Patent ID: 6375909
Filing Date: 2002-04-23
Classification: B01D,F23G,F23J,Y02C

Abstract:
A process for removing Hg and NOx from combustion flue gas generated by combustion of carbonaceous material comprising:a) providing said carbonaceous material and at least one additive compound selected from the group consisting of alkali earth metal, chlorine, and mixtures thereof, to a combustor to facilitate formation in situ of HCl acid and MO or M(OH)2 in the flue gas generated by the combustor; b) generating excess MO and M(OH)2 in the combustor to increase alkalinity and pH; c) converting gaseous Hg and HCl into HgCl2 by cooling Hg and HCl containing flue gas; d) converting gaseous NO and MO or M(OH)2 into a more soluble form of nitrogen oxides; e) quenching the HgCl2 and the NOx containing flue gas to about 70-90Â° C.; f) separating Hg in the form of HgCl2 and the soluble form of nitrogen oxides with a majority of ash generated by the combustor from the flue gas; g) cooling the flue gas in the presence of water to about 45-50Â° C.; h) removing residual HgCl2 and remaining soluble nitrogen oxides from the flue gas; i) condensing fugitive elemental Hg by contacting the flue gas with further cooling fluid to reduce flue gas temperature to substantially ambient temperature or lower; and j) separating condensed fugitive elemental Hg from the flue gas.