Patent ID: 6981456
Filing Date: 2006-01-03
Classification: B01D,F23C,F23J

Abstract:
1. A method to reduce mercury in gas emissions from the combustion of coal in a combustion unit, said method comprising: a. combusting coal in a primary combustion zone of the combustion unit under conditions of low or no excess oxygen during combustion in the zone wherein the excess oxygen in the combustion zone is no greater than two percent (2%); b. generating carbon rich fly ash during combustion and entraining the fly ash into flue gas generated by the combustion; c. releasing mercury during the combustion into the flue gas; d. staging combustion air by injecting combustion air in a post-combustion zone downstream of the combustion zone in the combustion unit; e. adsorbing the released mercury with the carbon rich fly ash generated during combustion; f. collecting the fly ash with the adsorbed mercury in a combustion waste treatment system, wherein the fly ash remains in the flue gas from combustion to collection and is permanently removed from the flue gas upon collection, wherein the combustion waste treatment system includes a particle control device which captures the fly ash with adsorbed mercury and discharges the captured fly ash to a fly ash collection unit; and g. exhausting the flue gases after adsorbing the released mercury to reduce mercury in the flue gases to be exhausted.