The Department of Environmental Protection this week approved Reliant Energy Northeast Management Co.’s plan to install a scrubber on each of the two boilers at its Keystone Power Plant in Plumcreek Township, Armstrong County.

Reliant intends to sell the gypsum produced by the contaminant removal process at the Keystone plant, a 1,700-megawatt pulverized coal-fired electric generating facility, to off-site customers.

Scrubbers, also known as wet flue gas desulfurization systems, reduce the amount of sulfur dioxide and particulate matter emitted from power plants. After the scrubbers are installed, the Keystone station will cut 170,000 tons of sulfur dioxide and 1,600 tons of particulate matter from its emissions each year.

"These sharp reductions illustrate how investment into existing power production facilities can result in significant air quality improvements in southwestern Pennsylvania," DEP Regional Director Kenneth Bowman said.

Scrubbers remove contaminants by forcing the flue gas through an absorber vessel before spraying it with a water slurry containing limestone. The calcium in the slurry reacts with the sulfur dioxide to form calcium sulfate, which is mixed with oxygen to create synthetic gypsum.

The remaining flue gas is passed through a mist eliminator, which removes any liquid and particulate matter trapped within the liquid from the gas. The flue gas then is exhausted to the stack and released.

Reliant Energy projects that the scrubber will be constructed and in operation by January 2009.

Links: Reliant Energy Invests $250 Million at Cheswick Plant

PPL Plant to Turn Scrubber Sludge Into Wall Board

Bruce Mansfield Plant Turns Scrubber Sludge Into Gypsum

DEP Issues National Gypsum Plan Approval for Scrubber Sludge Plant (1998)

12/8/2006