The Wisconsin Department of Natural Resources is taking public comment until Feb. 15 on a draft air construction permit that would allow activated carbon injection and selective non-catalytic reduction installations at the coal-fired Genoa plant of Dairyland Power Cooperative.
A selective non-catalytic reduction system (SNCR) is proposed to be installed to control NOx and an activated carbon injection (ACI) system to control mercury emissions. Construction is planned to start in March 2014, with the new systems operating in the fall 2014, said the September 2013 Dairyland application for this permit. This plant already has dry flue gas desulfurization for SO2 control and pulse jet fabric filters for particulates.
The Genoa plant consists of one-pulverized coal main steam boiler. Coal for this boiler is delivered by barge. There are also three #2 distillate oil-fired boilers onsite – an auxiliary boiler used for main steam boiler startup, coal mill inerting and space heating, a boiler used for heating in a building, and a hot water/glycol boiler used for providing heated makeup air for the coal handling system. This single-unit coal-fired-facility has a generating capacity of 378 MW.
Boiler B20 began operation in 1968 and currently burns subbituminous coal as the primary fuel, with distillate oil used for unit startup and flame stabilization. The U.S. Energy Information Administration database shows Genoa getting coal in 2013 from Peabody Energy‘s (NYSE: BTU) North Antelope Rochelle and Arch Coal‘s (NYSE: ACI) Black Thunder mines, both in the Wyoming end of the Powder River Basin.
The ACI system is proposed for control of mercury emissions from the flue gas of boiler B20. Estimated mercury emission reductions will be approximately 90% from the mercury input to the boiler. The installation is being proposed for the purpose of complying with the requirements of the U.S. Environmental Protection Agency’s Mercury and Air Toxics Standards (MATS), due to take initial effect in April 2015.
Activated carbon will be delivered by pneumatic trailers and initially stored on site in a silo with a working capacity of 100,000 pounds of carbon. Each truck will drop carbon directly into the silo, which will have a passive bin vent on the top of the silo to control dust. A pressure blower system will transport the carbon into the boiler duct, entering the existing dry flue gas desulfurization system.
The SNCR involves injecting a reagent into the furnace in order to reduce NOx emissions. The system will use urea and water, which will be vaporized in the furnace, reacting to produce ammonia, which will then react with the NOX to form N2 and H2O. Ammonia slip is expected to be less than 10 ppm.