Technology for Controlling Mercury Emissions from Coal-Fired Power Plans in Illinois: Draft

              DRAFT
Technology for Controlling Mercury Emissions from Coal-Fired Power
Plants in Illinois
The mercury emissions from a coal-fired power plant are the result of the mercury
content in the coal that is burned and the extent that processes in the boiler prevent the
mercury from being released with the exhaust gases of the power plant. Mercury can be
removed from the coal prior to combustion of the coal. This may be achieved by coal
cleaning or by some other treatment of the coal. Or, mercury can be removed from the
boiler flue gases by air pollution control (APC) equipment. Sometimes the APC
equipment that removes the mercury is equipment that is installed primarily to remove
other pollutants, such as particle matter (PM) or acid gases in a flue gas desulfurization
system (FGD). These are called co-benefit mercury removal. Mercury may also be
removed by pollution control systems that are specifically designed to remove mercury
from the flue gases.
Mercury emissions control technology is a rapidly developing field. New developments
continually improve capabilities to reduce mercury emissions from coal-fired power
plants. The following sections address a current understanding of how mercury
emissions from Illinois coal-fired power plants may be controlled.
Mercury Removal from Coal
Run of mine (ROM) bituminous coal is frequently cleaned for the following purposes:
• Removal of impurities to improve the heating value of the coal
• Reduction of transportation costs for coal to the power plant and ash from the
power plant
• Maintenance of ash content in coal supply within contract requirements
• Removal of sulfur, mainly as pyrites, lowering SO2 emissions when the coal is
burned.
However, cleaning ROM coal will provide the added benefit of removing mercury from
the coal. This is because mercury in the coal is preferentially associated with pyrites and