Basin Electric Power Cooperative said Dec. 6 that a scheduled fall maintenance outage is complete at the coal-fired Leland Olds Station, prepping the unit for the coming cold winter months and allowing first-time use of a new scrubber.
Unit 2 at the plant, located near Stanton, N.D., was taken out of service Sept. 8 so employees and contractors could perform maintenance and repairs to several systems. The unit’s new SO2 scrubber was commissioned during that time.
Mark Thompson, plant manager, said the boiler and turbine were inspected, maintained, and repaired as needed, as were valves, pumps, heaters and other balance-of-plant systems. “The high-pressure and intermediate-pressure turbine sections were disassembled for the first time in quite a while. Touch-up work was completed on the turbine blades. Inspections revealed no major issues,” Thompson said.
In addition to the maintenance work, Thompson said the final connection was made between Unit 2 and the new wet limestone flue gas desulfurization system, also known as a scrubber. The $410m scrubber uses limestone to remove SO2 from the flue gas. Unit 1 will be tied into the scrubber during a future maintenance outage.
Les Larson, Basin Electric senior mechanical engineer, who serves as project manager for the scrubber installation, said the final piece of ductwork connecting Unit 2 to the scrubber was lifted Oct. 10, and the first flue gas passed through the scrubber Oct. 29. “Startup of the scrubber equipment and systems was directed by the scrubber equipment supplier,” he said. “The scrubber is removing 98-99 percent of the sulfur dioxide from the flue gas.”
When Leland Olds Station Unit 1 went on-line in January 1966, it was the largest lignite-based power plant (222 MW) in the Western Hemisphere, Basin notes on its website. Leland Olds Station Unit 2, a 447-MW unit located adjacent to Unit 1, began commercial operation in December 1975. The majority of electricity produced at the Leland Olds Station is sent to substations near Fort Thompson and Watertown, S.D., for delivery to Basin Electric’s member systems. The plant normally burns about 3.3 million tons of lignite per year produced at the Freedom mine.
Says the website about the need for the new scrubber: “The Environmental Protection Agency’s Regional Haze Rule, which provides for improvements in visibility at our national parks and wilderness areas, requires greater emission control through the installation of best available retrofit technology (BART). The Leland Olds Station has always been in full compliance with all its federal and state environmental permits. By adding the scrubbers, Leland Olds will be in a better position to operate for an additional 20 to 30 years providing jobs and economic benefits to the area long into the future.”