The Indiana Office of Air Quality (OAQ) on Feb. 20 granted Indiana Michigan Power a final approval on air permit changes, including a change covering a new selective catalytic reduction (SCR) system on one of the two units at the Rockport coal plant.
The SCR, needed for NOx control, would be installed on Unit 1, with the project also including associated anhydrous ammonia handling equipment. In addition, revisions were made to the Title V permit to better represent the actual operating conditions being observed on the Station 8 baghouse than what is currently shown in the Title V Permit, and to add the applicability and operating limits necessary for compliance with the limited use provisions of the Industrial Boiler MACT Rule that will apply to the two auxiliary boilers at Rockport.
Unti 1 consists of a pulverized coal opposed wall fired dry bottom boiler, identified as MB1 (Main Boiler 1), with construction commenced in 1977 and completed in 1984, with a design heat input capacity of 12,374 million Btu per hour, with an electrostatic precipitator (ESP) system for control of particulate matter. Low NOX burners, and an overfire air (OFA) system have been installed and SCR now permitted for NOx control. No. 2 fuel oil is fired during startup, shutdown, and load stabilization periods. No. 2 fuel oil may also be burned to maintain boiler temperature to ensure boiler availability on short notice, and to maintain boiler temperature required during chemical cleaning. One powdered activated carbon (PAC) injection system permitted in 2008, 2010 and 2013, with a unit maximum capacity of injecting 4,000 pounds of halogenated or non-halogenated activated carbon per hour into the exhaust ductwork for Boiler 1 from a dedicated silo(s). One dry sorbent injection (DSI) system was permitted in 2013, with a design injection capacity of 20,000 pounds of Sodium Bicarbonate per hour into the exhaust ductwork for Boiler 1.
The SCR, under a consent decree with the federal government, needs to be installed on Unit 1 by Dec. 31, 2017, which will allow the unit to operate after that date. Approval for this SCR project is still pending at the Indiana Utility Regulatory Commission.
Rockport, located in Spencer County, Indiana, consists of two 1,300-MW coal-fired units. SO2 emissions at Rockport are limited by the New Source Performance Standard to 1.2 lbs SO2/MMBtu. Compliance with the emission limit is achieved by using a blend consisting primarily of low-sulfur subbituminous coal. The coal supply for Rockport currently uses a blend of Powder River Basin (PRB) coal from Wyoming and low-sulfur bituminous coal from eastern sources. In order to comply with stricter U.S. Environmental Protection Agency emissions standards, Dry Sorbent Injection (DSI) technology will be used at both Rockport units.
Rockport Unit 2’s new DSI technology began operating in December 2014. Installation of new DSI technology is currently underway at Rockport Unit 1 and is expected to be operational by May 2015. The new DSI technology is not expected to change the current coal blend at Rockport, this American Electric Power (NYSE: AEP) subsidiary noted in a Jan. 29 fuel report filed at the Indiana Utility Regulatory Commission.