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Background |
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Note that changing the coal preparation processes can
result in changes in the quantity, and sometimes the quality, of the
eventual coal combustion products (CCPs). This in turn may affect the
marketability of the CCPs. More information on CCPs and their potential
contributions to GHG reductions may be found under the topic of
Coal Combustion Products.
Coal contains varying amounts of rock and
other impurities that become part of the mined product, and significant
amounts of underlying and overlying materials are often mined in the process.
To remove these ash and sulfur impurities and to increase the coal's heating
value, much of the U.S. steam coal supply is cleaned, particularly bituminous
coals in the eastern U.S. Coal cleaning techniques range from simple washing
with water and mechanical separation of waste products to advanced chemical
cleaning processes. Utilities burning cleaned coal often find that the savings
it offers in transportation costs, fuel handling, plant efficiency,
availability, and environmental controls compensate for the added cost.
Coal water slurry
technologies provide a means for generating a useful, cost-effective fuel
from currently discarded coal fines that are created during cleaning
operations. This technology also provides better control of combustion
processes inside the furnace and offers the potential of reducing start-up
costs by partially replacing oil. Reduced emissions are possible due to the
composition of the slurry.
Improved coal quality can
result in:
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Reduced coal transportation costs and
fewer transportation emissions of
CO2, because less ash and
more Btu per pound are being transported to the power plant |
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Reduced coal handling equipment
maintenance costs, because there will be less hard, abrasive material
to grind and pulverize |
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Reduced combustion waste products
transportation costs, and fewer transportation emissions of
CO2
because of the reduction in the volume of waste materials being
transported from power plants to disposal sites |
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Reduced ash handling equipment
maintenance costs, because there will be reduced ash volume |
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Reduced ash leachate control and
disposal costs due to reduction in pyrites and other wastes |
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Reduced coal pile leachate and storm
water runoff control costs due to a reduction in the concentration of
pollutant originally in the coal |
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Increased boiler
availability, efficiency, and life expectancy, because of reduced slagging,
fouling, corrosion, and erosion |
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Reduced particulate and
SO2 control operating and maintenance costs, because of the
reduced ash and sulfur content |
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Power Partners℠
Projects |
Great River Energy (GRE)
will soon begin a full-scale, advanced clean
coal technology demonstration at its Coal Creek Station in North Dakota as
part of the Clean Coal Power Initiative (CCPI) with industry and DOE. The
thermal coal drying project will capture and reuse excess heat to dry the
coal, increasing its heating value and resulting in an estimated increase in
efficiency of about five percent.
Great River Energy (GRE) will
supply the energy to fuel a 50-million gallon ethanol plant adjacent to its
Coal Creek Station in Underwood, North Dakota. Sixty percent of the energy
for the Blue Flint Ethanol facility, co-owned and operated by Headwaters,
Incorporated, will come from waste steam generated by GRE’s Coal Creek
Station, reducing energy costs and GHG
emissions.
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References, Sources,
and
Other
Useful Data |
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Taylor & Francis Group (UK),
"International Journal of Coal Preparation and Utilization" (formerly "Coal
Preparation")
http://www.tandf.co.uk/journals/titles/07349343.asp
International Journal of Coal Preparation and Utilization publishes
original research papers, short communications, review articles, book
reviews, and symposium announcements covering all aspects of coal
preparation. The journal is significant reading for all individuals involved
with coal preparation, including those in operations, engineering,
management, education, and scientific research. Topics include: coal
properties and coal petrography; coal quality and characterization; surface
chemistry of coal and minerals; crushing, grinding and liberation; coal
screening and classification; dense medium and density separations; froth
flotation and oil agglomeration; process control and optimization;
flocculation and thickening; dewatering and thermal drying; briquetting and
pelletizing; coal handling and storage; coal utilization and blending; waste
disposal and pollution; utility waste product utilization; and carbon based
material. Additional subjects covered by the journal include properties of
coal/water and coal/oil slurries as well as the processing of oil shales and
tarsands by physical and physiochemical methods.
U.S. Department of Energy,
National Energy Technology Laboratory, “Development of a Coal Quality
Expert™: A DOE Assessment" (DOE/NETL-2001/1133, November 2000)
http://www.netl.doe.gov/technologies/coalpower/cctc/resources/pdfs/cqe/CQE_assess.pdf
The goal of this project was
to deliver a software tool for utilities, coal producers, and equipment
manufacturers that could analyze the impacts of coal quality, capital
improvements, operational changes, and/or environmental compliance
alternatives on power plant emissions, performance, and production costs.
This software was named the Coal Quality Expert (CQE™). A CQE™ beta version
was released in May 1995 and evaluated by several utilities by July 1995.
Version 1.1 was released in June 1996. CQE™ has been distributed to about 25
utilities in the United States and one in the United Kingdom through
membership in EPRI.
U.S. Department of Energy, National Energy
Technology Laboratory, “Clean
Coal Demonstrations:
Coal Treatments & Processes for Upgrading,
Removal of Sulfur & Other Impurities, Etc.”
http://www.netl.doe.gov/technologies/coalpower/cctc/cctdp/bibliography/misc/bibm_ctpursi.html
This document provides a list
of over 20 links to reports and newsletters related to coal cleaning.
U.S. Department of State, "Asia-Pacific
Partnership on Clean Development and Climate: Coal Mining Task Force Summary
of Action Plan and Projects”
http://www.state.gov/g/oes/rls/fs/2006/75376.htm
The Asia-Pacific Partnership
on Clean Development and Climate (APP) is a unique public-private initiative
among government and private sector partners from Australia, China, India,
Japan, the Republic of Korea and the United States. The Coal Mining Task
Force’s goal is to promote sustainable mining practices through improved
coal preparation (beneficiation), methane capture from active and abandoned
coal mines, underground coal gasification, and improved mine health and
safety. To meet this goal the Task Force has developed 16 initial projects
and activities. Coal beneficiation prepares coal for the intended end use by
removing or reducing impurities that interfere with clean combustion. This
process reduces the ash content of coal, thereby improving power plant
efficiency and reducing air emissions, coal transportation costs, power
plant maintenance costs, and ash disposal. This process can potentially
remove between 40-50 percent of the total sulfur, leading to a 20-25 percent
reduction in emissions of sulfur dioxide. The United States is leading the
Coal Mining Task Force in facilitating technology transfer through
workshops, demonstrations, and site visits among Partner countries to
improve coal quality, increase recovery, and reduce costs.
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