Quashing Quicksilver

Mechanical Engineering, Nov 2005 by Winters, Jeffrey

Last March, the U.S. Environmental Protection Agency issued its first-ever restrictions on mercury emissions from coal-fired power plants. The new regulations, long opposed by the power industry, which feared the expense of control devices, order a 23 percent cut by 2010 and a nearly 69 percent reduction by 2018.

But meeting these goals may not be as costly and difficult as first thought, if research results from Lehigh University in Bethlehem, Pa., can be applied. In tests at three East Coast power plants, flue-gas emissions of mercury have been slashed by as much as 70 percent without depressing plant performance or boosting fuel costs.

The system under testing changes the operation within the boiler to promote the oxidation of mercury in the flue gas so that it can be absorbed in the fly ash. When oxidized in this way, the mercury can be readily captured by common pollution control equipment, such as scrubbers or filters.

One of the developers of the system, Carlos Romero of Lehigh's Energy Research Center, estimates that such a system could save a 250 MW coal-fired power plant as much as $2 million a year in mercury control costs.

The research will be published in an upcoming issue of the journal Fuel.

JEFFREY WINTERS