Patent ID: 7867462

Claim:
A method for controlling emissions of a coal-fired furnace with ammonia recovery and fly ash beneficiation, the method comprising: introducing ammonia to react at a temperature of from about 600° F. to 750° F. with at least a portion of nitrogen oxides and sulfur oxides in the exhaust emission; introducing ammonia to react at a temperature of from about 275° F. to 300° F. with at least a portion of sulfur trioxides in the exhaust emission and produce at least one or more ammoniated compounds; precipitating at least a portion of fly ash particles and the ammoniated compounds in the exhaust emission; beneficiating in a first vessel at least the precipitated fly ash particles by reducing carbon content of the precipitated fly ash particles to a level of less than about 6% carbon to produce hot beneficiated fly ash particles; mixing in a second vessel at least a portion of the hot beneficiated fly ash particles with the precipitated ammoniated compounds such that the mixture is at a temperature of from about 500° F. to 842° F. to recover at least a portion of the ammonia; and reusing the recovered ammonia in the introducing ammonia steps to react with at least a portion of the nitrogen oxides and sulfur trioxides.