OCTOBER 19-20, 2012 - YMCA University of Science & Technology

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
Clean coal technology usually addresses atmospheric problems resulting from burning coal. The primary focus
was on sulfur dioxide and particulates, since it is the most important gas in the causation of acid rain. More
recent focus has been on carbon dioxide (due to its impact on global warming) as well as other pollutants.
Concerns exist regarding the economic viability of these technologies and the time frame of delivery, potentially
high hidden economic costs in terms of social and environmental damage, and the costs and viability of
disposing of removed carbon and other toxic matter.
Coal, which is primarily used for the generation of electricity, is the largest domestic contributor to carbon
dioxide emissions . The public has become more concerned about global warming through Intergovernmental
Panel On Climate Change(IPCC). The facility captures Carbon dioxide(CO 2) and acid rain producing sulfides,
separates them, and compresses the CO 2 into liquid. Plans are to inject the CO 2 into depleted natural gas fields
or other geological formations[1]. This technology is considered not to be a final solution for CO 2 reduction in
the atmosphere, but provides as an achievable solution in the near term with more desirable alternative
solutions to power generation which can be made economically practical.
Proposed Clean Coal Technology(CCT) Roadmap by DST in 11 th ,12 th
and 13 th Five Year Plans are as follows:
Near Term( up to 2012): Improved coal recovery , Coal Beneficiation , Reduction in Cost .
More emphasis on fluidised bed combustion (FBC), super critical power plant boilers, Integrated Gasification
Combined Cycle(IGCC) Demonstration.
Enhanced energy recovery from coal: CoalBedMethane(CBM),CoalMineMethane(CMM) etc. Pilot scale studies
on coal liquefaction.
Medium Term ( 2012 – 2017) : IGCC, PFBC, Ultra super critical power plants(USCP) , enhanced energy
recovery from coal, CBM , Commercial scale coal liquefaction , Zero Emission technologies(ZET)(pilot scale),
Carbon sequestration(pilot scale).
Long Term ( 2017 and beyond) : Zero Emission Technologies(Commercialisation),Carbon Sequestration
(demonstration plant) , IGFC and production of Hydrogen fuels from Coal.
Coal Power
The clean coal technology is of the utmost importance because: (i) coal is abundant and will remain a major
source of energy for future years, (ii) emission from coal based generation is a matter of serious concern.
Thus, clean coal research has begun to:
•Improve the quality of non-coking coal at the pre-combustion stage for use in power generation by value
addition,
•Adopt new coal combustion and conversion technologies for improving efficiency of coal utilization, and
•Reduce carbon dioxide and other pollutant emissions in the environment through Renovation and
Modernization(R&M).
Coal usually occurs as large-size shales of 200 mm, found at up to 500 m depth and has mineral or inorganic
matter as extraneous and inherent impurities, which needs to be removed. For commercial applications, high
grade coal is a preferred option, but it is generally low grade coals that are available in large quantities. Hence,
technology advancements are taking place in the use of low grade coals.
Clean coal technologies are categorized into: (i) Coal beneficiation, (ii) Coal conversion
(iii)Coal combustion , and (iv) Post-combustion.
2(a) Coal Beneficiation Technology
Coal beneficiation enables value addition in coal, mainly by reducing the percentage of ash generated on
combustion. Each type of coal has its own ‘washability’ criteria, depending on the chemical composition of coal.
Extraneous impurities are easier to remove by mechanical means as the specific gravity of coal is lower than the
impurities, so that upon washing, these impurities sink while the coal floats on the water surface. However, a part
of extraneous impurities is intimately inter-meshed with ROM coal and is difficult to remove only by mechanical
means. It requires chemical and biological methods of cleaning. Therefore, both dry and wet coal beneficiation
technologies have evolved. Coal is broken down into specified sizes according to the washing technology
applicable. Coarse coal is handled by dry separation in air jigs or hydraulic jigs, while cyclones and
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