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The Kingsport, Tenn., clean coal project operated virtually flawlessly throughout its demonstration period and continues its steady operations today. |
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KINGSPORT, TN - It was 35 years ago that
a single word in the smash hit, coming-of-age movie
The Graduate made cinema history: "plastics." As a
baby-faced Dustin Hoffman learned, the future was
"plastics."
Now, largely because of one of the Department of
Energy's most successful Clean Coal Technology projects,
in the next 35 years, the future may well be
"plastics?from coal."
Air Products Liquid Phase Conversion Company, L.P., a
partnership between Air Products and Chemicals, Inc.
(Air Products), and Eastman Chemical Company (Eastman),
has successfully completed a nearly 11-year project to
demonstrate an advanced method for making methanol from
coal. Eastman uses the methanol as a chemical "building
block" for a wide range of consumer products, from the
plastics of toothbrush handles to the celluloid of
photographic film.
The 69-month government co-funded operating period
ended as trouble-free as it began. Since April 1997,
when the Liquid Phase Methanol (LPMEOHTM)
process began its first test runs at Eastman Kingsport,
Tenn. chemicals-from-coal complex, the demonstration
facility has operated with a remarkable on-stream
availability of 97.5 percent, the best of any of the
original Clean Coal Technology projects co-funded by the
Energy Department in the late 1980s and early 1990s.
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The slurry bubble column reactor differentiates
the liquid phase methanol synthesis process from
conventional technology.
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During its demonstration period, the facility
produced nearly 104 million gallons of methanol from
coal gas with a demonstrated plant capacity in excess of
300 tons of methanol per day, more than 15 percent
greater than the plant's design rate.
As a result, Eastman is continuing to use the
technology to provide a portion of its chemical methanol
feedstock requirements, making the project another of
the Energy Department's clean coal commercial "success
stories."
The demonstration effort was the result of a $213.7
million cooperative agreement awarded to the Air
Products and Eastman partnership by the Energy
Department. The federal government provided $92.7
million while the partnership contributed nearly $121
million. The project was one of 38 joint
government-industry clean coal technology demonstration
ventures funded by the Energy Department in a program
originally begun during the Reagan Administration.
Besides being a current success story, the technology
could also offer a preview of future coal plants. One of
the Energy Department's top priorities is to develop a
"multi-product" coal plant - a plant that would
co-produce hydrogen and other chemical compounds
simultaneously with the generation of electricity.
President Bush recently announced plans to build an
emission-free coal plant, named FutureGen, that
would employ the "multi-product" concept.
Prior to the project, Eastman Chemical made methanol
using coal or synthesis gas from its Coal Gasification
Facility. The synthesis gas was reacted to methanol in a
fixed catalyst bed reactor. The Clean Coal Technology
project demonstrated a new and more effective way to
carry out the coal gas-to-methanol synthesis step with
greatly enhanced feedstock flexibility.
A joint Air Products-Department of Energy research
project in the 1980s had showed how the process could be
improved by suspending the catalyst in an inert mineral
oil and bubbling the coal gases through the slurry.
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Tomorrow's
Multi-Product Coal Plant... In
Kingsport, Tenn., coal is being gasified and the
gases used to make chemicals. In Tampa, Fla., and
West Terre Haute, Ind., coal is gasified and the
gases used to generate electricity. The ideal coal
plant of the future might do both.
Coal gasifiers blast coal with steam and either
air or oxygen to break it down into a rich mix of
carbon and hydrogen gases. Gasifiers operate best
when they run at a steady pace. Gas turbines, which
combust the coal gases to generate electricity, can
"load follow," or cycle up and down to meet
fluctuations in power demand.
A future coal power plant might use the coal gas
not required by the turbine during low electricity
demand to make methanol. The methanol could be
stored and used later as a turbine fuel during peak
demand, or it could be marketed separately. |
The "slurry bubble column" offered several advantages
to the gas phase process. The mineral oil helps
dissipate the heat created by the synthesis
gas-to-methanol reaction, helping protect the catalyst
and prolonging its life. The liquid phase process is
also capable of processing a wide variety of feedstock
gases from a coal gasifier more efficiently, converting
more of the gas to methanol per pass than its
conventional counterpart. Moreover, the methanol
produced was a higher quality product - generally
greater than 97 percent pure with only one percent water
by weight when high carbon oxides feedstocks are used.
The gas-phase process, by contrast, generally yields a
methanol product containing from 4 to 20 percent water
by weight and requires a balanced gas feedstock (a
unique stoichiometric ratio of carbon oxides and
hydrogen).
On December 19, 1989, the Energy Department announced
that a proposal by Air Products to scale up the LPMEOHTM
process to full commercial size had been selected for
government co-funding. A cooperative agreement,
outlining plans for the project and government-industry
cost-sharing arrangements, was awarded on October 18,
1992. Plant construction began in October 1995.
The first production of methanol occurred on April 2,
1997, and stable operations were achieved only four days
later. During a key part of the demonstration phase,
from 1998 through 2000, the plant's operational
reliability topped 99 percent.
Aside from providing a chemical feedstock for
Eastman, some methanol from the demonstration unit was
made available to seven test locations to study whether
coal-derived methanol, free of sulfur and other
impurities, could replace petroleum in transportation,
or be used as a peaking fuel in combustion turbines, or
supply a source of hydrogen for fuel cells. Test results
indicate that stabilized (as-produced) methanol from the
process can be used directly in fuel flexible vehicles,
gas turbines, and diesel generators with little to no
penalty on performance or fuel economy. However,
purification of the methanol (similar to gas-phase
systems) is needed if it is to be a source of hydrogen
for a phosphoric acid fuel cell.
Successful demonstration of the LPMEOHTM
technology, and the application of methanol to
transportation and power generation systems, adds
significant flexibility and dispatch benefits to
integrated gasification combined cycle electric power
plants. These facilities have traditionally been viewed
as strictly baseload power generation technology. Now,
central clean coal technology processing plants, making
coproducts of electricity and methanol, could
simultaneously meet the needs of local communities for
dispersed power, transportation fuels and manufactured
chemical products.
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