New air controls at Boswell 4 are done; final tune-up taking place

Construction on new air emissions controls for the coal-fired Boswell Unit 4 is substantially complete, the unit came back into operation on Oct. 24 after an outage that began Aug. 15 to tie in the new air controls, and the project due for an in-service date of Dec. 31.

Unit co-owner WPPI Energy supplied that information on Dec. 2 to the Public Service Commission of Wisconsin in a quarterly project update. The commission had granted WPPI a Certificate of Authority for the project in February 2013.

Testing and tuning of the NID scrubber system is in progress, with completion expected by the end of December, WPPI noted in the brief filing. WPPI owns 20% of the unit.

Minnesota Power is the other co-owner of the unit (at 80%), located in Minnesota. The Boswell 4 project is a multi-pollutant solution for reducing mercury, particulate matter (PM), SO2 and other hazardous air pollutants being addressed by U.S. Environmental Protection Agency regulations while also reducing plant wastewater. The units owners installed a semi-dry flue gas desulfurization system, fabric filter and powder activated carbon (PAC) injection system.

Minnesota Power installed Alstom’s circulating dry scrubber (CDS) technology, referred to as the NID system, for the removal of PM, SO2, acid gases including hydrochloric acid and trace metals, and other hazardous air pollutants being addressed by EPA regulations, while also reducing plant wastewater.

Boswell is a four-unit plant. Units 1 and 2 started producing power in 1958 and 1960. They were joined in 1973 by Unit 3 and in 1980 by Unit 4. Units 1 and 2 are 65 MW each, while Unit 3 is 355 MW and Unit 4 is 585 MW.

U.S. Energy Information Administration data shows that coal suppliers to the Boswell plant earlier this year were mines in the Powder River Basin, including Arch Coal‘s Black Thunder mine in Wyoming, Peabody Energy‘s North Antelope Rochelle mine in Wyoming and Cloud Peak Energy‘s Antelope mine in Wyoming and Spring Creek mine in Montana.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.