ADVANCED RESEARCH AND TECHNOLOGY DEVELOPMENT

FINE COAL UTILIZATION

Finely ground de-ashed coal (fine coal) is a new fuel form which has great potential to improve the utilization of coal in an

environmentally responsible manner. It is therefore important to perform research on the cleaning, gasification, and combustion of fine coal.

Biocleaning.

Several processes have been developed which utilize a wet
grinding process to manufacture fine coal. The resulting
product, fine coal in wet slurry form, is ideally suited for
microbial processing. A method for microbial removal of
sulfur and nitrogen pollutants from fine coal offers
significant advantages when compared to the conventional
chemical methods for on-stream gas phase removal of HS and
NH2 from fuel gas, or SOx and NOx from flue gas. Gas phase
processes that operate at elevated temperature (and possibly
pressure) are susceptible to process upsets, and must be
continuously operated on a real time process basis to be
fully effective.

On the other hand, microbial removal (Biocleaning) of
pollutants can be accomplished at low temperature and
pressure and can be operated totally independent from the
gasification or combustion process. In the event that a
relatively minor upset occurs in the Biocleaning process,
clean fuel feedstocks can be obtained from inventory with no
subsequent release of pollutants. The cost of chemicals
which are required for gas phase cleaning will also be
eliminated.

IGT is currently researching the microbial removal of sulfur
from fine coal. Most of the pyritic sulfur is physically
removed during fine coal production. Removal of the organic
sulfur as well may result in a product fuel which can be
gasified or combusted and meet New Source Performance
Standards (NSPS) without further processing. IGT recommends
that this program be continued and expanded to include
microbial denitrification as well.

Fine Coal Gasification:

Gasification of fine coal, which measures less than 40
microns, presents technical challenges totally different from
those addressed in the gasification of raw coal. IGT
recommends the investigation of a gasification process which
can utilize fine coal directly: internal recirculating
material, fluidized-bed (IRM bed).

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Fluidized-bed processes, which are favored for coal
gasification because of their high throughput and thermal
efficiency can not process coal particles smaller than 40
microns. A feedstock such as fine coal, which is composed
entirely of very fine particles, will not remain in the
fluidized-bed for sufficient residence time required for
complete gasification. IGT has developed the IRM bed which
is designed to process ultra fine particles. An inert
material (sand) is recirculated within the bed. This serves
to hold the fine coal in the bed for sufficient residence
time, while promoting mixing and efficient heat transfer.
IGT recommends that a research program be conducted in an
existing, process research-scale IRM bed to determine the
effect of various operating parameters on the gasification of
fine coal.

Fine Coal Combustion:

Burn profiles of various fine coals which have been
microbially treated for desulfurization and/or

denitrification should be generated to provide a comparison
of coal combustion characteristics. IGT recommends a

laboratory-scale research program to provide basic data
required to evaluate the use of fine, microbially-treated
coal for combustion.

IGT recommends $2.0 million to investigate biocleaning, the
IRM bed, and burn profiles to increase the utilization of
fine coal as a new fuel form.

SURFACE COAL GASIFICATION

POLLUTION ABATEMENT:

More efficient, cost effective gas processing plants for surface coal gasification are needed. Typically, over 30% of the cost of an integrated coal gasification facility is attributable to the gas purification facilities.

These facilities are composed primarily of particulate removal, waste heat recovery, gas upgrading, and pollution abatement systems. Ideally, the development of a new gas processing configuration will include efficient particulate removal and internal recycling and destruction of pollutants which remain after primary treatment. recovery of these remaining pollutants is currently accomplished in secondary removal systems which are extremely expensive to operate because of the dilute content of the pollutants in the gas stream.

The

The

IGT has developed a concept for an Advanced Gas Treatment (AGT) system, which addresses both particulate removal and pollutant recycle. development of this system will result in a highly efficient, dramatically simplified gas processing plant, which could be applied to

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any gasifier system for any application (chemicals production or power generation).

Particulate Removal:

Gas turbines or other downstream process equipment require a
very low particulate level in the gas stream to prevent
shortened equipment life. Conventionally, cyclones are used
to remove most of the particulate matter from the gas stream.
However, cyclones alone do not provide sufficient particulate
removal. IGT has tested a novel ceramic filter and has found
that operation of the ceramic filter in conjunction with
cyclones results in virtually complete removal of
particulates. Ceramic filters must be operated cyclically to
allow for filter cleaning, therefore, cycle time is an
important factor in the life and cost of a ceramic filter
system. Tests performed at IGT have also shown that the
placement of baffles in a fluidized-bed can reduce the amount
of particulates. It appears that the integration of in-bed
baffles, cyclones, and ceramic filters will result in very
high particulate removal efficiency and longer equipment
life. IGT recommends a research program which will include
modification of an existing process research unit and the
collection of data on the efficiency of a particulate removal
system consisting of in-bed baffles, cyclones and ceramic
filters.

Pollutant Recycle:

Pollution abatement facilities for coal gasification plants
include separate systems for removal of ammonia and hydrogen
sulfide from the product gas, as well as systems to recover
anhydrous ammonia and to convert hydrogen sulfide to a
saleable by-product (usually elemental sulfur). In the case
of hydrogen sulfide conversion to sulfur, a tail gas is
formed which contains hydrogen sulfide and sulfur dioxide in
sufficient quantity to require secondary treatment.
Conventional pollution abatement processes are expensive to
operate and are often susceptible to upsets which result in
unacceptable levels of sulfur and nitrogen compounds in the
product gas. It is extremely desirable to develop a simpler
pollution abatement system which can be used for all
coal gasifiers regardless of configuration or operating
pressure.

IGT has developed a concept for total recycle and destruction of all pollutants which would entirely eliminate the conventional ammonia removal, ammonia recovery, and secondary system for the removal of hydrogen sulfide and sulfur dioxide from tail gas formed during sulfur recovery.

This system consists of a water scrubber located directly
after the particulate removal system and waste heat boiler.

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The water scrub will remove ammonia from the product gas, and
because the gas temperature is lowered, polycyclic and
polynuclear aromatic compounds and light oils will also
The water from the scrubber will
condense and be removed.

then be steam stripped to remove the pollutants, which are
once again in a gaseous form much more concentrated than they
were in the original coal gas stream.

This concentrated stream, together with the hydrogen sulfide-
and sulfur dioxide-containing sulfur plant tail gas stream
will be recycled to the gasifier at a point where reducing
Sulfur dioxide will be converted back to
conditions prevail.
hydrogen sulfide, to be removed in the conventional sulfur
Ammonia, light oils, and heavier
removal system downstream.
hydrocarbons will crack to lighter gases, including methane.
At equilibrium, a clean gas stream which is acceptable for
either power generation or chemicals production is produced.

pressure.

Pollutant recycle systems previously considered have involved
the recycle of sulfur pollutants only, and only at low
The proposed system handles all pollutant streams;
This greatly reduces
ammonia, sulfur, tars, and light oils.
overall plant complexity and reduces capital and operating

costs.

IGT recommends $3.8 million to test pollutant recycle and
particulate removal at 500 psi pressure in an existing PDU.

RESEARCH ON ASH CHEMISTRY AND FLUIDIZATION BEHAVIOR

It is important to continue basic research activities to provide the data on coal ash chemistry and fluidization behavior which is necessary Because gasification models input for accurate gasification models. are a cost effective means of simulating the effects of varying process parameters and feedstocks on gasifier performance and product quality, it is desirable to refine these models as much as possible.

IGT is currently performing research in both ash chemistry and The results of these programs provide data to fluidization behavior. all fluidized-bed gasification processes.

Ash Chemistry:

IGT is currently performing research utilizing a hot stage microscope with a video camera and a penetration viscometer designed and built by IGT expressly for this program to examine the mechanisins of ash formation for a wide variety of coal chars and to determine ash properties.

The coupling of the video camera and the hot stage microscope permits direct, visual observation of ash fusion, while the penetration viscometer provides data which aid the understanding of ash agglomeration behavior.

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Fluidization Behavior:

IGT is currently operating an advanced multi-purpose research reactor to determine the behavior of both coal and ash particles in a fluidized-bed. Basic data on the interaction of the particles with fluidizing gas jets, other particles in the bed, and mechanical devices such as cyclones is being determined in this program.

IGT recommends $2.0 million in FY '87 for the continuation of the ash chemistry and fluidization behavior research programs which provide fundamental data necessary for better understanding of fluidized-bed, coal gasification processes.

UNCONVENTIONAL GAS

Geopressured/Geothermal Energy:

Geopressured/geothermal energy involves the coproduction of natural gas and hot brine. It is well known that there are thousands of TCF of methane in the ground in conjunction with geopressured reservoirs. In order to produce cost competitive natural gas, and thus attract commercial risk capital, there re technical issues that need to be resolved. The Department of Energy currently has underway as part of its geopressured resources program, a research project involving specially drilled geopressured/geothermal wells in the Texas/Louisiana Gulf Coast area. This project includes production testing coupled with scientifically sound data collection and analysis necessary to determine:

* the quantity of hydrocarbons produced with the brine

* the thermal and hydraulic energy content of the produced brine

the best methods to produce electricity from both the hydrocarbons and the energy content of the brine

* optimum techniques to treat the brine to inhibit corrosion and scale formation, remove solids, and dispose of the produced brine in a environmentally sound manner.

This project will provide information which will be available to industry and, therefore, lower the perceived risks associated with development of this important resource.

IGT recommends $4.2 million be provided to continue funding the existing DOE contract in which three field wells, Pleasant Bayou, Hulin, and Gladys McCall, will be used to resolve technical issues on production of hydrocarbons and brine, and generation of electricity using the energy content of the produced fluids, thus reducing the risk currently inhibiting industrial development of this valuable resource.

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