Mercury and acid gas control in utility baghouses through sorbent injection -- Pilot-scale demonstration

The mercury concentration in utility flue gas is in the range of 0.1 to 1.0 part per billion. EPA and state agencies are assessing whether such low concentrations of mercury emissions from coal-fired utilities pose a significant health risk and whether mercury regulations would be necessary or appropriate. In anticipation of regulations that would impose control on mercury emissions, Public Service Electric and Gas Company (PSE and G) has joined with the Electric Power Research Institute (EPRI) to evaluate carbon-based sorbents for mercury control at one of PSE and G's coal-fired power plants. While active carbon is currently injected into municipal solid-waste combustor (MWC) flue gas streams to reduce vapor phase mercury concentrations, this technique has not been rigorously tested on flue gas from coal-fired utility boilers. Due to the difference in flue gas composition and the low mercury concentrations present in utility flue gas, this technology is not directly transferable to utility applications. With new ambient standards for particulate matter and ozone in the future and inclusion of utilities in the Toxics Release Inventory, additional evaluations were conducted to determine the effectiveness of injecting calcium and sodium based sorbents upstream of a baghouse to control acid gas emissions (SO{submore » 2}, SO{sub 3} and HCl). Testing of sorbent injection technology is currently underway on a slipstream of flue gas from Hudson Unit 2 located in Jersey City, New Jersey. The unit is a dry-bottom, supercritical once-through design firing a low sulfur bituminous coal. The test facility (pilot) is based on a 4,000-acfm COHPAC baghouse. This paper describes the results of pilot testing of activated carbon and calcium/sodium sorbents injection technology for mercury and acid gas control.« less