AEP gets final air permit for Rockport SO2 control systems

The Indiana Department of Environmental Management on Aug. 27 approved an air permit change that would allow Indiana Michigan Power to install new air emissions controls on the two, 1,300-MW coal units at the Rockport power plant.

The approval covers construction of new Dry Sorbent Injection (DSI) systems for Units 1 and 2, the replacement of the Unit 1 Ash silo Bin Vent Filters, separator strings, and Unit 2 Separator Strings on three of the four silos, along with modifications to the design and operation of the existing landfill to dispose of the additional combustion waste generated by the DSI systems and changes to the ACI systems and the changes in the classification of the material being disposed.

As part a modification of New Source Review (NSR) Consent Decree, signed by the U.S. District Court for the Southern District of Ohio on May 14, Indiana Michigan Power has accepted federally enforceable limitations on annual SO2 emissions from the Rockport Plant main boilers.

Indiana Michigan Power is a unit of American Electric Power (NYSE: AEP) and Rockport fies Powder River Basin coal. The modified NSR deal, among other things, allows AEP to install these cheaper controls on the two Rockport coal units, instead of more costly flue gas desulfurization on one unit.

The new controls are:

  • Unit 1 Dry Sorbent Injection System, permitted in 2013, identified as (DSI-U1), consisting storage silos, pneumatic truck unloading stations and associated equipment, injection metering system that includes three metering feeders directly fed from each storage silo, blowers, and piping necessary to inject up to 10 tons per hour of sodium bicarbonate into the ductwork upstream of the electrostatic precipitators (ESPs) on each unit.
  • Unit 2 Dry Sorbent Injection System, permitted in 2013, identified as (DSI-U2), consisting storage silos, pneumatic truck unloading stations and associated equipment, injection metering system that includes three metering feeders directly fed from each storage silo, blowers, and piping necessary to inject up to 10 tons per hour of sodium bicarbonate into the ductwork upstream of the ESPs on each unit.
  • Modification of the existing Activated Carbon Injection (ACI) System on Units 1 and 2. This modification includes the replacement of the existing PAC feeder to increase the maximum feed rate of PAC to 4000 lbs/hr from the current maximum equipment rating of 1750 lbs/hr. In addition the PAC being used will be switched from a non-halogenated PAC to a halogenated PAC. Two additional 360 ton capacity silos will also be added to the system.
  • Modification of the design and operation of the existing landfill to dispose of the additional combustion waste generated by the DSI systems and changes to the ACI systems.

The affected units are:

  • One 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 ESP system for control of particulates. Low NOX burners and an overfire air (OFA) system have been installed for NOX control. One powdered activated carbon (PAC) injection system, identified as ACI, 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 (MB1) from a dedicated silo(s). One dry sorbent injection (DSI) system, identified as DSI-U1, permitted in 2013, with a design injection capacity of 20,000 pounds of sodium bicarbonate per hour into the exhaust ductwork for Boilers 1 (MB1). Emissions from Units MB1 and MB2 are exhausted through the common stack, Stack CS012.
  • One pulverized coal opposed wall fired dry bottom boiler, identified as MB2 (Main Boiler 2), with construction commenced in 1977 and completed in 1989, with a design heat input capacity of 12,374 million Btu per hour, with an ESP system for control of particulate matter. Low NOX burners and OFA have been installed for NOX control. One PAC injection system, identified as ACI, 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 2 (MB2) from a dedicated silo(s). One DSI system, identified as DSI-U2, permitted in 2013, with a combined maximum capacity of injecting 20,000 pounds of sodium bicarbonate per hour into the exhaust ductwork for Boilers 1 (MB2).
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.