For a Clean Burn

mechanical engineering power 2002

for a clean burn

An energy co-op in a leading coal state will try a CFB.

by Harry Hutchinson, Executive Editor

A power producer in one of the top coal areas of the United States will test a cleaner method of using the local energy resource in a couple of years. The East Kentucky Power Cooperative has ordered a circulating fluidized bed boiler for a new, third unit at its Spurlock power station near Maysville, Ky.

The older units at Spurlock burn pulverized coal and have a combined capacity of more than 800 megawatts. The CFB unit, which also will burn coal from Kentucky mines, will be rated at 268 MW. It is the co-op's first circulating fluidized bed and will likely fire up in late 2004. At last check, East Kentucky Power was waiting for the state to approve the final air permit.

Coal may not have the appeal of a bluegrass meadow or the cachet of racehorses, but it is a main prop of Kentucky's economy. The state trails only Wyoming and West Virginia in production, and gets more than 95 percent of its electricity from burning coal. The legislature has recommended that permitting decisions for new plants take into account the fuel source and give points to those burning Kentucky coal.

According to Annette DuPont-Ewing, executive director of Gov. Paul Patton's Energy Policy Advisory Board, out of 29 proposals for new power plants in the state, six would burn coal. Four of those are only in the planning stage, she said.

The East Kentucky Power Cooperative's Spurlock plant near Maysville, Ky., will get a third generating unit fired by a circulating fluidized bed.

The East Kentucky co-op has hired Alstom to supply the boiler and to build the unit. The supplier said that it has delivered 84 CFBs, with a total capacity of 8,000 MW, since 1986. Alstom said that the fluidized beds allow the clean burning of a variety of fuels, from biomass to hard and soft coals, petroleum coke, and coal washery wastes. According to Alstom, the new unit at Spurlock will include a system called a Flash Dryer Absorber, which combines several flue gas desulfurization functions and will remove almost 98 percent of the sulfur from the coal.

East Kentucky Power said the pulverized coal boilers at Spurlock use selective catalytic reduction to curb NO_x emissions, and SO₂ is kept down by using only low-sulfur coals. Electrostatic precipitators keep particulate emissions "very low," a spokesman said.

The co-op predicted the new unit "will meet the NO_x emissions of the existing pulverized coal fired boilers with SCRs." The expected big difference is in SO₂ emissions, which are expected to be about six times less than the current units can get by burning low-sulfur coal.

Unit 3's performance on particulate emissions will be at least as good as that of Units 1 and 2, the spokesman said, and may be better.

A site near the co-op's Smith peaking station, a gas-fueled plant in Trapp, Ky., may one day host a more ambitious
trial of advanced coal technology. Kentucky Pioneer Energy LLC of Cincinnati is leading a project that plans an integrated gasification combined-cycle plant there.

The technology comes from the U.S. Department of Energy's programs for the future of fossil fuels. A gasification plant feeds its product to a neighboring power plant. The synthetic gas fuels turbines to produce electricity. The turbine exhaust enters a heat recovery boiler that produces steam to run a second bank of turbines, for a second kick from the first burn.

Kentucky Pioneer expects the project, which is still in the conceptual stage, to generate 400 MW from the two cycles and then get 2 MW more by running coal gas through a molten carbonate fuel cell.