We will present a paper on our mercury control work at the Power Plant Air Pollutant Control “MEGA” Symposium, August 30 – September 2, 2010 in Baltimore MD.
Mercury Abatement By Existing Pollutant Control Equipment At Multiple Coal-fired Power Plants by J. O. Allen, Allen Analytics LLC, Tucson, AZ; R. Chang, Electric Power Research Institute, Palo Alto, CA; C. A. Tyree, Southern Company, Birmingham, AL.
Production coal-fired power plant data were analyzed in order to evaluate the effectiveness of existing pollution control equipment (SCR-ESP-FGD) for the control mercury emissions. More than five plant-years of process and emissions data were collected into a large data set. Mercury emissions were calculated in lb/TBtu using EPA methods. Mercury control efficiencies were 90% or greater on 50% of the study days. Lower collection efficiencies were observed when 1) load was near capacity, 2) SCR units were off-line, 3) FGD units were started up or shut down, and 4) mercury was re-emitted from FGD liquor. These results are consistent with mercury oxidation in SCR units and elsewhere, followed by collection and sequestration of oxidized mercury in FGD liquor. Consistent collection efficiencies of at least 90% will likely require additional process controls based on improved understanding of mercury oxidation and sequestration chemistries.