SYSTEM
READY FOR GASIFICATION)
HIGH VOLUME
AIR INJECTION
">
PRODUCTION
r
JW/77777///
(E) COMBUSTION FRONT
PROCEEDS IN THE SAME
DIRECTION AS INJEC-
TED AIR
HIGH VOLUME
AIR INJECTION
GAS
PRODUCTION
r
I /' -.x ^"—*""
(F) COMBUSTION FRONT
EVENTUALLY REACHES
PRODUCTION WELL
Figure A-l.
DIAGRAM OF LINKED VERTICAL WELL CONCEPT OF UCG
(Source: L-8555)
-46-
-------
Figure A-2. LOCATION MAP OF LERC UNDERGROUND
COAL GASIFICATION EXPERIMENT SITE
(Source: L-6631, L-327)
-47-
-------
The coal seam being tested is the Hanna No. 1 seam,
which is a subbituminous coal, approximately 9m (30 ft) thick,
107-122m (350-400 ft) deep and approximately 55-61m (180-200 ft)
below the water table. The seam outcrops on three sides and is
isolated on the fourth by faulting. A hydrostatic force of
0.58-0.72 MPa (70-90 psig) is exerted on the gasification zone
(L-8557, L-327, L-6921).
The local overburden consists of a series of shales,
siltstones and sandstones. Strata directly above and below the
coal seam consist of less permeable shales with 4.6m (15 ft)
above and 1.2m (4 ft) below the coal. With the presence of an
aquifer 24m (80 ft) above the coal seam, as well as the seam
itself being saturated, gas leakage has not been a problem.
However, influx of seam water in excess of that required by the
process as a hydrogen source must be controlled by increased
back pressure and increased air injection rates (L-6921, L-8557)
Chemical characterization of coal core samples from
two different sites within the Hanna coal field is summarized
in Table A-l. Results showed that vertical differences were
great and unpredictable, but samples from the same horizontal
stratum were systematically and predictably different. In
addition, analyses of eight potentially toxic trace elements
in coal core samples were also reported and compared to those
from an eastern in-situ test site. The Hanna coal contained
significantly higher levels of fluorine and lead, while the
eastern coal was higher in arsenic and beryllium. Cadmium,
mercury, selenium and tellurium were also measured but signifi-
cant differences were not observed (L-5722) .
-48-
-------
Table A-l. CHEMICAL COMPOSITION OF SUBBITUMINOUS "A" COAL CORE
SAMPLES FROM SITES 1 AND 2 OF THE HANNA COAL FIELD,
HANNA, WYOMING
I
VO
1
Determination11
Total carbon
Volatiles
High- temperature
ash (750°C)
Total sulfur
organic sulfur
pyritic sulfur
sulfate sulfur
Fixed carbon
Hydrogen
Moisture
Nitrogen
Oxygen
Drill
(9
Range
27.62 -
23.85 -
5.62 -
0.41 -
0.36 -
0.02 -
0.01 -
17.25 -
2.40 -
5.50 -
0.63 -
7.65 -
L Hole 3
Sub samp
, 7.
69.89
43.37
58.89
2.80
0.69
2.14
0.25
53.02
5.15
8.06
1.47
20.20
, Site 1
les)1
Drill Hole 16, Site 1
(51 Subsamples)2
Average, 7.5
60
39
16.
0
0
0
0
43
4.
7.
1
16.
.69
.79
.95
.88
.47
.37
,04
.32
16
.14
.28
.00
Range, %
12.5
11.8
3.8
0.3
0
0.05
0
1.3
1.4
4.3
0.5
6.4
- 73.40
- 52.10
- 78.70
- 4.20
- 0.84
- 3.64
- 0.19
- 53.70
- 7.30
- 9.9
- 1..8
- 1«,7
Average, %s
54
37
24
0
0
0
0
37
4.
7.
1.
13
.70
.48
.98
.85
.38
.43
,03
.53
26
.91
,29
,88
Drill Hole 04, Site 2
(60 Subsamples) a
Range, 7.
12.5 -
15.6 -
3.7 -
0.30 -
0.05 -
0.08 -
0 -
5.5 -
1.6 -
5.6 -
0.40 -
4.20 -
73.1
46.0
78.9
2.60
0.88
2.23
0.43
52.40
5.60
10.90
1.80
16.40
Average, 7i6
49.62
34.65
31.65
0.75
0.39
0.34
0.21
33.68
4.03
8.62
1.25
12.70
1 The 9 subsamples from Drill Hole 3 were vertical halves of 3 to 5-inch long subsections taken at random intervals in the depth range 472.0 - 488.0 ft
The 54 subsamples from Drill Hole 16 were vertical halves of 6-inch long consecutive subsections taken in the coal interval of .178.8 - 4Of, .0 ft.
(Results for 3 samples in this interval are not reported, due to sampling Josses.)
The 60 subsamples from prill Hole 04 were vertical halves of 3-inch long consecutive subsections taken in the coal interval of 167.5 - 297.5 ft.
Ml values are on a moisture-free basis.
5 The average for each determination is a uoighted average for the entire coal interval, allowing for differences in thickness of individual coal
subsections.
Source: L-5722
-------
Test Program - Status and Results
Two field test programs, Hanna I and II, have been
completed and plans have been finalized for Hanna III and IV.
Objectives and approaches are also being outlined for additional
tests. Brief descriptions of each experiment are presented
below (L-9118).
' Hanna I - The first Hanna experiment was initiated in
March 1973 and terminated in March 1974. Both forward and
reverse combustion techniques using air as the oxygen source
were tested. Figure A-3 illustrates the well spacings and
sequential linkage pattern.
All linkages started from a common but expanding com-
bustion zone at Well No. 3 which was hydraulically fractured
prior to ignition. Attempts to achieve linkage by forward com-
bustion proved unsuccessful due to plugging by carbonization
products. Reverse combustion linkage was successfully carried
out. This stage was typically characterized by high-pressure
air injection (1.8 MPa at 120 m or 250 psig at 400 feet) at a
low rate. When the combustion zone reached the injection well,
an abrupt pressure drop occurred; at this point larger volumes
of air were injected at low pressure (^0.9 Nm3/sec at 0.31-0.45
MPa or 2000 scfm at 30-50 psig) until linkage was complete.
Gasification then proceeded under a forward combustion mode.
Approximately three months after air injection was halted,
combustion was extinguished by natural influx of seam water
(L-327, L-6631, L-8580).
A complete history of gas production rate, air injection
rate and Btu value of produced gas is available in the literature
(L-8520, L-327, L-748, L-6631). Combustion was maintained con-
tinuously over the entire test period. From mid-September through
-50-
-------
(A) IGNITION IN WELL NO. 3 (B) LINKAGE AND
GASIFICATION
OF WELL 5-3 PATH
(C) SIMULTANEOUS LINKAGE
AND GASIFICATION OF
WELL 9-3 AND 3-15 PATHS
(D) LINKAGE AND GASIFICATION (E) ESTIMATED AREA AFFECTED
OF WELL 12-5 PATH IN HANNA NO. 1 EXPERIMENT
Figure A-3.
SEQUENCE OF LINKAGE IN THE HANNA #1 EXPERIMENT
(Source: L-6631)
-51-
-------
February 1974, gas production rates and gas heating values
stabilized; gas production averaged 4.2x10^ Nm3/day (1.6xl06
scf/day). The average gas heating value was 5.12xl06 J/Nm3
(126 Btu/scf). This is equivalent to one MW of electricity
at a 4070 conversion (thermal) efficiency. A typical analysis
of the gas produced is presented in Table A-2. Material balance
calculations indicated no gas leakage from the reaction zone,
significant influx of groundwater to the reaction zone, con-
sumption of approximately 20 tons of moisture-free coal per day
during the stable 5%-month period, and a 63 percent resource
utilization. Energy balance calculations indicated that about
3.5 times more energy was produced than consumed during the
experiment.
In general the results of the Hanna I experiment showed
that groundwater influx and gas leakage can be controlled by
air injection pressure. Relatively constant gas production
rates and gas heating values were maintained and directional
control of the combustion front movement was achieved during the
reverse combustion mode. Considerations not addressed in the
first test were prevention of roof collapse, maximization of
coal utilization, measurement of temperatures within the com-
bustion zone, location of the combustion zone as a function of
time, and overall process control (L-1436, L-6631).
Hanna II - The Hanna II test program was a more closely
monitored operation which was designed to take advantage of
the natural permeability of the coal seam while applying informa-
tion gained from Hanna I. This experiment was carried out at a
location about 240m (800 ft) west of the Hanna I site. The coal
seam thickness was the same but it is much closer to the surface
at this location (85m or 275 ft compared to 120m or 400 ft at
Hanna I). The layout of the four principal wells is shown in
-52-
-------
Table 4-2. TYPICAL COMPOSITION OF DRY GAS PRODUCED
IN UNDERGROUND COAL GASIFICATION EXPERIMENT, HANNA I
Constituent Mole percent
H2 15.96
Argon 0.76
N2 53.18
C1U 3.91
CO 6.33
C2H5 0.39
C02 19.22
C3H8 0.13
C3H6 0.04
i-CMlx,, 0.01
H2S 0.07
Heating Value 5.04x106 J/Nm3 (124 Btu/scf)
Source: L-1382, L-4822
-53-
-------
Figure A-4. Stratigraphic correlation of core sample data
from these wells indicates a distinct heterogeneity of the seam
over distances as short as 18m or 60 ft, thus making modeling
of fluid flow in such a complex system very difficult (L-8552,
L-6631).
The objectives of Phase I were to evaluate coal seam
permeability, investigate pneumatic linking and linking via
reverse combustion, and sustain gasification between the two
linked vertical wells (L-4674, L-8552). Extensive in-situ
and surface instrumentation was installed to provide data needed
for further understanding of the process. This phase was
conducted from April through August of 1975. The following
results were obtained:
Control of reverse combustion linkage was
demonstrated.
The preferred flow direction was updip and
along the general direction of geological
fracturing.
Completion of the wells near the bottom of
the seam resulted in placement of the link
in the bottom half of the seam, thus prevent-
ing passing over the top of unreacted coal
(overriding).
Air injection rate could be reduced by a
factor of 10 with only a 20 percent reduction
in Btu-value. Less than a 6-hour response
time was necessary to return the system to
full operating conditions.
-54-
-------
N60W
S6OW
0
10 20 30 40 feet
H
S20W
Figure A-4. WELL PATTERN; PHASE 1 OF THE HANNA II EXPERIMENT
Source: L-4674
-55-
-------
Table A-3 gives the overall average composition of product gas
from Phase I. A tabulated summary of additional results from
Phase I and later phases of Hanna II is presented in Table A-4.
Table A-3. OVERALL AVERAGE COMPOSITION OF PRODUCT GAS
FROM HANNA II, PHASE I
Component
H2
CO
C02
CH4
Vol 7=
17.3
14.7
12.4
3.3
Component
N2
Ar
H2S
C2 -C4
Vol %
51.0
0.6
0.1
0.6
Source: L-4674
During the experiments, two flares were available
for disposal of the low-Btu gas produced, both located approxi-
mately 10m (100 yards) from the well site. The small flare had
capacity for 2 m3/sec (4000 cf/min) of production gas for use
during the linkage phase and low-flow gasification experiments.
The large flare had capacity for ^6 m3/sec (12,000 cf/min)
of production gas for use during high-flow gasification. Only
the large flare was equipped with sample ports for sampling
of the discharge. Both flares were equipped with forced draft
combustion air blowers (L-8300).
Phases II and III of Hanna were designed as four-well
experiments as shown in Figure A-5. Wells 5,6,7 and 8 were
drilled 18m (60 ft) apart in a square pattern. Wells desig-
nated by letters were instrument wells, the details of which are
summarized in Table A-5. Phase II, completed in May 1976,
involved the following steps:
-56-
-------
Table A-4. SUMMARY OF HANNA II RESULTS
Phase
II
III
Duration
6/4-7/11/75
5/4-31/76 6/24-7/31/76
Well spacing
m (ft)
16
(52.5)
18.3
(60)
18.3
(60)
Coal consumption 1140
MT in place (tons) (1260)
1890
(2080)
3100
(3420)
Average heating value 6.18
106 J/NM3 (Btu/scf) (152)
6.97
(171.4)
5.60
(137.8)
Total air injected
10s Nm3 (10* scf)
1.87
(72.2)
2.81
(108.4)
5.47
(210.7)
Total dry gas produced 2.66
106 Nm3 (105 scf) (102.5)
4.47
(172.3)
7.92
(305.4)
Energy Return Ratio
5.2
4.5
4.5
Cold gas thermal
efficiency
0.83
0.89
0.77
Overall process
efficiency
0.72
0.74
0.65
Source: L-9170
-57.
-------
6si
6
A
<
B^
L,
}
D 5
S . n t
i
I
Ln
OO
I
H
-O
I
-o-
L
O
8
J
-O
K
-o—
M
O
o
KEY
INJECTION/PRODUCTION
WELLS
INSTRUMENTATION
WELLS
TRUE
NORTH
10
2O
30fe«l
N
Figure A-5.
WELL PATTERN FOR HANNA II, PHASES II AND III
(Source: L-9118)
-------
Ul
VO
I
Table A-5. SUMMARY OF INSTRUMENTATION FIELDED FOR PHASES II AND III OF
THE HANNA II UNDERGROUND COAL GASIFICATION EXPERIMENT
Instrumentation Well
Low Temperature Levels
High Temperature Levels 2
Resistivity Probes3
Geophones
Gas Sampling Canisters
Oownhole Pressure Transducers
Surface Pressure Transducers
Tilt Meters
Displacement Levels
A B
10 9
3
3 3
10 10
1
1
2
Plus Surface
C D E
10 10 8
3 3
3 3 3"
10 10 10
111
1
111
2
4 4
F
9
3
3"
10
1
'1
1
2
G H I J K L
9 10 10 10 10 10
333333
10s 10 10 10 10 10
1 11
1
1 11
2222
4
: Geophone Array (20 ft depth)
Resistivity Probe Array
M N 0 Total
10 7 9 141
12
333 48
10 10 10 150
1 9
3
1 9
14
12
398
15
81
TOTAL A 94
1 Up to six-fold redundancy at most levels plus resistance and noise measurements greatly increase the total number of thermal
channels available.
2 Different materials fielded for evaluation.
3 Three probes also fielded in shot-veil, SI
High-temperature sensors and cables fielded in these wells.
5 Different geophone spacing to measure vertical attenuation.
Source: L-S552
-------
Linkage of Wells 7 and .8 by reverse com-
bustion with ignition at Well 7.
Linkage of Wells 5 and 6 by reverse com-
bustion with ignition at Well 5.
Gasification in the forward direction
between Wells 5 and 6 with injection at
Well 6, utilizing three different in-
jection rates 0.74, 1.08, 1.1. Nm3/sec
or (1700, 2500, 3500 scf/min).
The results of this phase showed that a linkage path in a narrow
channel could be placed at the bottom of the coal seam. At
the midpoint of the 5-6 gasification line there were indications
that the reaction front could have been as wide as 18.3 m (60
ft) . Results of this 27-day gasification tfest are summarized
in Table A-4. During the planned changes in injection rates no
dramatic change in either the gas composition or the heating
value occurred. The improved gas quality and resource utiliza-
tion was attributed to the higher injection rates used and the
use of backpressure on the system to maintain the proper air/
water ratio.
During Phase III, the line drive portion of Hanna II,
the following steps were planned:
Simultaneous injection into Wells 7 and 8 to
achieve a broad reverse combustion linkage
between the 5-6 pathway and the 7-8 pathway.
Gasification of the area encompassed by the
four wells by injection into 7 and 8 utilizing
5 and 6 as the production wells.
-60-
-------
The attempt to create a broad linkage pathway, however, was
unsuccessful. Instead, a narrow link formed close to the line
between Wells 6 and 8. Phase III was therefore modified to
another two-well burn from 8 to 7 which was completed on July 30,
1976. These results are also summarized in Table A-4. The most
significant difference between the results of Phases II and III
was the effect of excess water during Phase III. Excess water
greatly lowered the heating value of the product gas and the
thermal efficiency of the gasification process (L-8552).
The overall accomplishments of the Hanna II experiment
can be summarized as follows(L-9118, L-9170):
Highest gross heating value over the longest
duration ever reported
Highest thermal efficiencies ever reported
High overall sweep efficiency for parallel
two-well gasification systems
• Most thoroughly instrumented UCG test ever
conducted
Highest production rates from any UCG test
in the free world
No measurable gas leakage from the reaction
zone during gasification
First monitoring of product gas stream for
trace components.
-61-
-------
In summary, the results of eight different reverse
combustion linkages at Hanna indicated that "subbituminous coal
is ideally suited to reverse combustion linkage both from a
controllability standpoint and the quantity of air needed to
complete a linkage" (L-8555). Great improvements in the control
of gas quality and production rate were achieved during the
progressive gasification stages.
Hanna III - The third Hanna test will be conducted
during the third quarter of FY 77 at a site approximately 210 m
(700 ft) west of the Hanna II site. Site preparation work is
now in progress. The primary objective will be to determine the
impacts of in-situ gasification on water quality. The well
pattern to be used, illustrated in Figure. A-6, consists of two
process wells on an 18 m (60 ft) spacing and ten water monitoring
wells. The coal seam aquifer and any overlying aquifers will be
monitored prior to and following the gasification test for a
minimum of 18 months. Baseline water quality, flow direction,
flow rate, storage coefficients and transmissivity for the
aquifers will be established (L-9118).
Additional objectives for Hanna ill include demonstrat-
ing the feasibility of computer monitoring for process control
and demonstrating the stability of product gas composition by
maintaining a constant air/water ratio.
Hanna IV - Plans have been finalized for Hanna IV. The
objectives are outlined below (L-9170) :
Determine relationships between injection
rate, well separation and sweep width
Determine feasibility of linking over distances
of 30 and 45 m (100 and 150 ft)
-62-
-------
o
MAJOR /
FRACTURE
DIRECTION
I
DIRECTION
OF WATER
MOVEMENT
6\
8 "^02'
10
12
INJECTION OR
PRODUCTION WELL
WELL COMPLETED
INTO OVERLYING
AQUIFER
WELL COMPLETED
INTO COAL SEAM
O
14
Figure A-6. HANNA III WELL PATTERN
(Source: L-9170)
-63-
-------
Define void shape and gasification front
inclination as a function of time
Demonstrate relaying process from one 2-well
system to another
Determine pressure and gas composition
gradients within the seam as a function of
time
Monitor product gas for trace components
over total test life
The test setup will consist of 3 wells at 30 and 45m (100 and 150
ft) spacings between pairs (L-9118).
Hanna V - The Hanna V test as presently planned
will consist of nine wells in three rows of three wells each.
This experiment will be of longer duration (12 months) with
production rates up to 2.3xl06 Nm3/day (9.0xl07 scf/day).
Gas turbine and gas cleanup testing may also be conducted. A
summary of the objectives for this test is as follows (L-9170) :
Demonstrate simultaneous operation of multi-
well pattern
Determine impacts of subsidence on process
Demonstrate process control with no downhole
instrumentation
Demonstrate feasibility of product gas cleanup
and utilization
-64-
-------
Obtain design information for scale-up to
demonstration plant
Obtain final test information for economic
analyses
Water Quality Studies
An investigation of potential groundwater pollutants
produced during in-situ gasification is underway by researchers
at the Laramie Energy Research Center. Coal tars which are
generated during gasification processes are known to contain
phenols, pyridines, anilines, quinolines and aromatic hydrocarbons.
All but the phenols are relatively insoluble in groundwater. Coal
itself may sorb some soluble organic components. These phenomena
may minimize dispersion of organic contaminants and thereby limit
their impact. On the other hand, inorganic residues in the ash
or char may be more accessible for dissolution in the groundwater
system (L-8520).
To date most characterization work has been carried out
on coal tar condensate samples collected during the Hanna I exper-
iment (L-748). The two-phase condensate consists of approximately
90 percent water and the remaining 10 percent an organic coal tar
layer. The total sample was collected in an air-cooled condenser
upstream of the product gas flare. Two samples representing
different reaction conditions were taken for characterization:
one during a period of low gas production associated with carbon-
ization (linkage phase) and the second during a high gas produc-
tion period associated with gasification. The organic (tar)
fractions were subjected to fractionalization schemes and subse-
quent analyses.
-65-
-------
Many coal tar samples collected during numerous gasifi-
cation tests at Hanna have been physically characterized. The
results for three selected parameters for samples collected
during gasification and carbonization periods are presented
below (L-748).
Sample 1 Sample 2
(carbonization)(gasification)
Specific gravity at 15°C (60°F) 0.962 0.977
Viscosity at 38°C (100°F) m2/sec 3.55x10"" 1.316xlO~3
Heat of combustion, J/g 3.7383xl07 4.0134xl07
(Btu/lb) (16,073) (17,256)
In general, chemical characterization of the coal tar
samples investigated indicate that tars generated during in-situ
gasification differ from those produced during conventional
coking operations, primarily in their lack of heavy ends (L-8580)
Simulated distillations of the coal tar sample collected during
the Hanna I test indicated that none of the material boils above
510aC (950°F) compared to 24 weight percent of a tar produced
under laboratory carbonization conditions boiling above 538°C
(1000°F). The likely explanation for this is that the higher
boiling components of UCG coal tar are separated out during
their passage through the coal seam to the surface (L-8580).
A typical elemental analysis of a UCG coal tar is
presented in Table A-6. In general the composition of tars
has been found to remain relatively constant during a given test
at Hanna and from test to test as well. Maximum values measured
for nitrogen and sulfur are 1 and 0.5 percent, respectively
(L-8580).
-66-
-------
Table A-6. TYPICAL ELEMENTAL ANALYSIS OF COAL TAR
Element
C
H
N
S
0*
Weight percent
86.33
10.43
0.79
0.18
2.27
* Percentage determined by difference.
Source: L-8580
Strong, weak and very weak bases are defined by their
half neutralization potential (HNP). Very strong bases have an
HNP less than 150 mV, while HNP's of weak bases such as pyridines
and quinolines range between 150 and 350 mV. Very weak bases
have an HNP greater than 350 mV; examples of these are amides.
Primary and secondary anilines will also titrate as very weak
bases since they undergo acetylation to amides. Nonaqueous
titration of the Hanna I samples produced results shown in Table
A-7. Results of total sulfur and total nitrogen titrations are
also available in this table.
The intial separation scheme based on mineral acid and
sodium hydroxide extractions followed by regeneration via pH
adjustment yields three major fractions (L-748):
Tar acids
Tar bases
Neutral oil fraction
-67-
-------
Table A-7. TOTAL NITROGEN, TOTAL SULFUR AND TITRATABLE
NITROGEN FOR ACID, BASE AND NEUTRAL FRACTIONS OF UCG COAL TAR
Total sulfur Total nitrogen
Titratable nitrogen*
Carbonization Sample
Tar base
Tar acid
Neutral
Gasification Sample
Tar base
Tar acid
Neutral
0.00
0.33
0.02
0.23
0.14
0.20
9.64
0.35
0.08
4.82
0.09
0.37
8.10% WB, 1.
0.264% WB, .
0.035% VWB
4.45% WB, 0.
0.058% VWB
0.37% WB, 0.
35% VWB
081% VWB
,
36% VWB
145% VWB
* WB and VWB refer to weak and very weak base.
Source: L-748
A slightly modified scheme was described in a later paper (L-8580)
The neutral fraction is subsequently separated with aliphatic and
aromatic fractions with silica gel, using hexane to elute the
aliphatics and methanol the aromatics (L-8580).
The compositional ranges given in Table A-8 were
obtained upon fractionalization of numerous tar samples. It was
pointed out that the 70:30 ratio of aromatic to aliphatic content
of the neutrals fraction was fairly constant over a wide range of
samples. The higher oxygen content of the carbonization sample
is due to the greater level of tar acids (substituted phenols)
present. Results of characterization of the tar base fraction
were presented in one paper (L-748), while the weak acids and
aliphatics are the subjects of a paper to be presented in the
near future (L-8580). These results are summarized below.
-68-
-------
Table A-8. COMPOSITIONAL RANGES OF UCG COAL TARS
Composition, wt. percent
Fraction Gasification sample Carbonization sample _
Tar bases 2.5-8.0 4.0
Tar acids: 42.1
Strong acids 0.1-1
Weak acids 12-31
Neutrals* 55-77 53.9
* Percentage ratio of aromatics to aliphatics usually constant 70:30.
Source: L-8580
Characterization of Weak Acids - The weak acid fraction
of the Hanna I sample (14.5 weight percent weak acids) was found
p
to be almost exclusively phenolic in nature. Specific compounds
identified by GC-MS include:
phenol
p-cresol
o-cresol
m-cresol
4 different xylenols
7 C3-phenols
5 C^-phenols
Small amount of aromatic aldehyde or ketone
In addition, H1 and C13 NMR analyses of manually trapped GLC
peaks supported the GC-MS results.
Characterization of Aliphatic Neutrals - This
fraction contains a normal saturate series running from Ci0 to
-69-
-------
C32 with some branched saturates and a particularly heavy level
of Ci9 branched saturates. Very limited degrees of unsaturation
or cyclic compounds were evident. Specific components identified
by GC-MS are listed in Table A-9.
Table A-9. COMPOSITION OF ALIPHATICS
FRACTION OF HANNA I COAL TAR SAMPLE
n-Cio through n-Caa series
Branched saturates:
2,11-dimethyl tridecane (Cis-H32)
2-methyl tetradecane (CisHsz)
4,11-dimethyl pentadecane (C17H36)
6-methyl octadecane (C^H^o)
7-methyl octadecane (CigHi+o)
3-methyl octadecane (CigH^o )
3,6-dimethyl heptadecane (Ci9Hil0)
two polybranched CigHi+o
2,4-dimethyl octadecane (020^2)
Source: L-8580
Characterization of Tar Base Fraction - GLC traces for
the tar base fractions of both Hanna samples were presented in
the literature. Identification of the peaks from the carboniza-
tion base was made with the aid of NMR, MS, UV and GLC data.
The results tabulated in Table A-10 show that 46.6 percent of
the base fraction was substituted pyridines, 13.4 percent anilines,
and 9.1 percent quinolines. Most of the remainder was thought to
be substituted pyridines.
-70-
-------
Table A-10. TABULATED SPECTRA ON SEPARATED COMPONENTS
FROM TAR BASE FRACTION OF HANNA CARBONIZATION SAMPLE
t
Component r '"
1 8.9
2 11.0
3 13.1
4 14,9
5 17.3
6 18.3
7 19.2
8 31.1
9 34.7
10 38.1
11 39.1
12 40.5
% Total
of base
fraction
1.18
6.40
6.20
9.61
12.90
3.22
7.11
5.98
4.88
2.54
4.08
5.02
Compound type
or compound
pyridine
2-picoline
2 , 6-lutidine
3-picoline ,
4-picoline
and 2-ethyl
pyridine
2 , 4-lutidine ,
2,5-lutidine plus
some methyl ethyl
pyridine
2, 3-lutidine
trimethyl
pyridine and an
ethyl pyridine
aniline
2 -methyl aniline
a dimethyl aniline
and an ethyl aniline
quinoline, a
dimethyl aniline
and a trimethyl
aniline
a methyl quinoline,
a C3 aniline;
quinoline, a
dime thy 1 quino 1 in e
* GLC retention times are relative to air.
Source: L-748
-71-
-------
Analysis of the Hanna gasification base sample produced
similar results except that the majority of the fraction was
heavier than the carbonization sample.
The aqueous fraction of the original condensate samples
and some additional water samples from the site tests are currently
being analyzed by the Research Triangle Institute. These results
are not yet available.
Future water quality studies are planned as an integral
part of the Hanna III experiment. To date, no general conclusions
have been reached regarding the impact of in-situ gasification on
water quality.
Air Quality Studies at Hanna
Product gas and flare discharge resulting from product
gas combustion were characterized during Phase II of the Hanna II
test of the Linked Vertical Well concept from 19 April through 17
May 1976 (L-85.54, L-8300) . The product gas was monitored over
seven different periods under three different conditions of air
injection rate. During each of these periods the product gas was
characterized with respect to particulate concentration; size
distribution and composition; four minor gas components -- carbon
disulfide, carbonyl sulfide, ammonia and hydrogen cyanide; and
vapor phase concentrations of ten elements -- sodium, potassium,
lithium, calcium, vanadium, mercury, arsenic, lead, selenium and
cadmium. Two monitoring periods were performed for the flare
discharge during which the discharge gas was characterized with
respect to particulate concentration and size distribution,
sulfur oxides, nitrogen oxides and total hydrocarbons. Details
of this study are available in a recently published report by
Radian Corporation (L-8300).
-72-
-------
The particulate size distribution of the production gas
was determined with Andersen cascade impactor samplers. In
general, a trend is evident from the data indicating an increase
in total particulate loading and a shift toward larger size
particles as the burn progresses. The increase in particulate
concentration is particularly apparent between the first three
periods when the injection rate was ^0.74 Nm3/sec (1700 scf/min)
and at the higher injection rates. From the data available, it
is not evident whether this increase is the result of increasing
gas velocities in the system as injection flow was increased or
a result of decreasing distance from the combustion zone to the
production well. One abnormally high particulate loading was
measured on one of the sampling days. The origin of the pheno-
menon was not known.
Particulate matter entrained in the product gas stream
was collected for characterization during each sampling period
using a heated cyclone-filter assembly. Materials were also
recovered from the extension pipe on the product*gas sampling
assembly following the final period. This material formed two
samples: "large wellhead particulates" which consisted of loose
material in the pipe which resembled unreacted coal in appearance
and "wellhead scrapings" which were removed from the interior
wall of the extension pipe and appeared to be condensed coal tars
and adhered fine particulates. Particulate samples were charac-
terized by analysis of major components, semiquantitative spark
source-mass spectrometry survey analysis, oil and tar content by
extraction with Freon, ash content and determination of bulk
density.
The results of analyses of four particulate samples for
nine major elemental components after extraction of condensed
oils and tars are listed in Table A-11. This list includes the
-73-
-------
Table A-ll. CONCENTRATIONS OF MAJOR COMPONENTS IN WELLHEAD PARTICULATES1
-p-
I
Element
Na
K
Li
Ca
Mg
Al
Fe
Ti
Si
Oils & tars2
Large wellhead
particulates
.162
.428
-
3.38
.408
4.85
1.46
.182
10.4*
1.67
Wellhead
scrapings
.131
.320
-
1.24
.588 •
3.56
2.26
.064
7.04
13.2
Cyclone
particulates
Run 3
5/5/76 (126)
.102
.031
22 . 1 ppm
3.00
.131
.420
3.38
.170
1.79
5.3
Cyclone
particulates
Run 7
5/16/76 (136)
.178
.270
36.8 ppm
.880
.780
3.34
1.75
.201
6.10
1.00
Concentrations expressed as percent in participate following Freon extraction
unless specified otherwise.
2 Determined by loss with Freon extraction.
Source: L-8300
-------
elements whose oxides are the major constituents of coal ash.
In Table A-12 the concentrations are shown following mathema-
tical conversion to the oxide forms, as is commonly done in
mineral analyses of coal ash, and correction for the weight of
extracted oils and tars. The total oxides content should approx-
imately equal the ash content of the particulates. As a check,
the ash content of the "large wellhead particulates" and the
"wellhead scrapings" was determined by combustion. The carbon,
hydrogen and oxygen contents were also determined providing
analyses of essentially all of the major particulate components.
The deviation of the sum of all of these major components from
100% is a measure of the overall accuracy of the analyses.
The concentrations of four gas components (ammonia,
hydrogen cyanide, carbonyl sulfide and carbon disulfide) in the
product gas were determined during each of the seven complete
sampling peeriods. The results of these determinations are
presented in Table A-13. During collection of the samples for
determination of these components, significant quantities of con-
densed oils and tars were trapped in the impinger solutions.
Checks for interferences from these condensates in the analyses
were made. Details are available in the study report.
The vapor phase concentrations of ten elements in the
product gas were also determined-via analysis of acidic and basic
impinger solutions. The results are presented in Table A-14.
The discharge gas from the flare was characterized on
two different sampling days. Tables A-15 and A-16 provide the
results of the characterization for particulate concentration
size distribution, and concentrations of SOz, NOX, total hydro-
carbons and maj or components.
-75-
-------
Table A-12. COMPOSITION OF WELLHEAD PARTICIPATES
cr.
i
Cyclone particulates , %
Large wellhead Wellhead Run 3 Run 5
particulates, %, scrapings, % 5/5/76 (126) 5/11/76 (131)
Na20
K20
Li20
CaO
MgO
A1203
Fe203
Ti02
Si02
Total oxides*
C
H
0
Ash
Total ash +
CEO
.21
.516
-
4.72
.676
10.3
2.09
.303
22.24
40.38
41.95
3.29
12.42
43.7
101.4
.176
.386
-
1.73
.975
7.56
3.23
.107
15.06
25.38
55.69
4.71
13.67
24.3
98.4
.137
.037
-
4.19
.217
.89
4.83
.284
3.83
13.66
78.72 60.33
6.47 1.01
7.87 2.62
106.72
Run 7
5/15/76 (136)
.240
.325
-
1.23
1.29
7.10
2.50
.335
13.05
25.81
58.06
3.26
11.08
98.21
* Percent values corrected to pre-extracted weights.
Total oxides should approximately equal ash content.
Source: L-8300
-------
Table A-13. AMMONIA, HYDROGEN CYANIDE, CARBONYL SULFIDE AND
CARBON DISULFIDE-CONCENTRATIONS* IN THE PRODUCTION GAS
Run
1
2
3
4
5
6
7
Date
4/26
5/2
5/4
5/8
5/10
5/13
5/15
(days)
(117)
(123)
(125)
(129)
(131)
(134)
(136)
NH3
0
0
0
0
0
0
0
.22
.13
.14
.21
.28
.18
.14
HCN
ppm
<1.2
1.0
10.0
9.4
0.17
6.9
0.43
COS
ppm
1
3
2
1
0
1
1
.1
.0
.8
.7
.57
.5
.1
CS2
ppm
1
4
2
9
9
7
8
.1
.7
.2
.0
.8
.4
.9
* All concentrations are v/v on a'dry gas basis.
Source: L-8300
-------
Table A-14. VAPOR PHASE ELEMENTAL CONCENTRATIONS" IN UCG PRODUCTION GAS
00
I
Sampling period and date
Element
Na
K
Li
Ca
V
Hg
Pb
Cd
As
Se
#1
4/26
4.00
.175
<.06
.39
.083
±
.039
.00092
.0100
.0325
n
5/2
.92
.164
<.06
.43
.034
.0099
.012
.00054
.0066
.0355
#3
5/4
3.97
.098
<.06
.84
.097
.0035
.030
.00047
.0117
.0137
#4
5/8
12.9
.037
<.06
.48
.071
.0105
.033
.00022
.036
.0101
#5
5/10 .
.49
.121
<.06
.80
.064
.0102
.021
.000089
.088
.0186
#6
5/13
4.35
.048
<.06
.42
.063
.0048
.016
.000083
.075
.0156
#7
5/15
<.05
<.02
<.06
.37
.064
.0056
.011
.00040
.029
.0169
* All concentrations ppm (v/v) on a moisture-free basis.
±
Insufficient data.
Source: L-8300
-------
Table A-15. PARTICULATE CONCENTRATION AND
DISTRIBUTION IN FLARE DISCHARGE GAS
Size
range,
y
>.10
10-7.0
7.0-5.0
5.0-3.0
3.0-1.0
1.0-0.75
0.75-0.50
<0.50
TOTAL
Particulate concentration
g/103 Nm3
May 6
6.52
2.35
2.65
1.95
2.85
1.45
1.80
19.48
39.05
May 7
2.55
1.72
1.42
2.25
5.72
2.07
3.22
23.36
42.31
Source: L-8300
Table A-16. COMPOSITION OF FLARE DISCHARGE GAS
Concentration*
Component
Total Hydrocarbons
Sulfur Dioxide
Nitrogen Oxides
Hydrogen
Nitrogen
Oxygen
Argon
Carbon Monoxide
Methane
Carbon Dioxide
C2 - CT
* All concentrations are
Source: L-8300
May 6
1480 ppm
425 ppm
370 ppm
280 ppm
76.53%
2 . 147=
1.007=
3 . 48%
1250 ppm
16.537=
620 pom
on v/v dry gas basis .
May 7
920 ppm
554 ppm
353 ppm
220 ppm
77.517o
4.697=
0.997=
2 . 427=
810 ppm
14.02%
30 m)m
-79-
-------
Atmospheric emissions from an in-situ gasification
module and other energy conversion processes were estimated in
another Radian study (L-5480). The basis of the model was as
follows:
105 Nm3/day (4xl06 scf/day)
1012 J/day (109 Btu/day)
107 J/Nm3 (250 Btu/scf)
The only gas treatment assumed was separation of coal tar products
It was anticipated that the only significant emissions from in-
situ gasification would be from high-pressure equipment and
vehicle traffic around the surface facilities.
An emission factor for fugitive emissions from high-
pressure equipment could not be derived from Hanna data because •
of large leakages due to inadequate well seals at the time the
data were reported. Therefore a total environmental emission of
0.22 volume percent of fuel gas produced (based on a previously
reported value for miscellaneous hydrocarbon emissions from gas
wells) was assumed. Applying this to an available fuel gas
analysis the following fugitive emission rates were derived:
Carbon monoxide 13.6 kg/day (30.0 Ib/day)
Hydrocarbons (CFU) 29.5 kg/day (65.0 Ib/day)
The emission rate for particulates of 2.5 kg/day
(5.5 Ib/day) represents fugitive dust from vehicular traffic
based on 8 km (5 miles) of unpaved roads with 80 vehicle-kilo-
meters (50 vehicle-miles) daily.
-80-
-------
APPENDIX B
-------
ERDA/LLL IN-SITU COAL GASIFICATION PROGRAM
The Lawrence Livermore Laboratory in-situ gasification
program was initiated in 1972. Initial funding was provided by
the U. S. Atomic Energy Commission during 1972 and 1973. Ongoing
work is continuing under ERDA sponsorship (Contract No. W-7405-
Eng-48). The LLL process is based on an underground packed-bed
reactor model and is applicable to the production of pipeline-
quality gas from thick (i.e., 15 meters) seams 150-1000 meters
deep. LLL's approach involves:
• Development of mathematical models of reaction
chamber kinetics
• Bench-scale testing
• Small-scale explosive fracturing tests at
Kemmerer, Wyoming
.• Larger scale field tests at the Hoe Creek site
near Gillette, Wyoming
The current development status of the project has been
described as still little more than conceptual. Application
has been made to the Bureau of Land Management for a Special Land
Use Permit to conduct UCG experiments on an 80-acre tract of
public land. Under a previous permit, LLL carried out extensive
drilling and geological and hydrogeological testing. The goals
and current status of the LLL test work are presented in more
detail below (L-8544).
In conjunction with this project two different feasi-
bility studies were sponsored by ERDA and LLL. Gulf Research and
Development Company and a consortium of companies headed by
-82-
-------
Resource Sciences Corporation has evaluated the commercial
potential of the LLL packed-bed concept, examined coal availabil-
ity, and recommended an R&D program leading to a demonstration
of the process. The conclusions of both studies were favorable.
Namely, more than 100 billion tons of deep, thick, western coal
are available; the cost of the resulting pipeline-quality gas
would be 60-70 percent of that produced by Lurgi technology,
assuming a reasonable sweep efficiency (70 percent) and moderate
explosive requirements. It was also concluded that less severe
environmental consequences would result from LLL's process.
LLL Process Description
The basic features of LLL's underground packed-bed
reactor process are (L-8581):
Drilling and explosive fracturing of the coal
Dewatering
*
Igniting the top of the permeable fractured area
Gasification in a downward direction via injec-
tion of steam and oxygen
Surface cleanup and upgrading of the raw gas
to high-Btu, pipeline-quality gas
The concept is illustrated in Figure B-l for a model
site. A block diagram is presented in Figure B-2 showing the
basic units proposed in the process. Gas purification modules
are shown although optimistic reports state that not all of
these modules will be needed if sulfur removal and methanation
are maximized underground (L-1326).
-83-
-------
PIPELINE GAS
C02
GAS PRODUCTION WELLS
OXYGEN PLANT
GAS
PURIFICATION
PLANT
WATER PLANT
WATER WELLS
INJECTION WELLS
REACTION ZONE
Figure B-l.
LLL IN-SITU COAL GASIFICATION CONCEPT
(Source: L-8558)
-84-
-------
OO
m
I
BRACKISH
WATER
WELLS
RECYCLE WATER
i
N2
WATER
PLANT
iOOO HTFD
1
'
OXYGEN
PLANT
4267 MTPD
IN-SITU
GASIFICATION
C02
- I
TAR AND SHIFT METHANATINC, PIPELINE
REMOVAL CONVERSION COMPRESSION GAS
1 7.8 x J0£ Kaf/a
' (274 x 10* acf/ai
BY-PRODUCT/ „,„ 90 ml ,
WASTE TAR SULFUR Inert.-,- 10 tool S
PLANT
(
SULFUR
Figure B-2: BLOCK DIAGRAM OF LLL IN-SITU COAL GASIFICATION PROCESS
(Source: L-8558, L-683)
-------
Fracturing - Fracturing is accomplished by means of
conventional explosives detonated in an array of drilled holes.
Injection and collection wells are then drilled and cased to
prevent water intrusion. The collection wells are drilled to
the bottom of the reaction zone while the injection wells reach
just to the top (L-1326).
Dewatering - Prior to and during gasification, dewater-
ing operations are necessary to remove and then to prevent re-entry
of groundwater into the reaction zone. Plans for this operation
are not yet definite; however, it appears that this water may
be suitable even for livestock use; arrangements were made with
a nearby ranch to pipe pregasification water from the first Hoe
Creek experiment overland to a stock pond. Water pumped out
during gasification will be monitored for possible contaminants
(phenols, inorganics, e.g.) and, if necessary, reinjected into
the Felix coal formation.
Ignition - In the LLL process the coal at the top of
the seam is ignited by injection of oxygen (L-8558).
t
Gasification - After good combustion is established,
oxygen and steam or brackish water is injected. Gasification
occurs in a downward direction under operating pressures ranging
from 3.5 to 7 MPa (500-1000 psi). This direction reportedly
provides more stable conditions because rapid reactions which take
place in hot spots are slowed by the buoyancy of the hot gases.
The product gas is withdrawn by collection wells drilled to the
bottom of the zone. It is desirable to confine the gasification
process to specific zones, leaving some coal between zones for
support (L-683).
Under oxygen-blown conditions, the product gas is
expected to contain principally methane and CO with lesser amounts
-86-
-------
of COa and Hz; HzS will also be present to some extent, A
comparison of expected gas compositions from Hoe Creek Test 1
(air) and later tests with oxygen is presented in Table B-l.
After gas purification, Figure B-2, the methane content may be
as high as 907o. Since the LLL process is aimed at high-Btu gas
production, maximum in- situ methanation is desirable. At temper
atures above 800°C methanation is equilibrium- limited. At lower
temperatures the uncatalyzed reaction proceeds slowly. It is
anticipated that methanation will approach completion because
of the following factors :
High pressure
Long gas residence time in the high- temperature
reaction zone (^1 hour)
Catalytic action of ash and shale
Laboratory data have reportedly yielded supporting evidence. A
potential problem may exist, however, due to difficulties in
obtaining adequate temperature control because of either in-situ
or injected water (L-8558, L-683) .
Surface Processing - Since it is anticipated that sulfur
cleanup will be accomplished in situ via chemical action of shale,
no above-ground sulfur removal facilities are planned. This
seems optimistic, however, when considering that 97 percent
underground sulfur removal must be achieved in order to meet
proposed new source performance standards for fossil fuel con-
version facilities, assuming 1 percent sulfur content in the
coal (L-683). Other surface facility requirements may include
oxygen and steam plants and possibly water treatment units.
-87-
-------
Table B-l
GAS COMPOSITIONS EXPECTED FROM HOE CREEK EXPERIMENTS
NOS. I (AIR-BLOWN) and 2 (OXYGEN-BLOWN)
Gas
Test component
Gas Composition H2
CO
CO 2
ou
H2S2
•N2
Heating Value
Volume, %
(water-free basis)
air-blown
16-17
21-23
5-7
1.5-2.5
<0.1
56-5-50.4
5.3xl06 J/Nm3
(130 Btu/scf)
oxygen-blown1
19.2
32.4
20.4
27.0
0.5
0.5
3. 8x10 7 J/Nm3
(945 Btu/scf)
Composition corresponds to gases in equilibrium at ^325°C and a pressure
of 7,1 MPa (70 atm) and is somewhat higher in CHi+ than Lurgi gasifier
products.
2.
This is a maximum value and assumes all the sulfur in the coal to be
released in the form of
Source: L-8581, L-8582, L-1326
-88-
-------
Scope of Work and Project Status
The LLL project involves theoretical, laboratory and
field studies. Field studies are being conducted at both the
Kemmerer and Gillette, Wyoming, sites. The status in each of
these areas is presented below. The main thrust of the environ-
mental assessment studies conducted to date has involved modeling
and laboratory studies.
Fundamental Laboratory Studies -
Bench-scale and coal gasification experiments have been
conducted in 0.3- and 1.5-m (1- and 5-ft) long packed-bed reactors
using steam and oxygen reactants. The gas quality achieved is
comparable to that produced in Lurgi gasification processes (L-8558)
9
Laboratory studies have also been performed to measure
the progress of thermal waves. The results were compared to
modeling predictions. It was found that Wyoming subbituminous
coals shrink upon heating and their permeabilities increase by
several orders of magnitude (L-8581).
Water Quality Studies -
LLL's approach to groundwater pollution assessment
involves development of a pollutant transport and dispersion model,
determination of pollutant parameters and model inputs via labor-
atory and field studies, and predictive studies using the model.
Preliminary results of the modeling and laboratory investigations
have been published. No field study data regarding groundwater
effects (other than base-line hydrogeological descriptions) are
available (L-8581). The status of each task in the water quality
program is described as follows.
-89-
-------
Pollutant Transport and Dispersion Model Development -
A computer model has been developed to calculate transport and
dispersion of groundwater pollutants from in-situ gasification
processes. Based on a mathematical model developed elsewhere
(Holly, et al., Teledyne Isotopes, Nevada Operations), the model
describes the hydrodynamic transport of radio-nuclides in porous
media. Dispersion and sorption of the pollutants as well as
different boundary conditions for release of contaminants into
the environment are accounted for.
The transport model is intended to describe the move-
ment of the groundwater plume from the burned-out area. This
area will contain primarily ash surrounded by a char ring where
heat has pyrolyzed the coal but the char has not gasified. Out-
side the char ring is a zone contaminated by gases and tars which
have migrated from the reaction zone during gasification.
^
The data input requirements to be supplied from
laboratory and field studies include the following:
Identity and concentration of pollutants
Size and pollutant source
Rate of change of pollution source concentration
with time
• Groundwater flow velocity and direction
Sorptive properties of porous media
Laboratory Experiments - Laboratory experiments are
being designed and carried out to determine the leachability of
inorganic and organic species from the gasification residue and
the sorption properties of coal for these potential groundwater
contaminants.
-90-
-------
The origin of inorganic groundwater pollutants is
assumed to be the ash. In one experiment 10-11 gram samples of
coal ash obtained by gasifying coal at 1273°K were subjected to
leaching with 25-m& aliquots of deionized water at flow rates
of 17 m£/h. The leachates were then analyzed for aluminum,
calcium, hydroxide and pH. Thiocyanates and cyanates will also
be considered in future tests. Results were expressed in terms
•J*,
of the volume of water required to leach "clean"" one gram of
ash and 3.3 x 10^ kg of ash (the amount of ash calculated to be
present after the Hoe Creek burn); the time required for leaching
the 3.3 x 10 " kg ash was then calculated. These results, along
with an analysis of the ash used in the experiment, are presented
in Tables B-2 and B-3. The effect of gasification temperature
on leachability was also examined; leachability appeared to
decrease with increasing temperature from 1273 to 1573°K (1 hour
reaction time), then became very stable above 1513°K when fusion
occurred.
Sorption properties of porous media through which the
pollutants are transported were then studied. Porosities and
distribution coefficients (K^) for water-soluble tar components
(principally phenols), Ca+Z, Al+3 and OH~ were measured for
unheated subbituminous Roland Seam coal.
It was shown that no preferential absorption of any of
the four major tar components by the coal was evidenced. Sorp-
tion isotherms (organics sorbed, mg/kg, vs. organics remaining,
mg/A) were then obtained for the total soluble organic component
(Figure B-3). Although coal had 10 times less sorptive capacity
than several activated carbons, the shapes of the sorptive iso-
therms vs. concentration were similar. The distribution coeffi-
cient was a strong function of the initial concentration of the
organics. K, increased from 2.0 to 50.0 as the initial
* For the OH ion, "clean" is assumed to be pH <10.0.
-91-
-------
Table B-2. ANALYSIS OF ASH (AS CONSTITUENT OXIDE) FROM COAL
TYPICAL OF _HOE CREEK TEST SITE*
Component Wt. Percent
Phosphorus pentoxide, PaOs 0.39
Silicate, Si02 35.38
Ferric oxide, Fe203 2.03
Alumina, A1203 19.80
Titania, Ti02 1>23
Lime, CaO 18.37
Magnesia, MgO 4.56
Sulfur trioxide, S03 16.98
Potassium oxide, K20 0.51
Sodium oxide, Na20 0.65
Undetermined 0 • 10.
100.00
* Wyodak Mine, Roland Seam subbituminous coal.
Source: L-8581
-92-
-------
Table B-3. RESULTS OF LABORATORY INORGANIC LEACHING STUDIES
Ion V'U) V'U) t(y)
Ca+2
Al+3
OH"
0
0
0
.140
.037 •
.140*
4.
1.
4.
6
2
6
x
X
X
10s
106
10 6*
26
7
. 26
.0
.0
.0
VT = Volume of water necessary to leach "clean" 1 gram of ash
T" = Volume of water necessary to leach "clean" 3.3 x 10" kg
of ash from the gasifier
t = Time required to leach the ash bed clean with a flow rate
of 175 m3/y
•* Volume necessary to drop the concentration of OH by an order of magnitude.
Source; L-8581
-93-
-------
6000
4000
en
j<
E 2000
i
o
LU
CO
OC
§ 1000
CO
o
CD
a:
O
600
400
200
' 1 r
10
20
40
100
200
400
1000 2000
"ORGANICS" REMAINING - mg/|
Figure B-3. SORPTION ISOTHERM FOR SOLUBLE ORGANIC COMPONENTS
FROM COAL TAR ON SUBBITUMINOUS COAL
(Source: L-8581)
-------
concentration decreased from 2000 mg/£. Since this concentration
is the maximum expected from any test, K^ = 2.0 was selected for
use in the transport model.
4"2
The sorption isotherm for Ca is shown in Figure B-4.
The sorption of Ca by subbituminous coal is significantly less
than that for the organic component. K^ is approximately 1.0 and,
over the range plotted, is independent of concentration. Sorption
of Al , on the other hand, is essentially infinite for sample
concentrations ranging from 265 to 924 mg/&.
Since the OH~ radical reacts readily with phenolic
functional groups in the coal, sorption could not be experimentally
determined. Attempts to titrate the coal with NaOH were also
unsuccessful. However, based on data reported in the literature,
it was estimated that OH~ released from one gram of ash will be
neutralized by approximately 1.5 grams' of coal (L-8581).
Organic contaminants are assumed to originate from the
tar left in or near the gasification void. Water samples collec-
ted from the LLL "in-situ" simulation reactor contain between
1000 and 2000 ppm soluble organics (phenols) while water samples
from laboratory pyrolysis experiments contain approximately 1000
ppm organics.
Results of Predictive Water Studies -
Some preliminary results of the predictive water quality
studies have been reported. Based on laboratory and field measure-
ments, the assumptions and inputs for the modeling of the Hoe
Creek gasification test which are summarized in Table B-4 were
selected and/or calculated.
-95-
-------
1000
800
M
SO
e
01
•s
O
tn
600
+
CO
O
400
200
200
400
600
800
1000
Ca remaining - mg/£
Figure B-4. SORPTION ISOTHERM FOR Ca
ON SUBBITUMINOUS COAL
(Source: L-8581)
IONS
-96-
-------
Table B-4. SUMMARY OF INPUT PARAMETERS FOR WATER QUALITY
MODEL CALCULATIONS
AQUIFER PROPERTIES
Flow velocity (V)
Total porosity ($ )
Interconnected (flow) porosity ($_)
r
Flow direction
m
Dispersion coefficients —
43.0 m/y
0.33
0.05
easterly
D = 1.5,
= 0.15
SOURCE PROPERTIES
Radius,
R
Material (m)
Ash
Ca+2 5 . 2
A1+3 5.2
OH~ 5.2
Organics 26.8
Initial
concentration, C
(cone, units)
400 mg/£ .
80 mg/Jl
1.0 x 10~3 mol/£b
2000 mg/£
Time
deplete
(y)
26
7
26
2
to
source
T
o
.0
.0
.0 3
.0 0
Rate of change
of pollutant
source cone.
(Co/To) (mg/A y)
15.4
11.4
.8 x lO"" mol/H y
.0 (slug release)
At flow rate of 43.0 m/y
DpH = 11.0
COAL SORPTIVE PROPERTIES
Material
Distribution
Coefficient, K,
Retardation
factor B*
1.0
14.4
OH~
Organics
(reacts with coal)
2.0
27.8
*At 2000 mg/£
Source: L-8581
-97-
-------
The aquifer properties include flow velocity and
direction, porosities and dispersion coefficients. Although
much lower local groundwater flow rates have been measured by
LLL, the 43.0 m/y figure based on U.S.G.S. data was used as the
model input. This will yield a maximum distance that the plume
might travel in a year, assuming no major alterations in ground-
water regime occur as a result of gasification.
Total porosity represents the total void space present
in a material; however-, since the pores are not all connected,
not all the porosity is open to flow. In a typical subbituminous
coal, the interconnected porosity (F) is 0.05 compared to 0.33
(4>T) for the total porosity. The quantity (1 - cj>T/cj>F) is the ratio
of coal to water flowing through the coal. For the Hoe Creek site
this ratio is 13:4. These parameters, along with the distribution
coeffieient for a specific component, are needed to describe the
retardation effect on the movement of that pollutant caused by
interaction with and passage through the coal.
The inorganic materials, as mentioned above, are
assumed to be leached from the ash slowly over a period of time.
Based on size of the source (i.e. , estimated dimensions of the
gasification zone), groundwater flow rate, and results of the
laboratory leaching tests, the number of years required to
deplete the source and the rate of change of the pollutant source
concentration were calculated. Assuming the groundwater flow
velocity and direction are not altered as a result of gasifica-
tion, it was estimated that 26 years would be required to deplete
the ash of Ca and OH~, while the Al+3 would be leached out in
seven years.
The size of the area contaminated by tars during
gasification will probably be determined by the water seal formed
-98-
-------
by dewatering operations; the organics can be transmitted only
as far as the formation water remaining in the coal seam. A
more realistic as well as more optimistic approach, however,
is based on the assumption that most of the gaseous tar compo-
nents will condense within a few feet of the gasification zone.
The less optimistic basis was used in the model, as was the
assumption that the tar was deposited as a "slug" since no
other time dependence could be postulated.
General conclusions regarding plume dispersion.are as
follows:
1. Because of the strong sorption effects of coal,
the organic plume only moves approximately
1500 meters in 1000 years and its concentra-
tion is reduced from 2000 to 200 mg/£. The
plume width is approximately 60 meters. These
results are based on predictive models.
2. In addition, since K, for organics increases
as the concentration decreases, the remaining
organics in solution will be essentially com-
pletely sorbed.
3„ The Ca 2 plume concentration decreases in the
direction of the gasifier as a result of the
change in the source concentration with time.
The plume is roughly 5 to 15 meters in width
and 80 meters long. After 1000 years the
modeled plume extended approximately 3000 meters
downstream and the maximum concentration was
45 percent of that which originally prevailed
at the source.
-99-
-------
Air Quality Studies -
Studies are also being conducted to model the air
pollution plume which is expected to result from the Hoe Creek
gasification test. Air quality modeling parameters are presen-
ted for the Hoe Creek site in Table B-5. Table B-l presented
the expected composition of the product gas to be flared. The
heating value is 5.3 x 106 J/Nm3 (130 Btu/scf). Maximum expected
product gas flow into the flare is 52 Nm3/min (2000 scfm). The
gas will be combusted in a 2:1 air/product ratio at about 1400°K.
Source strength data for ignited and extinguished (i.e., mal-
functioning flare operation) are given in Table B-6. Additional
information on the model and anticipated results are available
in the literature (L-8581). The general conclusion reached
was that the Hoe Creek gasification test would not produce
adverse air quality conditions, even under the worst operating
conditions.
Kemmerer Field Test -
A small-scale, high-explosive fracturing test was
conducted at this site. A 132-pound charge was detonated in a
single hole 50 feet below the surface. Permeability improve-
ments were then measured by drilling a series of core holes in
the vicinity of the explosion. Test blocks of coal were also
fractured with small charges to verify prediction methods. The
results indicated that measured permeability and fracturing were
in good agreement with preshot predictions for one- and two-
dimensional stress-strain codes (L-8558).
Gillette Field Tests, Hoe Creek Site -
The Hoe Creek test site is located in the Powder River
Basin approximately 20 miles south of Gillette, Wyoming (Figure
-100-
-------
Table B-5. SUMMARY OF INPUT DATA USED FOR
AIR QUALITY CALCULATIONS
Source
Flare Operating Condition
Ignited Extinguished*
Effective source height (m)
Temperature (K)
Gas flow rate (Nm3/min)
Fuel
Air
Heat flux (MJ/min)
10.0
1400
52
104
275
10.0
398
52
104
8.5'
Atmospheric Conditions and Site Characteristics
Wind speed (m/s) 4.0
Stability category Neutral (D)
Mixin.g height (m) 250
Topography level
1 The extinguished condition would _result from a flare malfunction.
Because it would lead to abnormally high ground-level concentrations,
it is included in the calculation.
2 Based on gas heat capacity of 8.0 cal/g-mol°C and an exit temperature
of 60°C for the air-fuel mixture.
Source: L-8581
-101-
-------
Table B-6. SOURCE STRENGTHS FOR VARIOUS EFFLUENT GASES-
Source
Flare Operation Gas Strength (m3/s)
Ignited C02
S02
.Extinguished C02
CO
H2
CHi,
H2S
0.27
0.00095
0.057
0.21
0.16
0.019
0.00095
* Calculated from the gas composition of Table B-l and a flow rate of"
52 Nm /min.
Source: L-8581
B-5). It is proposed that the tests be conducted in the Felix
No. 2 subbituminous coal seam which lies approximately 40 m deep
and is about 7.6m thick. The seam lies nearly horizontal with
a tilt of less than 1°.
The water table at the site lies approximately 20
meters below the surface. Aquifers consist of the sand below
20 meters and the Felix No. 1 and No. 2 coal seams. Silt-clay
aquitards lie both above and below the Felix No. 2 seam. Figure
B-6 illustrates a stratigraphic view of the site and Table B-7
summarizes its hydraulic characteristics. The groundwater
flow in the No. 2 seam is in an easterly (downward) direction.
Although USGS data indicate a maximum velocity of 43.0 meters
per year, LLL measurements yield much smaller local flow veloci-
ties (on the order of several meters per year). The horizontal
hydraulic conductivity of the seam is very low; i.e., about
0.15-0.27 m/day (0.5-0.9 ft/day) depending on the direction.
-102-
-------
NORTH DAKOTA
SOUTH DAKOTA
EXPLANATION
Precambrian rocks
Outline of area mapped
Belle Fourche
Axis of anticline
\ \
"'HILLSi*
~"" '" Axis of syncline
0Rapid city
.is
uplift
OUTH DAKOTA
xv ^— M -
-Swe«jtwa.tv>r
25 50 75 100
I | l J
Figure B-5. LOCATION OF HOE CREEK TEST SITE
(Source: L-8582)
-103-
-------
ex
CS
10
20
30
50
60
Felix
No. 1
Felix
No. 2
Sandstone with some
siltstone and claystone
Coal
Siltstone-claystone with
some shale and sandstone
Figure B-6.
STRATIGRAPHIC VIEW OF HOE CREEK SITE
(Source: L-8581)
-104-
-------
Table B-7. SUMMARY OF HYDRAULIC CHARACTERISTICS OF #2 COAL
AND ASSOCIATED,STRATA - HOE CREEK SITE
Rock Unit
Felix #1
Coal
Horizontal
hydraulic
conductivity,
Site m/day
0.314 toa
I 0.947
Horizontal
intrinsic
permeability,
0.475 toa
1.42
Coefficient
of storage
2 ,x 10~2
Vertical
hydraulic
conductivity
jri/day
Vertical
intrinsic
permeability
Vim2
- No measurement made -
Strata between
Felix #1 arid
Felix #2
III
0.078
0.116
- No measurement made -
2.24 x 10
~s2)
5.02 x 10
~"C
2.1 x 10
~2b
0.015
0.001
0.284
0.022
0.016
0.430
o
Ul
i
Felix if 2 coal
0.272
0.150
0.413
0.177
1, 18 x 10 3
~ No measurement made -
itrata below
'elix //2 coal
II
III
I
- No measurement made -
0.325^
O.l40g
0.492f
0.211^
- No measurement made -
> Horizontal
(not quantified)
1.6 x 10 2 - No measurement made -
to
4.15 x 10 3
0.001h
o.oou"
A range of values is given for two different single-well tests in the same well.
Values are averages for the total thickness of strata between Felix #1 and Felix #2 coals,
Values are averages for first 2.7 m of strata above top of Felix //2 coal.
Value along axis of maximum hydraulic conductivity with trend of N 59PE.
e Value along axis of minimum hydraulic conductivity with trend of N 31°W.
Measured along bearing of N 73°E.
•J Measured along bearing of N 39 °W.
Refers to first 2.1 m of strata below bottom of Felix //2 coal.
Source: L-8582
-------
A test pumping well drilled into the coal seam was able to sus-
tain a pumping rate of only 2 gpm. Data from another source
confirmed this low conductivity figure (the coal was reported
to be capable of sustaining a pumping rate of only 4 gpm) „
The water level above the No. 2 seam is about 23 m (75 ft), and
a hydrostatic pressure of 0.23 MPa (33 psi) was measured
(L-8558, L-8581, L-8582).
The TDS levels in the three aquifers of interest
decrease with increasing depth. The sand aquifer contains
2700 ppm TDS, while the upper and lower Felix seams contain
approximately 2000 and 1000 ppm TDS, respectively (L-8544).
Other chemical parameters for the three aquifers of interest
are shown in Table B-8 (L-8544).
The Hoe Creek test site was selected based on the
following criteria required for relatively shallow test condi-
tions (L-8558) :
Thick coal seam (15-50 feet)
Shallow depth (<300 feet)
Relatively flat coal bed
Low permeability overburden
No significant aquifer in either coal or
overburden
Suitable terrain for surface plant operations
Closeness to utilities and all-weather roads
Remoteness
-106-
-------
Table B-8. CHEMICAL QUALITY OF GROUNDWATER FROM VARIOUS STRATA
HOE CREEK SITE 1
Chemical
parameter-
Sodium
Potassium
Total Hardness
Iron
Bicarbonate
Sulfate
Chloride
pH •
Total dissolved solids
Conductivity
Felix #1
coal
60
10
750
0.31
288
750
11
7.3
1882
1900
Strata between
Felix #1 and #2
80
30
1075
0.51
280
1100
12.5
7.5
2738
2900
Felix #2
coal2'
75
6.5
96
0.47
480
174
'12.5
ca
7.8
976
1000
Concentrations in mg/&, conductivities in ymho/cm.
Average values for 2 samples.
Source: L-8582
-107-
-------
The original test plan called for two tests. Hoe
Creek Experiment No. 1, the preliminary experiment, took place
on November 5, 1975. As illustrated in Figure B-7, this was
a simple two-spot fracturing test in which two 750-pound explo-
sive charges were fired simultaneously at the bottom of two
holes 7.6 m (25 ft.) apart in the Felix No. 2 seam. If fracture
evaluation had shown that good permeability had been achieved
between these planned injection and production wells, an air
gasification test would have been the next step. However,
lower permeabilities than expected were achieved. Therefore,
a second phase of Experiment No. 1 is now being planned (L-8558).
These plans call for drilling a new production well
closer in. Gasification will then take place by a forward burn
after dewatering. If plugging or low gas flow occurs, then a
backward burn will be initiated to form a high permeability
path followed by a forward gasification stage. The coal will
be ignited at the top of the seam, with flow set up in a down-
ward direction toward the highly permeable region and production
well intake below.
Drilling preparations for the Hoe Creek Experiment
No. 2, the 5-spot test, were already in progress at the time of
the No. 1 Experiment. However, drilling was halted in December
1975. The objective of this test will be to fracture explosively
and dewater a suitable zone, then over a 2-month period gasify
approximately 3000 tons of coal in a 7.6 m (25 ft.) thick block
about 15 m (50 ft.) on each side. Nearly 40 drill holes are
planned in a circular area 30 m (100 ft.) in diameter. The
general layout of these holes is shown in Figure B-8. The
numbers of each type of well are itemized below:
-108-
-------
Flare
Air compressor
Reaction zone
Explosive
charges
Production gas
Overburden
-130 ft
Figure B-7. SCHEMATIC DIAGRAM OF HOE CREEK EXPERIMENT NO. I
(Source: L-8582)
-109-
-------
10-OW
^ 13-OW
•ti-ow
DW-4
9-OW
DW-
-N-
0 3
I ' • ' I
SCALE !N MILES
WELL DESIGNATIONS
OW: OBSERVATION
I: INSTRUMENT
HE: EXPLOSIVE
DW: DEWATERING
INJ: AIR INJECTION
PROD: GAS PRODUCTION
Figure B-8. HOE CREEK NO. 2 EXPERIMENT
- FIVE-SPOT TEST -
(Source: L-8581)
-110-
-------
5 - explosive fracturing
4 - dewatering
(1) - gas injection (center fracturing hole)
4 - production [10.6 m (35 ft.) from center]
13 - process instrumentation (thermocouples,
gas pressure, liquid levels)
4 - subsidence monitoring (tiltmeters,
extensometers, geophones)
7 - monitoring
f
Surface facilities will include a temporary gas processing plant
with capability of supplying oxygen and steam and for sampling,
metering and monitoring injection gases and product gases prior
to flaring. Gaseous and liquid effluents will also be monitored.
Additional plans call for material balance calculations to be
attempted using an argon tracer technique (L-8544).
The planned dewatering operation will involve pumping
water from the Felix No. 2 seam at about 20 gpm for about 10
days prior to gasification. This will involve removal of an
estimated 1100 m3 (300,000 gal) of water which could be used
either as process water or for stock tanks. Dewatering will
continue at a reduced rate (^10 gpm) during the 60-day gasifi-
cation period, resulting in an additional 3800 m3 (1,000,000 gal)
of water requiring disposal. Monitoring will be continued
throughout the dewatering operation.
-Ill-
-------
APPENDIX C
-------
MORGANTOWN ENERGY RESEARCH CENTER
In 1972 the Morgantown Energy Research Center (MERC)
initiated a five-year, $10-million, ERDA-funded project to develop
in-situ gasification technology for eastern U.S. coals. The
project was based on the Longwall Generator Concept, designed to
utilize the natural directional properties of the coal bed.. This
concept is perhaps the most versatile scheme for accommodating
different modifications in directional flow control, controlled
roof collapse, and hydraulic fracturing (L-2151).
The primary objective of this program is to study and
identify the controlling mechanisms in underground coal gasifica-
tion. It is hoped that through this study the following .benefits
will be gained:
Improvement of the resource utilization
efficiency *
Optimization of product gas heating value
and composition
Minimization of cost and environmental
degradation
Scope of Work and Status
The MERC program consists of simultaneous theoretical,
laboratory, and field projects. Each of these project phases
and its purpose is outlined below. Presently, work in all three
phases is continuing.
Theoretical Studies - Process simulation models of the
coal bed in the UCG process totally disregard internal effects
-113-
-------
(shrinking or swelling and phase changes) in the coal bed. To
better understand the total process, studies are conducted at
the micro, macro, and global levels with the hope of correlating
the effects between these levels.
The three mechanisms believed to be the major contrib-
uting factors of the UCG process are:
1) The mass and energy transport processes
2) Reaction kinetics and catalysis
3) The stress-strain, structural effects
Laboratory Studies - The MERC UCG in-house laboratory
effort is comprised of qualitative "effects" experiments; quanti-
tative mechanical, thermal, and physical property determinations;
and process simulation experiments.
Qualitative effects experiments are conducted on dif-
ferent type coals under various conditions to delineate the actual
physics of the UCG process so that it can be realistically modeled.
Simple oven tests where solid blocks of coal are heated at pre-
scribed rates and temperatures clearly demonstrate relative
reactivity, swelling or shrinking characteristics, phase changes,
and preferred directional thermal fracturing.
Mechanical properties at elevated temperatures have not
been sufficiently evaluated for UCG computations. Since these
data will be necessary to realistically model the structural
aspects of UCG, test facilities have been developed to obtain
such data.
-114-
-------
Field Project - The field work is being pursued in
cooperation with Consolidation Coal Company and Continental Oil
Company. This work is designed to demonstrate the feasibility
of new directional drilling technology, which compliments the
use of the Longwall Generator Concept. Figure C-l illustrates
the application of this concept to a power generation facility.
Use of directionally drilled holes can reduce surface
degradation and environmental impact-equal to or less than con-
ventional oil and gas well drilling patterns. Vertical well UCG
schemes require that patterns be drilled on less than 30-m (100-
ft) square network spacing; this not only destroys the surface
environment but also is not feasible in much of the eastern U.S.
terrain overlying major coal deposits.
The field work will also be useful for determining the
best reservoir preparation for gasification. One such prepara-
tion sequence is outlined in Figure C-2. Since there are several
options for preburn bed characterization and gasification with
two parallel, directionally drilled holes, each with a vertical
hole intersecting its blind end, it is important to develop the
best scheme for a particular coal.
The MERC underground coal gasification site is located
in Wetzel County, West Virginia, near the small community of
Pricetown. At this location the Pittsburgh coal is nominally
1.8 m (6 ft) thick and 1.5 m (5 ft) below the surface. The
hydrogeology of the site has been characterized and the results
have been reported (L-8395). To date drilling operations have
been carried out on the first well. Problems have been encountered
in achieving intersection of the directionally drilled and vertical
holes.
-115-
-------
(1/2 UNIT SHOWN)
I. BED. PREPARATION
v
A. Pump water out of 4
B. Produce CHi,. out of 4
" " 3 and 4 (Low P.P.)
C. Pump water out of 2
D. Produce CHi* out of 2
" " 1 and 2
" " 1 and 2, and 3 and 4
E. Inject air in 1 or 2 until 02 increases and CHit decreases
in 3 and 4
F. Inject air in 1 or 2 until H20 content decreases in 3 and 4
G. Miscellaneous pressure interference and other tests
between Step A and G
II. WELLBORE IGNITION
A. Decrease air rate in 1 and 2 to preset value
B. Vent 3 while heating 4
C. Inject in 3 and reverse burn from 4 to a
III. BLOCK REVERSE BURN
A. When ignition reaches a, change mode
B. Inject in 1 and 2 and produce gases out of 3 and 4
Figure C-l. A LONGWALL GENERATOR DEVELOPMENT SCHEME
-116-
-------
HEAT EXTRACTION
GAS CLEAN-UP I POWER
UN!T I GENERATORS
WATER CLEAN-UP
RECYCLING
COMPRESSION & COMBUSTION
GAS BLENDER >
MORGANTOWN &
CONTROL BOREHOLES
POSITIVE STREAM
BOREHOLE LINKING
FORWARD REVERSE
CYCLED GASIFICATION
Figure C-2. LONGWALL GENERATOR CONCEPT
(APPLICATION TO POWER GENERATION FACILITY)
(Source: L-2151)
-117-
-------
RADIAN
CORPORATION
APPENDIX D
-------
RADIAN
CORPORATION
TUSI IN-SITU LIGNITE GASIFICATION PROJECT
In March of 1975 an agreement was signed between the
Texas Utilities Services, Inc. (TUSI), and V/0 Licensintorg of
Moscow whereby TUSI was granted access to Russian in-situ gasi-
fication technology. This 2-million dollar, agreement also gave
TUSI exclusive licensing authority in the U. S. This is in
conjunction with Williams Brothers Process Services, Inc., of
Tulsa, Oklahoma. The Soviet Union will also receive modest
'royalties for any gas produced by their technology (L-1075,
L-1436).
TUSI members involved in this project include Dallas
Power and Light Co., Texas Electric Service Co., and Texas Power
and Light Co.
The Russian technology, which dates back to the 1930's,
has been applied in the USSR to a wide range of coals. Two UCG
plants are currently in operation. One of these supplies fuel
for a 30-MW power plant.. The reported heating value of the gas
generated is in the 3.5-4.1 x 10s J/Nm3 (85-100 Btu/scf) range
(L-1075, private communication).
The objectives of the initial test program are to
determine the heating value and quantity of gas produced, the
economics of the process and the existence and extent of adverse
environmental effects associated with the technology. Its appli-
cability to deep (>45 m [150 ft]) East Texas lignite deposits for
electric power generation is the overall objective. Drilling and
other site preparation work was initiated in March of 1975 and
the first burn took place in August and September 1976, at the
test site near the Big Brown Station near Fairfield. It is
anticipated that a few months of operation will be sufficient to
119-
-------
demonstrate whether or not the technology is feasible for this
application. A pilot-scale operation is also under consideration
(L-1075, plus TWQB information; L-9166).
The major emphasis of the environmental studies is on
groundwater contamination. Since the tests conducted or planned
to date are of short duration and of limited intensity, no sub-
sidence effects are anticipated. Deterioration of air quality
is also receiving little attention at this time. The Russians
claim that no adverse environmental effects have resulted in the
USSR and in conjunction with this, a TUSI official reported that
he observed "no visible evidence" of environmental problems at
the USSR site he visited. A potential problem condition at the
Texas site, however, may exist due to the presence of aquifers
in the strata (L-1075).
Process Description
The technology to be investigated is based on a perco-
lation method using air injection and producing wells. Permea-
bility is achieved by means of high-pressure air or hydraulic
fracturing techniques. Figure D-l represents the process flow
diagram for the test site. The basic features of the process are:
Drilling and fracturing
Ignition
Linkage
Gasification
Product treatment/utilization
Water treatment/disposal
Dewatering
-120-
-------
Air
Comp.
Sampling
Ground Surface
o
cz
p
6
V
/**
/ Air
Propone
-Pilot
Source
I-T1
M
I
Overburden
A . •; Lignite Cool
Figure D-l. PROCESS FLOW DIAGRAM FOR IN-SITU GASIFICATION TECHNOLOGICAL TEST SITE
(Source: L-9165)
-------
A detailed description of the process to be tested at Big Brown
is not readily available although it is probable that descriptive
information given in a recently published overview of Russian
technology can be applied here (L-8618).
After site selection and preparation, the test wells
are drilled. Air injection is then carried out to determine the
actual direction and separation of these wells. Once these are
established, monitoring wells are drilled and fitted with approp-
riate instrumentation. Ignition is accomplished by first inject-
ing compressed air to dewater the lignite at the bottom of the
injection well. The temperature of the lignite is then raised
by simultaneous injection of air and a burning fuel. Once
ignition is established, linkage between the two injection wells
is accomplished via a technique called "fire filtration linkage".
and later between the two producing wells (L-9165). The water
supply for the gasification reaction is the groundwater present
in the coal seam. Site-specific details of the Big Brown test
are provided in the next section, Project Scope and Status -
Field Test.
Project Status and Scope
Since signing of the agreement in March of 1975,
activities have been carried out in the following areas:
Site characterization and preparation
First gasification test
Water quality studies
Specific approaches and results to date in each of these areas
are described in the following text.
-122-
-------
Site Characterization - The site selected for the gasi-
fication test is located near the Big Brown Steam Plant at
Fairfield, Texas, in Freestone County. The lignite seam to be
gasified is situated 67 m (220 ft) deep under a hydraulic head
of 49 m (160 ft) . Aquifers are located in five different strata
at the test site; these include units 3, 9 (upper lignite seam),
11, 13 (lignite seam to be gasified) and 15, as indicated in the
stratigraphic view of the gasification site (Figure D-2). Geologic
descriptions of all the units shown are available in the permit
application to the Texas Water Quality Board (L-9165). Existent
water quality data are presented in a later subsection of this
project description (L-9166).
Site preparation activities consisted of drilling three
test wells, ten water quality monitoring wells, and three tempera-
ture wells in the area. Their approximate locations are indicated
on Figure D-3. Well numbers identify the unit into which the
well is drilled (refer also to Figure D-2). The water quality
wells and the respective units being monitored are as follows
(L-9166):
Well No. Unit
TTS 3-1 3
TTS 9-1 9
TTS 11-1 11
TTS 11-2 11
TTS 13-1 13
TTS 13-2 13
TTS 13-3 13
TTS 13-4 13
TTS 15-1 I5
TTS 15-2 15
-123-
-------
UNIT 1
INTERBEDDED SANDS, SILTS & CLAYS
UNIT 1
INTERBEDDED SANDS, SILTS & CLAYS
UNIT 3
SAND & SILTY SAND
UNIT 3
SAND & SILTY SAND
UNIT 5
INTERBEDDED SILTY SAND & SILT
' '«fc-
UNIT 9. LICNTTF
UNIT 10, CLAY'
UNIT El
SILTY SAND W/ SILTY CLAY LAYERS
UNI?" 12, CLAY
0811 «. CLAV
TOIT13. LIGNITE
15, SILTY SAND
ISO
125
100
75
ISO
125
100
75
Figure D-2. TUSI IN-SITU LIGNITE GASIFICATION PROJECT
STRATIGRAPHIC CROSS SECTION OF TEST AREA
(Source: L-9166)
-124-
-------
to
Ui
EDRILLED
AFTER BURN)
Scale: 1" = 100'
Figure D-3. MONITOR WELL LOCATIONS AT TECHNOLOGICAL TEST DRILLING SITE
(Source: L-9166)
-------
Details regarding construction of temperature monitoring wells
(TM-1, TM-2, TM-3) are given in the permit file. There are three
test wells specified, all of which are approximately 67 m (220 ft)
deep and within 30 m (100 ft) of each other. The ignition well
is identified as TTS-10 and wells TTS-9 and TTS-1A serve as injec-
tion wells. Well TTS-9 will be used only for air injection, while
Nos. 10 and 1A will also serve as gas draw-off wells (L-9165,
L-9166).
Field Test - The in-situ gasification test was initiated
on August 15 (air injection) and ignited on the 17th. The opera-
tion was shut down after 28 days because of inferior product gas
quality which resulted from operation at a much reduced operating
pressure required to control in-situ water quality. The product
gas from this test was flared after monitoring; no data were
available in the public domain, however, regarding gas quality.
The test can best be described by a tabulated chronology of events
compiled from several documents in the public files.
6/22 Public hearing held
7/29 TWQB approved permit
8/15 Air injected into the formation to "dry-out"
the production area
8/17 Formation ignited at base of TTS-1A by
simultaneous injection of air and a burning
fuel with air flow from TTS-10 to TTS-1A.
Air flex? reversed after 7 hours .
8/19 Completed "Link," TTS 10 & TTS 1A
-126-
-------
9/01 Completed "Link," ITS 10 & ITS 9
9/03 An upward trend was recognized in conductivity
in monitoring wells TTS 11-2, TTS 13-2 and
TTS 13-4, along with a reduction in pH in well
TTS 11-2. Operating pressure was reduced from
0.58 MPa (69 psig) (formation hydrostatic pres-
sure) to 0.43 MPa (48 psig) and notified TWQB.
9/04 Further increase in conductivity and decrease
in pH was noted in well TTS 11-2. The well
was pumped to clear the casing and another
sample taken which was similar to that recorded
on the 3rd. Analysis of a sample taken later
in the day indicated a further reduction in
conductivity.
9/05 The reduced pressure appeared to cause an
improvement in conductivity levels so the
pressure was raised to 0.52 MPa (60 psig) (0.16
MPa or 9 psig below hydrostatic) in an attempt
to improve produced gas quality without affecting
the conductivity of the water.
9/06 Conductivity reading increased significantly in
& wells 13-2 and 13-4. Pressure was returned to
9/07 0.43 MPa (48 psig) to reverse the upswing,
resulting in minor improvement.
9/08 A minor improvement appeared to occur during
-10 these days.
-127-
-------
9/11 The operating psig was progressively reduced to
-13 0.29 MPa (28 psig) until the gas quality was too
inferior to continue. At this time injection of
air was discontinued. It is anticipated that water
will now return to the gasified area and extin-
guish the flame. This will terminate the test
phase of the operation and begin the restor-
ation phase.
10/07 At this time the water table had almost returned
to normal levels, but the temperature near the
burn area remained high, 93-149°C (200-300°F).
Plans for closure specify full-length cementing of the wells to
be abandoned.
Water Quality Monitoring - As described above, ten
water monitoring wells were drilled at the test site. Baseline
data for criteria parameters for nine of these wells as determined
.from analysis of the samples are presented in Table D-l. Avail-
able measured levels for other parameters in. geological units of
interest are presented in Table D-2. Analyses are also being
conducted periodically for the following additional species:
N03 as N Total Fe
H2S As
CN~ Ba
CIU B
SCN~ Cd
TOG Ag
Frequency of sampling during the gasification period
is specified in Table D-3. For at least six weeks following the
burn, weekly samples will be taken, to be followed by monthly
sampling until restoration commences.
-128-
-------
Table D-l. BASELINE WATER QUALITY STANDARDS
FOR TEXAS LIGNITE GASIFICATION PROJECT
Well
TTS 3-1
9-1
11-1
11-2
13-1
13-2
13-3
13-4
Temperature
23.3
22.0
22.0
22.1
22.2
22.3
22.1
22.2
PH
8.1
8.7
9.17
8.31
8.50
9.35
9.58
8.75
Cond.
(ymhos)
530.0
361.4
386.7
394.7
459.0
507.5
557.7
479.5
NH3-N
(ppm)
.19
.19
.20
.20
.26
.35
.35
.36
(ppm)
58.3
.6
11.3
10.6
16.1
11.5
25.3
19.9
15-1
22.3
9.63
533.3
40
57.0
Source: L-9166
-129-
-------
Table D-2. ADDITIONAL BASELINE QUALITY PARAMETERS OF WATER IN GEOLOGIC UNITS
u>
Concentrations - ppm
Parameter
Chloride
Chromium (Hex)
Copper
Lead
Manganese
Mercury
Selenium
Sulfate
TDS
Zinc
Bicarbonate
Carbonate
Calcium
Magnesium
Sodium
PH
Phenols
Unit
*C 3
*250 @ 216
* .01 @
* 1.0 2.1 <§
* .05
* .05 17.4 @
* .002
.01
*250 47
500 @ 990 @
* 5
81
-
173
26
72
* 6-9 7.6
.001
Unit
9
96
-
<.l
-
.6
-
-
72
550 @
-
254
-
77 '
23
50
7.4
-
Unit
11
30
<.05
<.l
<.l
<.l
<.0001
.005
18
275
.90
-
20
14
9
64
8.3
.30 @
Unit
13
(Production)
84
<.05
.05
<.l
<.01
<.0001
* .022
37
*1120
.94
-
34
8
5
84
6.7
* .36
Unit
15
30
-
<•!
<.02
<.05
.0006
.025
40
350
.35
130
40
10
2
80
8.6
.06
* Expected restoration value for production area aquifer.
@ Expected restoration value for upper and lower aquifers.
Source: L-9166
-------
Table D-3. SAMPLING FREQUENCY FOR GASIFICATION PERIOD
Unit
13 Wells
Temp.
PH
Cond.
scu
NH3-N
Water
Level
(4) (Temp . only
for TM1, 2 & 3
Unit
(2)
Unit
(2)
Unit
(1)
Unit
(1)
15 Wells
11 Wells
9 Well
3 Well
3
1
1
1
1
3
1
1
1
1
3
1
1
1
1
1
1
1
1
1
1
1
1
1
1
3
1
1
1
1
Source: L-9166
Procedures were also specified in the permit in case of
an excursion. An excursion was defined by any of the following
occurrences:
• Increase in conductivity by 200 tnicromhos
• Increase in NHa-N by 5 ppm
• Increase in SO** by 100 ppm
• Significant variation in pH
In the event of an excursion possible actions to be taken include
(L-9166):
-131-
-------
• Drilling of additional holes in the direction
of the groundwater movement at 15- to 30-m
(50- to 100-ft) intervals
* Adjustment of operating conditions
• Pumping of monitoring wells to intercept the
contaminated groundwater
• Termination of test
In the case of dewatering, three possible disposal methods were
cited in the permit (L-9166). These included discharge into
either the retention pond at the coal storage area or the ash
pond at Big Brown or storage on site and subsequent utilization
for dus-t suppression on haul roads. The selection* of which of
all the above possible actions to be taken was to be based on
the nature and level of the contaminants.
Recently, additional arrangements have been made to
conduct GC-MS analyses of four specified water samples (Wells
TTS 10, 13-11, 13-2 and 11-2). Results of these analyses to
identify organic components are not yet available (L-9166).
Results of the water monitoring program to date are
available in the Texas Water Quality Board files. In summary,
the following observations can be made:
1. Temperature and NH3-nitrogen were unaffected
in all wells.
2. Decreases in pH were measured in the four
wells located in Unit 13 (the lignite seam
-132-
-------
being gasified) and in one of the wells in
the overlying aquifer (Unit 11). These
decreases were first noted as soon as one
day after air injection was initiated in
one case (No. TTS 13-2). After a period
of from 5 to 31 days the pH levels had
increased to apparently steady but below-
normal levels.
3. Conductivity increases were observed within
a few days following pH decreases in all of
these cases.
4. Some slow tailing-off of sulfate levels in
the affected monitoring wells was also
observed.
Water quality analyses of other than criteria pollutants mentioned
above were nSt yet available for the gasification and follow-up
period.
Some general conclusions may be drawn although they may
be premature. It has been suggested that the observed decrease
in pH may be due to C02 in the water from the injection of air
into the seam. In any case, pH serves as a better indicator of
excursion than conductivity since it drops sooner than observed
rises in conductivity. The apparent excursion into Unit 11 may
mean that in a full-scale process, overlying aquifers may present
a more serious problem than production zone aquifers since upper
aquifers generally are of greater quality and quantity. However,
the lack of a continuous data base due to problems in sampling
of this well causes due concern for validity of conclusions drawn
from these data.
-133-
-------
APPENDIX E
-------
UNIVERSITY OF ALABAMA - FEASIBILITY STUDY OF IN-SITU
COAL GASIFICATION IN THE WARRIOR COAL FIELD
A two-year technical feasibility study of in-situ
gasification of thin bituminous coal seams is currently underway
at the University of Alabama. The program was initiated in
August of 1975 under an NSF grant. Additional funding is provided
by the Alabama Power Company, the Mineral Resources of Alabama
and the University of Alabama.
The approach developed to achieve the objective of this
program involves seven basic tasks:
Site selection
Site-specific studies of geology and physical
coal properties
Determination of the air acceptance properties
of the seam
Development and operation of laboratory
combustor
Development of linking techniques that will
allow high resource recovery along with a
controllable gasification process
Development of analysis techniques for multi-
parameter investigations
Establishing baseline environmental character-
istics of the site
-135-
-------
All information contained in this section of the report is based
on the second semiannual project report (L-8617) published in
October 1976.
Process Features
The process details of the University of Alabama's plans
for in-situ gasification are. not defined at this time. As.
stated in the previous section, their process is aimed at gasifi-
cation of thin coal seams (<1 meter) of eastern bituminous coals.
Fracturing techniques are still under investigation although
vertical hydraulic fracturing is being emphasized. Follow-up
linkage by reverse combustion appears the most feasible at this
time with air gasification in the forward direction. Estimated
product quality and flow sheets for this process were not avail-
able at this early stage.
Project Status and Results
The status and results after completing the first year
of this two-year program are summarized below. Details are
available in the semiannual report (L-8617).
Site Selection - This task has been completed. The
gasification site is located two miles north of Adger, Alabama,
in Southern Jefferson County. It is located above the Gwin Seam
of the Warrior Coal Field, as illustrated in Figure E-l. The
coal seam to be gasified meets the requirement of being less than
1 meter thick; at the test site the coal is 0.86 m (34 in) thick
and lies under 79 m (260 ft) of overburden, although the depth
varies considerably from 0-104 m (0-340 ft) throughout the general
area. The overburden consists of sequences of dark gray siltstone,
fine-grained sandstone and shales.
-136-
-------
WARRIOR COAL FIELD
AHGA Of INVESTIGATION
Figure E-l. LOCATION OF THE EXPERIMENTAL IN-SITU GASIFICATION
STUDY AREA WITH RESPECT TO THE WARRIOR COAL FIELD IN ALABAMA
(Sotirce: L-8617)
-137-
-------
Geological and Coal Properties Studies - Significant
progress has been made in this second task area. During the
geological studies the coal and overburden have been character-
ized for the general area as well as the specific test site.
Figure E-2 presents the lithology of the experimental gasifi-
cation site as determined by a core sample. The test area is
located in the drainage area of Valley Creek, which flows into
the Black Warrior River. It has also been determined that two
or possibly three faults are present in the vicinity of the
test site.
The following coal properties were compiled from
available data for Alabama coals:
Proximate analyses (moisture, volatile matter,
fixed carbon,"ash)
• Ultimate analyses (H, C, N, 0, S)
Heating value
Free swelling index and other swelling
properties
Agglutinating value
Plastic properties
Other physical properties (breakage, friability,
grindability, hardness, etc.)
Most coals in the Warrior coal field are characterized as high or
medium volatile bituminous. The Gwin seam contains strongly
-138-
-------
40-H
60-H
80-
100-
120—f
140—
160-
i8o—r
200—r
220—1
240—T
260—
'/////////777A
280—\.' • '•
SANDSTONE
SILTSTONE
SHALE
Fiure E-2. LITHOLOGY PRESENT IN IN- SITU GASIFICATION
CORE HOLE 1-A AT EXPERIMENTAL GASIFICATION SITE
(Source: L-8617)
-139-
-------
swelling coal of MVB rank. No published analyses were available.
Two to three tons were sampled for use in the laboratory studies,
but this coal was so friable (easily crumbled) that it could not
be used in the combustor. Several coals from adjacent seams in
the Warrior field were collected for these tests, which will be
addressed in another section. The Utley (or Clements) seam, for
example, which lies 70 m (230 ft) above the Gwin seam, is assumed
to be similar to that in the gasification site.
Air Acceptance Properties of the Coal Seam - This part
of the program is also in progress. Air acceptance is a measure-
ment of the rate at which air, or another gas, can be forced into
a coal seam, through a drilled and cased borehole, at a certain
pressure. Two test holes have been drilled at the site and
several more are planned. No results are available yet.
a
Laboratory Combustor Studies - A bench-scale combustor
system was designed and constructed in order to provide data for
correlation between product gas quality and input variables. The
gas flow system is illustrated in Figure E-3 and details are
available in the semiannual project report. To date some meaning-
ful results have been obtained and this phase of the program is
continuing.
The combustor tests were conducted using coal block
samples having a single vertical crack up the middle in the
direction of the air flow. This crack simulates a simple case of
conditions resulting from hydraulic fracturing of the coal seam.
Severe plugging problems occurred during trials of forward com-
bustion due both to swelling close to the reaction zone and tar
condensation further down the crack. This was not the case during
reverse combustion runs; the reaction in this mode, however, does
-140-
-------
AIR
SUPPLY
PRESSURE
REGULATOR
ROTAMETER
NITROGEN
SUPPLY
AFTERBURNER
VENT
VENT
SAMPLE TO
GAS CHROMATOGRAPH
COMBUSTOR
CYCLONE
SCRUBBER
•IXJ-
SAMPLE TO
ANALYSIS
Figure E-3.
GAS FLOW SYSTEM FOR LABORATORY COMBUSTOR
(UNIVERSITY OF ALABAMA)
(Source: L-8617)
-------
not produce a satisfactory product gas. Therefore, further
testing was carried out to study its feasibility as a linking
mechanism following hydraulic fracturing. The following problems
are under investigation:
Required air flow to support combustion at the
maximum rate without excessive blow-by
Kinetics within the char region under the
influence of air passing from the crack
region to the outer edges of the combustion
zone
Heat transfer from the combustion zone into
the unburned coal
Details of these studies are available in the"literature (L-8617).
Development of Linking Techniques - This work is also
in progress. Present plans call for initial fracturing by
hydraulic fracturing techniques to be followed up by reverse
combustion to complete the linkage. Some of the basis for this
design was developed during the laboratory combustor tests.
A theory for predicting fracture direction for in-situ
gasification processes is being developed as part of this phase
of the program. Bureau of Mines and other field data are being
used to aid in the development and verification of a hydraulic
fracture model of coal that considers the directional permeability
and directional tensile strength properties of coal. It has been
shown that under certain conditions coal will fracture along its
face cleat direction rather than perpendicular to the least
principal stress as predicted by conventional fracture theory .
-142-
-------
Also under consideration as a possible fracturing or
linkage technique is the Bureau of Mines' (MERC) deviated drilling
or laser drilling approach.
Development of Numerical Analysis Techniques - The
objective of this support task is the development of numerical
techniques.to supplement the laboratory studies and to aid in
predicting the results of planned field work. Topics currently
under investigation include:
Advance rate and lateral extent of combustion
front during reverse burn
Heat transfer associated with advance of
the combustion front
Fluid flow associated with advance of the
combustion front
Groundwater Contamination Studies - This effort is aimed
primarily at defining potential long-term contamination of ground-
water by leaching of gasification residues rather than immediate
or short-term effects due to gas leakage during the burn. Both
organic and inorganic contaminants are being considered. The
major portion of planned baseline monitoring is now completed and
monitoring by the Geological Survey of Alabama is continuing.
The research studies involve both laboratory and modeling
activities. The approach and results to date in these different
areas are described below.
The geology and hydrology of the experimental site have
been characterized. The coal seam to be gasified lies below the
dry-season water table. The presence of several faults in the
-143-
-------
lower Pottsville formation contributes to increased groundwater
flow in the area. The permeability of the formation and the
pressure gradient were determined to be approximately 150 darcies
and 9.5 meters of water/kilometer (50 feet/mile), respectively.
Combined, the superficial water velocity is approximately 0.0015
cm/sec (1600 ft/year).
Laboratory leaching studies were conducted using coal
similar to that in the Gwin seam pyrolyzed under the following
laboratory conditions.
One hour to raise temperature of mass to 650°C
Few minutes to raise temperature to 1200°C
Reduced air flow to achieve partial combustion;
reaction complete within a few minutes-
Sample cooled
Analyses of the coal and the carbonization residue are presented
in Table E-l.
Leaching studies were then carried out in a packed tube
reactor as illustrated in Figure E-4. Experimental conditions
are summarized in Table E-2. The coal residues leached repre-
sented a situation where gasification of greater than 50 percent
of the coal in the seam was obtained. Since tap water was used
as the leaching agent, baseline leachate analyses for all species
considered except trace metals were determined. The flow rate
of 1.9 cm3/min simulated the estimated groundwater velocity in
the proposed test site (1.89 cm/min). Leachate samples were
collected for approximately one month and analyzed by standard
procedures as specified in Standard Methods for the Examination
of Water and Wastewater, American Public Health Association.
-144-
-------
Table E-l. PROPERTIES OF COAL USED
(Dry Basis)
Weight
Before
Carbonization
percent
After
Carbonization
Proximate
Volatile Matter
Fixed Carbon
Ash
Sulfur
Heating value, J/g
(Btu/scf)
32.91
64.63
2.46
1.88
3.4071 x 107
(14,649)
5.41
62.28
32.31
0.86
2.2358 x 107
(9,613)
Ultimate
Carbon
Hydrogen
Nitrogen
Sulfur
Ash
Oxygen (by difference)
80.54
5.59
1.76
1.92
2.60
7.59
61.81
1.89
1.01
0.81
32.31
2.12
Source: L-8617
•145-
-------
f
Water in
L
:r=—>- Overflow
Conscant
head
tank
Rotameter
Glass column,
2" I.D., 2r long
Residue particles
Sample
collection
vessel
Figure E-4. LEACHING APPARATUS
(Source: L-8617)
-146-
-------
Small
Medium
Large
-25.4 + 88.9
(-10 + 35)
-7.6 + 15.2
(-3 + 6)
-2.67 + 1.88
(-1.050 + 0.742)
Average
diameter, cm (in)
0.103
(0.0407)
0.500
(0.197)
2.28
(0.896)
Packed Tube Properties
Particle
size
Small
Medium
Large
Particle
mass
needed
to fill
tube
(grams)
648
520
446
Volume
of water
in packed
tube
(m£)
605
680
765
Water
residence
time in
tube
(hours)
5.35
6.00
6.75
Duration
of run
(days)
27.196
28.250
31.479
Source: L-8617
-147-
-------
Later studies will involve analysis of organic components by gas
chromatography/mass spectrometry.
Results were presented graphically for some components
as shown in Figures E-5 through E-9. Leaching curves were fitted
by an exponential decay equation; phenols did not fit this curve,
however. Decay coefficients calculated for each component are
tabulated in Table E-3 along with their initial concentrations.
The results were compared to available water quality standards.*
The general conclusion held to date is that no long-term
problems should result from in-situ gasification processes, although
in some cases, initial releases are higher than standards. These
cases include COD, ammonia and phenols. Values for COD, nitrate,
nitrite, sulfate and total dissolved solids were all below the
levels used for comparison in this study. No standards .for com-
parison were available for organic nitrogen or organic acids. All
metal concentrations in the effluents were found to be generally
lower than those in the city tap water used in the leaching experi-
ments , It was postulated that the coal residue absorbs metal ions
* Promulgated and recommended standards for comparison in the referenced study
include:
BOD, COD Effluent averages of samples, Tuscaloosa (Alabama) Wastewater
Treatment Plant.
BOD Effluent monthly average set by EPA as suitable for Tuscaloosa
Wastewater Treatment Plant.
Recommended maximum level for public water supply (Water Quality
Nitrite Criteria 1972)
Sulfate
Phenols
TDS Desirable maximum level for public water supply; may be exceeded
if concentration of other individual substances remains below
recommended limits (Water Quality Criteria 1972) .
Nitrate Maximum level set by law for public water supply (Federal Register,
December 24, 1975) .
-148-
-------
rather than emits them. Particle size of the residue was also
shown to be a factor. In general both C0 and r (initial concen-
tration and decay constant, respectively) are larger for small
particles than for large particles.
-149-
-------
60
e
G
O
u
c
o
o
Q
O
M
4.0
3.0
2.0
1.0
0.5
[O
1.0
0.5
o
Small particles
Run 1
C0 = 2.72 mg/£
r = 0.0177 hr
0 25 50 75 100
3.0
2.0
Medium particles
Run 2
C0 = 1.73 mg/i
r = 0.00673 hr
50
100
150
200
3.0
2.0
1.0
0.5
Figure E-5.
50
100
Large particles
Run 3
C0 = 1.00 mg/£_
r = 0.00352 hr
150
200
Time, hours
BOD CONCENTRATION CHANGE WITH TIME IN THE
CONTACTING EXPERIMENTS
(Source: L-8617)
-150-
-------
150 L
100
200
Small particles
Run 1
C0 = 252.1
r = 0.00174 hr
300
400
oo
S
c
o
•H
4J
Ct)
h
4-1
0)
a
e<'
o
o.
a
o
o
150
100
50
Medium particles
Run 2
C0 = 135.6 mg/A
r = 0.00145 hr
100
200
300
400
500
600
20
Large particles
Run 3
C0 = 70.8 mg/&
r = 0.000850 hr
100 200 300 400 500 600
Time, hours
Figure E-6. COD CONCENTRATION CHANGE WITH TIME
IN THE CONTACTING RUNS
(Source: L-8617)
-151-
-------
100
BO
e
o
•H
c
0)
O
O
u
u
•H
a
ts
60
l-l
O
100
200
Small particles
Run 1
C0 = 120 mg/JZ, •
r = 0.00378 hr
300
400
Medium particles
Run 2
C0 = 46 mg/£
r = 0.00123 hr~
100
200
300
400
500
600
40
30
20
Large particles
Run 3
C0 = 36 mg/X,
E3
100
200
300
400
500
600
Time, hours
Figure E-7. ORGANIC ACIDS CONCENTRATION CHANGE
WITH TIME IN THE CONTACTING RUNS
(Source: L-8617)
-152-
-------
•60
o
o
u
§
a,
Small particles
Run 1
C0 = 0.880 mg/Ji
300
400
500
600
Medium particles
Run 2
C0 - 0.300 mg/Z „
A
A
100
200
300
400
500
600
0.10
0.05
Large particles
Run 3
C0 = 0.055 mg/SL
•a—E
100 200 300 400 500 600
Figure E-8.
Time, hours
PHENOLS CONCENTRATION CHANGE WITH TIME
IN THE CONTACTING RUNS
(Source: L-8617)
-153-
-------
1.00
0.50(1
o.io
0.05
Small particles
Run 1
C0 = 0.512 mg/£
r = 0-00522 hr
100
200
300
400
c
o
CJ
e
o
o
6
o
i-i
4=
O
1.00
0.50
0.10
0.05
0.01
100
200
300
400
Medium particles
Run 2
C0 = 0.395 mg/JL
r = 0.00501 hr
500
600
0.50
Large particles
Run 3
C0 = 0.287 mg/A
r = 0.00493 hr
100 200 300 400 500 600
Figure E-9.
Time, hours
CHROMIUM CONCENTRATION CHANGE WITH TIME
IN THE CONTACTING RUNS
(Source: L-8617)
-154-
-------
Table E-3. WATER EFFLUENT ANALYSIS EXPONENTIAL DECAY CONSTANTS
Substance Particle Size
BOD
COD
Organic Acids
Ammonia (N)
Nitrate (N)
Sulfate
Organic Nitrogen
TDS
Phenol
Chromium
Copper
Manganese
Sodium
Nickel
Zinc
^^___ -
Source": L-8617
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
Small
Medium
Large
_
C0,mg/l
2.72
1.73
1.00
252
136
71
120
46
36
3.49
3.22
2.23
3.8
3.1
2.6
23.8
21.9
9.2
2.34
1.65
1.34
311
198
159
0.880
0.300
0 . 0-55
0.512
0.395
0.287
0.970
0.905
0.748
1.25
0.896
0.741
2.62
2.46
1.99
1.36
1.22
0.403
2.94
1.22
0.756
r , hr 1
0.0177
0.00673
0.00352
0.00174
0.00145
0.00085
0.00378
0.00123
0.000717
0.00288
0.00213
0.000817
0.000945
0.000548
0.000457
0.00121
0.00113
0.000624
0.00122
0.000876
0.000401
0.00516
0.00251
0.00150
—
—
-
0.00522
0.00501
0.00493
0.0105
0.00667
0.00447
0.0110
0.00632
0.00594
0.0110
0.00632
0.00392
0.00961
0.00810
0.00366
0.0129
0.00830
0.00621
•155-
-------
APPENDIX F
-------
RANN DIVISION (NATIONAL SCIENCE FOUNDATION)/
UNIVERSITY OF TEXAS - IN-SITU CONVERSION OF TEXAS LIGNITE
TO SYNTHETIC GAS
In September 1974, the University of Texas at Austin
initiated a project entitled "In-Situ Conversion of Texas Lignite
to Synthetic Gas." This project is being conducted under the
sponsorship of the RANN (Research Applied to National Needs)
program of the National Science Foundation, Texas Utilities
Services Company, Continental Oil Company, Mobil Oil Corporation,
and the State of Texas (L-9168, L-9169).
•v,
The obj ectives of this program are:
Determine which geological, physical and
chemical conditions are conducive to
application of underground gasification
Develop a mechanistic description for the
dominant chemical and physical processes
occurring during underground gasification
(this would provide a design basis for
later field testing)
Demonstrate- that in-situ gasification can
be operated and controlled satisfactorily
on a laboratory scale, maintaining consis-
tent production
Obtain engineering and geological data for
several candidate in-situ gasification sites,
based on core drilling at those sites
-157-
-------
Scope of Work
To achieve the objectives of this project the following
approach is being taken:
Develop a gasification channel simulation
model to facilitate an investigation of the
technical feasibility of in-situ gasification
Develop an economic computer model to facilitate
a study of the economic feasibility of in-situ
gasification
Design and construct a combustion tube
Conduct subsequent experiments in order to
obtain information on pyrolysis, gasification
pattern, and gasification products
Develop mathematical models suitable for design
scale-up of in-sit'u gasification facilities
Use all program intermediates to develop a
technical and economic basis for evaluating the
potential of in-situ gasification for a given
site
Experimental Configuration
To test the modeling hypothesis for an in-situ gasifica-
tion system it is necessary to construct a suitable experimental
apparatus, which is nearly completed. The experimental system
consists of a refractory-lined, five-centimeter diameter, one-meter
-158-
-------
long, insulated vertical stainless steel tube in which the reac-
tion will take place. The tube will be packed with small pieces
of lignite. In order to sustain sufficient flow rates, the bed
will have a specified porosity. Metering systems will be instal-
led to monitor the flow rate of oxygen and nitrogen to the reactor,
and thermocouples capable of measuring temperatures up to 1100°C
will be used to measure the temperature at six points in the
reactor. Gas samples will be collected in evacuated sampling
bottles and will be analyzed for carbon monoxide, oxygen, nitrogen,
and carbon dioxide via- gas chromatography. Due to the toxic
nature of the effluent gas, extensive safety precautions will be
taken. A flammability meter will be used to prevent any possible
explosion.
Project Status and Results
Based on the work conducted during the first year of
the program it has been concluded that:
In-situ gasification is technically feasible
for application to the deep-basin Texas
lignite
In-situ gasification effectively expands the
extraction limits for coal by a factor of ten
over strip mining; i.e., overburden to seam
ratios of approximately 150:1 appear to be
economic for in-situ gasification compared
to 15:1 for strip mining
The purpose of the next two years' research is to develop a
geological and engineering design for the application of in-situ
gasification to the large deposits of deep-basin lignite.
-159-
-------
APPENDIX G
-------
OTHER U.S. IN-SITU GASIFICATION PROJECTS
Currently, there are several other in-situ gasification
projects being conducted or recently completed in the U.S. under
various sponsorships. A brief description of each of these
projects follows.
Los Alamos Scientific Laboratory
This project is being developed without sponsorship so
that it can be prepared as a proposal to ERDA. The primary
features of this project are:
The process is tailored for application in
semi-arid regions of the Southwest
The process will use C02 and 02 instead of
steam and oxygen or air as the gasifying
agents *
This particular gasifying technique will involve two stages. In
stage 1, the coal bed is pretreated by drying with waste heat and
hydraulic fracturing. Stage 2 involves gasifying the coal by
using C02 and 02.
Texas A & M University (L-9175)
Gasification of lignite via reverse combustion linkage
and subsequent intense forward gasfication between two wells is
currently under study by the Petroleum Engineering Department at
Texas A & M University. Initial tests are planned for two wells
about 22.5 m (75 feet) apart. The gasifying agent to be used is
air, producing approximately 14,155 m3 (500,000 ft3) of gas per
day.
-161-
-------
Sandia Laboratories (L-1436)
Sandia Laboratories is conducting a project under the
sponsorship of ERDA to monitor the Hanna in-situ experiments.
It is expected that the results of this work can also be applied
to the high-Btu in-situ gasification project being conducted by
the Lawrence Livennore Laboratory.
Argonne National Laboratory (L-8585)
This project involves the investigation of reaction-
controlling variables and product distributions for the gasifica-
tion of both coals and chars utilizing steam and oxygen. Included
in this task is the investigation of the effects of using brackish
water as the water supply. ERDA is sponsoring this program.
West Virginia University (L-1436)
The University has been awarded two contracts totalling
$29,983 by the Bureau of Mines to conduct computer studies on in-
situ gasification.
Project Thunderbird (L-1436)
This was a U.S. Bureau of Mines in-situ gasification
feasibility study that was conducted from 1967 to 1969. Gasifi-
cation of 15-m .(50-ft) thick seams at a depth of 305 to 670 m
(1000-2200 ft) was the primary concern of this study. These
thick seams are considered uneconomical to mine.
A. D. Little Study (L-1436)
In 1972 A.D. Little reviewed available information in
order to evaluate the technical feasibility of in-situ gasification
of coal. A report based on the findings was published.
-162-
-------
APPENDIX H
-------
UCG PROJECTS OUTSIDE THE U.S.
The bulk of the work done outside the U.S. has been
conducted in the U.S.S.R. where underground coal gasification
has been under investigation since the 1930's. There are cur-
rently four or five electricity generating stations powered by
gas produced underground. Russian technology has been reviewed
in a report prepared by the Lawrence Livermore Laboratory under
contract to ERDA (L-8618). This document should be consulted
for information on Russian in-situ projects.
A three-year cooperative study between Belgium and West
Germany was recently announced (L-9176). The objective of this
work is to develop in-situ technology for utilization of the vast
coal resources located in. the West German Ruhr region through
northern Belgium arid the Netherlands. Initial tests involving
air combustion will probably get underway sometime in early 1978.
Air at pressures ranging from 20 to 50 atm will be injected into
coal seams about 1000 m deep. The anticipated heating value of
the product gas is between 100 and 140 Btu/scf. Application in
a combined-cycle system is being considered in order to obtain
the maximum energy usage efficiency. If the results are encourag-
ing, experiments substituting hydrogen for air may be attempted.
In Canada the governments of Alberta and British Columbia
are studying the feasibility of developing projects within their
provinces (L-1436). A test burn has been conducted but no details
are readily available at this time.
In the United Kingdon, the National Coal Board and the
C.E.G.B. (Central Electricity Generating Board) are also sponsor-
ing an evaluation of UCG. Pilot-scale trials in a 5-MW plant at
the Newman Spinney Station near Sheffield have been underway
-164-
-------
since 1957 (L-1436, L-8605, L-9176). A low-grade coal with high
mineral content is being gasified here.
Gasification of brown coal in northern Bohemia,
Czechoslovakia, has been under investigation since 1956. Follow-
ing several trial tests, plans were reported for application of
the basic technology (lateral gas removal) to an industrial-scale
project possibly in conjunction with a 220-MW power generating
unit. Purification of the crude gas involves tar and H2S removal.
Wastewater treatment includes NHa removal, phenol treatment by
butyl acetylate, and biological purification (L-4858, L-4860).
One of the aspects of UCG under study in Poland includes
control of roof behavior. Technologies involving air versus
oxygen blast have also been evaluated with respect to their
effects on void filling and roof control (L-9048).
Other UCG projects are currently underway in Germany,
France (Morroco), and other European countries. In addition,
Japanese literature published in the 1960's describes laboratory
studies of spontaneous combustion and underground gasification of
coal (L-5715, L-5718, L-8603, L-8604). A planned on-site test at
Sumitomo Coal Mining Co., Ltd., at Akadaira of Hokkaido was
described.
-165-
-------
BIBLIOGRAPHY
-------
BIBLIOGRAPHY
L-327 Campbell, G. G. , C. F. Brandenburg and R. M. Boyd,
Preliminary Evaluation of Underground Coal Gasifi-
cation at _ Hanna, Wyoming. Bureau of Mines Coal
Gasification Program Technical Progress Report 82.
Laramie, WY, Laramie Energy Research Center. October
1974.
L-683 Hughes, Evan E., Edward M. Dickson and Richard A.
Schmidt, Control of Environmental Impacts from Advanced
Energy Sources.Report No. PB-239 450, EPA-600/2-74-002,
EPA Contract No. 68-01-0483. Menlo Park, CA, Stanford
Research Inst., 1974.
L-727 Katz, Donald L., et al., Evaluation of Coal Conversion
Processes to Provide Clean Fuels.Final Report.Report
No. EPRI 206-0-0, PB-234 202 & 203. Ann Arbor, MI, Univ.
of Michigan, Col. of Engineering, 1974.
L-748 King, S. B., C. F. Brandenburg and. W. J. Lanum, "Char-
acterization of Nitrogen Compounds in Tar Produced from
Underground Coal Gasification", Amer. Chem. Soc., Div.
Fuel Chem. , Prepr. 20(2), 131-39 (1975)..
L-847 Miller, Stephen G., Environmental Impacts of Alternative
Conversion Processes~for Western Coal Development"
Washington, DC, Thomas E. Carroll Associates, October 1974.
L-871 Nadkarni, Ravindra M., Charles Bliss and William I. Watson,
"Underground Gasification of Coal", in Clean Fuels from
Coal Symposium Papers, Chicago, IL, September 1975~.
Chicago, IL, Inst. of Gas Technology, December 1973. p.
611-38.
L-1075 "Texas Utilities Will Try Russian Gasification Mode to
Hike Lignite Use", Electrical Week, 7 (24 March 1975).
L-1215 Mills, G. Alex, "Gas From Coal. Fuel of the Future",
Environ. Sci. Technol. 5(12), 1179-83 (1971).
L-1216 Nadkarni, Ravindra M., Charles Bliss and William I. Watson,
"Underground Gasification of Coal", Chem. Tech. 4(4), 230-
40 (1974).
-167-
-------
L-1326 Stephens, D. R., A. Pasternak and A. Maimoni, "The LLL
In-Situ Coal Gasification Program", in Proceedings -
Coal Utilization Symposium - Focus on S02 Emissions
Control, Louisville. KY, 22-24 October 1974.Monroeville,
PA, Bituminous Coal Research, 1974.p. 17-29.
L-1382 Fischer, D. D., and L. A. Schrider, "Comparison of Results
from Underground Coal Gasification and from a Stirred-Bed
Producer", Presented at the 79th National AIChE Meeting,
Houston, TX, 16-20 March 1975. Paper No. 26b.
L-1436 Howard-Smith, I., and G. J. Werner, Coal Conversion Tech-
nology. Park Ridge, NJ, Noyes Data Corp., 1976.
L-2116 Wallace, Robert T., "Energy: What are the Best Alterna-
tives?", Chem. Ens. 83(6), 121-25 (1976).
L-2151 Shuck, L. Z., and J. Pasini, III, "In-Situ Gasification
of Eastern Coals", Presented at the Coal Processing and
Conversion Symposium, Morgantown, WV, 2-3 June 1976.
L-2645 (Arthur D.) Little, Inc., A Current Appraisal of Under-
ground Coal Gasification. Bureau of Mines Report No.
OFR-11-72, PB-209 274, Contract No. SO-1111357. Cambridge,
MA, December 1971.
L-4674 Brandenburg, C. F., et al., Interpretation of Chemical
and Physical Measurements from an In-Situ Coal Gasifi-
cation Experiment^Report No. CONF-7509100-1. Presented
at the 50th Annual Fall Meeting of the Society of Petroleum
Engineers of AIME, Dallas, TX, 28 September - 1 October
1975. Paper No. SPE-5654..
L-4822 Fischer, D. D., C. F. Brandenburg and L. A. Schrider,
Energy Recovery from In-Situ Coal Gasification. Report
No. CONF-750306-2.Presented at the 15th Annual ASME
Symposium - In-Situ Fossil Fuel Recovery, Albuquerque, NM,
March 1975. Laramie, WY, Laramie Energy Research Center.
1975.
L-4858 Glivicky, 0., Results of Underground Brown-Coal Gasifi-
cation in North Bohemia^Report No. UCRL-Trans-10795.
Translated from Bergbautechnik 12(2). 99-101 (1962).
L-4860 Goergen, H., and K. Engin, Underground Gasification in the
Chomutpv Region. Report No. UCRL-Trans-10861.Translated
from Gluckauf-Forschungshefte 35(2). 76-78 (1974).
L-5480 Cavanaugh, E. C., et al., Atmospheric Pollution Potential
from Fossil Fuel Resource Extraction, Qn-Site Processing
and Transportation Final Report, January-December 1975?
Report No. PB-252 649, EPA-bOO/2-76-064, EPA Contract No.
68-02-1319. Austin, TX, Radian Corp., March 1976.
-168-
-------
L-5715 Hokao, Z., Basic Study of Underground Gasification of
Coal Using Oxygen. Report No. UCRL-Trans-10988.Trans-
lated from Nippon Kogyo Kaishi 7_7(881). 970-74 (1961).
L-5718 Nakamura, H., and S. Irie, Underground Gasification of
Coal. Report No. UCRL-Trans-10989.Translated from
Nenryo Kyokai-shi 44(462). 684-96 (1965).
L-5722 Estep-Barnes, P. A., and J. J. Kovach, Chemical and
Mineralogical Characterization of Core Samples from
Underground Coal Gasification Sites in Wyoming and
West Virginia.Report No. MERC/RI-75/2. Morgantown, WV,
Morgantown Energy Research Center, December 1975.
L-6631 Schrider, L. A., et al., "The Outlook for Underground Coal
Gasification", Presented at the 1975 Lignite Symposium,
Grand Forks, ND, May 1975.
L-6921 Brandenburg, Charles F., et al., "Underground Gasification
of a Subbituminous Coal", Amer. Chem. Soc., Div. Fuel Chem.,
Prepr. 20(2), 3-10 (1975).'
L-8300 Magee, R. A., R. M. Mann and R. V. Collins, Monitoring of
an In-Situ Gasification Test of the Linked Vertical Well
Concept. Final Report. ERDA Contract No. E(29-2)-3689 ,
Radian Project No. 200-138. Austin, TX, Radian Corp.,
September 1976.
L-8395 Sole, T. L., et al. , Hydrogeologic Assessment of an
Underground Coal Gasification Project Site Grant District
Wetzel Co., W. Va.Report No. MERC/TPR-76/5.Morgantown,
WV, Morgantown Energy Research Center, July 1976.
L-8520 Fischer, D. D., R. M. Boyd and L. A. Schrider, Environ-
mental Impact Studies Related to Underground Coal Gasiti-
cation.Report No. TID-27003.Laramie, WY, Laramie
Energy Research Center, April 1975.
L-8544 Mead, Warren, Draft Environmental Assessment of Application
by ERDA for a Special Land Use Permit_for Use of Public
Lands in Wyoming for In-Situ Coal Gasification Experiments.
Report No. UCID-17011.Livermore, CA, Univ. of California,
Lawrence Livermore Lab., January 1976.
L-8552 Brandenburg, C. F., et al., "Results and Status of the
Second Hanna In-Situ Coal Gasification Experiment", Pre-
sented at the Second Annual Underground Coal Gasification
Symposium, Morgantown, WV, 10-12 August 1976.
-169-
-------
L-8554 Fischer, Dennis D., "Monitoring of Emissions from an
In-Situ Coal Gasification Experiment", Presented at the
Second Annual Underground Coal Gasification Symposium,
Morgantown, WV, 10-12 August 1976.
L-8555 Fischer, Dennis D., et al., "Status of the Linked Vertical
Well Process in Underground Coal Gasification", Presented
at the Second Annual Underground Coal Gasification Sym-
posium, Morgantown, WV, 10-12 August 1976.
L-8557 Humphrey, A. E., et al., "Practical Considerations in
Designing an UCG Field Test", Presented at the Second
Annual Underground Coal Gasification Symposium, Morgantown,
WV, 10-12 August 1976.
L-8558 Stephens, D. R. , F. 0. Beane and R. W. Hill, "LLL In-Situ
Coal Gasification Program", Presented at the Second Annual
Underground Coal Gasification Symposium, Morgantown, WV,
10-12 August 1976.
L-8580 King, S. Bruce, "Composition of Selected Fractions from
Coal Tars Produced from an Underground Coal Gasification
Test", Preprint, Annual ACS Meeting, New Orleans, LA,
March 1977.
L-8581 Campbell, J. H., and H. Washington, "Preliminary Laboratory
and Modeling Studies on the Environmental Impact of 'In-
Situ' Coal Gasification", Preprint No. UCRL-78303. Pre-
sented at the Second Annual Underground Coal Gasification
Symposium, Morgantown, WV, 10-12 August 1976.
L-8582 Mead, Warren, ed., The Control of Gas and Liquid Effluents
During Hoe Creek Experiment #1.Report No. UCID-16984,
Contract No. W-7405-Eng-48.Livermore, CA, Univ. of
California, Lawrence Livermore Lab., 5 December 1975.
L-8585 Fischer, J., et al., Gasification of Chars Produced Under
Simulated In Situ Processing Conditions. Quarterly Report,
October - December 1975.Report No. ANL-76-3, ERDA
Contract No. W-31-109-Eng-38. Argonne, IL, Argonne
National Lab., 1975.
L-8603 Yanagimoto, T., M. Komatsu and A. Tomisaki, Spontaneous
Combustion and Underground Gasification of Coal: Coal-
Combustion Gas.Part I.Report No. UCRL-Trans-10990.
Translated from Kyushu Kozan Gakkai-shi 35(11), 421-29
(1967).
L-8604 Yanagimoto, T., A. Tomisaki and M. Komatsu, Spontaneous
Combustion and Underground Gasification of Coal: Coal-
Combustion Gas. Part III.Report No. UCRL-Trans-10992.
Translated from Kvushu Kozan Gakkai-shi 36(9), 307-14
(1968).
-170-
-------
L-8605
L-8617
L-8618
L-8730
L-9048
L-9118
L-9165
L-9166
L-9168
L-9L69
L-9170
A'> Utlc*e^round Fugl Gasification. Report No.
yCRL-Trans-iu^s. Translated from Tech. Apskats 35
lo-l/ (1962).
Douglas, George W., and Marvin D. McKinley, Second Semi-
Annual Report on Feasibility Studies of In-Situ Coal Gasifi-
cation in the Warrior Coal Field.BER Report No. 206-124.
Grant AER75-04512.University, AL, Univ."of Alabama, Col.
of Engineering, Bur. of Engineering Research, October 1976..
Gregg, D. W., R. W. Hill and D. U. Olness, An Overview of
the Soviet Effort in Underground Gasification of Coal.
Report No. UCRL-52004, ERDA Contract No. W-7405-Eng-48.
Livermore, CA, Lawrence Livermore Lab., Univ. of California,
29 January 1976.
Galland, J. M., and T. F. Edgar, Analysis and Modeling of
Underground Coal Gasification Systems. Energy Systems
Labs. Report No. ESL-13.Austin, TX, Univ. of Texas,
Dept. of Chemical Engineering, 1973.
Rauk, J., Roof Control in the Underground Gasification of
Tain Dipping Seams of Hard Coal.Report No.UCRL-Trans-
11028. Translated from Prze^TT Corn. 17(3), 163-70 (1961).
Decora, Andrew W., Internal Quarterly Progress Report,
July-September 19 76^Report No. LERC/QTR-76/3.Laramie,
WY/Laramie Energy Research Center, October 1976.
«
Texas Utilities Generating Company, Texas Water Quality
Board Application for In-Situ Mining Permit for Lignite
Gasification.Technical Report.Permit No. 02021.
Dallas, TX, 1976.
Texas Water Quality Board, Texas Utilities Generating Co.
In Situ Linkage Gasification Project File, TWQB Permit
No. 02021.
Edgar, Thomas F., In Situ Conversion of Texas Lignite to
Synthetic Fuels. Semi-Annual Report to the National
Science Foundation, Rann Division. Austin, TX, Univ. of
Texas, Dept. of Chemical Engineering, April 1975.
Edgar, Thomas F., W. R. Kaiser and T. W. Thompson, In Situ
Conversion of Texas Lignite to Synthetic Fuels. Semi-
Annual Report to the National Science Foundation, Rann
Division. Austin, TX, Univ. of Texas, Dept. of Chemical
Engineering, June 1976.
Fischer, Dennis D., Slide Presentation, Laramie, WY,
Laramie Energy Research Center, 1976.
-171-
-------
L-9171 "Underground Gasification Test Logs 8.5 Million cfd",
Coal Age 81(8), 29 (1976).
L-9176 "Underground Coal to be Gasified", Chem. Eng. News 54(50),
14 (1976).
-172-
-------
TECHNICAL REPORT DATA
(Please read Inunctions on the reverse before completing)
REPORT NO.
EPA-6QO/7-77-045
3. RECIPIENTS ACCESSION- NO,
4, TITLS AND SUBTITLE
In-situ Coal Gasification: Status of Technology and
Environmental Impact
5. REPORT DATS
May 1977
6. PERFORMING ORGANIZATION CODE
. AUTHORIS)
Nancy P. Philips and Charles A. Muela
S. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Radian Corporation
P.O. Box 9948
Austin, Texas 78766
10. PROGRAM ELEMENT NO.
E HE 62 3 A
11. CONTRACT/GRANT NO.
68-02-2147, Exhibit A
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Exhibit A; 10/76-2/77
14. SPONSORING AGENCY COD6
EPA/600/13
15.SUPPLEMENTARY.NOTES JERL-RTP project' officer for this report is William J. Rhodes,
Mail Drop 61, 919/549-8411 Ext 2851.
16. ABSTRACT
repor^ gives results of a. literature review and personal contacts to
ascertain, what is being done in in-situ coal gasification and to collect existing environ-
mental data. Study results indicate significant current interest and activity in the
development of in-situ coal gasification. The report presents a general description of
the chemistry, technology , and technological problems, along with detailed descrip-
tions of the technical objectives, approaches, and results of ongoing projects. This
presentation is used as a basis for summarizing the current state of knowledge regar-
ding environmental issues . Although some information exists in the areas of water
quality effects, air emissions, and ground subsidence, extensive additional work is
needed during the technology development in order to eliminate non-problems and
quantify real problems so that environmental control technology will be available when
needed.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPSN ENDED TERMS
c. COSATI Field/Group
Pollution
Coal Gasification
In Situ Combustion
Combustion
Environmental Engineering
Water Quality
Air Pollution
Subsidence
Pollution Control
Stationary Sources
Environmental Impact
13B
13H
21B,08I
05E
08M
13. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
185
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA form 2220-1 (9-73)
-173-
------- |