The Oklahoma Department of Environmental Quality went out for comment on Jan. 17 on an air permit change covering new air emissions controls for a coal-fired unit at Public Service Co. of Oklahoma’s Northeastern power plant.
An operating permit application to install activated carbon injection, dry sorbent injection and a fabric filter on Unit #3 is currently under review, said a DEQ notice. This so-called “M-5 permit” will provide for compliance with the Mercury and Air Toxics Standards (MATS). Public Service Co. of Oklahoma is a unit of American Electric Power (NYSE: AEP).
Unit 1 was repowered years ago, the DEQ noted. The boiler powering the steam turbine was replaced by two 160-MWe combined cycle gas turbines with heat recovery steam generators (HRSGs). Steam generated by the heat from the turbines and HRSGs re-powers the Unit 1 steam turbine, which was not removed when the original boiler was removed. The boiler providing steam to Unit 2 is 100% gas-fueled. An M-6 prevention of significant deterioration (PSD) modification authorizes installation of low-NOX burners and overfire air (LNB/OFA) on Unit 2.
The boilers providing steam for Units 3 and 4 are primarily coal-fired, with natural gas, #2 fuel oil, and co-firing of coal and natural gas as secondary fuels. The utility has added low-NOX concentric firing systems consisting of low-NOX burners (LNB) and separated overfire air (SOFA) to Units 3 and 4 in advance of EPA’s Cross-State Air Pollution Rule (CSAPR).
The pollution control project covered by application M-5 will add two injection systems to control emissions of mercury, SO2 and acid gasses, as well as a baghouse that will control PM emissions from the two injection systems and add a second level of control on existing PM emissions, all at Unit 3.
The M-5 project involves addition of an activated carbon injection (ACI) system to control mercury in the flue gas of Unit 3, as well as addition of a dry sorbent injection (DSI) system to control acid gasses and SO2 in the flue gas. Both systems will be added downstream of the electrostatic precipitator (ESP). A fabric filter baghouse (FF) will be added downstream of the ACI and DSI to capture particulate emissions from the treated flue gas stream. The DSI system involves sodium bicarbonate (SBC), which is delivered by differential pressure from trucks or rail cars to two storage silos.
The SBC injection rate is expected to be a nominal 5,250 lb/hr, but depends on system variables. The ACI injection rate is expected to be a nominal 250 lb/hr, but also depends on system variables. Material captured from the fabric filter is referred to as byproduct, and will be sent pneumatically to a byproduct storage silo. Byproduct is mixed with flyash and water to reduce dust emissions when loaded onto trucks for hauling to the landfill. Dry byproduct may also be loaded to the truck by a sealed system that sends displaced air to the silo.
The Babcock & Wilcox Co. (NYSE: BWC) said Jan. 21 that subsidiary Babcock & Wilcox Power Generation Group (B&W PGG) has been awarded contracts totaling more than $40m for emissions control equipment at two AEP coal-fired plants in Oklahoma and Texas. Under the contracts, B&W PGG will engineer and supply a fabric filter for particulate emissions control for Northeastern Unit 3. Material delivery for Northeastern Unit 3 is scheduled for mid-2014, B&W noted.
In September 2012, PSO filed an environmental compliance plan with the Oklahoma Corporation Commission reflecting the retirement of Northeastern Unit 4 (470 MW) in 2016 and additional environmental controls on Unit 3 to continue operations through 2026. Units 1 and 2 at Northeastern are gas-fired facilities with a combined capacity of 852 MW, while Units 3 and 4 are coal-fired and have a combined 930 MW.