Dairyland seeks permit for new air controls at Alma plant site

Dairyland Power Cooperative is permitting new air emissions controls for its coal-fired Alma power plant site in Buffalo County, Wisc., which includes the Alma and John P. Madgett (JPM) stations.

Dairyland submitted to the state Department of Natural Resources (DNR) a permit application, including plans and specifications for construction of emission control equipment including:

  • dry sorbent injection (DSI) and activated carbon injection (ACI) systems and a baghouse for Boiler B23 (Unit 4) and Boiler B24 (Unit 5); and
  • a DSI system, an ACI system and selective catalytic reduction (SCR) for Boiler B25 (the JPM boiler).

The DNR said in a June 8 notice that it has made a preliminary determination that the application meets state and federal air pollution control requirements and that the permit should be approved. Interested persons wishing to submit written comments on the application, or DNR’s review of it, should do so within 30 days of publication of the notice. A public hearing will be held July 8 in Alma, Wisc.

The existing electrostatic precipitators (ESPs) on A4 and A5 will also be converted to a fabric filter baghouse system as part of this project. No change is proposed to be made to the combustion portion of each boiler, and there will be no increase in the heat input to each of these boilers.

The DSI systems will reduce SO2 emissions from the boilers. In addition, it is expected that DSI, in conjunction with the fabric filter baghouses will also reduce the emissions of acid aerosols and toxic metals from the boiler stacks. The ACI systems are designed to reduce mercury (Hg) emissions from the boilers. The SCR system will reduce NOx emissions from the JPM boiler.

JPM is a Riley pulverized coal turbo-fired boiler that began operation in 1979. Subbituminous coal is the primary fuel, with distillate oil used for unit startup and flame stabilization. The boiler has a heat input based on the most recent Uniform Rating of Generation Equipment test of 4077.6 mmBtu/hour, and a recent one-hour maximum of 4470.7 mmBtu/hour. Particulate matter emissions are currently controlled by a pulse jet fabric-filter baghouse.

Alma 4 and Alma 5 are Riley pulverized coal wall-fired, dry bottom boilers that began operation in 1957 and 1960, respectively. A typical 70% bituminous/30% subbituminous coal blend is the primary fuel, with distillate oil used for unit startup and flame stabilization. The Alma 4 boiler has a heat input based on the most recent Uniform Rating of Generation Equipment test of 556.1 mmBtu/hour. The Alma 5 boiler has a heat input based on the most recent Uniform Rating of Generation Equipment test of 809.0 mmBtu/hour. Particulate matter emissions are currently controlled using electrostatic precipitators. As part of the DSI project, the ESPs will be replaced with a fabric filter baghouse system.

In a clean-air settlement announced in June 2012 with the U.S. Environmental Protection Agency and the Sierra Club, Dairyland agreed to limits in emission rates and total annual amounts emitted for SO2, NOx and particulates for JPM, Genoa Unit 3 and Alma Units 4-5. Dairyland also agreed to install SCR or equivalent alternative NOx technology at JPM and selective non-catalytic reduction (SNCR) at Genoa Unit 3. Dairyland also notified EPA that it will install DSI to further reduce SO2 emissions at JPM. Additional emission controls will also be installed on Alma Units 4-5. As part of the agreement, Dairyland’s Alma Units 1-3 ceased burning coal as of Dec. 31, 2011.

The first two units of the station, Alma 1 and 2, were constructed in 1947. Together, they generated 40 MW. Alma 3 was built in 1950 and Alma 4 in 1957. The largest and final unit of the Alma Station, Alma 5, came on-line in 1960 at 80 MW. The single-unit JPM station next door has a generating capacity of about 400 MW.

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.