Development of a Process for Combined Removal of Mercury and Nitrogen Oxides from Flue Gas

摘要

Emissions of mercury (Hg) from coal- fired power plants may soon be subject to regulation andnitrogen oxides (Nox) are already an important control issue. In both cases, significant portionsof the emissions consist of species (elemental mercury, Hg~0, and nitric oxide, NO) that arerelatively insoluble and therefore difficult to remove in a wet scrubber. Previous laboratoryresearch at Argonne established that a chemical oxidizing agent (NOXSORB?) could convertHg0 and NO to more readily soluble forms. The oxidation products from these reactions canthen be removed downstream of the reaction zone in an aqueous scrubber. Currently, we areusing the laboratory results to develop a press design for combined Hg/NO_x removal in a wetflue-gas desulfurization system. By September, we will have completed additional laboratorystudies of important press conditions and will have designed a pilot-scale test program toestablish the press potential at an industrial scale with coal-combustion flue gas. In this paper,we will present the press concept, the initial design for the test program, and laboratory resultsrelevant to the press. These results are expected to include removal performance withdifferent scrubbing chemistries, the effects of flue- gas composition, information on the importantreaction mechanisms, and the fate of the various oxidation reaction products.