(132c) The Pco Process for Photochemical Removal of Mercury from Flue Gas

The National Energy Technology Laboratory has developed several promising techniques to capture and remove elemental mercury from flue gases. Powerspan Corp. has licensed one of these technologies for application to coal-derived flue gases, and has initiated a bench and pilot test program to develop the Photochemical Oxidation, or PCO Process for commercial application with subbituminous and lignite fuels.

The PCO Process has the potential to serve as a low cost mercury oxidation technology that will facilitate the removal of elemental mercury within a downstream SO2 scrubber, wet electrostatic precipitator (WESP), or baghouse. The technique employs 254-nanometer (nm) ultraviolet light to produce an excited state mercury species in the flue gas, leading to oxidation of elemental mercury. Testing conducted in Powerspan's laboratories showed greater than 90% oxidation and removal of elemental mercury from a realistic simulated subbituminous flue gas stream at bench-scale. The parasitic power requirements are small and estimated to be less than 0.5%. Pilot-scale testing of the PCO Process is planned to begin soon.