The Orlando Utilities Commission has been approved by the Florida Department of Environmental Protection to install and operate a calcium bromide (CaBr2) and activated carbon injection demonstration project at the Stanton Energy Center.
This project is to explore mercury mitigation measures by activated carbon injection testing and CaBr2 spray application to the coal to reduce emission of mercury to meet the federal Mercury and Air Toxics Standards (MATS), which take effect in April 2015. The proposed demonstration project duration is expected to be 90 non-consecutive operational days, the agency said in a March 27 approval document.
The technology will consist of powdered activated carbon (PAC) that will be injected in the flue gas downstream of the air preheater in Stanton Unit 1 using the existing dry sorbent injection ports. In the flue gas duct, the injected carbon acts as a surface catalyst to convert the elemental mercury to oxidized mercury. The carbon particles are captured mostly by the electrostatic precipitator (ESP). The remaining carbon particles are removed in the wet flue gas desulfurization system.
Equipment will consist of a blower conveying PAC from bulk bags through injection lances into the boiler, ESPs or ductwork. The proposed sorbent injection system will utilize bulk bags (900 to 1,000 pounds each). These bulk bags will be sealed to a day hopper on a gravimetric feeder and then be discharged directly into the boiler, ESPs or ductwork. There is no bulk material transfer or bin vents with the proposed PAC injection system. Therefore, there is no emission point or vented emissions from the proposed PAC storage system.
The Stanton Energy Center is a nominal 1,876-MW facility. It includes two fossil fuel fired boiler generating units (Units 1 and 2), and two combined cycle combustion turbine-electrical generators (Units A and B).
Units 1 and 2 fire coal and No. 6 fuel oil and have a combined output of 936 MW. Unit A fires pipeline natural gas and diesel and has a total nominal capacity of 640 MW and will achieve approximately 700 MW during extreme winter peaking conditions. Unit B fires pipeline natural gas and has a design capacity of 300 MW.
Units 1 and 2 have the following control equipment: NOX emissions are controlled by low NOX burners, overfire air system and selective catalytic reduction; particulate matter emissions are controlled by dry electrostatic precipitator; and SO2 emissions are controlled by wet flue gas desulfurization. Unit 1 began operation in 1987 and Unit 2 began operation in 1996. A dry sorbent injection system was recently installed that is used to inject hydrated lime into the exhaust gas ductwork upstream of the ESP to minimize SO3 formation and ultimately to control sulfuric acid emissions.